feat: move Seedance and Omni video onto the job contract

.agents/references/providers/fal.md

@@ -52,6 +52,8 @@ Per-second figures below are fal's own 16:9 approximations.
 - Cancel: `PUT .../requests/{id}/cancel` returns 202 `CANCELLATION_REQUESTED` or 400 `ALREADY_COMPLETED`; in-progress jobs may still finish (docs).
 - `X-Fal-Request-Timeout` sets an absolute server-side deadline (docs).
 - The JS SDK wraps this as `fal.queue.submit/status/result/cancel`, or `fal.subscribe` which submits and polls (docs).
+  We use the queue calls, so a job keeps its request ID from submission; a rejected job (the likeness 422) surfaces when its result is read (probe, 2026-10-04).
+- SDK 1.10 calls: `POST queue.fal.run/<endpoint>`, `GET queue.fal.run/<owner>/<app>/requests/{id}/status?logs=0`, `GET .../requests/{id}`, `PUT .../requests/{id}/cancel`; storage uploads `POST rest.fal.ai/storage/upload/initiate?storage_type=fal-cdn-v3`, then `PUT` to the returned URL (probe).
 - Seedance output: `{ video: { url, content_type, file_name, file_size }, seed }`, plus `draft_id` on 2.5 (docs).
 - Seedance 2.0 inputs: `prompt`, `image_url` (i2v, required), `end_image_url` (i2v), `image_urls` / `video_urls` / `audio_urls` (r2v), `resolution`, `duration`, `aspect_ratio` (auto, 21:9, 16:9, 4:3, 1:1, 3:4, 9:16), `generate_audio` (default true, same price), `bitrate_mode`, `codec`, `end_user_id` (docs).
 - `duration` and `resolution` are string enums in the schema (`"auto"`, `"4"`..`"15"`) (docs).

.agents/references/providers/google.md

@@ -135,6 +135,9 @@ Public YouTube URLs work, with an 8 h/day cap on the free tier (docs).
 - `minimal` thinking errors on 3.8 Flash, 3.7 Flash, and 3.1 Pro preview but is the default on 3.5 Flash-Lite and the image models (docs).
 - Omni returns the video as base64 `data` inside `steps[]` by default; a URL comes back only with `response_format.delivery: "uri"`, and only in the create response or SSE stream, not on later `GET /interactions/{id}` (docs). Use `uri` above 4 MB (docs).
 - Omni requests are synchronous unless `background: true`; `store: false` disables `previous_interaction_id` editing (docs). Interactions are retained 55 days on paid tier, 1 day on free (docs).
+- Omni accepts `background: true` although the background-execution page lists only text models and agents: create returns `{id, status: "in_progress"}` in about 3 s, `GET /interactions/{id}` moves to `completed` after 20-70 s, and the completed interaction's `steps[]` carries the video `uri`, contrary to the note above (probe, 2026-10-04).
+- A `previous_interaction_id` edit on a background interaction kept the subject and camera and applied the edit ("snowy night"); Omni chose 10 s for both clips (probe, 2026-10-04).
+- Background interactions cancel with `POST /interactions/{id}/cancel` (docs, background execution).
 - Veo extension takes a video object from a previous generation (`instances[].video` as `uri` or `inlineData`), must be 720p, and requires `durationSeconds: 8` (docs).
 - Veo REST examples wrap reference images as `{ image: { inlineData }, referenceType: "asset" }` and frames as `{ inlineData }` (docs). `gcsUri` is not documented for the Gemini API.
 - Gemini 3.x function calling over generateContent needs thought signatures round-tripped and `FunctionResponse` `id` plus `name` matching the call; mismatches return empty responses with `STOP` rather than an error (docs).