--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/infinite_canvas/agent_response_test.c	Tue Aug 18 22:18:15 2026 -0700
@@ -0,0 +1,45 @@
+#include "infinite_canvas/agent_response.h"
+
+#include <assert.h>
+#include <string.h>
+
+int main(void)
+{
+    Canvas_Agent_Response response;
+    assert(Canvas_Agent_Response_Parse(
+        "{\"action\":\"create\",\"presentation\":\"action\","
+        "\"conversation_id\":0,"
+        "\"title\":\"Planning\",\"response\":\"Here is a calendar\","
+        "\"entities\":[{\"kind\":\"calendar\",\"label\":\"August\","
+        "\"x\":120,\"y\":80,\"width\":300,\"height\":260,\"value\":18},"
+        "{\"kind\":\"card\",\"label\":\"Launch\",\"text\":\"Ship it\"}]}",
+        &response));
+    assert(strcmp(response.action, "create") == 0);
+    assert(strcmp(response.presentation, "action") == 0);
+    assert(response.entity_count == 2);
+    assert(response.entities[0].type == CANVAS_ENTITY_CALENDAR);
+    assert(response.entities[0].has_position);
+    assert(response.entities[0].has_size);
+    assert(response.entities[0].has_value);
+    assert(response.entities[0].value == 18);
+    assert(response.entities[1].type == CANVAS_ENTITY_CARD);
+    assert(!response.entities[1].has_value);
+    assert(strcmp(response.entities[1].text, "Ship it") == 0);
+
+    assert(!Canvas_Agent_Response_Parse(
+        "{\"action\":\"create\",\"presentation\":\"action\","
+        "\"conversation_id\":0,"
+        "\"response\":\"bad\",\"entities\":["
+        "{\"kind\":\"web_content\",\"text\":\"file:///etc/passwd\"}]}",
+        &response));
+    assert(!Canvas_Agent_Response_Parse(
+        "{\"action\":\"create\",\"presentation\":\"action\","
+        "\"conversation_id\":0,"
+        "\"response\":\"bad\",\"entities\":[{\"kind\":\"unknown\"}]}",
+        &response));
+    assert(!Canvas_Agent_Response_Parse(
+        "{\"action\":\"append\",\"presentation\":\"action\","
+        "\"conversation_id\":4,\"response\":\"bad\"}",
+        &response));
+    return 0;
+}