Independent review finding on the merged #95980:
_apply_live_compression_config only acted on PRESENT keys, so removing
tail_mode / model.context_length / target_ratio / model_thresholds /
proactive_prune_* / protect_last_n / min_tail_user_messages / threshold /
idle_compact_after_seconds from config.yaml left stale values active in
live sessions forever (probe-verified: all six stale after applying
empty mappings).
Absence now restores the normalized default — or the model-derived
value — through the SAME derivation the construction path uses:
- ContextCompressor ctor defaults read off its real __init__ signature
(no hardcoded copies to drift)
- compression.threshold removal re-derives via agent_init's
_resolve_compression_threshold (Codex gpt-5.4/5.5 + spark autoraise
included)
- model.context_length removal drops the config override and forces
re-inference through the deferred get_model_context_length resolution,
which also re-applies the small-context threshold floor
- model_thresholds removal clears stale per-model overrides from the
live threshold; tail_mode falls back to the ctor's 'lean' (the old
present-key path normalized invalid values to 'legacy', diverging
from the compressor's own fallback)
Also fixes proactive_prune_min_reclaim_tokens's present-but-null default
(was 0; the real default is 4096).
Refs #94724
Teknium
ca753b96cb