// Use when the user wants to review a pull request, understand what a PR changes, assess risk of merging, or check for missing test coverage. Examples: "Review this PR", "What does PR #42 change?", "Is this PR safe to merge?"
Use when the user needs to run GitNexus CLI commands like analyze/index a repo, check status, clean the index, generate a wiki, or list indexed repos. Examples: "Index this repo", "Reanalyze the codebase", "Generate a wiki"
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"
Use when the user asks how code works, wants to understand architecture, trace execution flows, or explore unfamiliar parts of the codebase. Examples: "How does X work?", "What calls this function?", "Show me the auth flow"
Use when the user asks about GitNexus itself — available tools, how to query the knowledge graph, MCP resources, graph schema, or workflow reference. Examples: "What GitNexus tools are available?", "How do I use GitNexus?"
Use when the user wants to know what will break if they change something, or needs safety analysis before editing code. Examples: "Is it safe to change X?", "What depends on this?", "What will break?"
Use when the user wants to rename, extract, split, move, or restructure code safely. Examples: "Rename this function", "Extract this into a module", "Refactor this class", "Move this to a separate file"
| name | gitnexus-pr-review |
| description | Use when the user wants to review a pull request, understand what a PR changes, assess risk of merging, or check for missing test coverage. Examples: "Review this PR", "What does PR #42 change?", "Is this PR safe to merge?" |
1. gh pr diff <number> → Get the raw diff
2. gitnexus_detect_changes({scope: "compare", base_ref: "main"}) → Map diff to affected flows
3. For each changed symbol:
gitnexus_impact({target: "<symbol>", direction: "upstream"}) → Blast radius per change
4. gitnexus_context({name: "<key symbol>"}) → Understand callers/callees
5. READ gitnexus://repo/{name}/processes → Check affected execution flows
6. Summarize findings with risk assessment
If "Index is stale" → run
npx gitnexus analyzein terminal before reviewing.
- [ ] Fetch PR diff (gh pr diff or git diff base...head)
- [ ] gitnexus_detect_changes to map changes to affected execution flows
- [ ] gitnexus_impact on each non-trivial changed symbol
- [ ] Review d=1 items (WILL BREAK) — are callers updated?
- [ ] gitnexus_context on key changed symbols to understand full picture
- [ ] Check if affected processes have test coverage
- [ ] Assess overall risk level
- [ ] Write review summary with findings
| Dimension | How GitNexus Helps |
|---|---|
| Correctness | context shows callers — are they all compatible with the change? |
| Blast radius | impact shows d=1/d=2/d=3 dependents — anything missed? |
| Completeness | detect_changes shows all affected flows — are they all handled? |
| Test coverage | impact({includeTests: true}) shows which tests touch changed code |
| Breaking changes | d=1 upstream items that aren't updated in the PR = potential breakage |
| Signal | Risk |
|---|---|
| Changes touch <3 symbols, 0-1 processes | LOW |
| Changes touch 3-10 symbols, 2-5 processes | MEDIUM |
| Changes touch >10 symbols or many processes | HIGH |
| Changes touch auth, payments, or data integrity code | CRITICAL |
| d=1 callers exist outside the PR diff | Potential breakage — flag it |
gitnexus_detect_changes — map PR diff to affected execution flows:
gitnexus_detect_changes({scope: "compare", base_ref: "main"})
→ Changed: 8 symbols in 4 files
→ Affected processes: CheckoutFlow, RefundFlow, WebhookHandler
→ Risk: MEDIUM
gitnexus_impact — blast radius per changed symbol:
gitnexus_impact({target: "validatePayment", direction: "upstream"})
→ d=1 (WILL BREAK):
- processCheckout (src/checkout.ts:42) [CALLS, 100%]
- webhookHandler (src/webhooks.ts:15) [CALLS, 100%]
→ d=2 (LIKELY AFFECTED):
- checkoutRouter (src/routes/checkout.ts:22) [CALLS, 95%]
gitnexus_impact with tests — check test coverage:
gitnexus_impact({target: "validatePayment", direction: "upstream", includeTests: true})
→ Tests that cover this symbol:
- validatePayment.test.ts [direct]
- checkout.integration.test.ts [via processCheckout]
gitnexus_context — understand a changed symbol's role:
gitnexus_context({name: "validatePayment"})
→ Incoming calls: processCheckout, webhookHandler
→ Outgoing calls: verifyCard, fetchRates
→ Processes: CheckoutFlow (step 3/7), RefundFlow (step 1/5)
1. gh pr diff 42 > /tmp/pr42.diff
→ 4 files changed: payments.ts, checkout.ts, types.ts, utils.ts
2. gitnexus_detect_changes({scope: "compare", base_ref: "main"})
→ Changed symbols: validatePayment, PaymentInput, formatAmount
→ Affected processes: CheckoutFlow, RefundFlow
→ Risk: MEDIUM
3. gitnexus_impact({target: "validatePayment", direction: "upstream"})
→ d=1: processCheckout, webhookHandler (WILL BREAK)
→ webhookHandler is NOT in the PR diff — potential breakage!
4. gitnexus_impact({target: "PaymentInput", direction: "upstream"})
→ d=1: validatePayment (in PR), createPayment (NOT in PR)
→ createPayment uses the old PaymentInput shape — breaking change!
5. gitnexus_context({name: "formatAmount"})
→ Called by 12 functions — but change is backwards-compatible (added optional param)
6. Review summary:
- MEDIUM risk — 3 changed symbols affect 2 execution flows
- BUG: webhookHandler calls validatePayment but isn't updated for new signature
- BUG: createPayment depends on PaymentInput type which changed
- OK: formatAmount change is backwards-compatible
- Tests: checkout.test.ts covers processCheckout path, but no webhook test
Structure your review as:
## PR Review: <title>
**Risk: LOW / MEDIUM / HIGH / CRITICAL**
### Changes Summary
- <N> symbols changed across <M> files
- <P> execution flows affected
### Findings
1. **[severity]** Description of finding
- Evidence from GitNexus tools
- Affected callers/flows
### Missing Coverage
- Callers not updated in PR: ...
- Untested flows: ...
### Recommendation
APPROVE / REQUEST CHANGES / NEEDS DISCUSSION