diff --git a/scripts/check-control-ui-performance.mjs b/scripts/check-control-ui-performance.mjs
index b691f7652e53..4c20d03ce229 100644
--- a/scripts/check-control-ui-performance.mjs
+++ b/scripts/check-control-ui-performance.mjs
@@ -10,9 +10,9 @@ const KIB = 1024;
 // Small, explicit headroom over the optimized baseline. Budget changes should
 // accompany an intentional loading or chunking decision.
 export const CONTROL_UI_PERFORMANCE_BUDGETS = Object.freeze({
-  startupJsRequests: 20,
+  startupJsRequests: 18,
   startupCssRequests: 1,
-  startupJsGzipBytes: 340 * KIB,
+  startupJsGzipBytes: 310 * KIB,
   startupCssGzipBytes: 42 * KIB,
   largestJsGzipBytes: 215 * KIB,
   largestCssGzipBytes: 42 * KIB,
diff --git a/ui/src/app/custom-theme-jitless.test.ts b/ui/src/app/custom-theme-jitless.test.ts
deleted file mode 100644
index cbe1c679aae2..000000000000
--- a/ui/src/app/custom-theme-jitless.test.ts
+++ /dev/null
@@ -1,41 +0,0 @@
-// Control UI tests cover Zod initialization under the Gateway's strict CSP.
-import { describe, expect, it, vi } from "vitest";
-
-describe("custom theme Zod initialization", () => {
-  it("enables jitless mode before object schemas probe dynamic code", async () => {
-    vi.resetModules();
-    const { z } = await import("zod");
-    const config = z.config();
-    const previousJitless = config.jitless;
-    delete config.jitless;
-
-    const NativeFunction = globalThis.Function;
-    let evalProbeAttempted = false;
-    const FunctionProxy = new Proxy(NativeFunction, {
-      apply(target, thisArg, args) {
-        evalProbeAttempted ||= args.length === 1 && args[0] === "";
-        return Reflect.apply(target, thisArg, args);
-      },
-      construct(target, args, newTarget) {
-        evalProbeAttempted ||= args.length === 1 && args[0] === "";
-        return Reflect.construct(target, args, newTarget);
-      },
-    });
-    vi.stubGlobal("Function", FunctionProxy);
-
-    try {
-      await import("./custom-theme.ts");
-
-      expect(z.config().jitless).toBe(true);
-      expect(evalProbeAttempted).toBe(false);
-    } finally {
-      vi.unstubAllGlobals();
-      if (previousJitless === undefined) {
-        delete config.jitless;
-      } else {
-        config.jitless = previousJitless;
-      }
-      vi.resetModules();
-    }
-  });
-});
diff --git a/ui/src/app/custom-theme.ts b/ui/src/app/custom-theme.ts
index 71f38474a039..34a4849e1cd3 100644
--- a/ui/src/app/custom-theme.ts
+++ b/ui/src/app/custom-theme.ts
@@ -1,12 +1,7 @@
 import { truncateUtf16Safe } from "@openclaw/normalization-core/utf16-slice";
 // Control UI module implements custom theme behavior.
-import { z } from "zod";
 import { normalizeOptionalString } from "../lib/string-coerce.ts";
 
-// The Control UI CSP forbids dynamic code generation. Zod snapshots this flag
-// when z.object() is constructed, before its eval-backed fast path can probe.
-z.config({ jitless: true });
-
 const TWEAKCN_HOSTS = new Set(["tweakcn.com", "www.tweakcn.com"]);
 const THEME_ID_PATTERN = /^[A-Za-z0-9][A-Za-z0-9_-]{0,127}$/;
 const CUSTOM_THEME_STYLE_ID = "openclaw-custom-theme";
@@ -93,29 +88,6 @@ const MODE_TOKEN_ORDER = [
 type ModeTokenName = (typeof MODE_TOKEN_ORDER)[number];
 type ThemeTokenMap = Record<ModeTokenName, string>;
 
-const REQUIRED_TWEAKCN_MODE_VARS = [
-  "background",
-  "foreground",
-  "card",
-  "card-foreground",
-  "popover",
-  "popover-foreground",
-  "primary",
-  "primary-foreground",
-  "secondary",
-  "secondary-foreground",
-  "muted",
-  "muted-foreground",
-  "accent",
-  "accent-foreground",
-  "destructive",
-  "destructive-foreground",
-  "border",
-  "input",
-  "ring",
-] as const;
-type RequiredTweakcnModeVar = (typeof REQUIRED_TWEAKCN_MODE_VARS)[number];
-
 export type ImportedCustomTheme = {
   sourceUrl: string;
   themeId: string;
@@ -125,40 +97,15 @@ export type ImportedCustomTheme = {
   dark: ThemeTokenMap;
 };
 
-const cssTokenSchema = z.string().max(MAX_CSS_TOKEN_LENGTH);
-
-function createStringShape<const T extends readonly string[]>(keys: T) {
-  return Object.fromEntries(keys.map((key) => [key, cssTokenSchema])) as Record<
-    T[number],
-    typeof cssTokenSchema
-  >;
+// Shape checks are intentionally shallow: normalizeStoredTokenMap and
+// resolveModeVar re-validate every token (presence, length, safe CSS) and
+// throw on anything off, so no schema library is needed at this boundary.
+function readThemeRecord(value: unknown): Record<string, unknown> | null {
+  return value && typeof value === "object" && !Array.isArray(value)
+    ? (value as Record<string, unknown>)
+    : null;
 }
 
-const tweakcnThemeSchema = z.object({
-  name: z.string().max(80).optional(),
-  cssVars: z.object({
-    theme: z
-      .object({
-        "font-sans": cssTokenSchema.optional(),
-        "font-mono": cssTokenSchema.optional(),
-      })
-      .optional(),
-    light: z.object(createStringShape(REQUIRED_TWEAKCN_MODE_VARS)),
-    dark: z.object(createStringShape(REQUIRED_TWEAKCN_MODE_VARS)),
-  }),
-});
-
-const importedCustomThemeSchema = z.object({
-  sourceUrl: z.string(),
-  themeId: z.string(),
-  label: z.string(),
-  importedAt: z.string(),
-  light: z.object(createStringShape(MODE_TOKEN_ORDER)),
-  dark: z.object(createStringShape(MODE_TOKEN_ORDER)),
-});
-
-type TweakcnThemePayload = z.infer<typeof tweakcnThemeSchema>;
-
 type TweakcnThemeResolution = {
   sourceUrl: string;
   fetchUrl: string;
@@ -305,7 +252,7 @@ function makeTokenMap(entries: Array<[ModeTokenName, string]>): ThemeTokenMap {
   return Object.fromEntries(entries) as ThemeTokenMap;
 }
 
-function normalizeStoredTokenMap(value: Record<string, string> | undefined): ThemeTokenMap | null {
+function normalizeStoredTokenMap(value: Record<string, unknown> | undefined): ThemeTokenMap | null {
   if (!value || typeof value !== "object") {
     return null;
   }
@@ -321,8 +268,8 @@ function normalizeStoredTokenMap(value: Record<string, string> | undefined): The
 }
 
 function resolveModeVar(
-  theme: Record<string, string | undefined>,
-  shared: Record<string, string | undefined> | undefined,
+  theme: Record<string, unknown>,
+  shared: Record<string, unknown> | undefined,
   key: string,
   fallback?: string,
 ) {
@@ -344,8 +291,8 @@ function resolveModeVar(
 
 function normalizeModeTokenMap(
   mode: "light" | "dark",
-  theme: Record<RequiredTweakcnModeVar, string>,
-  shared: Record<string, string | undefined> | undefined,
+  theme: Record<string, unknown>,
+  shared: Record<string, unknown> | undefined,
 ): ThemeTokenMap {
   const isLight = mode === "light";
   const contrastTarget = isLight ? "black" : "white";
@@ -461,22 +408,31 @@ function normalizeTweakcnThemeUrl(input: string): TweakcnThemeResolution {
 }
 
 export function parseImportedCustomTheme(value: unknown): ImportedCustomTheme | null {
-  const parsed = importedCustomThemeSchema.safeParse(value);
-  if (!parsed.success) {
+  const record = readThemeRecord(value);
+  if (!record) {
+    return null;
+  }
+  const { sourceUrl, themeId, label, importedAt } = record;
+  if (
+    typeof sourceUrl !== "string" ||
+    typeof themeId !== "string" ||
+    typeof label !== "string" ||
+    typeof importedAt !== "string"
+  ) {
     return null;
   }
   try {
-    requireThemeId(parsed.data.themeId);
-    const light = normalizeStoredTokenMap(parsed.data.light);
-    const dark = normalizeStoredTokenMap(parsed.data.dark);
+    requireThemeId(themeId);
+    const light = normalizeStoredTokenMap(readThemeRecord(record.light) ?? undefined);
+    const dark = normalizeStoredTokenMap(readThemeRecord(record.dark) ?? undefined);
     if (!light || !dark) {
       return null;
     }
     return {
-      sourceUrl: parsed.data.sourceUrl,
-      themeId: parsed.data.themeId,
-      label: describeThemeLabel(parsed.data.label),
-      importedAt: parsed.data.importedAt,
+      sourceUrl,
+      themeId,
+      label: describeThemeLabel(label),
+      importedAt,
       light,
       dark,
     };
@@ -489,19 +445,21 @@ function normalizeImportedCustomTheme(
   payload: unknown,
   resolution: Pick<TweakcnThemeResolution, "sourceUrl" | "themeId">,
 ): ImportedCustomTheme {
-  const parsed = tweakcnThemeSchema.safeParse(payload);
-  if (!parsed.success) {
+  const record = readThemeRecord(payload);
+  const cssVars = readThemeRecord(record?.cssVars);
+  const light = readThemeRecord(cssVars?.light);
+  const dark = readThemeRecord(cssVars?.dark);
+  const shared = cssVars?.theme === undefined ? undefined : readThemeRecord(cssVars.theme);
+  if (!record || !cssVars || !light || !dark || shared === null) {
     throw new Error("tweakcn returned an invalid theme payload.");
   }
-  const data: TweakcnThemePayload = parsed.data;
-  const shared = data.cssVars.theme;
   return {
     sourceUrl: resolution.sourceUrl,
     themeId: resolution.themeId,
-    label: describeThemeLabel(data.name),
+    label: describeThemeLabel(normalizeOptionalString(record.name)),
     importedAt: new Date().toISOString(),
-    light: normalizeModeTokenMap("light", data.cssVars.light, shared),
-    dark: normalizeModeTokenMap("dark", data.cssVars.dark, shared),
+    light: normalizeModeTokenMap("light", light, shared),
+    dark: normalizeModeTokenMap("dark", dark, shared),
   };
 }
 
diff --git a/ui/src/lib/config-form-utils.node.test.ts b/ui/src/lib/config-form-utils.node.test.ts
index 13c3031c2759..e13d62bbf236 100644
--- a/ui/src/lib/config-form-utils.node.test.ts
+++ b/ui/src/lib/config-form-utils.node.test.ts
@@ -89,11 +89,7 @@ describe("sanitizeRedactedFormForSubmit", () => {
     };
 
     expect(
-      sanitizeRedactedFormForSubmit(
-        form,
-        originalForm,
-        '{\n  gateway: {\n    mode: "remote"\n  }\n}\n',
-      ),
+      sanitizeRedactedFormForSubmit(form, originalForm, { gateway: { mode: "remote" } }),
     ).toEqual({
       gateway: {
         mode: "remote",
@@ -113,11 +109,9 @@ describe("sanitizeRedactedFormForSubmit", () => {
     const originalForm = cloneConfigObject(form);
 
     expect(
-      sanitizeRedactedFormForSubmit(
-        form,
-        originalForm,
-        '{\n  gateway: {\n    mode: "remote",\n    remote: {\n      token: "__OPENCLAW_REDACTED__"\n    }\n  }\n}\n',
-      ),
+      sanitizeRedactedFormForSubmit(form, originalForm, {
+        gateway: { mode: "remote", remote: { token: "__OPENCLAW_REDACTED__" } },
+      }),
     ).toEqual(form);
   });
 
@@ -135,13 +129,9 @@ describe("sanitizeRedactedFormForSubmit", () => {
       },
     };
 
-    expect(
-      sanitizeRedactedFormForSubmit(
-        form,
-        originalForm,
-        "{\n  gateway: {\n    remote: {}\n  }\n}\n",
-      ),
-    ).toEqual(form);
+    expect(sanitizeRedactedFormForSubmit(form, originalForm, { gateway: { remote: {} } })).toEqual(
+      form,
+    );
   });
 
   it("prunes empty object parents when they are absent from original raw config", () => {
@@ -157,9 +147,7 @@ describe("sanitizeRedactedFormForSubmit", () => {
     };
     const originalForm = cloneConfigObject(form);
 
-    expect(
-      sanitizeRedactedFormForSubmit(form, originalForm, '{\n  ui: { theme: "dark" }\n}\n'),
-    ).toEqual({
+    expect(sanitizeRedactedFormForSubmit(form, originalForm, { ui: { theme: "dark" } })).toEqual({
       ui: { theme: "dark" },
     });
   });
@@ -175,15 +163,13 @@ describe("sanitizeRedactedFormForSubmit", () => {
     const originalForm = cloneConfigObject(form);
 
     expect(
-      sanitizeRedactedFormForSubmit(
-        form,
-        originalForm,
-        '{\n  channels: { slack: { tokens: ["second-token"] } }\n}\n',
-      ),
+      sanitizeRedactedFormForSubmit(form, originalForm, {
+        channels: { slack: { tokens: ["second-token"] } },
+      }),
     ).toEqual(form);
   });
 
-  it("leaves the form unchanged when original raw config cannot be parsed", () => {
+  it("leaves the form unchanged when the original raw config has no parsed snapshot", () => {
     const form = {
       gateway: {
         remote: {
@@ -193,7 +179,7 @@ describe("sanitizeRedactedFormForSubmit", () => {
     };
     const originalForm = cloneConfigObject(form);
 
-    expect(sanitizeRedactedFormForSubmit(form, originalForm, "{")).toEqual(form);
+    expect(sanitizeRedactedFormForSubmit(form, originalForm, null)).toEqual(form);
   });
 });
 describe("prototype pollution prevention", () => {
diff --git a/ui/src/lib/config-form-utils.ts b/ui/src/lib/config-form-utils.ts
index 36d4d971495f..0ff201025afb 100644
--- a/ui/src/lib/config-form-utils.ts
+++ b/ui/src/lib/config-form-utils.ts
@@ -1,6 +1,5 @@
 // Control UI controller manages form utils gateway state.
 import { isRecord } from "@openclaw/normalization-core/record-coerce";
-import JSON5 from "json5";
 
 export function cloneConfigObject<T>(value: T): T {
   return structuredClone(value);
@@ -93,19 +92,11 @@ function sanitizeRedactedValue(params: {
 export function sanitizeRedactedFormForSubmit(
   form: Record<string, unknown>,
   originalForm: Record<string, unknown> | null | undefined,
-  originalRaw: string,
+  parsedOriginalRaw: Record<string, unknown> | null,
 ): Record<string, unknown> {
-  if (!originalForm || !originalRaw) {
-    return form;
-  }
-
-  let parsedOriginalRaw: unknown;
-  try {
-    parsedOriginalRaw = JSON5.parse(originalRaw);
-  } catch {
-    return form;
-  }
-  if (!isRecord(parsedOriginalRaw)) {
+  // Callers parse the original raw once at snapshot ingestion so this submit
+  // path stays synchronous and never races the lazy JSON5 parser.
+  if (!originalForm || !parsedOriginalRaw) {
     return form;
   }
 
diff --git a/ui/src/lib/config/index.ts b/ui/src/lib/config/index.ts
index 7d046dab046b..663bcdbb5758 100644
--- a/ui/src/lib/config/index.ts
+++ b/ui/src/lib/config/index.ts
@@ -1,5 +1,4 @@
 // Control UI runtime config capability and shared config-domain mutations.
-import JSON5 from "json5";
 import type { GatewayBrowserClient } from "../../api/gateway.ts";
 import type { ConfigSchemaResponse, ConfigSnapshot, ConfigUiHints } from "../../api/types.ts";
 import { schemaType, type JsonSchema } from "../../components/config-form.shared.ts";
@@ -12,6 +11,7 @@ import {
   serializeConfigForm,
   setPathValue,
 } from "../config-form-utils.ts";
+import { parseJson5Text, warmJson5 } from "../json5-runtime.ts";
 import { createAppliedConfigRefreshController } from "./applied-refresh.ts";
 
 export type ConfigAutoSaveStatus = "idle" | "saving" | "saved" | "error" | "conflict";
@@ -44,6 +44,8 @@ type ConfigState = {
   configLoading: boolean;
   configRaw: string;
   configRawOriginal: string;
+  configRawOriginalParsed: Record<string, unknown> | null;
+  configRawOriginalParsePending: Promise<void> | null;
   configValid: boolean | null;
   configIssues: unknown[];
   configSaving: boolean;
@@ -150,6 +152,8 @@ function createInitialConfigState(snapshot?: Partial<RuntimeConfigGatewaySnapsho
     configLoading: false,
     configRaw: "{\n}\n",
     configRawOriginal: "",
+    configRawOriginalParsed: null,
+    configRawOriginalParsePending: null,
     configValid: null,
     configIssues: [],
     configSaving: false,
@@ -347,7 +351,7 @@ function applyConfigSnapshot(
   if (!preservePendingChanges) {
     state.configForm = cloneConfigObject(editableConfig ?? {});
     state.configFormOriginal = cloneConfigObject(editableConfig ?? {});
-    state.configRawOriginal = rawFromSnapshot;
+    setConfigRawOriginal(state, rawFromSnapshot);
     state.configFormDirty = false;
     state.configFormMode = "form";
     state.configDraftBaseHash = snapshot.hash ?? null;
@@ -529,7 +533,7 @@ function serializeFormForSubmit(state: ConfigState): string {
   const sanitized = sanitizeRedactedFormForSubmit(
     form,
     state.configFormOriginal,
-    state.configRawOriginal,
+    state.configRawOriginalParsed,
   );
   return serializeConfigForm(sanitized);
 }
@@ -558,7 +562,7 @@ function adoptConfigSetAck(state: ConfigState, submittedRaw: string, ackHash: st
   };
   state.configValid = true;
   state.configIssues = [];
-  state.configRawOriginal = submittedRaw;
+  setConfigRawOriginal(state, submittedRaw);
   if (parsed) {
     state.configFormOriginal = cloneConfigObject(parsed);
   }
@@ -599,10 +603,19 @@ async function submitConfigChange(
   }
   const connectionEpoch = currentConfigConnectionEpoch(state);
   const isCurrent = () => isCurrentConfigConnection(state, client, connectionEpoch);
+  // Claim busy before any await so a second click cannot slip past the busy
+  // state while a JSON5 original parse settles; finally releases it.
   state[busyKey] = true;
   state.lastError = null;
   state.chatError = null;
   try {
+    if (state.configRawOriginalParsePending) {
+      // JSON5 originals parse asynchronously on first load; sanitize needs them.
+      await state.configRawOriginalParsePending;
+      if (!isCurrent()) {
+        return false;
+      }
+    }
     const raw = serializeFormForSubmit(state);
     const baseHash = state.configDraftBaseHash ?? state.configSnapshot?.hash;
     if (!baseHash) {
@@ -685,6 +698,11 @@ function teardownFlushConfigDraft(
   client: GatewayBrowserClient,
   baseHash: string,
 ): void {
+  // Must stay synchronous: page unload destroys the context before any
+  // deferred work runs. If a JSON5 original parse is still pending, sanitize
+  // passes placeholders through; the gateway restores restorable sentinels
+  // (restoreRedactedValues) and rejects unrestorable ones, so the worst case
+  // matches not flushing at all while the common case saves the draft.
   const raw = serializeFormForSubmit(state);
   void client.request("config.set", { raw, baseHash }).catch(() => undefined);
 }
@@ -706,6 +724,16 @@ async function autoSaveConfig(
   }
   const connectionEpoch = currentConfigConnectionEpoch(state);
   const isCurrent = () => isCurrentConfigConnection(state, client, connectionEpoch);
+  if (state.configRawOriginalParsePending) {
+    // JSON5 originals parse asynchronously on first load; sanitize needs them.
+    // Await only when pending: teardown flushes rely on a synchronous prefix.
+    // Entry stays serialized across this await: runAutoSave's synchronous
+    // in-flight check folds concurrent triggers into one trailing save.
+    await state.configRawOriginalParsePending;
+    if (!isCurrent() || !state.configFormDirty || state.configFormMode !== "form") {
+      return false;
+    }
+  }
   const submittedRaw = serializeFormForSubmit(state);
   const baseHash = state.configDraftBaseHash ?? state.configSnapshot?.hash;
   if (!baseHash) {
@@ -869,7 +897,7 @@ async function lookupConfigSchemaPath(
 
 function parseConfigRawDraft(raw: string): Record<string, unknown> | null {
   try {
-    const parsed = JSON5.parse(raw) as unknown;
+    const parsed = parseJson5Text(raw);
     return parsed && typeof parsed === "object" && !Array.isArray(parsed)
       ? (parsed as Record<string, unknown>)
       : null;
@@ -878,6 +906,41 @@ function parseConfigRawDraft(raw: string): Record<string, unknown> | null {
   }
 }
 
+// Parse the authoritative raw once at ingestion so submit-time sanitizing
+// stays synchronous and never races the lazy JSON5 parser. Submit paths await
+// configRawOriginalParsePending so a JSON5 config racing the first parser load
+// cannot bypass redaction sanitizing.
+function setConfigRawOriginal(state: ConfigState, raw: string) {
+  state.configRawOriginal = raw;
+  state.configRawOriginalParsePending = null;
+  try {
+    state.configRawOriginalParsed = asConfigRecord(parseJson5Text(raw));
+    return;
+  } catch {
+    state.configRawOriginalParsed = null;
+  }
+  const pending = warmJson5()
+    .then((json5) => {
+      if (state.configRawOriginal !== raw || state.configRawOriginalParsePending !== pending) {
+        return;
+      }
+      try {
+        state.configRawOriginalParsed = asConfigRecord(json5.parse(raw));
+      } catch {
+        state.configRawOriginalParsed = null;
+      }
+    })
+    // Never-rejecting and self-clearing: submit gates await this promise, and
+    // a failed chunk load must not wedge every later save of this state.
+    .catch(() => undefined)
+    .finally(() => {
+      if (state.configRawOriginalParsePending === pending) {
+        state.configRawOriginalParsePending = null;
+      }
+    });
+  state.configRawOriginalParsePending = pending;
+}
+
 function mutateConfigForm(state: ConfigState, mutate: (draft: Record<string, unknown>) => void) {
   let base: Record<string, unknown>;
   if (state.configFormDirty && state.configFormMode === "raw") {
@@ -986,6 +1049,9 @@ function updateConfigFormValue(state: ConfigState, path: Array<string | number>,
 }
 
 function updateConfigRawValue(state: ConfigState, value: string) {
+  // Raw drafts may carry JSON5 comments; warm the parser before any
+  // mutateConfigForm/diff path needs it synchronously.
+  void warmJson5().catch(() => undefined);
   state.configRaw = value;
   // A raw-text edit becomes the authoritative draft; without this,
   // serializeFormForSubmit would submit the stale form and drop raw edits.
diff --git a/ui/src/lib/json5-runtime.test.ts b/ui/src/lib/json5-runtime.test.ts
new file mode 100644
index 000000000000..4e9d6f801c7e
--- /dev/null
+++ b/ui/src/lib/json5-runtime.test.ts
@@ -0,0 +1,16 @@
+// @vitest-environment node
+import { describe, expect, it } from "vitest";
+import { parseJson5Text, warmJson5 } from "./json5-runtime.ts";
+
+const COMMENTED = '// comment\n{\n  "a": 1, // trailing\n}\n';
+
+describe("json5 runtime boundary", () => {
+  it("parses strict JSON on the fast path", () => {
+    expect(parseJson5Text('{"a":1}')).toEqual({ a: 1 });
+  });
+
+  it("parses JSON5 text once the module is warmed", async () => {
+    await warmJson5();
+    expect(parseJson5Text(COMMENTED)).toEqual({ a: 1 });
+  });
+});
diff --git a/ui/src/lib/json5-runtime.ts b/ui/src/lib/json5-runtime.ts
new file mode 100644
index 000000000000..e9e07ee13613
--- /dev/null
+++ b/ui/src/lib/json5-runtime.ts
@@ -0,0 +1,44 @@
+// Lazy JSON5 boundary: strict JSON parses without the library, so json5 stays
+// out of the startup graph and loads only for config text that needs it.
+type Json5Module = { parse: (text: string) => unknown };
+
+let json5: Json5Module | null = null;
+let json5Loading: Promise<Json5Module> | null = null;
+
+export function isJson5Warm(): boolean {
+  return json5 !== null;
+}
+
+export function warmJson5(): Promise<Json5Module> {
+  json5Loading ??= import("json5").then(
+    (mod) => {
+      json5 = mod.default;
+      return json5;
+    },
+    (error: unknown) => {
+      // Transient chunk-load failures must not pin a rejected loader forever;
+      // the next warm retries the import.
+      json5Loading = null;
+      throw error;
+    },
+  );
+  return json5Loading;
+}
+
+/**
+ * Strict-JSON fast path with a JSON5 fallback once the module is warmed.
+ * Callers on the config surfaces warm the module before raw drafts can exist;
+ * if a JSON5-only text races the warm-up, this throws like a parse failure and
+ * the caller's existing invalid-draft handling applies until retry.
+ */
+export function parseJson5Text(raw: string): unknown {
+  try {
+    return JSON.parse(raw) as unknown;
+  } catch (jsonError) {
+    if (json5) {
+      return json5.parse(raw);
+    }
+    void warmJson5().catch(() => undefined);
+    throw jsonError;
+  }
+}
diff --git a/ui/src/pages/config/view.browser.test.ts b/ui/src/pages/config/view.browser.test.ts
index 3a9725fb3a58..50cf4c06a007 100644
--- a/ui/src/pages/config/view.browser.test.ts
+++ b/ui/src/pages/config/view.browser.test.ts
@@ -1,11 +1,18 @@
 // Control UI tests cover config behavior.
 import { render } from "lit";
-import { describe, expect, it, vi } from "vitest";
+import { beforeAll, describe, expect, it, vi } from "vitest";
 import "../../styles.css";
 import type { ThemeMode, ThemeName } from "../../app/theme.ts";
+import { warmJson5 } from "../../lib/json5-runtime.ts";
 import { createConfigViewState, renderConfig, type ConfigProps } from "./view.ts";
 
 describe("config view", () => {
+  // The view module warms the lazy JSON5 parser on load; tests assert the
+  // steady state where raw diffs parse synchronously.
+  beforeAll(async () => {
+    await warmJson5();
+  });
+
   const baseProps = () => ({
     raw: "{\n}\n",
     originalRaw: "{\n}\n",
diff --git a/ui/src/pages/config/view.ts b/ui/src/pages/config/view.ts
index e28a12f37cfb..1922cfd2ba69 100644
--- a/ui/src/pages/config/view.ts
+++ b/ui/src/pages/config/view.ts
@@ -1,6 +1,5 @@
 // Control UI view renders config screen content.
 import { truncateUtf16Safe } from "@openclaw/normalization-core/utf16-slice";
-import JSON5 from "json5";
 import { html, nothing } from "lit";
 import type { QueueMode } from "../../../../src/auto-reply/reply/queue/types.js";
 import type { ConfigUiHints } from "../../api/types.ts";
@@ -25,12 +24,12 @@ import {
   schemaType,
   type JsonSchema,
 } from "../../components/config-form.shared.ts";
-import "../../components/tooltip.ts";
 import {
   analyzeConfigSchema,
   renderConfigForm,
   type ConfigSchemaAnalysis,
 } from "../../components/config-form.ts";
+import "../../components/tooltip.ts";
 import { icons } from "../../components/icons.ts";
 import { getLobsterdex, getLobsterdexEntries } from "../../components/lobster-dex.ts";
 import {
@@ -47,6 +46,7 @@ import {
 } from "../../components/settings-ui.ts";
 import { t } from "../../i18n/index.ts";
 import type { ConfigAutoSaveStatus } from "../../lib/config/index.ts";
+import { isJson5Warm, parseJson5Text, warmJson5 } from "../../lib/json5-runtime.ts";
 import type { RealtimeTalkInputDevice } from "../chat/realtime-talk-input.ts";
 import { renderSettingsSelectRow } from "./settings-select-row.ts";
 import {
@@ -54,6 +54,10 @@ import {
   COMMUNICATION_SETTINGS_TARGET_IDS,
 } from "./settings-targets.ts";
 
+// The config editor is where JSON5 text first appears; warm the parser with
+// the page instead of racing the first raw-draft keystroke.
+void warmJson5().catch(() => undefined);
+
 const TEXT_SCALE_LABELS: Record<TextScaleStop, string> = {
   90: "configView.textSizes.small",
   100: "configView.textSizes.default",
@@ -746,8 +750,8 @@ function computeRawDiff(
     return viewState.rawDiffCache.diff;
   }
   try {
-    const originalValue = JSON5.parse(original) as unknown;
-    const currentValue = JSON5.parse(current) as unknown;
+    const originalValue = parseJson5Text(original);
+    const currentValue = parseJson5Text(current);
     if (
       !originalValue ||
       !currentValue ||
@@ -766,7 +770,12 @@ function computeRawDiff(
     viewState.rawDiffCache = { original, current, diff };
     return diff;
   } catch {
-    viewState.rawDiffCache = { original, current, diff: [] };
+    // While the lazy JSON5 parser is still loading, a parse failure may be
+    // transient; skip the cache so the next render retries instead of pinning
+    // an empty diff for this text pair.
+    if (isJson5Warm()) {
+      viewState.rawDiffCache = { original, current, diff: [] };
+    }
     return [];
   }
 }
@@ -1799,6 +1808,13 @@ export function renderConfig(props: ConfigProps) {
     formMode === "raw" && hasRawChanges && viewState.rawDiffOpen
       ? computeRawDiff(viewState, props.originalRaw, props.raw)
       : [];
+  if (formMode === "raw" && hasRawChanges && viewState.rawDiffOpen && !isJson5Warm()) {
+    // First diff open can race the lazy JSON5 parser; re-render when it lands
+    // so the pending-changes list fills in instead of staying empty.
+    void warmJson5()
+      .then(() => requestUpdate())
+      .catch(() => undefined);
+  }
   // Includes the app updater: writes are suspended while it runs, so raw
   // Save/Discard must read busy instead of silently no-opping.
   const configBusy = props.loading || props.saving || props.applying || props.updating;