feat(sync): load local prompt variations

[ctawiah]

Context

This is the foundation for Phase 1 of code canonical sync for AI Config prompt variations. The CLI needs a stable local format that people can edit and that later planning requests can send to Gonfalon without recreating or interpreting server-owned fields.

This PR is intentionally local-only. It defines how prompt files are discovered, parsed, validated, and converted into sync resources. It does not call Gonfalon, calculate fingerprints, create plans, or apply changes.

Summary

• Supports agent instructions and completion messages in an editor-friendly .prompt.md format.
• Includes variation identity, name, model configuration, model values, and output format.
• Keeps the server-owned AI Config variation comment out of local files and sync payloads.
• Walks project directories and sorts variations by project and lookup key for stable request construction.
• Rejects malformed or unsupported files with errors that identify the failing path.
• Leaves canonicalization, fingerprinting, and comparison to Gonfalon.

Verification

• go test ./internal/sync/... -count=1

[cursor]

Cursor Bugbot has reviewed your changes using default effort and found 2 potential issues.

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, have a team admin enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit 910e2dc. Configure here.}

[cursor]

Closing fence drops prompt body

Medium Severity

When the closing --- fence is not followed by a line ending or EOF, splitFrontMatter discards the rest of the file and returns an empty body instead of failing. consumeLineEnding already treats EOF as success, so this branch only hits trailing spaces, extra dashes, or same-line text after the closer. Compile then succeeds with empty instructions or messages, so those prompts can be synced as blank.

 

^{Reviewed by Cursor Bugbot for commit 910e2dc. Configure here.}

[cursor]

Walk errors empty a project

Low Severity

compileProjectVariations treats any fs.ErrNotExist from the walk as an empty project, not only a missing configs directory. A later ReadFile miss, such as a dangling symlink to a .prompt.md file, returns nil, nil and drops variations already collected for that project instead of surfacing the path error.

 

^{Reviewed by Cursor Bugbot for commit 910e2dc. Configure here.}