diff --git a/src/cold_display_guard/alarm_snapshots.py b/src/cold_display_guard/alarm_snapshots.py
index 604be68..179ccc5 100644
--- a/src/cold_display_guard/alarm_snapshots.py
+++ b/src/cold_display_guard/alarm_snapshots.py
@@ -30,6 +30,13 @@ class AlarmSnapshotSettings:
     encode_timeout_seconds: float = 10.0
 
 
+@dataclass(frozen=True, slots=True)
+class CalibrationOverlayRegion:
+    polygon: tuple[tuple[float, float], ...]
+    outline_rgb: tuple[int, int, int]
+    fill_rgb: tuple[int, int, int]
+
+
 class SnapshotUploadError(RuntimeError):
     pass
 
@@ -69,7 +76,8 @@ def capture_alert_snapshot(
     file_name = build_snapshot_file_name(alert_events[0], captured_at)
     object_key_hint = build_object_key_hint(settings.object_key_prefix, alert_events[0], captured_at, file_name)
     try:
-        image_bytes = (jpeg_encoder or encode_frame_to_jpeg)(frame, settings.encode_timeout_seconds)
+        annotated_frame = apply_calibration_overlay(frame, config)
+        image_bytes = (jpeg_encoder or encode_frame_to_jpeg)(annotated_frame, settings.encode_timeout_seconds)
         result = (uploader or upload_snapshot_bytes)(
             image_bytes,
             file_name=file_name,
@@ -91,6 +99,186 @@ def capture_alert_snapshot(
         }
 
 
+def apply_calibration_overlay(frame: Frame, config: dict[str, Any]) -> Frame:
+    regions = load_calibration_overlay_regions(config)
+    if not regions or frame.width <= 0 or frame.height <= 0:
+        return frame
+
+    rgb = bytearray(frame.rgb)
+    if len(rgb) != frame.width * frame.height * 3:
+        return frame
+
+    for region in regions:
+        polygon = normalized_polygon_to_pixels(region.polygon, frame.width, frame.height)
+        if len(polygon) < 3:
+            continue
+        fill_polygon(rgb, frame.width, frame.height, polygon, region.fill_rgb, alpha=0.24)
+        draw_polygon_outline(rgb, frame.width, frame.height, polygon, region.outline_rgb, alpha=0.85)
+    return Frame(width=frame.width, height=frame.height, rgb=bytes(rgb))
+
+
+def load_calibration_overlay_regions(config: dict[str, Any]) -> list[CalibrationOverlayRegion]:
+    regions: list[CalibrationOverlayRegion] = []
+    for zone in config.get("zones", []):
+        if not isinstance(zone, dict):
+            continue
+        polygon = normalize_overlay_polygon(zone.get("polygon", []))
+        if len(polygon) >= 3:
+            regions.append(
+                CalibrationOverlayRegion(
+                    polygon=polygon,
+                    outline_rgb=(255, 196, 0),
+                    fill_rgb=(255, 196, 0),
+                )
+            )
+
+    trash = config.get("trash", {})
+    if isinstance(trash, dict):
+        polygon = normalize_overlay_polygon(trash.get("roi", []))
+        if len(polygon) >= 3:
+            regions.append(
+                CalibrationOverlayRegion(
+                    polygon=polygon,
+                    outline_rgb=(255, 64, 64),
+                    fill_rgb=(255, 64, 64),
+                )
+            )
+    return regions
+
+
+def normalize_overlay_polygon(value: object) -> tuple[tuple[float, float], ...]:
+    points: list[tuple[float, float]] = []
+    if not isinstance(value, list | tuple):
+        return ()
+    for item in value:
+        if not isinstance(item, list | tuple) or len(item) != 2:
+            continue
+        try:
+            x = clamp_unit(float(item[0]))
+            y = clamp_unit(float(item[1]))
+        except (TypeError, ValueError):
+            continue
+        points.append((x, y))
+    return tuple(points)
+
+
+def normalized_polygon_to_pixels(
+    polygon: tuple[tuple[float, float], ...],
+    width: int,
+    height: int,
+) -> tuple[tuple[int, int], ...]:
+    max_x = max(0, width - 1)
+    max_y = max(0, height - 1)
+    return tuple((round(x * max_x), round(y * max_y)) for x, y in polygon)
+
+
+def fill_polygon(
+    rgb: bytearray,
+    width: int,
+    height: int,
+    polygon: tuple[tuple[int, int], ...],
+    color: tuple[int, int, int],
+    *,
+    alpha: float,
+) -> None:
+    min_x = max(0, min(point[0] for point in polygon))
+    max_x = min(width - 1, max(point[0] for point in polygon))
+    min_y = max(0, min(point[1] for point in polygon))
+    max_y = min(height - 1, max(point[1] for point in polygon))
+    for y in range(min_y, max_y + 1):
+        for x in range(min_x, max_x + 1):
+            if point_in_pixel_polygon(x, y, polygon):
+                blend_pixel(rgb, width, x, y, color, alpha)
+
+
+def draw_polygon_outline(
+    rgb: bytearray,
+    width: int,
+    height: int,
+    polygon: tuple[tuple[int, int], ...],
+    color: tuple[int, int, int],
+    *,
+    alpha: float,
+) -> None:
+    previous = polygon[-1]
+    for point in polygon:
+        draw_line(rgb, width, height, previous, point, color, alpha=alpha)
+        previous = point
+
+
+def draw_line(
+    rgb: bytearray,
+    width: int,
+    height: int,
+    start: tuple[int, int],
+    end: tuple[int, int],
+    color: tuple[int, int, int],
+    *,
+    alpha: float,
+) -> None:
+    x0, y0 = start
+    x1, y1 = end
+    dx = abs(x1 - x0)
+    dy = -abs(y1 - y0)
+    step_x = 1 if x0 < x1 else -1
+    step_y = 1 if y0 < y1 else -1
+    error = dx + dy
+    while True:
+        blend_pixel(rgb, width, x0, y0, color, alpha)
+        if x0 == x1 and y0 == y1:
+            break
+        twice_error = 2 * error
+        if twice_error >= dy:
+            error += dy
+            x0 += step_x
+        if twice_error <= dx:
+            error += dx
+            y0 += step_y
+
+
+def point_in_pixel_polygon(x: int, y: int, polygon: tuple[tuple[int, int], ...]) -> bool:
+    inside = False
+    px = float(x)
+    py = float(y)
+    previous_x, previous_y = polygon[-1]
+    for current_x, current_y in polygon:
+        if point_on_segment(px, py, previous_x, previous_y, current_x, current_y):
+            return True
+        crosses = (current_y > py) != (previous_y > py)
+        if crosses:
+            slope_x = (previous_x - current_x) * (py - current_y) / (previous_y - current_y) + current_x
+            if px < slope_x:
+                inside = not inside
+        previous_x, previous_y = current_x, current_y
+    return inside
+
+
+def point_on_segment(px: float, py: float, x0: int, y0: int, x1: int, y1: int) -> bool:
+    cross = (px - x0) * (y1 - y0) - (py - y0) * (x1 - x0)
+    if abs(cross) > 1e-9:
+        return False
+    return min(x0, x1) <= px <= max(x0, x1) and min(y0, y1) <= py <= max(y0, y1)
+
+
+def blend_pixel(
+    rgb: bytearray,
+    width: int,
+    x: int,
+    y: int,
+    color: tuple[int, int, int],
+    alpha: float,
+) -> None:
+    offset = (y * width + x) * 3
+    inverse = 1.0 - alpha
+    rgb[offset] = int(rgb[offset] * inverse + color[0] * alpha)
+    rgb[offset + 1] = int(rgb[offset + 1] * inverse + color[1] * alpha)
+    rgb[offset + 2] = int(rgb[offset + 2] * inverse + color[2] * alpha)
+
+
+def clamp_unit(value: float) -> float:
+    return min(1.0, max(0.0, value))
+
+
 def upload_snapshot_bytes(
     image_bytes: bytes,
     *,
diff --git a/tasks/todo.md b/tasks/todo.md
index 27ce5eb..807275f 100644
--- a/tasks/todo.md
+++ b/tasks/todo.md
@@ -64,3 +64,168 @@
   - `PYTHONPATH=src python3 -m unittest discover -s tests -v`
 - Deployed updated code to `xiaozheng@10.8.0.11` without overwriting the remote `config/example.toml`, rebuilt `cold-display-guard:dev`, and restarted only `cold-display-guard-api` plus `cold-display-guard-runtime`.
 - Natural post-deploy traffic did not arrive during the 2-minute observation window, so final runtime verification used the deployed container to build representative batch/case webhook payloads with the live remote config and confirmed `camera_ip = 192.168.3.4` plus all new downstream fields were present.
+
+## Current Task: Deploy To 192.168.5.103
+
+- [x] Inspect the existing deployment layout and active containers on `xiaozheng@192.168.5.103`.
+- [x] Verify the exact webhook route on that host before writing config.
+- [x] Sync the current project code to the remote deployment directory without overwriting the live RTSP and calibration config.
+- [x] Configure the remote webhook settings for the local `video-recognition` receiver.
+- [x] Rebuild and restart the remote API/runtime containers, then verify health and outbound webhook configuration.
+
+### Deployment Findings
+
+- Existing deployment path on `192.168.5.103` is `/home/xiaozheng/cold_display_guard`, not `~/apps/cold-display-guard/app`.
+- The host already runs `cold-display-guard-api`, `cold-display-guard-runtime`, and `cold-display-guard-web` on ports `19080` and `23000`.
+- The same host also runs `video-recognition`, and a direct probe to `http://127.0.0.1:8080/api/webhook/cold-display-guard` returned `200 OK`, so this is the verified webhook target for this environment.
+
+### Deployment Verification
+
+- From inside the running `cold-display-guard-api` container on `192.168.5.103`:
+  - `http://host.docker.internal:8080/api/webhook/cold-display-guard` failed DNS resolution.
+  - `http://172.17.0.1:8080/api/webhook/cold-display-guard` returned `200 OK`.
+  - `http://192.168.5.103:8080/api/webhook/cold-display-guard` returned `200 OK`.
+- The configured webhook target was set to `http://192.168.5.103:8080/api/webhook/cold-display-guard` for both `event_url` and `case_url`.
+- Remote config was enriched to include:
+  - `case_sink`
+  - `alarm_snapshot_upload`
+  - `webhook_retry_sink`
+  - `webhook_delivery_sink`
+  - `webhooks`
+- Code sync used `rsync` with `config/example.toml` excluded so the live RTSP URL and calibration polygons were preserved.
+- Remote rebuild/restart completed for `cold-display-guard-api` and `cold-display-guard-runtime`.
+- Verified after restart:
+  - `GET http://127.0.0.1:19080/api/manage/health` returned `status=ok`
+  - `GET http://127.0.0.1:19080/api/manage/config` showed `webhooks.enabled=true`
+  - `event_url` and `case_url` both active on `http://192.168.5.103:8080/api/webhook/cold-display-guard`
+  - `alarm_snapshot_upload.enabled=true`
+
+## Current Task: Alarm Snapshot Calibration Overlay
+
+**Goal:** Webhook-linked uploaded alarm snapshots should visually include the calibrated cold display zones and trash confirmation ROI from the current config.
+
+**Design:** Keep the existing runtime flow intact: capture current RTSP frame, process events, then upload an alarm snapshot only for warning/alarm events. Before JPEG encoding, build overlay regions from `[[zones]]` plus `[trash].roi`, clamp normalized polygon coordinates to the image bounds, draw a semi-transparent fill and visible outline directly onto a copied `Frame.rgb`, and pass that annotated frame to the existing encoder/uploader. Do not change `BatchEngine`, Webhook payload shape, OTA upload protocol, or management snapshot capture.
+
+- [x] Review task-relevant lessons and current dirty worktree.
+- [x] Inspect `alarm_snapshots.py`, `main.py`, config polygon shape, and existing tests.
+- [x] Write a failing unit test proving alert snapshot upload encodes an annotated frame when zones/trash ROI are configured.
+- [x] Write focused unit tests for polygon overlay behavior using a tiny RGB frame.
+- [x] Run targeted tests and confirm the new tests fail for the expected missing overlay behavior.
+- [x] Implement the smallest standard-library overlay helper in `src/cold_display_guard/alarm_snapshots.py`.
+- [x] Wire `capture_alert_snapshot` to apply configured overlays before JPEG encoding.
+- [x] Run targeted snapshot/runtime tests.
+- [x] Run the full Python test suite.
+
+### Review
+
+- Added `apply_calibration_overlay` in `src/cold_display_guard/alarm_snapshots.py` to draw configured food-zone polygons in yellow and the trash ROI in red onto a copied frame before JPEG encoding and OTA upload.
+- The overlay clamps normalized coordinates to image bounds, draws semi-transparent fills plus outlines, and leaves the original `Frame.rgb` unchanged for downstream runtime processing.
+- `capture_alert_snapshot` now encodes the annotated frame when warning/alarm events trigger snapshot upload; non-alert events and disabled upload behavior are unchanged.
+- Targeted verification passed:
+  - `PYTHONPATH=src python3 -m unittest tests/test_alarm_snapshots.py -v`
+  - `PYTHONPATH=src python3 -m unittest tests/test_main.py -v`
+- Full verification passed:
+  - `PYTHONPATH=src python3 -m unittest discover -s tests -v`
+
+## Current Task: Deploy Overlay Update To 10.8.0.23
+
+**Goal:** Deploy the alarm snapshot calibration overlay change to `xiaozheng@10.8.0.23` without overwriting live RTSP/calibration config or unrelated local changes.
+
+**Plan:** Inspect the remote deployment layout first, confirm which containers are active, sync only the runtime source file required for the overlay change, rebuild/restart the API/runtime services that use the Python image, and verify both service health and the deployed source code.
+
+- [x] Inspect remote deployment directory, Docker/Compose files, and active containers on `xiaozheng@10.8.0.23`.
+- [x] Confirm the remote config file remains present and is not overwritten.
+- [x] Sync `src/cold_display_guard/alarm_snapshots.py` to the remote deployment path.
+- [x] Rebuild and restart only the affected `cold-display-guard-api` and `cold-display-guard-runtime` services when Compose is available.
+- [x] Verify management API health after restart.
+- [x] Verify the deployed remote source contains `apply_calibration_overlay`.
+
+### Deployment Review
+
+- Remote deployment path confirmed as `/home/xiaozheng/cold_display_guard`.
+- Active services before deployment: `cold-display-guard-api`, `cold-display-guard-runtime`, and `cold-display-guard-web`.
+- Remote live `config/example.toml` was checked before and after deployment and was not overwritten.
+- Synced only `src/cold_display_guard/alarm_snapshots.py` to avoid deploying unrelated local `web/nginx.conf` changes.
+- Created a timestamped backup of the previous remote `alarm_snapshots.py` beside the source file before syncing.
+- Rebuilt `cold-display-guard:dev` with `docker compose --env-file deploy/cold-display-guard.env -f deploy/docker-compose.yml build cold-display-guard-api`.
+- Restarted only `cold-display-guard-api` and `cold-display-guard-runtime` with Compose; `cold-display-guard-web` remained untouched.
+- Verification passed:
+  - `curl http://127.0.0.1:19080/api/manage/health` returned `status=ok` and `runtime_status=running`.
+  - `docker exec cold-display-guard-api python3 -c ...` confirmed `apply_calibration_overlay` exists in the running image with signature `(frame, config) -> Frame`.
+  - API and runtime logs show normal startup after restart.
+
+## Current Task: Update Timing Parameters On 10.8.0.23
+
+**Goal:** Adjust the live timing settings on `xiaozheng@10.8.0.23` per operator request.
+
+**Applied mapping:** The current application has no separate pre-warning threshold. It supports `max_dwell_seconds` for the time alarm/overdue threshold and `trash_confirmation_seconds` for the disposal confirmation window before warning escalation. Applied `max_dwell_seconds = 120` and `trash_confirmation_seconds = 30`.
+
+- [x] Back up `/home/xiaozheng/cold_display_guard/config/example.toml`.
+- [x] Update `[thresholds].max_dwell_seconds` from `300` to `120`.
+- [x] Update `[thresholds].trash_confirmation_seconds` from `120` to `30`.
+- [x] Restart `cold-display-guard-api` and `cold-display-guard-runtime`.
+- [x] Verify `/api/manage/health`.
+- [x] Verify `/api/manage/config` returns `{"max_dwell_seconds": 120, "trash_confirmation_seconds": 30}`.
+
+### Timing Update Review
+
+- Remote config was edited in place after creating a timestamped backup.
+- `cold-display-guard-api` and `cold-display-guard-runtime` were explicitly restarted with Docker Compose.
+- `cold-display-guard-web` was not restarted.
+- Verification passed:
+  - `GET http://127.0.0.1:19080/api/manage/health` returned `status=ok` and `runtime_status=running`.
+  - `GET http://127.0.0.1:19080/api/manage/config` returned `max_dwell_seconds = 120` and `trash_confirmation_seconds = 30`.
+  - Container status showed `cold-display-guard-api` healthy and `cold-display-guard-runtime` running after restart.
+- Note: requested `预警时长 = 1min` is not independently configurable in the current codebase; supporting distinct pre-warning at 60 seconds and overdue at 120 seconds would require a code change.
+
+## Current Task: Pre-Warning Alarm Flow And Full Webhook/MQTT Chain
+
+**Goal:** Implement the requested camera-side timing flow, deploy it to `xiaozheng@10.8.0.23`, and verify the Webhook -> `video_recognition_local` -> MQTT -> `store_data_platform` chain.
+
+**Design:** Keep all timing decisions inside `cold_display_guard.BatchEngine`. Add separate thresholds for pre-warning, alarm, and alarm-removal timeout; emit explicit lifecycle events so downstream services do not infer camera-side timers. Keep `video_recognition_local` as a transparent Webhook/MQTT bridge, and update `store_data_platform` only where event names map to notifications, case types, and CRM penalty submission.
+
+- [x] Review task-relevant instructions, lessons, and dirty worktree.
+- [x] Inspect the current cold-display engine, case store, webhook payload, and tests.
+- [x] Inspect `video_recognition_local` cold-display Webhook receiver and MQTT publisher.
+- [x] Inspect `store_data_platform` cold-display MQTT consumer, notification mapping, and CRM submission trigger.
+- [x] Inspect `xiaozheng@10.8.0.23` active containers and deployment paths.
+- [x] Add failing cold-display engine/case/config/webhook tests for `time_pre_warning`, `pre_warning_handled`, `time_alarm`, and `alarm_removal_timeout`.
+- [x] Implement the camera-side state machine and config fields.
+- [x] Add/adjust `video_recognition_local` passthrough tests for the new event names.
+- [x] Add/adjust `store_data_platform` tests and mappings for new event semantics.
+- [x] Run local targeted and full relevant verification.
+- [x] Deploy changed services to `xiaozheng@10.8.0.23` without overwriting live RTSP/calibration secrets.
+- [x] Update the remote timing config to `pre_warning_seconds=60`, `max_dwell_seconds=120`, `alarm_removal_seconds=30`, `trash_confirmation_seconds=30`.
+- [x] Verify remote Webhook target reachability from the cold-display container to local `video-recognition`.
+- [x] Observe cold-display, video-recognition, MQTT, and platform logs; record the result.
+
+### Current Findings
+
+- `cold_display_guard` currently has only `max_dwell_seconds` and `trash_confirmation_seconds`; it cannot independently represent 1-minute pre-warning, 2-minute alarm, and 30-second alarm-removal timeout.
+- `video_recognition_local` receives `/api/webhook/cold-display-guard` payloads as generic JSON and forwards them to MQTT; new event names should remain transparent, but tests should lock this behavior.
+- `store_data_platform` currently treats `time_alarm` and `batch_pending_disposal` as warning notifications, and only `warning_escalated` triggers CRM penalty submission. This must change so `time_pre_warning` is the warning, `time_alarm` is the alert reminder, and `alarm_removal_timeout` triggers CRM submission.
+- On `10.8.0.23`, active containers include `cold-display-guard-*`, `video-recognition`, and `mosquitto`; `video-recognition` runs with host networking, while `cold-display-guard-api` runs on its Compose network.
+
+### Local Verification
+
+- Cold-display full Python suite passed: `PYTHONPATH=src python3 -m unittest discover -s tests -v` (`98` tests).
+- `video_recognition_local` cold-display focused tests passed: `go test ./internal/server ./internal/mqtt ./cmd -run 'TestColdDisplayGuard|Test.*ColdDisplayGuard' -count=1`.
+- `store_data_platform` display-cabinet service focused tests passed: `go test ./store_data/service -run 'Test.*StoreDisplayCabinet|TestResolveStoreDisplayCabinet.*|TestShouldSubmitStoreDisplayCabinetPenalty|TestBuildStoreDisplayCabinet.*' -count=1`.
+
+### Deployment Review
+
+- Synced only these cold-display source files to `xiaozheng@10.8.0.23:/home/xiaozheng/cold_display_guard/src/cold_display_guard/`: `models.py`, `config.py`, `engine.py`, `cases.py`, `webhooks.py`.
+- Backed up the remote source files and live `config/example.toml` before deployment.
+- Updated the live remote thresholds to `pre_warning_seconds=60`, `max_dwell_seconds=120`, `alarm_removal_seconds=30`, and `trash_confirmation_seconds=30`.
+- Updated the live remote Webhook target from the unreachable old host to `http://10.8.0.23:8080/api/webhook/cold-display-guard`.
+- Rebuilt `cold-display-guard:dev` and restarted only `cold-display-guard-api` and `cold-display-guard-runtime`.
+- Remote verification passed:
+  - `GET /api/manage/health` returned `status=ok` and `runtime_status=running`.
+  - `GET /api/manage/config` returned the four expected threshold values and the new Webhook target.
+  - Container-side synthetic engine run emitted `batch_started`, `time_pre_warning`, `time_alarm`, `alarm_removal_timeout`, then `batch_pending_disposal` plus `batch_discarded`.
+  - Natural runtime log emitted `alarm_removal_timeout` for `batch_000881` at `2026-06-15T11:52:20+08:00`.
+  - Webhook delivery for that event returned HTTP `200` from `video-recognition`.
+  - `video_recognition_local` result JSONL recorded both `alarm_removal_timeout` batch and case events.
+  - MQTT probe confirmed `video-recognition` published to `video/cold-display-guard/result/cold-display-guard` with `device_identifier=cold-display-guard`.
+- `store_data_platform` is not deployed on `10.8.0.23` under that repository name or as an identifiable container; platform handling changes were completed and verified in the local repository.
+- The cold-display retry queue has no pending entries; old `192.168.5.103` failures are already dead-letter history.
diff --git a/tests/test_alarm_snapshots.py b/tests/test_alarm_snapshots.py
index ad697ea..ad3b72e 100644
--- a/tests/test_alarm_snapshots.py
+++ b/tests/test_alarm_snapshots.py
@@ -3,6 +3,7 @@ from __future__ import annotations
 import unittest
 from datetime import datetime, timezone
 
+from cold_display_guard import alarm_snapshots
 from cold_display_guard.alarm_snapshots import (
     capture_alert_snapshot,
     load_alarm_snapshot_settings,
@@ -127,6 +128,75 @@ class AlarmSnapshotTests(unittest.TestCase):
         self.assertEqual(result["object_key"], "uploads/alarms/test.jpg")
         self.assertEqual(result["batch_ids"], ["batch_1"])
 
+    def test_calibration_overlay_draws_zones_and_trash_roi_without_mutating_source(self) -> None:
+        apply_overlay = getattr(alarm_snapshots, "apply_calibration_overlay", None)
+        self.assertTrue(callable(apply_overlay), "apply_calibration_overlay should be available")
+        frame = Frame(width=5, height=5, rgb=b"\x00\x00\x00" * 25)
+
+        annotated = apply_overlay(
+            frame,
+            {
+                "zones": [
+                    {
+                        "id": "1",
+                        "label": "区域 1",
+                        "polygon": [[0.2, 0.2], [0.8, 0.2], [0.8, 0.8], [0.2, 0.8]],
+                    }
+                ],
+                "trash": {"roi": [[0.0, 0.0], [0.4, 0.0], [0.0, 0.4]]},
+            },
+        )
+
+        self.assertEqual(frame.rgb, b"\x00\x00\x00" * 25)
+        self.assertNotEqual(annotated.rgb, frame.rgb)
+        self.assertNotEqual(annotated.pixel(1, 1), (0, 0, 0))
+        self.assertNotEqual(annotated.pixel(2, 2), (0, 0, 0))
+        self.assertNotEqual(annotated.pixel(0, 0), (0, 0, 0))
+
+    def test_capture_alert_snapshot_encodes_frame_with_configured_calibration_overlay(self) -> None:
+        encoded_frames: list[Frame] = []
+
+        def fake_encode(frame: Frame, timeout_seconds: float) -> bytes:
+            encoded_frames.append(frame)
+            return b"jpeg-bytes"
+
+        def fake_upload(
+            image_bytes: bytes,
+            *,
+            file_name: str,
+            object_key_hint: str,
+            settings,
+            post_json_request=None,
+            post_multipart_request=None,
+        ) -> dict[str, object]:
+            return {"status": "uploaded", "object_key": "uploads/alarms/overlay.jpg", "file_name": file_name}
+
+        source_frame = Frame(width=5, height=5, rgb=b"\x00\x00\x00" * 25)
+        result = capture_alert_snapshot(
+            source_frame,
+            [{"event": "time_alarm", "severity": "alarm", "batch_id": "batch_1", "camera_id": "cam_1", "zone_id": "1", "ts": "2026-06-09T09:00:00+00:00"}],
+            {
+                "alarm_snapshot_upload": {"enabled": True},
+                "zones": [
+                    {
+                        "id": "1",
+                        "label": "区域 1",
+                        "polygon": [[0.2, 0.2], [0.8, 0.2], [0.8, 0.8], [0.2, 0.8]],
+                    }
+                ],
+                "trash": {"roi": [[0.0, 0.0], [0.4, 0.0], [0.0, 0.4]]},
+            },
+            now=datetime(2026, 6, 9, 9, 0, tzinfo=UTC),
+            jpeg_encoder=fake_encode,
+            uploader=fake_upload,
+        )
+
+        self.assertEqual(result["status"], "uploaded")
+        self.assertEqual(source_frame.rgb, b"\x00\x00\x00" * 25)
+        self.assertEqual(len(encoded_frames), 1)
+        self.assertNotEqual(encoded_frames[0].rgb, source_frame.rgb)
+        self.assertNotEqual(encoded_frames[0].pixel(1, 1), (0, 0, 0))
+
 
 if __name__ == "__main__":
     unittest.main()