[Feature] Add preview mode

[zhangyibin8111]

Problem Description

When previewing a file using the Rendered or Split view modes, clicking on a table or other area may cause changes to the file content.

Proposed Solution

Added preview mode, only allows viewing.

Use Cases

Suitable for situations where only reading mode is required.

Priority

How important is this feature to your workflow?

• Critical - blocking my work
• High - significant improvement
• Medium - nice to have
• Low - minor convenience

[OlaProeis]

@zhangyibin8111

Thanks for the report — this is a great idea, and it lines up with what we wanted for safe reading in Rendered/Split view.

Shipped in v0.3.1 (currently on the 0.3.1-experimental branch; will be in the public v0.3.1 release).

We implemented this as Preview lock: a per-tab read-only mode for preview panes, without turning the whole app into view-only.

How it works

• In Rendered or Split view, use the padlock in the bottom-right of the preview pane (markdown, CSV, or tree viewer).
• Locked: WYSIWYG edits are blocked — no table cell edits, no click-to-edit on headings/paragraphs, no task-checkbox toggles, no CSV/tree inline editing.
• Unlocked: Preview behaves as before (editable rendered view).
• The raw editor is never locked. In Split view you can still edit source on the left while the preview stays read-only on the right.
• The lock state is per tab and persists across view-mode changes and session restore.

What still works while locked

Navigation and reading are unchanged: scrolling, zoom, following links/wikilinks, copying text, code-block Run (if you use that), etc.

Docs

• Preview lock
• Behaviour matrix & regression notes

If you try v0.3.1 and anything still mutates the file when you expect read-only preview, please comment with your view mode and what you clicked — we’d like to tighten any gaps.