feat(ai): context tool — resolve the active view entity

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

lib/ai/agent/tools/context.js

@@ -0,0 +1,20 @@
+import { pool } from '../../../db/pool.js';
+
+const TABLE = { page: 'pages', ref: 'refs', task: 'tasks', project: 'projects', space: 'spaces' };
+
+export const contextTool = {
+  name: 'context',
+  description: "Resolve what the owner is currently looking at (the active view). Call this first to ground your answer in the right entity.",
+  input_schema: { type: 'object', properties: {} },
+  async handler(_args, ctx) {
+    const view = ctx.view;
+    if (!view?.entityType || !view?.entityId) {
+      return { note: 'No specific entity is active; only the Space context is available.', space_id: ctx.space_id };
+    }
+    const table = TABLE[view.entityType];
+    if (!table) return { entityType: view.entityType, entityId: view.entityId, note: 'unrecognised entity type' };
+    const { rows: [row] } = await pool.query(`SELECT * FROM ${table} WHERE id=$1`, [view.entityId]);
+    if (!row) return { entityType: view.entityType, entityId: view.entityId, error: 'not found' };
+    return { entityType: view.entityType, ...row };
+  }
+};