chatgpt-codex second-pass review on #3249: the previous helper folded
the 4k SUMMARY_TEXT_RESERVE into both the maxFrames cap math AND the
skip decision (return 0 when frameBudget < 0). That made any residual
headroom below 4k fall negative and force the LLM-summarizer fallback,
even though a text-only snapcompact archive (the 'text.length <= 2 *
edgeCap' short-circuit in planArchive) typically costs only a few
hundred tokens of summary lead-in and would have fit cleanly.
The two reserves now serve their own jobs:
- Skip iff 'baseTokens >= totalBudget' (kept-recent + non-message
already eats the entire window − reserve envelope). No reserve
fudge here; positive residual is always worth attempting.
- Cap reserve (4k) is applied ONLY to the maxFrames calculation so
the projection still passes once frames land. When the frame budget
goes negative under that reserve but residual headroom is positive,
the helper now returns maxFrames=1 instead of 0 so snapcompact's
frame-less planArchive branch can still produce a valid archive.
Updated regression test to pin the new contract directly: kept-recent
tuned for 1500 tokens of headroom (well below the 4k cap reserve), the
old helper returned 0 and skipped to the LLM summarizer, the new helper
invokes snapcompact with maxFrames=1.
roboomp
db57efc3d3