[andyhsu6]

Closes #290.

Symptom

A project with 70 outlines and 58 chapter rows answered "所有章节都已生成内容" when the user tried to batch-generate, so the 12 outlined-but-unbuilt chapters were unreachable from the UI.

Cause

handleOpenBatchGenerate looked for the first chapter with empty content among existing chapter rows:

const firstIncompleteChapter = sortedChapters.find(ch => !ch.content || ch.content.trim() === '');
if (!firstIncompleteChapter) { message.info(t('toast.allGenerated')); return; }

An outline without a chapter row is invisible to that scan. Deleting chapters (rows removed, outlines kept as the plan) produces exactly this state; so does any import that created outlines without chapters. The backend had the same blind spot — stats reported only chapter count and max chapter number, and nothing could build a chapter from its outline.

Change

• GET /project/{id}/stats now returns outline_total, max_outline_number and missing_from_outlines.
• POST /project/{id}/materialize-outlines creates the missing chapter rows from their outlines: idempotent, never overwrites an existing chapter, keeps the outline link and its title, empty content, status=draft.
• The batch entry point materialises the missing rows first and then continues with the normal flow, instead of stopping at the "all generated" toast.

Verification (real project)

stats before: {'total': 58, 'max_chapter_number': 58, 'outline_total': 70, 'missing_from_outlines': 12}
materialize:  {'created': [59..70], 'count': 12}
stats after:  {'total': 70, 'max_chapter_number': 70, 'outline_total': 70, 'missing_from_outlines': 0}

Test plan

cd backend && .venv/bin/python -m pytest tests/test_chapter_materialize_from_outlines.py -q   → 3 passed
cd backend && .venv/bin/python -m pytest tests/ -q -p no:cacheprovider                        → 1659 passed
cd frontend && npx vitest run                                                                 → 232 passed (28 files)
cd frontend && npm run build                                                                  → built

Tests cover the stats gap, idempotency, "never overwrites an existing chapter", and outlines without an order_index being skipped.

Desensitized per repository policy: no source text, titles or character names are included.