Editable rendered views, Open with, presentation mode

[mindaugaskasp]

What

Editable rendered views. The rendered Markdown and Jira views in the snippet editor are contenteditable WYSIWYG rather than one-way previews. Both parsers already emitted the same block tree, so the read-back is one shared reader (domToBlocks) and only the markers differ (markdownSerialize, jiraSerialize).

While typing, the DOM is the source of truth — the tree is re-parsed only when content changes from outside, or the caret jumps to offset 0 on every keystroke. Paste reads text/plain only: a native contenteditable paste inserts the clipboard's text/html, which is attacker-authored markup landing in the DOM behind Vue's back (rule 8). Task boxes tick where they are drawn.

Round trips normalise spelling, never structure (* item → - item, bq. → {quote}). Each loss is asserted individually so a silent widening fails the build.

Open with. DiffBro appears in Finder's and Explorer's Open-with lists for 12 text/data extensions, role: Viewer / rank: Alternate so it never becomes the default handler. First file opens a tab and takes the left pane, the next joins it on the right, the one after starts a new tab — derived from tab state, never counted, so an action between two opens cannot desync the cycle.

Presentation mode (F5). The comparison alone, full screen, Esc restores — including leaving a window that was already full screen alone.

Two launch-time bugs this exposed

• The app refused to start. Two files selected at once parsed the second path as a verb; index.js reported "Unknown command" and exit(1) before any window existed.
• It opened its own source. Unpackaged, argv[1] is the entry script, which was read as a document.

Both now have regression tests.

Smaller fixes

• Capture is Mermaid-only (a picture of text is a worse copy of Copy)
• Tab names take word characters only — */ was accepted and rendered
• Collapsed rail no longer glues the key buttons to the window edge
• The waiting screen can clear a wrong first file

Housekeeping

• Decoding moved out of Electron-importing files.js into a pure, tested decodeText.js on TextDecoder, dropping iconv-lite. Verified byte-identical against iconv for the same detected label.
• The 20-theme list is imported rather than written out three times
• DEFAULT_SETTINGS, walkReset, currentLocale, isDiagramTheme deleted as dead
• tabs.js beat its size ratchet; its exemption is deleted, not raised

Verification

• npm run check — exit 0; coverage 95.30 / 88.38 / 95.83 / 96.36
• Full e2e suite green (the two tag-shelf-resize failures were mine and are fixed — sidebar padding is the shelf grip's clearance, held at 10px)
• make theme-sweep — 1580 measurements across all 20 themes, all passing. Worst new reading: sepia 3.93 against a 3.0 floor
• Size ratchets fired four times and were resolved by extraction, never by raising a cap

Not verified

macOS open-file and the Windows default-handler behaviour need a real packaged install — LaunchServices can't be driven from a test.

🤖 Generated with Claude Code