fix(core): tolerate missing done task mirrors on startup

packages/core/src/__tests__/store-create.test.ts

@@ -67,6 +67,19 @@ describe("TaskStore", () => {
     });
   });
 
+  describe("startup watch recovery", () => {
+    it("does not crash done-task backfill when a DB row has no task.json mirror", async () => {
+      const task = await store.createTask({ description: "done task with missing mirror" });
+      (store as unknown as { db: { prepare: (sql: string) => { run: (...args: unknown[]) => void } } }).db
+        .prepare(`UPDATE tasks SET "column" = ?, updatedAt = ? WHERE id = ?`)
+        .run("done", new Date().toISOString(), task.id);
+      await deleteTaskDir(task.id);
+
+      await expect(store.watch()).resolves.toBeUndefined();
+      await store.close();
+    });
+  });
+
   describe("breakIntoSubtasks task creation flag", () => {
     it("persists breakIntoSubtasks=true when explicitly requested", async () => {
       const task = await store.createTask({

packages/core/src/store.ts

@@ -11712,7 +11712,24 @@ ${TASK_UPSERT_SQL_ASSIGNMENTS}
         if (cachedTask.column !== "done") continue;
 
         const taskDir = this.taskDir(taskId);
-        const raw = await readFile(join(taskDir, "task.json"), "utf-8");
+        let raw: string;
+        try {
+          raw = await readFile(join(taskDir, "task.json"), "utf-8");
+        } catch (error) {
+          if ((error as NodeJS.ErrnoException)?.code === "ENOENT") {
+            /*
+             * FNXC:StartupRecovery 2026-06-23-05:02:
+             * A recovered or corrupt SQLite index can retain done-task rows whose legacy task.json mirror was already removed. Startup watch must not crash while running the one-time done-pause backfill; skip the missing mirror and keep the dashboard available so operators can inspect or repair the project.
+             */
+            storeLog.warn("Skipping done-task pause metadata backfill for missing task.json", {
+              phase: "watch:done-pause-backfill",
+              taskId,
+              taskJsonPath: join(taskDir, "task.json"),
+            });
+            continue;
+          }
+          throw error;
+        }
         const diskTask = JSON.parse(raw) as Task;
         if (!this.clearDoneTransientFields(diskTask)) continue;