TEST ONLY — do not merge.

This is one fixed-current-runtime source discriminator for the separate C++ CTX PP forward/device-loop throughput regression. The asynchronous-consensus product change is already merged and is not under review here.

One-factor construction

• Native source: 544199a47b91b65d295322c6bb1f74dadbcf6a79
• Native source tree: 5726e87af6bc2267e116eb26c1bd71ef9c5fded6
• Native source parent: f665e59a7d650672433743bb6233712e04c5a90f
• This source is three first-parent commits earlier than the valid slow 58d8964d checkpoint from the preceding discriminator. The two intervening commits before 58d8964d are test-waiver and CODEOWNERS changes; 58d8964d is the only intervening product-code change.
• Current-runtime overlay is limited to the NIXL installer/development pins and all five image tags using build 202607151440-16194; stable patch ID: 7e73140158499de670b40490317c6f77601d06fc.
• The asynchronous-consensus factor is explicitly a semantically matched pre-cancellation port, not a byte-identical application. This native source predates the cancellation APIs expected by the later factor. The port preserves automatic NIXL/UCX TP1/CP1/PP activation, protocol version 1 with cancellation fixed off (mode 2), immutable terminal-vote publication, and coordinator poll/yield completion. It does not add or execute timeout publication or cancellation handling. Factor stable patch ID: 52adfb97177ae01283e352d36d52b428f2f1bf00.
• The coordinator implementation, MPI tags/utilities, and coordinator tests are byte-identical to the later validated factor. One CMake list-order normalization was restored after applying the factor and has no net tree effect beyond adding the factor source.
• The current image, native five-way stage mapping, workload YAML, selector, and timeout are unchanged from the preceding valid slow discriminator.
• Current main is present only as a no-tree second parent for CI mergeability.

Interpretation

• At least 1402 output tokens/s places the regression in the following three first-parent commits through 58d8964d, where the only product-code change is the NIXL in-flight-cancellation change.
• Near 800 output tokens/s excludes those three commits and moves the source bound earlier.
• Any partial recovery will be quantified.
• A build/import failure, timeout, failed request, cancellation event, or protocol-mode mismatch is compatibility/censored evidence and is not a throughput result.

Requested evidence

Run only GB300-12_GPUs-3_Nodes-PyTorch-Disagg-PerfSanity-CTX1-NODE1-GPU4-GEN1-NODE2-GPU8-Post-Merge-1, requiring the exact selector, three nodes, twelve tasks, four GPUs per node, --no-container-mount-home, 512/512 successful requests, coordinator activation with protocol mode 2 and cancellation disabled on all four CTX PP ranks, no timeout/cancellation events, clean shutdown, and a valid official throughput metric.

The draft will be closed after terminal evidence is captured; the branch will be preserved.