[antosubash]

Performance fix for the file_storage S3 upload path and the file browse page (local performance review, 2026-11-05).

• Spool I/O off the event loop. Server-side S3 uploads buffer through a SpooledTemporaryFile. Work stays inline while the buffer is in memory, and moves to a worker thread once it rolls to disk or a write would push it past 2 MiB.
  • Offloaded calls are shielded, so cancellation waits for in-flight I/O before the file is closed.
• One S3 client per multipart upload, instead of one per call.
  • Create, complete and abort now share private client-taking helpers on S3MultipartMixin, so the public methods and the upload path cannot drift. Complete sorts the parts; abort tolerates NoSuchUpload.
• Browse index. New (tenant_id, is_deleted, created_at DESC, id) index for the default newest-first file list, added in migration f6c2d4e8b109.

Measured locally against a fake S3, with no network. Method and caveats are in docs/perf/2026-11-05-file-storage.md.

• Event-loop lag p99 during 32–64 MiB uploads went from roughly 29–55 ms to 11–14 ms.
• Elapsed upload time is within about 10–35% of main.
• A 16 MiB multipart upload opens 2 clients instead of 10.
• The browse first page over 100k rows on SQLite went from 38 ms to 0.08 ms.

Pipeline:

• /optimize ran once and produced 1 commit.
• A performance pass restored throughput after the first version offloaded every chunk (2–6x slower).
• Two review rounds fixed three things:
  • _io could spin when its inner task was cancelled;
  • an empty tail chunk;
  • the multipart helper drift described above.

Local CI:

• make lint ✓, make test-js ✓ and make migrations-roundtrip-pg ✓ (on a fresh database).
• make test-py (8 workers): all passed except test_clean_target_is_not_in_repo, the known local /tmp/.git placeholder failure.

Note: f6c2d4e8b109, #832's e805a1b2c3d4 and #833's c5d8e2f1a903 all revise e731a1b2c3d4. Whichever merges later re-points its down_revision.

https://claude.ai/code/session_01M9neheZZEe3sVpDi2S3zT4

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
🔒 Security Review	✅ Completed 2026-11-05T17:10:13.531779Z	cb78e1c	PR opened

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