# R28 — Mirror FIFO and serialization

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): Hold B system dark appearance; enqueue B viewport, light+zoom, cookies+reload; resize C; release B.

What differed: After C progresses while B waits; B applies queued viewport, rendering, cookie clear, reload in order after held media ends. Before the global mirror is still behind A until A releases.

## C5 steps and timestamps

Before step times (UTC):

```jsonl
{"time":"2026-11-10T11:39:21.061Z","tool":"preview_open","caller":0,"args":{"reuseExistingTab":false,"open":false}}
{"time":"2026-11-10T11:39:21.141Z","tool":"preview_open","caller":0,"args":{"reuseExistingTab":false,"open":false}}
{"time":"2026-11-10T11:39:21.215Z","tool":"preview_open","caller":0,"args":{"reuseExistingTab":false,"open":false}}
{"time":"2026-11-10T11:39:21.288Z","tool":"preview_navigate","caller":0,"args":{"tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","url":"http://127.0.0.1:18766/fixture"}}
{"time":"2026-11-10T11:39:21.421Z","tool":"preview_set_appearance","caller":0,"args":{"tabId":"tab_d_bea12b60-c14f-4580-bb58-2b38123bd480","colorScheme":"dark"}}
{"time":"2026-11-10T11:39:38.940Z","event":"RPC.send","method":"preview.adjust","payload":{"threadId":"f41bc889-9c75-40ee-b7a0-6866bd924e3e","tabId":"tab_d_bea12b60-c14f-4580-bb58-2b38123bd480","colorScheme":"light"}}
{"time":"2026-11-10T11:39:41.540Z","event":"RPC.send","method":"preview.adjust","payload":{"threadId":"f41bc889-9c75-40ee-b7a0-6866bd924e3e","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","colorScheme":"dark"}}
{"time":"2026-11-10T11:39:41.745Z","event":"RPC.send","method":"preview.resize","payload":{"threadId":"f41bc889-9c75-40ee-b7a0-6866bd924e3e","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","viewport":{"_tag":"freeform","width":900,"height":700}}}
{"time":"2026-11-10T11:39:41.749Z","event":"RPC.send","method":"preview.adjust","payload":{"threadId":"f41bc889-9c75-40ee-b7a0-6866bd924e3e","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","colorScheme":"light","zoomFactor":1.5}}
{"time":"2026-11-10T11:39:41.751Z","event":"RPC.send","method":"preview.adjust","payload":{"threadId":"f41bc889-9c75-40ee-b7a0-6866bd924e3e","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","clear":"cookies","hardReload":true}}
{"time":"2026-11-10T11:39:41.753Z","event":"RPC.send","method":"preview.resize","payload":{"threadId":"f41bc889-9c75-40ee-b7a0-6866bd924e3e","tabId":"tab_f_bea12b60-c14f-4580-bb58-2b38123bd480","viewport":{"_tag":"freeform","width":700,"height":500}}}
{"time":"2026-11-10T11:39:42.055Z","event":"gate.release","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","mode":"resolve"}
{"time":"2026-11-10T11:39:43.271Z","event":"release.stuck.A"}
{"time":"2026-11-10T11:39:43.272Z","event":"gate.release","tabId":"tab_d_bea12b60-c14f-4580-bb58-2b38123bd480","mode":"resolve"}
```

After step times (UTC):

```jsonl
{"time":"2026-11-10T11:36:55.056Z","tool":"preview_open","caller":0,"args":{"reuseExistingTab":false,"open":false}}
{"time":"2026-11-10T11:36:55.139Z","tool":"preview_open","caller":0,"args":{"reuseExistingTab":false,"open":false}}
{"time":"2026-11-10T11:36:55.197Z","tool":"preview_open","caller":0,"args":{"reuseExistingTab":false,"open":false}}
{"time":"2026-11-10T11:36:55.262Z","tool":"preview_navigate","caller":0,"args":{"tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","url":"http://127.0.0.1:18766/fixture"}}
{"time":"2026-11-10T11:36:55.471Z","tool":"preview_set_appearance","caller":0,"args":{"tabId":"tab_c_bd9d2d9d-727d-4676-b1e8-9554a31f1406","colorScheme":"dark"}}
{"time":"2026-11-10T11:37:12.494Z","event":"RPC.send","method":"preview.adjust","payload":{"threadId":"100ee364-0c8a-4d22-8790-3614885b473c","tabId":"tab_c_bd9d2d9d-727d-4676-b1e8-9554a31f1406","colorScheme":"light"}}
{"time":"2026-11-10T11:37:15.111Z","event":"RPC.send","method":"preview.adjust","payload":{"threadId":"100ee364-0c8a-4d22-8790-3614885b473c","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","colorScheme":"dark"}}
{"time":"2026-11-10T11:37:15.315Z","event":"RPC.send","method":"preview.resize","payload":{"threadId":"100ee364-0c8a-4d22-8790-3614885b473c","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","viewport":{"_tag":"freeform","width":900,"height":700}}}
{"time":"2026-11-10T11:37:15.320Z","event":"RPC.send","method":"preview.adjust","payload":{"threadId":"100ee364-0c8a-4d22-8790-3614885b473c","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","colorScheme":"light","zoomFactor":1.5}}
{"time":"2026-11-10T11:37:15.323Z","event":"RPC.send","method":"preview.adjust","payload":{"threadId":"100ee364-0c8a-4d22-8790-3614885b473c","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","clear":"cookies","hardReload":true}}
{"time":"2026-11-10T11:37:15.326Z","event":"RPC.send","method":"preview.resize","payload":{"threadId":"100ee364-0c8a-4d22-8790-3614885b473c","tabId":"tab_e_bd9d2d9d-727d-4676-b1e8-9554a31f1406","viewport":{"_tag":"freeform","width":700,"height":500}}}
{"time":"2026-11-10T11:37:15.634Z","event":"gate.release","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","mode":"resolve"}
{"time":"2026-11-10T11:37:16.850Z","event":"release.stuck.A"}
{"time":"2026-11-10T11:37:16.850Z","event":"gate.release","tabId":"tab_c_bd9d2d9d-727d-4676-b1e8-9554a31f1406","mode":"resolve"}
```

<a id="before"></a>
## Before — C5

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

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

```jsonl
{"time":"2026-11-10T11:39:21.140Z","tool":"preview_open","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_d_bea12b60-c14f-4580-bb58-2b38123bd480","url":null,"loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_d_bea12b60-c14f-4580-bb58-2b38123bd480","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:39:21.215Z","tool":"preview_open","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","url":null,"loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_d_bea12b60-c14f-4580-bb58-2b38123bd480","owner":"agent","ownedByCaller":true},{"tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:39:21.288Z","tool":"preview_open","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_f_bea12b60-c14f-4580-bb58-2b38123bd480","url":null,"loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_d_bea12b60-c14f-4580-bb58-2b38123bd480","owner":"agent","ownedByCaller":true},{"tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","owner":"agent","ownedByCaller":true},{"tabId":"tab_f_bea12b60-c14f-4580-bb58-2b38123bd480","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:39:21.420Z","tool":"preview_navigate","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","url":"http://127.0.0.1:18766/fixture","loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_d_bea12b60-c14f-4580-bb58-2b38123bd480","owner":"agent","ownedByCaller":true},{"tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","owner":"agent","ownedByCaller":true},{"tabId":"tab_f_bea12b60-c14f-4580-bb58-2b38123bd480","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:39:37.438Z","tool":"preview_set_appearance","caller":0,"result":{"content":[{"type":"text","text":"Preview automation setColorScheme timed out after 15000ms."}],"isError":true}}
{"time":"2026-11-10T11:39:41.544Z","event":"RPC.result","method":"preview.adjust","result":{"tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","viewport":{"_tag":"freeform","width":800,"height":600},"colorScheme":"dark","zoomFactor":1.25}}
{"time":"2026-11-10T11:39:41.749Z","event":"RPC.result","method":"preview.resize","result":{"tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","viewport":{"_tag":"freeform","width":900,"height":700},"colorScheme":"dark","zoomFactor":1.25}}
{"time":"2026-11-10T11:39:41.751Z","event":"RPC.result","method":"preview.adjust","result":{"tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","viewport":{"_tag":"freeform","width":900,"height":700},"colorScheme":"light","zoomFactor":1.5}}
{"time":"2026-11-10T11:39:41.753Z","event":"RPC.result","method":"preview.adjust","result":{"tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","viewport":{"_tag":"freeform","width":900,"height":700},"colorScheme":"light","zoomFactor":1.5}}
{"time":"2026-11-10T11:39:41.754Z","event":"RPC.result","method":"preview.resize","result":{"tabId":"tab_f_bea12b60-c14f-4580-bb58-2b38123bd480","viewport":{"_tag":"freeform","width":700,"height":500}}}
```

Relevant server milestones:

```jsonl
{"time":"2026-11-10T11:37:01.802Z","event":"host.connected","connectionId":"df66ae07-3409-4a36-adf5-acca7ed48f60"}
{"time":"2026-11-10T11:39:38.436Z","event":"host.connected","connectionId":"a4ed59d2-1007-4877-9053-374f3fd9a6d0"}
{"time":"2026-11-10T11:39:43.283Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.283Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"setViewportSize.start","detail":[{"width":800,"height":600}]}
{"time":"2026-11-10T11:39:43.286Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"setViewportSize.end","detail":{}}
{"time":"2026-11-10T11:39:43.286Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"setViewportSize.start","detail":[{"width":800,"height":600}]}
{"time":"2026-11-10T11:39:43.286Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"setViewportSize.end","detail":{}}
{"time":"2026-11-10T11:39:43.287Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.287Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.287Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.start","detail":{"method":"Emulation.setDeviceMetricsOverride","params":{"width":640,"height":480,"deviceScaleFactor":2.5,"mobile":false}}}
{"time":"2026-11-10T11:39:43.288Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.end","detail":{"method":"Emulation.setDeviceMetricsOverride"}}
{"time":"2026-11-10T11:39:43.288Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.288Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.288Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.start","detail":{"method":"Page.reload","params":{"ignoreCache":true}}}
{"time":"2026-11-10T11:39:43.293Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.end","detail":{"method":"Page.reload"}}
{"time":"2026-11-10T11:39:43.294Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.294Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.start","detail":{"method":"Network.clearBrowserCookies"}}
{"time":"2026-11-10T11:39:43.294Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.end","detail":{"method":"Network.clearBrowserCookies"}}
{"time":"2026-11-10T11:39:43.294Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.start","detail":{"method":"Page.reload","params":{"ignoreCache":true}}}
{"time":"2026-11-10T11:39:43.298Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.end","detail":{"method":"Page.reload"}}
{"time":"2026-11-10T11:39:43.298Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.298Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.start","detail":{"method":"Network.clearBrowserCache"}}
{"time":"2026-11-10T11:39:43.303Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.end","detail":{"method":"Network.clearBrowserCache"}}
{"time":"2026-11-10T11:39:43.303Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.303Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.303Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"emulateMedia.start","detail":[{"colorScheme":"dark"}]}
{"time":"2026-11-10T11:39:43.303Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"emulateMedia.held","detail":{}}
{"time":"2026-11-10T11:39:43.317Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"emulateMedia.end","detail":{}}
{"time":"2026-11-10T11:39:43.318Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.318Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"setViewportSize.start","detail":[{"width":900,"height":700}]}
{"time":"2026-11-10T11:39:43.319Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"setViewportSize.end","detail":{}}
{"time":"2026-11-10T11:39:43.319Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.start","detail":{"method":"Emulation.setDeviceMetricsOverride","params":{"width":720,"height":560,"deviceScaleFactor":2.5,"mobile":false}}}
{"time":"2026-11-10T11:39:43.320Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.end","detail":{"method":"Emulation.setDeviceMetricsOverride"}}
{"time":"2026-11-10T11:39:43.320Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.320Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"emulateMedia.start","detail":[{"colorScheme":"light"}]}
{"time":"2026-11-10T11:39:43.321Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"emulateMedia.end","detail":{}}
{"time":"2026-11-10T11:39:43.321Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.start","detail":{"method":"Emulation.setDeviceMetricsOverride","params":{"width":600,"height":467,"deviceScaleFactor":3,"mobile":false}}}
{"time":"2026-11-10T11:39:43.322Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.end","detail":{"method":"Emulation.setDeviceMetricsOverride"}}
{"time":"2026-11-10T11:39:43.322Z","event":"mirror.received","type":"resized","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.322Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.start","detail":{"method":"Network.clearBrowserCookies"}}
{"time":"2026-11-10T11:39:43.322Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.end","detail":{"method":"Network.clearBrowserCookies"}}
{"time":"2026-11-10T11:39:43.322Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.start","detail":{"method":"Page.reload","params":{"ignoreCache":true}}}
{"time":"2026-11-10T11:39:43.323Z","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480","event":"cdp.end","detail":{"method":"Page.reload"}}
{"time":"2026-11-10T11:39:43.323Z","event":"mirror.received","type":"resized","tabId":"tab_f_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.324Z","tabId":"tab_f_bea12b60-c14f-4580-bb58-2b38123bd480","event":"setViewportSize.start","detail":[{"width":700,"height":500}]}
{"time":"2026-11-10T11:39:43.326Z","tabId":"tab_f_bea12b60-c14f-4580-bb58-2b38123bd480","event":"setViewportSize.end","detail":{}}
{"time":"2026-11-10T11:39:43.326Z","tabId":"tab_f_bea12b60-c14f-4580-bb58-2b38123bd480","event":"setViewportSize.start","detail":[{"width":700,"height":500}]}
{"time":"2026-11-10T11:39:43.326Z","tabId":"tab_f_bea12b60-c14f-4580-bb58-2b38123bd480","event":"setViewportSize.end","detail":{}}
{"time":"2026-11-10T11:39:43.706Z","event":"mirror.received","type":"navigated","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.706Z","event":"mirror.received","type":"navigated","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.706Z","event":"mirror.received","type":"navigated","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.706Z","event":"mirror.received","type":"navigated","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
{"time":"2026-11-10T11:39:43.706Z","event":"mirror.received","type":"navigated","tabId":"tab_e_bea12b60-c14f-4580-bb58-2b38123bd480"}
```

<a id="after"></a>
## After — C5

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

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

```jsonl
{"time":"2026-11-10T11:36:55.139Z","tool":"preview_open","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_c_bd9d2d9d-727d-4676-b1e8-9554a31f1406","url":null,"loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_c_bd9d2d9d-727d-4676-b1e8-9554a31f1406","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:36:55.197Z","tool":"preview_open","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","url":null,"loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_c_bd9d2d9d-727d-4676-b1e8-9554a31f1406","owner":"agent","ownedByCaller":true},{"tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:36:55.261Z","tool":"preview_open","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_e_bd9d2d9d-727d-4676-b1e8-9554a31f1406","url":null,"loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_c_bd9d2d9d-727d-4676-b1e8-9554a31f1406","owner":"agent","ownedByCaller":true},{"tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","owner":"agent","ownedByCaller":true},{"tabId":"tab_e_bd9d2d9d-727d-4676-b1e8-9554a31f1406","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:36:55.469Z","tool":"preview_navigate","caller":0,"result":{"isError":false,"selectedStatusFields":{"available":true,"tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","url":"http://127.0.0.1:18766/fixture","loading":false,"control":{"owner":"agent","ownedByCaller":true,"generation":0},"dialog":null,"viewportSetting":{"_tag":"fill"},"viewport":{"width":1280,"height":800},"tabs":[{"tabId":"tab_c_bd9d2d9d-727d-4676-b1e8-9554a31f1406","owner":"agent","ownedByCaller":true},{"tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","owner":"agent","ownedByCaller":true},{"tabId":"tab_e_bd9d2d9d-727d-4676-b1e8-9554a31f1406","owner":"agent","ownedByCaller":true}]}}}
{"time":"2026-11-10T11:37:10.993Z","tool":"preview_set_appearance","caller":0,"result":{"content":[{"type":"text","text":"Preview automation setColorScheme timed out after 15000ms."}],"isError":true}}
{"time":"2026-11-10T11:37:15.115Z","event":"RPC.result","method":"preview.adjust","result":{"tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","viewport":{"_tag":"freeform","width":800,"height":600},"colorScheme":"dark","zoomFactor":1.25}}
{"time":"2026-11-10T11:37:15.320Z","event":"RPC.result","method":"preview.resize","result":{"tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","viewport":{"_tag":"freeform","width":900,"height":700},"colorScheme":"dark","zoomFactor":1.25}}
{"time":"2026-11-10T11:37:15.323Z","event":"RPC.result","method":"preview.adjust","result":{"tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","viewport":{"_tag":"freeform","width":900,"height":700},"colorScheme":"light","zoomFactor":1.5}}
{"time":"2026-11-10T11:37:15.325Z","event":"RPC.result","method":"preview.adjust","result":{"tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","viewport":{"_tag":"freeform","width":900,"height":700},"colorScheme":"light","zoomFactor":1.5}}
{"time":"2026-11-10T11:37:15.332Z","event":"RPC.result","method":"preview.resize","result":{"tabId":"tab_e_bd9d2d9d-727d-4676-b1e8-9554a31f1406","viewport":{"_tag":"freeform","width":700,"height":500}}}
```

Relevant server milestones:

```jsonl
{"time":"2026-11-10T11:29:29.949Z","event":"host.connected","connectionId":"09b81d2d-300e-436a-8035-a1f18530f0d1"}
{"time":"2026-11-10T11:37:15.113Z","event":"mirror.received","type":"resized","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406"}
{"time":"2026-11-10T11:37:15.114Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"emulateMedia.start","detail":[{"colorScheme":"dark"}]}
{"time":"2026-11-10T11:37:15.114Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"emulateMedia.held","detail":{}}
{"time":"2026-11-10T11:37:15.318Z","event":"mirror.received","type":"resized","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406"}
{"time":"2026-11-10T11:37:15.322Z","event":"mirror.received","type":"resized","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406"}
{"time":"2026-11-10T11:37:15.324Z","event":"mirror.received","type":"resized","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406"}
{"time":"2026-11-10T11:37:15.330Z","event":"mirror.received","type":"resized","tabId":"tab_e_bd9d2d9d-727d-4676-b1e8-9554a31f1406"}
{"time":"2026-11-10T11:37:15.330Z","tabId":"tab_e_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"setViewportSize.start","detail":[{"width":700,"height":500}]}
{"time":"2026-11-10T11:37:15.334Z","tabId":"tab_e_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"setViewportSize.end","detail":{}}
{"time":"2026-11-10T11:37:15.334Z","tabId":"tab_e_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"setViewportSize.start","detail":[{"width":700,"height":500}]}
{"time":"2026-11-10T11:37:15.335Z","tabId":"tab_e_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"setViewportSize.end","detail":{}}
{"time":"2026-11-10T11:37:15.653Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"emulateMedia.end","detail":{}}
{"time":"2026-11-10T11:37:15.653Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"setViewportSize.start","detail":[{"width":900,"height":700}]}
{"time":"2026-11-10T11:37:15.657Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"setViewportSize.end","detail":{}}
{"time":"2026-11-10T11:37:15.657Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"cdp.start","detail":{"method":"Emulation.setDeviceMetricsOverride","params":{"width":720,"height":560,"deviceScaleFactor":2.5,"mobile":false}}}
{"time":"2026-11-10T11:37:15.658Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"cdp.end","detail":{"method":"Emulation.setDeviceMetricsOverride"}}
{"time":"2026-11-10T11:37:15.658Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"emulateMedia.start","detail":[{"colorScheme":"light"}]}
{"time":"2026-11-10T11:37:15.659Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"emulateMedia.end","detail":{}}
{"time":"2026-11-10T11:37:15.660Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"cdp.start","detail":{"method":"Emulation.setDeviceMetricsOverride","params":{"width":600,"height":467,"deviceScaleFactor":3,"mobile":false}}}
{"time":"2026-11-10T11:37:15.661Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"cdp.end","detail":{"method":"Emulation.setDeviceMetricsOverride"}}
{"time":"2026-11-10T11:37:15.662Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"cdp.start","detail":{"method":"Network.clearBrowserCookies"}}
{"time":"2026-11-10T11:37:15.663Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"cdp.end","detail":{"method":"Network.clearBrowserCookies"}}
{"time":"2026-11-10T11:37:15.663Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"cdp.start","detail":{"method":"Page.reload","params":{"ignoreCache":true}}}
{"time":"2026-11-10T11:37:15.666Z","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406","event":"cdp.end","detail":{"method":"Page.reload"}}
{"time":"2026-11-10T11:37:15.667Z","event":"mirror.received","type":"navigated","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406"}
{"time":"2026-11-10T11:37:15.690Z","event":"mirror.received","type":"navigated","tabId":"tab_d_bd9d2d9d-727d-4676-b1e8-9554a31f1406"}
```

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