diff --git a/package.json b/package.json
index a7c1702..efaf633 100644
--- a/package.json
+++ b/package.json
@@ -5,7 +5,7 @@
   "scripts": {
     "build": "rescript build",
     "clean": "rescript clean",
-    "test": "node --test tests/bridge_test.mjs",
+    "test": "node --test tests/*.mjs",
     "check": "npm run build && npm run test"
   },
   "devDependencies": {
diff --git a/tests/bridge_contract_test.mjs b/tests/bridge_contract_test.mjs
new file mode 100644
index 0000000..e94031e
--- /dev/null
+++ b/tests/bridge_contract_test.mjs
@@ -0,0 +1,208 @@
+// SPDX-License-Identifier: MIT OR AGPL-3.0-or-later
+// SPDX-FileCopyrightText: 2024 Hyperpolymath
+
+/**
+ * Bridge Contract Tests
+ *
+ * These tests verify behavioral invariants and algebraic properties
+ * of the Bridge module, ensuring the API contracts are upheld.
+ */
+
+import { test, describe } from "node:test";
+import { strictEqual, deepStrictEqual, ok } from "node:assert";
+import {
+  transform,
+  transformSafe,
+  compose,
+  identity,
+  uppercase,
+  prefix,
+  suffix,
+  info,
+} from "../lib/es6/src/Bridge.mjs";
+
+describe("Bridge Contracts", () => {
+
+  describe("identity laws", () => {
+    test("identity returns input unchanged for any string", () => {
+      const testCases = ["", "hello", "  spaces  ", "123", "émoji 🎉", "\n\t"];
+      for (const input of testCases) {
+        strictEqual(identity(input), input, `identity(${JSON.stringify(input)}) should equal input`);
+      }
+    });
+
+    test("identity ∘ identity = identity (idempotent)", () => {
+      const input = "test";
+      strictEqual(identity(identity(input)), identity(input));
+    });
+  });
+
+  describe("composition laws", () => {
+    test("compose(f, identity) = f (right identity)", () => {
+      const f = prefix("pre-");
+      const composed = compose(f, identity);
+      const input = "test";
+      strictEqual(composed(input), f(input));
+    });
+
+    test("compose(identity, f) = f (left identity)", () => {
+      const f = suffix("-suf");
+      const composed = compose(identity, f);
+      const input = "test";
+      strictEqual(composed(input), f(input));
+    });
+
+    test("compose(f, compose(g, h)) = compose(compose(f, g), h) (associativity)", () => {
+      const f = prefix("a-");
+      const g = suffix("-b");
+      const h = uppercase;
+      const input = "x";
+
+      const leftAssoc = compose(f, compose(g, h));
+      const rightAssoc = compose(compose(f, g), h);
+
+      strictEqual(leftAssoc(input), rightAssoc(input));
+    });
+  });
+
+  describe("transform contracts", () => {
+    test("transform always prepends [bridge] prefix", () => {
+      const inputs = ["", "a", "hello world", "123"];
+      for (const input of inputs) {
+        ok(transform(input).startsWith("[bridge] "),
+           `transform(${JSON.stringify(input)}) should start with [bridge] `);
+      }
+    });
+
+    test("transform preserves input after prefix", () => {
+      const input = "original";
+      strictEqual(transform(input), "[bridge] " + input);
+    });
+
+    test("transform output length = input length + 9", () => {
+      const inputs = ["", "a", "hello"];
+      for (const input of inputs) {
+        strictEqual(transform(input).length, input.length + 9,
+          `transform adds exactly 9 characters ([bridge] )`);
+      }
+    });
+  });
+
+  describe("transformSafe contracts", () => {
+    test("transformSafe returns Error variant for empty string only", () => {
+      const result = transformSafe("");
+      strictEqual(result.TAG, "Error");
+    });
+
+    test("transformSafe returns Ok variant for non-empty strings", () => {
+      const inputs = [" ", "a", "test", "\n"];
+      for (const input of inputs) {
+        const result = transformSafe(input);
+        strictEqual(result.TAG, "Ok",
+          `transformSafe(${JSON.stringify(input)}) should return Ok`);
+      }
+    });
+
+    test("transformSafe Ok value equals transform output", () => {
+      const input = "test";
+      const result = transformSafe(input);
+      strictEqual(result._0, transform(input));
+    });
+
+    test("transformSafe result is exhaustive (Ok or Error)", () => {
+      const inputs = ["", "a", "test"];
+      for (const input of inputs) {
+        const result = transformSafe(input);
+        ok(result.TAG === "Ok" || result.TAG === "Error",
+          "Result must be Ok or Error");
+      }
+    });
+  });
+
+  describe("prefix/suffix factory contracts", () => {
+    test("prefix factory returns a function", () => {
+      strictEqual(typeof prefix("x"), "function");
+    });
+
+    test("suffix factory returns a function", () => {
+      strictEqual(typeof suffix("x"), "function");
+    });
+
+    test("prefix(a)(prefix(b)(x)) = prefix(a + b)(x) (prefix composition)", () => {
+      const input = "test";
+      const a = "first-";
+      const b = "second-";
+      strictEqual(prefix(a)(prefix(b)(input)), a + b + input);
+    });
+
+    test("suffix(a)(suffix(b)(x)) has both suffixes", () => {
+      const input = "test";
+      const result = suffix("-a")(suffix("-b")(input));
+      strictEqual(result, "test-b-a");
+    });
+
+    test("prefix with empty string is identity-like", () => {
+      const input = "test";
+      strictEqual(prefix("")(input), input);
+    });
+
+    test("suffix with empty string is identity-like", () => {
+      const input = "test";
+      strictEqual(suffix("")(input), input);
+    });
+  });
+
+  describe("uppercase contracts", () => {
+    test("uppercase is idempotent: uppercase(uppercase(x)) = uppercase(x)", () => {
+      const inputs = ["hello", "HELLO", "HeLLo", "123", ""];
+      for (const input of inputs) {
+        strictEqual(uppercase(uppercase(input)), uppercase(input),
+          `uppercase should be idempotent for ${JSON.stringify(input)}`);
+      }
+    });
+
+    test("uppercase preserves length", () => {
+      const inputs = ["hello", "test", "abc123"];
+      for (const input of inputs) {
+        strictEqual(uppercase(input).length, input.length);
+      }
+    });
+
+    test("uppercase of empty string is empty string", () => {
+      strictEqual(uppercase(""), "");
+    });
+  });
+
+  describe("info contracts", () => {
+    test("info output contains config name", () => {
+      const config = { name: "mybridge", version: "1.0.0" };
+      ok(info(config).includes(config.name));
+    });
+
+    test("info output contains config version", () => {
+      const config = { name: "mybridge", version: "2.5.3" };
+      ok(info(config).includes(config.version));
+    });
+
+    test("info format is 'name vversion'", () => {
+      const config = { name: "test", version: "1.0.0" };
+      strictEqual(info(config), "test v1.0.0");
+    });
+  });
+
+  describe("type preservation contracts", () => {
+    test("all transform functions return strings", () => {
+      const fns = [
+        () => transform("x"),
+        () => identity("x"),
+        () => uppercase("x"),
+        () => prefix("a")("x"),
+        () => suffix("b")("x"),
+        () => compose(identity, identity)("x"),
+      ];
+      for (const fn of fns) {
+        strictEqual(typeof fn(), "string", "Function should return string");
+      }
+    });
+  });
+});