diff --git a/lib/api.js b/lib/api.js
index 828ef59..9065355 100644
--- a/lib/api.js
+++ b/lib/api.js
@@ -1,6 +1,105 @@
 const fetch = require('node-fetch');
 const config = require('./config');
 
+function createCondition({ property, operator, value }) {
+  return {
+    type: 'condition',
+    id: `cond_${Date.now()}_${Math.random().toString(36).slice(2, 9)}`,
+    property,
+    operator,
+    value
+  };
+}
+
+function normalizeDateOnly(value) {
+  if (typeof value !== 'string') return value;
+  const tIndex = value.indexOf('T');
+  if (tIndex === -1) return value;
+  return value.slice(0, tIndex);
+}
+
+function parseBooleanLike(value) {
+  if (typeof value === 'boolean') return value;
+  if (typeof value === 'number') return value !== 0;
+  if (typeof value === 'string') return value.toLowerCase() === 'true' || value === '1';
+  return false;
+}
+
+function legacyListFiltersToFilterQuery(filters = {}) {
+  const query = {
+    type: 'group',
+    id: `root_${Date.now()}`,
+    conjunction: 'and',
+    children: []
+  };
+
+  // Legacy GET /api/tasks query params are no longer supported for filtering.
+  // Convert common CLI filters to POST /api/tasks/query FilterQuery objects.
+  if (filters.completed !== undefined) {
+    const isCompleted = parseBooleanLike(filters.completed);
+    query.children.push(
+      createCondition({
+        property: 'status.isCompleted',
+        operator: isCompleted ? 'is-checked' : 'is-not-checked',
+        value: null
+      })
+    );
+  }
+
+  if (filters.archived !== undefined) {
+    const isArchived = parseBooleanLike(filters.archived);
+    query.children.push(
+      createCondition({
+        property: 'archived',
+        operator: isArchived ? 'is-checked' : 'is-not-checked',
+        value: null
+      })
+    );
+  }
+
+  if (filters.project !== undefined && filters.project !== null && String(filters.project).trim()) {
+    query.children.push(
+      createCondition({
+        property: 'projects',
+        operator: 'contains',
+        value: String(filters.project)
+      })
+    );
+  }
+
+  if (filters.scheduled_after !== undefined && filters.scheduled_after !== null && String(filters.scheduled_after).trim()) {
+    query.children.push(
+      createCondition({
+        property: 'scheduled',
+        operator: 'is-on-or-after',
+        value: normalizeDateOnly(String(filters.scheduled_after))
+      })
+    );
+  }
+
+  if (filters.scheduled_before !== undefined && filters.scheduled_before !== null && String(filters.scheduled_before).trim()) {
+    query.children.push(
+      createCondition({
+        property: 'scheduled',
+        operator: 'is-on-or-before',
+        value: normalizeDateOnly(String(filters.scheduled_before))
+      })
+    );
+  }
+
+  if (filters.due_before !== undefined && filters.due_before !== null && String(filters.due_before).trim()) {
+    query.children.push(
+      createCondition({
+        property: 'due',
+        operator: 'is-before',
+        value: String(filters.due_before)
+      })
+    );
+  }
+
+  return query;
+}
+
 class TaskNotesAPI {
   constructor() {
     this.config = config.get();
@@ -81,18 +180,18 @@ class TaskNotesAPI {
   }
 
   async listTasks(filters = {}) {
-    const params = new URLSearchParams();
-    
-    Object.entries(filters).forEach(([key, value]) => {
-      if (value !== undefined && value !== null) {
-        params.append(key, value);
+    const { limit, ...legacyFilters } = filters || {};
+    const filterQuery = legacyListFiltersToFilterQuery(legacyFilters);
+    const result = await this.queryTasks(filterQuery);
+
+    if (limit !== undefined && limit !== null) {
+      const parsedLimit = parseInt(limit, 10);
+      if (!Number.isNaN(parsedLimit) && parsedLimit >= 0 && Array.isArray(result.tasks)) {
+        return { ...result, tasks: result.tasks.slice(0, parsedLimit) };
       }
-    });
+    }
 
-    const queryString = params.toString();
-    const endpoint = `/api/tasks${queryString ? `?${queryString}` : ''}`;
-    
-    return this.request(endpoint);
+    return result;
   }
 
   async queryTasks(filterQuery) {
@@ -319,4 +418,4 @@ class TaskNotesAPI {
   }
 }
 
-module.exports = TaskNotesAPI;
\ No newline at end of file
+module.exports = TaskNotesAPI;