PR 0130 Vulkan admit fallback combiners without active mux

PR #130 — Vulkan: admit fallback combiners without active mux

State: Merged Reviewed head: 93a5620d083e33ce607d80c4246bb71b7b633c32 Role: Supporting implementation/test history. The primary technical reference is Performance-Research-G07-Hybrid-Ubershader-Specialization.

Why it mattered

Admission checks should inspect state actually consumed by active work. A global unsupported mode is irrelevant when no active stage uses it.

Processing difference

flowchart LR
    A["Before: Any LSB mux selector rejected fallback, even inactive or zero-stage cases."] --> B["PR #130"]
    B --> C["After: Reject only an active stage that actually enables unsupported mux behavior."]

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Durable lesson

Admission checks should inspect state actually consumed by active work. A global unsupported mode is irrelevant when no active stage uses it.

Avoid repeating

• Do not infer correctness or cost from labels such as clean, finish, same handle, or disabled.
• Preserve the ownership, range, publication, retry, identity, or progress contract exposed by the PR.
• Keep focused correctness evidence separate from broad throughput claims.
• Re-run the relevant negative control when moving the mechanism to another renderer or subsystem.

Evidence pointer

• PR #130
• Reviewed head: 93a5620d083e33ce607d80c4246bb71b7b633c32
• Primary technical reference: Performance-Research-G07-Hybrid-Ubershader-Specialization

Architecture

This page records what the PR taught us. Current design, source status, future experiments, and acceptance rules belong on the linked technical reference page.