The streamed-screen pin is host-wide and persisted, but the session it applies to
is not. A box that boots between a desktop (heads to mirror) and a nested or
headless Game Mode (none) carried the pin into a session where `monitors::resolve`
could only fail — and since `vdisplay::open` is the one place every session opens a
display, that failure was a host refusing to stream at all rather than one
streaming the normal way. Pinning a monitor in Desktop mode bricked Game Mode.
A compositor reporting NO heads whatsoever now degrades to the virtual-display
path with the reason logged. Narrow on purpose: a pin that misses among heads that
DO exist stays the hard error §5.2 makes it — showing someone a different screen
than they asked for is the failure worth refusing over, and "there are no screens
here" is not that. An enumeration ERROR also stays on the mirror path, so the
session fails with the real reason instead of quietly ignoring the operator.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
enricobuehlerandClaude Opus 5
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