diff --git a/packages/runtime-tests/vite.config.ts b/packages/runtime-tests/vite.config.ts
index 71ebeea..e4acb29 100644
--- a/packages/runtime-tests/vite.config.ts
+++ b/packages/runtime-tests/vite.config.ts
@@ -4,8 +4,12 @@ import vueJsx from "@vitejs/plugin-vue-jsx";
 export default defineConfig({
   plugins: [vueJsx()],
   test: {
-    // chalk disables color in non-TTY envs; force it on so ANSI style bugs don't hide from tests
-    env: { FORCE_COLOR: "3" },
+    // chalk disables color in non-TTY envs; force it on so ANSI style bugs don't hide from tests.
+    // CI:"false" because the runner sets CI=true, which flips vue-tui's interactive
+    // detection (interactive = !isInCi && isTTY) off — disabling the resize listener,
+    // cursor, and ANSI erases that these render tests exercise. The PTY child helpers
+    // already force CI=false for the same reason; do it for the in-process suite too.
+    env: { FORCE_COLOR: "3", CI: "false" },
     // Files parallelize, but tests within a file run serially: many assert
     // timing-sensitive render/commit/flush counts that destabilize under
     // in-file concurrency on a constrained (4-core) CI runner.
diff --git a/packages/runtime-tests/vitest.pty.config.ts b/packages/runtime-tests/vitest.pty.config.ts
index 7adeb5e..834badc 100644
--- a/packages/runtime-tests/vitest.pty.config.ts
+++ b/packages/runtime-tests/vitest.pty.config.ts
@@ -20,6 +20,9 @@ export default defineConfig({
     // trap). File-level parallelism is the proven, stable win.
     fileParallelism: true,
     testTimeout: 15000,
-    env: { FORCE_COLOR: "3" },
+    // CI:"false" so the runner's CI=true doesn't flip interactive detection off
+    // for any in-process render tests under this config (the PTY child helpers
+    // set it per-spawn, but vitest-level tests need it too).
+    env: { FORCE_COLOR: "3", CI: "false" },
   },
 });