Step 2 of the camera architecture overhaul agreed after #1395. When
the camera viewer hits its error state OR before a print at any
time, a Diagnose button runs a staged check against the printer and
renders the result inline: which stage failed, how long it took,
and a translated remediation hint. Cuts off the "user opens a
'camera broken' ticket → ask for support bundle → triage" loop at
the user's screen.
Backend
- New `backend/app/services/camera_diagnose.py` orchestrator with
CameraDiagnoseResult / CameraDiagnoseStage dataclasses.
- New POST /printers/{id}/camera/diagnose route in camera.py.
- Stages:
tcp_reachable — TCP socket open to 322 (RTSP) / 6000 (chamber)
with 3 s timeout. Distinguishes timeout, refused, and host-
unreachable into distinct summary codes so the frontend can
show a precise remediation (firewall vs LAN-only off vs
wrong IP).
first_frame — captures one JPEG end-to-end via the existing
capture_camera_frame_bytes pipeline. Auth + RTSP handshake +
first keyframe collapse into one stage; the user-facing
answer is the same regardless of which sub-layer failed.
- Live-stream shortcut: when a viewer is currently watching the
camera with a buffered frame < 10 s old, the diagnostic skips
the real test and returns live_stream_active_healthy. Opening a
fresh socket would kick the live viewer off on single-camera-
connection firmwares (the #1348 reconnect-storm trigger), so we
trust the real-world evidence instead.
- Response surfaces protocol, port, and profile name for support
triage — lets us ask "what does your modal say?" instead of
"send the support bundle".
Frontend
- New CameraDiagnoseModal renders one row per stage with green-
check / red-X / grey-skipped icons, the per-stage duration in
ms, a remediation banner styled by overall status, and a Run
again button.
- Two entry points:
1. The viewer's error overlay grows a Diagnose button next to
Retry. Retry stays the primary action; Diagnose is the
escape hatch for users who can't see what's wrong.
2. A stethoscope icon in the viewer's always-visible control
bar, between Refresh and Fullscreen. Pre-flight testing
("did my firmware update break the camera?", "is the
camera up before I send a print?") doesn't require waiting
for the stream to fail first.
- Also lifted the previously-hard-coded "Camera unavailable" /
"Retry" strings into camera.unavailable / camera.retry so the
error UI is fully translated alongside the new keys.
