Impact Analysis

impact-analysis

> Perform cross-package impact analysis for a type, function, or constant in a TypeScript monorepo, tracing all consumers and property accesses.

Step 1: Parse arguments

Extract the symbol name from $ARGUMENTS.

Supported flags:

• --property — highlight accesses to a specific property and include breaking change analysis

Examples:

• MyInterface — analyze all consumers of MyInterface
• MyInterface --property oldName — analyze consumers and highlight accesses to .oldName

If no symbol name is provided, ask the user which symbol to analyze.

Step 2: Find the definition

Search for the symbol definition across the monorepo:

# Search for type/interface/class/function/const declarations
grep -rn "export\s\+\(type\|interface\|class\|function\|const\|enum\)\s\+" --include="*.ts" --include="*.tsx"

Use Grep to locate all matching declarations. For each candidate:

1. Read the file to confirm it is the primary definition (not a re-export).
2. Identify the package by finding the nearest package.json ancestor.
3. Record the definition shape — list its properties, methods, parameters, or members so you can match them against consumer usage in later steps.

Important:

• If the symbol is defined in multiple packages, ask the user which definition to trace.
• If no definition is found, broaden the search to include non-exported declarations and type aliases.

Step 3: Trace imports

Search for all imports of the symbol across the entire monorepo:

# Direct named imports
grep -rn "import.*{[^}]*[^}]*}" --include="*.ts" --include="*.tsx"

# Re-exports
grep -rn "export.*{[^}]*[^}]*}" --include="*.ts" --include="*.tsx"
grep -rn "export.*from" --include="*.ts" --include="*.tsx" | grep ""

Use Grep to find all import and re-export statements. For each match:

1. Classify the import type:

• Direct import — imports the symbol from the defining package
• Re-export — re-exports the symbol through a barrel file (index.ts) or intermediate package
• Barrel import — imports the symbol from a barrel file that re-exports it

1. Track the import chain — if the symbol is re-exported through intermediate packages, trace the full chain from definition to final consumer. This ensures you do not miss indirect consumers who import from a barrel or wrapper package.

1. Record each consumer file with its package name and import path.

Step 4: Analyze property accesses

For each consumer file identified in Step 3:

1. Read the relevant code around each import and usage site.
2. Identify how the symbol is used:

• Property accesses (e.g., obj.prop, Type['prop'])
• Method calls (e.g., obj.method())
• Construction (e.g., new ClassName())
• Type annotations (e.g., param: MyInterface)
• Spread or destructuring (e.g., { prop1, prop2 } = obj)
• Generic type parameters (e.g., SomeType)

1. If --property flag was provided, specifically search for accesses to that property:

``bash # Property access patterns grep -n "\." grep -n "\[''\]" grep -n ":" ``

1. Record the accessed properties/methods for each consumer file.

Step 5: Group and report

Present results grouped by package using the following format:

## Impact Analysis: 

### Definition
- **Package:** 
- **File:** :
- **Kind:** type | interface | class | function | const | enum
- **Shape:** 

### Consumers (N files across M packages)

####  (N files)
- `` — accesses: `.prop1`, `.prop2`
- `` — constructs ``
- `` — type annotation only

####  (N files)
- `` — accesses: `.prop1`, `.method()`
- `` — destructures: `{ prop1, prop2 }`

### Re-export Chain
 ->  -> 

Important:

• Sort packages alphabetically.
• Within each package, sort files alphabetically.
• If a consumer only uses the symbol as a type annotation (no property access), note "type annotation only".
• If no consumers are found, report that explicitly.

Step 6: Breaking change analysis

Only perform this step if --property was specified.

Compile a focused report on the impact of renaming or removing the specified property:

### Breaking Change Analysis: `.`

**Affected locations (N files across M packages):**

| Package | File | Line | Usage |
|---------|------|------|-------|
|  | `` |  | `obj.` |
|  | `` |  | `{  } = obj` |

**Migration approach:**
1. Update the definition in ``
2. Update re-exports if the property is part of a mapped type
3. Update each consumer file listed above
4. Run `npx tsc --noEmit` to verify no remaining type errors

If the number of affected locations is large (20+), suggest using a codemod or find-and-replace strategy instead of manual updates.

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: tada5hi
• Source: tada5hi/skills
• License: Apache-2.0

Install and usage instructions live in the source repository linked above.