fix(tui): skip unchanged footer redraws

[wooksong]

Summary

• Skip terminal writes when streaming leaves the rendered footer unchanged.
• Avoid immediate redraws for repeated activity text while retaining the one-second activity tick.
• Enclose changed footer paints and full redraws in synchronized output.
• Add focused regression tests for hidden reasoning, activity updates, streamed replies, and transcript rebuild paths.

Testing

• pnpm test (709 tests)
• pnpm typecheck
• pnpm build
• pnpm lint:tools

Closes #27

[TaewoooPark]

Thanks again @wooksong for the focused fix! I tested the built CLI in a visible xterm.js terminal connected to a real macOS PTY, and found one resize case that needed a small follow-up. I've added commit 481247c to this branch.

Why the extra commit: after a long response settles with the composer at the bottom, resizing from 80×24 to 80×12 clips the lower composer border and status hint. At ccf79b4, the footer cache treats that display as unchanged and writes nothing; expanding back to 24 rows does not restore it either. The cache compared width/content/cursor, but terminal height can invalidate where those rows actually are.

The follow-up records the painted height and uses the existing full-screen rebuild path when height changes, both for the resize event and for a paint that happens before the debounced resize handler. Clearing relative to the old cursor position would not be sufficient after clipping. Unchanged-size hidden reasoning still produces no output, so the main benefit of your patch is preserved.

Validation: both added regression cases fail before this commit and pass afterward; all 711 tests, typecheck, build, and tool-schema lint pass locally. I also repeated 24→12→24 at 80 columns in the visible PTY-backed terminal and confirmed that the lower border, hint, and composer cursor remain correct. This used a local Motif-style SSE fixture, not a live model request. Remote CI for this exact commit also passed all five jobs (Node 20/22, Linux ARM64, Python, and goldens): https://github.com/TaewoooPark/Motifcode/actions/runs/35743315930.

Could you please review the follow-up commit and confirm that it looks good to you, ideally also trying the height-only resize in your terminal? I'll leave the PR open for your feedback before merging.

The other pre-existing findings are tracked separately in #30 (paste line endings), #31 (reasoning-toggle transcript duplication), and #32 (post-exit footer), with additional reproduction notes on #28. They are not bundled into this patch.

[wooksong]

Could you please review the follow-up commit and confirm that it looks good to you, ideally also trying the height-only resize in your terminal? I'll leave the PR open for your feedback before merging.

@TaewoooPark Reproduced on ccf79b4 in WSL xterm: 80×24 to 80×12 clips the lower composer border, and returning to 24 does not restore it. Windows Terminal did not clip it. LGTM.

[TaewoooPark]

Thanks @wooksong for the focused contribution and for checking the height-resize case in WSL xterm and Windows Terminal!

I rechecked 481247c against the original ccf79b4 in a visible xterm.js terminal backed by a real macOS PTY: after a settled response, 80×24 → 80×12 → 80×24 now preserves the composer border, hint, and cursor. The unchanged-footer optimization is preserved. The 66 related tests and typecheck passed again, and all five CI jobs passed on this exact head: https://github.com/TaewoooPark/Motifcode/actions/runs/35743315930.

No further change is needed for #27. Merging this PR as a squash commit now. The separate scrollback work remains tracked in #28 / #34; this merge does not include an npm release. Thank you again!