[gspark-etri]

Background

Hybrid-attention models (Gemma3) on ATOM need global block tables plus lane-local sliding cache tables when the batcher owns its KV block tables, and PD needs a path for batch-1 compiles that have only one KV block. This lands the code from a draft stack as one reviewable unit.

Changes

Taken from feat/236-atom-single-pd (draft PRs #210, #232, #237), only these paths:

• opt_prime/opt_prime/accel/platforms/atom/batching.py: hybrid global/sliding table ownership, decode-mask reset after fresh prefill, fresh full-prefix hybrid PD import (global layers into the lane's block, latest sliding window into the lane cache), batch-1 single-block PD with caches off, InvalidKVImport validation before any device write, physical KV element size checked from allocation size.
• opt_prime/tests/test_atom_hybrid.py (new), opt_prime/tests/test_atom_batching.py.
• opt_prime/docs/validation/batching/ATOM.md: fix: initialize hybrid ATOM KV tables and per-request masks #210's "Hybrid attention" paragraph rewritten: fresh full-prefix hybrid PD and batch-1 single-block PD with caches off are supported; hybrid prefix and host caching are still rejected; no link to a runtime validation record.

No evidence files, runtime records or validator scripts are included.

Verification

Run locally on this base (CPU, TORCH_DEVICE_BACKEND_AUTOLOAD=0):

• pytest -q tests/test_atom_hybrid.py tests/test_atom_batching.py: 33 passed.
• Same two files against the optimus-rm version of batching.py: 13 failed, 20 passed (the new cases fail without the change).
• Full suite: CI (cpu-tests).

Compatibility and limits

• Non-hybrid models with kv_blocks >= lanes + 1 behave as before.
• Hybrid prefix caching, host caching and partial remote prefixes are rejected (sliding-state restoration is not implemented, ATOM hybrid attention requires local KV table ownership #207).
• Single-block PD requires batch 1, a prefill worker, prefix/host caching off and a full prompt KV from position zero; the block is released after each request.
• No hardware run is claimed by this PR.

Related Issue

Closes #231
Closes #236
Refs #207 (stays open for sliding-state restoration)

Supersedes #210, #232, #237.

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