[Bugfix][Frontend] Accept thinking as enable_thinking alias

[Atharv-16]

Purpose

Fixes #43728.

Some reasoning parsers only read enable_thinking from chat_template_kwargs, while clients / templates still pass thinking. When those disagree, you can get content: null or mismatched thinking mode.

This adds a shared resolve_enable_thinking() helper (enable_thinking canonical, thinking as alias) and wires it into the parsers that were still one-sided or duplicated the dual-read logic.

Not a duplicate

• No open PR targets [Bug] Inconsistent parameter names (thinking vs enable_thinking) between reasoning parsers and chat templates causes content:null #43728.
• Follows the collaborator note on the issue: keep enable_thinking as the canonical name and accept thinking as a compatible alias.
• Does not rewrite chat templates; only parser-side resolution.

Test Plan

.venv/bin/python -m pytest \
  tests/parser/test_resolve_enable_thinking.py \
  tests/parser/engine/test_qwen3_reasoning.py::TestThinkingDisabled \
  tests/parser/engine/test_nemotron_v3.py::TestNemotronSwap \
  -v --noconftest

Test Result

22 passed.

AI assistance

Cursor helped draft the helper, parser wiring, tests, and this PR text. I reviewed every changed line and ran the tests above.

Made with Cursor

[claude]

Claude Code Review

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[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @Atharv-16.

https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/working-with-forks/syncing-a-fork

[Atharv-16]

Rebased onto latest main (resolved a small import conflict in vllm/parser/nemotron_v3.py with the new CHATML_TURN_BOUNDARIES import).

Ready for review when you have a chance:
@tomeras91 @aarnphm @chaunceyjiang @sfeng33 @bbrowning

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No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Team

Run ID: 4af4db58-7325-4f2a-8d46-1cdfc50a1006

📥 Commits

Reviewing files that changed from the base of the PR and between 199cb9b and 92a41b2.

📒 Files selected for processing (10)

• tests/parser/engine/test_nemotron_v3.py
• tests/parser/engine/test_qwen3_reasoning.py
• tests/parser/test_resolve_enable_thinking.py
• vllm/parser/gemma4.py
• vllm/parser/glm47_moe.py
• vllm/parser/kimi_k2.py
• vllm/parser/ling3.py
• vllm/parser/nemotron_v3.py
• vllm/parser/qwen3.py
• vllm/parser/utils.py

Included review availability: Your plan provides up to 10 included reviews per hour; 9 remain after this review.

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📝 Summary

Summary by CodeRabbit

• New Features

  • Added support for using thinking as an alias for enable_thinking when configuring reasoning mode.
  • Standardized reasoning-mode configuration across supported model parsers, including configurable defaults and consistent handling when both options are provided.

• Tests

  • Added coverage for reasoning configuration, aliases, defaults, precedence, parser state, and content-only streaming when reasoning is disabled.

Walkthrough

Changes

The parser utilities now resolve thinking and enable_thinking through one shared helper. Gemma4, GLM-4.7, Kimi K2, Ling3, Nemotron V3, and Qwen3 use the helper. Tests cover defaults, aliases, parser states, and streaming output.

Thinking option resolution

Layer / File(s)	Summary
Shared resolver contract vllm/parser/utils.py, tests/parser/test_resolve_enable_thinking.py	Added resolve_enable_thinking with configurable defaults, alias support, OR precedence, and tests for supported inputs.
Parser integration vllm/parser/gemma4.py, vllm/parser/glm47_moe.py, vllm/parser/kimi_k2.py, vllm/parser/ling3.py, vllm/parser/nemotron_v3.py, vllm/parser/qwen3.py	Replaced parser-specific thinking-option logic with the shared resolver while preserving parser-specific defaults.
Parser behavior validation tests/parser/engine/test_nemotron_v3.py, tests/parser/engine/test_qwen3_reasoning.py	Added coverage for alias-controlled parser states, content routing, and disabled-thinking streaming output.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Merge Risk: ⚪ Minimal · up to 92a41

This update makes reasoning parsers honor both thinking option names consistently, preventing disabled-thinking responses from being misclassified as reasoning. The covered parser behavior and preserved defaults leave no actionable merge risk.

Sequence Diagram(s)

sequenceDiagram
  participant ChatTemplateKwargs
  participant ReasoningParser
  participant ParserState
  participant StreamOutput
  ChatTemplateKwargs->>ReasoningParser: provide thinking configuration
  ReasoningParser->>ParserState: select CONTENT or REASONING state
  ReasoningParser->>StreamOutput: parse model output
  StreamOutput-->>ParserState: emit content without reasoning when disabled

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🚥 Pre-merge checks | ✅ 3 | ❌ 2

❌ Failed checks (2 warnings)

Check name	Status	Explanation	Resolution
Linked Issues check	⚠️ Warning	The PR addresses shared resolution for several affected parsers, including Qwen3, Nemotron V3, and Kimi K2. However, the linked issue also identifies Hunyuan A13B as an affected parser, and no Hunyuan…	Apply resolve_enable_thinking() to the Hunyuan A13B parser, or provide evidence that it is already fixed elsewhere and is outside this PR's required scope. Verify the related parser behavior with tests.
Docstring Coverage	⚠️ Warning	Docstring coverage is 22.73% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 22 functions across 10 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly identifies the main change: accepting thinking as an alias for enable_thinking.
Description check	✅ Passed	The description explains the parameter inconsistency, the shared resolver, affected parser behavior, linked issue, and tests.
Out of Scope Changes check	✅ Passed	The changes are limited to the shared thinking-mode resolver, affected reasoning parsers, and focused parser tests. No unrelated code changes are indicated.

Full details: Linked Issues check

Explanation

The PR addresses shared resolution for several affected parsers, including Qwen3, Nemotron V3, and Kimi K2. However, the linked issue also identifies Hunyuan A13B as an affected parser, and no Hunyuan A13B changes appear in the PR.

• Fix all pre-merge checks with AI

✨ Finishing Touches 💡 1

🛠️ Fix failing CI checks 💡

• Create stacked PR
• Commit on current branch

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