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 analyzein 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:
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 MCPindexed 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.