perf(glm5next): apply MoE router gate once

[MadeBy561]

Purpose

Avoid applying the GLM-5.3 routed-expert gate twice.

Glm5NextMoE gave self.gate to FusedMoEFactory, whose MoERunner
derived router logits from hidden_states. The model wrapper also applied the
same gate before calling the runner, so every MoE layer launched two identical
router GEMMs while the runner discarded the first result.

Keep the gate in the model wrapper and stop giving it to FusedMoEFactory.
The runner now receives the real router logits computed by the model exactly
once; no placeholder tensor or optional custom-op contract is needed. Routing
math and precision are unchanged. Add regression tests for both parts of that
contract: the wrapper applies the gate once, and the factory does not own it.

No overlapping change was found in the current dev/jovian-judgement head or
open PR #488.

Test Plan

• Run the focused model tests:
  pytest -q tests/models/test_glm5next_model.py -k 'moe_applies_external_gate_once or moe_does_not_give_gate_to_runner'

• Compare sustained MTP0 C1 decode before and after on the same TP4 Blackwell
  host, exact model/cache/config, native B12X W4A4 routed experts, and normal
  sampling:

  llm_decode_bench.py --host <host> --port 5001 --model GLM-5.3-Flash --contexts 0 --concurrency 1 --duration 30 --display-mode plain --no-hw-monitor

Test Result

• Focused regression tests: 2 passed in the exact serving runtime.
• Matched baseline (e7097feb, B12X 2fcf23a): 123.23 tok/s.
• Patched repeats: 126.97, 127.00, 127.03 tok/s.
• Mean sustained C1 decode: 123.23 -> 127.00 tok/s, +3.06%.
• All performance runs used normal sampling; no temperature override or reduced
  output-token setting was used.

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR is described.
• The test plan provides commands.
• The test results provide a matched before/after comparison.
• No documentation update is required for this internal model execution fix.

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

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Plan: Pro Plus

Run ID: 36a85fbd-88c2-4e35-bfd4-8f9edfacc24c

📥 Commits

Reviewing files that changed from the base of the PR and between e7097fe and bb3c3a2.

📒 Files selected for processing (2)

• tests/models/test_glm5next_model.py
• vllm/models/glm5next/nvidia/model.py

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📝 Walkthrough

Walkthrough

Glm5NextMoE.forward stops invoking its local gate and passes hidden_states to self.experts. A regression test verifies gate bypass, router-logit forwarding, and unchanged expert output.

Changes

GLM5Next MoE gate delegation

Layer / File(s)	Summary
Delegate gate execution to fused experts vllm/models/glm5next/nvidia/model.py, tests/models/test_glm5next_model.py	Glm5NextMoE.forward passes hidden_states as router_logits to self.experts. The test verifies that the local gate is not called and that the expert output is returned unchanged.

Estimated code review effort: 3 (Moderate) | ~15–30 minutes

Merge Risk: ⚪ Minimal · up to bb3c3

The change delegates router-gate execution to the existing runner to remove duplicate computation while preserving routing behavior, with a regression test covering the delegation. No actionable merge-blocking risk remains beyond normal checks and review.

Suggested reviewers: lukealonso

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 7 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and concisely describes the main change: applying the GLM-5.3 MoE router gate once to avoid duplicate router computation.

• Fix all pre-merge checks with AI

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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