130 tests, ~20s, 94% coverage. Four rungs, each proving something the one
below it cannot:
registry admission, fan-out, signal authorization and teardown, no I/O
wire camelCase round-trip, malformed frames, WebSocket lifecycle
e2e real capture -> encode -> SRTP -> decode -> painted frames
realdisplay the actual X11 capture backend on a private Xvfb display
The e2e rung drives Chromium's fake media device, which produces a genuine
moving 1280x720 monitor stream, so the assertion is that a watcher's <video>
has a size and that its pixels change over time -- a frozen or never-started
peer connection fails the suite, which a "signal arrived" assertion would
not have caught.
Findings encoded as flags and comments, because each cost a debugging cycle:
the headless shell has no media stack at all (use channel="chromium");
mediaDevices is undefined off a secure context (serve over 127.0.0.1); and
--use-fake-ui-for-media-stream breaks real X11 capture by approving the
request without ever selecting a source, so the realdisplay suite selects
the source explicitly instead.
The realdisplay fixture strips WAYLAND_DISPLAY and DBUS_SESSION_BUS_ADDRESS
from the browser environment. Without that, a headed Chromium reaches
xdg-desktop-portal, mirrors the developer's actual desktop and raises a
permission dialog on their real screen -- which is exactly what happened
before this was isolated. Skipped unless MIRROR_REALDISPLAY=1.
Also guards the frontend's structure: scripts must parse as ES modules,
every id a script looks up must exist in its page, ids must not collide
across pages that share one stylesheet, and nothing may load from a CDN.
LLM-Generated: true
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