[t3dotgg]

When an agent starts threads with t3_thread_launch or create_threads, the thread that started them showed nothing in its Lineage panel. Six launched threads were running, but the launcher looked like no agents were active.

The launched threads were fine. They just had no link back to the thread that started them.

Now a launch records the caller as lineage.launchedByThreadId. Lineage lists those threads like subagents: running ones are expanded and counted in the header, and finished ones go under "Previous agents". The launched thread shows its launcher as "Parent thread". The field is optional, so older servers and clients still decode. The thread stays top-level: no parent, no merge-back, still in the sidebar. MCP t3_thread_list and t3_thread_read return the field too.

Threads launched before this change are not backfilled.

Before	After

Mobile has no Lineage view, so it is not affected.

Reviewed with sol-loop: 2 rounds with gpt-6.1-sol on xhigh.

Created with Claude Opus 5.5 in Claude Code.

🤖 Generated with Claude Code

[macroscopeapp]

Approvability

Verdict: Approved at 696eedd

Macroscope's review found this PR approvable — This is a focused, backward-compatible fix that records which agent launched a top-level thread and displays that relationship in Lineage. It adds targeted coverage without changing thread execution, defaults, deployment behavior, or security-sensitive code.

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📚 Code guidelines (1)

docs/internals/effect-services.md — configured

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ℹ️ Recent review info

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📥 Commits

Reviewing files that changed from the base of the PR and between 736130c and 696eedd.

📒 Files selected for processing (18)

• apps/server/src/mcp/OrchestratorMcpService.ts
• apps/server/src/mcp/OrchestratorMcpToolkit.integration.test.ts
• apps/server/src/mcp/toolkits/project/handlers.test.ts
• apps/server/src/mcp/toolkits/project/handlers.ts
• apps/server/src/orchestration-v2/Orchestrator.ts
• apps/server/src/orchestration-v2/ThreadLaunchService.test.ts
• apps/server/src/orchestration-v2/ThreadLaunchService.ts
• apps/server/src/orchestration-v2/ThreadManagementService.test.ts
• apps/server/src/orchestration-v2/ThreadManagementService.ts
• apps/web/src/components/chat/ThreadRelationshipsControl.agents.test.tsx
• apps/web/src/components/chat/ThreadRelationshipsControl.tsx
• docs/orchestration-v2/core-graph-and-data-model.md
• docs/orchestration-v2/orchestrator-mcp-server.md
• docs/orchestration-v2/thread-lineage-and-context-transfer.md
• packages/client-runtime/src/state/threadRelationships.test.ts
• packages/client-runtime/src/state/threadRelationships.ts
• packages/contracts/src/orchestrationV2.ts
• packages/contracts/src/orchestratorMcp.ts

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📝 Walkthrough

Walkthrough

Thread creation paths now record the launching thread in lineage. Runtime relationship data derives launch edges, and the chat relationship control displays launched threads according to status.

Changes

Launcher lineage

Layer / File(s)	Summary
Record and expose launcher lineage packages/contracts/src/orchestrationV2.ts, apps/server/src/orchestration-v2/ThreadLaunchService.ts, apps/server/src/mcp/toolkits/project/handlers.ts, apps/server/src/mcp/OrchestratorMcpService.ts, apps/server/src/orchestration-v2/Orchestrator.ts, apps/server/src/orchestration-v2/ThreadManagementService.ts, packages/contracts/src/orchestratorMcp.ts, apps/server/src/orchestration-v2/*test.ts, apps/server/src/mcp/*test.ts, apps/server/src/mcp/toolkits/project/handlers.test.ts, docs/orchestration-v2/*	The lineage and thread.create contracts accept an optional launchedByThreadId. Launch paths pass the caller’s thread ID, and the orchestrator stores it without setting parent lineage. Creation provenance removes client-supplied launcher IDs. MCP thread list items and details expose the ID or null. Tests and documentation cover these changes.
Derive and display launch relationships packages/client-runtime/src/state/threadRelationships.ts, packages/client-runtime/src/state/threadRelationships.test.ts, apps/web/src/components/chat/ThreadRelationshipsControl.tsx, apps/web/src/components/chat/ThreadRelationshipsControl.agents.test.tsx	The relationship graph derives launch edges and uses activity-run status, or thread status when absent. The chat control groups started-agent relationships by status, counts running launch edges, and displays launched-thread rows with agent icons and provider drivers.

Priority: ➖ Normal

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

Change: Bug fix

Sequence Diagram(s)

sequenceDiagram
  participant Caller as Calling agent thread
  participant ProjectHandler as Project handler
  participant ThreadLaunchService
  participant Orchestrator
  participant RelationshipGraph as Thread relationship graph
  participant ChatControl as Thread relationships control
  Caller->>ProjectHandler: Call t3_thread_launch
  ProjectHandler->>ThreadLaunchService: Pass launchedByThreadId
  ThreadLaunchService->>Orchestrator: Dispatch thread.create
  Orchestrator->>Orchestrator: Store launcher ID in lineage
  RelationshipGraph->>RelationshipGraph: Derive launch edge and status
  ChatControl->>RelationshipGraph: Read thread relationships
  ChatControl->>ChatControl: Group and display launched thread

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Suggested reviewers: juliusmarminge

Merge Risk: ⚪ Minimal · up to 696ee

The launcher lineage change is mergeable after normal checks; no concrete issue remains that requires a fix before merge.

🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Description check	⚠️ Warning	The description explains the problem and change, and includes before-and-after screenshots. It omits the required scope and approval information and does not report focused tests or their results.	Add the linked issue or maintainer approval and explain why the change qualifies for any scope exemption. Describe the focused tests or manual checks performed and their observed results. State anything that could not be checked; if tests w…
Docstring Coverage	⚠️ Warning	Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 15 files. (3 skipped: …	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main change: showing threads an agent launched in the Lineage view.
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

Resolution

Add the linked issue or maintainer approval and explain why the change qualifies for any scope exemption. Describe the focused tests or manual checks performed and their observed results. State anything that could not be checked; if tests were not run, say so.

Full details: Docstring Coverage

Explanation

Docstring coverage is 25.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 15 files. (3 skipped: 3 unsupported.)

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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	4.9 KiB	4.9 KiB	0 B (0.0%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.7 KiB	3.7 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	20.4 KiB	20.4 KiB	0 B (0.0%)	29.3 KiB	✅
Codex	Live turn messages	2	2	0 (0.0%)	8	✅
Claude	Total thread wire	4.9 KiB	4.9 KiB	0 B (0.0%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.7 KiB	3.7 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	20.8 KiB	20.8 KiB	0 B (0.0%)	29.3 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: 736130c · PR result: 696eedd · 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: 106.1 KiB
• Claude decoded thread snapshot: 106.4 KiB

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

[juliusmarminge]

i dont agree with this. this was a deliberate decision to not show.

spawning new threads and delegating task should be differnet. i expect threads in the sidebar and subagents in the lineage panel... agents spawns top level threads as a more detached option to delegated tasks, and thus they should not be in the lineage panel.

that's my 2 cents