Summary

Fix center-pane scrolling for chat/terminal tabs while preserving raw terminal input behavior.

What changed

• Capture chat redraw history for normal-screen clear/redraw flows, including tmux-translated ESC[H ESC[J synchronized redraws.
• Forward mouse wheel events to embedded apps that request mouse reporting, using SGR coordinates when enabled.
• Add prefix-based center scroll controls: C-Space u scrolls up and C-Space d scrolls down when a center terminal is focused.
• Keep raw Ctrl+U and Ctrl+D flowing to the agent instead of using them as amux scroll shortcuts.
• Preserve explicit CSI 3J clearback semantics outside the synchronized redraw-preservation case.
• Add unit and real tmux/e2e coverage for wheel forwarding, chat redraw scrollback, prefix scrolling, and raw control byte delivery.

Root cause

Amux was not preserving chat redraw frames when tmux translated full-screen clears into cursor-home plus erase-to-end. Separately, mouse wheel events were treated only as local scroll unless the embedded terminal's mouse reporting state was tracked.

Validation

• /Users/andrewlee/.agents/skills/autoreview/scripts/autoreview --mode local clean
• make verify-loop
• go test ./...
• make harness-presets
• pinned make devcheck
• pinned make lint-strict-new
• git diff --check
• pre-push CI-parity lint, harness, and e2e hook passed