Fix: drop stale <Static> output from fullStaticOutput on identity change

[chiga0]

Fixes #949.

Summary

`Ink#fullStaticOutput` is the running concatenation of everything every `` instance has ever emitted during the lifetime of an Ink renderer. It is initialised to `''` in the constructor and only ever grows — no code path shrinks or resets it. When `shouldClearTerminalForFrame` later fires (overflow, leaving fullscreen, fullscreen unmount), Ink writes `clearTerminal + fullStaticOutput + output`, which means any item emitted by a `` that has since been unmounted/replaced re-materialises above the current viewport even though it no longer exists in the React tree.

Real-world symptom: "cleared history reappears after a long response scrolls the viewport" in TUIs that drive a Static replay via a remount key (Gemini CLI, qwen-code, …). End-to-end repro thread: QwenLM/qwen-code#4083.

Fix

Track `rootNode.previousStaticNode` across commits. When `resetAfterCommit` detects that `rootNode.staticNode` has changed identity (first mount, last unmount, or remount via key), fire a new `onStaticChange` hook on the root node before `onImmediateRender`. Ink installs an `onStaticChange` handler that resets `this.fullStaticOutput = ''`. The new instance (if any) re-emits its items into a fresh accumulator on the immediate render that follows.

```diff
// resetAfterCommit, src/reconciler.ts

• if (rootNode.staticNode !== rootNode.previousStaticNode) {
• rootNode.previousStaticNode = rootNode.staticNode;
• if (typeof rootNode.onStaticChange === 'function') {

•  rootNode.onStaticChange();
  

• }
• }
  ```

```diff
// constructor wiring, src/ink.tsx
this.rootNode.onImmediateRender = this.onRender;

• this.rootNode.onStaticChange = this.handleStaticChange;
  ...
• handleStaticChange = (): void => {
• this.fullStaticOutput = '';
• };
  ```

Scope (no behaviour change for the classic case)

• The Tap-style "one Static mounted for the lifetime of the app, items keep getting appended" use case is untouched: `staticNode` identity never changes → `onStaticChange` never fires → `fullStaticOutput` keeps accumulating exactly as today.
• The rootNode.staticNode dangling reference causes OOM after <Static> unmount #904 / fix: clear staticNode reference on Static unmount #905 unmount path is strengthened: in addition to clearing `rootNode.staticNode` (so the renderer stops walking a freed Yoga tree), Ink now also drops the now-orphan output from `fullStaticOutput`, so a later overflow-driven `clearTerminal` rewrite does not resurrect the unmounted Static's items.
• The original `static output stops accumulating after Static unmounts (rootNode.staticNode dangling reference causes OOM after <Static> unmount #904)` regression test still passes — its length-stability assertion (`outputAfterChurn.length === outputAfterUnmount.length`) holds whether `fullStaticOutput` is left intact at unmount or reset at unmount; this PR doesn't change that invariant.

Test

Adds `fullStaticOutput is reset when unmounts so stale items are not replayed` to `test/components.tsx`. Mounts a `<Static items={['HISTORY-A', 'HISTORY-B']} />` in debug mode (every `stdout.write` is `fullStaticOutput + dynamicOutput`), unmounts it, asserts that the subsequent write does NOT include `HISTORY-A` or `HISTORY-B`. Without the fix the assertion fails; with the fix it passes.

The companion remount-via-key case is intentionally NOT tested here because it additionally depends on the `staticNode`-pointer-clobbered-on-remount bug fixed by #948. Each fix stands alone; this PR is independent of #948 and can be merged in either order. The two fixes compose to give the full "remount produces only new items, no resurrected old items" behaviour.

Verified:

• New test fails on `master` (`76d221c`) — confirms the bug
• New test passes with this patch
• Existing Static tests all pass (`static output`, `skip previous output when rendering new static output`, `static output stops accumulating after Static unmounts (rootNode.staticNode dangling reference causes OOM after <Static> unmount #904)`, `render only new items in static output on final render`, non-interactive mode, concurrent mode)
• Other test failures in the full suite (`cursor moves on space input`, `measure-element`-related, `wrap-ansi doesn't trim leading whitespace`) reproduce on `master` without this patch and are unrelated.

Why a hook on the root node and not inline in the reconciler

The reconciler owns the React → DOM mapping; `fullStaticOutput` is a private Ink-instance writer-side accumulator. A hook keeps the layering intact: the reconciler reports an identity change, Ink decides what to do with it. The same pattern is already used for `onRender`, `onImmediateRender`, and `onComputeLayout`.

[chiga0]

Review note submitted from local audit.

Generated By GPT-5 model

[sindresorhus]

Can you fix the merge conflict?

[chiga0]

Can you fix the merge conflict?

It's all clean now. Please check again.

By the way, cloud you please release package v7.0.3 after merged the pull request, thank you very much about that. Our package want to upgrade ink from v6.3 to v7, but find the issue. Thank you again.