| name | hw-visual-verify |
| description | Visually verify a rendered change on real C64 hardware (U64/U2+/TeensyROM) by capturing the HDMI output through a USB capture device. Use when confirming overlays, display modes, palette/dither/color changes, or scene transitions actually render correctly — RAM dumps alone cannot prove what the VIC drew. |
Visual verification on real hardware
The U64's HTTP API lets you confirm what was written to screen / color RAM / VIC
registers (/v1/machine:readmem), but it can't tell you what the VIC actually
rendered — character-ROM mismatches, MCM bit-3 surprises, and mode-switch
artifacts only show up on the screen itself. When you need that ground truth and
a USB video capture device is wired to the U64's HDMI output (e.g. Elgato Cam
Link, AverMedia, any UVC capture stick), cv2.VideoCapture(index) will return
a 1080p BGR frame you can imwrite() and Read.
Don't write a capture script from scratch unless you need to. Use an existing
script in scripts/diags if one is available.
Ask the user before assuming a capture is available — they vary by machine. If
one is present, use it for verification of any visual change (overlays, display
modes, scene transitions) instead of guessing from RAM dumps alone.
Finding the capture device
c64cast --list-devices shows each camera's name + USB VID:PID + correct index
when the camera extra (cv2-enumerate-cameras) is installed — so the Cam Link is
identifiable by its Elgato VID rather than by trial-and-error index probing.
[video].device also accepts a name substring or VID:PID string (resolved via
camera.py resolve_camera_index), so a webcam scene
can target the capture stick stably.
Scope
Local-only machine specifics (which OpenCV index is the capture device on this
host, what else is on the LAN) belong in .claude/settings.local.json or
auto-memory, not in a checked-in file.
