ScreenBrief

Record your iPhone screen while you talk about what you want changed, tap Copy, and paste into your coding agent's thread. The agent fetches the video and reads it as a timeline: what you said, next to screenshots of what was on screen at that moment.

It was built for T3 Code threads, for one person's use. The copied text is plain, so any agent that can run a command on the Mac can follow it.

Using it

1. Open ScreenBrief on the iPhone and tap Start recording. Tap Start Sharing in the system sheet (turn Microphone on the first time; iOS remembers it).
2. Switch to the app you are testing. Use it and say what you want changed.
3. Stop from the red status bar pill, or come back to ScreenBrief and tap the button again.
4. Open the recording in ScreenBrief, check the transcript, tap Copy.
5. Paste into the agent's thread. If the Mac cannot reach the phone (you are away from it), also attach the video from Photos, album "ScreenBrief". A recording over 50 MB is attached as its parts; the app says how many.

The agent runs screenbrief pull <id>, reads the FEEDBACK.md it prints, opens the frames, and makes the changes. If it cannot get the video it is told to wait for you rather than guess from the transcript.

Pasting from the field without the video. Turn on the background check once with screenbrief watch --install. A pull that cannot get the video is then remembered. When the iPhone is next in reach of the Mac (unlocked, on the same Wi-Fi or plugged in), the Mac fetches and processes the recording by itself and sends the waiting T3 Code thread a message with the FEEDBACK.md path, so the agent carries on without you attaching anything. The check runs every two minutes and only reaches for the phone while something is waiting. Getting the video across with no shared network at all is issue #4.

How it works

flowchart LR
  subgraph iPhone
    A[Record button] --> B[Broadcast extension<br/>screen + microphone<br/>H.264 + AAC .mov]
    B --> C[Photos<br/>album ScreenBrief]
    C --> D[App: copy into Documents,<br/>transcribe on the phone]
    D --> E[Copy: text brief<br/>id + instructions + transcript]
  end
  E -- paste --> T[Agent thread]
  C -. attach video<br/>when away .-> T
  subgraph Mac
    T --> P[screenbrief pull id]
    P --> V{Get the video}
    V -- phone reachable --> V1[devicectl copy<br/>from the app]
    V -- otherwise --> V2[video attached<br/>to the thread]
    V1 --> X[Transcribe with whisper.cpp,<br/>pick frames]
    V2 --> X
    X --> F[FEEDBACK.md<br/>+ frames + contact sheet]
  end
  F --> G[Agent reads it<br/>and makes the changes]

• iPhone app (ios/). A ReplayKit broadcast upload extension records the whole screen and the microphone, also while other apps are in front, and writes one fragmented QuickTime movie (about 750 kbps, so about 5.6 MB a minute). When the broadcast stops it saves the movie to Photos. The app notices the new video, copies it into its own Documents/Recordings/, transcribes it on the phone, and shows a list with playback, the transcript and a Copy button.

• The copied text (ios/ScreenBrief/Model/Brief.swift) holds the recording id, the instruction screenbrief pull <id>, what to do when the video cannot be fetched, and the phone's transcript.

• Mac CLI (mac/, Node, no dependencies beyond ffmpeg and whisper.cpp). screenbrief pull looks for the video in two places:

  • on the iPhone, through the developer pairing Xcode already has with it (phone unlocked, on the same Wi-Fi as the Mac or plugged in);
  • among the files attached in T3 Code (~/.t3/userdata/attachments), matched by the title the recorder writes into each movie (ScreenBrief-<id>, or ScreenBrief-<id>-part2of3 for a part), or for older recordings by the start time, which is also the id.

  It then transcribes with whisper.cpp, picks the frames that matter (the start of each spoken phrase, each screen change, each touch mark) and writes a bundle to ~/ScreenBrief/recordings/phone-<id>/ with FEEDBACK.md, frames/, a contact sheet and recording.mp4.

• Touch overlay (overlays/, optional). iOS does not show touches in a screen recording and does not let one app see touches in another. This is a debug-only component you add to the app you are testing; it draws taps, long presses and finger trails in magenta, and the Mac side turns them into timeline entries.

The extension and the app share no storage (there is no App Group): Photos is the hand-off, and a shared Keychain item carries the recorder's heartbeat and diagnostics. There is no pairing step, and nothing runs in the background on the Mac unless you turn on the optional check with screenbrief watch --install.

Limits

• About 8 minutes per file when you attach the video. T3 Code attaches files up to 50 MB each. The app splits a longer recording into parts that fit (no re-encoding) and saves them to Photos next to the original; you attach all the parts and screenbrief pull joins them. In the Photos picker the parts are the shorter videos right after the full one. When the Mac can reach the phone it copies the whole recording and the parts are not needed.
• Portrait. The movie's orientation is fixed by its first frame. Turning the phone to landscape partway through leaves that stretch sideways.
• Touches are not recorded unless the app you are testing has the overlay.
• A personal tool, opened up. It was made for one phone and one Mac. You build the iPhone app yourself (see below); expect rough edges.

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