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perf(server): long threads open about 2.5x faster - #34014
Opening a long thread spent most of its server time scanning tool output JSON with LIKE, on every read, for every row.
Projection-store read, heaviest thread
Before
After
Open a long thread (median)
62 ms
24 ms
Open + load one older page (median)
127 ms
50 ms
6 clients opening at once (p95)
350 ms
233 ms
Save one dynamic tool item
—
+0.03 ms
Problem
Thread windows decide whether a work group can be deferred. A dynamic_tool item whose output renders inline (HTML render, MCP app, viewed image, delegated task) must stay visible.
That check was a LIKE '%...%' over payload_json. It ran in retainedWindowRows for every row in the window, and in readTimelineIndex for the whole thread when paging older history in deferred mode.
Tool payloads can be large, so on a long thread this scan took more time than the rest of the query.
Change
New column orchestration_v2_projection_turn_items.inline_work_output, written in the turn-item.updated upsert in ProjectionStore.ts. That upsert is the only writer to the table.
Both read paths now read the column instead of scanning the payload:
- AND NOT (${inlineWorkOutput})+ AND inline_work_output = 0
The write side mirrors the old LIKE patterns with case-insensitive regexes (_ becomes .). For delegated tasks it finds the first "toolName":" and tests the rest of the payload once, so payloads with many nested tool names can't stall a save.
Migration 081_TurnItemInlineWorkOutput adds the column and backfills it with the same LIKE predicate the read used before, so existing threads keep the same grouping.
Trade-offs
The predicate now lives in two places: the regex in ProjectionStore and the frozen backfill in the migration. Both have a comment pointing at each other.
The MCP attachment query further down ProjectionStore still uses LIKE. It runs on one item, not a window, so I left it.
The backfill took a few seconds on a 6.3 GB database and flagged about 5.6k rows.
Scope and approval
No prior issue or discussion. I think this fits the small, focused fix exception:
The defect: every thread open and every older-history page re-ran a LIKE '%...%' scan over tool payload JSON to compute a value that only changes when the item is saved. On a long thread that scan took more than half the read time.
Why it's focused: it fixes one problem in one owner. The value moves from read time to the one place that writes turn items (ProjectionStore's turn-item.updated upsert), plus a migration to backfill existing rows.
No behavior change: the same items stay inline and the same work groups defer. The backfill uses the exact predicate the read used before, and the writer matches it on every dynamic_tool row of a real 12k-row database. No contract, client, provider, setting or default changes.
If maintainers would rather track this in an issue first, I'm happy to open one.
Verification
Benchmarked at the projection-store level on a read-only copy of a real database, control 1fed70cd19, Node 26. No WebSocket or UI time is included, so the time users see goes down less than this.
The concurrency gain is smaller (about 1.5× at 6 clients) because decoding and the remaining SQL now take most of the time.
Tests cover the backfill for each inline kind and the writer flag through projectionStore.apply.
Macroscope's review found this PR approvable — Thread reads use a precomputed inline-output flag instead of repeatedly scanning tool payloads. The additive migration preserves payload data, and reported large-database backfill timing supports limited startup impact.
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Walkthrough
Migration 83 adds and backfills an inline-work-output flag for turn items. ProjectionStore computes and stores the flag, then uses it in deferred-work selection and timeline indexing. Tests cover migration backfills and projection behavior.
Changes: Inline work output
Layer / File(s)
Summary
Add and backfill the flag apps/server/src/persistence/Migrations/083_TurnItemInlineWorkOutput.ts, apps/server/src/persistence/Migrations.ts, apps/server/src/persistence/Migrations/083_TurnItemInlineWorkOutput.test.ts, apps/server/src/persistence/reconcileV2PreviewMigration.test.ts
Migration 83 adds a non-null inline_work_output column with a default of 0, then marks matching dynamic-tool rows. The migration registry and expected migration lists include migration 83. Tests check the backfill and migration sequence.
Write and use the flag apps/server/src/orchestration-v2/ProjectionStore.ts, apps/server/src/orchestration-v2/ProjectionStore.test.ts
ProjectionStore classifies inline output and stores the flag when it inserts or updates turn items. Deferred-work selection excludes rows marked as inline output, and timeline indexing reads the stored flag. Tests cover inline dynamic-tool payloads and restoring a completed command execution.
The change stores the inline-output flag at write time and backfills it with a migration, so thread opens avoid scanning payloads. No actionable merge-blocking risk remains in the reviewed changes.
Pre-merge checks: 4
Check name
Status
Explanation
Title check
The title "perf(server): long threads open about 2.5x faster" describes the main goal of the change. The PR moves inline-work-output detection from read-time LIKE scans over payload JSON to a stored i…
Description check
The description covers the problem (LIKE scans over tool payload JSON on every read), the change (new inline_work_output column, read-path updates, backfill migration), and verification (benchmarks, t…
Linked Issues check
Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check
Check skipped because no linked issues were found for this pull request.
Full details: Title check
Explanation
The title "perf(server): long threads open about 2.5x faster" describes the main goal of the change. The PR moves inline-work-output detection from read-time LIKE scans over payload JSON to a stored inline_work_output column, which is the mechanism behind the speedup. The title is a conventional commit that names the affected area (server) and the user-visible effect.
Full details: Description check
Explanation
The description covers the problem (LIKE scans over tool payload JSON on every read), the change (new inline_work_output column, read-path updates, backfill migration), and verification (benchmarks, tests, runtime checks). It also includes a scope and approval section that explains the small-fix exception and notes that no prior issue exists. Two items diverge from the template. The Problem section is a bulleted list instead of a sentence or two, and the Verification section cites benchmarks run on a copy of a real database. The description also uses 'Opus 5.5 via Claude Code' as the agent attribution, which the template requests. Overall, the description is mostly complete.
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Actionable comments posted: 1
Fix comments: Fix CodeRabbit comments on this PR
Prompt to fix all issues
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only still-valid issues, skip the rest with a brief reason, keep changes
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Inline comments:
Review comments at @apps/server/src/orchestration-v2/ProjectionStore.ts:
- Around line 2006-2009: Update INLINE_WORK_OUTPUT and its dynamic-tool matching
path to locate the first toolName prefix and scan only the remaining payload
once, while preserving cross-field matching for delegate.task; add a test
confirming that behavior.
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The delegate_task regex rescanned the rest of the payload for every nested toolName, so a large payload could stall the event loop on save.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
merged current main (merge commit, no rebase). main added its own migration 81 (ProjectionMessageSearchText), so this PR's migration is now 082_TurnItemInlineWorkOutput. the registry, its test and the V2 preview ledger list follow. no other code changed.
the CodeRabbit finding about rescanning "toolName":" prefixes was already fixed in c6903399a8 (isInlineWorkOutput finds the first prefix and scans its suffix once).
vp run check:changed passes on node 26.12.1: format, lint, knip, typecheck, and 71 tests in 5 files, including the 082 migration and ProjectionStore tests.
Earlier verification (gpt-6.1-sol, at c6903399a8)
Verified in a real dev environment
verified runtime behavior at c6903399a8db4ec1d566c266815bf7c1fe7f164c on linux using the real dev web app, repository playwright and google chrome. no source changes were needed.
created a project pointing at a real git repository and 13 codex gpt-6.1-sol turns through the app on github/main (04f6cfca87). one completed turn contains 160 actual command calls. stopped main before starting the exact pr head with the same app-created state and an explicit isolated home.
reopened the conversation, clicked load earlier turns, expanded the deferred work and its command list, and checked that the inline html output remained visible. both revisions returned a 160-item deferred group; all three expansion pages succeeded.
migration preserved all 218 transcript items. the cached flag matched the original LIKE predicate on every row: 218 rows / 1 inline output / 0 mismatches.
a fresh codex turn on the pr ran git status and published another real html output. it survived reload. the writer then matched on 224 rows / 2 inline outputs / 0 mismatches.
60 focused projection-store and migration tests passed through blacksmith on node 26. github checks are passing at this head.
the claimed 2.5x speedup. this app-created history exercises the changed read and write paths but does not reproduce the original large-dynamic-tool-payload slowdown at its reported scale. no end-to-end speedup claim follows from this pass.
native desktop, ios/android, remote relay/tunnel connections, other providers, MCP app outputs, viewed-image output retention, or delegated-task outputs.
html_preview timed out twice on main; html_render succeeded on both revisions. the first oversized parallel tool dispatch also left two command items running on main; shutdown terminalized those items. the successful 160-command turn used smaller awaited batches.
Main took migration 082 (TurnItemConversationIndex), so the inline work output migration moves to 083.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
…cy-research
Renumber the inline-output migration to 095 (main took 083-094), extend the
write-time check and the backfill with main's send_to_user and sentMessage
predicates, and read the column in main's run-scoped inline-output lookup.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
The merge with main dropped the attempt_id and attempt_status columns from
readTimelineIndex, so a jump to an entry folded work across attempts.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Real-server comparison on the same 8-vCPU Linux VM, Node 26.13.1. Fresh synthetic state on each commit; replay provider used only for seeding. Primary seed: 200 human-authored turns × 11 tools × 40,000 text bytes, with one inline HTML item every twentieth turn. Five rounds per commit: three warmup pairs, 40 timed open/older pairs, then 15 batches of six concurrent opens. Captures render the measurement output; raw samples are included in the reproduction bundle.
Opening is measurably faster: median across rounds falls from 52.22 to 35.33 ms, about 1.48×. The 16.89 ms improvement exceeds each side's round spread: 14.93 ms on base and 7.33 ms on head. Returned content and ordering match after removing generated identifiers and timestamps. Both return 140 initial items and 280 older items, with the known inline item retained separately on each page.
The supplemental case verifies deferred grouping directly: both older pages retain 18 groups of 200 items, one group of 199, and the separate inline item. Older-page median falls from 1,117.27 to 13.82 ms, exceeding the observed spreads.
The primary combined median also falls, 97.30 → 67.78 ms, but its improvement does not exceed the base's full round range. The concurrency improvement likewise does not clear that strict spread criterion. This establishes an opening improvement, not the historical 2.5× magnitude or a stable concurrency claim.
The historical 6.3 GB database and exact 2.5× magnitude were not reproduced; the primary synthetic HTTP measurement shows 1.48×.
The original zz-bench-34014.ts was not supplied. The event-backed recreation contains 2,800 items and returns 280 older-page items, rather than the triage fixture's 2,400 and 240.
Primary older-page, combined and concurrency improvements did not exceed the largest round spread. The separate deferred-group fixture does establish a stable older-page improvement.
Browser rendering, end-to-end client latency, desktop and mobile behavior were not measured.
The reported 0.03 ms dynamic-tool save overhead, migration backfill, and inline-output families other than htmlRender were not exercised.
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needs-rebaseConflicts with its base branch. Closes after 7 days with no activity.size:M30-99 changed lines (additions + deletions).vouch:unvouchedAuthor is not yet trusted in the VOUCHED list.
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Opening a long thread spent most of its server time scanning tool output JSON with
LIKE, on every read, for every row.Problem
dynamic_toolitem whose output renders inline (HTML render, MCP app, viewed image, delegated task) must stay visible.LIKE '%...%'overpayload_json. It ran inretainedWindowRowsfor every row in the window, and inreadTimelineIndexfor the whole thread when paging older history in deferred mode.Change
orchestration_v2_projection_turn_items.inline_work_output, written in theturn-item.updatedupsert inProjectionStore.ts. That upsert is the only writer to the table.LIKEpatterns with case-insensitive regexes (_becomes.). For delegated tasks it finds the first"toolName":"and tests the rest of the payload once, so payloads with many nested tool names can't stall a save.081_TurnItemInlineWorkOutputadds the column and backfills it with the sameLIKEpredicate the read used before, so existing threads keep the same grouping.Trade-offs
ProjectionStoreand the frozen backfill in the migration. Both have a comment pointing at each other.ProjectionStorestill usesLIKE. It runs on one item, not a window, so I left it.Scope and approval
No prior issue or discussion. I think this fits the small, focused fix exception:
LIKE '%...%'scan over tool payload JSON to compute a value that only changes when the item is saved. On a long thread that scan took more than half the read time.ProjectionStore'sturn-item.updatedupsert), plus a migration to backfill existing rows.dynamic_toolrow of a real 12k-row database. No contract, client, provider, setting or default changes.If maintainers would rather track this in an issue first, I'm happy to open one.
Verification
1fed70cd19, Node 26. No WebSocket or UI time is included, so the time users see goes down less than this.projectionStore.apply.Opus 5.5 via Claude Code in T3 Code.
🤖 Generated with Claude Code