[kalvinnchau]

xterm 6 removes the legacy Alt-arrow mappings and changes the scrollbar and DOM renderer. A dependency-only upgrade would change shell navigation. Upgrade @xterm/xterm from 5.5.0 to 6.0.0 and @xterm/addon-fit from 0.10.0 to 0.11.0, preserving the old macOS/Linux navigation sequences after the existing shortcut dispatcher runs.

Mapped keys use public Terminal.input(..., true), retaining normal user-input provenance and scrolling. The private coreService.onUserInput seam remains necessary: v6's public onData still omits the source. Both upstream implementations were checked, and real keyboard/paste/parser events exercise the boundary. Existing appearance assertions now measure actual glyph spans and the visible v6 background.

Validation:

• Production build passes.
• All 18 cases in the complete terminal renderer, motion, and browser-availability files pass in Chromium and WebKit at 23a694a7.
• New navigation tests fail without the compatibility mapping in both engines and for both platform mappings.
• Three browser cases added, none removed. They require real xterm event ordering, rendering, layout, wheel input, and scrollbar dragging. Coverage includes modified arrows, application cursor mode, bracketed paste, parser replies, atomic synchronized output and timeout recovery, alternate-screen restoration, hidden output, retained scrollback, live shortcut overrides, themes, and enlarged text.
• Mandatory push checks pass: TypeScript, the full Vitest suite (10,081 passed, 9 skipped; 662 passed files, 2 skipped), design types and design guards. No tests were disabled by this change.

The platform mappings are exercised on macOS with navigator-platform emulation; this does not establish execution on Linux or native packaged-desktop acceptance. The scrollbar now uses xterm's themed implementation, so its appearance and wheel normalization follow v6. No new addon or native PTY behavior is introduced.

Human-reported native macOS smoke test passed on 2026-10-16 at 23a694a7. The human confirmed all five supplied checks:

1. Word navigation and Ctrl+C line cancellation.
2. Interrupting a running process and returning to the prompt.
3. Fullscreen TUI use, resizing, hide/reopen, and switching channels while retaining the session.
4. Wheel/scrollbar scrolling, light/dark appearance, and interface-size changes.
5. Restart/end/reopen, live shortcut rebinding without shell input, and plugin disable/re-enable.

Linux execution and packaged-desktop acceptance remain unverified. The optional manual synchronized-redraw command was not included in the human confirmation; synchronized output and timeout recovery are covered by the automated browser cases.

Agent self-review and automated renderer validation completed before the human smoke test; no blocking code findings remain.

buzz-review-completed

[wpfleger96]

🤖 thanks for this. I diffed xterm's Keyboard.ts between 5.5.0 and 6.0.0 and the restored sequences match what 5.5 sent, including Alt+Up/Down passing through unchanged on macOS. terminal.input(..., true) goes through triggerDataEvent with wasUserInput, so the onUserInput provenance seam and scroll-on-input both still work, and the other v6 breaking changes (overviewRulerWidth, windowsMode, fastScrollModifier) aren't used here.

two nonblocking nits:

• for every other key it sends, xterm calls cancel(event, true), which also does stopPropagation(). the compat path only calls preventDefault(), so Alt+arrow keydowns keep bubbling out of the terminal. the shortcut dispatcher skips prevented events, so I don't see a live bug, but adding event.stopPropagation() would match xterm.
• docs/terminal.md says the Ctrl-arrow mapping applies on Linux, but the code applies it on every non-Apple platform, Windows included (same as 5.5). "on Linux and Windows" would be more accurate.