# 33 — Script Fallback Empty Articles

## Summary

Both filesystem and DuckDB script stage runners catch missing or invalid extract artifacts and silently set `articles = []`, then proceed to `generate_script` with success reporting (file path) or partial failure (DB path only if zero lines). Missing extract stage is not surfaced as a stage error; the script falls back to story summaries only, degrading episode quality without operator visibility.

## Should vs Actual

| Should | Actual |
|--------|--------|
| Script stage fails fast if extract prerequisite missing | `except` → `articles = []`, continue |
| Clear warning in `StageResult.error` or `items_in` mismatch | File mode always `success=True`; DB mode succeeds if any lines generated |
| Operator knows extract was skipped | Only log inside `generate_script` content_map fallback to `item.summary` |
| Consistent exception handling | File: `FileNotFoundError, json.JSONDecodeError`; DB: bare `Exception` |

## Evidence

**Filesystem script stage**:

```296:317:src/densefeed/pipeline.py
    async def _stage_script_file(self, reg: PipelineRegister, date: str) -> StageResult:
        ...
        try:
            articles = [Article(**a) for a in reg.read_jsonl(3, "articles.jsonl")]
        except (FileNotFoundError, json.JSONDecodeError):
            articles = []

        ...
        script = await generate_script(
            ranked, articles, self.config, date, jsonl_path=jsonl_path
        )

        return StageResult(
            stage=4,
            name="script",
            success=True,
            ...
        )
```

**DuckDB script stage** — broader catch:

```439:467:src/densefeed/pipeline.py
    async def _stage_script_db(self, run_id: str, date: str) -> StageResult:
        ...
        try:
            articles = [Article(**a) for a in storage.read_stage(run_id, 3)]
        except (FileNotFoundError, Exception):
            articles = []

        script = await generate_script(ranked, articles, self.config, date)
        if not script.lines:
            return StageResult(..., success=False, error="script generation produced no lines")
```

**`generate_script` silently uses summaries when article body missing**:

```141:195:src/densefeed/stages/script.py
    article_map = {a.url: a for a in (articles or [])}
    ...
    content_map = {
        item.title: (
            article_map[item.url].body
            if item.url in article_map and article_map[item.url].body
            else item.summary
        )
        for item in items
    }
```

Empty `articles` means **all** content comes from `item.summary` — no log at warning level for that fallback at pipeline level.

## Impact

- **Silent quality degradation**: Skipping Extract in Individual Stages tab still produces a "successful" script with shallow content.
- **Debugging pain**: Users blame LLM/script stage when root cause is missing stage 3 artifacts.
- **Inconsistent strictness**: DB path fails on zero lines; file path reports success even for empty dialogue edge cases handled inside `generate_script`.
- **Chaining bugs amplified**: Combined with run_id heuristic (item 30), script may read wrong/missing extract data without error.

## Suggested fix

1. Replace silent fallback with explicit policy flag: `require_extract: bool` (default `True` in production, `False` in dev).
2. When extract data missing: `StageResult(success=False, error="extract stage output missing for run ...")` unless flag set.
3. If soft fallback desired: `success=True` with `error="warning: using summaries only (N articles missing)"` and log `items_in` from extract vs rank counts.
4. Narrow DB `except` to `FileNotFoundError` only (what `read_stage` raises).
5. Add pipeline validation helper: `assert_prerequisites(run_id, stage)` before each stage in advanced UI.
6. Surface extract coverage metric in stage log: `items_out` articles / `items_in` ranked.

## Related issues

- **30-single-stage-run-id-heuristic** — wrong run → missing extract appears as empty articles
- **32-publish-split** — downstream stages may succeed on thin scripts
- **26-app-py-god-module** — Individual Stages tab enables running script without extract