feat(forge): per-user forge connections — keyring, host-keyed resolution, project pin (#2778)

A forge token is a user's credential, not an instance's. The single
admin-settings config is replaced by per-user keyring rows (one per forge
host), and every server-side forge read runs on the PROJECT OWNER's keyring:

- forge_connections table + projects.forge_connection_id pin (migration 0078,
  which also carries the existing admin config into the first admin's row and
  deletes the old setting keys — no legacy dual-read)
- get_forge() replaced by get_forges(owner_id, project_id) -> ForgeSelector;
  resolve(repo) picks the connection whose host serves the repo. A pinned
  project uses ONLY its pinned connection; a stale pin (ownership moved) is
  ignored, never honored across users
- env FORGE_* config survives as an implicit entry for admin owners only;
  a stored row for the same host beats it
- consumers threaded: pull-time freshness (owner of the note), coverage
  (owner of the project), coverage routes' configured flag
- routes: /api/settings/forge-connections CRUD + per-connection test
  (own-rows only, tokens never returned); /api/admin/forge shrinks to
  /api/admin/forge-webhook (secret only); PUT /api/projects/<id>/forge pins,
  owner-or-admin asking, owner's connections only
- UI: Git Forges card moves to Settings -> Integrations as a connection
  list; webhook secret stays in the admin Config tab; owner-only forge
  select on the project coverage card
- backups exclude forge_connections (credentials, api_keys precedent) and
  the pin, so restores fall back to keyring resolution

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/scribe/routes/settings.py

@@ -20,7 +20,8 @@ settings_bp = Blueprint("settings", __name__, url_prefix="/api/settings")
 # read and skip the mask on write; this generic KV surface has to apply the
 # same treatment, or it silently un-masks what those endpoints masked — the
 # rows live on the admin's own user_id, so the plain GET returned them raw.
-_SECRET_KEYS = frozenset({"smtp_password", "forge_token", "forge_webhook_secret"})
+# (forge_token left with 0078: forge credentials are keyring rows now, #2778.)
+_SECRET_KEYS = frozenset({"smtp_password", "forge_webhook_secret"})
 _SECRET_MASK = "********"
 
 
@@ -73,3 +74,103 @@ async def test_search():
     if not Config.searxng_enabled():
         return jsonify({"configured": False, "results": [], "searxng_url": ""})
     return jsonify({"configured": True, "results": [], "searxng_url": Config.SEARXNG_URL})
+
+
+# --- forge connections (#2778) ------------------------------------------------
+# The user's keyring: read-only forge credentials, one per host, resolved by
+# repo host for every server-side forge read on the user's projects. Strictly
+# own-rows — a connection is a credential, and there is no admin view of
+# another user's keyring. Tokens never leave the server: the model's to_dict
+# omits them, and the routes never echo the submitted value back.
+
+
+@settings_bp.route("/forge-connections", methods=["GET"])
+@login_required
+async def list_forge_connections_route():
+    from scribe.services.forge import FORGE_KINDS
+    from scribe.services.forge_connections import list_connections
+
+    uid = get_current_user_id()
+    rows = await list_connections(uid)
+    return jsonify({
+        "connections": [r.to_dict() for r in rows],
+        "kinds": list(FORGE_KINDS),
+    })
+
+
+@settings_bp.route("/forge-connections", methods=["POST"])
+@login_required
+async def create_forge_connection_route():
+    from scribe.services.forge_connections import create_connection
+
+    uid = get_current_user_id()
+    data = await request.get_json() or {}
+    try:
+        row = await create_connection(
+            uid,
+            kind=str(data.get("kind", "")),
+            base_url=str(data.get("base_url", "")),
+            token=str(data.get("token", "")),
+        )
+    except ValueError as exc:
+        return jsonify({"error": str(exc)}), 400
+    return jsonify(row.to_dict()), 201
+
+
+@settings_bp.route("/forge-connections/<int:connection_id>", methods=["PUT"])
+@login_required
+async def update_forge_connection_route(connection_id: int):
+    from scribe.services.forge_connections import update_connection
+
+    uid = get_current_user_id()
+    data = await request.get_json() or {}
+    token = str(data.get("token", ""))
+    # The mask coming back means "unchanged" — the form round-trips what the
+    # list showed, and storing the mask would silently break the connection.
+    if token == _SECRET_MASK:
+        token = ""
+    try:
+        row = await update_connection(
+            uid, connection_id,
+            kind=str(data.get("kind", "")),
+            base_url=str(data.get("base_url", "")),
+            token=token,
+        )
+    except ValueError as exc:
+        return jsonify({"error": str(exc)}), 400
+    if row is None:
+        return jsonify({"error": "Connection not found"}), 404
+    return jsonify(row.to_dict())
+
+
+@settings_bp.route("/forge-connections/<int:connection_id>", methods=["DELETE"])
+@login_required
+async def delete_forge_connection_route(connection_id: int):
+    from scribe.services.forge_connections import delete_connection
+
+    uid = get_current_user_id()
+    if not await delete_connection(uid, connection_id):
+        return jsonify({"error": "Connection not found"}), 404
+    return "", 204
+
+
+@settings_bp.route("/forge-connections/<int:connection_id>/test", methods=["POST"])
+@login_required
+async def test_forge_connection_route(connection_id: int):
+    """Probe the SAVED connection: reachability and token acceptance in one
+    press, so a misconfiguration is visible now rather than as silent
+    fallbacks later (#2663's lesson, applied per keyring row)."""
+    from scribe.services.forge import ForgeError, build_adapter
+    from scribe.services.forge_connections import get_connection
+
+    uid = get_current_user_id()
+    row = await get_connection(uid, connection_id)
+    if row is None:
+        return jsonify({"error": "Connection not found"}), 404
+    adapter = build_adapter(row.kind, row.base_url, row.token)
+    if adapter is None:
+        return jsonify({"error": "Connection is not usable — check kind and base URL"}), 400
+    try:
+        return jsonify(await adapter.check())
+    except ForgeError as exc:
+        return jsonify({"error": str(exc)}), 502