Markdown preview: local images never render (relative/absolute/file:// ignored; only http(s) and data: work)

[Fartown]

Otty version: 1.2.3 (macOS)
Component: built-in Markdown preview (file-open-with = "otty", .md → Markdown preview)

Summary

The Markdown preview renders text, tables and links correctly, but images referenced via local file paths never render — they show a broken-image placeholder. All local reference forms are affected:

• relative: ![a](pic.jpg)
• sub-directory: ![a](sub/pic.jpg)
• absolute: ![a](/tmp/pic.jpg)
• file URL: ![a](file:///tmp/pic.jpg)

http(s):// and data: URIs work fine.

Evidence (controlled experiments)

1. atime probing — opened an .md containing the four local forms above; atimes of all referenced image files stayed untouched → the renderer never even attempts to read local image files.
2. HTTP works — same document with image URLs rewritten to http://127.0.0.1:8899/... loads everything (server log: 83/83 GET 200).
3. data: works — a document with 83 base64 data-URI images renders them (verified via decode CPU time).

Expected

Relative image paths resolve against the Markdown file's own directory and local images render (as in VS Code / Typora / GitHub), so repo docs like docs/guide.md + docs/assets/x.png preview correctly.

Actual

Only http(s) and data: images load; local file images are silently ignored.

Why it matters

Previewing repository documentation with bundled ./assets images is a common workflow; today the only workarounds are running a local HTTP server or embedding base64 — both awkward.