fix: make Search watch admission recoverable (Closes #1295)

src/following_store.py

@@ -113,6 +113,27 @@ class FollowingStore:
                 )
         return snapshot
 
+    def preflight(self, login: str, raw_item: dict, watching: bool) -> dict:
+        """Validate a requested change and capacity without mutating the registry."""
+        login = self._login(login)
+        item = self._normalize_item(raw_item)
+        if not isinstance(watching, bool):
+            raise ValueError("watching is invalid")
+        if not watching:
+            return item
+        identity = self._identity(item)
+        with self._connect() as connection:
+            row = connection.execute(
+                "SELECT revision, items FROM following_issues WHERE login = ?", (login,)
+            ).fetchone()
+            current, _legacy = self._snapshot(row, login)
+        if (
+            len(current["items"]) >= self.limit
+            and not any(self._identity(candidate) == identity for candidate in current["items"])
+        ):
+            raise ValueError(f"following is limited to {self.limit} issues")
+        return item
+
     def set_watching(self, login: str, raw_item: dict, watching: bool) -> dict:
         login = self._login(login)
         item = self._normalize_item(raw_item)

src/gitea_proxy.py

@@ -608,6 +608,8 @@ async def work_preview(repository: str, kind: str, number: int) -> dict:
         "title": issue.get("title", "") if isinstance(issue.get("title"), str) else "",
         "body": issue.get("body", "") if isinstance(issue.get("body"), str) else "",
         "state": state,
+        "updated_at": issue.get("updated_at", "")
+        if isinstance(issue.get("updated_at"), str) else "",
         "author": author.get("login", "") if isinstance(author.get("login"), str) else "",
         "labels": [
             label["name"] for label in labels

src/main.py

@@ -3738,26 +3738,43 @@ async def mutate_global_search_preview_subscription(
         repository, preview = await _search_preview_subscription_target(owner, repo, number, kind)
         login = await _confirmed_login()
         store = _following_store()
-        await asyncio.to_thread(store.get, login)
+        following_item = {
+            "repository": repository,
+            "number": number,
+            "title": preview.get("title", ""),
+            "state": preview.get("state", ""),
+            "updated_at": preview.get("updated_at", ""),
+            "url": preview.get("url", ""),
+        }
+        await asyncio.to_thread(store.preflight, login, following_item, watching)
         result = await asyncio.wait_for(
             gitea_proxy.set_issue_subscription(repository, number, watching),
             timeout=ISSUE_ACTION_TIMEOUT_SECONDS,
         )
         if result.get("watching") is not watching:
             raise RuntimeError("Gitea did not confirm subscription state")
-        following = await asyncio.to_thread(
-            store.set_watching,
-            login,
-            {
-                "repository": repository,
-                "number": number,
-                "title": preview.get("title", ""),
-                "state": preview.get("state", ""),
-                "updated_at": preview.get("updated_at", ""),
-                "url": preview.get("url", ""),
-            },
-            watching,
-        )
+        try:
+            following = await asyncio.to_thread(
+                store.set_watching,
+                login,
+                following_item,
+                watching,
+            )
+        except Exception:
+            try:
+                compensated = await asyncio.wait_for(
+                    gitea_proxy.set_issue_subscription(repository, number, not watching),
+                    timeout=ISSUE_ACTION_TIMEOUT_SECONDS,
+                )
+            except Exception:
+                compensated = None
+            if not isinstance(compensated, dict) or compensated.get("watching") is not (not watching):
+                return JSONResponse({
+                    **result,
+                    "following_synced": False,
+                    "error": "Watching in Gitea, but Following could not sync. Retry this action.",
+                })
+            raise
     except HTTPException:
         raise
     except Exception: