[juliusmarminge]

Claude subagent context snapshots disappear before they reach lineage and timeline tooltips. This layer adds an optional wire field and shared formatting, then displays the latest reported context tokens and tool uses in web tooltips and mobile Agents/transcript rows. Missing snapshots stay hidden; zero and decreases remain visible. Settled task snapshots hide while a child follow-up is active or queued. Lineage also drops the older snapshot when it overlays a newer finished child run.

Rebuilt from Gigioxx’s #15446 against current main. The maintainer takeover covers this focused restoration. Related #15429 remains open: cumulative cost and maximum-window display are outside this change. The next stack layer supplies Claude snapshots; this layer stands alone when providers omit them.

Verification: 60 focused Node tests passed (runtime 19→20, contracts 38 unchanged, web Node 2 unchanged); the new codec/projection case fails on main. All 18 existing browser cases passed; one was extended to cover usage, decreases, live-follow-up hiding and a newer finished child run. Scoped contracts, runtime, web and mobile typechecks plus targeted lint/format passed. One new runtime test, no new browser test cases. Two fresh whole-stack review rounds by Claude Opus 5.5 and GPT-6 Sol completed; the second round found no blockers after fixes for workflow totals mislabeled as context and stale context beside a newer finished child run.

Before/after proof: actual main production sources at 1451e7cb23 versus rebuilt stack at 93c22b64a6 (client layer 90df6f1425). Both use identical synthetic isolated data, a 1280×800 viewport, scroll state and font fallback. The running web app verified both timeline and lineage hover cards. Synthetic data exercises rendering; separate adapter tests exercise provider frames. No fresh Claude CLI/account, real SDK workflow, remote/relay/tunnel, macOS, Windows, iOS, Android or Electron desktop session was verified. Mobile layout was inspected and typechecked, with usage on its own line so model names cannot squeeze it out.

Before — timeline tooltip on main:

After — timeline tooltip with the rebuilt client:

Before — lineage tooltip on main:

After — lineage tooltip with the rebuilt client:

Implemented with GPT-6.1 Sol through the Codex harness; tests by GPT-6 Astra; adversarial reviews by Claude Opus 5.5 and GPT-6 Sol through T3 Code delegation.

[macroscopeapp]

Approvability

Verdict: Approved at 90df6f1

Macroscope's review found this PR approvable — This is a backward-compatible, optional data-field addition with localized formatting and display changes in existing web and mobile subagent surfaces. Existing behavior remains unchanged when snapshots are absent, and the follow-up handling only prevents stale informational data from being shown.

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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	5.0 KiB	5.0 KiB	0 B (0.0%)	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	0 B (0.0%)	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	+7 B (+0.1%)	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	+7 B (+0.6%)	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: 1451e7c · PR result: 90df6f1 · 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

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

[coderabbitai]

📝 Walkthrough

The change adds context-token and tool-use snapshots to the subagent runtime, resolves whether snapshots should be displayed based on child-thread activity, and shows formatted usage in web tooltips and mobile subagent rows.

Changes: Subagent usage display

Layer / File(s)	Summary
Usage contract and runtime propagation packages/contracts/src/orchestrationV2.ts, packages/client-runtime/src/state/subagentRuntime.ts, packages/client-runtime/src/state/subagentRuntime.test.ts	The orchestration contract adds context-token and tool-use snapshots. Runtime projection carries snapshots as context usage, and a round-trip test checks populated, zero-valued, and absent usage.
Usage resolution and web display packages/client-runtime/src/state/subagentDisplay.ts, apps/web/src/components/chat/ThreadRelationshipsControl.tsx, apps/web/src/components/chat/V2LifecycleRow.tsx, apps/web/src/components/chat/SubagentTooltipContent.tsx, apps/web/src/components/chat/ThreadRelationshipsControl.agents.browser.test.tsx	Display helpers format usage and suppress it for terminal subagents when the child thread has activity or is queued. Web tooltips receive resolved usage, and browser tests cover display and suppression conditions.
Mobile usage display apps/mobile/src/features/threads/SubagentRow.tsx, apps/mobile/src/features/threads/thread-subagent-group.tsx	Mobile subagent rows receive live usage and display formatted context usage when available.

Priority: ⬇️ Low

Estimated code review effort: 3 (Moderate) | ~20 minutes

Change: Feature

Sequence Diagram(s)

sequenceDiagram
  participant ThreadRelationshipsControl
  participant resolveSubagentContextUsage
  participant ChildThread
  participant SubagentTooltipContent
  ThreadRelationshipsControl->>resolveSubagentContextUsage: subagent status and usage
  ThreadRelationshipsControl->>resolveSubagentContextUsage: related child thread
  resolveSubagentContextUsage->>ChildThread: read activity and queued status
  resolveSubagentContextUsage-->>ThreadRelationshipsControl: resolved usage or null
  ThreadRelationshipsControl->>SubagentTooltipContent: usage
  SubagentTooltipContent-->>ThreadRelationshipsControl: formatted usage display

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Possibly related PRs

• pingdotgg/t3code#15446: Adds Claude subagent usage snapshots to the contract and runtime, which this PR consumes for web and mobile display.

Suggested reviewers: jakeleventhal, maria-rcks

Merge Risk: 🔵 Low · up to 90df6

Timeline and mobile views can show outdated context usage after a follow-up run. This is a bounded display issue that should be fixed or accepted before merging.

Pre-merge checks: 4

Check name	Status	Explanation
Title check		The title clearly and concisely describes the main change: displaying optional subagent context snapshots for clients.
Description check		The description covers the problem, implementation, maintainer approval, verification results, limitations, before/after screenshots, and tooling used.
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.

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[coderabbitai]

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 @packages/client-runtime/src/state/subagentDisplay.ts:
- Around line 137-142: Update the terminal-status guard in the subagent usage
resolver to compare the child thread’s latestRunRequestedAt with the terminal
task’s completion time; return null when a newer child run was requested, and
otherwise preserve the existing terminal-task usage behavior.

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📥 Commits

Reviewing files that changed from the base of the PR and between 1451e7c and 90df6f1.

📒 Files selected for processing: 10

• apps/mobile/src/features/threads/SubagentRow.tsx
• apps/mobile/src/features/threads/thread-subagent-group.tsx
• apps/web/src/components/chat/SubagentTooltipContent.tsx
• apps/web/src/components/chat/ThreadRelationshipsControl.agents.browser.test.tsx
• apps/web/src/components/chat/ThreadRelationshipsControl.tsx
• apps/web/src/components/chat/V2LifecycleRow.tsx
• packages/client-runtime/src/state/subagentDisplay.ts
• packages/client-runtime/src/state/subagentRuntime.test.ts
• packages/client-runtime/src/state/subagentRuntime.ts
• packages/contracts/src/orchestrationV2.ts

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[juliusmarminge]

Validated current head 90df6f1: CI is green after one rerun for the unchanged script-highlighting browser test; its isolated three-case run also passed. The cancelled native fingerprint job was superseded by a successful run of the same workflow/head. Normal skipped jobs remain skipped. Macroscope approved the current head, and CodeRabbit withdrew the historical-snapshot finding after source-backed clarification; all review threads are resolved. Two independent full-stack review rounds, scoped typechecks/lint, focused Node/browser tests, and actual-main/head tooltip proof are recorded in the description. Ready for maintainer review; unmerged.