[davior]

Summary

Last piece of SN-2. With AI_BACKEND=suite, generate_image_for_user (used by the image route and the assistant's generate_image action) sends its fal request to the suite's media queue instead of to fal. local is unchanged.

• Notes still owns the catalogue. The model list, size presets and each endpoint's request fields (build_fal_image_body) stay here, as in GAM. The suite is the fal key, the queue and the bill, so no fal key is needed in Notes in this mode.
• Flow: submit POST /ai/media/jobs (kind image), poll until it finishes, take the image URL from fal's result, then download and save it into the user's media exactly as before (stable /media/... URL, thumbnail, size cap, SSRF check).
• Cost is the suite's billed amount from the job, returned as before (cost, currency; null when fal's price is not yet known). Notes writes no usage row; the suite has.
• A generation that does not finish within the existing 180 s is cancelled (DELETE on the job) rather than left running and billing, and answers 504. fal's own refusal reason is passed through as a 502 fal_error. The suite being down is a 503 suite_unavailable.
• This completes SN-2 (search SN-2a: web search through Gecko Suite behind AI_BACKEND #214, speech SN-2b: speech through Gecko Suite behind AI_BACKEND #215, images here).

Not changed: Settings → Images' fal usage and balance readouts (/images/usage, /images/pricing) still use Notes' own fal admin/billing keys; they report Notes' own history, not the suite's.

Test plan

• pytest -q in backend/: 1379 passed, 1 skipped (Python 3.13 locally; CI is 3.11). 5 new tests in tests/test_suite_proxy.py through the real image route with a fake suite and a fake fal download: queued → running → completed, file saved in Notes' media, cost from the job, the endpoint body Notes built, no usage row and no fal key needed; a failed job keeping fal's reason; a never-finishing job cancelled with a 504; a model outside Notes' list refused without calling the suite; the suite down.
• Not run against the real suite or fal.

Deployment

Nothing changes unless AI_BACKEND=suite is set (from #213).

• Before enabling: the person needs a fal.ai provider in the suite (their own, or a shared one), which the suite's importer brings across from Notes' fal key.
• Configuration: none new. Services rebuilt: backend only. Migrations, Caddy: none.
• Verify: in suite mode generate an image from the editor (it appears in the note) and from the assistant; the suite's Usage view shows an image event under app notes with a cost.
• Roll back: AI_BACKEND=local, docker compose up -d.

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Generated by Claude Code