feat: mention teammates from Today updates (Closes #1064)

tests/e2e/fake_gitea.py

@@ -89,6 +89,11 @@ class FakeGiteaHandler(BaseHTTPRequestHandler):
             self._json(200, REPOSITORY)
         elif path == "/api/v1/repos/search":
             self._json(200, {"data": [REPOSITORY], "ok": True})
+        elif path == "/api/v1/repos/acme/mobile/assignees":
+            self._json(200, [
+                USER,
+                {"id": 2, "login": "alex", "full_name": "Alexander", "active": True},
+            ])
         elif path == "/api/v1/repos/issues/search":
             is_assigned_scan = query.get("assigned") == ["true"] and query.get("type") == ["issues"]
             is_available_scan = not any(

tests/e2e/test_mobile_today_handoff_release.py

@@ -96,6 +96,33 @@ def test_release_artifact_plans_hands_off_and_opens_next_mobile_issue(tmp_path:
                     "created_at": "2026-08-18T00:00:00Z",
                 }]
             }
+            page.locator("[data-mobile-today-update]").click()
+            expect(page.locator("#today-progress-sheet")).to_be_visible()
+            progress = page.locator("#today-progress-body")
+            progress.fill("Pairing with @al")
+            mention = page.locator('#today-progress-body-mentions [data-login="alex"]')
+            try:
+                expect(mention).to_be_visible()
+            except AssertionError as error:
+                raise AssertionError({
+                    "status": page.locator("#today-progress-body-mention-status").text_content(),
+                    "requests": fake.requests[-20:],
+                    "browser_errors": browser_errors,
+                    "failed_responses": failed_responses,
+                }) from error
+            mention_bounds = mention.bounding_box()
+            assert mention_bounds and mention_bounds["height"] >= 44
+            mention.click()
+            expect(progress).to_have_value("Pairing with @alex ")
+            page.locator("#post-today-progress").click()
+            expect(page.locator("#today-progress-sheet")).to_be_hidden()
+            admitted = page.evaluate("""() => {
+                const record = JSON.parse(localStorage.getItem('stackchain.authored-outbox.v1') || 'null');
+                return record?.items?.find(item => item.kind === 'issue-comment' && item.number === 41);
+            }""")
+            assert admitted and admitted["repository"] == "acme/mobile"
+            assert admitted["body"] == "Pairing with @alex"
+
             page.locator("[data-mobile-today-update]").click()
             expect(page.locator("#today-progress-sheet")).to_be_visible()
             owned = page.locator('[data-comment-id="701"]')
@@ -192,7 +219,10 @@ def test_release_artifact_plans_hands_off_and_opens_next_mobile_issue(tmp_path:
             expect(page.locator("#issue-comment")).to_have_value("")
             expect(page.locator("[data-mobile-today-hud]")).to_have_attribute("data-overlay-hidden", "true")
             expect(page.locator("[data-mobile-today-hud]")).to_contain_text("Polish desktop filters")
-            assert fake.comments == [(41, "Handoff complete; continuing with the next Today item.")]
+            assert fake.comments == [
+                (41, "Pairing with @alex"),
+                (41, "Handoff complete; continuing with the next Today item."),
+            ]
 
             receipt = page.locator("#today-completion-undo")
             expect(receipt).to_be_visible()