🍄 Mycelium

The wood-wide-web of your codebase.

A reactive, AI-native code intelligence graph. Your AI agent perceives your code like a nervous system perceives a body — every change, instantly felt, instantly understood.

Charter · GitFlow · Contributing · Governance · RFCs · Sponsors

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Why Mycelium

In a forest, trees do not communicate through their leaves. They communicate underground through mycelium — a fungal network that exchanges signals, nutrients, and warnings across the entire ecosystem. Scientists call it the Wood Wide Web.

Your codebase is a forest. Today, AI agents read it leaf by leaf — grep, find, read, repeat. They burn tokens, miss connections, and forget everything between sessions.

Mycelium is the network that lives beneath your code. It is:

• Reactive — every edit propagates through the graph in milliseconds. No reindex. No staleness.
• AI-native — query results are serialized in a compact symbolic DSL, not JSON. AI gets 3–4× more meaning per token.
• Polyglot — 20+ languages on day one, hundreds within reach. Adding a new language touches ≤3 files. No core changes.
• Local, embeddable, fast — a single Rust binary. Sub-millisecond multi-hop queries. No server, no cloud.

Status

v0.2.0 — Alpha. All Charter §2 performance SLAs satisfied. Heavy-graph algorithms complete in < 2 s on 1K-node graphs.

Component	Status
Core engine (Trunk + Synapse + Cortex)	✅ Shipped
Language packs: Python, TS, JS, Rust, Go	✅ Tier 1 complete
Language packs: Java, C, C++, C#, Ruby	✅ Tier 2 complete
MCP server (93 tools)	✅ Shipped
Hyphae DSL (lexer + parser + evaluator)	✅ RFC-0004 complete
CLI (mycelium index, mycelium serve --mcp)	✅ Shipped
Persistence (MessagePack snapshot)	✅ Shipped
Watch mode (reactive FSE re-index)	✅ Shipped
npm / bun CLI install (no cargo)	✅ v0.2.0 (RFC-0110)
PyPI bindings	🔜 future

Public roadmap: GitHub Projects. Changelog: CHANGELOG.md. Charter: CHARTER.md — read this before any contribution.

Design Pillars

Pillar	What it means
Trunk	Containment as a Materialized Path Radix Trie. Ancestor and descendant queries are string operations, not graph walks.
Synapse	Cross-cutting relationships (calls, extends, implements, the full UML set) as CSR-encoded adjacency lists, indexed per edge kind.
Hyphae	A CSS-selector-inspired query language with edge pseudo-classes. class.AuthService > method:async:calls(UserRepo > method).
Reactive Layer	Salsa-style dependency tracking. File changes invalidate only the affected query subscriptions, not the whole graph.
AI Serialization	Emmet-like compact DSL output. ~70% fewer tokens than JSON for the same information.
Batch API	Multi-step query plans in a single MCP call. Computation pushed down, AI round-trips cut 5–20× to 1–3×.

Three Faces, One Engine

Mycelium ships as a single Rust binary exposing three faces, sharing one core:

┌─────────────────────────────────────────┐
│      mycelium-core (Rust crate)         │  ← the engine
└────────────────┬────────────────────────┘
                 │
   ┌─────────────┼─────────────┐
   ▼             ▼             ▼
 CLI          MCP Server     Claude Skill
 mycelium     mycelium       SKILL.md + bin
 query …      serve --mcp    + auto-config

Install once. Use from terminal, from your AI agent, or as a skill bundle.

Quick Start

Install

Have Rust? Install from crates.io (the mycelium-rcig-* prefix is because the short names mycelium-core/mycelium-cli were taken by unrelated 2019/2025 projects):

cargo install mycelium-rcig-cli

# Or install latest from source:
cargo install --git https://github.com/aimasteracc/mycelium mycelium-rcig-cli

No Rust toolchain? Install the prebuilt binary with npm or bun (RFC-0110) — no cargo required:

npm install -g @aimasteracc/mycelium     # npm
bun  add     -g @aimasteracc/mycelium     # bun
bunx @aimasteracc/mycelium --version      # or run without installing

Use

# Index a project (Python, TS, JS, Rust, Go, Java, C, C++, C#, Ruby)
mycelium index ./my-project

# Serve as MCP for your AI agent (Claude, GPT-4, etc.)
mycelium serve --mcp --root ./my-project

Hyphae DSL — query the graph like CSS selects DOM

# via mycelium_query MCP tool:
# Find all functions that call AuthService
{ "query": "function:calls(#AuthService)" }

# Find all methods inside Foo class
{ "query": "#Foo > method" }

# Find callers of login, up to depth 3
{ "query": "*:callers(#login)" }

Performance SLA (the bar we ship against)

Metric	Target	Compared to
Cold small query	< 5 ms	SQLite-based code graphs ≈ 50 ms
3-hop traversal	< 1 ms	Neo4j ≈ 10–30 ms
Reactive re-query after file change	< 10 ms	Full reindex on most tools
AI token efficiency	25–30% of JSON	—
New language onboarding	≤ 3 files, 0 core changes	codegraph-style: 5–10 files + core

CI gates regressions on these numbers. If a release does not meet them, it does not ship.

The Hive — Our Autonomous Development Team

Mycelium is developed by a team of AI agents under a single human founder. The team is defined in .hive/:

Agent	Role
PM	Roadmap, prioritization, daily standup
Architect	RFC review, ADRs
Spec Author	Drafts RFCs from issues
Test Author	TDD — tests precede implementation
Rust Implementer	Engine and CLI code
Pack Author	New language packs
Reviewer	PR review, lint, style, security
Doc Sync	Docs ↔ code consistency
Bench	Performance regression detection
Security	Vulnerabilities, dependencies, secrets
Release	Versioning, changelog, publishing
Triage	Issue labeling, duplicate detection

The Hive shares persistent memory (.hive/memory/) so lessons learned and decisions made stay across sessions. See .hive/_orchestrator.md for the protocol.

Contributing

Pull requests are welcome but must target develop, never main. Large changes go through the RFC process first.

Start here: CONTRIBUTING.md · GITFLOW.md · GOVERNANCE.md

We use DCO (Developer Certificate of Origin), not a CLA. Add Signed-off-by: to every commit and you are good.

Sponsorship

Mycelium is MIT-licensed and developed by a small team backed by Anthropic's Claude. If it saves your AI agent tokens, your engineers time, or your team frustration, please consider sponsoring. See SPONSORS.md for the current honor roll.

License

MIT © aimasteracc and the Mycelium contributors.

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_{Built with 🍄 by humans and AI, together.
"Every neuron that fires, every leaf that trembles, every line of code that changes — all felt instantly."}