AFTER — real T3 server and CLI output
Commit: 45c3c905c370bbf18152b46d4c2e68dd1a6ee056
Environment: Linux x86_64; Node v26.12.1; Pi (@earendil-works/pi-coding-agent) 1.4.0
Fresh isolated T3 database; synthetic git project; no copied live data.
Launch arguments: --session-dir /dev/null/pi-diagnostics
Message: diagnostics reproduction
Paths anonymized for publication. Server excerpts show the last occurrence of each relevant event.

CLI OUTPUT
$ t3 project add <synthetic-project> --title Pi crash diagnostics
Added project 8b3bd7e2-2f2d-43d7-a4ca-731d720c447c (Pi crash diagnostics) at <synthetic-project>.

$ t3 thread start <synthetic-project> diagnostics reproduction --title Pi crash diagnostics --provider pi --model default --json --wait
{"threadId":"mcp:90c0bffb-5971-4fe1-b927-119d512ac167","runId":"run:thread:mcp%3A90c0bffb-5971-4fe1-b927-119d512ac167:ordinal:1","status":"failed","reply":null,"error":"Pi RPC read failed: pi process exited with code 1\nError: ENOTDIR: not a directory, mkdir '/dev/null/pi-diagnostics'\nat mkdirSync (node:fs:1760:26)\nat new _SessionManager ([redacted]\nat _SessionManager.create ([redacted]."}
Thread mcp:90c0bffb-5971-4fe1-b927-119d512ac167 stopped with status failed: Pi RPC read failed: pi process exited with code 1
Error: ENOTDIR: not a directory, mkdir '/dev/null/pi-diagnostics'
at mkdirSync (node:fs:1760:26)
at new _SessionManager ([redacted]
at _SessionManager.create ([redacted].


SERVER DIAGNOSTIC EXCERPTS
[23:17:17.756] WARN (#2401): Pi process closed stdout.
  {
    detail: 'pi process exited with code 1\n' +
      "Error: ENOTDIR: not a directory, mkdir '/dev/null/pi-diagnostics'\n" +
      'at mkdirSync (node:fs:1760:26)\n' +
      'at new _SessionManager ([redacted]\n' +
      'at _SessionManager.create ([redacted]'
  }
[23:17:17.774] WARN (#2405): orchestration-v2.provider-session-runtime-failed
  {
    providerSessionId: 'provider-session:provider-instance:pi:thread:mcp%3A90c0bffb-5971-4fe1-b927-119d512ac167:0533246a-e472-4086-92e0-bee873726adf',
    cause: 'ProviderAdapterEventStreamError: Failed while streaming pi provider session provider-session:provider-instance:pi:thread:mcp%3A90c0bffb-5971-4fe1-b927-119d512ac167:0533246a-e472-4086-92e0-bee873726adf events.\n' +
      '    at file://<checkout>/packages/provider-pi/src/server/adapter.ts:2525:19\n' +
      '    at orchestrationV2.providerTurnStart.start (file://<checkout>/apps/server/src/orchestration-v2/ProviderTurnStartService.ts:1767:15)\n' +
      '    at orchestrationV2.providerTurnStart.start (definition) (file://<checkout>/apps/server/src/orchestration-v2/ProviderTurnStartService.ts:275:26)\n' +
      '    at ProviderTurnStartService.start (file://<checkout>/apps/server/src/orchestration-v2/EffectWorker.ts:164:16)\n' +
      '    at ProviderTurnStartService.start (definition) (file://<checkout>/apps/server/src/orchestration-v2/ProviderTurnStartService.ts:1761:21)\n' +
      '    at OrchestrationEffectExecutorV2.execute (file://<checkout>/apps/server/src/orchestration-v2/EffectWorker.ts:842:14)\n' +
      '    at OrchestrationEffectExecutorV2.execute (definition) (file://<checkout>/apps/server/src/orchestration-v2/EffectWorker.ts:101:23)\n' +
      '    at serverActivation.forkParkedFiber (file://<checkout>/apps/server/src/serverRuntimeStartup.ts:390:30)\n' +
      '    at serverActivation.forkParkedFiber (definition) (file://<checkout>/apps/server/src/serverActivation.ts:12:39)\n' +
      '    at ServerRuntimeStartup.startEffectWorkerWithRelay (file://<checkout>/apps/server/src/serverRuntimeStartup.ts:548:9)\n' +
      '    at ServerRuntimeStartup.startEffectWorkerWithRelay (definition) (file://<checkout>/apps/server/src/serverRuntimeStartup.ts:383:50) {\n' +
      '  [cause]: Error: Cause([Fail(PiRpcError: Pi RPC read failed: pi process exited with code 1\n' +
      "  Error: ENOTDIR: not a directory, mkdir '/dev/null/pi-diagnostics'\n" +
      '  at mkdirSync (node:fs:1760:26)\n' +
      '  at new _SessionManager ([redacted]\n' +
      '  at _SessionManager.create ([redacted].)])\n' +
      '}'
  }