fix(coding-agent): resolve shell config from session settings

Stop shell resolution from consulting ambient process.cwd() during bash execution and use the active session's shellPath setting instead.

closes #3452

packages/coding-agent/src/utils/shell.ts

@@ -1,10 +1,12 @@
 import { existsSync } from "node:fs";
 import { delimiter } from "node:path";
 import { spawn, spawnSync } from "child_process";
-import { getBinDir, getSettingsPath } from "../config.js";
-import { SettingsManager } from "../core/settings-manager.js";
+import { getBinDir } from "../config.js";
 
-let cachedShellConfig: { shell: string; args: string[] } | null = null;
+export interface ShellConfig {
+	shell: string;
+	args: string[];
+}
 
 /**
  * Find bash executable on PATH (cross-platform)
@@ -42,29 +44,19 @@ function findBashOnPath(): string | null {
 }
 
 /**
- * Get shell configuration based on platform.
+ * Resolve shell configuration based on platform and an optional explicit shell path.
  * Resolution order:
- * 1. User-specified shellPath in settings.json
+ * 1. User-specified shellPath
  * 2. On Windows: Git Bash in known locations, then bash on PATH
  * 3. On Unix: /bin/bash, then bash on PATH, then fallback to sh
  */
-export function getShellConfig(): { shell: string; args: string[] } {
-	if (cachedShellConfig) {
-		return cachedShellConfig;
-	}
-
-	const settings = SettingsManager.create(process.cwd());
-	const customShellPath = settings.getShellPath();
-
+export function getShellConfig(customShellPath?: string): ShellConfig {
 	// 1. Check user-specified shell path
 	if (customShellPath) {
 		if (existsSync(customShellPath)) {
-			cachedShellConfig = { shell: customShellPath, args: ["-c"] };
-			return cachedShellConfig;
+			return { shell: customShellPath, args: ["-c"] };
 		}
-		throw new Error(
-			`Custom shell path not found: ${customShellPath}\nPlease update shellPath in ${getSettingsPath()}`,
-		);
+		throw new Error(`Custom shell path not found: ${customShellPath}`);
 	}
 
 	if (process.platform === "win32") {
@@ -81,41 +73,36 @@ export function getShellConfig(): { shell: string; args: string[] } {
 
 		for (const path of paths) {
 			if (existsSync(path)) {
-				cachedShellConfig = { shell: path, args: ["-c"] };
-				return cachedShellConfig;
+				return { shell: path, args: ["-c"] };
 			}
 		}
 
 		// 3. Fallback: search bash.exe on PATH (Cygwin, MSYS2, WSL, etc.)
 		const bashOnPath = findBashOnPath();
 		if (bashOnPath) {
-			cachedShellConfig = { shell: bashOnPath, args: ["-c"] };
-			return cachedShellConfig;
+			return { shell: bashOnPath, args: ["-c"] };
 		}
 
 		throw new Error(
 			`No bash shell found. Options:\n` +
 				`  1. Install Git for Windows: https://git-scm.com/download/win\n` +
 				`  2. Add your bash to PATH (Cygwin, MSYS2, etc.)\n` +
-				`  3. Set shellPath in ${getSettingsPath()}\n\n` +
+				"  3. Set shellPath in settings.json\n\n" +
 				`Searched Git Bash in:\n${paths.map((p) => `  ${p}`).join("\n")}`,
 		);
 	}
 
 	// Unix: try /bin/bash, then bash on PATH, then fallback to sh
 	if (existsSync("/bin/bash")) {
-		cachedShellConfig = { shell: "/bin/bash", args: ["-c"] };
-		return cachedShellConfig;
+		return { shell: "/bin/bash", args: ["-c"] };
 	}
 
 	const bashOnPath = findBashOnPath();
 	if (bashOnPath) {
-		cachedShellConfig = { shell: bashOnPath, args: ["-c"] };
-		return cachedShellConfig;
+		return { shell: bashOnPath, args: ["-c"] };
 	}
 
-	cachedShellConfig = { shell: "sh", args: ["-c"] };
-	return cachedShellConfig;
+	return { shell: "sh", args: ["-c"] };
 }
 
 export function getShellEnv(): NodeJS.ProcessEnv {