{
  "surface": "Real web client, Chromium preview browser, 1280x800 CSS pixels, light appearance",
  "setup": "Install each checkout with vp i; run T3CODE_DEV_SEED=0 node scripts/scenarios/start-app.ts web <fresh-home> 127.0.0.1 <port> in each checkout; run seed.mjs <checkout> <fresh-home>. Open the pairing path from fresh-home/pairing-path privately, then open the Selection timing sidebar row.",
  "terminalSetup": [
    {"tool":"preview_act","action":"click","selector":"[aria-label=\"Toggle terminal drawer\"]"},
    {"tool":"preview_act","action":"type","selector":"[aria-label=\"Terminal input\"]","text":"PS1='demo $ '; printf '\\033[2J\\033[H'; printf 'Selection timing example: triple-click this terminal line.\\n'"},
    {"tool":"preview_act","action":"press","key":"Enter"}
  ],
  "observer": "Evaluate observe-selection.js in the page. It observes visible DOM only and adds a timing badge; it does not change selection logic, timers, or action UI.",
  "recordedSteps": [
    {"tool":"preview_recording_start"},
    {"tool":"preview_evaluate","expression":"window.selectionProof.arm('Assistant triple-click','[aria-label=\"Cite selection in composer\"]',3)"},
    {"tool":"preview_act","action":"click","clickCount":3,"x":353,"y":141},
    {"tool":"preview_evaluate","expression":"window.selectionProof.results"},
    {"tool":"preview_act","action":"press","key":"Escape"},
    {"tool":"preview_evaluate","expression":"window.getSelection().removeAllRanges(); window.selectionProof.arm('Assistant double-click','[aria-label=\"Cite selection in composer\"]',2)"},
    {"tool":"preview_act","action":"click","clickCount":2,"x":353,"y":141},
    {"tool":"preview_evaluate","expression":"window.selectionProof.results"},
    {"tool":"preview_act","action":"press","key":"Escape"},
    {"tool":"preview_evaluate","expression":"window.getSelection().removeAllRanges(); window.selectionProof.arm('Terminal triple-click','[role=\"menuitem\"]',3)"},
    {"tool":"preview_act","action":"click","clickCount":3,"x":370,"y":533},
    {"tool":"preview_evaluate","expression":"window.selectionProof.results"},
    {"tool":"preview_recording_stop"}
  ],
  "observations": {
    "base": {"assistantTripleMs":600,"assistantDoubleMs":565,"terminalTripleMs":567},
    "head": {"assistantTripleMs":85,"assistantDoubleMs":548,"terminalTripleMs":99}
  },
  "limits": "DOM visibility sampled on requestAnimationFrame; preview recording is 4 fps. This demonstrates removal of the 500 ms delay, not exact one-frame paint latency. Base video trimmed to remove initial driver setup dead time; interaction playback speed unchanged.",
  "attribution": "AI-assisted; verified with the tests and tools listed above."
}