[bompus]

The server's find call is about 6x faster after the first keystroke on long threads: 600–750 ms per keystroke before, 100–110 ms after, on the three largest threads in a real database (2,000–2,700 searchable messages each).

Problem

Each find scan visits every message and looks its parsed text up in a cache that held 512 entries. A thread with more than 512 distinct messages is walked in order, so each lookup evicts an entry the same scan needs next, and nothing is ever found in the cache. Every keystroke (each is a new query) and every next/previous match press while the thread is streaming re-parses the whole thread.

Change

Raise the parsed-text cache capacity from 512 to 8192 (ThreadFind.ts), with a comment saying why it must exceed the largest thread. Add a regression test: on a 600-message thread, a second query that differs from the first re-parses nothing (600 parses on the second query before the change, 0 after).

Scope and approval

A one-constant fix for a performance defect, with a test that fails without it. No output changes: match counts and positions are identical between the two builds in every measured case. I think it qualifies for the small-focused-fix exception; happy to open a discussion first if you would rather.

Verification

Read-only snapshot of a real 15 GB database, three largest threads, ThreadFind called in process (so these are server times, not measured in the UI). Before = upstream/main, after = this branch. Five interleaved pairs of separate processes (order alternated), host load 3.4–5.3; queries are 3–6 character prefixes of words in each thread, every typing call a new query. Median per call:

Thread (searchable messages)	Scenario	Before	After	Benefit
2,028	typing, after the first keystroke	600 ms	104 ms	5.8x
2,028	next match while the thread streams	596 ms	105 ms	5.7x
2,726	typing, after the first keystroke	751 ms	112 ms	6.7x
2,726	next match while the thread streams	764 ms	107 ms	7.1x
2,359	typing, after the first keystroke	731 ms	103 ms	7.1x
2,359	next match while the thread streams	732 ms	99 ms	7.4x
all three	next match on a quiet thread (cached result)	0.2–0.3 ms	0.2 ms	no clear change

• The first keystroke of a find session is unchanged (about 830 ms before, 820–930 ms after): the cache starts empty. Entries expire one minute after they were parsed, whether or not they were read since, so a session longer than a minute pays one full parse again.
• Heap after typing grew by about 4–9 MB more than before on these threads (0.6–0.8 M characters of text each). The cache is shared across threads and bounded by entry count, so the worst case is larger: entries hold their text and parsed segments, and 8192 entries of large messages could reach hundreds of MB. Expired entries are only dropped when their key is read or newer entries push them out.
• Threads above 8192 messages still cycle the cache. The separate cache for texts over 32,768 characters keeps its capacity of 32.
• Check: vp test run apps/server/src/orchestration-v2/ThreadFind.test.ts (24 tests pass); the new test fails on the old capacity with "expected 600 to equal 0". Not checked: UI-side effect of the shorter server time, other machines or data, Bun.

Claude Sonnet 5.5 in Claude Code, run through T3 Code.

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Summary by cubic

Makes find in long threads about 6x faster after the first keystroke. The parsed-text cache was too small (512 entries) to hold a whole thread, so each scan evicted entries it still needed and re-parsed all 2,000–2,700 messages per keystroke; raising the capacity to 8192 keeps parses cached across queries and cuts median time from 600–750 ms to 100–110 ms. Adds a regression test asserting a second query on a 600-message thread re-parses nothing (600 parses before, 0 after). The change is reconciled with the current upstream state of the find code.

Side effects

• Heap grows roughly 4–9 MB more per large thread while typing; 8192 entries of large messages could reach hundreds of MB.
• Threads above 8192 messages still cycle the cache, and the separate cache for texts over 32,768 characters is unchanged.
• No output changes: match counts and positions are identical in all measured cases.

^{Written for commit 70d353b. Summary will update on new commits.}

[coderabbitai]

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📝 Walkthrough

The small-text parse cache capacity increases from 512 to 8192 entries. A new test checks that a second query reuses parsed messages from the first query in a 600-message thread.

Changes: Thread search cache

Layer / File(s)	Summary
Cache capacity and parse reuse apps/server/src/orchestration-v2/ThreadFind.ts, apps/server/src/orchestration-v2/ThreadFind.test.ts	The small-text cache capacity increases to 8192 entries; its one-minute TTL remains unchanged. A test verifies that the second query finds 111 matches without parsing the 600 messages again.

Priority: ➖ Normal

Estimated code review effort: 2 (Simple) | ~8 minutes

Change: Bug fix

Suggested reviewers: noojuno

Merge Risk: 🔵 Low · up to ea7b7

The larger cache improves reuse on long threads, but exceptionally large searches can retain hundreds of megabytes per cache for up to a minute. Consider a byte-bounded cache before merging.

Architecture risk: 🔵 Low · up to ea7b7

The change affects 1 system.

Changed systems: apps/server

Architecture concerns
No architecture-level concerns identified.

Review details

Systems and components

• observed — apps/server (service) was modified; 2 changed files map to changed impact.

Before / after behavior

• observed — Modified behavior in apps/server/src/orchestration-v2/ThreadFind.test.ts: Adds coverage for parse reuse across different queries in a 600-message thread: the first search finds 600 matches and parses each message; the second finds 111 matches without invoking the parser again.
• observed — Modified behavior in apps/server/src/orchestration-v2/ThreadFind.ts: The small-text cache capacity increases from 512 to 8192 entries; its one-minute TTL and lookup remain unchanged.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly and concisely describes the main performance fix: avoiding repeated parsing when searching long threads.
Description check		The description includes the required Problem, Change, Scope and approval, and Verification sections. It explains the defect, implementation, test coverage, measured results, limitations, memory impac…
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: Description check

Explanation

The description includes the required Problem, Change, Scope and approval, and Verification sections. It explains the defect, implementation, test coverage, measured results, limitations, memory impact, and agent usage.

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Actionable comments posted: 1

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• 🪄 Fix comments: Fix CodeRabbit comments on this PR

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Inline comments:
Review comments at @apps/server/src/orchestration-v2/ThreadFind.ts:
- Around line 266-269: Reduce the textCache capacity in searchThread from 8192
to 512 entries, preserving its existing one-minute time-to-live and lookup
behavior.

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• apps/server/src/orchestration-v2/ThreadFind.test.ts
• apps/server/src/orchestration-v2/ThreadFind.ts

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[bompus]

cubic is skipping this pull request (its account line limit). The owner chose to go ahead without cubic for this pull request, in a reply to the question "What about cubic's review of fork PR #12?": "2A Proceed without cubic". CodeRabbit completed on the final head (ea7b7cf) and its one finding was answered above.