VALIDATION ONLY: discriminate ROCm runtime-link cache defect

[nekomario28]

One-shot hosted A/B evidence carrier. Closed unmerged after discrimination. Base is the clean candidate; head adds only the temporary workflow.

Pinned identities:

• upstream feat(rocm): add RDNA3 and RDNA4 runtime foundation FlashML-org/FreeToken#132 base: 45417560beeba896a9b0866e50154d2a7a320b8b
• clean candidate: 2ccee21c1298377f7c6c211e44165f60c3039f7f
• carrier head: ab8e75d170561639e7082e00857b06ceb1b9aaf0

Hosted A/B result

Run 32812370176, job 97694048534: SUCCESS on Ubuntu 24.04.

The exact same regression was applied to both source trees:

upstream #132 base:
ROCM_RUNTIME_LINK_CACHE_BASE_RC=1
ROCM_RUNTIME_LINK_CACHE_BASE=EXPECTED_FAIL

clean candidate:
ROCM_RUNTIME_LINK_CACHE_REFRESH=PASS
ROCM_RUNTIME_LINK_CACHE_CANDIDATE=PASS

final:
ROCM_RUNTIME_LINK_CACHE_AB=BASE_RED_FIX_GREEN

The base failure was required to contain AssertionError. The job also verified exact carrier/candidate/base ancestry, exact two-file candidate diff, and git diff --check.

This confirms the filesystem/cache-lifetime discriminator: the fixed shared compatibility symlink in FlashML-org#132 cannot satisfy the regression after the original versioned runtime target disappears and the runtime origin changes, while the runtime-origin-keyed fix does.

No ROCm/GPU packages were installed. This does not claim a physical ROCm JIT build, performance result, or maintainer acceptance. Clean candidate remains fix/pr132-rocm-runtime-link-cache@2ccee21c1298377f7c6c211e44165f60c3039f7f; carrier is intentionally not merged.