fix(shell): address Windows backspace and TUI shell regressions

frontend/terminal/src/components/PromptInput.tsx

@@ -59,16 +59,7 @@ function MultilineTextInput({
 				return;
 			}
 
-			if (key.backspace || key.delete) {
-				if (key.delete) {
-					if (cursorOffset >= value.length) {
-						return;
-					}
-					const nextValue = value.slice(0, cursorOffset) + value.slice(cursorOffset + 1);
-					onChange(nextValue);
-					return;
-				}
-
+			if (key.backspace) {
 				if (cursorOffset === 0) {
 					return;
 				}
@@ -78,6 +69,15 @@ function MultilineTextInput({
 				return;
 			}
 
+			if (key.delete) {
+				if (cursorOffset >= value.length) {
+					return;
+				}
+				const nextValue = value.slice(0, cursorOffset) + value.slice(cursorOffset + 1);
+				onChange(nextValue);
+				return;
+			}
+
 			if (!input) {
 				return;
 			}

src/openharness/tools/bash_tool.py

@@ -43,6 +43,7 @@ class BashTool(BaseTool):
                 arguments.command,
                 cwd=cwd,
                 prefer_pty=True,
+                stdin=asyncio.subprocess.DEVNULL,
                 stdout=asyncio.subprocess.PIPE,
                 stderr=asyncio.subprocess.STDOUT,
             )

src/openharness/utils/shell.py

@@ -34,14 +34,14 @@ def resolve_shell_command(
     if bash:
         argv = [bash, "-lc", command]
         if prefer_pty:
-            wrapped = _wrap_command_with_script(argv)
+            wrapped = _wrap_command_with_script(argv, platform_name=resolved_platform)
             if wrapped is not None:
                 return wrapped
         return argv
     shell = shutil.which("sh") or os.environ.get("SHELL") or "/bin/sh"
     argv = [shell, "-lc", command]
     if prefer_pty:
-        wrapped = _wrap_command_with_script(argv)
+        wrapped = _wrap_command_with_script(argv, platform_name=resolved_platform)
         if wrapped is not None:
             return wrapped
     return argv
@@ -104,7 +104,14 @@ async def create_shell_subprocess(
     return process
 
 
-def _wrap_command_with_script(argv: list[str]) -> list[str] | None:
+def _wrap_command_with_script(
+    argv: list[str],
+    *,
+    platform_name: PlatformName | None = None,
+) -> list[str] | None:
+    resolved_platform = platform_name or get_platform()
+    if resolved_platform == "macos":
+        return None
     script = shutil.which("script")
     if script is None:
         return None

tests/test_tools/test_bash_tool.py

@@ -154,3 +154,28 @@ async def test_bash_tool_collects_combined_output(monkeypatch, tmp_path: Path):
     assert result.is_error is False
     assert result.output == "line one\nline two"
     assert result.metadata["returncode"] == 0
+
+
+@pytest.mark.asyncio
+async def test_bash_tool_uses_devnull_stdin_for_non_interactive_shell(monkeypatch, tmp_path: Path):
+    process = _FakeProcess(
+        stdout=_FakeStdout([b"ok\n", b""]),
+        returncode=0,
+    )
+    seen_kwargs: dict[str, object] = {}
+
+    async def fake_create_shell_subprocess(*args, **kwargs):
+        del args
+        seen_kwargs.update(kwargs)
+        return process
+
+    monkeypatch.setattr("openharness.tools.bash_tool.create_shell_subprocess", fake_create_shell_subprocess)
+
+    result = await BashTool().execute(
+        BashToolInput(command="echo ok"),
+        ToolExecutionContext(cwd=tmp_path),
+    )
+
+    assert result.is_error is False
+    assert seen_kwargs["stdin"] == asyncio.subprocess.DEVNULL
+    assert seen_kwargs["prefer_pty"] is True

tests/test_utils/test_shell.py

@@ -49,3 +49,32 @@ def test_resolve_shell_command_uses_powershell_on_windows(monkeypatch):
         "-Command",
         "Write-Output hi",
     ]
+
+
+def test_resolve_shell_command_skips_script_on_macos(monkeypatch):
+    def fake_which(name: str) -> str | None:
+        mapping = {
+            "bash": "/bin/bash",
+            "script": "/usr/bin/script",
+        }
+        return mapping.get(name)
+
+    monkeypatch.setattr("openharness.utils.shell.shutil.which", fake_which)
+
+    command = resolve_shell_command("echo hi", platform_name="macos", prefer_pty=True)
+
+    assert command == ["/bin/bash", "-lc", "echo hi"]
+
+
+def test_resolve_shell_command_linux_without_script_falls_back(monkeypatch):
+    def fake_which(name: str) -> str | None:
+        mapping = {
+            "bash": "/usr/bin/bash",
+        }
+        return mapping.get(name)
+
+    monkeypatch.setattr("openharness.utils.shell.shutil.which", fake_which)
+
+    command = resolve_shell_command("echo hi", platform_name="linux", prefer_pty=True)
+
+    assert command == ["/usr/bin/bash", "-lc", "echo hi"]