修复 External 去背景重放与画布竞态

按原始请求指纹在可变预检前返回幂等任务
修正来源身份优先级与跨项目歧义校验
冻结并复验原位替换目标的完整媒体语义
修复 Python helper 原位替换请求并补正向路由测试

.codex/skills/genarrative-external-editor-api/SKILL.md

@@ -119,7 +119,7 @@ client.remove_background(
 )
 ```
 
-Background removal preserves the source pixel size. When `canvasSession` is used, pass the real `source_width` and `source_height`, or provide both `canvasWidth` and `canvasHeight`; the helper rejects missing dimensions instead of guessing a square placeholder. `assetKind` may only describe a static image and must match the authoritative source record. Prefer a project resource ID or asset ID when the same object key has multiple semantic registrations; for a raw object key outside in-place replacement, pass `sourceResourceId` to disambiguate. Without `canvasCompletion`, `targetLayerId` may replace only the layer that points to the same authoritative object as the source, and the server durably binds a raw object key to that target resource for Worker revalidation.
+Background removal preserves the source pixel size. For normal canvas placement with `canvasSession`, pass the real `source_width` and `source_height`, or provide both `canvasWidth` and `canvasHeight`; the helper rejects missing dimensions instead of guessing a square placeholder. `assetKind` may only describe a static image and must match the authoritative source record. Prefer a project resource ID or asset ID when the same object key has multiple semantic registrations; for a raw object key outside in-place replacement, pass `sourceResourceId` to disambiguate. Passing `targetLayerId` selects in-place replacement: the helper retains the session's project/library context but does not inject `canvasCompletion`, and it rejects an explicit `canvasCompletion` combined with `targetLayerId`. The target layer must point to the same authoritative object as the source, and the server durably binds a raw object key to that target resource for Worker revalidation.
 
 Helper convenience methods wait locally, but the server still uses short asynchronous submit/status requests. For durable caller-controlled orchestration, call `submit_generation`, persist its `operationId` and idempotency key, then call `get_generation` or `wait_for_generation`.
 

.codex/skills/genarrative-external-editor-api/references/requests-and-outputs.md

@@ -100,7 +100,7 @@ A minimal `canvasCompletion` is:
 
 `dialogId` is optional. The placeholder supplies canvas placement and completion coordinates; it is not a final media pixel-size constraint. For successful pixel-art snapping, the result layer uses the final logical-grid PNG dimensions even when they differ from the placeholder. Do not reconstruct canvas state from completion results. Reload the project and asset library when complete authoritative snapshots are needed.
 
-Background removal preserves the source image dimensions. The Python helper therefore requires the real `source_width` and `source_height` whenever `canvasSession` is used without an explicit `canvasWidth` plus `canvasHeight`; it never substitutes a square default. The request `assetKind` is optional, static-image only, and must equal the authoritative source type when one exists. Without `canvasCompletion`, an in-place `targetLayerId` must resolve to the same authoritative source object; a raw object key is bound to that target resource instead of relying on project-list order.
+Background removal preserves the source image dimensions. For normal canvas placement, the Python helper therefore requires the real `source_width` and `source_height` whenever `canvasSession` is used without an explicit `canvasWidth` plus `canvasHeight`; it never substitutes a square default. Passing `targetLayerId` instead selects in-place replacement, so the helper keeps the session's project/library fields without injecting `canvasCompletion` and rejects callers that explicitly combine both placement modes. The request `assetKind` is optional, static-image only, and must equal the authoritative source type when one exists. An in-place target must resolve to the same authoritative source object; a raw object key is bound to that target resource instead of relying on project-list order.
 
 Character animation accepts `assetFolderId` and `assetLabel` and persists the final transparent sequence directly. Its completed compact result includes the authoritative `assetKind="character-animation"` resource and asset with `imageSequenceFrames` and `imageSequenceDurationMs`. Use those records directly and never synthesize a duplicate asset from the first frame.
 

.codex/skills/genarrative-external-editor-api/scripts/genarrative_external_api.py

@@ -582,11 +582,16 @@ class GenarrativeExternalClient:
         session = fields.get("canvasSession")
         if session is None:
             session = fields.get("canvas_session")
+        target_layer_id = normalize_optional_text(fields.get("targetLayerId"))
+        if target_layer_id and fields.get("canvasCompletion") is not None:
+            raise GenarrativeApiError(
+                "targetLayerId and canvasCompletion are mutually exclusive for background removal"
+            )
         canvas_width = fields.get("canvasWidth")
         canvas_height = fields.get("canvasHeight")
         if (canvas_width is None) != (canvas_height is None):
             raise GenarrativeApiError("canvasWidth and canvasHeight must be provided together")
-        if session is not None and canvas_width is None:
+        if session is not None and canvas_width is None and not target_layer_id:
             if source_width is None or source_height is None:
                 raise GenarrativeApiError(
                     "remove_background requires source_width and source_height when canvasSession is used without canvasWidth/canvasHeight"
@@ -599,6 +604,8 @@ class GenarrativeExternalClient:
             source_width or 1,
             source_height or 1,
         )
+        if target_layer_id:
+            fields.pop("canvasCompletion", None)
         idempotency_key = fields.pop("idempotencyKey", None)
         return self.submit_and_wait_generation(
             "/api/external/v1/editor/images/background-removals",
@@ -838,6 +845,30 @@ def _self_test() -> None:
     assert calls[0]["body"]["canvasCompletion"]["placeholder"]["width"] == 720
     assert calls[0]["body"]["canvasCompletion"]["placeholder"]["height"] == 1280
     calls.clear()
+    client.remove_background(
+        "uploads/source.png",
+        canvasSession=session,
+        targetLayerId="layer-1",
+        assetLabel="原位去背景结果",
+    )
+    assert calls[0]["body"]["projectId"] == "proj-demo"
+    assert calls[0]["body"]["assetFolderId"] == "editor-asset-folder-demo"
+    assert calls[0]["body"]["assetLabel"] == "原位去背景结果"
+    assert calls[0]["body"]["targetLayerId"] == "layer-1"
+    assert "canvasCompletion" not in calls[0]["body"]
+    calls.clear()
+    try:
+        client.remove_background(
+            "uploads/source.png",
+            canvasSession=session,
+            targetLayerId="layer-1",
+            canvasCompletion={"title": "冲突完成指令"},
+        )
+    except GenarrativeApiError as error:
+        assert "targetLayerId and canvasCompletion are mutually exclusive" in str(error)
+    else:
+        raise AssertionError("background removal must reject conflicting canvas placement modes")
+    assert calls == []
     try:
         client.remove_background("uploads/source.png", canvasSession=session)
     except GenarrativeApiError as error:

server-rs/crates/api-server/src/editor_generation_queue.rs

@@ -6,7 +6,10 @@ use shared_contracts::external_generation::{
     ExternalGenerationJobStatus, ExternalGenerationJobStatusRecord,
 };
 use shared_kernel::{build_prefixed_uuid_id, offset_datetime_to_unix_micros};
-use spacetime_client::{ExternalGenerationJobEnqueueRecordInput, ExternalGenerationJobRecord};
+use spacetime_client::{
+    ExternalGenerationJobEnqueueRecordInput, ExternalGenerationJobGetRecordInput,
+    ExternalGenerationJobRecord, SpacetimeClientError,
+};
 
 use crate::{http_error::AppError, request_context::RequestContext, state::AppState};
 
@@ -30,6 +33,7 @@ const EDITOR_GENERATION_QUEUE_PROVIDER: &str = "editor-generation-worker";
 const MAX_EDITOR_GENERATION_JOB_PAYLOAD_BYTES: usize = 512 * 1024;
 const EXTERNAL_API_GENERATION_DEDUPE_PREFIX: &str = "external-api-generation";
 const EDITOR_API_REQUEST_GENERATION_DEDUPE_PREFIX: &str = "editor-api-request-generation";
+const EXTERNAL_API_REQUEST_FINGERPRINT_FIELD: &str = "_externalApiRequestFingerprint";
 pub(crate) const GAME_CREATOR_CLIENT_GENERATION_DEDUPE_PREFIX: &str =
     "game-creator-client-generation";
 pub(crate) const GAME_CREATOR_CLIENT_GENERATION_SOURCE: &str = "ai-game-creator-client";
@@ -89,6 +93,186 @@ fn build_editor_generation_dedupe_key(
     format!("{namespace}:{job_kind}:{:x}", hasher.finalize())
 }
 
+#[derive(Clone, Debug, PartialEq, Eq)]
+pub(crate) struct ExternalApiEditorGenerationRequestIdentity {
+    job_id: String,
+    dedupe_key: String,
+    request_fingerprint: String,
+}
+
+pub(crate) fn external_api_editor_generation_request_identity<T>(
+    owner_user_id: &str,
+    job_kind: &str,
+    payload: &T,
+    idempotency_key: &str,
+) -> Result<ExternalApiEditorGenerationRequestIdentity, AppError>
+where
+    T: Serialize,
+{
+    let payload = serde_json::to_value(payload).map_err(payload_serialization_error)?;
+    let canonical_payload = canonicalize_external_api_request_value(payload);
+    let canonical_payload =
+        serde_json::to_vec(&canonical_payload).map_err(payload_serialization_error)?;
+    let mut request_hasher = Sha256::new();
+    request_hasher.update(b"genarrative-external-api-request-v1\0");
+    request_hasher.update(canonical_payload);
+    let request_fingerprint = format!("{:x}", request_hasher.finalize());
+    let dedupe_key = build_editor_generation_dedupe_key(
+        EXTERNAL_API_GENERATION_DEDUPE_PREFIX,
+        owner_user_id,
+        job_kind,
+        idempotency_key,
+    );
+    let mut job_hasher = Sha256::new();
+    job_hasher.update(b"genarrative-external-api-operation-v1\0");
+    job_hasher.update(dedupe_key.as_bytes());
+    let job_digest = format!("{:x}", job_hasher.finalize());
+
+    Ok(ExternalApiEditorGenerationRequestIdentity {
+        job_id: format!("task-{}", &job_digest[..32]),
+        dedupe_key,
+        request_fingerprint,
+    })
+}
+
+fn canonicalize_external_api_request_value(value: Value) -> Value {
+    match value {
+        Value::Array(values) => Value::Array(
+            values
+                .into_iter()
+                .map(canonicalize_external_api_request_value)
+                .collect(),
+        ),
+        Value::Object(values) => {
+            let mut entries = values.into_iter().collect::<Vec<_>>();
+            entries.sort_by(|left, right| left.0.cmp(&right.0));
+            Value::Object(
+                entries
+                    .into_iter()
+                    .map(|(key, value)| (key, canonicalize_external_api_request_value(value)))
+                    .collect(),
+            )
+        }
+        other => other,
+    }
+}
+
+pub(crate) async fn find_external_api_editor_generation_replay(
+    state: &AppState,
+    owner_user_id: &str,
+    job_kind: &str,
+    identity: &ExternalApiEditorGenerationRequestIdentity,
+) -> Result<Option<ExternalGenerationJobRecord>, AppError> {
+    let job = match state
+        .spacetime_client()
+        .get_external_generation_job(ExternalGenerationJobGetRecordInput {
+            job_id: identity.job_id.clone(),
+            owner_user_id: owner_user_id.to_string(),
+        })
+        .await
+    {
+        Ok(job) => job,
+        Err(SpacetimeClientError::Procedure(message))
+            if message == "external_generation_job 不存在" =>
+        {
+            return Ok(None);
+        }
+        Err(error) => {
+            return Err(
+                AppError::from_status(StatusCode::BAD_GATEWAY).with_details(json!({
+                    "provider": EDITOR_GENERATION_QUEUE_PROVIDER,
+                    "message": format!("读取 External 幂等任务失败：{error}"),
+                })),
+            );
+        }
+    };
+    ensure_external_api_editor_generation_request_identity(job, owner_user_id, job_kind, identity)
+        .map(Some)
+}
+
+#[allow(clippy::too_many_arguments)]
+pub(crate) async fn enqueue_external_api_editor_generation_with_request_identity<T>(
+    state: &AppState,
+    owner_user_id: &str,
+    job_kind: &str,
+    source_entity_id: impl Into<String>,
+    request_label: impl Into<String>,
+    price_mud_points: u64,
+    payload: &T,
+    identity: &ExternalApiEditorGenerationRequestIdentity,
+) -> Result<ExternalGenerationJobRecord, AppError>
+where
+    T: Serialize,
+{
+    let request_payload_json =
+        serialize_external_api_editor_generation_payload_with_identity(payload, identity)?;
+    let job = enqueue_serialized_editor_generation_job_with_identity(
+        state,
+        owner_user_id,
+        job_kind,
+        source_entity_id,
+        request_label,
+        price_mud_points,
+        request_payload_json,
+        identity.job_id.clone(),
+        identity.dedupe_key.clone(),
+    )
+    .await?;
+    ensure_external_api_editor_generation_request_identity(job, owner_user_id, job_kind, identity)
+}
+
+fn ensure_external_api_editor_generation_request_identity(
+    job: ExternalGenerationJobRecord,
+    owner_user_id: &str,
+    job_kind: &str,
+    identity: &ExternalApiEditorGenerationRequestIdentity,
+) -> Result<ExternalGenerationJobRecord, AppError> {
+    let persisted_fingerprint = serde_json::from_str::<Value>(&job.request_payload_json)
+        .ok()
+        .and_then(|payload| {
+            payload
+                .get(EXTERNAL_API_REQUEST_FINGERPRINT_FIELD)
+                .and_then(Value::as_str)
+                .map(str::to_string)
+        });
+    if job.job_id == identity.job_id
+        && job.dedupe_key == identity.dedupe_key
+        && job.job_kind == job_kind
+        && job.owner_user_id == owner_user_id
+        && persisted_fingerprint.as_deref() == Some(identity.request_fingerprint.as_str())
+    {
+        return Ok(job);
+    }
+    Err(
+        AppError::from_status(StatusCode::CONFLICT).with_details(json!({
+            "provider": EDITOR_GENERATION_QUEUE_PROVIDER,
+            "message": "Idempotency-Key 已用于不同的生成请求，请复用原请求参数或更换幂等键。",
+        })),
+    )
+}
+
+fn serialize_external_api_editor_generation_payload_with_identity<T>(
+    payload: &T,
+    identity: &ExternalApiEditorGenerationRequestIdentity,
+) -> Result<String, AppError>
+where
+    T: Serialize + ?Sized,
+{
+    let mut payload = serde_json::to_value(payload).map_err(payload_serialization_error)?;
+    payload
+        .as_object_mut()
+        .ok_or_else(|| {
+            payload_serialization_error(serde_json::Error::io(std::io::Error::other(
+                "编辑器生成任务参数必须是 JSON object",
+            )))
+        })?
+        .insert(
+            EXTERNAL_API_REQUEST_FINGERPRINT_FIELD.to_string(),
+            Value::String(identity.request_fingerprint.clone()),
+        );
+    serialize_editor_generation_job_payload(&payload)
+}
+
 #[allow(clippy::too_many_arguments)]
 pub(crate) async fn enqueue_editor_generation_job_with_identity<T>(
     state: &AppState,
@@ -678,6 +862,163 @@ mod tests {
         );
     }
 
+    #[test]
+    fn external_background_removal_operation_id_is_key_scoped_and_body_fingerprint_is_separate() {
+        let first_body = json!({
+            "sourceImageSrc": "editor-upload/source-a.png",
+            "projectId": "project-1",
+        });
+        let reordered_same_body = json!({
+            "projectId": "project-1",
+            "sourceImageSrc": "editor-upload/source-a.png",
+        });
+        let changed_body = json!({
+            "sourceImageSrc": "editor-upload/source-b.png",
+            "projectId": "project-1",
+        });
+        let spoofed_client_source = json!({
+            "sourceImageSrc": "editor-upload/source-a.png",
+            "projectId": "project-1",
+            "generationInputs": {
+                "source": GAME_CREATOR_CLIENT_GENERATION_SOURCE,
+            },
+        });
+        let first = external_api_editor_generation_request_identity(
+            "user-1",
+            EDITOR_BACKGROUND_REMOVAL_JOB_KIND,
+            &first_body,
+            "stable-key",
+        )
+        .expect("request identity should build");
+        let reordered = external_api_editor_generation_request_identity(
+            "user-1",
+            EDITOR_BACKGROUND_REMOVAL_JOB_KIND,
+            &reordered_same_body,
+            "stable-key",
+        )
+        .expect("canonical request identity should build");
+        let changed = external_api_editor_generation_request_identity(
+            "user-1",
+            EDITOR_BACKGROUND_REMOVAL_JOB_KIND,
+            &changed_body,
+            "stable-key",
+        )
+        .expect("changed request identity should build");
+        let spoofed = external_api_editor_generation_request_identity(
+            "user-1",
+            EDITOR_BACKGROUND_REMOVAL_JOB_KIND,
+            &spoofed_client_source,
+            "stable-key",
+        )
+        .expect("external request identity must ignore payload-controlled namespaces");
+
+        assert_eq!(first.job_id, reordered.job_id);
+        assert_eq!(first.request_fingerprint, reordered.request_fingerprint);
+        assert_eq!(first.job_id, changed.job_id);
+        assert_ne!(first.request_fingerprint, changed.request_fingerprint);
+        assert_eq!(first.job_id, spoofed.job_id);
+        assert_eq!(first.dedupe_key, spoofed.dedupe_key);
+        assert_ne!(first.request_fingerprint, spoofed.request_fingerprint);
+        assert!(first.job_id.starts_with("task-"));
+        assert_ne!(
+            first.job_id,
+            external_api_editor_generation_request_identity(
+                "user-2",
+                EDITOR_BACKGROUND_REMOVAL_JOB_KIND,
+                &first_body,
+                "stable-key",
+            )
+            .unwrap()
+            .job_id,
+        );
+        assert_ne!(
+            first.job_id,
+            external_api_editor_generation_request_identity(
+                "user-1",
+                EDITOR_BACKGROUND_REMOVAL_JOB_KIND,
+                &first_body,
+                "other-key",
+            )
+            .unwrap()
+            .job_id,
+        );
+    }
+
+    #[test]
+    fn external_background_removal_replay_compares_raw_request_before_canonical_worker_payload() {
+        let raw_request = json!({
+            "sourceImageSrc": "resource-source",
+            "projectId": "project-output",
+        });
+        let identity = external_api_editor_generation_request_identity(
+            "user-1",
+            EDITOR_BACKGROUND_REMOVAL_JOB_KIND,
+            &raw_request,
+            "stable-key",
+        )
+        .expect("request identity should build");
+        let canonical_worker_payload = json!({
+            "sourceImageSrc": "resource-source",
+            "projectId": "project-output",
+            "sourceResourceId": "resource-source",
+            "assetKind": "character",
+        });
+        let persisted_payload = serialize_external_api_editor_generation_payload_with_identity(
+            &canonical_worker_payload,
+            &identity,
+        )
+        .expect("canonical worker payload should serialize with its private request fingerprint");
+        let mut job = queue_job_fixture("queued", None);
+        job.job_id = identity.job_id.clone();
+        job.dedupe_key = identity.dedupe_key.clone();
+        job.job_kind = EDITOR_BACKGROUND_REMOVAL_JOB_KIND.to_string();
+        job.request_payload_json = persisted_payload.clone();
+
+        assert!(
+            ensure_external_api_editor_generation_request_identity(
+                job.clone(),
+                "user-1",
+                EDITOR_BACKGROUND_REMOVAL_JOB_KIND,
+                &identity,
+            )
+            .is_ok(),
+            "same raw request must replay even when its canonical worker payload came from mutable preflight",
+        );
+
+        let changed_identity = external_api_editor_generation_request_identity(
+            "user-1",
+            EDITOR_BACKGROUND_REMOVAL_JOB_KIND,
+            &json!({
+                "sourceImageSrc": "resource-other",
+                "projectId": "project-output",
+            }),
+            "stable-key",
+        )
+        .expect("changed request identity should build");
+        let error = ensure_external_api_editor_generation_request_identity(
+            job,
+            "user-1",
+            EDITOR_BACKGROUND_REMOVAL_JOB_KIND,
+            &changed_identity,
+        )
+        .expect_err("same key with a different raw request must conflict");
+        assert_eq!(error.status_code(), StatusCode::CONFLICT);
+
+        let restored: crate::editor_project::EditorBackgroundRemovalRequest =
+            serde_json::from_str(&persisted_payload)
+                .expect("worker must ignore the private queue fingerprint envelope field");
+        let restored_payload =
+            serde_json::to_value(restored).expect("worker payload should encode");
+        assert_eq!(restored_payload["sourceImageSrc"], json!("resource-source"));
+        assert_eq!(restored_payload["assetKind"], json!("character"));
+        assert!(
+            restored_payload
+                .get(EXTERNAL_API_REQUEST_FINGERPRINT_FIELD)
+                .is_none(),
+            "private replay identity must not enter generationInputs or worker provenance",
+        );
+    }
+
     #[test]
     fn external_api_dedupe_key_preserves_legacy_hash_bytes() {
         let dedupe_key = build_editor_generation_dedupe_key(

server-rs/crates/api-server/src/external_editor_api.rs

@@ -858,6 +858,14 @@ pub async fn remove_external_editor_image_background(
     let Json(payload) = parse_external_generation_json_payload(&request_context, payload)?;
     let payload = EditorBackgroundRemovalRequest::from(payload);
     let project_id = payload.project_id.clone();
+    #[cfg(test)]
+    if let Some(job) = state.intercept_test_external_background_removal_enqueue(
+        principal.owner_user_id(),
+        payload.source_image_src.as_str(),
+        idempotency_key,
+    ) {
+        return Ok(external_generation_accepted_response(&request_context, job));
+    }
     let job = enqueue_editor_background_removal_for_owner(
         &state,
         &request_context,
@@ -2063,6 +2071,107 @@ mod tests {
         );
     }
 
+    #[tokio::test]
+    async fn external_background_removal_route_accepts_a_valid_submission_once() {
+        const OWNER_USER_ID: &str = "user-external-background-removal-success";
+        const SOURCE_IMAGE_SRC: &str = "editor-upload/background-removal-source.png";
+        const IDEMPOTENCY_KEY: &str = "background-removal-success-contract-test";
+        const OPERATION_ID: &str = "task-external-background-removal-success";
+
+        let state = AppState::new(crate::config::AppConfig::default())
+            .expect("external background removal success test state should build");
+        let mut queued_job = external_generation_job_fixture("pending");
+        queued_job.job_id = OPERATION_ID.to_string();
+        queued_job.job_kind = "editor_background_removal".to_string();
+        queued_job.owner_user_id = OWNER_USER_ID.to_string();
+        state.set_test_external_background_removal_enqueue(
+            OWNER_USER_ID,
+            SOURCE_IMAGE_SRC,
+            IDEMPOTENCY_KEY,
+            queued_job,
+        );
+        let request_body = json!({"sourceImageSrc": SOURCE_IMAGE_SRC}).to_string();
+
+        let without_scope = Router::new()
+            .route(
+                "/api/external/v1/editor/images/background-removals",
+                post(remove_external_editor_image_background),
+            )
+            .layer(Extension(request_context(false)))
+            .layer(Extension(ExternalApiPrincipal::for_test(
+                OWNER_USER_ID,
+                &[],
+            )))
+            .with_state(state.clone());
+        let forbidden = without_scope
+            .oneshot(
+                axum::http::Request::builder()
+                    .method("POST")
+                    .uri("/api/external/v1/editor/images/background-removals")
+                    .header("content-type", "application/json")
+                    .header(IDEMPOTENCY_KEY_HEADER, IDEMPOTENCY_KEY)
+                    .body(Body::from(request_body.clone()))
+                    .expect("external background removal forbidden request should build"),
+            )
+            .await
+            .expect("external background removal forbidden response should return");
+        assert_eq!(forbidden.status(), StatusCode::FORBIDDEN);
+        assert_eq!(state.test_editor_generation_enqueue_attempts(), 0);
+
+        let app = Router::new()
+            .route(
+                "/api/external/v1/editor/images/background-removals",
+                post(remove_external_editor_image_background),
+            )
+            .layer(Extension(request_context(false)))
+            .layer(Extension(ExternalApiPrincipal::for_test(
+                OWNER_USER_ID,
+                &[SCOPE_EDITOR_IMAGE_GENERATE],
+            )))
+            .with_state(state.clone());
+        let response = app
+            .oneshot(
+                axum::http::Request::builder()
+                    .method("POST")
+                    .uri("/api/external/v1/editor/images/background-removals")
+                    .header("content-type", "application/json")
+                    .header(IDEMPOTENCY_KEY_HEADER, IDEMPOTENCY_KEY)
+                    .body(Body::from(request_body))
+                    .expect("external background removal success request should build"),
+            )
+            .await
+            .expect("external background removal success response should return");
+
+        assert_eq!(response.status(), StatusCode::ACCEPTED);
+        assert_eq!(
+            response
+                .headers()
+                .get("location")
+                .and_then(|value| value.to_str().ok()),
+            Some("/api/external/v1/generations/task-external-background-removal-success")
+        );
+        let body = axum::body::to_bytes(response.into_body(), 64 * 1024)
+            .await
+            .expect("external background removal success body should collect");
+        let payload: Value = serde_json::from_slice(&body)
+            .expect("external background removal success body should be JSON");
+        assert_eq!(payload["operationId"], json!(OPERATION_ID));
+        assert_eq!(payload["status"], json!("queued"));
+        assert_eq!(
+            payload["statusUrl"],
+            json!(format!("/api/external/v1/generations/{OPERATION_ID}"))
+        );
+        assert_eq!(
+            payload["pollAfterMs"],
+            json!(EXTERNAL_GENERATION_POLL_AFTER_MS)
+        );
+        assert_eq!(
+            state.test_editor_generation_enqueue_attempts(),
+            1,
+            "valid External background removal should enqueue exactly once",
+        );
+    }
+
     #[tokio::test]
     async fn external_generic_image_generation_rejects_scene_asset_kind_before_queueing() {
         assert_external_generic_image_scene_bypass_is_rejected_before_queueing(

server-rs/crates/api-server/src/state.rs

@@ -27,6 +27,8 @@ use platform_llm::{LlmClient, LlmConfig, LlmError, LlmProvider, OpenAiChatTokenB
 use platform_matting::{MattingClient, MattingConfig};
 use platform_oss::{OssClient, OssConfig, OssError};
 use platform_wechat::{WechatClient, WechatConfig, pay::WechatPayClient};
+#[cfg(test)]
+use spacetime_client::ExternalGenerationJobRecord;
 use spacetime_client::{
     EditorGenerationModelPricingRecord, EditorGenerationPricingConfigRecord,
     EditorGenerationPricingConfigUpsertRecordInput, EditorGenerationPricingTierRecord,
@@ -128,6 +130,15 @@ impl BackpressureState {
 #[derive(Clone)]
 pub struct AppState(Arc<AppStateInner>);
 
+#[cfg(test)]
+#[derive(Clone)]
+struct TestExternalBackgroundRemovalEnqueue {
+    expected_owner_user_id: String,
+    expected_source_image_src: String,
+    expected_idempotency_key: String,
+    job: ExternalGenerationJobRecord,
+}
+
 impl fmt::Debug for AppState {
     fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
         f.debug_tuple("AppState").field(self.0.as_ref()).finish()
@@ -256,6 +267,9 @@ pub struct AppStateInner {
     test_editor_generation_enqueue_attempts: AtomicUsize,
     #[cfg(test)]
     test_fail_editor_generation_enqueue: AtomicBool,
+    #[cfg(test)]
+    test_external_background_removal_enqueue:
+        Arc<Mutex<Option<TestExternalBackgroundRemovalEnqueue>>>,
     oss_client: Option<OssClient>,
     #[cfg_attr(test, allow(dead_code))]
     auth_store: InMemoryAuthStore,
@@ -611,6 +625,8 @@ impl AppState {
             test_editor_generation_enqueue_attempts: AtomicUsize::new(0),
             #[cfg(test)]
             test_fail_editor_generation_enqueue: AtomicBool::new(false),
+            #[cfg(test)]
+            test_external_background_removal_enqueue: Arc::new(Mutex::new(None)),
             oss_client,
             auth_store,
             password_entry_service,
@@ -810,6 +826,46 @@ impl AppState {
             .load(Ordering::Acquire)
     }
 
+    #[cfg(test)]
+    pub(crate) fn set_test_external_background_removal_enqueue(
+        &self,
+        expected_owner_user_id: impl Into<String>,
+        expected_source_image_src: impl Into<String>,
+        expected_idempotency_key: impl Into<String>,
+        job: ExternalGenerationJobRecord,
+    ) {
+        *self
+            .test_external_background_removal_enqueue
+            .lock()
+            .expect("test external background removal enqueue should lock") =
+            Some(TestExternalBackgroundRemovalEnqueue {
+                expected_owner_user_id: expected_owner_user_id.into(),
+                expected_source_image_src: expected_source_image_src.into(),
+                expected_idempotency_key: expected_idempotency_key.into(),
+                job,
+            });
+    }
+
+    #[cfg(test)]
+    pub(crate) fn intercept_test_external_background_removal_enqueue(
+        &self,
+        owner_user_id: &str,
+        source_image_src: &str,
+        idempotency_key: &str,
+    ) -> Option<ExternalGenerationJobRecord> {
+        let fixture = self
+            .test_external_background_removal_enqueue
+            .lock()
+            .expect("test external background removal enqueue should lock")
+            .clone()?;
+        assert_eq!(owner_user_id, fixture.expected_owner_user_id);
+        assert_eq!(source_image_src, fixture.expected_source_image_src);
+        assert_eq!(idempotency_key, fixture.expected_idempotency_key);
+        self.test_editor_generation_enqueue_attempts
+            .fetch_add(1, Ordering::AcqRel);
+        Some(fixture.job)
+    }
+
     #[cfg(any())]
     pub async fn upsert_creation_entry_type_config(
         &self,