Source-Driven Development

Source-Driven Development

Version: 1.0.0 Last Updated: 2026-05-12

Overview

Source-driven development ensures that framework-specific code is written against current official documentation, not stale training data. AI models often generate code using deprecated APIs, wrong parameter orders, or patterns from older versions. This skill enforces a verification loop:

Detect version → Fetch current docs → Write code with citations → Surface conflicts

This skill leverages the Context7 MCP server (if available) to fetch version-specific documentation at build time.

When to Use

• /temper:build or /temper:fix writing framework-specific code (React, Spring Boot, Express, FastAPI, etc.)
• Adding or updating a dependency
• Writing code that uses a library API you haven't used recently
• Whenever the agent says "I believe the API works like..."

Skip when:

• Writing plain logic (no framework dependency)
• Writing tests for code you just read (you already have the source)
• Modifying config files with known structure

Process

Step 1: Read Manifest

Detect the project's dependencies and versions:

1. JavaScript/TypeScript: Read package.json — extract dependencies and devDependencies
2. Java: Read pom.xml or build.gradle — extract dependency versions
3. Python: Read pyproject.toml or requirements.txt — extract pinned versions
4. Go: Read go.mod — extract module versions
5. Rust: Read Cargo.toml — extract dependency versions

For the specific library you're about to use, note the exact version installed.

Step 2: Fetch Current Documentation

If the Context7 MCP server is available:

1. Resolve the library ID: mcp__plugin_context7_context7__resolve-library-id with the library name
2. Query for the specific API: mcp__plugin_context7_context7__query-docs with:
   • libraryId from step 1
   • query describing the specific API or pattern you need
3. Read the returned documentation snippets

If Context7 is NOT available:

• Fall back to web search for {library} v{version} {api} documentation
• Use mcp__web_reader__webReader to fetch the official docs page
• This is [HEURISTIC] rather than [PROVEN] — note the evidence level

Step 3: Cite Sources

When writing framework-specific code, include a citation comment:

// Ref: React 19 useActionState — https://react.dev/reference/react/useActionState
const [state, submitAction, isPending] = useActionState(async (prevState, formData) => {
  // ...
}, initialState);

Or in Java:

// Ref: Spring Data JDBC 3.4 @Query — https://docs.spring.io/spring-data/jdbc/reference/repositories/query-methods.html
@Query("SELECT * FROM users WHERE email = :email")
Optional<User> findByEmail(@Param("email") String email);

Citation format: {framework} v{version} {api/function} — {url}

Step 4: Surface Conflicts

After fetching docs, compare against what you were about to write:

1. API signature changed? — parameters added, removed, or reordered
2. Deprecated pattern? — the pattern you planned to use is now deprecated
3. New recommended approach? — a better pattern exists in the current version
4. Breaking change? — the version in the project has a breaking change from what training data suggests

If a conflict is found:

• BLOCK if the planned code would use a removed API
• WARN if the planned code uses a deprecated but still functional API
• SUGGEST if a newer pattern exists but the old one still works

Step 5: Authority Hierarchy

When multiple documentation sources conflict, use this hierarchy:

1. Official docs (react.dev, docs.spring.io, fastapi.tiangolo.com) — highest authority
2. Type definitions (DefinitelyTyped, built-in .d.ts) — mechanical truth
3. Source code (GitHub repo, node_modules) — ground truth but may be internal
4. Community (Stack Overflow, blog posts) — useful for patterns, not API signatures
5. Training data (what the model "knows") — lowest authority, always verify

Rationalizations

Rationalization	Why It's Wrong
"I know this API — I've used it before"	APIs change between versions. React 18 hooks != React 19 hooks. Verify.
"The docs will just confirm what I already know"	Then verification takes 10 seconds. Do it. Unexpected deprecations are common.
"I can just check if the test passes"	Tests prove the code runs, not that it uses the recommended approach. Deprecated APIs pass tests today and break tomorrow.
"Looking up docs slows me down"	Writing the wrong API and debugging for 30 minutes is slower than a 10-second doc check.
"The codebase already uses this pattern"	The codebase may be on an older version. Your task might be the one that should update the pattern.

Red Flags

Watch for these signs that source-driven development would have prevented a problem:

• "Property X does not exist on type Y" — you used an API from a different version
• "Warning: X is deprecated, use Y instead" — you used training-data knowledge, not current docs
• Test passes but runtime behavior differs — API contract changed subtly between versions
• Code works locally but fails in CI — dependency version mismatch between environments
• Import not found — the module was reorganized in a newer version

Verification

After writing framework-specific code:

1. Did you include a citation comment? If not, add one.
2. Does the cited URL actually contain the API you used? Verify, don't hallucinate URLs.
3. Does the code match the version in the manifest? Not the latest version — the installed version.
4. Were there any conflicts surfaced in Step 4? If so, were they resolved?