feat: enhance list command with last modified timestamps and sorting

- Add lastModified field showing when each change was last modified
- Default sort order is now "recent" (most recently modified first)
- Add --sort option to choose between "recent" and "name" ordering
- Add --json option for programmatic access with structured output
- Fall back to directory mtime for empty change directories
- Display relative time (e.g., "2h ago", "3d ago") in human output

src/cli/index.ts

@@ -96,11 +96,14 @@ program
   .description('List items (changes by default). Use --specs to list specs.')
   .option('--specs', 'List specs instead of changes')
   .option('--changes', 'List changes explicitly (default)')
-  .action(async (options?: { specs?: boolean; changes?: boolean }) => {
+  .option('--sort <order>', 'Sort order: "recent" (default) or "name"', 'recent')
+  .option('--json', 'Output as JSON (for programmatic use)')
+  .action(async (options?: { specs?: boolean; changes?: boolean; sort?: string; json?: boolean }) => {
     try {
       const listCommand = new ListCommand();
       const mode: 'changes' | 'specs' = options?.specs ? 'specs' : 'changes';
-      await listCommand.execute('.', mode);
+      const sort = options?.sort === 'name' ? 'name' : 'recent';
+      await listCommand.execute('.', mode, { sort, json: options?.json });
     } catch (error) {
       console.log(); // Empty line for spacing
       ora().fail(`Error: ${(error as Error).message}`);

src/core/list.ts

@@ -9,13 +9,78 @@ interface ChangeInfo {
   name: string;
   completedTasks: number;
   totalTasks: number;
+  lastModified: Date;
+}
+
+interface ListOptions {
+  sort?: 'recent' | 'name';
+  json?: boolean;
+}
+
+/**
+ * Get the most recent modification time of any file in a directory (recursive).
+ * Falls back to the directory's own mtime if no files are found.
+ */
+async function getLastModified(dirPath: string): Promise<Date> {
+  let latest: Date | null = null;
+
+  async function walk(dir: string): Promise<void> {
+    const entries = await fs.readdir(dir, { withFileTypes: true });
+    for (const entry of entries) {
+      const fullPath = path.join(dir, entry.name);
+      if (entry.isDirectory()) {
+        await walk(fullPath);
+      } else {
+        const stat = await fs.stat(fullPath);
+        if (latest === null || stat.mtime > latest) {
+          latest = stat.mtime;
+        }
+      }
+    }
+  }
+
+  await walk(dirPath);
+
+  // If no files found, use the directory's own modification time
+  if (latest === null) {
+    const dirStat = await fs.stat(dirPath);
+    return dirStat.mtime;
+  }
+
+  return latest;
+}
+
+/**
+ * Format a date as relative time (e.g., "2 hours ago", "3 days ago")
+ */
+function formatRelativeTime(date: Date): string {
+  const now = new Date();
+  const diffMs = now.getTime() - date.getTime();
+  const diffSecs = Math.floor(diffMs / 1000);
+  const diffMins = Math.floor(diffSecs / 60);
+  const diffHours = Math.floor(diffMins / 60);
+  const diffDays = Math.floor(diffHours / 24);
+
+  if (diffDays > 30) {
+    return date.toLocaleDateString();
+  } else if (diffDays > 0) {
+    return `${diffDays}d ago`;
+  } else if (diffHours > 0) {
+    return `${diffHours}h ago`;
+  } else if (diffMins > 0) {
+    return `${diffMins}m ago`;
+  } else {
+    return 'just now';
+  }
 }
 
 export class ListCommand {
-  async execute(targetPath: string = '.', mode: 'changes' | 'specs' = 'changes'): Promise<void> {
+  async execute(targetPath: string = '.', mode: 'changes' | 'specs' = 'changes', options: ListOptions = {}): Promise<void> {
+    const { sort = 'recent', json = false } = options;
+
     if (mode === 'changes') {
       const changesDir = path.join(targetPath, 'openspec', 'changes');
-      
+
       // Check if changes directory exists
       try {
         await fs.access(changesDir);
@@ -30,24 +95,48 @@ export class ListCommand {
         .map(entry => entry.name);
 
       if (changeDirs.length === 0) {
-        console.log('No active changes found.');
+        if (json) {
+          console.log(JSON.stringify({ changes: [] }));
+        } else {
+          console.log('No active changes found.');
+        }
         return;
       }
 
       // Collect information about each change
       const changes: ChangeInfo[] = [];
-      
+
       for (const changeDir of changeDirs) {
         const progress = await getTaskProgressForChange(changesDir, changeDir);
+        const changePath = path.join(changesDir, changeDir);
+        const lastModified = await getLastModified(changePath);
         changes.push({
           name: changeDir,
           completedTasks: progress.completed,
-          totalTasks: progress.total
+          totalTasks: progress.total,
+          lastModified
         });
       }
 
-      // Sort alphabetically by name
-      changes.sort((a, b) => a.name.localeCompare(b.name));
+      // Sort by preference (default: recent first)
+      if (sort === 'recent') {
+        changes.sort((a, b) => b.lastModified.getTime() - a.lastModified.getTime());
+      } else {
+        changes.sort((a, b) => a.name.localeCompare(b.name));
+      }
+
+      // JSON output for programmatic use
+      if (json) {
+        const jsonOutput = changes.map(c => ({
+          name: c.name,
+          completedTasks: c.completedTasks,
+          totalTasks: c.totalTasks,
+          lastModified: c.lastModified.toISOString(),
+          status: c.totalTasks === 0 ? 'no-tasks' : c.completedTasks === c.totalTasks ? 'complete' : 'in-progress'
+        }));
+        console.log(JSON.stringify({ changes: jsonOutput }, null, 2));
+        return;
+      }
 
       // Display results
       console.log('Changes:');
@@ -56,7 +145,8 @@ export class ListCommand {
       for (const change of changes) {
         const paddedName = change.name.padEnd(nameWidth);
         const status = formatTaskStatus({ total: change.totalTasks, completed: change.completedTasks });
-        console.log(`${padding}${paddedName}     ${status}`);
+        const timeAgo = formatRelativeTime(change.lastModified);
+        console.log(`${padding}${paddedName}     ${status.padEnd(12)}  ${timeAgo}`);
       }
       return;
     }