impact

Reverse dependency analysis: what depends on a given file or symbol.

Usage

prx impact [options] <file>

Options

Flag	Description
`--symbol <name>`	Narrow to a specific exported symbol
`--hops N`	Limit traversal depth (default: all reachable)
`--budget N`	Cap output at N tokens
`--plain`	Human-readable output

What it returns

Target exports — what the file exports
Dependent files — files that import the target, with hop distance
Symbol attribution — which symbols each dependent uses
Stats — direct count, transitive count, test file count

Examples

# What depends on this file?
prx impact src/auth/handler.ts

# What uses this specific function?
prx impact src/auth/handler.ts --symbol authenticate

# Direct dependents only (1 hop)
prx impact src/auth/handler.ts --hops 1

Example output:

{
  "data": {
    "target": "src/auth/handler.ts",
    "exports": ["handleLogin", "handleLogout", "authenticate"],
    "dependents": [
      {
        "file": "src/routes/api.ts",
        "hops": 1,
        "symbols_used": ["handleLogin", "authenticate"]
      },
      {
        "file": "src/middleware/auth.ts",
        "hops": 1,
        "symbols_used": ["authenticate"]
      },
      {
        "file": "src/tests/auth.test.ts",
        "hops": 1,
        "symbols_used": ["handleLogin", "handleLogout"]
      }
    ],
    "stats": {
      "direct": 3,
      "transitive": 7,
      "test_files": 1
    }
  }
}

How it works

prx impact does a reverse walk of the import graph built by prx index. Import edges are extracted from the AST using tree-sitter across 10 language families.

When an import name is ambiguous across many files, resolution falls back to a directory-proximity heuristic and returns the most likely candidates. Treat the output as a high-quality map, not a formal proof of completeness.

Tips

Run prx impact before any refactor that touches a shared file. It tells you the blast radius before you make the change.
Use --symbol to narrow the analysis when you’re only changing one export. A file might have 10 dependents, but only 2 of them use the symbol you’re changing.
Use --hops 1 for a quick check of direct dependents. The transitive closure can be large on central files.
The test_files count in stats tells you how many test files will need updating.
Run prx index . first to build the import graph. Without an index, impact analysis falls back to a slower on-demand extraction.

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