[982945902]

Summary

• add a streaming Rust tool parser for LiquidAI LFM2/LFM2.5 output
• parse list-wrapped Python-style calls with dotted names, parallel calls, nested JSON-compatible literals, sets, signed numbers, and reserved-keyword arguments
• recover common LFM2 output quirks including raw control characters in strings and zero-padded integers
• preserve LFM2 special tokens, suppress echoed tool-call bodies, and safely fall back to text for malformed calls
• register the lfm2 parser and automatic LiquidAI/LFM2* model matching

Refs #44280.

Duplicate-work check

I claimed the lfm2 roadmap item in #44280 and re-checked the roadmap comments plus open PR searches for lfm2, LFM2 tool parser, and the roadmap issue number. I found no existing claim or open PR implementing the Rust LFM2 parser.

This is separate from #52579 (Olmo3). Both use rustpython-parser, but the parser formats, state machines, and tests are independent.

Tests

• cargo test --manifest-path rust/Cargo.toml -p vllm-parser --lib — 439 passed
• cargo test --manifest-path rust/Cargo.toml -p vllm-chat --lib — 279 passed
• cargo clippy --manifest-path rust/Cargo.toml -p vllm-parser -p vllm-chat --all-targets -- -D warnings — passed
• changed-file pre-commit hooks — passed

Model-output evaluation

The focused Rust regression fixtures exercise representative LFM2/LFM2.5 output shapes from the existing Python parser suite: parallel and parameterless calls, dotted names, nested collections, sets, Python/JSON literals, split streaming markers, trailing content, echoed-call suppression, raw newline/NUL characters, zero-padded integers, reserved Python keyword arguments, empty call lists, and malformed-call fallback.

A Hugging Face tokenizer/template roundtrip was not added because this environment could not connect to huggingface.co; no model-weight evaluation was run. The parser itself does not affect model execution or sampling.

AI assistance

OpenAI Codex was used to help implement and test this change. The human submitter is responsible for reviewing every changed line and defending the change end-to-end.

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[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @982945902.

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

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.

[982945902]

Rebased onto the latest main and re-reviewed the LFM2 state machine, malformed-input fallback, streaming boundaries, and automatic model routing. I found no additional correctness issue requiring a code change.

Validation on the current head:

• cargo test --manifest-path rust/Cargo.toml -p vllm-parser --lib — 431 passed
• cargo test --manifest-path rust/Cargo.toml -p vllm-chat --lib — 276 passed
• Clippy with -D warnings — passed
• changed-file pre-commit hooks — passed

DCO now passes and the PR is mergeable. The remaining failed pre-run-check is the first-time-contributor gate; could a maintainer add verified or ready so CI can run?

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @982945902.

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

[982945902]

Rebased onto current main (687db59744) and resolved the parser-name/Cargo manifest conflicts while preserving the current serde rc feature.

Validation on the rebased head:

• vllm-parser: 439 passed
• vllm-chat: 279 passed
• Clippy with -D warnings: passed
• changed-file pre-commit hooks: passed

[mergify]

This pull request has merge conflicts that must be resolved before it can be
merged. Please rebase the PR, @982945902.

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