context-library-lookup

name	context_library_lookup
description	Locate and extract authoritative documentation and source code for the vendored xgrammar and vLLM materials stored under the repository's .context/ directory.

SKILL: Lookup xgrammar + vLLM context from .context/

Purpose

Ground answers about xgrammar and vLLM in the exact vendored materials in this repo. The .context/ directory contains documentation, examples, and (for xgrammar) the Python package source. Use it instead of upstream web docs to avoid version mismatch.

When to Use

Use this skill whenever questions involve:

• Grammar-constrained decoding, EBNF/regex grammars, or XGrammar APIs.
• vLLM structured outputs, tool calling, FunctionGemma integration, or server behavior.
• Any symbols likely defined in xgrammar or vLLM rather than this repo.

Do NOT use external web docs if the relevant info exists in .context/.

Vendored Roots (Actual Layout)

Top-level context docs:

• .context/CUSTOM_XGRAMMAR_GUIDE.md
• .context/FUNCTIONGEMMA_DOCS.md
• .context/FUNCTIONGEMMA_PROMPT_TIPS.md
• .context/STRUCTURAL_TAG_INTEGRATION_EXPLORATION.md
• .context/SERVER_SETUP.md
• .context/SERVER_LOG_GUIDE.md
• .context/HOW_TO_CREATE_AN_AGENT.md
• .context/HOW_TO_CREATE_A_GRAIL_PYM_SCRIPT.md
• .context/functiongemma_examples/

xgrammar materials:

• .context/xgrammar/README.md
• .context/xgrammar/docs/
• .context/xgrammar/examples/
• .context/xgrammar/python/ (Python package source)

vLLM materials:

• .context/vllm/README(16).md
• .context/vllm/tool_calling.md
• .context/vllm/structured_outputs.md
• .context/vllm/VLLM_FUNCTIONGEMMA_DOCS.md
• .context/vllm/*.py (examples and scripts)
• .context/vllm/lora.md

Core Workflow

1. Identify whether the concept is xgrammar or vLLM.
2. Start with docs/README files, then check examples.
3. For xgrammar APIs, use .context/xgrammar/python/ for canonical source.
4. Extract minimal authoritative excerpts (signature + key logic/notes).
5. Answer with file paths + line references.

Search Tactics (ripgrep)

Start narrow:

xgrammar:

rg -n "MySymbol" .context/xgrammar
rg -n "EBNF|grammar|constraint" .context/xgrammar
rg -n "def my_function" .context/xgrammar/python

vLLM:

rg -n "tool calling|structured outputs" .context/vllm
rg -n "FunctionGemma" .context/vllm
rg -n "server|openai" .context/vllm

If origin is unclear, search both:

rg -n "SomeUniqueString" .context/xgrammar .context/vllm

Documentation First

Priority order:

1. .context/* topic guides (FunctionGemma, server setup, structural tags)
2. Library READMEs and docs directories
3. Example scripts
4. xgrammar Python source (canonical implementation)

Note: The vLLM export here is documentation + example scripts, not full source.

Canonical Definition Rules

xgrammar

• Prefer .context/xgrammar/python/ for API definitions and logic.
• Use docs to explain intended usage or constraints.

vLLM

• Prefer .context/vllm/*.md for behavior and configuration.
• Use example scripts to clarify expected request shapes or usage patterns.

Extract Minimal Authoritative Excerpts

Include:

• Function/class signature or relevant section header
• Docstring or paragraph that defines semantics
• The minimal snippet that answers the question

Avoid dumping whole files.

Response Template

1. Library: xgrammar or vLLM
2. Where in .context/: root + key file(s)
3. Docs say: short summary with file reference
4. Implementation (if xgrammar): key snippet with file reference
5. Behavior summary tied to cited lines

Anti-Patterns

• Don’t rely on upstream GitHub docs if .context/ has it.
• Don’t assume behavior from memory.
• Don’t cite only index/re-export files.
• Don’t paste huge code blocks.

Quick Cheatsheet

Grammar-constrained decoding

• Start: .context/CUSTOM_XGRAMMAR_GUIDE.md, .context/xgrammar/README.md
• Then: .context/xgrammar/docs/, .context/xgrammar/python/

vLLM structured outputs/tool calling

• Start: .context/vllm/structured_outputs.md, .context/vllm/tool_calling.md
• Then: .context/vllm/VLLM_FUNCTIONGEMMA_DOCS.md, example scripts

FunctionGemma integration

• Start: .context/FUNCTIONGEMMA_DOCS.md, .context/FUNCTIONGEMMA_PROMPT_TIPS.md
• Then: .context/functiongemma_examples/, .context/vllm/VLLM_FUNCTIONGEMMA_DOCS.md

Goal

Produce answers that are verifiably grounded in the vendored xgrammar and vLLM materials in .context/, with file/line references for quick confirmation.