At a glance
- What broke13 short video drafts in one day. The 10 rendered after the top-up cost about $5.20 against the $1.86 the console showed: 2.8 times the estimate, from a per-second rate off by 3.3.
- Found byThe operator's fal balance: a $10 top-up, $4 left after one day of drafts
- Where it standsStill open. The log says so, and the write-up grows as the repair does.
The story
On 30 September 2026 we topped up fal by $10, rendered ten short video drafts, and had about $4 left by the evening. The screen that was built to stop exactly this said we had spent $1.86.
This site is the working notebook of a one-person studio that builds its own tools. A fix is the account of one thing that broke, written by the person who broke it.
The short answer: fal’s pricing API gives one price per model, and it is the cheapest tier. Gemini Omni Flash 1.1 costs $0.03 a second at 360p. Our drafts rendered at 720p, which the model page bills at $0.10 a second. The per-second rate was off by 3.3 times, the day’s total by 2.8, and the ceiling sat on the wrong number. Nothing in the pipeline could tell.
| Tier | fal bills | The console showed | Gap |
|---|---|---|---|
| 360p | $0.03/s | $0.03/s | none |
| 720p (our drafts) | $0.10/s | $0.03/s | 3.3× |
| 1080p | $0.15/s | $0.03/s | 5× |
What follows: why a price lookup existed at all, the two wrong turns before the right one, the one-line fix, and the trigger that reopens this page.
The evidence
The trace is rough while the fix is open. It runs straight from the repair on.
- Opened
fal balance at $4 after a $10 top-up and a day of Omni drafts. The console showed $1.86 spent.
- Diagnosis
fal's usage API refused the inference key. No per-call ledger available; the balance delta is the only real figure.
- Diagnosis
Per-turn log rebuilt from the door's records: 10 drafts at 720p, $1.86 estimated at the 360p rate. Model page lists $0.10/s for 720p. Rate ratio 3.3; totals ratio 2.8.
receipt · turns.jsonl rebuild, 2026-10-06 - Repair
Omni door prices by resolution: factor 1 / 10⁄3 / 5 for 360p / 720p / 1080p.
receipt · KOS commit 3d35df45 - Monitoring
Spend band mod shows the day's estimated spend in the terminal status line. Watching for a day with a gap over 20 percent.
receipt · vault commit 1288d8c - Opened
A session's script called fal directly with our key: eight image edits, $0.32. The status line stayed blank and the usage dashboard showed fal near $0.
- Diagnosis
No fal call sends a cost to the tracing store the dashboard reads, and the status line only parsed door answers. fal's usage API works with an admin-scoped key.
- Repair
Dashboard and status line read fal's own bill through the usage API. Seven days: dashboard $1.449, fal's bill $1.449.
receipt · KOS commit def97564, vault commit dd89895 - Monitoring
Watching the dashboard's fal figure against fal's billing page, once a week.
The rule I changed after
Check the model page against the pricing API before trusting an estimate. A spend ceiling is only as true as the estimate under it.