# Gitnexus Debugging

> Use when the user is debugging a bug, tracing an error, or asking why something fails. Examples: "Why is X failing?", "Where does this error come from?", "Trace this bug"

- Skill: `bbrysonelite-max/gitnexus-debugging` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add bbrysonelite-max/gitnexus-debugging`
- Raw SKILL.md: https://api.skillmd.com/api/skills/bbrysonelite-max/gitnexus-debugging/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: bbrysonelite-max (https://skillmd.com/u/bbrysonelite-max)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/bbrysonelite-max/gitnexus-debugging

---


# Debugging with GitNexus

## When to Use

- "Why is this function failing?"
- "Trace where this error comes from"
- "Who calls this method?"
- "This endpoint returns 500"
- Investigating bugs, errors, or unexpected behavior

## Workflow

```
1. gitnexus_query({query: "<error or symptom>"})            → Find related execution flows
2. gitnexus_context({name: "<suspect>"})                    → See callers/callees/processes
3. READ gitnexus://repo/{name}/process/{name}                → Trace execution flow
4. gitnexus_cypher({query: "MATCH path..."})                 → Custom traces if needed
```

> If "Index is stale" → run `npx gitnexus analyze` in terminal.

## Checklist

```
- [ ] Understand the symptom (error message, unexpected behavior)
- [ ] gitnexus_query for error text or related code
- [ ] Identify the suspect function from returned processes
- [ ] gitnexus_context to see callers and callees
- [ ] Trace execution flow via process resource if applicable
- [ ] gitnexus_cypher for custom call chain traces if needed
- [ ] Read source files to confirm root cause
```

## Debugging Patterns

| Symptom              | GitNexus Approach                                          |
| -------------------- | ---------------------------------------------------------- |
| Error message        | `gitnexus_query` for error text → `context` on throw sites |
| Wrong return value   | `context` on the function → trace callees for data flow    |
| Intermittent failure | `context` → look for external calls, async deps            |
| Performance issue    | `context` → find symbols with many callers (hot paths)     |
| Recent regression    | `detect_changes` to see what your changes affect           |

## Tools

**gitnexus_query** — find code related to error:

```
gitnexus_query({query: "payment validation error"})
→ Processes: CheckoutFlow, ErrorHandling
→ Symbols: validatePayment, handlePaymentError, PaymentException
```

**gitnexus_context** — full context for a suspect:

```
gitnexus_context({name: "validatePayment"})
→ Incoming calls: processCheckout, webhookHandler
→ Outgoing calls: verifyCard, fetchRates (external API!)
→ Processes: CheckoutFlow (step 3/7)
```

**gitnexus_cypher** — custom call chain traces:

```cypher
MATCH path = (a)-[:CodeRelation {type: 'CALLS'}*1..2]->(b:Function {name: "validatePayment"})
RETURN [n IN nodes(path) | n.name] AS chain
```

## Example: "Payment endpoint returns 500 intermittently"

```
1. gitnexus_query({query: "payment error handling"})
   → Processes: CheckoutFlow, ErrorHandling
   → Symbols: validatePayment, handlePaymentError

2. gitnexus_context({name: "validatePayment"})
   → Outgoing calls: verifyCard, fetchRates (external API!)

3. READ gitnexus://repo/my-app/process/CheckoutFlow
   → Step 3: validatePayment → calls fetchRates (external)

4. Root cause: fetchRates calls external API without proper timeout
```

## Codex Runtime

Keep GitNexus as the external product name. Use actual GitNexus MCP tools and resources when available; otherwise preflight the CLI through `npx gitnexus`.

Never expose or print secret, credential, or token values.

Mandatory dependencies:
- `GitNexus CLI or MCP`
- `indexed Git repository`

Preflight each dependency using MCP/app capability discovery, CLI availability/version checks, read-only filesystem or Git checks for repositories, and provider auth-status commands without printing secrets, credentials, or tokens.
If any mandatory dependency is unavailable, stop and report a concise blocked state naming the missing dependency and the next action needed.