Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/haabe/mycelium/setupnpx skills add haabe/mycelium --skill setupgit clone --depth 1 https://github.com/haabe/myceliumWhat it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00101 | $0.04389 |
| Opus 5 | $0.00051 | $0.02194 |
| Sonnet 5 | $0.00020 | $0.00878 |
| Haiku 4.5 | $0.00010 | $0.00439 |
Grade A, and why
setup scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 313 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Mycelium plugin setup
When this skill runs, do the following sequence. The skill is designed to be safe to re-run — every step is idempotent.
Step 1: Detect initialization state
Check whether the user's project already has Mycelium project-state. The signal that initialization has happened:
test -f "$CLAUDE_PROJECT_DIR/.claude/diamonds/active.yml"
If the file exists, print:
"Mycelium project state is already initialized. Existing canvas, diamonds, and memory are preserved. Run
/mycelium:diamond-assessto see current state."
Then exit. Do NOT touch existing files.
If the file does NOT exist, continue to Step 2.
Step 2: Create project-state directory structure
Resolve the project root: use $CLAUDE_PROJECT_DIR if set, else fall back to pwd. (Claude Code sets it automatically; non-Claude-Code agents may not.)
Create these directories in the user's project (using Bash mkdir -p):
<project_root>/.claude/canvas/
<project_root>/.claude/diamonds/
<project_root>/.claude/memory/
<project_root>/.claude/harness/
<project_root>/.claude/evals/
<project_root>/.claude/jit-tooling/
These directories hold project-specific state that the user's project owns and commits to git. Framework reference content (skills, hooks, theory gates) lives in the plugin cache and is not duplicated here.
A .claude/state/ directory may also be present — that one is created and owned by Claude Code itself for runtime state (audit logs, etc.), not by Mycelium. Mycelium does not write to it; if you see it, it's expected.
Important — empty dirs and git: directories that don't get a starter file in Step 3 (canvas/, evals/, jit-tooling/) are empty after Step 2 and would not survive a git commit. Drop a .gitkeep stub in each so they remain in the user's repo:
touch <project_root>/.claude/canvas/.gitkeep
touch <project_root>/.claude/evals/.gitkeep
touch <project_root>/.claude/jit-tooling/.gitkeep
Step 3: Write minimal starter files
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 2d ago First seen · 313 lines · 101 tokens per session scan A 3a608299120f
setup is a skill published in the GitHub repository haabe/mycelium (45 stars, last pushed 2d ago), licensed MIT. It adds 101 tokens to every session and 4,389 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
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