| name | codebase-research |
| description | Codebase exploration and architecture analysis. Read files, trace data flow, identify modification points, map dependencies, find reusable code, evaluate design patterns. |
Codebase Research
Systematically explore and analyze a codebase to understand its architecture, trace data flow, and identify how to make changes safely.
Analysis Process
Follow these steps in order. Do not skip steps or propose changes to code you have not read.
1. Read Referenced Files
- Read every file that is directly relevant to the task
- Understand the current architecture before proposing changes
- Read imports and dependencies to understand the module graph
- Check for configuration files that affect behavior (tsconfig, eslint, webpack, etc.)
2. Trace Data Flow
- Follow the path from entry point to output for the affected feature
- Identify every transformation the data undergoes
- Map inputs, intermediate states, and outputs
- Note where data crosses boundaries (API calls, database queries, message queues)
3. Identify Modification Points
- Determine which files, functions, and interfaces need changes
- Note the exact lines where modifications are required
- Identify any type definitions, schemas, or contracts that must be updated
- Check for generated code that may need regeneration
4. Map Dependencies
- Identify what depends on the code being changed (downstream consumers)
- Identify what the code being changed depends on (upstream providers)
- Determine the safe modification order to avoid breaking intermediate states
- Flag any circular dependencies
5. Check for Reusable Code
- Search for existing utilities, helpers, or patterns that apply to the task
- Check shared libraries and common modules
- Look for similar implementations elsewhere in the codebase that can be referenced
- Prefer reusing existing code over creating new abstractions
6. Evaluate Design Patterns
- Match the codebase's existing patterns -- do not introduce new architectural patterns without reason
- Check naming conventions, file organization, and code style
- Identify any patterns that are partially implemented and should be completed
- Note anti-patterns that should not be propagated
Output Format
## Architecture Analysis
### Files to Create
- `path/to/file.ts` -- purpose
### Files to Modify
- `path/to/file.ts:L42-L68` -- what changes and why
### Dependency Graph
- [file A] -> [file B] -> [file C] (modification order)
### Design Decisions
| Decision | Choice | Rationale |
|----------|--------|-----------|
### Reusable Code
- `path/to/util.ts:functionName` -- how it applies
### Risks
- [risk description] -- [mitigation]
Rules
- Always read files before recommending changes to them
- Follow existing patterns in the codebase -- do not introduce new architectural patterns unless explicitly required
- Include file:line references for all recommendations
- Flag breaking changes explicitly
- Keep the modification surface area as small as possible
