diff --git a/CHANGELOG.md b/CHANGELOG.md
index bace2d9577..0673a0517f 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -327,6 +327,14 @@ This release closes that milestone with **181 merged pull requests**.
 
 ### Fixed
 
+- **events:** Run-scoped reads no longer return 500 on the JSONL backend for a
+  run ID it cannot use as a filename. `GET
+  /api/threads/{thread_id}/runs/{run_id}/events`, `.../messages`, and
+  `.../workspace-changes` pass the URL's run ID to the event store unchecked;
+  with `run_events.backend: jsonl` an ID such as `run.1` raised `ValueError`,
+  while the memory and database stores return an empty result. JSONL reads and
+  deletes now treat such an ID as an unknown run; writes still reject it.
+  ([#6070])
 - **scheduler:** Fixed-hour cron tasks no longer fire twice on the daylight-saving
   fall-back day. `croniter` returns both occurrences of an ambiguous wall-clock
   hour (the first with `fold=0`, the second with `fold=1`). For tasks where
@@ -6268,4 +6276,5 @@ with **180 merged pull requests** since the first 2.0 milestone tag.
 [#6015]: https://github.com/bytedance/deer-flow/pull/6015
 [#6066]: https://github.com/bytedance/deer-flow/pull/6066
 [#6069]: https://github.com/bytedance/deer-flow/pull/6069
+[#6070]: https://github.com/bytedance/deer-flow/pull/6070
 
diff --git a/CHANGELOG_zh.md b/CHANGELOG_zh.md
index b9046e9b9a..bc0c552602 100644
--- a/CHANGELOG_zh.md
+++ b/CHANGELOG_zh.md
@@ -332,6 +332,12 @@
 
 ### 修复
 
+- **事件：** 在 JSONL 后端上，按 run 读取时，若 run ID 无法用作文件名，不再返回
+  500。`GET /api/threads/{thread_id}/runs/{run_id}/events`、`.../messages` 与
+  `.../workspace-changes` 会把 URL 中的 run ID 原样传给事件存储；在
+  `run_events.backend: jsonl` 下，`run.1` 这类 ID 会抛出 `ValueError`，而内存与
+  数据库存储返回空结果。现在 JSONL 的读取与删除把这类 ID 视为不存在的 run，写入
+  仍会拒绝它。([#6070])
 - **调度器：** 固定小时的 cron 任务在夏令时回退（DST fall-back）当天不再重复运行两次。
   `croniter` 会返回模糊本地时间的两个实例（首个为 `fold=0`，第二个为 `fold=1`）。
   对于分和时字段不包含通配符的固定任务，现在会跳过第二个重复实例（`fold=1`），保持每天只运行一次
@@ -5316,3 +5322,4 @@ DeerFlow 2.0 是围绕"超级智能体"框架的彻底重写，核心包含子
 [#6015]: https://github.com/bytedance/deer-flow/pull/6015
 [#6066]: https://github.com/bytedance/deer-flow/pull/6066
 [#6069]: https://github.com/bytedance/deer-flow/pull/6069
+[#6070]: https://github.com/bytedance/deer-flow/pull/6070
diff --git a/backend/packages/harness/deerflow/runtime/AGENTS.md b/backend/packages/harness/deerflow/runtime/AGENTS.md
index 3a13d27f10..42bc4960f0 100644
--- a/backend/packages/harness/deerflow/runtime/AGENTS.md
+++ b/backend/packages/harness/deerflow/runtime/AGENTS.md
@@ -90,6 +90,8 @@ run reads, and sequence recovery split on physical newlines. Do not use
 part of the record. Preserve existing UTF-8 files and the writer format.
 `tests/test_jsonl_event_store_unicode.py` covers Unicode values, reopening,
 idempotent writes, LF/CRLF, blank lines, and malformed records.
+Reads and deletes treat a run ID writes reject as an unknown run (routes pass
+URL IDs through); writes still raise.
 
 **Targeted run-event attribution** (`runtime/events/store/`):
 `RunEventStore.find_latest_ai_message_run_ids()` has a complete-or-error
diff --git a/backend/packages/harness/deerflow/runtime/events/store/jsonl.py b/backend/packages/harness/deerflow/runtime/events/store/jsonl.py
index 76c3db829f..647410f689 100644
--- a/backend/packages/harness/deerflow/runtime/events/store/jsonl.py
+++ b/backend/packages/harness/deerflow/runtime/events/store/jsonl.py
@@ -94,10 +94,14 @@ class JsonlRunEventStore(RunEventStore):
             task = asyncio.create_task(operation(), name=f"jsonl-mutation:{thread_id}")
             return await self._await_owned_task(task)
 
+    @staticmethod
+    def _is_safe_id(value: str) -> bool:
+        return bool(value) and _SAFE_ID_PATTERN.match(value) is not None
+
     @staticmethod
     def _validate_id(value: str, label: str) -> str:
         """Validate that an ID is safe for use in filesystem paths."""
-        if not value or not _SAFE_ID_PATTERN.match(value):
+        if not JsonlRunEventStore._is_safe_id(value):
             raise ValueError(f"Invalid {label}: must be alphanumeric/dash/underscore, got {value!r}")
         return value
 
@@ -109,6 +113,18 @@ class JsonlRunEventStore(RunEventStore):
         self._validate_id(run_id, "run_id")
         return self._thread_dir(thread_id) / f"{run_id}.jsonl"
 
+    def _existing_run_file(self, thread_id: str, run_id: str) -> Path | None:
+        """Return the run's file, or ``None`` when the run has none.
+
+        Writes reject a run ID that is unsafe as a filename, so no file can hold
+        one; reads and deletes treat it as an unknown run, matching the memory
+        and database stores, rather than raising on a caller-supplied ID.
+        """
+        if not self._is_safe_id(run_id):
+            return None
+        path = self._run_file(thread_id, run_id)
+        return path if path.exists() else None
+
     def _next_seq(self, thread_id: str) -> int:
         self._seq_counters[thread_id] = self._seq_counters.get(thread_id, 0) + 1
         return self._seq_counters[thread_id]
@@ -159,8 +175,8 @@ class JsonlRunEventStore(RunEventStore):
 
     def _read_run_events(self, thread_id: str, run_id: str) -> list[dict]:
         """Read events for a specific run file (blocking I/O)."""
-        path = self._run_file(thread_id, run_id)
-        if not path.exists():
+        path = self._existing_run_file(thread_id, run_id)
+        if path is None:
             return []
         events = []
         for line in path.read_text(encoding="utf-8").strip().split("\n"):
@@ -180,8 +196,8 @@ class JsonlRunEventStore(RunEventStore):
                 f.unlink()
 
     def _delete_run_file(self, thread_id: str, run_id: str) -> None:
-        path = self._run_file(thread_id, run_id)
-        if path.exists():
+        path = self._existing_run_file(thread_id, run_id)
+        if path is not None:
             path.unlink()
 
     async def put(self, *, thread_id, run_id, event_type, category, content="", metadata=None, created_at=None):
diff --git a/backend/tests/test_run_event_store.py b/backend/tests/test_run_event_store.py
index 28383552f4..f56c8c426d 100644
--- a/backend/tests/test_run_event_store.py
+++ b/backend/tests/test_run_event_store.py
@@ -1285,6 +1285,44 @@ class TestJsonlRunEventStore:
         assert not (tmp_path / "jsonl" / "threads" / "t1" / "runs" / "r2.jsonl").exists()
         assert await s.count_messages("t1") == 1
 
+    @pytest.mark.anyio
+    @pytest.mark.parametrize("run_id", ["", "run.1", "a b", "../decoy"])
+    async def test_unsafe_run_id_reads_as_an_absent_run(self, tmp_path, run_id):
+        """A run ID no file can hold answers like the memory and DB stores' unknown run.
+
+        Run-scoped routes pass the URL's ``run_id`` straight through, so raising
+        here surfaced as a 500 instead of the empty result the other backends give.
+        """
+        from deerflow.runtime.events.store.jsonl import JsonlRunEventStore
+
+        s = JsonlRunEventStore(base_dir=tmp_path / "jsonl")
+        await s.put(thread_id="t1", run_id="r1", event_type="ai_message", category="message")
+        # ``../decoy`` would resolve here if the ID reached the filesystem.
+        decoy = tmp_path / "jsonl" / "threads" / "t1" / "decoy.jsonl"
+        decoy.write_text('{"seq": 9, "category": "message", "event_type": "ai_message"}\n', encoding="utf-8")
+
+        assert await s.list_events("t1", run_id) == []
+        assert await s.list_messages_by_run("t1", run_id) == []
+        assert await s.get_last_visible_ai_seq_by_run("t1", [run_id, "r1"]) == {"r1": 1}
+        assert await s.delete_by_run("t1", run_id) == 0
+        assert decoy.exists()
+        assert await s.count_messages("t1") == 1
+
+    @pytest.mark.anyio
+    async def test_unsafe_run_id_is_still_rejected_on_write(self, tmp_path):
+        from deerflow.runtime.events.store.jsonl import JsonlRunEventStore
+
+        s = JsonlRunEventStore(base_dir=tmp_path / "jsonl")
+        event = {"thread_id": "t1", "run_id": "run.1", "event_type": "ai_message", "category": "message"}
+
+        with pytest.raises(ValueError, match="Invalid run_id"):
+            await s.put(**event)
+        with pytest.raises(ValueError, match="Invalid run_id"):
+            await s.put_if_absent(**event)
+        with pytest.raises(ValueError, match="Invalid run_id"):
+            await s.put_batch([event])
+        assert await s.count_messages("t1") == 0
+
 
 class TestGetMessageSeqs:
     """Look up the thread-global seq of already-persisted messages by identity.
diff --git a/backend/tests/test_run_events_endpoint.py b/backend/tests/test_run_events_endpoint.py
index 3deb2e9bb2..10626cd168 100644
--- a/backend/tests/test_run_events_endpoint.py
+++ b/backend/tests/test_run_events_endpoint.py
@@ -111,6 +111,29 @@ async def test_list_run_events_redacts_historical_run_start_metadata():
     assert events[0] is not stored_row
 
 
+@pytest.mark.parametrize("run_id", ["run.1", "a%20b", "%2e%2e"])
+@pytest.mark.parametrize("route", ["events", "messages", "workspace-changes"])
+def test_run_scoped_reads_of_a_noncanonical_run_id_on_jsonl_match_the_memory_store(tmp_path, route, run_id):
+    """The URL's run_id reaches the event store unvalidated; JSONL must answer it as an unknown run, not a 500."""
+    from _router_auth_helpers import make_authed_test_app
+    from fastapi.testclient import TestClient
+
+    from app.gateway.routers import thread_runs
+    from deerflow.runtime.events.store.jsonl import JsonlRunEventStore
+
+    def get(store):
+        app = make_authed_test_app()
+        app.include_router(thread_runs.router)
+        app.state.run_event_store = store
+        with TestClient(app, raise_server_exceptions=False) as client:
+            return client.get(f"/api/threads/t1/runs/{run_id}/{route}")
+
+    jsonl = get(JsonlRunEventStore(tmp_path))
+    memory = get(MemoryRunEventStore())
+
+    assert (jsonl.status_code, jsonl.json()) == (200, memory.json())
+
+
 @pytest.mark.anyio
 async def test_effective_memory_flows_from_injection_to_the_existing_debug_api():
     """The production run-events route is the field-level consumer for M1.