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>

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