feat(stderr-debug): add logging utilities and enhance CLI execution error handling

Add comprehensive logging infrastructure through new logger utility module to improve debugging visibility:

- Create logger.ts with log(), logError(), logCommand(), and output channel management
- Add command execution logging before running CLI processes
- Log both stderr and stdout output from CLI execution (first 500 chars of stdout)
- Enhanced error handling with detailed stderr/stdout information in error messages
- Add "Show Logs" action to error dialogs to help users access debugging information
- Replace console.log with logger.log() in extension activation
- Update error type annotations to include stderr and stdout properties

Improvements enable better troubleshooting of CLI execution failures while maintaining extension reliability.

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>

Author: yamork779

src/cli/execution.ts

@@ -6,6 +6,7 @@ import * as path from "path";
 import * as os from "os";
 import { findClaudeCliPath } from "./detection";
 import { ProgressCallback, Model } from "../types";
+import { log, logError, logCommand } from "../utils/logger";
 
 const execAsync = promisify(exec);
 
@@ -43,12 +44,21 @@ export async function generateWithCLI(
         ? `type "${promptFile}" | ${escapedCliPath} -p --model ${model}`
         : `cat "${promptFile}" | ${escapedCliPath} -p --model ${model}`;
 
+    logCommand(command);
+
     const { stdout, stderr } = await execAsync(command, {
       shell: process.platform === "win32" ? "cmd.exe" : "/bin/bash",
       maxBuffer: 10 * 1024 * 1024,
       timeout: 120000,
     });
 
+    if (stderr) {
+      log(`CLI stderr: ${stderr.trim()}`);
+    }
+    if (stdout) {
+      log(`CLI stdout (first 500 chars): ${stdout.substring(0, 500)}`);
+    }
+
     if (stderr && !stdout) {
       throw new Error(`CLI error output: ${stderr.trim()}`);
     }
@@ -91,7 +101,7 @@ export async function generateWithCLI(
 
     return lines[lines.length - 1] || "chore: update code";
   } catch (error) {
-    const err = error as NodeJS.ErrnoException & { killed?: boolean };
+    const err = error as NodeJS.ErrnoException & { killed?: boolean; stderr?: string; stdout?: string };
     if (err.killed) {
       throw new Error(
         "CLI process timed out after 2 minutes. Try a smaller diff or check your connection."
@@ -100,7 +110,21 @@ export async function generateWithCLI(
     if (err.code === "ENOENT") {
       throw new Error(`CLI executable not found at: ${cliPath}`);
     }
-    throw error;
+    // Provide detailed error information for debugging
+    const stderr = err.stderr?.trim() || "";
+    const stdout = err.stdout?.trim() || "";
+    const details: string[] = [];
+    if (stderr) {
+      details.push(`stderr: ${stderr}`);
+    }
+    if (stdout) {
+      details.push(`stdout: ${stdout}`);
+    }
+    const baseMessage = err.message || String(error);
+    const detailStr = details.length > 0 ? ` [${details.join("; ")}]` : "";
+    const fullError = `CLI execution failed: ${baseMessage}${detailStr}`;
+    logError(fullError, error);
+    throw new Error(fullError);
   } finally {
     try {
       await fs.promises.unlink(promptFile);
@@ -144,20 +168,29 @@ export async function generateWithCLIManaged(
         ? `type "${promptFile}" | ${escapedCliPath} -p --model haiku`
         : `cat "${promptFile}" | ${escapedCliPath} -p --model haiku`;
 
+    logCommand(command);
+
     const { stdout, stderr } = await execAsync(command, {
       shell: process.platform === "win32" ? "cmd.exe" : "/bin/bash",
       maxBuffer: 10 * 1024 * 1024,
       timeout: 120000,
       cwd: repoPath,
     });
 
+    if (stderr) {
+      log(`CLI stderr: ${stderr.trim()}`);
+    }
+    if (stdout) {
+      log(`CLI stdout (first 500 chars): ${stdout.substring(0, 500)}`);
+    }
+
     if (stderr && !stdout) {
       throw new Error(`CLI error output: ${stderr.trim()}`);
     }
 
     return stdout.trim() || "chore: update code";
   } catch (error) {
-    const err = error as NodeJS.ErrnoException & { killed?: boolean };
+    const err = error as NodeJS.ErrnoException & { killed?: boolean; stderr?: string; stdout?: string };
     if (err.killed) {
       throw new Error(
         "CLI process timed out after 2 minutes. Try a smaller diff or check your connection."
@@ -166,7 +199,21 @@ export async function generateWithCLIManaged(
     if (err.code === "ENOENT") {
       throw new Error(`CLI executable not found at: ${cliPath}`);
     }
-    throw error;
+    // Provide detailed error information for debugging
+    const stderr = err.stderr?.trim() || "";
+    const stdout = err.stdout?.trim() || "";
+    const details: string[] = [];
+    if (stderr) {
+      details.push(`stderr: ${stderr}`);
+    }
+    if (stdout) {
+      details.push(`stdout: ${stdout}`);
+    }
+    const baseMessage = err.message || String(error);
+    const detailStr = details.length > 0 ? ` [${details.join("; ")}]` : "";
+    const fullError = `CLI execution failed: ${baseMessage}${detailStr}`;
+    logError(fullError, error);
+    throw new Error(fullError);
   } finally {
     try {
       await fs.promises.unlink(promptFile);

src/extension.ts

@@ -1,6 +1,7 @@
 import * as vscode from "vscode";
 import { generateCommitMessage, editCommitMessage } from "./generators/commit";
 import type { GitRepository, GitAPI, Language } from "./types";
+import { log, logError, showOutputChannel, disposeOutputChannel } from "./utils/logger";
 
 /**
  * Show an information message that auto-closes after a specified timeout.
@@ -105,7 +106,7 @@ function getActiveRepository(
 }
 
 export function activate(context: vscode.ExtensionContext): void {
-  console.log("Claude Commit extension is now active");
+  log("Claude Commit extension activated");
 
   const generateCommit = vscode.commands.registerCommand(
     "claude-commit.generate",
@@ -180,9 +181,14 @@ export function activate(context: vscode.ExtensionContext): void {
           const errorMessage = generationError instanceof Error
             ? generationError.message
             : String(generationError);
-          vscode.window.showErrorMessage(
-            `Failed to generate commit: ${errorMessage}`
+          logError("Failed to generate commit", generationError);
+          const action = await vscode.window.showErrorMessage(
+            `Failed to generate commit: ${errorMessage}`,
+            "Show Logs"
           );
+          if (action === "Show Logs") {
+            showOutputChannel();
+          }
           return;
         }
 
@@ -401,4 +407,6 @@ async function handleEditWithFeedback(
   );
 }
 
-export function deactivate(): void {}
+export function deactivate(): void {
+  disposeOutputChannel();
+}

src/utils/logger.ts

@@ -0,0 +1,49 @@
+import * as vscode from "vscode";
+
+let outputChannel: vscode.OutputChannel | undefined;
+
+export function getOutputChannel(): vscode.OutputChannel {
+  if (!outputChannel) {
+    outputChannel = vscode.window.createOutputChannel("Claude Commit");
+  }
+  return outputChannel;
+}
+
+export function log(message: string): void {
+  const channel = getOutputChannel();
+  const timestamp = new Date().toISOString();
+  channel.appendLine(`[${timestamp}] ${message}`);
+}
+
+export function logError(message: string, error?: unknown): void {
+  const channel = getOutputChannel();
+  const timestamp = new Date().toISOString();
+  channel.appendLine(`[${timestamp}] ERROR: ${message}`);
+  if (error) {
+    if (error instanceof Error) {
+      channel.appendLine(`  Message: ${error.message}`);
+      if (error.stack) {
+        channel.appendLine(`  Stack: ${error.stack}`);
+      }
+    } else {
+      channel.appendLine(`  Details: ${String(error)}`);
+    }
+  }
+}
+
+export function logCommand(command: string): void {
+  const channel = getOutputChannel();
+  const timestamp = new Date().toISOString();
+  channel.appendLine(`[${timestamp}] Executing: ${command}`);
+}
+
+export function showOutputChannel(): void {
+  getOutputChannel().show();
+}
+
+export function disposeOutputChannel(): void {
+  if (outputChannel) {
+    outputChannel.dispose();
+    outputChannel = undefined;
+  }
+}