perf(server): stop keeping every Claude SDK message for live sessions

[t3dotgg]

A long-uptime report (T3 Code 0.0.40, 9 days uptime, about 11 live Claude sessions) showed server memory that only a restart freed. One cause: ClaudeAdapter kept every parent assistant message and every tool-result user message (subagent tool results too) in memory. It copied them into context.turns at the end of each turn, and they stayed there until the session stopped. The session reaper skips sessions with an active turn or background work, so a busy session can hold them for days.

Nothing reads these messages. readThread has no production caller. ProviderService discards the snapshot that rollbackThread returns. Rollback reads the native Claude history and turnStartMessageIds.

Fix

This follows #9684, which made the same fix for OpenCode.

• Remove items from ClaudeTurnState and the two sites that pushed SDK messages into it.
• context.turns now keeps only turn ids. A comment says the native Claude session file is the transcript.
• snapshotThread maps each turn to { id, items: [] }, so readThread and rollbackThread still report the correct turn count.

The change is in apps/server/src/provider/Layers/ClaudeAdapter.ts only. We did not measure the memory saved. It depends on how much tool output a live session produces.

Verification

• vp test run apps/server/src/provider/Layers/ClaudeAdapter.test.ts (140 passed). The existing readThread and rollback tests check the turn count. Removing the turn id push makes 5 rollback tests fail.
• vp lint and vp fmt --check on ClaudeAdapter.ts
• vp run --filter t3 typecheck

Related: #9661 tracks performance audit fixes.

Made by Claude Opus 5.5 (1M context) in Claude Code, running in T3 Code.

🤖 Generated with Claude Code

Summary by CodeRabbit

• Bug Fixes
  • Thread snapshots now show completed turns with empty item lists instead of accumulated messages.

[macroscopeapp]

Approvability

Verdict: Approved at 0929738

Macroscope's review found this PR approvable — This is a narrowly scoped server memory-retention fix that stops storing full Claude SDK messages while preserving turn counts, IDs, event handling, and native-history rollback. The snapshot shape remains compatible, with only unused in-memory message contents replaced by empty arrays.

No code changes detected at 37bae9d. Prior analysis still applies.

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[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	13.5 KiB	13.5 KiB	−37 B (−0.3%)	15.1 KiB	✅
Codex	Thread snapshot wire	7.1 KiB	7.1 KiB	−11 B (−0.2%)	7.3 KiB	✅
Codex	Live turn WebSocket wire	6.5 KiB	6.4 KiB	−26 B (−0.4%)	7.8 KiB	✅
Codex	Live turn WebSocket decoded	56.3 KiB	56.2 KiB	−44 B (−0.1%)	66.4 KiB	✅
Codex	Live turn messages	10	9	−1 (−10.0%)	21	✅
Claude	Total thread wire	13.5 KiB	13.5 KiB	−8 B (−0.1%)	15.1 KiB	✅
Claude	Thread snapshot wire	7.1 KiB	7.1 KiB	+1 B (+0.0%)	7.3 KiB	✅
Claude	Live turn WebSocket wire	6.4 KiB	6.4 KiB	−9 B (−0.1%)	7.8 KiB	✅
Claude	Live turn WebSocket decoded	57.0 KiB	57.0 KiB	0 B (0.0%)	66.4 KiB	✅
Claude	Live turn messages	9	9	0 (0.0%)	21	✅

Baseline: 2a9832b · PR result: 37bae9d · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 114.0 KiB
• Claude decoded thread snapshot: 114.7 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.

[macroscopeapp]

readThread now returns empty items for completed Claude turns, changing its observable snapshot behavior. Could you add a focused adapter test that completes a turn, calls readThread, and verifies the turn ID remains while its items are empty (and item events still carry the content)?

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[t3dotgg]

Not adding this. Asserting items is empty would only restate the literal items: [] in snapshotThread (ClaudeAdapter.ts:2176). The turn count after completed turns is already checked by readThread at ClaudeAdapter.test.ts:6631 and by the rollback snapshots at :6745, and item content is covered by the existing item event tests. readThread also has no production caller.

[macroscopeapp]

The existing tests don’t cover this observable contract: they verify turn count or events separately, but not that readThread retains the completed turn ID while omitting its items. Since readThread is part of the adapter interface, I still think the focused regression test is warranted.

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• apps/server/src/provider/Layers/ClaudeAdapter.ts

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📝 Walkthrough

Walkthrough

Claude turn state and session history now store turn IDs without accumulated message items. Thread snapshots return an empty items array for each turn.

Changes

Claude turn tracking

Layer / File(s)	Summary
Turn tracking and snapshots apps/server/src/provider/Layers/ClaudeAdapter.ts	Turn state and session history no longer retain collected message items. Turn creation and message handling omit item accumulation. Thread snapshots return an empty items array for each turn.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to 09297

The change reduces live-session message retention without an identified disruption to thread reading or rollback. It is mergeable after normal checks.

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check. Docstring coverage is scoped to functions touched by this diff. Analyzed 0 functions across 1…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Title check	✅ Passed	The title clearly and concisely describes the main change: reducing memory retention of Claude SDK messages in live server sessions.
Description check	✅ Passed	The description explains the memory-growth problem, the implementation, scope, rationale, and verification steps. It does not use the template headings or include the checklist, but it provides the re…

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[juliusmarminge]

Superseded by #13718 (merged as 5660ab5) — same fix: remove unused items tracking from Claude adapter turn state.

[juliusmarminge]

Closing as superseded by #13718.