Fix AP blueprint cross-DB queries + harden Ghost sync init

AP blueprints (activitypub.py, ap_social.py) were querying federation
tables (ap_actor_profiles etc.) on g.s which points to the app's own DB
after the per-app split. Now uses g._ap_s backed by get_federation_session()
for non-federation apps.

Also hardens Ghost sync before_app_serving to catch/rollback on failure
instead of crashing the Hypercorn worker.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

shared/infrastructure/ap_social.py

@@ -19,10 +19,56 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
     """Create a per-app social blueprint scoped to *app_name*."""
     bp = Blueprint("ap_social", __name__, url_prefix="/social")
 
+    # ------------------------------------------------------------------
+    # Federation session — AP tables live in db_federation.
+    # ------------------------------------------------------------------
+    from shared.db.session import needs_federation_session, create_federation_session
+
+    @bp.before_request
+    async def _open_ap_session():
+        if needs_federation_session():
+            sess = create_federation_session()
+            g._ap_s = sess
+            g._ap_tx = await sess.begin()
+            g._ap_own = True
+        else:
+            g._ap_s = g.s
+            g._ap_own = False
+
+    @bp.after_request
+    async def _commit_ap_session(response):
+        if getattr(g, "_ap_own", False):
+            if 200 <= response.status_code < 400:
+                try:
+                    await g._ap_tx.commit()
+                except Exception:
+                    try:
+                        await g._ap_tx.rollback()
+                    except Exception:
+                        pass
+        return response
+
+    @bp.teardown_request
+    async def _close_ap_session(exc):
+        if getattr(g, "_ap_own", False):
+            s = getattr(g, "_ap_s", None)
+            if s:
+                if exc is not None or s.in_transaction():
+                    tx = getattr(g, "_ap_tx", None)
+                    if tx and tx.is_active:
+                        try:
+                            await tx.rollback()
+                        except Exception:
+                            pass
+                try:
+                    await s.close()
+                except Exception:
+                    pass
+
     @bp.before_request
     async def load_actor():
         if g.get("user"):
-            actor = await services.federation.get_actor_by_user_id(g.s, g.user.id)
+            actor = await services.federation.get_actor_by_user_id(g._ap_s, g.user.id)
             g._social_actor = actor
 
     def _require_actor():
@@ -51,10 +97,10 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
         total = 0
         followed_urls: set[str] = set()
         if query:
-            actors, total = await services.federation.search_actors(g.s, query)
+            actors, total = await services.federation.search_actors(g._ap_s, query)
             if actor:
                 following, _ = await services.federation.get_following(
-                    g.s, actor.preferred_username, page=1, per_page=1000,
+                    g._ap_s, actor.preferred_username, page=1, per_page=1000,
                 )
                 followed_urls = {a.actor_url for a in following}
         return await render_template(
@@ -77,11 +123,11 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
         followed_urls: set[str] = set()
         if query:
             actors, total = await services.federation.search_actors(
-                g.s, query, page=page,
+                g._ap_s, query, page=page,
             )
             if actor:
                 following, _ = await services.federation.get_following(
-                    g.s, actor.preferred_username, page=1, per_page=1000,
+                    g._ap_s, actor.preferred_username, page=1, per_page=1000,
                 )
                 followed_urls = {a.actor_url for a in following}
         return await render_template(
@@ -103,7 +149,7 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
         remote_actor_url = form.get("actor_url", "")
         if remote_actor_url:
             await services.federation.send_follow(
-                g.s, actor.preferred_username, remote_actor_url,
+                g._ap_s, actor.preferred_username, remote_actor_url,
             )
         if request.headers.get("HX-Request"):
             return await _actor_card_response(actor, remote_actor_url, is_followed=True)
@@ -116,7 +162,7 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
         remote_actor_url = form.get("actor_url", "")
         if remote_actor_url:
             await services.federation.unfollow(
-                g.s, actor.preferred_username, remote_actor_url,
+                g._ap_s, actor.preferred_username, remote_actor_url,
             )
         if request.headers.get("HX-Request"):
             return await _actor_card_response(actor, remote_actor_url, is_followed=False)
@@ -125,7 +171,7 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
     async def _actor_card_response(actor, remote_actor_url, is_followed):
         """Re-render a single actor card after follow/unfollow via HTMX."""
         remote_dto = await services.federation.get_or_fetch_remote_actor(
-            g.s, remote_actor_url,
+            g._ap_s, remote_actor_url,
         )
         if not remote_dto:
             return Response("", status=200)
@@ -151,10 +197,10 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
     async def followers_list():
         actor = _require_actor()
         actors, total = await services.federation.get_followers_paginated(
-            g.s, actor.preferred_username, app_domain=app_name,
+            g._ap_s, actor.preferred_username, app_domain=app_name,
         )
         following, _ = await services.federation.get_following(
-            g.s, actor.preferred_username, page=1, per_page=1000,
+            g._ap_s, actor.preferred_username, page=1, per_page=1000,
         )
         followed_urls = {a.actor_url for a in following}
         return await render_template(
@@ -171,10 +217,10 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
         actor = _require_actor()
         page = request.args.get("page", 1, type=int)
         actors, total = await services.federation.get_followers_paginated(
-            g.s, actor.preferred_username, page=page, app_domain=app_name,
+            g._ap_s, actor.preferred_username, page=page, app_domain=app_name,
         )
         following, _ = await services.federation.get_following(
-            g.s, actor.preferred_username, page=1, per_page=1000,
+            g._ap_s, actor.preferred_username, page=1, per_page=1000,
         )
         followed_urls = {a.actor_url for a in following}
         return await render_template(
@@ -193,7 +239,7 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
     async def following_list():
         actor = _require_actor()
         actors, total = await services.federation.get_following(
-            g.s, actor.preferred_username,
+            g._ap_s, actor.preferred_username,
         )
         return await render_template(
             "social/following.html",
@@ -208,7 +254,7 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
         actor = _require_actor()
         page = request.args.get("page", 1, type=int)
         actors, total = await services.federation.get_following(
-            g.s, actor.preferred_username, page=page,
+            g._ap_s, actor.preferred_username, page=page,
         )
         return await render_template(
             "social/_actor_list_items.html",
@@ -228,7 +274,7 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
         from shared.models.federation import RemoteActor
         from sqlalchemy import select as sa_select
         remote = (
-            await g.s.execute(
+            await g._ap_s.execute(
                 sa_select(RemoteActor).where(RemoteActor.id == id)
             )
         ).scalar_one_or_none()
@@ -236,12 +282,12 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
             abort(404)
         from shared.services.federation_impl import _remote_actor_to_dto
         remote_dto = _remote_actor_to_dto(remote)
-        items = await services.federation.get_actor_timeline(g.s, id)
+        items = await services.federation.get_actor_timeline(g._ap_s, id)
         is_following = False
         if actor:
             from shared.models.federation import APFollowing
             existing = (
-                await g.s.execute(
+                await g._ap_s.execute(
                     sa_select(APFollowing).where(
                         APFollowing.actor_profile_id == actor.id,
                         APFollowing.remote_actor_id == id,
@@ -268,7 +314,7 @@ def create_ap_social_blueprint(app_name: str) -> Blueprint:
             except ValueError:
                 pass
         items = await services.federation.get_actor_timeline(
-            g.s, id, before=before,
+            g._ap_s, id, before=before,
         )
         return await render_template(
             "social/_timeline_items.html",