diag(track-a): revalidate DRI repair in isolated client startup

[blakinio]

Track A RUNTIME — isolated physical revalidation of merged DRI repair

Task: OTC-20260816-track-a-dri-repair-isolated-client-revalidation.
Base: exact trusted main@fa5b66b697d42c60515c5de48ea5e30135eadd0e after repair #429 and archive #430.
Execution: exactly one governance-compliant ephemeral_isolated physical discriminator on synology-otclient-01.

The experiment is derived from immutable accepted isolated startup harness blob 1616edcc982be50ef2c95b8077160ec8fe9291fe and the accepted XCB/GL diagnostic transformer. Relative to that accepted diagnostic surface, the only new runtime graphics/provider input is the already-proven contained DRI path supplied only to task-owned Xvfb as LIBGL_DRIVERS_PATH; the Xvfb argument list remains unchanged and no +extension GLX is added. The official-client process does not receive LIBGL_DRIVERS_PATH and no RHI/backend is forced.

No canonical lease/registration/session state, credentials, login, gameplay, Track B or historical #303 surface may be used. This task may mutate only its task-owned ephemeral namespace. Exactly one semantic physical run is authorized; any valid discriminator ends the experiment without retry.

Research output remains Draft-only; coordinator promotion is separate.

[blakinio]

Coordinator disposition: ACCEPT, superseded by current-main promotion PR #432. Semantic run 31970703417/job 95222630271 was governance-admitted (31970703290=SUCCESS), completed exactly one ephemeral-isolated execution, restored Xvfb GLX (opcode 150), removed the prior configured allowlist QXcb neither-GLX-nor-EGL / QRhiGles2 create-failure signature, and still observed the exact client alive with zero visible windows through 35s. Cleanup completed; no canonical state, credentials/login/gameplay/backend forcing or Track B access. Final source head 17e09be passed governance 31970849706 and CI 31970849838 / Required 95222998232, with zero review threads. Closing this researcher Draft unmerged; durable task/evidence blobs are replayed in #432 without temporary workflow history.