diff --git a/extensions/line/src/download.ts b/extensions/line/src/download.ts
index dda32eb064d..ec7db64d732 100644
--- a/extensions/line/src/download.ts
+++ b/extensions/line/src/download.ts
@@ -2,6 +2,7 @@ import fs from "node:fs";
 import { messagingApi } from "@line/bot-sdk";
 import { logVerbose } from "openclaw/plugin-sdk/runtime-env";
 import { buildRandomTempFilePath } from "openclaw/plugin-sdk/temp-path";
+import { lowercasePreservingWhitespace } from "openclaw/plugin-sdk/text-runtime";
 
 interface DownloadResult {
   path: string;
@@ -78,7 +79,7 @@ function detectContentType(buffer: Buffer): string {
       return "image/webp";
     }
     if (hasFtypBox) {
-      const majorBrand = buffer.toString("ascii", 8, 12).toLowerCase();
+      const majorBrand = lowercasePreservingWhitespace(buffer.toString("ascii", 8, 12));
       if (AUDIO_BRANDS.has(majorBrand)) {
         return "audio/mp4";
       }
diff --git a/src/agents/pi-embedded-runner/model.provider-runtime.test-support.ts b/src/agents/pi-embedded-runner/model.provider-runtime.test-support.ts
index 2001abd7954..26932f10f82 100644
--- a/src/agents/pi-embedded-runner/model.provider-runtime.test-support.ts
+++ b/src/agents/pi-embedded-runner/model.provider-runtime.test-support.ts
@@ -1,3 +1,4 @@
+import { lowercasePreservingWhitespace } from "../../shared/string-coerce.js";
 import type { OpenRouterModelCapabilities } from "./openrouter-model-capabilities.js";
 
 const OPENAI_BASE_URL = "https://api.openai.com/v1";
@@ -129,7 +130,7 @@ function buildDynamicModel(
   >,
 ) {
   const modelId = params.modelId.trim();
-  const lower = modelId.toLowerCase();
+  const lower = lowercasePreservingWhitespace(modelId);
   switch (params.provider) {
     case "openrouter": {
       const capabilities = options.getOpenRouterModelCapabilities(modelId);
diff --git a/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.test-support.ts b/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.test-support.ts
index 4e913a4a9ce..a57abe219b7 100644
--- a/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.test-support.ts
+++ b/src/agents/pi-embedded-runner/run/attempt.spawn-workspace.test-support.ts
@@ -13,7 +13,10 @@ import type {
   IngestResult,
 } from "../../../context-engine/types.js";
 import { formatErrorMessage } from "../../../infra/errors.js";
-import { normalizeLowercaseStringOrEmpty } from "../../../shared/string-coerce.js";
+import {
+  normalizeLowercaseStringOrEmpty,
+  normalizeOptionalLowercaseString,
+} from "../../../shared/string-coerce.js";
 import type { EmbeddedContextFile } from "../../pi-embedded-helpers.js";
 import type { MessagingToolSend } from "../../pi-embedded-messaging.js";
 import type { WorkspaceBootstrapFile } from "../../workspace.js";
@@ -477,10 +480,18 @@ vi.mock("../cache-ttl.js", () => ({
             modelId?: string;
           }
         | undefined;
-      if (context?.provider && entry?.provider?.toLowerCase() !== context.provider.toLowerCase()) {
+      if (
+        context?.provider &&
+        normalizeOptionalLowercaseString(entry?.provider) !==
+          normalizeOptionalLowercaseString(context.provider)
+      ) {
         continue;
       }
-      if (context?.modelId && entry?.modelId?.toLowerCase() !== context.modelId.toLowerCase()) {
+      if (
+        context?.modelId &&
+        normalizeOptionalLowercaseString(entry?.modelId) !==
+          normalizeOptionalLowercaseString(context.modelId)
+      ) {
         continue;
       }
       const timestamp = entry?.timestamp;
diff --git a/src/auto-reply/test-helpers/command-auth-registry-fixture.ts b/src/auto-reply/test-helpers/command-auth-registry-fixture.ts
index ba4bf04b832..41b5d623f11 100644
--- a/src/auto-reply/test-helpers/command-auth-registry-fixture.ts
+++ b/src/auto-reply/test-helpers/command-auth-registry-fixture.ts
@@ -1,6 +1,7 @@
 import { afterEach, beforeEach } from "vitest";
 import { normalizeE164 } from "../../plugin-sdk/account-resolution.js";
 import { setActivePluginRegistry } from "../../plugins/runtime.js";
+import { lowercasePreservingWhitespace } from "../../shared/string-coerce.js";
 import { createOutboundTestPlugin, createTestRegistry } from "../../test-utils/channel-plugins.js";
 
 function formatDiscordAllowFromEntries(allowFrom: Array<string | number>): string[] {
@@ -8,7 +9,7 @@ function formatDiscordAllowFromEntries(allowFrom: Array<string | number>): strin
     .map((entry) => String(entry).trim())
     .filter(Boolean)
     .map((entry) => entry.replace(/^(discord|user|pk):/i, "").replace(/^<@!?(\d+)>$/, "$1"))
-    .map((entry) => entry.toLowerCase());
+    .map((entry) => lowercasePreservingWhitespace(entry));
 }
 
 function normalizePhoneAllowFromEntries(allowFrom: Array<string | number>): string[] {
diff --git a/src/memory-host-sdk/host/multimodal.ts b/src/memory-host-sdk/host/multimodal.ts
index 1ccbd49c9ee..baf97c39666 100644
--- a/src/memory-host-sdk/host/multimodal.ts
+++ b/src/memory-host-sdk/host/multimodal.ts
@@ -1,4 +1,7 @@
-import { normalizeLowercaseStringOrEmpty } from "../../shared/string-coerce.js";
+import {
+  lowercasePreservingWhitespace,
+  normalizeLowercaseStringOrEmpty,
+} from "../../shared/string-coerce.js";
 
 const MEMORY_MULTIMODAL_SPECS = {
   image: {
@@ -79,7 +82,10 @@ export function buildCaseInsensitiveExtensionGlob(extension: string): string {
   if (!normalized) {
     return "*";
   }
-  const parts = Array.from(normalized, (char) => `[${char.toLowerCase()}${char.toUpperCase()}]`);
+  const parts = Array.from(normalized, (char) => {
+    const lower = lowercasePreservingWhitespace(char);
+    return `[${lower}${char.toUpperCase()}]`;
+  });
   return `*.${parts.join("")}`;
 }
 
diff --git a/src/param-key.ts b/src/param-key.ts
index 8d62d9a2c9f..ab8790caeb4 100644
--- a/src/param-key.ts
+++ b/src/param-key.ts
@@ -1,8 +1,10 @@
+import { lowercasePreservingWhitespace } from "./shared/string-coerce.js";
+
 function toSnakeCaseKey(key: string): string {
-  return key
+  const snakeKey = key
     .replace(/([A-Z]+)([A-Z][a-z])/g, "$1_$2")
-    .replace(/([a-z0-9])([A-Z])/g, "$1_$2")
-    .toLowerCase();
+    .replace(/([a-z0-9])([A-Z])/g, "$1_$2");
+  return lowercasePreservingWhitespace(snakeKey);
 }
 
 export function readSnakeCaseParamRaw(params: Record<string, unknown>, key: string): unknown {