feat: Add GPT-5 model variants and improve Codex execution logic. Addressed code review comments

apps/server/src/lib/git.ts

@@ -0,0 +1,82 @@
+/**
+ * Shared git command execution utilities.
+ *
+ * This module provides the canonical `execGitCommand` helper and common
+ * git utilities used across services and routes.  All consumers should
+ * import from here rather than defining their own copy.
+ */
+
+import { spawnProcess } from '@automaker/platform';
+
+// ============================================================================
+// Secure Command Execution
+// ============================================================================
+
+/**
+ * Execute git command with array arguments to prevent command injection.
+ * Uses spawnProcess from @automaker/platform for secure, cross-platform execution.
+ *
+ * @param args - Array of git command arguments (e.g., ['worktree', 'add', path])
+ * @param cwd - Working directory to execute the command in
+ * @param env - Optional additional environment variables to pass to the git process.
+ *   These are merged on top of the current process environment.  Pass
+ *   `{ LC_ALL: 'C' }` to force git to emit English output regardless of the
+ *   system locale so that text-based output parsing remains reliable.
+ * @returns Promise resolving to stdout output
+ * @throws Error with stderr/stdout message if command fails. The thrown error
+ *   also has `stdout` and `stderr` string properties for structured access.
+ *
+ * @example
+ * ```typescript
+ * // Safe: no injection possible
+ * await execGitCommand(['branch', '-D', branchName], projectPath);
+ *
+ * // Force English output for reliable text parsing:
+ * await execGitCommand(['rebase', '--', 'main'], worktreePath, { LC_ALL: 'C' });
+ *
+ * // Instead of unsafe:
+ * // await execAsync(`git branch -D ${branchName}`, { cwd });
+ * ```
+ */
+export async function execGitCommand(
+  args: string[],
+  cwd: string,
+  env?: Record<string, string>
+): Promise<string> {
+  const result = await spawnProcess({
+    command: 'git',
+    args,
+    cwd,
+    ...(env !== undefined ? { env } : {}),
+  });
+
+  // spawnProcess returns { stdout, stderr, exitCode }
+  if (result.exitCode === 0) {
+    return result.stdout;
+  } else {
+    const errorMessage =
+      result.stderr || result.stdout || `Git command failed with code ${result.exitCode}`;
+    throw Object.assign(new Error(errorMessage), {
+      stdout: result.stdout,
+      stderr: result.stderr,
+    });
+  }
+}
+
+// ============================================================================
+// Common Git Utilities
+// ============================================================================
+
+/**
+ * Get the current branch name for the given worktree.
+ *
+ * This is the canonical implementation shared across services.  Services
+ * should import this rather than duplicating the logic locally.
+ *
+ * @param worktreePath - Path to the git worktree
+ * @returns The current branch name (trimmed)
+ */
+export async function getCurrentBranch(worktreePath: string): Promise<string> {
+  const branchOutput = await execGitCommand(['rev-parse', '--abbrev-ref', 'HEAD'], worktreePath);
+  return branchOutput.trim();
+}