fix(editor): add Tab/Shift+Tab list indentation (#202)

[zacharias-ona]

Closes #202

What

Pressing Tab inside a bullet or numbered list item did nothing — there was no way to create nested lists. Lexical's built-in TabIndentationPlugin doesn't work for list items because ListItemNode.canIndent() returns false, causing Tab to insert a tab character instead of indenting.

How

Added a custom ListTabIndentationPlugin that intercepts KEY_TAB_COMMAND at high priority when the cursor is inside a ListItemNode. It dispatches INDENT_CONTENT_COMMAND (Tab) or OUTDENT_CONTENT_COMMAND (Shift+Tab) inside editor.update(), which Lexical's RichTextPlugin handler routes to ListItemNode.setIndent() to create/remove nested list levels. Max indent depth is capped at 7.

Testing

Added 3 Playwright E2E tests in e2e/editor-list-indent.spec.ts:

• Tab indents a bullet list item into a nested list
• Shift+Tab unindents a nested bullet list item back to flat
• Tab indents a numbered list item into a nested list

All tests verify the DOM structure (nested <ul>/<ol> elements) after keyboard interaction.

[vercel]

The latest updates on your projects. Learn more about Vercel for GitHub.

Project	Deployment	Actions	Updated (UTC)
memo	Ready	Preview, Comment	Apr 17, 2026 10:26pm

[zacharias-ona]

✅ UI verification passed — design spec compliance confirmed.

Static analysis: The new ListTabIndentationPlugin is purely behavioral (intercepts KEY_TAB_COMMAND, dispatches INDENT/OUTDENT). It renders null — no DOM output, no styling, no color/typography/spacing changes. No design spec violations.

Visual verification: Playwright screenshots of the editor page (desktop dark + mobile) show no regressions. Layout, colors, typography, spacing, and responsive behavior all match .agents/design.md.

[zacharias-ona]

✅ Post-merge verification passed.

E2E suite: 50/50 tests passed (including the 3 new editor-list-indent tests from this PR).

Ad-hoc smoke tests:

• ✅ Landing page — loaded, has title
• ✅ /sign-in — rendered with email input
• ✅ /api/health — returned OK
• ✅ Authenticated login flow — redirected to workspace
• ✅ Workspace page — fully loaded
• ✅ No console errors (unauthenticated or authenticated)

Skipped:

• /dashboard (route does not exist)
• Editor navigation via sidebar (no page buttons with timestamps found in test workspace)