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 node .gitnexus/run.cjs analyze 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:

cypher

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