Which Timeline warnings does the free plan call show before rendering?

The free POST /v1/timeline-1.0/plan call returns the warnings that depend only on the numbers in your document, such as gaps, a tail the video does not cover, fades that snap to whole frames and ignored motion. It cannot return anything that needs the real files, because the plan never downloads or probes media.

That split decides when to rely on the plan and when to read warnings[] on the finished render. Plan has no Idempotency-Key requirement, creates no job and reserves no credits.

What we ran and what came back

We called the repository's plan builder with a 12-second spine, a 4-second slot at 0, and a second 4-second slot at 6 seconds with a 0.3-second fade, output.fps 25. The response held coverage_seconds: 10 and three warnings: transition_snapped_to_frame, timeline_gap_filled for 2 seconds, and video_coverage_shorter_than_audio.

The same builder returned an empty warnings array for a still with source_in, a 60 fps request over unknown sources, a soundtrack with no loop, and a slot with a source_in of 50 seconds. Those need the media, so they appear only at render time.

A pre-flight routine

Run the plan, fail your own pipeline on any warning you consider a defect, and probe the clips with video inspect for the lengths and frame rates the plan cannot see. Compare each clip's length with source_in + duration, plus the fade length on any slot that has one. Then render.

Send output.fps in the plan when you will send it in the render. With it omitted, the plan validates at 30 fps while the render matches your sources, so a frame-snap warning in the plan may differ from the render's.

Reading the render result

When the job is result_ready, GET /v1/jobs/:id/result returns kind: timeline_render with warnings[]. The documentation calls them soft warnings, not failures: padded or looped short sources, snapped transitions and ignored still motion all let the job finish. Log them with the job id so a later complaint about a frozen frame can be traced to the exact warning.

Render pricing is $0.10 per ceil output minute, and the plan response gives billable_minutes and estimated_cost_usd_micros so you can check cost in the same call.