fix(agent): preserve recent turns during compression - #39170
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Rebased onto origin/main and resolved the context-compressor merge conflict. Scoped verification passed ( |
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A context-compaction handoff banner is inserted with role="user" when the protected head ends in an assistant/tool message. On a resumed or multi-compaction session, _find_last_user_message_idx would return that banner as the latest user turn, so _ensure_last_user_message_in_tail anchored the tail to the summary and rolled the genuine last user message into the next compaction — the exact active-task loss the anchor exists to prevent (#10896/#22523). Reuse the existing _is_context_summary_content helper to skip summary banners when locating the last real user message. Salvaged from #36626 by Frank Song (issue #36624). The PR's other two changes (demoting completed tool results inside the protected tail; a preflight compression_exhausted result) are superseded on current main by the min_tail floor (#39170), the no-op compression counting (#40803), and the existing 413/disabled terminal-error paths.
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A context-compaction handoff banner is inserted with role="user" when the protected head ends in an assistant/tool message. On a resumed or multi-compaction session, _find_last_user_message_idx would return that banner as the latest user turn, so _ensure_last_user_message_in_tail anchored the tail to the summary and rolled the genuine last user message into the next compaction — the exact active-task loss the anchor exists to prevent (NousResearch#10896/NousResearch#22523). Reuse the existing _is_context_summary_content helper to skip summary banners when locating the last real user message. Salvaged from NousResearch#36626 by Frank Song (issue NousResearch#36624). The PR's other two changes (demoting completed tool results inside the protected tail; a preflight compression_exhausted result) are superseded on current main by the min_tail floor (NousResearch#39170), the no-op compression counting (NousResearch#40803), and the existing 413/disabled terminal-error paths.
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A context-compaction handoff banner is inserted with role="user" when the protected head ends in an assistant/tool message. On a resumed or multi-compaction session, _find_last_user_message_idx would return that banner as the latest user turn, so _ensure_last_user_message_in_tail anchored the tail to the summary and rolled the genuine last user message into the next compaction — the exact active-task loss the anchor exists to prevent (NousResearch#10896/NousResearch#22523). Reuse the existing _is_context_summary_content helper to skip summary banners when locating the last real user message. Salvaged from NousResearch#36626 by Frank Song (issue NousResearch#36624). The PR's other two changes (demoting completed tool results inside the protected tail; a preflight compression_exhausted result) are superseded on current main by the min_tail floor (NousResearch#39170), the no-op compression counting (NousResearch#40803), and the existing 413/disabled terminal-error paths.
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A context-compaction handoff banner is inserted with role="user" when the protected head ends in an assistant/tool message. On a resumed or multi-compaction session, _find_last_user_message_idx would return that banner as the latest user turn, so _ensure_last_user_message_in_tail anchored the tail to the summary and rolled the genuine last user message into the next compaction — the exact active-task loss the anchor exists to prevent (NousResearch#10896/NousResearch#22523). Reuse the existing _is_context_summary_content helper to skip summary banners when locating the last real user message. Salvaged from NousResearch#36626 by Frank Song (issue NousResearch#36624). The PR's other two changes (demoting completed tool results inside the protected tail; a preflight compression_exhausted result) are superseded on current main by the min_tail floor (NousResearch#39170), the no-op compression counting (NousResearch#40803), and the existing 413/disabled terminal-error paths.
santhreal
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A context-compaction handoff banner is inserted with role="user" when the protected head ends in an assistant/tool message. On a resumed or multi-compaction session, _find_last_user_message_idx would return that banner as the latest user turn, so _ensure_last_user_message_in_tail anchored the tail to the summary and rolled the genuine last user message into the next compaction — the exact active-task loss the anchor exists to prevent (NousResearch#10896/NousResearch#22523). Reuse the existing _is_context_summary_content helper to skip summary banners when locating the last real user message. Salvaged from NousResearch#36626 by Frank Song (issue NousResearch#36624). The PR's other two changes (demoting completed tool results inside the protected tail; a preflight compression_exhausted result) are superseded on current main by the min_tail floor (NousResearch#39170), the no-op compression counting (NousResearch#40803), and the existing 413/disabled terminal-error paths.
Gravezzz
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A context-compaction handoff banner is inserted with role="user" when the protected head ends in an assistant/tool message. On a resumed or multi-compaction session, _find_last_user_message_idx would return that banner as the latest user turn, so _ensure_last_user_message_in_tail anchored the tail to the summary and rolled the genuine last user message into the next compaction — the exact active-task loss the anchor exists to prevent (NousResearch#10896/NousResearch#22523). Reuse the existing _is_context_summary_content helper to skip summary banners when locating the last real user message. Salvaged from NousResearch#36626 by Frank Song (issue NousResearch#36624). The PR's other two changes (demoting completed tool results inside the protected tail; a preflight compression_exhausted result) are superseded on current main by the min_tail floor (NousResearch#39170), the no-op compression counting (NousResearch#40803), and the existing 413/disabled terminal-error paths.
waym0reom3ga
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A context-compaction handoff banner is inserted with role="user" when the protected head ends in an assistant/tool message. On a resumed or multi-compaction session, _find_last_user_message_idx would return that banner as the latest user turn, so _ensure_last_user_message_in_tail anchored the tail to the summary and rolled the genuine last user message into the next compaction — the exact active-task loss the anchor exists to prevent (NousResearch#10896/NousResearch#22523). Reuse the existing _is_context_summary_content helper to skip summary banners when locating the last real user message. Salvaged from NousResearch#36626 by Frank Song (issue NousResearch#36624). The PR's other two changes (demoting completed tool results inside the protected tail; a preflight compression_exhausted result) are superseded on current main by the min_tail floor (NousResearch#39170), the no-op compression counting (NousResearch#40803), and the existing 413/disabled terminal-error paths.
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A context-compaction handoff banner is inserted with role="user" when the protected head ends in an assistant/tool message. On a resumed or multi-compaction session, _find_last_user_message_idx would return that banner as the latest user turn, so _ensure_last_user_message_in_tail anchored the tail to the summary and rolled the genuine last user message into the next compaction — the exact active-task loss the anchor exists to prevent (NousResearch#10896/NousResearch#22523). Reuse the existing _is_context_summary_content helper to skip summary banners when locating the last real user message. Salvaged from NousResearch#36626 by Frank Song (issue NousResearch#36624). The PR's other two changes (demoting completed tool results inside the protected tail; a preflight compression_exhausted result) are superseded on current main by the min_tail floor (NousResearch#39170), the no-op compression counting (NousResearch#40803), and the existing 413/disabled terminal-error paths.
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What does this PR do?
Fixes context compression tail selection so token-exhausted compactions keep a bounded run of recent messages verbatim instead of preserving only the latest user anchor plus a tiny tail. This prevents recent assistant/tool context immediately before the latest ask from being folded into the summary, while capping the message floor so large tool-output tails can still be compacted.
Related Issue
Fixes #9413
Type of Change
Changes Made
agent/context_compressor.py: replace the hard-coded 3-message protected tail floor with a boundedprotect_last_n-aware floor, capped at 8 messages and constrained to leave a real middle window to summarize.tests/agent/test_context_compressor.py: add a regression test for tiny-budget compression preserving recent turns before the latest user ask.How to Test
HERMES_HOME=/private/tmp/hermes-agent-test-home-issue-new-5b851828 PATH="$VIRTUAL_ENV/bin:$PATH" /opt/homebrew/bin/timeout -k 30 480 sh -c 'pytest tests/ -q -x --timeout=60 "$@"' sh/opt/homebrew/bin/timeout -k 30 480 pytest tests/agent/test_context_compressor.py -q/opt/homebrew/bin/timeout -k 30 480 pytest -q -x --timeout=60 tests/agent/test_context_compressor.py tests/run_agent/test_compression_boundary.py tests/agent/test_compressor_image_tokens.py tests/agent/test_compressor_historical_media.py tests/agent/test_context_compressor_summary_continuity.py tests/run_agent/test_compressor_fallback_update.pyruff check agent/context_compressor.py tests/agent/test_context_compressor.pypython scripts/check-windows-footguns.py agent/context_compressor.py tests/agent/test_context_compressor.pygit diff --checkChecklist
Code
fix(scope):,feat(scope):, etc.)pytest tests/ -qand all tests passDocumentation & Housekeeping
docs/, docstrings) — or N/Acli-config.yaml.exampleif I added/changed config keys — or N/ACONTRIBUTING.mdorAGENTS.mdif I changed architecture or workflows — or N/AFor New Skills
hermes --toolsets skills -q "Use the X skill to do Y"Screenshots / Logs
tests/agent/test_context_compressor.py -q: 92 passed in 40.64s.ruff check agent/context_compressor.py tests/agent/test_context_compressor.pypassed.python scripts/check-windows-footguns.py agent/context_compressor.py tests/agent/test_context_compressor.pypassed.git diff --checkpassed.HERMES_HOME; it stopped early in unrelatedtests/acp/test_edit_approval.py::test_write_file_approval_mutates_and_request_includes_diffbecause this sandbox treats pytest's/private/var/.../Ttemp path as a sensitive system path, sowrite_filerefused the test write before the suite reached compressor coverage.