A local, always-fresh repository knowledge base for AI coding agents.
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myco· Storage: SQLite at.mycelium/index.db· Interfaces: MCP, HTTP, CLI
Mycelium parses your repo with Go/AST and tree-sitter, stores symbols and references in a single SQLite file, and serves that index to Claude Code, Cursor, and any other MCP client. A background daemon keeps the index within a few hundred milliseconds of what's on disk. No external services, no Docker.
See CHANGELOG.md for version history and docs/limitations.md for what doesn't work yet.
# Linux amd64
curl -sSL https://github.com/datata1/mycelium/releases/latest/download/myco-linux-amd64.tar.gz \
| tar -xz -C /opt && sudo ln -sf /opt/myco-linux-amd64/myco /usr/local/bin/myco
# macOS arm64 (Apple Silicon)
curl -sSL https://github.com/datata1/mycelium/releases/latest/download/myco-darwin-arm64.tar.gz \
| tar -xz -C /opt && sudo ln -sf /opt/myco-darwin-arm64/myco /usr/local/bin/mycoSupported platforms: linux/amd64, linux/arm64, darwin/amd64, darwin/arm64, windows/amd64.
Requires Go 1.25+ and a C toolchain (tree-sitter uses cgo).
git clone https://github.com/datata1/mycelium
cd mycelium
task build # → ~/.local/bin/myco
task install # → overwrites whichever myco is on PATHThe sqlite_fts5 build tag is required — it enables FTS5 in the embedded SQLite driver.
cd my-repo
myco init # writes .mycelium.yml, installs post-commit hook
myco daemon & # start the watcher + index server
myco query find AuthService # symbol lookup
myco query refs ParseRequest # callers
myco query neighbors AuthService --direction in --depth 2myco init --mcp claude
# Paste the printed JSON snippet into ~/.claude.json, then restart Claude Code.myco init --mcp cursor
# Paste the printed JSON snippet into ~/.cursor/mcp.json.All tools return JSON; line/col positions are 1-based. Tools marked project? accept an optional workspace project name; tools marked since? accept a git ref and restrict to files changed between <ref>...HEAD; tools marked focus? accept the v2.4 lexical filter.
| Tool | Purpose | Key inputs |
|---|---|---|
find_symbol |
Fuzzy/exact symbol lookup. | name, kind?, limit?, project?, since?, focus? |
get_references |
Callers / importers / type uses; resolved vs textual; fans out through interface implementations. | target, limit?, project?, since? |
read_focused |
File with non-matching symbols collapsed to one-line markers. Empty focus returns the file in full. |
path, focus? |
search_lexical |
Ripgrep-style regex over indexed files. | pattern, path_contains?, k?, project?, since? |
list_files |
Indexed files with language tags. | language?, name_contains?, limit?, project?, since? |
get_file_outline |
Hierarchical symbol tree for one file. | path, focus? |
get_file_summary |
Structural summary (exports, imports, LOC). | path |
get_neighborhood |
Local call graph around a symbol. Walks RefInherit edges so interface consumers fan in. |
target, depth?, direction?, project?, focus? |
impact_analysis |
Transitive inbound closure ranked by distance. For "who's impacted if I change this?" | target, kind?, depth?, project?, since? |
critical_path |
Up to k shortest outbound call paths from from to to. Bounded BFS at depth ≤ 8. |
from, to, depth?, k?, project? |
stats |
Languages, symbol counts, refs, freshness. | — |
find_document_key |
i18n keys, package.json deps, go.mod requires. | key, kind?, project?, limit? |
Edit .mycelium.yml in your repo root (generated by myco init):
version: 1
languages: [go, typescript, python]
include:
- "**/*.go"
- "src/**/*.{ts,tsx}"
- "**/*.py"
exclude:
- "**/node_modules/**"
- "**/vendor/**"
watcher:
debounce_ms: 200
coalesce_ms: 2000
daemon:
socket: .mycelium/daemon.sock
http_port: 7777 # 0 to disable
hooks:
post_commit: true
index:
path: .mycelium/index.db
max_file_size_kb: 1024Monorepos with independent sub-projects register each under one daemon — one SQLite file, one watcher, N logical scopes.
projects:
- name: api
root: services/api
languages: [go]
include: ["**/*.go"]
- name: web
root: services/web
languages: [typescript]
include: ["**/*.ts", "**/*.tsx"]
- name: worker
root: services/worker
languages: [python]
include: ["**/*.py"]Every query tool gains an optional project input that scopes results to one sub-project. Unknown project names return zero hits rather than silently falling back to unscoped.
Pass --since <ref> (CLI) or since (MCP) to restrict any read to files changed between <ref>...HEAD.
myco query files --since main
myco query find Handler --since main
myco query impact MyService --since HEAD~5 --kind methodEnable telemetry in .mycelium.yml:
telemetry:
enabled: trueThen aggregate after a session:
myco stats --telemetrySee docs/adoption.md for the setup checklist and what healthy adoption looks like.
myco init [--mcp claude|cursor]
myco daemon
myco mcp
myco index
myco stats [--telemetry]
myco doctor
myco query find <name> [--kind K] [--limit N] [--project P] [--since REF] [--focus F]
myco query refs <symbol> [--limit N] [--project P] [--since REF]
myco query files [name-contains] [--language L] [--limit N] [--project P] [--since REF]
myco query outline <path> [--focus F]
myco query summary <path>
myco query neighbors <symbol> [--depth N] [--direction out|in|both] [--project P] [--focus F]
myco query impact <symbol> [--kind K] [--depth N] [--project P] [--since REF]
myco query path <from> <to> [--depth N] [--k N] [--project P]
myco query grep <regex> [--path P] [--k N] [--project P] [--since REF]no such module: fts5 — rebuild with the sqlite_fts5 build tag.
Daemon won't start: listen: address already in use — delete .mycelium/daemon.sock and retry.
myco doctor reports issues — run myco doctor for structured diagnostics. See docs/limitations.md for known constraints.
Apache License 2.0 — see LICENSE.