diff --git a/.github/workflows/windows-arm64-diagnostics.yml b/.github/workflows/windows-arm64-diagnostics.yml
index 6f9abec..daaf868 100644
--- a/.github/workflows/windows-arm64-diagnostics.yml
+++ b/.github/workflows/windows-arm64-diagnostics.yml
@@ -56,21 +56,13 @@ jobs:
           whoami /groups | Select-String -Pattern 'Mandatory|Administrators'
           foreach ($name in 'pwsh', 'powershell', 'cmd', 'python') {
             $command = Get-Command $name -ErrorAction SilentlyContinue
-            if ($null -eq $command) { "$name: not found"; continue }
+            if ($null -eq $command) { "${name}: not found"; continue }
             $bytes = [IO.File]::ReadAllBytes($command.Source)
             $offset = [BitConverter]::ToInt32($bytes, 0x3C)
             $machine = [BitConverter]::ToUInt16($bytes, $offset + 4)
             "{0}: {1} machine={2:x4}" -f $name, $command.Source, $machine
           }
           python -c "import platform, sys; print(sys.version, platform.machine())"
-      - name: ConPTY smoke with an ordinary token
-        if: always()
-        shell: pwsh
-        run: python scripts/conformance/windows_standard_user.py scripts/conformance/conpty_smoke.py --runtime diagnostic-runtime/runtime --output diagnostic-output/smoke-ordinary.json
-      - name: ConPTY smoke with the runner token
-        if: always()
-        shell: pwsh
-        run: python scripts/conformance/conpty_smoke.py --runtime diagnostic-runtime/runtime --output diagnostic-output/smoke-runner.json
       - name: Conformance with the side-loaded runtime
         if: always()
         shell: pwsh
@@ -82,6 +74,14 @@ jobs:
           Copy-Item -Recurse diagnostic-runtime diagnostic-runtime-inbox
           Remove-Item diagnostic-runtime-inbox/runtime/conpty.dll, diagnostic-runtime-inbox/runtime/OpenConsole.exe
           python scripts/conformance/windows_standard_user.py scripts/conformance/run.py --app diagnostic-runtime-inbox/pebrel.exe --platform windows-aarch64 --output diagnostic-output/inbox/windows-arm64-report.json --no-platform-golden
+      - name: ConPTY smoke with an ordinary token
+        if: always()
+        shell: pwsh
+        run: python scripts/conformance/windows_standard_user.py scripts/conformance/conpty_smoke.py --runtime diagnostic-runtime/runtime --wait 25 --prompt-script "$env:TEMP/pebrel_prompt.ps1" --output diagnostic-output/smoke-ordinary.json
+      - name: ConPTY smoke with the runner token
+        if: always()
+        shell: pwsh
+        run: python scripts/conformance/conpty_smoke.py --runtime diagnostic-runtime/runtime --wait 25 --prompt-script "$env:TEMP/pebrel_prompt.ps1" --output diagnostic-output/smoke-runner.json
       - uses: actions/upload-artifact@v4
         if: always()
         with:
diff --git a/scripts/conformance/conpty_smoke.py b/scripts/conformance/conpty_smoke.py
index cfad172..8b6f1ee 100644
--- a/scripts/conformance/conpty_smoke.py
+++ b/scripts/conformance/conpty_smoke.py
@@ -82,7 +82,14 @@ def api(library: str | None) -> tuple[CreateFn, CloseFn, str]:
     return create, close, library or "kernel32"
 
 
-def run_case(library: str | None, command: str, flags: int, wait_seconds: float) -> dict[str, object]:
+def run_case(
+    library: str | None,
+    command: str,
+    flags: int,
+    wait_seconds: float,
+    done_marker: bytes = b"CONPTY_SMOKE_OK",
+) -> dict[str, object]:
+    """Interactive shells never exit; the marker ends the wait once it renders."""
     result: dict[str, object] = {"library": library or "kernel32", "command": command, "flags": flags}
     try:
         create, close, _ = api(library)
@@ -142,11 +149,16 @@ def run_case(library: str | None, command: str, flags: int, wait_seconds: float)
     thread.start()
     deadline = time.monotonic() + wait_seconds
     first_output_ms: int | None = None
+    marker_ms: int | None = None
     while time.monotonic() < deadline:
         if chunks and first_output_ms is None:
             first_output_ms = round((time.monotonic() - started) * 1000)
+        if marker_ms is None and done_marker in b"".join(chunks):
+            marker_ms = round((time.monotonic() - started) * 1000)
+            break
         if kernel.WaitForSingleObject(process.hProcess, 100) == 0:
             break
+    result["marker_ms"] = marker_ms
     code = wt.DWORD()
     kernel.GetExitCodeProcess(process.hProcess, ctypes.byref(code))
     if code.value == 259:  # STILL_ACTIVE
@@ -178,7 +190,13 @@ def main() -> int:
     parser.add_argument("--runtime", help="directory holding conpty.dll and OpenConsole.exe")
     parser.add_argument("--wait", type=float, default=15.0)
     parser.add_argument("--output")
+    parser.add_argument(
+        "--prompt-script",
+        help="also start Windows PowerShell interactively with this integration script, like Pebrel does",
+    )
     args = parser.parse_args()
+    # Terminal bytes include private-use glyphs that legacy code pages reject.
+    sys.stdout.reconfigure(encoding="utf-8", errors="replace")
 
     shells = []
     for name in ("pwsh", "powershell", "cmd"):
@@ -207,6 +225,23 @@ def main() -> int:
                 case["shell"] = name
                 print(json.dumps(case, ensure_ascii=False), flush=True)
                 report["cases"].append(case)
+        powershell = dict(shells).get("powershell")
+        if args.prompt_script and powershell:
+            # The prompt function emits OSC 133;A once PowerShell reaches its
+            # first interactive prompt; a bare interactive shell shows "PS ".
+            script = os.path.abspath(args.prompt_script)
+            interactive = {
+                "powershell-interactive": (f'"{powershell}" -NoLogo -NoExit', b"PS "),
+                "powershell-integration": (
+                    f'"{powershell}" -NoLogo -NoExit -ExecutionPolicy Bypass -Command ". \'{script}\'"',
+                    b"133;A",
+                ),
+            }
+            for name, (command, marker) in interactive.items():
+                case = run_case(library, command, PSEUDOCONSOLE_WIN32_INPUT_MODE, args.wait, marker)
+                case["shell"] = name
+                print(json.dumps(case, ensure_ascii=False), flush=True)
+                report["cases"].append(case)
     if args.output:
         os.makedirs(os.path.dirname(os.path.abspath(args.output)), exist_ok=True)
         with open(args.output, "w", encoding="utf-8") as handle: