Add generation harness runtime

backend/app/services/harness/__init__.py

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+"""Generation harness runtime support."""
+

backend/app/services/harness/artifacts.py

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+"""Artifact result types for generation harness workflows."""
+
+from dataclasses import dataclass
+from typing import Literal
+
+from app.services.story_status import StoryAssetStatus
+
+AssetCompletionKind = Literal["cover_image", "storybook_images", "audio"]
+
+
+@dataclass(frozen=True)
+class AssetCompletionResult:
+    """Service-level result for a generated asset completion attempt."""
+
+    asset: AssetCompletionKind
+    status: StoryAssetStatus
+    value: str | bytes | None = None
+    error: str | None = None
+    blocks_main_result: bool = False
+
+    @property
+    def succeeded(self) -> bool:
+        """Whether the asset reached a usable ready state."""
+
+        return self.status == StoryAssetStatus.READY and self.error is None
+
+
+def asset_result_metadata(result: AssetCompletionResult) -> dict:
+    """Build JSON-safe metadata for asset workflow events."""
+
+    return {
+        "asset": result.asset,
+        "status": result.status.value,
+        "error": result.error,
+        "blocks_main_result": result.blocks_main_result,
+    }
+

backend/app/services/harness/asset_workflows.py

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+"""Artifact completion workflows for the generation harness runtime."""
+
+from collections.abc import Awaitable, Callable
+
+from fastapi import HTTPException
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.core.logging import get_logger
+from app.db.models import Story
+from app.services.harness.artifacts import AssetCompletionResult, asset_result_metadata
+from app.services.harness.control import ExecutionControl
+from app.services.harness.trace import TraceRecorder
+from app.services.story_status import StoryAssetStatus, sync_story_status
+
+logger = get_logger(__name__)
+
+ImageGenerator = Callable[..., Awaitable[str]]
+TTSGenerator = Callable[..., Awaitable[bytes]]
+AudioCacheExists = Callable[[str], bool]
+AudioCacheReader = Callable[[str], bytes]
+AudioCacheWriter = Callable[[int, bytes], str]
+
+
+async def complete_cover_image_asset(
+    story: Story,
+    db: AsyncSession,
+    *,
+    generate_image_func: ImageGenerator,
+    raise_on_failure: bool = False,
+    last_error_prefix: str | None = None,
+    log_event: str = "cover_asset_generation_failed",
+    job=None,
+) -> AssetCompletionResult:
+    """Generate or retry a text story cover through one asset workflow."""
+
+    if not story.cover_prompt:
+        raise HTTPException(status_code=400, detail="Story has no cover prompt")
+
+    sync_story_status(story, image_status=StoryAssetStatus.GENERATING)
+    await db.commit()
+    await ExecutionControl(db).stop_if_cancel_requested(job=job, story=story)
+    await TraceRecorder(db).record_step(
+        job=job,
+        story_id=story.id,
+        event_type="cover_image_started",
+        status="running",
+        message="Cover image generation started.",
+        metadata={"asset": "image", "cover_prompt_present": True},
+    )
+
+    try:
+        await ExecutionControl(db).stop_if_cancel_requested(job=job, story=story)
+        image_url = await generate_image_func(
+            story.cover_prompt,
+            db=db,
+            user_id=story.user_id,
+            generation_job=job,
+            story_id=story.id,
+        )
+        story.image_url = image_url
+        sync_story_status(story, image_status=StoryAssetStatus.READY)
+        await db.commit()
+        result = AssetCompletionResult(
+            asset="cover_image",
+            status=StoryAssetStatus.READY,
+            value=image_url,
+            blocks_main_result=raise_on_failure,
+        )
+        await TraceRecorder(db).record_step(
+            job=job,
+            story_id=story.id,
+            event_type="cover_image_succeeded",
+            status="succeeded",
+            message="Cover image was generated.",
+            metadata=asset_result_metadata(result),
+        )
+        return result
+    except Exception as exc:
+        provider_error = str(exc)
+        last_error = (
+            f"{last_error_prefix}: {provider_error}"
+            if last_error_prefix
+            else provider_error
+        )
+        sync_story_status(
+            story,
+            image_status=StoryAssetStatus.FAILED,
+            last_error=last_error,
+        )
+        await db.commit()
+        logger.warning(log_event, story_id=story.id, error=provider_error)
+
+        result = AssetCompletionResult(
+            asset="cover_image",
+            status=StoryAssetStatus.FAILED,
+            error=provider_error,
+            blocks_main_result=raise_on_failure,
+        )
+        await TraceRecorder(db).record_step(
+            job=job,
+            story_id=story.id,
+            event_type="cover_image_failed",
+            status="failed",
+            message="Cover image generation failed.",
+            metadata=asset_result_metadata(result),
+        )
+        if raise_on_failure:
+            raise HTTPException(
+                status_code=500,
+                detail=f"Image generation failed: {provider_error}",
+            ) from exc
+
+        return result
+
+
+async def read_cached_audio_asset(
+    story: Story,
+    db: AsyncSession,
+    *,
+    audio_cache_exists_func: AudioCacheExists,
+    read_audio_cache_func: AudioCacheReader,
+) -> bytes | None:
+    """Read cached audio or repair stale audio cache metadata."""
+
+    if story.audio_path and audio_cache_exists_func(story.audio_path):
+        if story.audio_status != StoryAssetStatus.READY.value:
+            sync_story_status(story, audio_status=StoryAssetStatus.READY)
+            await db.commit()
+        return read_audio_cache_func(story.audio_path)
+
+    if story.audio_path and not audio_cache_exists_func(story.audio_path):
+        logger.warning(
+            "story_audio_cache_missing",
+            story_id=story.id,
+            audio_path=story.audio_path,
+        )
+        story.audio_path = None
+        if story.audio_status == StoryAssetStatus.READY.value:
+            sync_story_status(story, audio_status=StoryAssetStatus.NOT_REQUESTED)
+            await db.commit()
+
+    return None
+
+
+async def complete_audio_asset(
+    story: Story,
+    db: AsyncSession,
+    *,
+    text_to_speech_func: TTSGenerator,
+    audio_cache_exists_func: AudioCacheExists,
+    read_audio_cache_func: AudioCacheReader,
+    write_story_audio_cache_func: AudioCacheWriter,
+    raise_on_failure: bool = True,
+    job=None,
+) -> AssetCompletionResult:
+    """Complete TTS audio generation through one asset workflow."""
+
+    if not story.story_text:
+        raise HTTPException(status_code=400, detail="Story has no text")
+
+    cached_audio = await read_cached_audio_asset(
+        story,
+        db,
+        audio_cache_exists_func=audio_cache_exists_func,
+        read_audio_cache_func=read_audio_cache_func,
+    )
+    if cached_audio is not None:
+        result = AssetCompletionResult(
+            asset="audio",
+            status=StoryAssetStatus.READY,
+            value=cached_audio,
+            blocks_main_result=raise_on_failure,
+        )
+        await TraceRecorder(db).record_step(
+            job=job,
+            story_id=story.id,
+            event_type="audio_cache_hit",
+            status="succeeded",
+            message="Cached story audio was reused.",
+            metadata=asset_result_metadata(result),
+        )
+        return result
+
+    sync_story_status(story, audio_status=StoryAssetStatus.GENERATING)
+    await db.commit()
+    await ExecutionControl(db).stop_if_cancel_requested(job=job, story=story)
+    await TraceRecorder(db).record_step(
+        job=job,
+        story_id=story.id,
+        event_type="audio_started",
+        status="running",
+        message="Story audio generation started.",
+        metadata={"asset": "audio"},
+    )
+
+    try:
+        await ExecutionControl(db).stop_if_cancel_requested(job=job, story=story)
+        audio_data = await text_to_speech_func(
+            story.story_text,
+            db=db,
+            user_id=story.user_id,
+            generation_job=job,
+            story_id=story.id,
+        )
+        story.audio_path = write_story_audio_cache_func(story.id, audio_data)
+        sync_story_status(
+            story,
+            audio_status=StoryAssetStatus.READY,
+        )
+        await db.commit()
+        result = AssetCompletionResult(
+            asset="audio",
+            status=StoryAssetStatus.READY,
+            value=audio_data,
+            blocks_main_result=raise_on_failure,
+        )
+        await TraceRecorder(db).record_step(
+            job=job,
+            story_id=story.id,
+            event_type="audio_succeeded",
+            status="succeeded",
+            message="Story audio was generated and cached.",
+            metadata=asset_result_metadata(result),
+        )
+        return result
+    except Exception as exc:
+        provider_error = str(exc)
+        story.audio_path = None
+        sync_story_status(
+            story,
+            audio_status=StoryAssetStatus.FAILED,
+            last_error=provider_error,
+        )
+        await db.commit()
+        logger.error("audio_generation_failed", story_id=story.id, error=provider_error)
+
+        result = AssetCompletionResult(
+            asset="audio",
+            status=StoryAssetStatus.FAILED,
+            error=provider_error,
+            blocks_main_result=raise_on_failure,
+        )
+        await TraceRecorder(db).record_step(
+            job=job,
+            story_id=story.id,
+            event_type="audio_failed",
+            status="failed",
+            message="Story audio generation failed.",
+            metadata=asset_result_metadata(result),
+        )
+        if raise_on_failure:
+            raise HTTPException(
+                status_code=500,
+                detail=f"Audio generation failed: {provider_error}",
+            ) from exc
+
+        return result
+
+
+def get_storybook_pages_data(story: Story) -> list[dict]:
+    """Return mutable storybook page data from the persisted JSON field."""
+
+    return [dict(page) for page in story.pages or [] if isinstance(page, dict)]
+
+
+def build_storybook_error_message(
+    *,
+    cover_failed: bool,
+    failed_pages: list[int],
+) -> str | None:
+    """Summarize storybook image generation errors for the latest attempt."""
+
+    parts: list[str] = []
+    if cover_failed:
+        parts.append("封面生成失败")
+    if failed_pages:
+        pages = "、".join(str(page) for page in sorted(failed_pages))
+        parts.append(f"第 {pages} 页插图生成失败")
+    return "；".join(parts) if parts else None
+
+
+def resolve_storybook_image_status(
+    *,
+    generate_images: bool,
+    cover_prompt: str | None,
+    cover_url: str | None,
+    pages_data: list[dict],
+) -> StoryAssetStatus:
+    """Resolve the persisted image status for a storybook."""
+
+    if not generate_images:
+        return StoryAssetStatus.NOT_REQUESTED
+
+    expected_assets = 0
+    ready_assets = 0
+
+    if cover_prompt or cover_url:
+        expected_assets += 1
+    if cover_url:
+        ready_assets += 1
+
+    for page in pages_data:
+        if not page.get("image_prompt") and not page.get("image_url"):
+            continue
+        expected_assets += 1
+        if page.get("image_url"):
+            ready_assets += 1
+
+    if expected_assets == 0:
+        return StoryAssetStatus.NOT_REQUESTED
+
+    if ready_assets == expected_assets:
+        return StoryAssetStatus.READY
+
+    return StoryAssetStatus.FAILED
+
+
+async def complete_storybook_image_assets(
+    story: Story,
+    db: AsyncSession,
+    *,
+    generate_image_func: ImageGenerator,
+    job=None,
+) -> AssetCompletionResult:
+    """Complete missing cover/page images for a persisted storybook."""
+
+    pages_data = get_storybook_pages_data(story)
+    has_image_prompt = bool(story.cover_prompt) or any(
+        page.get("image_prompt") for page in pages_data
+    )
+    if not has_image_prompt:
+        raise HTTPException(status_code=400, detail="Storybook has no image prompts")
+
+    sync_story_status(story, image_status=StoryAssetStatus.GENERATING)
+    await db.commit()
+    await ExecutionControl(db).stop_if_cancel_requested(job=job, story=story)
+    await TraceRecorder(db).record_step(
+        job=job,
+        story_id=story.id,
+        event_type="storybook_images_started",
+        status="running",
+        message="Storybook missing image completion started.",
+        metadata={"asset": "image"},
+    )
+
+    cover_failed = False
+    failed_pages: list[int] = []
+    completed_pages: list[int] = []
+
+    if story.cover_prompt and not story.image_url:
+        await ExecutionControl(db).stop_if_cancel_requested(job=job, story=story)
+        try:
+            story.image_url = await generate_image_func(
+                story.cover_prompt,
+                db=db,
+                user_id=story.user_id,
+                generation_job=job,
+                story_id=story.id,
+            )
+            await TraceRecorder(db).record_step(
+                job=job,
+                story_id=story.id,
+                event_type="storybook_cover_image_succeeded",
+                status="succeeded",
+                message="Storybook cover image was generated.",
+                metadata={"asset": "image", "scope": "cover"},
+            )
+        except Exception as exc:
+            cover_failed = True
+            logger.warning(
+                "storybook_cover_asset_completion_failed",
+                story_id=story.id,
+                error=str(exc),
+            )
+            await TraceRecorder(db).record_step(
+                job=job,
+                story_id=story.id,
+                event_type="storybook_cover_image_failed",
+                status="failed",
+                message="Storybook cover image generation failed.",
+                metadata={"asset": "image", "scope": "cover", "error": str(exc)},
+            )
+
+    for page in pages_data:
+        if not page.get("image_prompt") or page.get("image_url"):
+            continue
+
+        await ExecutionControl(db).stop_if_cancel_requested(job=job, story=story)
+        try:
+            page["image_url"] = await generate_image_func(
+                page["image_prompt"],
+                db=db,
+                user_id=story.user_id,
+                generation_job=job,
+                story_id=story.id,
+            )
+            page_number = page.get("page_number")
+            if isinstance(page_number, int):
+                completed_pages.append(page_number)
+            await TraceRecorder(db).record_step(
+                job=job,
+                story_id=story.id,
+                event_type="storybook_page_image_succeeded",
+                status="succeeded",
+                message="Storybook page image was generated.",
+                metadata={"asset": "image", "scope": "page", "page_number": page_number},
+            )
+        except Exception as exc:
+            page_number = page.get("page_number")
+            if isinstance(page_number, int):
+                failed_pages.append(page_number)
+            logger.warning(
+                "storybook_page_asset_completion_failed",
+                story_id=story.id,
+                page=page_number,
+                error=str(exc),
+            )
+            await TraceRecorder(db).record_step(
+                job=job,
+                story_id=story.id,
+                event_type="storybook_page_image_failed",
+                status="failed",
+                message="Storybook page image generation failed.",
+                metadata={
+                    "asset": "image",
+                    "scope": "page",
+                    "page_number": page_number,
+                    "error": str(exc),
+                },
+            )
+
+    story.pages = pages_data
+    error_message = build_storybook_error_message(
+        cover_failed=cover_failed,
+        failed_pages=failed_pages,
+    )
+    image_status = resolve_storybook_image_status(
+        generate_images=True,
+        cover_prompt=story.cover_prompt,
+        cover_url=story.image_url,
+        pages_data=pages_data,
+    )
+    sync_story_status(
+        story,
+        image_status=image_status,
+        last_error=error_message,
+    )
+    await db.commit()
+
+    result = AssetCompletionResult(
+        asset="storybook_images",
+        status=image_status,
+        value=story.image_url,
+        error=error_message,
+    )
+    await TraceRecorder(db).record_step(
+        job=job,
+        story_id=story.id,
+        event_type="storybook_images_completed",
+        status="failed" if error_message else "succeeded",
+        message="Storybook image completion finished.",
+        metadata={
+            **asset_result_metadata(result),
+            "completed_pages": sorted(completed_pages),
+            "failed_pages": sorted(failed_pages),
+        },
+    )
+    return result

backend/app/services/harness/control.py

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+"""Execution control helpers for generation harness workflows."""
+
+from typing import TYPE_CHECKING
+
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.services.generation_jobs import finish_generation_job
+
+if TYPE_CHECKING:
+    from app.db.models import GenerationJob, Story
+
+
+class GenerationJobCanceledError(Exception):
+    """Raised when a running worker job has been canceled by the user."""
+
+
+class ExecutionControl:
+    """Runtime control surface for cancelable generation workflows."""
+
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    async def stop_if_cancel_requested(
+        self,
+        *,
+        job: "GenerationJob | None",
+        story: "Story | None" = None,
+    ) -> None:
+        """Stop a worker-owned job at the next safe checkpoint after cancellation."""
+
+        if job is None:
+            return
+
+        await self.db.refresh(job)
+        if job.current_step != "cancel_requested":
+            return
+
+        await finish_generation_job(
+            self.db,
+            job=job,
+            story=story,
+            status="canceled",
+            current_step="generation_canceled",
+            error_message="Generation canceled by user.",
+            message="Generation job was canceled after a user request.",
+        )
+        raise GenerationJobCanceledError()
+

backend/app/services/harness/plans.py

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+"""Workflow plan builders for generation harness workflows."""
+
+from dataclasses import dataclass
+from enum import StrEnum
+from typing import Any
+
+from app.services.harness.types import ArtifactKind, WorkflowStep
+
+
+class WorkflowMode(StrEnum):
+    """Supported executable workflow modes."""
+
+    STORY = "story"
+    STORY_WITH_ASSETS = "story_with_assets"
+    STORYBOOK = "storybook"
+    ASSET_GENERATION = "asset_generation"
+    ASSET_RETRY = "asset_retry"
+
+
+@dataclass(frozen=True)
+class WorkflowTask:
+    """One planned step in a generation workflow."""
+
+    key: str
+    step: WorkflowStep
+    artifact: ArtifactKind
+    required: bool = True
+    recoverable: bool = False
+
+    def to_snapshot(self) -> dict[str, Any]:
+        """Return a JSON-safe snapshot for tests and trace metadata."""
+
+        return {
+            "key": self.key,
+            "step": self.step.value,
+            "artifact": self.artifact.value,
+            "required": self.required,
+            "recoverable": self.recoverable,
+        }
+
+
+@dataclass(frozen=True)
+class WorkflowPlan:
+    """Declarative shape of a generation workflow before execution."""
+
+    mode: WorkflowMode
+    tasks: tuple[WorkflowTask, ...]
+
+    def to_snapshot(self) -> dict[str, Any]:
+        """Return a JSON-safe snapshot for tests and trace metadata."""
+
+        return {
+            "mode": self.mode.value,
+            "tasks": [task.to_snapshot() for task in self.tasks],
+        }
+
+
+def build_story_plan(*, generate_images: bool) -> WorkflowPlan:
+    """Build a plan for a text story generation request."""
+
+    tasks = [
+        WorkflowTask(
+            key="prepare_context",
+            step=WorkflowStep.CONTEXT_PREPARATION,
+            artifact=ArtifactKind.NONE,
+        ),
+        WorkflowTask(
+            key="generate_narrative",
+            step=WorkflowStep.NARRATIVE_GENERATION,
+            artifact=ArtifactKind.STORY_TEXT,
+        ),
+        WorkflowTask(
+            key="persist_story",
+            step=WorkflowStep.STORY_PERSISTENCE,
+            artifact=ArtifactKind.STORY_TEXT,
+        ),
+    ]
+
+    if generate_images:
+        tasks.append(
+            WorkflowTask(
+                key="generate_cover_image",
+                step=WorkflowStep.IMAGE_GENERATION,
+                artifact=ArtifactKind.COVER_IMAGE,
+                required=False,
+                recoverable=True,
+            )
+        )
+
+    tasks.extend(
+        [
+            WorkflowTask(
+                key="queue_postprocessing",
+                step=WorkflowStep.POSTPROCESSING,
+                artifact=ArtifactKind.ACHIEVEMENT_MEMORY,
+                required=False,
+                recoverable=True,
+            ),
+            WorkflowTask(
+                key="complete_generation",
+                step=WorkflowStep.COMPLETION,
+                artifact=ArtifactKind.NONE,
+            ),
+        ]
+    )
+
+    return WorkflowPlan(
+        mode=WorkflowMode.STORY_WITH_ASSETS if generate_images else WorkflowMode.STORY,
+        tasks=tuple(tasks),
+    )
+
+
+def build_storybook_plan(*, generate_images: bool) -> WorkflowPlan:
+    """Build a plan for a storybook generation request."""
+
+    tasks = [
+        WorkflowTask(
+            key="prepare_context",
+            step=WorkflowStep.CONTEXT_PREPARATION,
+            artifact=ArtifactKind.NONE,
+        ),
+        WorkflowTask(
+            key="generate_storybook_pages",
+            step=WorkflowStep.NARRATIVE_GENERATION,
+            artifact=ArtifactKind.STORYBOOK_PAGES,
+        ),
+    ]
+
+    if generate_images:
+        tasks.append(
+            WorkflowTask(
+                key="generate_storybook_images",
+                step=WorkflowStep.IMAGE_GENERATION,
+                artifact=ArtifactKind.IMAGE,
+                required=False,
+                recoverable=True,
+            )
+        )
+
+    tasks.extend(
+        [
+            WorkflowTask(
+                key="persist_storybook",
+                step=WorkflowStep.STORY_PERSISTENCE,
+                artifact=ArtifactKind.STORYBOOK_PAGES,
+            ),
+            WorkflowTask(
+                key="queue_postprocessing",
+                step=WorkflowStep.POSTPROCESSING,
+                artifact=ArtifactKind.ACHIEVEMENT_MEMORY,
+                required=False,
+                recoverable=True,
+            ),
+            WorkflowTask(
+                key="complete_generation",
+                step=WorkflowStep.COMPLETION,
+                artifact=ArtifactKind.NONE,
+            ),
+        ]
+    )
+
+    return WorkflowPlan(mode=WorkflowMode.STORYBOOK, tasks=tuple(tasks))
+
+
+def build_asset_plan(*, output_mode: str, assets: list[str]) -> WorkflowPlan:
+    """Build a plan for asset generation or retry jobs."""
+
+    mode = (
+        WorkflowMode.ASSET_RETRY
+        if output_mode == WorkflowMode.ASSET_RETRY.value
+        else WorkflowMode.ASSET_GENERATION
+    )
+    initial_step = (
+        WorkflowStep.ASSET_RETRY
+        if mode == WorkflowMode.ASSET_RETRY
+        else WorkflowStep.ASSET_GENERATION
+    )
+    initial_key = (
+        "start_asset_retry"
+        if mode == WorkflowMode.ASSET_RETRY
+        else "start_asset_generation"
+    )
+    completion_key = (
+        "complete_asset_retry"
+        if mode == WorkflowMode.ASSET_RETRY
+        else "complete_asset_generation"
+    )
+
+    tasks = [
+        WorkflowTask(
+            key=initial_key,
+            step=initial_step,
+            artifact=ArtifactKind.NONE,
+        )
+    ]
+
+    for asset in dict.fromkeys(assets):
+        if asset == "image":
+            tasks.append(
+                WorkflowTask(
+                    key="complete_image_asset",
+                    step=WorkflowStep.IMAGE_GENERATION,
+                    artifact=ArtifactKind.IMAGE,
+                    required=False,
+                    recoverable=True,
+                )
+            )
+        elif asset == "audio":
+            tasks.append(
+                WorkflowTask(
+                    key="complete_audio_asset",
+                    step=WorkflowStep.AUDIO_GENERATION,
+                    artifact=ArtifactKind.AUDIO,
+                    required=False,
+                    recoverable=True,
+                )
+            )
+        else:
+            tasks.append(
+                WorkflowTask(
+                    key=f"complete_{asset}_asset",
+                    step=WorkflowStep.UNKNOWN,
+                    artifact=ArtifactKind.UNKNOWN,
+                    required=False,
+                    recoverable=True,
+                )
+            )
+
+    tasks.append(
+        WorkflowTask(
+            key=completion_key,
+            step=initial_step,
+            artifact=ArtifactKind.NONE,
+        )
+    )
+
+    return WorkflowPlan(mode=mode, tasks=tuple(tasks))

backend/app/services/harness/quality_gates.py

@@ -0,0 +1,191 @@
+"""Deterministic quality gates for generated child-facing content."""
+
+from dataclasses import dataclass
+from enum import StrEnum
+
+from app.services.adapters.storybook.primary import Storybook
+from app.services.adapters.text.models import StoryOutput
+from app.services.harness.types import FailureCategory
+
+
+class QualityGateCode(StrEnum):
+    """Stable issue codes emitted by deterministic quality gates."""
+
+    MISSING_TITLE = "missing_title"
+    MISSING_STORY_TEXT = "missing_story_text"
+    MISSING_COVER_PROMPT = "missing_cover_prompt"
+    MISSING_STORYBOOK_PAGE = "missing_storybook_page"
+    INVALID_STORYBOOK_PAGE_NUMBER = "invalid_storybook_page_number"
+    MISSING_STORYBOOK_PAGE_TEXT = "missing_storybook_page_text"
+    UNSAFE_CHILD_CONTENT = "unsafe_child_content"
+
+
+@dataclass(frozen=True)
+class QualityGateIssue:
+    """One deterministic quality gate issue."""
+
+    code: QualityGateCode
+    message: str
+    failure_category: FailureCategory = FailureCategory.SCHEMA_ERROR
+    field: str | None = None
+
+    def to_metadata(self) -> dict:
+        """Return a JSON-safe metadata payload."""
+
+        return {
+            "code": self.code.value,
+            "message": self.message,
+            "failure_category": self.failure_category.value,
+            "field": self.field,
+        }
+
+
+class QualityGateError(ValueError):
+    """Raised when generated content fails deterministic quality gates."""
+
+    def __init__(self, issues: list[QualityGateIssue]):
+        self.issues = issues
+        message = "；".join(issue.message for issue in issues)
+        super().__init__(message)
+
+    def to_metadata(self) -> dict:
+        """Return a JSON-safe metadata payload."""
+
+        return {"issues": [issue.to_metadata() for issue in self.issues]}
+
+
+UNSAFE_CHILD_TERMS = (
+    "自杀",
+    "自残",
+    "血腥",
+    "虐待",
+    "毒品",
+    "色情",
+)
+
+
+def _is_blank(value: str | None) -> bool:
+    return not value or not value.strip()
+
+
+def _unsafe_issue_if_present(text: str, *, field: str) -> QualityGateIssue | None:
+    for term in UNSAFE_CHILD_TERMS:
+        if term in text:
+            return QualityGateIssue(
+                code=QualityGateCode.UNSAFE_CHILD_CONTENT,
+                message="生成内容包含不适合 3-8 岁儿童的明显风险词。",
+                failure_category=FailureCategory.SAFETY_ERROR,
+                field=field,
+            )
+    return None
+
+
+def validate_story_output(output: StoryOutput) -> None:
+    """Validate generated text story output before persistence."""
+
+    issues: list[QualityGateIssue] = []
+
+    if _is_blank(output.title):
+        issues.append(
+            QualityGateIssue(
+                code=QualityGateCode.MISSING_TITLE,
+                message="故事标题为空。",
+                field="title",
+            )
+        )
+
+    if _is_blank(output.story_text):
+        issues.append(
+            QualityGateIssue(
+                code=QualityGateCode.MISSING_STORY_TEXT,
+                message="故事正文为空。",
+                field="story_text",
+            )
+        )
+
+    if _is_blank(output.cover_prompt_suggestion):
+        issues.append(
+            QualityGateIssue(
+                code=QualityGateCode.MISSING_COVER_PROMPT,
+                message="封面提示词为空。",
+                field="cover_prompt_suggestion",
+            )
+        )
+
+    unsafe_issue = _unsafe_issue_if_present(
+        " ".join([output.title or "", output.story_text or ""]),
+        field="story_text",
+    )
+    if unsafe_issue is not None:
+        issues.append(unsafe_issue)
+
+    if issues:
+        raise QualityGateError(issues)
+
+
+def validate_storybook_output(output: Storybook) -> None:
+    """Validate generated storybook output before persistence."""
+
+    issues: list[QualityGateIssue] = []
+
+    if _is_blank(output.title):
+        issues.append(
+            QualityGateIssue(
+                code=QualityGateCode.MISSING_TITLE,
+                message="绘本标题为空。",
+                field="title",
+            )
+        )
+
+    if not output.pages:
+        issues.append(
+            QualityGateIssue(
+                code=QualityGateCode.MISSING_STORYBOOK_PAGE,
+                message="绘本至少需要一页内容。",
+                field="pages",
+            )
+        )
+
+    seen_page_numbers: set[int] = set()
+    page_texts: list[str] = []
+    for index, page in enumerate(output.pages, start=1):
+        if not isinstance(page.page_number, int) or page.page_number <= 0:
+            issues.append(
+                QualityGateIssue(
+                    code=QualityGateCode.INVALID_STORYBOOK_PAGE_NUMBER,
+                    message=f"绘本第 {index} 个页面页码无效。",
+                    field=f"pages[{index - 1}].page_number",
+                )
+            )
+        elif page.page_number in seen_page_numbers:
+            issues.append(
+                QualityGateIssue(
+                    code=QualityGateCode.INVALID_STORYBOOK_PAGE_NUMBER,
+                    message=f"绘本页码 {page.page_number} 重复。",
+                    field=f"pages[{index - 1}].page_number",
+                )
+            )
+        else:
+            seen_page_numbers.add(page.page_number)
+
+        if _is_blank(page.text):
+            issues.append(
+                QualityGateIssue(
+                    code=QualityGateCode.MISSING_STORYBOOK_PAGE_TEXT,
+                    message=f"绘本第 {index} 页正文为空。",
+                    field=f"pages[{index - 1}].text",
+                )
+            )
+        else:
+            page_texts.append(page.text)
+
+    unsafe_issue = _unsafe_issue_if_present(
+        " ".join([output.title or "", *page_texts]),
+        field="pages",
+    )
+    if unsafe_issue is not None:
+        issues.append(unsafe_issue)
+
+    if issues:
+        raise QualityGateError(issues)
+

backend/app/services/harness/trace.py

@@ -0,0 +1,64 @@
+"""Trace recording helpers for generation harness workflows."""
+
+from typing import TYPE_CHECKING, Any
+
+from sqlalchemy.ext.asyncio import AsyncSession
+
+from app.services.generation_jobs import record_generation_event
+from app.services.harness.types import (
+    ArtifactKind,
+    FailureCategory,
+    WorkflowStep,
+    normalize_trace_metadata,
+)
+
+if TYPE_CHECKING:
+    from app.db.models import GenerationJob
+
+
+class TraceRecorder:
+    """Append workflow events with standard harness trace metadata."""
+
+    def __init__(self, db: AsyncSession):
+        self.db = db
+
+    async def record_step(
+        self,
+        *,
+        job: "GenerationJob | None",
+        event_type: str,
+        status: str,
+        story_id: int | None = None,
+        message: str | None = None,
+        metadata: dict[str, Any] | None = None,
+        step: WorkflowStep | str | None = None,
+        artifact: ArtifactKind | str | None = None,
+        failure_category: FailureCategory | str | None = None,
+        retryable: bool | None = None,
+        blocks_main_result: bool | None = None,
+        commit: bool = True,
+    ):
+        """Append a workflow event when the caller is running under a tracked job."""
+
+        if job is None:
+            return None
+
+        return await record_generation_event(
+            self.db,
+            job=job,
+            story_id=story_id,
+            event_type=event_type,
+            status=status,
+            message=message,
+            metadata=normalize_trace_metadata(
+                event_type,
+                metadata,
+                step=step,
+                artifact=artifact,
+                failure_category=failure_category,
+                retryable=retryable,
+                blocks_main_result=blocks_main_result,
+            ),
+            commit=commit,
+        )
+

backend/app/services/harness/types.py

@@ -0,0 +1,169 @@
+"""Shared types for the generation harness runtime."""
+
+from enum import StrEnum
+from typing import Any
+
+
+class WorkflowStep(StrEnum):
+    """Standard product-level steps for generation workflows."""
+
+    REQUEST_ACCEPTANCE = "request_acceptance"
+    WORKER_START = "worker_start"
+    CONTEXT_PREPARATION = "context_preparation"
+    NARRATIVE_GENERATION = "narrative_generation"
+    STORY_PERSISTENCE = "story_persistence"
+    PROVIDER_INVOCATION = "provider_invocation"
+    IMAGE_GENERATION = "image_generation"
+    AUDIO_GENERATION = "audio_generation"
+    ASSET_RETRY = "asset_retry"
+    ASSET_GENERATION = "asset_generation"
+    POSTPROCESSING = "postprocessing"
+    COMPLETION = "completion"
+    CANCELLATION = "cancellation"
+    STALE_RECOVERY = "stale_recovery"
+    UNKNOWN = "unknown"
+
+
+class ArtifactKind(StrEnum):
+    """Artifacts produced or completed by generation workflows."""
+
+    STORY_TEXT = "story_text"
+    STORYBOOK_PAGES = "storybook_pages"
+    COVER_IMAGE = "cover_image"
+    PAGE_IMAGE = "page_image"
+    IMAGE = "image"
+    AUDIO = "audio"
+    ACHIEVEMENT_MEMORY = "achievement_memory"
+    NONE = "none"
+    UNKNOWN = "unknown"
+
+
+class FailureCategory(StrEnum):
+    """Coarse failure categories for trace and analytics metadata."""
+
+    PROVIDER_ERROR = "provider_error"
+    SCHEMA_ERROR = "schema_error"
+    SAFETY_ERROR = "safety_error"
+    TIMEOUT = "timeout"
+    CANCELED = "canceled"
+    STALE_JOB = "stale_job"
+    STORAGE_ERROR = "storage_error"
+    VALIDATION_ERROR = "validation_error"
+    UNKNOWN_ERROR = "unknown_error"
+
+
+class StepStatus(StrEnum):
+    """Standard status values for a workflow step."""
+
+    QUEUED = "queued"
+    RUNNING = "running"
+    SUCCEEDED = "succeeded"
+    FAILED = "failed"
+    CANCELED = "canceled"
+
+
+EVENT_STEP_MAP: dict[str, WorkflowStep] = {
+    "request_accepted": WorkflowStep.REQUEST_ACCEPTANCE,
+    "retry_queued": WorkflowStep.REQUEST_ACCEPTANCE,
+    "worker_started": WorkflowStep.WORKER_START,
+    "context_prepared": WorkflowStep.CONTEXT_PREPARATION,
+    "narrative_generated": WorkflowStep.NARRATIVE_GENERATION,
+    "story_saved": WorkflowStep.STORY_PERSISTENCE,
+    "provider_call_started": WorkflowStep.PROVIDER_INVOCATION,
+    "provider_call_succeeded": WorkflowStep.PROVIDER_INVOCATION,
+    "provider_call_failed": WorkflowStep.PROVIDER_INVOCATION,
+    "quality_gate_failed": WorkflowStep.NARRATIVE_GENERATION,
+    "cover_image_started": WorkflowStep.IMAGE_GENERATION,
+    "cover_image_succeeded": WorkflowStep.IMAGE_GENERATION,
+    "cover_image_failed": WorkflowStep.IMAGE_GENERATION,
+    "storybook_images_started": WorkflowStep.IMAGE_GENERATION,
+    "storybook_cover_image_succeeded": WorkflowStep.IMAGE_GENERATION,
+    "storybook_cover_image_failed": WorkflowStep.IMAGE_GENERATION,
+    "storybook_page_image_succeeded": WorkflowStep.IMAGE_GENERATION,
+    "storybook_page_image_failed": WorkflowStep.IMAGE_GENERATION,
+    "storybook_images_completed": WorkflowStep.IMAGE_GENERATION,
+    "audio_started": WorkflowStep.AUDIO_GENERATION,
+    "audio_cache_hit": WorkflowStep.AUDIO_GENERATION,
+    "audio_succeeded": WorkflowStep.AUDIO_GENERATION,
+    "audio_failed": WorkflowStep.AUDIO_GENERATION,
+    "asset_retry_started": WorkflowStep.ASSET_RETRY,
+    "asset_retry_completed": WorkflowStep.ASSET_RETRY,
+    "asset_generation_completed": WorkflowStep.ASSET_GENERATION,
+    "postprocessing_queued": WorkflowStep.POSTPROCESSING,
+    "generation_completed": WorkflowStep.COMPLETION,
+    "generation_failed": WorkflowStep.COMPLETION,
+    "generation_canceled": WorkflowStep.CANCELLATION,
+    "cancel_requested": WorkflowStep.CANCELLATION,
+    "generation_stale_failed": WorkflowStep.STALE_RECOVERY,
+}
+
+EVENT_ARTIFACT_MAP: dict[str, ArtifactKind] = {
+    "narrative_generated": ArtifactKind.STORY_TEXT,
+    "quality_gate_failed": ArtifactKind.STORY_TEXT,
+    "cover_image_started": ArtifactKind.COVER_IMAGE,
+    "cover_image_succeeded": ArtifactKind.COVER_IMAGE,
+    "cover_image_failed": ArtifactKind.COVER_IMAGE,
+    "storybook_images_started": ArtifactKind.IMAGE,
+    "storybook_cover_image_succeeded": ArtifactKind.COVER_IMAGE,
+    "storybook_cover_image_failed": ArtifactKind.COVER_IMAGE,
+    "storybook_page_image_succeeded": ArtifactKind.PAGE_IMAGE,
+    "storybook_page_image_failed": ArtifactKind.PAGE_IMAGE,
+    "storybook_images_completed": ArtifactKind.IMAGE,
+    "audio_started": ArtifactKind.AUDIO,
+    "audio_cache_hit": ArtifactKind.AUDIO,
+    "audio_succeeded": ArtifactKind.AUDIO,
+    "audio_failed": ArtifactKind.AUDIO,
+    "postprocessing_queued": ArtifactKind.ACHIEVEMENT_MEMORY,
+}
+
+
+def step_for_event(event_type: str) -> WorkflowStep:
+    """Return the standard workflow step for a persisted event type."""
+
+    return EVENT_STEP_MAP.get(event_type, WorkflowStep.UNKNOWN)
+
+
+def artifact_for_event(event_type: str) -> ArtifactKind:
+    """Return the standard artifact for a persisted event type."""
+
+    return EVENT_ARTIFACT_MAP.get(event_type, ArtifactKind.NONE)
+
+
+def normalize_trace_metadata(
+    event_type: str,
+    metadata: dict[str, Any] | None = None,
+    *,
+    step: WorkflowStep | str | None = None,
+    artifact: ArtifactKind | str | None = None,
+    failure_category: FailureCategory | str | None = None,
+    retryable: bool | None = None,
+    blocks_main_result: bool | None = None,
+) -> dict[str, Any]:
+    """Merge legacy metadata with standard harness trace fields."""
+
+    normalized: dict[str, Any] = dict(metadata or {})
+
+    resolved_step = str(step or normalized.get("step") or step_for_event(event_type))
+    resolved_artifact = str(
+        artifact or normalized.get("artifact") or artifact_for_event(event_type)
+    )
+
+    normalized["step"] = resolved_step
+    normalized["artifact"] = resolved_artifact
+
+    if failure_category is not None:
+        normalized["failure_category"] = str(failure_category)
+    elif "failure_category" not in normalized:
+        normalized["failure_category"] = None
+
+    if retryable is not None:
+        normalized["retryable"] = retryable
+    elif "retryable" not in normalized:
+        normalized["retryable"] = False
+
+    if blocks_main_result is not None:
+        normalized["blocks_main_result"] = blocks_main_result
+    elif "blocks_main_result" not in normalized:
+        normalized["blocks_main_result"] = False
+
+    return normalized

backend/app/services/provider_router.py

@@ -10,7 +10,7 @@ from app.core.logging import get_logger
 from app.services.adapters import AdapterConfig, AdapterRegistry
 from app.services.adapters.text.models import StoryOutput
 from app.services.cost_tracker import cost_tracker
-from app.services.generation_jobs import record_generation_event
+from app.services.harness.trace import TraceRecorder
 from app.services.provider_cache import get_providers
 from app.services.provider_metrics import health_checker, metrics_collector
 from app.services.provider_policy import (
@@ -67,8 +67,7 @@ async def _record_provider_event_if_present(
     if db is None or job is None:
         return
 
-    await record_generation_event(
-        db,
+    await TraceRecorder(db).record_step(
         job=job,
         story_id=story_id,
         event_type=event_type,

backend/app/services/story_service.py

@@ -1,9 +1,7 @@
 """Story business logic service."""
 
 import asyncio
-from dataclasses import dataclass
 from datetime import datetime, timedelta, timezone
-from typing import Literal
 
 from fastapi import HTTPException
 from sqlalchemy import desc, select
@@ -42,6 +40,29 @@ from app.services.generation_jobs import (
     get_generation_job_for_user,
     record_generation_event,
 )
+from app.services.harness.artifacts import (
+    AssetCompletionResult,
+    asset_result_metadata,
+)
+from app.services.harness.asset_workflows import (
+    build_storybook_error_message,
+    complete_audio_asset,
+    complete_cover_image_asset,
+    complete_storybook_image_assets,
+    get_storybook_pages_data,
+    read_cached_audio_asset,
+    resolve_storybook_image_status,
+)
+from app.services.harness.control import (
+    ExecutionControl,
+    GenerationJobCanceledError,
+)
+from app.services.harness.quality_gates import (
+    QualityGateError,
+    validate_story_output,
+    validate_storybook_output,
+)
+from app.services.harness.trace import TraceRecorder
 from app.services.memory_service import build_enhanced_memory_context
 from app.services.provider_router import (
     generate_image,
@@ -56,29 +77,6 @@ from app.tasks.achievements import extract_story_achievements
 
 logger = get_logger(__name__)
 
-AssetCompletionKind = Literal["cover_image", "storybook_images", "audio"]
-
-
-@dataclass(frozen=True)
-class AssetCompletionResult:
-    """Service-level result for a generated asset completion attempt."""
-
-    asset: AssetCompletionKind
-    status: StoryAssetStatus
-    value: str | bytes | None = None
-    error: str | None = None
-    blocks_main_result: bool = False
-
-    @property
-    def succeeded(self) -> bool:
-        """Whether the asset reached a usable ready state."""
-
-        return self.status == StoryAssetStatus.READY and self.error is None
-
-
-class GenerationJobCanceledError(Exception):
-    """Raised when a running worker job has been canceled by the user."""
-
 
 async def _record_job_event_if_present(
     db: AsyncSession,
@@ -92,11 +90,7 @@ async def _record_job_event_if_present(
 ) -> None:
     """Append a workflow event when the caller is running under a tracked job."""
 
-    if job is None:
-        return
-
-    await record_generation_event(
-        db,
+    await TraceRecorder(db).record_step(
         job=job,
         story_id=story_id,
         event_type=event_type,
@@ -114,34 +108,31 @@ async def _stop_if_job_cancel_requested(
 ) -> None:
     """Stop a worker-owned job at the next safe checkpoint after cancellation."""
 
-    if job is None:
-        return
+    await ExecutionControl(db).stop_if_cancel_requested(job=job, story=story)
 
-    await db.refresh(job)
-    if job.current_step != "cancel_requested":
-        return
 
-    await finish_generation_job(
+async def _record_quality_gate_failure_if_present(
+    db: AsyncSession,
+    *,
+    job,
+    error: QualityGateError,
+) -> None:
+    """Append a quality gate failure event for tracked worker jobs."""
+
+    await _record_job_event_if_present(
         db,
         job=job,
-        story=story,
-        status="canceled",
-        current_step="generation_canceled",
-        error_message="Generation canceled by user.",
-        message="Generation job was canceled after a user request.",
+        event_type="quality_gate_failed",
+        status="failed",
+        message="Generated content failed deterministic quality gates.",
+        metadata=error.to_metadata(),
     )
-    raise GenerationJobCanceledError()
 
 
 def _asset_result_metadata(result: AssetCompletionResult) -> dict:
     """Build JSON-safe metadata for asset workflow events."""
 
-    return {
-        "asset": result.asset,
-        "status": result.status.value,
-        "error": result.error,
-        "blocks_main_result": result.blocks_main_result,
-    }
+    return asset_result_metadata(result)
 
 
 def _build_storybook_error_message(
@@ -151,13 +142,10 @@ def _build_storybook_error_message(
 ) -> str | None:
     """Summarize storybook image generation errors for the latest attempt."""
 
-    parts: list[str] = []
-    if cover_failed:
-        parts.append("封面生成失败")
-    if failed_pages:
-        pages = "、".join(str(page) for page in sorted(failed_pages))
-        parts.append(f"第 {pages} 页插图生成失败")
-    return "；".join(parts) if parts else None
+    return build_storybook_error_message(
+        cover_failed=cover_failed,
+        failed_pages=failed_pages,
+    )
 
 
 def _resolve_storybook_image_status(
@@ -169,31 +157,12 @@ def _resolve_storybook_image_status(
 ) -> StoryAssetStatus:
     """Resolve the persisted image status for a storybook."""
 
-    if not generate_images:
-        return StoryAssetStatus.NOT_REQUESTED
-
-    expected_assets = 0
-    ready_assets = 0
-
-    if cover_prompt or cover_url:
-        expected_assets += 1
-    if cover_url:
-        ready_assets += 1
-
-    for page in pages_data:
-        if not page.get("image_prompt") and not page.get("image_url"):
-            continue
-        expected_assets += 1
-        if page.get("image_url"):
-            ready_assets += 1
-
-    if expected_assets == 0:
-        return StoryAssetStatus.NOT_REQUESTED
-
-    if ready_assets == expected_assets:
-        return StoryAssetStatus.READY
-
-    return StoryAssetStatus.FAILED
+    return resolve_storybook_image_status(
+        generate_images=generate_images,
+        cover_prompt=cover_prompt,
+        cover_url=cover_url,
+        pages_data=pages_data,
+    )
 
 
 async def _prepare_generation_context(
@@ -539,93 +508,21 @@ async def _complete_cover_image_asset(
 ) -> AssetCompletionResult:
     """Generate or retry a text story cover through one asset workflow."""
 
-    if not story.cover_prompt:
-        raise HTTPException(status_code=400, detail="Story has no cover prompt")
-
-    sync_story_status(story, image_status=StoryAssetStatus.GENERATING)
-    await db.commit()
-    await _stop_if_job_cancel_requested(db, job=job, story=story)
-    await _record_job_event_if_present(
+    return await complete_cover_image_asset(
+        story,
         db,
+        generate_image_func=generate_image,
+        raise_on_failure=raise_on_failure,
+        last_error_prefix=last_error_prefix,
+        log_event=log_event,
         job=job,
-        story_id=story.id,
-        event_type="cover_image_started",
-        status="running",
-        message="Cover image generation started.",
-        metadata={"asset": "image", "cover_prompt_present": True},
     )
 
-    try:
-        await _stop_if_job_cancel_requested(db, job=job, story=story)
-        image_url = await generate_image(
-            story.cover_prompt,
-            db=db,
-            user_id=story.user_id,
-            generation_job=job,
-            story_id=story.id,
-        )
-        story.image_url = image_url
-        sync_story_status(story, image_status=StoryAssetStatus.READY)
-        await db.commit()
-        result = AssetCompletionResult(
-            asset="cover_image",
-            status=StoryAssetStatus.READY,
-            value=image_url,
-            blocks_main_result=raise_on_failure,
-        )
-        await _record_job_event_if_present(
-            db,
-            job=job,
-            story_id=story.id,
-            event_type="cover_image_succeeded",
-            status="succeeded",
-            message="Cover image was generated.",
-            metadata=_asset_result_metadata(result),
-        )
-        return result
-    except Exception as exc:
-        provider_error = str(exc)
-        last_error = (
-            f"{last_error_prefix}: {provider_error}"
-            if last_error_prefix
-            else provider_error
-        )
-        sync_story_status(
-            story,
-            image_status=StoryAssetStatus.FAILED,
-            last_error=last_error,
-        )
-        await db.commit()
-        logger.warning(log_event, story_id=story.id, error=provider_error)
-
-        result = AssetCompletionResult(
-            asset="cover_image",
-            status=StoryAssetStatus.FAILED,
-            error=provider_error,
-            blocks_main_result=raise_on_failure,
-        )
-        await _record_job_event_if_present(
-            db,
-            job=job,
-            story_id=story.id,
-            event_type="cover_image_failed",
-            status="failed",
-            message="Cover image generation failed.",
-            metadata=_asset_result_metadata(result),
-        )
-        if raise_on_failure:
-            raise HTTPException(
-                status_code=500,
-                detail=f"Image generation failed: {provider_error}",
-            ) from exc
-
-        return result
-
 
 def _get_storybook_pages_data(story: Story) -> list[dict]:
     """Return mutable storybook page data from the persisted JSON field."""
 
-    return [dict(page) for page in story.pages or [] if isinstance(page, dict)]
+    return get_storybook_pages_data(story)
 
 
 async def _complete_storybook_image_assets(
@@ -636,176 +533,23 @@ async def _complete_storybook_image_assets(
 ) -> AssetCompletionResult:
     """Complete missing cover/page images for a persisted storybook."""
 
-    pages_data = _get_storybook_pages_data(story)
-    has_image_prompt = bool(story.cover_prompt) or any(
-        page.get("image_prompt") for page in pages_data
-    )
-    if not has_image_prompt:
-        raise HTTPException(status_code=400, detail="Storybook has no image prompts")
-
-    sync_story_status(story, image_status=StoryAssetStatus.GENERATING)
-    await db.commit()
-    await _stop_if_job_cancel_requested(db, job=job, story=story)
-    await _record_job_event_if_present(
-        db,
-        job=job,
-        story_id=story.id,
-        event_type="storybook_images_started",
-        status="running",
-        message="Storybook missing image completion started.",
-        metadata={"asset": "image"},
-    )
-
-    cover_failed = False
-    failed_pages: list[int] = []
-    completed_pages: list[int] = []
-
-    if story.cover_prompt and not story.image_url:
-        await _stop_if_job_cancel_requested(db, job=job, story=story)
-        try:
-            story.image_url = await generate_image(
-                story.cover_prompt,
-                db=db,
-                user_id=story.user_id,
-                generation_job=job,
-                story_id=story.id,
-            )
-            await _record_job_event_if_present(
-                db,
-                job=job,
-                story_id=story.id,
-                event_type="storybook_cover_image_succeeded",
-                status="succeeded",
-                message="Storybook cover image was generated.",
-                metadata={"asset": "image", "scope": "cover"},
-            )
-        except Exception as exc:
-            cover_failed = True
-            logger.warning(
-                "storybook_cover_asset_completion_failed",
-                story_id=story.id,
-                error=str(exc),
-            )
-            await _record_job_event_if_present(
-                db,
-                job=job,
-                story_id=story.id,
-                event_type="storybook_cover_image_failed",
-                status="failed",
-                message="Storybook cover image generation failed.",
-                metadata={"asset": "image", "scope": "cover", "error": str(exc)},
-            )
-
-    for page in pages_data:
-        if not page.get("image_prompt") or page.get("image_url"):
-            continue
-
-        await _stop_if_job_cancel_requested(db, job=job, story=story)
-        try:
-            page["image_url"] = await generate_image(
-                page["image_prompt"],
-                db=db,
-                user_id=story.user_id,
-                generation_job=job,
-                story_id=story.id,
-            )
-            page_number = page.get("page_number")
-            if isinstance(page_number, int):
-                completed_pages.append(page_number)
-            await _record_job_event_if_present(
-                db,
-                job=job,
-                story_id=story.id,
-                event_type="storybook_page_image_succeeded",
-                status="succeeded",
-                message="Storybook page image was generated.",
-                metadata={"asset": "image", "scope": "page", "page_number": page_number},
-            )
-        except Exception as exc:
-            page_number = page.get("page_number")
-            if isinstance(page_number, int):
-                failed_pages.append(page_number)
-            logger.warning(
-                "storybook_page_asset_completion_failed",
-                story_id=story.id,
-                page=page_number,
-                error=str(exc),
-            )
-            await _record_job_event_if_present(
-                db,
-                job=job,
-                story_id=story.id,
-                event_type="storybook_page_image_failed",
-                status="failed",
-                message="Storybook page image generation failed.",
-                metadata={
-                    "asset": "image",
-                    "scope": "page",
-                    "page_number": page_number,
-                    "error": str(exc),
-                },
-            )
-
-    story.pages = pages_data
-    error_message = _build_storybook_error_message(
-        cover_failed=cover_failed,
-        failed_pages=failed_pages,
-    )
-    image_status = _resolve_storybook_image_status(
-        generate_images=True,
-        cover_prompt=story.cover_prompt,
-        cover_url=story.image_url,
-        pages_data=pages_data,
-    )
-    sync_story_status(
+    return await complete_storybook_image_assets(
         story,
-        image_status=image_status,
-        last_error=error_message,
-    )
-    await db.commit()
-    result = AssetCompletionResult(
-        asset="storybook_images",
-        status=image_status,
-        value=story.image_url,
-        error=error_message,
-    )
-    await _record_job_event_if_present(
         db,
+        generate_image_func=generate_image,
         job=job,
-        story_id=story.id,
-        event_type="storybook_images_completed",
-        status="failed" if error_message else "succeeded",
-        message="Storybook image completion finished.",
-        metadata={
-            **_asset_result_metadata(result),
-            "completed_pages": sorted(completed_pages),
-            "failed_pages": sorted(failed_pages),
-        },
     )
-    return result
 
 
 async def _read_cached_audio_asset(story: Story, db: AsyncSession) -> bytes | None:
     """Read cached audio or repair stale audio cache metadata."""
 
-    if story.audio_path and audio_cache_exists(story.audio_path):
-        if story.audio_status != StoryAssetStatus.READY.value:
-            sync_story_status(story, audio_status=StoryAssetStatus.READY)
-            await db.commit()
-        return read_audio_cache(story.audio_path)
-
-    if story.audio_path and not audio_cache_exists(story.audio_path):
-        logger.warning(
-            "story_audio_cache_missing",
-            story_id=story.id,
-            audio_path=story.audio_path,
-        )
-        story.audio_path = None
-        if story.audio_status == StoryAssetStatus.READY.value:
-            sync_story_status(story, audio_status=StoryAssetStatus.NOT_REQUESTED)
-            await db.commit()
-
-    return None
+    return await read_cached_audio_asset(
+        story,
+        db,
+        audio_cache_exists_func=audio_cache_exists,
+        read_audio_cache_func=read_audio_cache,
+    )
 
 
 async def _complete_audio_asset(
@@ -817,107 +561,18 @@ async def _complete_audio_asset(
 ) -> AssetCompletionResult:
     """Complete TTS audio generation through one asset workflow."""
 
-    if not story.story_text:
-        raise HTTPException(status_code=400, detail="Story has no text")
-
-    cached_audio = await _read_cached_audio_asset(story, db)
-    if cached_audio is not None:
-        result = AssetCompletionResult(
-            asset="audio",
-            status=StoryAssetStatus.READY,
-            value=cached_audio,
-            blocks_main_result=raise_on_failure,
-        )
-        await _record_job_event_if_present(
-            db,
-            job=job,
-            story_id=story.id,
-            event_type="audio_cache_hit",
-            status="succeeded",
-            message="Cached story audio was reused.",
-            metadata=_asset_result_metadata(result),
-        )
-        return result
-
     from app.services.provider_router import text_to_speech
 
-    sync_story_status(story, audio_status=StoryAssetStatus.GENERATING)
-    await db.commit()
-    await _stop_if_job_cancel_requested(db, job=job, story=story)
-    await _record_job_event_if_present(
+    return await complete_audio_asset(
+        story,
         db,
+        text_to_speech_func=text_to_speech,
+        audio_cache_exists_func=audio_cache_exists,
+        read_audio_cache_func=read_audio_cache,
+        write_story_audio_cache_func=write_story_audio_cache,
+        raise_on_failure=raise_on_failure,
         job=job,
-        story_id=story.id,
-        event_type="audio_started",
-        status="running",
-        message="Story audio generation started.",
-        metadata={"asset": "audio"},
     )
-
-    try:
-        await _stop_if_job_cancel_requested(db, job=job, story=story)
-        audio_data = await text_to_speech(
-            story.story_text,
-            db=db,
-            user_id=story.user_id,
-            generation_job=job,
-            story_id=story.id,
-        )
-        story.audio_path = write_story_audio_cache(story.id, audio_data)
-        sync_story_status(
-            story,
-            audio_status=StoryAssetStatus.READY,
-        )
-        await db.commit()
-        result = AssetCompletionResult(
-            asset="audio",
-            status=StoryAssetStatus.READY,
-            value=audio_data,
-            blocks_main_result=raise_on_failure,
-        )
-        await _record_job_event_if_present(
-            db,
-            job=job,
-            story_id=story.id,
-            event_type="audio_succeeded",
-            status="succeeded",
-            message="Story audio was generated and cached.",
-            metadata=_asset_result_metadata(result),
-        )
-        return result
-    except Exception as exc:
-        provider_error = str(exc)
-        story.audio_path = None
-        sync_story_status(
-            story,
-            audio_status=StoryAssetStatus.FAILED,
-            last_error=provider_error,
-        )
-        await db.commit()
-        logger.error("audio_generation_failed", story_id=story.id, error=provider_error)
-
-        result = AssetCompletionResult(
-            asset="audio",
-            status=StoryAssetStatus.FAILED,
-            error=provider_error,
-            blocks_main_result=raise_on_failure,
-        )
-        await _record_job_event_if_present(
-            db,
-            job=job,
-            story_id=story.id,
-            event_type="audio_failed",
-            status="failed",
-            message="Story audio generation failed.",
-            metadata=_asset_result_metadata(result),
-        )
-        if raise_on_failure:
-            raise HTTPException(
-                status_code=500,
-                detail=f"Audio generation failed: {provider_error}",
-            ) from exc
-
-        return result
 
 
 async def validate_profile_and_universe(
@@ -988,6 +643,13 @@ async def generate_and_save_story(
             user_id=user_id,
             generation_job=job,
         )
+        validate_story_output(result)
+    except QualityGateError as exc:
+        await _record_quality_gate_failure_if_present(db, job=job, error=exc)
+        raise HTTPException(
+            status_code=502,
+            detail="Story generation failed quality checks, please try again.",
+        ) from exc
     except Exception as exc:
         raise HTTPException(
             status_code=502,
@@ -1096,6 +758,10 @@ async def generate_storybook_service(
             user_id=user_id,
             generation_job=job,
         )
+        validate_storybook_output(storybook)
+    except QualityGateError as exc:
+        await _record_quality_gate_failure_if_present(db, job=job, error=exc)
+        raise HTTPException(status_code=500, detail=f"故事书质量检查失败: {exc}") from exc
     except Exception as e:
         logger.error("storybook_generation_failed", error=str(e))
         raise HTTPException(status_code=500, detail=f"故事书生成失败: {e}")

backend/tests/test_generation_jobs.py

@@ -165,6 +165,70 @@ async def test_unified_generation_is_queued_then_worker_persists_story_and_event
         app.dependency_overrides.clear()
 
 
+async def test_generation_worker_records_quality_gate_failure_without_persisting_story(
+    db_session,
+    test_user,
+):
+    invalid_output = StoryOutput(
+        mode="generated",
+        title="空白故事",
+        story_text="",
+        cover_prompt_suggestion="A blank cover",
+    )
+    job = await create_generation_job(
+        db_session,
+        user_id=test_user.id,
+        output_mode="story",
+        input_type="keywords",
+        request_payload={
+            "output_mode": "story",
+            "type": "keywords",
+            "data": "小兔子",
+            "generate_images": False,
+        },
+    )
+
+    with patch(
+        "app.services.story_service.generate_story_content",
+        new_callable=AsyncMock,
+    ) as mock_generate_story_content:
+        mock_generate_story_content.return_value = invalid_output
+
+        with pytest.raises(Exception):
+            await run_generation_job_service(job.id, db_session)
+
+    refreshed_job = (
+        await db_session.execute(select(GenerationJob).where(GenerationJob.id == job.id))
+    ).scalar_one()
+    assert refreshed_job.status == "failed"
+    assert refreshed_job.story_id is None
+    assert refreshed_job.current_step == "generation_failed"
+    assert "quality checks" in refreshed_job.error_message
+
+    stories = (
+        await db_session.execute(select(Story).where(Story.user_id == test_user.id))
+    ).scalars().all()
+    assert stories == []
+
+    events = (
+        await db_session.execute(
+            select(GenerationJobEvent)
+            .where(GenerationJobEvent.job_id == job.id)
+            .order_by(GenerationJobEvent.id)
+        )
+    ).scalars().all()
+    assert [event.event_type for event in events] == [
+        "request_accepted",
+        "worker_started",
+        "context_prepared",
+        "quality_gate_failed",
+        "generation_failed",
+    ]
+    quality_event = events[3]
+    assert quality_event.event_metadata["step"] == "narrative_generation"
+    assert quality_event.event_metadata["issues"][0]["code"] == "missing_story_text"
+
+
 async def test_asset_retry_records_job_events_and_updates_retryable_assets(
     db_session,
     test_user,

backend/tests/test_harness_runtime.py

@@ -0,0 +1,374 @@
+"""Tests for generation harness runtime support."""
+
+import pytest
+from sqlalchemy import select
+
+from app.db.models import GenerationJob, GenerationJobEvent
+from app.services.adapters.storybook.primary import Storybook, StorybookPage
+from app.services.adapters.text.models import StoryOutput
+from app.services.generation_jobs import create_generation_job, record_generation_event
+from app.services.harness.control import ExecutionControl, GenerationJobCanceledError
+from app.services.harness.plans import (
+    build_asset_plan,
+    build_story_plan,
+    build_storybook_plan,
+)
+from app.services.harness.quality_gates import (
+    QualityGateError,
+    validate_story_output,
+    validate_storybook_output,
+)
+from app.services.harness.trace import TraceRecorder
+from app.services.harness.types import (
+    ArtifactKind,
+    FailureCategory,
+    WorkflowStep,
+    artifact_for_event,
+    normalize_trace_metadata,
+    step_for_event,
+)
+
+
+def test_event_type_maps_to_standard_workflow_step():
+    assert step_for_event("request_accepted") == WorkflowStep.REQUEST_ACCEPTANCE
+    assert step_for_event("context_prepared") == WorkflowStep.CONTEXT_PREPARATION
+    assert step_for_event("narrative_generated") == WorkflowStep.NARRATIVE_GENERATION
+    assert step_for_event("story_saved") == WorkflowStep.STORY_PERSISTENCE
+    assert step_for_event("provider_call_succeeded") == WorkflowStep.PROVIDER_INVOCATION
+    assert step_for_event("quality_gate_failed") == WorkflowStep.NARRATIVE_GENERATION
+    assert step_for_event("cover_image_failed") == WorkflowStep.IMAGE_GENERATION
+    assert step_for_event("audio_succeeded") == WorkflowStep.AUDIO_GENERATION
+    assert step_for_event("generation_canceled") == WorkflowStep.CANCELLATION
+    assert step_for_event("generation_stale_failed") == WorkflowStep.STALE_RECOVERY
+    assert step_for_event("future_event") == WorkflowStep.UNKNOWN
+
+
+def test_event_type_maps_to_standard_artifact():
+    assert artifact_for_event("narrative_generated") == ArtifactKind.STORY_TEXT
+    assert artifact_for_event("quality_gate_failed") == ArtifactKind.STORY_TEXT
+    assert artifact_for_event("cover_image_succeeded") == ArtifactKind.COVER_IMAGE
+    assert artifact_for_event("storybook_page_image_failed") == ArtifactKind.PAGE_IMAGE
+    assert artifact_for_event("audio_cache_hit") == ArtifactKind.AUDIO
+    assert artifact_for_event("postprocessing_queued") == ArtifactKind.ACHIEVEMENT_MEMORY
+    assert artifact_for_event("request_accepted") == ArtifactKind.NONE
+
+
+def test_trace_metadata_adds_standard_fields_without_dropping_legacy_values():
+    metadata = normalize_trace_metadata(
+        "provider_call_failed",
+        {
+            "capability": "text",
+            "adapter": "demo",
+            "error": "timeout",
+        },
+        failure_category=FailureCategory.TIMEOUT,
+        retryable=True,
+    )
+
+    assert metadata["capability"] == "text"
+    assert metadata["adapter"] == "demo"
+    assert metadata["error"] == "timeout"
+    assert metadata["step"] == "provider_invocation"
+    assert metadata["artifact"] == "none"
+    assert metadata["failure_category"] == "timeout"
+    assert metadata["retryable"] is True
+    assert metadata["blocks_main_result"] is False
+
+
+def test_trace_metadata_respects_explicit_step_and_artifact():
+    metadata = normalize_trace_metadata(
+        "narrative_generated",
+        {"title": "小兔子的冒险"},
+        step=WorkflowStep.NARRATIVE_GENERATION,
+        artifact=ArtifactKind.STORYBOOK_PAGES,
+        blocks_main_result=True,
+    )
+
+    assert metadata["title"] == "小兔子的冒险"
+    assert metadata["step"] == "narrative_generation"
+    assert metadata["artifact"] == "storybook_pages"
+    assert metadata["blocks_main_result"] is True
+
+
+def test_story_plan_without_assets_snapshot():
+    assert build_story_plan(generate_images=False).to_snapshot() == {
+        "mode": "story",
+        "tasks": [
+            {
+                "key": "prepare_context",
+                "step": "context_preparation",
+                "artifact": "none",
+                "required": True,
+                "recoverable": False,
+            },
+            {
+                "key": "generate_narrative",
+                "step": "narrative_generation",
+                "artifact": "story_text",
+                "required": True,
+                "recoverable": False,
+            },
+            {
+                "key": "persist_story",
+                "step": "story_persistence",
+                "artifact": "story_text",
+                "required": True,
+                "recoverable": False,
+            },
+            {
+                "key": "queue_postprocessing",
+                "step": "postprocessing",
+                "artifact": "achievement_memory",
+                "required": False,
+                "recoverable": True,
+            },
+            {
+                "key": "complete_generation",
+                "step": "completion",
+                "artifact": "none",
+                "required": True,
+                "recoverable": False,
+            },
+        ],
+    }
+
+
+def test_story_plan_with_assets_marks_cover_recoverable():
+    plan = build_story_plan(generate_images=True).to_snapshot()
+
+    assert plan["mode"] == "story_with_assets"
+    assert plan["tasks"][3] == {
+        "key": "generate_cover_image",
+        "step": "image_generation",
+        "artifact": "cover_image",
+        "required": False,
+        "recoverable": True,
+    }
+
+
+def test_storybook_plan_with_images_marks_storybook_images_recoverable():
+    plan = build_storybook_plan(generate_images=True).to_snapshot()
+
+    assert plan["mode"] == "storybook"
+    assert [task["key"] for task in plan["tasks"]] == [
+        "prepare_context",
+        "generate_storybook_pages",
+        "generate_storybook_images",
+        "persist_storybook",
+        "queue_postprocessing",
+        "complete_generation",
+    ]
+    assert plan["tasks"][2]["artifact"] == "image"
+    assert plan["tasks"][2]["recoverable"] is True
+
+
+def test_asset_retry_plan_deduplicates_assets():
+    plan = build_asset_plan(output_mode="asset_retry", assets=["image", "audio", "image"])
+
+    assert plan.to_snapshot() == {
+        "mode": "asset_retry",
+        "tasks": [
+            {
+                "key": "start_asset_retry",
+                "step": "asset_retry",
+                "artifact": "none",
+                "required": True,
+                "recoverable": False,
+            },
+            {
+                "key": "complete_image_asset",
+                "step": "image_generation",
+                "artifact": "image",
+                "required": False,
+                "recoverable": True,
+            },
+            {
+                "key": "complete_audio_asset",
+                "step": "audio_generation",
+                "artifact": "audio",
+                "required": False,
+                "recoverable": True,
+            },
+            {
+                "key": "complete_asset_retry",
+                "step": "asset_retry",
+                "artifact": "none",
+                "required": True,
+                "recoverable": False,
+            },
+        ],
+    }
+
+
+def test_story_quality_gate_accepts_complete_child_safe_story():
+    validate_story_output(
+        StoryOutput(
+            mode="generated",
+            title="小兔子的月光花园",
+            story_text="小兔子在花园里学会了和朋友轮流分享水壶。",
+            cover_prompt_suggestion="A gentle moonlit garden with a rabbit",
+        )
+    )
+
+
+def test_story_quality_gate_rejects_missing_story_text():
+    output = StoryOutput(
+        mode="generated",
+        title="空白故事",
+        story_text="",
+        cover_prompt_suggestion="A cover",
+    )
+
+    try:
+        validate_story_output(output)
+    except QualityGateError as exc:
+        assert [issue.code.value for issue in exc.issues] == ["missing_story_text"]
+        assert exc.to_metadata()["issues"][0]["field"] == "story_text"
+    else:
+        raise AssertionError("Expected QualityGateError")
+
+
+def test_story_quality_gate_rejects_obviously_unsafe_child_content():
+    output = StoryOutput(
+        mode="generated",
+        title="危险词测试",
+        story_text="这个故事包含血腥场景。",
+        cover_prompt_suggestion="A cover",
+    )
+
+    try:
+        validate_story_output(output)
+    except QualityGateError as exc:
+        assert [issue.code.value for issue in exc.issues] == ["unsafe_child_content"]
+        assert exc.to_metadata()["issues"][0]["failure_category"] == "safety_error"
+    else:
+        raise AssertionError("Expected QualityGateError")
+
+
+def test_storybook_quality_gate_rejects_duplicate_page_number():
+    storybook = Storybook(
+        title="森林绘本",
+        main_character="小兔子",
+        art_style="水彩",
+        cover_prompt="A forest cover",
+        pages=[
+            StorybookPage(page_number=1, text="第一页。", image_prompt="page 1"),
+            StorybookPage(page_number=1, text="第二页。", image_prompt="page 2"),
+        ],
+    )
+
+    try:
+        validate_storybook_output(storybook)
+    except QualityGateError as exc:
+        assert [issue.code.value for issue in exc.issues] == [
+            "invalid_storybook_page_number"
+        ]
+        assert exc.to_metadata()["issues"][0]["field"] == "pages[1].page_number"
+    else:
+        raise AssertionError("Expected QualityGateError")
+
+
+@pytest.mark.asyncio
+async def test_trace_recorder_persists_standard_metadata(db_session, test_user):
+    job = await create_generation_job(
+        db_session,
+        user_id=test_user.id,
+        output_mode="story",
+        input_type="keywords",
+        request_payload={"data": "小兔子"},
+    )
+
+    event = await TraceRecorder(db_session).record_step(
+        job=job,
+        event_type="provider_call_failed",
+        status="failed",
+        metadata={
+            "capability": "text",
+            "adapter": "demo",
+            "error": "timeout",
+        },
+        failure_category=FailureCategory.TIMEOUT,
+        retryable=True,
+    )
+
+    assert event is not None
+    events = (
+        await db_session.execute(
+            select(GenerationJobEvent)
+            .where(GenerationJobEvent.job_id == job.id)
+            .order_by(GenerationJobEvent.id)
+        )
+    ).scalars().all()
+
+    assert [item.event_type for item in events] == [
+        "request_accepted",
+        "provider_call_failed",
+    ]
+    metadata = events[1].event_metadata
+    assert metadata["capability"] == "text"
+    assert metadata["adapter"] == "demo"
+    assert metadata["step"] == "provider_invocation"
+    assert metadata["artifact"] == "none"
+    assert metadata["failure_category"] == "timeout"
+    assert metadata["retryable"] is True
+
+
+@pytest.mark.asyncio
+async def test_trace_recorder_ignores_missing_job(db_session):
+    event = await TraceRecorder(db_session).record_step(
+        job=None,
+        event_type="context_prepared",
+        status="succeeded",
+    )
+
+    assert event is None
+
+
+@pytest.mark.asyncio
+async def test_execution_control_cancels_job_at_safe_checkpoint(
+    db_session,
+    test_user,
+    test_story,
+):
+    job = await create_generation_job(
+        db_session,
+        user_id=test_user.id,
+        output_mode="story",
+        input_type="keywords",
+        request_payload={"data": "小兔子"},
+        story_id=test_story.id,
+    )
+    await record_generation_event(
+        db_session,
+        job=job,
+        story_id=test_story.id,
+        event_type="cancel_requested",
+        status="running",
+        message="Cancellation requested.",
+    )
+
+    with pytest.raises(GenerationJobCanceledError):
+        await ExecutionControl(db_session).stop_if_cancel_requested(
+            job=job,
+            story=test_story,
+        )
+
+    refreshed_job = (
+        await db_session.execute(select(GenerationJob).where(GenerationJob.id == job.id))
+    ).scalar_one()
+    assert refreshed_job.status == "canceled"
+    assert refreshed_job.current_step == "generation_canceled"
+    assert refreshed_job.error_message == "Generation canceled by user."
+
+    events = (
+        await db_session.execute(
+            select(GenerationJobEvent)
+            .where(GenerationJobEvent.job_id == job.id)
+            .order_by(GenerationJobEvent.id)
+        )
+    ).scalars().all()
+    assert [item.event_type for item in events] == [
+        "request_accepted",
+        "cancel_requested",
+        "generation_canceled",
+    ]

docs/planning/harness-stage-0-report.md

@@ -0,0 +1,111 @@
+# Harness Engineering 改造阶段 0 报告
+
+**阶段**: 0 - 设计与基线  
+**日期**: 2026-06-21  
+**状态**: 已完成  
+**范围**: 技术设计、阶段拆解、最小任务、验收标准  
+
+---
+
+## 1. 本阶段目标
+
+本阶段不修改业务代码，目标是先建立 harness engineering 改造的执行基线：
+
+- 明确这次改造不是引入外部工作流引擎，也不是重写项目。
+- 确认现有统一生成工作流的能力边界。
+- 设计 Generation Harness Runtime 的目标架构。
+- 把后续工作拆成可执行、可验证、可报告的阶段。
+
+## 2. 已完成工作
+
+- 阅读并对齐现有统一生成 PRD：`docs/product/unified-generation-workflow-prd.md`
+- 阅读现有架构说明：`docs/technical/architecture.md`
+- 阅读现有 job/event 说明：`docs/technical/generation-job-state.md`
+- 阅读 Provider 路由说明：`docs/technical/provider-routing.md`
+- 检查当前生成链路实现：
+  - `backend/app/services/story_service.py`
+  - `backend/app/services/generation_jobs.py`
+  - `backend/app/services/provider_router.py`
+  - `backend/app/tasks/generation_workflow.py`
+- 检查当前关键测试：
+  - `backend/tests/test_generation_jobs.py`
+  - `backend/tests/test_stories.py`
+- 新增技术设计文档：
+  - `docs/technical/harness-engineering-modernization.md`
+
+## 3. 核心结论
+
+DreamWeaver 已经具备 harness engineering 的雏形，不需要从零开始。
+
+当前最有价值的改造路径是：
+
+1. 先抽出 harness 基础类型、trace recorder 和 execution control。
+2. 再拆资产工作流。
+3. 然后引入显式 workflow plan。
+4. 最后补 quality gates、trace analytics 和前端增量展示。
+
+第一阶段应避免大改数据库、API 和前端，先保证内部边界更清楚，并让现有测试继续通过。
+
+## 4. 发现的现状问题
+
+| 问题 | 影响 | 后续阶段 |
+| --- | --- | --- |
+| `story_service` 同时负责业务流程、事件记录、取消检查、资产补全和响应构造 | 文件职责偏重，后续扩展容易继续堆叠 | 阶段 1、2、3 |
+| event type 已经丰富，但缺少标准 step/artifact/failure category | 可观测性有数据，但分析语义还不稳定 | 阶段 1、5 |
+| Provider trace 已落库，但还没有纳入统一 runtime 语义 | 调用层和产品步骤之间缺少统一映射 | 阶段 1、5 |
+| 输出质量主要依赖 adapter 和 schema | 儿童内容质量、结构完整性和安全门还不够显式 | 阶段 4 |
+| 资产工作流 helper 已抽出一部分，但仍在 `story_service` 内 | 重试、后台补全、同步兼容路径仍有重复风险 | 阶段 2 |
+
+## 5. 阶段 1 入口标准
+
+可以进入阶段 1，入口条件已满足：
+
+- 技术设计已存在。
+- 最小任务已经拆解。
+- 阶段 1 不需要产品澄清。
+- 阶段 1 不需要数据库迁移。
+- 阶段 1 有明确验证命令。
+
+阶段 1 第一批任务：
+
+| ID | 任务 |
+| --- | --- |
+| H1-1 | 新增 `app/services/harness/__init__.py` |
+| H1-2 | 新增 `types.py` 枚举和 event type 映射 |
+| H1-3 | 新增 `trace.py` 封装 job event 写入 |
+| H1-4 | 新增 `control.py` 封装取消检查 |
+| H1-5 | 替换 `story_service` 内部 helper 实现 |
+| H1-6 | 补 `tests/test_harness_runtime.py` |
+
+## 6. 验证
+
+本阶段为文档阶段，验证方式是文档审查和路径确认。
+
+已确认：
+
+- 设计文档放在 `docs/technical/`
+- 阶段报告放在 `docs/planning/`
+- 后续阶段有明确测试命令
+- 改造策略与现有统一生成 PRD 不冲突
+
+## 7. 风险
+
+| 风险 | 等级 | 处理 |
+| --- | --- | --- |
+| 过早拆 workflow 导致行为回归 | 高 | 阶段 1 不拆主流程，只抽基础支撑件 |
+| metadata 标准化影响前端 | 中 | 只新增字段，不删除旧字段 |
+| 文档太大但实现不跟进 | 中 | 每个阶段都产出报告并更新状态 |
+
+## 8. 下一步
+
+进入阶段 1：Harness 基础类型与事件封装。
+
+优先顺序：
+
+1. 新增 harness 包和纯类型定义。
+2. 增加单测锁定 event type 到 step 的映射。
+3. 新增 trace recorder，保持旧事件行为。
+4. 新增 execution control，保持取消行为。
+5. 替换 `story_service` 内部 helper 为代理调用。
+6. 运行阶段 1 验证命令并产出阶段 1 报告。
+

docs/planning/harness-stage-1-report.md

@@ -0,0 +1,122 @@
+# Harness Engineering 改造阶段 1 报告
+
+**阶段**: 1 - Harness 基础类型与事件封装  
+**日期**: 2026-06-21  
+**状态**: 已完成  
+**范围**: 后端 harness 包、标准类型、trace recorder、execution control、定向测试  
+
+---
+
+## 1. 本阶段目标
+
+本阶段目标是先建立 Generation Harness Runtime 的最低可用支撑件，不重排主生成流程，不修改数据库结构，不破坏现有 API。
+
+目标包括：
+
+- 新增标准 workflow step、artifact、failure category 类型。
+- 将现有 event type 映射到标准 step/artifact。
+- 封装 job event 写入，统一补齐标准 trace metadata。
+- 封装取消检查，保留当前安全检查点语义。
+- 增加单元测试，确保新支撑件可独立验证。
+
+## 2. 已完成工作
+
+### 新增文件
+
+- `backend/app/services/harness/__init__.py`
+- `backend/app/services/harness/types.py`
+- `backend/app/services/harness/trace.py`
+- `backend/app/services/harness/control.py`
+- `backend/tests/test_harness_runtime.py`
+
+### 修改文件
+
+- `backend/app/services/story_service.py`
+  - 保留 `_record_job_event_if_present` 和 `_stop_if_job_cancel_requested` 原函数名。
+  - 内部改为代理到 `TraceRecorder` 和 `ExecutionControl`。
+  - 将 `GenerationJobCanceledError` 移入 harness control 模块。
+
+- `backend/app/services/provider_router.py`
+  - Provider 调用事件改为通过 `TraceRecorder` 写入。
+  - 保留原有 metadata 字段，例如 capability、adapter、strategy、latency、estimated cost、error。
+
+- `docs/technical/harness-engineering-modernization.md`
+  - 更新阶段 1 状态。
+
+## 3. 行为兼容性
+
+本阶段采用“只新增标准字段，不删除旧字段”的策略。
+
+新增写入到 `generation_job_events.event_metadata` 的标准字段包括：
+
+- `step`
+- `artifact`
+- `failure_category`
+- `retryable`
+- `blocks_main_result`
+
+现有事件顺序、event type、status、message 和既有 metadata 字段保持兼容。
+
+## 4. 验证结果
+
+已执行：
+
+```bash
+cd backend
+.venv/bin/python -m pytest tests/test_harness_runtime.py tests/test_generation_jobs.py
+.venv/bin/python -m ruff check app tests
+```
+
+结果：
+
+- `24 passed`
+- `ruff`: `All checks passed!`
+
+覆盖到的关键行为：
+
+- event type 到标准 workflow step 的映射。
+- event type 到 artifact 的映射。
+- trace metadata 不丢失旧字段。
+- TraceRecorder 能写入标准 metadata。
+- job 为 `None` 时 TraceRecorder 安全跳过。
+- ExecutionControl 能在 `cancel_requested` checkpoint 将 job 收敛为 `canceled`。
+- 现有 generation job、取消、重试、Provider 统计测试继续通过。
+
+## 5. 自审结论
+
+本阶段改动符合阶段 1 设计：
+
+- 没有引入外部框架。
+- 没有修改数据库迁移。
+- 没有修改 API schema。
+- 没有重排现有生成 workflow。
+- 没有删除旧 metadata 字段。
+- `story_service` 仍保留旧 helper 入口，降低后续阶段风险。
+
+## 6. 已知限制
+
+- 当前只有通过 `TraceRecorder` 写入的事件会自动带标准 metadata。直接调用 `record_generation_event` 的旧代码路径暂未全量迁移。
+- `failure_category` 目前只在显式传入时有具体值，Provider 错误自动分类留到后续阶段。
+- `AssetCompletionResult` 仍在 `story_service.py`，资产工作流拆分留到阶段 2。
+- `WorkflowPlan` 和执行器尚未实现，阶段 1 只完成运行时支撑件。
+
+## 7. 风险与处理
+
+| 风险 | 等级 | 当前处理 |
+| --- | --- | --- |
+| 新 metadata 影响前端 | 低 | 只新增字段，不删除字段 |
+| 取消语义回归 | 低 | `tests/test_generation_jobs.py` 已通过 |
+| Provider 聚合误算 | 低 | Provider 统计测试已通过 |
+| 直接调用 `record_generation_event` 的路径未标准化 | 中 | 后续阶段逐步迁移或在底层统一补齐 |
+
+## 8. 下一阶段建议
+
+进入阶段 2：资产工作流边界抽取。
+
+建议先做最小切片：
+
+1. 将 `AssetCompletionResult` 移到 harness 或 artifact workflow 模块，并保留兼容 import。
+2. 抽普通故事封面补全工作流，保持测试不变。
+3. 抽音频补全工作流，先覆盖缓存命中、生成成功、生成失败。
+4. 最后抽绘本图片工作流，因为它涉及并发生成和逐页事件顺序，风险略高。
+

docs/planning/harness-stage-2-report.md

@@ -0,0 +1,121 @@
+# Harness Engineering 改造阶段 2 报告
+
+**阶段**: 2 - 资产工作流边界抽取  
+**日期**: 2026-06-21  
+**状态**: 已完成主要目标  
+**范围**: 封面、音频、持久化绘本缺失图片补全工作流抽取  
+
+---
+
+## 1. 本阶段目标
+
+本阶段目标是将资产补全职责从 `story_service.py` 中抽出，迁入 harness runtime 的 artifact workflow 层，同时保留原有函数签名和外部行为。
+
+阶段 2 不修改数据库结构，不修改 API schema，不改变前端行为。
+
+## 2. 已完成工作
+
+### 新增和扩展文件
+
+- `backend/app/services/harness/artifacts.py`
+  - 新增 `AssetCompletionResult`
+  - 新增 `asset_result_metadata`
+
+- `backend/app/services/harness/asset_workflows.py`
+  - 新增 `complete_cover_image_asset`
+  - 新增 `read_cached_audio_asset`
+  - 新增 `complete_audio_asset`
+  - 新增 `get_storybook_pages_data`
+  - 新增 `build_storybook_error_message`
+  - 新增 `resolve_storybook_image_status`
+  - 新增 `complete_storybook_image_assets`
+
+### 修改文件
+
+- `backend/app/services/story_service.py`
+  - 移除本地 `AssetCompletionResult` 定义，改为从 harness artifacts 引入。
+  - `_complete_cover_image_asset` 改为代理到 harness asset workflow。
+  - `_read_cached_audio_asset` 改为代理到 harness asset workflow。
+  - `_complete_audio_asset` 改为代理到 harness asset workflow。
+  - `_complete_storybook_image_assets` 改为代理到 harness asset workflow。
+  - 绘本错误信息和图片状态推导 helper 改为代理到 harness asset workflow。
+
+## 3. 行为兼容性
+
+本阶段保留了 `story_service.py` 内原有私有 helper 名称，因此调用方不需要调整。
+
+保持兼容的行为包括：
+
+- 普通故事封面生成成功和失败语义。
+- 封面失败时主内容仍可读，并进入可重试状态。
+- 音频缓存命中、缓存缺失修复、TTS 成功和 TTS 失败语义。
+- 音频失败时可选择阻塞或非阻塞，取决于 `raise_on_failure`。
+- 持久化绘本缺失封面/分页插图补全语义。
+- 绘本逐页图片事件和完成事件 metadata。
+- `retryable_assets` 行为。
+
+## 4. 验证结果
+
+已执行：
+
+```bash
+cd backend
+.venv/bin/python -m pytest tests/test_harness_runtime.py tests/test_generation_jobs.py tests/test_stories.py tests/test_audio_cache.py
+.venv/bin/python -m ruff check app tests
+```
+
+结果：
+
+- `72 passed`
+- `ruff`: `All checks passed!`
+
+覆盖到的关键行为：
+
+- 统一生成 job 队列和 worker 持久化。
+- 资产重试 job 事件。
+- 普通故事封面生成与重试。
+- 绘本分页图片重试。
+- 音频缓存、生成、失败和清理。
+- Provider 调用事件和聚合。
+- job 取消、重试和卡住任务收敛。
+
+## 5. 自审结论
+
+本阶段符合设计目标：
+
+- 资产补全职责已从 `story_service` 主体中显著抽离。
+- 外部 API 和数据库模型未变。
+- 当前主要测试通过。
+- harness 层开始承载 artifact workflow，但仍通过依赖注入函数调用 Provider 和文件缓存，便于测试与后续替换。
+
+## 6. 保留到后续阶段的内容
+
+首次绘本生成前的并发图片生成函数 `_generate_storybook_image_assets` 仍保留在 `story_service.py`。
+
+保留原因：
+
+- 它发生在绘本主记录持久化之前。
+- 它与“生成绘本结构 -> 可选并发生成图片 -> 持久化故事”的执行计划强相关。
+- 更适合在阶段 3 引入 `WorkflowPlan` 时一起整理，而不是在阶段 2 单独迁移。
+
+## 7. 风险与处理
+
+| 风险 | 等级 | 当前处理 |
+| --- | --- | --- |
+| 资产工作流迁移改变事件顺序 | 低 | generation job 和 story 测试已通过 |
+| 音频缓存修复逻辑回归 | 低 | `test_audio_cache.py` 已通过 |
+| 绘本图片补全状态误判 | 低 | 绘本重试测试已通过 |
+| 首次绘本并发图片仍在 service 内 | 中 | 阶段 3 处理 |
+
+## 8. 下一阶段建议
+
+进入阶段 3：Workflow Plan 与执行器。
+
+建议切片：
+
+1. 定义 `WorkflowPlan`、`WorkflowTask` 和模式枚举，不接入主流程。
+2. 为普通故事、完整故事、绘本、资产任务生成 plan 快照测试。
+3. 将 `_generate_generation_service_with_job` 的分支逐步迁移到 plan 构建。
+4. 处理首次绘本并发图片生成，把它纳入 storybook plan 的 asset step。
+5. 保持 `/api/generations` 和现有 job event 顺序兼容。
+

docs/planning/harness-stage-3-report.md

@@ -0,0 +1,121 @@
+# Harness Engineering 改造阶段 3 报告
+
+**阶段**: 3 - Workflow Plan 与执行器  
+**日期**: 2026-06-21  
+**状态**: 已完成计划建模基线，执行器接管未启用  
+**范围**: 纯 WorkflowPlan 建模、计划快照测试  
+
+---
+
+## 1. 本阶段目标
+
+阶段 3 的完整目标是引入显式 `WorkflowPlan`，逐步减少 `_generate_generation_service_with_job` 中的分支逻辑。
+
+本次完成了最小安全切片：
+
+- 定义 plan 类型和 task 类型。
+- 为普通故事、带封面故事、绘本、资产任务生成计划。
+- 用快照测试锁定计划形状。
+- 暂不改变实际执行流，避免事件顺序和前端时间线发生非必要变化。
+
+## 2. 已完成工作
+
+### 新增文件
+
+- `backend/app/services/harness/plans.py`
+
+### 新增能力
+
+- `WorkflowMode`
+  - `story`
+  - `story_with_assets`
+  - `storybook`
+  - `asset_generation`
+  - `asset_retry`
+
+- `WorkflowTask`
+  - `key`
+  - `step`
+  - `artifact`
+  - `required`
+  - `recoverable`
+
+- `WorkflowPlan`
+  - `mode`
+  - `tasks`
+  - `to_snapshot()`
+
+- plan builder
+  - `build_story_plan(generate_images=...)`
+  - `build_storybook_plan(generate_images=...)`
+  - `build_asset_plan(output_mode=..., assets=...)`
+
+### 修改文件
+
+- `backend/tests/test_harness_runtime.py`
+  - 增加普通故事计划快照。
+  - 增加带封面故事计划快照。
+  - 增加绘本带图片计划快照。
+  - 增加资产重试计划去重测试。
+
+## 3. 为什么没有接入执行器
+
+本阶段有意没有新增运行时事件，例如 `workflow_planned`，也没有让 plan 接管 `_generate_generation_service_with_job`。
+
+原因：
+
+- 新 event type 会改变前端生成轨迹时间线，需要同步前端 label 和 progress 映射。
+- 当前生成 job 测试已经严格断言事件顺序。
+- 直接接管执行器会同时触碰 story、storybook、asset_generation、asset_retry 四条路径，风险偏高。
+- 先稳定 plan snapshot，可以让后续迁移按任务级别逐步推进。
+
+## 4. 验证结果
+
+已执行：
+
+```bash
+cd backend
+.venv/bin/python -m pytest tests/test_harness_runtime.py tests/test_generation_jobs.py
+.venv/bin/python -m ruff check app tests
+```
+
+结果：
+
+- `28 passed`
+- `ruff`: `All checks passed!`
+
+阶段 3 的计划建模未改变业务执行流，因此完整后端行为仍由阶段 2 的完整测试结果兜底。
+
+## 5. 自审结论
+
+本阶段符合“小步可验证”原则：
+
+- 新增模块不依赖数据库、FastAPI 或 Provider。
+- plan 只描述 workflow 形状，不执行副作用。
+- 所有任务均可 JSON snapshot，后续可写入 trace metadata 或用于执行器。
+- 没有影响现有 API、job event 顺序或前端。
+
+## 6. 保留到后续的内容
+
+| 内容 | 建议处理 |
+| --- | --- |
+| 执行器接管 `_generate_generation_service_with_job` | 分 story、storybook、asset 三次迁移 |
+| 首次绘本生成前并发图片生成 | 跟 storybook plan 的 image task 一起迁移 |
+| `workflow_planned` 事件 | 等前端 label 和 progress 映射准备好后再加入 |
+| plan 与 trace metadata 关联 | 先在 execution context 内部使用，再决定是否落库 |
+
+## 7. 下一阶段建议
+
+下一步有两条可选路线：
+
+1. **继续阶段 3B：执行器小步接管**
+   - 先让普通故事不带图片路径使用 plan。
+   - 再迁移普通故事带图片路径。
+   - 最后迁移绘本和资产任务。
+
+2. **进入阶段 4：Quality Gates**
+   - 在不改变执行器的前提下，为 Provider 输出增加确定性校验。
+   - 这条路线风险更低，对儿童内容质量收益更直接。
+
+建议优先做阶段 4 的低风险质量门，然后再回来做阶段 3B 的执行器迁移。
+

docs/planning/harness-stage-4-report.md

@@ -0,0 +1,140 @@
+# Harness Engineering 改造阶段 4 报告
+
+**阶段**: 4 - Quality Gates 与输出验证  
+**日期**: 2026-06-21  
+**状态**: 已完成确定性质量门  
+**范围**: 文本故事和绘本结构输出校验、质量门失败事件、测试验证  
+
+---
+
+## 1. 本阶段目标
+
+阶段 4 的目标是在 Provider 输出进入持久化之前增加低成本、确定性的质量门。
+
+本阶段不调用额外 AI 模型，不增加外部服务成本，只做结构完整性和明显儿童安全风险检查。
+
+## 2. 已完成工作
+
+### 新增文件
+
+- `backend/app/services/harness/quality_gates.py`
+
+### 新增能力
+
+- `QualityGateCode`
+  - `missing_title`
+  - `missing_story_text`
+  - `missing_cover_prompt`
+  - `missing_storybook_page`
+  - `invalid_storybook_page_number`
+  - `missing_storybook_page_text`
+  - `unsafe_child_content`
+
+- `QualityGateIssue`
+  - 稳定 code
+  - 中文 message
+  - `failure_category`
+  - field
+
+- `QualityGateError`
+  - 聚合多个 issue
+  - 可输出 JSON-safe metadata
+
+- `validate_story_output`
+  - 检查标题
+  - 检查正文
+  - 检查封面 prompt
+  - 检查明显不适合 3-8 岁儿童的风险词
+
+- `validate_storybook_output`
+  - 检查标题
+  - 检查至少一页
+  - 检查页码有效且不重复
+  - 检查每页正文
+  - 检查明显不适合 3-8 岁儿童的风险词
+
+### 修改文件
+
+- `backend/app/services/story_service.py`
+  - 文本故事 Provider 输出后、持久化前执行 `validate_story_output`。
+  - 绘本 Provider 输出后、图片生成和持久化前执行 `validate_storybook_output`。
+  - 质量门失败会写入 `quality_gate_failed` job event。
+  - 质量门失败不会落库故事主记录。
+
+- `backend/app/services/harness/types.py`
+  - `quality_gate_failed` 映射到 `narrative_generation` step。
+  - `quality_gate_failed` 映射到 `story_text` artifact。
+
+- `backend/tests/test_harness_runtime.py`
+  - 增加质量门纯函数测试。
+
+- `backend/tests/test_generation_jobs.py`
+  - 增加 worker 质量门失败测试，确认 story 不落库、job failed、事件可解释。
+
+## 3. 行为语义
+
+质量门失败属于生成失败，而不是降级完成。
+
+原因：
+
+- 文本故事正文或绘本页结构是 blocking artifact。
+- 如果主内容本身不合格，系统不能保存为可读故事。
+- 图片、音频等 recoverable artifact 失败仍按原有 `degraded_completed` 或可重试逻辑处理。
+
+## 4. 验证结果
+
+已执行：
+
+```bash
+cd backend
+.venv/bin/python -m pytest tests/test_harness_runtime.py tests/test_generation_jobs.py
+.venv/bin/python -m ruff check app tests
+.venv/bin/python -m pytest
+```
+
+结果：
+
+- 定向测试：`33 passed`
+- 完整后端测试：`138 passed`
+- `ruff`: `All checks passed!`
+
+覆盖到的关键行为：
+
+- 质量门接受完整、安全的儿童故事。
+- 质量门拒绝空正文。
+- 质量门拒绝明显不适合儿童的风险词。
+- 质量门拒绝绘本重复页码。
+- worker 中质量门失败会写入 `quality_gate_failed`。
+- 质量门失败不会持久化 story。
+- 现有所有后端测试继续通过。
+
+## 5. 自审结论
+
+本阶段符合设计目标：
+
+- 没有引入额外 AI 调用。
+- 没有引入新依赖。
+- 没有改变 API schema。
+- 没有改变图片、音频资产失败降级语义。
+- 对儿童内容质量和结构完整性有了第一层确定性保护。
+
+## 6. 已知限制
+
+| 限制 | 后续建议 |
+| --- | --- |
+| 儿童安全词表很保守，只覆盖明显风险词 | 后续可接入可配置词表或轻量安全审核 Provider |
+| 当前 `quality_gate_failed` artifact 固定映射到 `story_text` | 后续可根据 story/storybook mode 写入更精确 artifact |
+| 质量门失败文案目前偏技术 | 后续可为前端增加更友好的用户提示 |
+| 未做模型评审式质量评分 | 先保留，避免增加成本和不稳定性 |
+
+## 7. 下一阶段建议
+
+进入阶段 5：Trace Analytics 与前端增量展示。
+
+建议切片：
+
+1. 后端 Provider/Job 聚合支持 `failure_category` 统计。
+2. 前端生成轨迹显示 `step` 和 `artifact` 的中文标签。
+3. 管理端 Provider dashboard 展示 failure category 聚合。
+4. 更新 smoke 脚本检查标准 metadata。
+

docs/technical/harness-engineering-modernization.md

@@ -0,0 +1,493 @@
+# Harness Engineering 架构改造技术设计
+
+**项目**: DreamWeaver 梦语织机  
+**版本**: 0.1  
+**日期**: 2026-06-21  
+**状态**: 阶段 0 已建立设计基线  
+**作者**: Codex  
+
+---
+
+## 1. 背景
+
+DreamWeaver 当前已经完成统一生成工作流的第一轮落地：`POST /api/generations` 会创建 `generation_jobs`，后台 worker 执行故事或绘本生成，`generation_job_events` 记录关键过程，前端通过 job 查询和故事状态展示进度、失败与重试入口。
+
+现有架构已经具备 harness engineering 的雏形：
+
+- `story_service` 负责上下文准备、主内容生成、故事落库、资产补全、状态同步和任务收敛。
+- `generation_jobs` 负责 job/event、进度摘要、取消、重试和 Provider 聚合。
+- `provider_router` 负责 Provider 选择、failover、熔断、成本和调用事件。
+- `story_status` 负责把文本、图片、音频状态推导为统一故事状态。
+
+当前主要问题不是缺少能力，而是生成运行时控制逻辑分散在多个 service 内。取消检查、事件记录、资产恢复、Provider 轨迹、失败分类和质量校验还没有形成显式的运行时边界。
+
+本设计的目标，是把现有“隐性 harness”升级为可观测、可恢复、可验证、可演进的 Generation Harness Runtime，同时保留当前 API、数据库和前端主行为。
+
+## 2. 目标
+
+### 2.1 产品目标
+
+- 家长提交故事或绘本生成后，能获得稳定、可解释、可恢复的结果。
+- 主内容生成成功后，即使图片或音频失败，也不影响阅读。
+- 用户能清楚看到任务步骤、失败原因和可重试资产。
+- 后续新增语音共创、更多内容模式或新资产类型时，复用同一套运行时模型。
+
+### 2.2 工程目标
+
+- 把 `story_service` 中的运行时控制职责抽到 harness 层。
+- 让 workflow step、artifact、trace、failure category 成为一等概念。
+- 保持 `/api/generations`、旧兼容接口、现有状态字段和主要测试行为不破坏。
+- 优先做渐进式重构，不引入复杂工作流引擎，不进行大爆炸重写。
+- 每个大阶段都产出阶段报告，包含实现、审查、验证和风险。
+
+### 2.3 非目标
+
+- 本轮不引入 Temporal、Dagster、LangGraph 等外部工作流引擎。
+- 本轮不彻底重做数据库结构。
+- 本轮不废弃旧生成接口，只继续保持兼容层指向统一入口。
+- 本轮不把 DreamWeaver 抽象成通用 agent 平台，所有抽象必须服务儿童故事生成业务。
+- 本轮不要求一次性完成所有 eval、质量门和 replay 能力。
+
+## 3. 架构原则
+
+1. **主内容优先可读**  
+   文本故事或绘本结构是 blocking artifact；封面、分页插图、音频是 recoverable artifact。
+
+2. **API 稳定优先**  
+   先重构内部边界，再考虑扩展响应字段。现有前端、smoke、测试不应被第一阶段打断。
+
+3. **事件结构稳定**  
+   继续复用 `generation_job_events`，但逐步标准化 metadata，避免每个调用点随手定义不同结构。
+
+4. **Provider 不等于产品能力**  
+   Provider 只是 tool invocation 的实现。产品能力应由 capability、workflow step、artifact 和 recovery policy 共同定义。
+
+5. **小步可验证**  
+   每个最小任务都必须能通过单测、局部测试或文档审查验证。
+
+## 4. 目标架构
+
+```mermaid
+flowchart TB
+  API["FastAPI API 层"] --> COMMAND["Generation Command"]
+  COMMAND --> HARNESS["Generation Harness Runtime"]
+
+  HARNESS --> CTX["Context Builder<br/>档案 / 宇宙 / 记忆 / 输入规范化"]
+  HARNESS --> PLAN["Workflow Plan<br/>story / storybook / asset_generation / asset_retry"]
+  HARNESS --> CONTROL["Execution Control<br/>取消 / 超时收敛 / 安全检查点"]
+  HARNESS --> TRACE["Trace Recorder<br/>job events / step metadata / provider trace"]
+  HARNESS --> ARTIFACT["Artifact Workflows<br/>story_text / storybook_pages / image / audio"]
+  HARNESS --> GUARD["Quality Gates<br/>schema / 儿童安全 / 内容完整性"]
+
+  ARTIFACT --> ROUTER["Provider Router<br/>策略 / failover / 熔断 / 成本"]
+  ROUTER --> ADAPTERS["Provider Adapters"]
+  HARNESS --> STATE["State Store<br/>stories / generation_jobs / generation_job_events"]
+  STATE --> FE["Vue 前端进度 / 详情 / 重试"]
+```
+
+## 5. 运行时核心概念
+
+### 5.1 Generation Command
+
+表示一次用户意图，来源包括：
+
+- `POST /api/generations`
+- `POST /api/generations/{story_id}/retry-assets`
+- `POST /api/generations/jobs/{job_id}/retry`
+- 旧兼容接口产生的同步生成调用
+
+标准字段：
+
+| 字段 | 说明 |
+| --- | --- |
+| `output_mode` | `story`、`storybook`、`asset_generation`、`asset_retry` |
+| `input_type` | `keywords`、`full_story`、`image`、`audio` 或资产组合 |
+| `user_id` | 当前用户 |
+| `story_id` | 已有故事 ID，可为空 |
+| `request_payload` | 原始请求的 JSON 安全快照 |
+
+### 5.2 Workflow Step
+
+第一阶段先将现有 event type 映射为标准 step，不立即改库：
+
+| Step | 当前事件 | 是否阻塞主内容 |
+| --- | --- | --- |
+| `request_acceptance` | `request_accepted`、`retry_queued` | 是 |
+| `worker_start` | `worker_started` | 是 |
+| `context_preparation` | `context_prepared` | 是 |
+| `narrative_generation` | `narrative_generated` | 是 |
+| `story_persistence` | `story_saved` | 是 |
+| `image_generation` | `cover_image_*`、`storybook_*image*` | 否 |
+| `audio_generation` | `audio_*` | 否 |
+| `postprocessing` | `postprocessing_queued` | 否 |
+| `completion` | `generation_completed`、`asset_*_completed` | 是 |
+| `cancellation` | `cancel_requested`、`generation_canceled` | 是 |
+| `stale_recovery` | `generation_stale_failed` | 是 |
+
+### 5.3 Artifact
+
+| Artifact | 来源 | 状态字段 | 恢复策略 |
+| --- | --- | --- | --- |
+| `story_text` | text provider | `text_status` | 失败则 job failed |
+| `storybook_pages` | storybook provider | `text_status` | 失败则 job failed |
+| `cover_image` | image provider | `image_status` | 失败后 `degraded_completed`，可重试 |
+| `page_image` | image provider | `image_status` | 部分页失败后 `degraded_completed`，可重试 |
+| `audio` | tts provider + file cache | `audio_status` | 失败后 `degraded_completed`，可重试 |
+| `achievement_memory` | Celery 后处理 | 事件记录 | 失败不影响主内容 |
+
+### 5.4 Failure Category
+
+第一阶段先在代码中定义枚举和 metadata 规范；后续逐步写入事件：
+
+| Category | 说明 |
+| --- | --- |
+| `provider_error` | 外部 Provider 返回失败或不可用 |
+| `schema_error` | Provider 输出无法解析或字段不完整 |
+| `safety_error` | 儿童安全或内容安全校验失败 |
+| `timeout` | 调用超时或 job 超时 |
+| `canceled` | 用户取消 |
+| `stale_job` | 后台任务卡住后被系统收敛 |
+| `storage_error` | 数据库、文件缓存或持久化失败 |
+| `validation_error` | 用户输入、档案或宇宙校验失败 |
+| `unknown_error` | 未归类错误 |
+
+### 5.5 Trace Metadata
+
+标准 event metadata 应逐步包含：
+
+```json
+{
+  "step": "narrative_generation",
+  "artifact": "story_text",
+  "capability": "text",
+  "adapter": "demo",
+  "provider_id": null,
+  "strategy": "priority",
+  "latency_ms": 42,
+  "estimated_cost_usd": 0.01,
+  "failure_category": null,
+  "error": null,
+  "retryable": false,
+  "blocks_main_result": true
+}
+```
+
+短期兼容要求：
+
+- 不删除现有 metadata 字段。
+- 新增字段必须向后兼容。
+- 前端仍可使用当前 `event_type`、`status`、`message`、`event_metadata`。
+
+## 6. 模块设计
+
+### 6.1 `app/services/harness/types.py`
+
+新增纯类型模块，不依赖数据库。
+
+职责：
+
+- 定义 `WorkflowStep`
+- 定义 `ArtifactKind`
+- 定义 `FailureCategory`
+- 定义 `StepStatus`
+- 定义 `TraceMetadata`
+- 定义从旧 event type 到标准 step 的映射函数
+
+验收：
+
+- 单测覆盖 event type 到 step 的映射。
+- 未知 event type 映射到 `unknown` 或保守默认，不抛出非预期异常。
+
+### 6.2 `app/services/harness/trace.py`
+
+封装 job event 写入。
+
+职责：
+
+- 提供 `TraceRecorder.record_step(...)`
+- 提供 `TraceRecorder.record_provider_call(...)`
+- 统一补齐 `step`、`artifact`、`failure_category`、`retryable`、`blocks_main_result`
+- 内部继续调用现有 `record_generation_event`
+
+验收：
+
+- 现有 `generation_job_events` 行为保持。
+- 新事件 metadata 含标准字段。
+- job 为空时安全跳过，兼容旧同步接口。
+
+### 6.3 `app/services/harness/control.py`
+
+封装执行控制。
+
+职责：
+
+- 提供 `ExecutionControl.stop_if_cancel_requested(...)`
+- 保留现有取消语义和 `GenerationJobCanceledError`
+- 后续可扩展 step timeout、checkpoint、stale recovery
+
+验收：
+
+- 取消中的 job 仍被标记为 `canceled`。
+- 现有取消测试继续通过。
+
+### 6.4 `app/services/harness/artifacts.py`
+
+第二阶段再拆。第一阶段先保留 `story_service` 中的资产函数，只把共享结果类型移动或桥接。
+
+职责：
+
+- 表达 `AssetCompletionResult`
+- 后续承载封面、绘本插图、音频工作流
+
+验收：
+
+- 资产重试行为不变。
+- `retryable_assets` 行为不变。
+
+### 6.5 `story_service` 改造方式
+
+第一阶段仅做低风险替换：
+
+- `_record_job_event_if_present` 代理到 `TraceRecorder`
+- `_stop_if_job_cancel_requested` 代理到 `ExecutionControl`
+- `AssetCompletionResult` 可先留在原文件，第二阶段再移动
+- 不重写 `generate_generation_service`、`run_generation_job_service` 主流程
+
+第二阶段再拆分：
+
+- `story_generation_workflow.py`
+- `storybook_generation_workflow.py`
+- `asset_generation_workflow.py`
+- `asset_retry_workflow.py`
+
+## 7. 阶段计划
+
+### 阶段 0: 设计与基线
+
+目标：
+
+- 产出本技术设计。
+- 产出阶段 0 报告。
+- 明确阶段拆解、验收标准和验证方式。
+
+最小任务：
+
+| ID | 任务 | 验收 |
+| --- | --- | --- |
+| H0-1 | 梳理现有统一生成 PRD、架构文档和测试 | 文档引用现有边界，不重复设计入口 |
+| H0-2 | 定义目标 runtime 架构 | 技术设计包含模块、数据、阶段计划 |
+| H0-3 | 拆分最小可执行任务 | 每个阶段有任务 ID 和验收标准 |
+| H0-4 | 建立阶段报告机制 | `docs/planning/` 下有阶段报告 |
+
+### 阶段 1: Harness 基础类型与事件封装
+
+目标：
+
+- 新增 harness 包。
+- 标准化 workflow step、artifact、failure category。
+- 用 `TraceRecorder` 封装事件写入。
+- 用 `ExecutionControl` 封装取消检查。
+
+最小任务：
+
+| ID | 任务 | 验收 |
+| --- | --- | --- |
+| H1-1 | 新增 `app/services/harness/__init__.py` | 后端 import 正常 |
+| H1-2 | 新增 `types.py` 枚举和映射 | 单测覆盖核心 event type |
+| H1-3 | 新增 `trace.py` | record 后 metadata 含 `step` |
+| H1-4 | 新增 `control.py` | 取消行为与旧逻辑一致 |
+| H1-5 | 替换 `story_service` 中事件和取消 helper 的内部实现 | 现有 API 行为不变 |
+| H1-6 | 补 `tests/test_harness_runtime.py` | 后端测试通过 |
+
+验证命令：
+
+```bash
+cd backend
+pytest tests/test_harness_runtime.py tests/test_generation_jobs.py
+ruff check app tests
+```
+
+阶段报告：
+
+- `docs/planning/harness-stage-1-report.md`
+
+### 阶段 2: 资产工作流边界抽取
+
+目标：
+
+- 将封面、绘本插图、音频补全从 `story_service` 中拆成 artifact workflow。
+- 保持当前 `StoryAssetStatus` 和 `sync_story_status` 语义。
+
+最小任务：
+
+| ID | 任务 | 验收 |
+| --- | --- | --- |
+| H2-1 | 移动或桥接 `AssetCompletionResult` | import 稳定 |
+| H2-2 | 抽普通故事封面工作流 | 封面生成、失败、重试测试通过 |
+| H2-3 | 抽绘本图片工作流 | 绘本逐页事件顺序不破坏 |
+| H2-4 | 抽音频工作流 | 音频缓存和失败状态测试通过 |
+| H2-5 | 补 artifact workflow 单测 | 资产相关测试通过 |
+
+验证命令：
+
+```bash
+cd backend
+pytest tests/test_stories.py tests/test_generation_jobs.py tests/test_audio_cache.py
+ruff check app tests
+```
+
+阶段报告：
+
+- `docs/planning/harness-stage-2-report.md`
+
+### 阶段 3: Workflow Plan 与执行器
+
+目标：
+
+- 用显式 `WorkflowPlan` 表达 story、storybook、asset_generation、asset_retry。
+- 将 `_generate_generation_service_with_job` 的分支压缩到计划构建和执行器。
+
+最小任务：
+
+| ID | 任务 | 验收 |
+| --- | --- | --- |
+| H3-1 | 定义 `WorkflowPlan` 和 `WorkflowTask` | 不依赖 FastAPI schema |
+| H3-2 | 为普通故事构建 plan | 不生成图片时步骤正确 |
+| H3-3 | 为完整故事构建 plan | 图片为 recoverable step |
+| H3-4 | 为绘本构建 plan | 绘本结构和图片步骤可区分 |
+| H3-5 | 为资产任务构建 plan | 重试和后台生成共用计划 |
+| H3-6 | 增加 plan 单测 | 核心模式计划快照稳定 |
+
+验证命令：
+
+```bash
+cd backend
+pytest tests/test_harness_runtime.py tests/test_generation_jobs.py tests/test_stories.py
+ruff check app tests
+```
+
+阶段报告：
+
+- `docs/planning/harness-stage-3-report.md`
+
+### 阶段 4: Quality Gates 与输出验证
+
+目标：
+
+- 在 Provider 输出进入持久化之前，加入低成本、确定性的质量门。
+- 后续可扩展模型评审，但第一轮避免额外 AI 成本。
+
+最小任务：
+
+| ID | 任务 | 验收 |
+| --- | --- | --- |
+| H4-1 | 定义 quality gate 接口 | 不绑定具体 Provider |
+| H4-2 | 文本故事完整性检查 | 标题、正文、封面 prompt 缺失可识别 |
+| H4-3 | 绘本结构检查 | 页数、页码、正文、图片 prompt 可识别 |
+| H4-4 | 儿童内容基础安全检查 | 明显不适龄词或空内容阻断 |
+| H4-5 | gate 失败写入 `failure_category` | job event 可解释 |
+
+验证命令：
+
+```bash
+cd backend
+pytest tests/test_harness_runtime.py tests/test_generation_jobs.py tests/test_stories.py
+ruff check app tests
+```
+
+阶段报告：
+
+- `docs/planning/harness-stage-4-report.md`
+
+### 阶段 5: Trace Analytics 与前端增量展示
+
+目标：
+
+- 前端继续消费现有 job/event，但可展示标准 step、artifact、failure category。
+- 管理端可按 failure category 聚合失败原因。
+
+最小任务：
+
+| ID | 任务 | 验收 |
+| --- | --- | --- |
+| H5-1 | 后端聚合支持标准 step/failure category | 旧字段兼容 |
+| H5-2 | 用户端生成轨迹展示 step 名称 | 移动端不溢出 |
+| H5-3 | 管理端 Provider dashboard 增加 failure category | 构建通过 |
+| H5-4 | 更新 smoke 脚本校验标准 metadata | demo smoke 通过 |
+
+验证命令：
+
+```bash
+cd backend
+pytest
+ruff check app tests
+cd ../frontend
+npm run build
+cd ../admin-frontend
+npm run build
+```
+
+阶段报告：
+
+- `docs/planning/harness-stage-5-report.md`
+
+## 8. 需求与验收
+
+### 功能需求
+
+| ID | 优先级 | 需求 | 验收标准 |
+| --- | --- | --- | --- |
+| FR-001 | MUST | 系统必须保留统一生成 API 行为 | `/api/generations` 测试继续通过 |
+| FR-002 | MUST | 系统必须有标准 workflow step 类型 | 核心 event type 可映射到 step |
+| FR-003 | MUST | 系统必须有标准 artifact 类型 | story、storybook、image、audio 可区分 |
+| FR-004 | MUST | 系统必须标准化 job event metadata | 新事件含 `step`，旧字段不删除 |
+| FR-005 | MUST | 用户取消语义必须保持 | 取消测试继续通过 |
+| FR-006 | SHOULD | Provider 调用应记录标准 trace 字段 | provider event 含 capability、adapter、latency、cost、step |
+| FR-007 | SHOULD | 资产工作流应从主 service 拆出 | `story_service` 行数和职责减少 |
+| FR-008 | SHOULD | 输出验证应在持久化前执行 | schema 缺失可被测试捕获 |
+| FR-009 | COULD | 前端展示标准 step/failure category | 构建通过且无布局溢出 |
+
+### 非功能需求
+
+| ID | 优先级 | 需求 | 验收标准 |
+| --- | --- | --- | --- |
+| NFR-001 | MUST | 向后兼容 | 现有测试和 smoke 主链路不破坏 |
+| NFR-002 | MUST | 可测试 | 每个新增 harness 模块有单测 |
+| NFR-003 | MUST | 可观测 | job/event 可以解释 step、artifact、失败原因 |
+| NFR-004 | SHOULD | 低耦合 | harness 类型模块不依赖 FastAPI 和 SQLAlchemy |
+| NFR-005 | SHOULD | 性能稳定 | 不新增阻塞式外部调用 |
+| NFR-006 | SHOULD | 中文一致性 | 文档、用户可见文案和新增注释使用简体中文 |
+
+## 9. 风险与缓解
+
+| 风险 | 影响 | 缓解 |
+| --- | --- | --- |
+| 过度抽象导致改造变慢 | 中 | 第一阶段只抽类型、trace、control，不拆主流程 |
+| 事件 metadata 变化影响前端 | 中 | 只新增字段，不删除旧字段 |
+| 取消/重试语义被破坏 | 高 | 优先跑 `tests/test_generation_jobs.py` |
+| Provider trace 与 job event 重复 | 低 | 保持 Provider 事件专注调用层，workflow 事件专注产品步骤 |
+| 文档与实现偏离 | 中 | 每个阶段报告必须记录实现偏差 |
+| 质量门误伤内容 | 中 | 第四阶段先做确定性低风险检查，模型评审延后 |
+
+## 10. 审查清单
+
+每个阶段完成前必须检查：
+
+- [ ] 是否保持 `/api/generations` 行为兼容
+- [ ] 是否有对应测试或验证命令
+- [ ] 是否没有引入不必要的外部框架
+- [ ] 是否没有重写无关功能
+- [ ] 是否保留用户已有工作区改动
+- [ ] 是否更新阶段报告
+- [ ] 是否更新本设计中的阶段状态或偏差记录
+
+## 11. 当前状态
+
+| 阶段 | 状态 | 备注 |
+| --- | --- | --- |
+| 阶段 0 | 已完成设计基线 | 已建立本设计与阶段 0 报告 |
+| 阶段 1 | 已完成基础实现 | 已新增 harness 类型、trace recorder、execution control，并通过定向测试 |
+| 阶段 2 | 已完成主要资产补全抽取 | 封面、音频、持久化绘本缺失图片补全已迁入 harness asset workflows |
+| 阶段 3 | 已完成计划建模基线 | 已定义 WorkflowPlan/WorkflowTask 和核心模式计划快照；执行器接管留待后续 |
+| 阶段 4 | 已完成确定性质量门 | 已接入文本故事和绘本结构完整性/儿童安全基础检查 |
+| 阶段 5 | 待执行 | Trace Analytics 与前端展示 |