douglasmonsky 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. query({search_query: "<error or symptom>"}) → Find related execution flows
2. context({name: "<suspect>"}) → See callers/callees/processes
3. READ gitnexus://repo/{name}/process/{name} → Trace execution flow
4. cypher({statement: "MATCH path..."}) → Custom traces if needed
If "Index is stale" → run
gitnexus analyze --index-only .in terminal.
Checklist
- [ ] Understand the symptom (error message, unexpected behavior)
- [ ] query for error text or related code
- [ ] Identify the suspect function from returned processes
- [ ] context to see callers and callees
- [ ] Trace execution flow via process resource if applicable
- [ ] cypher for custom call chain traces if needed
- [ ] Read source files to confirm root cause
Debugging Patterns
| Symptom | GitNexus Approach |
|---|---|
| Error message | 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 |
| "How does A reach B?" | trace between the two symbols — shortest call chain in one call |
Tools
query — find code related to error:
query({search_query: "payment validation error"})
→ Processes: CheckoutFlow, ErrorHandling
→ Symbols: validatePayment, handlePaymentError, PaymentException
context — full context for a suspect:
context({name: "validatePayment"})
→ Incoming calls: processCheckout, webhookHandler
→ Outgoing calls: verifyCard, fetchRates (external API!)
→ Processes: CheckoutFlow (step 3/7)
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
trace — shortest call chain between two symbols ("how does A reach B?"), one call instead of chaining context hops:
trace({ from: "processCheckout", to: "fetchRates" })
→ status: ok, hopCount: 3
→ hops: processCheckout → validatePayment → verifyCard → fetchRates
→ edges: CALLS (1.0), CALLS (0.95), CALLS (1.0)
When no path exists, trace reports the furthest reachable node — exactly where the chain breaks (dynamic dispatch, reflection, or an external boundary).
Example: "Payment endpoint returns 500 intermittently"
1. query({search_query: "payment error handling"})
→ Processes: CheckoutFlow, ErrorHandling
→ Symbols: validatePayment, handlePaymentError
2. 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