diff --git a/README.md b/README.md
index 57253f1..9108ede 100644
--- a/README.md
+++ b/README.md
@@ -283,10 +283,21 @@ Creates and configures an intelligent model router.
 
 ```typescript
 interface ModelRouterOptions {
-  strategy: "fallback" | "context" | "cost";  // Routing strategy
+  strategy: "fallback" | "context" | "cost" | "smart";  // Routing strategy
+  smart?: SmartRouterOptions;                 // Smart routing options
   fallbackMap?: Record<string, string[]>;     // Fallback model map
   maxRetries?: number;                        // Max retry attempts (default: 1)
 }
+
+interface SmartRouterOptions {
+  defaultModel?: string;                      // Fallback when confidence is low
+  confidenceThreshold?: number;               // Minimum task confidence
+  modelOverrides?: Record<string, string>;    // Override task-to-model mapping
+  taskClassification?: Record<string, TaskClassificationConfig>;
+  cacheDetections?: boolean;                  // Cache repeated prompt detections
+  detectionCacheTtlMs?: number;               // Detection cache TTL in ms
+  enableAnalytics?: boolean;                  // Record task routing analytics
+}
 ```
 
 **Example:**
@@ -309,6 +320,21 @@ patchGlobalFetch();
 // API calls will automatically retry with fallback models on failure
 ```
 
+Smart routing type definitions are available for the upcoming task classifier:
+
+```typescript
+import type { SmartRouterOptions, TaskClassification } from "tokenfirewall";
+
+const smartOptions: SmartRouterOptions = {
+  defaultModel: "gpt-4o-mini",
+  confidenceThreshold: 0.75,
+  modelOverrides: {
+    code_generation: "claude-3-5-sonnet-20241022",
+    math_reasoning: "o1-mini"
+  }
+};
+```
+
 ### Routing Strategies
 
 **1. Fallback Strategy** - Uses predefined fallback map
diff --git a/src/index.ts b/src/index.ts
index c769e99..4b8e743 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -249,7 +249,14 @@ export type {
   FailureContext,
   RoutingDecision,
   RouterEvent,
-  ApiKeyConfig
+  ApiKeyConfig,
+  BuiltInTaskType,
+  TaskType,
+  TaskDetectionMethod,
+  TaskModelPreference,
+  TaskClassificationConfig,
+  TaskClassification,
+  SmartRouterOptions
 } from "./router/types";
 
 /**
diff --git a/src/router/types.ts b/src/router/types.ts
index 8e333f4..7fdebc3 100644
--- a/src/router/types.ts
+++ b/src/router/types.ts
@@ -5,7 +5,114 @@
 /**
  * Routing strategy types
  */
-export type RoutingStrategy = "fallback" | "context" | "cost";
+export type RoutingStrategy = "fallback" | "context" | "cost" | "smart";
+
+/**
+ * Built-in smart routing task types documented for model selection.
+ */
+export type BuiltInTaskType =
+  | "code_generation"
+  | "code_review"
+  | "math_reasoning"
+  | "complex_reasoning"
+  | "document_analysis"
+  | "creative_writing"
+  | "translation"
+  | "simple_chat"
+  | "data_extraction"
+  | "chinese_language"
+  | "factual_qa"
+  | "technical_documentation";
+
+/**
+ * Task type accepted by the smart router. String intersections preserve
+ * autocomplete for built-ins while allowing user-defined task names.
+ */
+export type TaskType = BuiltInTaskType | (string & {});
+
+/**
+ * Detection method that produced a smart routing classification.
+ */
+export type TaskDetectionMethod =
+  | "keyword"
+  | "pattern"
+  | "language"
+  | "context"
+  | "manual"
+  | "custom";
+
+/**
+ * Model preference for a task type.
+ */
+export interface TaskModelPreference {
+  /** Primary model recommended for this task */
+  model: string;
+  /** Optional provider name when the model can be ambiguous */
+  provider?: string;
+  /** Optional priority for tie-breaking; higher wins */
+  priority?: number;
+  /** Optional reason shown in analytics/debug output */
+  reason?: string;
+}
+
+/**
+ * Custom task definition used by the smart router.
+ */
+export interface TaskClassificationConfig {
+  /** Keywords that indicate this task */
+  keywords?: string[];
+  /** String or RegExp patterns that indicate this task */
+  patterns?: Array<string | RegExp>;
+  /** Preferred model for this task */
+  model: string;
+  /** Optional fallback models for this task */
+  alternatives?: TaskModelPreference[];
+  /** Minimum confidence required before selecting this task */
+  confidenceThreshold?: number;
+}
+
+/**
+ * Result produced by task classification.
+ */
+export interface TaskClassification {
+  /** Detected task type */
+  taskType: TaskType;
+  /** Confidence from 0 to 1 */
+  confidence: number;
+  /** Selected model for the request */
+  selectedModel: string;
+  /** Human-readable reason for the classification */
+  reason: string;
+  /** Detection method that produced the classification */
+  method?: TaskDetectionMethod;
+  /** Alternative model candidates */
+  alternatives?: TaskModelPreference[];
+}
+
+/**
+ * Options for the smart routing strategy.
+ */
+export interface SmartRouterOptions {
+  /** Default model used when confidence is below the threshold */
+  defaultModel?: string;
+  /** Minimum confidence required to use a classified task route */
+  confidenceThreshold?: number;
+  /** Per-task model overrides */
+  modelOverrides?: Partial<Record<BuiltInTaskType, string>> & Record<string, string>;
+  /** Custom task definitions keyed by task type */
+  taskClassification?: Record<string, TaskClassificationConfig>;
+  /** Cache task detections for repeated prompts (default: true for implementations) */
+  cacheDetections?: boolean;
+  /** Detection cache TTL in milliseconds */
+  detectionCacheTtlMs?: number;
+  /** Enable task analytics collection */
+  enableAnalytics?: boolean;
+  /** Optional custom async detector invoked before built-in detection */
+  customDetector?: (
+    prompt: string,
+    context?: Record<string, unknown>
+  ) => Promise<TaskClassification | null> | TaskClassification | null;
+}
 
 /**
  * Failure types detected by error detector
@@ -35,6 +142,8 @@ export interface ApiKeyConfig {
 export interface ModelRouterOptions {
   /** Routing strategy to use */
   strategy: RoutingStrategy;
+  /** Smart routing options used when strategy is "smart" */
+  smart?: SmartRouterOptions;
   /** Map of primary models to fallback models */
   fallbackMap?: Record<string, string[]>;
   /** Maximum number of retry attempts (default: 1) */
diff --git a/tests/router-types.test.js b/tests/router-types.test.js
new file mode 100644
index 0000000..af33c01
--- /dev/null
+++ b/tests/router-types.test.js
@@ -0,0 +1,48 @@
+/**
+ * Router type definition smoke tests.
+ *
+ * Run: node tests/router-types.test.js
+ */
+
+const { createModelRouter, disableModelRouter } = require("../dist/index.js");
+
+function assert(condition, message) {
+  if (!condition) {
+    throw new Error(message);
+  }
+}
+
+try {
+  const smartRouter = createModelRouter({
+    strategy: "smart",
+    smart: {
+      defaultModel: "gpt-4o-mini",
+      confidenceThreshold: 0.75,
+      modelOverrides: {
+        code_generation: "claude-3-5-sonnet-20241022",
+        math_reasoning: "o1-mini",
+      },
+      cacheDetections: true,
+      enableAnalytics: true,
+    },
+  });
+
+  assert(smartRouter.getStrategy() === "smart", "smart strategy should be accepted");
+  disableModelRouter();
+
+  const fallbackRouter = createModelRouter({
+    strategy: "fallback",
+    fallbackMap: {
+      "gpt-4o": ["gpt-4o-mini"],
+    },
+  });
+
+  assert(fallbackRouter.getStrategy() === "fallback", "existing strategies should still work");
+  disableModelRouter();
+
+  console.log("Router type definition smoke tests passed.");
+} catch (error) {
+  disableModelRouter();
+  console.error("Router type definition smoke tests failed:", error.message);
+  process.exit(1);
+}