Composing #57835's multi-fossil summary scan with #47274's merged-handoff
unwrap: when the restart-decay path pulls a merged handoff into the
compression window, its genuine prior-tail user content must enter the
summarizer input (folded into the fresh summary) rather than being
dropped with the summary row. Standalone handoffs still drop. The
continuity test now pins the composed contract: recovered verbatim OR
via summarizer input, never silently deleted, never duplicated.
- Three '_previous_summary == "fresh summary"' exact pins and one
transcript-wide fossil-absence pin predated main's deterministic
task-snapshot grounding (761a0b124e), which prepends a
'## Historical Task Snapshot' section to stored summaries and may
quote a folded head turn inside the handoff. Re-pin the contracts
(fresh body present, fossil absent from non-summary messages)
instead of exact strings.
- Add test_restart_simulation_fresh_compressor_does_not_reprotect_head:
a fresh ContextCompressor over a transcript containing a persisted
handoff summary computes the same decayed protected-head boundary
(compress_start base) as a live already-compacted process, and the
first post-restart compaction does not preserve pre-restart head
fossils (#57814).
protect_first_n decay state (compression_count / _previous_summary) is
in-memory only, so a gateway restart re-protected the persisted handoff
summary and head fossils, growing the head unboundedly across
restart+compaction cycles (#57814).
_effective_protect_first_n now probes a bounded resumed-head window for
a persisted handoff summary (by metadata or content prefix) and decays
protection when one is found, before compress_start is computed. The
first post-restart compaction self-heals: stacked summary fossils are
folded into the next summary prompt instead of preserved verbatim,
rehydration is rolled back on abort, deterministic fallback carries a
bounded redacted previous-summary snapshot, and forced user-leading
merged summaries keep the live tail request after the summary end
marker so they stay rehydratable.
Squashed reapply of the 12-commit series from PR #57835 onto current
main (branch was 1210 commits behind; single add/add conflict with the
task-snapshot grounding helpers resolved by keeping both).
Fixes#57814.
The salvaged estimator ran a per-character Python loop on every
estimate_tokens_rough() call — a ~28,000,000x slowdown vs (len+3)//4 on a
1MB ASCII tool output (measured ~3.0s per call). Gate it:
- str.isascii() O(1) fast path keeps pure-ASCII text bit-identical to the
classic (len+3)//4 rule at ~1.3x baseline cost (0.23us vs 0.17us per
1MB call).
- Non-ASCII text counts dense CJK chars via a compiled character-class
regex in C (len(text) - len(re.sub(''))): ~352ms/1MB hangul vs ~2.1s
for the per-char loop.
- Non-ASCII-but-non-CJK text (accents, Cyrillic, emoji) keeps the classic
rule.
Also: parity tests against the per-char reference implementation, and
updated two stale expectations that encoded the old behavior (CJK now
counted ~1 token/char; short string content now ceil-divided instead of
floored to 0). The continuity test now detects merged-into-tail summaries
via _is_context_summary_content.
Snapshot review_agent._session_messages before teardown so close() can
clean per-session state without dropping the user-visible
self-improvement summary. Adds two regressions:
- bg-review summarizer receives captured review-agent tool messages
after review_agent.close() runs
- context-compressor protected-head handoff rehydration populates
_previous_summary and keeps the old handoff out of newly summarized
turns
Salvaged from PR #26039 onto current main after agent/background_review.py
extraction. Original commit 63eaf6055; bg-review test updated to patch
the module-level summarize_background_review_actions in
agent.background_review instead of the now-forwarder
AIAgent._summarize_background_review_actions.
