diff --git a/src/index.ts b/src/index.ts
index c769e99..3439c58 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -227,6 +227,10 @@ export async function listModels(options: Omit<ListModelsOptions, 'budgetManager
 
 // Keep the original export for backward compatibility
 export { listAvailableModels };
+export {
+  assertValidSmartRouterOptions,
+  validateSmartRouterOptions
+} from "./router/smartRouterValidator";
 
 // Export types for TypeScript users
 export type {
@@ -252,6 +256,12 @@ export type {
   ApiKeyConfig
 } from "./router/types";
 
+export type {
+  SmartRouterTaskConfig,
+  SmartRouterValidationOptions,
+  SmartRouterValidationResult
+} from "./router/smartRouterValidator";
+
 /**
  * Model configuration for bulk registration
  */
diff --git a/src/router/smartRouterValidator.ts b/src/router/smartRouterValidator.ts
new file mode 100644
index 0000000..22cf57f
--- /dev/null
+++ b/src/router/smartRouterValidator.ts
@@ -0,0 +1,191 @@
+export interface SmartRouterValidationOptions {
+  defaultModel?: string;
+  confidenceThreshold?: number;
+  modelOverrides?: Record<string, string>;
+  taskClassification?: Record<string, SmartRouterTaskConfig>;
+  cacheDetections?: boolean;
+  detectionCacheTtlMs?: number;
+  enableAnalytics?: boolean;
+}
+
+export interface SmartRouterTaskConfig {
+  keywords?: string[];
+  patterns?: Array<string | RegExp>;
+  model: string;
+  confidenceThreshold?: number;
+}
+
+export interface SmartRouterValidationResult {
+  valid: boolean;
+  errors: string[];
+}
+
+/**
+ * Validate smart-router configuration before it reaches routing logic.
+ */
+export function validateSmartRouterOptions(
+  options: SmartRouterValidationOptions
+): SmartRouterValidationResult {
+  const errors: string[] = [];
+
+  if (!options || typeof options !== "object" || Array.isArray(options)) {
+    return {
+      valid: false,
+      errors: ["Smart router options must be an object"]
+    };
+  }
+
+  validateOptionalModel("defaultModel", options.defaultModel, errors);
+  validateConfidenceThreshold("confidenceThreshold", options.confidenceThreshold, errors);
+  validateBoolean("cacheDetections", options.cacheDetections, errors);
+  validateBoolean("enableAnalytics", options.enableAnalytics, errors);
+  validateCacheTtl(options.detectionCacheTtlMs, errors);
+  validateModelOverrides(options.modelOverrides, errors);
+  validateTaskClassification(options.taskClassification, errors);
+
+  return {
+    valid: errors.length === 0,
+    errors
+  };
+}
+
+/**
+ * Throw a single helpful error when smart-router configuration is invalid.
+ */
+export function assertValidSmartRouterOptions(options: SmartRouterValidationOptions): void {
+  const result = validateSmartRouterOptions(options);
+  if (!result.valid) {
+    throw new Error(`TokenFirewall Smart Router: ${result.errors.join("; ")}`);
+  }
+}
+
+function validateOptionalModel(
+  field: string,
+  value: string | undefined,
+  errors: string[]
+): void {
+  if (value !== undefined && !isNonEmptyString(value)) {
+    errors.push(`${field} must be a non-empty string when provided`);
+  }
+}
+
+function validateConfidenceThreshold(
+  field: string,
+  value: number | undefined,
+  errors: string[]
+): void {
+  if (value === undefined) {
+    return;
+  }
+
+  if (typeof value !== "number" || Number.isNaN(value) || value < 0 || value > 1) {
+    errors.push(`${field} must be a number between 0 and 1`);
+  }
+}
+
+function validateBoolean(field: string, value: boolean | undefined, errors: string[]): void {
+  if (value !== undefined && typeof value !== "boolean") {
+    errors.push(`${field} must be a boolean when provided`);
+  }
+}
+
+function validateCacheTtl(value: number | undefined, errors: string[]): void {
+  if (value === undefined) {
+    return;
+  }
+
+  if (typeof value !== "number" || Number.isNaN(value) || value <= 0) {
+    errors.push("detectionCacheTtlMs must be a positive number when provided");
+  }
+}
+
+function validateModelOverrides(
+  overrides: Record<string, string> | undefined,
+  errors: string[]
+): void {
+  if (overrides === undefined) {
+    return;
+  }
+
+  if (!isPlainObject(overrides)) {
+    errors.push("modelOverrides must be an object mapping task types to model names");
+    return;
+  }
+
+  for (const [taskType, model] of Object.entries(overrides)) {
+    if (!isNonEmptyString(taskType)) {
+      errors.push("modelOverrides cannot contain an empty task type");
+    }
+    if (!isNonEmptyString(model)) {
+      errors.push(`modelOverrides.${taskType} must be a non-empty model name`);
+    }
+  }
+}
+
+function validateTaskClassification(
+  taskClassification: Record<string, SmartRouterTaskConfig> | undefined,
+  errors: string[]
+): void {
+  if (taskClassification === undefined) {
+    return;
+  }
+
+  if (!isPlainObject(taskClassification)) {
+    errors.push("taskClassification must be an object keyed by task type");
+    return;
+  }
+
+  for (const [taskType, config] of Object.entries(taskClassification)) {
+    if (!isNonEmptyString(taskType)) {
+      errors.push("taskClassification cannot contain an empty task type");
+    }
+    validateTaskConfig(taskType, config, errors);
+  }
+}
+
+function validateTaskConfig(
+  taskType: string,
+  config: SmartRouterTaskConfig,
+  errors: string[]
+): void {
+  if (!isPlainObject(config)) {
+    errors.push(`taskClassification.${taskType} must be an object`);
+    return;
+  }
+
+  if (!isNonEmptyString(config.model)) {
+    errors.push(`taskClassification.${taskType}.model must be a non-empty string`);
+  }
+
+  validateConfidenceThreshold(
+    `taskClassification.${taskType}.confidenceThreshold`,
+    config.confidenceThreshold,
+    errors
+  );
+
+  if (config.keywords !== undefined && !isStringArray(config.keywords)) {
+    errors.push(`taskClassification.${taskType}.keywords must be an array of strings`);
+  }
+
+  if (config.patterns !== undefined && !isPatternArray(config.patterns)) {
+    errors.push(`taskClassification.${taskType}.patterns must contain only strings or RegExp values`);
+  }
+}
+
+function isPlainObject(value: unknown): value is Record<string, unknown> {
+  return Boolean(value) && typeof value === "object" && !Array.isArray(value);
+}
+
+function isNonEmptyString(value: unknown): value is string {
+  return typeof value === "string" && value.trim().length > 0;
+}
+
+function isStringArray(value: unknown): value is string[] {
+  return Array.isArray(value) && value.every(isNonEmptyString);
+}
+
+function isPatternArray(value: unknown): value is Array<string | RegExp> {
+  return Array.isArray(value) && value.every((pattern) =>
+    isNonEmptyString(pattern) || pattern instanceof RegExp
+  );
+}
diff --git a/tests/smart-router-validator.test.js b/tests/smart-router-validator.test.js
new file mode 100644
index 0000000..09c0b5a
--- /dev/null
+++ b/tests/smart-router-validator.test.js
@@ -0,0 +1,83 @@
+/**
+ * Smart router configuration validator tests.
+ *
+ * Run: node tests/smart-router-validator.test.js
+ */
+
+const {
+  assertValidSmartRouterOptions,
+  validateSmartRouterOptions,
+} = require("../dist/index.js");
+
+function assert(condition, message) {
+  if (!condition) {
+    throw new Error(message);
+  }
+}
+
+try {
+  const valid = validateSmartRouterOptions({
+    defaultModel: "gpt-4o-mini",
+    confidenceThreshold: 0.7,
+    cacheDetections: true,
+    detectionCacheTtlMs: 60_000,
+    enableAnalytics: false,
+    modelOverrides: {
+      code_generation: "claude-3-5-sonnet-20241022",
+    },
+    taskClassification: {
+      support_triage: {
+        keywords: ["support", "ticket"],
+        patterns: [/urgent/i, "escalate"],
+        model: "gpt-4o-mini",
+        confidenceThreshold: 0.55,
+      },
+    },
+  });
+
+  assert(valid.valid, "valid smart router config should pass");
+  assert(valid.errors.length === 0, "valid config should not return errors");
+
+  const invalid = validateSmartRouterOptions({
+    defaultModel: "",
+    confidenceThreshold: 1.2,
+    cacheDetections: "yes",
+    detectionCacheTtlMs: 0,
+    modelOverrides: {
+      code_generation: "",
+    },
+    taskClassification: {
+      "": {
+        keywords: ["ok"],
+        patterns: [42],
+        model: "",
+        confidenceThreshold: -0.1,
+      },
+    },
+  });
+
+  assert(!invalid.valid, "invalid smart router config should fail");
+  assert(invalid.errors.some((error) => error.includes("defaultModel")), "should flag defaultModel");
+  assert(invalid.errors.some((error) => error.includes("confidenceThreshold")), "should flag threshold");
+  assert(invalid.errors.some((error) => error.includes("cacheDetections")), "should flag boolean fields");
+  assert(invalid.errors.some((error) => error.includes("detectionCacheTtlMs")), "should flag cache TTL");
+  assert(invalid.errors.some((error) => error.includes("modelOverrides.code_generation")), "should flag model override values");
+  assert(invalid.errors.some((error) => error.includes("taskClassification cannot contain an empty task type")), "should flag empty task type");
+  assert(invalid.errors.some((error) => error.includes(".model")), "should flag task model");
+  assert(invalid.errors.some((error) => error.includes(".patterns")), "should flag invalid patterns");
+
+  let threw = false;
+  try {
+    assertValidSmartRouterOptions({
+      confidenceThreshold: Number.NaN,
+    });
+  } catch (error) {
+    threw = error.message.includes("TokenFirewall Smart Router:");
+  }
+  assert(threw, "assertValidSmartRouterOptions should throw a helpful error");
+
+  console.log("Smart router validator tests passed.");
+} catch (error) {
+  console.error("Smart router validator tests failed:", error.message);
+  process.exit(1);
+}