diff --git a/extensions/device-pair/index.ts b/extensions/device-pair/index.ts
index 21bbdef8bac..3754b570c7f 100644
--- a/extensions/device-pair/index.ts
+++ b/extensions/device-pair/index.ts
@@ -1,7 +1,10 @@
 import { mkdtemp, rm, writeFile } from "node:fs/promises";
 import os from "node:os";
 import path from "node:path";
-import { normalizeOptionalString } from "openclaw/plugin-sdk/text-runtime";
+import {
+  normalizeLowercaseStringOrEmpty,
+  normalizeOptionalString,
+} from "openclaw/plugin-sdk/text-runtime";
 import {
   clearDeviceBootstrapTokens,
   definePluginEntry,
@@ -563,7 +566,7 @@ export default definePluginEntry({
       handler: async (ctx) => {
         const args = normalizeOptionalString(ctx.args) ?? "";
         const tokens = args.split(/\s+/).filter(Boolean);
-        const action = tokens[0]?.toLowerCase() ?? "";
+        const action = normalizeLowercaseStringOrEmpty(tokens[0]);
         const gatewayClientScopes = Array.isArray(ctx.gatewayClientScopes)
           ? ctx.gatewayClientScopes
           : undefined;
@@ -583,7 +586,7 @@ export default definePluginEntry({
         }
 
         if (action === "notify") {
-          const notifyAction = normalizeOptionalString(tokens[1])?.toLowerCase() ?? "status";
+          const notifyAction = normalizeLowercaseStringOrEmpty(tokens[1]) || "status";
           return await handleNotifyCommand({
             api,
             ctx,
diff --git a/extensions/device-pair/pair-command-approve.ts b/extensions/device-pair/pair-command-approve.ts
index e68b86e066b..55b9e5d36ca 100644
--- a/extensions/device-pair/pair-command-approve.ts
+++ b/extensions/device-pair/pair-command-approve.ts
@@ -1,4 +1,7 @@
-import { normalizeOptionalString } from "openclaw/plugin-sdk/text-runtime";
+import {
+  normalizeLowercaseStringOrEmpty,
+  normalizeOptionalString,
+} from "openclaw/plugin-sdk/text-runtime";
 import { approveDevicePairing, listDevicePairing } from "./api.js";
 import { formatPendingRequests } from "./notify.js";
 
@@ -31,7 +34,7 @@ export function selectPendingApprovalRequest(params: {
       : { reply: buildMultiplePendingApprovalReply(params.pending) };
   }
 
-  if (params.requested.toLowerCase() === "latest") {
+  if (normalizeLowercaseStringOrEmpty(params.requested) === "latest") {
     return {
       pending: [...params.pending].toSorted((a, b) => (b.ts ?? 0) - (a.ts ?? 0))[0],
     };
diff --git a/extensions/tlon/src/monitor/approval.ts b/extensions/tlon/src/monitor/approval.ts
index d9dfcb053f1..882c8704d60 100644
--- a/extensions/tlon/src/monitor/approval.ts
+++ b/extensions/tlon/src/monitor/approval.ts
@@ -7,6 +7,7 @@
 
 // Extensions cannot import core internals directly, so use node:crypto here.
 import { randomBytes } from "node:crypto";
+import { normalizeLowercaseStringOrEmpty } from "openclaw/plugin-sdk/text-runtime";
 import type { PendingApproval } from "../settings.js";
 
 export type { PendingApproval };
@@ -106,7 +107,7 @@ export type ApprovalResponse = {
  *   - "block" permanently blocks the ship via Tlon's native blocking
  */
 export function parseApprovalResponse(text: string): ApprovalResponse | null {
-  const trimmed = text.trim().toLowerCase();
+  const trimmed = normalizeLowercaseStringOrEmpty(text);
 
   // Match "approve", "deny", or "block" optionally followed by an ID
   const match = trimmed.match(/^(approve|deny|block)(?:\s+(.+))?$/);
@@ -125,7 +126,7 @@ export function parseApprovalResponse(text: string): ApprovalResponse | null {
  * Used to determine if we should intercept the message before normal processing.
  */
 export function isApprovalResponse(text: string): boolean {
-  const trimmed = text.trim().toLowerCase();
+  const trimmed = normalizeLowercaseStringOrEmpty(text);
   return trimmed.startsWith("approve") || trimmed.startsWith("deny") || trimmed.startsWith("block");
 }
 
diff --git a/extensions/tlon/src/monitor/media.ts b/extensions/tlon/src/monitor/media.ts
index 0035760e409..3813187060c 100644
--- a/extensions/tlon/src/monitor/media.ts
+++ b/extensions/tlon/src/monitor/media.ts
@@ -7,6 +7,7 @@ import {
   MAX_IMAGE_BYTES,
   saveMediaBuffer,
 } from "openclaw/plugin-sdk/media-runtime";
+import { normalizeLowercaseStringOrEmpty } from "openclaw/plugin-sdk/text-runtime";
 import { getDefaultSsrFPolicy } from "../urbit/context.js";
 
 const MAX_IMAGES_PER_MESSAGE = 8;
@@ -136,7 +137,7 @@ function getExtensionFromUrl(url: string): string | null {
   try {
     const pathname = new URL(url).pathname;
     const match = pathname.match(/\.([a-z0-9]+)$/i);
-    return match ? match[1].toLowerCase() : null;
+    return match ? normalizeLowercaseStringOrEmpty(match[1]) : null;
   } catch {
     return null;
   }
diff --git a/extensions/tlon/src/tlon-api.ts b/extensions/tlon/src/tlon-api.ts
index 911ea6264bb..01ba8718f4d 100644
--- a/extensions/tlon/src/tlon-api.ts
+++ b/extensions/tlon/src/tlon-api.ts
@@ -1,6 +1,7 @@
 import crypto from "node:crypto";
 import { PutObjectCommand, S3Client } from "@aws-sdk/client-s3";
 import { getSignedUrl } from "@aws-sdk/s3-request-presigner";
+import { normalizeLowercaseStringOrEmpty } from "openclaw/plugin-sdk/text-runtime";
 import { authenticate } from "./urbit/auth.js";
 import { scryUrbitPath } from "./urbit/channel-ops.js";
 import { ssrfPolicyFromDangerouslyAllowPrivateNetwork } from "./urbit/context.js";
@@ -72,7 +73,7 @@ function getExtensionFromMimeType(mimeType?: string): string {
   if (!mimeType) {
     return ".jpg";
   }
-  return mimeToExt[mimeType.toLowerCase()] || ".jpg";
+  return mimeToExt[normalizeLowercaseStringOrEmpty(mimeType)] || ".jpg";
 }
 
 function hasCustomS3Creds(
diff --git a/extensions/voice-call/src/providers/mock.ts b/extensions/voice-call/src/providers/mock.ts
index 7dcb201ff30..133f9e3d862 100644
--- a/extensions/voice-call/src/providers/mock.ts
+++ b/extensions/voice-call/src/providers/mock.ts
@@ -1,4 +1,5 @@
 import crypto from "node:crypto";
+import { normalizeLowercaseStringOrEmpty } from "openclaw/plugin-sdk/text-runtime";
 import type {
   EndReason,
   GetCallStatusInput,
@@ -170,7 +171,7 @@ export class MockProvider implements VoiceCallProvider {
   }
 
   async getCallStatus(input: GetCallStatusInput): Promise<GetCallStatusResult> {
-    const id = input.providerCallId.toLowerCase();
+    const id = normalizeLowercaseStringOrEmpty(input.providerCallId);
     if (id.includes("stale") || id.includes("ended") || id.includes("completed")) {
       return { status: "completed", isTerminal: true };
     }
diff --git a/extensions/voice-call/src/providers/plivo.ts b/extensions/voice-call/src/providers/plivo.ts
index 2e257037e6c..138330ceabd 100644
--- a/extensions/voice-call/src/providers/plivo.ts
+++ b/extensions/voice-call/src/providers/plivo.ts
@@ -1,4 +1,5 @@
 import crypto from "node:crypto";
+import { normalizeLowercaseStringOrEmpty } from "openclaw/plugin-sdk/text-runtime";
 import type { PlivoConfig, WebhookSecurityConfig } from "../config.js";
 import { getHeader } from "../http-headers.js";
 import type {
@@ -480,7 +481,7 @@ export class PlivoProvider implements VoiceCallProvider {
 
   private static normalizeNumber(numberOrSip: string): string {
     const trimmed = numberOrSip.trim();
-    if (trimmed.toLowerCase().startsWith("sip:")) {
+    if (normalizeLowercaseStringOrEmpty(trimmed).startsWith("sip:")) {
       return trimmed;
     }
     return trimmed.replace(/[^\d+]/g, "");
diff --git a/extensions/voice-call/src/response-generator.ts b/extensions/voice-call/src/response-generator.ts
index 4bdae5bf269..85e16891bea 100644
--- a/extensions/voice-call/src/response-generator.ts
+++ b/extensions/voice-call/src/response-generator.ts
@@ -4,6 +4,7 @@
  */
 
 import crypto from "node:crypto";
+import { normalizeLowercaseStringOrEmpty } from "openclaw/plugin-sdk/text-runtime";
 import type { SessionEntry } from "../api.js";
 import type { VoiceCallConfig } from "./config.js";
 import type { CoreAgentDeps, CoreConfig } from "./core-bridge.js";
@@ -95,7 +96,7 @@ function tryParseSpokenJson(text: string): string | null {
 }
 
 function isLikelyMetaReasoningParagraph(paragraph: string): boolean {
-  const lower = paragraph.toLowerCase();
+  const lower = normalizeLowercaseStringOrEmpty(paragraph);
   if (!lower) {
     return false;
   }
diff --git a/src/channels/conversation-label.ts b/src/channels/conversation-label.ts
index 6f801c6a548..d652dec5a8b 100644
--- a/src/channels/conversation-label.ts
+++ b/src/channels/conversation-label.ts
@@ -1,5 +1,8 @@
 import type { MsgContext } from "../auto-reply/templating.js";
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import {
+  normalizeLowercaseStringOrEmpty,
+  normalizeOptionalString,
+} from "../shared/string-coerce.js";
 import { normalizeChatType } from "./chat-type.js";
 
 function extractConversationId(from?: string): string | undefined {
@@ -60,7 +63,7 @@ export function resolveConversationLabel(ctx: MsgContext): string | undefined {
   if (base.includes(id)) {
     return base;
   }
-  if (base.toLowerCase().includes(" id:")) {
+  if (normalizeLowercaseStringOrEmpty(base).includes(" id:")) {
     return base;
   }
   if (base.startsWith("#") || base.startsWith("@")) {
diff --git a/src/channels/plugins/chat-target-prefixes.ts b/src/channels/plugins/chat-target-prefixes.ts
index 7cb728f2ea8..fc6bc03bcd2 100644
--- a/src/channels/plugins/chat-target-prefixes.ts
+++ b/src/channels/plugins/chat-target-prefixes.ts
@@ -1,3 +1,5 @@
+import { normalizeLowercaseStringOrEmpty } from "../../shared/string-coerce.js";
+
 export type ServicePrefix<TService extends string> = { prefix: string; service: TService };
 
 export type ChatTargetPrefixesParams = {
@@ -94,7 +96,7 @@ export function resolveServicePrefixedTarget<TService extends string, TTarget>(p
     if (!remainder) {
       throw new Error(`${prefix} target is required`);
     }
-    const remainderLower = remainder.toLowerCase();
+    const remainderLower = normalizeLowercaseStringOrEmpty(remainder);
     if (params.isChatTarget(remainderLower)) {
       return params.parseTarget(remainder);
     }