Copy this template into the pull request description of every change that adds or modifies code in donner/gpu/, and fill in every section. A section that does not apply says so and why; a section left blank means the record is incomplete.

This record exists because the GPU runtime is a clean-room implementation. An independent provenance and license audit is a blocking release gate, and it can only be performed against contemporaneous records. Reconstructing one after the fact is not the same evidence.

Permitted inputs

Only these may inform an implementation:

• Donner's own renderer requirements, call sites, tests, captures, design docs, and shader algorithms.
• Normative public specifications: WebGPU, WGSL, Vulkan, SPIR-V.
• Official Apple Metal documentation and platform SDK interfaces.
• Black-box outputs of the current Donner renderer produced from Donner-owned test inputs: pixels, public error outcomes, counters, command captures, and timing measurements.

Prohibited inputs

• Source from wgpu, wgpu-native, Naga, Dawn, Tint, or their internal tests, whether copied or translated line by line.
• Their internal object models, private algorithms, generated headers, state trackers, shader IR, or backend workarounds.
• Linking any of those implementations into the runtime, shader toolchain, tests, or CI.

Reading a prohibited project's public documentation to understand a platform concept is not the same as reading its implementation. If you read its implementation, say so here and expect the change to be reworked from the specification instead.

Record

What this change implements

State the Donner requirement or the normative specification section, with a link or a section number. "Because the renderer needs it" is not a requirement; name the call site.

Design notes for nontrivial algorithms

For each nontrivial algorithm or state machine, describe the approach in your own words and why it was chosen. A change with no nontrivial algorithm says so.

Behavior-establishing tests

Name each test target and case that establishes the behavior. A behavior with no test is not established.

Frozen-baseline comparison

If the change alters rendered output, structural counters, or public error outcomes, name the frozen baselines it was compared against and the result. See donner/gpu/baseline/README.md.

Third-party headers, tools, and SDKs used

List every third-party header, platform SDK, out-of-process validator, and toolchain used to build or validate the change, with versions where the behavior depends on them. Out-of-process validators are not implementation dependencies, but they belong in the record.

Confirmation

• No prohibited implementation source was consulted, copied, or translated for this change.

• No prohibited implementation is linked into the runtime, tests, or CI by this change.

• Every third-party input used is listed above.