Spec Kit Baseline Skill

When to Use

• You need a spec for existing or legacy code.
• You want to document a feature before refactoring.
• You inherited a codebase without written requirements.

Inputs

• A target path, file list, or glob pattern describing the code to analyze.
• Repo context with .specify/ scripts and templates.

If the target is missing or ambiguous, ask a focused question before continuing.

Goal

Generate a technology-agnostic spec for existing code, then create the feature branch/spec file using the standard Spec Kit templates.

Workflow

1. Parse target input: Identify files, directories, or patterns to analyze.

   • Accept file paths, glob patterns, or directory paths.
   • If empty: stop and ask for a concrete target.

2. Discover and read source files:

   • Expand globs to a file list.
   • Read file contents for analysis.
   • Identify primary language(s) and frameworks.
   • Map key file relationships and dependencies.

3. Analyze code structure:

   • Identify entry points and public interfaces.
   • Extract function/method signatures and behaviors.
   • Find data models and entities.
   • Detect API endpoints and routes.
   • Identify user-facing functionality.

4. Generate a short name (2-4 words) from the analyzed code:

   • Use action-noun format (e.g., "user-auth", "payment-processing").
   • Base on primary functionality discovered.
   • Preserve technical terms where meaningful.

5. Create the feature branch and spec file:

   • Find the highest existing feature number for this short name (branches/specs).
   • Run .specify/scripts/bash/create-new-feature.sh --json with the calculated number and short name.
   • Read BRANCH_NAME, FEATURE_DIR, and SPEC_FILE paths from the script JSON output.
   • For single quotes in args like "I'm Groot", use escape syntax: e.g 'I'''m Groot' (or double-quote if possible: "I'm Groot").

6. Load the spec template from .specify/templates/spec-template.md.

7. Draft the specification using the template structure:

   • User Stories: Infer from user-facing code paths and interactions.
   • Acceptance Scenarios: Derive from validation logic, error handling, and tests.
   • Functional Requirements: Extract from business rules and constraints.
   • Key Entities: Identify from data models and schemas.
   • Success Criteria: Infer from metrics, logging, or performance-related code.
   • Assumptions: Document inferences made during analysis.

8. Abstract implementation details:

   • Convert technical patterns to user-focused requirements.
   • Remove framework-specific terminology.
   • Focus on WHAT the code does, not HOW it does it.

9. Create spec quality checklist at FEATURE_DIR/checklists/requirements.md.

10. Report completion with:

    • Branch name and spec file path.
    • Summary of analyzed files.
    • Key features discovered.
    • Areas needing clarification or review.

Outputs

• specs/<feature>/spec.md
• specs/<feature>/checklists/requirements.md

Key rules

• Focus on extracting WHAT and WHY from HOW.
• Abstract away implementation details in the generated spec.
• Document assumptions made during code analysis.
• Flag areas where code behavior is unclear.
• Preserve discovered business rules and constraints.
• Use [NEEDS CLARIFICATION] for ambiguous code sections (max 3).
• Generated specs should be validated by someone who knows the feature.

Examples

Code Pattern → Spec Requirement:

• if (user.role === 'admin') → "System MUST restrict action to administrator users"
• password.length >= 8 → "Passwords MUST be at least 8 characters"
• cache.set(key, value, 3600) → "System MUST cache results for improved performance"
• try { ... } catch (e) { notify(e) } → "System MUST notify users when errors occur"

Code Pattern → User Story:

• Login endpoint with OAuth → "As a user, I can sign in using my social account"
• Shopping cart logic → "As a customer, I can add items to my cart for later purchase"
• Report generation → "As an analyst, I can generate reports on system activity"

Next Steps

After generating spec.md:

• Clarify with domain experts using speckit-clarify.
• Plan modernization/refactoring with speckit-plan.
• Compare the generated spec with actual requirements to identify gaps.