[gspark-etri]

Background

Gemma hybrid caches were rejected whenever a remote prefill worker was configured. Fresh remote prefixes need different placement for sliding and global attention, and source dtype metadata can disagree with physical KV storage.

Changes

• Enable full-prefix hybrid PD imports, place sliding tails by lane and global KV by assigned block, and validate geometry and physical storage.
• Reset the imported lane's decode mask; fail partial-prefix results per request while retaining lane reuse.
• Add CPU regressions and a real ATOM HTTP validator using recorded RNGD KV exports.

Verification

• Base f84823a; hardware-validated change c76e03a; recovery follow-up 1e54786. PYTHONPATH=opt_prime python -m pytest -q opt_prime/tests/test_atom_hybrid.py opt_prime/tests/test_atom_batching.py opt_prime/tests/test_pd_recovery.py opt_prime/tests/test_serve_batched.py: 37 passed, one existing warning. Initial regression failed before the fix; partial-result and malformed KV geometry recovery verified red/green. Hardware/runtime errors still poison the scheduler; only validation errors before device writes are request-scoped. The exception follow-up also passed the long-input hardware rerun described below.
• One allocated ATOM, Gemma3-1B B1/context9216/k3, corrected experiment: isolate Gemma native global-prefill causality discrepancy #225 artifact, pinned checkpoint 5b11413a10db4e486ef16a20101fd028f8f2499c. Four questions at short/medium lengths, two passes, cancellation/disconnect and reuse: 18 normal/reuse responses exactly match native tokens through EOS; 20 remote / 0 local prefills including cancellations. Final free lane [0].
• Latest hardware follow-up on 1e54786 (evidence commit69bca73): four6423–6428token inputs, two passes, cancel/disconnect and reuse:10normal/reuse responses match native ATOM,12remote/0local prefills. This remains recorded RNGD KV replay. The shared arithmetic answer25 is wrong, so this proves behavior parity, not quality.
• Reproduction commands, selected JSON and experiment record under opt_prime/examples/pd/http_matrix/.
• Scoped Ruff and diff check pass. Sensitive checker: changed files clean; four unchanged baseline findings in unrelated documentation.

Compatibility and limits

Stacked on #230. Fresh full-prefix PD only; hybrid prefix/host cache restoration remains rejected. Hardware producer is recorded RNGD KV replay, not live prefill. No overlap, hardware batch >1 or speedup claim. Vendor SIGPIPE backtraces on socket disconnect persist despite successful reuse; separate #214/#215 addresses that issue. Corrected Gemma artifact depends on upstream optimum-rbln #827.

Related Issue

Closes #231. Parent validation #201/#227 remains active.