fix: pass configured shell to PTY instead of hardcoding sh

The PTY runner hardcoded CommandBuilder::new("sh"), but on Windows the
user's shell might be a Git Bash absolute path that isn't on PATH. The
non-PTY path already uses the resolved shell from getShellConfig(). Now
the PTY path does the same, passing it through PtyStartOptions.shell.

crates/pi-natives/src/pty.rs

@@ -38,6 +38,9 @@ pub struct PtyStartOptions<'env> {
 	pub cols:       Option<u16>,
 	/// PTY row count.
 	pub rows:       Option<u16>,
+	/// Shell binary to use (e.g. "sh", "bash", or an absolute path).
+	/// Defaults to "sh" if not provided.
+	pub shell:      Option<String>,
 }
 
 /// Result of a PTY command run.
@@ -58,6 +61,7 @@ struct PtyRunConfig {
 	env:     Option<HashMap<String, String>>,
 	cols:    u16,
 	rows:    u16,
+	shell:   Option<String>,
 }
 
 enum ReaderEvent {
@@ -116,6 +120,7 @@ impl PtySession {
 			env:     options.env,
 			cols:    options.cols.unwrap_or(120).clamp(20, 400),
 			rows:    options.rows.unwrap_or(40).clamp(5, 200),
+			shell:   options.shell,
 		};
 		let ct = task::CancelToken::new(options.timeout_ms, options.signal);
 		let core = Arc::clone(&self.core);
@@ -247,7 +252,7 @@ fn run_pty_sync(
 			.map_err(|err| Error::from_reason(format!("Failed to open PTY: {err}")))?
 	};
 
-	let mut cmd = CommandBuilder::new("sh");
+	let mut cmd = CommandBuilder::new(config.shell.as_deref().unwrap_or("sh"));
 	cmd.arg("-lc");
 	cmd.arg(&config.command);
 	if let Some(cwd) = config.cwd.as_ref() {

packages/coding-agent/src/tools/bash-interactive.ts

@@ -297,6 +297,7 @@ export async function runInteractiveBashPty(
 	},
 ): Promise<BashInteractiveResult> {
 	const settings = await Settings.init();
+	const { shell: resolvedShell } = settings.getShellConfig();
 	const sink = new OutputSink({
 		artifactPath: options.artifactPath,
 		artifactId: options.artifactId,
@@ -363,6 +364,7 @@ export async function runInteractiveBashPty(
 						signal: options.signal,
 						cols,
 						rows,
+						shell: resolvedShell,
 					},
 					(err, chunk) => {
 						if (finished || err || !chunk) return;