diff --git a/internal/tasktree/activities.ts b/internal/tasktree/activities.ts
index 5999bbb8..92580499 100644
--- a/internal/tasktree/activities.ts
+++ b/internal/tasktree/activities.ts
@@ -6,7 +6,6 @@ export function createTaskTreeActivities(store: TaskTreeStore) {
       const task = await store.getTask(input.taskId);
       if (!task) throw Object.assign(new Error("task was not found"), { code: "task_not_found" });
       const { report } = await store.writeReport({ taskId: task.id, title: "Temporal execution report", body: `Task ${task.title} completed by Temporal worker.`, status: "succeeded" });
-      await store.completeTask(task.id);
       return { taskId: task.id, reportId: report.id };
     }
   };
diff --git a/internal/tasktree/store.ts b/internal/tasktree/store.ts
index dd0e120a..b5e385f3 100644
--- a/internal/tasktree/store.ts
+++ b/internal/tasktree/store.ts
@@ -57,6 +57,17 @@ const schemaMigrations: SchemaMigration[] = [
     error_code TEXT NOT NULL DEFAULT '', error_message TEXT NOT NULL DEFAULT '',
     updated_at TIMESTAMPTZ NOT NULL DEFAULT now())`,
   ] },
+  { id: "tasktree-20260721-v4-report-completes-task", statements: [
+    `UPDATE tasktree_groups g SET updated_at=now()
+      WHERE EXISTS (
+        SELECT 1 FROM tasktree_tasks t
+        JOIN tasktree_execution_reports r ON r.task_id=t.id
+        WHERE t.group_id=g.id AND t.status <> 'completed'
+      )`,
+    `UPDATE tasktree_tasks t SET status='completed',updated_at=now()
+      WHERE t.status <> 'completed'
+        AND EXISTS (SELECT 1 FROM tasktree_execution_reports r WHERE r.task_id=t.id)`,
+  ] },
 ];
 const schemaMigrationIds = schemaMigrations.map((migration) => migration.id);
 const schemaAdvisoryLockKeys = [0x48574c42, 0x54545245] as const;
@@ -346,14 +357,14 @@ export class TaskTreeStore {
     const client = await this.pool.connect();
     try {
       await client.query("BEGIN");
+      const task = await client.query("SELECT group_id FROM tasktree_tasks WHERE id=$1 FOR UPDATE", [input.taskId]);
+      if (!task.rows[0]) throw domainError("task_not_found", "task was not found");
       const result = await client.query(
         "INSERT INTO tasktree_execution_reports (id,task_id,title,body,status) VALUES ($1,$2,$3,$4,$5) RETURNING *",
         [`tr_${randomUUID()}`, input.taskId, input.title, input.body, input.status ?? "succeeded"]
       );
-      await client.query(
-        "UPDATE tasktree_groups g SET updated_at=now() FROM tasktree_tasks t WHERE t.id=$1 AND g.id=t.group_id",
-        [input.taskId]
-      );
+      await client.query("UPDATE tasktree_tasks SET status='completed',updated_at=now() WHERE id=$1", [input.taskId]);
+      await client.query("UPDATE tasktree_groups SET updated_at=now() WHERE id=$1", [task.rows[0].group_id]);
       await client.query("COMMIT");
       return reportRow(result.rows[0]);
     } catch (error) {
@@ -376,29 +387,55 @@ export class TaskTreeStore {
     return result.rows[0] ? reportRow(result.rows[0]) : null;
   }
 
-  async writeReport(input: { taskId: string; title: string; body: string; status?: string }): Promise<{ report: ExecutionReport; mutation: boolean }> {
+  async writeReport(input: { taskId: string; title: string; body: string; status?: string }): Promise<{
+    report: ExecutionReport;
+    mutation: boolean;
+    task: TaskItem;
+    taskMutation: boolean;
+  }> {
     await this.ensureSchema();
-    const task = await this.getTask(input.taskId);
-    if (!task) throw domainError("task_not_found", "task was not found");
-    const current = await this.pool.query(
-      "SELECT * FROM tasktree_execution_reports WHERE task_id=$1 AND title=$2 ORDER BY created_at DESC,id LIMIT 1",
-      [input.taskId, input.title]
-    );
-    const status = input.status ?? "succeeded";
-    if (current.rows[0] && current.rows[0].body === input.body && current.rows[0].status === status) {
-      return { report: reportRow(current.rows[0]), mutation: false };
-    }
-    const result = current.rows[0]
-      ? await this.pool.query(
-        "UPDATE tasktree_execution_reports SET body=$2,status=$3,created_at=now() WHERE id=$1 RETURNING *",
-        [current.rows[0].id, input.body, status]
-      )
-      : await this.pool.query(
-        "INSERT INTO tasktree_execution_reports (id,task_id,title,body,status) VALUES ($1,$2,$3,$4,$5) RETURNING *",
-        [`tr_${randomUUID()}`, input.taskId, input.title, input.body, status]
+    const client = await this.pool.connect();
+    try {
+      await client.query("BEGIN");
+      const taskResult = await client.query("SELECT * FROM tasktree_tasks WHERE id=$1 FOR UPDATE", [input.taskId]);
+      if (!taskResult.rows[0]) throw domainError("task_not_found", "task was not found");
+      const current = await client.query(
+        "SELECT * FROM tasktree_execution_reports WHERE task_id=$1 AND title=$2 ORDER BY created_at DESC,id LIMIT 1",
+        [input.taskId, input.title]
       );
-    await this.pool.query("UPDATE tasktree_groups SET updated_at=now() WHERE id=$1", [task.groupId]);
-    return { report: reportRow(result.rows[0]), mutation: true };
+      const status = input.status ?? "succeeded";
+      const mutation = !current.rows[0] || current.rows[0].body !== input.body || current.rows[0].status !== status;
+      const reportResult = !mutation
+        ? current
+        : current.rows[0]
+          ? await client.query(
+            "UPDATE tasktree_execution_reports SET body=$2,status=$3,created_at=now() WHERE id=$1 RETURNING *",
+            [current.rows[0].id, input.body, status]
+          )
+          : await client.query(
+            "INSERT INTO tasktree_execution_reports (id,task_id,title,body,status) VALUES ($1,$2,$3,$4,$5) RETURNING *",
+            [`tr_${randomUUID()}`, input.taskId, input.title, input.body, status]
+          );
+      const taskMutation = taskResult.rows[0].status !== "completed";
+      const completedTask = taskMutation
+        ? await client.query("UPDATE tasktree_tasks SET status='completed',updated_at=now() WHERE id=$1 RETURNING *", [input.taskId])
+        : taskResult;
+      if (mutation || taskMutation) {
+        await client.query("UPDATE tasktree_groups SET updated_at=now() WHERE id=$1", [taskResult.rows[0].group_id]);
+      }
+      await client.query("COMMIT");
+      return {
+        report: reportRow(reportResult.rows[0]),
+        mutation,
+        task: taskRow(completedTask.rows[0]),
+        taskMutation,
+      };
+    } catch (error) {
+      await client.query("ROLLBACK").catch(() => {});
+      throw error;
+    } finally {
+      client.release();
+    }
   }
 
   async importMdtodo(plan: MdtodoImportPlan) {
@@ -422,7 +459,8 @@ export class TaskTreeStore {
         await client.query(
           `INSERT INTO tasktree_tasks (id,group_id,parent_id,kind,title,description,status,start_at,due_at,sort_order)
            VALUES ($1,$2,$3,$4,$5,$6,$7,$8,$9,$10)`,
-          [taskId, groupId, parentId, kind, task.title, task.description, task.status, task.startAt, task.dueAt, index]
+          [taskId, groupId, parentId, kind, task.title, task.description,
+            task.reports.length > 0 ? "completed" : task.status, task.startAt, task.dueAt, index]
         );
         for (const report of task.reports) {
           await client.query(
diff --git a/internal/tasktree/tasktree.test.ts b/internal/tasktree/tasktree.test.ts
index c2108156..99f4b7d0 100644
--- a/internal/tasktree/tasktree.test.ts
+++ b/internal/tasktree/tasktree.test.ts
@@ -166,11 +166,20 @@ test("native PostgreSQL store exposes overview and three task levels", async ()
       (error: any) => error?.code === "execution_report_required"
     );
     const firstReport = await store.writeReport({ taskId: task.id, title: "Execution", body: "passed" });
+    assert.equal(firstReport.task.status, "completed");
+    assert.equal(firstReport.taskMutation, true);
     const repeatedReport = await store.writeReport({ taskId: task.id, title: "Execution", body: "passed" });
+    assert.equal(repeatedReport.taskMutation, false);
+    await store.updateTask(task.id, { status: "blocked" });
+    const correctedReport = await store.writeReport({ taskId: task.id, title: "Execution", body: "passed" });
+    assert.equal(correctedReport.mutation, false);
+    assert.equal(correctedReport.taskMutation, true);
+    assert.equal(correctedReport.task.status, "completed");
     const changedReport = await store.writeReport({ taskId: task.id, title: "Execution", body: "passed with evidence" });
     assert.equal(firstReport.mutation, true);
     assert.equal(repeatedReport.mutation, false);
     assert.equal(changedReport.mutation, true);
+    assert.equal(changedReport.taskMutation, false);
     assert.equal(firstReport.report.id, repeatedReport.report.id);
     assert.equal(firstReport.report.id, changedReport.report.id);
     assert.equal((await store.completeTask(task.id))?.status, "completed");