diff --git a/packages/core/src/client/endpoints.ts b/packages/core/src/client/endpoints.ts
index fec9f0b..2c8e0df 100644
--- a/packages/core/src/client/endpoints.ts
+++ b/packages/core/src/client/endpoints.ts
@@ -24,13 +24,13 @@ export function videoGenerateEndpoint(baseUrl: string): string {
 // ---- Async Task Query ----
 
 export function taskEndpoint(baseUrl: string, taskId: string): string {
-  return `${baseUrl}/api/v1/tasks/${taskId}`;
+  return `${baseUrl}/api/v1/tasks/${encodeURIComponent(taskId)}`;
 }
 
 // ---- Application (Agent / Workflow) ----
 
 export function appCompletionEndpoint(baseUrl: string, appId: string): string {
-  return `${baseUrl}/api/v1/apps/${appId}/completion`;
+  return `${baseUrl}/api/v1/apps/${encodeURIComponent(appId)}/completion`;
 }
 
 // ---- Memory (DashScope v2) ----
@@ -48,7 +48,7 @@ export function memoryListEndpoint(baseUrl: string): string {
 }
 
 export function memoryNodeEndpoint(baseUrl: string, nodeId: string): string {
-  return `${baseUrl}/api/v2/apps/memory/memory_nodes/${nodeId}`;
+  return `${baseUrl}/api/v2/apps/memory/memory_nodes/${encodeURIComponent(nodeId)}`;
 }
 
 // ---- Speech Synthesis (TTS) ----
@@ -70,7 +70,7 @@ export function profileSchemaEndpoint(baseUrl: string): string {
 }
 
 export function userProfileEndpoint(baseUrl: string, schemaId: string): string {
-  return `${baseUrl}/api/v2/apps/memory/profile_schemas/${schemaId}/profiles`;
+  return `${baseUrl}/api/v2/apps/memory/profile_schemas/${encodeURIComponent(schemaId)}/profiles`;
 }
 
 // ---- MCP Services (Streamable HTTP) ----
diff --git a/packages/core/src/client/stream.ts b/packages/core/src/client/stream.ts
index 56904aa..6fe6ac2 100644
--- a/packages/core/src/client/stream.ts
+++ b/packages/core/src/client/stream.ts
@@ -1,3 +1,6 @@
+import { BailianError } from "../errors/base.ts";
+import { ExitCode } from "../errors/codes.ts";
+
 export interface ServerSentEvent {
   event?: string;
   data: string;
@@ -11,12 +14,20 @@ export async function* parseSSE(response: Response): AsyncGenerator<ServerSentEv
   const decoder = new TextDecoder();
   let buffer = "";
 
+  // Guard against a hostile or malfunctioning stream that never emits a newline
+  // (or builds a single absurdly large event): bound the in-memory buffer so the
+  // parser cannot be driven to exhaust process memory.
+  const MAX_SSE_BUFFER = 16 * 1024 * 1024; // 16 MiB
+
   try {
     while (true) {
       const { done, value } = await reader.read();
       if (done) break;
 
       buffer += decoder.decode(value, { stream: true });
+      if (buffer.length > MAX_SSE_BUFFER) {
+        throw new BailianError("SSE stream exceeded the maximum buffer size.", ExitCode.GENERAL);
+      }
 
       const lines = buffer.split("\n");
       buffer = lines.pop() || "";
@@ -43,6 +54,12 @@ export async function* parseSSE(response: Response): AsyncGenerator<ServerSentEv
         switch (field) {
           case "data":
             event.data = event.data !== undefined ? `${event.data}\n${value}` : value;
+            if (event.data.length > MAX_SSE_BUFFER) {
+              throw new BailianError(
+                "SSE event exceeded the maximum buffer size.",
+                ExitCode.GENERAL,
+              );
+            }
             break;
           case "event":
             event.event = value;