Render JSON, JSONL, and YAML files with pretty/expandable view

[nonatofabio]

Summary

Extend Mindle beyond Markdown to render JSON, JSONL, and YAML files in a clean, readable way. These formats sit right next to .md files in the kind of project folders Mindle is built for (specs, configs, logs, AI-tool outputs), and there's no dedicated macOS reader for them either.

Proposed behavior

.json

• Pretty-printed with consistent indentation (2 or 4 spaces, ideally configurable)
• Syntax highlighting (keys, strings, numbers, booleans, null)
• Collapsible objects and arrays (click to fold/unfold subtrees)

.jsonl / .ndjson

• Each line shown as a single collapsed entry by default — compact list view
• Click a line to expand it into the full pretty-printed JSON view (same renderer as .json)
• "Expand all" / "Collapse all" affordance
• Useful for large logs and AI streaming-output captures

.yaml / .yml

• Pretty rendering with syntax highlighting
• Collapsible mappings and sequences (same fold behavior as JSON)
• Multi-document YAML streams (separated by ---) treated like JSONL: each document is a collapsible entry, expandable into the full view

Why this fits Mindle

Mindle's reader positioning is strongest for the "AI writes, you read" workflow — and that workflow doesn't stop at Markdown. AI coding tools and pipelines generate JSON specs, JSONL logs, and YAML configs in the same project folders. A user opening Mindle to read a CLAUDE.md will likely also want to peek at the claude.jsonl log or the config.yaml next to it without launching VSCode.

Implementation notes (optional)

• Detect by file extension first; fall back to content sniffing for files without an extension
• Reuse the existing reader chrome (tabs, themes, Quick Look) — only the body renderer changes per format
• Errors (malformed JSON/YAML) shown inline with line/column, not as a modal — keep it a reader, not an editor