feat: integrate lerna cache

TICKET: WP-6096

Author: zahin-mohammad

.gitignore

@@ -18,3 +18,6 @@ modules/**/pack-scoped/
 coverage
 /.direnv/
 .claude/
+.nx/
+CLAUDE.sessions.md
+sessions/

CLAUDE.md

@@ -54,6 +54,45 @@ yarn integration-test
 yarn coverage
 ```
 
+### Test Caching
+BitGoJS uses Lerna + Nx for local test caching to speed up development:
+
+```bash
+# Tests are automatically cached when you run them
+yarn unit-test
+
+# Cache status is shown in output:
+# - Fresh run: Tests execute normally
+# - Cache hit: "[existing outputs match the cache, left as is]"
+
+# Clear cache if needed
+rm -rf .nx/cache
+
+# Cache works with all test commands
+yarn unit-test --scope @bitgo/sdk-core  # Caches per package
+yarn unit-test-changed                   # Caches changed packages
+```
+
+The cache automatically invalidates when:
+- Source files change
+- Test files change
+- Dependencies change
+- Configuration files change (tsconfig.json, .mocharc.*, package.json)
+
+**Note for CI**: Nx caching requires proper dependency management. Tests depend on build outputs, so ensure packages are built before running tests. The `yarn postinstall` step must run even when node_modules are cached.
+
+If you encounter TypeScript module resolution errors in CI, you can disable Nx caching by:
+```bash
+# Option 1: Use --skip-nx-cache flag
+yarn unit-test --skip-nx-cache
+
+# Option 2: Set environment variable
+NX_SKIP_NX_CACHE=true yarn unit-test
+
+# Option 3: Temporarily disable in lerna.json
+# Set "useNx": false
+```
+
 ### Browser Compatibility
 ```bash
 # Run browser tests
@@ -121,3 +160,7 @@ This will generate the necessary boilerplate for a new coin implementation.
 ## Node.js Version Support
 
 BitGoJS supports Node.js versions >=20 and <23, with NPM >=3.10.10.
+
+## Sessions System Behaviors
+
+@CLAUDE.sessions.md

lerna.json

@@ -7,5 +7,5 @@
     }
   },
   "$schema": "node_modules/lerna/schemas/lerna-schema.json",
-  "useNx": false
+  "useNx": true
 }

nx.json

@@ -0,0 +1,86 @@
+{
+  "$schema": "./node_modules/nx/schemas/nx-schema.json",
+  "tasksRunnerOptions": {
+    "default": {
+      "runner": "nx/tasks-runners/default",
+      "options": {
+        "cacheableOperations": ["build", "unit-test", "integration-test"],
+        "cacheDirectory": ".nx/cache",
+        "parallel": 3,
+        "skipNxCache": false
+      }
+    }
+  },
+  "targetDefaults": {
+    "build": {
+      "cache": true,
+      "dependsOn": ["^build"],
+      "inputs": [
+        "production",
+        "{projectRoot}/**/*.json",
+        "{projectRoot}/tsconfig.json",
+        "{projectRoot}/package.json",
+        "{workspaceRoot}/tsconfig.json",
+        "{workspaceRoot}/tsconfig.packages.json"
+      ],
+      "outputs": [
+        "{projectRoot}/dist"
+      ]
+    },
+    "unit-test": {
+      "cache": true,
+      "dependsOn": ["build"],
+      "inputs": [
+        "default",
+        "{projectRoot}/**/*.ts",
+        "{projectRoot}/**/*.js",
+        "{projectRoot}/**/*.json",
+        "{projectRoot}/.mocharc.*",
+        "{projectRoot}/tsconfig.json",
+        "{projectRoot}/package.json",
+        "{workspaceRoot}/tsconfig.json"
+      ],
+      "outputs": [
+        "{projectRoot}/.nyc_output",
+        "{projectRoot}/coverage"
+      ]
+    },
+    "integration-test": {
+      "cache": true,
+      "dependsOn": ["build"],
+      "inputs": [
+        "default",
+        "{projectRoot}/**/*.ts",
+        "{projectRoot}/**/*.js",
+        "{projectRoot}/**/*.json",
+        "{projectRoot}/.mocharc.*",
+        "{projectRoot}/tsconfig.json",
+        "{projectRoot}/package.json",
+        "{workspaceRoot}/tsconfig.json"
+      ],
+      "outputs": [
+        "{projectRoot}/.nyc_output",
+        "{projectRoot}/coverage"
+      ]
+    }
+  },
+  "namedInputs": {
+    "default": [
+      "{projectRoot}/**/*",
+      "!{projectRoot}/**/*.md",
+      "!{projectRoot}/**/*.spec.ts",
+      "!{projectRoot}/**/*.spec.js",
+      "!{projectRoot}/**/test/**",
+      "!{projectRoot}/.nyc_output/**",
+      "!{projectRoot}/coverage/**",
+      "!{projectRoot}/dist/**",
+      "!{projectRoot}/lib/**",
+      "!{projectRoot}/node_modules/**"
+    ],
+    "production": [
+      "default",
+      "!{projectRoot}/**/*.spec.ts",
+      "!{projectRoot}/**/test/**"
+    ]
+  }
+}