feat: Implement Phase 1 of SDK agent architecture with hook integration

- Added CLI commands for context, new session, save observation, and summary.
- Created HooksDatabase for managing SDK sessions and observations.
- Implemented migration 004 to add new tables: sdk_sessions, observation_queue, observations, and session_summaries.
- Developed hook functions for context display, session initialization, observation queuing, and session finalization.
- Added comprehensive tests for database schema and hook functionality.
- Documented Phase 1 implementation in PHASE1-COMPLETE.md.

src/hooks/save.ts

@@ -0,0 +1,72 @@
+import { HooksDatabase } from '../services/sqlite/HooksDatabase.js';
+import path from 'path';
+
+export interface PostToolUseInput {
+  session_id: string;
+  cwd: string;
+  tool_name: string;
+  tool_input: any;
+  tool_output: any;
+  [key: string]: any;
+}
+
+// Tools to skip (low value or too frequent)
+const SKIP_TOOLS = new Set([
+  'TodoWrite',
+  'ListMcpResourcesTool'
+]);
+
+/**
+ * Save Hook - PostToolUse
+ * Queues tool observations for SDK processing
+ */
+export function saveHook(input: PostToolUseInput): void {
+  try {
+    const { session_id, cwd, tool_name, tool_input, tool_output } = input;
+
+    // Skip certain tools
+    if (SKIP_TOOLS.has(tool_name)) {
+      console.log('{"continue": true, "suppressOutput": true}');
+      process.exit(0);
+    }
+
+    // Extract project from cwd
+    const project = path.basename(cwd);
+
+    // Find active SDK session
+    const db = new HooksDatabase();
+    const session = db.findActiveSDKSession(session_id);
+
+    if (!session) {
+      // No active session yet - this can happen if UserPromptSubmit hasn't run
+      // Just exit silently
+      db.close();
+      console.log('{"continue": true, "suppressOutput": true}');
+      process.exit(0);
+    }
+
+    // Queue the observation
+    // SDK session ID might be null if init message hasn't arrived yet
+    // Use the internal ID as a fallback
+    const sdkSessionId = session.sdk_session_id || `pending-${session.id}`;
+
+    db.queueObservation(
+      sdkSessionId,
+      tool_name,
+      JSON.stringify(tool_input),
+      JSON.stringify(tool_output)
+    );
+
+    db.close();
+
+    // Output hook response
+    console.log('{"continue": true, "suppressOutput": true}');
+    process.exit(0);
+
+  } catch (error: any) {
+    // On error, don't block Claude Code
+    console.error(`[claude-mem save error: ${error.message}]`);
+    console.log('{"continue": true, "suppressOutput": true}');
+    process.exit(0);
+  }
+}