Slimmed after review: the 200K default is dropped. Children compact at the same
0.50 x window ratio trigger as their parent (500K on a 1M model). Reasons:
- the run this came from happened at 0.85 (850K); main was already at 0.50, so
the real delta against main was 500K -> 200K, not 850K -> 200K;
- a replay of the run's 22,489 logged calls (evals/postmortem, cap sweep) put
200K-400K caps within 5% of each other in cost once cache prefixes are intact,
because the write price dominates and the cap only trims read volume;
- every compaction is a chance to lose detail, and the accuracy side was never
measured; at 500K a 1M child compacts roughly never.
What stays: the reviewer's finding that the value was coerced, not validated
(YAML true -> int 1 -> a one-token trigger; "200k" -> silently off). Values are
validated: int >= 16000 enables the cap, 0/false/null/unset = off, anything else
is warned and ignored. Docs and config comment restated accordingly.
Independent review: a YAML `true` coerced to int 1 and gave every child a
one-token compression trigger; "200k" silently disabled the default cap.
Values are now validated: an int >= 16000 is used, 0/false/null disable on
purpose, anything else warns and falls back to the 200K default so a typo
never costs money. Config comment and docs say it caps the compaction
trigger, not a hard request-size limit.
Test: true / "200k" / 5 -> default; 0 / false / None -> disabled; valid ints
pass.
A delegate_task child inherits the compression threshold as a RATIO of the
model window. On a 1M-window model at the run's configured 0.85 that is an
850K-token trigger: in the 1,393-agent refactor run 1,373 of 1,375 children
never compressed once, 62% of all API calls carried >150K of context, and the
calls above 200K carried ~$10.9k of the $19.3k bill (58% of it cache WRITES,
i.e. re-sending a 300-800K prefix on every call). A sawtooth replay of the
logged calls with a 200K cap / 65K floor cuts context spend by ~49% (~$7k).
Children are brief-driven and disposable; they re-read their brief and the
files they touch, so a large window buys them little. New
delegation.compression_threshold_tokens (default 200000) is applied to the
child's ContextCompressor right after construction as the lower of it and
any global compression.threshold_tokens; the parent's own trigger is
untouched. 0 disables the subagent-specific cap. The compressor applies
threshold_tokens_cap on first window resolution, so this is byte-equivalent
to the user having set compression.threshold_tokens for the child.
Live through the real spawn path (_build_child_agent, real imports, temp
HERMES_HOME, 1M-window model): main child trigger 500,000 / branch 200,000;
parent 500,000 on both.
Tests (3): default caps a 1M child at 200K; the cap is the lower of the
delegation and global values and never raises a small-window child's
trigger; 0 disables and an already-resolved trigger is re-clamped.
Docs: delegation.md, configuration.md.
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