Adds coop_vk_validate, a harness that drives the Vulkan capture path end-to-end
against a shipping title (default Sphere Spectacle, a pure-Vulkan game) and asserts
frames reach the shared texture and advance, the captured resolution/colors are
sane, saves a BMP screenshot for visual confirmation, and reports the present rate.
Findings:
- Layer method WORKS: coop_vk_layer mirrors the game correctly at 1920x1080 --
right colors/brightness, no BGRA/RGBA swizzle, no sRGB darkening (screenshot
confirmed). The layer captures every present (no drops).
- Suspended-inject "Auto-attach" is NOT applicable to a Steam title that must launch
through Steam: its exe renders nothing when launched directly, so there's no Vulkan
present to catch. The layer is the method for Steam Vulkan games (the early-inject
mechanism itself is covered by mock_game_test's suspended-launch path).
- The layer does video, but the game needs coop_hook.dll co-injected for focus-spoof
or an unfocused, event-driven game throttles itself to a few fps (looks like a
capture slowdown but isn't). A present-rate number alone can't prove "no FPS impact"
-- it's the game's own cadence; capture stays off the critical path (every present
copied, read-back on its own queue + present-semaphore re-chain).
Also adds SharedTextureSource::read_frame (bulk RGBA readback) for the screenshot.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
