episode.yaml: the timeline follows the script, the cast survives

[alpibrupa]

The audiobook was narrating text the book had cut

episode.yaml carries two things with opposite requirements:

• voices — the cast sheet an author hand-tunes. Must survive regeneration. There is a test protecting that, and it is right.
• timeline — derived from the script. Must follow it.

Preserving the whole file protected both. So when an editorial pass deleted twenty paragraphs, script.json moved on and the timeline did not — and assemble reads the timeline. Ten of Production's seventeen chapters went on splicing in audio for lines the manuscript no longer had, and chapter 11 was additionally missing two lines that were in the script.

Nothing reported it. The render succeeded, the durations looked plausible, and the voice-line manifest said zero stale — correctly, because every surviving line did match its own text. The tell was a count that should have been an equality:

prompt-to-production   716 lines   734 voices

Chapter 9 was still narrating 19 seconds of prose the book had removed.

The fix

A non-forced run now merges rather than skipping: the timeline is rewritten from the plan, an existing cast is kept, and a character the manuscript has introduced since the last run gets a default voice rather than none. --force still overwrites both, and the file is only rewritten when something actually changed.

The failing test asserted the whole file was preserved — the assumption behind the bug, not a guard against it. Replaced with three that state the narrower, correct guarantee.

Verified

All four books re-assembled from corrected timelines, 19 orphaned voice files removed:

	lines = voices	stale	timeline mismatch	duration
Production	716 = 716	0	0	3.33 h
Evidence	315 = 315	0	0	1.90 h
Ledger	295 = 295	0	0	1.76 h
Decision	245 = 245	0	0	1.51 h

Production lost 3.6 minutes — the cut paragraphs, no longer read aloud.

Note

This is the third silent-staleness bug in this pipeline, after the voice-line cache and write_project skipping script.json. All three had the same shape: a derived artifact treated as durable, no error raised, plausible output. Worth remembering that the manifest caught the first two and could not catch this one — it verifies line contents, and this was a defect in the line set.

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