feat: implement session management for image generation skills and add session handling functions

skills/baoyu-gemini-web/scripts/session-store.ts

@@ -0,0 +1,90 @@
+import { mkdir, readFile, writeFile, readdir, stat } from 'node:fs/promises';
+import path from 'node:path';
+import { resolveGeminiWebSessionsDir, resolveGeminiWebSessionPath } from './paths.js';
+
+export interface SessionMessage {
+  role: 'user' | 'assistant';
+  content: string;
+  timestamp: string;
+  error?: string;
+}
+
+export interface SessionData {
+  id: string;
+  metadata: unknown;
+  messages: SessionMessage[];
+  createdAt: string;
+  updatedAt: string;
+}
+
+export interface SessionListItem {
+  id: string;
+  updatedAt: string;
+}
+
+export async function readSession(id: string): Promise<SessionData | null> {
+  const sessionPath = resolveGeminiWebSessionPath(id);
+  try {
+    const content = await readFile(sessionPath, 'utf8');
+    return JSON.parse(content) as SessionData;
+  } catch {
+    return null;
+  }
+}
+
+export async function writeSession(
+  id: string,
+  metadata: unknown,
+  userMessage: string,
+  assistantMessage: string,
+  error?: string,
+): Promise<void> {
+  const sessionPath = resolveGeminiWebSessionPath(id);
+  const sessionsDir = resolveGeminiWebSessionsDir();
+  await mkdir(sessionsDir, { recursive: true });
+
+  const existing = await readSession(id);
+  const now = new Date().toISOString();
+
+  const newMessages: SessionMessage[] = [
+    { role: 'user', content: userMessage, timestamp: now },
+    { role: 'assistant', content: assistantMessage, timestamp: now, ...(error && { error }) },
+  ];
+
+  const data: SessionData = {
+    id,
+    metadata,
+    messages: [...(existing?.messages ?? []), ...newMessages],
+    createdAt: existing?.createdAt ?? now,
+    updatedAt: now,
+  };
+  await writeFile(sessionPath, JSON.stringify(data, null, 2));
+}
+
+export async function listSessions(limit = 100): Promise<SessionListItem[]> {
+  const sessionsDir = resolveGeminiWebSessionsDir();
+  try {
+    const files = await readdir(sessionsDir);
+    const jsonFiles = files.filter((f) => f.endsWith('.json'));
+
+    const items: { id: string; updatedAt: string; mtime: number }[] = [];
+    for (const file of jsonFiles) {
+      const filePath = path.join(sessionsDir, file);
+      try {
+        const stats = await stat(filePath);
+        items.push({
+          id: file.slice(0, -5),
+          updatedAt: stats.mtime.toISOString(),
+          mtime: stats.mtime.getTime(),
+        });
+      } catch {
+        continue;
+      }
+    }
+
+    items.sort((a, b) => b.mtime - a.mtime);
+    return items.slice(0, limit).map(({ id, updatedAt }) => ({ id, updatedAt }));
+  } catch {
+    return [];
+  }
+}