/leann-search

name: leann-search
description: Semantic search across codebase using LEANN vector index
allowed-tools: [Bash, Read]

LEANN Semantic Search

Use LEANN for meaning-based code search instead of grep.

When to Use

• **Conceptual queries**: "how does authentication work", "where are errors handled"
• **Understanding patterns**: "streaming implementation", "provider architecture"
• **Finding related code**: code that's semantically similar but uses different terms

When NOT to Use

• **Exact matches**: Use Grep for `class Foo`, `def bar`, specific identifiers
• **Regex patterns**: Use Grep for `error.*handling`, `import.*from`
• **File paths**: Use Glob for `*.test.ts`, `src/**/*.py`

Commands

# Search the current project's index
leann search <index-name> "<query>" --top-k 5

# List available indexes
leann list

# Example
leann search rigg "how do providers handle streaming" --top-k 5

MCP Tool (in Claude Code)

leann_search(index_name="rigg", query="your semantic query", top_k=5)

Rebuilding the Index

When codebase changes significantly:

cd /path/to/project
leann build <project-name> --docs src tests scripts \
  --file-types '.ts,.py,.md,.json' \
  --no-recompute --no-compact \
  --embedding-mode sentence-transformers \
  --embedding-model all-MiniLM-L6-v2

How It Works

1. LEANN uses sentence embeddings to understand *meaning* 2. Searches find conceptually similar code, not just text matches 3. Results ranked by semantic similarity score (0-1)

Grep vs LEANN Decision

| Query Type | Tool | Example | |------------|------|---------| | Natural language | LEANN | "how does caching work" | | Class/function name | Grep | "class CacheManager" | | Pattern matching | Grep | `error\|warning` | | Find implementations | LEANN | "rate limiting logic" |