feat(web): surface orchestration agents in the timeline

[shivamhwp]

Orchestrator V2 already projects native subagents, and the existing Agents panel already owns their live detail. The remaining problem is presentation: chat repeats one lifecycle row per agent, duplicating the roster and stretching the turn.

This PR keeps the existing orchestration semantics and:

• collapses only local subagents from the same run into one compact timeline action;
• derives the visible count and aggregate state from existing projected item statuses;
• keeps partial failures visible and destructive while sibling agents are still working;
• opens the existing Agents panel for names, status, duration, output, and hierarchy;
• preserves inherited fork projections as lifecycle rows so they keep their source-thread context;
• keeps superseded and replacement attempts in separate summary rosters;
• isolates changing agent summaries from unrelated virtualized timeline rows.

There are no server, contract, persistence, provider-adapter, recovery, client-runtime, or mobile behavior changes.

Screenshots

Before	After

Agents panel	Mobile width

Verification

• 163 focused timeline, session, runtime, and panel tests pass across five files.
• Web typecheck passes.
• The changed timeline files pass formatting, lint, and whitespace checks.
• Render coverage confirms local agents collapse to one summary row while inherited rows and separate attempts remain independent.
• The summary exposes working, failed, stopped, and completed states and opens the existing Agents panel.

Built and tested with GPT-5.6-Sol in the Codex harness through T3 Code.

---

Note

Low Risk
Web-only chat timeline presentation; behavior changes only when onOpenAgents is wired, with no auth, API, or persistence impact.

Overview
Local subagent events in chat are collapsed into one summary row per run (or per attempt when steered), instead of repeating a lifecycle card per agent.

deriveMessagesTimelineRows gains optional summarizeSubagents and a new agent-spawn row type with aggregated counts (working, failed, stopped). Inherited subagents and runs without a summarization callback still render as ordinary event rows; superseded vs active attempts stay in separate groups.

MessagesTimeline takes onOpenAgents and enables summarization only when that callback is present. The new AgentSpawnCtaRow shows status text (including visible failures while others are still running) and opens the existing Agents panel. ChatView passes addAgentsSurface for that hook.

Tests cover grouping, attempt boundaries, opt-out when summarization is off, and the updated markup expectations.

^{Reviewed by Cursor Bugbot for commit 28a337d. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add orchestration agent summary rows to MessagesTimeline

• Introduces a new agent-spawn row variant in deriveMessagesTimelineRows that collapses local subagent events into a single aggregated summary per attempt, run, or item when summarizeSubagents is enabled.
• Adds the AgentSpawnCtaRow component, which renders a clickable CTA with dynamic status text (live vs completed, failed/stopped counts) and opens the Agents panel via onOpenAgents.
• MessagesTimeline accepts an optional onOpenAgents prop; when present it enables subagent summarization and threads the callback through TimelineRowCtx.
• ChatViewContent wires onOpenAgents={addAgentsSurface} to the timeline so users can open the Agents panel from the summary row.
• isRowUnchanged extended to shallow-compare agent-spawn rows, preventing unnecessary re-renders in virtualization.
• Risk: when onOpenAgents is provided, local subagent event rows are no longer rendered individually — callers relying on per-event row rendering (e.g. in MessagesTimeline.logic.ts) should verify the collapsed summary covers their use case.

^{Macroscope summarized 28a337d.}

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[shivamhwp]

Orchestrator V2 already projects native subagents, and the existing Agents panel already owns their live detail. The remaining problem is presentation: chat repeats one lifecycle row per agent, duplicating the roster and stretching the turn.

This PR keeps the existing orchestration semantics and:

• collapses only local subagents from the same run into one compact timeline action;
• derives the visible count and aggregate state from existing projected item statuses;
• keeps partial failures visible and destructive while sibling agents are still working;
• opens the existing Agents panel for names, status, duration, output, and hierarchy;
• preserves inherited fork projections as lifecycle rows so they keep their source-thread context;
• keeps superseded and replacement attempts in separate summary rosters;
• isolates changing agent summaries from unrelated virtualized timeline rows.

There are no server, contract, persistence, provider-adapter, recovery, client-runtime, or mobile behavior changes.

Screenshots

Before	After

Agents panel	Mobile width

Verification

• 163 focused timeline, session, runtime, and panel tests pass across five files.
• Web typecheck passes.
• The changed timeline files pass formatting, lint, and whitespace checks.
• Render coverage confirms local agents collapse to one summary row while inherited rows and separate attempts remain independent.
• The summary exposes working, failed, stopped, and completed states and opens the existing Agents panel.

Built and tested with GPT-5.6-Sol in the Codex harness through T3 Code.

---

Note

Low Risk
Web-only chat timeline presentation; behavior changes only when onOpenAgents is wired, with no auth, API, or persistence impact.

Overview
Local subagent events in chat are collapsed into one summary row per run (or per attempt when steered), instead of repeating a lifecycle card per agent.

deriveMessagesTimelineRows gains optional summarizeSubagents and a new agent-spawn row type with aggregated counts (working, failed, stopped). Inherited subagents and runs without a summarization callback still render as ordinary event rows; superseded vs active attempts stay in separate groups.

MessagesTimeline takes onOpenAgents and enables summarization only when that callback is present. The new AgentSpawnCtaRow shows status text (including visible failures while others are still running) and opens the existing Agents panel. ChatView passes addAgentsSurface for that hook.

Tests cover grouping, attempt boundaries, opt-out when summarization is off, and the updated markup expectations.

^{Reviewed by Cursor Bugbot for commit 28a337d. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add orchestration agent summary rows to MessagesTimeline

• Introduces a new agent-spawn row variant in deriveMessagesTimelineRows that collapses local subagent events into a single aggregated summary per attempt, run, or item when summarizeSubagents is enabled.
• Adds the AgentSpawnCtaRow component, which renders a clickable CTA with dynamic status text (live vs completed, failed/stopped counts) and opens the Agents panel via onOpenAgents.
• MessagesTimeline accepts an optional onOpenAgents prop; when present it enables subagent summarization and threads the callback through TimelineRowCtx.
• ChatViewContent wires onOpenAgents={addAgentsSurface} to the timeline so users can open the Agents panel from the summary row.
• isRowUnchanged extended to shallow-compare agent-spawn rows, preventing unnecessary re-renders in virtualization.
• Risk: when onOpenAgents is provided, local subagent event rows are no longer rendered individually — callers relying on per-event row rendering (e.g. in MessagesTimeline.logic.ts) should verify the collapsed summary covers their use case.

^{Macroscope summarized 28a337d.}

[coderabbitai]

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[shivamhwp]

Orchestrator V2 already projects native subagents, and the existing Agents panel already owns their live detail. The remaining problem is presentation: chat repeats one lifecycle row per agent, duplicating the roster and stretching the turn.

This PR keeps the existing orchestration semantics and:

• collapses only local subagents from the same run into one compact timeline action;
• derives the visible count and aggregate state from existing projected item statuses;
• keeps partial failures visible and destructive while sibling agents are still working;
• opens the existing Agents panel for names, status, duration, output, and hierarchy;
• preserves inherited fork projections as lifecycle rows so they keep their source-thread context;
• keeps superseded and replacement attempts in separate summary rosters;
• isolates changing agent summaries from unrelated virtualized timeline rows.

There are no server, contract, persistence, provider-adapter, recovery, client-runtime, or mobile behavior changes.

Screenshots

Before	After

Agents panel	Mobile width

Verification

• 163 focused timeline, session, runtime, and panel tests pass across five files.
• Web typecheck passes.
• The changed timeline files pass formatting, lint, and whitespace checks.
• Render coverage confirms local agents collapse to one summary row while inherited rows and separate attempts remain independent.
• The summary exposes working, failed, stopped, and completed states and opens the existing Agents panel.

Built and tested with GPT-5.6-Sol in the Codex harness through T3 Code.

---

Note

Low Risk
Web-only chat timeline presentation; behavior changes only when onOpenAgents is wired, with no auth, API, or persistence impact.

Overview
Local subagent events in chat are collapsed into one summary row per run (or per attempt when steered), instead of repeating a lifecycle card per agent.

deriveMessagesTimelineRows gains optional summarizeSubagents and a new agent-spawn row type with aggregated counts (working, failed, stopped). Inherited subagents and runs without a summarization callback still render as ordinary event rows; superseded vs active attempts stay in separate groups.

MessagesTimeline takes onOpenAgents and enables summarization only when that callback is present. The new AgentSpawnCtaRow shows status text (including visible failures while others are still running) and opens the existing Agents panel. ChatView passes addAgentsSurface for that hook.

Tests cover grouping, attempt boundaries, opt-out when summarization is off, and the updated markup expectations.

^{Reviewed by Cursor Bugbot for commit 28a337d. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add orchestration agent summary rows to MessagesTimeline

• Introduces a new agent-spawn row variant in deriveMessagesTimelineRows that collapses local subagent events into a single aggregated summary per attempt, run, or item when summarizeSubagents is enabled.
• Adds the AgentSpawnCtaRow component, which renders a clickable CTA with dynamic status text (live vs completed, failed/stopped counts) and opens the Agents panel via onOpenAgents.
• MessagesTimeline accepts an optional onOpenAgents prop; when present it enables subagent summarization and threads the callback through TimelineRowCtx.
• ChatViewContent wires onOpenAgents={addAgentsSurface} to the timeline so users can open the Agents panel from the summary row.
• isRowUnchanged extended to shallow-compare agent-spawn rows, preventing unnecessary re-renders in virtualization.
• Risk: when onOpenAgents is provided, local subagent event rows are no longer rendered individually — callers relying on per-event row rendering (e.g. in MessagesTimeline.logic.ts) should verify the collapsed summary covers their use case.

^{Macroscope summarized 28a337d.}

[coderabbitai]

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[shivamhwp]

Orchestrator V2 already projects native subagents, and the existing Agents panel already owns their live detail. The remaining problem is presentation: chat repeats one lifecycle row per agent, duplicating the roster and stretching the turn.

This PR keeps the existing orchestration semantics and:

• collapses only local subagents from the same run into one compact timeline action;
• derives the visible count and aggregate state from existing projected item statuses;
• keeps partial failures visible and destructive while sibling agents are still working;
• opens the existing Agents panel for names, status, duration, output, and hierarchy;
• preserves inherited fork projections as lifecycle rows so they keep their source-thread context;
• keeps superseded and replacement attempts in separate summary rosters;
• isolates changing agent summaries from unrelated virtualized timeline rows.

There are no server, contract, persistence, provider-adapter, recovery, client-runtime, or mobile behavior changes.

Screenshots

Before	After

Agents panel	Mobile width

Verification

• 163 focused timeline, session, runtime, and panel tests pass across five files.
• Web typecheck passes.
• The changed timeline files pass formatting, lint, and whitespace checks.
• Render coverage confirms local agents collapse to one summary row while inherited rows and separate attempts remain independent.
• The summary exposes working, failed, stopped, and completed states and opens the existing Agents panel.

Built and tested with GPT-5.6-Sol in the Codex harness through T3 Code.

---

Note

Low Risk
Web-only chat timeline presentation; behavior changes only when onOpenAgents is wired, with no auth, API, or persistence impact.

Overview
Local subagent events in chat are collapsed into one summary row per run (or per attempt when steered), instead of repeating a lifecycle card per agent.

deriveMessagesTimelineRows gains optional summarizeSubagents and a new agent-spawn row type with aggregated counts (working, failed, stopped). Inherited subagents and runs without a summarization callback still render as ordinary event rows; superseded vs active attempts stay in separate groups.

MessagesTimeline takes onOpenAgents and enables summarization only when that callback is present. The new AgentSpawnCtaRow shows status text (including visible failures while others are still running) and opens the existing Agents panel. ChatView passes addAgentsSurface for that hook.

Tests cover grouping, attempt boundaries, opt-out when summarization is off, and the updated markup expectations.

^{Reviewed by Cursor Bugbot for commit 28a337d. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add orchestration agent summary rows to MessagesTimeline

• Introduces a new agent-spawn row variant in deriveMessagesTimelineRows that collapses local subagent events into a single aggregated summary per attempt, run, or item when summarizeSubagents is enabled.
• Adds the AgentSpawnCtaRow component, which renders a clickable CTA with dynamic status text (live vs completed, failed/stopped counts) and opens the Agents panel via onOpenAgents.
• MessagesTimeline accepts an optional onOpenAgents prop; when present it enables subagent summarization and threads the callback through TimelineRowCtx.
• ChatViewContent wires onOpenAgents={addAgentsSurface} to the timeline so users can open the Agents panel from the summary row.
• isRowUnchanged extended to shallow-compare agent-spawn rows, preventing unnecessary re-renders in virtualization.
• Risk: when onOpenAgents is provided, local subagent event rows are no longer rendered individually — callers relying on per-event row rendering (e.g. in MessagesTimeline.logic.ts) should verify the collapsed summary covers their use case.

^{Macroscope summarized 28a337d.}

[coderabbitai]

Important

Review skipped

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✨ Finishing Touches

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• Commit unit tests in branch subagent-obs/05-thread-visibility

Warning

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---

_{Comment @coderabbitai help to get the list of available commands.}

[shivamhwp]

Orchestrator V2 already projects native subagents, and the existing Agents panel already owns their live detail. The remaining problem is presentation: chat repeats one lifecycle row per agent, duplicating the roster and stretching the turn.

This PR keeps the existing orchestration semantics and:

• collapses only local subagents from the same run into one compact timeline action;
• derives the visible count and aggregate state from existing projected item statuses;
• keeps partial failures visible and destructive while sibling agents are still working;
• opens the existing Agents panel for names, status, duration, output, and hierarchy;
• preserves inherited fork projections as lifecycle rows so they keep their source-thread context;
• keeps superseded and replacement attempts in separate summary rosters;
• isolates changing agent summaries from unrelated virtualized timeline rows.

There are no server, contract, persistence, provider-adapter, recovery, client-runtime, or mobile behavior changes.

Screenshots

Before	After

Agents panel	Mobile width

Verification

• 163 focused timeline, session, runtime, and panel tests pass across five files.
• Web typecheck passes.
• The changed timeline files pass formatting, lint, and whitespace checks.
• Render coverage confirms local agents collapse to one summary row while inherited rows and separate attempts remain independent.
• The summary exposes working, failed, stopped, and completed states and opens the existing Agents panel.

Built and tested with GPT-5.6-Sol in the Codex harness through T3 Code.

---

Note

Low Risk
Web-only chat timeline presentation; behavior changes only when onOpenAgents is wired, with no auth, API, or persistence impact.

Overview
Local subagent events in chat are collapsed into one summary row per run (or per attempt when steered), instead of repeating a lifecycle card per agent.

deriveMessagesTimelineRows gains optional summarizeSubagents and a new agent-spawn row type with aggregated counts (working, failed, stopped). Inherited subagents and runs without a summarization callback still render as ordinary event rows; superseded vs active attempts stay in separate groups.

MessagesTimeline takes onOpenAgents and enables summarization only when that callback is present. The new AgentSpawnCtaRow shows status text (including visible failures while others are still running) and opens the existing Agents panel. ChatView passes addAgentsSurface for that hook.

Tests cover grouping, attempt boundaries, opt-out when summarization is off, and the updated markup expectations.

^{Reviewed by Cursor Bugbot for commit 28a337d. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add orchestration agent summary rows to MessagesTimeline

• Introduces a new agent-spawn row variant in deriveMessagesTimelineRows that collapses local subagent events into a single aggregated summary per attempt, run, or item when summarizeSubagents is enabled.
• Adds the AgentSpawnCtaRow component, which renders a clickable CTA with dynamic status text (live vs completed, failed/stopped counts) and opens the Agents panel via onOpenAgents.
• MessagesTimeline accepts an optional onOpenAgents prop; when present it enables subagent summarization and threads the callback through TimelineRowCtx.
• ChatViewContent wires onOpenAgents={addAgentsSurface} to the timeline so users can open the Agents panel from the summary row.
• isRowUnchanged extended to shallow-compare agent-spawn rows, preventing unnecessary re-renders in virtualization.
• Risk: when onOpenAgents is provided, local subagent event rows are no longer rendered individually — callers relying on per-event row rendering (e.g. in MessagesTimeline.logic.ts) should verify the collapsed summary covers their use case.

^{Macroscope summarized 28a337d.}

[coderabbitai]

Important

Review skipped

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⚙️ Run configuration

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Run ID: 606ccf48-8344-45dd-ab00-72d4e58d33f9

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch subagent-obs/05-thread-visibility

Warning

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---

_{Comment @coderabbitai help to get the list of available commands.}

[shivamhwp]

Orchestrator V2 already projects native subagents, and the existing Agents panel already owns their live detail. The remaining problem is presentation: chat repeats one lifecycle row per agent, duplicating the roster and stretching the turn.

This PR keeps the existing orchestration semantics and:

• collapses only local subagents from the same run into one compact timeline action;
• derives the visible count and aggregate state from existing projected item statuses;
• keeps partial failures visible and destructive while sibling agents are still working;
• opens the existing Agents panel for names, status, duration, output, and hierarchy;
• preserves inherited fork projections as lifecycle rows so they keep their source-thread context;
• keeps superseded and replacement attempts in separate summary rosters;
• isolates changing agent summaries from unrelated virtualized timeline rows.

There are no server, contract, persistence, provider-adapter, recovery, client-runtime, or mobile behavior changes.

Screenshots

Before	After

Agents panel	Mobile width

Verification

• 163 focused timeline, session, runtime, and panel tests pass across five files.
• Web typecheck passes.
• The changed timeline files pass formatting, lint, and whitespace checks.
• Render coverage confirms local agents collapse to one summary row while inherited rows and separate attempts remain independent.
• The summary exposes working, failed, stopped, and completed states and opens the existing Agents panel.

Built and tested with GPT-5.6-Sol in the Codex harness through T3 Code.

---

Note

Low Risk
Web-only chat timeline presentation; behavior changes only when onOpenAgents is wired, with no auth, API, or persistence impact.

Overview
Local subagent events in chat are collapsed into one summary row per run (or per attempt when steered), instead of repeating a lifecycle card per agent.

deriveMessagesTimelineRows gains optional summarizeSubagents and a new agent-spawn row type with aggregated counts (working, failed, stopped). Inherited subagents and runs without a summarization callback still render as ordinary event rows; superseded vs active attempts stay in separate groups.

MessagesTimeline takes onOpenAgents and enables summarization only when that callback is present. The new AgentSpawnCtaRow shows status text (including visible failures while others are still running) and opens the existing Agents panel. ChatView passes addAgentsSurface for that hook.

Tests cover grouping, attempt boundaries, opt-out when summarization is off, and the updated markup expectations.

^{Reviewed by Cursor Bugbot for commit 28a337d. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add orchestration agent summary rows to MessagesTimeline

• Introduces a new agent-spawn row variant in deriveMessagesTimelineRows that collapses local subagent events into a single aggregated summary per attempt, run, or item when summarizeSubagents is enabled.
• Adds the AgentSpawnCtaRow component, which renders a clickable CTA with dynamic status text (live vs completed, failed/stopped counts) and opens the Agents panel via onOpenAgents.
• MessagesTimeline accepts an optional onOpenAgents prop; when present it enables subagent summarization and threads the callback through TimelineRowCtx.
• ChatViewContent wires onOpenAgents={addAgentsSurface} to the timeline so users can open the Agents panel from the summary row.
• isRowUnchanged extended to shallow-compare agent-spawn rows, preventing unnecessary re-renders in virtualization.
• Risk: when onOpenAgents is provided, local subagent event rows are no longer rendered individually — callers relying on per-event row rendering (e.g. in MessagesTimeline.logic.ts) should verify the collapsed summary covers their use case.

^{Macroscope summarized 28a337d.}

[coderabbitai]

Important

Review skipped

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⚙️ Run configuration

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Run ID: 606ccf48-8344-45dd-ab00-72d4e58d33f9

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Use the checkbox below for a quick retry:

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✨ Finishing Touches

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• Create PR with unit tests
• Commit unit tests in branch subagent-obs/05-thread-visibility

Warning

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---

_{Comment @coderabbitai help to get the list of available commands.}

[shivamhwp]

Orchestrator V2 already projects native subagents, and the existing Agents panel already owns their live detail. The remaining problem is presentation: chat repeats one lifecycle row per agent, duplicating the roster and stretching the turn.

This PR keeps the existing orchestration semantics and:

• collapses only local subagents from the same run into one compact timeline action;
• derives the visible count and aggregate state from existing projected item statuses;
• keeps partial failures visible and destructive while sibling agents are still working;
• opens the existing Agents panel for names, status, duration, output, and hierarchy;
• preserves inherited fork projections as lifecycle rows so they keep their source-thread context;
• keeps superseded and replacement attempts in separate summary rosters;
• isolates changing agent summaries from unrelated virtualized timeline rows.

There are no server, contract, persistence, provider-adapter, recovery, client-runtime, or mobile behavior changes.

Screenshots

Before	After

Agents panel	Mobile width

Verification

• 163 focused timeline, session, runtime, and panel tests pass across five files.
• Web typecheck passes.
• The changed timeline files pass formatting, lint, and whitespace checks.
• Render coverage confirms local agents collapse to one summary row while inherited rows and separate attempts remain independent.
• The summary exposes working, failed, stopped, and completed states and opens the existing Agents panel.

Built and tested with GPT-5.6-Sol in the Codex harness through T3 Code.

---

Note

Low Risk
Web-only chat timeline presentation; behavior changes only when onOpenAgents is wired, with no auth, API, or persistence impact.

Overview
Local subagent events in chat are collapsed into one summary row per run (or per attempt when steered), instead of repeating a lifecycle card per agent.

deriveMessagesTimelineRows gains optional summarizeSubagents and a new agent-spawn row type with aggregated counts (working, failed, stopped). Inherited subagents and runs without a summarization callback still render as ordinary event rows; superseded vs active attempts stay in separate groups.

MessagesTimeline takes onOpenAgents and enables summarization only when that callback is present. The new AgentSpawnCtaRow shows status text (including visible failures while others are still running) and opens the existing Agents panel. ChatView passes addAgentsSurface for that hook.

Tests cover grouping, attempt boundaries, opt-out when summarization is off, and the updated markup expectations.

^{Reviewed by Cursor Bugbot for commit 28a337d. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add orchestration agent summary rows to MessagesTimeline

• Introduces a new agent-spawn row variant in deriveMessagesTimelineRows that collapses local subagent events into a single aggregated summary per attempt, run, or item when summarizeSubagents is enabled.
• Adds the AgentSpawnCtaRow component, which renders a clickable CTA with dynamic status text (live vs completed, failed/stopped counts) and opens the Agents panel via onOpenAgents.
• MessagesTimeline accepts an optional onOpenAgents prop; when present it enables subagent summarization and threads the callback through TimelineRowCtx.
• ChatViewContent wires onOpenAgents={addAgentsSurface} to the timeline so users can open the Agents panel from the summary row.
• isRowUnchanged extended to shallow-compare agent-spawn rows, preventing unnecessary re-renders in virtualization.
• Risk: when onOpenAgents is provided, local subagent event rows are no longer rendered individually — callers relying on per-event row rendering (e.g. in MessagesTimeline.logic.ts) should verify the collapsed summary covers their use case.

^{Macroscope summarized 28a337d.}

[coderabbitai]

Important

Review skipped

Auto reviews are disabled on this repository. Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Team

Run ID: 606ccf48-8344-45dd-ab00-72d4e58d33f9

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

Use the checkbox below for a quick retry:

• 🔍 Trigger review

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch subagent-obs/05-thread-visibility

Warning

Your free Security trial is over. An organization admin can upgrade to Advanced for continuous pull request security review or dismiss this notice.

---

_{Comment @coderabbitai help to get the list of available commands.}

[shivamhwp]

Orchestrator V2 already projects native subagents, and the existing Agents panel already owns their live detail. The remaining problem is presentation: chat repeats one lifecycle row per agent, duplicating the roster and stretching the turn.

This PR keeps the existing orchestration semantics and:

• collapses only local subagents from the same run into one compact timeline action;
• derives the visible count and aggregate state from existing projected item statuses;
• keeps partial failures visible and destructive while sibling agents are still working;
• opens the existing Agents panel for names, status, duration, output, and hierarchy;
• preserves inherited fork projections as lifecycle rows so they keep their source-thread context;
• keeps superseded and replacement attempts in separate summary rosters;
• isolates changing agent summaries from unrelated virtualized timeline rows.

There are no server, contract, persistence, provider-adapter, recovery, client-runtime, or mobile behavior changes.

Screenshots

Before	After

Agents panel	Mobile width

Verification

• 163 focused timeline, session, runtime, and panel tests pass across five files.
• Web typecheck passes.
• The changed timeline files pass formatting, lint, and whitespace checks.
• Render coverage confirms local agents collapse to one summary row while inherited rows and separate attempts remain independent.
• The summary exposes working, failed, stopped, and completed states and opens the existing Agents panel.

Built and tested with GPT-5.6-Sol in the Codex harness through T3 Code.

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Note

Low Risk
Web-only chat timeline presentation; behavior changes only when onOpenAgents is wired, with no auth, API, or persistence impact.

Overview
Local subagent events in chat are collapsed into one summary row per run (or per attempt when steered), instead of repeating a lifecycle card per agent.

deriveMessagesTimelineRows gains optional summarizeSubagents and a new agent-spawn row type with aggregated counts (working, failed, stopped). Inherited subagents and runs without a summarization callback still render as ordinary event rows; superseded vs active attempts stay in separate groups.

MessagesTimeline takes onOpenAgents and enables summarization only when that callback is present. The new AgentSpawnCtaRow shows status text (including visible failures while others are still running) and opens the existing Agents panel. ChatView passes addAgentsSurface for that hook.

Tests cover grouping, attempt boundaries, opt-out when summarization is off, and the updated markup expectations.

^{Reviewed by Cursor Bugbot for commit 28a337d. Bugbot is set up for automated code reviews on this repo. Configure here.}

Note

Add orchestration agent summary rows to MessagesTimeline

• Introduces a new agent-spawn row variant in deriveMessagesTimelineRows that collapses local subagent events into a single aggregated summary per attempt, run, or item when summarizeSubagents is enabled.
• Adds the AgentSpawnCtaRow component, which renders a clickable CTA with dynamic status text (live vs completed, failed/stopped counts) and opens the Agents panel via onOpenAgents.
• MessagesTimeline accepts an optional onOpenAgents prop; when present it enables subagent summarization and threads the callback through TimelineRowCtx.
• ChatViewContent wires onOpenAgents={addAgentsSurface} to the timeline so users can open the Agents panel from the summary row.
• isRowUnchanged extended to shallow-compare agent-spawn rows, preventing unnecessary re-renders in virtualization.
• Risk: when onOpenAgents is provided, local subagent event rows are no longer rendered individually — callers relying on per-event row rendering (e.g. in MessagesTimeline.logic.ts) should verify the collapsed summary covers their use case.

^{Macroscope summarized 28a337d.}

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