diff --git a/lib/strategies/base.js b/lib/strategies/base.js
new file mode 100644
index 0000000..a974915
--- /dev/null
+++ b/lib/strategies/base.js
@@ -0,0 +1,39 @@
+/**
+ * Base strategy class. All strategies extend this.
+ * 
+ * Strategies receive market state updates and emit trade signals.
+ * Signals are { side: 'yes'|'no', price: number, size: number, reason: string }
+ */
+export class BaseStrategy {
+  constructor(name, config = {}) {
+    this.name = name;
+    this.config = config;
+    this.enabled = true;
+    this.mode = 'paper'; // 'paper' | 'live'
+  }
+
+  /**
+   * Called on every market state update.
+   * Return a signal object or null.
+   */
+  evaluate(marketState) {
+    throw new Error(`${this.name}: evaluate() not implemented`);
+  }
+
+  /**
+   * Called when a market settles. Useful for strategies that
+   * need to know outcomes (like Martingale).
+   */
+  onSettlement(result, tradeHistory) {
+    // Override in subclass if needed
+  }
+
+  toJSON() {
+    return {
+      name: this.name,
+      enabled: this.enabled,
+      mode: this.mode,
+      config: this.config
+    };
+  }
+}