Expect root-relative pagination links from ansible virtuals

A GitHub release scan that hit a transient asset error still saved the release-list ETag, so the failed asset was never retried. Assets that are corrupt, deleted or truncated upstream fail on every retry, so they must not keep the remote failed.

- fail the rpm/deb/alpine scan on transient asset fetch, short read or metadata insert errors, so the ETag is not saved and the backoff retry re-derives the asset
- add `provider.ErrInvalidPackage` for unparseable packages and 404/410/416 asset downloads; such assets are logged and skipped
- decide a ranged fetch holds the whole object from Content-Length or the Content-Range total, or a clean EOF when the total is unknown
- add a NOT VALID cascading FK from the GitHub sync-state tables to `remotes`

Reviewed-on: #135
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

README.md

@@ -27,11 +27,12 @@ Classification precedence, TTLs and eviction for every remote: [docs/common/cach
 Each type's paths, Terraform examples and local/virtual behaviour are in `docs/<type>/`:
 
 - `alpine`: [remote](docs/alpine/remote.md), [remote-github](docs/alpine/remote-github.md)
+- `ansible`: [remote](docs/ansible/remote.md), [local](docs/ansible/local.md), [virtual](docs/ansible/virtual.md)
 - `cargo`: [remote](docs/cargo/remote.md)
 - `deb`: [remote](docs/deb/remote.md), [remote-github](docs/deb/remote-github.md)
 - `docker`: [remote](docs/docker/remote.md), [local](docs/docker/local.md)
 - `generic`: [remote](docs/generic/remote.md)
-- `gems`: [remote](docs/gems/remote.md)
+- `gems`: [remote](docs/gems/remote.md), [local](docs/gems/local.md), [virtual](docs/gems/virtual.md)
 - `goproxy`: [remote](docs/goproxy/remote.md)
 - `helm`: [remote](docs/helm/remote.md), [local](docs/helm/local.md), [virtual](docs/helm/virtual.md)
 - `npm`: [remote](docs/npm/remote.md), [local](docs/npm/local.md), [virtual](docs/npm/virtual.md)
@@ -131,6 +132,7 @@ No patterns + no blocklist = open proxy. Provider handles mutability classificat
 GET /api/v1/remote/{name}/{path}     Proxy/cache artifact
 GET /api/v1/virtual/{name}/{path}    Virtual repo (merged index)
 PUT /api/v1/local/{name}/{package}   npm publish (local npm repos)
+POST/DELETE /api/v1/local/{name}/api/v1/gems[/yank]   gem push / yank (local gems repos)
 GET /v2/{name}/{path}                Docker Registry v2
 ```
 

docs/ansible/local.md

@@ -0,0 +1,26 @@
+# Local ansible repository
+
+A local `ansible` repo is a Galaxy v3 server: `ansible-galaxy collection publish`
+and `ansible-galaxy collection install` work against `/api/v1/local/<repo>`.
+`publish` needs an API key; any value works.
+
+```bash
+ansible-galaxy collection build
+ansible-galaxy collection publish unkin-hello-1.0.0.tar.gz \
+  --server https://artifactapi.example.com/api/v1/local/<repo>/ --api-key unused
+ansible-galaxy collection install unkin.hello \
+  --server https://artifactapi.example.com/api/v1/local/<repo>/
+```
+
+Publishing reads `collection_info` from the tarball's `MANIFEST.json` and
+finishes the import synchronously, so the import task is already `completed`.
+Uploads over 256 MiB, tarballs with members or symlinks escaping the collection root, or
+with an invalid name, version or dependency map are rejected with 400.
+
+The repo serves `api/v3/collections/<ns>/<name>/`, the paginated
+`versions/` list (`limit` up to 100, `offset`), `versions/<version>/` with
+`download_url`, `artifact.sha256` and `metadata.dependencies`, and
+`artifacts/<ns>-<name>-<version>.tar.gz`.
+
+Versions are immutable: publishing an existing `namespace.name:version` is
+rejected with 409.

docs/ansible/remote.md

@@ -0,0 +1,11 @@
+# `ansible` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `ansible` | Galaxy `api/` JSON (links rewritten, `limit`/`offset` forwarded) | `artifacts/*.tar.gz` |
+
+```bash
+ansible-galaxy collection install community.general -s https://artifactapi.example/api/v1/remote/galaxy/api/
+```

docs/ansible/virtual.md

@@ -0,0 +1,28 @@
+# `ansible` virtual
+
+An ansible virtual serves one Galaxy v3 API over local and remote ansible
+members: `ansible-galaxy collection install` works against
+`/api/v1/virtual/<name>/`.
+
+- `versions/` concatenates member version lists in member order; on a
+  duplicate version the earlier member wins. Pagination (`limit` up to 100,
+  `offset`) runs over the merged list.
+- `versions/<version>/` is the owning member's detail with `href` and
+  `download_url` pointing at the virtual; the download 302s to that member.
+- A member error fails the request with 502; a member without the collection
+  is skipped. Merges are cached for 60s.
+
+```hcl
+resource "artifactapi_virtual" "ansible" {
+  name         = "ansible"
+  package_type = "ansible"
+  members      = [artifactapi_local_ansible.internal.name, artifactapi_remote_ansible.galaxy.name]
+}
+```
+
+```bash
+ansible-galaxy collection install unkin.hello community.general \
+  --server https://artifactapi.example.com/api/v1/virtual/ansible/
+```
+
+Publish to the local member directly; the virtual is read-only.

docs/common/caching.md

@@ -93,7 +93,7 @@ Force a moving path mutable, e.g. branch tarballs on `generic`:
 ## Built-in classification per type
 
 Each type's page lists its auto-detected mutable and immutable paths:
-[alpine](../alpine/remote.md), [alpine github](../alpine/remote-github.md),
+[alpine](../alpine/remote.md), [alpine github](../alpine/remote-github.md), [ansible](../ansible/remote.md),
 [cargo](../cargo/remote.md), [deb](../deb/remote.md), [deb github](../deb/remote-github.md),
 [docker](../docker/remote.md), [generic](../generic/remote.md), [gems](../gems/remote.md), [goproxy](../goproxy/remote.md),
 [helm](../helm/remote.md), [npm](../npm/remote.md), [nuget](../nuget/remote.md),

docs/gems/local.md

@@ -0,0 +1,24 @@
+# Local gems repository
+
+A local `gems` repo is a RubyGems source: `gem push`, `gem yank`, `gem install`
+and `bundle install` work against `/api/v1/local/<repo>`. `gem push` needs an
+API key; any value works.
+
+```bash
+GEM_HOST_API_KEY=unused gem push --host https://artifactapi.example.com/api/v1/local/<repo> mygem-1.0.0.gem
+gem install mygem --source https://artifactapi.example.com/api/v1/local/<repo>/
+gem yank mygem -v 1.0.0 --host https://artifactapi.example.com/api/v1/local/<repo>
+```
+
+```ruby
+# Gemfile
+source "https://artifactapi.example.com/api/v1/local/<repo>/"
+gem "mygem"
+```
+
+The repo serves the compact index (`versions`, `info/<gem>`, `names`), `gems/*.gem`
+and `quick/Marshal.4.8/*.gemspec.rz`. The legacy `specs.4.8.gz` indexes are not
+served; current gem and bundler clients use the compact index.
+
+Versions are immutable: pushing an existing name-version-platform is rejected
+with 409. A yanked version disappears from the index and its files are removed.

docs/gems/virtual.md

@@ -0,0 +1,28 @@
+# `gems` virtual
+
+A gems virtual serves one RubyGems source over local and remote gems members:
+`gem install` and `bundle install` work against `/api/v1/virtual/<name>/`.
+
+- `info/<gem>` is the union of member lines; on a duplicate version-platform
+  the earlier member wins. A gem only one member has is served verbatim.
+- `versions` regenerates the line (and md5) of every gem several members list
+  from its merged `info`; other gems' lines pass through. `names` is the union.
+- `gems/*.gem` and `quick/Marshal.4.8/*.gemspec.rz` 302 to the member whose
+  `info` line won.
+- A member error fails the request with 502; a member without the gem is
+  skipped. Merges are cached for 60s.
+
+```hcl
+resource "artifactapi_virtual" "gems" {
+  name         = "gems"
+  package_type = "gems"
+  members      = [artifactapi_local_gems.internal.name, artifactapi_remote_gems.rubygems.name]
+}
+```
+
+```ruby
+# Gemfile
+source "https://artifactapi.example.com/api/v1/virtual/gems/"
+```
+
+Push to the local member directly; the virtual is read-only.

e2e-docker/README.md

@@ -29,10 +29,16 @@ already-running stack.
   generic (upload/download), pypi (wheel + generated `simple/`
   index), rpm (real package + **automatic repodata** generation), npm (stock
   `node:22` client: `npm publish` unscoped + scoped, `npm install` + `require()`,
-  second version, republish rejected).
+  second version, republish rejected), gems (stock `ruby:3.3`: `gem push`,
+  `gem install`, `bundle install` + `require`, republish rejected, `gem yank`,
+  yanked re-push rejected), ansible (stock `ansible-galaxy`: `collection build`,
+  `publish`, republish rejected, `install` + module run).
 - **Virtual repositories** — pypi simple-index merge and helm `index.yaml` merge
   across two members; npm packument merge over two locals via a stock `node:22`
-  client (merged versions, install through the member redirect).
+  client (merged versions, install through the member redirect); gems compact
+  index merge over two locals via stock `ruby:3.3` bundler (member order wins,
+  downloads 302 to the owning member); ansible over two locals via stock
+  `ansible-galaxy` (install through the virtual, download 302 to the owner).
 - **Mirrorlist** — an rpm remote with a `mirrorlist` of extra upstream mirrors
   (pool = `base_url` + `mirrorlist`): round-robin distribution across both mirrors
   (constant-body `mockupstreama` / `mockupstreamb`), failover past a dead primary,

e2e-docker/ansible_local_test.go

@@ -0,0 +1,66 @@
+//go:build dockere2e
+
+package e2edocker
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+// ansibleHelloScript builds unkin.e2e_hello 1.0.0 with one module into /w/dist.
+const ansibleHelloScript = `pip install -q ansible-core >/dev/null 2>&1
+mkdir -p /w && cd /w && ansible-galaxy collection init unkin.e2e_hello >/dev/null
+cd unkin/e2e_hello && sed -i 's/^version: .*/version: 1.0.0/' galaxy.yml && mkdir -p plugins/modules
+printf '%s\n' 'DOCUMENTATION = r"""' 'module: hello' 'short_description: e2e greeting' 'description: Returns a greeting.' 'options:' '  name: {type: str, default: world, description: Who to greet.}' '"""' \
+  'from ansible.module_utils.basic import AnsibleModule' \
+  'm = AnsibleModule(argument_spec=dict(name=dict(type="str", default="world")))' \
+  'm.exit_json(changed=False, msg="hello " + m.params["name"])' > plugins/modules/hello.py
+ansible-galaxy collection build --output-path /w/dist >/dev/null
+`
+
+// ansibleHelloPlay runs unkin.e2e_hello.hello from collections in /w/coll.
+const ansibleHelloPlay = `export ANSIBLE_COLLECTIONS_PATH=/w/coll
+ansible-doc unkin.e2e_hello.hello | grep -q 'Returns a greeting'
+printf -- '- hosts: localhost\n  gather_facts: false\n  tasks:\n    - unkin.e2e_hello.hello: {name: e2e}\n      register: r\n    - debug: {msg: "PLAY {{ r.msg }}"}\n' > /w/play.yml
+ansible-playbook -i localhost, -c local /w/play.yml | grep -o 'PLAY hello e2e' | head -1
+`
+
+// TestLocalAnsiblePublishInstall builds a collection with a stock
+// ansible-galaxy client, publishes it to a local ansible repo, rejects the
+// republish, installs it back and runs its module.
+func TestLocalAnsiblePublishInstall(t *testing.T) {
+	network := os.Getenv("COMPOSE_NETWORK")
+	internal := os.Getenv("ARTIFACTAPI_INTERNAL")
+	if network == "" || internal == "" {
+		t.Skip("COMPOSE_NETWORK/ARTIFACTAPI_INTERNAL not set; run via scripts/docker-e2e.sh")
+	}
+	if _, err := exec.LookPath("docker"); err != nil {
+		t.Skip("docker not available on the test host")
+	}
+
+	name := fmt.Sprintf("e2e-ansible-local-%d", time.Now().UnixNano())
+	createRepo(t, fmt.Sprintf(`{"name":%q,"package_type":"ansible","repo_type":"local"}`, name))
+	defer deleteRepo(t, name)
+
+	script := "set -euo pipefail\n" + ansibleHelloScript + `
+ansible-galaxy collection publish /w/dist/unkin-e2e_hello-1.0.0.tar.gz --server "$SRV" --api-key unused
+if ansible-galaxy collection publish /w/dist/unkin-e2e_hello-1.0.0.tar.gz --server "$SRV" --api-key unused; then echo "republish accepted"; exit 1; fi
+ansible-galaxy collection install unkin.e2e_hello:==1.0.0 --server "$SRV" -p /w/coll
+` + ansibleHelloPlay
+
+	srv := strings.TrimRight(internal, "/") + "/api/v1/local/" + name + "/"
+	out, err := exec.Command("docker", "run", "--rm", "--network", network,
+		"-e", "SRV="+srv, "python:3.12-slim", "bash", "-c", script).CombinedOutput()
+	if err != nil {
+		t.Fatalf("ansible-galaxy client run failed: %v\n%s", err, out)
+	}
+	for _, want := range []string{"successfully published and imported", "HTTP Code: 409", "unkin.e2e_hello:1.0.0 was installed successfully", "PLAY hello e2e"} {
+		if !strings.Contains(string(out), want) {
+			t.Fatalf("missing %q in client output:\n%s", want, out)
+		}
+	}
+}

e2e-docker/ansible_virtual_test.go

@@ -0,0 +1,64 @@
+//go:build dockere2e
+
+package e2edocker
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+// TestVirtualAnsibleInstall publishes a collection to the second of two
+// ansible locals and installs it with stock ansible-galaxy through a virtual
+// over both, the download 302ing to the owning member.
+func TestVirtualAnsibleInstall(t *testing.T) {
+	network := os.Getenv("COMPOSE_NETWORK")
+	internal := os.Getenv("ARTIFACTAPI_INTERNAL")
+	if network == "" || internal == "" {
+		t.Skip("COMPOSE_NETWORK/ARTIFACTAPI_INTERNAL not set; run via scripts/docker-e2e.sh")
+	}
+	if _, err := exec.LookPath("docker"); err != nil {
+		t.Skip("docker not available on the test host")
+	}
+
+	id := time.Now().UnixNano()
+	a, b, virt := fmt.Sprintf("e2e-ansible-a-%d", id), fmt.Sprintf("e2e-ansible-b-%d", id), fmt.Sprintf("e2e-ansible-v-%d", id)
+	for _, name := range []string{a, b} {
+		createRepo(t, fmt.Sprintf(`{"name":%q,"package_type":"ansible","repo_type":"local"}`, name))
+		defer deleteRepo(t, name)
+	}
+	createVirtual(t, fmt.Sprintf(`{"name":%q,"package_type":"ansible","members":[%q,%q]}`, virt, a, b))
+	defer deleteVirtual(t, virt)
+
+	base := strings.TrimRight(internal, "/")
+	script := "set -euo pipefail\n" + ansibleHelloScript + `
+ansible-galaxy collection publish /w/dist/unkin-e2e_hello-1.0.0.tar.gz --server "$BASE/api/v1/local/$B/" --api-key unused
+V="$BASE/api/v1/virtual/$VIRT"
+ansible-galaxy collection install unkin.e2e_hello --server "$V/" -p /w/coll
+DL=$(python3 -c 'import json,sys,urllib.request as u;print(json.load(u.urlopen(sys.argv[1]))["download_url"])' "$V/api/v3/collections/unkin/e2e_hello/versions/1.0.0/")
+echo "REDIRECT $(python3 -c 'import sys,urllib.request as u
+class N(u.HTTPRedirectHandler):
+    def redirect_request(self,*a): return None
+try: u.build_opener(N).open(sys.argv[1])
+except u.HTTPError as e: print(e.code, e.headers["Location"])' "$DL")"
+` + ansibleHelloPlay
+
+	out, err := exec.Command("docker", "run", "--rm", "--network", network,
+		"-e", "BASE="+base, "-e", "B="+b, "-e", "VIRT="+virt,
+		"python:3.12-slim", "bash", "-c", script).CombinedOutput()
+	if err != nil {
+		t.Fatalf("ansible-galaxy client run failed: %v\n%s", err, out)
+	}
+	for _, want := range []string{
+		"unkin.e2e_hello:1.0.0 was installed successfully",
+		"REDIRECT 302 " + base + "/api/v1/local/" + b + "/artifacts/unkin-e2e_hello-1.0.0.tar.gz",
+		"PLAY hello e2e",
+	} {
+		if !strings.Contains(string(out), want) {
+			t.Fatalf("missing %q in client output:\n%s", want, out)
+		}
+	}
+}

e2e-docker/caching_ansible_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"ansible", "galaxy/artifacts/ns-col-1.0.0.tar.gz", "galaxy/artifacts/ns-col-1.0.0.tar.gz"})
+}

e2e-docker/gems_local_test.go

@@ -0,0 +1,67 @@
+//go:build dockere2e
+
+package e2edocker
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+// TestLocalGemsPushInstall drives stock gem and bundler clients against a
+// local gems repo: push two versions, reject a republish, gem install and
+// bundle install the latest via the compact index, then yank it and check a
+// re-push of the yanked version with different bytes is rejected.
+func TestLocalGemsPushInstall(t *testing.T) {
+	network := os.Getenv("COMPOSE_NETWORK")
+	internal := os.Getenv("ARTIFACTAPI_INTERNAL")
+	if network == "" || internal == "" {
+		t.Skip("COMPOSE_NETWORK/ARTIFACTAPI_INTERNAL not set; run via scripts/docker-e2e.sh")
+	}
+	if _, err := exec.LookPath("docker"); err != nil {
+		t.Skip("docker not available on the test host")
+	}
+
+	name := fmt.Sprintf("e2e-gems-local-%d", time.Now().UnixNano())
+	createRepo(t, fmt.Sprintf(`{"name":%q,"package_type":"gems","repo_type":"local"}`, name))
+	defer deleteRepo(t, name)
+
+	src := strings.TrimRight(internal, "/") + "/api/v1/local/" + name
+	script := `set -euo pipefail
+export GEM_HOST_API_KEY=unused
+mk() { d=/w/src-$1${2:+-b}; mkdir -p $d/lib; cd $d
+  echo "module UnkinE2eHello; VERSION = '$1'; end${2:-}" > lib/unkin-e2e-hello.rb
+  printf 'Gem::Specification.new { |s| s.name = "unkin-e2e-hello"; s.version = "%s"; s.summary = "e2e"; s.authors = ["e2e"]; s.files = ["lib/unkin-e2e-hello.rb"] }' "$1" > g.gemspec
+  gem build g.gemspec >/dev/null 2>&1; }
+mk 0.1.0 && gem push --host "$SRC" unkin-e2e-hello-0.1.0.gem
+mk 0.2.0 && gem push --host "$SRC" unkin-e2e-hello-0.2.0.gem
+if gem push --host "$SRC" unkin-e2e-hello-0.2.0.gem; then echo "republish accepted"; exit 1; fi
+mkdir -p /w/app && cd /w/app
+printf -- "---\n:sources:\n- $SRC/\n" > ~/.gemrc
+gem install --no-document unkin-e2e-hello
+ruby -e 'require "unkin-e2e-hello"; puts "GEM #{UnkinE2eHello::VERSION}"'
+gem uninstall -a -x unkin-e2e-hello >/dev/null
+printf 'source "%s/"\ngem "unkin-e2e-hello"\n' "$SRC" > Gemfile
+bundle install
+bundle exec ruby -e 'require "unkin-e2e-hello"; puts "BUNDLE #{UnkinE2eHello::VERSION}"'
+gem yank unkin-e2e-hello -v 0.2.0 --host "$SRC"
+echo "INFO $(curl -s "$SRC/info/unkin-e2e-hello" | cut -d' ' -f1 | tr '\n' ' ')"
+mk 0.2.0 '# changed' && if gem push --host "$SRC" unkin-e2e-hello-0.2.0.gem; then echo "yanked re-push accepted"; exit 1; fi
+cd /w/app && gem uninstall -a -x unkin-e2e-hello >/dev/null
+if gem install --remote --no-document unkin-e2e-hello -v 0.2.0; then echo "yanked version installed"; exit 1; fi
+echo "VERSIONS $(curl -s "$SRC/versions" | grep '^unkin-e2e-hello ' | cut -d' ' -f2)"`
+
+	out, err := exec.Command("docker", "run", "--rm", "--network", network,
+		"-e", "SRC="+src, "ruby:3.3", "bash", "-c", script).CombinedOutput()
+	if err != nil {
+		t.Fatalf("gem client run failed: %v\n%s", err, out)
+	}
+	for _, want := range []string{"GEM 0.2.0", "BUNDLE 0.2.0", "INFO --- 0.1.0 ", "re-pushing a yanked version is not allowed", "VERSIONS 0.1.0\n"} {
+		if !strings.Contains(string(out), want) {
+			t.Fatalf("missing %q in gem output:\n%s", want, out)
+		}
+	}
+}

e2e-docker/gems_virtual_test.go

@@ -0,0 +1,69 @@
+//go:build dockere2e
+
+package e2edocker
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+// TestVirtualGemsInstall pushes to two local gems repos and drives stock
+// bundler through a virtual over both: merged versions, member order winning a
+// duplicate version, and downloads redirected to the owning member.
+func TestVirtualGemsInstall(t *testing.T) {
+	network := os.Getenv("COMPOSE_NETWORK")
+	internal := os.Getenv("ARTIFACTAPI_INTERNAL")
+	if network == "" || internal == "" {
+		t.Skip("COMPOSE_NETWORK/ARTIFACTAPI_INTERNAL not set; run via scripts/docker-e2e.sh")
+	}
+	if _, err := exec.LookPath("docker"); err != nil {
+		t.Skip("docker not available on the test host")
+	}
+
+	id := time.Now().UnixNano()
+	a, b, virt := fmt.Sprintf("e2e-gems-a-%d", id), fmt.Sprintf("e2e-gems-b-%d", id), fmt.Sprintf("e2e-gems-v-%d", id)
+	for _, name := range []string{a, b} {
+		createRepo(t, fmt.Sprintf(`{"name":%q,"package_type":"gems","repo_type":"local"}`, name))
+		defer deleteRepo(t, name)
+	}
+	createVirtual(t, fmt.Sprintf(`{"name":%q,"package_type":"gems","members":[%q,%q]}`, virt, a, b))
+	defer deleteVirtual(t, virt)
+
+	base := strings.TrimRight(internal, "/")
+	script := `set -euo pipefail
+export GEM_HOST_API_KEY=unused
+pub() { d=/w/src-$1-$2; mkdir -p $d/lib; cd $d
+  echo "module UnkinE2eHello; VERSION = '$1:$2'; end" > lib/unkin-e2e-hello.rb
+  printf 'Gem::Specification.new { |s| s.name = "unkin-e2e-hello"; s.version = "%s"; s.summary = "e2e"; s.authors = ["e2e"]; s.files = ["lib/unkin-e2e-hello.rb"] }' "$2" > g.gemspec
+  gem build g.gemspec >/dev/null 2>&1; gem push --host "$BASE/api/v1/local/$1" unkin-e2e-hello-$2.gem; }
+pub "$A" 0.1.0
+pub "$B" 0.1.0
+pub "$B" 0.2.0
+V="$BASE/api/v1/virtual/$V"
+echo "VERSIONS $(curl -s "$V/versions" | grep '^unkin-e2e-hello ' | cut -d' ' -f2)"
+mkdir -p /w/app && cd /w/app
+printf 'source "%s/"\ngem "unkin-e2e-hello", "0.1.0"\n' "$V" > Gemfile
+bundle install
+bundle exec ruby -e 'require "unkin-e2e-hello"; puts "REQ #{UnkinE2eHello::VERSION}"'
+echo "REDIRECT $(curl -s -o /dev/null -w '%{redirect_url}' "$V/gems/unkin-e2e-hello-0.2.0.gem")"`
+
+	out, err := exec.Command("docker", "run", "--rm", "--network", network,
+		"-e", "BASE="+base, "-e", "A="+a, "-e", "B="+b, "-e", "V="+virt,
+		"ruby:3.3", "bash", "-c", script).CombinedOutput()
+	if err != nil {
+		t.Fatalf("bundler run failed: %v\n%s", err, out)
+	}
+	for _, want := range []string{
+		"VERSIONS 0.1.0,0.2.0",
+		"REQ " + a + ":0.1.0",
+		"REDIRECT " + base + "/api/v1/local/" + b + "/gems/unkin-e2e-hello-0.2.0.gem",
+	} {
+		if !strings.Contains(string(out), want) {
+			t.Fatalf("missing %q in bundler output:\n%s", want, out)
+		}
+	}
+}

internal/api/v1/ansible.go

@@ -0,0 +1,289 @@
+package v1
+
+import (
+	"bytes"
+	"cmp"
+	"context"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/url"
+	"slices"
+	"strconv"
+	"strings"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+
+	"git.unkin.net/unkin/artifactapi/internal/database"
+	"git.unkin.net/unkin/artifactapi/internal/provider/ansible"
+	"git.unkin.net/unkin/artifactapi/internal/virtual"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+var ansibleMaxPublishBytes int64 = 256 << 20
+
+// ansibleError writes a Galaxy v3 error document, which ansible-galaxy prints.
+func ansibleError(w http.ResponseWriter, status int, msg string) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(map[string]any{"errors": []map[string]string{{
+		"status": strconv.Itoa(status), "code": strings.ToLower(strings.ReplaceAll(http.StatusText(status), " ", "_")),
+		"title": http.StatusText(status), "detail": msg,
+	}}})
+}
+
+func writeAnsibleJSON(w http.ResponseWriter, status int, v any) {
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Cache-Control", "no-store")
+	w.Header().Set("Vary", "Host, X-Forwarded-Proto")
+	w.WriteHeader(status)
+	enc := json.NewEncoder(w)
+	enc.SetEscapeHTML(false)
+	_ = enc.Encode(v)
+}
+
+func isAnsiblePublish(path string) bool {
+	return strings.TrimSuffix(path, "/")+"/" == ansible.PublishPath
+}
+
+func (h *ProxyHandler) handleAnsiblePublish(w http.ResponseWriter, r *http.Request) {
+	remote, err := h.db.GetRemote(r.Context(), chi.URLParam(r, "localName"))
+	if err != nil || remote.RepoType != models.RepoTypeLocal || remote.PackageType != models.PackageAnsible {
+		ansibleError(w, http.StatusMethodNotAllowed, "publish is only supported on local ansible repositories")
+		return
+	}
+	base, ok := requestBaseURL(w, r)
+	if !ok {
+		return
+	}
+	r.Body = http.MaxBytesReader(w, r.Body, ansibleMaxPublishBytes)
+	file, sum, err := readAnsibleUpload(r)
+	if err != nil {
+		var tooLarge *http.MaxBytesError
+		if errors.As(err, &tooLarge) {
+			ansibleError(w, http.StatusRequestEntityTooLarge, fmt.Sprintf("upload exceeds %d bytes", ansibleMaxPublishBytes))
+			return
+		}
+		ansibleError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	digest := sha256.Sum256(file)
+	if got := hex.EncodeToString(digest[:]); sum != "" && !strings.EqualFold(sum, got) {
+		ansibleError(w, http.StatusBadRequest, "sha256 does not match the uploaded file")
+		return
+	}
+	e, err := ansible.ParseCollection(bytes.NewReader(file))
+	if err != nil {
+		ansibleError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	e.SHA256, e.Size, e.CreatedAt = hex.EncodeToString(digest[:]), int64(len(file)), time.Now().UTC()
+
+	id := e.Namespace + "." + e.Name + ":" + e.Version
+	unlock, err := h.engine.Lock(r.Context(), remote.Name, "_ansiblelock/"+e.TaskID(), gemsLockWait, 5*time.Minute)
+	if err != nil {
+		ansibleError(w, http.StatusServiceUnavailable, id+" is being published, retry")
+		return
+	}
+	defer unlock()
+	conflict := func() {
+		ansibleError(w, http.StatusConflict, id+" already exists; overwrites are not allowed")
+	}
+	if f, err := h.db.GetLocalFile(r.Context(), remote.Name, e.IndexPath()); err != nil {
+		ansibleError(w, http.StatusInternalServerError, err.Error())
+		return
+	} else if f != nil {
+		conflict()
+		return
+	}
+	// The version is not live, so a tarball left by a failed publish is safe to drop.
+	artifact := ansible.ArtifactPrefix + e.Filename()
+	fail := func(status int, msg string) {
+		if err := h.db.DeleteLocalFile(context.WithoutCancel(r.Context()), remote.Name, artifact); err != nil {
+			slog.Error("ansible publish cleanup failed", "repo", remote.Name, "path", artifact, "error", err)
+		}
+		ansibleError(w, status, msg)
+	}
+	if ok, err := h.npmStoreImmutable(r.Context(), remote.Name, artifact, file, "application/gzip"); err != nil {
+		fail(http.StatusInternalServerError, err.Error())
+		return
+	} else if !ok {
+		fail(http.StatusConflict, id+" already exists; overwrites are not allowed")
+		return
+	}
+	entry, err := json.Marshal(e)
+	if err != nil {
+		fail(http.StatusInternalServerError, err.Error())
+		return
+	}
+	// The index entry gates visibility, so it is written last.
+	if _, err := h.npmStore(r.Context(), remote.Name, e.IndexPath(), entry, "application/json", false); err != nil {
+		if errors.Is(err, database.ErrAlreadyExists) {
+			conflict()
+			return
+		}
+		fail(http.StatusInternalServerError, err.Error())
+		return
+	}
+	slog.Info("local ansible collection published", "repo", remote.Name, "collection", id)
+	repoBase := base + "/api/v1/local/" + url.PathEscape(remote.Name)
+	writeAnsibleJSON(w, http.StatusAccepted, map[string]string{"task": repoBase + "/api/v3/imports/collections/" + e.TaskID() + "/"})
+}
+
+// readAnsibleUpload returns the multipart "file" part, which ansible-galaxy
+// base64-encodes, and the optional "sha256" field sent with it.
+func readAnsibleUpload(r *http.Request) ([]byte, string, error) {
+	mr, err := r.MultipartReader()
+	if err != nil {
+		return nil, "", errors.New("expected a multipart/form-data upload")
+	}
+	var file []byte
+	var sum string
+	for {
+		part, err := mr.NextPart()
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return nil, "", err
+		}
+		switch part.FormName() {
+		case "file":
+			if file != nil {
+				return nil, "", errors.New("multiple file parts")
+			}
+			var src io.Reader = part
+			switch enc := strings.ToLower(part.Header.Get("Content-Transfer-Encoding")); enc {
+			case "base64":
+				src = base64.NewDecoder(base64.StdEncoding, part)
+			case "", "binary", "7bit", "8bit":
+			default:
+				return nil, "", fmt.Errorf("unsupported Content-Transfer-Encoding %q", enc)
+			}
+			if file, err = io.ReadAll(src); err != nil {
+				return nil, "", err
+			}
+		case "sha256":
+			b, err := io.ReadAll(io.LimitReader(part, 128))
+			if err != nil {
+				return nil, "", err
+			}
+			sum = strings.TrimSpace(string(b))
+		}
+	}
+	if file == nil {
+		return nil, "", errors.New("missing file part")
+	}
+	return file, sum, nil
+}
+
+// serveLocalAnsible answers the Galaxy v3 API of a local ansible repo.
+func (h *ProxyHandler) serveLocalAnsible(w http.ResponseWriter, r *http.Request, remote *models.Remote, ap ansible.APIPath) {
+	base, ok := requestBaseURL(w, r)
+	if !ok {
+		return
+	}
+	body, err := h.localAnsibleDoc(r.Context(), remote.Name, ap, r.URL.Query(), base+"/api/v1/local/"+url.PathEscape(remote.Name))
+	if errors.Is(err, virtual.ErrNotFound) {
+		ansibleError(w, http.StatusNotFound, "not found")
+		return
+	}
+	if err != nil {
+		ansibleError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	w.Header().Set("X-Artifact-Source", "local")
+	writeAnsibleJSON(w, http.StatusOK, body)
+}
+
+// LocalAnsible serves a local ansible repo's collection, full versions list
+// or version detail to ansible virtuals, with root-relative URLs.
+func (h *ProxyHandler) LocalAnsible(ctx context.Context, repo, path string) ([]byte, error) {
+	doc, err := h.localAnsibleDoc(ctx, repo, ansible.ParseAPIPath(path), nil, "/api/v1/local/"+url.PathEscape(repo))
+	if err != nil {
+		return nil, err
+	}
+	return json.Marshal(doc)
+}
+
+// localAnsibleDoc builds the document for ap; a nil q lists every version.
+func (h *ProxyHandler) localAnsibleDoc(ctx context.Context, repo string, ap ansible.APIPath, q url.Values, base string) (any, error) {
+	switch ap.Kind {
+	case ansible.APIRoot:
+		return ansible.Root(), nil
+	case ansible.APIImport:
+		ns, rest, _ := strings.Cut(ap.TaskID, "-")
+		name, version, _ := strings.Cut(rest, "-")
+		entries, err := h.localAnsibleEntries(ctx, repo, ns, name)
+		if err != nil {
+			return nil, err
+		}
+		for _, e := range entries {
+			if e.Version == version {
+				return ansible.ImportTask(e), nil
+			}
+		}
+	case ansible.APICollection, ansible.APIVersions, ansible.APIVersion:
+		entries, err := h.localAnsibleEntries(ctx, repo, ap.Namespace, ap.Name)
+		if err != nil || len(entries) == 0 {
+			return nil, cmp.Or(err, virtual.ErrNotFound)
+		}
+		refs := make([]ansible.VersionRef, len(entries))
+		for i, e := range entries {
+			refs[i] = e.Ref()
+		}
+		switch ap.Kind {
+		case ansible.APICollection:
+			return ansible.CollectionDoc(base, ap.Namespace, ap.Name, refs), nil
+		case ansible.APIVersions:
+			limit, offset := len(refs), 0
+			if q != nil {
+				limit, offset = ansible.Page(q)
+			}
+			return ansible.VersionsPage(base, ap.Namespace, ap.Name, refs, limit, offset), nil
+		}
+		for _, e := range entries {
+			if e.Version == ap.Version {
+				return ansible.VersionDoc(base, e), nil
+			}
+		}
+	}
+	return nil, virtual.ErrNotFound
+}
+
+// localAnsibleEntries returns a collection's versions, newest publish first.
+func (h *ProxyHandler) localAnsibleEntries(ctx context.Context, repo, ns, name string) ([]ansible.Entry, error) {
+	if !ansible.NameRe.MatchString(ns) || !ansible.NameRe.MatchString(name) {
+		return nil, nil
+	}
+	prefix := ansible.IndexPrefix + ns + "/" + name + "/"
+	files, err := h.db.ListLocalFilesByPrefix(ctx, repo, prefix)
+	if err != nil {
+		return nil, err
+	}
+	slices.SortFunc(files, func(a, b database.LocalFile) int { return cmp.Compare(b.ID, a.ID) })
+	var out []ansible.Entry
+	for _, f := range files {
+		// LIKE treats '_' as a wildcard, so the prefix match can over-select.
+		if !strings.HasPrefix(f.FilePath, prefix) {
+			continue
+		}
+		raw, err := h.readLocalBlob(ctx, f.ContentHash)
+		if err != nil {
+			return nil, err
+		}
+		var e ansible.Entry
+		if err := json.Unmarshal(raw, &e); err != nil {
+			return nil, fmt.Errorf("decode %s: %w", f.FilePath, err)
+		}
+		out = append(out, e)
+	}
+	return out, nil
+}

internal/api/v1/ansible_handler_test.go

@@ -0,0 +1,275 @@
+package v1
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"context"
+	"encoding/base64"
+	"encoding/json"
+	"mime/multipart"
+	"net/http"
+	"net/http/httptest"
+	"net/textproto"
+	"strings"
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/virtual"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func testCollection(t *testing.T, ns, name, version string) []byte {
+	t.Helper()
+	manifest := `{"collection_info":{"namespace":"` + ns + `","name":"` + name + `","version":"` + version + `","dependencies":{"ansible.posix":">=1.0.0"}}}`
+	var buf bytes.Buffer
+	zw := gzip.NewWriter(&buf)
+	tw := tar.NewWriter(zw)
+	_ = tw.WriteHeader(&tar.Header{Name: "MANIFEST.json", Mode: 0o644, Size: int64(len(manifest))})
+	_, _ = tw.Write([]byte(manifest))
+	_ = tw.Close()
+	_ = zw.Close()
+	return buf.Bytes()
+}
+
+// ansiblePublish uploads like ansible-galaxy: the file part base64-encoded
+// whenever a sha256 field is sent, raw otherwise.
+func ansiblePublish(t *testing.T, url string, tarball []byte, sum string) (int, string) {
+	t.Helper()
+	var body bytes.Buffer
+	mw := multipart.NewWriter(&body)
+	hdr := textproto.MIMEHeader{"Content-Disposition": {`form-data; name="file"; filename="c.tar.gz"`}}
+	data := tarball
+	if sum != "" {
+		_ = mw.WriteField("sha256", sum)
+		hdr.Set("Content-Transfer-Encoding", "base64")
+		data = []byte(base64.StdEncoding.EncodeToString(tarball))
+	}
+	fw, _ := mw.CreatePart(hdr)
+	_, _ = fw.Write(data)
+	_ = mw.Close()
+	req, _ := http.NewRequest(http.MethodPost, url, &body)
+	req.Header.Set("Content-Type", mw.FormDataContentType())
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+	var b bytes.Buffer
+	_, _ = b.ReadFrom(resp.Body)
+	return resp.StatusCode, b.String()
+}
+
+func getJSON(t *testing.T, url string, v any) {
+	t.Helper()
+	code, body := npmDo(t, http.MethodGet, url, "")
+	if code != http.StatusOK {
+		t.Fatalf("GET %s = %d: %s", url, code, body)
+	}
+	if err := json.Unmarshal([]byte(body), v); err != nil {
+		t.Fatalf("GET %s: %v: %s", url, err, body)
+	}
+}
+
+func TestAnsiblePublishAndServe(t *testing.T) {
+	h, srv := npmTestServer(t)
+	repo := npmRepo(t, h, models.PackageAnsible)
+	base := srv.URL + "/api/v1/local/" + repo + "/"
+	publish := base + "api/v3/artifacts/collections/"
+
+	v1 := testCollection(t, "unkin", "e2e_hello", "1.0.0")
+	code, body := ansiblePublish(t, publish, v1, sha256Hex(v1))
+	if code != http.StatusAccepted {
+		t.Fatalf("publish = %d: %s", code, body)
+	}
+	var task struct{ Task string }
+	_ = json.Unmarshal([]byte(body), &task)
+	if task.Task != base+"api/v3/imports/collections/unkin-e2e_hello-1.0.0/" {
+		t.Fatalf("task = %q", task.Task)
+	}
+	var st map[string]any
+	getJSON(t, task.Task, &st)
+	if st["state"] != "completed" || st["finished_at"] == "" {
+		t.Fatalf("task = %v", st)
+	}
+	if code, _ := npmDo(t, http.MethodGet, base+"api/v3/imports/collections/unkin-e2e_hello-9.9.9/", ""); code != http.StatusNotFound {
+		t.Errorf("unknown task = %d, want 404", code)
+	}
+
+	for _, v := range []string{"1.1.0", "2.0.0"} {
+		tb := testCollection(t, "unkin", "e2e_hello", v)
+		if code, body := ansiblePublish(t, publish, tb, ""); code != http.StatusAccepted {
+			t.Fatalf("publish %s = %d: %s", v, code, body)
+		}
+	}
+	if code, body := ansiblePublish(t, publish, v1, ""); code != http.StatusConflict || !strings.Contains(body, "already exists") {
+		t.Errorf("identical republish = %d: %s, want 409", code, body)
+	}
+	if code, _ := ansiblePublish(t, publish, testCollection(t, "unkin", "e2e_hello", "1.0.0")[:20], ""); code != http.StatusBadRequest {
+		t.Errorf("truncated tarball = %d, want 400", code)
+	}
+
+	var root map[string]map[string]string
+	getJSON(t, base+"api/", &root)
+	if root["available_versions"]["v3"] != "v3/" {
+		t.Fatalf("root = %v", root)
+	}
+
+	var page struct {
+		Meta  struct{ Count int }
+		Links struct{ Next, Previous *string }
+		Data  []struct{ Version, Href string }
+	}
+	getJSON(t, base+"api/v3/collections/unkin/e2e_hello/versions/?limit=2", &page)
+	if page.Meta.Count != 3 || len(page.Data) != 2 || page.Data[0].Version != "2.0.0" || page.Links.Next == nil || page.Links.Previous != nil {
+		t.Fatalf("page 1 = %+v", page)
+	}
+	next := *page.Links.Next
+	if !strings.HasPrefix(next, "/api/v1/local/"+repo+"/") {
+		t.Fatalf("next = %q, want root-relative", next)
+	}
+	next = srv.URL + next
+	page.Links.Next = nil
+	getJSON(t, next, &page)
+	if len(page.Data) != 1 || page.Data[0].Version != "1.0.0" || page.Links.Next != nil {
+		t.Fatalf("page 2 (%s) = %+v", next, page)
+	}
+
+	var detail struct {
+		DownloadURL string `json:"download_url"`
+		Artifact    struct{ Sha256 string }
+		Metadata    struct{ Dependencies map[string]string }
+		Namespace   struct{ Name string }
+		Collection  struct{ Name string }
+	}
+	getJSON(t, page.Data[0].Href, &detail)
+	if detail.DownloadURL != base+"artifacts/unkin-e2e_hello-1.0.0.tar.gz" || detail.Artifact.Sha256 != sha256Hex(v1) ||
+		detail.Metadata.Dependencies["ansible.posix"] != ">=1.0.0" || detail.Namespace.Name != "unkin" || detail.Collection.Name != "e2e_hello" {
+		t.Fatalf("detail = %+v", detail)
+	}
+	if code, got := npmDo(t, http.MethodGet, detail.DownloadURL, ""); code != http.StatusOK || got != string(v1) {
+		t.Fatalf("download = %d (%d bytes)", code, len(got))
+	}
+
+	var coll map[string]any
+	getJSON(t, base+"api/v3/collections/unkin/e2e_hello/", &coll)
+	if coll["versions_url"] != base+"api/v3/collections/unkin/e2e_hello/versions/" || coll["updated_at"] == "" {
+		t.Fatalf("collection = %v", coll)
+	}
+	for _, p := range []string{"api/v3/collections/unkin/nope/", "api/v3/collections/unkin/e2e_hello/versions/9.0.0/", "_index/unkin/e2e_hello/1.0.0", "other"} {
+		if code, _ := npmDo(t, http.MethodGet, base+p, ""); code != http.StatusNotFound {
+			t.Errorf("GET %s = %d, want 404", p, code)
+		}
+	}
+}
+
+func TestAnsiblePublishRejects(t *testing.T) {
+	h, srv := npmTestServer(t)
+	repo := npmRepo(t, h, models.PackageAnsible)
+	publish := srv.URL + "/api/v1/local/" + repo + "/api/v3/artifacts/collections/"
+	tb := testCollection(t, "unkin", "rej", "1.0.0")
+
+	if code, _ := ansiblePublish(t, publish, tb, strings.Repeat("0", 64)); code != http.StatusBadRequest {
+		t.Errorf("sha256 mismatch = %d, want 400", code)
+	}
+	if code, _ := npmDo(t, http.MethodPost, publish, "raw"); code != http.StatusBadRequest {
+		t.Errorf("non-multipart = %d, want 400", code)
+	}
+	old := ansibleMaxPublishBytes
+	ansibleMaxPublishBytes = 64
+	if code, _ := ansiblePublish(t, publish, tb, ""); code != http.StatusRequestEntityTooLarge {
+		t.Errorf("oversize = %d, want 413", code)
+	}
+	ansibleMaxPublishBytes = old
+	generic := npmRepo(t, h, models.PackageGeneric)
+	if code, _ := ansiblePublish(t, srv.URL+"/api/v1/local/"+generic+"/api/v3/artifacts/collections/", tb, ""); code != http.StatusMethodNotAllowed {
+		t.Errorf("publish to generic local = %d, want 405", code)
+	}
+	if code, _ := ansiblePublish(t, publish, tb, ""); code != http.StatusAccepted {
+		t.Errorf("publish after rejects = %d, want 202", code)
+	}
+}
+
+func TestAnsibleLocalPerHost(t *testing.T) {
+	h, srv := npmTestServer(t)
+	repo := npmRepo(t, h, models.PackageAnsible)
+	if code, b := ansiblePublish(t, srv.URL+"/api/v1/local/"+repo+"/api/v3/artifacts/collections/", testCollection(t, "unkin", "host", "1.0.0"), ""); code != http.StatusAccepted {
+		t.Fatalf("publish = %d: %s", code, b)
+	}
+	routes := h.Routes()
+	path := "/local/" + repo + "/api/v3/collections/unkin/host/versions/1.0.0/"
+	r := httptest.NewRequest(http.MethodGet, path, nil)
+	r.Host = "x@evil.com"
+	w := httptest.NewRecorder()
+	routes.ServeHTTP(w, r)
+	if w.Code != http.StatusBadRequest {
+		t.Errorf("bad Host = %d, want 400", w.Code)
+	}
+	r = httptest.NewRequest(http.MethodGet, path, nil)
+	r.Host = "aa.example"
+	r.Header.Set("X-Forwarded-Proto", "https")
+	w = httptest.NewRecorder()
+	routes.ServeHTTP(w, r)
+	if w.Code != http.StatusOK || !strings.Contains(w.Body.String(), `"download_url":"https://aa.example/api/v1/local/`+repo+`/artifacts/unkin-host-1.0.0.tar.gz"`) {
+		t.Fatalf("detail = %d: %s", w.Code, w.Body)
+	}
+	if cc, vary := w.Header().Get("Cache-Control"), w.Header().Get("Vary"); cc != "no-store" || vary != "Host, X-Forwarded-Proto" {
+		t.Errorf("Cache-Control %q Vary %q", cc, vary)
+	}
+}
+
+func TestAnsibleVirtualOverLocals(t *testing.T) {
+	h, srv := npmTestServer(t)
+	h.virtualEngine = virtual.NewEngine(h.db, nil)
+	h.virtualEngine.AnsibleLocal = h.LocalAnsible
+	a, b := npmRepo(t, h, models.PackageAnsible), npmRepo(t, h, models.PackageAnsible)
+	for _, p := range []struct{ repo, version string }{{a, "1.0.0"}, {b, "1.0.0"}, {b, "2.0.0"}} {
+		if code, body := ansiblePublish(t, srv.URL+"/api/v1/local/"+p.repo+"/api/v3/artifacts/collections/", testCollection(t, "unkin", "virt", p.version), ""); code != http.StatusAccepted {
+			t.Fatalf("publish %s to %s = %d: %s", p.version, p.repo, code, body)
+		}
+	}
+	virt := "v" + a
+	if err := h.db.CreateVirtual(context.Background(), &models.Virtual{Name: virt, PackageType: models.PackageAnsible, Members: []string{a, b}}); err != nil {
+		t.Fatal(err)
+	}
+	base := srv.URL + "/api/v1/virtual/" + virt + "/"
+
+	var page struct {
+		Meta  struct{ Count int }
+		Links struct{ Next *string }
+		Data  []struct{ Version, Href string }
+	}
+	getJSON(t, base+"api/v3/collections/unkin/virt/versions/?limit=1", &page)
+	if page.Meta.Count != 2 || len(page.Data) != 1 || page.Data[0].Version != "1.0.0" || page.Links.Next == nil {
+		t.Fatalf("page 1 = %+v", page)
+	}
+	href := page.Data[0].Href
+	if !strings.HasPrefix(*page.Links.Next, "/api/v1/virtual/"+virt+"/") {
+		t.Fatalf("next = %q, want root-relative", *page.Links.Next)
+	}
+	getJSON(t, srv.URL+*page.Links.Next, &page)
+	if len(page.Data) != 1 || page.Data[0].Version != "2.0.0" || page.Links.Next != nil {
+		t.Fatalf("page 2 = %+v", page)
+	}
+
+	var detail struct {
+		DownloadURL string `json:"download_url"`
+	}
+	getJSON(t, href, &detail)
+	if detail.DownloadURL != base+a+"/artifacts/unkin-virt-1.0.0.tar.gz" {
+		t.Fatalf("download_url = %q, want the first member via the virtual", detail.DownloadURL)
+	}
+	noFollow := &http.Client{CheckRedirect: func(*http.Request, []*http.Request) error { return http.ErrUseLastResponse }}
+	resp, err := noFollow.Get(detail.DownloadURL)
+	if err != nil {
+		t.Fatal(err)
+	}
+	_ = resp.Body.Close()
+	if resp.StatusCode != http.StatusFound || resp.Header.Get("Location") != srv.URL+"/api/v1/local/"+a+"/artifacts/unkin-virt-1.0.0.tar.gz" {
+		t.Fatalf("download = %d -> %q", resp.StatusCode, resp.Header.Get("Location"))
+	}
+	for _, p := range []string{"api/v3/collections/unkin/nope/", "notamember/x.tar.gz"} {
+		if code, _ := npmDo(t, http.MethodGet, base+p, ""); code != http.StatusNotFound {
+			t.Errorf("GET %s = %d, want 404", p, code)
+		}
+	}
+}

internal/api/v1/ansible_virtual.go

@@ -0,0 +1,64 @@
+package v1
+
+import (
+	"encoding/json"
+	"errors"
+	"log/slog"
+	"net/http"
+	"net/url"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider/ansible"
+	"git.unkin.net/unkin/artifactapi/internal/virtual"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+// serveVirtualAnsible serves the merged Galaxy v3 API and 302s downloads to
+// the member owning that version.
+func (h *ProxyHandler) serveVirtualAnsible(w http.ResponseWriter, r *http.Request, virt models.Virtual, path, proxyBaseURL string) {
+	ap := ansible.ParseAPIPath(path)
+	base := proxyBaseURL + "/api/v1/virtual/" + url.PathEscape(virt.Name)
+	var doc any
+	var err error
+	switch ap.Kind {
+	case ansible.APIRoot:
+		doc = ansible.Root()
+	case ansible.APIVersion:
+		var body []byte
+		if body, err = h.virtualEngine.AnsibleVersion(r.Context(), virt, ap.Namespace, ap.Name, ap.Version, proxyBaseURL); err == nil {
+			doc = json.RawMessage(body)
+		}
+	case ansible.APICollection, ansible.APIVersions:
+		var d *virtual.AnsibleDoc
+		if d, err = h.virtualEngine.AnsibleVersions(r.Context(), virt, ap.Namespace, ap.Name); err == nil {
+			if ap.Kind == ansible.APICollection {
+				doc = ansible.CollectionDoc(base, ap.Namespace, ap.Name, d.Refs)
+			} else {
+				limit, offset := ansible.Page(r.URL.Query())
+				doc = ansible.VersionsPage(base, ap.Namespace, ap.Name, d.Refs, limit, offset)
+			}
+		}
+	default:
+		loc, ok, err := h.virtualEngine.MemberRedirect(r.Context(), virt, path, r.URL.RawQuery, proxyBaseURL)
+		switch {
+		case err != nil:
+			ansibleError(w, http.StatusBadRequest, err.Error())
+		case !ok:
+			ansibleError(w, http.StatusNotFound, "not found")
+		default:
+			w.Header().Set("Cache-Control", "no-store")
+			w.Header().Set("Vary", "Host, X-Forwarded-Proto")
+			http.Redirect(w, r, loc, http.StatusFound)
+		}
+		return
+	}
+	switch {
+	case errors.Is(err, virtual.ErrNotFound):
+		ansibleError(w, http.StatusNotFound, "not found")
+	case err != nil:
+		slog.Error("virtual ansible fetch failed", "virtual", virt.Name, "path", path, "error", err)
+		ansibleError(w, http.StatusBadGateway, "bad gateway")
+	default:
+		w.Header().Set("X-Artifact-Source", "virtual")
+		writeAnsibleJSON(w, http.StatusOK, doc)
+	}
+}

internal/api/v1/forwardquery_test.go

@@ -0,0 +1,58 @@
+package v1
+
+import (
+	"net/url"
+	"strings"
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+)
+
+type plainProvider struct{ provider.Provider }
+
+type forwardingProvider struct{ plainProvider }
+
+func digits(v string) (string, bool) {
+	if v == "" || strings.Trim(v, "0123456789") != "" {
+		return "", false
+	}
+	return strings.TrimLeft(v, "0"), true
+}
+
+func (forwardingProvider) ForwardedQuery(path string) map[string]provider.QueryValidator {
+	if strings.HasSuffix(path, ".tar.gz") {
+		return nil
+	}
+	return map[string]provider.QueryValidator{"limit": digits, "offset": digits}
+}
+
+func TestForwardQuery(t *testing.T) {
+	tests := []struct {
+		name  string
+		prov  provider.Provider
+		path  string
+		query string
+		want  string
+	}{
+		{"non-forwarder keeps path", plainProvider{}, "a/versions/", "limit=10&offset=5", "a/versions/"},
+		{"no query", forwardingProvider{}, "a/versions/", "", "a/versions/"},
+		{"allowlisted params sorted", forwardingProvider{}, "a/versions/", "offset=5&limit=10", "a/versions/?limit=10&offset=5"},
+		{"unknown params dropped", forwardingProvider{}, "a/versions/", "x=1&limit=10&cb=zz", "a/versions/?limit=10"},
+		{"only unknown params", forwardingProvider{}, "a/versions/", "x=1", "a/versions/"},
+		{"first value wins", forwardingProvider{}, "a/versions/", "limit=10&limit=20", "a/versions/?limit=10"},
+		{"invalid value dropped", forwardingProvider{}, "a/versions/", "limit=1%202&offset=5", "a/versions/?offset=5"},
+		{"value canonicalised", forwardingProvider{}, "a/versions/", "limit=0010", "a/versions/?limit=10"},
+		{"path without allowlist", forwardingProvider{}, "a/b-1.0.0.tar.gz", "limit=10", "a/b-1.0.0.tar.gz"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			q, err := url.ParseQuery(tt.query)
+			if err != nil {
+				t.Fatal(err)
+			}
+			if got := forwardQuery(tt.prov, tt.path, q); got != tt.want {
+				t.Errorf("forwardQuery = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}

internal/api/v1/gems.go

@@ -0,0 +1,312 @@
+package v1
+
+import (
+	"cmp"
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"maps"
+	"net/http"
+	"net/url"
+	"slices"
+	"strings"
+	"time"
+
+	"github.com/go-chi/chi/v5"
+
+	"git.unkin.net/unkin/artifactapi/internal/database"
+	"git.unkin.net/unkin/artifactapi/internal/provider/gems"
+	"git.unkin.net/unkin/artifactapi/internal/virtual"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+// Local gems repos speak the RubyGems push/yank API and compact index. Per gem:
+//   gems/<full>.gem                         package (immutable)
+//   quick/Marshal.4.8/<full>.gemspec.rz     marshalled spec (immutable)
+//   _index/<name>/<full>                    compact index /info line; gates visibility
+//   _yanked/<name>/<full>                   yank tombstone; blocks re-push of the version
+
+var (
+	gemsMaxPushBytes int64 = 256 << 20
+	gemsLockWait           = 30 * time.Second
+)
+
+const (
+	gemsIndexPrefix  = "_index/"
+	gemsYankedPrefix = "_yanked/"
+)
+
+func gemsText(w http.ResponseWriter, status int, msg string) {
+	w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+	w.WriteHeader(status)
+	_, _ = io.WriteString(w, msg)
+}
+
+func (h *ProxyHandler) localGemsRemote(w http.ResponseWriter, r *http.Request) (*models.Remote, bool) {
+	remote, err := h.db.GetRemote(r.Context(), chi.URLParam(r, "localName"))
+	if err != nil || remote.RepoType != models.RepoTypeLocal || remote.PackageType != models.PackageGems {
+		gemsText(w, http.StatusMethodNotAllowed, "only supported on local gems repositories")
+		return nil, false
+	}
+	return remote, true
+}
+
+// lockGemVersion serialises push and yank of one gem version across replicas.
+func (h *ProxyHandler) lockGemVersion(w http.ResponseWriter, r *http.Request, repo, full string) (func(), bool) {
+	unlock, err := h.engine.Lock(r.Context(), repo, "_gemlock/"+full, gemsLockWait, 5*time.Minute)
+	if err != nil {
+		gemsText(w, http.StatusServiceUnavailable, full+" is being pushed or yanked, retry")
+		return nil, false
+	}
+	return unlock, true
+}
+
+func (h *ProxyHandler) handleLocalPost(w http.ResponseWriter, r *http.Request) {
+	if isAnsiblePublish(chi.URLParam(r, "*")) {
+		h.handleAnsiblePublish(w, r)
+		return
+	}
+	if chi.URLParam(r, "*") != "api/v1/gems" {
+		gemsText(w, http.StatusNotFound, "not found")
+		return
+	}
+	remote, ok := h.localGemsRemote(w, r)
+	if !ok {
+		return
+	}
+	gem, err := io.ReadAll(http.MaxBytesReader(w, r.Body, gemsMaxPushBytes))
+	if err != nil {
+		gemsText(w, http.StatusRequestEntityTooLarge, fmt.Sprintf("gem exceeds %d bytes", gemsMaxPushBytes))
+		return
+	}
+	spec, err := gems.ParseGem(gem)
+	if err != nil {
+		gemsText(w, http.StatusBadRequest, err.Error())
+		return
+	}
+	quick, err := gems.QuickSpec(spec)
+	if err != nil {
+		gemsText(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+
+	full := spec.FullName()
+	unlock, ok := h.lockGemVersion(w, r, remote.Name, full)
+	if !ok {
+		return
+	}
+	defer unlock()
+	conflict := func() {
+		gemsText(w, http.StatusConflict, fmt.Sprintf("%s already exists; overwrites are not allowed", full))
+	}
+	index := gemsIndexPrefix + spec.Name + "/" + full
+	for _, p := range []string{gemsYankedPrefix + spec.Name + "/" + full, index} {
+		f, err := h.db.GetLocalFile(r.Context(), remote.Name, p)
+		if err != nil {
+			gemsText(w, http.StatusInternalServerError, err.Error())
+			return
+		}
+		if f != nil && p == index {
+			conflict()
+			return
+		}
+		if f != nil {
+			gemsText(w, http.StatusConflict, fmt.Sprintf("%s was yanked; re-pushing a yanked version is not allowed", full))
+			return
+		}
+	}
+	// The version is not live, so on failure every path is an invisible leftover and safe to drop.
+	paths := []string{"gems/" + full + ".gem", "quick/Marshal.4.8/" + full + ".gemspec.rz", index}
+	fail := func(status int, msg string) {
+		for _, p := range paths {
+			if err := h.db.DeleteLocalFile(context.WithoutCancel(r.Context()), remote.Name, p); err != nil {
+				slog.Error("gem push cleanup failed", "repo", remote.Name, "path", p, "error", err)
+			}
+		}
+		gemsText(w, status, msg)
+	}
+	// The index line gates visibility, so it is written last.
+	for _, f := range []struct {
+		path string
+		data []byte
+	}{
+		{paths[0], gem},
+		{paths[1], quick},
+	} {
+		ok, err := h.npmStoreImmutable(r.Context(), remote.Name, f.path, f.data, "application/octet-stream")
+		if err != nil {
+			fail(http.StatusInternalServerError, err.Error())
+			return
+		}
+		if !ok {
+			fail(http.StatusConflict, fmt.Sprintf("%s already exists; overwrites are not allowed", full))
+			return
+		}
+	}
+	line := gems.InfoLine(spec, gem)
+	if _, err := h.npmStore(r.Context(), remote.Name, index, []byte(line), "text/plain", false); err != nil {
+		fail(http.StatusInternalServerError, err.Error())
+		return
+	}
+
+	slog.Info("local gem pushed", "repo", remote.Name, "gem", full)
+	gemsText(w, http.StatusOK, "Successfully registered gem: "+spec.Name+" ("+spec.Version+")")
+}
+
+func (h *ProxyHandler) handleLocalDelete(w http.ResponseWriter, r *http.Request) {
+	if chi.URLParam(r, "*") != "api/v1/gems/yank" {
+		gemsText(w, http.StatusNotFound, "not found")
+		return
+	}
+	remote, ok := h.localGemsRemote(w, r)
+	if !ok {
+		return
+	}
+	body, err := io.ReadAll(http.MaxBytesReader(w, r.Body, 64<<10))
+	if err != nil {
+		gemsText(w, http.StatusRequestEntityTooLarge, "yank body too large")
+		return
+	}
+	form, err := url.ParseQuery(string(body))
+	if err != nil {
+		gemsText(w, http.StatusBadRequest, "invalid form body")
+		return
+	}
+	for k, v := range r.URL.Query() {
+		if form.Get(k) == "" {
+			form[k] = v
+		}
+	}
+	spec := &gems.Spec{Name: form.Get("gem_name"), Version: form.Get("version"), Platform: form.Get("platform")}
+	if spec.Platform == "" {
+		spec.Platform = "ruby"
+	}
+	if !gems.NameRe.MatchString(spec.Name) || !gems.VersionRe.MatchString(spec.Version) || !gems.PlatformRe.MatchString(spec.Platform) {
+		gemsText(w, http.StatusBadRequest, "invalid gem_name, version or platform")
+		return
+	}
+
+	full := spec.FullName()
+	unlock, ok := h.lockGemVersion(w, r, remote.Name, full)
+	if !ok {
+		return
+	}
+	defer unlock()
+	index := gemsIndexPrefix + spec.Name + "/" + full
+	existing, err := h.db.GetLocalFile(r.Context(), remote.Name, index)
+	if err != nil {
+		gemsText(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	if existing == nil {
+		gemsText(w, http.StatusNotFound, "The version "+spec.Version+" does not exist")
+		return
+	}
+	// The tombstone keeps the yanked line and is written before any delete.
+	line, err := h.readLocalBlob(r.Context(), existing.ContentHash)
+	if err != nil {
+		gemsText(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	if _, err := h.npmStore(r.Context(), remote.Name, gemsYankedPrefix+spec.Name+"/"+full, line, "text/plain", false); err != nil && !errors.Is(err, database.ErrAlreadyExists) {
+		gemsText(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	for _, p := range []string{index, "gems/" + full + ".gem", "quick/Marshal.4.8/" + full + ".gemspec.rz"} {
+		if err := h.db.DeleteLocalFile(context.WithoutCancel(r.Context()), remote.Name, p); err != nil {
+			gemsText(w, http.StatusInternalServerError, err.Error())
+			return
+		}
+	}
+	slog.Info("local gem yanked", "repo", remote.Name, "gem", full)
+	gemsText(w, http.StatusOK, "Successfully deleted gem: "+spec.Name+" ("+spec.Version+")")
+}
+
+// isGemsIndexPath reports whether path is a compact index document.
+func isGemsIndexPath(path string) bool {
+	return path == "versions" || path == "names" || strings.HasPrefix(path, "info/")
+}
+
+func (h *ProxyHandler) serveLocalGemsIndex(w http.ResponseWriter, r *http.Request, remote *models.Remote, path string) {
+	body, err := h.LocalGemsIndex(r.Context(), remote.Name, path)
+	if errors.Is(err, virtual.ErrNotFound) {
+		gemsText(w, http.StatusNotFound, "not found")
+		return
+	}
+	if err != nil {
+		gemsText(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	w.Header().Set("X-Artifact-Source", "local")
+	gemsText(w, http.StatusOK, string(body))
+}
+
+// LocalGemsIndex builds a local gems repo's versions, names or info/<gem>
+// document, or returns virtual.ErrNotFound.
+func (h *ProxyHandler) LocalGemsIndex(ctx context.Context, repo, path string) ([]byte, error) {
+	if name, ok := strings.CutPrefix(path, "info/"); ok {
+		if !gems.NameRe.MatchString(name) {
+			return nil, virtual.ErrNotFound
+		}
+		lines, err := h.localGemsLines(ctx, repo, gemsIndexPrefix+name+"/")
+		if err != nil {
+			return nil, err
+		}
+		if len(lines[name]) == 0 {
+			return nil, virtual.ErrNotFound
+		}
+		return gems.InfoBody(lines[name]), nil
+	}
+	if path != "versions" && path != "names" {
+		return nil, virtual.ErrNotFound
+	}
+	lines, err := h.localGemsLines(ctx, repo, gemsIndexPrefix)
+	if err != nil {
+		return nil, err
+	}
+	names := slices.Sorted(maps.Keys(lines))
+	var b strings.Builder
+	if path == "names" {
+		b.WriteString("---\n")
+		for _, n := range names {
+			b.WriteString(n + "\n")
+		}
+		return []byte(b.String()), nil
+	}
+	b.WriteString(gems.VersionsHeader(time.Now()))
+	for _, n := range names {
+		b.WriteString(gems.VersionsLine(n, gems.InfoBody(lines[n])) + "\n")
+	}
+	return []byte(b.String()), nil
+}
+
+// localGemsLines returns /info lines per gem name in push order.
+func (h *ProxyHandler) localGemsLines(ctx context.Context, repo, prefix string) (map[string][]string, error) {
+	files, err := h.db.ListLocalFilesByPrefix(ctx, repo, prefix)
+	if err != nil {
+		return nil, err
+	}
+	slices.SortFunc(files, func(a, b database.LocalFile) int { return cmp.Compare(a.ID, b.ID) })
+	out := map[string][]string{}
+	for _, f := range files {
+		// LIKE treats '_' as a wildcard, so the prefix match can over-select.
+		rest, ok := strings.CutPrefix(f.FilePath, prefix)
+		if !ok {
+			continue
+		}
+		name := strings.TrimPrefix(prefix, gemsIndexPrefix)
+		if name == "" {
+			name, _, _ = strings.Cut(rest, "/")
+		} else {
+			name = strings.TrimSuffix(name, "/")
+		}
+		line, err := h.readLocalBlob(ctx, f.ContentHash)
+		if err != nil {
+			return nil, err
+		}
+		out[name] = append(out[name], string(line))
+	}
+	return out, nil
+}

internal/api/v1/gems_handler_test.go

@@ -0,0 +1,254 @@
+package v1
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"context"
+	"crypto/md5"
+	"crypto/sha256"
+	"encoding/hex"
+	"fmt"
+	"net/http"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"git.unkin.net/unkin/artifactapi/internal/cache"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func testGemFile(t *testing.T, name, version, platform string) []byte {
+	t.Helper()
+	meta := fmt.Sprintf(`--- !ruby/object:Gem::Specification
+name: %s
+version: !ruby/object:Gem::Version
+  version: %s
+platform: %s
+dependencies:
+- !ruby/object:Gem::Dependency
+  name: rack
+  requirement: !ruby/object:Gem::Requirement
+    requirements:
+    - - "~>"
+      - !ruby/object:Gem::Version
+        version: '3.0'
+  type: :runtime
+  prerelease: false
+rubygems_version: 3.5.22
+specification_version: 4
+summary: test
+`, name, version, platform)
+	var gz bytes.Buffer
+	zw := gzip.NewWriter(&gz)
+	_, _ = zw.Write([]byte(meta))
+	_ = zw.Close()
+	var buf bytes.Buffer
+	tw := tar.NewWriter(&buf)
+	_ = tw.WriteHeader(&tar.Header{Name: "metadata.gz", Mode: 0o444, Size: int64(gz.Len())})
+	_, _ = tw.Write(gz.Bytes())
+	_ = tw.Close()
+	return buf.Bytes()
+}
+
+func sha256Hex(b []byte) string {
+	s := sha256.Sum256(b)
+	return hex.EncodeToString(s[:])
+}
+
+func TestGemsPushIndexYank(t *testing.T) {
+	h, srv := npmTestServer(t)
+	repo := npmRepo(t, h, models.PackageGems)
+	base := srv.URL + "/api/v1/local/" + repo + "/"
+
+	g1 := testGemFile(t, "hello_gem", "0.1.0", "ruby")
+	g2 := testGemFile(t, "hello_gem", "0.2.0", "ruby")
+	gj := testGemFile(t, "hello_gem", "0.2.0", "java")
+	other := testGemFile(t, "hello-gem", "1.0.0", "ruby")
+	for _, g := range [][]byte{g1, g2, gj, other} {
+		if code, body := npmDo(t, http.MethodPost, base+"api/v1/gems", string(g)); code != http.StatusOK {
+			t.Fatalf("push = %d: %s", code, body)
+		}
+	}
+	if code, _ := npmDo(t, http.MethodPost, base+"api/v1/gems", string(g1)+"x"); code != http.StatusConflict {
+		t.Fatalf("repush with different bytes = %d, want 409", code)
+	}
+	if code, _ := npmDo(t, http.MethodPost, base+"api/v1/gems", string(g1)); code != http.StatusConflict {
+		t.Fatalf("identical repush = %d, want 409", code)
+	}
+	if code, _ := npmDo(t, http.MethodPost, base+"api/v1/gems", "not a gem"); code != http.StatusBadRequest {
+		t.Fatalf("garbage push = %d, want 400", code)
+	}
+
+	code, info := npmDo(t, http.MethodGet, base+"info/hello_gem", "")
+	want := "---\n0.1.0 rack:~> 3.0|checksum:" + sha256Hex(g1) + "\n0.2.0 rack:~> 3.0|checksum:" + sha256Hex(g2) +
+		"\n0.2.0-java rack:~> 3.0|checksum:" + sha256Hex(gj) + "\n"
+	if code != http.StatusOK || info != want {
+		t.Fatalf("info = %d\n%q\nwant\n%q", code, info, want)
+	}
+	if code, _ := npmDo(t, http.MethodHead, base+"versions", ""); code != http.StatusOK {
+		t.Fatalf("HEAD versions = %d; gem probes the compact index with HEAD", code)
+	}
+	_, versions := npmDo(t, http.MethodGet, base+"versions", "")
+	head, body, ok := strings.Cut(versions, "\n---\n")
+	if !ok || !strings.HasPrefix(head, "created_at: ") {
+		t.Fatalf("versions header = %q", versions)
+	}
+	_, otherInfo := npmDo(t, http.MethodGet, base+"info/hello-gem", "")
+	wantBody := fmt.Sprintf("hello-gem 1.0.0 %x\nhello_gem 0.1.0,0.2.0,0.2.0-java %x\n", md5.Sum([]byte(otherInfo)), md5.Sum([]byte(info)))
+	if body != wantBody {
+		t.Fatalf("versions body =\n%q\nwant\n%q", body, wantBody)
+	}
+	if _, names := npmDo(t, http.MethodGet, base+"names", ""); names != "---\nhello-gem\nhello_gem\n" {
+		t.Fatalf("names = %q", names)
+	}
+	if code, got := npmDo(t, http.MethodGet, base+"gems/hello_gem-0.2.0-java.gem", ""); code != http.StatusOK || got != string(gj) {
+		t.Fatalf("download = %d", code)
+	}
+	if code, _ := npmDo(t, http.MethodGet, base+"quick/Marshal.4.8/hello_gem-0.1.0.gemspec.rz", ""); code != http.StatusOK {
+		t.Fatalf("quick spec = %d", code)
+	}
+	if code, _ := npmDo(t, http.MethodGet, base+"info/missing", ""); code != http.StatusNotFound {
+		t.Fatalf("missing info = %d", code)
+	}
+
+	yank := func(form string) int {
+		req, _ := http.NewRequest(http.MethodDelete, base+"api/v1/gems/yank", strings.NewReader(form))
+		req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			t.Fatal(err)
+		}
+		_ = resp.Body.Close()
+		return resp.StatusCode
+	}
+	if c := yank("gem_name=hello_gem&version=0.2.0&platform=java"); c != http.StatusOK {
+		t.Fatalf("yank = %d", c)
+	}
+	if c := yank("gem_name=hello_gem&version=0.2.0&platform=java"); c != http.StatusNotFound {
+		t.Fatalf("second yank = %d, want 404", c)
+	}
+	if c := yank("gem_name=../x&version=1"); c != http.StatusBadRequest {
+		t.Fatalf("bad yank = %d, want 400", c)
+	}
+	if _, info := npmDo(t, http.MethodGet, base+"info/hello_gem", ""); strings.Contains(info, "java") || !strings.Contains(info, "0.2.0 ") {
+		t.Fatalf("info after yank = %q", info)
+	}
+	if code, _ := npmDo(t, http.MethodGet, base+"gems/hello_gem-0.2.0-java.gem", ""); code != http.StatusNotFound {
+		t.Fatalf("yanked download = %d, want 404", code)
+	}
+	if _, v := npmDo(t, http.MethodGet, base+"versions", ""); strings.Contains(v, "java") || !strings.Contains(v, "hello_gem 0.1.0,0.2.0 ") {
+		t.Fatalf("versions after yank = %q", v)
+	}
+	for _, g := range []string{string(gj), string(gj) + "x"} {
+		if code, body := npmDo(t, http.MethodPost, base+"api/v1/gems", g); code != http.StatusConflict || !strings.Contains(body, "yanked") {
+			t.Fatalf("push after yank = %d %q, want 409", code, body)
+		}
+	}
+	if _, info := npmDo(t, http.MethodGet, base+"info/hello_gem", ""); strings.Contains(info, "java") {
+		t.Fatalf("info after rejected re-push = %q", info)
+	}
+
+	if c := yank("gem_name=hello-gem&version=1.0.0"); c != http.StatusOK {
+		t.Fatalf("yank last version = %d", c)
+	}
+	if code, _ := npmDo(t, http.MethodGet, base+"info/hello-gem", ""); code != http.StatusNotFound {
+		t.Fatalf("info for fully yanked gem = %d, want 404", code)
+	}
+	if _, names := npmDo(t, http.MethodGet, base+"names", ""); names != "---\nhello_gem\n" {
+		t.Fatalf("names after yanking every version = %q", names)
+	}
+}
+
+func TestGemsPushRejects(t *testing.T) {
+	h, srv := npmTestServer(t)
+	npmLocal := npmRepo(t, h, models.PackageNPM)
+	g := string(testGemFile(t, "g", "1.0.0", "ruby"))
+	if code, _ := npmDo(t, http.MethodPost, srv.URL+"/api/v1/local/"+npmLocal+"/api/v1/gems", g); code != http.StatusMethodNotAllowed {
+		t.Fatalf("push to npm local = %d, want 405", code)
+	}
+	repo := npmRepo(t, h, models.PackageGems)
+	if code, _ := npmDo(t, http.MethodPost, srv.URL+"/api/v1/local/"+repo+"/other", g); code != http.StatusNotFound {
+		t.Fatalf("push to other path = %d, want 404", code)
+	}
+	old := gemsMaxPushBytes
+	gemsMaxPushBytes = 64
+	defer func() { gemsMaxPushBytes = old }()
+	if code, _ := npmDo(t, http.MethodPost, srv.URL+"/api/v1/local/"+repo+"/api/v1/gems", g); code != http.StatusRequestEntityTooLarge {
+		t.Fatalf("oversized push = %d, want 413", code)
+	}
+}
+
+func TestGemsPushYankSerialised(t *testing.T) {
+	h, srv := npmTestServer(t)
+	repo := npmRepo(t, h, models.PackageGems)
+	base := srv.URL + "/api/v1/local/" + repo + "/"
+	g := string(testGemFile(t, "race", "1.0.0", "ruby"))
+	var wg sync.WaitGroup
+	for i := 0; i < 16; i++ {
+		wg.Add(2)
+		go func() {
+			defer wg.Done()
+			if code, body := npmDo(t, http.MethodPost, base+"api/v1/gems", g); code != http.StatusOK && code != http.StatusConflict {
+				t.Errorf("push = %d: %s", code, body)
+			}
+		}()
+		go func() {
+			defer wg.Done()
+			if code, body := npmDo(t, http.MethodDelete, base+"api/v1/gems/yank?gem_name=race&version=1.0.0", ""); code != http.StatusOK && code != http.StatusNotFound {
+				t.Errorf("yank = %d: %s", code, body)
+			}
+		}()
+	}
+	wg.Wait()
+
+	present := func(p string) bool {
+		f, err := h.db.GetLocalFile(context.Background(), repo, p)
+		if err != nil {
+			t.Fatal(err)
+		}
+		return f != nil
+	}
+	live := []string{"_index/race/race-1.0.0", "gems/race-1.0.0.gem", "quick/Marshal.4.8/race-1.0.0.gemspec.rz"}
+	tomb := present("_yanked/race/race-1.0.0")
+	for _, p := range live {
+		if present(p) == tomb {
+			t.Errorf("tombstoned=%v but %s present=%v", tomb, p, !tomb)
+		}
+	}
+	_, info := npmDo(t, http.MethodGet, base+"info/race", "")
+	if strings.Contains(info, "1.0.0") == tomb {
+		t.Errorf("tombstoned=%v but info = %q", tomb, info)
+	}
+}
+
+func TestGemsLockTimeoutIs503(t *testing.T) {
+	h, srv := npmTestServer(t)
+	repo := npmRepo(t, h, models.PackageGems)
+	base := srv.URL + "/api/v1/local/" + repo + "/"
+	redis, err := cache.NewRedis(testRedis)
+	if err != nil {
+		t.Fatal(err)
+	}
+	token, err := redis.AcquireLock(context.Background(), repo, "_gemlock/busy-1.0.0", time.Minute)
+	if token == "" || err != nil {
+		t.Fatalf("hold lock = %q %v", token, err)
+	}
+	prev := gemsLockWait
+	gemsLockWait = 100 * time.Millisecond
+	t.Cleanup(func() { gemsLockWait = prev })
+
+	if code, _ := npmDo(t, http.MethodPost, base+"api/v1/gems", string(testGemFile(t, "busy", "1.0.0", "ruby"))); code != http.StatusServiceUnavailable {
+		t.Fatalf("push under held lock = %d, want 503", code)
+	}
+	if code, _ := npmDo(t, http.MethodDelete, base+"api/v1/gems/yank?gem_name=busy&version=1.0.0", ""); code != http.StatusServiceUnavailable {
+		t.Fatalf("yank under held lock = %d, want 503", code)
+	}
+	if err := redis.ReleaseLock(context.Background(), repo, "_gemlock/busy-1.0.0", token); err != nil {
+		t.Fatal(err)
+	}
+	if code, body := npmDo(t, http.MethodPost, base+"api/v1/gems", string(testGemFile(t, "busy", "1.0.0", "ruby"))); code != http.StatusOK {
+		t.Fatalf("push after release = %d: %s", code, body)
+	}
+}

internal/api/v1/gems_virtual.go

@@ -0,0 +1,39 @@
+package v1
+
+import (
+	"errors"
+	"log/slog"
+	"net/http"
+
+	"git.unkin.net/unkin/artifactapi/internal/virtual"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+// serveVirtualGems serves the merged compact index and 302s downloads to the
+// member owning that version.
+func (h *ProxyHandler) serveVirtualGems(w http.ResponseWriter, r *http.Request, virt models.Virtual, path, proxyBaseURL string) {
+	var body []byte
+	var loc string
+	var err error
+	if isGemsIndexPath(path) {
+		body, _, err = h.virtualEngine.FetchGems(r.Context(), virt, path)
+	} else {
+		loc, err = h.virtualEngine.GemsRedirect(r.Context(), virt, path, r.URL.RawQuery, proxyBaseURL)
+	}
+	switch {
+	case errors.Is(err, virtual.ErrNotFound):
+		gemsText(w, http.StatusNotFound, "not found")
+	case errors.Is(err, virtual.ErrBadPath):
+		gemsText(w, http.StatusBadRequest, err.Error())
+	case err != nil:
+		slog.Error("virtual gems fetch failed", "virtual", virt.Name, "path", path, "error", err)
+		gemsText(w, http.StatusBadGateway, "bad gateway")
+	case loc != "":
+		w.Header().Set("Cache-Control", "no-store")
+		w.Header().Set("Vary", "Host, X-Forwarded-Proto")
+		http.Redirect(w, r, loc, http.StatusFound)
+	default:
+		w.Header().Set("X-Artifact-Source", "virtual")
+		gemsText(w, http.StatusOK, string(body))
+	}
+}

internal/api/v1/npm_handler_test.go

@@ -15,7 +15,9 @@ import (
 
 	"github.com/go-chi/chi/v5"
 
+	"git.unkin.net/unkin/artifactapi/internal/cache"
 	"git.unkin.net/unkin/artifactapi/internal/database"
+	"git.unkin.net/unkin/artifactapi/internal/proxy"
 	"git.unkin.net/unkin/artifactapi/internal/storage"
 	"git.unkin.net/unkin/artifactapi/internal/testsupport"
 	"git.unkin.net/unkin/artifactapi/internal/virtual"
@@ -25,6 +27,7 @@ import (
 var (
 	testDSN   string
 	testMinio testsupport.MinioConn
+	testRedis string
 )
 
 func TestMain(m *testing.M) {
@@ -38,8 +41,15 @@ func TestMain(m *testing.M) {
 		termPG()
 		os.Exit(m.Run())
 	}
-	testDSN, testMinio = dsn, conn
+	redisURL, termRedis, err := testsupport.StartRedis(ctx)
+	if err != nil {
+		termMinio()
+		termPG()
+		os.Exit(m.Run())
+	}
+	testDSN, testMinio, testRedis = dsn, conn, redisURL
 	code := m.Run()
+	termRedis()
 	termMinio()
 	termPG()
 	os.Exit(code)
@@ -65,7 +75,11 @@ func npmTestServer(t *testing.T) (*ProxyHandler, *httptest.Server) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	h := NewProxyHandler(nil, nil, db, store, nil)
+	redis, err := cache.NewRedis(testRedis)
+	if err != nil {
+		t.Fatal(err)
+	}
+	h := NewProxyHandler(proxy.NewEngine(db, redis, store), nil, db, store, nil)
 	r := chi.NewRouter()
 	r.Mount("/api/v1", h.Routes())
 	srv := httptest.NewServer(r)

internal/api/v1/proxy.go

@@ -8,6 +8,7 @@ import (
 	"log/slog"
 	"net"
 	"net/http"
+	"net/url"
 	"strconv"
 	"strings"
 
@@ -16,6 +17,7 @@ import (
 	v2 "git.unkin.net/unkin/artifactapi/internal/api/v2"
 	"git.unkin.net/unkin/artifactapi/internal/database"
 	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/internal/provider/ansible"
 	"git.unkin.net/unkin/artifactapi/internal/proxy"
 	"git.unkin.net/unkin/artifactapi/internal/storage"
 	"git.unkin.net/unkin/artifactapi/internal/virtual"
@@ -47,8 +49,12 @@ func (h *ProxyHandler) Routes() chi.Router {
 	r.Get("/remote/{remoteName}/*", h.handleProxy)
 	r.Head("/remote/{remoteName}/*", h.handleProxyHead)
 	r.Get("/local/{localName}/*", h.handleLocal)
+	r.Head("/local/{localName}/*", h.handleLocal)
 	r.Put("/local/{localName}/*", h.handleLocalPut)
+	r.Post("/local/{localName}/*", h.handleLocalPost)
+	r.Delete("/local/{localName}/*", h.handleLocalDelete)
 	r.Get("/virtual/{virtualName}/*", h.handleVirtual)
+	r.Head("/virtual/{virtualName}/*", h.handleVirtual)
 	return r
 }
 
@@ -111,7 +117,7 @@ func (h *ProxyHandler) handleProxy(w http.ResponseWriter, r *http.Request) {
 }
 
 func (h *ProxyHandler) serveFetch(w http.ResponseWriter, r *http.Request, remote *models.Remote, prov provider.Provider, path string) {
-	result, err := h.engine.Fetch(r.Context(), *remote, path, prov, r.Header)
+	result, err := h.engine.Fetch(r.Context(), *remote, forwardQuery(prov, path, r.URL.Query()), prov, r.Header)
 	if err != nil {
 		var proxyErr *proxy.ProxyError
 		if errors.As(err, &proxyErr) {
@@ -201,6 +207,15 @@ func (h *ProxyHandler) handleVirtual(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if virt.PackageType == models.PackageGems {
+		h.serveVirtualGems(w, r, *virt, path, proxyBaseURL)
+		return
+	}
+	if virt.PackageType == models.PackageAnsible {
+		h.serveVirtualAnsible(w, r, *virt, path, proxyBaseURL)
+		return
+	}
+
 	loc, ok, err := h.virtualEngine.MemberRedirect(r.Context(), *virt, path, r.URL.RawQuery, proxyBaseURL)
 	if err != nil {
 		http.Error(w, err.Error(), http.StatusBadRequest)
@@ -254,6 +269,27 @@ func (h *ProxyHandler) handleLocal(w http.ResponseWriter, r *http.Request) {
 			return
 		}
 	}
+	if remote.PackageType == models.PackageGems {
+		if isGemsIndexPath(path) {
+			h.serveLocalGemsIndex(w, r, remote, path)
+			return
+		}
+		if strings.HasPrefix(path, gemsIndexPrefix) || strings.HasPrefix(path, gemsYankedPrefix) {
+			http.Error(w, "not found", http.StatusNotFound)
+			return
+		}
+	}
+
+	if remote.PackageType == models.PackageAnsible {
+		if ap := ansible.ParseAPIPath(path); ap.Kind != ansible.APIUnknown {
+			h.serveLocalAnsible(w, r, remote, ap)
+			return
+		}
+		if !strings.HasPrefix(path, ansible.ArtifactPrefix) {
+			http.Error(w, "not found", http.StatusNotFound)
+			return
+		}
+	}
 
 	prov, _ := provider.Get(remote.PackageType)
 	if indexer, ok := prov.(provider.LocalIndexer); ok {
@@ -306,6 +342,25 @@ func Scheme(r *http.Request) string {
 	return "http"
 }
 
+// forwardQuery appends the provider's validated query params to path in a
+// canonical (sorted, single-valued) form, since the result is the cache key.
+func forwardQuery(prov provider.Provider, path string, query url.Values) string {
+	f, ok := prov.(provider.QueryForwarder)
+	if !ok {
+		return path
+	}
+	kept := url.Values{}
+	for name, valid := range f.ForwardedQuery(path) {
+		if v, ok := valid(query.Get(name)); ok {
+			kept.Set(name, v)
+		}
+	}
+	if len(kept) == 0 {
+		return path
+	}
+	return path + "?" + kept.Encode()
+}
+
 // rewriteServed rewrites a cached body for the requesting host and marks the
 // response uncacheable by shared caches, since it varies per Host.
 func rewriteServed(w http.ResponseWriter, r *http.Request, sr provider.ServeRewriter, remote models.Remote, src io.Reader) ([]byte, bool) {

internal/cache/cache_test.go

@@ -61,18 +61,54 @@ func TestTTL(t *testing.T) {
 func TestLock(t *testing.T) {
 	requireRedis(t)
 	ctx := context.Background()
-	ok, err := testRedis.AcquireLock(ctx, "r", "lockpath", time.Minute)
-	if err != nil || !ok {
-		t.Fatalf("first acquire should succeed: %v %v", ok, err)
+	token, err := testRedis.AcquireLock(ctx, "r", "lockpath", time.Minute)
+	if err != nil || token == "" {
+		t.Fatalf("first acquire should succeed: %q %v", token, err)
 	}
-	if ok, _ := testRedis.AcquireLock(ctx, "r", "lockpath", time.Minute); ok {
+	if again, _ := testRedis.AcquireLock(ctx, "r", "lockpath", time.Minute); again != "" {
 		t.Error("second acquire should fail while held")
 	}
-	if err := testRedis.ReleaseLock(ctx, "r", "lockpath"); err != nil {
+	if err := testRedis.ReleaseLock(ctx, "r", "lockpath", "not-the-owner"); err != nil {
 		t.Fatal(err)
 	}
-	if ok, _ := testRedis.AcquireLock(ctx, "r", "lockpath", time.Minute); !ok {
-		t.Error("acquire should succeed after release")
+	if again, _ := testRedis.AcquireLock(ctx, "r", "lockpath", time.Minute); again != "" {
+		t.Error("release with a foreign token must not drop the lock")
+	}
+	if err := testRedis.ReleaseLock(ctx, "r", "lockpath", token); err != nil {
+		t.Fatal(err)
+	}
+	next, _ := testRedis.AcquireLock(ctx, "r", "lockpath", time.Minute)
+	if next == "" {
+		t.Fatal("acquire should succeed after release")
+	}
+	if next == token {
+		t.Error("tokens must differ between holders")
+	}
+}
+
+func TestStaleReleaseKeepsNextHolder(t *testing.T) {
+	requireRedis(t)
+	ctx := context.Background()
+	stale, err := testRedis.AcquireLock(ctx, "r", "stale", 50*time.Millisecond)
+	if err != nil || stale == "" {
+		t.Fatalf("acquire: %q %v", stale, err)
+	}
+	time.Sleep(100 * time.Millisecond)
+	fresh, err := testRedis.AcquireLock(ctx, "r", "stale", time.Minute)
+	if err != nil || fresh == "" {
+		t.Fatalf("acquire after expiry: %q %v", fresh, err)
+	}
+	if err := testRedis.ReleaseLock(ctx, "r", "stale", stale); err != nil {
+		t.Fatal(err)
+	}
+	if again, _ := testRedis.AcquireLock(ctx, "r", "stale", time.Minute); again != "" {
+		t.Fatal("stale holder's release dropped the second holder's lock")
+	}
+	if err := testRedis.ReleaseLock(ctx, "r", "stale", fresh); err != nil {
+		t.Fatal(err)
+	}
+	if again, _ := testRedis.AcquireLock(ctx, "r", "stale", time.Minute); again == "" {
+		t.Error("owner release should free the lock")
 	}
 }
 

internal/cache/redis.go

@@ -2,6 +2,7 @@ package cache
 
 import (
 	"context"
+	"crypto/rand"
 	"fmt"
 	"strings"
 	"time"
@@ -46,15 +47,23 @@ func (r *Redis) CheckTTL(ctx context.Context, remote, path string) (bool, error)
 	return exists > 0, nil
 }
 
-func (r *Redis) AcquireLock(ctx context.Context, remote, path string, ttl time.Duration) (bool, error) {
+// AcquireLock returns the owner token on success and "" when the lock is held.
+func (r *Redis) AcquireLock(ctx context.Context, remote, path string, ttl time.Duration) (string, error) {
 	key := fmt.Sprintf("lock:%s:%s", remote, path)
-	ok, err := r.client.SetNX(ctx, key, "1", ttl).Result()
-	return ok, err
+	token := rand.Text()
+	ok, err := r.client.SetNX(ctx, key, token, ttl).Result()
+	if err != nil || !ok {
+		return "", err
+	}
+	return token, nil
 }
 
-func (r *Redis) ReleaseLock(ctx context.Context, remote, path string) error {
+var releaseScript = redis.NewScript(`if redis.call('get',KEYS[1])==ARGV[1] then return redis.call('del',KEYS[1]) else return 0 end`)
+
+// ReleaseLock deletes the lock only while token still owns it.
+func (r *Redis) ReleaseLock(ctx context.Context, remote, path, token string) error {
 	key := fmt.Sprintf("lock:%s:%s", remote, path)
-	return r.client.Del(ctx, key).Err()
+	return releaseScript.Run(ctx, r.client, []string{key}, token).Err()
 }
 
 // SetETag stores etag for path, or drops the stored one when etag is empty.

internal/database/github_sync_test.go

@@ -207,3 +207,72 @@ func TestGitHubSyncLeaseFailureBackoff(t *testing.T) {
 		t.Fatal("claimed inside freshness window after a successful sync")
 	}
 }
+
+// Deleting a remote drops its sync state, so a recreated remote of the same name
+// starts clean instead of inheriting the old ETag, sync time and retry state.
+func TestGitHubSyncStateDeletedWithRemote(t *testing.T) {
+	requireDB(t)
+	for _, tc := range []struct {
+		table   string
+		pt      models.PackageType
+		claim   func(name string) (bool, string, error)
+		release func(name string, res provider.SyncResult) error
+	}{
+		{"github_rpm_sync_state", models.PackageGitHubRPM,
+			func(n string) (bool, string, error) {
+				return testDB.ClaimGitHubSyncLease(ctx(), n, "r1", time.Hour, time.Minute)
+			},
+			func(n string, res provider.SyncResult) error {
+				return testDB.ReleaseGitHubSyncLease(ctx(), n, "r1", res)
+			}},
+		{"github_deb_sync_state", models.PackageGitHubDeb,
+			func(n string) (bool, string, error) {
+				return testDB.ClaimGitHubDebSyncLease(ctx(), n, "r1", time.Hour, time.Minute)
+			},
+			func(n string, res provider.SyncResult) error {
+				return testDB.ReleaseGitHubDebSyncLease(ctx(), n, "r1", res)
+			}},
+		{"github_alpine_sync_state", models.PackageGitHubAlpine,
+			func(n string) (bool, string, error) {
+				return testDB.ClaimGitHubAlpineSyncLease(ctx(), n, "r1", time.Hour, time.Minute)
+			},
+			func(n string, res provider.SyncResult) error {
+				return testDB.ReleaseGitHubAlpineSyncLease(ctx(), n, "r1", res)
+			}},
+	} {
+		t.Run(tc.table, func(t *testing.T) {
+			name := "gh-recreate-" + time.Now().Format("150405.000000")
+			create := func() {
+				t.Helper()
+				if err := testDB.CreateRemote(ctx(), &models.Remote{
+					Name: name, PackageType: tc.pt, RepoType: models.RepoTypeRemote,
+					BaseURL: "https://api.github.com/repos/acme/tools", ReleasesRemote: "github", MutableTTL: 3600,
+				}); err != nil {
+					t.Fatalf("create remote: %v", err)
+				}
+			}
+
+			create()
+			if ok, _, err := tc.claim(name); err != nil || !ok {
+				t.Fatalf("claim: ok=%v err=%v", ok, err)
+			}
+			if err := tc.release(name, provider.SyncResult{Etag: `"old"`}); err != nil {
+				t.Fatalf("release: %v", err)
+			}
+
+			if err := testDB.DeleteRemote(ctx(), name); err != nil {
+				t.Fatalf("delete remote: %v", err)
+			}
+			var rows int
+			if err := testDB.Pool.QueryRow(ctx(), `SELECT count(*) FROM `+tc.table+` WHERE remote_name = $1`, name).Scan(&rows); err != nil || rows != 0 {
+				t.Fatalf("sync state left after delete: rows=%d err=%v", rows, err)
+			}
+
+			create()
+			ok, etag, err := tc.claim(name)
+			if err != nil || !ok || etag != "" {
+				t.Fatalf("recreated remote claim ok=%v etag=%q err=%v, want a fresh claim with no etag", ok, etag, err)
+			}
+		})
+	}
+}

internal/provider/all/ansible.go

@@ -0,0 +1,3 @@
+package all
+
+import _ "git.unkin.net/unkin/artifactapi/internal/provider/ansible"

internal/provider/alpine/github.go

@@ -372,6 +372,9 @@ func (p *GitHubProvider) scanWithState(ctx context.Context, remote models.Remote
 		return newEtag, false, err
 	}
 
+	// A transiently failed asset fails the scan so the ETag is not advanced and
+	// the retry re-derives it; an invalid package is skipped as no retry fixes it.
+	var failed []error
 	seen := map[string]bool{}
 	for _, rel := range releases {
 		if rel.Draft {
@@ -400,10 +403,14 @@ func (p *GitHubProvider) scanWithState(ctx context.Context, remote models.Remote
 			meta, err := p.deriveAsset(ctx, remote, asset, fp)
 			if err != nil {
 				slog.Warn("github_alpine: derive asset failed", "remote", remote.Name, "asset", asset.Name, "error", err)
+				if !errors.Is(err, provider.ErrInvalidPackage) {
+					failed = append(failed, fmt.Errorf("%s: %w", asset.Name, err))
+				}
 				continue
 			}
 			if err := inserter.InsertAlpineMetadata(ctx, meta); err != nil {
 				slog.Error("github_alpine: insert metadata failed", "remote", remote.Name, "asset", asset.Name, "error", err)
+				failed = append(failed, fmt.Errorf("%s: %w", asset.Name, err))
 				continue
 			}
 			slog.Info("github_alpine: derived asset", "remote", remote.Name, "name", meta.Name, "version", meta.Version, "arch", meta.Arch)
@@ -415,7 +422,7 @@ func (p *GitHubProvider) scanWithState(ctx context.Context, remote models.Remote
 			_ = deleter.DeleteAlpineMetadata(ctx, remote.Name, fp)
 		}
 	}
-	return newEtag, true, nil
+	return newEtag, true, errors.Join(failed...)
 }
 
 type ghRelease struct {
@@ -496,7 +503,7 @@ func (p *GitHubProvider) deriveAsset(ctx context.Context, remote models.Remote,
 		return nil, err
 	}
 	if meta.Name == "" || meta.Arch == "" {
-		return nil, errors.New(".PKGINFO missing pkgname/arch")
+		return nil, fmt.Errorf("%w: .PKGINFO missing pkgname/arch", provider.ErrInvalidPackage)
 	}
 
 	meta.RepoName = remote.Name
@@ -526,13 +533,13 @@ func (p *GitHubProvider) fetchPkginfo(ctx context.Context, remote models.Remote,
 		}
 		meta, complete, perr := pkginfoFromPrefix(body)
 		if perr != nil {
-			return nil, fmt.Errorf("parse apk .PKGINFO: %w", perr)
+			return nil, fmt.Errorf("%w: parse apk .PKGINFO: %w", provider.ErrInvalidPackage, perr)
 		}
 		if complete {
 			return meta, nil
 		}
 		if full || n >= p.headerMax {
-			return nil, fmt.Errorf(".PKGINFO not found within %d bytes of %s", n, downloadURL)
+			return nil, fmt.Errorf("%w: .PKGINFO not found within %d bytes of %s", provider.ErrInvalidPackage, n, downloadURL)
 		}
 		n *= 2
 		if n > p.headerMax {
@@ -594,7 +601,7 @@ func pkginfoFromPrefix(prefix []byte) (meta *provider.AlpineMetadata, complete b
 }
 
 // rangeGet returns the first n bytes of downloadURL. full is true when the
-// response body was shorter than n (i.e. we already have the whole object).
+// response holds the whole object.
 func (p *GitHubProvider) rangeGet(ctx context.Context, remote models.Remote, downloadURL string, n int64) ([]byte, bool, error) {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, downloadURL, nil)
 	if err != nil {
@@ -616,15 +623,9 @@ func (p *GitHubProvider) rangeGet(ctx context.Context, remote models.Remote, dow
 	}
 	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
-		return nil, false, fmt.Errorf("range GET %s: status %d", downloadURL, resp.StatusCode)
+		return nil, false, fmt.Errorf("range GET: %w", provider.AssetStatusError(downloadURL, resp))
 	}
-
-	body, err := io.ReadAll(io.LimitReader(resp.Body, n))
-	if err != nil {
-		return nil, false, err
-	}
-	full := int64(len(body)) < n
-	return body, full, nil
+	return provider.ReadPrefix(resp, n)
 }
 
 // assetPath is the package's location relative to github.com — the path the

internal/provider/alpine/github_test.go

@@ -8,6 +8,7 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -88,15 +89,17 @@ type githubFixture struct {
 	notModHit   int
 	releaseAuth string
 	assetAuth   string
+	assetFail   map[string]int // asset filename -> downloads left to answer 500
 	mu          sync.Mutex
 }
 
 func newGitHubFixture(t *testing.T, withDigest bool) *githubFixture {
 	t.Helper()
 	f := &githubFixture{
-		apkBytes: map[string][]byte{},
-		rangeHit: map[string]int{},
-		fullHit:  map[string]int{},
+		apkBytes:  map[string][]byte{},
+		rangeHit:  map[string]int{},
+		fullHit:   map[string]int{},
+		assetFail: map[string]int{},
 	}
 	f.apkBytes["demo-1.2.3-r0.apk"] = testsupport.MinimalApk("demo", "1.2.3-r0", "x86_64")
 
@@ -146,6 +149,12 @@ func newGitHubFixture(t *testing.T, withDigest bool) *githubFixture {
 		}
 		rng := r.Header.Get("Range")
 		f.mu.Lock()
+		if f.assetFail[name] > 0 {
+			f.assetFail[name]--
+			f.mu.Unlock()
+			http.Error(w, "boom", http.StatusInternalServerError)
+			return
+		}
 		f.assetAuth = r.Header.Get("Authorization")
 		if rng != "" {
 			f.rangeHit[name]++
@@ -495,3 +504,13 @@ func readAPKIndex(t *testing.T, gzBytes []byte) string {
 		}
 	}
 }
+
+func TestGitHubDeriveAssetMissingPkgnameIsInvalid(t *testing.T) {
+	fx := newGitHubFixture(t, true)
+	fx.apkBytes["nameless-1-r0.apk"] = testsupport.MinimalApk("", "1-r0", "x86_64")
+	asset := ghAsset{BrowserDownloadURL: fx.srv.URL + "/acme/tools/releases/download/v1.2.3/nameless-1-r0.apk"}
+	_, err := newTestProvider().deriveAsset(context.Background(), fx.remote(), asset, "fp")
+	if !errors.Is(err, provider.ErrInvalidPackage) {
+		t.Fatalf("want ErrInvalidPackage, got %v", err)
+	}
+}

internal/provider/alpine/syncer_test.go

@@ -308,3 +308,58 @@ func TestSyncerPrimeBypassesRecencyPeriodicDoesNot(t *testing.T) {
 		t.Fatalf("periodic scan ran inside recency window: %d -> %d releases calls", releasesAfterPrime, fx.releasesHit)
 	}
 }
+
+// A transiently failed asset fails the scan: the ETag is not advanced, a retry
+// is scheduled, and the retry against the unchanged release list derives it. An
+// invalid package is skipped instead, since no retry can fix it.
+func TestSyncerFailedAssetRetry(t *testing.T) {
+	for _, tc := range []struct {
+		name      string
+		corrupt   bool
+		wantRetry bool
+	}{
+		{name: "transient", wantRetry: true},
+		{name: "invalid package", corrupt: true},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			fx := newGitHubFixture(t, true)
+			fx.etag = `"v1"`
+			if tc.corrupt {
+				fx.apkBytes["other-9-r0.apk"] = []byte("not a package")
+			} else {
+				fx.apkBytes["other-9-r0.apk"] = testsupport.MinimalApk("other", "9-r0", "aarch64")
+				fx.assetFail["other-9-r0.apk"] = 1
+			}
+			store := newFakeSyncStore()
+			s := newSyncer(store, newTestProvider(), testSyncConfig())
+			remote := fx.remote()
+			bg := context.Background()
+
+			s.process(bg, syncJob{remote: remote, prime: true})
+			_, pending := store.retryAt[remote.Name]
+			if pending != tc.wantRetry {
+				t.Fatalf("retry pending=%v, want %v", pending, tc.wantRetry)
+			}
+			if _, saved := store.etags[remote.Name]; saved == tc.wantRetry {
+				t.Fatalf("etag saved=%v after first scan", saved)
+			}
+			if rows, _ := store.ListAlpineMetadataEntries(bg, remote.Name); len(rows) != 1 {
+				t.Fatalf("healthy asset not served: %d rows", len(rows))
+			}
+			if !tc.wantRetry {
+				return
+			}
+
+			store.mu.Lock()
+			store.retryAt[remote.Name] = time.Now().Add(-time.Second)
+			store.mu.Unlock()
+			s.process(bg, syncJob{remote: remote})
+			if _, pending := store.retryAt[remote.Name]; pending || store.etags[remote.Name] != `"v1"` {
+				t.Fatalf("retry not recorded: pending=%v etag=%q", pending, store.etags[remote.Name])
+			}
+			if rows, _ := store.ListAlpineMetadataEntries(bg, remote.Name); len(rows) != 2 {
+				t.Fatalf("retry did not derive the failed asset: %d rows", len(rows))
+			}
+		})
+	}
+}

internal/provider/ansible/ansible.go

@@ -0,0 +1,139 @@
+// Package ansible proxies an Ansible Galaxy server (v3 collections API):
+// mutable JSON metadata whose links are rewritten back to the remote, plus
+// immutable collection tarballs.
+package ansible
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/auth"
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func init() {
+	provider.Register(&Provider{})
+}
+
+type Provider struct{}
+
+func (p *Provider) Type() models.PackageType { return models.PackageAnsible }
+
+func (p *Provider) Classify(path string) provider.Mutability {
+	if isArtifact(path) {
+		return provider.Immutable
+	}
+	return provider.Mutable
+}
+
+func (p *Provider) ContentType(path string) string {
+	if isArtifact(path) {
+		return "application/gzip"
+	}
+	return "application/json"
+}
+
+func (p *Provider) UpstreamURL(remote models.Remote, path string) string {
+	return strings.TrimRight(remote.BaseURL, "/") + "/" + strings.TrimLeft(path, "/")
+}
+
+const maxPageLimit = 100
+
+// ForwardedQuery keeps limit/offset pagination on metadata paths only.
+func (p *Provider) ForwardedQuery(path string) map[string]provider.QueryValidator {
+	if isArtifact(path) {
+		return nil
+	}
+	return map[string]provider.QueryValidator{"limit": pageLimit, "offset": pageOffset}
+}
+
+func pageOffset(v string) (string, bool) {
+	n, err := strconv.ParseUint(v, 10, 32)
+	return strconv.FormatUint(n, 10), err == nil
+}
+
+func pageLimit(v string) (string, bool) {
+	n, err := strconv.ParseUint(v, 10, 32)
+	if err != nil || n == 0 {
+		return "", false
+	}
+	return strconv.FormatUint(min(n, maxPageLimit), 10), true
+}
+
+// RewriteResponse points href, download_url and links.* at the remote. Links
+// stay root-relative, which ansible-galaxy joins onto the server URL, so the
+// cached body is independent of the request host.
+func (p *Provider) RewriteResponse(body []byte, remote models.Remote, _ string) ([]byte, error) {
+	dec := json.NewDecoder(bytes.NewReader(body))
+	dec.UseNumber()
+	var doc any
+	if err := dec.Decode(&doc); err != nil {
+		return nil, nil
+	}
+	r := rewriter{
+		prefix: provider.RemoteMountPath + url.PathEscape(remote.Name) + "/",
+		base:   strings.TrimRight(remote.BaseURL, "/") + "/",
+	}
+	r.walk(doc)
+	var out bytes.Buffer
+	enc := json.NewEncoder(&out)
+	enc.SetEscapeHTML(false)
+	if err := enc.Encode(doc); err != nil {
+		return nil, err
+	}
+	return out.Bytes(), nil
+}
+
+func (p *Provider) AuthHeaders(_ context.Context, remote models.Remote) (http.Header, error) {
+	return auth.BasicHeaders(remote), nil
+}
+
+type rewriter struct{ prefix, base string }
+
+func (r rewriter) walk(v any) {
+	switch v := v.(type) {
+	case []any:
+		for _, e := range v {
+			r.walk(e)
+		}
+	case map[string]any:
+		for k, e := range v {
+			switch k {
+			case "href", "download_url":
+				v[k] = r.link(e)
+			case "links":
+				if links, ok := e.(map[string]any); ok {
+					for lk, l := range links {
+						links[lk] = r.link(l)
+					}
+					continue
+				}
+			}
+			r.walk(v[k])
+		}
+	}
+}
+
+func (r rewriter) link(v any) any {
+	s, ok := v.(string)
+	switch {
+	case !ok:
+		return v
+	case strings.HasPrefix(s, "/api/"):
+		return r.prefix + s[1:]
+	case strings.HasPrefix(s, r.base):
+		return r.prefix + strings.TrimPrefix(s, r.base)
+	}
+	return s
+}
+
+func isArtifact(path string) bool {
+	path, _, _ = strings.Cut(path, "?")
+	return strings.Contains(path, "/artifacts/") && strings.HasSuffix(path, ".tar.gz")
+}

internal/provider/ansible/ansible_test.go

@@ -0,0 +1,150 @@
+package ansible
+
+import (
+	"encoding/json"
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+const tarball = "api/v3/plugin/ansible/content/published/collections/artifacts/ansible-posix-2.0.0.tar.gz"
+
+func TestClassify(t *testing.T) {
+	p := &Provider{}
+	tests := []struct {
+		path string
+		want provider.Mutability
+	}{
+		{"api/", provider.Mutable},
+		{"api/v3/collections/community/general/versions/?limit=100", provider.Mutable},
+		{"api/v3/collections/community/general/versions/?x=.tar.gz", provider.Mutable},
+		{"api/v3/collections/ansible/posix/versions/2.0.0/", provider.Mutable},
+		{"api/v3/collections/ansible/posix/readme.tar.gz", provider.Mutable},
+		{tarball, provider.Immutable},
+		{tarball + "?limit=1", provider.Immutable},
+	}
+	for _, tt := range tests {
+		if got := p.Classify(tt.path); got != tt.want {
+			t.Errorf("Classify(%q) = %v, want %v", tt.path, got, tt.want)
+		}
+	}
+}
+
+func TestContentTypeIgnoresQuery(t *testing.T) {
+	if got := (&Provider{}).ContentType("api/v3/collections/a/b/versions/?x=.tar.gz"); got != "application/json" {
+		t.Errorf("ContentType = %q, want application/json", got)
+	}
+}
+
+func TestForwardedQuery(t *testing.T) {
+	p := &Provider{}
+	if got := p.ForwardedQuery(tarball); got != nil {
+		t.Errorf("tarball ForwardedQuery = %v, want nil", got)
+	}
+	q := p.ForwardedQuery("api/v3/collections/a/b/versions/")
+	if len(q) != 2 || q["limit"] == nil || q["offset"] == nil {
+		t.Fatalf("metadata ForwardedQuery keys = %v, want limit and offset", q)
+	}
+	tests := []struct {
+		param, in, want string
+		ok              bool
+	}{
+		{"limit", "10", "10", true},
+		{"limit", "007", "7", true},
+		{"limit", "100", "100", true},
+		{"limit", "5000", "100", true},
+		{"limit", "0", "", false},
+		{"limit", "", "", false},
+		{"limit", "-1", "", false},
+		{"limit", "+5", "", false},
+		{"limit", "1e3", "", false},
+		{"limit", "10 ", "", false},
+		{"offset", "0", "0", true},
+		{"offset", "000", "0", true},
+		{"offset", "0100", "100", true},
+		{"offset", "abc", "", false},
+		{"offset", "99999999999999999999", "", false},
+	}
+	for _, tt := range tests {
+		got, ok := q[tt.param](tt.in)
+		if ok != tt.ok || (ok && got != tt.want) {
+			t.Errorf("%s(%q) = %q, %v, want %q, %v", tt.param, tt.in, got, ok, tt.want, tt.ok)
+		}
+	}
+}
+
+func rewrite(t *testing.T, remote models.Remote, body string) map[string]any {
+	t.Helper()
+	out, err := (&Provider{}).RewriteResponse([]byte(body), remote, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	var got map[string]any
+	if err := json.Unmarshal(out, &got); err != nil {
+		t.Fatalf("rewritten body is not JSON: %v: %s", err, out)
+	}
+	return got
+}
+
+func TestRewriteResponse(t *testing.T) {
+	remote := models.Remote{Name: "galaxy", BaseURL: "https://galaxy.ansible.com/"}
+	got := rewrite(t, remote, `{
+		"links": {"next": "/api/v3/collections/a/b/versions/?limit=10&offset=10", "previous": null},
+		"data": [{
+			"href": "/api/v3/collections/a/b/versions/1.0.0/",
+			"download_url": "https://galaxy.ansible.com/api/v3/plugin/ansible/content/published/collections/artifacts/a-b-1.0.0.tar.gz",
+			"description": "/api/ is where it lives",
+			"docs": "/api/v3/not-a-link/",
+			"metadata": {"repository": "https://github.com/a/b", "homepage": "https://galaxy.ansible.com/ui/"}
+		}]
+	}`)
+	pre := "/api/v1/remote/galaxy/"
+	links := got["links"].(map[string]any)
+	if want := pre + "api/v3/collections/a/b/versions/?limit=10&offset=10"; links["next"] != want {
+		t.Errorf("links.next = %v, want %q", links["next"], want)
+	}
+	if links["previous"] != nil {
+		t.Errorf("links.previous = %v, want null", links["previous"])
+	}
+	item := got["data"].([]any)[0].(map[string]any)
+	if want := pre + "api/v3/collections/a/b/versions/1.0.0/"; item["href"] != want {
+		t.Errorf("href = %v, want %q", item["href"], want)
+	}
+	if want := pre + "api/v3/plugin/ansible/content/published/collections/artifacts/a-b-1.0.0.tar.gz"; item["download_url"] != want {
+		t.Errorf("download_url = %v, want %q", item["download_url"], want)
+	}
+	for k, want := range map[string]string{"description": "/api/ is where it lives", "docs": "/api/v3/not-a-link/"} {
+		if item[k] != want {
+			t.Errorf("%s rewritten to %v", k, item[k])
+		}
+	}
+	meta := item["metadata"].(map[string]any)
+	if meta["repository"] != "https://github.com/a/b" || meta["homepage"] != "https://galaxy.ansible.com/ui/" {
+		t.Errorf("unrelated URLs rewritten: %v", meta)
+	}
+}
+
+func TestRewriteResponseEscapesRemoteName(t *testing.T) {
+	got := rewrite(t, models.Remote{Name: `a"b/c`, BaseURL: "https://g/"}, `{"href":"/api/x/"}`)
+	if want := "/api/v1/remote/a%22b%2Fc/api/x/"; got["href"] != want {
+		t.Errorf("href = %v, want %q", got["href"], want)
+	}
+}
+
+func TestRewriteResponseKeepsLargeNumbers(t *testing.T) {
+	out, err := (&Provider{}).RewriteResponse([]byte(`{"n":12345678901234567890}`), models.Remote{Name: "g"}, "")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if want := "{\"n\":12345678901234567890}\n"; string(out) != want {
+		t.Errorf("got %q, want %q", out, want)
+	}
+}
+
+func TestRewriteResponseSkipsNonJSON(t *testing.T) {
+	out, err := (&Provider{}).RewriteResponse([]byte("<html>"), models.Remote{Name: "g"}, "")
+	if err != nil || out != nil {
+		t.Errorf("got %q, %v; want nil, nil", out, err)
+	}
+}

internal/provider/ansible/local.go

@@ -0,0 +1,347 @@
+package ansible
+
+import (
+	"archive/tar"
+	"compress/gzip"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"net/url"
+	"path"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+)
+
+// Local ansible repos speak the Galaxy v3 publish and install API. Per version:
+//   artifacts/<ns>-<name>-<version>.tar.gz  collection tarball (immutable)
+//   _index/<ns>/<name>/<version>            Entry JSON; gates visibility
+
+const (
+	IndexPrefix    = "_index/"
+	ArtifactPrefix = "artifacts/"
+	PublishPath    = "api/v3/artifacts/collections/"
+)
+
+var (
+	NameRe    = regexp.MustCompile(`^[a-z][a-z0-9_]{0,63}$`)
+	VersionRe = regexp.MustCompile(`^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(-[0-9A-Za-z.-]+)?(\+[0-9A-Za-z.-]+)?$`)
+)
+
+var (
+	MaxManifestBytes int64 = 1 << 20
+	MaxScanBytes     int64 = 512 << 20
+)
+
+// Entry is one published collection version.
+type Entry struct {
+	Namespace string          `json:"namespace"`
+	Name      string          `json:"name"`
+	Version   string          `json:"version"`
+	SHA256    string          `json:"sha256"`
+	Size      int64           `json:"size"`
+	Metadata  json.RawMessage `json:"metadata"`
+	CreatedAt time.Time       `json:"created_at"`
+}
+
+func (e Entry) Filename() string { return e.Namespace + "-" + e.Name + "-" + e.Version + ".tar.gz" }
+
+// IndexPath is the entry's hidden index file.
+func (e Entry) IndexPath() string { return IndexPrefix + e.Namespace + "/" + e.Name + "/" + e.Version }
+
+// TaskID names the import task returned on publish.
+func (e Entry) TaskID() string { return e.Namespace + "-" + e.Name + "-" + e.Version }
+
+// ParseCollection reads collection_info from a collection tarball's top-level
+// MANIFEST.json. Every member is checked, so a tarball whose paths or links
+// escape the collection root is rejected even after the manifest.
+func ParseCollection(r io.Reader) (*Entry, error) {
+	zr, err := gzip.NewReader(r)
+	if err != nil {
+		return nil, fmt.Errorf("not a gzip tarball: %w", err)
+	}
+	scan := &io.LimitedReader{R: zr, N: MaxScanBytes}
+	tr := tar.NewReader(scan)
+	var e *Entry
+	for {
+		hdr, err := tr.Next()
+		if scan.N <= 0 {
+			return nil, errors.New("collection exceeds decompressed size limit")
+		}
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return nil, fmt.Errorf("read tarball: %w", err)
+		}
+		name, err := memberPath(hdr)
+		if err != nil {
+			return nil, err
+		}
+		if name != "MANIFEST.json" || hdr.Typeflag != tar.TypeReg {
+			continue
+		}
+		if e != nil {
+			return nil, errors.New("duplicate MANIFEST.json")
+		}
+		if e, err = parseManifest(io.LimitReader(tr, MaxManifestBytes+1)); err != nil {
+			return nil, err
+		}
+	}
+	if e == nil {
+		return nil, errors.New("no MANIFEST.json in collection tarball")
+	}
+	return e, nil
+}
+
+// memberPath returns hdr's cleaned name, rejecting absolute or escaping
+// paths and links, and anything but files, directories and symlinks.
+func memberPath(hdr *tar.Header) (string, error) {
+	name := path.Clean(strings.TrimPrefix(hdr.Name, "./"))
+	if escapes(name) {
+		return "", fmt.Errorf("tarball member %q escapes the collection root", hdr.Name)
+	}
+	switch hdr.Typeflag {
+	case tar.TypeReg, tar.TypeDir:
+	case tar.TypeSymlink:
+		if path.IsAbs(hdr.Linkname) || escapes(path.Join(path.Dir(name), hdr.Linkname)) {
+			return "", fmt.Errorf("tarball symlink %q escapes the collection root", hdr.Name)
+		}
+	default:
+		return "", fmt.Errorf("tarball member %q has unsupported type %q", hdr.Name, hdr.Typeflag)
+	}
+	return name, nil
+}
+
+func escapes(p string) bool {
+	return path.IsAbs(p) || p == ".." || strings.HasPrefix(p, "../") || strings.Contains(p, "\\")
+}
+
+func parseManifest(r io.Reader) (*Entry, error) {
+	raw, err := io.ReadAll(r)
+	if err != nil {
+		return nil, fmt.Errorf("read MANIFEST.json: %w", err)
+	}
+	if int64(len(raw)) > MaxManifestBytes {
+		return nil, fmt.Errorf("MANIFEST.json exceeds %d bytes", MaxManifestBytes)
+	}
+	var doc struct {
+		CollectionInfo map[string]json.RawMessage `json:"collection_info"`
+	}
+	if err := json.Unmarshal(raw, &doc); err != nil || doc.CollectionInfo == nil {
+		return nil, errors.New("MANIFEST.json has no collection_info")
+	}
+	info := doc.CollectionInfo
+	e := &Entry{}
+	for k, dst := range map[string]*string{"namespace": &e.Namespace, "name": &e.Name, "version": &e.Version} {
+		if err := json.Unmarshal(info[k], dst); err != nil {
+			return nil, fmt.Errorf("collection_info.%s is not a string", k)
+		}
+	}
+	if !NameRe.MatchString(e.Namespace) || !NameRe.MatchString(e.Name) || !VersionRe.MatchString(e.Version) {
+		return nil, fmt.Errorf("invalid collection %q.%q version %q", e.Namespace, e.Name, e.Version)
+	}
+	deps := map[string]string{}
+	if d := info["dependencies"]; len(d) > 0 && string(d) != "null" {
+		if err := json.Unmarshal(d, &deps); err != nil {
+			return nil, errors.New("collection_info.dependencies must map collection names to version ranges")
+		}
+	}
+	for k := range deps {
+		ns, n, ok := strings.Cut(k, ".")
+		if !ok || !NameRe.MatchString(ns) || !NameRe.MatchString(n) {
+			return nil, fmt.Errorf("invalid dependency %q", k)
+		}
+	}
+	info["dependencies"], _ = json.Marshal(deps)
+	if e.Metadata, err = json.Marshal(info); err != nil {
+		return nil, err
+	}
+	return e, nil
+}
+
+// APIPath is a parsed Galaxy v3 request path below a repo.
+type APIPath struct {
+	Kind                     APIKind
+	Namespace, Name, Version string
+	TaskID                   string
+}
+
+type APIKind int
+
+const (
+	APIUnknown APIKind = iota
+	APIRoot
+	APICollection
+	APIVersions
+	APIVersion
+	APIImport
+)
+
+// ParseAPIPath parses api/, api/v3/collections/<ns>/<name>/[versions/[<v>/]]
+// and api/v3/imports/collections/<id>/, with or without trailing slashes.
+func ParseAPIPath(p string) APIPath {
+	p = strings.TrimSuffix(p, "/")
+	if p == "api" {
+		return APIPath{Kind: APIRoot}
+	}
+	if id, ok := strings.CutPrefix(p, "api/v3/imports/collections/"); ok && id != "" && !strings.Contains(id, "/") {
+		return APIPath{Kind: APIImport, TaskID: id}
+	}
+	rest, ok := strings.CutPrefix(p, "api/v3/collections/")
+	if !ok {
+		return APIPath{}
+	}
+	segs := strings.Split(rest, "/")
+	if len(segs) < 2 || !NameRe.MatchString(segs[0]) || !NameRe.MatchString(segs[1]) {
+		return APIPath{}
+	}
+	ap := APIPath{Namespace: segs[0], Name: segs[1]}
+	switch {
+	case len(segs) == 2:
+		ap.Kind = APICollection
+	case len(segs) == 3 && segs[2] == "versions":
+		ap.Kind = APIVersions
+	case len(segs) == 4 && segs[2] == "versions" && VersionRe.MatchString(segs[3]):
+		ap.Kind, ap.Version = APIVersion, segs[3]
+	default:
+		return APIPath{}
+	}
+	return ap
+}
+
+// Root is the API root ansible-galaxy discovers.
+func Root() map[string]any {
+	return map[string]any{"available_versions": map[string]string{"v3": "v3/"}}
+}
+
+func CollectionPath(ns, name string) string { return "/api/v3/collections/" + ns + "/" + name + "/" }
+
+func VersionPath(ns, name, version string) string {
+	return CollectionPath(ns, name) + "versions/" + url.PathEscape(version) + "/"
+}
+
+// VersionRef is one entry of a versions list.
+type VersionRef struct {
+	Version   string `json:"version"`
+	CreatedAt string `json:"created_at,omitempty"`
+	UpdatedAt string `json:"updated_at,omitempty"`
+}
+
+func (e Entry) Ref() VersionRef {
+	t := e.CreatedAt.UTC().Format(time.RFC3339Nano)
+	return VersionRef{Version: e.Version, CreatedAt: t, UpdatedAt: t}
+}
+
+// CollectionDoc describes a collection from its versions; base is the repo
+// URL the hrefs are built on.
+func CollectionDoc(base, ns, name string, refs []VersionRef) map[string]any {
+	var created, updated time.Time
+	for _, r := range refs {
+		if t, err := time.Parse(time.RFC3339Nano, r.CreatedAt); err == nil && (created.IsZero() || t.Before(created)) {
+			created = t
+		}
+		if t, err := time.Parse(time.RFC3339Nano, r.UpdatedAt); err == nil && t.After(updated) {
+			updated = t
+		}
+	}
+	return map[string]any{
+		"href":         base + CollectionPath(ns, name),
+		"namespace":    ns,
+		"name":         name,
+		"deprecated":   false,
+		"versions_url": base + CollectionPath(ns, name) + "versions/",
+		"created_at":   formatTime(created),
+		"updated_at":   formatTime(updated),
+	}
+}
+
+func formatTime(t time.Time) string {
+	if t.IsZero() {
+		return ""
+	}
+	return t.UTC().Format(time.RFC3339Nano)
+}
+
+// Page reads limit/offset as the remote forwards them, defaulting to 100/0.
+func Page(q url.Values) (limit, offset int) {
+	limit, offset = maxPageLimit, 0
+	if v, ok := pageLimit(q.Get("limit")); ok {
+		limit, _ = strconv.Atoi(v)
+	}
+	if v, ok := pageOffset(q.Get("offset")); ok {
+		offset, _ = strconv.Atoi(v)
+	}
+	return limit, offset
+}
+
+// VersionsPage is one page of refs in Galaxy v3 list form. Links are
+// root-relative like Galaxy's, since ansible-galaxy splices them onto the
+// server URL.
+func VersionsPage(base, ns, name string, refs []VersionRef, limit, offset int) map[string]any {
+	list := rootPath(base) + CollectionPath(ns, name) + "versions/"
+	link := func(off int) any {
+		return list + "?" + url.Values{"limit": {strconv.Itoa(limit)}, "offset": {strconv.Itoa(off)}}.Encode()
+	}
+	offset = min(offset, len(refs))
+	var previous, next any
+	if offset > 0 {
+		previous = link(max(offset-limit, 0))
+	}
+	if offset+limit < len(refs) {
+		next = link(offset + limit)
+	}
+	data := []map[string]any{}
+	for _, r := range refs[offset:min(offset+limit, len(refs))] {
+		data = append(data, map[string]any{
+			"version":    r.Version,
+			"href":       base + VersionPath(ns, name, r.Version),
+			"created_at": r.CreatedAt,
+			"updated_at": r.UpdatedAt,
+			"marks":      []string{},
+		})
+	}
+	return map[string]any{
+		"meta":  map[string]any{"count": len(refs)},
+		"links": map[string]any{"first": link(0), "previous": previous, "next": next, "last": link(max(len(refs)-1, 0) / limit * limit)},
+		"data":  data,
+	}
+}
+
+// rootPath drops the scheme and host from base.
+func rootPath(base string) string {
+	if u, err := url.Parse(base); err == nil {
+		return u.EscapedPath()
+	}
+	return base
+}
+
+// VersionDoc is a version's detail; the tarball is served from the repo at
+// artifacts/<filename>.
+func VersionDoc(base string, e Entry) map[string]any {
+	t := e.CreatedAt.UTC().Format(time.RFC3339Nano)
+	return map[string]any{
+		"href":         base + VersionPath(e.Namespace, e.Name, e.Version),
+		"namespace":    map[string]string{"name": e.Namespace},
+		"collection":   map[string]string{"name": e.Name},
+		"name":         e.Name,
+		"version":      e.Version,
+		"download_url": base + "/" + ArtifactPrefix + e.Filename(),
+		"artifact":     map[string]any{"filename": e.Filename(), "sha256": e.SHA256, "size": e.Size},
+		"metadata":     e.Metadata,
+		"signatures":   []string{},
+		"created_at":   t,
+		"updated_at":   t,
+	}
+}
+
+// ImportTask is a finished import: publishing completes synchronously.
+func ImportTask(e Entry) map[string]any {
+	t := e.CreatedAt.UTC().Format(time.RFC3339Nano)
+	return map[string]any{
+		"id": e.TaskID(), "state": "completed", "created_at": t, "started_at": t, "finished_at": t,
+		"messages": []any{}, "error": nil,
+	}
+}

internal/provider/ansible/local_test.go

@@ -0,0 +1,256 @@
+package ansible
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"encoding/json"
+	"fmt"
+	"net/url"
+	"strings"
+	"testing"
+)
+
+type member struct {
+	hdr  tar.Header
+	body string
+}
+
+func collectionTar(t *testing.T, members ...member) []byte {
+	t.Helper()
+	var buf bytes.Buffer
+	zw := gzip.NewWriter(&buf)
+	tw := tar.NewWriter(zw)
+	for _, m := range members {
+		h := m.hdr
+		if h.Typeflag == 0 {
+			h.Typeflag = tar.TypeReg
+		}
+		if h.Typeflag == tar.TypeReg {
+			h.Size = int64(len(m.body))
+		}
+		h.Mode = 0o644
+		if err := tw.WriteHeader(&h); err != nil {
+			t.Fatal(err)
+		}
+		_, _ = tw.Write([]byte(m.body))
+	}
+	_ = tw.Close()
+	_ = zw.Close()
+	return buf.Bytes()
+}
+
+func manifest(ns, name, version, deps string) member {
+	return member{tar.Header{Name: "MANIFEST.json"}, `{"collection_info":{"namespace":"` + ns + `","name":"` + name +
+		`","version":"` + version + `","authors":["a"],"dependencies":` + deps + `}}`}
+}
+
+func TestParseCollection(t *testing.T) {
+	e, err := ParseCollection(bytes.NewReader(collectionTar(t,
+		member{tar.Header{Name: "plugins/", Typeflag: tar.TypeDir}, ""},
+		member{tar.Header{Name: "plugins/modules/hello.py"}, "x"},
+		member{tar.Header{Name: "docs/link", Typeflag: tar.TypeSymlink, Linkname: "../plugins/modules/hello.py"}, ""},
+		manifest("unkin", "e2e_hello", "1.0.0-rc.1+b1", `{"ansible.posix":">=1.0.0"}`),
+	)))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if e.Namespace != "unkin" || e.Name != "e2e_hello" || e.Version != "1.0.0-rc.1+b1" || e.Filename() != "unkin-e2e_hello-1.0.0-rc.1+b1.tar.gz" {
+		t.Fatalf("entry = %+v", e)
+	}
+	var md struct {
+		Authors      []string          `json:"authors"`
+		Dependencies map[string]string `json:"dependencies"`
+	}
+	if err := json.Unmarshal(e.Metadata, &md); err != nil || md.Dependencies["ansible.posix"] != ">=1.0.0" || len(md.Authors) != 1 {
+		t.Fatalf("metadata = %s (%v)", e.Metadata, err)
+	}
+
+	e, err = ParseCollection(bytes.NewReader(collectionTar(t, manifest("a", "b", "1.0.0", "null"))))
+	if err != nil || !strings.Contains(string(e.Metadata), `"dependencies":{}`) {
+		t.Fatalf("null dependencies = %s (%v), want {}", e.Metadata, err)
+	}
+}
+
+func TestParseCollectionRejects(t *testing.T) {
+	ok := manifest("a", "b", "1.0.0", "{}")
+	tests := []struct {
+		name    string
+		members []member
+		want    string
+	}{
+		{"no manifest", []member{{tar.Header{Name: "README.md"}, "x"}}, "no MANIFEST.json"},
+		{"nested manifest only", []member{{tar.Header{Name: "x/MANIFEST.json"}, ok.body}}, "no MANIFEST.json"},
+		{"dotdot", []member{ok, {tar.Header{Name: "../evil"}, "x"}}, "escapes"},
+		{"dotdot after clean", []member{ok, {tar.Header{Name: "a/../../evil"}, "x"}}, "escapes"},
+		{"absolute", []member{ok, {tar.Header{Name: "/etc/passwd"}, "x"}}, "escapes"},
+		{"symlink escape", []member{ok, {tar.Header{Name: "a/l", Typeflag: tar.TypeSymlink, Linkname: "../../x"}, ""}}, "symlink"},
+		{"absolute symlink", []member{ok, {tar.Header{Name: "l", Typeflag: tar.TypeSymlink, Linkname: "/etc"}, ""}}, "symlink"},
+		{"hardlink", []member{ok, {tar.Header{Name: "l", Typeflag: tar.TypeLink, Linkname: "MANIFEST.json"}, ""}}, "unsupported type"},
+		{"duplicate manifest", []member{ok, ok}, "duplicate"},
+		{"bad namespace", []member{manifest("Bad", "b", "1.0.0", "{}")}, "invalid collection"},
+		{"bad version", []member{manifest("a", "b", "1.0", "{}")}, "invalid collection"},
+		{"bad dependency", []member{manifest("a", "b", "1.0.0", `{"nodot":"*"}`)}, "invalid dependency"},
+		{"list dependencies", []member{manifest("a", "b", "1.0.0", `["x.y"]`)}, "dependencies must map"},
+		{"huge manifest", []member{{tar.Header{Name: "MANIFEST.json"}, strings.Repeat(" ", int(MaxManifestBytes)+1)}}, "exceeds"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			_, err := ParseCollection(bytes.NewReader(collectionTar(t, tt.members...)))
+			if err == nil || !strings.Contains(err.Error(), tt.want) {
+				t.Fatalf("err = %v, want %q", err, tt.want)
+			}
+		})
+	}
+	if _, err := ParseCollection(strings.NewReader("not gzip")); err == nil {
+		t.Error("non-gzip input accepted")
+	}
+}
+
+func TestParseCollectionScanLimit(t *testing.T) {
+	old := MaxScanBytes
+	MaxScanBytes = 4096
+	defer func() { MaxScanBytes = old }()
+	_, err := ParseCollection(bytes.NewReader(collectionTar(t,
+		member{tar.Header{Name: "big"}, strings.Repeat("x", 8192)},
+		manifest("a", "b", "1.0.0", "{}"),
+	)))
+	if err == nil || !strings.Contains(err.Error(), "decompressed size limit") {
+		t.Fatalf("err = %v, want decompressed size limit", err)
+	}
+}
+
+func TestParseAPIPath(t *testing.T) {
+	tests := []struct {
+		in   string
+		want APIPath
+	}{
+		{"api", APIPath{Kind: APIRoot}},
+		{"api/", APIPath{Kind: APIRoot}},
+		{"api/v3/collections/unkin/e2e_hello/", APIPath{Kind: APICollection, Namespace: "unkin", Name: "e2e_hello"}},
+		{"api/v3/collections/unkin/e2e_hello/versions", APIPath{Kind: APIVersions, Namespace: "unkin", Name: "e2e_hello"}},
+		{"api/v3/collections/unkin/e2e_hello/versions/1.0.0/", APIPath{Kind: APIVersion, Namespace: "unkin", Name: "e2e_hello", Version: "1.0.0"}},
+		{"api/v3/imports/collections/unkin-e2e_hello-1.0.0/", APIPath{Kind: APIImport, TaskID: "unkin-e2e_hello-1.0.0"}},
+		{"api/v3/collections/unkin/e2e_hello/versions/1.0/", APIPath{}},
+		{"api/v3/collections/../x/", APIPath{}},
+		{"api/v3/collections/unkin/e2e_hello/versions/1.0.0/extra/", APIPath{}},
+		{"artifacts/unkin-e2e_hello-1.0.0.tar.gz", APIPath{}},
+		{"api/v3/imports/collections/a/b/", APIPath{}},
+	}
+	for _, tt := range tests {
+		if got := ParseAPIPath(tt.in); got != tt.want {
+			t.Errorf("ParseAPIPath(%q) = %+v, want %+v", tt.in, got, tt.want)
+		}
+	}
+}
+
+func TestVersionsPage(t *testing.T) {
+	refs := []VersionRef{{Version: "3.0.0"}, {Version: "2.0.0"}, {Version: "1.0.0"}}
+	list := "/r/api/v3/collections/a/b/versions/"
+	links := func(p map[string]any) map[string]any { return p["links"].(map[string]any) }
+	versions := func(p map[string]any) (out []string) {
+		for _, d := range p["data"].([]map[string]any) {
+			out = append(out, d["version"].(string))
+		}
+		return out
+	}
+
+	p := VersionsPage("https://h/r", "a", "b", refs, 2, 0)
+	if got := versions(p); strings.Join(got, ",") != "3.0.0,2.0.0" {
+		t.Fatalf("page 1 = %v", got)
+	}
+	if l := links(p); l["previous"] != nil || l["next"] != list+"?limit=2&offset=2" || l["last"] != list+"?limit=2&offset=2" {
+		t.Fatalf("page 1 links = %v", l)
+	}
+	if p["meta"].(map[string]any)["count"] != 3 {
+		t.Fatalf("count = %v", p["meta"])
+	}
+
+	p = VersionsPage("https://h/r", "a", "b", refs, 2, 2)
+	if got := versions(p); strings.Join(got, ",") != "1.0.0" {
+		t.Fatalf("page 2 = %v", got)
+	}
+	if l := links(p); l["next"] != nil || l["previous"] != list+"?limit=2&offset=0" {
+		t.Fatalf("page 2 links = %v", l)
+	}
+
+	if got := versions(VersionsPage("", "a", "b", refs, 2, 99)); len(got) != 0 {
+		t.Fatalf("offset past end = %v, want empty", got)
+	}
+}
+
+// TestVersionsPageFollow pages through more than 100 versions the way
+// ansible-galaxy does: old clients splice next onto the versions URL in place
+// of its path, new ones urljoin it onto the server.
+func TestVersionsPageFollow(t *testing.T) {
+	var refs []VersionRef
+	for i := 104; i >= 0; i-- {
+		refs = append(refs, VersionRef{Version: fmt.Sprintf("1.0.%d", i)})
+	}
+	server := "https://h:8443/api/v1/local/r%2Bx/"
+	base := strings.TrimSuffix(server, "/")
+	versionsURL := server + "api/v3/collections/a/b/versions/"
+	for _, follow := range map[string]func(string) string{
+		"replace": func(link string) string {
+			u, _ := url.Parse(versionsURL)
+			return strings.Replace(versionsURL, u.EscapedPath(), link, 1)
+		},
+		"urljoin": func(link string) string {
+			s, _ := url.Parse(server)
+			l, _ := url.Parse(link)
+			return s.ResolveReference(l).String()
+		},
+	} {
+		var got []string
+		next := versionsURL + "?limit=100"
+		for pages := 0; next != ""; pages++ {
+			if pages > 3 {
+				t.Fatal("pagination does not terminate")
+			}
+			u, err := url.Parse(next)
+			if err != nil || u.Host != "h:8443" || !strings.HasPrefix(u.EscapedPath(), "/api/v1/local/r%2Bx/api/v3/") {
+				t.Fatalf("followed link %q is not on the server", next)
+			}
+			limit, offset := Page(u.Query())
+			p := VersionsPage(base, "a", "b", refs, limit, offset)
+			for _, d := range p["data"].([]map[string]any) {
+				got = append(got, d["version"].(string))
+			}
+			next = ""
+			if l, ok := p["links"].(map[string]any)["next"].(string); ok {
+				next = follow(l)
+			}
+		}
+		if len(got) != 105 || got[0] != "1.0.104" || got[104] != "1.0.0" {
+			t.Fatalf("collected %d versions, first %v", len(got), got[:1])
+		}
+	}
+}
+
+func TestCollectionDocTimes(t *testing.T) {
+	d := CollectionDoc("", "a", "b", []VersionRef{
+		{CreatedAt: "2026-01-01T00:00:05Z", UpdatedAt: "2026-01-01T00:00:05Z"},
+		{CreatedAt: "2026-01-01T00:00:05.5Z", UpdatedAt: "2026-01-01T00:00:05.5Z"},
+		{CreatedAt: "2026-01-01T00:00:04.9Z", UpdatedAt: "2026-01-01T00:00:04.9Z"},
+	})
+	if d["created_at"] != "2026-01-01T00:00:04.9Z" || d["updated_at"] != "2026-01-01T00:00:05.5Z" {
+		t.Fatalf("created/updated = %v/%v", d["created_at"], d["updated_at"])
+	}
+}
+
+func TestPage(t *testing.T) {
+	for _, tt := range []struct {
+		q             string
+		limit, offset int
+	}{
+		{"", 100, 0},
+		{"limit=5&offset=10", 5, 10},
+		{"limit=5000", 100, 0},
+		{"limit=0&offset=-1", 100, 0},
+	} {
+		q, _ := url.ParseQuery(tt.q)
+		if l, o := Page(q); l != tt.limit || o != tt.offset {
+			t.Errorf("Page(%q) = %d,%d want %d,%d", tt.q, l, o, tt.limit, tt.offset)
+		}
+	}
+}

internal/provider/cap_query_forwarder.go

@@ -0,0 +1,12 @@
+package provider
+
+// QueryForwarder is a remote provider whose upstream answers depend on the
+// query string (e.g. paginated JSON APIs). Only the named params for path are
+// forwarded upstream and kept in the cache key, each as the canonical value
+// its validator returns; a value the validator rejects is dropped.
+type QueryForwarder interface {
+	ForwardedQuery(path string) map[string]QueryValidator
+}
+
+// QueryValidator canonicalises a raw query value, reporting false to drop it.
+type QueryValidator func(v string) (string, bool)

internal/provider/deb/github.go

@@ -333,6 +333,9 @@ func (p *GitHubProvider) scanWithState(ctx context.Context, remote models.Remote
 		return newEtag, false, err
 	}
 
+	// A transiently failed asset fails the scan so the ETag is not advanced and
+	// the retry re-derives it; an invalid package is skipped as no retry fixes it.
+	var failed []error
 	seen := map[string]bool{}
 	for _, rel := range releases {
 		if rel.Draft {
@@ -361,10 +364,14 @@ func (p *GitHubProvider) scanWithState(ctx context.Context, remote models.Remote
 			meta, err := p.deriveAsset(ctx, remote, asset, fp)
 			if err != nil {
 				slog.Warn("github_deb: derive asset failed", "remote", remote.Name, "asset", asset.Name, "error", err)
+				if !errors.Is(err, provider.ErrInvalidPackage) {
+					failed = append(failed, fmt.Errorf("%s: %w", asset.Name, err))
+				}
 				continue
 			}
 			if err := store.InsertDebMetadata(ctx, meta); err != nil {
 				slog.Error("github_deb: insert metadata failed", "remote", remote.Name, "asset", asset.Name, "error", err)
+				failed = append(failed, fmt.Errorf("%s: %w", asset.Name, err))
 				continue
 			}
 			slog.Info("github_deb: derived asset", "remote", remote.Name, "name", meta.Name, "version", meta.Version, "arch", meta.Architecture)
@@ -376,7 +383,7 @@ func (p *GitHubProvider) scanWithState(ctx context.Context, remote models.Remote
 			_ = store.DeleteDebMetadata(ctx, remote.Name, fp)
 		}
 	}
-	return newEtag, true, nil
+	return newEtag, true, errors.Join(failed...)
 }
 
 type ghRelease struct {
@@ -468,7 +475,7 @@ func (p *GitHubProvider) deriveAsset(ctx context.Context, remote models.Remote,
 		Size:         asset.Size,
 	}
 	if meta.Name == "" {
-		return nil, errors.New("control missing Package field")
+		return nil, fmt.Errorf("%w: control missing Package field", provider.ErrInvalidPackage)
 	}
 
 	// The Packages SHA256 must be the sha256 of the whole .deb. Prefer GitHub's
@@ -503,13 +510,13 @@ func (p *GitHubProvider) fetchControl(ctx context.Context, remote models.Remote,
 		}
 		control, complete, perr := controlFromPrefix(body)
 		if perr != nil {
-			return "", fmt.Errorf("parse deb control: %w", perr)
+			return "", fmt.Errorf("%w: parse deb control: %w", provider.ErrInvalidPackage, perr)
 		}
 		if complete {
 			return control, nil
 		}
 		if full || n >= p.headerMax {
-			return "", fmt.Errorf("control.tar not found within %d bytes of %s", n, downloadURL)
+			return "", fmt.Errorf("%w: control.tar not found within %d bytes of %s", provider.ErrInvalidPackage, n, downloadURL)
 		}
 		n *= 2
 		if n > p.headerMax {
@@ -567,7 +574,7 @@ func controlFromPrefix(prefix []byte) (control string, complete bool, err error)
 }
 
 // rangeGet returns the first n bytes of downloadURL. full is true when the
-// response body was shorter than n (i.e. we already have the whole object).
+// response holds the whole object.
 func (p *GitHubProvider) rangeGet(ctx context.Context, remote models.Remote, downloadURL string, n int64) ([]byte, bool, error) {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, downloadURL, nil)
 	if err != nil {
@@ -589,15 +596,9 @@ func (p *GitHubProvider) rangeGet(ctx context.Context, remote models.Remote, dow
 	}
 	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
-		return nil, false, fmt.Errorf("range GET %s: status %d", downloadURL, resp.StatusCode)
+		return nil, false, fmt.Errorf("range GET: %w", provider.AssetStatusError(downloadURL, resp))
 	}
-
-	body, err := io.ReadAll(io.LimitReader(resp.Body, n))
-	if err != nil {
-		return nil, false, err
-	}
-	full := int64(len(body)) < n
-	return body, full, nil
+	return provider.ReadPrefix(resp, n)
 }
 
 func (p *GitHubProvider) computeSHA256(ctx context.Context, remote models.Remote, downloadURL string) (string, error) {
@@ -620,7 +621,7 @@ func (p *GitHubProvider) computeSHA256(ctx context.Context, remote models.Remote
 	}
 	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {
-		return "", fmt.Errorf("GET %s: status %d", downloadURL, resp.StatusCode)
+		return "", fmt.Errorf("GET: %w", provider.AssetStatusError(downloadURL, resp))
 	}
 
 	h := sha256.New()

internal/provider/deb/github_test.go

@@ -7,6 +7,7 @@ import (
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -81,15 +82,17 @@ type githubFixture struct {
 	notModHit   int
 	releaseAuth string
 	assetAuth   string
+	assetFail   map[string]int // asset filename -> downloads left to answer 500
 	mu          sync.Mutex
 }
 
 func newGitHubFixture(t *testing.T, withDigest bool) *githubFixture {
 	t.Helper()
 	f := &githubFixture{
-		debBytes: map[string][]byte{},
-		rangeHit: map[string]int{},
-		fullHit:  map[string]int{},
+		debBytes:  map[string][]byte{},
+		rangeHit:  map[string]int{},
+		fullHit:   map[string]int{},
+		assetFail: map[string]int{},
 	}
 	f.debBytes["demo_1.2-3_amd64.deb"] = testsupport.MinimalDeb("demo", "1.2-3", "amd64")
 
@@ -139,6 +142,12 @@ func newGitHubFixture(t *testing.T, withDigest bool) *githubFixture {
 		}
 		rng := r.Header.Get("Range")
 		f.mu.Lock()
+		if f.assetFail[name] > 0 {
+			f.assetFail[name]--
+			f.mu.Unlock()
+			http.Error(w, "boom", http.StatusInternalServerError)
+			return
+		}
 		f.assetAuth = r.Header.Get("Authorization")
 		if rng != "" {
 			f.rangeHit[name]++
@@ -460,3 +469,13 @@ func TestGitHubAssetPatternFilter(t *testing.T) {
 		t.Fatalf("pattern filter failed, rows=%+v", rows)
 	}
 }
+
+func TestGitHubDeriveAssetMissingPackageIsInvalid(t *testing.T) {
+	fx := newGitHubFixture(t, true)
+	fx.debBytes["nameless_1_amd64.deb"] = testsupport.MinimalDeb("", "1", "amd64")
+	asset := ghAsset{BrowserDownloadURL: fx.srv.URL + "/acme/tools/releases/download/v1.2-3/nameless_1_amd64.deb", Digest: "sha256:00"}
+	_, err := newTestProvider().deriveAsset(context.Background(), fx.remote(), asset, "fp")
+	if !errors.Is(err, provider.ErrInvalidPackage) {
+		t.Fatalf("want ErrInvalidPackage, got %v", err)
+	}
+}

internal/provider/deb/syncer_test.go

@@ -308,3 +308,58 @@ func TestSyncerPrimeBypassesRecencyPeriodicDoesNot(t *testing.T) {
 		t.Fatalf("periodic scan ran inside recency window: %d -> %d releases calls", releasesAfterPrime, fx.releasesHit)
 	}
 }
+
+// A transiently failed asset fails the scan: the ETag is not advanced, a retry
+// is scheduled, and the retry against the unchanged release list derives it. An
+// invalid package is skipped instead, since no retry can fix it.
+func TestSyncerFailedAssetRetry(t *testing.T) {
+	for _, tc := range []struct {
+		name      string
+		corrupt   bool
+		wantRetry bool
+	}{
+		{name: "transient", wantRetry: true},
+		{name: "invalid package", corrupt: true},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			fx := newGitHubFixture(t, true)
+			fx.etag = `"v1"`
+			if tc.corrupt {
+				fx.debBytes["other_9-9_arm64.deb"] = []byte("not a package")
+			} else {
+				fx.debBytes["other_9-9_arm64.deb"] = testsupport.MinimalDeb("other", "9-9", "arm64")
+				fx.assetFail["other_9-9_arm64.deb"] = 1
+			}
+			store := newFakeSyncStore()
+			s := newSyncer(store, newTestProvider(), testSyncConfig())
+			remote := fx.remote()
+			bg := context.Background()
+
+			s.process(bg, syncJob{remote: remote, prime: true})
+			_, pending := store.retryAt[remote.Name]
+			if pending != tc.wantRetry {
+				t.Fatalf("retry pending=%v, want %v", pending, tc.wantRetry)
+			}
+			if _, saved := store.etags[remote.Name]; saved == tc.wantRetry {
+				t.Fatalf("etag saved=%v after first scan", saved)
+			}
+			if rows, _ := store.ListDebMetadataEntries(bg, remote.Name); len(rows) != 1 {
+				t.Fatalf("healthy asset not served: %d rows", len(rows))
+			}
+			if !tc.wantRetry {
+				return
+			}
+
+			store.mu.Lock()
+			store.retryAt[remote.Name] = time.Now().Add(-time.Second)
+			store.mu.Unlock()
+			s.process(bg, syncJob{remote: remote})
+			if _, pending := store.retryAt[remote.Name]; pending || store.etags[remote.Name] != `"v1"` {
+				t.Fatalf("retry not recorded: pending=%v etag=%q", pending, store.etags[remote.Name])
+			}
+			if rows, _ := store.ListDebMetadataEntries(bg, remote.Name); len(rows) != 2 {
+				t.Fatalf("retry did not derive the failed asset: %d rows", len(rows))
+			}
+		})
+	}
+}

internal/provider/gems/local.go

@@ -0,0 +1,468 @@
+package gems
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"compress/zlib"
+	"crypto/md5"
+	"crypto/sha256"
+	"encoding/hex"
+	"errors"
+	"fmt"
+	"io"
+	"maps"
+	"regexp"
+	"slices"
+	"strings"
+	"time"
+
+	"gopkg.in/yaml.v3"
+)
+
+var (
+	NameRe     = regexp.MustCompile(`^[A-Za-z0-9][A-Za-z0-9._-]*$`)
+	VersionRe  = regexp.MustCompile(`^[0-9]+(\.[0-9A-Za-z]+)*(-[0-9A-Za-z-]+(\.[0-9A-Za-z-]+)*)?$`)
+	PlatformRe = regexp.MustCompile(`^[A-Za-z0-9_.-]+$`)
+	opRe       = regexp.MustCompile(`^(=|!=|>|<|>=|<=|~>)$`)
+)
+
+const maxMetadataBytes = 8 << 20
+
+type Requirement [][2]string
+
+type Dependency struct {
+	Name        string
+	Requirement Requirement
+	Type        string
+	Prerelease  bool
+}
+
+// Spec is the subset of a gemspec the compact index and quick spec need.
+type Spec struct {
+	Name, Version, Platform string
+	Summary, RubyGemsVer    string
+	SpecVersion             int
+	Date                    time.Time
+	Authors, Licenses       []string
+	Email, Description      string
+	Homepage                string
+	Metadata                map[string]string
+	Dependencies            []Dependency
+	RequiredRuby            Requirement
+	RequiredRubyGems        Requirement
+}
+
+// FullName is the gem's file stem: name-version, plus -platform when not ruby.
+func (s *Spec) FullName() string {
+	if s.Platform == "" || s.Platform == "ruby" {
+		return s.Name + "-" + s.Version
+	}
+	return s.Name + "-" + s.Version + "-" + s.Platform
+}
+
+type yamlReq struct {
+	Requirements [][]yaml.Node `yaml:"requirements"`
+}
+
+func (r *yamlReq) decode() (Requirement, error) {
+	if r == nil {
+		return nil, nil
+	}
+	var out Requirement
+	for _, pair := range r.Requirements {
+		var op string
+		var ver struct {
+			Version string `yaml:"version"`
+		}
+		if len(pair) != 2 || pair[0].Decode(&op) != nil || pair[1].Decode(&ver) != nil {
+			return nil, errors.New("malformed requirement")
+		}
+		if !opRe.MatchString(op) || !VersionRe.MatchString(ver.Version) {
+			return nil, fmt.Errorf("invalid requirement %q %q", op, ver.Version)
+		}
+		out = append(out, [2]string{op, ver.Version})
+	}
+	return out, nil
+}
+
+// String renders the requirement as the compact index does: "op ver&op ver".
+func (r Requirement) String() string {
+	parts := make([]string, len(r))
+	for i, p := range r {
+		parts[i] = p[0] + " " + p[1]
+	}
+	return strings.Join(parts, "&")
+}
+
+func (r Requirement) trivial() bool {
+	return len(r) == 0 || len(r) == 1 && r[0] == [2]string{">=", "0"}
+}
+
+// ParseGem reads the gemspec from a .gem archive (a tar holding metadata.gz).
+func ParseGem(gem []byte) (*Spec, error) {
+	tr := tar.NewReader(bytes.NewReader(gem))
+	for {
+		hdr, err := tr.Next()
+		if err == io.EOF {
+			return nil, errors.New("gem has no metadata.gz")
+		}
+		if err != nil {
+			return nil, fmt.Errorf("read gem: %w", err)
+		}
+		if hdr.Name != "metadata.gz" {
+			continue
+		}
+		zr, err := gzip.NewReader(tr)
+		if err != nil {
+			return nil, fmt.Errorf("metadata.gz: %w", err)
+		}
+		raw, err := io.ReadAll(io.LimitReader(zr, maxMetadataBytes+1))
+		if err != nil {
+			return nil, fmt.Errorf("metadata.gz: %w", err)
+		}
+		if len(raw) > maxMetadataBytes {
+			return nil, fmt.Errorf("metadata exceeds %d bytes", maxMetadataBytes)
+		}
+		return parseMetadata(raw)
+	}
+}
+
+func parseMetadata(raw []byte) (*Spec, error) {
+	var doc struct {
+		Name    string `yaml:"name"`
+		Version struct {
+			Version string `yaml:"version"`
+		} `yaml:"version"`
+		Platform     string            `yaml:"platform"`
+		Summary      string            `yaml:"summary"`
+		Authors      []string          `yaml:"authors"`
+		Email        yaml.Node         `yaml:"email"`
+		Description  string            `yaml:"description"`
+		Homepage     string            `yaml:"homepage"`
+		Licenses     []string          `yaml:"licenses"`
+		Metadata     map[string]string `yaml:"metadata"`
+		Date         string            `yaml:"date"`
+		RubyGemsVer  string            `yaml:"rubygems_version"`
+		SpecVersion  int               `yaml:"specification_version"`
+		Dependencies []struct {
+			Name        string   `yaml:"name"`
+			Requirement *yamlReq `yaml:"requirement"`
+			VersionReqs *yamlReq `yaml:"version_requirements"`
+			Type        string   `yaml:"type"`
+			Prerelease  bool     `yaml:"prerelease"`
+		} `yaml:"dependencies"`
+		RequiredRuby     *yamlReq `yaml:"required_ruby_version"`
+		RequiredRubyGems *yamlReq `yaml:"required_rubygems_version"`
+	}
+	if err := yaml.Unmarshal(raw, &doc); err != nil {
+		return nil, fmt.Errorf("gemspec yaml: %w", err)
+	}
+	s := &Spec{
+		Name: doc.Name, Version: doc.Version.Version, Platform: doc.Platform,
+		Summary: doc.Summary, Authors: doc.Authors, Description: doc.Description,
+		Homepage: doc.Homepage, Licenses: doc.Licenses, Metadata: doc.Metadata,
+		RubyGemsVer: doc.RubyGemsVer, SpecVersion: doc.SpecVersion,
+	}
+	if s.Platform == "" {
+		s.Platform = "ruby"
+	}
+	if !NameRe.MatchString(s.Name) || !VersionRe.MatchString(s.Version) || !PlatformRe.MatchString(s.Platform) {
+		return nil, fmt.Errorf("invalid gem name/version/platform %q %q %q", s.Name, s.Version, s.Platform)
+	}
+	if doc.Email.Kind == yaml.ScalarNode {
+		s.Email = doc.Email.Value
+	}
+	if t, err := time.Parse("2006-01-02", strings.SplitN(doc.Date, " ", 2)[0]); err == nil {
+		s.Date = t
+	}
+	var err error
+	if s.RequiredRuby, err = doc.RequiredRuby.decode(); err != nil {
+		return nil, err
+	}
+	if s.RequiredRubyGems, err = doc.RequiredRubyGems.decode(); err != nil {
+		return nil, err
+	}
+	for _, d := range doc.Dependencies {
+		if !NameRe.MatchString(d.Name) {
+			return nil, fmt.Errorf("invalid dependency name %q", d.Name)
+		}
+		req := d.Requirement
+		if req == nil {
+			req = d.VersionReqs
+		}
+		r, err := req.decode()
+		if err != nil {
+			return nil, fmt.Errorf("dependency %s: %w", d.Name, err)
+		}
+		typ := strings.TrimPrefix(d.Type, ":")
+		if typ == "" {
+			typ = "runtime"
+		}
+		s.Dependencies = append(s.Dependencies, Dependency{Name: d.Name, Requirement: r, Type: typ, Prerelease: d.Prerelease})
+	}
+	return s, nil
+}
+
+// InfoLine renders the spec's compact index /info line; checksum is the
+// .gem's sha256 hex.
+func InfoLine(s *Spec, gem []byte) string {
+	sum := sha256.Sum256(gem)
+	var deps []string
+	for _, d := range s.Dependencies {
+		if d.Type == "runtime" {
+			r := d.Requirement
+			if len(r) == 0 {
+				r = Requirement{{">=", "0"}}
+			}
+			deps = append(deps, d.Name+":"+r.String())
+		}
+	}
+	key := s.Version
+	if s.Platform != "ruby" {
+		key += "-" + s.Platform
+	}
+	line := key + " " + strings.Join(deps, ",") + "|checksum:" + hex.EncodeToString(sum[:])
+	if !s.RequiredRuby.trivial() {
+		line += ",ruby:" + s.RequiredRuby.String()
+	}
+	if !s.RequiredRubyGems.trivial() {
+		line += ",rubygems:" + s.RequiredRubyGems.String()
+	}
+	return line
+}
+
+// InfoBody renders an /info document from its lines.
+func InfoBody(lines []string) []byte {
+	var b strings.Builder
+	b.WriteString("---\n")
+	for _, l := range lines {
+		b.WriteString(l)
+		b.WriteByte('\n')
+	}
+	return []byte(b.String())
+}
+
+// InfoKey returns an /info line's version[-platform] token.
+func InfoKey(line string) string {
+	k, _, _ := strings.Cut(line, " ")
+	return k
+}
+
+// InfoLines returns an /info body's version lines.
+func InfoLines(body []byte) []string {
+	var out []string
+	for _, l := range strings.Split(string(body), "\n") {
+		if l != "" && l != "---" {
+			out = append(out, l)
+		}
+	}
+	return out
+}
+
+func MD5Hex(b []byte) string {
+	sum := md5.Sum(b)
+	return hex.EncodeToString(sum[:])
+}
+
+// VersionsLine renders one /versions entry from a gem's /info body.
+func VersionsLine(name string, info []byte) string {
+	var keys []string
+	for _, l := range InfoLines(info) {
+		keys = append(keys, InfoKey(l))
+	}
+	return name + " " + strings.Join(keys, ",") + " " + MD5Hex(info)
+}
+
+// VersionsHeader starts a /versions document.
+func VersionsHeader(at time.Time) string {
+	return "created_at: " + at.UTC().Format(time.RFC3339) + "\n---\n"
+}
+
+// QuickSpec returns the deflated Marshal.4.8 dump of the spec, as served at
+// quick/Marshal.4.8/<full>.gemspec.rz.
+func QuickSpec(s *Spec) ([]byte, error) {
+	var buf bytes.Buffer
+	zw := zlib.NewWriter(&buf)
+	if _, err := zw.Write(MarshalSpec(s)); err != nil {
+		return nil, err
+	}
+	if err := zw.Close(); err != nil {
+		return nil, err
+	}
+	return buf.Bytes(), nil
+}
+
+// MarshalSpec mirrors Gem::Specification#_dump wrapped by Marshal.dump.
+func MarshalSpec(s *Spec) []byte {
+	var in rbMarshal
+	in.WriteString("\x04\x08")
+	in.array(19)
+	in.str(s.RubyGemsVer)
+	in.WriteByte('i')
+	in.fixnum(s.SpecVersion)
+	in.str(s.Name)
+	in.version(s.Version)
+	in.time(s.Date)
+	in.str(s.Summary)
+	in.requirement(s.RequiredRuby)
+	in.requirement(s.RequiredRubyGems)
+	in.str(s.Platform)
+	in.array(len(s.Dependencies))
+	for _, d := range s.Dependencies {
+		in.WriteByte('o')
+		in.sym("Gem::Dependency")
+		in.fixnum(4)
+		in.sym("@name")
+		in.str(d.Name)
+		in.sym("@requirement")
+		in.requirement(d.Requirement)
+		in.sym("@type")
+		in.sym(d.Type)
+		in.sym("@prerelease")
+		in.boolean(d.Prerelease)
+	}
+	in.str("")
+	in.optStr(s.Email)
+	in.strs(s.Authors)
+	in.optStr(s.Description)
+	in.optStr(s.Homepage)
+	in.boolean(true)
+	in.str(s.Platform)
+	in.strs(s.Licenses)
+	in.WriteByte('{')
+	in.fixnum(len(s.Metadata))
+	for _, k := range slices.Sorted(maps.Keys(s.Metadata)) {
+		in.str(k)
+		in.str(s.Metadata[k])
+	}
+
+	var out rbMarshal
+	out.WriteString("\x04\x08u")
+	out.sym("Gem::Specification")
+	out.fixnum(in.Len())
+	out.Write(in.Bytes())
+	return out.Bytes()
+}
+
+// rbMarshal writes the Ruby Marshal 4.8 subset gemspecs use. It never emits
+// object or symbol links, so every symbol is written in full.
+type rbMarshal struct{ bytes.Buffer }
+
+func (m *rbMarshal) fixnum(n int) {
+	switch {
+	case n == 0:
+		m.WriteByte(0)
+	case n > 0 && n < 123:
+		m.WriteByte(byte(n + 5))
+	case n < 0 && n > -124:
+		m.WriteByte(byte(n - 5))
+	default:
+		var b []byte
+		for x := n; len(b) < 4; x >>= 8 {
+			b = append(b, byte(x))
+			if (n >= 0 && x>>8 == 0) || (n < 0 && x>>8 == -1) {
+				break
+			}
+		}
+		if n >= 0 {
+			m.WriteByte(byte(len(b)))
+		} else {
+			m.WriteByte(byte(-len(b)))
+		}
+		m.Write(b)
+	}
+}
+
+func (m *rbMarshal) raw(s string) {
+	m.fixnum(len(s))
+	m.WriteString(s)
+}
+
+func (m *rbMarshal) sym(s string) {
+	m.WriteByte(':')
+	m.raw(s)
+}
+
+// str writes a UTF-8 String (an ivar-wrapped string with E=true).
+func (m *rbMarshal) str(s string) {
+	m.WriteString("I\"")
+	m.raw(s)
+	m.fixnum(1)
+	m.sym("E")
+	m.WriteByte('T')
+}
+
+func (m *rbMarshal) optStr(s string) {
+	if s == "" {
+		m.WriteByte('0')
+		return
+	}
+	m.str(s)
+}
+
+func (m *rbMarshal) strs(ss []string) {
+	m.array(len(ss))
+	for _, s := range ss {
+		m.str(s)
+	}
+}
+
+func (m *rbMarshal) array(n int) {
+	m.WriteByte('[')
+	m.fixnum(n)
+}
+
+func (m *rbMarshal) boolean(b bool) {
+	if b {
+		m.WriteByte('T')
+	} else {
+		m.WriteByte('F')
+	}
+}
+
+func (m *rbMarshal) version(v string) {
+	m.WriteByte('U')
+	m.sym("Gem::Version")
+	m.array(1)
+	m.str(v)
+}
+
+func (m *rbMarshal) requirement(r Requirement) {
+	if len(r) == 0 {
+		r = Requirement{{">=", "0"}}
+	}
+	m.WriteByte('U')
+	m.sym("Gem::Requirement")
+	m.array(1)
+	m.array(len(r))
+	for _, p := range r {
+		m.array(2)
+		m.str(p[0])
+		m.version(p[1])
+	}
+}
+
+// time writes a UTC Time with day resolution, as Time#_dump lays it out.
+func (m *rbMarshal) time(t time.Time) {
+	t = t.UTC()
+	// Time#_dump holds year-1900 in 16 bits.
+	if t.IsZero() || t.Year() < 1900 || t.Year() > 1900+0xffff {
+		t = time.Unix(0, 0).UTC()
+	}
+	p := uint32(1)<<31 | uint32(1)<<30 | uint32(t.Year()-1900)<<14 | uint32(t.Month()-1)<<10 | uint32(t.Day())<<5 | uint32(t.Hour())
+	s := uint32(t.Minute())<<26 | uint32(t.Second())<<20
+	m.WriteString("Iu")
+	m.sym("Time")
+	m.fixnum(8)
+	for _, w := range []uint32{p, s} {
+		m.Write([]byte{byte(w), byte(w >> 8), byte(w >> 16), byte(w >> 24)})
+	}
+	m.fixnum(1)
+	m.sym("zone")
+	m.WriteString("I\"")
+	m.raw("UTC")
+	m.fixnum(1)
+	m.sym("E")
+	m.WriteByte('F')
+}

internal/provider/gems/local_test.go

@@ -0,0 +1,223 @@
+package gems
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"compress/zlib"
+	"crypto/sha256"
+	"encoding/hex"
+	"io"
+	"strings"
+	"testing"
+	"time"
+)
+
+const testMetadata = `--- !ruby/object:Gem::Specification
+name: unkin-e2e-hello
+version: !ruby/object:Gem::Version
+  version: 0.1.0
+platform: %PLATFORM%
+authors:
+- e2e
+date: 2026-10-17 00:00:00.000000000 Z
+dependencies:
+- !ruby/object:Gem::Dependency
+  name: rack
+  requirement: &1 !ruby/object:Gem::Requirement
+    requirements:
+    - - ">="
+      - !ruby/object:Gem::Version
+        version: '2.0'
+    - - "<"
+      - !ruby/object:Gem::Version
+        version: '4'
+  type: :runtime
+  prerelease: false
+  version_requirements: *1
+- !ruby/object:Gem::Dependency
+  name: json
+  version_requirements: !ruby/object:Gem::Requirement
+    requirements:
+    - - "~>"
+      - !ruby/object:Gem::Version
+        version: '2.1'
+  type: :runtime
+  prerelease: false
+- !ruby/object:Gem::Dependency
+  name: rake
+  requirement: !ruby/object:Gem::Requirement
+    requirements:
+    - - ">="
+      - !ruby/object:Gem::Version
+        version: '0'
+  type: :development
+  prerelease: false
+email:
+licenses:
+- MIT
+metadata:
+  source_code_uri: https://example.com
+required_ruby_version: !ruby/object:Gem::Requirement
+  requirements:
+  - - ">="
+    - !ruby/object:Gem::Version
+      version: '2.7'
+required_rubygems_version: !ruby/object:Gem::Requirement
+  requirements:
+  - - ">="
+    - !ruby/object:Gem::Version
+      version: '0'
+rubygems_version: 3.5.22
+specification_version: 4
+summary: hi
+`
+
+func buildGem(t *testing.T, metadata []byte) []byte {
+	t.Helper()
+	var gz bytes.Buffer
+	zw := gzip.NewWriter(&gz)
+	_, _ = zw.Write(metadata)
+	_ = zw.Close()
+	var buf bytes.Buffer
+	tw := tar.NewWriter(&buf)
+	for name, body := range map[string][]byte{"data.tar.gz": []byte("x"), "metadata.gz": gz.Bytes()} {
+		if err := tw.WriteHeader(&tar.Header{Name: name, Mode: 0o444, Size: int64(len(body))}); err != nil {
+			t.Fatal(err)
+		}
+		_, _ = tw.Write(body)
+	}
+	_ = tw.Close()
+	return buf.Bytes()
+}
+
+func testGem(t *testing.T, platform string) []byte {
+	return buildGem(t, []byte(strings.Replace(testMetadata, "%PLATFORM%", platform, 1)))
+}
+
+func TestParseGemAndInfoLine(t *testing.T) {
+	gem := testGem(t, "ruby")
+	s, err := ParseGem(gem)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if s.FullName() != "unkin-e2e-hello-0.1.0" || !s.Date.Equal(time.Date(2026, 10, 17, 0, 0, 0, 0, time.UTC)) {
+		t.Fatalf("spec = %+v", s)
+	}
+	if len(s.Dependencies) != 3 || s.Dependencies[1].Requirement.String() != "~> 2.1" {
+		t.Fatalf("deps = %+v", s.Dependencies)
+	}
+	sum := sha256.Sum256(gem)
+	want := "0.1.0 rack:>= 2.0&< 4,json:~> 2.1|checksum:" + hex.EncodeToString(sum[:]) + ",ruby:>= 2.7"
+	if got := InfoLine(s, gem); got != want {
+		t.Fatalf("InfoLine =\n %s\nwant\n %s", got, want)
+	}
+
+	plat, err := ParseGem(testGem(t, "x86_64-linux"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if plat.FullName() != "unkin-e2e-hello-0.1.0-x86_64-linux" || InfoKey(InfoLine(plat, nil)) != "0.1.0-x86_64-linux" {
+		t.Fatalf("platform gem: %s / %s", plat.FullName(), InfoLine(plat, nil))
+	}
+}
+
+func TestParseGemRejects(t *testing.T) {
+	big := []byte(testMetadata + "description: " + strings.Repeat("a", maxMetadataBytes) + "\n")
+	cases := map[string][]byte{
+		"not a tar":      []byte("garbage"),
+		"no metadata":    func() []byte { var b bytes.Buffer; tw := tar.NewWriter(&b); _ = tw.Close(); return b.Bytes() }(),
+		"bad name":       buildGem(t, []byte(strings.Replace(testMetadata, "name: unkin-e2e-hello", "name: ../x", 1))),
+		"bad version":    buildGem(t, []byte(strings.Replace(testMetadata, "version: 0.1.0", "version: 'a b'", 1))),
+		"bad dep op":     buildGem(t, []byte(strings.Replace(testMetadata, `- - "~>"`, `- - "=~"`, 1))),
+		"metadata bomb":  buildGem(t, big),
+		"bad platform":   buildGem(t, []byte(strings.Replace(testMetadata, "%PLATFORM%", "x/y", 1))),
+		"bad dependency": buildGem(t, []byte(strings.Replace(testMetadata, "name: json", "name: 'a|b'", 1))),
+	}
+	for name, gem := range cases {
+		if _, err := ParseGem(gem); err == nil {
+			t.Errorf("%s: accepted", name)
+		}
+	}
+}
+
+func TestVersionsLineMD5(t *testing.T) {
+	info := InfoBody([]string{"0.1.0 |checksum:aa", "0.2.0-java |checksum:bb"})
+	if string(info) != "---\n0.1.0 |checksum:aa\n0.2.0-java |checksum:bb\n" {
+		t.Fatalf("InfoBody = %q", info)
+	}
+	if got := VersionsLine("g", info); got != "g 0.1.0,0.2.0-java "+MD5Hex(info) {
+		t.Fatalf("VersionsLine = %q", got)
+	}
+}
+
+// Byte layouts below are taken from Ruby 3.3's Marshal.dump.
+func TestRubyMarshalEncoding(t *testing.T) {
+	for n, want := range map[int]string{0: "\x00", 4: "\x09", 122: "\x7f", 123: "\x01\x7b", 255: "\x01\xff", 256: "\x02\x00\x01", 65536: "\x03\x00\x00\x01", -1: "\xfa", -123: "\x80"} {
+		var m rbMarshal
+		m.fixnum(n)
+		if m.String() != want {
+			t.Errorf("fixnum(%d) = %x, want %x", n, m.String(), want)
+		}
+	}
+	var m rbMarshal
+	m.str("3.5.22")
+	if m.String() != "I\"\x0b3.5.22\x06:\x06ET" {
+		t.Errorf("str = %q", m.String())
+	}
+	m.Reset()
+	m.version("0.1.0")
+	if m.String() != "U:\x11Gem::Version[\x06I\"\x0a0.1.0\x06:\x06ET" {
+		t.Errorf("version = %q", m.String())
+	}
+	m.Reset()
+	m.time(time.Date(2026, 10, 17, 0, 0, 0, 0, time.UTC))
+	if want := "Iu:\x09Time\x0d\x20\xa6\x1f\xc0\x00\x00\x00\x00\x06:\x09zoneI\"\x08UTC\x06:\x06EF"; m.String() != want {
+		t.Errorf("time = %q, want %q", m.String(), want)
+	}
+	var epoch rbMarshal
+	epoch.time(time.Time{})
+	for _, y := range []int{1, 1899, 1900 + 0x10000} {
+		m.Reset()
+		m.time(time.Date(y, 1, 1, 0, 0, 0, 0, time.UTC))
+		if m.String() != epoch.String() {
+			t.Errorf("time(year %d) = %q, want the epoch encoding %q", y, m.String(), epoch.String())
+		}
+	}
+}
+
+func TestQuickSpec(t *testing.T) {
+	s, err := ParseGem(testGem(t, "ruby"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	q, err := QuickSpec(s)
+	if err != nil {
+		t.Fatal(err)
+	}
+	q2, _ := QuickSpec(s)
+	if !bytes.Equal(q, q2) {
+		t.Fatal("QuickSpec is not deterministic")
+	}
+	zr, err := zlib.NewReader(bytes.NewReader(q))
+	if err != nil {
+		t.Fatal(err)
+	}
+	raw, _ := io.ReadAll(zr)
+	head := "\x04\x08u:\x17Gem::Specification"
+	if !strings.HasPrefix(string(raw), head) {
+		t.Fatalf("quick spec prefix = %q", raw[:30])
+	}
+	inner := string(raw[len(head):])
+	at := strings.Index(inner, "\x04\x08[\x18")
+	var length rbMarshal
+	length.fixnum(len(inner) - at)
+	if at < 1 || inner[:at] != length.String() {
+		t.Fatalf("inner dump header = %q", inner[:8])
+	}
+	for _, want := range []string{"o:\x14Gem::Dependency", ":\x0cruntime", ":\x10development", "source_code_uri"} {
+		if !strings.Contains(string(raw), want) {
+			t.Errorf("quick spec missing %q", want)
+		}
+	}
+}

internal/provider/provider.go

@@ -8,6 +8,9 @@ import (
 	"git.unkin.net/unkin/artifactapi/pkg/models"
 )
 
+// RemoteMountPath is the URL path remote proxies are served under.
+const RemoteMountPath = "/api/v1/remote/"
+
 type Mutability int
 
 const (

internal/provider/rpm/github.go

@@ -343,6 +343,9 @@ func (p *GitHubProvider) scanWithState(ctx context.Context, remote models.Remote
 		return newEtag, false, err
 	}
 
+	// A transiently failed asset fails the scan so the ETag is not advanced and
+	// the retry re-derives it; an invalid package is skipped as no retry fixes it.
+	var failed []error
 	seen := map[string]bool{}
 	for _, rel := range releases {
 		if rel.Draft {
@@ -373,10 +376,14 @@ func (p *GitHubProvider) scanWithState(ctx context.Context, remote models.Remote
 			meta, err := p.deriveAsset(ctx, remote, asset, fp)
 			if err != nil {
 				slog.Warn("github_rpm: derive asset failed", "remote", remote.Name, "asset", asset.Name, "error", err)
+				if !errors.Is(err, provider.ErrInvalidPackage) {
+					failed = append(failed, fmt.Errorf("%s: %w", asset.Name, err))
+				}
 				continue
 			}
 			if err := store.InsertRPMMetadata(ctx, meta); err != nil {
 				slog.Error("github_rpm: insert metadata failed", "remote", remote.Name, "asset", asset.Name, "error", err)
+				failed = append(failed, fmt.Errorf("%s: %w", asset.Name, err))
 				continue
 			}
 			slog.Info("github_rpm: derived asset", "remote", remote.Name, "name", meta.Name, "version", meta.Version, "arch", meta.Arch)
@@ -388,7 +395,7 @@ func (p *GitHubProvider) scanWithState(ctx context.Context, remote models.Remote
 			_ = store.DeleteRPMMetadata(ctx, remote.Name, fp)
 		}
 	}
-	return newEtag, true, nil
+	return newEtag, true, errors.Join(failed...)
 }
 
 type ghRelease struct {
@@ -569,12 +576,12 @@ func (p *GitHubProvider) fetchHeader(ctx context.Context, remote models.Remote,
 			}
 			continue
 		}
-		return nil, fmt.Errorf("parse rpm header: %w", perr)
+		return nil, fmt.Errorf("%w: parse rpm header: %w", provider.ErrInvalidPackage, perr)
 	}
 }
 
 // rangeGet returns the first n bytes of downloadURL. full is true when the
-// response body was shorter than n (i.e. we already have the whole object).
+// response holds the whole object.
 func (p *GitHubProvider) rangeGet(ctx context.Context, remote models.Remote, downloadURL string, n int64) ([]byte, bool, error) {
 	req, err := http.NewRequestWithContext(ctx, http.MethodGet, downloadURL, nil)
 	if err != nil {
@@ -596,15 +603,9 @@ func (p *GitHubProvider) rangeGet(ctx context.Context, remote models.Remote, dow
 	}
 	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
-		return nil, false, fmt.Errorf("range GET %s: status %d", downloadURL, resp.StatusCode)
+		return nil, false, fmt.Errorf("range GET: %w", provider.AssetStatusError(downloadURL, resp))
 	}
-
-	body, err := io.ReadAll(io.LimitReader(resp.Body, n))
-	if err != nil {
-		return nil, false, err
-	}
-	full := int64(len(body)) < n
-	return body, full, nil
+	return provider.ReadPrefix(resp, n)
 }
 
 func (p *GitHubProvider) computeSHA256(ctx context.Context, remote models.Remote, downloadURL string) (string, error) {
@@ -627,7 +628,7 @@ func (p *GitHubProvider) computeSHA256(ctx context.Context, remote models.Remote
 	}
 	defer resp.Body.Close()
 	if resp.StatusCode != http.StatusOK {
-		return "", fmt.Errorf("GET %s: status %d", downloadURL, resp.StatusCode)
+		return "", fmt.Errorf("GET: %w", provider.AssetStatusError(downloadURL, resp))
 	}
 
 	h := sha256.New()

internal/provider/rpm/github_test.go

@@ -1,11 +1,13 @@
 package rpm
 
 import (
+	"cmp"
 	"compress/gzip"
 	"context"
 	"crypto/sha256"
 	"encoding/hex"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"io"
 	"net/http"
@@ -24,15 +26,22 @@ import (
 // fakeStore is an in-memory provider.RemoteMetadataStore keyed by file_path,
 // mirroring the (repo_name, file_path) uniqueness of the real table.
 type fakeStore struct {
-	mu   sync.Mutex
-	rows map[string]provider.RPMMetadata
+	mu         sync.Mutex
+	rows       map[string]provider.RPMMetadata
+	insertFail map[string]int // package name -> inserts left to fail
 }
 
-func newFakeStore() *fakeStore { return &fakeStore{rows: map[string]provider.RPMMetadata{}} }
+func newFakeStore() *fakeStore {
+	return &fakeStore{rows: map[string]provider.RPMMetadata{}, insertFail: map[string]int{}}
+}
 
 func (f *fakeStore) InsertRPMMetadata(_ context.Context, m *provider.RPMMetadata) error {
 	f.mu.Lock()
 	defer f.mu.Unlock()
+	if f.insertFail[m.Name] > 0 {
+		f.insertFail[m.Name]--
+		return errors.New("insert failed")
+	}
 	if _, ok := f.rows[m.FilePath]; ok {
 		return nil // ON CONFLICT DO NOTHING
 	}
@@ -79,15 +88,20 @@ type githubFixture struct {
 	releaseAuth string            // Authorization header seen on the last releases request
 	assetAuth   string            // Authorization header seen on the last asset request
 	failStatus  int               // when set, the releases list answers this status (rate-limit style)
+	assetFail   map[string]int    // asset filename -> downloads left to answer failCode
+	failCode    int               // status for assetFail downloads; 0 = 500
+	shortRead   map[string]int    // asset filename -> ranged GETs left to close early
 	mu          sync.Mutex
 }
 
 func newGitHubFixture(t *testing.T, withDigest bool) *githubFixture {
 	t.Helper()
 	f := &githubFixture{
-		rpmBytes: map[string][]byte{},
-		rangeHit: map[string]int{},
-		fullHit:  map[string]int{},
+		rpmBytes:  map[string][]byte{},
+		rangeHit:  map[string]int{},
+		fullHit:   map[string]int{},
+		assetFail: map[string]int{},
+		shortRead: map[string]int{},
 	}
 	f.rpmBytes["demo-1.2-3.x86_64.rpm"] = testsupport.MinimalRPM("demo", "1.2", "3", "x86_64")
 
@@ -145,6 +159,17 @@ func newGitHubFixture(t *testing.T, withDigest bool) *githubFixture {
 		}
 		rng := r.Header.Get("Range")
 		f.mu.Lock()
+		if f.assetFail[name] > 0 {
+			f.assetFail[name]--
+			code := cmp.Or(f.failCode, http.StatusInternalServerError)
+			f.mu.Unlock()
+			http.Error(w, "boom", code)
+			return
+		}
+		short := rng != "" && f.shortRead[name] > 0
+		if short {
+			f.shortRead[name]--
+		}
 		f.assetAuth = r.Header.Get("Authorization")
 		if rng != "" {
 			f.rangeHit[name]++
@@ -165,6 +190,9 @@ func newGitHubFixture(t *testing.T, withDigest bool) *githubFixture {
 			end = len(body) - 1
 		}
 		w.Header().Set("Content-Range", fmt.Sprintf("bytes 0-%d/%d", end, len(body)))
+		if short {
+			end /= 2
+		}
 		w.Header().Set("Content-Length", strconv.Itoa(end+1))
 		w.WriteHeader(http.StatusPartialContent)
 		w.Write(body[:end+1])

internal/provider/rpm/syncer_test.go

@@ -399,3 +399,74 @@ func TestSyncerFailedScanRetriesAfterBackoff(t *testing.T) {
 		t.Fatalf("recovery did not refresh metadata: %d rows", len(rows))
 	}
 }
+
+// A transiently failed asset fails the scan: the ETag is not advanced, a retry
+// is scheduled, and the retry against the unchanged release list derives it. An
+// invalid package is skipped instead, since no retry can fix it.
+func TestSyncerFailedAssetRetry(t *testing.T) {
+	for _, tc := range []struct {
+		name      string
+		corrupt   bool
+		failCode  int
+		short     bool
+		insert    bool
+		wantRetry bool
+	}{
+		{name: "transient", wantRetry: true},
+		{name: "rate limited", failCode: http.StatusForbidden, wantRetry: true},
+		{name: "short read", short: true, wantRetry: true},
+		{name: "insert failure", insert: true, wantRetry: true},
+		{name: "invalid package", corrupt: true},
+		{name: "asset not found", failCode: http.StatusNotFound},
+		{name: "asset gone", failCode: http.StatusGone},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			const other = "other-9-9.aarch64.rpm"
+			fx := newGitHubFixture(t, true)
+			fx.etag = `"v1"`
+			fx.rpmBytes[other] = testsupport.MinimalRPM("other", "9", "9", "aarch64")
+			store := newFakeSyncStore()
+			switch {
+			case tc.corrupt:
+				fx.rpmBytes[other] = []byte("not a package")
+			case tc.short:
+				fx.shortRead[other] = 1
+			case tc.insert:
+				store.insertFail["other"] = 1
+			case tc.failCode != 0 && !tc.wantRetry:
+				fx.failCode, fx.assetFail[other] = tc.failCode, 1<<30
+			default:
+				fx.failCode, fx.assetFail[other] = tc.failCode, 1
+			}
+			s := newSyncer(store, newTestProvider(), testSyncConfig())
+			remote := fx.remote()
+			bg := context.Background()
+
+			s.process(bg, syncJob{remote: remote, prime: true})
+			_, pending := store.retryAt[remote.Name]
+			if pending != tc.wantRetry {
+				t.Fatalf("retry pending=%v, want %v", pending, tc.wantRetry)
+			}
+			if _, saved := store.etags[remote.Name]; saved == tc.wantRetry {
+				t.Fatalf("etag saved=%v after first scan", saved)
+			}
+			if rows, _ := store.ListRPMMetadataEntries(bg, remote.Name); len(rows) != 1 {
+				t.Fatalf("healthy asset not served: %d rows", len(rows))
+			}
+			if !tc.wantRetry {
+				return
+			}
+
+			store.mu.Lock()
+			store.retryAt[remote.Name] = time.Now().Add(-time.Second)
+			store.mu.Unlock()
+			s.process(bg, syncJob{remote: remote})
+			if _, pending := store.retryAt[remote.Name]; pending || store.etags[remote.Name] != `"v1"` {
+				t.Fatalf("retry not recorded: pending=%v etag=%q", pending, store.etags[remote.Name])
+			}
+			if rows, _ := store.ListRPMMetadataEntries(bg, remote.Name); len(rows) != 2 {
+				t.Fatalf("retry did not derive the failed asset: %d rows", len(rows))
+			}
+		})
+	}
+}

internal/provider/syncretry.go

@@ -3,8 +3,10 @@ package provider
 import (
 	"errors"
 	"fmt"
+	"io"
 	"net/http"
 	"strconv"
+	"strings"
 	"time"
 )
 
@@ -43,6 +45,49 @@ func NewUpstreamStatusError(url string, resp *http.Response) *UpstreamStatusErro
 	return e
 }
 
+// ErrInvalidPackage marks an asset whose bytes are not a valid package. It is
+// permanent, so a scan skips the asset instead of failing and retrying.
+var ErrInvalidPackage = errors.New("invalid package")
+
+// AssetStatusError classifies a non-success asset download. A missing or
+// unsatisfiable asset is permanent; anything else (403/429 rate limits, 5xx) is
+// transient.
+func AssetStatusError(url string, resp *http.Response) error {
+	switch resp.StatusCode {
+	case http.StatusNotFound, http.StatusGone, http.StatusRequestedRangeNotSatisfiable:
+		return fmt.Errorf("%w: %s: status %d", ErrInvalidPackage, url, resp.StatusCode)
+	}
+	return NewUpstreamStatusError(url, resp)
+}
+
+// ReadPrefix reads up to n bytes of a 200 or 206 asset response. full reports
+// that the body is the whole object (per Content-Length or the Content-Range
+// total, or a clean EOF before n when the total is unknown); a body ending before n bytes that is not the whole object is a
+// transient short read.
+func ReadPrefix(resp *http.Response, n int64) (body []byte, full bool, err error) {
+	body, err = io.ReadAll(io.LimitReader(resp.Body, n))
+	if err != nil {
+		return nil, false, err
+	}
+	total := resp.ContentLength
+	unknown := resp.StatusCode == http.StatusOK && total == -1
+	if resp.StatusCode == http.StatusPartialContent {
+		total = -1
+		if _, t, ok := strings.Cut(resp.Header.Get("Content-Range"), "/"); ok {
+			if v, perr := strconv.ParseInt(t, 10, 64); perr == nil {
+				total = v
+			}
+			unknown = t == "*"
+		}
+	}
+	// net/http errors on a premature close, so a clean EOF before n with an unknown total is the whole object.
+	full = total == int64(len(body)) || (unknown && int64(len(body)) < n)
+	if !full && int64(len(body)) < n {
+		return nil, false, fmt.Errorf("short read: got %d of %d bytes", len(body), n)
+	}
+	return body, full, nil
+}
+
 // SyncResult is a background scan's outcome, recorded when its sync lease is
 // released. A failed scan keeps the prior sync time and ETag and schedules a
 // retry after Backoff, doubled per consecutive failure up to MaxBackoff, and

internal/provider/syncretry_test.go

@@ -3,7 +3,9 @@ package provider
 import (
 	"errors"
 	"fmt"
+	"io"
 	"net/http"
+	"net/http/httptest"
 	"strconv"
 	"testing"
 	"time"
@@ -61,3 +63,76 @@ func TestNewSyncResult(t *testing.T) {
 		t.Fatalf("wrapped hint not clamped to ttl: retry in %v", until)
 	}
 }
+
+func TestAssetStatusErrorClassification(t *testing.T) {
+	for status, permanent := range map[int]bool{
+		http.StatusNotFound: true, http.StatusGone: true, http.StatusRequestedRangeNotSatisfiable: true,
+		http.StatusForbidden: false, http.StatusTooManyRequests: false, http.StatusInternalServerError: false, http.StatusBadGateway: false,
+	} {
+		err := AssetStatusError("u", &http.Response{StatusCode: status, Header: http.Header{}})
+		if errors.Is(err, ErrInvalidPackage) != permanent {
+			t.Errorf("status %d: permanent=%v, want %v", status, !permanent, permanent)
+		}
+	}
+}
+
+func TestReadPrefix(t *testing.T) {
+	cases := []struct {
+		name     string
+		status   int
+		cl       int64
+		crange   string
+		body     string
+		n        int64
+		wantFull bool
+		wantErr  bool
+	}{
+		{name: "200 whole object", status: 200, cl: 5, body: "hello", n: 32, wantFull: true},
+		{name: "200 larger than n", status: 200, cl: 5, body: "hello", n: 4},
+		{name: "200 chunked shorter than n", status: 200, cl: -1, body: "hello", n: 32, wantFull: true},
+		{name: "200 chunked larger than n", status: 200, cl: -1, body: "hello", n: 4},
+		{name: "206 whole object", status: 206, crange: "bytes 0-4/5", body: "hello", n: 32, wantFull: true},
+		{name: "206 prefix", status: 206, crange: "bytes 0-3/100", body: "hell", n: 4},
+		{name: "206 short read", status: 206, crange: "bytes 0-31/100", body: "hello", n: 32, wantErr: true},
+		{name: "206 no content-range short", status: 206, body: "hello", n: 32, wantErr: true},
+		{name: "206 unknown total shorter than n", status: 206, cl: -1, crange: "bytes 0-4/*", body: "hello", n: 32, wantFull: true},
+		{name: "206 unknown total prefix", status: 206, cl: -1, crange: "bytes 0-3/*", body: "hell", n: 4},
+	}
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
+				if tc.cl > 0 {
+					w.Header().Set("Content-Length", strconv.FormatInt(tc.cl, 10))
+				}
+				if tc.crange != "" {
+					w.Header().Set("Content-Range", tc.crange)
+				}
+				w.WriteHeader(tc.status)
+				_, _ = io.WriteString(w, tc.body)
+				w.(http.Flusher).Flush()
+			}))
+			defer srv.Close()
+			resp, err := http.Get(srv.URL)
+			if err != nil {
+				t.Fatal(err)
+			}
+			defer resp.Body.Close()
+			if tc.cl == -1 && resp.ContentLength != -1 {
+				t.Fatalf("response not chunked: ContentLength=%d", resp.ContentLength)
+			}
+			body, full, err := ReadPrefix(resp, tc.n)
+			if (err != nil) != tc.wantErr {
+				t.Fatalf("err=%v, wantErr=%v", err, tc.wantErr)
+			}
+			if err != nil {
+				if errors.Is(err, ErrInvalidPackage) {
+					t.Fatalf("short read must be transient: %v", err)
+				}
+				return
+			}
+			if full != tc.wantFull || int64(len(body)) > tc.n {
+				t.Fatalf("full=%v len=%d, want full=%v", full, len(body), tc.wantFull)
+			}
+		})
+	}
+}

internal/proxy/classifier.go

@@ -2,6 +2,7 @@ package proxy
 
 import (
 	"regexp"
+	"strings"
 	"sync"
 
 	"git.unkin.net/unkin/artifactapi/internal/provider"
@@ -37,7 +38,9 @@ func NewClassifier(p provider.Provider) *Classifier {
 	return &Classifier{provider: p}
 }
 
+// Classify judges the bare path; a forwarded query must not change the verdict.
 func (c *Classifier) Classify(remote models.Remote, path string) Classification {
+	path, _, _ = strings.Cut(path, "?")
 	if matchesAny(path, compilePatterns(remote.Blocklist)) {
 		return ClassDenied
 	}

internal/proxy/classifier_extra_test.go

@@ -38,6 +38,24 @@ func TestClassifierBranches(t *testing.T) {
 	}
 }
 
+func TestClassifierIgnoresForwardedQuery(t *testing.T) {
+	gp, err := provider.Get(models.PackageGeneric)
+	if err != nil {
+		t.Fatal(err)
+	}
+	c := NewClassifier(gp)
+	if got := c.Classify(models.Remote{Blocklist: []string{`\.exe$`}}, "x.exe?limit=1"); got != ClassDenied {
+		t.Errorf("blocklist bypassed by query: %v", got)
+	}
+	allow := models.Remote{Patterns: []string{`/versions/$`}}
+	if got := c.Classify(allow, "a/versions/?limit=1&offset=100"); got != ClassImmutable {
+		t.Errorf("allowlisted paginated path = %v, want immutable", got)
+	}
+	if got := c.Classify(models.Remote{MutablePatterns: []string{`/versions/$`}}, "a/versions/?offset=100"); got != ClassMutable {
+		t.Errorf("mutable pattern on paginated path = %v, want mutable", got)
+	}
+}
+
 func TestClassificationString(t *testing.T) {
 	for c, want := range map[Classification]string{
 		ClassImmutable:     "immutable",

internal/proxy/engine.go

@@ -134,10 +134,11 @@ func (e *Engine) Fetch(ctx context.Context, remote models.Remote, path string, p
 		slog.Warn("cache hit but S3 miss, re-fetching", "remote", remote.Name, "path", path)
 	}
 
-	locked, err := e.cache.AcquireLock(ctx, remote.Name, path, fetchLockTTL)
+	token, err := e.cache.AcquireLock(ctx, remote.Name, path, fetchLockTTL)
 	if err != nil {
 		slog.Warn("lock acquire failed", "error", err)
 	}
+	locked := token != ""
 
 	if !locked {
 		// Another request holds the fetch lock. Poll the store until the leader
@@ -151,7 +152,7 @@ func (e *Engine) Fetch(ctx context.Context, remote models.Remote, path string, p
 	}
 
 	if locked {
-		defer e.cache.ReleaseLock(ctx, remote.Name, path)
+		defer func() { _ = e.cache.ReleaseLock(context.WithoutCancel(ctx), remote.Name, path, token) }()
 	}
 
 	if class == ClassMutable && remote.CheckMutable {
@@ -216,7 +217,8 @@ func (e *Engine) Fetch(ctx context.Context, remote models.Remote, path string, p
 
 // Evict drops path from every cache layer (artifact row, index object, Redis
 // freshness and ETag keys) so the next request refetches from upstream. A
-// trailing "/*" evicts every path under that directory.
+// trailing "/*" evicts every path under that directory; a plain path also
+// drops its forwarded-query variants ("path?...").
 func (e *Engine) Evict(ctx context.Context, remoteName, path string) error {
 	prefix, wildcard := strings.CutSuffix(path, "*")
 	if wildcard && !strings.HasSuffix(prefix, "/") {
@@ -228,21 +230,34 @@ func (e *Engine) Evict(ctx context.Context, remoteName, path string) error {
 		return fmt.Errorf("get remote: %w", err)
 	}
 	if !wildcard {
-		if err := e.waitForLock(ctx, remoteName, path); err != nil {
+		release, err := e.Lock(ctx, remoteName, path, e.evictLockWait, fetchLockTTL)
+		if err != nil {
 			return err
 		}
-		defer func() { _ = e.cache.ReleaseLock(context.WithoutCancel(ctx), remoteName, path) }()
+		defer release()
 		if err := e.db.DeleteArtifact(ctx, remoteName, path); err != nil {
 			return fmt.Errorf("delete artifact: %w", err)
 		}
 		if err := e.store.Delete(ctx, storage.IndexKey(remoteName, path)); err != nil {
 			return fmt.Errorf("delete index: %w", err)
 		}
-		return e.cache.ForgetPath(ctx, remoteName, path)
+		if err := e.cache.ForgetPath(ctx, remoteName, path); err != nil {
+			return err
+		}
+		if strings.Contains(path, "?") {
+			return nil
+		}
+		return e.evictPrefix(ctx, remoteName, path+"?")
 	}
 	// ponytail: no lock for wildcards; a Fetch already in flight under the
 	// prefix can re-cache its path after the evict. Per-path locks over a
 	// directory would close it if that ever matters.
+	return e.evictPrefix(ctx, remoteName, prefix)
+}
+
+// evictPrefix drops every cached path starting with prefix, including the
+// forwarded-query variants ("path?...") of a single path.
+func (e *Engine) evictPrefix(ctx context.Context, remoteName, prefix string) error {
 	if err := e.db.DeleteArtifactsByPrefix(ctx, remoteName, prefix); err != nil {
 		return fmt.Errorf("delete artifacts: %w", err)
 	}
@@ -252,28 +267,36 @@ func (e *Engine) Evict(ctx context.Context, remoteName, path string) error {
 	return e.cache.ForgetPrefix(ctx, remoteName, prefix)
 }
 
-// waitForLock takes the per-path fetch lock so an in-flight Fetch cannot
-// re-set TTL/ETag keys after an evict. It fails with a 503 when the lock
-// cannot be taken within evictLockWait or Redis errors.
-func (e *Engine) waitForLock(ctx context.Context, remoteName, path string) error {
-	deadline := time.Now().Add(e.evictLockWait)
+// Lock takes the per-path Redis lock (the one Fetch holds) and returns its
+// release. It fails with a 503 when the lock cannot be taken within wait or
+// Redis errors.
+func (e *Engine) Lock(ctx context.Context, remoteName, path string, wait, ttl time.Duration) (func(), error) {
+	token, err := e.waitForLock(ctx, remoteName, path, wait, ttl)
+	if err != nil {
+		return nil, err
+	}
+	return func() { _ = e.cache.ReleaseLock(context.WithoutCancel(ctx), remoteName, path, token) }, nil
+}
+
+func (e *Engine) waitForLock(ctx context.Context, remoteName, path string, wait, ttl time.Duration) (string, error) {
+	deadline := time.Now().Add(wait)
 	for {
-		ok, err := e.cache.AcquireLock(ctx, remoteName, path, fetchLockTTL)
-		if ok {
-			return nil
+		token, err := e.cache.AcquireLock(ctx, remoteName, path, ttl)
+		if token != "" {
+			return token, nil
 		}
 		if ctx.Err() != nil {
-			return ctx.Err()
+			return "", ctx.Err()
 		}
 		if err != nil {
-			return &ProxyError{Status: http.StatusServiceUnavailable, Message: fmt.Sprintf("fetch lock: %v", err)}
+			return "", &ProxyError{Status: http.StatusServiceUnavailable, Message: fmt.Sprintf("lock: %v", err)}
 		}
 		if time.Now().After(deadline) {
-			return &ProxyError{Status: http.StatusServiceUnavailable, Message: "fetch in progress, retry evict"}
+			return "", &ProxyError{Status: http.StatusServiceUnavailable, Message: "resource busy, retry later"}
 		}
 		select {
 		case <-ctx.Done():
-			return ctx.Err()
+			return "", ctx.Err()
 		case <-time.After(50 * time.Millisecond):
 		}
 	}

internal/proxy/evict_test.go

@@ -152,13 +152,15 @@ func TestEvictUnknownRemote(t *testing.T) {
 	}
 }
 
-func holdLock(t *testing.T, remote, path string) {
+func holdLock(t *testing.T, remote, path string) string {
 	t.Helper()
 	ctx := context.Background()
-	if ok, err := testCache.AcquireLock(ctx, remote, path, time.Minute); !ok || err != nil {
-		t.Fatalf("acquire: %v %v", ok, err)
+	token, err := testCache.AcquireLock(ctx, remote, path, time.Minute)
+	if token == "" || err != nil {
+		t.Fatalf("acquire: %q %v", token, err)
 	}
-	t.Cleanup(func() { _ = testCache.ReleaseLock(ctx, remote, path) })
+	t.Cleanup(func() { _ = testCache.ReleaseLock(ctx, remote, path, token) })
+	return token
 }
 
 func TestEvictWaitsForFetchLock(t *testing.T) {
@@ -167,7 +169,7 @@ func TestEvictWaitsForFetchLock(t *testing.T) {
 	r := rpmRemote(t, "evict-lock", srv.URL)
 	ctx := context.Background()
 	const path = "8/Everything/x86_64/repodata/repomd.xml"
-	holdLock(t, r.Name, path)
+	token := holdLock(t, r.Name, path)
 	done := make(chan error, 1)
 	go func() { done <- testEngine.Evict(ctx, r.Name, path) }()
 	select {
@@ -175,13 +177,13 @@ func TestEvictWaitsForFetchLock(t *testing.T) {
 		t.Fatalf("evict returned while fetch lock held: %v", err)
 	case <-time.After(200 * time.Millisecond):
 	}
-	_ = testCache.ReleaseLock(ctx, r.Name, path)
+	_ = testCache.ReleaseLock(ctx, r.Name, path, token)
 	if err := <-done; err != nil {
 		t.Fatalf("evict: %v", err)
 	}
-	ok, err := testCache.AcquireLock(ctx, r.Name, path, time.Second)
-	if !ok || err != nil {
-		t.Fatalf("lock still held after evict: %v %v", ok, err)
+	token, err := testCache.AcquireLock(ctx, r.Name, path, time.Second)
+	if token == "" || err != nil {
+		t.Fatalf("lock still held after evict: %q %v", token, err)
 	}
 }
 
@@ -269,3 +271,28 @@ func TestEvictWildcardClearsPrefixOnly(t *testing.T) {
 		t.Errorf("path outside prefix = %q, want cached rev1", got)
 	}
 }
+
+func TestEvictPathDropsQueryVariants(t *testing.T) {
+	requireStack(t)
+	srv, _, _ := changingUpstream(t)
+	r := rpmRemote(t, "evict-query", srv.URL)
+	const (
+		path    = "8/Everything/x86_64/repodata/repomd.xml"
+		variant = path + "?limit=10"
+		sibling = "8/Everything/x86_64/repodata/repomd.xml.asc"
+	)
+	for _, p := range []string{path, variant, sibling} {
+		fetchBody(t, r, p)
+	}
+	if err := testEngine.Evict(context.Background(), r.Name, path); err != nil {
+		t.Fatalf("evict: %v", err)
+	}
+	for _, p := range []string{path, variant} {
+		if c := layers(t, r.Name, p); c != (cached{}) {
+			t.Errorf("%s after evict = %+v, want every layer gone", p, c)
+		}
+	}
+	if c := layers(t, r.Name, sibling); c == (cached{}) {
+		t.Errorf("%s sharing the name prefix was evicted", sibling)
+	}
+}

internal/server/server.go

@@ -167,6 +167,8 @@ func (s *Server) routes() chi.Router {
 
 	proxyHandler := v1.NewProxyHandler(s.engine, s.virtEngine, s.db, s.store, s.localHandler)
 	s.virtEngine.NPMLocal = proxyHandler.LocalNPMPackument
+	s.virtEngine.GemsLocal = proxyHandler.LocalGemsIndex
+	s.virtEngine.AnsibleLocal = proxyHandler.LocalAnsible
 	r.Mount("/api/v1", proxyHandler.Routes())
 	r.Mount("/v2", proxyHandler.DockerV2Routes())
 

internal/virtual/ansible_merger.go

@@ -0,0 +1,182 @@
+package virtual
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strconv"
+	"strings"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider/ansible"
+	"git.unkin.net/unkin/artifactapi/internal/proxy"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+const (
+	maxAnsibleCollections = 1024
+	ansibleMemberPage     = 100
+	maxAnsibleMemberPages = 100
+)
+
+// AnsibleMember is one member's versions of a collection; Found is false when
+// the member does not have it.
+type AnsibleMember struct {
+	RemoteName string
+	Found      bool
+	Refs       []ansible.VersionRef
+}
+
+// AnsibleDoc is a collection's merged versions; Owners maps each version to
+// the member serving it.
+type AnsibleDoc struct {
+	Refs   []ansible.VersionRef
+	Owners map[string]string
+	body   []byte
+}
+
+func (d *AnsibleDoc) index() []byte            { return d.body }
+func (d *AnsibleDoc) files() map[string][]byte { return nil }
+
+// MergeAnsibleVersions concatenates member versions in member order; the
+// first member wins a duplicate version. ErrNotFound means no member has the
+// collection.
+func MergeAnsibleVersions(members []AnsibleMember) (*AnsibleDoc, error) {
+	d := &AnsibleDoc{Refs: []ansible.VersionRef{}, Owners: map[string]string{}}
+	found := false
+	for _, m := range members {
+		found = found || m.Found
+		for _, r := range m.Refs {
+			if _, dup := d.Owners[r.Version]; dup {
+				continue
+			}
+			d.Owners[r.Version] = m.RemoteName
+			d.Refs = append(d.Refs, r)
+		}
+	}
+	if !found {
+		return nil, ErrNotFound
+	}
+	var err error
+	d.body, err = json.Marshal(d.Refs)
+	return d, err
+}
+
+// AnsibleVersions returns the merged versions of ns.name across members.
+func (e *Engine) AnsibleVersions(ctx context.Context, virt models.Virtual, ns, name string) (*AnsibleDoc, error) {
+	prefix := "ansible\x00" + virt.Name + "\x00"
+	inserted := false
+	repo, err := e.merged(ctx, prefix+ns+"/"+name, func(ctx context.Context) (mergedRepo, error) {
+		inserted = true
+		members, err := fetchMembers(virt, func(m string) (*AnsibleMember, error) { return e.ansibleMember(ctx, m, ns, name) })
+		if err != nil {
+			return nil, err
+		}
+		return MergeAnsibleVersions(members)
+	})
+	if err != nil {
+		return nil, err
+	}
+	if inserted {
+		e.evictOldest(prefix, maxAnsibleCollections)
+	}
+	return repo.(*AnsibleDoc), nil
+}
+
+// AnsibleVersion serves the owning member's version detail with href and
+// download_url pointing at the virtual; the download 302s to the member.
+// Member documents carry root-relative URLs, so anything else is rejected.
+func (e *Engine) AnsibleVersion(ctx context.Context, virt models.Virtual, ns, name, version, proxyBaseURL string) ([]byte, error) {
+	d, err := e.AnsibleVersions(ctx, virt, ns, name)
+	if err != nil {
+		return nil, err
+	}
+	owner, ok := d.Owners[version]
+	if !ok {
+		return nil, ErrNotFound
+	}
+	remote, err := e.getRemote(ctx, owner)
+	if err != nil {
+		return nil, fmt.Errorf("remote %q: %w", owner, err)
+	}
+	body, err := e.ansibleDoc(ctx, *remote, ansible.VersionPath(ns, name, version)[1:])
+	if err != nil {
+		return nil, fmt.Errorf("member %q: %v", owner, err)
+	}
+	var detail map[string]any
+	if err := json.Unmarshal(body, &detail); err != nil {
+		return nil, fmt.Errorf("member %q version detail: %v", owner, err)
+	}
+	dl, _ := detail["download_url"].(string)
+	u, err := url.Parse(dl)
+	if err != nil {
+		return nil, fmt.Errorf("member %q download_url %q: %v", owner, dl, err)
+	}
+	rest, ok := strings.CutPrefix(u.EscapedPath(), "/api/v1/"+string(remote.RepoType)+"/"+url.PathEscape(owner)+"/")
+	if !ok || u.Scheme != "" || u.Host != "" {
+		return nil, fmt.Errorf("member %q download_url %q is not served by the member", owner, dl)
+	}
+	base := strings.TrimRight(proxyBaseURL, "/") + "/api/v1/virtual/" + url.PathEscape(virt.Name)
+	detail["download_url"] = base + "/" + url.PathEscape(owner) + "/" + rest
+	detail["href"] = base + ansible.VersionPath(ns, name, version)
+	return json.Marshal(detail)
+}
+
+// ansibleMember reads every version a member lists for ns.name, following
+// the member's pagination for remotes.
+func (e *Engine) ansibleMember(ctx context.Context, member, ns, name string) (*AnsibleMember, error) {
+	remote, err := e.getRemote(ctx, member)
+	if err != nil {
+		return nil, fmt.Errorf("remote %q: %w", member, err)
+	}
+	m := &AnsibleMember{RemoteName: member}
+	list := ansible.CollectionPath(ns, name)[1:] + "versions/"
+	for page := 0; page < maxAnsibleMemberPages; page++ {
+		// Locals list every version at once; remote pages match the keys the
+		// remote caches client requests under.
+		path := list
+		if remote.RepoType != models.RepoTypeLocal {
+			path += "?limit=" + strconv.Itoa(ansibleMemberPage)
+			if page > 0 {
+				path += "&offset=" + strconv.Itoa(len(m.Refs))
+			}
+		}
+		body, err := e.ansibleDoc(ctx, *remote, path)
+		var pe *proxy.ProxyError
+		if errors.Is(err, ErrNotFound) || errors.As(err, &pe) && pe.Status == http.StatusNotFound {
+			return m, nil
+		}
+		if err != nil {
+			return nil, err
+		}
+		var doc struct {
+			Meta struct{ Count int }
+			Data []ansible.VersionRef
+		}
+		if err := json.Unmarshal(body, &doc); err != nil {
+			return nil, fmt.Errorf("%s/%s: %v", member, path, err)
+		}
+		m.Found = true
+		m.Refs = append(m.Refs, doc.Data...)
+		if remote.RepoType == models.RepoTypeLocal || len(m.Refs) >= doc.Meta.Count {
+			return m, nil
+		}
+		if len(doc.Data) == 0 {
+			return nil, fmt.Errorf("%s/%s: empty page after %d of %d versions", member, path, len(m.Refs), doc.Meta.Count)
+		}
+	}
+	return nil, fmt.Errorf("%s: more than %d pages of %s.%s versions", member, maxAnsibleMemberPages, ns, name)
+}
+
+// ansibleMemberDoc reads a Galaxy API document from a member.
+func (e *Engine) ansibleMemberDoc(ctx context.Context, remote models.Remote, path string) ([]byte, error) {
+	if remote.RepoType != models.RepoTypeLocal {
+		return e.fetchMemberPath(ctx, remote, path)
+	}
+	if e.AnsibleLocal == nil {
+		return nil, errors.New("local ansible indexes are not wired")
+	}
+	return e.AnsibleLocal(ctx, remote.Name, path)
+}

internal/virtual/ansible_merger_test.go

@@ -0,0 +1,206 @@
+package virtual
+
+import (
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"net/http"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider/ansible"
+	"git.unkin.net/unkin/artifactapi/internal/proxy"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func refs(vs ...string) []ansible.VersionRef {
+	out := make([]ansible.VersionRef, len(vs))
+	for i, v := range vs {
+		out[i] = ansible.VersionRef{Version: v}
+	}
+	return out
+}
+
+func TestMergeAnsibleVersionsMemberOrderWins(t *testing.T) {
+	d, err := MergeAnsibleVersions([]AnsibleMember{
+		{RemoteName: "internal", Found: true, Refs: refs("2.0.0", "1.0.0")},
+		{RemoteName: "missing"},
+		{RemoteName: "galaxy", Found: true, Refs: refs("3.0.0", "2.0.0", "0.9.0")},
+	})
+	if err != nil {
+		t.Fatal(err)
+	}
+	var got []string
+	for _, r := range d.Refs {
+		got = append(got, r.Version)
+	}
+	if strings.Join(got, ",") != "2.0.0,1.0.0,3.0.0,0.9.0" {
+		t.Fatalf("merged = %v", got)
+	}
+	for v, owner := range map[string]string{"2.0.0": "internal", "1.0.0": "internal", "3.0.0": "galaxy", "0.9.0": "galaxy"} {
+		if d.Owners[v] != owner {
+			t.Errorf("owner of %s = %q, want %q", v, d.Owners[v], owner)
+		}
+	}
+	if _, err := MergeAnsibleVersions([]AnsibleMember{{RemoteName: "a"}, {RemoteName: "b"}}); !errors.Is(err, ErrNotFound) {
+		t.Fatalf("no member has it: want ErrNotFound, got %v", err)
+	}
+	if d, err := MergeAnsibleVersions([]AnsibleMember{{RemoteName: "a", Found: true}}); err != nil || len(d.Refs) != 0 {
+		t.Fatalf("found with no versions = %v %v", d, err)
+	}
+}
+
+// galaxyPages answers a remote's versions list like Galaxy, two per page.
+func galaxyPages(versions []string, path string) ([]byte, error) {
+	_, q, _ := strings.Cut(path, "?")
+	offset := 0
+	if _, off, ok := strings.Cut(q, "offset="); ok {
+		_, _ = fmt.Sscan(off, &offset)
+	}
+	end := min(offset+2, len(versions))
+	return json.Marshal(map[string]any{"meta": map[string]int{"count": len(versions)}, "data": refs(versions[min(offset, end):end]...)})
+}
+
+func ansibleEngine(doc func(remote models.Remote, path string) ([]byte, error)) *Engine {
+	return &Engine{
+		mergeTTL: time.Minute,
+		getRemote: func(_ context.Context, name string) (*models.Remote, error) {
+			rt := models.RepoTypeRemote
+			if name == "internal" {
+				rt = models.RepoTypeLocal
+			}
+			return &models.Remote{Name: name, RepoType: rt}, nil
+		},
+		ansibleDoc: func(_ context.Context, remote models.Remote, path string) ([]byte, error) { return doc(remote, path) },
+	}
+}
+
+func ansibleVirt(members ...string) models.Virtual {
+	return models.Virtual{Name: "ansible", PackageType: models.PackageAnsible, Members: members}
+}
+
+func TestAnsibleVersionsFollowsRemotePages(t *testing.T) {
+	var mu sync.Mutex
+	var asked []string
+	e := ansibleEngine(func(remote models.Remote, path string) ([]byte, error) {
+		mu.Lock()
+		asked = append(asked, remote.Name+" "+path)
+		mu.Unlock()
+		if remote.Name == "internal" {
+			return galaxyPages([]string{"1.0.0", "5.0.0"}, "")
+		}
+		return galaxyPages([]string{"5.0.0", "4.0.0", "3.0.0", "2.0.0", "1.5.0"}, path)
+	})
+	virt := ansibleVirt("internal", "galaxy")
+	d, err := e.AnsibleVersions(context.Background(), virt, "community", "general")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(d.Refs) != 6 || d.Owners["5.0.0"] != "internal" || d.Owners["1.5.0"] != "galaxy" {
+		t.Fatalf("merged = %+v", d)
+	}
+	want := map[string]bool{
+		"internal api/v3/collections/community/general/versions/":                  true,
+		"galaxy api/v3/collections/community/general/versions/?limit=100":          true,
+		"galaxy api/v3/collections/community/general/versions/?limit=100&offset=2": true,
+		"galaxy api/v3/collections/community/general/versions/?limit=100&offset=4": true,
+	}
+	if len(asked) != len(want) {
+		t.Fatalf("asked %v", asked)
+	}
+	for _, a := range asked {
+		if !want[a] {
+			t.Errorf("unexpected fetch %q", a)
+		}
+	}
+	if _, err := e.AnsibleVersions(context.Background(), virt, "community", "general"); err != nil || len(asked) != len(want) {
+		t.Fatalf("merge not cached: %v, %d fetches", err, len(asked))
+	}
+}
+
+func TestAnsibleVersionsFailsClosed(t *testing.T) {
+	e := ansibleEngine(func(remote models.Remote, path string) ([]byte, error) {
+		switch remote.Name {
+		case "internal":
+			return nil, ErrNotFound
+		case "gone":
+			return nil, &proxy.ProxyError{Status: http.StatusNotFound}
+		}
+		return nil, errors.New("upstream down")
+	})
+	if _, err := e.AnsibleVersions(context.Background(), ansibleVirt("internal", "gone"), "a", "b"); !errors.Is(err, ErrNotFound) {
+		t.Fatalf("all members lack it: want ErrNotFound, got %v", err)
+	}
+	if _, err := e.AnsibleVersions(context.Background(), ansibleVirt("internal", "galaxy"), "a", "b"); err == nil || errors.Is(err, ErrNotFound) {
+		t.Fatalf("member error: want a non-404 error, got %v", err)
+	}
+}
+
+func TestAnsibleVersionsShortRemote(t *testing.T) {
+	e := ansibleEngine(func(_ models.Remote, path string) ([]byte, error) {
+		if strings.Contains(path, "offset=") {
+			return json.Marshal(map[string]any{"meta": map[string]int{"count": 3}, "data": []any{}})
+		}
+		return galaxyPages([]string{"3.0.0", "2.0.0", "1.0.0"}, path)
+	})
+	if _, err := e.AnsibleVersions(context.Background(), ansibleVirt("galaxy"), "a", "b"); err == nil || errors.Is(err, ErrNotFound) {
+		t.Fatalf("empty page before count: want a non-404 error, got %v", err)
+	}
+}
+
+func TestAnsibleVersionRoutesViaVirtual(t *testing.T) {
+	detail := func(dl string) []byte {
+		b, _ := json.Marshal(map[string]any{"version": "1.0.0", "download_url": dl, "artifact": map[string]string{"sha256": "ab"}})
+		return b
+	}
+	dls := map[string]string{
+		"internal": "/api/v1/local/internal/artifacts/a-b-1.0.0.tar.gz",
+		"galaxy":   "/api/v1/remote/galaxy/api/v3/plugin/ansible/content/published/collections/artifacts/a-b-2.0.0.tar.gz",
+		"evil":     "https://evil.example/api/v1/remote/evil/x.tar.gz",
+		"other":    "/api/v1/remote/someoneelse/x.tar.gz",
+	}
+	e := ansibleEngine(func(remote models.Remote, path string) ([]byte, error) {
+		if strings.Contains(path, "/versions/?") || strings.HasSuffix(path, "/versions/") {
+			v := map[string]string{"internal": "1.0.0", "galaxy": "2.0.0", "evil": "3.0.0", "other": "4.0.0"}[remote.Name]
+			return galaxyPages([]string{v}, path)
+		}
+		return detail(dls[remote.Name]), nil
+	})
+	virt := ansibleVirt("internal", "galaxy", "evil", "other")
+	for v, want := range map[string]string{
+		"1.0.0": "https://h/api/v1/virtual/ansible/internal/artifacts/a-b-1.0.0.tar.gz",
+		"2.0.0": "https://h/api/v1/virtual/ansible/galaxy/api/v3/plugin/ansible/content/published/collections/artifacts/a-b-2.0.0.tar.gz",
+	} {
+		body, err := e.AnsibleVersion(context.Background(), virt, "a", "b", v, "https://h")
+		if err != nil {
+			t.Fatal(err)
+		}
+		var got struct {
+			Href        string
+			DownloadURL string `json:"download_url"`
+			Artifact    struct{ Sha256 string }
+		}
+		_ = json.Unmarshal(body, &got)
+		if got.DownloadURL != want || got.Href != "https://h/api/v1/virtual/ansible/api/v3/collections/a/b/versions/"+v+"/" || got.Artifact.Sha256 != "ab" {
+			t.Errorf("%s detail = %+v", v, got)
+		}
+		loc, ok, err := e.MemberRedirect(context.Background(), virt, strings.TrimPrefix(want, "https://h/api/v1/virtual/ansible/"), "", "https://h")
+		if err != nil || !ok || loc != "https://h"+dls[map[string]string{"1.0.0": "internal", "2.0.0": "galaxy"}[v]] {
+			t.Errorf("%s redirect = %q %v %v", v, loc, ok, err)
+		}
+	}
+	for _, v := range []string{"3.0.0", "4.0.0"} {
+		if _, err := e.AnsibleVersion(context.Background(), virt, "a", "b", v, "https://h"); err == nil || errors.Is(err, ErrNotFound) {
+			t.Errorf("%s: foreign download_url accepted: %v", v, err)
+		}
+	}
+	if _, err := e.AnsibleVersion(context.Background(), virt, "a", "b", "9.9.9", "https://h"); !errors.Is(err, ErrNotFound) {
+		t.Errorf("unknown version: want ErrNotFound, got %v", err)
+	}
+	if _, _, err := e.MemberRedirect(context.Background(), virt, "galaxy/../internal/x", "", "https://h"); !errors.Is(err, ErrBadPath) {
+		t.Errorf("escaping redirect: want ErrBadPath, got %v", err)
+	}
+}

internal/virtual/engine.go

@@ -32,6 +32,17 @@ type Engine struct {
 	// to the repo, or ErrNotFound.
 	NPMLocal func(ctx context.Context, repo, pkg string) ([]byte, error)
 
+	gemsMember func(ctx context.Context, name, path string) (*GemsMember, error)
+
+	// GemsLocal returns a local gems repo's versions, names or info/<gem>, or
+	// ErrNotFound.
+	GemsLocal func(ctx context.Context, repo, path string) ([]byte, error)
+
+	// AnsibleLocal returns a local ansible repo's collection, full versions list
+	// or version detail with root-relative URLs, or ErrNotFound.
+	AnsibleLocal func(ctx context.Context, repo, path string) ([]byte, error)
+	ansibleDoc   func(ctx context.Context, remote models.Remote, path string) ([]byte, error)
+
 	mergeTTL time.Duration
 
 	sf   singleflight.Group
@@ -61,6 +72,8 @@ func NewEngine(db *database.DB, proxyEngine *proxy.Engine) *Engine {
 	e := &Engine{db: db, proxyEngine: proxyEngine, getRemote: db.GetRemote, mergeTTL: rpmMergeTTL}
 	e.rpmMember = e.fetchRPMMember
 	e.npmMember = e.fetchNPMMember
+	e.gemsMember = e.fetchGemsMember
+	e.ansibleDoc = e.ansibleMemberDoc
 	return e
 }
 
@@ -185,16 +198,17 @@ var (
 	ErrBadPath  = errors.New("invalid path")
 )
 
-// MemberRedirect maps an rpm or npm virtual package path (<member>/<href>, as
-// written by MergeRPM/MergeNPM) to the owning member's route. ok is false for
-// any other path; ErrBadPath means the path is absolute or escapes the member.
+// MemberRedirect maps an rpm, npm or ansible virtual package path
+// (<member>/<href>, as written by MergeRPM/MergeNPM/AnsibleVersion) to the
+// owning member's route. ok is false for any other path; ErrBadPath means the
+// path is absolute or escapes the member.
 func (e *Engine) MemberRedirect(ctx context.Context, virt models.Virtual, path, rawQuery, proxyBaseURL string) (string, bool, error) {
 	switch virt.PackageType {
 	case models.PackageRPM:
 		if strings.HasPrefix(path, "repodata/") {
 			return "", false, nil
 		}
-	case models.PackageNPM:
+	case models.PackageNPM, models.PackageAnsible:
 	default:
 		return "", false, nil
 	}
@@ -202,6 +216,11 @@ func (e *Engine) MemberRedirect(ctx context.Context, virt models.Virtual, path,
 	if !found || !slices.Contains(virt.Members, name) {
 		return "", false, nil
 	}
+	return e.memberLocation(ctx, name, rest, rawQuery, proxyBaseURL)
+}
+
+// memberLocation returns the URL of rest on member name's own route.
+func (e *Engine) memberLocation(ctx context.Context, name, rest, rawQuery, proxyBaseURL string) (string, bool, error) {
 	segs, err := memberSegments(rest)
 	if err != nil {
 		return "", false, err

internal/virtual/gems_merger.go

@@ -0,0 +1,294 @@
+package virtual
+
+import (
+	"bytes"
+	"context"
+	"errors"
+	"fmt"
+	"net/http"
+	"slices"
+	"strings"
+	"time"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider/gems"
+	"git.unkin.net/unkin/artifactapi/internal/proxy"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+const (
+	maxGemsInfos      = 1024
+	maxGemsCandidates = 8
+)
+
+// GemsMember is one member's compact index document; Body is nil when the
+// member does not have it.
+type GemsMember struct {
+	RemoteName string
+	Body       []byte
+}
+
+// GemsDoc is a merged compact index document. Owners maps each /info
+// version[-platform] to the member serving it.
+type GemsDoc struct {
+	Body   []byte
+	Owners map[string]string
+}
+
+func (d *GemsDoc) index() []byte            { return d.Body }
+func (d *GemsDoc) files() map[string][]byte { return nil }
+
+// MergeGemsInfo unions /info lines across members; the first member wins a
+// duplicate version-platform. A gem only one member has is passed through
+// verbatim so its md5 matches that member's /versions. ErrNotFound means no
+// member has the gem.
+func MergeGemsInfo(members []GemsMember) (*GemsDoc, error) {
+	var have []GemsMember
+	for _, m := range members {
+		if m.Body != nil {
+			have = append(have, m)
+		}
+	}
+	if len(have) == 0 {
+		return nil, ErrNotFound
+	}
+	d := &GemsDoc{Owners: map[string]string{}}
+	var lines []string
+	for _, m := range have {
+		for _, l := range gems.InfoLines(m.Body) {
+			k := gems.InfoKey(l)
+			if _, dup := d.Owners[k]; dup {
+				continue
+			}
+			d.Owners[k] = m.RemoteName
+			lines = append(lines, l)
+		}
+	}
+	if len(have) == 1 {
+		d.Body = have[0].Body
+	} else {
+		d.Body = gems.InfoBody(lines)
+	}
+	return d, nil
+}
+
+// versionsLines returns the entry lines of a /versions document.
+func versionsLines(m GemsMember) ([]byte, error) {
+	if m.Body == nil {
+		return nil, fmt.Errorf("member %q has no versions", m.RemoteName)
+	}
+	if bytes.HasPrefix(m.Body, []byte("---\n")) {
+		return m.Body[4:], nil
+	}
+	_, rest, ok := bytes.Cut(m.Body, []byte("\n---\n"))
+	if !ok {
+		return nil, fmt.Errorf("member %q versions has no --- separator", m.RemoteName)
+	}
+	return rest, nil
+}
+
+func gemName(line []byte) string {
+	n, _, _ := bytes.Cut(line, []byte(" "))
+	return string(bytes.TrimSpace(n))
+}
+
+// MergeGemsVersions passes through the lines of gems only one member lists
+// and writes one regenerated line, from the merged /info, per gem that
+// several members list.
+func MergeGemsVersions(members []GemsMember, info func(name string) (*GemsDoc, error), at time.Time) ([]byte, error) {
+	bodies := make([][]byte, len(members))
+	owners := map[string]int{}
+	for i, m := range members {
+		rest, err := versionsLines(m)
+		if err != nil {
+			return nil, err
+		}
+		bodies[i] = rest
+		seen := map[string]bool{}
+		for line := range bytes.Lines(rest) {
+			if n := gemName(line); n != "" && !seen[n] {
+				seen[n] = true
+				owners[n]++
+			}
+		}
+	}
+	var b bytes.Buffer
+	b.WriteString(gems.VersionsHeader(at))
+	var shared []string
+	for _, rest := range bodies {
+		for line := range bytes.Lines(rest) {
+			n := gemName(line)
+			if n == "" {
+				continue
+			}
+			if owners[n] > 1 {
+				if !slices.Contains(shared, n) {
+					shared = append(shared, n)
+				}
+				continue
+			}
+			b.Write(bytes.TrimRight(line, "\n"))
+			b.WriteByte('\n')
+		}
+	}
+	for _, n := range shared {
+		d, err := info(n)
+		if errors.Is(err, ErrNotFound) {
+			continue
+		}
+		if err != nil {
+			return nil, err
+		}
+		b.WriteString(gems.VersionsLine(n, d.Body) + "\n")
+	}
+	return b.Bytes(), nil
+}
+
+// MergeGemsNames unions member /names documents, sorted.
+func MergeGemsNames(members []GemsMember) ([]byte, error) {
+	set := map[string]bool{}
+	for _, m := range members {
+		rest, err := versionsLines(m)
+		if err != nil {
+			return nil, err
+		}
+		for line := range bytes.Lines(rest) {
+			if n := gemName(line); n != "" {
+				set[n] = true
+			}
+		}
+	}
+	names := make([]string, 0, len(set))
+	for n := range set {
+		names = append(names, n)
+	}
+	slices.Sort(names)
+	return []byte("---\n" + strings.Join(names, "\n") + "\n"), nil
+}
+
+// FetchGems serves a gems virtual's merged versions, names or info/<gem>.
+func (e *Engine) FetchGems(ctx context.Context, virt models.Virtual, path string) ([]byte, string, error) {
+	var d *GemsDoc
+	var err error
+	switch {
+	case strings.HasPrefix(path, "info/"):
+		name := strings.TrimPrefix(path, "info/")
+		if !gems.NameRe.MatchString(name) {
+			return nil, "", ErrNotFound
+		}
+		d, err = e.gemsInfo(ctx, virt, name)
+	case path == "versions":
+		d, err = e.gemsMerged(ctx, virt, path, func(ctx context.Context, ms []GemsMember) ([]byte, error) {
+			return MergeGemsVersions(ms, func(name string) (*GemsDoc, error) { return e.gemsInfo(ctx, virt, name) }, time.Now())
+		})
+	case path == "names":
+		d, err = e.gemsMerged(ctx, virt, path, func(_ context.Context, ms []GemsMember) ([]byte, error) {
+			return MergeGemsNames(ms)
+		})
+	default:
+		return nil, "", ErrNotFound
+	}
+	if err != nil {
+		return nil, "", err
+	}
+	return d.Body, "text/plain; charset=utf-8", nil
+}
+
+func (e *Engine) gemsMerged(ctx context.Context, virt models.Virtual, path string, merge func(context.Context, []GemsMember) ([]byte, error)) (*GemsDoc, error) {
+	repo, err := e.merged(ctx, "gems\x00"+virt.Name+"\x00"+path, func(ctx context.Context) (mergedRepo, error) {
+		members, err := fetchMembers(virt, func(name string) (*GemsMember, error) { return e.gemsMember(ctx, name, path) })
+		if err != nil {
+			return nil, err
+		}
+		body, err := merge(ctx, members)
+		if err != nil {
+			return nil, err
+		}
+		return &GemsDoc{Body: body}, nil
+	})
+	if err != nil {
+		return nil, err
+	}
+	return repo.(*GemsDoc), nil
+}
+
+func (e *Engine) gemsInfo(ctx context.Context, virt models.Virtual, name string) (*GemsDoc, error) {
+	prefix := "gems\x00" + virt.Name + "\x00info/"
+	inserted := false
+	repo, err := e.merged(ctx, prefix+name, func(ctx context.Context) (mergedRepo, error) {
+		inserted = true
+		members, err := fetchMembers(virt, func(m string) (*GemsMember, error) { return e.gemsMember(ctx, m, "info/"+name) })
+		if err != nil {
+			return nil, err
+		}
+		return MergeGemsInfo(members)
+	})
+	if err != nil {
+		return nil, err
+	}
+	if inserted {
+		e.evictOldest(prefix, maxGemsInfos)
+	}
+	return repo.(*GemsDoc), nil
+}
+
+// GemsRedirect maps a gems virtual download (gems/<full>.gem or
+// quick/Marshal.4.8/<full>.gemspec.rz) to the member whose /info line won the
+// merge for that version-platform.
+func (e *Engine) GemsRedirect(ctx context.Context, virt models.Virtual, path, rawQuery, proxyBaseURL string) (string, error) {
+	full, ok := strings.CutPrefix(path, "gems/")
+	if ok {
+		full, ok = strings.CutSuffix(full, ".gem")
+	} else if full, ok = strings.CutPrefix(path, "quick/Marshal.4.8/"); ok {
+		full, ok = strings.CutSuffix(full, ".gemspec.rz")
+	}
+	if !ok || strings.Contains(full, "/") {
+		return "", ErrNotFound
+	}
+	tried := 0
+	for i := 1; i < len(full)-1 && tried < maxGemsCandidates; i++ {
+		if full[i] != '-' || full[i+1] < '0' || full[i+1] > '9' || !gems.NameRe.MatchString(full[:i]) {
+			continue
+		}
+		tried++
+		d, err := e.gemsInfo(ctx, virt, full[:i])
+		if errors.Is(err, ErrNotFound) {
+			continue
+		}
+		if err != nil {
+			return "", err
+		}
+		if owner, ok := d.Owners[full[i+1:]]; ok {
+			loc, ok, err := e.memberLocation(ctx, owner, path, rawQuery, proxyBaseURL)
+			if err == nil && !ok {
+				err = ErrNotFound
+			}
+			return loc, err
+		}
+	}
+	return "", ErrNotFound
+}
+
+// fetchGemsMember returns a nil Body when the member lacks the document.
+func (e *Engine) fetchGemsMember(ctx context.Context, name, path string) (*GemsMember, error) {
+	remote, err := e.getRemote(ctx, name)
+	if err != nil {
+		return nil, fmt.Errorf("remote %q: %w", name, err)
+	}
+	m := &GemsMember{RemoteName: name}
+	if remote.RepoType == models.RepoTypeLocal {
+		if e.GemsLocal == nil {
+			return nil, errors.New("local gems indexes are not wired")
+		}
+		m.Body, err = e.GemsLocal(ctx, name, path)
+	} else {
+		m.Body, err = e.fetchMemberPath(ctx, *remote, path)
+	}
+	var pe *proxy.ProxyError
+	if errors.Is(err, ErrNotFound) || errors.As(err, &pe) && pe.Status == http.StatusNotFound {
+		return &GemsMember{RemoteName: name}, nil
+	}
+	if err != nil {
+		return nil, err
+	}
+	return m, nil
+}

internal/virtual/gems_merger_test.go

@@ -0,0 +1,180 @@
+package virtual
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider/gems"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func TestMergeGemsInfoMemberOrderWins(t *testing.T) {
+	local := GemsMember{RemoteName: "internal", Body: []byte("---\n1.0.0 |checksum:aa\n1.0.0-java |checksum:ab\n")}
+	remote := GemsMember{RemoteName: "rubygems", Body: []byte("---\n0.9.0 |checksum:99\n1.0.0 |checksum:bb\n2.0.0 rack:>= 0|checksum:cc,ruby:>= 3.0\n")}
+	d, err := MergeGemsInfo([]GemsMember{local, {RemoteName: "empty"}, remote})
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := "---\n1.0.0 |checksum:aa\n1.0.0-java |checksum:ab\n0.9.0 |checksum:99\n2.0.0 rack:>= 0|checksum:cc,ruby:>= 3.0\n"
+	if string(d.Body) != want {
+		t.Fatalf("merged info =\n%q\nwant\n%q", d.Body, want)
+	}
+	for k, owner := range map[string]string{"1.0.0": "internal", "1.0.0-java": "internal", "0.9.0": "rubygems", "2.0.0": "rubygems"} {
+		if d.Owners[k] != owner {
+			t.Errorf("owner of %s = %q, want %q", k, d.Owners[k], owner)
+		}
+	}
+
+	odd := GemsMember{RemoteName: "rubygems", Body: []byte("---\n1.0.0 |checksum:bb\n\n")}
+	if d, _ := MergeGemsInfo([]GemsMember{{RemoteName: "internal"}, odd}); string(d.Body) != string(odd.Body) {
+		t.Fatalf("a gem only one member has must pass through verbatim, got %q", d.Body)
+	}
+	if _, err := MergeGemsInfo([]GemsMember{{RemoteName: "a"}}); !errors.Is(err, ErrNotFound) {
+		t.Fatalf("want ErrNotFound, got %v", err)
+	}
+}
+
+func TestMergeGemsVersions(t *testing.T) {
+	local := GemsMember{RemoteName: "internal", Body: []byte("created_at: 2026-10-18T00:00:00Z\n---\nhello 0.1.0 11\nrack 9.0.0 22\n")}
+	remote := GemsMember{RemoteName: "rubygems", Body: []byte("created_at: 2024-04-01T00:00:05Z\n---\n" +
+		"rack 1.0.0,2.0.0 33\nrails 7.0.0 44\nrack -1.0.0,3.0.0 55\n")}
+	merged := &GemsDoc{Body: []byte("---\n9.0.0 |checksum:x\n2.0.0 |checksum:y\n3.0.0 |checksum:z\n")}
+	var asked []string
+	at := time.Date(2026, 10, 18, 1, 2, 3, 0, time.UTC)
+	body, err := MergeGemsVersions([]GemsMember{local, remote}, func(name string) (*GemsDoc, error) {
+		asked = append(asked, name)
+		return merged, nil
+	}, at)
+	if err != nil {
+		t.Fatal(err)
+	}
+	want := "created_at: 2026-10-18T01:02:03Z\n---\nhello 0.1.0 11\nrails 7.0.0 44\nrack 9.0.0,2.0.0,3.0.0 " + gems.MD5Hex(merged.Body) + "\n"
+	if string(body) != want {
+		t.Fatalf("versions =\n%q\nwant\n%q", body, want)
+	}
+	if len(asked) != 1 || asked[0] != "rack" {
+		t.Fatalf("merged info fetched for %v, want only the shared gem", asked)
+	}
+
+	if _, err := MergeGemsVersions([]GemsMember{{RemoteName: "x", Body: []byte("no separator")}}, nil, at); err == nil {
+		t.Fatal("malformed member versions must fail")
+	}
+	if _, err := MergeGemsVersions([]GemsMember{{RemoteName: "x"}}, nil, at); err == nil {
+		t.Fatal("a member without versions must fail")
+	}
+}
+
+func TestMergeGemsNames(t *testing.T) {
+	body, err := MergeGemsNames([]GemsMember{{RemoteName: "a", Body: []byte("---\nzeta\nalpha\n")}, {RemoteName: "b", Body: []byte("---\nalpha\nmid\n")}})
+	if err != nil || string(body) != "---\nalpha\nmid\nzeta\n" {
+		t.Fatalf("names = %q %v", body, err)
+	}
+}
+
+func gemsEngine(fetch func(name, path string) (*GemsMember, error)) *Engine {
+	return &Engine{
+		mergeTTL: time.Minute,
+		getRemote: func(_ context.Context, name string) (*models.Remote, error) {
+			rt := models.RepoTypeRemote
+			if name == "internal" {
+				rt = models.RepoTypeLocal
+			}
+			return &models.Remote{Name: name, RepoType: rt}, nil
+		},
+		gemsMember: func(_ context.Context, name, path string) (*GemsMember, error) { return fetch(name, path) },
+	}
+}
+
+func gemsVirt(members ...string) models.Virtual {
+	return models.Virtual{Name: "gems", PackageType: models.PackageGems, Members: members}
+}
+
+func TestGemsRedirectToOwner(t *testing.T) {
+	var mu sync.Mutex
+	asked := map[string]int{}
+	e := gemsEngine(func(name, path string) (*GemsMember, error) {
+		mu.Lock()
+		asked[name+" "+path]++
+		mu.Unlock()
+		switch name + " " + path {
+		case "internal info/foo-2fa":
+			return &GemsMember{RemoteName: name, Body: []byte("---\n1.0.0 |checksum:a\n")}, nil
+		case "rubygems info/foo-2fa":
+			return &GemsMember{RemoteName: name, Body: []byte("---\n1.0.0 |checksum:b\n1.1.0-x86_64-linux |checksum:c\n")}, nil
+		case "rubygems info/foo":
+			return &GemsMember{RemoteName: name, Body: []byte("---\n2.0.0 |checksum:d\n")}, nil
+		}
+		return &GemsMember{RemoteName: name}, nil
+	})
+	virt := gemsVirt("internal", "rubygems")
+	for path, want := range map[string]string{
+		"gems/foo-2fa-1.0.0.gem":                     "http://host/api/v1/local/internal/gems/foo-2fa-1.0.0.gem",
+		"gems/foo-2fa-1.1.0-x86_64-linux.gem":        "http://host/api/v1/remote/rubygems/gems/foo-2fa-1.1.0-x86_64-linux.gem",
+		"quick/Marshal.4.8/foo-2fa-1.0.0.gemspec.rz": "http://host/api/v1/local/internal/quick/Marshal.4.8/foo-2fa-1.0.0.gemspec.rz",
+		"quick/Marshal.4.8/foo-2.0.0.gemspec.rz":     "http://host/api/v1/remote/rubygems/quick/Marshal.4.8/foo-2.0.0.gemspec.rz",
+	} {
+		loc, err := e.GemsRedirect(context.Background(), virt, path, "", "http://host")
+		if err != nil || loc != want {
+			t.Errorf("%s -> %q %v, want %q", path, loc, err, want)
+		}
+	}
+	for _, path := range []string{"gems/foo-2fa-9.9.9.gem", "gems/nodash.gem", "gems/x/../foo-2.0.0.gem", "other/foo-2.0.0.gem", "specs.4.8.gz"} {
+		if _, err := e.GemsRedirect(context.Background(), virt, path, "", "http://host"); !errors.Is(err, ErrNotFound) {
+			t.Errorf("%s: want ErrNotFound, got %v", path, err)
+		}
+	}
+	if asked["internal info/foo-2fa"] != 1 {
+		t.Fatalf("merged info must be cached across redirects, internal asked %d times", asked["internal info/foo-2fa"])
+	}
+}
+
+func TestFetchGemsFailsClosed(t *testing.T) {
+	e := gemsEngine(func(name, path string) (*GemsMember, error) {
+		if name == "rubygems" {
+			return nil, errors.New("upstream down")
+		}
+		return &GemsMember{RemoteName: name, Body: []byte("created_at: x\n---\nhello 0.1.0 11\n")}, nil
+	})
+	for _, path := range []string{"versions", "names", "info/hello"} {
+		if _, _, err := e.FetchGems(context.Background(), gemsVirt("internal", "rubygems"), path); err == nil || errors.Is(err, ErrNotFound) {
+			t.Errorf("%s: want member error, got %v", path, err)
+		}
+	}
+	if _, err := e.GemsRedirect(context.Background(), gemsVirt("internal", "rubygems"), "gems/hello-0.1.0.gem", "", "http://h"); err == nil || errors.Is(err, ErrNotFound) {
+		t.Errorf("redirect: want member error, got %v", err)
+	}
+}
+
+func TestFetchGemsVersionsUsesMergedInfo(t *testing.T) {
+	e := gemsEngine(func(name, path string) (*GemsMember, error) {
+		docs := map[string]string{
+			"internal versions":  "created_at: x\n---\nrack 9.0.0 11\n",
+			"rubygems versions":  "created_at: y\n---\nrack 3.0.0 22\nrails 7.0.0 33\n",
+			"internal info/rack": "---\n9.0.0 |checksum:a\n",
+			"rubygems info/rack": "---\n3.0.0 |checksum:b\n",
+		}
+		if d, ok := docs[name+" "+path]; ok {
+			return &GemsMember{RemoteName: name, Body: []byte(d)}, nil
+		}
+		return &GemsMember{RemoteName: name}, nil
+	})
+	virt := gemsVirt("internal", "rubygems")
+	info, ct, err := e.FetchGems(context.Background(), virt, "info/rack")
+	if err != nil || !strings.HasPrefix(ct, "text/plain") {
+		t.Fatalf("info: %v %q", err, ct)
+	}
+	versions, _, err := e.FetchGems(context.Background(), virt, "versions")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(string(versions), "\nrails 7.0.0 33\nrack 9.0.0,3.0.0 "+gems.MD5Hex(info)+"\n") {
+		t.Fatalf("versions = %q", versions)
+	}
+	if _, _, err := e.FetchGems(context.Background(), virt, "info/../x"); !errors.Is(err, ErrNotFound) {
+		t.Fatalf("bad name: %v", err)
+	}
+}

migrations/0003_github_sync_state_cascade.sql

@@ -0,0 +1,12 @@
+-- Sync state is dropped with its remote, so a recreated remote of the same name
+-- starts with no inherited ETag or timing. NOT VALID skips checking rows left by
+-- remotes deleted before this migration, which would otherwise fail it.
+ALTER TABLE github_rpm_sync_state    DROP CONSTRAINT IF EXISTS github_rpm_sync_state_remote_fk;
+ALTER TABLE github_rpm_sync_state    ADD CONSTRAINT github_rpm_sync_state_remote_fk
+	FOREIGN KEY (remote_name) REFERENCES remotes(name) ON DELETE CASCADE NOT VALID;
+ALTER TABLE github_deb_sync_state    DROP CONSTRAINT IF EXISTS github_deb_sync_state_remote_fk;
+ALTER TABLE github_deb_sync_state    ADD CONSTRAINT github_deb_sync_state_remote_fk
+	FOREIGN KEY (remote_name) REFERENCES remotes(name) ON DELETE CASCADE NOT VALID;
+ALTER TABLE github_alpine_sync_state DROP CONSTRAINT IF EXISTS github_alpine_sync_state_remote_fk;
+ALTER TABLE github_alpine_sync_state ADD CONSTRAINT github_alpine_sync_state_remote_fk
+	FOREIGN KEY (remote_name) REFERENCES remotes(name) ON DELETE CASCADE NOT VALID;

pkg/models/package_type_ansible.go

@@ -0,0 +1,5 @@
+package models
+
+const PackageAnsible PackageType = "ansible"
+
+func init() { registerPackageType(PackageAnsible) }

ui/src/packagetypes/defs/ansible.ts

@@ -0,0 +1,28 @@
+import type { PackageTypeUI } from '../types';
+
+const def: PackageTypeUI = {
+  color: 'red',
+  snippets: ({ name, url, proxy, isLocal }) => {
+    if (isLocal) {
+      const src = `${url}/api/v1/local/${name}/`;
+      return [
+        {
+          title: 'Publish and install',
+          language: 'bash',
+          code: `ansible-galaxy collection publish <ns>-<name>-<version>.tar.gz --server ${src} --api-key unused
+ansible-galaxy collection install <ns>.<name> --server ${src}`,
+          note: 'publish needs an API key; any value works. Publishing an existing version is rejected.',
+        },
+      ];
+    }
+    return [
+      {
+        title: 'Install collections through this Galaxy proxy',
+        language: 'bash',
+        code: `ansible-galaxy collection install community.general -s ${proxy}/api/`,
+      },
+    ];
+  },
+};
+
+export default def;

ui/src/packagetypes/defs/gems.ts

@@ -2,7 +2,26 @@ import type { PackageTypeUI } from '../types';
 
 const def: PackageTypeUI = {
   color: 'red',
-  snippets: ({ proxy }) => {
+  snippets: ({ name, url, proxy, isLocal }) => {
+    if (isLocal) {
+      const src = `${url}/api/v1/local/${name}`;
+      return [
+        {
+          title: 'Push and yank',
+          language: 'bash',
+          code: `GEM_HOST_API_KEY=unused gem push --host ${src} <gem>-<version>.gem
+GEM_HOST_API_KEY=unused gem yank <gem> -v <version> --host ${src}`,
+          note: 'gem push needs an API key; any value works. Pushing an existing version is rejected.',
+        },
+        {
+          title: 'Install',
+          language: 'bash',
+          code: `gem install <gem> --source ${src}/
+# Gemfile
+source "${src}/"`,
+        },
+      ];
+    }
     return [
       {
         title: 'Use this remote as the RubyGems source',