1.0: TUI render-path stabilization freeze — soak + regression tests before 1.0

[mabry1985]

From the 1.0-readiness audit. Not a filed bug — a churn signal. The TUI render/resize path has dominated recent releases:

• #467 / v0.71.1 — reflow <Static> history on resize
• #469 / v0.71.2 — stop live-region output duplicating on resize (the throttled clear+repaint)
• #440 — full-screen + native selection (reversed v0.65.0's mouse capture)
• #444 word-diff, #459 thinking render, #449 gradient spinner

4+ of the last ~8 releases touched the render loop. For a 1.0 the render path should stop churning.

Why this is fragile (verified constraints, don't re-litigate)

• Ink's <Static> is append-only and index-tracked — it never redraws committed lines; the array passed to it must only ever grow (packages/cli/src/ui/components/MainContent.tsx:36-40).
• Ink's live region redraws by erasing the previous frame's stored log-update line count — after a resize the terminal has reflowed that frame to a different height, so the erase misses and stale frames land in scrollback.
• refreshStatic() (clear + historyRemountKey bump) is the only lever that fully repaints; it's now called on model change, /clear, view switch, transcript toggle, and (as of fix(tui): stop live-region output duplicating on terminal resize #469) resize.
• In full-screen, layout height==rows forces Ink into the clearTerminal branch — it rewrites the whole alt-screen on every commit.

Proposed 1.0 gate

1. Soak the render path — a real-terminal pass over: drag-resize (inline + full-screen), long sessions, streaming + spinner, agent tabs, transcript overlay, dialogs. Resize duplication is real-TTY-only — ink-testing-library's fake stdout has no cursor/scrollback, so unit tests cannot catch it (this is exactly why fix(tui): stop live-region output duplicating on terminal resize #469 shipped unverified until a live check).
2. Regression tests at the seams we can test — resize→repaint wiring (done in DefaultAppLayout.test.tsx), <Static> growth invariant, refreshStatic call sites.
3. Tune RESIZE_THROTTLE_MS (currently 80ms, DefaultAppLayout.tsx) if the drag repaint flickers in daily use.
4. Freeze the render loop for 1.0 — TUI Wave-2 (TUI S4 — Steer & Queue (interrupt + resubmit-merge) #450–TUI S9 — adaptive 'system' theme + semantic palette + gradient brand #455) is explicitly post-1.0; several are high-blast-radius (S6 touches the ~1100-line KeypressContext; S7 refactors AppContainer's ~120-field memo).

Related: specs/tui-overhaul.md, #456 (minor follow-ups).

[mabry1985]

Descoped. protoCLI is an in-house tool + reference pattern, not a shipped product — the whole 1.0 hardening project was over-scoped (product thinking for a "use it, hack it, break it" tool). Dropping the project entirely.

The findings themselves stay preserved here (closed, searchable) and in session memory. The few that are real bugs regardless of product-vs-pattern — #476 (prompt hooks / getCustomExcludes silently no-op) and #479 (SIGTERM swallows cleanup, LSP orphans, unbounded shell output) — are the ones worth reopening/cherry-picking if they ever bite. Reopen any of these if it becomes worth doing.