Slice 10: create_pr (open a pull request)

forge CreatePullRequest (Gitea; empty base resolves to the repo default branch). Service CreatePR records a pr-created event. HTTP POST /api/repo/pr/create; MCP tool create_pr; <pr-list> New pull request button (head = selected repo current branch, base = default). Live-tested end-to-end: app create_pr opened a real PR (base auto-resolved), listed, then cleaned up; main untouched.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

internal/forge/forge.go

@@ -48,11 +48,21 @@ type MergeResult struct {
 	BranchDeleted bool   `json:"branchDeleted"`
 }
 
+// NewPR describes a pull request to open. An empty Base means "the repo's
+// default branch".
+type NewPR struct {
+	Head  string
+	Base  string
+	Title string
+	Body  string
+}
+
 // Provider talks to one hosting provider.
 type Provider interface {
 	// Handles reports whether this provider serves the given remote host.
 	Handles(host string) bool
 	ListPullRequests(ctx context.Context, owner, repo string) ([]PullRequest, error)
+	CreatePullRequest(ctx context.Context, owner, repo string, pr NewPR) (PullRequest, error)
 	MergeAndCleanup(ctx context.Context, owner, repo string, number int64, method MergeMethod) (MergeResult, error)
 }
 

internal/forge/gitea.go

@@ -54,6 +54,36 @@ func (g *Gitea) ListPullRequests(_ context.Context, owner, repo string) ([]PullR
 	return out, nil
 }
 
+// CreatePullRequest opens a PR. An empty Base resolves to the repo's default
+// branch. Requires the head branch to already exist on the remote.
+func (g *Gitea) CreatePullRequest(_ context.Context, owner, repo string, pr NewPR) (PullRequest, error) {
+	if strings.TrimSpace(pr.Head) == "" {
+		return PullRequest{}, fmt.Errorf("a head branch is required")
+	}
+	base := strings.TrimSpace(pr.Base)
+	if base == "" {
+		r, _, err := g.client.GetRepo(owner, repo)
+		if err != nil {
+			return PullRequest{}, err
+		}
+		base = r.DefaultBranch
+	}
+	title := pr.Title
+	if strings.TrimSpace(title) == "" {
+		title = pr.Head
+	}
+	created, _, err := g.client.CreatePullRequest(owner, repo, gitea.CreatePullRequestOption{
+		Head:  pr.Head,
+		Base:  base,
+		Title: title,
+		Body:  pr.Body,
+	})
+	if err != nil {
+		return PullRequest{}, err
+	}
+	return toPR(created), nil
+}
+
 // MergeAndCleanup merges the PR and deletes its head branch (when the head is in
 // the same repo — never a fork's branch). Callers MUST have confirmed with the
 // user first (§1.4).

internal/mcp/mcp.go

@@ -81,6 +81,15 @@ type mergePRInput struct {
 	Number int64  `json:"number" jsonschema:"the pull request number to merge and clean up"`
 }
 
+// createPRInput describes a pull request to open.
+type createPRInput struct {
+	Path  string `json:"path" jsonschema:"absolute path of the repository, from list_repos"`
+	Head  string `json:"head" jsonschema:"the branch to merge from (must already exist on the remote)"`
+	Base  string `json:"base" jsonschema:"the branch to merge into; leave empty for the repo's default branch"`
+	Title string `json:"title" jsonschema:"the pull request title"`
+	Body  string `json:"body" jsonschema:"the pull request description (optional)"`
+}
+
 // gitCommitInput is the argument schema for git_commit.
 type gitCommitInput struct {
 	Path    string `json:"path" jsonschema:"absolute path of the repository, from list_repos"`
@@ -196,6 +205,18 @@ func NewServer(svc *service.Service, version string) *mcpsdk.Server {
 		return nil, prListOutput{PRs: prs}, nil
 	})
 
+	// create_pr — open a pull request from a branch.
+	mcpsdk.AddTool(s, &mcpsdk.Tool{
+		Name:        "create_pr",
+		Description: "Open a pull request from head into base (leave base empty for the repo's default branch). The head branch must already exist on the remote — push it first. Path is from list_repos.",
+	}, func(ctx context.Context, _ *mcpsdk.CallToolRequest, in createPRInput) (*mcpsdk.CallToolResult, forge.PullRequest, error) {
+		pr, err := svc.CreatePR(ctx, activity.ActorClaude, in.Path, in.Head, in.Base, in.Title, in.Body)
+		if err != nil {
+			return nil, forge.PullRequest{}, err
+		}
+		return nil, pr, nil
+	})
+
 	// merge_and_cleanup_pr — DESTRUCTIVE: merges a PR and deletes its branch.
 	mcpsdk.AddTool(s, &mcpsdk.Tool{
 		Name:        "merge_and_cleanup_pr",

internal/service/service.go

@@ -137,6 +137,22 @@ func (s *Service) ForgePRs(ctx context.Context, repoPath string) ([]forge.PullRe
 	return s.forge.ListPullRequests(ctx, owner, repo)
 }
 
+// CreatePR opens a pull request from head into base (empty base = the repo's
+// default branch) and records the action. The head branch must already exist on
+// the remote (push it first).
+func (s *Service) CreatePR(ctx context.Context, actor activity.Actor, repoPath, head, base, title, body string) (forge.PullRequest, error) {
+	owner, repo, err := s.resolveForge(ctx, repoPath)
+	if err != nil {
+		return forge.PullRequest{}, err
+	}
+	pr, err := s.forge.CreatePullRequest(ctx, owner, repo, forge.NewPR{Head: head, Base: base, Title: title, Body: body})
+	if err != nil {
+		return forge.PullRequest{}, err
+	}
+	s.feed.Record(actor, "pr-created", filepath.Clean(repoPath), fmt.Sprintf("PR #%d %s → %s", pr.Number, pr.Head, pr.Base))
+	return pr, nil
+}
+
 // MergeAndCleanup merges a PR and deletes its branch, then records the action.
 // The caller is responsible for confirming with the user first (§1.4); actor
 // distinguishes a UI action (user) from an MCP one (claude).