# ADR-022: Multiple Syndication Format Support

## Status
Proposed

## Context
StarPunk currently provides RSS 2.0 feed generation using the feedgen library. The IndieWeb community and modern feed readers increasingly support additional syndication formats:
- ATOM feeds (RFC 4287) - W3C/IETF standard XML format
- JSON Feed (v1.1) - Modern JSON-based format gaining adoption
- Microformats2 - Already partially implemented for IndieWeb parsing

Multiple syndication formats increase content reach and client compatibility.

## Decision
Implement ATOM and JSON Feed support alongside existing RSS 2.0, maintaining all three formats in parallel.

## Rationale
1. **Low Implementation Complexity**: The feedgen library already supports ATOM generation with minimal code changes
2. **JSON Feed Simplicity**: JSON structure maps directly to our Note model, easier than XML
3. **Standards Alignment**: Both formats are well-specified and stable
4. **User Choice**: Different clients prefer different formats
5. **Minimal Maintenance**: Once implemented, feed formats rarely change

## Consequences
### Positive
- Broader client compatibility
- Better IndieWeb ecosystem integration
- Leverages existing feedgen dependency for ATOM
- JSON Feed provides modern alternative to XML

### Negative
- Three feed endpoints to maintain
- Slightly increased test surface
- Additional routes in API

## Alternatives Considered
1. **Single Universal Format**: Rejected - different clients have different preferences
2. **Content Negotiation**: Too complex for minimal benefit
3. **Plugin System**: Over-engineering for 3 stable formats

## Implementation Approach
1. ATOM: Use feedgen's built-in ATOM support (5-10 lines different from RSS)
2. JSON Feed: Direct serialization from Note models (~50 lines)
3. Routes: `/feed.xml` (RSS), `/feed.atom` (ATOM), `/feed.json` (JSON)

## Effort Estimate
- ATOM Feed: 2-4 hours (mostly testing)
- JSON Feed: 4-6 hours (new serialization logic)
- Tests & Documentation: 2-3 hours
- Total: 8-13 hours