diff --git a/vehicle-data-platform/apps/api/internal/platform/handler_test.go b/vehicle-data-platform/apps/api/internal/platform/handler_test.go
index 99b5a07b..2e086c8f 100644
--- a/vehicle-data-platform/apps/api/internal/platform/handler_test.go
+++ b/vehicle-data-platform/apps/api/internal/platform/handler_test.go
@@ -236,3 +236,43 @@ func TestHandlerVehicleDataAPIsResolveVehicleKeyword(t *testing.T) {
 		})
 	}
 }
+
+func TestHandlerRawFramesPostAcceptsKeyword(t *testing.T) {
+	handler := NewHandler(NewService(NewMockStore()))
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodPost, "/api/history/raw-frames/query", strings.NewReader(`{"keyword":"川AHTWO1","limit":1}`))
+	handler.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status = %d body=%s", rec.Code, rec.Body.String())
+	}
+	var body struct {
+		Data struct {
+			Items []RawFrameRow `json:"items"`
+		} `json:"data"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
+		t.Fatalf("response JSON should decode: %v body=%s", err, rec.Body.String())
+	}
+	if len(body.Data.Items) != 1 || body.Data.Items[0].VIN != "LNXNEGRR7SR318212" {
+		t.Fatalf("raw POST should resolve keyword to VIN, got %+v body=%s", body.Data.Items, rec.Body.String())
+	}
+}
+
+func TestHandlerRawFramesKeepsUnresolvedKeywordEmpty(t *testing.T) {
+	handler := NewHandler(NewService(NewMockStore()))
+	rec := httptest.NewRecorder()
+	req := httptest.NewRequest(http.MethodGet, "/api/history/raw-frames?keyword=64646848247&limit=1", nil)
+	handler.ServeHTTP(rec, req)
+	if rec.Code != http.StatusOK {
+		t.Fatalf("status = %d body=%s", rec.Code, rec.Body.String())
+	}
+	var body struct {
+		Data Page[RawFrameRow] `json:"data"`
+	}
+	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
+		t.Fatalf("response JSON should decode: %v body=%s", err, rec.Body.String())
+	}
+	if body.Data.Total != 0 || len(body.Data.Items) != 0 {
+		t.Fatalf("unresolved keyword should not fabricate raw rows: %+v body=%s", body.Data, rec.Body.String())
+	}
+}
diff --git a/vehicle-data-platform/apps/api/internal/platform/mock_store.go b/vehicle-data-platform/apps/api/internal/platform/mock_store.go
index c7118aea..f5faff4c 100644
--- a/vehicle-data-platform/apps/api/internal/platform/mock_store.go
+++ b/vehicle-data-platform/apps/api/internal/platform/mock_store.go
@@ -218,16 +218,21 @@ func (m *MockStore) RawFrames(_ context.Context, query RawFrameQuery) (Page[RawF
 	if !query.IncludeFields && len(query.Fields) == 0 {
 		fields = nil
 	}
-	protocol := defaultString(query.Protocol, "GB32960")
-	vin := defaultString(query.VIN, "LB9A32A24R0LS1426")
 	rows := []RawFrameRow{
-		{ID: "raw-20260703-001", VIN: vin, Plate: "粤AG18312", Protocol: protocol, FrameType: "realtime", DeviceTime: "2026-07-03 20:12:06", ServerTime: "2026-07-03 20:12:06", RawSizeBytes: 430, ParsedFields: fields},
+		{ID: "raw-20260703-001", VIN: "LB9A32A24R0LS1426", Plate: "粤AG18312", Protocol: "GB32960", FrameType: "realtime", DeviceTime: "2026-07-03 20:12:06", ServerTime: "2026-07-03 20:12:06", RawSizeBytes: 430, ParsedFields: fields},
+		{ID: "raw-20260703-002", VIN: "LNXNEGRR7SR318212", Plate: "川AHTWO1", Protocol: "GB32960", FrameType: "realtime", DeviceTime: "2026-07-03 20:12:06", ServerTime: "2026-07-03 20:12:06", RawSizeBytes: 430, ParsedFields: fields},
+	}
+	if vin := strings.TrimSpace(query.VIN); vin != "" {
+		rows = keep(rows, func(row RawFrameRow) bool { return row.VIN == vin })
+	}
+	if protocol := strings.TrimSpace(query.Protocol); protocol != "" {
+		rows = keep(rows, func(row RawFrameRow) bool { return row.Protocol == protocol })
 	}
 	limit := query.Limit
 	if limit <= 0 {
 		limit = 100
 	}
-	return Page[RawFrameRow]{Items: rows, Total: len(rows), Limit: limit, Offset: query.Offset}, nil
+	return page(rows, url.Values{"limit": {strconv.Itoa(limit)}, "offset": {strconv.Itoa(query.Offset)}}), nil
 }
 
 func (m *MockStore) DailyMileage(_ context.Context, query url.Values) (Page[DailyMileageRow], error) {
diff --git a/vehicle-data-platform/docs/api-contract.md b/vehicle-data-platform/docs/api-contract.md
new file mode 100644
index 00000000..9bc1d606
--- /dev/null
+++ b/vehicle-data-platform/docs/api-contract.md
@@ -0,0 +1,105 @@
+# Vehicle Data Platform API Contract
+
+## Response Envelope
+
+All platform APIs return the same envelope:
+
+```json
+{
+  "data": {},
+  "traceId": "trace-20260704000000.000000",
+  "timestamp": 1783094400000
+}
+```
+
+Pagination uses:
+
+```json
+{
+  "items": [],
+  "total": 0,
+  "limit": 20,
+  "offset": 0
+}
+```
+
+## Vehicle Keyword
+
+The platform is vehicle-first. Query APIs should accept `keyword` as the user-facing vehicle selector.
+
+`keyword` may be:
+
+- VIN
+- plate
+- JT808 phone
+
+The BFF resolves `keyword` through vehicle identity data before querying realtime, history, RAW, or mileage data. `vin` remains accepted as a compatibility alias on data query APIs, but new UI and integrations should send `keyword`.
+
+If a keyword cannot be resolved to a VIN, data APIs must not fabricate a VIN. They should return empty result pages for vehicle data, while `/api/vehicles/detail` exposes `lookupResolved=false` and quality issues for follow-up binding work.
+
+## Core Query APIs
+
+### Vehicle Detail
+
+```http
+GET /api/vehicles/detail?keyword=粤AG18312
+```
+
+Returns one vehicle service view with identity, realtime summary, source coverage, history preview, RAW preview, mileage preview, and quality issues.
+
+### Realtime Vehicles
+
+```http
+GET /api/realtime/vehicles?keyword=粤AG18312&protocol=JT808&online=online&limit=50&offset=0
+```
+
+Returns VIN-level realtime rows. Protocol is a source filter, not a product boundary.
+
+### History Locations
+
+```http
+GET /api/history/locations?keyword=粤AG18312&protocol=JT808&dateFrom=2026-07-03%2000:00:00&dateTo=2026-07-03%2023:59:59&limit=20&offset=0
+```
+
+Returns historical location points from TDengine, enriched with plate where possible.
+
+### RAW Frames
+
+Short GET query:
+
+```http
+GET /api/history/raw-frames?keyword=粤AG18312&protocol=GB32960&limit=20&offset=0&includeFields=true
+```
+
+Large field-filter query:
+
+```http
+POST /api/history/raw-frames/query
+Content-Type: application/json
+
+{
+  "keyword": "粤AG18312",
+  "protocol": "GB32960",
+  "dateFrom": "2026-07-03 00:00:00",
+  "dateTo": "2026-07-03 23:59:59",
+  "fields": ["gb32960.vehicle.speed_kmh", "gb32960.vehicle.total_mileage_km"],
+  "includeFields": true,
+  "limit": 20,
+  "offset": 0
+}
+```
+
+Use POST when `fields` may be long. `parsedFields` is returned only when `includeFields=true` or specific `fields` are requested.
+
+### Mileage
+
+```http
+GET /api/mileage/daily?keyword=粤AG18312&protocol=JT808&dateFrom=2026-07-01&dateTo=2026-07-03&limit=20&offset=0
+GET /api/mileage/summary?keyword=粤AG18312&protocol=JT808&dateFrom=2026-07-01&dateTo=2026-07-03
+```
+
+Returns daily mileage rows and aggregate mileage summary.
+
+## Compatibility Rule
+
+Existing callers may still send `vin`. The BFF treats `vin` as a vehicle lookup value for compatibility, so `vin=粤AG18312` still resolves through identity binding. New code should use `keyword` to avoid implying the value is already a real VIN.