[GG] fix(workspace): isolate target and speculative execution buffers

[voipmonitor]

Summary

• add independent workspace lanes per ubatch
• route target execution through lane 0 and speculative execution through lane 1
• cover model load, attention setup, warmup, capture, proposal, and capacity computation
• keep PCIe lifecycle, MRV2 profiling, and MoE scheduling changes out of this PR

Root cause

The target model and speculator previously shared process-global workspace storage. Captured views from one execution path could be invalidated or aliased when the other path resized or reused that storage. Workspace ownership must include both ubatch and execution lane.

Merge order

This branch is based directly on dev/gilded-gnosis; it is not stacked. Merge this before the reduced #149. After it lands, #149 will be refreshed against the new GG head so its profiling-only speculator capture also enters lane 1.

Validation

• tests/v1/worker/test_workspace.py: 3 passed
• Ruff lint and format checks passed
• git diff --check passed

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Review details

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Configuration used: Organization UI

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📥 Commits

Reviewing files that changed from the base of the PR and between 73e4a8c and b14c1dc.

📒 Files selected for processing (5)

• tests/v1/worker/test_workspace.py
• vllm/v1/worker/gpu/model_runner.py
• vllm/v1/worker/gpu/warmup.py
• vllm/v1/worker/gpu_worker.py
• vllm/v1/worker/workspace.py

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/gg-speculator-workspace-lanes-20260721

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[voipmonitor]

Folded unchanged into #149 as the first reviewable commit. #149 now carries workspace ownership, graph-channel ownership, and MRV2 profiling as one direct-GG lifecycle fix, so there is no hidden merge-order dependency. Closing this PR as superseded; no implementation or tests were dropped.