Fail GitHub scans on asset errors and drop sync state with its remote (#135)

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>

PLAN.md

@@ -672,7 +672,7 @@ func TestMain(m *testing.M) {
 
 ```hcl
 provider "artifactapi" {
-  endpoint = "https://artifactapi.k8s.syd1.au.unkin.net"
+  endpoint = "https://artifactapi.example.com"
 }
 
 resource "artifactapi_remote" "terraform_registry" {

README.md

@@ -1,6 +1,6 @@
 # ArtifactAPI
 
-Caching proxy for package repositories. Single Go binary, 11 package types, content-addressable storage, managed by Terraform.
+Caching proxy for package repositories. Single Go binary, 12 package types, content-addressable storage, managed by Terraform.
 
 ## Quick Start
 
@@ -20,97 +20,26 @@ API: `http://localhost:8000` | Frontend: `http://localhost:5173`
 
 ## Package Types
 
-| Type | Mutable (auto-detected) | Immutable (auto-detected) |
-|---|---|---|
-| `generic` | nothing | everything |
-| `docker` | tag manifests, `/tags/list` | blobs, digest manifests |
-| `helm` | `index.yaml` | `.tgz` charts |
-| `pypi` | `simple/*` index pages | `.whl`, `.tar.gz` |
-| `npm` | package metadata | `.tgz` tarballs |
-| `rpm` | `repomd.xml`, `repodata/*` | `.rpm` |
-| `alpine` | `APKINDEX.tar.gz` | `.apk` |
-| `puppet` | `v3/modules/*`, `v3/releases*` | `.tar.gz` |
-| `terraform` | `*/versions` | `*/download/*/*` |
-| `goproxy` | `@v/list`, `@latest` | `.info`, `.mod`, `.zip` |
-| `cargo` | sparse index files (`config.json` synthesized) | `crates/*/*.crate` |
-| `github_rpm` | `repodata/*` (synthesized) | `.rpm` (redirected) |
-
 Providers classify paths automatically. Users only configure what to proxy and TTLs.
 
-### `github_rpm` — GitHub releases as a yum repo (metadata-only, no precache)
+Classification precedence, TTLs and eviction for every remote: [docs/common/caching.md](docs/common/caching.md).
 
-A `github_rpm` remote turns a GitHub repo's **releases** into a real `dnf`/`yum`
-repository without ever caching the packages. It scans releases for `.rpm`
-assets, derives each package's metadata (NEVRA, requires/provides/conflicts/
-obsoletes, files, checksum) and **synthesizes `repodata/` on the fly**. Package
-metadata comes from a **ranged GET of just the RPM header** (the header sits at
-the front of the file, so the whole package is never downloaded); the sha256
-checksum comes from the GitHub asset `digest` when present, else a one-time
-lazy stream. Derived metadata is cached (keyed by asset) so repodata generation
-is served from primed DB rows, never a cold on-demand derive.
+Each type's paths, Terraform examples and local/virtual behaviour are in `docs/<type>/`:
 
-Each package's `<location>` points back at the remote, which **302-redirects**
-the download to the `releases_remote` — an existing generic `github.com` remote
-that streams the actual bytes. `dnf` follows the redirect transparently.
-
-#### Background syncer
-
-A single process-wide **background syncer** keeps every `github_rpm` remote's
-derived metadata current off the client request path:
-
-- **Prime on create.** Creating a `github_rpm` remote enqueues a background prime
-  scan, so its metadata is derived right away without blocking the create call.
-  The first `dnf` request is served from cache. If a request arrives before the
-  prime lands, it returns a retryable `503` (with `Retry-After`) rather than
-  serving an empty repo or blocking on a multi-minute derive.
-- **Periodic re-check, driven by `mutable_ttl`.** Each remote is re-checked for
-  new or changed releases no more often than its `mutable_ttl`. New/changed
-  assets are derived incrementally; assets already cached are never re-fetched,
-  and assets that disappear upstream are pruned.
-- **ETag / 304 conditional requests.** The releases-list `ETag` is stored per
-  remote and sent as `If-None-Match`; a `304 Not Modified` means nothing changed
-  and the syncer derives nothing. GitHub does not count `304` conditional
-  responses against the rate limit, so an unchanged repo is nearly free — this is
-  the main lever keeping GitHub traffic low.
-- **Global rate limit.** Every GitHub call (releases list + each ranged asset
-  header GET) passes through a single token-bucket limiter **shared across all
-  remotes**, so GitHub is never hammered. Configure a token (`password`) on the
-  remote for the higher authenticated rate limit (~5000/hr vs ~60/hr
-  unauthenticated).
-- **Multi-replica coordination.** State is shared through the database. Before a
-  periodic scan a replica must atomically claim a per-remote lease
-  (`github_rpm_sync_state`: `last_synced_at`, `etag`, `sync_lease_owner`,
-  `sync_lease_expires`); only the winner scans. This bounds total GitHub load to
-  ~once per `mutable_ttl` regardless of replica count, and the shared `etag`
-  lets any replica issue the conditional request.
-
-```hcl
-# Backend that serves the actual .rpm bytes from github.com.
-resource "artifactapi_remote_generic" "github" {
-  name     = "github"
-  base_url = "https://github.com"
-  patterns = [
-    "acme/tools/releases/download/.*\\.rpm$", # allowlist the repo's release assets
-  ]
-}
-
-resource "artifactapi_remote_github_rpm" "acme-tools" {
-  name            = "acme-tools"
-  base_url        = "https://api.github.com/repos/acme/tools" # the releases API root
-  releases_remote = "github"                                  # backend for downloads
-  mutable_ttl     = 3600                                      # release re-scan interval
-
-  # Optional: restrict which release assets become packages (regex on filename).
-  patterns = [".*\\.x86_64\\.rpm$", ".*\\.noarch\\.rpm$"]
-
-  # Optional: a token for private repos / higher API rate limits.
-  # password = "ghp_..."
-}
-```
-
-`dnf` config: `baseurl=https://artifactapi.example/api/v1/remote/acme-tools`.
-The repo is multi-arch (no `$basearch` needed) — `dnf` selects matching packages
-from the synthesized metadata.
+- `alpine`: [remote](docs/alpine/remote.md), [remote-github](docs/alpine/remote-github.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), [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)
+- `nuget`: [remote](docs/nuget/remote.md)
+- `puppet`: [remote](docs/puppet/remote.md), [local](docs/puppet/local.md)
+- `pypi`: [remote](docs/pypi/remote.md)
+- `rpm`: [remote](docs/rpm/remote.md), [remote-github](docs/rpm/remote-github.md)
+- `terraform`: [remote](docs/terraform/remote.md), [local](docs/terraform/local.md)
 
 ### GitHub authentication
 
@@ -179,105 +108,9 @@ GITHUB_APP_PRIVATE_KEY_PATH=/etc/artifactapi/github-app.pem
 
 ## Terraform
 
-Remotes and virtuals are managed by Terraform. Each package type has its own resource:
+Remotes and virtuals are managed by Terraform. Each package type has its own resource; see `docs/<type>/` for examples.
 
-```hcl
-resource "artifactapi_remote_generic" "github" {
-  name     = "github"
-  base_url = "https://github.com"
-
-  immutable_ttl = 0
-  mutable_ttl   = 7200
-
-  patterns = [
-    "ducaale/xh/.*/xh-.*-x86_64-unknown-linux-musl.tar.gz$",
-    "mikefarah/yq/.*/yq_linux_amd64$",
-  ]
-
-  mutable_patterns = [
-    ".*/archive/refs/heads/.*\\.tar\\.gz$",
-  ]
-}
-
-resource "artifactapi_remote_docker" "dockerhub" {
-  name     = "dockerhub"
-  base_url = "https://registry-1.docker.io"
-
-  immutable_ttl    = 0
-  mutable_ttl      = 300
-  ban_tags_enabled = true
-  ban_tags         = ["latest"]
-
-  patterns = [
-    "^library/postgres",
-    "^library/redis",
-  ]
-}
-
-resource "artifactapi_remote_helm" "jetstack" {
-  name     = "jetstack"
-  base_url = "https://charts.jetstack.io"
-
-  immutable_ttl = 0
-  mutable_ttl   = 3600
-}
-
-resource "artifactapi_virtual" "helm" {
-  name         = "helm"
-  package_type = "helm"
-  members      = [artifactapi_remote_helm.jetstack.name]
-}
-```
-
-Provider: [terraform-provider-artifactapi](../terraform-provider-artifactapi)
-
-### Serving providers as a registry
-
-A local `terraform` repo is a real provider registry: upload
-`terraform-provider-{type}_{version}_{os}_{arch}.zip` files under
-`{namespace}/{type}/`, and Terraform installs them from a bare source address —
-no `.terraformrc` mirror config:
-
-```hcl
-terraform {
-  required_providers {
-    artifactapi = {
-      source  = "artifactapi.k8s.syd1.au.unkin.net/<repo>/<type>"
-      version = "0.1.2"
-    }
-  }
-}
-```
-
-The Terraform *namespace* segment is the artifactapi repo name; the provider is
-matched by *type*. The registry serves service discovery
-(`/.well-known/terraform.json`), the `providers.v1` version/download endpoints,
-and a GPG-signed `SHA256SUMS` per the provider registry protocol.
-
-Signing needs a GPG key. By default artifactapi generates one on first start and
-stores it in the database (`signing_keys` table), so every replica shares it and
-there's nothing to provision. To bring your own key instead, point
-`TF_SIGNING_KEY_PATH` at an armored private key (optionally
-`TF_SIGNING_KEY_PASSPHRASE`), which takes precedence over the generated one.
-`TF_PROVIDER_PROTOCOLS` (default `5.0,6.0`) sets the advertised plugin protocols.
-
-### Local docker registry
-
-A local `docker` repo is a real container registry, not a mirror: it serves the
-Docker Registry HTTP API V2 for both push and pull, so any client (`docker`,
-`podman`, `skopeo`, `buildah`) can use it directly.
-
-```sh
-docker tag myapp:latest artifactapi.k8s.syd1.au.unkin.net/docker-internal/myapp:latest
-docker push        artifactapi.k8s.syd1.au.unkin.net/docker-internal/myapp:latest
-docker pull        artifactapi.k8s.syd1.au.unkin.net/docker-internal/myapp:latest
-```
-
-The first path segment after `/v2/` is the artifactapi repo name; the remainder
-is the image name. Blobs and manifests are stored through the shared
-content-addressable store (deduplicated by digest, reaped by GC once
-unreferenced); tags are mutable references and re-pushing a tag moves it. Blob
-uploads support both the monolithic and chunked (`POST`/`PATCH`/`PUT`) flows.
+Provider: [terraform-provider-artifactapi](https://git.unkin.net/unkin/terraform-provider-artifactapi)
 
 ## Access Control
 
@@ -297,6 +130,8 @@ 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/alpine/remote-github.md

@@ -0,0 +1,7 @@
+# `github_alpine` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `github_alpine` | `APKINDEX.tar.gz` (synthesized) | `.apk` (redirected) |

docs/alpine/remote.md

@@ -0,0 +1,7 @@
+# `alpine` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `alpine` | `APKINDEX.tar.gz` | `.apk` |

docs/cargo/remote.md

@@ -0,0 +1,7 @@
+# `cargo` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `cargo` | sparse index files (`config.json` synthesized) | `crates/*/*.crate` |

docs/common/caching.md

@@ -0,0 +1,101 @@
+# Caching and classification (all remotes)
+
+Every proxied request on a remote is classified as **denied**, **immutable** or
+**mutable**. The class picks the storage path and the freshness TTL.
+
+## Fields
+
+| Field | Meaning |
+|---|---|
+| `patterns` | Allowlist of regexes. Empty allows every path; otherwise a non-matching path is denied (403). |
+| `blocklist` | Regexes; a match is denied (403). |
+| `immutable_patterns` | Regexes forcing a path immutable. |
+| `mutable_patterns` | Regexes forcing a path mutable. |
+| `immutable_ttl` | Seconds an immutable path stays fresh. `0` = forever. |
+| `mutable_ttl` | Seconds a mutable path stays fresh. `0` also means never expires. Omitted on create, it defaults to `3600`; omitted on update, the stored value is kept. |
+| `check_mutable` | When a mutable path's `mutable_ttl` expires, sends a conditional `HEAD` (`If-None-Match`) with the stored upstream ETag. A `304` re-arms the TTL and serves the stored copy; anything else refetches in full. The ETag is kept for `max(10 × mutable_ttl, 7 days)`, re-armed on each `304`, so idle paths age out. It is only stored when `check_mutable` is set and `mutable_ttl` is non-zero, and never for immutable paths. |
+| `stale_on_error` | On an upstream network error, serve the stored copy instead of failing. |
+| `quarantine_enabled` / `quarantine_days` | Stored on the remote but not enforced by the proxy yet. |
+| `mirrorlist` / `mirror_strategy` | rpm/deb/alpine only. Upstream pool is `[base_url] + mirrorlist`; `round_robin` (default) rotates the starting mirror, `least_conn` starts at the one with the fewest in-flight requests. Network errors and 5xx fail over to the next mirror; other statuses return as-is. |
+
+## Precedence
+
+The first rule that matches wins:
+
+1. `blocklist` matches: **denied**
+2. `patterns` is non-empty and nothing matches: **denied**
+3. `immutable_patterns` matches: **immutable**
+4. `mutable_patterns` matches: **mutable**
+5. the provider's built-in `Classify` says mutable: **mutable**
+6. anything else: **immutable**
+
+So `blocklist` beats the allowlist, and `immutable_patterns` beats
+`mutable_patterns`. Either user list overrides the built-in rules. `GET` and
+`HEAD` both apply this order.
+
+## Matching rules
+
+- Regexes are Go `regexp`, matched **unanchored** (`MatchString`). Add `^` or `$` yourself when you need them.
+- They match the path after `/api/v1/remote/<name>/`, without a leading slash, e.g. `9/BaseOS/x86_64/os/repodata/repomd.xml`.
+- The query string is not part of the path. It is dropped and not forwarded upstream.
+- `create` and `update` reject an invalid regex in `patterns`, `blocklist`, `mutable_patterns`, `immutable_patterns` or `ban_tags` with a 400. Only invalid regexes already stored before that check are skipped at match time.
+
+## Lifecycles
+
+| | Immutable | Mutable |
+|---|---|---|
+| Stored as | content-addressed blob (sha256), streamed | per-path index object, buffered and rewritten by the provider |
+| Fresh for | `immutable_ttl` (`0` = forever) | `mutable_ttl` |
+| After expiry | refetched from upstream | revalidated with `If-None-Match` when `check_mutable` is set and an ETag is stored, else refetched |
+| Upstream down | `stale_on_error` serves the stored copy and re-arms the TTL; an open circuit breaker always serves stale if a copy exists, else 503 | same |
+
+Concurrent misses on one path share a fetch lock. Waiters poll the store for
+up to 5s instead of all going upstream.
+
+## Eviction
+
+```sh
+curl -X DELETE https://artifactapi.example.com/api/v2/remotes/<name>/objects/<path>
+curl -X DELETE https://artifactapi.example.com/api/v2/remotes/<name>/objects/<dir>/*
+```
+
+- Evict drops the artifact row, the index object and the Redis TTL and ETag keys, so the next request goes upstream whatever the class or TTL.
+- Deleting a remote drops its Redis TTL and ETag keys, so a re-created remote of the same name starts cold.
+- A single-path evict takes the fetch lock first, so an in-flight fetch can't re-cache the path. It returns 503 if the lock stays busy.
+- A wildcard must end in `<dir>/*` and takes no lock.
+- Returns 204, or 404 for an unknown remote.
+
+## Examples
+
+Bodies for `POST https://artifactapi.example.com/api/v2/remotes`.
+
+GitHub release assets through a `generic` remote, allowlisted:
+
+```json
+{"name": "github", "package_type": "generic", "base_url": "https://github.com",
+ "immutable_ttl": 0, "mutable_ttl": 7200,
+ "patterns": ["^mikefarah/yq/releases/download/.*/yq_linux_amd64$"]}
+```
+
+rpm remote: `repodata/*` and `repomd.xml` are mutable by default, so only the TTLs are needed:
+
+```json
+{"name": "almalinux", "package_type": "rpm", "base_url": "https://repo.almalinux.org/almalinux",
+ "immutable_ttl": 0, "mutable_ttl": 3600, "check_mutable": true, "stale_on_error": true}
+```
+
+Force a moving path mutable, e.g. branch tarballs on `generic`:
+
+```json
+{"mutable_patterns": ["/archive/refs/heads/.*\\.tar\\.gz$"], "mutable_ttl": 600}
+```
+
+## 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),
+[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),
+[puppet](../puppet/remote.md), [pypi](../pypi/remote.md), [rpm](../rpm/remote.md),
+[rpm github](../rpm/remote-github.md), [terraform](../terraform/remote.md).

docs/deb/remote-github.md

@@ -0,0 +1,7 @@
+# `github_deb` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `github_deb` | `Packages*`, `Release*` (synthesized) | `.deb` (redirected) |

docs/deb/remote.md

@@ -0,0 +1,7 @@
+# `deb` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `deb` | `Packages*`, `Sources*`, `Release`, `InRelease`, `Release.gpg`, `Contents-*` | `.deb` |

docs/docker/local.md

@@ -0,0 +1,17 @@
+# Local docker registry
+
+A local `docker` repo is a real container registry, not a mirror: it serves the
+Docker Registry HTTP API V2 for both push and pull, so any client (`docker`,
+`podman`, `skopeo`, `buildah`) can use it directly.
+
+```sh
+docker tag myapp:latest artifactapi.example.com/docker-internal/myapp:latest
+docker push        artifactapi.example.com/docker-internal/myapp:latest
+docker pull        artifactapi.example.com/docker-internal/myapp:latest
+```
+
+The first path segment after `/v2/` is the artifactapi repo name; the remainder
+is the image name. Blobs and manifests are stored through the shared
+content-addressable store (deduplicated by digest, reaped by GC once
+unreferenced); tags are mutable references and re-pushing a tag moves it. Blob
+uploads support both the monolithic and chunked (`POST`/`PATCH`/`PUT`) flows.

docs/docker/remote.md

@@ -0,0 +1,26 @@
+# `docker` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `docker` | tag manifests, `/tags/list` | blobs, digest manifests |
+
+## Terraform
+
+```hcl
+resource "artifactapi_remote_docker" "dockerhub" {
+  name     = "dockerhub"
+  base_url = "https://registry-1.docker.io"
+
+  immutable_ttl    = 0
+  mutable_ttl      = 300
+  ban_tags_enabled = true
+  ban_tags         = ["latest"]
+
+  patterns = [
+    "^library/postgres",
+    "^library/redis",
+  ]
+}
+```

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/remote.md

@@ -0,0 +1,7 @@
+# `gems` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `gems` | compact index (`versions`, `info/*`, `names`), `*specs.4.8.gz` | `gems/*.gem`, `quick/Marshal.4.8/*.gemspec.rz` |

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.

docs/generic/remote.md

@@ -0,0 +1,28 @@
+# `generic` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `generic` | nothing | everything |
+
+## Terraform
+
+```hcl
+resource "artifactapi_remote_generic" "github" {
+  name     = "github"
+  base_url = "https://github.com"
+
+  immutable_ttl = 0
+  mutable_ttl   = 7200
+
+  patterns = [
+    "ducaale/xh/.*/xh-.*-x86_64-unknown-linux-musl.tar.gz$",
+    "mikefarah/yq/.*/yq_linux_amd64$",
+  ]
+
+  mutable_patterns = [
+    ".*/archive/refs/heads/.*\\.tar\\.gz$",
+  ]
+}
+```

docs/goproxy/remote.md

@@ -0,0 +1,7 @@
+# `goproxy` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `goproxy` | `@v/list`, `@latest` | `.info`, `.mod`, `.zip` |

docs/helm/local.md

@@ -0,0 +1,15 @@
+# Local helm repository
+
+A local `helm` repo is a real chart repository: `PUT` a packaged chart to
+`/api/v2/remotes/<repo>/files/<chart>-<version>.tgz` and `index.yaml` is
+generated from each chart's `Chart.yaml` (with sha256 digests) at
+`/api/v1/local/<repo>/index.yaml`; a file not named after its `Chart.yaml`
+name and version is stored but left out of the index. Add the local as a
+member of a helm virtual to serve it alongside remotes.
+
+```bash
+helm package ./mychart
+curl -fsSL --upload-file mychart-0.1.0.tgz \
+  https://artifactapi.example.com/api/v2/remotes/<repo>/files/mychart-0.1.0.tgz
+helm repo add <repo> https://artifactapi.example.com/api/v1/local/<repo>
+```

docs/helm/remote.md

@@ -0,0 +1,19 @@
+# `helm` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `helm` | `index.yaml` | `.tgz` charts |
+
+## Terraform
+
+```hcl
+resource "artifactapi_remote_helm" "jetstack" {
+  name     = "jetstack"
+  base_url = "https://charts.jetstack.io"
+
+  immutable_ttl = 0
+  mutable_ttl   = 3600
+}
+```

docs/helm/virtual.md

@@ -0,0 +1,9 @@
+# `helm` virtual
+
+```hcl
+resource "artifactapi_virtual" "helm" {
+  name         = "helm"
+  package_type = "helm"
+  members      = [artifactapi_remote_helm.jetstack.name]
+}
+```

docs/npm/local.md

@@ -0,0 +1,14 @@
+# Local npm registry
+
+A local `npm` repo is a real npm registry: `npm publish` (scoped and unscoped)
+and `npm install` work against `/api/v1/local/<repo>/`. npm requires an
+`_authToken` for the registry before it will publish; any value works.
+
+```ini
+# .npmrc
+registry=https://artifactapi.example.com/api/v1/local/<repo>/
+//artifactapi.example.com/api/v1/local/<repo>/:_authToken=unused
+```
+
+Versions are immutable: republishing an existing version is rejected. The
+dist-tags sent with a publish (`latest`, or `--tag`) move to that version.

docs/npm/remote.md

@@ -0,0 +1,7 @@
+# `npm` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `npm` | package metadata | `.tgz` tarballs |

docs/npm/virtual.md

@@ -0,0 +1,30 @@
+# `npm` virtual
+
+An npm virtual serves one registry over local and remote npm members:
+`npm install` and `npm view` work against `/api/v1/virtual/<name>/`.
+
+- Versions are the union across members; on a duplicate version the earlier
+  member wins.
+- Each dist-tag comes from the first member defining it, and is dropped if it
+  names a version missing from the merged set.
+- Tarball URLs point at the virtual (`<member>/<path>`), which 302s to the
+  owning member.
+- Full and abbreviated (`application/vnd.npm.install-v1+json`) packuments are
+  both served.
+- A member error fails the request with 502; a member without the package is
+  skipped. Merges are cached for 60s per package.
+
+```hcl
+resource "artifactapi_virtual" "npm" {
+  name         = "npm"
+  package_type = "npm"
+  members      = [artifactapi_local_npm.internal.name, artifactapi_remote_npm.npmjs.name]
+}
+```
+
+```ini
+# .npmrc
+registry=https://artifactapi.example.com/api/v1/virtual/npm/
+```
+
+Publish to the local member directly; the virtual is read-only.

docs/nuget/remote.md

@@ -0,0 +1,7 @@
+# `nuget` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `nuget` | `index.json` (service index), registration and flat container indexes | `.nupkg`, `.snupkg`, `.nuspec`, `readme`, `icon` |

docs/puppet/local.md

@@ -0,0 +1,14 @@
+# Local puppet forge
+
+A local `puppet` repo is a Forge: `PUT` a module tarball to
+`/api/v2/remotes/<repo>/files/<owner>-<module>-<version>.tar.gz` and the Forge
+v3 API (`/v3/modules`, `/v3/releases`, `/v3/files`) is served from each
+release's `metadata.json` at `/api/v1/local/<repo>`. Versions are immutable.
+
+```bash
+puppet module build ./hello
+curl -fsSL --upload-file pkg/unkin-hello-0.1.0.tar.gz \
+  https://artifactapi.example.com/api/v2/remotes/<repo>/files/unkin-hello-0.1.0.tar.gz
+puppet module install unkin-hello \
+  --module_repository https://artifactapi.example.com/api/v1/local/<repo>
+```

docs/puppet/remote.md

@@ -0,0 +1,7 @@
+# `puppet` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `puppet` | `v3/modules/*`, `v3/releases*` | `.tar.gz` |

docs/pypi/remote.md

@@ -0,0 +1,7 @@
+# `pypi` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `pypi` | `simple/*` index pages | `.whl`, `.tar.gz` |

docs/rpm/remote-github.md

@@ -0,0 +1,82 @@
+# `github_rpm` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `github_rpm` | `repodata/*` (synthesized) | `.rpm` (redirected) |
+
+## GitHub releases as a yum repo (metadata-only, no precache)
+
+A `github_rpm` remote turns a GitHub repo's **releases** into a real `dnf`/`yum`
+repository without ever caching the packages. It scans releases for `.rpm`
+assets, derives each package's metadata (NEVRA, requires/provides/conflicts/
+obsoletes, files, checksum) and **synthesizes `repodata/` on the fly**. Package
+metadata comes from a **ranged GET of just the RPM header** (the header sits at
+the front of the file, so the whole package is never downloaded); the sha256
+checksum comes from the GitHub asset `digest` when present, else a one-time
+lazy stream. Derived metadata is cached (keyed by asset) so repodata generation
+is served from primed DB rows, never a cold on-demand derive.
+
+Each package's `<location>` points back at the remote, which **302-redirects**
+the download to the `releases_remote` — an existing generic `github.com` remote
+that streams the actual bytes. `dnf` follows the redirect transparently.
+
+### Background syncer
+
+A single process-wide **background syncer** keeps every `github_rpm` remote's
+derived metadata current off the client request path:
+
+- **Prime on create.** Creating a `github_rpm` remote enqueues a background prime
+  scan, so its metadata is derived right away without blocking the create call.
+  The first `dnf` request is served from cache. If a request arrives before the
+  prime lands, it returns a retryable `503` (with `Retry-After`) rather than
+  serving an empty repo or blocking on a multi-minute derive.
+- **Periodic re-check, driven by `mutable_ttl`.** Each remote is re-checked for
+  new or changed releases no more often than its `mutable_ttl`. New/changed
+  assets are derived incrementally; assets already cached are never re-fetched,
+  and assets that disappear upstream are pruned.
+- **ETag / 304 conditional requests.** The releases-list `ETag` is stored per
+  remote and sent as `If-None-Match`; a `304 Not Modified` means nothing changed
+  and the syncer derives nothing. GitHub does not count `304` conditional
+  responses against the rate limit, so an unchanged repo is nearly free — this is
+  the main lever keeping GitHub traffic low.
+- **Global rate limit.** Every GitHub call (releases list + each ranged asset
+  header GET) passes through a single token-bucket limiter **shared across all
+  remotes**, so GitHub is never hammered. Configure a token (`password`) on the
+  remote for the higher authenticated rate limit (~5000/hr vs ~60/hr
+  unauthenticated).
+- **Multi-replica coordination.** State is shared through the database. Before a
+  periodic scan a replica must atomically claim a per-remote lease
+  (`github_rpm_sync_state`: `last_synced_at`, `etag`, `sync_lease_owner`,
+  `sync_lease_expires`); only the winner scans. This bounds total GitHub load to
+  ~once per `mutable_ttl` regardless of replica count, and the shared `etag`
+  lets any replica issue the conditional request.
+
+```hcl
+# Backend that serves the actual .rpm bytes from github.com.
+resource "artifactapi_remote_generic" "github" {
+  name     = "github"
+  base_url = "https://github.com"
+  patterns = [
+    "acme/tools/releases/download/.*\\.rpm$", # allowlist the repo's release assets
+  ]
+}
+
+resource "artifactapi_remote_github_rpm" "acme-tools" {
+  name            = "acme-tools"
+  base_url        = "https://api.github.com/repos/acme/tools" # the releases API root
+  releases_remote = "github"                                  # backend for downloads
+  mutable_ttl     = 3600                                      # release re-scan interval
+
+  # Optional: restrict which release assets become packages (regex on filename).
+  patterns = [".*\\.x86_64\\.rpm$", ".*\\.noarch\\.rpm$"]
+
+  # Optional: a token for private repos / higher API rate limits.
+  # password = "ghp_..."
+}
+```
+
+`dnf` config: `baseurl=https://artifactapi.example/api/v1/remote/acme-tools`.
+The repo is multi-arch (no `$basearch` needed) — `dnf` selects matching packages
+from the synthesized metadata.

docs/rpm/remote.md

@@ -0,0 +1,7 @@
+# `rpm` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `rpm` | `repomd.xml`, `repodata/*` | `.rpm` |

docs/terraform/local.md

@@ -0,0 +1,29 @@
+# Serving providers as a registry
+
+A local `terraform` repo is a real provider registry: upload
+`terraform-provider-{type}_{version}_{os}_{arch}.zip` files under
+`{namespace}/{type}/`, and Terraform installs them from a bare source address —
+no `.terraformrc` mirror config:
+
+```hcl
+terraform {
+  required_providers {
+    artifactapi = {
+      source  = "artifactapi.example.com/<repo>/<type>"
+      version = "0.1.2"
+    }
+  }
+}
+```
+
+The Terraform *namespace* segment is the artifactapi repo name; the provider is
+matched by *type*. The registry serves service discovery
+(`/.well-known/terraform.json`), the `providers.v1` version/download endpoints,
+and a GPG-signed `SHA256SUMS` per the provider registry protocol.
+
+Signing needs a GPG key. By default artifactapi generates one on first start and
+stores it in the database (`signing_keys` table), so every replica shares it and
+there's nothing to provision. To bring your own key instead, point
+`TF_SIGNING_KEY_PATH` at an armored private key (optionally
+`TF_SIGNING_KEY_PASSPHRASE`), which takes precedence over the generated one.
+`TF_PROVIDER_PROTOCOLS` (default `5.0,6.0`) sets the advertised plugin protocols.

docs/terraform/remote.md

@@ -0,0 +1,7 @@
+# `terraform` remote
+
+Shared classification, TTL and eviction rules: [caching](../common/caching.md).
+
+| Type | Mutable (auto-detected) | Immutable (auto-detected) |
+|---|---|---|
+| `terraform` | `*/versions` | `*/download/*/*` |

e2e-docker/README.md

@@ -22,14 +22,21 @@ already-running stack.
 ## Coverage
 
 - **Repository lifecycle** — add / change / delete for remote, local and virtual repos.
-- **Caching** — one immutable artifact per remote package type (generic, docker,
-  helm, pypi, npm, rpm, alpine, puppet, terraform, goproxy, cargo) proxied through the
-  mock upstream: first fetch `X-Artifact-Source: remote`, second `cache`, bytes
+- **Caching** — one immutable artifact per remote package type (one
+  `caching_<type>_test.go` case each) proxied through the mock upstream: first fetch `X-Artifact-Source: remote`, second `cache`, bytes
   verified against the origin fixture.
-- **Local uploads** — generic (upload/download), pypi (wheel + generated `simple/`
-  index), rpm (real package + **automatic repodata** generation).
+- **Local uploads** — puppet (Forge v3 API via real `r10k` and `puppet module install`),
+  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), gems (stock `ruby:3.3`: `gem push`,
+  `gem install`, `bundle install` + `require`, republish rejected, `gem yank`,
+  yanked re-push rejected).
 - **Virtual repositories** — pypi simple-index merge and helm `index.yaml` merge
-  across two members.
+  across two members; npm packument merge over two locals via a stock `node:22`
+  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).
 - **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/caching_alpine_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"alpine", "alpine/x86_64/testpkg-1.0-r0.apk", "alpine/x86_64/testpkg-1.0-r0.apk"})
+}

e2e-docker/caching_cargo_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"cargo", "crates/mycrate/mycrate-1.0.0.crate", "crates/mycrate/mycrate-1.0.0.crate"})
+}

e2e-docker/caching_docker_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"docker", "library/testimg/blobs/blobdata", "v2/library/testimg/blobs/blobdata"})
+}

e2e-docker/caching_gems_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"gems", "gems/mygem-1.0.0.gem", "gems/mygem-1.0.0.gem"})
+}

e2e-docker/caching_generic_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"generic", "blobs/hello.bin", "blobs/hello.bin"})
+}

e2e-docker/caching_goproxy_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"goproxy", "goproxy/example.com/mod/@v/v1.0.0.zip", "goproxy/example.com/mod/@v/v1.0.0.zip"})
+}

e2e-docker/caching_helm_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"helm", "charts/mychart-1.0.0.tgz", "charts/mychart-1.0.0.tgz"})
+}

e2e-docker/caching_npm_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"npm", "mypkg/-/mypkg-1.0.0.tgz", "mypkg/-/mypkg-1.0.0.tgz"})
+}

e2e-docker/caching_nuget_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"nuget", "nuget/e2epkg/1.0.0/e2epkg.1.0.0.nupkg", "nuget/e2epkg/1.0.0/e2epkg.1.0.0.nupkg"})
+}

e2e-docker/caching_puppet_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"puppet", "puppet-releases/author-mod-1.0.0.tar.gz", "puppet-releases/author-mod-1.0.0.tar.gz"})
+}

e2e-docker/caching_pypi_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"pypi", "packages/foo-1.0-py3-none-any.whl", "packages/foo-1.0-py3-none-any.whl"})
+}

e2e-docker/caching_rpm_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"rpm", "rpmrepo/Packages/e2e-testpkg-1.0-1.noarch.rpm", "rpmrepo/Packages/e2e-testpkg-1.0-1.noarch.rpm"})
+}

e2e-docker/caching_terraform_test.go

@@ -0,0 +1,7 @@
+//go:build dockere2e
+
+package e2edocker
+
+func init() {
+	cachingCases = append(cachingCases, cachingCase{"terraform", "hashicorp/aws/download/pkg.zip", "v1/providers/hashicorp/aws/download/pkg.zip"})
+}

e2e-docker/caching_test.go

@@ -9,32 +9,23 @@ import (
 	"testing"
 )
 
+type cachingCase struct {
+	pkgType string
+	// path is the request path under /api/v1/remote/<name>/. The provider
+	// derives the upstream URL from it (docker prepends /v2/, terraform
+	// prepends /v1/providers/), and the fixture lives at that resolved path.
+	path    string
+	fixture string
+}
+
+// cachingCases is filled by one caching_<type>_test.go file per package type.
+var cachingCases []cachingCase
+
 // TestCachingPerProvider proxies one immutable artifact for every remote
 // package type through the mock upstream and asserts: first fetch is served
 // from the remote, the second from cache, and the bytes match the origin.
 func TestCachingPerProvider(t *testing.T) {
-	cases := []struct {
-		pkgType string
-		// path is the request path under /api/v1/remote/<name>/. The provider
-		// derives the upstream URL from it (docker prepends /v2/, terraform
-		// prepends /v1/providers/), and the fixture lives at that resolved path.
-		path    string
-		fixture string
-	}{
-		{"generic", "blobs/hello.bin", "blobs/hello.bin"},
-		{"npm", "mypkg/-/mypkg-1.0.0.tgz", "mypkg/-/mypkg-1.0.0.tgz"},
-		{"helm", "charts/mychart-1.0.0.tgz", "charts/mychart-1.0.0.tgz"},
-		{"pypi", "packages/foo-1.0-py3-none-any.whl", "packages/foo-1.0-py3-none-any.whl"},
-		{"rpm", "rpmrepo/Packages/e2e-testpkg-1.0-1.noarch.rpm", "rpmrepo/Packages/e2e-testpkg-1.0-1.noarch.rpm"},
-		{"alpine", "alpine/x86_64/testpkg-1.0-r0.apk", "alpine/x86_64/testpkg-1.0-r0.apk"},
-		{"puppet", "puppet-releases/author-mod-1.0.0.tar.gz", "puppet-releases/author-mod-1.0.0.tar.gz"},
-		{"goproxy", "goproxy/example.com/mod/@v/v1.0.0.zip", "goproxy/example.com/mod/@v/v1.0.0.zip"},
-		{"cargo", "crates/mycrate/mycrate-1.0.0.crate", "crates/mycrate/mycrate-1.0.0.crate"},
-		{"terraform", "hashicorp/aws/download/pkg.zip", "v1/providers/hashicorp/aws/download/pkg.zip"},
-		{"docker", "library/testimg/blobs/blobdata", "v2/library/testimg/blobs/blobdata"},
-	}
-
-	for _, tc := range cases {
+	for _, tc := range cachingCases {
 		t.Run(tc.pkgType, func(t *testing.T) {
 			name := "cache-" + tc.pkgType
 			createRepo(t, fmt.Sprintf(`{

e2e-docker/fixtures/gems/mygem-1.0.0.gem

@@ -0,0 +1 @@
+mygem-1.0.0 e2e fixture

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)
+		}
+	}
+}

e2e-docker/helm_local_test.go

@@ -0,0 +1,71 @@
+//go:build dockere2e
+
+package e2edocker
+
+import (
+	"net/http"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+// TestLocalHelmRealClient packages a chart with the real helm CLI, publishes it
+// to a helm local, then drives helm repo add/search/pull/template against the
+// local and against a helm virtual that has the local as a member.
+func TestLocalHelmRealClient(t *testing.T) {
+	network := os.Getenv("COMPOSE_NETWORK")
+	internal := strings.TrimRight(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")
+	}
+
+	createRepo(t, `{"name":"local-helm","package_type":"helm","repo_type":"local"}`)
+	defer deleteRepo(t, "local-helm")
+	createVirtual(t, `{"name":"vhelm","package_type":"helm","members":["local-helm"]}`)
+	defer deleteVirtual(t, "vhelm")
+
+	helm := func(script string) string {
+		t.Helper()
+		out, err := exec.Command("docker", "run", "--rm", "--network", network, "--entrypoint", "sh",
+			"alpine/helm:3.16.4", "-c", "set -eu; "+script).Output()
+		if err != nil {
+			stderr := ""
+			if ee, ok := err.(*exec.ExitError); ok {
+				stderr = string(ee.Stderr)
+			}
+			t.Fatalf("helm script failed: %v\n%s%s", err, out, stderr)
+		}
+		return string(out)
+	}
+
+	chart := helm("cd /tmp && helm create e2echart >/dev/null && helm package e2echart >/dev/null && cat e2echart-0.1.0.tgz")
+	uploadFile(t, "local-helm", "e2echart-0.1.0.tgz", []byte(chart), "application/gzip")
+
+	// Chart metadata is recorded asynchronously after upload; poll the index.
+	var body []byte
+	for deadline := time.Now().Add(15 * time.Second); time.Now().Before(deadline); time.Sleep(500 * time.Millisecond) {
+		var resp *http.Response
+		resp, body = doRequest(t, http.MethodGet, api("/api/v1/local/local-helm/index.yaml"), nil, "")
+		if resp.StatusCode == http.StatusOK && strings.Contains(string(body), "e2echart-0.1.0.tgz") {
+			break
+		}
+	}
+	if !strings.Contains(string(body), "e2echart-0.1.0.tgz") || !strings.Contains(string(body), "digest: ") {
+		t.Fatalf("index.yaml never listed the chart:\n%s", body)
+	}
+
+	for _, repoURL := range []string{internal + "/api/v1/local/local-helm", internal + "/api/v1/virtual/vhelm"} {
+		out := helm("helm repo add e2e " + repoURL + " >/dev/null && " +
+			"helm search repo e2e/e2echart && " +
+			"cd /tmp && helm pull e2e/e2echart --version 0.1.0 && " +
+			"helm template rel e2echart-0.1.0.tgz | grep -c 'kind: Deployment'")
+		if !strings.Contains(out, "e2e/e2echart") || !strings.Contains(out, "0.1.0") || !strings.HasSuffix(strings.TrimSpace(out), "1") {
+			t.Fatalf("helm via %s:\n%s", repoURL, out)
+		}
+	}
+}

e2e-docker/npm_local_test.go

@@ -0,0 +1,62 @@
+//go:build dockere2e
+
+package e2edocker
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+// TestLocalNPMPublishInstall drives a stock npm client against a local npm
+// repo: publish unscoped and scoped packages, install and require() them in a
+// fresh project, publish a second version, and reject a republish.
+func TestLocalNPMPublishInstall(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-npm-local-%d", time.Now().UnixNano())
+	createRepo(t, fmt.Sprintf(`{"name":%q,"package_type":"npm","repo_type":"local"}`, name))
+	defer deleteRepo(t, name)
+
+	reg := strings.TrimRight(internal, "/") + "/api/v1/local/" + name + "/"
+	script := `set -euo pipefail
+printf 'registry=%s\n%s:_authToken=unused\n' "$REG" "${REG#http:}" > ~/.npmrc
+mk() { d="/w/src/$1-$2"; mkdir -p "$d"; cd "$d"
+  printf '{"name":"%s","version":"%s","main":"index.js"}' "$1" "$2" > package.json
+  echo "module.exports = '$1@$2';" > index.js; }
+mk e2e-npm-plain 1.0.0 && npm publish
+mk @e2e/npm-scoped 1.0.0 && npm publish
+mk e2e-npm-plain 1.0.0
+if npm publish 2>/dev/null; then echo "republish accepted"; exit 1; fi
+mkdir -p /w/app && cd /w/app && npm init -y >/dev/null
+npm install --no-audit --cache /tmp/fresh-cache e2e-npm-plain @e2e/npm-scoped
+node -e "console.log('REQ', require('e2e-npm-plain'), require('@e2e/npm-scoped'))"
+mk e2e-npm-plain 1.1.0 && npm publish
+echo "VERSIONS $(npm view e2e-npm-plain versions --json | tr -d ' \n')"
+echo "LATEST $(npm view e2e-npm-plain dist-tags.latest)"`
+
+	out, err := exec.Command("docker", "run", "--rm", "--network", network,
+		"-e", "REG="+reg, "node:22", "bash", "-c", script).CombinedOutput()
+	if err != nil {
+		t.Fatalf("npm client run failed: %v\n%s", err, out)
+	}
+	for _, want := range []string{
+		"REQ e2e-npm-plain@1.0.0 @e2e/npm-scoped@1.0.0",
+		`VERSIONS ["1.0.0","1.1.0"]`,
+		"LATEST 1.1.0",
+	} {
+		if !strings.Contains(string(out), want) {
+			t.Fatalf("missing %q in npm output:\n%s", want, out)
+		}
+	}
+}

e2e-docker/npm_virtual_test.go

@@ -0,0 +1,68 @@
+//go:build dockere2e
+
+package e2edocker
+
+import (
+	"fmt"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+// TestVirtualNPMInstall publishes to two local npm repos and drives a stock
+// npm client through a virtual over both: merged versions and dist-tags, and
+// an install whose tarballs resolve via the virtual's member redirect.
+func TestVirtualNPMInstall(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-npm-a-%d", id), fmt.Sprintf("e2e-npm-b-%d", id), fmt.Sprintf("e2e-npm-v-%d", id)
+	for _, name := range []string{a, b} {
+		createRepo(t, fmt.Sprintf(`{"name":%q,"package_type":"npm","repo_type":"local"}`, name))
+		defer deleteRepo(t, name)
+	}
+	createVirtual(t, fmt.Sprintf(`{"name":%q,"package_type":"npm","members":[%q,%q]}`, virt, a, b))
+	defer deleteVirtual(t, virt)
+
+	base := strings.TrimRight(internal, "/")
+	script := `set -euo pipefail
+pub() { d="/w/src/$2-$3-$1"; mkdir -p "$d"; cd "$d"
+  printf '{"name":"%s","version":"%s","main":"index.js"}' "$2" "$3" > package.json
+  echo "module.exports = '$1:$2@$3';" > index.js
+  printf 'registry=%s\n%s:_authToken=unused\n' "$BASE/api/v1/local/$1/" "${BASE#http:}/api/v1/local/$1/" > .npmrc
+  npm publish; }
+pub "$A" @e2e/virt 1.0.0
+pub "$B" @e2e/virt 1.0.0
+pub "$B" @e2e/virt 1.1.0
+mkdir -p /w/app && cd /w/app && npm init -y >/dev/null
+echo "registry=$BASE/api/v1/virtual/$V/" > .npmrc
+echo "VERSIONS $(npm view @e2e/virt versions --json | tr -d ' \n')"
+npm install --no-audit --cache /tmp/fresh-cache @e2e/virt@1.0.0
+node -e "console.log('REQ', require('@e2e/virt'))"
+echo "RESOLVED $(node -p "require('./package-lock.json').packages['node_modules/@e2e/virt'].resolved")"`
+
+	out, err := exec.Command("docker", "run", "--rm", "--network", network,
+		"-e", "BASE="+base, "-e", "A="+a, "-e", "B="+b, "-e", "V="+virt,
+		"node:22", "bash", "-c", script).CombinedOutput()
+	if err != nil {
+		t.Fatalf("npm client run failed: %v\n%s", err, out)
+	}
+	for _, want := range []string{
+		`VERSIONS ["1.0.0","1.1.0"]`,
+		"REQ " + a + ":@e2e/virt@1.0.0",
+		"RESOLVED " + base + "/api/v1/virtual/" + virt + "/" + a + "/@e2e/virt/-/virt-1.0.0.tgz",
+	} {
+		if !strings.Contains(string(out), want) {
+			t.Fatalf("missing %q in npm output:\n%s", want, out)
+		}
+	}
+}

e2e-docker/puppet_local_test.go

@@ -0,0 +1,88 @@
+//go:build dockere2e
+
+package e2edocker
+
+import (
+	"archive/tar"
+	"bytes"
+	"compress/gzip"
+	"net/http"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+	"time"
+)
+
+const puppetHelloMetadata = `{"name":"unkin-hello","version":"0.1.0","author":"unkin","summary":"e2e","license":"Apache-2.0","source":"https://example.invalid","dependencies":[{"name":"puppetlabs/stdlib","version_requirement":">= 4.0.0 < 10.0.0"}]}`
+
+func puppetModuleTarball(t *testing.T) []byte {
+	t.Helper()
+	var buf bytes.Buffer
+	zw := gzip.NewWriter(&buf)
+	tw := tar.NewWriter(zw)
+	for name, body := range map[string]string{
+		"unkin-hello-0.1.0/metadata.json":     puppetHelloMetadata,
+		"unkin-hello-0.1.0/manifests/init.pp": "class hello {}\n",
+	} {
+		if err := tw.WriteHeader(&tar.Header{Name: name, Mode: 0o644, Size: int64(len(body)), ModTime: time.Now()}); err != nil {
+			t.Fatal(err)
+		}
+		_, _ = tw.Write([]byte(body))
+	}
+	_ = tw.Close()
+	_ = zw.Close()
+	return buf.Bytes()
+}
+
+// TestLocalPuppetRealClient publishes a module to a puppet local and installs
+// it with the real r10k and puppet module tool. The stdlib dependency is not on
+// a local-only forge, so puppet runs with --ignore-dependencies.
+func TestLocalPuppetRealClient(t *testing.T) {
+	network := os.Getenv("COMPOSE_NETWORK")
+	internal := strings.TrimRight(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")
+	}
+
+	createRepo(t, `{"name":"local-puppet","package_type":"puppet","repo_type":"local"}`)
+	defer deleteRepo(t, "local-puppet")
+
+	upload := api("/api/v2/remotes/local-puppet/files/unkin-hello-0.1.0.tar.gz")
+	defer doRequest(t, http.MethodDelete, api("/api/v2/remotes/local-puppet/files/v3/files/unkin-hello-0.1.0.tar.gz"), nil, "")
+	tarball := puppetModuleTarball(t)
+	if resp, body := doRequest(t, http.MethodPut, upload, tarball, "application/gzip"); resp.StatusCode != http.StatusCreated {
+		t.Fatalf("upload: %d %s", resp.StatusCode, body)
+	}
+	if resp, _ := doRequest(t, http.MethodPut, upload, tarball, "application/gzip"); resp.StatusCode != http.StatusConflict {
+		t.Fatalf("re-upload of an existing version: %d, want 409", resp.StatusCode)
+	}
+	if resp, body := getEventually(t, api("/api/v1/local/local-puppet/v3/releases/unkin-hello-0.1.0"), 15*time.Second); resp.StatusCode != http.StatusOK || !strings.Contains(string(body), `"file_md5"`) {
+		t.Fatalf("release never indexed: %d %s", resp.StatusCode, body)
+	}
+
+	forge := internal + "/api/v1/local/local-puppet"
+	run := func(image, script string) string {
+		t.Helper()
+		out, err := exec.Command("docker", "run", "--rm", "--network", network, "--entrypoint", "sh", image, "-c", "set -eu; "+script).CombinedOutput()
+		if err != nil {
+			t.Fatalf("%s failed: %v\n%s", image, err, out)
+		}
+		return string(out)
+	}
+
+	out := run("ghcr.io/voxpupuli/r10k:latest", "cd /tmp && printf 'forge:\\n  baseurl: "+forge+"\\n' > r10k.yaml && "+
+		"printf \"forge '"+forge+"'\\nmod 'unkin-hello', '0.1.0'\\n\" > Puppetfile && "+
+		"r10k puppetfile install -c r10k.yaml --verbose && cat modules/hello/metadata.json")
+	if !strings.Contains(out, `"unkin-hello"`) {
+		t.Fatalf("r10k did not install unkin-hello:\n%s", out)
+	}
+
+	out = run("ghcr.io/openvoxproject/openvoxagent:latest", "export PATH=/opt/puppetlabs/bin:$PATH; puppet module install unkin-hello --module_repository "+forge+" --ignore-dependencies --target-dir /tmp/mods && puppet module list --color=false --modulepath /tmp/mods")
+	if !strings.Contains(out, "unkin-hello (v0.1.0)") {
+		t.Fatalf("puppet module install did not install unkin-hello:\n%s", out)
+	}
+}

e2e/head_test.go

@@ -0,0 +1,182 @@
+//go:build e2e
+
+package e2e
+
+import (
+	"encoding/json"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"strconv"
+	"strings"
+	"testing"
+	"time"
+
+	"git.unkin.net/unkin/artifactapi/internal/testsupport"
+)
+
+// assertHeadMatchesGet checks HEAD returns GET's status, type and length with no body.
+func assertHeadMatchesGet(t *testing.T, url string) {
+	t.Helper()
+	get, err := http.Get(url)
+	if err != nil {
+		t.Fatalf("GET: %v", err)
+	}
+	body, _ := io.ReadAll(get.Body)
+	get.Body.Close()
+	if get.StatusCode != http.StatusOK {
+		t.Fatalf("GET %s: %d %s", url, get.StatusCode, body)
+	}
+
+	head, err := http.Head(url)
+	if err != nil {
+		t.Fatalf("HEAD: %v", err)
+	}
+	hb, _ := io.ReadAll(head.Body)
+	head.Body.Close()
+	if head.StatusCode != http.StatusOK {
+		t.Fatalf("HEAD %s: got %d, want 200", url, head.StatusCode)
+	}
+	if len(hb) != 0 {
+		t.Errorf("HEAD returned a %d-byte body", len(hb))
+	}
+	for _, h := range []string{"Content-Type", "Cache-Control", "Vary"} {
+		if head.Header.Get(h) != get.Header.Get(h) {
+			t.Errorf("HEAD %s %q, GET %q", h, head.Header.Get(h), get.Header.Get(h))
+		}
+	}
+	if head.ContentLength != int64(len(body)) {
+		t.Errorf("HEAD Content-Length %d, GET body %d bytes", head.ContentLength, len(body))
+	}
+}
+
+func TestProxyHeadNuGetRewritten(t *testing.T) {
+	var upstream *httptest.Server
+	upstream = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(map[string]any{"version": "3.0.0", "resources": []map[string]string{
+			{"@id": upstream.URL + "/v3-flatcontainer/", "@type": "PackageBaseAddress/3.0.0"},
+		}})
+	}))
+	defer upstream.Close()
+
+	createRemote(t, mustFormat(`{"name": "head-nuget", "package_type": "nuget", "base_url": %q}`, upstream.URL+"/v3/index.json"))
+	defer deleteRemote(t, "head-nuget")
+
+	url := apiURL("/api/v1/remote/head-nuget/index.json")
+	assertHeadMatchesGet(t, url)
+
+	req, _ := http.NewRequest(http.MethodHead, url, nil)
+	req.Host = "evil.example:"
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusBadRequest {
+		t.Errorf("HEAD with invalid Host: got %d, want 400", resp.StatusCode)
+	}
+}
+
+func TestProxyHeadGitHubRPMRepodata(t *testing.T) {
+	rpm := testsupport.MinimalRPM("demo", "1.2", "3", "x86_64")
+	var gh *httptest.Server
+	mux := http.NewServeMux()
+	mux.HandleFunc("/repos/acme/tools/releases", func(w http.ResponseWriter, r *http.Request) {
+		if p := r.URL.Query().Get("page"); p != "" && p != "1" {
+			w.Write([]byte("[]"))
+			return
+		}
+		json.NewEncoder(w).Encode([]map[string]any{{"tag_name": "v1.2-3", "assets": []map[string]any{{
+			"name":                 "demo-1.2-3.x86_64.rpm",
+			"size":                 len(rpm),
+			"browser_download_url": gh.URL + "/acme/tools/releases/download/v1.2-3/demo-1.2-3.x86_64.rpm",
+		}}}})
+	})
+	mux.HandleFunc("/acme/tools/releases/download/", func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Length", strconv.Itoa(len(rpm)))
+		w.Write(rpm)
+	})
+	gh = httptest.NewServer(mux)
+	defer gh.Close()
+
+	createRemote(t, mustFormat(`{"name": "head-ghrpm", "package_type": "github_rpm", "base_url": %q, "releases_remote": "github"}`, gh.URL+"/repos/acme/tools"))
+	defer deleteRemote(t, "head-ghrpm")
+
+	url := apiURL("/api/v1/remote/head-ghrpm/repodata/repomd.xml")
+	deadline := time.Now().Add(30 * time.Second)
+	for {
+		if _, status := getBody(t, url); status == http.StatusOK || time.Now().After(deadline) {
+			break
+		}
+		time.Sleep(500 * time.Millisecond)
+	}
+	assertHeadMatchesGet(t, url)
+}
+
+func TestProxyHeadNpmUncachedPackument(t *testing.T) {
+	const abbreviated = "application/vnd.npm.install-v1+json"
+	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Set("Content-Type", "application/json")
+		doc := map[string]any{"name": "left-pad", "versions": map[string]any{"1.3.0": map[string]any{}}}
+		if r.Header.Get("Accept") != abbreviated {
+			doc["readme"] = strings.Repeat("full packument ", 200)
+		}
+		json.NewEncoder(w).Encode(doc)
+	}))
+	defer upstream.Close()
+
+	createRemote(t, mustFormat(`{"name": "head-npm", "package_type": "npm", "base_url": %q}`, upstream.URL))
+	defer deleteRemote(t, "head-npm")
+
+	url := apiURL("/api/v1/remote/head-npm/left-pad")
+	do := func(method string) (*http.Response, []byte) {
+		req, _ := http.NewRequest(method, url, nil)
+		req.Header.Set("Accept", abbreviated)
+		resp, err := http.DefaultClient.Do(req)
+		if err != nil {
+			t.Fatalf("%s: %v", method, err)
+		}
+		defer resp.Body.Close()
+		b, _ := io.ReadAll(resp.Body)
+		return resp, b
+	}
+	head, _ := do(http.MethodHead)
+	get, body := do(http.MethodGet)
+	if head.StatusCode != http.StatusOK || get.StatusCode != http.StatusOK {
+		t.Fatalf("HEAD %d, GET %d", head.StatusCode, get.StatusCode)
+	}
+	if head.ContentLength != int64(len(body)) {
+		t.Errorf("uncached HEAD Content-Length %d, GET body %d bytes", head.ContentLength, len(body))
+	}
+}
+
+func TestProxyHeadNonRewritingUsesUpstreamHead(t *testing.T) {
+	methods := make(chan string, 4)
+	upstream := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		methods <- r.Method
+		w.Header().Set("Content-Type", "text/xml")
+		w.Write([]byte("<repomd/>"))
+	}))
+	defer upstream.Close()
+
+	createRemote(t, mustFormat(`{"name": "head-rpm", "package_type": "rpm", "base_url": %q}`, upstream.URL))
+	defer deleteRemote(t, "head-rpm")
+
+	resp, err := http.Head(apiURL("/api/v1/remote/head-rpm/repodata/repomd.xml"))
+	if err != nil {
+		t.Fatalf("HEAD: %v", err)
+	}
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusOK || resp.Header.Get("X-Artifact-Source") != "remote" {
+		t.Fatalf("HEAD %d source %q", resp.StatusCode, resp.Header.Get("X-Artifact-Source"))
+	}
+	close(methods)
+	var seen []string
+	for m := range methods {
+		seen = append(seen, m)
+	}
+	if len(seen) != 1 || seen[0] != http.MethodHead {
+		t.Errorf("upstream saw %v, want a single HEAD", seen)
+	}
+}

e2e/scheme_test.go

@@ -0,0 +1,59 @@
+//go:build e2e
+
+package e2e
+
+import (
+	"encoding/json"
+	"net/http"
+	"strings"
+	"testing"
+)
+
+func getForwardedHTTPS(t *testing.T, url string) *http.Response {
+	t.Helper()
+	req, _ := http.NewRequest(http.MethodGet, url, nil)
+	req.Header.Set("X-Forwarded-Proto", "https")
+	client := &http.Client{CheckRedirect: func(*http.Request, []*http.Request) error { return http.ErrUseLastResponse }}
+	resp, err := client.Do(req)
+	if err != nil {
+		t.Fatalf("GET %s: %v", url, err)
+	}
+	return resp
+}
+
+func TestForwardedProtoCargoConfig(t *testing.T) {
+	createRemote(t, `{"name": "scheme-cargo", "package_type": "cargo", "base_url": "https://index.crates.io"}`)
+	defer deleteRemote(t, "scheme-cargo")
+
+	resp := getForwardedHTTPS(t, apiURL("/api/v1/remote/scheme-cargo/config.json"))
+	defer resp.Body.Close()
+	var cfg map[string]string
+	if err := json.NewDecoder(resp.Body).Decode(&cfg); err != nil {
+		t.Fatal(err)
+	}
+	if want := "https://" + strings.TrimPrefix(baseURL, "http://") + "/api/v1/remote/scheme-cargo/"; !strings.HasPrefix(cfg["dl"], want) {
+		t.Errorf("dl = %q, want prefix %q", cfg["dl"], want)
+	}
+}
+
+func TestForwardedProtoVirtualRedirect(t *testing.T) {
+	createRemote(t, `{"name": "scheme-rpm", "package_type": "rpm", "base_url": "https://rpm.example.com"}`)
+	defer deleteRemote(t, "scheme-rpm")
+	resp, err := http.Post(apiURL("/api/v2/virtuals"), "application/json",
+		strings.NewReader(`{"name": "scheme-virt", "package_type": "rpm", "members": ["scheme-rpm"]}`))
+	if err != nil {
+		t.Fatal(err)
+	}
+	resp.Body.Close()
+	if resp.StatusCode != http.StatusCreated {
+		t.Fatalf("create virtual: status %d", resp.StatusCode)
+	}
+	defer deleteRequest(t, apiURL("/api/v2/virtuals/scheme-virt"))
+
+	resp = getForwardedHTTPS(t, apiURL("/api/v1/virtual/scheme-virt/scheme-rpm/Packages/a.rpm"))
+	resp.Body.Close()
+	loc := resp.Header.Get("Location")
+	if want := "https://" + strings.TrimPrefix(baseURL, "http://") + "/api/v1/remote/scheme-rpm/Packages/a.rpm"; resp.StatusCode != http.StatusFound || loc != want {
+		t.Errorf("redirect = %d %q, want 302 %q", resp.StatusCode, loc, want)
+	}
+}

internal/api/terraform/registry.go

@@ -13,6 +13,7 @@ import (
 
 	"github.com/go-chi/chi/v5"
 
+	v1 "git.unkin.net/unkin/artifactapi/internal/api/v1"
 	"git.unkin.net/unkin/artifactapi/internal/database"
 	tfprov "git.unkin.net/unkin/artifactapi/internal/provider/terraform"
 	"git.unkin.net/unkin/artifactapi/internal/tfsign"
@@ -290,12 +291,5 @@ func writeJSON(w http.ResponseWriter, v any) {
 }
 
 func baseURL(r *http.Request) string {
-	scheme := "http"
-	if r.TLS != nil {
-		scheme = "https"
-	}
-	if fwd := r.Header.Get("X-Forwarded-Proto"); fwd != "" {
-		scheme = fwd
-	}
-	return scheme + "://" + r.Host
+	return v1.Scheme(r) + "://" + r.Host
 }

internal/api/v1/gems.go

@@ -0,0 +1,308 @@
+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 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.go

@@ -0,0 +1,334 @@
+package v1
+
+import (
+	"bytes"
+	"context"
+	"crypto/sha1"
+	"crypto/sha512"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"log/slog"
+	"net/http"
+	"net/url"
+	"regexp"
+	"strings"
+
+	"github.com/go-chi/chi/v5"
+
+	"git.unkin.net/unkin/artifactapi/internal/database"
+	"git.unkin.net/unkin/artifactapi/internal/storage"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+// Local npm repos speak the npm registry publish/read protocol. Per package:
+//   <pkg>/-/<base>-<version>.tgz   tarball (immutable)
+//   <pkg>/-/<base>-<version>.json  version manifest (immutable)
+//   <pkg>/-/dist-tags/<tag>        version string (mutable)
+
+var (
+	npmNameRe   = regexp.MustCompile(`^(@[a-z0-9][a-z0-9._~-]*/)?[a-z0-9][a-z0-9._~-]*$`)
+	npmRefRe    = regexp.MustCompile(`^[0-9A-Za-z][0-9A-Za-z.+_-]*$`)
+	npmSemverRe = regexp.MustCompile(`^(0|[1-9]\d*)\.(0|[1-9]\d*)\.(0|[1-9]\d*)(?:-((?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*)(?:\.(?:0|[1-9]\d*|\d*[a-zA-Z-][0-9a-zA-Z-]*))*))?(?:\+([0-9a-zA-Z-]+(?:\.[0-9a-zA-Z-]+)*))?$`)
+
+	npmMaxPublishBytes int64 = 256 << 20
+)
+
+func (h *ProxyHandler) localNPMRemote(r *http.Request, name string) (*models.Remote, bool) {
+	remote, err := h.db.GetRemote(r.Context(), name)
+	if err != nil {
+		return nil, false
+	}
+	return remote, remote.RepoType == models.RepoTypeLocal && remote.PackageType == models.PackageNPM
+}
+
+// npmPackageName returns the package a packument/publish path addresses, or ""
+// when the path is something else (e.g. a tarball under <pkg>/-/).
+func npmPackageName(raw string) string {
+	p, err := url.PathUnescape(raw)
+	if err != nil {
+		return ""
+	}
+	p = strings.TrimSuffix(p, "/")
+	if !npmNameRe.MatchString(p) {
+		return ""
+	}
+	return p
+}
+
+type npmRelease struct {
+	version  string
+	manifest []byte
+	tarball  []byte
+	tags     []string
+}
+
+func parseNPMPublish(body io.Reader, pkg string) (*npmRelease, error) {
+	var doc struct {
+		Name        string                     `json:"name"`
+		DistTags    map[string]string          `json:"dist-tags"`
+		Versions    map[string]json.RawMessage `json:"versions"`
+		Attachments map[string]struct {
+			Data string `json:"data"`
+		} `json:"_attachments"`
+	}
+	if err := json.NewDecoder(body).Decode(&doc); err != nil {
+		return nil, fmt.Errorf("invalid publish body: %w", err)
+	}
+	if doc.Name != pkg {
+		return nil, fmt.Errorf("body name %q does not match %q", doc.Name, pkg)
+	}
+	if len(doc.Versions) != 1 || len(doc.Attachments) != 1 {
+		return nil, errors.New("publish must carry exactly one version and one tarball")
+	}
+
+	rel := &npmRelease{}
+	for v, m := range doc.Versions {
+		rel.version, rel.manifest = v, m
+	}
+	if !npmSemverRe.MatchString(rel.version) {
+		return nil, fmt.Errorf("invalid version %q", rel.version)
+	}
+	var meta struct {
+		Name    string `json:"name"`
+		Version string `json:"version"`
+		Dist    struct {
+			Integrity string `json:"integrity"`
+			Shasum    string `json:"shasum"`
+		} `json:"dist"`
+	}
+	if err := json.Unmarshal(rel.manifest, &meta); err != nil {
+		return nil, fmt.Errorf("invalid version manifest: %w", err)
+	}
+	if meta.Name != pkg || meta.Version != rel.version {
+		return nil, errors.New("version manifest name/version mismatch")
+	}
+
+	for _, a := range doc.Attachments {
+		tgz, err := base64.StdEncoding.DecodeString(a.Data)
+		if err != nil {
+			return nil, fmt.Errorf("invalid tarball encoding: %w", err)
+		}
+		rel.tarball = tgz
+	}
+	if err := verifyNPMDist(rel.tarball, meta.Dist.Integrity, meta.Dist.Shasum); err != nil {
+		return nil, err
+	}
+
+	for tag, v := range doc.DistTags {
+		if !npmRefRe.MatchString(tag) || v != rel.version {
+			return nil, fmt.Errorf("dist-tag %q must point at the published version", tag)
+		}
+		rel.tags = append(rel.tags, tag)
+	}
+	return rel, nil
+}
+
+func verifyNPMDist(tgz []byte, integrity, shasum string) error {
+	if b64, ok := strings.CutPrefix(integrity, "sha512-"); ok {
+		sum := sha512.Sum512(tgz)
+		if base64.StdEncoding.EncodeToString(sum[:]) != b64 {
+			return errors.New("tarball does not match dist.integrity")
+		}
+		return nil
+	}
+	if shasum != "" {
+		sum := sha1.Sum(tgz)
+		if hex.EncodeToString(sum[:]) != shasum {
+			return errors.New("tarball does not match dist.shasum")
+		}
+		return nil
+	}
+	return errors.New("version manifest carries no sha512 integrity or shasum")
+}
+
+func npmError(w http.ResponseWriter, status int, msg string) {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	_ = json.NewEncoder(w).Encode(map[string]string{"error": msg})
+}
+
+func (h *ProxyHandler) handleLocalPut(w http.ResponseWriter, r *http.Request) {
+	remote, ok := h.localNPMRemote(r, chi.URLParam(r, "localName"))
+	if !ok {
+		npmError(w, http.StatusMethodNotAllowed, "publish is only supported on local npm repositories")
+		return
+	}
+	pkg := npmPackageName(chi.URLParam(r, "*"))
+	if pkg == "" {
+		npmError(w, http.StatusBadRequest, "invalid package name")
+		return
+	}
+	rel, err := parseNPMPublish(http.MaxBytesReader(w, r.Body, npmMaxPublishBytes), pkg)
+	if err != nil {
+		var tooLarge *http.MaxBytesError
+		if errors.As(err, &tooLarge) {
+			npmError(w, http.StatusRequestEntityTooLarge, fmt.Sprintf("publish body exceeds %d bytes", npmMaxPublishBytes))
+			return
+		}
+		npmError(w, http.StatusBadRequest, err.Error())
+		return
+	}
+
+	base := pkg[strings.LastIndex(pkg, "/")+1:]
+	stem := pkg + "/-/" + base + "-" + rel.version
+	// The manifest gates visibility and tags may only name visible versions, so
+	// the order is tarball, manifest, tags. A tarball left by a failed publish is
+	// accepted again only with identical bytes; an existing manifest always conflicts.
+	conflict := func() {
+		npmError(w, http.StatusConflict, fmt.Sprintf("%s@%s already exists; overwrites are not allowed", pkg, rel.version))
+	}
+	ok, err = h.npmStoreImmutable(r.Context(), remote.Name, stem+".tgz", rel.tarball, "application/octet-stream")
+	if err != nil {
+		npmError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	if !ok {
+		conflict()
+		return
+	}
+	if _, err := h.npmStore(r.Context(), remote.Name, stem+".json", rel.manifest, "application/json", false); err != nil {
+		if errors.Is(err, database.ErrAlreadyExists) {
+			conflict()
+			return
+		}
+		npmError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	for _, tag := range rel.tags {
+		if _, err := h.npmStore(r.Context(), remote.Name, pkg+"/-/dist-tags/"+tag, []byte(rel.version), "text/plain", true); err != nil {
+			npmError(w, http.StatusInternalServerError, err.Error())
+			return
+		}
+	}
+
+	slog.Info("local npm package published", "repo", remote.Name, "package", pkg, "version", rel.version)
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusCreated)
+	_ = json.NewEncoder(w).Encode(map[string]any{"ok": true, "id": pkg})
+}
+
+// npmStoreImmutable reports false when path already holds different bytes.
+func (h *ProxyHandler) npmStoreImmutable(ctx context.Context, repo, path string, data []byte, contentType string) (bool, error) {
+	hash, err := h.npmStore(ctx, repo, path, data, contentType, false)
+	if !errors.Is(err, database.ErrAlreadyExists) {
+		return err == nil, err
+	}
+	existing, err := h.db.GetLocalFile(ctx, repo, path)
+	if err != nil || existing == nil {
+		return false, fmt.Errorf("read existing %s: %v", path, err)
+	}
+	return existing.ContentHash == hash, nil
+}
+
+func (h *ProxyHandler) npmStore(ctx context.Context, repo, path string, data []byte, contentType string, mutable bool) (string, error) {
+	result, err := h.cas.Store(ctx, bytes.NewReader(data), contentType)
+	if err != nil {
+		return "", err
+	}
+	if err := h.db.UpsertBlob(ctx, result.ContentHash, result.S3Key, result.SizeBytes, contentType); err != nil {
+		return "", err
+	}
+	if mutable {
+		return result.ContentHash, h.db.UpsertLocalFile(ctx, repo, path, result.ContentHash)
+	}
+	return result.ContentHash, h.db.CreateLocalFile(ctx, repo, path, result.ContentHash)
+}
+
+func (h *ProxyHandler) readLocalBlob(ctx context.Context, contentHash string) ([]byte, error) {
+	reader, _, err := h.store.Download(ctx, storage.BlobKey(strings.TrimPrefix(contentHash, "sha256:")))
+	if err != nil {
+		return nil, err
+	}
+	defer reader.Close()
+	return io.ReadAll(reader)
+}
+
+func (h *ProxyHandler) serveNPMPackument(w http.ResponseWriter, r *http.Request, remote *models.Remote, pkg string) {
+	files, err := h.db.ListLocalFilesByPrefix(r.Context(), remote.Name, pkg+"/-/")
+	if err != nil {
+		npmError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	base, ok := requestBaseURL(w, r)
+	if !ok {
+		return
+	}
+	read := func(hash string) ([]byte, error) { return h.readLocalBlob(r.Context(), hash) }
+	tarballBase := base + "/api/v1/local/" + remote.Name + "/"
+	doc, err := buildNPMPackument(pkg, files, read, tarballBase)
+	if err != nil {
+		npmError(w, http.StatusInternalServerError, err.Error())
+		return
+	}
+	if doc == nil {
+		npmError(w, http.StatusNotFound, "not found")
+		return
+	}
+	setNPMPerHostHeaders(w)
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("X-Artifact-Source", "local")
+	w.WriteHeader(http.StatusOK)
+	_ = json.NewEncoder(w).Encode(doc)
+}
+
+// setNPMPerHostHeaders keeps shared caches off packuments whose tarball URLs
+// are built from the request host and Accept (abbreviated vs full).
+func setNPMPerHostHeaders(w http.ResponseWriter) {
+	w.Header().Set("Cache-Control", "no-store")
+	w.Header().Set("Vary", "Host, X-Forwarded-Proto, Accept")
+}
+
+// buildNPMPackument returns nil when pkg has no published versions.
+func buildNPMPackument(pkg string, files []database.LocalFile, read func(hash string) ([]byte, error), tarballBase string) (map[string]any, error) {
+	prefix := pkg + "/-/"
+	versions := map[string]any{}
+	tags := 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
+		}
+		if tag, isTag := strings.CutPrefix(rest, "dist-tags/"); isTag {
+			v, err := read(f.ContentHash)
+			if err != nil {
+				return nil, err
+			}
+			tags[tag] = string(v)
+			continue
+		}
+		stem, isManifest := strings.CutSuffix(rest, ".json")
+		if !isManifest {
+			continue
+		}
+		raw, err := read(f.ContentHash)
+		if err != nil {
+			return nil, err
+		}
+		var m map[string]any
+		if err := json.Unmarshal(raw, &m); err != nil {
+			return nil, fmt.Errorf("manifest %s: %w", f.FilePath, err)
+		}
+		dist, _ := m["dist"].(map[string]any)
+		if dist == nil {
+			dist = map[string]any{}
+			m["dist"] = dist
+		}
+		dist["tarball"] = tarballBase + prefix + stem + ".tgz"
+		v, _ := m["version"].(string)
+		versions[v] = m
+	}
+	if len(versions) == 0 {
+		return nil, nil
+	}
+	for tag, v := range tags {
+		if _, ok := versions[v]; !ok {
+			delete(tags, tag)
+		}
+	}
+	return map[string]any{"_id": pkg, "name": pkg, "dist-tags": tags, "versions": versions}, nil
+}

internal/api/v1/npm_handler_test.go

@@ -0,0 +1,347 @@
+package v1
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"io"
+	"net/http"
+	"net/http/httptest"
+	"os"
+	"strings"
+	"sync"
+	"testing"
+	"time"
+
+	"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"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+var (
+	testDSN   string
+	testMinio testsupport.MinioConn
+	testRedis string
+)
+
+func TestMain(m *testing.M) {
+	ctx := context.Background()
+	dsn, termPG, err := testsupport.StartPostgres(ctx)
+	if err != nil {
+		os.Exit(m.Run())
+	}
+	conn, termMinio, err := testsupport.StartMinio(ctx)
+	if err != nil {
+		termPG()
+		os.Exit(m.Run())
+	}
+	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)
+}
+
+func npmTestServer(t *testing.T) (*ProxyHandler, *httptest.Server) {
+	t.Helper()
+	if testDSN == "" {
+		t.Skip("Docker unavailable")
+	}
+	db, err := database.New(testDSN)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Cleanup(db.Close)
+	var store *storage.S3
+	for i := 0; i < 20; i++ {
+		if store, err = storage.NewS3(testMinio.Endpoint, testMinio.AccessKey, testMinio.SecretKey, "npm", false, ""); err == nil {
+			break
+		}
+		time.Sleep(500 * time.Millisecond)
+	}
+	if err != nil {
+		t.Fatal(err)
+	}
+	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)
+	t.Cleanup(srv.Close)
+	return h, srv
+}
+
+func npmRepo(t *testing.T, h *ProxyHandler, pt models.PackageType) string {
+	t.Helper()
+	name := fmt.Sprintf("npm-%s-%d", pt, time.Now().UnixNano())
+	if err := h.db.CreateRemote(context.Background(), &models.Remote{Name: name, PackageType: pt, RepoType: models.RepoTypeLocal}); err != nil {
+		t.Fatal(err)
+	}
+	return name
+}
+
+func npmDo(t *testing.T, method, url, body string) (int, string) {
+	t.Helper()
+	req, _ := http.NewRequest(method, url, strings.NewReader(body))
+	resp, err := http.DefaultClient.Do(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+	b, _ := io.ReadAll(resp.Body)
+	return resp.StatusCode, string(b)
+}
+
+func packumentVersions(t *testing.T, url string) map[string]any {
+	t.Helper()
+	code, body := npmDo(t, http.MethodGet, url, "")
+	if code != http.StatusOK {
+		t.Fatalf("GET %s = %d: %s", url, code, body)
+	}
+	var doc struct {
+		Versions map[string]any `json:"versions"`
+	}
+	if err := json.Unmarshal([]byte(body), &doc); err != nil {
+		t.Fatal(err)
+	}
+	return doc.Versions
+}
+
+func packumentTags(t *testing.T, url string) map[string]string {
+	t.Helper()
+	_, body := npmDo(t, http.MethodGet, url, "")
+	var doc struct {
+		Tags map[string]string `json:"dist-tags"`
+	}
+	if err := json.Unmarshal([]byte(body), &doc); err != nil {
+		t.Fatal(err)
+	}
+	return doc.Tags
+}
+
+func concurrentPuts(t *testing.T, url string, bodies ...string) []int {
+	t.Helper()
+	var wg sync.WaitGroup
+	codes := make([]int, len(bodies))
+	for i, b := range bodies {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			codes[i], _ = npmDo(t, http.MethodPut, url, b)
+		}()
+	}
+	wg.Wait()
+	return codes
+}
+
+func TestNPMPublishHandler(t *testing.T) {
+	h, srv := npmTestServer(t)
+	repo := npmRepo(t, h, models.PackageNPM)
+	base := srv.URL + "/api/v1/local/" + repo + "/"
+
+	t.Run("scoped name via %2f", func(t *testing.T) {
+		body := publishBody(t, "@acme/widget", []byte("scoped tgz"), publishOpts{})
+		if code, b := npmDo(t, http.MethodPut, base+"@acme%2fwidget", body); code != http.StatusCreated {
+			t.Fatalf("publish = %d: %s", code, b)
+		}
+		v := packumentVersions(t, base+"@acme%2fwidget")
+		dist := v["1.0.0"].(map[string]any)["dist"].(map[string]any)
+		tarball := dist["tarball"].(string)
+		if !strings.HasPrefix(tarball, base+"@acme/widget/-/widget-1.0.0.tgz") {
+			t.Fatalf("tarball = %s", tarball)
+		}
+		if code, b := npmDo(t, http.MethodGet, tarball, ""); code != http.StatusOK || b != "scoped tgz" {
+			t.Fatalf("tarball fetch = %d %q", code, b)
+		}
+	})
+
+	t.Run("republish", func(t *testing.T) {
+		if code, b := npmDo(t, http.MethodPut, base+"repub", publishBody(t, "repub", []byte("v1"), publishOpts{})); code != http.StatusCreated {
+			t.Fatalf("first publish = %d: %s", code, b)
+		}
+		if code, _ := npmDo(t, http.MethodPut, base+"repub", publishBody(t, "repub", []byte("different"), publishOpts{})); code != http.StatusConflict {
+			t.Errorf("different bytes = %d, want 409", code)
+		}
+		if code, b := npmDo(t, http.MethodPut, base+"repub", publishBody(t, "repub", []byte("v2"), publishOpts{version: "1.1.0"})); code != http.StatusCreated {
+			t.Fatalf("publish 1.1.0 = %d: %s", code, b)
+		}
+		if code, _ := npmDo(t, http.MethodPut, base+"repub", publishBody(t, "repub", []byte("v1"), publishOpts{})); code != http.StatusConflict {
+			t.Errorf("identical republish = %d, want 409", code)
+		}
+		if tags := packumentTags(t, base+"repub"); tags["latest"] != "1.1.0" {
+			t.Errorf("latest = %q, want 1.1.0", tags["latest"])
+		}
+	})
+
+	t.Run("rejected republish leaves tags", func(t *testing.T) {
+		for _, v := range []string{"1.0.0", "1.1.0"} {
+			if code, b := npmDo(t, http.MethodPut, base+"rej", publishBody(t, "rej", []byte("tgz "+v), publishOpts{version: v})); code != http.StatusCreated {
+				t.Fatalf("publish %s = %d: %s", v, code, b)
+			}
+		}
+		if code, _ := npmDo(t, http.MethodPut, base+"rej", publishBody(t, "rej", []byte("tgz 1.0.0"), publishOpts{shasum: "x"})); code != http.StatusConflict {
+			t.Fatalf("re-PUT 1.0.0 = %d, want 409", code)
+		}
+		if tags := packumentTags(t, base+"rej"); tags["latest"] != "1.1.0" {
+			t.Errorf("latest = %q, want 1.1.0", tags["latest"])
+		}
+	})
+
+	t.Run("mid-publish window", func(t *testing.T) {
+		if code, b := npmDo(t, http.MethodPut, base+"mid", publishBody(t, "mid", []byte("v1"), publishOpts{})); code != http.StatusCreated {
+			t.Fatalf("publish = %d: %s", code, b)
+		}
+		ctx := context.Background()
+		if _, err := h.npmStore(ctx, repo, "mid/-/mid-1.0.1.tgz", []byte("v2"), "application/octet-stream", false); err != nil {
+			t.Fatal(err)
+		}
+		if tags := packumentTags(t, base+"mid"); tags["latest"] != "1.0.0" {
+			t.Errorf("tarball-only 1.0.1: latest = %q", tags["latest"])
+		}
+		if _, err := h.npmStore(ctx, repo, "mid/-/dist-tags/latest", []byte("1.0.1"), "text/plain", true); err != nil {
+			t.Fatal(err)
+		}
+		if tags := packumentTags(t, base+"mid"); tags["latest"] == "1.0.1" {
+			t.Error("latest points at invisible 1.0.1")
+		}
+	})
+
+	t.Run("concurrent identical", func(t *testing.T) {
+		body := publishBody(t, "same", []byte("same tgz"), publishOpts{})
+		codes := concurrentPuts(t, base+"same", body, body)
+		if codes[0]+codes[1] != http.StatusCreated+http.StatusConflict || codes[0] == codes[1] {
+			t.Fatalf("codes = %v, want one 201 and one 409", codes)
+		}
+		if tags := packumentTags(t, base+"same"); len(tags) != 1 || tags["latest"] != "1.0.0" {
+			t.Errorf("tags = %v", tags)
+		}
+	})
+
+	t.Run("concurrent different manifests", func(t *testing.T) {
+		tgz := []byte("race tgz")
+		codes := concurrentPuts(t, base+"race",
+			publishBody(t, "race", tgz, publishOpts{shasum: "a", tags: map[string]string{"a": "1.0.0"}}),
+			publishBody(t, "race", tgz, publishOpts{shasum: "b", tags: map[string]string{"b": "1.0.0"}}))
+		won := map[int]string{}
+		for i, c := range codes {
+			won[c] = []string{"a", "b"}[i]
+		}
+		if len(won) != 2 || won[http.StatusCreated] == "" || won[http.StatusConflict] == "" {
+			t.Fatalf("codes = %v, want one 201 and one 409", codes)
+		}
+		v := packumentVersions(t, base+"race")["1.0.0"].(map[string]any)
+		if got := v["dist"].(map[string]any)["shasum"]; got != won[http.StatusCreated] {
+			t.Errorf("manifest shasum = %v, winner %s", got, won[http.StatusCreated])
+		}
+		tags := packumentTags(t, base+"race")
+		if len(tags) != 1 || tags[won[http.StatusCreated]] != "1.0.0" {
+			t.Errorf("tags = %v, winner %s", tags, won[http.StatusCreated])
+		}
+	})
+
+	t.Run("retry after tarball-only write", func(t *testing.T) {
+		tgz := []byte("half published")
+		if _, err := h.npmStore(context.Background(), repo, "retry/-/retry-1.0.0.tgz", tgz, "application/octet-stream", false); err != nil {
+			t.Fatal(err)
+		}
+		if code, _ := npmDo(t, http.MethodGet, base+"retry", ""); code != http.StatusNotFound {
+			t.Fatalf("tarball-only version visible: %d", code)
+		}
+		if code, _ := npmDo(t, http.MethodPut, base+"retry", publishBody(t, "retry", []byte("other bytes"), publishOpts{})); code != http.StatusConflict {
+			t.Errorf("retry with different bytes = %d, want 409", code)
+		}
+		if code, b := npmDo(t, http.MethodPut, base+"retry", publishBody(t, "retry", tgz, publishOpts{})); code != http.StatusCreated {
+			t.Fatalf("retry with identical bytes = %d: %s", code, b)
+		}
+		if _, ok := packumentVersions(t, base+"retry")["1.0.0"]; !ok {
+			t.Error("retried version missing from packument")
+		}
+	})
+
+	t.Run("concurrent versions", func(t *testing.T) {
+		codes := concurrentPuts(t, base+"conc",
+			publishBody(t, "conc", []byte("tgz 1.0.0"), publishOpts{version: "1.0.0"}),
+			publishBody(t, "conc", []byte("tgz 2.0.0"), publishOpts{version: "2.0.0"}))
+		if codes[0] != http.StatusCreated || codes[1] != http.StatusCreated {
+			t.Fatalf("codes = %v", codes)
+		}
+		v := packumentVersions(t, base+"conc")
+		if _, ok := v["1.0.0"]; !ok {
+			t.Error("1.0.0 missing")
+		}
+		if _, ok := v["2.0.0"]; !ok {
+			t.Error("2.0.0 missing")
+		}
+	})
+
+	t.Run("body too large", func(t *testing.T) {
+		old := npmMaxPublishBytes
+		npmMaxPublishBytes = 64
+		defer func() { npmMaxPublishBytes = old }()
+		if code, _ := npmDo(t, http.MethodPut, base+"big", publishBody(t, "big", []byte("x"), publishOpts{})); code != http.StatusRequestEntityTooLarge {
+			t.Errorf("oversized body = %d, want 413", code)
+		}
+	})
+
+	t.Run("non-npm local", func(t *testing.T) {
+		generic := npmRepo(t, h, models.PackageGeneric)
+		if code, _ := npmDo(t, http.MethodPut, srv.URL+"/api/v1/local/"+generic+"/pkg", publishBody(t, "pkg", []byte("x"), publishOpts{})); code != http.StatusMethodNotAllowed {
+			t.Errorf("publish to generic local = %d, want 405", code)
+		}
+	})
+}
+
+func TestNPMPackumentPerHost(t *testing.T) {
+	h, srv := npmTestServer(t)
+	h.virtualEngine = virtual.NewEngine(h.db, nil)
+	h.virtualEngine.NPMLocal = h.LocalNPMPackument
+	repo := npmRepo(t, h, models.PackageNPM)
+	virt := "v" + repo
+	if err := h.db.CreateVirtual(context.Background(), &models.Virtual{Name: virt, PackageType: models.PackageNPM, Members: []string{repo}}); err != nil {
+		t.Fatal(err)
+	}
+	if code, b := npmDo(t, http.MethodPut, srv.URL+"/api/v1/local/"+repo+"/hostpkg", publishBody(t, "hostpkg", []byte("tgz"), publishOpts{})); code != http.StatusCreated {
+		t.Fatalf("publish = %d: %s", code, b)
+	}
+	routes := h.Routes()
+	get := func(path, host, proto string) *httptest.ResponseRecorder {
+		r := httptest.NewRequest(http.MethodGet, path, nil)
+		r.Host = host
+		if proto != "" {
+			r.Header.Set("X-Forwarded-Proto", proto)
+		}
+		w := httptest.NewRecorder()
+		routes.ServeHTTP(w, r)
+		return w
+	}
+	for _, path := range []string{"/local/" + repo + "/hostpkg", "/virtual/" + virt + "/hostpkg"} {
+		for _, host := range []string{"x@evil.com", "evil.example:"} {
+			if w := get(path, host, ""); w.Code != http.StatusBadRequest {
+				t.Errorf("%s Host %q = %d, want 400", path, host, w.Code)
+			}
+		}
+		w := get(path, "aa.example", "https")
+		if w.Code != http.StatusOK || !strings.Contains(w.Body.String(), `"tarball":"https://aa.example/api/v1/`) {
+			t.Fatalf("%s = %d: %s", path, w.Code, w.Body)
+		}
+		if cc, vary := w.Header().Get("Cache-Control"), w.Header().Get("Vary"); cc != "no-store" || vary != "Host, X-Forwarded-Proto, Accept" {
+			t.Errorf("%s Cache-Control %q Vary %q", path, cc, vary)
+		}
+	}
+}

internal/api/v1/npm_test.go

@@ -0,0 +1,166 @@
+package v1
+
+import (
+	"crypto/sha1"
+	"crypto/sha512"
+	"encoding/base64"
+	"encoding/hex"
+	"encoding/json"
+	"errors"
+	"strings"
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/database"
+)
+
+func TestNPMPackageName(t *testing.T) {
+	tests := map[string]string{
+		"left-pad":                "left-pad",
+		"left-pad/":               "left-pad",
+		"@acme%2fwidget":          "@acme/widget",
+		"@acme%2Fwidget":          "@acme/widget",
+		"@acme/widget":            "@acme/widget",
+		"left-pad/-/left-pad.tgz": "",
+		"@acme/widget/-/w-1.tgz":  "",
+		"a/b":                     "",
+		"../etc":                  "",
+		"Upper":                   "",
+		"":                        "",
+	}
+	for in, want := range tests {
+		if got := npmPackageName(in); got != want {
+			t.Errorf("npmPackageName(%q) = %q, want %q", in, got, want)
+		}
+	}
+}
+
+type publishOpts struct {
+	bodyName, manifestName, version, integrity, shasum string
+	tags                                               map[string]string
+	extraVersion                                       bool
+}
+
+func publishBody(t *testing.T, pkg string, tgz []byte, o publishOpts) string {
+	t.Helper()
+	sha := sha512.Sum512(tgz)
+	sh1 := sha1.Sum(tgz)
+	if o.bodyName == "" {
+		o.bodyName = pkg
+	}
+	if o.manifestName == "" {
+		o.manifestName = pkg
+	}
+	if o.version == "" {
+		o.version = "1.0.0"
+	}
+	if o.integrity == "" {
+		o.integrity = "sha512-" + base64.StdEncoding.EncodeToString(sha[:])
+	}
+	if o.shasum == "" {
+		o.shasum = hex.EncodeToString(sh1[:])
+	}
+	if o.tags == nil {
+		o.tags = map[string]string{"latest": o.version}
+	}
+	versions := map[string]any{o.version: map[string]any{
+		"name": o.manifestName, "version": o.version, "main": "index.js",
+		"dist": map[string]any{"integrity": o.integrity, "shasum": o.shasum, "tarball": "http://elsewhere/x.tgz"},
+	}}
+	if o.extraVersion {
+		versions["2.0.0"] = map[string]any{"name": pkg, "version": "2.0.0"}
+	}
+	b, _ := json.Marshal(map[string]any{
+		"_id": pkg, "name": o.bodyName, "dist-tags": o.tags, "versions": versions,
+		"_attachments": map[string]any{pkg + "-" + o.version + ".tgz": map[string]any{
+			"content_type": "application/octet-stream", "data": base64.StdEncoding.EncodeToString(tgz), "length": len(tgz),
+		}},
+	})
+	return string(b)
+}
+
+func TestParseNPMPublish(t *testing.T) {
+	tgz := []byte("fake tarball bytes")
+
+	rel, err := parseNPMPublish(strings.NewReader(publishBody(t, "@acme/widget", tgz, publishOpts{tags: map[string]string{"latest": "1.0.0", "beta": "1.0.0"}})), "@acme/widget")
+	if err != nil {
+		t.Fatalf("valid scoped publish rejected: %v", err)
+	}
+	if rel.version != "1.0.0" || string(rel.tarball) != string(tgz) || len(rel.tags) != 2 {
+		t.Fatalf("unexpected release: %+v", rel)
+	}
+
+	if _, err := parseNPMPublish(strings.NewReader(publishBody(t, "left-pad", tgz, publishOpts{integrity: "none", shasum: hex.EncodeToString(make([]byte, 20))})), "left-pad"); err == nil {
+		t.Fatal("shasum fallback should reject a mismatched tarball")
+	}
+	if _, err := parseNPMPublish(strings.NewReader(publishBody(t, "left-pad", tgz, publishOpts{integrity: "none"})), "left-pad"); err != nil {
+		t.Fatalf("matching shasum fallback rejected: %v", err)
+	}
+
+	bad := map[string]publishOpts{
+		"body name mismatch":        {bodyName: "other"},
+		"manifest name mismatch":    {manifestName: "other"},
+		"integrity mismatch":        {integrity: "sha512-AAAA"},
+		"path-like version":         {version: "../1.0.0"},
+		"non-semver version":        {version: "1..2"},
+		"leading-zero version":      {version: "01.0.0"},
+		"tag at another version":    {tags: map[string]string{"latest": "9.9.9"}},
+		"path-like tag":             {tags: map[string]string{"../x": "1.0.0"}},
+		"multiple versions at once": {extraVersion: true},
+	}
+	for name, o := range bad {
+		if _, err := parseNPMPublish(strings.NewReader(publishBody(t, "left-pad", tgz, o)), "left-pad"); err == nil {
+			t.Errorf("%s: expected rejection", name)
+		}
+	}
+	if _, err := parseNPMPublish(strings.NewReader(`{"name":"left-pad","versions":{}}`), "left-pad"); err == nil {
+		t.Error("deprecate-style body without attachments should be rejected")
+	}
+}
+
+func TestBuildNPMPackument(t *testing.T) {
+	blobs := map[string]string{
+		"h1": `{"name":"my_pkg","version":"1.0.0","dist":{"shasum":"aa","tarball":"http://elsewhere/x.tgz"}}`,
+		"h2": `{"name":"my_pkg","version":"1.1.0"}`,
+		"h3": "1.1.0",
+		"h4": "2.0.0",
+		"hx": `{"name":"myXpkg","version":"6.6.6"}`,
+	}
+	read := func(h string) ([]byte, error) {
+		b, ok := blobs[h]
+		if !ok {
+			return nil, errors.New("missing blob")
+		}
+		return []byte(b), nil
+	}
+	files := []database.LocalFile{
+		{FilePath: "my_pkg/-/dist-tags/latest", ContentHash: "h3"},
+		{FilePath: "my_pkg/-/dist-tags/next", ContentHash: "h4"},
+		{FilePath: "my_pkg/-/my_pkg-1.0.0.json", ContentHash: "h1"},
+		{FilePath: "my_pkg/-/my_pkg-1.0.0.tgz", ContentHash: "nope"},
+		{FilePath: "my_pkg/-/my_pkg-1.1.0.json", ContentHash: "h2"},
+		{FilePath: "myXpkg/-/myXpkg-6.6.6.json", ContentHash: "hx"},
+	}
+
+	doc, err := buildNPMPackument("my_pkg", files, read, "http://reg/api/v1/local/npm/")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if tags := doc["dist-tags"].(map[string]string); tags["latest"] != "1.1.0" || len(tags) != 1 {
+		t.Errorf("dist-tags = %v", tags)
+	}
+	versions := doc["versions"].(map[string]any)
+	if len(versions) != 2 {
+		t.Fatalf("versions = %v (LIKE over-match must be dropped)", versions)
+	}
+	v1 := versions["1.0.0"].(map[string]any)["dist"].(map[string]any)
+	if v1["tarball"] != "http://reg/api/v1/local/npm/my_pkg/-/my_pkg-1.0.0.tgz" || v1["shasum"] != "aa" {
+		t.Errorf("1.0.0 dist = %v", v1)
+	}
+	if versions["1.1.0"].(map[string]any)["dist"].(map[string]any)["tarball"] != "http://reg/api/v1/local/npm/my_pkg/-/my_pkg-1.1.0.tgz" {
+		t.Error("1.1.0 missing rewritten tarball")
+	}
+
+	if doc, err := buildNPMPackument("absent", files, read, "x/"); err != nil || doc != nil {
+		t.Errorf("absent package: doc=%v err=%v", doc, err)
+	}
+}

internal/api/v1/npm_virtual.go

@@ -0,0 +1,26 @@
+package v1
+
+import (
+	"context"
+	"encoding/json"
+
+	"git.unkin.net/unkin/artifactapi/internal/virtual"
+)
+
+// LocalNPMPackument serves a local npm repo's packument to npm virtuals, with
+// tarball paths relative to the repo.
+func (h *ProxyHandler) LocalNPMPackument(ctx context.Context, repo, pkg string) ([]byte, error) {
+	files, err := h.db.ListLocalFilesByPrefix(ctx, repo, pkg+"/-/")
+	if err != nil {
+		return nil, err
+	}
+	read := func(hash string) ([]byte, error) { return h.readLocalBlob(ctx, hash) }
+	doc, err := buildNPMPackument(pkg, files, read, "")
+	if err != nil {
+		return nil, err
+	}
+	if doc == nil {
+		return nil, virtual.ErrNotFound
+	}
+	return json.Marshal(doc)
+}

internal/api/v1/proxy.go

@@ -1,11 +1,15 @@
 package v1
 
 import (
+	"bytes"
 	"errors"
 	"fmt"
 	"io"
 	"log/slog"
+	"net"
 	"net/http"
+	"strconv"
+	"strings"
 
 	"github.com/go-chi/chi/v5"
 
@@ -15,6 +19,7 @@ import (
 	"git.unkin.net/unkin/artifactapi/internal/proxy"
 	"git.unkin.net/unkin/artifactapi/internal/storage"
 	"git.unkin.net/unkin/artifactapi/internal/virtual"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
 )
 
 type ProxyHandler struct {
@@ -40,8 +45,14 @@ func NewProxyHandler(engine *proxy.Engine, virtualEngine *virtual.Engine, db *da
 func (h *ProxyHandler) Routes() chi.Router {
 	r := chi.NewRouter()
 	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
 }
 
@@ -67,31 +78,43 @@ func (h *ProxyHandler) handleDockerPing(w http.ResponseWriter, r *http.Request)
 	w.WriteHeader(http.StatusOK)
 }
 
-func (h *ProxyHandler) handleProxy(w http.ResponseWriter, r *http.Request) {
+// remoteFor resolves the remote and provider named in the request, writing the
+// error response itself when either is missing.
+func (h *ProxyHandler) remoteFor(w http.ResponseWriter, r *http.Request) (*models.Remote, provider.Provider, bool) {
 	remoteName := chi.URLParam(r, "remoteName")
-	path := chi.URLParam(r, "*")
-
 	remote, err := h.db.GetRemote(r.Context(), remoteName)
 	if err != nil {
 		http.Error(w, fmt.Sprintf("remote %q not found", remoteName), http.StatusNotFound)
-		return
+		return nil, nil, false
 	}
-
 	prov, err := provider.Get(remote.PackageType)
 	if err != nil {
 		http.Error(w, fmt.Sprintf("no provider for %q", remote.PackageType), http.StatusInternalServerError)
+		return nil, nil, false
+	}
+	return remote, prov, true
+}
+
+// serveRemote lets metadata-only remotes (e.g. github_rpm) synthesize their own
+// responses and redirect package downloads instead of proxying bytes.
+func (h *ProxyHandler) serveRemote(w http.ResponseWriter, r *http.Request, remote *models.Remote, prov provider.Provider, path string) bool {
+	rs, ok := prov.(provider.RemoteServer)
+	return ok && rs.ServeRemote(w, r, *remote, path, fmt.Sprintf("%s://%s", Scheme(r), r.Host), h.db)
+}
+
+func (h *ProxyHandler) handleProxy(w http.ResponseWriter, r *http.Request) {
+	remote, prov, ok := h.remoteFor(w, r)
+	if !ok {
 		return
 	}
-
-	// Metadata-only remotes (e.g. github_rpm) synthesize their own responses and
-	// redirect package downloads to a backend remote instead of proxying bytes.
-	if rs, ok := prov.(provider.RemoteServer); ok {
-		proxyBaseURL := fmt.Sprintf("%s://%s", scheme(r), r.Host)
-		if rs.ServeRemote(w, r, *remote, path, proxyBaseURL, h.db) {
-			return
-		}
+	path := chi.URLParam(r, "*")
+	if h.serveRemote(w, r, remote, prov, path) {
+		return
 	}
+	h.serveFetch(w, r, remote, prov, path)
+}
 
+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)
 	if err != nil {
 		var proxyErr *proxy.ProxyError
@@ -99,34 +122,51 @@ func (h *ProxyHandler) handleProxy(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, proxyErr.Message, proxyErr.Status)
 			return
 		}
-		slog.Error("proxy fetch failed", "remote", remoteName, "path", path, "error", err)
+		slog.Error("proxy fetch failed", "remote", remote.Name, "path", path, "error", err)
 		http.Error(w, "bad gateway", http.StatusBadGateway)
 		return
 	}
 	defer result.Reader.Close()
 
+	var body io.Reader = result.Reader
+	if sr, ok := prov.(provider.ServeRewriter); ok && prov.Classify(path) == provider.Mutable {
+		raw, ok := rewriteServed(w, r, sr, *remote, result.Reader)
+		if !ok {
+			return
+		}
+		body, result.Size = bytes.NewReader(raw), int64(len(raw))
+	}
+
 	w.Header().Set("Content-Type", result.ContentType)
 	w.Header().Set("X-Artifact-Source", result.Source)
 	if result.Size > 0 {
+		w.Header().Set("Content-Length", fmt.Sprintf("%d", result.Size))
 		w.Header().Set("X-Artifact-Size", fmt.Sprintf("%d", result.Size))
 	}
 	w.WriteHeader(http.StatusOK)
-	io.Copy(w, result.Reader)
+	io.Copy(w, body)
 }
 
-func (h *ProxyHandler) handleProxyHead(w http.ResponseWriter, r *http.Request) {
-	remoteName := chi.URLParam(r, "remoteName")
-	path := chi.URLParam(r, "*")
+func rewritesMutable(prov provider.Provider, path string) bool {
+	_, sr := prov.(provider.ServeRewriter)
+	_, rr := prov.(provider.ResponseRewriter)
+	return (sr || rr) && prov.Classify(path) == provider.Mutable
+}
 
-	remote, err := h.db.GetRemote(r.Context(), remoteName)
-	if err != nil {
-		http.Error(w, fmt.Sprintf("remote %q not found", remoteName), http.StatusNotFound)
+// handleProxyHead answers HEAD like GET without a body. Responses a provider
+// synthesizes or rewrites per request go through the GET path so their headers
+// match; everything else is answered from store metadata or an upstream HEAD.
+func (h *ProxyHandler) handleProxyHead(w http.ResponseWriter, r *http.Request) {
+	remote, prov, ok := h.remoteFor(w, r)
+	if !ok {
 		return
 	}
-
-	prov, err := provider.Get(remote.PackageType)
-	if err != nil {
-		http.Error(w, fmt.Sprintf("no provider for %q", remote.PackageType), http.StatusInternalServerError)
+	path := chi.URLParam(r, "*")
+	if h.serveRemote(w, r, remote, prov, path) {
+		return
+	}
+	if rewritesMutable(prov, path) {
+		h.serveFetch(w, r, remote, prov, path)
 		return
 	}
 
@@ -137,7 +177,7 @@ func (h *ProxyHandler) handleProxyHead(w http.ResponseWriter, r *http.Request) {
 			http.Error(w, proxyErr.Message, proxyErr.Status)
 			return
 		}
-		slog.Error("proxy head failed", "remote", remoteName, "path", path, "error", err)
+		slog.Error("proxy head failed", "remote", remote.Name, "path", path, "error", err)
 		http.Error(w, "bad gateway", http.StatusBadGateway)
 		return
 	}
@@ -160,7 +200,15 @@ func (h *ProxyHandler) handleVirtual(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	proxyBaseURL := fmt.Sprintf("%s://%s", scheme(r), r.Host)
+	proxyBaseURL, ok := requestBaseURL(w, r)
+	if !ok {
+		return
+	}
+
+	if virt.PackageType == models.PackageGems {
+		h.serveVirtualGems(w, r, *virt, path, proxyBaseURL)
+		return
+	}
 
 	loc, ok, err := h.virtualEngine.MemberRedirect(r.Context(), *virt, path, r.URL.RawQuery, proxyBaseURL)
 	if err != nil {
@@ -172,7 +220,14 @@ func (h *ProxyHandler) handleVirtual(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	body, contentType, err := h.virtualEngine.Fetch(r.Context(), *virt, path, proxyBaseURL)
+	var body []byte
+	var contentType string
+	if virt.PackageType == models.PackageNPM {
+		abbreviated := strings.Contains(r.Header.Get("Accept"), virtual.NPMAbbreviatedType)
+		body, contentType, err = h.virtualEngine.FetchNPM(r.Context(), *virt, path, proxyBaseURL, abbreviated)
+	} else {
+		body, contentType, err = h.virtualEngine.Fetch(r.Context(), *virt, path, proxyBaseURL)
+	}
 	if errors.Is(err, virtual.ErrNotFound) {
 		http.Error(w, "not found", http.StatusNotFound)
 		return
@@ -183,6 +238,9 @@ func (h *ProxyHandler) handleVirtual(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if virt.PackageType == models.PackageNPM {
+		setNPMPerHostHeaders(w)
+	}
 	w.Header().Set("Content-Type", contentType)
 	w.Header().Set("X-Artifact-Source", "virtual")
 	w.WriteHeader(http.StatusOK)
@@ -199,6 +257,23 @@ func (h *ProxyHandler) handleLocal(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
+	if remote.PackageType == models.PackageNPM {
+		if pkg := npmPackageName(path); pkg != "" {
+			h.serveNPMPackument(w, r, remote, pkg)
+			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
+		}
+	}
+
 	prov, _ := provider.Get(remote.PackageType)
 	if indexer, ok := prov.(provider.LocalIndexer); ok {
 		if indexer.ServeLocalIndex(w, r, h.db, remote.Name, path) {
@@ -237,12 +312,78 @@ func (h *ProxyHandler) serveLocalFile(w http.ResponseWriter, r *http.Request, re
 	io.Copy(w, reader)
 }
 
-func scheme(r *http.Request) string {
+// Scheme returns the client-facing scheme: TLS, else the first
+// X-Forwarded-Proto value when it is http or https, else http.
+func Scheme(r *http.Request) string {
 	if r.TLS != nil {
 		return "https"
 	}
-	if fwd := r.Header.Get("X-Forwarded-Proto"); fwd != "" {
+	fwd, _, _ := strings.Cut(r.Header.Get("X-Forwarded-Proto"), ",")
+	if fwd = strings.ToLower(strings.TrimSpace(fwd)); fwd == "https" {
 		return fwd
 	}
 	return "http"
 }
+
+// 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) {
+	base, ok := requestBaseURL(w, r)
+	if !ok {
+		return nil, false
+	}
+	raw, err := io.ReadAll(src)
+	if err != nil {
+		http.Error(w, "bad gateway", http.StatusBadGateway)
+		return nil, false
+	}
+	raw = sr.RewriteServed(raw, remote, base)
+	w.Header().Set("Cache-Control", "no-store")
+	w.Header().Set("Vary", "Host, X-Forwarded-Proto")
+	w.Header().Set("Content-Length", strconv.Itoa(len(raw)))
+	return raw, true
+}
+
+// requestBaseURL returns the client-facing scheme://host, answering 400 on an
+// invalid Host.
+func requestBaseURL(w http.ResponseWriter, r *http.Request) (string, bool) {
+	if !validHost(r.Host) {
+		http.Error(w, "invalid host header", http.StatusBadRequest)
+		return "", false
+	}
+	return Scheme(r) + "://" + r.Host, true
+}
+
+// validHost accepts host[:port] where host is a DNS name or IP literal.
+func validHost(hostport string) bool {
+	host, port := hostport, ""
+	if h, p, err := net.SplitHostPort(hostport); err == nil {
+		if p == "" {
+			return false
+		}
+		host, port = h, p
+	} else if strings.HasPrefix(hostport, "[") {
+		return strings.HasSuffix(hostport, "]") && net.ParseIP(hostport[1:len(hostport)-1]) != nil
+	}
+	if port != "" {
+		if n, err := strconv.Atoi(port); err != nil || n < 1 || n > 65535 {
+			return false
+		}
+	}
+	if net.ParseIP(host) != nil {
+		return true
+	}
+	if strings.HasPrefix(hostport, "[") {
+		return false
+	}
+	if host == "" || len(host) > 253 {
+		return false
+	}
+	for _, label := range strings.Split(strings.TrimSuffix(host, "."), ".") {
+		if label == "" || len(label) > 63 || label[0] == '-' || label[len(label)-1] == '-' ||
+			strings.Trim(strings.ToLower(label), "abcdefghijklmnopqrstuvwxyz0123456789-_") != "" {
+			return false
+		}
+	}
+	return true
+}

internal/api/v1/rewrite_test.go

@@ -0,0 +1,74 @@
+package v1
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider/nuget"
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+func TestValidHost(t *testing.T) {
+	for _, h := range []string{"aa.example", "aa.example:8443", "artifactapi.k8s.syd1.au.unkin.net", "10.0.0.1:80", "[::1]:8080", "[::1]", "::1", "localhost", "my_host.local"} {
+		if !validHost(h) {
+			t.Errorf("validHost(%q) = false, want true", h)
+		}
+	}
+	for _, h := range []string{"", "evil\".example", "a b", "aa.example:0", "aa.example:99999", "aa.example:x", "aa.example:", ":8080", "-bad.example", "a..b", "[::1", "[nope]:80", "a/b", "a<script>", strings.Repeat("a", 64) + ".example"} {
+		if validHost(h) {
+			t.Errorf("validHost(%q) = true, want false", h)
+		}
+	}
+}
+
+var nugetOrg = models.Remote{Name: "nuget-org", BaseURL: "https://api.nuget.org/v3/index.json"}
+
+const serviceIndex = `{"resources":[{"@id":"https://api.nuget.org/v3-flatcontainer/"}]}`
+
+func rewrite(t *testing.T, host, proto string) (*httptest.ResponseRecorder, string, bool) {
+	t.Helper()
+	r := httptest.NewRequest(http.MethodGet, "/api/v1/remote/nuget-org/index.json", nil)
+	r.Host = host
+	if proto != "" {
+		r.Header.Set("X-Forwarded-Proto", proto)
+	}
+	w := httptest.NewRecorder()
+	raw, ok := rewriteServed(w, r, &nuget.Provider{}, nugetOrg, strings.NewReader(serviceIndex))
+	return w, string(raw), ok
+}
+
+func TestRewriteServedHeaders(t *testing.T) {
+	w, body, ok := rewrite(t, "aa.example:8443", "https")
+	if !ok {
+		t.Fatal("valid request rejected")
+	}
+	if want := `{"resources":[{"@id":"https://aa.example:8443/api/v1/remote/nuget-org/v3-flatcontainer/"}]}`; body != want {
+		t.Errorf("body = %s, want %s", body, want)
+	}
+	if got := w.Header().Get("Cache-Control"); got != "no-store" {
+		t.Errorf("Cache-Control = %q, want no-store", got)
+	}
+	if got := w.Header().Get("Vary"); got != "Host, X-Forwarded-Proto" {
+		t.Errorf("Vary = %q", got)
+	}
+	if got := w.Header().Get("Content-Length"); got != "91" || len(body) != 91 {
+		t.Errorf("Content-Length = %q, body len %d", got, len(body))
+	}
+}
+
+func TestRewriteServedIgnoresBogusProto(t *testing.T) {
+	_, plain, _ := rewrite(t, "aa.example", "")
+	_, bogus, _ := rewrite(t, "aa.example", "javascript")
+	if bogus != plain || !strings.Contains(bogus, `"http://aa.example/`) {
+		t.Errorf("bogus X-Forwarded-Proto changed the body: %s", bogus)
+	}
+}
+
+func TestRewriteServedRejectsInvalidHost(t *testing.T) {
+	w, _, ok := rewrite(t, `evil"},{"x":"`, "")
+	if ok || w.Code != http.StatusBadRequest {
+		t.Errorf("invalid host: ok=%v code=%d, want rejected with 400", ok, w.Code)
+	}
+}

internal/api/v1/routes_test.go

@@ -0,0 +1,41 @@
+package v1
+
+import (
+	"net/http"
+	"testing"
+
+	"github.com/go-chi/chi/v5"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+	"git.unkin.net/unkin/artifactapi/internal/provider/npm"
+	"git.unkin.net/unkin/artifactapi/internal/provider/nuget"
+	"git.unkin.net/unkin/artifactapi/internal/provider/rpm"
+)
+
+func TestRoutesRemoteHead(t *testing.T) {
+	r := (&ProxyHandler{}).Routes()
+	for _, m := range []string{http.MethodGet, http.MethodHead} {
+		if !r.Match(chi.NewRouteContext(), m, "/remote/myremote/some/path") {
+			t.Errorf("%s /remote/myremote/some/path not routed", m)
+		}
+	}
+}
+
+func TestRewritesMutable(t *testing.T) {
+	tests := []struct {
+		name string
+		prov provider.Provider
+		path string
+		want bool
+	}{
+		{"npm packument", &npm.Provider{}, "left-pad", true},
+		{"npm tarball", &npm.Provider{}, "left-pad/-/left-pad-1.3.0.tgz", false},
+		{"nuget index", &nuget.Provider{}, "index.json", true},
+		{"rpm repodata", &rpm.Provider{}, "repodata/repomd.xml", false},
+	}
+	for _, tc := range tests {
+		if got := rewritesMutable(tc.prov, tc.path); got != tc.want {
+			t.Errorf("%s: rewritesMutable = %v, want %v", tc.name, got, tc.want)
+		}
+	}
+}

internal/api/v1/scheme_test.go

@@ -7,14 +7,28 @@ import (
 )
 
 func TestScheme(t *testing.T) {
-	if got := scheme(&http.Request{TLS: &tls.ConnectionState{}}); got != "https" {
+	if got := Scheme(&http.Request{TLS: &tls.ConnectionState{}}); got != "https" {
 		t.Errorf("TLS request scheme = %q, want https", got)
 	}
 	r := &http.Request{Header: http.Header{"X-Forwarded-Proto": {"https"}}}
-	if got := scheme(r); got != "https" {
+	if got := Scheme(r); got != "https" {
 		t.Errorf("X-Forwarded-Proto scheme = %q, want https", got)
 	}
-	if got := scheme(&http.Request{Header: http.Header{}}); got != "http" {
+	for fwd, want := range map[string]string{
+		"https, http": "https",
+		"http, https": "http",
+		"HTTPS":       "https",
+		" https ":     "https",
+		"javascript":  "http",
+		"ftp":         "http",
+		"https;evil":  "http",
+	} {
+		r := &http.Request{Header: http.Header{"X-Forwarded-Proto": {fwd}}}
+		if got := Scheme(r); got != want {
+			t.Errorf("X-Forwarded-Proto %q scheme = %q, want %s", fwd, got, want)
+		}
+	}
+	if got := Scheme(&http.Request{Header: http.Header{}}); got != "http" {
 		t.Errorf("default scheme = %q, want http", got)
 	}
 }

internal/api/v2/remotes.go

@@ -67,8 +67,12 @@ func (h *RemotesHandler) get(w http.ResponseWriter, r *http.Request) {
 	writeJSON(w, http.StatusOK, remote)
 }
 
+// defaultMutableTTL matches the remotes.mutable_ttl column default; a create
+// that omits mutable_ttl gets it, an explicit 0 still means never expire.
+const defaultMutableTTL = 3600
+
 func (h *RemotesHandler) create(w http.ResponseWriter, r *http.Request) {
-	var remote models.Remote
+	remote := models.Remote{MutableTTL: defaultMutableTTL}
 	if err := json.NewDecoder(r.Body).Decode(&remote); err != nil {
 		http.Error(w, "invalid json", http.StatusBadRequest)
 		return
@@ -114,7 +118,15 @@ func (h *RemotesHandler) create(w http.ResponseWriter, r *http.Request) {
 
 func (h *RemotesHandler) update(w http.ResponseWriter, r *http.Request) {
 	name := chi.URLParam(r, "name")
+	// Capture the current backend before the update so we can tell whether the
+	// remote's base_url (its upstream) changed. A read failure just means we
+	// skip the freshness flush; it must not block the update.
+	existing, err := h.db.GetRemote(r.Context(), name)
+	oldKnown := err == nil
 	var remote models.Remote
+	if oldKnown {
+		remote.MutableTTL = existing.MutableTTL
+	}
 	if err := json.NewDecoder(r.Body).Decode(&remote); err != nil {
 		http.Error(w, "invalid json", http.StatusBadRequest)
 		return
@@ -132,13 +144,6 @@ func (h *RemotesHandler) update(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusBadRequest)
 		return
 	}
-	// Capture the current backend before the update so we can tell whether the
-	// remote's base_url (its upstream) changed. A read failure just means we
-	// skip the freshness flush; it must not block the update.
-	oldBaseURL, oldKnown := "", false
-	if existing, err := h.db.GetRemote(r.Context(), name); err == nil {
-		oldBaseURL, oldKnown = existing.BaseURL, true
-	}
 	if err := h.db.UpdateRemote(r.Context(), &remote); err != nil {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
@@ -147,13 +152,13 @@ func (h *RemotesHandler) update(w http.ResponseWriter, r *http.Request) {
 	// Release / APKINDEX): purge it so the next request re-fetches from the new
 	// upstream instead of serving stale data until TTL expiry. A flush failure
 	// is logged but does not fail the request — the DB update already landed.
-	if oldKnown && oldBaseURL != remote.BaseURL && h.cache != nil {
+	if oldKnown && existing.BaseURL != remote.BaseURL && h.cache != nil {
 		if err := h.cache.FlushRemote(r.Context(), name); err != nil {
 			slog.Warn("flush cached metadata after base_url change failed",
 				"remote", name, "error", err)
 		} else {
 			slog.Info("flushed cached metadata after base_url change",
-				"remote", name, "old_base_url", oldBaseURL, "new_base_url", remote.BaseURL)
+				"remote", name, "old_base_url", existing.BaseURL, "new_base_url", remote.BaseURL)
 		}
 	}
 	writeJSON(w, http.StatusOK, remote)
@@ -165,6 +170,11 @@ func (h *RemotesHandler) del(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, err.Error(), http.StatusInternalServerError)
 		return
 	}
+	if h.cache != nil {
+		if err := h.cache.FlushRemote(r.Context(), name); err != nil {
+			slog.Warn("flush cached metadata after delete failed", "remote", name, "error", err)
+		}
+	}
 	w.WriteHeader(http.StatusNoContent)
 }
 

internal/api/v2/remotes_flush_test.go

@@ -94,3 +94,28 @@ func TestUpdateFlushFailureStillSucceeds(t *testing.T) {
 		t.Fatalf("flush calls = %v, want exactly one attempted flush", ff.calls)
 	}
 }
+
+// Deleting a remote flushes its cached state so a re-created remote of the
+// same name starts cold; a flush error does not fail the delete.
+func TestDeleteFlushesCache(t *testing.T) {
+	if testDSN == "" {
+		t.Skip("Docker unavailable")
+	}
+	db, err := database.New(testDSN)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+
+	for _, ff := range []*fakeFlusher{{}, {err: errors.New("redis down")}} {
+		const name = "rpm-flush-delete"
+		seedRemote(t, db, name, "https://example.com/repo")
+		h := NewRemotesHandler(db, ff, nil).Routes()
+		if c := do(t, h, "DELETE", "/"+name, ""); c != 204 {
+			t.Fatalf("delete = %d, want 204", c)
+		}
+		if len(ff.calls) != 1 || ff.calls[0] != name {
+			t.Fatalf("flush calls = %v, want exactly one flush of %q", ff.calls, name)
+		}
+	}
+}

internal/api/v2/remotes_ttl_test.go

@@ -0,0 +1,57 @@
+package v2
+
+import (
+	"context"
+	"testing"
+
+	"git.unkin.net/unkin/artifactapi/internal/database"
+)
+
+// An omitted mutable_ttl defaults to 3600 on create and keeps the stored value
+// on update; an explicit 0 is stored as 0 in both.
+func TestMutableTTLOmittedVsZero(t *testing.T) {
+	if testDSN == "" {
+		t.Skip("Docker unavailable")
+	}
+	db, err := database.New(testDSN)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer db.Close()
+	h := NewRemotesHandler(db, nil, nil).Routes()
+	ttl := func(name string) int {
+		t.Helper()
+		r, err := db.GetRemote(context.Background(), name)
+		if err != nil {
+			t.Fatalf("get %s: %v", name, err)
+		}
+		return r.MutableTTL
+	}
+	const body = `"package_type":"rpm","base_url":"https://example.com/repo"`
+
+	steps := []struct {
+		method, path, json string
+		want               int
+	}{
+		{"POST", "/", `{"name":"ttl-omit",` + body + `}`, 3600},
+		{"PUT", "/ttl-omit", `{` + body + `,"mutable_ttl":120}`, 120},
+		{"PUT", "/ttl-omit", `{` + body + `}`, 120},
+		{"PUT", "/ttl-omit", `{` + body + `,"mutable_ttl":0}`, 0},
+		{"PUT", "/ttl-omit", `{` + body + `}`, 0},
+	}
+	for i, s := range steps {
+		if c := do(t, h, s.method, s.path, s.json); c/100 != 2 {
+			t.Fatalf("step %d %s %s = %d", i, s.method, s.path, c)
+		}
+		if got := ttl("ttl-omit"); got != s.want {
+			t.Errorf("step %d: mutable_ttl = %d, want %d", i, got, s.want)
+		}
+	}
+
+	if c := do(t, h, "POST", "/", `{"name":"ttl-zero",`+body+`,"mutable_ttl":0}`); c != 201 {
+		t.Fatalf("create explicit 0 = %d", c)
+	}
+	if got := ttl("ttl-zero"); got != 0 {
+		t.Errorf("explicit 0 stored as %d", got)
+	}
+}

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")
 	}
 }
 
@@ -86,6 +122,12 @@ func TestETagAndToken(t *testing.T) {
 	if v, _ := testRedis.GetETag(ctx, "r", "p"); v != `"abc"` {
 		t.Errorf("etag = %q", v)
 	}
+	if err := testRedis.SetETag(ctx, "r", "p", "", 0); err != nil {
+		t.Fatal(err)
+	}
+	if v, _ := testRedis.GetETag(ctx, "r", "p"); v != "" {
+		t.Errorf("empty etag should drop the stored one, got %q", v)
+	}
 
 	if v, _ := testRedis.GetToken(ctx, "missing"); v != "" {
 		t.Error("missing token should be empty")

internal/cache/redis.go

@@ -2,6 +2,7 @@ package cache
 
 import (
 	"context"
+	"crypto/rand"
 	"fmt"
 	"strings"
 	"time"
@@ -46,19 +47,31 @@ 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.
 func (r *Redis) SetETag(ctx context.Context, remote, path, etag string, ttl time.Duration) error {
 	key := fmt.Sprintf("etag:%s:%s", remote, path)
+	if etag == "" {
+		return r.client.Del(ctx, key).Err()
+	}
 	return r.client.Set(ctx, key, etag, ttl).Err()
 }
 

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/database/helm_metadata.go

@@ -0,0 +1,44 @@
+package database
+
+import (
+	"context"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+)
+
+func (db *DB) InsertHelmMetadata(ctx context.Context, meta *provider.HelmMetadata) error {
+	_, err := db.Pool.Exec(ctx, `
+		INSERT INTO helm_metadata (repo_name, file_path, content_hash, name, version, chart_yaml)
+		VALUES ($1,$2,$3,$4,$5,$6)
+		ON CONFLICT (repo_name, file_path) DO NOTHING
+	`, meta.RepoName, meta.FilePath, meta.ContentHash, meta.Name, meta.Version, meta.ChartYAML)
+	return err
+}
+
+func (db *DB) DeleteHelmMetadata(ctx context.Context, repoName, filePath string) error {
+	_, err := db.Pool.Exec(ctx, `DELETE FROM helm_metadata WHERE repo_name = $1 AND file_path = $2`, repoName, filePath)
+	return err
+}
+
+func (db *DB) ListHelmMetadataEntries(ctx context.Context, repoName string) ([]provider.HelmMetadata, error) {
+	rows, err := db.Pool.Query(ctx, `
+		SELECT repo_name, file_path, content_hash, name, version, chart_yaml, created_at
+		FROM helm_metadata
+		WHERE repo_name = $1
+		ORDER BY name, version, file_path
+	`, repoName)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var result []provider.HelmMetadata
+	for rows.Next() {
+		var m provider.HelmMetadata
+		if err := rows.Scan(&m.RepoName, &m.FilePath, &m.ContentHash, &m.Name, &m.Version, &m.ChartYAML, &m.CreatedAt); err != nil {
+			return nil, err
+		}
+		result = append(result, m)
+	}
+	return result, rows.Err()
+}

internal/database/puppet_metadata.go

@@ -0,0 +1,46 @@
+package database
+
+import (
+	"context"
+
+	"git.unkin.net/unkin/artifactapi/internal/provider"
+)
+
+func (db *DB) InsertPuppetMetadata(ctx context.Context, meta *provider.PuppetMetadata) error {
+	_, err := db.Pool.Exec(ctx, `
+		INSERT INTO puppet_metadata (repo_name, file_path, content_hash, slug, version, metadata_json, file_size, file_md5)
+		VALUES ($1,$2,$3,$4,$5,$6,$7,$8)
+		ON CONFLICT (repo_name, file_path) DO NOTHING
+	`, meta.RepoName, meta.FilePath, meta.ContentHash, meta.Slug, meta.Version, meta.MetadataJSON, meta.Size, meta.MD5)
+	return err
+}
+
+func (db *DB) DeletePuppetMetadata(ctx context.Context, repoName, filePath string) error {
+	_, err := db.Pool.Exec(ctx, `DELETE FROM puppet_metadata WHERE repo_name = $1 AND file_path = $2`, repoName, filePath)
+	return err
+}
+
+// ListPuppetMetadataEntries returns a repo's releases, optionally narrowed to
+// one module slug (empty slug lists every module).
+func (db *DB) ListPuppetMetadataEntries(ctx context.Context, repoName, slug string) ([]provider.PuppetMetadata, error) {
+	rows, err := db.Pool.Query(ctx, `
+		SELECT repo_name, file_path, content_hash, slug, version, metadata_json, file_size, file_md5, created_at
+		FROM puppet_metadata
+		WHERE repo_name = $1 AND ($2 = '' OR slug = $2)
+		ORDER BY slug, file_path
+	`, repoName, slug)
+	if err != nil {
+		return nil, err
+	}
+	defer rows.Close()
+
+	var result []provider.PuppetMetadata
+	for rows.Next() {
+		var m provider.PuppetMetadata
+		if err := rows.Scan(&m.RepoName, &m.FilePath, &m.ContentHash, &m.Slug, &m.Version, &m.MetadataJSON, &m.Size, &m.MD5, &m.CreatedAt); err != nil {
+			return nil, err
+		}
+		result = append(result, m)
+	}
+	return result, rows.Err()
+}

internal/provider/all/alpine.go

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

internal/provider/all/cargo.go

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

internal/provider/all/deb.go

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

internal/provider/all/docker.go

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

internal/provider/all/gems.go

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

internal/provider/all/generic.go

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

internal/provider/all/goproxy.go

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

internal/provider/all/helm.go

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

internal/provider/all/npm.go

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

internal/provider/all/nuget.go

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

internal/provider/all/puppet.go

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

internal/provider/all/pypi.go

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

internal/provider/all/rpm.go

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

internal/provider/all/terraform.go

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

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/cap_file_store.go

@@ -0,0 +1,15 @@
+package provider
+
+import (
+	"context"
+	"io"
+)
+
+type FileStore interface {
+	ListFilesByPrefix(ctx context.Context, repoName, prefix string) ([]FileEntry, error)
+	ListPackages(ctx context.Context, repoName string) ([]string, error)
+}
+
+type BlobReader interface {
+	Download(ctx context.Context, key string) (io.ReadCloser, int64, error)
+}

internal/provider/cap_index_merger.go

@@ -0,0 +1,10 @@
+package provider
+
+type IndexMerger interface {
+	MergeIndexes(members []MemberIndex, proxyBaseURL string) ([]byte, error)
+}
+
+type MemberIndex struct {
+	RemoteName string
+	Body       []byte
+}

internal/provider/cap_local_indexer.go

@@ -0,0 +1,11 @@
+package provider
+
+import (
+	"context"
+	"net/http"
+)
+
+type LocalIndexer interface {
+	ServeLocalIndex(w http.ResponseWriter, r *http.Request, files FileStore, repoName, path string) bool
+	GenerateLocalIndex(ctx context.Context, files FileStore, repoName, path string) ([]byte, error)
+}

internal/provider/cap_local_uploader.go

@@ -0,0 +1,6 @@
+package provider
+
+type LocalUploader interface {
+	ValidateUpload(filePath string) (storagePath, contentType string, err error)
+	UploadResponse(storagePath, contentHash string, sizeBytes int64) map[string]any
+}

internal/provider/cap_post_delete_hook.go

@@ -0,0 +1,11 @@
+package provider
+
+import (
+	"context"
+)
+
+// PostDeleteHook lets a provider clean up derived state (e.g. RPM metadata that
+// feeds generated repodata) after a local file is removed.
+type PostDeleteHook interface {
+	AfterDelete(ctx context.Context, repoName, storagePath string, db MetadataDeleter) error
+}

internal/provider/cap_post_upload_hook.go

@@ -0,0 +1,9 @@
+package provider
+
+import (
+	"context"
+)
+
+type PostUploadHook interface {
+	AfterUpload(ctx context.Context, repoName, storagePath, contentHash string, blobs BlobReader, db MetadataStore)
+}

internal/provider/cap_remote_server.go

@@ -0,0 +1,25 @@
+package provider
+
+import (
+	"net/http"
+
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+// RemoteServer lets a remote provider fully answer a request itself instead of
+// going through the byte-proxy engine. It is the remote-side analog of
+// LocalIndexer: a metadata-only remote (e.g. github_rpm) uses it to synthesize
+// repodata from derived per-asset metadata and to redirect package downloads to
+// a backend remote, without ever precaching the packages. Returning false lets
+// the normal proxy path take over.
+type RemoteServer interface {
+	ServeRemote(w http.ResponseWriter, r *http.Request, remote models.Remote, path, proxyBaseURL string, store RemoteMetadataStore) bool
+}
+
+// RemoteMetadataStore is the persistence surface a RemoteServer needs to cache
+// and read the metadata it derives per upstream asset. *database.DB satisfies it.
+type RemoteMetadataStore interface {
+	RPMMetadataReader
+	MetadataStore
+	MetadataDeleter
+}

internal/provider/cap_response_rewriter.go

@@ -0,0 +1,7 @@
+package provider
+
+// ResponseRewriter marks providers whose RewriteResponse changes mutable
+// bodies, so the served length is only known after a fetch.
+type ResponseRewriter interface {
+	RewritesResponse()
+}

internal/provider/cap_serve_rewriter.go

@@ -0,0 +1,12 @@
+package provider
+
+import (
+	"git.unkin.net/unkin/artifactapi/pkg/models"
+)
+
+// ServeRewriter rewrites a cached mutable remote response per request, for
+// indexes whose URLs must name the requesting host and so cannot be rewritten
+// before caching.
+type ServeRewriter interface {
+	RewriteServed(body []byte, remote models.Remote, proxyBaseURL string) []byte
+}