fix: Address code review comments

apps/server/src/services/branch-commit-log-service.ts

@@ -0,0 +1,119 @@
+/**
+ * Service for fetching branch commit log data.
+ *
+ * Extracts the heavy Git command execution and parsing logic from the
+ * branch-commit-log route handler so the handler only validates input,
+ * invokes this service, streams lifecycle events, and sends the response.
+ */
+
+import { execGitCommand } from '../routes/worktree/common.js';
+
+// ============================================================================
+// Types
+// ============================================================================
+
+export interface BranchCommit {
+  hash: string;
+  shortHash: string;
+  author: string;
+  authorEmail: string;
+  date: string;
+  subject: string;
+  body: string;
+  files: string[];
+}
+
+export interface BranchCommitLogResult {
+  branch: string;
+  commits: BranchCommit[];
+  total: number;
+}
+
+// ============================================================================
+// Service
+// ============================================================================
+
+/**
+ * Fetch the commit log for a specific branch (or HEAD).
+ *
+ * Runs `git log`, `git diff-tree`, and `git rev-parse` inside
+ * the given worktree path and returns a structured result.
+ *
+ * @param worktreePath - Absolute path to the worktree / repository
+ * @param branchName   - Branch to query (omit or pass undefined for HEAD)
+ * @param limit        - Maximum number of commits to return (clamped 1-100)
+ */
+export async function getBranchCommitLog(
+  worktreePath: string,
+  branchName: string | undefined,
+  limit: number
+): Promise<BranchCommitLogResult> {
+  // Clamp limit to a reasonable range
+  const parsedLimit = Number(limit);
+  const commitLimit = Math.min(Math.max(1, Number.isFinite(parsedLimit) ? parsedLimit : 20), 100);
+
+  // Use the specified branch or default to HEAD
+  const targetRef = branchName || 'HEAD';
+
+  // Get detailed commit log for the specified branch
+  const logOutput = await execGitCommand(
+    [
+      'log',
+      targetRef,
+      `--max-count=${commitLimit}`,
+      '--format=%H%n%h%n%an%n%ae%n%aI%n%s%n%b%n---END---',
+    ],
+    worktreePath
+  );
+
+  // Parse the output into structured commit objects
+  const commits: BranchCommit[] = [];
+
+  const commitBlocks = logOutput.split('---END---\n').filter((block) => block.trim());
+
+  for (const block of commitBlocks) {
+    const lines = block.split('\n');
+    if (lines.length >= 6) {
+      const hash = lines[0].trim();
+
+      // Get list of files changed in this commit
+      let files: string[] = [];
+      try {
+        const filesOutput = await execGitCommand(
+          ['diff-tree', '--no-commit-id', '--name-only', '-r', hash],
+          worktreePath
+        );
+        files = filesOutput
+          .trim()
+          .split('\n')
+          .filter((f) => f.trim());
+      } catch {
+        // Ignore errors getting file list
+      }
+
+      commits.push({
+        hash,
+        shortHash: lines[1].trim(),
+        author: lines[2].trim(),
+        authorEmail: lines[3].trim(),
+        date: lines[4].trim(),
+        subject: lines[5].trim(),
+        body: lines.slice(6).join('\n').trim(),
+        files,
+      });
+    }
+  }
+
+  // If branchName wasn't specified, get current branch for display
+  let displayBranch = branchName;
+  if (!displayBranch) {
+    const branchOutput = await execGitCommand(['rev-parse', '--abbrev-ref', 'HEAD'], worktreePath);
+    displayBranch = branchOutput.trim();
+  }
+
+  return {
+    branch: displayBranch,
+    commits,
+    total: commits.length,
+  };
+}