fix(voice-call): keep realtime context truncation UTF-16 safe (#101304)

Alix-007 · steipete · web-flow · commit 079a704dda76 · 2026-07-07T11:01:48.000+01:00
* Fix UTF-16-safe realtime context truncation

* test(voice-call): tighten UTF-16 context regression

---------

Co-authored-by: Peter Steinberger &lt;steipete@gmail.com&gt;
diff --git a/extensions/voice-call/src/realtime-agent-context.test.ts b/extensions/voice-call/src/realtime-agent-context.test.ts
@@ -93,4 +93,28 @@ describe("buildRealtimeVoiceInstructions", () => {
     expect(instructions).toContain("### IDENTITY.md");
     expect(instructions).not.toContain("do not include");
   });
+
+  it("truncates injected context without splitting UTF-16 surrogate pairs", async () => {
+    const agentId = "abc🚀tail";
+    const expectedContext = "OpenClaw agent voice context:\n\n- Agent id: abc";
+    const config = createConfig({
+      agentContext: {
+        enabled: true,
+        maxChars: expectedContext.length + 33,
+        includeIdentity: false,
+        includeWorkspaceFiles: false,
+        files: [],
+      },
+    });
+    config.agentId = agentId;
+
+    const instructions = await buildRealtimeVoiceInstructions({
+      baseInstructions: "Base voice instructions.",
+      config,
+      coreConfig: { agents: { list: [{ id: agentId }] } } as CoreConfig,
+      agentRuntime: createAgentRuntime("/unused"),
+    });
+
+    expect(instructions).toBe(`Base voice instructions.\n\n${expectedContext}\n[truncated]`);
+  });
 });
diff --git a/extensions/voice-call/src/realtime-agent-context.ts b/extensions/voice-call/src/realtime-agent-context.ts
@@ -3,6 +3,7 @@ import type { OpenClawConfig } from "openclaw/plugin-sdk/config-contracts";
 import { buildRealtimeVoiceAgentConsultPolicyInstructions } from "openclaw/plugin-sdk/realtime-voice";
 import { root } from "openclaw/plugin-sdk/security-runtime";
 import { normalizeOptionalString as normalizeString } from "openclaw/plugin-sdk/string-coerce-runtime";
+import { truncateUtf16Safe } from "openclaw/plugin-sdk/text-utility-runtime";
 import type { VoiceCallConfig } from "./config.js";
 import type { CoreAgentDeps, CoreConfig } from "./core-bridge.js";
 
@@ -22,7 +23,7 @@ function limitText(text: string, maxChars: number): string {
   if (text.length <= maxChars) {
     return text;
   }
-  return `${text.slice(0, Math.max(0, maxChars - 32)).trimEnd()}\n[truncated]`;
+  return `${truncateUtf16Safe(text, Math.max(0, maxChars - 32)).trimEnd()}\n[truncated]`;
 }
 
 /** Read configured workspace context files through the safe workspace root. */

Original file line number	Diff line number	Diff line change
`@@ -3,6 +3,7 @@ import type { OpenClawConfig } from "openclaw/plugin-sdk/config-contracts";`
`3`	`3`	`import { buildRealtimeVoiceAgentConsultPolicyInstructions } from "openclaw/plugin-sdk/realtime-voice";`
`4`	`4`	`import { root } from "openclaw/plugin-sdk/security-runtime";`
`5`	`5`	`import { normalizeOptionalString as normalizeString } from "openclaw/plugin-sdk/string-coerce-runtime";`
	`6`	`+import { truncateUtf16Safe } from "openclaw/plugin-sdk/text-utility-runtime";`
`6`	`7`	`import type { VoiceCallConfig } from "./config.js";`
`7`	`8`	`import type { CoreAgentDeps, CoreConfig } from "./core-bridge.js";`
`8`	`9`
`@@ -22,7 +23,7 @@ function limitText(text: string, maxChars: number): string {`
`22`	`23`	`if (text.length <= maxChars) {`
`23`	`24`	`return text;`
`24`	`25`	`}`
`25`		- return `${text.slice(0, Math.max(0, maxChars - 32)).trimEnd()}\n[truncated]`;
	`26`	+ return `${truncateUtf16Safe(text, Math.max(0, maxChars - 32)).trimEnd()}\n[truncated]`;
`26`	`27`	`}`
`27`	`28`
`28`	`29`	`/** Read configured workspace context files through the safe workspace root. */`