# R31 — Metadata no-grace exception

Environment: fs-50; Linux 6.8.0-117-generic x86_64; Node v26.12.1; Playwright 1.60.0; Chrome Headless Shell 157.0.8103.38; isolated dev:server, T3CODE_DEV_SEED=0, fresh per-checkout SQLite; synthetic Fx fixture; RPC/MCP over loopback; UTC timestamps.

Scripted interaction (same inputs on both revisions; generated ids differ): Delay the post-evaluate status read by 800ms against its internal 500ms budget; capture metadata fallback, eventual read settlement, subsequent ordinary status and evaluate.

What differed: Both keep successful evaluate despite metadata timeout and retain the same host connection for subsequent calls; only metadata falls back.

## C2meta steps and timestamps

Before step times (UTC):

```jsonl
{"time":"2026-11-10T11:43:01.664Z","tool":"preview_open","caller":0,"args":{"reuseExistingTab":false,"open":false}}
{"time":"2026-11-10T11:43:01.817Z","tool":"preview_evaluate","caller":0,"args":{"tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","expression":"document.body.dataset.probe=\"ok\"; \"ok\""}}
{"time":"2026-11-10T11:43:02.934Z","tool":"preview_status","caller":0,"args":{"tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36"}}
{"time":"2026-11-10T11:43:02.948Z","tool":"preview_evaluate","caller":0,"args":{"tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","expression":"document.body.dataset.probe=\"ok\"; \"ok\""}}
{"time":"2026-11-10T11:43:03.036Z","tool":"t3_preview_close","caller":0,"args":{"tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36"}}
```

After step times (UTC):

```jsonl
{"time":"2026-11-10T11:40:34.904Z","tool":"preview_open","caller":0,"args":{"reuseExistingTab":false,"open":false}}
{"time":"2026-11-10T11:40:35.023Z","tool":"preview_evaluate","caller":0,"args":{"tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","expression":"document.body.dataset.probe=\"ok\"; \"ok\""}}
{"time":"2026-11-10T11:40:36.136Z","tool":"preview_status","caller":0,"args":{"tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3"}}
{"time":"2026-11-10T11:40:36.142Z","tool":"preview_evaluate","caller":0,"args":{"tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","expression":"document.body.dataset.probe=\"ok\"; \"ok\""}}
{"time":"2026-11-10T11:40:36.150Z","tool":"t3_preview_close","caller":0,"args":{"tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3"}}
```

<a id="before"></a>
## Before — C2meta

SHA: [fa2f4ff2a2](https://github.com/pingdotgg/t3code/commit/fa2f4ff2a2bac5ac92e07749f6b83b0003d642a0)

Agent-visible results (status/list fields selected; error text verbatim):

```jsonl
{"time":"2026-11-10T11:43:01.817Z","tool":"preview_open","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","url":null,"loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:43:02.333Z","tool":"preview_evaluate","caller":0,"result":{"isError":false,"structuredContent":{"value":"ok"}}}
{"time":"2026-11-10T11:43:02.948Z","tool":"preview_status","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","url":null,"loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:43:03.036Z","tool":"preview_evaluate","caller":0,"result":{"isError":false,"structuredContent":{"value":"ok"}}}
{"time":"2026-11-10T11:43:03.047Z","tool":"t3_preview_close","caller":0,"result":{"isError":false,"structuredContent":{}}}
```

Relevant server milestones:

```jsonl
{"time":"2026-11-10T11:41:26.652Z","event":"host.connected","connectionId":"e4558845-047d-4489-8aed-1f3ec563d9e4"}
{"time":"2026-11-10T11:43:01.678Z","event":"request.start","operation":"open","requestId":"preview-34","tabId":"tab_2_1322bfd2-cca3-4137-992e-c9da3d086a36","timeoutMs":660000,"connectionId":"e4558845-047d-4489-8aed-1f3ec563d9e4"}
{"time":"2026-11-10T11:43:01.807Z","tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","event":"tab.created","detail":{"desktop":false,"isolatedContext":true}}
{"time":"2026-11-10T11:43:01.809Z","event":"operation.settled","requestId":"preview-34","operation":"open","ok":true}
{"time":"2026-11-10T11:43:01.825Z","event":"request.start","operation":"evaluate","requestId":"preview-35","tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","timeoutMs":15000,"connectionId":"e4558845-047d-4489-8aed-1f3ec563d9e4"}
{"time":"2026-11-10T11:43:01.830Z","event":"operation.settled","requestId":"preview-35","operation":"evaluate","ok":true}
{"time":"2026-11-10T11:43:01.830Z","event":"request.start","operation":"status","requestId":"preview-36","tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","timeoutMs":500,"connectionId":"e4558845-047d-4489-8aed-1f3ec563d9e4"}
{"time":"2026-11-10T11:43:02.331Z","event":"metadata.fallback","tag":"PreviewAutomationTimeoutError"}
{"time":"2026-11-10T11:43:02.631Z","event":"operation.settled","requestId":"preview-36","operation":"status","ok":true}
{"time":"2026-11-10T11:43:02.939Z","event":"request.start","operation":"status","requestId":"preview-37","tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","timeoutMs":15000,"connectionId":"e4558845-047d-4489-8aed-1f3ec563d9e4"}
{"time":"2026-11-10T11:43:02.940Z","event":"operation.settled","requestId":"preview-37","operation":"status","ok":true}
{"time":"2026-11-10T11:43:02.954Z","event":"request.start","operation":"evaluate","requestId":"preview-38","tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","timeoutMs":15000,"connectionId":"e4558845-047d-4489-8aed-1f3ec563d9e4"}
{"time":"2026-11-10T11:43:03.032Z","event":"operation.settled","requestId":"preview-38","operation":"evaluate","ok":true}
{"time":"2026-11-10T11:43:03.033Z","event":"request.start","operation":"status","requestId":"preview-39","tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","timeoutMs":500,"connectionId":"e4558845-047d-4489-8aed-1f3ec563d9e4"}
{"time":"2026-11-10T11:43:03.033Z","event":"operation.settled","requestId":"preview-39","operation":"status","ok":true}
{"time":"2026-11-10T11:43:03.043Z","event":"request.start","operation":"close","requestId":"preview-40","tabId":"tab_4_1322bfd2-cca3-4137-992e-c9da3d086a36","timeoutMs":15000,"connectionId":"e4558845-047d-4489-8aed-1f3ec563d9e4"}
{"time":"2026-11-10T11:43:03.044Z","event":"operation.settled","requestId":"preview-40","operation":"close","ok":true}
```

<a id="after"></a>
## After — C2meta

SHA: [b088b88d19](https://github.com/pingdotgg/t3code/commit/b088b88d19fb0edc43f754da2e1d199bda70d6d8)

Agent-visible results (status/list fields selected; error text verbatim):

```jsonl
{"time":"2026-11-10T11:40:35.023Z","tool":"preview_open","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","url":null,"loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:40:35.536Z","tool":"preview_evaluate","caller":0,"result":{"isError":false,"structuredContent":{"value":"ok"}}}
{"time":"2026-11-10T11:40:36.142Z","tool":"preview_status","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","url":null,"loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:40:36.149Z","tool":"preview_evaluate","caller":0,"result":{"isError":false,"structuredContent":{"value":"ok"}}}
{"time":"2026-11-10T11:40:36.159Z","tool":"t3_preview_close","caller":0,"result":{"isError":false,"structuredContent":{}}}
```

Relevant server milestones:

```jsonl
{"time":"2026-11-10T11:38:06.533Z","event":"host.connected","connectionId":"61893f52-5b7b-45e6-b0a0-72e49d4ebf16"}
{"time":"2026-11-10T11:40:34.909Z","event":"request.start","operation":"open","requestId":"preview-34","tabId":"tab_2_b49bf147-bc21-4874-9243-25ceadea1fd3","timeoutMs":660000,"connectionId":"61893f52-5b7b-45e6-b0a0-72e49d4ebf16"}
{"time":"2026-11-10T11:40:35.016Z","tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","event":"tab.created","detail":{"desktop":false,"isolatedContext":true}}
{"time":"2026-11-10T11:40:35.017Z","event":"operation.settled","requestId":"preview-34","operation":"open","ok":true}
{"time":"2026-11-10T11:40:35.028Z","event":"request.start","operation":"evaluate","requestId":"preview-35","tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","timeoutMs":15000,"connectionId":"61893f52-5b7b-45e6-b0a0-72e49d4ebf16"}
{"time":"2026-11-10T11:40:35.030Z","event":"operation.settled","requestId":"preview-35","operation":"evaluate","ok":true}
{"time":"2026-11-10T11:40:35.031Z","event":"request.start","operation":"status","requestId":"preview-36","tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","timeoutMs":500,"connectionId":"61893f52-5b7b-45e6-b0a0-72e49d4ebf16"}
{"time":"2026-11-10T11:40:35.532Z","event":"metadata.fallback","tag":"PreviewAutomationTimeoutError"}
{"time":"2026-11-10T11:40:35.831Z","event":"operation.settled","requestId":"preview-36","operation":"status","ok":true}
{"time":"2026-11-10T11:40:36.140Z","event":"request.start","operation":"status","requestId":"preview-37","tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","timeoutMs":15000,"connectionId":"61893f52-5b7b-45e6-b0a0-72e49d4ebf16"}
{"time":"2026-11-10T11:40:36.140Z","event":"operation.settled","requestId":"preview-37","operation":"status","ok":true}
{"time":"2026-11-10T11:40:36.146Z","event":"request.start","operation":"evaluate","requestId":"preview-38","tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","timeoutMs":15000,"connectionId":"61893f52-5b7b-45e6-b0a0-72e49d4ebf16"}
{"time":"2026-11-10T11:40:36.147Z","event":"operation.settled","requestId":"preview-38","operation":"evaluate","ok":true}
{"time":"2026-11-10T11:40:36.148Z","event":"request.start","operation":"status","requestId":"preview-39","tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","timeoutMs":500,"connectionId":"61893f52-5b7b-45e6-b0a0-72e49d4ebf16"}
{"time":"2026-11-10T11:40:36.148Z","event":"operation.settled","requestId":"preview-39","operation":"status","ok":true}
{"time":"2026-11-10T11:40:36.157Z","event":"request.start","operation":"close","requestId":"preview-40","tabId":"tab_4_b49bf147-bc21-4874-9243-25ceadea1fd3","timeoutMs":15000,"connectionId":"61893f52-5b7b-45e6-b0a0-72e49d4ebf16"}
{"time":"2026-11-10T11:40:36.158Z","event":"operation.settled","requestId":"preview-40","operation":"close","ok":true}
```

AI-assisted; verified with the tests and tools listed above.