Add agentpr pr edit subcommand

Update a PR's title and/or body as the agent user, sending only the
fields supplied.

cmd/agentpr/main.go

@@ -5,6 +5,7 @@
 //
 //	agentpr pr create --repo owner/repo --base main --head feature --title T --body B
 //	agentpr pr comment --repo owner/repo --pr 12 --body "..."
+//	agentpr pr edit --repo owner/repo --pr 12 --title T --body B
 //	agentpr whoami
 package main
 
@@ -56,9 +57,9 @@ func client() (*agent.GiteaClient, error) {
 func newPRCmd() *cobra.Command {
 	cmd := &cobra.Command{
 		Use:   "pr",
-		Short: "Create PRs and post PR comments",
+		Short: "Create and edit PRs, and post PR comments",
 	}
-	cmd.AddCommand(newPRCreateCmd(), newPRCommentCmd())
+	cmd.AddCommand(newPRCreateCmd(), newPRCommentCmd(), newPREditCmd())
 	return cmd
 }
 
@@ -143,6 +144,55 @@ func newPRCommentCmd() *cobra.Command {
 	return cmd
 }
 
+func newPREditCmd() *cobra.Command {
+	var repo, title, body string
+	var pr int
+	cmd := &cobra.Command{
+		Use:          "edit",
+		Short:        "Edit a pull request's title and/or body",
+		SilenceUsage: true,
+		RunE: func(cmd *cobra.Command, args []string) error {
+			owner, name, err := agent.ParseRepo(repo)
+			if err != nil {
+				return err
+			}
+			if pr <= 0 {
+				return fmt.Errorf("--pr must be a positive PR number")
+			}
+			// Only the flags actually given are sent: omitting --title must
+			// leave the title as it is, not blank it.
+			var opts agent.EditPROptions
+			if cmd.Flags().Changed("title") {
+				opts.Title = &title
+			}
+			if cmd.Flags().Changed("body") {
+				opts.Body = &body
+			}
+			if opts.Title == nil && opts.Body == nil {
+				return fmt.Errorf("at least one of --title or --body is required")
+			}
+			c, err := client()
+			if err != nil {
+				return err
+			}
+			updated, err := c.EditPR(owner+"/"+name, pr, opts)
+			if err != nil {
+				return err
+			}
+			fmt.Printf("#%d %s\n", updated.Number, updated.HTMLURL)
+			return nil
+		},
+	}
+	f := cmd.Flags()
+	f.StringVar(&repo, "repo", "", "Repository as owner/repo (required)")
+	f.IntVar(&pr, "pr", 0, "PR number (required)")
+	f.StringVar(&title, "title", "", "New PR title (unchanged when omitted)")
+	f.StringVar(&body, "body", "", "New PR body (unchanged when omitted)")
+	_ = cmd.MarkFlagRequired("repo")
+	_ = cmd.MarkFlagRequired("pr")
+	return cmd
+}
+
 func newWhoamiCmd() *cobra.Command {
 	return &cobra.Command{
 		Use:          "whoami",

cmd/agentpr/main_test.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"io"
+	"strings"
 	"testing"
 )
 
@@ -16,3 +17,19 @@ func TestExecuteBadRepoErrors(t *testing.T) {
 		t.Fatal("Execute() = nil, want error for a malformed --repo")
 	}
 }
+
+// `pr edit` with neither --title nor --body has nothing to send; it must fail
+// with a usage error before any Vault/Gitea call, so this stays hermetic.
+func TestPREditRequiresTitleOrBody(t *testing.T) {
+	cmd := newRootCmd()
+	cmd.SetArgs([]string{"pr", "edit", "--repo", "unkin/repo", "--pr", "7"})
+	cmd.SetOut(io.Discard)
+	cmd.SetErr(io.Discard)
+	err := cmd.Execute()
+	if err == nil {
+		t.Fatal("Execute() = nil, want an error when neither --title nor --body is given")
+	}
+	if !strings.Contains(err.Error(), "--title or --body") {
+		t.Errorf("error = %q, want it to name the missing flags", err)
+	}
+}