StarPunk/docs/reports/ADR-019-implementation-summary.md

ADR-019 Implementation Summary

Quick Reference for Developer Date: 2025-11-19 Version Target: 0.8.0

What You Need to Know

This is a critical bug fix that implements IndieAuth authentication correctly by following the IndieLogin.com API specification. The previous attempts (v0.7.0 OAuth metadata, v0.7.1 h-app visibility) were based on misunderstanding the requirements.

Documentation Structure

All documentation has been separated into proper categories:

1. Architecture Decision Record (ADR-019)

File: /home/phil/Projects/starpunk/docs/decisions/ADR-019-indieauth-pkce-authentication.md

What it contains:

• Context: Why we need this change
• Decision: What we're doing (PKCE implementation)
• Rationale: Why this approach is correct
• Consequences: Benefits and trade-offs
• NO implementation details (those are in the design doc)

2. Design Document (Complete Technical Specifications)

File: /home/phil/Projects/starpunk/docs/designs/indieauth-pkce-authentication.md

What it contains:

• Complete authentication flow diagrams
• PKCE implementation specifications
• Database schema changes
• Exact code changes with line numbers
• Code to remove with line numbers
• Testing strategy and test code
• Error handling specifications
• Security considerations
• Complete implementation guide with step-by-step instructions

This is your primary implementation reference.

3. Versioning Guidance

File: /home/phil/Projects/starpunk/docs/reports/ADR-019-versioning-guidance.md

What it contains:

• Version number decision: 0.8.0
• Git tag handling (keep all existing tags)
• CHANGELOG update instructions
• Rationale for versioning choice
• What to do with v0.7.0 and v0.7.1 tags

Quick Implementation Checklist

Follow the design document for detailed steps. This is just a high-level checklist:

Pre-Implementation

• Read ADR-019 (architectural decision)
• Read full design document
• Review versioning guidance
• Understand PKCE flow

Database

• Add code_verifier column to auth_state table
• Test migration

Code Changes

• Add PKCE functions to starpunk/auth.py
• Update _verify_state_token() to return verifier
• Update initiate_login() with PKCE
• Update handle_callback() with PKCE and iss validation
• Update callback route to extract and pass iss
• Update logging to redact code_verifier

Code Removal

• Remove OAuth metadata endpoint from starpunk/routes/public.py
• Remove h-app microformats from templates/base.html
• Remove indieauth-metadata link from templates/base.html

Testing

• Run unit tests for PKCE functions
• Run integration tests for auth flow
• Manual testing with IndieLogin.com
• Verify logs show PKCE parameters (redacted)
• Check database for code_verifier storage

Versioning

• Update __version__ to "0.8.0" in starpunk/__init__.py
• Update __version_info__ to (0, 8, 0)
• Update CHANGELOG.md with v0.8.0 entry
• Add notes to v0.7.0 and v0.7.1 CHANGELOG entries
• Create git tag v0.8.0
• Do NOT delete v0.7.0 or v0.7.1 tags

Documentation

• Update ADR-016 status to "Superseded by ADR-019"
• Update ADR-017 status to "Superseded by ADR-019"
• Add implementation note to ADR-005

Key Points

What's Wrong Now

1. Missing PKCE - IndieLogin.com requires it, we don't have it
2. Wrong endpoints - Using /auth instead of /authorize and /token
3. Unnecessary features - OAuth metadata and h-app not needed

What We're Fixing

1. Add PKCE - Generate verifier/challenge, store, validate
2. Correct endpoints - Use /authorize and /token
3. Remove cruft - Delete OAuth metadata and h-app
4. Add iss validation - Security best practice

Why v0.8.0?

• Not v0.7.2: Too substantial for PATCH (database change, PKCE implementation, removals)
• Not v1.0.0: Not ready for stable (V1 features not complete)
• Yes v0.8.0: Appropriate MINOR increment for significant change during 0.x phase

Why Keep v0.7.0 and v0.7.1 Tags?

• Git history integrity
• Can't "un-release" versions
• CHANGELOG explains what didn't work
• Shows progression of understanding

File Reference

Read in this order:

1. This file (you are here) - Overview
2. /home/phil/Projects/starpunk/docs/decisions/ADR-019-indieauth-pkce-authentication.md - Architectural decision
3. /home/phil/Projects/starpunk/docs/designs/indieauth-pkce-authentication.md - Full implementation guide
4. /home/phil/Projects/starpunk/docs/reports/ADR-019-versioning-guidance.md - Versioning details

Standards Reference:

• /home/phil/Projects/starpunk/docs/standards/versioning-strategy.md - Semantic versioning rules
• /home/phil/Projects/starpunk/docs/standards/git-branching-strategy.md - Git workflow

Critical Files to Modify

Python Code

/home/phil/Projects/starpunk/starpunk/auth.py
/home/phil/Projects/starpunk/starpunk/routes/auth.py
/home/phil/Projects/starpunk/starpunk/routes/public.py (deletions)
/home/phil/Projects/starpunk/starpunk/__init__.py (version)

Templates

/home/phil/Projects/starpunk/templates/base.html (deletions)

Database

Schema: auth_state table (add code_verifier column)

Documentation

/home/phil/Projects/starpunk/CHANGELOG.md (updates)
/home/phil/Projects/starpunk/docs/decisions/ADR-016-indieauth-client-discovery.md (status)
/home/phil/Projects/starpunk/docs/decisions/ADR-017-oauth-client-metadata-document.md (status)
/home/phil/Projects/starpunk/docs/decisions/ADR-005-indielogin-authentication.md (note)

Success Criteria

You're done when:

1. User can log in via IndieLogin.com
2. PKCE parameters visible in authorization URL
3. code_verifier stored in database
4. Token exchange succeeds with code_verifier
5. All tests pass
6. Version is 0.8.0
7. CHANGELOG updated
8. ADR statuses updated

Getting Help

If authentication still fails:

1. Check logs for PKCE parameters (should be redacted but visible)
2. Verify database has code_verifier column
3. Check authorization URL has code_challenge and code_challenge_method=S256
4. Verify token exchange POST includes code_verifier
5. Check IndieLogin.com response in logs

Key debugging points:

• initiate_login(): Should generate verifier and challenge
• Database: Should store verifier with state
• Authorization URL: Should include challenge
• handle_callback(): Should retrieve verifier
• Token exchange: Should send verifier
• IndieLogin.com: Should return {"me": "url"}

Questions?

Refer to:

• Design document for "how"
• ADR-019 for "why"
• Versioning guidance for "what version"

All documentation follows the project principle: Every line must justify its existence.

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Author: StarPunk Architect Status: Ready for Implementation Priority: Critical (authentication broken in production)