diff --git a/extensions/diffs/src/tool.ts b/extensions/diffs/src/tool.ts
index 0851a292b9d..c0fcb36b4fd 100644
--- a/extensions/diffs/src/tool.ts
+++ b/extensions/diffs/src/tool.ts
@@ -428,10 +428,10 @@ function buildArtifactContext(
   }
 
   const artifactContext = {
-    agentId: normalizeContextString(context.agentId),
-    sessionId: normalizeContextString(context.sessionId),
-    messageChannel: normalizeContextString(context.messageChannel),
-    agentAccountId: normalizeContextString(context.agentAccountId),
+    agentId: normalizeOptionalString(context.agentId),
+    sessionId: normalizeOptionalString(context.sessionId),
+    messageChannel: normalizeOptionalString(context.messageChannel),
+    agentAccountId: normalizeOptionalString(context.agentAccountId),
   };
 
   return Object.values(artifactContext).some((value) => value !== undefined)
@@ -439,11 +439,6 @@ function buildArtifactContext(
     : undefined;
 }
 
-function normalizeContextString(value: string | undefined): string | undefined {
-  const normalized = normalizeOptionalString(value);
-  return normalized ? normalized : undefined;
-}
-
 function normalizeDiffInput(params: DiffsToolParams): DiffInput {
   const patch = params.patch?.trim();
   const before = params.before;
diff --git a/extensions/googlechat/src/monitor.ts b/extensions/googlechat/src/monitor.ts
index 1071716fbb3..bc916c80641 100644
--- a/extensions/googlechat/src/monitor.ts
+++ b/extensions/googlechat/src/monitor.ts
@@ -3,7 +3,7 @@ import {
   deliverTextOrMediaReply,
   resolveSendableOutboundReplyParts,
 } from "openclaw/plugin-sdk/reply-payload";
-import { normalizeOptionalString } from "openclaw/plugin-sdk/text-runtime";
+import { normalizeOptionalLowercaseString } from "openclaw/plugin-sdk/text-runtime";
 import type { OpenClawConfig } from "../runtime-api.js";
 import {
   createChannelReplyPipeline,
@@ -73,7 +73,7 @@ export function registerGoogleChatWebhookTarget(target: WebhookTarget): () => vo
 }
 
 function normalizeAudienceType(value?: string | null): GoogleChatAudienceType | undefined {
-  const normalized = normalizeOptionalString(value)?.toLowerCase();
+  const normalized = normalizeOptionalLowercaseString(value);
   if (normalized === "app-url" || normalized === "app_url" || normalized === "app") {
     return "app-url";
   }
diff --git a/extensions/telegram/src/status-reaction-variants.ts b/extensions/telegram/src/status-reaction-variants.ts
index 137e7b2eeda..32e974c8168 100644
--- a/extensions/telegram/src/status-reaction-variants.ts
+++ b/extensions/telegram/src/status-reaction-variants.ts
@@ -114,11 +114,6 @@ const STATUS_REACTION_EMOJI_KEYS: StatusReactionEmojiKey[] = [
   "compacting",
 ];
 
-function normalizeEmoji(value: string | undefined): string | undefined {
-  const trimmed = normalizeOptionalString(value);
-  return trimmed ? trimmed : undefined;
-}
-
 function toUniqueNonEmpty(values: string[]): string[] {
   return Array.from(new Set(values.map((value) => value.trim()).filter(Boolean)));
 }
@@ -128,18 +123,18 @@ export function resolveTelegramStatusReactionEmojis(params: {
   overrides?: StatusReactionEmojis;
 }): Required<StatusReactionEmojis> {
   const { overrides } = params;
-  const queuedFallback = normalizeEmoji(params.initialEmoji) ?? DEFAULT_EMOJIS.queued;
+  const queuedFallback = normalizeOptionalString(params.initialEmoji) ?? DEFAULT_EMOJIS.queued;
   return {
-    queued: normalizeEmoji(overrides?.queued) ?? queuedFallback,
-    thinking: normalizeEmoji(overrides?.thinking) ?? DEFAULT_EMOJIS.thinking,
-    tool: normalizeEmoji(overrides?.tool) ?? DEFAULT_EMOJIS.tool,
-    coding: normalizeEmoji(overrides?.coding) ?? DEFAULT_EMOJIS.coding,
-    web: normalizeEmoji(overrides?.web) ?? DEFAULT_EMOJIS.web,
-    done: normalizeEmoji(overrides?.done) ?? DEFAULT_EMOJIS.done,
-    error: normalizeEmoji(overrides?.error) ?? DEFAULT_EMOJIS.error,
-    stallSoft: normalizeEmoji(overrides?.stallSoft) ?? DEFAULT_EMOJIS.stallSoft,
-    stallHard: normalizeEmoji(overrides?.stallHard) ?? DEFAULT_EMOJIS.stallHard,
-    compacting: normalizeEmoji(overrides?.compacting) ?? DEFAULT_EMOJIS.compacting,
+    queued: normalizeOptionalString(overrides?.queued) ?? queuedFallback,
+    thinking: normalizeOptionalString(overrides?.thinking) ?? DEFAULT_EMOJIS.thinking,
+    tool: normalizeOptionalString(overrides?.tool) ?? DEFAULT_EMOJIS.tool,
+    coding: normalizeOptionalString(overrides?.coding) ?? DEFAULT_EMOJIS.coding,
+    web: normalizeOptionalString(overrides?.web) ?? DEFAULT_EMOJIS.web,
+    done: normalizeOptionalString(overrides?.done) ?? DEFAULT_EMOJIS.done,
+    error: normalizeOptionalString(overrides?.error) ?? DEFAULT_EMOJIS.error,
+    stallSoft: normalizeOptionalString(overrides?.stallSoft) ?? DEFAULT_EMOJIS.stallSoft,
+    stallHard: normalizeOptionalString(overrides?.stallHard) ?? DEFAULT_EMOJIS.stallHard,
+    compacting: normalizeOptionalString(overrides?.compacting) ?? DEFAULT_EMOJIS.compacting,
   };
 }
 
@@ -148,7 +143,7 @@ export function buildTelegramStatusReactionVariants(
 ): Map<string, string[]> {
   const variantsByRequested = new Map<string, string[]>();
   for (const key of STATUS_REACTION_EMOJI_KEYS) {
-    const requested = normalizeEmoji(emojis[key]);
+    const requested = normalizeOptionalString(emojis[key]);
     if (!requested) {
       continue;
     }
@@ -225,7 +220,7 @@ export function resolveTelegramReactionVariant(params: {
   variantsByRequestedEmoji: Map<string, string[]>;
   allowedEmojiReactions?: Set<TelegramReactionEmoji> | null;
 }): TelegramReactionEmoji | undefined {
-  const requestedEmoji = normalizeEmoji(params.requestedEmoji);
+  const requestedEmoji = normalizeOptionalString(params.requestedEmoji);
   if (!requestedEmoji) {
     return undefined;
   }
diff --git a/src/acp/types.ts b/src/acp/types.ts
index f12175dcb27..1d0e7c1d828 100644
--- a/src/acp/types.ts
+++ b/src/acp/types.ts
@@ -1,5 +1,5 @@
 import type { SessionId } from "@agentclientprotocol/sdk";
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import { normalizeOptionalLowercaseString } from "../shared/string-coerce.js";
 import { VERSION } from "../version.js";
 
 export const ACP_PROVENANCE_MODE_VALUES = ["off", "meta", "meta+receipt"] as const;
@@ -9,7 +9,7 @@ export type AcpProvenanceMode = (typeof ACP_PROVENANCE_MODE_VALUES)[number];
 export function normalizeAcpProvenanceMode(
   value: string | undefined,
 ): AcpProvenanceMode | undefined {
-  const normalized = normalizeOptionalString(value)?.toLowerCase();
+  const normalized = normalizeOptionalLowercaseString(value);
   if (!normalized) {
     return undefined;
   }
diff --git a/src/agents/pi-embedded-subscribe.tools.ts b/src/agents/pi-embedded-subscribe.tools.ts
index 115de5264ec..02dbc37ba91 100644
--- a/src/agents/pi-embedded-subscribe.tools.ts
+++ b/src/agents/pi-embedded-subscribe.tools.ts
@@ -2,7 +2,11 @@ import { getChannelPlugin, normalizeChannelId } from "../channels/plugins/index.
 import { normalizeTargetForProvider } from "../infra/outbound/target-normalization.js";
 import { splitMediaFromOutput } from "../media/parse.js";
 import { pluginRegistrationContractRegistry } from "../plugins/contracts/registry.js";
-import { normalizeOptionalString, readStringValue } from "../shared/string-coerce.js";
+import {
+  normalizeOptionalLowercaseString,
+  normalizeOptionalString,
+  readStringValue,
+} from "../shared/string-coerce.js";
 import { truncateUtf16Safe } from "../utils.js";
 import { collectTextContentBlocks } from "./content-blocks.js";
 import { type MessagingToolSend } from "./pi-embedded-messaging.js";
@@ -182,7 +186,7 @@ function readToolResultDetails(result: unknown): Record<string, unknown> | undef
 
 function readToolResultStatus(result: unknown): string | undefined {
   const status = readToolResultDetails(result)?.status;
-  return normalizeOptionalString(status)?.toLowerCase();
+  return normalizeOptionalLowercaseString(status);
 }
 
 function isExternalToolResult(result: unknown): boolean {
diff --git a/src/auto-reply/reply/dispatch-acp-delivery.ts b/src/auto-reply/reply/dispatch-acp-delivery.ts
index 0b691b5cd07..44603408200 100644
--- a/src/auto-reply/reply/dispatch-acp-delivery.ts
+++ b/src/auto-reply/reply/dispatch-acp-delivery.ts
@@ -3,7 +3,10 @@ import type { OpenClawConfig } from "../../config/config.js";
 import type { TtsAutoMode } from "../../config/types.tts.js";
 import { logVerbose } from "../../globals.js";
 import { formatErrorMessage } from "../../infra/errors.js";
-import { normalizeOptionalString } from "../../shared/string-coerce.js";
+import {
+  normalizeOptionalLowercaseString,
+  normalizeOptionalString,
+} from "../../shared/string-coerce.js";
 import { resolveStatusTtsSnapshot } from "../../tts/status-config.js";
 import { resolveConfiguredTtsMode } from "../../tts/tts-config.js";
 import type { FinalizedMsgContext } from "../templating.js";
@@ -53,11 +56,6 @@ type ToolMessageHandle = {
   messageId: string;
 };
 
-function normalizeDeliveryChannel(value: string | undefined): string | undefined {
-  const normalized = normalizeOptionalString(value)?.toLowerCase();
-  return normalized || undefined;
-}
-
 async function shouldTreatDeliveredTextAsVisible(params: {
   channel: string | undefined;
   kind: ReplyDispatchKind;
@@ -70,7 +68,7 @@ async function shouldTreatDeliveredTextAsVisible(params: {
   if (params.kind === "final") {
     return true;
   }
-  const channelId = normalizeDeliveryChannel(params.channel);
+  const channelId = normalizeOptionalLowercaseString(params.channel);
   if (!channelId) {
     return false;
   }
@@ -185,8 +183,8 @@ export function createAcpDispatchDeliveryCoordinator(params: {
     },
     toolMessageByCallId: new Map(),
   };
-  const directChannel = normalizeDeliveryChannel(params.ctx.Provider ?? params.ctx.Surface);
-  const routedChannel = normalizeDeliveryChannel(params.originatingChannel);
+  const directChannel = normalizeOptionalLowercaseString(params.ctx.Provider ?? params.ctx.Surface);
+  const routedChannel = normalizeOptionalLowercaseString(params.originatingChannel);
   const explicitAccountId = normalizeOptionalString(params.ctx.AccountId);
   const resolvedAccountId =
     explicitAccountId ??
diff --git a/src/auto-reply/status.ts b/src/auto-reply/status.ts
index 8b2662549dc..a65e1258023 100644
--- a/src/auto-reply/status.ts
+++ b/src/auto-reply/status.ts
@@ -31,7 +31,7 @@ import { resolveCommitHash } from "../infra/git-commit.js";
 import type { MediaUnderstandingDecision } from "../media-understanding/types.js";
 import { listPluginCommands } from "../plugins/commands.js";
 import { resolveAgentIdFromSessionKey } from "../routing/session-key.js";
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import { normalizeOptionalLowercaseString } from "../shared/string-coerce.js";
 import { resolveStatusTtsSnapshot } from "../tts/status-config.js";
 import {
   estimateUsageCost,
@@ -98,7 +98,7 @@ type StatusArgs = {
 type NormalizedAuthMode = "api-key" | "oauth" | "token" | "aws-sdk" | "mixed" | "unknown";
 
 function normalizeAuthMode(value?: string): NormalizedAuthMode | undefined {
-  const normalized = normalizeOptionalString(value)?.toLowerCase();
+  const normalized = normalizeOptionalLowercaseString(value);
   if (!normalized) {
     return undefined;
   }
diff --git a/src/channels/chat-type.ts b/src/channels/chat-type.ts
index fced60739fb..2f2914df8cf 100644
--- a/src/channels/chat-type.ts
+++ b/src/channels/chat-type.ts
@@ -1,9 +1,9 @@
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import { normalizeOptionalLowercaseString } from "../shared/string-coerce.js";
 
 export type ChatType = "direct" | "group" | "channel";
 
 export function normalizeChatType(raw?: string): ChatType | undefined {
-  const value = normalizeOptionalString(raw)?.toLowerCase();
+  const value = normalizeOptionalLowercaseString(raw);
   if (!value) {
     return undefined;
   }
diff --git a/src/config/sessions/types.ts b/src/config/sessions/types.ts
index 719b9c90ee7..140f8f05aac 100644
--- a/src/config/sessions/types.ts
+++ b/src/config/sessions/types.ts
@@ -235,14 +235,9 @@ export type SessionEntry = {
   acp?: SessionAcpMeta;
 };
 
-function normalizeRuntimeField(value: string | undefined): string | undefined {
-  const trimmed = normalizeOptionalString(value);
-  return trimmed ? trimmed : undefined;
-}
-
 export function normalizeSessionRuntimeModelFields(entry: SessionEntry): SessionEntry {
-  const normalizedModel = normalizeRuntimeField(entry.model);
-  const normalizedProvider = normalizeRuntimeField(entry.modelProvider);
+  const normalizedModel = normalizeOptionalString(entry.model);
+  const normalizedProvider = normalizeOptionalString(entry.modelProvider);
   let next = entry;
 
   if (!normalizedModel) {
@@ -327,8 +322,8 @@ export function mergeSessionEntryWithPolicy(
   // Guard against stale provider carry-over when callers patch runtime model
   // without also patching runtime provider.
   if (Object.hasOwn(patch, "model") && !Object.hasOwn(patch, "modelProvider")) {
-    const patchedModel = normalizeRuntimeField(patch.model);
-    const existingModel = normalizeRuntimeField(existing.model);
+    const patchedModel = normalizeOptionalString(patch.model);
+    const existingModel = normalizeOptionalString(existing.model);
     if (patchedModel && patchedModel !== existingModel) {
       delete next.modelProvider;
     }
diff --git a/src/infra/process-respawn.ts b/src/infra/process-respawn.ts
index 3c84288aea8..9fac4214600 100644
--- a/src/infra/process-respawn.ts
+++ b/src/infra/process-respawn.ts
@@ -1,5 +1,5 @@
 import { spawn } from "node:child_process";
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import { normalizeOptionalLowercaseString } from "../shared/string-coerce.js";
 import { formatErrorMessage } from "./errors.js";
 import { triggerOpenClawRestart } from "./restart.js";
 import { detectRespawnSupervisor } from "./supervisor-markers.js";
@@ -13,7 +13,7 @@ export type GatewayRespawnResult = {
 };
 
 function isTruthy(value: string | undefined): boolean {
-  const normalized = normalizeOptionalString(value)?.toLowerCase();
+  const normalized = normalizeOptionalLowercaseString(value);
   return normalized === "1" || normalized === "true" || normalized === "yes" || normalized === "on";
 }
 
diff --git a/src/infra/update-channels.ts b/src/infra/update-channels.ts
index 0ab618c8c52..3d0316257fb 100644
--- a/src/infra/update-channels.ts
+++ b/src/infra/update-channels.ts
@@ -1,4 +1,4 @@
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import { normalizeOptionalLowercaseString } from "../shared/string-coerce.js";
 
 export type UpdateChannel = "stable" | "beta" | "dev";
 export type UpdateChannelSource = "config" | "git-tag" | "git-branch" | "default";
@@ -8,7 +8,7 @@ export const DEFAULT_GIT_CHANNEL: UpdateChannel = "dev";
 export const DEV_BRANCH = "main";
 
 export function normalizeUpdateChannel(value?: string | null): UpdateChannel | null {
-  const normalized = normalizeOptionalString(value)?.toLowerCase();
+  const normalized = normalizeOptionalLowercaseString(value);
   if (!normalized) {
     return null;
   }
diff --git a/src/media-understanding/scope.ts b/src/media-understanding/scope.ts
index 7a68c901a6c..f61a9cca94a 100644
--- a/src/media-understanding/scope.ts
+++ b/src/media-understanding/scope.ts
@@ -1,11 +1,11 @@
 import { normalizeChatType } from "../channels/chat-type.js";
 import type { MediaUnderstandingScopeConfig } from "../config/types.tools.js";
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import { normalizeOptionalLowercaseString } from "../shared/string-coerce.js";
 
 export type MediaUnderstandingScopeDecision = "allow" | "deny";
 
 function normalizeDecision(value?: string | null): MediaUnderstandingScopeDecision | undefined {
-  const normalized = normalizeOptionalString(value)?.toLowerCase();
+  const normalized = normalizeOptionalLowercaseString(value);
   if (normalized === "allow") {
     return "allow";
   }
@@ -15,11 +15,6 @@ function normalizeDecision(value?: string | null): MediaUnderstandingScopeDecisi
   return undefined;
 }
 
-function normalizeMatch(value?: string | null): string | undefined {
-  const normalized = normalizeOptionalString(value)?.toLowerCase();
-  return normalized || undefined;
-}
-
 export function normalizeMediaUnderstandingChatType(raw?: string | null): string | undefined {
   return normalizeChatType(raw ?? undefined);
 }
@@ -35,9 +30,9 @@ export function resolveMediaUnderstandingScope(params: {
     return "allow";
   }
 
-  const channel = normalizeMatch(params.channel);
+  const channel = normalizeOptionalLowercaseString(params.channel);
   const chatType = normalizeMediaUnderstandingChatType(params.chatType);
-  const sessionKey = normalizeMatch(params.sessionKey) ?? "";
+  const sessionKey = normalizeOptionalLowercaseString(params.sessionKey) ?? "";
 
   for (const rule of scope.rules ?? []) {
     if (!rule) {
@@ -45,9 +40,9 @@ export function resolveMediaUnderstandingScope(params: {
     }
     const action = normalizeDecision(rule.action) ?? "allow";
     const match = rule.match ?? {};
-    const matchChannel = normalizeMatch(match.channel);
+    const matchChannel = normalizeOptionalLowercaseString(match.channel);
     const matchChatType = normalizeMediaUnderstandingChatType(match.chatType);
-    const matchPrefix = normalizeMatch(match.keyPrefix);
+    const matchPrefix = normalizeOptionalLowercaseString(match.keyPrefix);
 
     if (matchChannel && matchChannel !== channel) {
       continue;
diff --git a/src/media/channel-inbound-roots.ts b/src/media/channel-inbound-roots.ts
index b6143b2a360..b22f381a965 100644
--- a/src/media/channel-inbound-roots.ts
+++ b/src/media/channel-inbound-roots.ts
@@ -1,10 +1,10 @@
 import type { MsgContext } from "../auto-reply/templating.js";
 import { getBootstrapChannelPlugin } from "../channels/plugins/bootstrap-registry.js";
 import type { OpenClawConfig } from "../config/config.js";
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import { normalizeOptionalLowercaseString } from "../shared/string-coerce.js";
 
 function findChannelMessagingAdapter(channelId?: string | null) {
-  const normalized = normalizeOptionalString(channelId)?.toLowerCase();
+  const normalized = normalizeOptionalLowercaseString(channelId);
   if (!normalized) {
     return undefined;
   }
diff --git a/src/plugin-sdk/channel-streaming.ts b/src/plugin-sdk/channel-streaming.ts
index cd6a1755383..dac5307ea85 100644
--- a/src/plugin-sdk/channel-streaming.ts
+++ b/src/plugin-sdk/channel-streaming.ts
@@ -7,7 +7,7 @@ import type {
   SlackChannelStreamingConfig,
   TextChunkMode,
 } from "../config/types.base.js";
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import { normalizeOptionalLowercaseString } from "../shared/string-coerce.js";
 
 export type {
   ChannelDeliveryStreamingConfig,
@@ -48,7 +48,7 @@ function normalizeStreamingMode(value: unknown): string | null {
   if (typeof value !== "string") {
     return null;
   }
-  const normalized = normalizeOptionalString(value)?.toLowerCase();
+  const normalized = normalizeOptionalLowercaseString(value);
   return normalized || null;
 }
 
diff --git a/src/shared/string-coerce.ts b/src/shared/string-coerce.ts
index 45e14dbb274..f57315f0dc4 100644
--- a/src/shared/string-coerce.ts
+++ b/src/shared/string-coerce.ts
@@ -14,6 +14,10 @@ export function normalizeOptionalString(value: unknown): string | undefined {
   return normalizeNullableString(value) ?? undefined;
 }
 
+export function normalizeOptionalLowercaseString(value: unknown): string | undefined {
+  return normalizeOptionalString(value)?.toLowerCase();
+}
+
 export function resolvePrimaryStringValue(value: unknown): string | undefined {
   if (typeof value === "string") {
     return normalizeOptionalString(value);
diff --git a/src/tts/status-config.ts b/src/tts/status-config.ts
index f78ecccbfe1..a9412cfa6c2 100644
--- a/src/tts/status-config.ts
+++ b/src/tts/status-config.ts
@@ -2,7 +2,10 @@ import fs from "node:fs";
 import path from "node:path";
 import type { OpenClawConfig } from "../config/config.js";
 import type { TtsAutoMode, TtsConfig, TtsProvider } from "../config/types.tts.js";
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import {
+  normalizeOptionalLowercaseString,
+  normalizeOptionalString,
+} from "../shared/string-coerce.js";
 import { CONFIG_DIR, resolveUserPath } from "../utils.js";
 import { normalizeTtsAutoMode } from "./tts-auto-mode.js";
 
@@ -33,7 +36,7 @@ function resolveConfiguredTtsAutoMode(raw: TtsConfig): TtsAutoMode {
 function normalizeConfiguredSpeechProviderId(
   providerId: string | undefined,
 ): TtsProvider | undefined {
-  const normalized = normalizeOptionalString(providerId)?.toLowerCase();
+  const normalized = normalizeOptionalLowercaseString(providerId);
   if (!normalized) {
     return undefined;
   }
diff --git a/src/tts/tts-auto-mode.ts b/src/tts/tts-auto-mode.ts
index 8800c9b3046..759978ebce3 100644
--- a/src/tts/tts-auto-mode.ts
+++ b/src/tts/tts-auto-mode.ts
@@ -1,5 +1,5 @@
 import type { TtsAutoMode } from "../config/types.tts.js";
-import { normalizeOptionalString } from "../shared/string-coerce.js";
+import { normalizeOptionalLowercaseString } from "../shared/string-coerce.js";
 
 export const TTS_AUTO_MODES = new Set<TtsAutoMode>(["off", "always", "inbound", "tagged"]);
 
@@ -7,7 +7,7 @@ export function normalizeTtsAutoMode(value: unknown): TtsAutoMode | undefined {
   if (typeof value !== "string") {
     return undefined;
   }
-  const normalized = normalizeOptionalString(value)?.toLowerCase();
+  const normalized = normalizeOptionalLowercaseString(value);
   if (TTS_AUTO_MODES.has(normalized as TtsAutoMode)) {
     return normalized as TtsAutoMode;
   }