fix(compression): guard against cross-session stale _previous_summary contamination#38832
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… contamination When a cron or background session compacts, it sets _previous_summary for iterative updates. If that session ends without /new or /reset (which calls on_session_reset()), the stale summary survives on the ContextCompressor instance. A subsequent live messaging session's compaction then injects it as 'PREVIOUS SUMMARY:' into the summarizer prompt — contaminating the live session with unrelated content from the prior session. Add an else guard in compress(): when no handoff summary is found in the current messages but _previous_summary is non-empty, discard it so _generate_summary() starts fresh instead of iteratively updating a stale cross-session summary. Fixes NousResearch#38788
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Merged via #41717 (commit 8513a6a) — your point-of-use guard in |
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What
When a cron or background session compacts, the ContextCompressor sets
_previous_summaryfor iterative summary updates. If that session ends without/newor/reset(which callon_session_reset()), the stale summary survives on the shared instance. A subsequent live messaging session's compaction then injects it asPREVIOUS SUMMARY:into the summarizer prompt — contaminating the live session with unrelated content.Root Cause
In
compress(), when no handoff summary is found in the current messages (via_find_latest_context_summary), but_previous_summaryis non-empty from a prior session, the code silently carries the stale value forward._generate_summary()then enters its iterative-update branch (line 1343), injecting the stale cron summary into the summarizer prompt.Fix
Added an
elifguard incompress()(after the handoff-search block, line 1911): when no handoff summary is found in the current messages but_previous_summaryis non-empty, discard it. This ensures_generate_summary()starts fresh when the summary state belongs to a different session.The guard does NOT fire when a handoff summary IS found in the current messages — iterative updates within the same session are preserved.
Tests
Three new tests in
tests/agent/test_context_compressor_cross_session_guard.py:_previous_summaryset from a simulated prior session, no handoff in current messages → cleared to None_previous_summarypreserved (guard doesn't fire)_previous_summaryalready None → guard is no-opAll 33 tests pass (26 existing + 7 in this change set).
Related
Fixes #38788