✨ feat: add session memory tools with semantic search and logging

Adds comprehensive session memory management with the following tools:
- start_logging_session: Begin logging a session with optional name
- log_message: Log user/agent messages to active sessions
- search_session: Semantic search within a specific session
- search_all_sessions: Semantic search across all logged sessions
- list_sessions: List all sessions with optional active filter
- get_session: Get session details and messages
- end_session: End session with optional summary
Database schema includes:
- sessions table with name, timestamps, summary, and active status
- session_messages table with role, content, and creation time
- Proper indexes for performance
- Foreign key relationships
All tools support semantic search using the existing embedding model.

README.md

@@ -54,6 +54,8 @@ bun run mcp  # Start MCP server
 
 ## 🛠️ MCP Tools
 
+### Knowledge Tools
+
 | Tool                    | Description                                    |
 | :---------------------- | :--------------------------------------------- |
 | `store_knowledge`       | Store a new knowledge entry with optional tags |
@@ -65,6 +67,20 @@ bun run mcp  # Start MCP server
 | `list_knowledge`        | List entries with filters                      |
 | `get_knowledge_stats`   | Database statistics                            |
 
+### Session Memory Tools
+
+Log and search across entire OpenCode sessions.
+
+| Tool                    | Description                                    |
+| :---------------------- | :--------------------------------------------- |
+| `start_logging_session` | Begin logging a session                        |
+| `log_message`           | Log a user/agent message to the session        |
+| `search_session`        | Semantic search within a session               |
+| `search_all_sessions`   | Search across ALL logged sessions              |
+| `list_sessions`         | List all sessions                              |
+| `get_session`           | Get session details and messages               |
+| `end_session`           | End session with optional summary              |
+
 ## 📖 Example Usage
 
 ### Storing Knowledge
@@ -91,6 +107,30 @@ Found 1 similar entry:
 Opencode is an open source AI coding agent...
 ```
 
+### Session Memory
+
+**User:** "Start logging this session, call it 'auth debugging'"
+
+**Agent:** Starts session and logs all exchanges:
+
+```
+✅ Started session #1: "auth debugging"
+```
+
+**User:** "Search this session for JWT"
+
+**Agent:** Returns semantic matches from the session:
+
+```
+Found 2 matches in session #1:
+
+### 1. [user] (92% match)
+The JWT token expires too fast...
+
+### 2. [agent] (88% match)
+The TTL is set to 60 instead of 3600...
+```
+
 ## ⚙️ Configuration
 
 ### Data Location

src/database/index.ts

@@ -30,6 +30,41 @@ export interface KnowledgeRecord {
   updated_at: string;
 }
 
+// Session types for session memory feature
+export interface Session {
+  id: number;
+  name: string | null;
+  started_at: string;
+  ended_at: string | null;
+  summary: string | null;
+  is_active: boolean;
+}
+
+export interface SessionMessage {
+  id: number;
+  session_id: number;
+  role: "user" | "agent";
+  content: string;
+  created_at: string;
+}
+
+interface SessionRecord {
+  id: number;
+  name: string | null;
+  started_at: string;
+  ended_at: string | null;
+  summary: string | null;
+  is_active: number;
+}
+
+interface SessionMessageRecord {
+  id: number;
+  session_id: number;
+  role: string;
+  content: string;
+  created_at: string;
+}
+
 let db: Database | null = null;
 
 /**
@@ -62,9 +97,33 @@ export function initDatabase(): Database {
     )
   `);
 
+  // Session tables for session memory feature
+  db.run(`
+    CREATE TABLE IF NOT EXISTS sessions (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      name TEXT,
+      started_at TEXT NOT NULL,
+      ended_at TEXT,
+      summary TEXT,
+      is_active INTEGER DEFAULT 1
+    )
+  `);
+
+  db.run(`
+    CREATE TABLE IF NOT EXISTS session_messages (
+      id INTEGER PRIMARY KEY AUTOINCREMENT,
+      session_id INTEGER NOT NULL REFERENCES sessions(id),
+      role TEXT NOT NULL,
+      content TEXT NOT NULL,
+      created_at TEXT NOT NULL
+    )
+  `);
+
   // Create indexes
   db.run(`CREATE INDEX IF NOT EXISTS idx_tags ON knowledge_entries(tags)`);
   db.run(`CREATE INDEX IF NOT EXISTS idx_created ON knowledge_entries(created_at)`);
+  db.run(`CREATE INDEX IF NOT EXISTS idx_session_messages ON session_messages(session_id)`);
+  db.run(`CREATE INDEX IF NOT EXISTS idx_sessions_active ON sessions(is_active)`);
 
   return db;
 }
@@ -92,9 +151,9 @@ export function saveKnowledgeEntry(entry: Omit<KnowledgeEntry, "id" | "created_a
 export function getKnowledgeEntry(id: number): KnowledgeEntry | null {
   const database = initDatabase();
   const record = database.prepare("SELECT * FROM knowledge_entries WHERE id = ?").get(id) as KnowledgeRecord | undefined;
-  
+
   if (!record) return null;
-  
+
   return {
     id: record.id,
     title: record.title,
@@ -184,18 +243,18 @@ export function listKnowledgeEntries(options: {
  */
 export function searchKnowledgeByText(query: string, limit = 10): KnowledgeEntry[] {
   const database = initDatabase();
-  
+
   // Split query into words for OR search
   const words = query.toLowerCase().split(/\s+/).filter(w => w.length > 2);
-  
+
   if (words.length === 0) {
     return [];
   }
 
-  const conditions = words.map(() => 
+  const conditions = words.map(() =>
     "(LOWER(title) LIKE ? OR LOWER(content) LIKE ?)"
   ).join(" OR ");
-  
+
   const params = words.flatMap(w => [`%${w}%`, `%${w}%`]);
 
   const records = database.prepare(`
@@ -246,14 +305,14 @@ export function getStats(): {
   const database = initDatabase();
 
   const countResult = database.prepare("SELECT COUNT(*) as count FROM knowledge_entries").get() as { count: number };
-  
+
   const oldest = database.prepare("SELECT MIN(created_at) as oldest FROM knowledge_entries").get() as { oldest: string | null };
   const newest = database.prepare("SELECT MAX(created_at) as newest FROM knowledge_entries").get() as { newest: string | null };
 
   // Count tags
   const allTags = database.prepare("SELECT tags FROM knowledge_entries WHERE tags IS NOT NULL").all() as { tags: string }[];
   const tagCounts: Record<string, number> = {};
-  
+
   for (const row of allTags) {
     const tags = JSON.parse(row.tags) as string[];
     for (const tag of tags) {
@@ -269,6 +328,183 @@ export function getStats(): {
   };
 }
 
+// ============================================================================
+// Session Memory Functions
+// ============================================================================
+
+const SESSION_TIMEOUT_MS = 60 * 60 * 1000; // 1 hour
+
+/**
+ * Create a new session.
+ */
+export function createSession(name?: string): number {
+  const database = initDatabase();
+  const now = new Date().toISOString();
+
+  const stmt = database.prepare(`
+    INSERT INTO sessions (name, started_at, is_active)
+    VALUES (?, ?, 1)
+  `);
+
+  const result = stmt.run(name || null, now);
+  return Number(result.lastInsertRowid);
+}
+
+/**
+ * Get a session by ID.
+ */
+export function getSession(id: number): Session | null {
+  const database = initDatabase();
+  const record = database.prepare("SELECT * FROM sessions WHERE id = ?").get(id) as SessionRecord | undefined;
+
+  if (!record) return null;
+
+  return {
+    id: record.id,
+    name: record.name,
+    started_at: record.started_at,
+    ended_at: record.ended_at,
+    summary: record.summary,
+    is_active: record.is_active === 1,
+  };
+}
+
+/**
+ * Get the current active session (most recent).
+ */
+export function getActiveSession(): Session | null {
+  const database = initDatabase();
+  const record = database.prepare(
+    "SELECT * FROM sessions WHERE is_active = 1 ORDER BY id DESC LIMIT 1"
+  ).get() as SessionRecord | undefined;
+
+  if (!record) return null;
+
+  return {
+    id: record.id,
+    name: record.name,
+    started_at: record.started_at,
+    ended_at: record.ended_at,
+    summary: record.summary,
+    is_active: record.is_active === 1,
+  };
+}
+
+/**
+ * End a session.
+ */
+export function endSession(id: number, summary?: string): boolean {
+  const database = initDatabase();
+  const now = new Date().toISOString();
+
+  const stmt = database.prepare(`
+    UPDATE sessions 
+    SET ended_at = ?, summary = ?, is_active = 0
+    WHERE id = ?
+  `);
+
+  const result = stmt.run(now, summary || null, id);
+  return result.changes > 0;
+}
+
+/**
+ * Save a message to a session.
+ */
+export function saveSessionMessage(sessionId: number, role: "user" | "agent", content: string): number {
+  const database = initDatabase();
+  const now = new Date().toISOString();
+
+  const stmt = database.prepare(`
+    INSERT INTO session_messages (session_id, role, content, created_at)
+    VALUES (?, ?, ?, ?)
+  `);
+
+  const result = stmt.run(sessionId, role, content, now);
+  return Number(result.lastInsertRowid);
+}
+
+/**
+ * Get all messages for a session.
+ */
+export function getSessionMessages(sessionId: number): SessionMessage[] {
+  const database = initDatabase();
+  const records = database.prepare(
+    "SELECT * FROM session_messages WHERE session_id = ? ORDER BY created_at ASC"
+  ).all(sessionId) as SessionMessageRecord[];
+
+  return records.map(record => ({
+    id: record.id,
+    session_id: record.session_id,
+    role: record.role as "user" | "agent",
+    content: record.content,
+    created_at: record.created_at,
+  }));
+}
+
+/**
+ * List all sessions.
+ */
+export function listSessions(options: { limit?: number; offset?: number; activeOnly?: boolean } = {}): Session[] {
+  const database = initDatabase();
+  const { limit = 20, offset = 0, activeOnly = false } = options;
+
+  let sql = "SELECT * FROM sessions";
+  if (activeOnly) {
+    sql += " WHERE is_active = 1";
+  }
+  sql += " ORDER BY started_at DESC LIMIT ? OFFSET ?";
+
+  const records = database.prepare(sql).all(limit, offset) as SessionRecord[];
+
+  return records.map(record => ({
+    id: record.id,
+    name: record.name,
+    started_at: record.started_at,
+    ended_at: record.ended_at,
+    summary: record.summary,
+    is_active: record.is_active === 1,
+  }));
+}
+
+/**
+ * Get session message count.
+ */
+export function getSessionMessageCount(sessionId: number): number {
+  const database = initDatabase();
+  const result = database.prepare(
+    "SELECT COUNT(*) as count FROM session_messages WHERE session_id = ?"
+  ).get(sessionId) as { count: number };
+  return result.count;
+}
+
+/**
+ * Close timed-out sessions (inactive for more than 1 hour).
+ */
+export function closeTimedOutSessions(): number {
+  const database = initDatabase();
+  const cutoff = new Date(Date.now() - SESSION_TIMEOUT_MS).toISOString();
+
+  // Find sessions where last message is older than cutoff
+  const stmt = database.prepare(`
+    UPDATE sessions 
+    SET is_active = 0, ended_at = CURRENT_TIMESTAMP, summary = 'Auto-closed due to inactivity'
+    WHERE is_active = 1 AND id IN (
+      SELECT s.id FROM sessions s
+      LEFT JOIN (
+        SELECT session_id, MAX(created_at) as last_msg 
+        FROM session_messages 
+        GROUP BY session_id
+      ) m ON s.id = m.session_id
+      WHERE s.is_active = 1 
+      AND (m.last_msg IS NULL OR m.last_msg < ?)
+      AND s.started_at < ?
+    )
+  `);
+
+  const result = stmt.run(cutoff, cutoff);
+  return result.changes;
+}
+
 /**
  * Close the database connection.
  */

src/mcp-server.ts

@@ -1,9 +1,9 @@
 #!/usr/bin/env bun
 /**
  * Personal Knowledge MCP Server
- * 
+ *
  * Exposes knowledge database via Model Context Protocol for use by AI agents.
- * 
+ *
  * Tools provided:
  * - store_knowledge: Store a new knowledge entry
  * - search_knowledge: Semantic search using vector embeddings
@@ -13,6 +13,15 @@
  * - delete_knowledge: Delete an entry
  * - list_knowledge: List entries with filters
  * - get_knowledge_stats: Get database statistics
+ *
+ * Session Memory Tools:
+ * - start_logging_session: Begin logging a session
+ * - log_message: Log a user or agent message
+ * - search_session: Search within a session
+ * - search_all_sessions: Search across all sessions
+ * - list_sessions: List all sessions
+ * - get_session: Get session details
+ * - end_session: End and summarize a session
  */
 import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
 import { StdioServerTransport } from "@modelcontextprotocol/sdk/server/stdio.js";
@@ -27,6 +36,19 @@ import {
   listKnowledge,
   getKnowledgeStats,
 } from "./services/knowledgeService.js";
+import {
+  startLoggingSession,
+  logMessage,
+  searchSession,
+  searchAllSessions,
+  getSession as getSessionDetails,
+  getActiveSession,
+  hasActiveSession,
+  endSession,
+  listSessions,
+  closeTimedOutSessions,
+  getSessionStats,
+} from "./services/sessionService.js";
 
 // Create MCP server
 const server = new McpServer({
@@ -73,13 +95,13 @@ server.tool(
   async ({ query, limit }) => {
     try {
       const results = await searchKnowledge(query, { limit, minScore: 0.3 });
-      
+
       if (results.length === 0) {
         return {
           content: [{ type: "text", text: "No similar knowledge entries found." }],
         };
       }
-      
+
       let output = `## Found ${results.length} similar entries:\n\n`;
       for (let i = 0; i < results.length; i++) {
         const r = results[i];
@@ -91,7 +113,7 @@ server.tool(
         }
         output += `\n${r.content_preview}...\n\n---\n\n`;
       }
-      
+
       return {
         content: [{ type: "text", text: output }],
       };
@@ -99,9 +121,9 @@ server.tool(
       const message = error instanceof Error ? error.message : "Unknown error";
       if (message.includes("not initialized")) {
         return {
-          content: [{ 
-            type: "text", 
-            text: "Vector database not initialized. Use search_knowledge_text for keyword search, or add some entries first." 
+          content: [{
+            type: "text",
+            text: "Vector database not initialized. Use search_knowledge_text for keyword search, or add some entries first."
           }],
         };
       }
@@ -122,21 +144,21 @@ server.tool(
   },
   async ({ query, limit }) => {
     const results = searchKnowledgeText(query, limit);
-    
+
     if (results.length === 0) {
       return {
         content: [{ type: "text", text: `No results found for: "${query}"` }],
       };
     }
-    
-    const formatted = results.map((r) => 
+
+    const formatted = results.map((r) =>
       `**${r.title}** (ID: ${r.id})\n${r.content.slice(0, 200)}...${r.tags ? `\nTags: ${r.tags.join(", ")}` : ""}`
     ).join("\n\n---\n\n");
-    
+
     return {
-      content: [{ 
-        type: "text", 
-        text: `Found ${results.length} result(s) for "${query}":\n\n${formatted}` 
+      content: [{
+        type: "text",
+        text: `Found ${results.length} result(s) for "${query}":\n\n${formatted}`
       }],
     };
   }
@@ -151,13 +173,13 @@ server.tool(
   },
   async ({ id }) => {
     const entry = getKnowledge(id);
-    
+
     if (!entry) {
       return {
         content: [{ type: "text", text: `No entry found with ID: ${id}` }],
       };
     }
-    
+
     return {
       content: [{
         type: "text",
@@ -184,25 +206,25 @@ server.tool(
     if (content !== undefined) updates.content = content;
     if (source !== undefined) updates.source = source;
     if (tags !== undefined) updates.tags = tags;
-    
+
     if (Object.keys(updates).length === 0) {
       return {
         content: [{ type: "text", text: "No updates provided" }],
       };
     }
-    
+
     const result = await updateKnowledge(id, updates);
-    
+
     if (!result.success) {
       return {
         content: [{ type: "text", text: `No entry found with ID: ${id}` }],
       };
     }
-    
+
     return {
-      content: [{ 
-        type: "text", 
-        text: `✅ Updated entry #${id}\n${result.vectorized ? "📊 Re-indexed for semantic search" : "⚠️ Database updated (vector re-indexing failed)"}` 
+      content: [{
+        type: "text",
+        text: `✅ Updated entry #${id}\n${result.vectorized ? "📊 Re-indexed for semantic search" : "⚠️ Database updated (vector re-indexing failed)"}`
       }],
     };
   }
@@ -217,13 +239,13 @@ server.tool(
   },
   async ({ id }) => {
     const success = await deleteKnowledge(id);
-    
+
     if (!success) {
       return {
         content: [{ type: "text", text: `No entry found with ID: ${id}` }],
       };
     }
-    
+
     return {
       content: [{ type: "text", text: `✅ Deleted entry #${id}` }],
     };
@@ -241,21 +263,21 @@ server.tool(
   },
   async ({ limit, offset, tags }) => {
     const entries = listKnowledge({ limit, offset, tags });
-    
+
     if (entries.length === 0) {
       return {
         content: [{ type: "text", text: "No knowledge entries found." }],
       };
     }
-    
-    const formatted = entries.map((e) => 
+
+    const formatted = entries.map((e) =>
       `- **${e.title}** (ID: ${e.id})${e.tags ? ` [${e.tags.join(", ")}]` : ""}`
     ).join("\n");
-    
+
     return {
-      content: [{ 
-        type: "text", 
-        text: `📚 Knowledge Entries (${entries.length}):\n\n${formatted}` 
+      content: [{
+        type: "text",
+        text: `📚 Knowledge Entries (${entries.length}):\n\n${formatted}`
       }],
     };
   }
@@ -268,13 +290,13 @@ server.tool(
   {},
   async () => {
     const stats = await getKnowledgeStats();
-    
+
     const tagList = Object.entries(stats.database.tagCounts)
       .sort((a, b) => b[1] - a[1])
       .slice(0, 10)
       .map(([tag, count]) => `  ${tag}: ${count}`)
       .join("\n");
-    
+
     return {
       content: [{
         type: "text",
@@ -294,11 +316,253 @@ ${tagList || "  No tags yet"}`,
   }
 );
 
+// ============================================================================
+// Session Memory Tools
+// ============================================================================
+
+// Tool: Start logging session
+server.tool(
+  "start_logging_session",
+  "Start logging a new session for later search. IMPORTANT: After starting, you MUST call log_message for EACH user message and your response to capture the conversation. Call this when the user wants to record an important conversation.",
+  {
+    name: z.string().optional().describe("Optional name for the session (e.g., 'debugging auth')"),
+  },
+  async ({ name }) => {
+    try {
+      // Close any timed-out sessions first
+      closeTimedOutSessions();
+
+      const { sessionId, session } = startLoggingSession(name);
+      return {
+        content: [{
+          type: "text",
+          text: `✅ Started session #${sessionId}${name ? `: "${name}"` : ""}\n\n**IMPORTANT:** You must now call \`log_message\` for each exchange:\n1. Call \`log_message(role="user", content="...")\` with the user's message\n2. Call \`log_message(role="agent", content="...")\` with your response\n\nUse \`end_session\` when finished.`,
+        }],
+      };
+    } catch (error) {
+      const message = error instanceof Error ? error.message : "Unknown error";
+      return {
+        content: [{ type: "text", text: `❌ Failed to start session: ${message}` }],
+      };
+    }
+  }
+);
+
+// Tool: Log message (MUST be called for each exchange during a session)
+server.tool(
+  "log_message",
+  "Log a message to the current session. REQUIRED: Call this for EVERY user message and agent response while a session is active. This enables semantic search across the conversation later.",
+  {
+    role: z.enum(["user", "agent"]).describe("Who sent the message: 'user' or 'agent'"),
+    content: z.string().describe("The full message content to log"),
+    sessionId: z.number().optional().describe("Session ID (uses active session if not provided)"),
+  },
+  async ({ role, content, sessionId }) => {
+    try {
+      const result = await logMessage(role, content, sessionId);
+      return {
+        content: [{
+          type: "text",
+          text: `📝 Logged [${role}] message${result.indexed ? " (indexed for search)" : ""}`,
+        }],
+      };
+    } catch (error) {
+      const message = error instanceof Error ? error.message : "Unknown error";
+      return {
+        content: [{ type: "text", text: `❌ Failed to log message: ${message}` }],
+      };
+    }
+  }
+);
+
+// Tool: Search within a session
+server.tool(
+  "search_session",
+  "Search for content within a specific session using semantic similarity.",
+  {
+    sessionId: z.number().describe("The session ID to search within"),
+    query: z.string().describe("Search query"),
+    limit: z.number().optional().default(5).describe("Maximum results (default: 5)"),
+  },
+  async ({ sessionId, query, limit }) => {
+    try {
+      const results = await searchSession(sessionId, query, limit);
+
+      if (results.length === 0) {
+        return {
+          content: [{ type: "text", text: `No matches found in session #${sessionId}` }],
+        };
+      }
+
+      let output = `## Found ${results.length} matches in session #${sessionId}:\n\n`;
+      for (let i = 0; i < results.length; i++) {
+        const r = results[i];
+        const role = r.tags?.find(t => t.startsWith("role:"))?.replace("role:", "") || "?";
+        const similarity = Math.round(r.score * 100);
+        output += `### ${i + 1}. [${role}] (${similarity}% match)\n`;
+        output += `${r.content_preview}...\n\n`;
+      }
+
+      return {
+        content: [{ type: "text", text: output }],
+      };
+    } catch (error) {
+      const message = error instanceof Error ? error.message : "Unknown error";
+      return {
+        content: [{ type: "text", text: `❌ Search error: ${message}` }],
+      };
+    }
+  }
+);
+
+// Tool: Search all sessions
+server.tool(
+  "search_all_sessions",
+  "Search across ALL logged sessions using semantic similarity.",
+  {
+    query: z.string().describe("Search query"),
+    limit: z.number().optional().default(10).describe("Maximum results (default: 10)"),
+  },
+  async ({ query, limit }) => {
+    try {
+      const results = await searchAllSessions(query, limit);
+
+      if (results.length === 0) {
+        return {
+          content: [{ type: "text", text: "No matches found across sessions" }],
+        };
+      }
+
+      let output = `## Found ${results.length} matches across sessions:\n\n`;
+      for (let i = 0; i < results.length; i++) {
+        const r = results[i];
+        const sessionTag = r.tags?.find(t => t.startsWith("session:"));
+        const sessionId = sessionTag?.replace("session:", "") || "?";
+        const role = r.tags?.find(t => t.startsWith("role:"))?.replace("role:", "") || "?";
+        const similarity = Math.round(r.score * 100);
+        output += `### ${i + 1}. Session #${sessionId} [${role}] (${similarity}% match)\n`;
+        output += `${r.content_preview}...\n\n`;
+      }
+
+      return {
+        content: [{ type: "text", text: output }],
+      };
+    } catch (error) {
+      const message = error instanceof Error ? error.message : "Unknown error";
+      return {
+        content: [{ type: "text", text: `❌ Search error: ${message}` }],
+      };
+    }
+  }
+);
+
+// Tool: List sessions
+server.tool(
+  "list_sessions",
+  "List all logged sessions",
+  {
+    limit: z.number().optional().default(20).describe("Maximum sessions to return"),
+    activeOnly: z.boolean().optional().default(false).describe("Only show active sessions"),
+  },
+  async ({ limit, activeOnly }) => {
+    const sessions = listSessions({ limit, activeOnly });
+
+    if (sessions.length === 0) {
+      return {
+        content: [{ type: "text", text: "No sessions found" }],
+      };
+    }
+
+    const formatted = sessions.map(s => {
+      const status = s.is_active ? "🟢 Active" : "⚪ Ended";
+      const name = s.name ? `"${s.name}"` : "(unnamed)";
+      return `- **#${s.id}** ${name} - ${status} - ${s.started_at.slice(0, 10)}`;
+    }).join("\n");
+
+    return {
+      content: [{
+        type: "text",
+        text: `## Sessions (${sessions.length}):\n\n${formatted}`,
+      }],
+    };
+  }
+);
+
+// Tool: Get session details
+server.tool(
+  "get_session",
+  "Get details and messages from a specific session",
+  {
+    sessionId: z.number().describe("The session ID"),
+  },
+  async ({ sessionId }) => {
+    const result = getSessionDetails(sessionId);
+
+    if (!result) {
+      return {
+        content: [{ type: "text", text: `Session #${sessionId} not found` }],
+      };
+    }
+
+    const { session, messages, messageCount } = result;
+    const status = session.is_active ? "🟢 Active" : "⚪ Ended";
+
+    let output = `## Session #${session.id}${session.name ? `: "${session.name}"` : ""}\n\n`;
+    output += `**Status:** ${status}\n`;
+    output += `**Started:** ${session.started_at}\n`;
+    if (session.ended_at) output += `**Ended:** ${session.ended_at}\n`;
+    if (session.summary) output += `**Summary:** ${session.summary}\n`;
+    output += `**Messages:** ${messageCount}\n\n`;
+
+    if (messages.length > 0) {
+      output += "### Recent Messages:\n\n";
+      const recentMessages = messages.slice(-10); // Last 10
+      for (const msg of recentMessages) {
+        output += `**[${msg.role}]** ${msg.content.slice(0, 200)}${msg.content.length > 200 ? "..." : ""}\n\n`;
+      }
+    }
+
+    return {
+      content: [{ type: "text", text: output }],
+    };
+  }
+);
+
+// Tool: End session
+server.tool(
+  "end_session",
+  "End the current or specified session",
+  {
+    sessionId: z.number().optional().describe("Session ID (ends active session if not provided)"),
+    summary: z.string().optional().describe("Optional summary of what was accomplished"),
+  },
+  async ({ sessionId, summary }) => {
+    const result = endSession(sessionId, summary);
+
+    if (!result.success) {
+      return {
+        content: [{ type: "text", text: "❌ No active session to end" }],
+      };
+    }
+
+    return {
+      content: [{
+        type: "text",
+        text: `✅ Ended session with ${result.messageCount} messages${summary ? `\n📝 Summary: "${summary}"` : ""}`,
+      }],
+    };
+  }
+);
+
 // Start the server
 async function main() {
+  // Clean up any timed-out sessions on startup
+  closeTimedOutSessions();
+
   const transport = new StdioServerTransport();
   await server.connect(transport);
   console.error("Personal Knowledge MCP Server running on stdio");
 }
 
 main().catch(console.error);
+

src/services/sessionService.ts

@@ -0,0 +1,229 @@
+/**
+ * Session Service
+ *
+ * Business logic for session memory feature.
+ * Coordinates session management and vector indexing of messages.
+ */
+import {
+    createSession as dbCreateSession,
+    getSession as dbGetSession,
+    getActiveSession as dbGetActiveSession,
+    endSession as dbEndSession,
+    saveSessionMessage as dbSaveSessionMessage,
+    getSessionMessages as dbGetSessionMessages,
+    listSessions as dbListSessions,
+    getSessionMessageCount,
+    closeTimedOutSessions as dbCloseTimedOutSessions,
+    type Session,
+    type SessionMessage,
+} from "../database/index.js";
+import { queryVectors, updateVector, type SearchResult } from "./vectorService.js";
+
+export { type Session, type SessionMessage };
+
+// Track the current active session ID in memory for auto-logging
+let currentSessionId: number | null = null;
+
+/**
+ * Start a new logging session.
+ */
+export function startLoggingSession(name?: string): { sessionId: number; session: Session } {
+    // Close any existing active session first
+    const existing = dbGetActiveSession();
+    if (existing) {
+        dbEndSession(existing.id, "Auto-closed when new session started");
+    }
+
+    const sessionId = dbCreateSession(name);
+    currentSessionId = sessionId;
+
+    const session = dbGetSession(sessionId);
+    if (!session) {
+        throw new Error("Failed to create session");
+    }
+
+    return { sessionId, session };
+}
+
+/**
+ * Log a message to the current or specified session.
+ * Also indexes the message in the vector database for search.
+ */
+export async function logMessage(
+    role: "user" | "agent",
+    content: string,
+    sessionId?: number
+): Promise<{ messageId: number; indexed: boolean }> {
+    const targetSessionId = sessionId ?? currentSessionId;
+
+    if (!targetSessionId) {
+        throw new Error("No active session. Call start_logging_session first.");
+    }
+
+    // Check if session exists and is active
+    const session = dbGetSession(targetSessionId);
+    if (!session) {
+        throw new Error(`Session ${targetSessionId} not found`);
+    }
+    if (!session.is_active) {
+        throw new Error(`Session ${targetSessionId} is already closed`);
+    }
+
+    // Save message to database
+    const messageId = dbSaveSessionMessage(targetSessionId, role, content);
+
+    // Index in vector DB for semantic search
+    let indexed = false;
+    try {
+        await updateVector({
+            id: messageId,
+            title: `[${role}] Session ${targetSessionId}`,
+            content: content,
+            tags: [`session:${targetSessionId}`, `role:${role}`],
+            created_at: new Date().toISOString(),
+            updated_at: new Date().toISOString(),
+        });
+        indexed = true;
+    } catch {
+        // Vector indexing failed, but message is saved
+        console.error("Vector indexing failed for session message");
+    }
+
+    return { messageId, indexed };
+}
+
+/**
+ * Search within a specific session using semantic similarity.
+ */
+export async function searchSession(
+    sessionId: number,
+    query: string,
+    limit = 5
+): Promise<SearchResult[]> {
+    // Query vectors with session tag filter
+    const results = await queryVectors(query, { limit: limit * 2, minScore: 0.3 });
+
+    // Filter to only include messages from this session
+    const sessionTag = `session:${sessionId}`;
+    const filtered = results.filter(r => r.tags?.includes(sessionTag));
+
+    return filtered.slice(0, limit);
+}
+
+/**
+ * Search across all sessions using semantic similarity.
+ */
+export async function searchAllSessions(
+    query: string,
+    limit = 10
+): Promise<SearchResult[]> {
+    // Get all session-tagged results
+    const results = await queryVectors(query, { limit: limit * 2, minScore: 0.3 });
+
+    // Filter to only session messages (have session: tag)
+    const filtered = results.filter(r => r.tags?.some(t => t.startsWith("session:")));
+
+    return filtered.slice(0, limit);
+}
+
+/**
+ * Get a session with its messages.
+ */
+export function getSession(sessionId: number): {
+    session: Session;
+    messages: SessionMessage[];
+    messageCount: number;
+} | null {
+    const session = dbGetSession(sessionId);
+    if (!session) return null;
+
+    const messages = dbGetSessionMessages(sessionId);
+    const messageCount = getSessionMessageCount(sessionId);
+
+    return { session, messages, messageCount };
+}
+
+/**
+ * Get the current active session.
+ */
+export function getActiveSession(): Session | null {
+    return dbGetActiveSession();
+}
+
+/**
+ * Check if there's an active session for auto-logging.
+ */
+export function hasActiveSession(): boolean {
+    return currentSessionId !== null && dbGetActiveSession() !== null;
+}
+
+/**
+ * End the current or specified session.
+ */
+export function endSession(
+    sessionId?: number,
+    summary?: string
+): { success: boolean; messageCount: number } {
+    const targetSessionId = sessionId ?? currentSessionId;
+
+    if (!targetSessionId) {
+        return { success: false, messageCount: 0 };
+    }
+
+    const messageCount = getSessionMessageCount(targetSessionId);
+    const success = dbEndSession(targetSessionId, summary);
+
+    if (success && targetSessionId === currentSessionId) {
+        currentSessionId = null;
+    }
+
+    return { success, messageCount };
+}
+
+/**
+ * List all sessions.
+ */
+export function listSessions(options?: {
+    limit?: number;
+    offset?: number;
+    activeOnly?: boolean;
+}): Session[] {
+    return dbListSessions(options);
+}
+
+/**
+ * Close any timed-out sessions (inactive for 1+ hour).
+ */
+export function closeTimedOutSessions(): number {
+    const closed = dbCloseTimedOutSessions();
+
+    // Clear current session if it was closed
+    if (currentSessionId && !dbGetActiveSession()) {
+        currentSessionId = null;
+    }
+
+    return closed;
+}
+
+/**
+ * Get session stats.
+ */
+export function getSessionStats(): {
+    totalSessions: number;
+    activeSessions: number;
+    totalMessages: number;
+} {
+    const allSessions = dbListSessions({ limit: 1000 });
+    const activeSessions = allSessions.filter(s => s.is_active).length;
+
+    let totalMessages = 0;
+    for (const session of allSessions) {
+        totalMessages += getSessionMessageCount(session.id);
+    }
+
+    return {
+        totalSessions: allSessions.length,
+        activeSessions,
+        totalMessages,
+    };
+}

tests/services/session.test.ts

@@ -0,0 +1,157 @@
+/**
+ * Session Service Tests
+ *
+ * Uses isolated test database via OPENCODE_PK_DATA_DIR environment variable.
+ * Uses dynamic imports to ensure env var is set BEFORE module loads.
+ */
+import { describe, test, expect, beforeAll, afterAll } from "bun:test";
+import { mkdtempSync, rmSync } from "fs";
+import { join } from "path";
+import { tmpdir } from "os";
+
+// Set up isolated test database BEFORE any imports
+const testDir = mkdtempSync(join(tmpdir(), "opencode-pk-test-"));
+process.env.OPENCODE_PK_DATA_DIR = testDir;
+
+// Types for the dynamically imported module
+type DatabaseModule = typeof import("../../src/database/index");
+
+let db: DatabaseModule;
+
+describe("Session Database Functions", () => {
+    beforeAll(async () => {
+        // Dynamic import AFTER env var is set
+        db = await import("../../src/database/index");
+        db.initDatabase();
+    });
+
+    afterAll(() => {
+        // Clean up
+        db.closeDatabase();
+        rmSync(testDir, { recursive: true, force: true });
+    });
+
+    describe("createSession", () => {
+        test("creates a session with name", () => {
+            const id = db.createSession("Test Session");
+            expect(id).toBeGreaterThan(0);
+
+            const session = db.getSession(id);
+            expect(session).not.toBeNull();
+            expect(session!.name).toBe("Test Session");
+            expect(session!.is_active).toBe(true);
+            expect(session!.ended_at).toBeNull();
+        });
+
+        test("creates a session without name", () => {
+            const id = db.createSession();
+            const session = db.getSession(id);
+            expect(session).not.toBeNull();
+            expect(session!.name).toBeNull();
+            expect(session!.is_active).toBe(true);
+        });
+    });
+
+    describe("getActiveSession", () => {
+        test("returns most recent active session", () => {
+            db.createSession("First");
+            db.createSession("Second");
+
+            const active = db.getActiveSession();
+            expect(active).not.toBeNull();
+            // Check it's the most recent by name (ID ordering can vary)
+            expect(active!.name).toBe("Second");
+        });
+    });
+
+    describe("endSession", () => {
+        test("ends a session with summary", () => {
+            const id = db.createSession("To End");
+            const success = db.endSession(id, "Completed successfully");
+
+            expect(success).toBe(true);
+
+            const session = db.getSession(id);
+            expect(session).not.toBeNull();
+            expect(session!.is_active).toBe(false);
+            expect(session!.ended_at).not.toBeNull();
+            expect(session!.summary).toBe("Completed successfully");
+        });
+
+        test("returns false for non-existent session", () => {
+            const success = db.endSession(99999);
+            expect(success).toBe(false);
+        });
+    });
+
+    describe("saveSessionMessage", () => {
+        test("saves user message", () => {
+            const sessionId = db.createSession("Message Test");
+            const msgId = db.saveSessionMessage(sessionId, "user", "Hello, world!");
+
+            expect(msgId).toBeGreaterThan(0);
+
+            const messages = db.getSessionMessages(sessionId);
+            expect(messages.length).toBe(1);
+            expect(messages[0].role).toBe("user");
+            expect(messages[0].content).toBe("Hello, world!");
+        });
+
+        test("saves agent message", () => {
+            const sessionId = db.createSession("Agent Message Test");
+            db.saveSessionMessage(sessionId, "user", "Question");
+            const msgId = db.saveSessionMessage(sessionId, "agent", "Answer");
+
+            const messages = db.getSessionMessages(sessionId);
+            expect(messages.length).toBe(2);
+            expect(messages[1].role).toBe("agent");
+            expect(messages[1].content).toBe("Answer");
+        });
+    });
+
+    describe("getSessionMessageCount", () => {
+        test("returns correct count", () => {
+            const sessionId = db.createSession("Count Test");
+            db.saveSessionMessage(sessionId, "user", "Message 1");
+            db.saveSessionMessage(sessionId, "agent", "Message 2");
+            db.saveSessionMessage(sessionId, "user", "Message 3");
+
+            const count = db.getSessionMessageCount(sessionId);
+            expect(count).toBe(3);
+        });
+
+        test("returns 0 for empty session", () => {
+            const sessionId = db.createSession("Empty");
+            const count = db.getSessionMessageCount(sessionId);
+            expect(count).toBe(0);
+        });
+    });
+
+    describe("listSessions", () => {
+        test("lists all sessions", () => {
+            // Create a few sessions for testing
+            db.createSession("List Test 1");
+            db.createSession("List Test 2");
+
+            const sessions = db.listSessions({ limit: 100 });
+            expect(sessions.length).toBeGreaterThanOrEqual(2);
+        });
+
+        test("respects limit", () => {
+            const sessions = db.listSessions({ limit: 2 });
+            expect(sessions.length).toBeLessThanOrEqual(2);
+        });
+
+        test("filters active only", () => {
+            const activeId = db.createSession("Active Only Test");
+            const inactiveId = db.createSession("Will End");
+            db.endSession(inactiveId);
+
+            const activeSessions = db.listSessions({ activeOnly: true });
+            const activeIds = activeSessions.map(s => s.id);
+
+            expect(activeIds).toContain(activeId);
+            expect(activeIds).not.toContain(inactiveId);
+        });
+    });
+});