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Assessing Impact

Generates a pre-change blast-radius report showing what breaks if you rename, refactor, or delete a symbol or file.

Dev & CodingIntermediate★ 148⑂ 5AI score 9/10Last updated: Sep 12, 2026

What it does

  • Resolves a target symbol (e.g. validateUser) or file path and walks all references across the repo.
  • Combines tree-sitter AST reference walking with a plain-text scan over non-parsed files (configs, docs) to reduce blind spots.
  • Clusters findings by package, test files, documentation mentions, and feature (when a _FEATURES.md exists), emitting Markdown or JSON.
  • Suggests likely regression test surfaces and lists explicit caveats about what the scan cannot see.
  • Deliberately withholds a high/medium/low risk label so Claude weighs the evidence and writes the judgement.

Who it's for

  • Developers refactoring, renaming, or deleting code in a repo they don't work in daily.
  • Open-source contributors or maintainers of inherited legacy code asking "is this safe to remove?"
  • Anyone who wants one-shot impact analysis without standing up SourceGraph, GitNexus, or a full IDE index.

Example uses

  1. Before a rename: $PYTHON $IMPACT ./repo validateUser to see how many packages and tests are touched.
  2. Target a whole module — $PYTHON $IMPACT ./repo path/to/module.py — to confirm no stragglers import it before deletion.
  3. Run after exploring-codebases so the report clusters the blast radius by product feature ("billing", "auth") instead of raw directories.

· · · Install guide · · ·

Try it now, no install

Paste this into Claude to use the skill without installing anything.

Read the instructions in this file and follow them to help me:
https://raw.githubusercontent.com/oaustegard/claude-skills/HEAD/assessing-impact/SKILL.md

What I want: (describe your task here)

If Claude can't open the link, open it yourself and paste the contents instead.

↓ If it works for you, download the ZIP below and install it. Then it runs on its own — no pasting each time.

Install in the Claude app (no terminal)
  1. Download the ZIP with the button below.
  2. In Claude, open Settings → Capabilities and turn on 'Code execution and file creation'. (one time)
  3. Go to Customize → Skills → + → 'Upload a skill' and upload the ZIP.
↓ Download ZIP
Install in Claude Code

Let Claude do it — paste this into Claude Code

Install the skill I found on Claude Skill Mart.
Copy the assessing-impact folder from the GitHub repo oaustegard/claude-skills into my ~/.claude/skills/assessing-impact/.
When it's done, tell me in one line what this skill can do.

Install with a command instead

git clone https://github.com/oaustegard/claude-skills.git /tmp/claude-skills && cp -r /tmp/claude-skills/assessing-impact /tmp/claude-skills/tree-sitting ~/.claude/skills/

⚠ This is a third-party skill. Check the source repository before installing.

  1. Clone the repo: git clone https://github.com/oaustegard/claude-skills.git
  2. Create the skills directory if needed: mkdir -p ~/.claude/skills
  3. Copy this skill and its required companion tree-sitting: cp -r claude-skills/assessing-impact claude-skills/tree-sitting ~/.claude/skills/
  4. Set up Python deps: uv venv ~/.venv && uv pip install --python ~/.venv/bin/python tree-sitter
  5. Adjust the /mnt/skills/user/... paths in SKILL.md to your real install path (~/.claude/skills/...) when exporting $IMPACT and $PYTHON.
  6. Restart Claude Code and ask something like "what breaks if I change this function?" to trigger the skill.
View source on GitHub ↗License: MIT