umbral: Skill for Claude Code

Exploring Codebases with GitNexus

When to Use

• "How does authentication work?"
• "What's the project structure?"
• "Show me the main components"
• "Where is the database logic?"
• Understanding code you haven't seen before

Workflow

1. READ gitnexus://repos                          → Discover indexed repos
2. READ gitnexus://repo/{name}/context             → Codebase overview, check staleness
3. gitnexus_query({query: "<what you want to understand>"})  → Find related execution flows
4. gitnexus_context({name: "<symbol>"})            → Deep dive on specific symbol
5. READ gitnexus://repo/{name}/process/{name}      → Trace full execution flow

If step 2 says "Index is stale" → run npx gitnexus analyze in terminal.

Checklist

- [ ] READ gitnexus://repo/{name}/context
- [ ] gitnexus_query for the concept you want to understand
- [ ] Review returned processes (execution flows)
- [ ] gitnexus_context on key symbols for callers/callees
- [ ] READ process resource for full execution traces
- [ ] Read source files for implementation details

Resources

Resource	What you get
gitnexus://repo/{name}/context	Stats, staleness warning (~150 tokens)
gitnexus://repo/{name}/clusters	All functional areas with cohesion scores (~300 tokens)
gitnexus://repo/{name}/cluster/{name}	Area members with file paths (~500 tokens)
gitnexus://repo/{name}/process/{name}	Step-by-step execution trace (~200 tokens)

Tools

gitnexus_query — find execution flows related to a concept:

gitnexus_query({query: "payment processing"})
→ Processes: CheckoutFlow, RefundFlow, WebhookHandler
→ Symbols grouped by flow with file locations

gitnexus_context — 360-degree view of a symbol:

gitnexus_context({name: "validateUser"})
→ Incoming calls: loginHandler, apiMiddleware
→ Outgoing calls: checkToken, getUserById
→ Processes: LoginFlow (step 2/5), TokenRefresh (step 1/3)