[dongfengy]

Description

Enable Mooncake context reuse with attention-DP owners and unified-pool EAGLE-style MTP. Route connector hooks to the local request owner, carry the MTP prefill layout and lookahead/alignment requirements, and reserve completion capacity while preserving cancellation and preemption lifetimes.

Support is limited to context-only speculative requests with a cache transceiver and an actual unified target/draft KV pool. Vanilla MTP and separate draft pools remain unsupported; attention DP requires PP=1 and CP=1. Configuration must resolve to the supported model mode after loading its checkpoint metadata.

The implementation uses main's pool/role API and retains checkpoint identity, reuse scope, LoRA/multimodal keys, worker readiness, and shutdown draining. It does not restore the old donor CLI or old connector configuration.

Dependency: #20326. This draft targets main and includes the prerequisite commits; merge/rebase after that dependency lands.

Test Coverage

Carries the source ADP, connector-layout, Mooncake, and native reuse-alignment cases. Python AST parsing, fatal Python static checks, git diff --check, and independent source review passed. No builds, tests, GPU execution, or benchmarks were run. Validate multi-rank reuse, chunk boundaries, cancellation, transfer/recompute boundaries, and MTP correctness before leaving draft.

PR Checklist

• Description explains the supported behavior and scope.
• Commits include DCO sign-off.
• Runtime correctness and failure-path validation completed.
• Confirm CI platform and test-list coverage for the carried regression cases before leaving draft.
• Please check this after reviewing the above items as appropriate for this PR.