diff --git a/.projenrc.ts b/.projenrc.ts
index f8973c50..123366b6 100644
--- a/.projenrc.ts
+++ b/.projenrc.ts
@@ -324,7 +324,15 @@ const backEndApp = new awscdk.AwsCdkTypeScriptApp({
   eslint: true,
   jest: true,
   jestOptions: {
+    // Recycle a worker once it exceeds this heap so accumulated memory (v8 coverage +
+    // CDK synth) is freed between suites rather than growing for the worker's lifetime.
+    extraCliOptions: ['--workerIdleMemoryLimit=2GB'],
     jestConfig: {
+      // Cap parallelism. The test/infra/** suites each synthesize full CDK stacks and use
+      // ~1.4GB heap apiece; at the default (cpuCount-1) worker count their aggregate RSS,
+      // plus v8 coverage, exceeds the 16GB CI runner and the OS OOM-kills the run (exit 1
+      // with no Jest summary). Limiting workers keeps peak memory well under the runner.
+      maxWorkers: '50%',
       // Ensure Jest can resolve tsconfig path aliases used by lambda handlers/tests.
       moduleNameMapper: {
         '^@BE/(.*)$': '<rootDir>/src/app/$1',
diff --git a/packages/back-end/.projen/tasks.json b/packages/back-end/.projen/tasks.json
index 5d4a1a36..58b437f0 100644
--- a/packages/back-end/.projen/tasks.json
+++ b/packages/back-end/.projen/tasks.json
@@ -140,7 +140,7 @@
       "description": "Run tests",
       "steps": [
         {
-          "exec": "jest --passWithNoTests --updateSnapshot",
+          "exec": "jest --workerIdleMemoryLimit=2GB --passWithNoTests --updateSnapshot",
           "receiveArgs": true
         },
         {
diff --git a/packages/back-end/package.json b/packages/back-end/package.json
index 7622285b..824538a1 100644
--- a/packages/back-end/package.json
+++ b/packages/back-end/package.json
@@ -109,6 +109,7 @@
   "version": "0.0.0",
   "jest": {
     "coverageProvider": "v8",
+    "maxWorkers": "50%",
     "moduleNameMapper": {
       "^@BE/(.*)$": "<rootDir>/src/app/$1",
       "^@SharedLib/(.*)$": "<rootDir>/../shared-lib/src/app/$1",