`create` gave up after 45 s and dropped its `stop` flag WITHOUT setting it — the
`StopGuard` that owns the only `store(true)` was built on the success path only. The
thread meanwhile discarded its own send failure with `let _ =`, so it sailed past the
dead channel, made the virtual output PRIMARY, and parked in `while !stop` for the
rest of the process's life holding the D-Bus connection that IS the monitor's
lifetime. Its teardown was unreachable.
Under the default topology that orphan applies a SOLE-monitor APPLY_TEMPORARY config.
Every physical head goes dark, and Mutter reverts such a config only once the virtual
monitor disappears — which the parked thread prevents. There is no in-process
recovery: each retry adds another orphan and another virtual monitor.
The other three portal/D-Bus backends never had this — kwin.rs, hyprland.rs and
wlroots.rs all `?` on that exact send. Mutter is now the same shape, via a shared
`report_node` that stops the session when the opener has gone. Two more layers behind
it, because the send can also LAND in the moment `recv_timeout` gives up: `create`
and `stream_existing_output` build their guards BEFORE the wait, so every error arm
signals the thread on its way out, and the thread re-checks the flag before it touches
topology — so a doomed session never applies a sole-monitor config at all, rather than
applying one and reverting it a tick later.
The fix lands once because the duplication that caused it is gone first: `connect` and
`connect_monitor` shared ~72 verbatim lines, and the mirror path repeating the session
path's `let _ = send` is precisely what that copy bought. Both now share `open_rd_sc`
(steps 1-2) and `start_and_await_node` (step 4).
Also stops a physical hotplug stealing the virtual monitor's identity.
`wait_virtual_connector` took "any connector absent from the pre-snapshot" across a
window spanning a ~10 s stream wait plus 6 s of polling; TOPOLOGY_LOCK keeps sibling
sessions out of it but a hotplug is not ours to serialise, and the session's topology
apply and scale persistence would then be aimed at the operator's new panel. It now
prefers the connector advertising the client's exact WxH — the discriminator
`make_virtual_primary` already matches on — falls back to the old behaviour when that
singles nothing out, and warns when more than one candidate appears.
Tests: `pick_virtual` split out of the polling loop so the choice is testable without
a session bus. Verified on Linux (192.168.1.25): 99 passed, and the hotplug case FAILS
against the old first-new-connector logic, so it is not vacuous.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
enricobuehlerandClaude Opus 5
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