Recording — GIF & MP4 evidence

When a criterion asserts behavior over time — streaming output, a loading→ loaded transition, a ticking timer, an animation, a multi-step flow — a static screenshot can't prove it. Record a clip and upload it as gif or video evidence. This is a first-class capability, not a nice-to-have: time-based claims are unverifiable without it.

Two ways to record. Prefer the CDP frame-sequence path — it's headless/ cloud-portable; OS screen recording is macOS-only.

Path 1 — CDP frame sequence → MP4/GIF (portable, recommended)

Capture a sequence of agent-browser screenshots while the behavior happens, then assemble with ffmpeg. Works on web (--session) and Electron (--cdp), and runs headless (no display, cloud-safe) because frames come from the browser engine, not the OS screen. It also sidesteps the corrupt-MP4-on-kill problem that ffmpeg screen capture has.

bash

# 1. capture frames while driving the scenario
FRAMES=$(mktemp -d)
TARGET="--session app" # or "--cdp 9222" for Electron
i=0
# start your scenario in the background or in another step, then:
while [ $i -lt 40 ]; do # ~20s at 0.5s/frame
  printf -v n "%06d" $i
  agent-browser $TARGET screenshot "$FRAMES/frame_$n.png"
  i=$((i + 1))
  sleep 0.5
done

# 2a. assemble an MP4 (~2 fps)
ffmpeg -y -framerate 2 -i "$FRAMES/frame_%06d.png" \
  -c:v libx264 -crf 23 -pix_fmt yuv420p ./proof/flow.mp4

# 2b. or a GIF (good palette = legible inline)
ffmpeg -y -framerate 2 -i "$FRAMES/frame_%06d.png" \
  -vf "scale=900:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" \
  ./proof/flow.gif

rm -rf "$FRAMES"

Tune the frame interval to the behavior: faster (0.25s) for quick animations, slower (1s) for long flows. Keep the clip scoped — a few seconds of the actual behavior, not the whole session.

Path 2 — OS screen recording (macOS, local only)

When you must capture the real screen — native windows, OS chrome, a non-Chromium app driven via computer-use.md — record at the OS level. This is macOS-only and not cloud-portable.

bash

# built-in: record the screen to MP4 (Ctrl-C / kill to stop; or -V N for N seconds)
screencapture -v ./proof/demo.mp4
screencapture -V 15 ./proof/demo.mp4 # fixed 15s capture

# ffmpeg avfoundation (list devices first: ffmpeg -f avfoundation -list_devices true -i "")
ffmpeg -y -f avfoundation -framerate 30 -i "1:none" -t 15 \
  -c:v libx264 -crf 23 -pix_fmt yuv420p ./proof/demo.mp4

Convert an MP4 to GIF when you need an inline-renderable artifact:

bash

ffmpeg -y -i ./proof/demo.mp4 \
  -vf "fps=8,scale=900:-1:flags=lanczos,split[s0][s1];[s0]palettegen[p];[s1][p]paletteuse" \
  ./proof/demo.gif

GIF vs MP4 — which to upload

GIF — short (≤ ~10s) UI behavior that should render inline in the report (loading state, a toast, a streamed line appearing). Renders without a player.
MP4 — longer demos or multi-step flows where file size matters and a player is acceptable. Larger, but better quality per byte.

Upload

bash

lh verify submit --operation "$LOBE_OPERATION_ID" --item "$CHECK_ITEM_ID" --type gif \
  --file ./proof/flow.gif --by agent-browser \
  --desc "Response streams in token-by-token after send"

lh verify submit --operation "$LOBE_OPERATION_ID" --item "$CHECK_ITEM_ID" --type video \
  --file ./proof/demo.mp4 --by cdp --desc "End-to-end import flow completes"

Prerequisites & portability

ffmpeg — brew install ffmpeg (or bun add -g ffmpeg-static). Needed for both paths' assembly/conversion.
agent-browser — for the CDP frame path (agent-browser.md).
Path 1 is headless/cloud-safe; Path 2 is macOS-only — see evidence.md.