feat(glm53): stabilize hybrid graph metadata

[devinkuhn]

Summary

Adds graph-stable metadata storage for GLM-5.3 hybrid execution. This PR is stacked on #523 and contains only the persistent metadata/KDA delta.

Behavior

• fixed-address GDN metadata arena sized for the qualified capture envelope
• graph-safe pooled-selector arena and vectorized row selection
• separate KDA live-request and graph-plan capacities
• capture capacity includes the maximum CUDA-graph token shape
• precomputed KDA chunk indices and offsets are reused through captured execution
• fail-closed capacity checks instead of reallocating captured metadata
• preserves the newer Jovian live-tensor B12X KDA binding from merged PR perf(glm5next): run B12X KDA on live layer tensors #521

This extracts the production behavior from D16 commits 95e8533, 9c9d73c, e83f736, 3d39898, 3c4e5b1, and 42aee72.

Verification

• AST parse: 7 changed Python files
• git diff --check: clean
• D16 runtime qualification exercised these paths under TP4/DCP4/MTP3 FULL capture and replay

Broad CI is left to repository CI; no GPU builds were run on the controller.

AI assistance disclosure

AI assistance was used for implementation and test construction. Devin Kuhn reviewed and directed the behavior.

Final D22 production receipt (2026-08-30)

The reviewed production derivative retained fixed-address hybrid metadata and registered the exact DCP layout [2304, 2304, 2304, 9216] across four CUDA-IPC allocations. FULL graph capture and post-reload raw generation remained coherent with restart count 0 and no Xid/OOM/EngineDead.

Fleet-owned immutable deployment receipt: Apple-Federal-Credit-Union/fleet-infra#309.

Required dependency on #523

This PR is source-dependent on #523 because it imports vllm.models.glm5next_cudagraph, which #523 introduces. GitHub cannot target a contributor-fork branch as the base of an upstream PR, so this PR intentionally remains based on dev/jovian-judgement for now.

Merge order: merge #523 first, then rebase this branch onto the updated dev/jovian-judgement before merging #524. Until that rebase, #524 is not independently import-complete and should not be merged. The implementation is kept separate to preserve the requested feature-by-feature review boundary rather than duplicating #523's graph code here.

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📥 Commits

Reviewing files that changed from the base of the PR and between 0b67266 and 5779c76.

📒 Files selected for processing (7)

• tests/models/kimi_k3/test_kda.py
• tests/models/test_glm5next_pooled_indexer.py
• tests/v1/attention/test_gdn_metadata_builder.py
• vllm/model_executor/layers/mamba/gdn/kimi_gdn_linear_attn.py
• vllm/models/glm5next/nvidia/pooled_indexer.py
• vllm/models/kimi_k3/nvidia/ops/third_party/kda/chunk.py
• vllm/v1/attention/backends/gdn_attn.py

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