test(runtime-tests): pin JSX children typing under the automatic runtime

The WithChildren shim is only exercised under jsx:"react-jsx", which lives
solely in integration/pty/fixtures/tsconfig.json. Nothing in `ready` ran tsc
against that config (vp check uses jsx:"preserve" and excludes the fixtures;
pty-test only transpiles them), so a regression in the shim — children
silently rejected, or declared props silently widened away — would pass
verification unnoticed.

Add a type-only regression fixture (not a runnable PTY program; not a
*.test.tsx, so vitest never collects it) that pins both directions of the
contract: children are accepted on Box/Text/Static/Transform, and declared
props stay validated via @ts-expect-error (invalid value, wrong type, unknown
prop, and missing required props on Transform/Static).

Wire `tsc -p integration/pty/fixtures/tsconfig.json --noEmit` into `ready` via
a typecheck:fixtures script, run after build (so @vue-tui/runtime resolves
against fresh dist types) and before pty-test, so the react-jsx path is
actually enforced rather than only manually checkable.

packages/runtime-tests/integration/pty/fixtures/jsx-children-types.tsx

@@ -0,0 +1,42 @@
+/**
+ * Type-only regression fixture — NOT a runnable PTY program (nothing spawns it,
+ * and it is not a `*.test.tsx` so vitest never collects it). It exists purely so
+ * `tsc -p integration/pty/fixtures/tsconfig.json` type-checks it.
+ *
+ * It pins the contract the `WithChildren` shim establishes under the automatic
+ * JSX runtime (`jsx: "react-jsx"`, this dir's tsconfig — the mode the main
+ * runtime-tests tsconfig does NOT use): components accept JSX children while
+ * their declared props stay fully validated. If the shim regresses in either
+ * direction, this file fails to compile:
+ *   - children rejected     -> the `accepted` cases error
+ *   - prop validation lost   -> the `@ts-expect-error` directives become unused
+ */
+import { Box, Static, Text, Transform } from "@vue-tui/runtime";
+
+// Children are accepted (the shim's whole purpose under the automatic runtime).
+export const accepted = [
+  <Text color="green">plain text child</Text>,
+  <Box flexDirection="row">
+    <Text>nested child</Text>
+  </Box>,
+  <Static items={[1, 2, 3]}>
+    <Text>static child</Text>
+  </Static>,
+  <Transform transform={(line) => line}>
+    <Text>transformed child</Text>
+  </Transform>,
+];
+
+// Declared props stay validated — children must not widen the prop bag.
+export const rejected = [
+  // @ts-expect-error `display` accepts "flex" | "none", not a number
+  <Box display={123}>x</Box>,
+  // @ts-expect-error `bold` accepts a boolean, not a string
+  <Text bold="yes">x</Text>,
+  // @ts-expect-error `bogusProp` is not a declared Box prop
+  <Box bogusProp="x">x</Box>,
+  // @ts-expect-error `transform` is required
+  <Transform>x</Transform>,
+  // @ts-expect-error `items` is required
+  <Static>x</Static>,
+];

packages/runtime-tests/package.json

@@ -6,6 +6,7 @@
   "scripts": {
     "test": "vp test",
     "pty-test": "vp test run --config vitest.pty.config.ts --passWithNoTests",
+    "typecheck:fixtures": "tsc -p integration/pty/fixtures/tsconfig.json --noEmit",
     "check": "vp check"
   },
   "devDependencies": {