address comments

Author: eleanorjboyd

src/extension.ts

@@ -95,7 +95,11 @@ import { collectEnvironmentInfo, getEnvManagerAndPackageManagerConfigLevels, run
 import { EnvironmentManagers, ProjectCreators, PythonProjectManager } from './internal.api';
 import { registerSystemPythonFeatures } from './managers/builtin/main';
 import { SysPythonManager } from './managers/builtin/sysPythonManager';
-import { createNativePythonFinder, NativePythonFinder } from './managers/common/nativePythonFinder';
+import {
+    createNativePythonFinder,
+    NativePythonFinder,
+    PetBinaryNotFoundError,
+} from './managers/common/nativePythonFinder';
 import { IDisposable } from './managers/common/types';
 import { registerCondaFeatures } from './managers/conda/main';
 import { registerPipenvFeatures } from './managers/pipenv/main';
@@ -530,21 +534,32 @@ export async function activate(context: ExtensionContext): Promise<PythonEnviron
             traceError('Failed to start Python finder (pet):', error);
 
             const errnoError = error as NodeJS.ErrnoException;
-            // Plain Error (no .code) = binary not found by getNativePythonToolsPath.
-            // Errno error (has .code) = spawn failed (ENOENT, EACCES, EPERM, etc.).
-            const reason = errnoError.code ? 'spawn_failed' : 'binary_not_found';
+            // PetBinaryNotFoundError = file missing; errno .code = OS spawn failure; anything else = unknown.
+            const reason =
+                error instanceof PetBinaryNotFoundError
+                    ? 'binary_not_found'
+                    : errnoError.code
+                      ? 'spawn_failed'
+                      : 'unknown';
             sendTelemetryEvent(EventNames.PET_START_FAILED, undefined, {
                 errorCode: errnoError.code ?? 'UNKNOWN',
                 reason,
                 platform: process.platform,
                 arch: process.arch,
             });
 
-            window.showErrorMessage(
-                l10n.t(
-                    'Python Environments: Failed to start the Python finder. Some features may not work correctly. Check the Output panel for details.',
-                ),
+            const openOutput = l10n.t('Open Output');
+            const openSettings = l10n.t('Open Settings');
+            const choice = await window.showErrorMessage(
+                l10n.t('Python Environments: Failed to start the Python finder. Some features may not work correctly.'),
+                openOutput,
+                openSettings,
             );
+            if (choice === openOutput) {
+                outputChannel.show();
+            } else if (choice === openSettings) {
+                await commands.executeCommand('workbench.action.openSettings', 'python.defaultInterpreterPath');
+            }
             return;
         }
 

src/managers/common/nativePythonFinder.ts

@@ -76,6 +76,13 @@ export class ConfigureRetryState {
     }
 }
 
+export class PetBinaryNotFoundError extends Error {
+    constructor(message: string) {
+        super(message);
+        this.name = 'PetBinaryNotFoundError';
+    }
+}
+
 export async function getNativePythonToolsPath(): Promise<string> {
     const envsExt = getExtension(ENVS_EXTENSION_ID);
     if (envsExt) {
@@ -91,14 +98,14 @@ export async function getNativePythonToolsPath(): Promise<string> {
 
     const python = getExtension(PYTHON_EXTENSION_ID);
     if (!python) {
-        throw new Error('Python extension not found and envs extension pet binary is missing');
+        throw new PetBinaryNotFoundError('Python extension not found and envs extension pet binary is missing');
     }
 
     const fallbackPath = path.join(python.extensionPath, 'python-env-tools', 'bin', isWindows() ? 'pet.exe' : 'pet');
     const fallbackExists = await fs.pathExists(fallbackPath);
     traceVerbose(`[pet] Fallback path (python-ext): ${fallbackPath} — exists: ${fallbackExists}`);
     if (!fallbackExists) {
-        throw new Error(`Python finder binary not found at: ${fallbackPath}`);
+        throw new PetBinaryNotFoundError(`Python finder binary not found at: ${fallbackPath}`);
     }
     return fallbackPath;
 }
@@ -490,7 +497,7 @@ class NativePythonFinderImpl implements NativePythonFinder {
             this.proc.on('exit', (code, signal) => {
                 this.processExited = true;
                 const wasExpected = this.isRestarting || this.isDisposed;
-                if (code !== 0) {
+                if (!wasExpected && code !== 0) {
                     this.outputChannel.error(
                         `[pet] Python Environment Tools exited unexpectedly with code ${code}, signal ${signal}`,
                     );