Issue 16808 runtime reproduction, 2026-10-22, Ubuntu Linux x64.
Before source: 8d3b061121 (origin/main), with test-only commit c81f3257cc.
Real app: vp run dev, isolated worktree .t3 state; web port 7613, server port 15653.
Client: T3 collaborative browser, 1280x800, no device emulation.
Provider: claudeAgent / claude-opus-5-5, full access.
Task: launch native Agent(run_in_background:true), sleep 20, then delegate_task to codex/gpt-6.1-sol, task 'Reply exactly OK'. Root must reply ROOT_STARTED and end immediately.

Database (read-only query of isolated orchestration_v2_projection_runs):
ordinal 1: requested 2026-10-22T10:15:49.582Z, completed 2026-10-22T10:15:58.848Z.
ordinal 2 (completion wake): requested 2026-10-22T10:16:27.664Z, completed 2026-10-22T10:16:31.309Z.

Observed web transcript:
ROOT_STARTED
Delayed delegate_task test: Finished
sleep 20 finished, but the delegate_task call failed and no delegated task was created.
Raw tool result:
<error>{"_tag":"OrchestratorMcpFailure","code":"parent_not_active","message":"Delegated tasks require an active run owned by this MCP provider session."}</error>

An independent native-background probe through the running T3 session returned the same raw error after its root turn settled.

Red test: OrchestratorMcpService.test.ts, 'a native background subagent delegates after its parent\'s run settles'.
AssertionError: expected OrchestratorMcpFailure to have deep property 'status'.
code: parent_not_active
message: Delegated tasks require an active run owned by this MCP provider session.
Control: marking the run running makes the same test pass; restored completed afterward.