Identify a completed merged assistant handoff from the carrier's own stop state instead of an unrelated adjacent history row. Keep carriers with pending tool calls actionable so compaction cannot abort a live tool chain.
Treat a merged assistant-role summary carrier as the driving reference handoff when it immediately follows a completed assistant stop. Its preserved prose and stale tool_calls are assistant continuity, not a fresh live user request.
Keep legitimate in-flight behavior unchanged when there is no completed stop, a real user turn follows, or a distinct later assistant tool-call row continues the loop.
Extends the #80622 active-turn guard for the merged-carrier shape reported under #42768.
Review follow-up on the salvaged #90353:
- Todo snapshot (+ coupled pruned-skill reload notice, 7a16840add) is now
reduced only as a LAST resort after reasoning/tool/summary shrink ops,
and the reload notice survives even then.
- Reuse existing helpers/constants instead of re-hardcoding:
_PRUNED_TOOL_PLACEHOLDER, _PRUNE_MIN_CHARS, _NEWEST_TURN_ONLY_BUDGET_KEYS,
and _prune_stale_reasoning_replay (codex sidecar shrink, #71058 boundary).
- Assistant-role messages without the summary metadata key are no longer
truncatable by the summary-cap heuristic.
- Caller passes budget so the estimator runs 3x, not 5x, per would-grow pass.
The anti-growth guard correctly refuses to persist a compressed
candidate larger than the original, but the rejection was never
recorded by the anti-thrashing breaker: _ineffective_compression_count
stayed at zero, the latch never tripped, and automatic compression
retried the SAME unchanged transcript on every turn - same summary
request, same refusal, same user-facing warning (#88568).
Add ContextCompressor.record_rejected_compaction(): one persisted
ineffective strike, without arming post-compaction real-usage
verification (nothing was committed) and without touching the
fallback-summary streak (no summary was accepted). The would-grow
abort path in conversation_compression calls it before returning the
original transcript. Two refusals latch the normal breaker, manual
/compress keeps bypassing it (force=True), and the existing recovery
window still allows one probe later.
Fixes#88568
A later hygiene idle-timeout write can replace an aux-model cooldown on
the shared column. Drop the in-memory timer on that refresh so the
in-agent compressor is not still blocked after the DB row is hygiene.
Session hygiene persists compression_failure_cooldown_until after a
30s no-progress watchdog so the pre-agent pass can skip. The
in-conversation compressor read the same column and then refused to
run even though its own budget is sufficient.
Ignore hygiene idle-timeout errors on the in-agent path. Real
aux-model faults such as rate limits still block.
Fixes#86972
- _build_anchor_index(): regex-harvests PR/issue numbers, SHAs, branches,
file paths, error strings, handles, URLs from the compacted region into a
bounded indexed summary section. LLM-free, so needle identifiers cannot be
paraphrased away (the GUI-lineage failure class: 10/15 verbatim-or-nothing
golds). Doubles as session_search query-anchor map.
- evals/compaction/test_region_scoping.py: sentinel tripwire proving the
summarizer input carries ONLY the compacted region (head/tail sentinels
never reach the serialized turns body) in both legacy and lean modes.
- _digest_worthy() drops no-signal tool rows before chunking (GUI-lineage
digests were starving on tool-noise)
- eval recovery sim now uses in-memory SQLite FTS5 + BM25 (production
session_search engine) instead of term-frequency scoring
- recovery query writer sees the digest section (front of context) so it can
mine anchor identifiers
Fix: _LENGTH_CONTINUATION_DROPPED_TOOLS_PREFIX ended with '(' but
_get_continuation_prompt still had f'({tool_list})', producing
'((write_file)' instead of '(write_file)'. Removed the '(' from
the prefix constant — the parenthesis belongs in the interpolation.
Widened: promoted the empty-response nudge (line 6993,
'You just executed tool calls but returned an empty response...')
to _EMPTY_TOOL_RESPONSE_NUDGE constant and added it to the
classifier's recognition set. Same bug class — its
_empty_recovery_synthetic metadata flag doesn't survive SessionDB
projection either.
Test: added parametrize case for the empty-response nudge (7→8 cases).
E2E: verified byte-for-byte string equivalence for all nudge constants.
aed114a69 taught _is_synthetic_compression_user_turn to recognize the
max-iteration nudge as ephemeral runtime scaffolding rather than a human
turn, since its role="user" metadata flag doesn't survive SessionDB
projection and a crash/interrupt mid-turn can persist it durably — becoming
the compaction anchor / auto-focus topic in place of the real task.
conversation_loop.py's retry loop appends several more role="user" rows
with the exact same "ephemeral, metadata-tag-only" shape, none of them
recognized by the classifier:
- The three _get_continuation_prompt variants (length-continuation nudge,
tagged _length_continuation_nudge) — two fixed strings plus a third that
interpolates the dropped-tool-call list.
- _CODEX_INCOMPLETE_NUDGE (codex/responses reasoning-only retry).
- The codex ack-continuation nudge (acknowledgment-only reply re-prompt).
- The dropped-tool-call nudge (tagged _dropped_toolcall_nudge) — persisted
across up to 3 consecutive retries before the finalization pop-loop
strips it; an interrupt/crash before that pop can persist it same as the
max-iteration case.
Promote the previously-inline nudge strings to named module-level constants
in conversation_loop.py (single source of truth for both construction and
recognition), then extend the classifier to recognize all of them — exact
match for the five fixed-content nudges, a stable-prefix check for the
dropped-tool-call continuation variant (its tool list is interpolated so it
can't be exact-matched, same treatment TODO_INJECTION_HEADER already gets).
Imported lazily inside the classifier to avoid a module-load-order cycle —
conversation_loop.py already imports FROM context_compressor.py at call
time for the same reason.
Generic thinking fields (reasoning / reasoning_content + the
reasoning_details text charge) are replayed for at most the NEWEST
assistant turn on every transport: Anthropic strips all-but-newest at
convert time, Bedrock Converse never replays thinking, and strict
chat-completions providers reject or one-space-pad the field. The tail
budget walks charged them on every message anyway, spending 19-24% of
the budget (per the issue's 1,025-message measurement) on bytes that
provably never reach the wire — so the tail cut landed early and each
compaction discarded more real transcript than configured.
_estimate_msg_budget_tokens now partitions the replay keys:
* _ALWAYS_REPLAYED_BUDGET_KEYS (codex_reasoning_items,
codex_message_items) — charged unconditionally. These ride the wire
on every retained turn (#55572), and codex_reasoning_items now also
carries native server-side compaction checkpoints (#81747).
* _NEWEST_TURN_ONLY_BUDGET_KEYS (reasoning, reasoning_content) + the
reasoning_details text charge — charged only for the newest assistant
turn via charge_stale_thinking, resolved by the three budget walks
(tail cut, raw-budget re-walk, proactive-prune boundary).
Default stays the conservative full charge for callers without
turn-position context. A partition invariant test pins that any future
_REPLAY_BUDGET_KEYS entry must be classified into exactly one class.
Direction credit: #73669 (@x7peeps) and #73730 (@webtecnica) both
attacked this; the keep_open reviews asked for provider/API-mode-aware
accounting that keeps Codex carriers charged — this implements that
shape.
Two corrections on top of the #71077 base (the whole bug class):
1. Turn boundary = last USER message, not last assistant message. A Codex
turn spans several assistant messages (assistant+tool_calls -> tool ->
... -> final assistant) whose reasoning items must replay together; the
last-assistant boundary would strip reasoning mid-chain from the active
turn (the gap flagged in PR #71077 review).
2. type="compaction" checkpoints (native server-side compaction, PR #81747)
are exempt: they carry already-pruned history, not per-turn reasoning.
Pruning filters items instead of popping the sidecar key.
Sibling site fixed in the same class: the Codex incomplete-continuation
dedup path blind-overwrote codex_reasoning_items on visually-duplicate
interim messages, which would drop the only copy of a checkpoint captured
on the earlier response. Extracted merge_interim_reasoning_items() into
agent/native_compaction.py; newer reasoning wins, prior checkpoints are
preserved unless the newer payload carries its own.
- Wire the Pass-1 dedup floor (len < 200) to the shared _PRUNE_MIN_CHARS
constant it was already documented as matching, and use the constant in
the remaining test literal.
- Restructure the clarify 'resolved' computation (is_answer_shaped +
sentinel check) instead of compute-then-flip.
- Add a live producer->recognizer drift guard: the REAL oneshot no-user
callback's output must be recognized as a sentinel, so producer wording
drift fails a test instead of silently reintroducing false attribution.
- Document the any()-poisoning semantic for multi-select sentinel lists.
Follow-up to the salvaged #81244 commits:
- Timeout/no-user clarify callbacks (CLI timeout, gateway timeout and
delivery failure, oneshot no-user) embed sentinel prose as
user_response; quoting those as '[clarify] user responded: ...' would
be false attribution. Route them to the generic summary path.
- Extract the shared _PRUNE_MIN_CHARS = 200 floor (prune default +
proactive clamp) and cap the clarify summary at _PRUNE_MIN_CHARS - 1,
removing the knife-edge equality the summary's survival depended on
and keeping it out of the >=200-char dedup pass.
- Tests: 4 sentinel shapes + multi-select sentinel; mutation-checked.
handle_max_iterations() appends its runtime summary request as a plain
role="user" row, which SessionDB persists verbatim. On later compaction the
synthetic-turn filters only recognized compaction summaries, continuation
rows, and todo snapshots, so the nudge could be selected as the latest
actionable user turn — becoming the task snapshot / auto-focus input and
getting summarized as "User asked: ...", demoting the real human task.
Metadata flags do not survive SessionDB projection (the reason the existing
markers are content-based), so recognition must key off stable content.
Extract the nudge into a shared MAX_ITERATIONS_SUMMARY_REQUEST constant and
teach _is_synthetic_compression_user_turn() to recognize it, mirroring the
continuation/todo markers. Every _is_actionable_user_turn call site already
pairs the synthetic guard, so the single recognizer change covers anchor
selection, auto-focus, and real-user-turn detection.
Fixes#78580
Review-pass follow-ups (three parallel reviewers, findings verified):
- hermes_state_search.py list_recent_user_messages now drops legacy
standalone compaction handoffs in the decode loop (SQL can't see them:
durable role=user, no display_kind). Closes the /undo N pairing skew
where the in-memory count (new predicate) and the DB soft-delete pick
(old predicate) targeted different turns on legacy sessions. Fetches
with headroom so the requested limit is still honored. 3 new tests,
mutation-checked (no-op'ing the skip fails 2/3).
- _should_skip_model_call_for_reference_handoff: single drive-check scan
(was two — once inside the restore helper, once after); the restore
helper no longer re-scans and its return value now decides the verdict.
- _final_response_from_messages replaced by the _HANDOFF_SKIP_FINAL_RESPONSE
constant it always returned (parameter was unused).
- _handoff_carries_live_user_content delegates to the canonical
_strip_context_summary_handoff_message — also fixes the edge where a
merged-shaped row with an EMPTY preserved prior tail was wrongly
treated as carrying live content.
- Site-level guard test for rollback.restore with a legacy handoff row
(predicate-in-context, complements the unit tests).
Follow-ups on top of the salvaged #80696 fix (review findings):
- Sibling sites: rollback.restore, gateway /retry, CLI /retry and /undo N,
and both CLI resume turn counters now use is_user_originated_turn so
legacy-persisted standalone handoffs (durable role=user, no display_kind)
can never be truncation targets or counted as user turns (#80622
suggested regression 4, dispatcher-wide).
- Site-1 guard: hoist the api_call_count decrement + iteration-budget
refund above the break so a skipped turn no longer leaks a budget unit
and finalize_turn logs the true call count (matches the ollama early-exit
and the site-2 sibling).
- Site-2 guard: run the handoff guard BEFORE reanchoring so a restored
user ask is what the anchor lands on, not a stale pre-restore index.
- SUMMARY_PREFIX: add the mid-tool-loop carve-out the code-side guard
already implements, so a literal-minded model doesn't halt an in-flight
exchange after in-place compaction.
- Skip path returns a short compaction status instead of replaying the
previous turn's answer (finalize_turn would append it as a fresh
assistant row — duplicate prose in transcript and delivery).
After a completed assistant stop, a standalone CONTEXT COMPACTION handoff
could occupy the sole user slot and resume stale Historical Task Snapshot
work with no new human ask. Guard post-compaction continues, hide
standalone handoffs from session dispatch, and harden SUMMARY_PREFIX for
the empty-after-handoff case (#80622).
Two docstring corrections on top of the salvaged #80997 fix — behavior
unchanged, both verified against the code:
- The 'rough growth over-counts every content class' claim is false for
Cyrillic/Greek/Thai/Arabic (chars/4 vs ~2-3 chars/token on o200k):
growth there can under-count up to ~2x (#62605's direction). Document
the real backstops instead: an at/over-threshold real reading clears
the baseline (post-response gate fires on real usage within one call)
and the provider overflow handler compacts reactively.
- Document the two measurement bases (turn-prologue raw messages vs the
loop's fully assembled request that seeds the baseline) and why the
prologue's smaller basis can only OVER-defer — the loop's pre-API
pressure check re-runs the projection with the aligned basis before
every provider call, so a prologue over-defer never skips a needed
compaction.
The rough preflight estimate intentionally overestimates, but not by a
fixed margin: CJK text is counted at ~1.7x its o200k cost and
Responses-mode reasoning replay blobs at several times their billed
cost. Heavy sessions show rough estimates 2-3x real usage and compact
at 35-55% of the real window, stalling turns for minutes and discarding
detail (churn), because the defer guard only tolerated 5% rough growth
and sessions that never compressed had no baseline at all.
Pair every request's rough estimate (note_request_rough_estimate,
recorded in the conversation loop right after the pressure estimate)
with the provider's real prompt_tokens in update_from_response(), then
defer preflight while projected real usage — last real + rough growth
since that reading — stays under the threshold. Rough growth is itself
an overestimate of real growth, so the projection is an upper bound and
deferring below the threshold is safe; the provider's context-overflow
handler remains the backstop.
The baseline no longer ratchets on defer: it is refreshed by the
response pairing, and advancing it without a matching real reading
would shrink apparent growth and defer on stale data.
Review follow-up: after the walk-back widening, the exempted assistant
is often not the final message, and the partial-batch shape is
byte-identical to a settled-but-malformed orphan — so say 'presumed
pending' and document WHY presuming is safe (sanitize_api_messages
step 2 stubs any genuinely unanswered call pre-API on every path).
Widen #79293's trailing-in-flight guard from 'last message is assistant'
to 'last non-tool message is assistant': a multi-call batch snapshotted
between the executor's per-result appends looks like
[..., assistant(c1,c2,c3), tool(c1)] — c2/c3 are pending, not orphaned,
but the tail-only guard missed that shape and stripped them (same silent
result loss as the original bug, via concurrent /compress or the gateway
hygiene pass).
Preserving is safe on both shapes: the pre-API chokepoint
(sanitize_api_messages step 2) injects stub results for any call that
genuinely never gets an answer, while stripping a live call silently
loses its late result.
test_sanitizer_strips_orphaned_keeps_valid's mixed valid/orphan shape
moves mid-list — at the tail it is byte-identical to a live partial
batch and the sanitizer now correctly presumes in-flight there.
New regression test fails without the walk-back (c2/c3 stripped),
passes with it.
Tool_executor.py appends role=tool results AFTER running each call. When
context compression fires mid-chain, the trailing assistant(tool_calls)
message is a pending request whose result has not yet been appended.
_sanitize_tool_pairs previously stripped it as an 'orphan', so when the
executor later appended the real result, repair_message_sequence dropped
it as unmatched and the completed side effect (and final synthesis) was
lost. Preserve the trailing in-flight call verbatim; only genuinely
orphaned calls in the discarded region are stripped.
Adds regression tests: three unit tests for _sanitize_tool_pairs plus an
end-to-end test reproducing compression -> side-effect completion ->
result-returned flow. Confirmed failing on pre-fix code, passing with
the fix.
Three review follow-ups on the salvaged #79286 commit:
- update_model() zeroed the in-memory prune runway but left the durable
model_config copy stale, breaking the method's own durable-sync
discipline (the strike reset three lines above keeps its durable copy
in sync). A restart after a model switch resurrected a runway
computed under the old model's trigger sizes. New
_clear_durable_proactive_prune_rearm() removes the persisted key via
patch_session_model_config() without touching the transcript.
- The archive_and_compact capability check ran AFTER the expensive
3-pass prune scan, so a duck-typed session store lacking the method
paid the full scan on every eligible iteration forever with pruning
permanently no-opping. Hoist it above the scan (all in-tree stores
pass a real SessionDB; this only affects third-party stores).
- _load_proactive_prune_rearm_tokens now uses the shared
get_session_model_config_value() accessor instead of inlining a 5th
copy of the model_config JSON parse, matching its sibling loaders'
typed-accessor pattern.
Also documents why the rotation-publish-failure branch restores only
the runway field rather than the full attempt snapshot.
Tests: model-switch durable clear, patch_session_model_config
merge/delete/no-op, and a guard proving incapable stores skip the scan.
A successful compaction frees the largest allocation a long session ever
drops (the compressed-away message dicts), but Python's arena allocator
keeps those pages in the heap — RSS retains the pre-compaction
high-water mark until exit. #76905's trim_memory lifecycle covers the
gateway/TUI housekeeping loops but not the CLI compression path.
Call trim_memory(reason='post-compression') at the compression-success
point in ContextCompressor.compress(), following the house pattern
(lazy import in try, debug-level log on failure). The helper is
glibc-gated, config-gated and rate-limited, so it is a safe no-op on
other platforms and cannot fail compression.
Re-expresses the intent of #70782 (JonthanaHanh), which reached for a
bare gc.collect(); trim_memory is the house mechanism and already
wraps a collect.
A host timeout previously left the timed-out worker holding the durable
per-session compression lock AND refreshing its lease indefinitely, so a
truly hung summary blocked every later compression attempt; and a LATE
successful summary could clear the failure cooldown the host had just
recorded.
Transplant the lease-cancellation invariants from PR #71569
(@ciabata-git): the worker publishes an idempotent, holder-scoped release
hook on the fence once it owns the durable lock (begin_lock_setup /
register_cancelled_lock_release close the acquire→publish race), the
refresher start is serialized against the release path, and the host
invokes the hook on idle timeout, hygiene timeout, and every unwind
(revoke_commit_admission now also releases). ABA safety: the SessionDB
release is holder-qualified (DELETE ... WHERE holder = ?), so a stale
release can never free a replacement holder's lease.
State ordering: the compressor consults a fence-cancellation check BEFORE
clearing the failure cooldown, so a late worker cannot undo the host's
timeout cooldown; the check is installed only for the fenced call and
removed in a finally.
Regression implements the reviewer's exact 5-step scenario: summary
blocked indefinitely → host timeout → a NEW compressor acquires the
durable lock while the old summary is STILL blocked → old worker released
→ it cannot clear cooldown, release the new holder's lease, or publish
stale state.
PR #76354 review, blocking finding 4 / merge gates 4 + 5.
Co-authored-by: ciabata-git <ciabata-git@users.noreply.github.com>
Three code-reuse fixes applied during salvage:
1. Reuse _relative_time from hermes_cli/main.py instead of duplicating
the relative-time formatting logic in hermes_cli/status.py.
2. Extract _stamp_hygiene_compression_provenance helper in gateway/run.py
to deduplicate the two nearly-identical try/except blocks that stamp
compression timeout/abort provenance in the hygiene path.
3. Add ContextCompressor.record_timeout_failure() method and use it from
the in-agent compress_context timeout callback instead of re-implementing
the (60, 300, 900) cooldown ladder inline. The existing summary-LLM
exception handler already has this ladder — now both paths share one
method.
Makes interrupt-protected context compression cancellable by an explicit
user or lifecycle stop, without weakening protection against ordinary
incoming messages, voice interjections, or active-turn redirects.
Separates explicit hard cancellation from ordinary interrupt/redirect
state with a dedicated threading.Event; introduces
AuxiliaryExplicitCancellation as an attempt-local frozen-cause signal;
isolates the synchronous provider callback in a bounded daemon worker
during protected compression; atomically linearizes Codex timeout
cleanup against explicit cancellation; propagates hard cancellation
through child agents and explicit stop surfaces; serializes hard-cancel
admission against compression commit admission with
CompressionCommitFence; aborts before session rotation or late DB commit,
restores in-place transcript mutations and compressor state, and releases
the heartbeat and compression lease.
Based on #74449 by @suparious. Resolved merge conflicts in
agent/context_compressor.py (feasibility check + try/except) and
tui_gateway/methods_session.py.
- Reuse telemetry['middle_window_tokens'] for the skip's middle estimate
(is-None fallback to a fresh estimate) so log and telemetry agree
- Declare prellm_skip_count in the base telemetry schema (fixed shape)
- Defer _derive_auto_focus_topic into the non-skip branch (user-turn scan
was wasted work on every skip)
- Document the skip in compress()'s Algorithm list and force: arg doc
- Drop dead call_llm patches from 7 tests (unreachable with
_generate_summary mocked)
When the middle section is < 10% of threshold tokens AND at least one prior
real-usage ineffectiveness strike has been recorded, skip the expensive LLM
summarization call and fall through to the deterministic message-dropping
path. Without this guard, a tool-heavy session where the protected tail
already holds most of the tokens can burn 500+ seconds on a summary call
that replaces a few lightweight messages with negligible token savings.
Key design decisions per GottZ review on PR #60451:
1. Separate _prellm_skip_count counter — never increments
_ineffective_compression_count (the strike counter that latches at >=2
to disable compression entirely). One real strike + one skip must NOT
permanently lock out compression until /new.
2. feasibility_skip sentinel flag — exempts skips from the abort branch
(abort_on_summary_failure / _last_summary_auth_failure /
_last_summary_network_failure). A stale failure flag from a prior
cycle must not turn a deliberate skip into a full abort.
3. reason=None for feasibility-skip fallbacks — a stale _last_summary_error
from an earlier real failure must not be embedded into the skip's
deterministic fallback marker.
4. info-level logging for feasibility-skip fallbacks (not warning) — this
is an intentional optimization, not a failure.
Skipped when force=True (manual /compress) so auth/error handling paths
are always exercised on explicit user request.
Adds 6 regression tests (TestPreLlmFeasibilityCheck) covering:
- Strike counter isolation
- Stale auth/network failure flag immunity
- force=True bypass
- No-skip when no prior strikes
- Counter reset on session reset
Co-authored-by: Cursor <cursoragent@cursor.com>
Co-authored-by: TRON <tron-agent@agentmail.to>
The micro-compaction defrag pass (_defrag_rolling_summary) rewrites the
newest MICRO marker's content and pops _DB_PERSISTED_MARKER from the
LIVE dict in place — the same in-place pop class finalize_turn's fill
site was fixed for in #75170. Without invalidation the bounded
flush-scan cursor identity-skips the rewritten marker row and the
defragged rolling summary never reaches state.db (resume rehydrates a
stale summary).
The compressor holds no agent reference, so the pop site raises
_flush_scan_cursor_invalidated and the finalize_turn micro-compaction
block consumes it, setting agent._db_flush_scan_prefix = None.
The module-scope pop sites (context_compressor.py:175/224) operate on
fresh copies — identity-breaking by construction — and need no flag.
Follow-up to #75170 (fix-the-class sweep of _DB_PERSISTED_MARKER
in-place pops).
Companion to the preflight fix: _estimate_msg_budget_tokens charged
reasoning_details at chars/4 via _REPLAY_BUDGET_KEYS, so the signed/base64
envelope (measured 72% of the reasoning mass on Anthropic-wire sessions)
consumed the tail budget and _find_tail_cut_by_tokens summarized away real
transcript to make room for tokens that are never sent (69 messages on the
measured session; up to ~4.8x budget inflation on thinking-heavy histories).
Per the #51800 counter-argument, actual thinking TEXT stays visible to the
budget: _reasoning_details_text_chars counts thinking/text/summary fields
and skips signature/data/encrypted blobs, and the text is skipped entirely
when reasoning/reasoning_content already carries the identical prose (so it
is charged once, not twice). codex_reasoning_items remains fully charged —
Codex Responses genuinely replays it every request (#55572).
Sabotage-verified: restoring reasoning_details to _REPLAY_BUDGET_KEYS fails
the new envelope and double-charge tests.
Fix#75588
## Root cause
When a short conversation ends in a tool-call/result group and the
protected head alignment reaches the end of the message list,
_find_tail_cut_by_tokens() could return len(messages) + 1. This
happened because the final return used max(cut_idx, head_end + 1)
which could push past the array length when head_end >= len(messages).
The out-of-range value then propagated into _find_context_summaries()
which iterated range(start, end) and indexed messages[idx] without
clamping, raising IndexError and failing the active gateway turn.
## Fix
Two-layer defense:
1. Source fix: _find_tail_cut_by_tokens() now clamps its return to
min(n, ...) so it never exceeds len(messages).
2. Defensive clamp: _find_context_summaries() now bounds start/end
to [0, len(messages)] so even if a future caller passes bad values,
it cannot crash.
## Verification
- 7 new regression tests for the exact boundary conditions
- All 214 existing test_context_compressor.py tests pass
Phase 2 review findings on the salvage branch:
C1 (critical): batch and micro summary markers share
COMPRESSED_SUMMARY_METADATA_KEY, and compress() never reset micro state.
After micro absorbed exchanges 1..k, a batch compaction summarizing
1..m (m>k) could fire; the next micro pass's supersede then dropped the
batch marker (whose content the stale rolling summary does NOT contain)
and archive_and_compact immediately made the loss durable. Defrag had
the same hazard: it rewrote "the newest marker" even if that was a
batch marker. Empirically confirmed with a probe (batch marker content
destroyed in one pass).
Fix, three parts:
- Micro-created markers now carry MICRO_COMPACT_MARKER_KEY; supersede
and defrag only ever touch micro-tagged markers. Rehydration in
_resolve_compact_cursor tags the marker it absorbs (containment
proof), which safely covers adopting a batch marker as the new
rolling base after a reset.
- compress() success path resets micro rolling summary/cursor state so
a stale summary can never claim cumulativeness over a batch marker.
- Regression tests for both directions plus the reset.
W4: _splice_micro_compact_result no longer strips _db_persisted stamps
from surviving messages. Micro archives in place under the SAME session
id (unlike batch's child-session rotation, #57491), so surviving stamps
are accurate; stripping them meant an archive_and_compact failure left
every previously-persisted message unstamped and the next append-only
flush re-inserted them all as duplicate active rows.
W5: finalize_turn micro gate now checks agent._persist_disabled —
persistence-isolated fork agents (background review) must not burn an
aux call per review turn, and must never archive_and_compact the
canonical session rows if their compressor ever gains a DB binding.
W1: _serialize_one_exchange now delegates to _serialize_for_summary
(was a ~70-line near-verbatim copy; one serializer, one place to fix).
S4: _find_one_exchange boundary guard rejects only assistant/tool
boundaries (the actual alternation hazard) instead of requiring user —
a stray mid-list system/injected message can no longer wedge the
cursor forever.
5 new regression tests; 38 micro/prune tests, 400 compression-suite
tests, 61 finalize/persist tests pass; ruff clean.
abundantbeing