perf(api): バッチ化・並列化で逐次クエリ/逐次 await を解消

[otomatty]

タイトルリネーム伝播 (propagateTitleRename) の参照元ページ書き換えを、
最大 8 件 (SOURCE_REWRITE_CONCURRENCY) の Promise.allSettled バッチで
並列化する。各 source は独立した page_contents 行をロックするため順序
非依存で、ロック競合・デッドロックは発生しない。失敗は従来どおりベスト
エフォートでカウント・ログし、後続 source / ghost 昇格を止めない。

AI モデル同期 (syncOneProvider) の新規モデル投入を、行ごとの逐次 INSERT
から単一マルチバリュー INSERT に変更 (N+1 → 1 クエリ)。sortOrder は max+1
から index で事前採番する。表示順 (orderBy) にしか使わないため、稀な
onConflict スキップで生じるギャップは無害。

並列パスの回帰防止テストを追加 (順序非依存の意味ベース DB モック):
ベストエフォート集計・同時実行数 8 のバウンド検証。

Refs #1001

Summary by CodeRabbit

• Tests

  • Added unit tests verifying concurrent title-rename behavior and enforcement of parallelism limits.
  • Improved concurrency test utilities to make task-ordering and microtask boundaries deterministic.

• Performance

  • Optimized AI model sync with batched inserts to reduce per-item work.
  • Title-rename processing now uses bounded parallelism with improved success/failure accounting and resilient error handling.

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[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

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Run ID: cf73ae5a-0bc2-4274-8199-016e1221c5e1

📥 Commits

Reviewing files that changed from the base of the PR and between d7ed16b and b222dfd.

📒 Files selected for processing (2)

• server/api/src/__tests__/services/titleRenamePropagationService.test.ts
• server/api/src/services/titleRenamePropagationService.ts

🚧 Files skipped from review as they are similar to previous changes (2)

• server/api/src/tests/services/titleRenamePropagationService.test.ts
• server/api/src/services/titleRenamePropagationService.ts

---

📝 Walkthrough

Walkthrough

This PR implements two independent performance optimizations: source-page rewrites in title-rename propagation now execute with bounded parallelism via chunked batching, and AI model insertion switches from per-row loops to single multi-value statements. Tests verify parallel failure tolerance and concurrency limits.

Changes

Title Rename Propagation with Bounded Parallelism

Layer / File(s)	Summary
Concurrency constant and source-page wrapper server/api/src/services/titleRenamePropagationService.ts	SOURCE_REWRITE_CONCURRENCY caps concurrent source-page rewrites, and rewriteAndInvalidateSourcePage wraps per-page rewrite with optional Hocuspocus cache invalidation that logs but suppresses invalidation errors.
Batched parallel propagateTitleRename loop server/api/src/services/titleRenamePropagationService.ts	propagateTitleRename replaces sequential per-source rewrites with Promise.allSettled over SOURCE_REWRITE_CONCURRENCY-sized batches, aggregating success/failure counters and continuing to ghost-link promotion phase.
Test utilities and parallel concurrency tests server/api/src/__tests__/services/titleRenamePropagationService.test.ts	Order-independent DB mock (createParallelRenameDb) and microtask-flush utility enable two new tests: one verifies best-effort parallel rewriting tolerates per-source FOR UPDATE failures while aggregating counts; the other asserts concurrency is bounded by SOURCE_REWRITE_CONCURRENCY.

AI Model Batch Insert Optimization

Layer / File(s)	Summary
Batched multi-value insert in syncOneProvider server/api/src/services/syncAiModels.ts	syncOneProvider now computes nextSortOrder once, filters existing IDs upfront, and inserts all new rows in a single batch with per-row sortOrder offsets, using onConflictDoNothing with returning to set upserted count.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related issues

• perf(api): 逐次クエリ/逐次 await のバッチ・並列化 #1001: This PR directly implements the two optimizations described in the issue: parallelizing title-rename propagation and batching model inserts.

Possibly related PRs

• otomatty/zedi#736: The batched parallel rewrite flow in titleRenamePropagationService builds on the propagateTitleRename implementation introduced in this PR.

Poem

🐰 I hop in chunks and split my load,

rewrites race but stay within the road.
Batch the seeds, one planted row—
fewer trips, more carrots grow.
Hooray for rabbits, fast and bold!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 55.56% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main performance improvements: eliminating sequential queries and awaits through batching and parallelization.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

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• Create PR with unit tests
• Commit unit tests in branch claude/github-issue-1001-mBbii

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[gemini-code-assist]

Code Review

This pull request optimizes AI model synchronization by batching inserts and parallelizes source page rewriting during title rename propagation in bounded batches. The feedback recommends reducing the concurrency limit from 8 to 4 to avoid database connection pool exhaustion and transaction propagation issues, along with updating the corresponding test suite to reflect this change.

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