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>

AGENT.md

@@ -366,8 +366,8 @@ obeys the safety rules (§1.4).
   - Read: `list_repos`, `get_repo`, `get_active_project`, `get_activity`,
     `get_pending_switch`, `list_prs`.
   - Act: `git_fetch`, `git_pull`, `git_push`, `git_commit`, `git_checkout`,
-    `create_branch`, `git_discard_changes`, `merge_and_cleanup_pr`,
+    `create_branch`, `git_discard_changes`, `create_pr`, `merge_and_cleanup_pr`,
-    `set_active_project`, `ack_switch`. (More — `create_pr` — as they land.)
+    `set_active_project`, `ack_switch`.
 - **A tool's result type must be a struct, never a bare slice/map/scalar.** The
   go-sdk infers each tool's `outputSchema` from its handler's result type, and MCP
   structured output must be a JSON **object** (`type: "object"`). A handler that

CHANGELOG.md

@@ -230,3 +230,16 @@ Append-only running history of all changes (AGENT.md §9.1). Newest last.
   `cmd/server/main.go`, `components/repo-menu`, `web/templates/help.html`,
   `AGENT.md` (§8.1). Checkout isn't §1.4-destructive — git refuses if it would
   overwrite uncommitted changes.
+
+## 2026-09-20 — Slice 10: create_pr
+- **What:** forge `CreatePullRequest` (Gitea; empty base → repo default branch,
+  via GetRepo). Service `CreatePR` (records `pr-created`). HTTP
+  `POST /api/repo/pr/create`. MCP tool `create_pr`. `<pr-list>` gained a
+  "New pull request…" button (head = selected repo's current branch, base =
+  default). AGENT.md §8.1 lists `create_pr` in Act.
+- **Why:** Open PRs from the app or Claude — the front half of the PR workflow
+  whose back half is "Merge & clean up".
+- **Affects:** `internal/forge`, `internal/service`, `internal/mcp`,
+  `cmd/server/main.go`, `components/pr-list`, `web/templates/help.html`,
+  `AGENT.md`.
+- **Note:** the head branch must already exist on the remote (push first).

cmd/server/main.go

@@ -240,6 +240,23 @@ func main() {
 		}
 		return c.JSON(http.StatusOK, map[string]any{"supported": true, "prs": prs})
 	})
+	e.POST("/api/repo/pr/create", func(c echo.Context) error {
+		var body struct {
+			Path  string `json:"path"`
+			Head  string `json:"head"`
+			Base  string `json:"base"`
+			Title string `json:"title"`
+			Body  string `json:"body"`
+		}
+		if err := c.Bind(&body); err != nil {
+			return c.JSON(http.StatusBadRequest, map[string]string{"error": "invalid body"})
+		}
+		pr, err := svc.CreatePR(c.Request().Context(), activity.ActorUser, body.Path, body.Head, body.Base, body.Title, body.Body)
+		if err != nil {
+			return c.JSON(http.StatusBadGateway, map[string]string{"error": err.Error()})
+		}
+		return c.JSON(http.StatusOK, pr)
+	})
 	e.POST("/api/repo/pr/merge", func(c echo.Context) error {
 		var body struct {
 			Path   string `json:"path"`

components/pr-list/pr-list.js

@@ -10,6 +10,7 @@ class PRList extends HTMLElement {
   #controller = null;
   #onSelect = null;
   #path = '';
+  #repo = null;
 
   constructor() {
     super();
@@ -18,7 +19,7 @@ class PRList extends HTMLElement {
 
   connectedCallback() {
     this.#renderShell();
-    this.#onSelect = (e) => this.#load(e.detail?.path);
+    this.#onSelect = (e) => { this.#repo = e.detail; this.#load(e.detail?.path); };
     document.addEventListener('repo:select', this.#onSelect);
   }
 
@@ -64,6 +65,25 @@ class PRList extends HTMLElement {
     }
   }
 
+  async #create() {
+    const branch = this.#repo?.branch;
+    if (!branch) return;
+    const title = window.prompt(`Open a pull request from "${branch}" (into the default branch).\nTitle:`, branch);
+    if (title === null) return;
+    try {
+      const res = await fetch('/api/repo/pr/create', {
+        method: 'POST',
+        headers: { 'Content-Type': 'application/json' },
+        body: JSON.stringify({ path: this.#path, head: branch, base: '', title: title.trim() || branch }),
+      });
+      const data = await res.json();
+      if (!res.ok) throw new Error(data.error || `HTTP ${res.status}`);
+      this.#load(this.#path); // refresh so the new PR appears
+    } catch (err) {
+      window.alert(`Create PR failed: ${err.message}`);
+    }
+  }
+
   #render(prs) {
     const body = this.shadowRoot.getElementById('body');
     if (prs.length === 0) {
@@ -102,8 +122,13 @@ class PRList extends HTMLElement {
         :host { display: block; }
         .box { background: var(--surface-1); border: 1px solid var(--border);
                border-radius: var(--radius); padding: 14px 16px; }
+        .hd { display: flex; align-items: center; gap: 8px; margin-bottom: 8px; }
         h3 { font-size: 12px; text-transform: uppercase; letter-spacing: .04em;
-             color: var(--color-fg-muted); margin: 0 0 8px; }
+             color: var(--color-fg-muted); margin: 0; }
+        #new { margin-left: auto; font: inherit; cursor: pointer; padding: 3px 10px;
+               border-radius: var(--radius-sm); border: 1px solid var(--fill-accent);
+               color: var(--fill-accent); background: transparent; }
+        #new:hover { background: var(--surface-2); }
         ul { list-style: none; margin: 0; padding: 0; display: grid; gap: 10px; }
         li { border-top: 1px solid var(--border); padding-top: 8px; }
         li:first-child { border-top: none; padding-top: 0; }
@@ -124,9 +149,13 @@ class PRList extends HTMLElement {
         .error { color: var(--color-danger); }
       </style>
       <div class="box">
-        <h3>Pull requests</h3>
+        <div class="hd">
+          <h3>Pull requests</h3>
+          <button id="new" title="Open a PR from the current branch">New pull request…</button>
+        </div>
         <div id="body"><p class="muted">Select a repository.</p></div>
       </div>`;
+    this.shadowRoot.getElementById('new').addEventListener('click', () => this.#create());
   }
 
   #esc(s) {

components/pr-list/pr-list.md

@@ -13,10 +13,14 @@ naming the PR, base, and branch to be deleted.
   configured or the repo isn't on the forge host.
 - **Listens:** `repo:select` on `document` — loads PRs for `event.detail.path`.
 - **Fetches:** `GET /api/repo/prs?path=…` (`{supported:false}` → hidden).
-- **Writes:** `POST /api/repo/pr/merge {path, number}` after a `confirm()`.
+- **Writes:** `POST /api/repo/pr/merge {path, number}` after a `confirm()`;
+  `POST /api/repo/pr/create {path, head, base, title}` via the "New pull request…"
+  button (head = the selected repo's current branch, base = the repo default).
 
 ## History
 - 2026-09-20: created — slice 5 (forge); list open PRs + "Merge & clean up".
+- 2026-09-20: added "New pull request…" (create_pr) — opens a PR from the
+  selected repo's current branch into the default branch (slice 10).
 
 ## Notes / gotchas
 - Requires `GITEA_URL` + `GITEA_TOKEN` on the server; otherwise the component

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).

web/templates/help.html

@@ -88,7 +88,9 @@
     <h2>Pull requests: Merge &amp; clean up</h2>
     <p>
       When a repository is hosted on your Gitea server, its open pull requests
-      appear under the details panel. Each has a <strong>Merge &amp; clean up</strong>
+      appear under the details panel. Use <strong>New pull request…</strong> to
+      open one from the selected repo's current branch (push the branch first).
+      Each open PR has a <strong>Merge &amp; clean up</strong>
       button: it squash-merges the pull request and <strong>deletes its
       branch</strong> in one step, so finished work doesn't leave branches lying
       around. You'll be asked to confirm — it names the pull request and the branch