The Linux backend decision existed as open_video_backend's string match
plus five partial hand-copies (the zero-copy-plane gate, the pyro
advertisement gate, the software advertisement pin, the vulkan pref
ceiling, resolved_backend_is_gpu). Windows solved this long ago —
windows_resolved_backend() is consumed by its dispatch AND its mirrors,
with labels still stamped at the open sites. Linux now has the twin:
resolve_linux_backend (pure, lazy auto probe) + linux_resolved_backend
(config wrapper, unknown→auto exactly as every mirror's old `_` arm).
⚠ This deliberately DEVIATES from the audit's shadow-assertion
prescription, on both critics' findings: the shadow had no execution
venue (open_video had ZERO test call sites; shipped hosts are --release)
— unfalsifiable ceremony — and the file's own Windows half proves
dispatch-consumes-resolver is safe: the mgmt record is protected by the
label-from-the-open-site convention, not by resolver avoidance. One
consumed table beats two tables plus an inert cross-check.
Preservation riders from the critique, all applied:
- pref_ceiling KEEPS its cfg!(vulkan-encode) branch (the resolver is
feature-blind; dropping it re-creates advertise-then-die-at-open).
- linux_zero_copy_is_vaapi's Vulkan|Software arm preserves the old `_`
fallthrough EXACTLY — the vulkan-on-NVIDIA capture-plane mismatch and
the software twin are FILED in the design doc, not fixed here.
- resolved_backend_is_gpu splits as linux + not(any(windows, linux)) —
never a target list, so no exotic target loses the fn.
- The auto probe is lazy (impl FnOnce) — explicit prefs stay zero-probe
(/serverinfo polls through these mirrors), pinned by a panicking
closure in the resolver test.
New coverage: the full alias table pinned, and a GPU-free dispatch test
through the real open_video_backend (software arm, vendored openh264) —
its first test call site anywhere. Config-latch seam guarded loudly.
Cross-crate mirrors recorded out of scope in the design doc:
session_plan::resolve_encoder, gamestream/serverinfo.rs
base_codec_mode_support, capture.rs's "pyrowave" string.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
enricobuehlerandClaude Opus 5
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