# Issue #171: Chat Command Parsing

## Objective

Implement command parsing layer for chat integration that is shared across Discord, Mattermost, and Slack bridges.

## Approach

1. Create command interface types
2. Write comprehensive tests for all command formats (TDD RED phase)
3. Implement tokenizer for parsing @mosaic commands
4. Implement action dispatch logic
5. Add error handling with helpful messages
6. Verify all tests pass (TDD GREEN phase)
7. Refactor if needed (TDD REFACTOR phase)

## Command Grammar

- Pattern: `@mosaic <action> [args...]`
- Actions: fix, status, cancel, retry, verbose, quiet, help
- Issue reference formats:
  - `#42` - Current repo issue
  - `owner/repo#42` - Cross-repo issue
  - `https://git.example.com/owner/repo/issues/42` - Full URL

## Progress

- [x] Create command interface types
- [x] Write unit tests (RED phase)
- [x] Implement command parser service
- [x] Implement tokenizer
- [x] Implement action dispatch
- [x] Handle error responses
- [x] Verify all tests pass (GREEN phase) - 24/24 tests passing
- [x] Run quality gates (typecheck, lint, build, test) - All passing
- [x] Commit changes

## Testing

- Test all command formats
- Test issue reference parsing (all 3 formats)
- Test error cases (invalid commands, missing args)
- Test edge cases (extra whitespace, case sensitivity)

## Notes

- Parser must be platform-agnostic (works with Discord, Mattermost, Slack)
- Error messages should be helpful and guide users
- Follow strict TDD: tests before implementation

## Implementation Details

- Used regex patterns for issue reference parsing (current repo, cross-repo, full URL)
- Tokenizer splits on whitespace after normalizing input
- Action dispatch uses switch statement for type safety
- Helpful error messages with examples provided for invalid input
- Case-insensitive command parsing (@Mosaic, @mosaic both work)
- Handles edge cases: extra whitespace, leading zeros in issue numbers

## Files Created

- `/home/jwoltje/src/mosaic-stack/apps/api/src/bridge/parser/command.interface.ts` - Type definitions
- `/home/jwoltje/src/mosaic-stack/apps/api/src/bridge/parser/command-parser.service.ts` - Parser service
- `/home/jwoltje/src/mosaic-stack/apps/api/src/bridge/parser/command-parser.spec.ts` - Unit tests

## Test Results

- 24/24 tests passing
- All quality gates passed (typecheck, lint, build)