perf(conversations): Fence commits on caller-owned history cursors - #1228
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perf(conversations): Fence commits on caller-owned history cursors#1228sentry-junior[bot] wants to merge 8 commits into
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Make append return the inserted delta and live history cursor so commitMessages can advance committedSeq/messageSeqs without a second loadCurrentHistory of the entire active version. Co-Authored-By: David Cramer <david@sentry.io>
Co-Authored-By: David Cramer <david@sentry.io>
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dcramer
marked this pull request as ready for review
August 4, 2026 18:20
Separate message and turn-context appends, return committedSeq from append, and let turn-session checkpoints pass an already-materialized base so commitMessages only writes the delta after verifying the live cursor. Co-Authored-By: David Cramer <david@sentry.io>
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Exact global-cursor equality rejected checkpoints after MCP connects, auth requests, and other non-agent events advanced seq. Fence on agent message prefix and message seqs instead, and adopt the live cursor when only host-only facts moved it.
Session summaries use a strict schema without fence fields. messageSeqs was left on the summary payload, so index readers rejected every new summary and hid sessions from operational listings.
Reject non-prefix session bases so handoff/compaction take the cold path, adopt concurrent same-prefix agent commits past a stale fence, and cover the product checkpoint/resume path with integration tests. Co-Authored-By: David Cramer <david@sentry.io>
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History fences can adopt concurrent same-prefix commits, but session metadata must not regress. Re-check the live turn session after commit and refuse delayed running checkpoints that would overwrite awaiting_resume/completed/failed state. Co-Authored-By: David Cramer <david@sentry.io>
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Reviewed by Cursor Bugbot for commit ab58929. Configure here.
expectedVersion must prefer the stale caller base over a fresh store read at upsert entry; otherwise delayed running checkpoints skip the lifecycle guard and can still overwrite awaiting_resume. Co-Authored-By: David Cramer <david@sentry.io>
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Stop durable agent-history checkpoints from reloading and deep-comparing the full active history on every write. Callers that already hold a committed projection can fence on that cursor and append only the delta.
Cursor-fenced commits
commitMessagesaccepts an optionalbasewithcommittedSeq,historyVersion,messageSeqs, messages, and provenance. When present, it verifies the live cursor, then writes only new durable messages. Turn-session checkpoints pass the already-materialized session as that base and persistmessageSeqsfor the next fence.Fence hardening
Session checkpoints only reuse a prior base when the next durable messages are a true prefix extension, so handoff/compaction replacements take the cold path. After handoff, resume materialization adopts the replacement epoch's fence cursors instead of keeping the pre-handoff
committedSeq/messageSeqs. When the live store advanced past a stale base, commits adopt concurrent same-prefix agent writes (for example a racingturn_endbefore timeout continuation) and still reject divergent rewrites. Host-only cursor advances remain allowed.Session lifecycle guard
History adoption alone is not enough: a delayed
runningcheckpoint must not overwriteawaiting_resume/completed/failedsession metadata that landed meanwhile. After the history commit,upsertAgentTurnSessionRecordre-reads the live session and rejects lifecycle regressions (and older same-rank slices). Completed delivery retries stay idempotent once a terminal record exists.Separate appends
Native agent-history messages and host-only
turn_contextevents are appended in separate store calls. Message sequence assignment no longer depends on mixed-event ordering.Append result
appendreturns{ historyVersion, inserted: [{ seq }], committedSeq }so commit paths advance without a post-write full history reload. Session summaries strip fence fields (messageSeqs,committedSeq,historyVersion) so strict summary readers keep working.Cold paths without a base still load current history once for prefix validation. Coverage includes fenced deltas, host-only cursor advances, concurrent same-prefix adoption, delayed running-vs-awaiting_resume session races, handoff yield/resume, tool-timeout continuation, and product-path mid-turn checkpoints after MCP connect.