Follow-up to @someaka's fix.
Polish:
- Drop the redundant `_preflight_tokens >= threshold_tokens` clause.
`should_compress(tokens)` already short-circuits when tokens < threshold,
so the explicit comparison was dead code on the True branch.
Tests:
- Preflight: pin that should_compress() is called (anti-thrash has a vote).
Mocks should_compress to return False even with tokens past the raw
threshold and asserts no compression runs — exact bug shape from #29335.
- Gateway: AST scan of gateway/run.py asserts every
`session_entry.session_id = ...` assignment is followed by a
`session_store._save()` call within the same block. Three sites mutate
the session_id after compression; all three must persist or the next
turn loads the pre-compression transcript and re-loops. Empirically
verified the test catches the bug (drops the new _save() line → red).
AUTHOR_MAP:
- Map ed@bebop.crew -> someaka so the salvaged commit resolves to
@someaka in release notes.
