perf(server): sidebar shell loads 3x faster and startup thread counts 80x faster#27106

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: 108.5 KiB
• Claude decoded thread snapshot: 108.8 KiB

External image Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: perf/shell-subset-reads
• File: .coderabbit.config.ts
• Commit: 7adc73b
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Team
• Run ID: c41c6308-b2ff-4ecb-9010-bccc369287e2

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Reviewing files that changed from the base of the PR and between 5c828e3c1677dee041caafeb926e109700080037 and 7adc73b2c75e5e12b571e280d1961698f0280d83.

External image Files selected for processing: 1

• apps/server/integration/transferBudgetV2.integration.test.ts

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The change adds thread-count and active-shell-index APIs. Subscriber snapshot loading uses the index to select shell data before decoding and applies subscriber trim options. Startup, relay, project, and thread-launch paths use the new APIs or scoped snapshots.

Changes: Active Shell Index and Subscriber Snapshots

Layer / File(s)	Summary
Add the active shell index API apps/server/src/orchestration-v2/ProjectionStore.ts, apps/server/src/orchestration-v2/Orchestrator.ts, apps/server/src/orchestration-v2/ThreadManagementService.ts, apps/server/src/orchestration-v2/ProjectionStore.test.ts, apps/server/src/orchestration-v2/ProviderTurnControlService.test.ts	The projection store counts non-deleted threads, including archived threads, and lists active shell entries with a mayBeLive flag. The orchestrator and thread-management service expose both methods. Tests compare index entries with shell snapshots and update the relevant mock.
Select and trim subscriber snapshots apps/server/src/orchestration-v2/ShellStream.ts	The loader uses index entries to select threads before reading shell data when trimming is enabled. Shared trim logic applies idle-subagent and older-settled filters.
Use the loader in HTTP and WebSocket routes apps/server/src/orchestration-v2/http.ts, apps/server/src/ws.ts, apps/server/src/ws.test.ts	Both routes use the shared loader with subscriber options. They enrich projects from the returned snapshot; the WebSocket path also uses the returned subagent IDs.
Update other thread snapshot and index callers apps/server/src/orchestration-v2/ThreadLaunchService.ts, apps/server/src/project/ProjectService.ts, apps/server/src/relay/AgentAwarenessRelay.ts, apps/server/src/relay/AgentAwarenessRelay.test.ts, apps/server/src/serverRuntimeStartup.ts, apps/server/src/serverRuntimeStartup.test.ts, apps/server/src/serverRuntimeStartup.autoPull.test.ts, apps/server/integration/transferBudgetV2.integration.test.ts	Startup telemetry uses the thread count, and auto-bootstrap searches the active-shell index. Other callers use project- or worktree-scoped snapshots, or request active top-level shells for the relay’s initial snapshot.

Priority: External image Normal

Estimated code review effort: 3 (Moderate) | ~25 minutes

Change: Refactor

Sequence Diagram(s)

mermaid

1	sequenceDiagram
2	participant SubscriberRoute
3	participant loadSubscriberShellSnapshot
4	participant listActiveShellIndex
5	participant readThreads
6	SubscriberRoute->>loadSubscriberShellSnapshot: Pass trim options and readers
7	loadSubscriberShellSnapshot->>listActiveShellIndex: Read index when trimming is enabled
8	listActiveShellIndex-->>loadSubscriberShellSnapshot: Return active shell entries
9	loadSubscriberShellSnapshot->>loadSubscriberShellSnapshot: Select thread IDs and compute trim facts
10	loadSubscriberShellSnapshot->>readThreads: Read selected thread IDs
11	readThreads-->>loadSubscriberShellSnapshot: Return shell data
12	loadSubscriberShellSnapshot-->>SubscriberRoute: Return trimmed snapshot and subagent IDs

Possibly related issues

• pingdotgg/t3code#23000 — The PR adds an active-shell index and targeted shell reads, which overlap with the issue’s shell-list read-cost objective. It does not add the proposed indexes.
• pingdotgg/t3code#18618 — The PR narrows shell reads to selected rows, but does not change ThreadPullRequestService.
• pingdotgg/t3code#25621 — The PR changes shell reads in named caller paths, but the diff does not show whether it removes the SQL variable limit.
• pingdotgg/t3code#24895 — The PR reduces shell reads through index-based selection, but does not address the issue’s other recovery and canonical projection statements.
• pingdotgg/t3code#9661 — The PR changes per-subscriber shell reads, which overlaps with the tracker’s S11 item. The tracker’s broader items are not fully addressed.

Suggested reviewers: t3dotgg, maria-rcks

The reviewed test mock change does not introduce a merge-blocking behavior or integration risk.

Check name	Status	Explanation
Title check	Passed	The title clearly and concisely summarizes the primary performance improvements: faster sidebar shell loading and startup thread counting.
Description check	Passed	The description clearly explains the problem, implementation approach, measured performance improvements, snapshot equivalence, and verification coverage. It does not include an explicit Scope and app…
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.

Full details: Description check

Explanation

The description clearly explains the problem, implementation approach, measured performance improvements, snapshot equivalence, and verification coverage. It does not include an explicit Scope and approval section or linked approval evidence, but the core description is mostly complete and relevant.

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