[t3dotgg]

Every new session downloads the whole thread list, even when the cache on the device is seconds old. On real data that is 129 KB of JSON (15.9 KB gzip, 40 rows) on every browser reload, phone launch and reconnect, after #24723.

Now a new session resumes from the cached cursor when that is safe, and the server sends only the threads that changed.

How it works

• When a resume is safe. The cache stores a resume key: the server's shellResumeKey (new for each server process), the client build, and the snapshot flags (omitIdleSubagents and omitOlderSettled). A new session resumes only when its key matches and the cache's last full snapshot is under 24 hours old. Otherwise it loads the HTTP snapshot, as before.
  • A new server process covers every change to rows that emits no event: migrations, new code, a recreated, copied or restored database.
  • The client build covers caches written by a build that dropped row fields it did not know.
  • The flags cover caches built with another row selection, such as caches from before #24648 or #24723.
  • The 24-hour limit stops rows that a fresh snapshot would trim (idle subagent children, settled threads) from piling up.
• Cheap replay. One grouped SQL query finds each project and thread touched in the gap without reading any payload. The server then sends each current row once. The gap cap goes from 1,000 events to 100,000, with a new cap of 25 touched rows. A fresh snapshot keeps the 25 newest settled threads, so a resume never sends more rows than a snapshot holds. Rows touched in a gap are often ones a snapshot leaves out (older settled and idle subagent threads). Past either cap the server sends a full snapshot on the socket, as before.
• Thread families (#24648). A resumed cache stays at generation 0 until the replay's synchronized marker, and only then counts as authoritative.
• Safety. Items buffered from a replaced subscription attempt are dropped, since they could roll the shell back. Only a real snapshot or a completed resume credits a session. A resume through the cache that fails before its marker falls back to HTTP.

Measured on real data

Read-only copy of a heavy user's database, run through this branch's own subscribeOrchestrationV2Shell, event store and projection store, with both snapshot flags. Bytes sent until the shell is live again, for the most recent stretch of the event log:

Time away	Before (every new session)	After
none (reload, reconnect)	129 KB / 15.9 KB gzip	25 B
5 min	same	15.0 KB / 3.4 KB (4 rows)
15 min	same	114 KB / 14.2 KB (22 rows)
30 min or more	same	same (socket snapshot, past 25 touched rows)

A resume also sends a project metadata refresh of at most 9.4 KB (1.9 KB gzip). Server time was 9 to 16 ms for a resume and 79 to 104 ms for a socket snapshot.

That stretch was busy. Over random absences in the last 14 days, the share that still resumes is:

Time away	Rows touched (median / 90th)	Resumes
5 min	0 / 1	100%
1 h	0 / 9	98%
4 h	2 / 28	90%
8 h	9 / 36	80%
24 h	32 / 88	38%

A saved cursor can sit a little behind the head, because a change that only moves the cursor is not saved. Real rates can be slightly lower.

These cases are not improved. Each still costs one full snapshot per client, as today:

• a server restart or upgrade, including a desktop relaunch with its own local server,
• a resume more than 24 hours after the last full snapshot,
• a client build change (store update, OTA update, hosted web deploy),
• a gap that touches more than 25 threads and projects.

Compatibility

• Old servers send no shellResumeKey, so new clients behave as today.
• Old clients ignore the new config and cache fields.
• Old caches have no key: they load HTTP once, then become resumable. No migration.

Prior art

• #21627 and #14098 resume a completed in-memory shell after a reconnect. This PR replaces that part of both with one rule for memory and disk, and keeps the stream item tagging idea from #21627. The pull request link dedupe in #21627 and the supervisor and relay work in #14098 are separate.
• #21082 moves the completion marker into the first chunk. That is a separate change; here the replay stays in the stream tail. Expect a small rebase in subscribeOrchestrationV2Shell.

Proof

• Focused tests:
  • A restarted client resumes with no HTTP load and no cache write.
  • Each of these loads HTTP instead: another server, another build, other flags, no completion marker, an old cache, a basis 24 hours old, a basis from the future.
  • The generation stays 0 until the marker.
  • An error before the marker falls back to HTTP. Errors after a completed resume keep resuming.
  • A reconnect in the same process keeps the generation.
  • Attempt tags survive a buffered resubscribe.
  • Server: grouped replay heads, both caps, and the guard for a cursor past the head.
• The resume key includes omitOlderSettled: a cache built with other flags loads HTTP. A completed resume reads the cached older settled counts once more.
• Negative controls: removing the marker bump, using <= for the age, restoring the old error rule, leaving omitOlderSettled out of the key, or restoring the 500-row cap each fails a test.
• After the rebase onto #24723 and #24266: perf(client): skip unchanged shell and config cache writes #24266 skips the cache write when only the cursor moved. That skip now also needs the same resume key, so a new key is always saved.
• vp run check:changed passes.
• No UI change. Running app on the rebased head (dev server seeded from a copy of real data, headless web): three page loads in one browser made 1 HTTP shell request and 3 socket subscriptions, and the server ran no full socket snapshot, so the last two loads resumed. The sidebar read Settled (208) on all three loads, and a parent with idle subagents still listed all 6 in Lineage after the resume.
• Not checked in a running app: a server restart (covered by the key tests), a network drop, and a phone launch (no working device here).

Council review

Rounds: 6 (design 1 to 3, code 1 and 2, then the rebase onto #24723).

Delegate	Design 1	Design 2	Design 3	Code 1	Code 2	Rebase 1
Claude Opus 5.5	7/10	8/10	9/10	9/10	9/10	9/10
Muse Wonder Full	7/10	9/10	9/10	9/10	9/10	9/10
Codex GPT-6.1 Sol	7/10	8/10	9/10	9/10	10/10	9/10

Created with Claude Opus 5.5 in Claude Code, running in T3 Code.

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Needs Human Approval

Macroscope's review found this PR requires human approval — This PR introduces a cross-cutting default change that lets new sessions resume persisted shell state through new client, cache, RPC, and server replay logic. It also adds a line-level static-analysis suppression, so the change warrants human review.

Notes:

• No code objects were reviewed. Approvability was decided on eligibility alone.

^{You can add or adjust custom eligibility rules. Learn more.}

[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	5.0 KiB	5.0 KiB	+7 B (+0.1%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.2 KiB	1.2 KiB	+7 B (+0.6%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.9 KiB	20.9 KiB	0 B (0.0%)	29.3 KiB	✅
Codex	Live turn messages	2	2	0 (0.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.0 KiB	0 B (0.0%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.2 KiB	0 B (0.0%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.2 KiB	21.2 KiB	0 B (0.0%)	29.3 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: e57c093 · PR result: 87ddf5b · 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: 108.5 KiB
• Claude decoded thread snapshot: 108.8 KiB

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Recent review info

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• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: t3/resume-shell-from-persisted-cache
• File: .coderabbit.config.ts
• Commit: 87ddf5b
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• Review profile: CHILL
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Commits

Reviewing files that changed from the base of the PR and between 124f10b and 87ddf5b.

Files selected for processing: 2

• packages/client-runtime/src/state/olderSettledThreads.test.ts
• packages/client-runtime/src/state/shell-sync.test.ts

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Walkthrough

The change adds keyed, time-limited shell resumption across client sessions. Clients persist resume metadata and track subscription attempts. The server reads per-aggregate replay heads and sends current shell updates when replay is eligible, or sends a snapshot otherwise.

Changes: Shell resume flow

Layer / File(s)	Summary
Resume contracts and cache packages/contracts/src/server.ts, packages/client-runtime/src/platform/*, packages/client-runtime/src/connection/registry.test.ts, apps/mobile/src/connection/*, apps/web/src/connection/*	Server configuration adds a shell resume key. Client presentation adds build metadata, and the cached-shell shape carries an optional resume basis. Mobile and web adapters load and save that basis with the snapshot.
Subscription attempt identity packages/client-runtime/src/rpc/client.ts, packages/client-runtime/src/rpc/client.test.ts	Subscription values can carry the identity of the attempt that produced them. Existing session-based APIs adapt their callbacks through the attempt.
Aggregate replay heads apps/server/src/persistence/OrchestrationEventStore.ts, apps/server/src/persistence/OrchestrationEventStore.test.ts, apps/server/src/orchestration-v2/ShellStream.ts, apps/server/src/orchestration-v2/ShellStream.test.ts	The event store returns the newest eligible event head per project or V2 thread. Shell stream helpers filter subagent transcript events, convert replay heads to shell events, and provide a process-cached resume key.
WebSocket shell replay apps/server/src/ws.ts, apps/server/src/ws.test.ts	Shell subscriptions use replay heads and touched-aggregate limits. They send current updates and synchronization when replay is eligible, or fall back to a snapshot.
Attempt-aware client synchronization packages/client-runtime/src/state/shell.ts, packages/client-runtime/src/state/shell-sync.test.ts, packages/client-runtime/src/state/olderSettledThreads.test.ts, docs/internals/connection-runtime.md	Shell synchronization checks the resume key, build, selection flags, and cache age. It tracks authoritative synchronization, persists resume metadata, and uses HTTP snapshots when the cached resume is ineligible or fails before synchronization.

Priority: Normal

Estimated code review effort: 4 (Complex) | ~45 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant ClientShell
  participant ws
  participant OrchestrationEventStore
  participant ShellStream
  ClientShell->>ws: Subscribe with cursor and selection
  ws->>OrchestrationEventStore: Read replay heads for sequence range
  OrchestrationEventStore-->>ws: Return aggregate heads
  ws->>ShellStream: Convert replay heads to shell events
  ShellStream-->>ws: Return shell events
  ws-->>ClientShell: Send updates and synchronization

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Possibly related issues

• pingdotgg/t3code#22372: Eligible cached resumes replace full HTTP shell snapshots; the issue’s per-update sorting and filtering work is not changed.
• pingdotgg/t3code#24660: Eligible resumes can avoid full snapshot reads; this change does not add reader concurrency or change transcript caching.

Suggested reviewers: macroscopeapp, maria-rcks, juliusmarminge

Merge Risk: Low · up to 87ddf

Web deployments that share a version may resume an older shell cache and retain stale rows until they are updated. This is a bounded merge risk; use a build identifier that changes with client code.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly and concisely describes the primary change: new sessions resume the cached shell thread list instead of downloading it.
Description check		The description explains the problem, implementation, safety conditions, compatibility behavior, measured impact, focused tests, manual verification, and unchecked scenarios. It does not use the exact…
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 explains the problem, implementation, safety conditions, compatibility behavior, measured impact, focused tests, manual verification, and unchecked scenarios. It does not use the exact template headings or provide an explicit triaged issue or maintainer approval link, but it is otherwise mostly complete and directly related to the change.

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[coderabbitai]

Actionable comments posted: 1

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Inline comments:
Review comments at @apps/web/src/connection/platform.ts:
- Line 329: Update the web adapter’s `build` value derived from `APP_VERSION` to
include a per-deploy identifier, such as the commit hash or build timestamp, so
it changes whenever the client code changes, including over-the-air updates.

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Review info

Run configuration

• Source mode: Auto
• Repository: pingdotgg/t3code
• Branch: t3/resume-shell-from-persisted-cache
• File: .coderabbit.config.ts
• Commit: 61328be
• Layers: Repository TS config
• Review profile: CHILL
• Plan: Team
• Run ID: 04903093-2181-4e9b-88f0-5c8af234b145

Commits

Reviewing files that changed from the base of the PR and between 8045537 and 61328be.

Files selected for processing: 22

• apps/mobile/src/connection/environment-cache-store.test.ts
• apps/mobile/src/connection/environment-cache-store.ts
• apps/mobile/src/connection/platform.ts
• apps/server/src/orchestration-v2/ShellStream.test.ts
• apps/server/src/orchestration-v2/ShellStream.ts
• apps/server/src/persistence/OrchestrationEventStore.test.ts
• apps/server/src/persistence/OrchestrationEventStore.ts
• apps/server/src/ws.test.ts
• apps/server/src/ws.ts
• apps/web/src/connection/platform.ts
• apps/web/src/connection/storage.ts
• docs/internals/connection-runtime.md
• packages/client-runtime/src/connection/registry.test.ts
• packages/client-runtime/src/platform/capabilities.ts
• packages/client-runtime/src/platform/orchestrationCache.ts
• packages/client-runtime/src/platform/persistence.ts
• packages/client-runtime/src/rpc/client.test.ts
• packages/client-runtime/src/rpc/client.ts
• packages/client-runtime/src/state/shell-sync.test.ts
• packages/client-runtime/src/state/shell.ts
• packages/client-runtime/src/state/shellReducer.ts
• packages/contracts/src/server.ts

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