brownfield-blast

/brownfield-blast — Blast Radius Report

Purpose

Generate a detailed blast radius report showing all files affected if you change a given file.

Trigger

• "Show me the blast radius of this file"
• "What happens if I change X?"
• "Who depends on this module?"

Type: /brownfield-blast <file-path>

---

Steps

1. Resolve the target file

If $ARGUMENTS is empty, use the currently open file. Resolve relative paths to project root. Verify the file exists in the graph.

2. Load blast radius from DB

const queries = require('./.claude/query-helpers.js');
const blastData = queries.getBlastRadius(targetFilePath);

Returns:

• count (total transitive dependents)
• direct (files that directly import this)
• transitive (all affected files at all depths)
• files (array with distances/hops)
• crossLang (cross-language dependencies)

3. Load file summary for context

const summary = queries.getFileSummary(targetFilePath);

Provides:

• summary (1-line module purpose)
• primaryRole (Util, Logic, Infra, etc.)
• importedByCount (fan-in)
• riskScore, band
• dangerReason

4. Build the report

Format:

# Blast Radius — <file-path>

## File Summary
[Summary from dep-graph]

**Role:** <role>  
**Risk Score:** <score>/100  
**Bug Fixes:** <count>  

---

## Direct Dependents
<N> files directly import this:
- <file 1>
- <file 2>
- ...

---

## Transitive Dependents
<N> files would be affected if this changes:
- <file 1> (distance: 1 hop)
- <file 2> (distance: 1 hop)
- <file 3> (distance: 2 hops)
- ...
[Show up to 20; note if more exist]

---

## Cross-Language Hits
[If any]
- <swift file> imports this JS file (iOS build may break)
- <go file> depends on exported JSON schema

---

## Recommended Action

[If transitive dependents < 5]
✓ Safe to change. Low blast radius. Run tests in dependent files.

[If transitive dependents 5-20]
⚠ Moderate impact. Affects <N> files. Ensure tests pass for:
  • <top 3 dependent files>

[If transitive dependents > 20]
🛑 CRITICAL impact. <N> files depend on this.
Before changing:
  1. Ensure changes are backwards compatible
  2. Update all dependent imports
  3. Run full test suite
  4. Notify team (@owner)