feat(memory): track trajectory elongation from hard compaction (#1739)#1787
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feat(memory): track trajectory elongation from hard compaction (#1739)#1787
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Add compaction_hard_count and turns_after_hard_compaction metrics to MetricsSnapshot. Increment hard compaction counter and record per-segment turn counts at each hard compaction event. Log both at agent shutdown via tracing::info! for session-level trajectory analysis. Turn counter is incremented before all early-return guards in maybe_compact so proactive compression and exhaustion paths are counted accurately.
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Summary
compaction_hard_count: u64andturns_after_hard_compaction: Vec<u64>toMetricsSnapshotCompactionTier::Hardevent inmaybe_compact()compacted_this_turn) so no turns are silently droppedshutdown()and both fields are logged viatracing::info!when at least one hard compaction occurredMotivation
JetBrains Research (Dec 2025) found LLM summarization causes agents to run 13-15% longer on average. This change adds the instrumentation needed to detect and measure trajectory elongation in real Zeph sessions via
.local/testing/debug/session.log.Test plan
cargo +nightly fmt --check— passcargo clippy --workspace --features full -- -D warnings— passcargo nextest run --config-file .github/nextest.toml --workspace --features full --lib --bins— 5581 passed, 12 skippedcompaction_hard_count_zero_by_default,compaction_hard_count_increments_on_hard_tier,compaction_turns_after_hard_tracks_segments,compaction_turn_counter_increments_before_exhaustion_guard