open-codebase-index

open-codebase-index

Search a codebase by meaning, then follow the result into definitions, callers, and dependency paths.

open-codebase-index is a local semantic code index for OpenCode, Jcode, Pi, Codex, Claude Code, and other MCP clients. It combines embeddings, BM25 keyword search, branch-aware filtering, symbol lookup, and a call graph behind agent-friendly tools.

New installs should use open-codebase-index and open-codebase-index-mcp. The legacy package opencode-codebase-index and opencode-codebase-index-mcp remain supported aliases.

Highlights

• Semantic and hybrid retrieval for questions where you do not know the identifier.
• Low-token discovery through codebase_context and codebase_peek.
• Definition and graph navigation through implementation_lookup, call_graph, and call_graph_path.
• Incremental, branch-aware indexing with file watching and content-hash reuse.
• Local storage backed by SQLite, usearch vectors, and a BM25 inverted index.
• Multiple embedding providers: Ollama, GitHub Copilot, OpenAI, Google, or a custom OpenAI-compatible endpoint.
• Native parsing for TypeScript/TSX, JavaScript/JSX, Python, Rust, Swift, Go, Java, C#, Ruby, C/C++, Metal, PHP, Apex, Bash, Zig, GDScript, MATLAB, JSON, TOML, YAML, Markdown, and HTML, with text fallback.

Quick start with OpenCode

Requires Node.js 20 or newer.

• Install the package:

  npm install open-codebase-index
  

  Legacy installs continue to work with:

  npm install opencode-codebase-index
  

• Add it to opencode.json:

  {
    "plugin": ["open-codebase-index"]
  }
  

  Legacy alias:

  {
    "plugin": ["opencode-codebase-index"]
  }
  

• Run /status, then /index.

• Ask a repository question, for example:

  Where is authentication state validated before an API request?

The first index creates embeddings. Later runs reuse unchanged content and process only relevant changes.

Choose your host

Host	Recommended integration	Storage
OpenCode	Native plugin	.opencode/
Jcode	Per-session MCP server	.codebase-index/
Pi	Pi package	.codebase-index/
Codex	Marketplace plugin with MCP and skill guidance	.codebase-index/
Claude Code	Marketplace plugin with MCP and skill guidance	.claude/
Cursor, Windsurf, other MCP clients	open-codebase-index-mcp (legacy alias: opencode-codebase-index-mcp)	Selected by --host; default is OpenCode-compatible

See Installation and host setup for complete instructions.

Recommended workflow

• Check readiness with index_status or /status.
• Index when needed with index_codebase or /index.
• Start repository discovery with codebase_context.
• Use codebase_peek when you only need likely locations.
• Use implementation_lookup for a known symbol or definition question.
• Use codebase_search when you need full matching source content.
• Use grep for exact identifiers or exhaustive text matches.
• Use call-graph tools for callers, callees, and dependency paths.

Which search tool should I use?

Need	Tool
Route a repository question to a bounded evidence pack	codebase_context
Find likely files and symbols without source bodies	codebase_peek
Retrieve full matching code	codebase_search
Find an authoritative definition	implementation_lookup
Find analogous implementations or duplicates	find_similar
Find direct callers or callees	call_graph
Find a path between two symbols	call_graph_path
Analyze a branch or pull request blast radius	pr_impact

See Tools and commands for host availability, tool details, MCP prompts, and slash commands.

How it works

source files
   │
   ├─ file discovery and git-aware change detection
   ├─ tree-sitter parsing and semantic chunking
   ├─ embedding generation and content-hash reuse
   ▼
SQLite metadata + usearch vectors + BM25 index
   │
   ├─ semantic candidates
   ├─ keyword candidates
   ├─ branch and request filters
   ├─ deterministic fusion and ranking
   ▼
locations, source results, definitions, and call-graph evidence

The TypeScript layer handles host integration, configuration, indexing orchestration, providers, ranking, and tools. The Rust NAPI module handles parsing, vector storage, SQLite operations, BM25 indexing, hashing, and call extraction.

Read Architecture for the detailed data flow and design decisions.

Embedding providers

With embeddingProvider: "auto", providers are tried in this order:

• Ollama
• GitHub Copilot
• OpenAI
• Google

Ollama is the simplest local option:

ollama pull nomic-embed-text

{
  "embeddingProvider": "ollama"
}

A custom OpenAI-compatible embeddings endpoint is also supported. Provider, indexing, search, reranking, include/exclude, knowledge-base, storage, and debug settings are documented in Configuration.

Configuration example

OpenCode project config lives at .opencode/codebase-index.json. Codex, Pi, and Jcode use .codebase-index/config.json; Claude uses .claude/codebase-index.json.

{
  "embeddingProvider": "auto",
  "scope": "project",
  "indexing": {
    "autoIndex": false,
    "watchFiles": true,
    "requireProjectMarker": true,
    "semanticOnly": false
  },
  "search": {
    "maxResults": 20,
    "minScore": 0.1,
    "fusionStrategy": "rrf",
    "rerankTopN": 20
  }
}

Only specify values you want to override. See Configuration for defaults and host-specific paths.

Branch-aware indexing

The index stores reusable content by hash and maintains branch catalogs for chunks and symbols. On a branch switch, unchanged content can be reused while results remain scoped to the active branch. Linked worktrees without a local project config share the main checkout's portable project index; adding a worktree-local config creates an isolated index boundary.

Knowledge bases and reranking

OpenCode and Pi can index additional directories as knowledge bases. Configure them with knowledgeBases or use the host-native knowledge-base tools where available.

Optional external reranking supports Cohere, Jina, and custom compatible endpoints. Local filtering and evidence classes are applied before external candidates are submitted.

See Configuration for examples and privacy considerations.

Troubleshooting

Start with:

• /status or index_status
• index_health_check
• a normal /index retry
• a forced rebuild only when status reports incompatibility or corruption

Common provider, native module, stale index, branch, and performance issues are covered in Troubleshooting.

Evaluation and performance

The repository includes reproducible retrieval datasets, latency and quality budgets, baseline comparison, and cross-repository benchmarking tools.

• Evaluation harness
• Cross-repository benchmarking

Performance depends on repository size, parser coverage, provider latency, embedding cache reuse, and the selected indexing limits. Prefer measured evaluation over fixed marketing claims.

Development

npm ci
npm run build
npm run typecheck
npm run lint
npm run test:run

Native changes require Rust and npm run build:native. See Contributing, Architecture, and Adding language support.

Documentation

• Installation and host setup
• Tools and commands
• Configuration
• Troubleshooting
• Architecture
• Evaluation
• Cross-repository benchmarking
• Adding language support
• Future open-codebase-index rename plan
• Contributing
• Security
• Changelog

License

MIT. See LICENSE.