Preserve original filename in uploaded image paths (Vibe Kanban)

[stunningpixels]

Summary

Changes the image storage filename format from {UUID}.{ext} to {UUID}_{clean_name}.{ext}. The filename can be useful to help the model understand.

Changes Made

Added sanitize_filename() function

A new helper function that sanitizes filenames for filesystem safety:

• Converts to lowercase
• Replaces whitespace with underscores
• Removes special characters (keeps only alphanumeric and underscores)
• Truncates to 50 characters max to avoid filesystem limits
• Falls back to "image" if the result is empty

Updated filename generation

Modified store_image() in ImageService to use the new format:

let clean_name = sanitize_filename(original_filename);
let new_filename = format!("{}_{}.{}", Uuid::new_v4(), clean_name, extension);

Examples

Original Filename	New Storage Filename
Screenshot 2024-01-15.png	a1b2c3d4-..._screenshot_2024_01_15.png
My Cool Image!!!.jpg	a1b2c3d4-..._my_cool_image.jpg
résumé.png	a1b2c3d4-..._rsum.png
.png (no stem)	a1b2c3d4-..._image.png

Why This Change

• Improved readability: File paths in markdown (.vibe-images/uuid_screenshot.png) are now human-readable
• Easier debugging: When inspecting cache directories or worktrees, files are identifiable by name
• Backwards compatible: Existing images continue to work since lookups use database IDs, not filename parsing

Files Modified

• crates/services/src/services/image.rs

Testing

• ✅ Backend type check passes (pnpm run backend:check)
• ✅ All 195 workspace tests pass (cargo test --workspace)

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This PR was written using Vibe Kanban