assessing-impact

Assessing Impact

Cheap, ad-hoc impact analysis for a single target. Not a graph database — a focused walk over an AST cache plus a complementary text scan, clustered into a report that's easy to summarize.

Use this when you're about to refactor / rename / delete a symbol in a repo you don't work in daily, and you want a single artifact that says: "these N files will need to change, in these M packages, with these tests likely affected."

Don't use this for deep ongoing impact analysis on your own codebase — stand up GitNexus, SourceGraph, or your IDE's index. This skill is for the one-shot case.

Setup

uv venv /home/claude/.venv 2>/dev/null
uv pip install --python /home/claude/.venv/bin/python tree-sitter
export PYTHON=/home/claude/.venv/bin/python
export IMPACT=/mnt/skills/user/assessing-impact/scripts/impact.py

The script depends on the tree-sitting skill — it imports engine.py directly. The bundled grammars live with tree-sitting; no separate language-pack install needed.

Workflow

1. Run the report

$PYTHON $IMPACT /path/to/repo SYMBOL_NAME

Or target a whole file:

$PYTHON $IMPACT /path/to/repo path/to/module.py

2. Read the data, write the summary

The script prints a structured markdown report. Treat it as input for your final summary, not the deliverable. It deliberately doesn't assign a "high/medium/low" risk label — that's your job, after weighing:

• Refs concentrated in one package (low blast) vs. fanned across many (high)
• Test refs present (good — the change has a verification surface) vs. absent
• Doc mentions (renames need to update docs too)
• Caveats listed at the bottom (what the script can't see)

3. Drill if needed

If a particular package looks suspicious, follow up with tree-sitting to read the actual call sites:

TREESIT=/mnt/skills/user/tree-sitting/scripts/treesit.py
$PYTHON $TREESIT /path/to/repo --no-tree 'source:caller_function'

Options

Flag	Default	Purpose
--features PATH	_FEATURES.md	Root _FEATURES.md — when present, refs get clustered by feature in addition to by package.
--skip DIRS	(defaults from tree-sitting)	Extra comma-separated dirs to skip.
--limit-per-name N	500	Cap refs per symbol name. Bump if you suspect truncation.
--json	off	Emit JSON instead of markdown — for downstream tooling.