diff --git a/runner/orchestration/build-repair.ts b/runner/orchestration/build-repair.ts
index acfe55f..f5f7eeb 100644
--- a/runner/orchestration/build-repair.ts
+++ b/runner/orchestration/build-repair.ts
@@ -71,6 +71,7 @@ export async function repairAndBuild(
     rootPromptDef,
     directory,
     workerConcurrencyQueue,
+    abortSignal,
     attempts,
     progress
   );
@@ -89,6 +90,7 @@ async function handleRepairResponse(
   rootPromptDef: RootPromptDefinition,
   directory: string,
   workerConcurrencyQueue: PQueue,
+  abortSignal: AbortSignal,
   attempts: number,
   progress: ProgressLogger
 ) {
@@ -107,9 +109,15 @@ async function handleRepairResponse(
   mergeRepairFiles(repairResponse.outputFiles, finalOutputFiles);
   writeResponseFiles(directory, finalOutputFiles, env, rootPromptDef.name);
 
-  const buildResult = await workerConcurrencyQueue.add(
-    () => runBuild(evalID, gateway, directory, env, rootPromptDef, progress),
-    { throwOnTimeout: true }
+  const buildResult = await runBuild(
+    evalID,
+    gateway,
+    directory,
+    env,
+    rootPromptDef,
+    abortSignal,
+    workerConcurrencyQueue,
+    progress
   );
 
   return {
diff --git a/runner/orchestration/build-serve-loop.ts b/runner/orchestration/build-serve-loop.ts
index 0e9bebf..5df5e2e 100644
--- a/runner/orchestration/build-serve-loop.ts
+++ b/runner/orchestration/build-serve-loop.ts
@@ -5,9 +5,7 @@ import { Environment } from '../configuration/environment.js';
 import {
   AttemptDetails,
   LlmContextFile,
-  LlmResponseFile,
   RootPromptDefinition,
-  Usage,
 } from '../shared-interfaces.js';
 import { DEFAULT_MAX_REPAIR_ATTEMPTS } from '../configuration/constants.js';
 import { ProgressLogger } from '../progress/progress-logger.js';
@@ -59,9 +57,15 @@ export async function attemptBuild(
   const finalOutputFiles = initialResponse.files.map((file) => ({
     ...file,
   }));
-  const initialBuildResult = await workerConcurrencyQueue.add(
-    () => runBuild(evalID, gateway, directory, env, rootPromptDef, progress),
-    { throwOnTimeout: true }
+  const initialBuildResult = await runBuild(
+    evalID,
+    gateway,
+    directory,
+    env,
+    rootPromptDef,
+    abortSignal,
+    workerConcurrencyQueue,
+    progress
   );
   let repairAttempts = 0;
   const maxRepairAttempts = gateway.shouldRetryFailedBuilds(evalID)
@@ -122,6 +126,8 @@ export async function attemptBuild(
     directory,
     env,
     rootPromptDef,
+    workerConcurrencyQueue,
+    abortSignal,
     progress,
     skipScreenshots,
     skipAxeTesting,
@@ -176,6 +182,8 @@ export async function attemptBuild(
       directory,
       env,
       rootPromptDef,
+      workerConcurrencyQueue,
+      abortSignal,
       progress,
       skipScreenshots,
       skipAxeTesting,
diff --git a/runner/orchestration/build-worker.ts b/runner/orchestration/build-worker.ts
index 006659c..927f7ba 100644
--- a/runner/orchestration/build-worker.ts
+++ b/runner/orchestration/build-worker.ts
@@ -6,6 +6,7 @@ import { Environment } from '../configuration/environment.js';
 import { ProgressLogger } from '../progress/progress-logger.js';
 import { RootPromptDefinition } from '../shared-interfaces.js';
 import { EvalID, Gateway } from './gateway.js';
+import PQueue from 'p-queue';
 
 /** Attempts to build the code. */
 export async function runBuild(
@@ -14,6 +15,8 @@ export async function runBuild(
   appDirectoryPath: string,
   env: Environment,
   rootPromptDef: RootPromptDefinition,
+  abortSignal: AbortSignal,
+  workerConcurrencyQueue: PQueue,
   progress: ProgressLogger
 ): Promise<BuildResult> {
   progress.log(rootPromptDef, 'build', `Building the app`);
@@ -24,6 +27,8 @@ export async function runBuild(
       env,
       appDirectoryPath,
       rootPromptDef,
+      workerConcurrencyQueue,
+      abortSignal,
       progress
     );
     if (result.status === BuildResultStatus.SUCCESS) {
diff --git a/runner/orchestration/gateway.ts b/runner/orchestration/gateway.ts
index 6519310..da631c0 100644
--- a/runner/orchestration/gateway.ts
+++ b/runner/orchestration/gateway.ts
@@ -1,3 +1,4 @@
+import PQueue from 'p-queue';
 import { LlmGenerateFilesContext } from '../codegen/llm-runner.js';
 import { Environment } from '../configuration/environment.js';
 import { ProgressLogger } from '../progress/progress-logger.js';
@@ -41,6 +42,8 @@ export interface Gateway<Env extends Environment> {
     env: Env,
     appDirectoryPath: string,
     rootPromptDef: RootPromptDefinition,
+    workerConcurrencyQueue: PQueue,
+    abortSignal: AbortSignal,
     progress: ProgressLogger
   ): Promise<BuildResult>;
 
diff --git a/runner/orchestration/gateways/local_gateway.ts b/runner/orchestration/gateways/local_gateway.ts
index 1cb69fd..b39a0e3 100644
--- a/runner/orchestration/gateways/local_gateway.ts
+++ b/runner/orchestration/gateways/local_gateway.ts
@@ -21,6 +21,7 @@ import { killChildProcessGracefully } from '../../utils/kill-gracefully.js';
 import { ProgressLogger } from '../../progress/progress-logger.js';
 import { serveApp } from '../../workers/serve-testing/serve-app.js';
 import { LocalEnvironment } from '../../configuration/environment-local.js';
+import PQueue from 'p-queue';
 
 let uniqueIDs = 0;
 
@@ -70,6 +71,8 @@ export class LocalGateway implements Gateway<LocalEnvironment> {
     env: LocalEnvironment,
     appDirectoryPath: string,
     rootPromptDef: RootPromptDefinition,
+    workerConcurrencyQueue: PQueue,
+    abortSignal: AbortSignal,
     progress: ProgressLogger
   ): Promise<BuildResult> {
     const buildParams: BuildWorkerMessage = {
@@ -78,21 +81,29 @@ export class LocalGateway implements Gateway<LocalEnvironment> {
       buildCommand: env.buildCommand,
     };
 
-    return new Promise<BuildResult>((resolve, reject) => {
-      const child: ChildProcess = fork(
-        path.resolve(import.meta.dirname, '../../workers/builder/worker.js')
-      );
-      child.send(buildParams);
+    return workerConcurrencyQueue.add(
+      () =>
+        new Promise<BuildResult>((resolve, reject) => {
+          const child: ChildProcess = fork(
+            path.resolve(
+              import.meta.dirname,
+              '../../workers/builder/worker.js'
+            ),
+            { signal: abortSignal }
+          );
+          child.send(buildParams);
 
-      child.on('message', async (result: BuildWorkerResponseMessage) => {
-        await killChildProcessGracefully(child);
-        resolve(result.payload);
-      });
-      child.on('error', async (err) => {
-        await killChildProcessGracefully(child);
-        reject(err);
-      });
-    });
+          child.on('message', async (result: BuildWorkerResponseMessage) => {
+            await killChildProcessGracefully(child);
+            resolve(result.payload);
+          });
+          child.on('error', async (err) => {
+            await killChildProcessGracefully(child);
+            reject(err);
+          });
+        }),
+      { throwOnTimeout: true }
+    );
   }
 
   async serveBuild<T>(
diff --git a/runner/orchestration/serve-testing-worker.ts b/runner/orchestration/serve-testing-worker.ts
index 7a19f0f..ca5b369 100644
--- a/runner/orchestration/serve-testing-worker.ts
+++ b/runner/orchestration/serve-testing-worker.ts
@@ -11,6 +11,7 @@ import {
 } from '../workers/serve-testing/worker-types.js';
 import { EvalID, Gateway } from './gateway.js';
 import { BrowserAgentTaskInput } from '../testing/browser-agent/models.js';
+import PQueue from 'p-queue';
 
 /** Attempts to run & test an eval app. */
 export async function serveAndTestApp(
@@ -19,6 +20,8 @@ export async function serveAndTestApp(
   appDirectoryPath: string,
   env: Environment,
   rootPromptDef: RootPromptDefinition,
+  workerConcurrencyQueue: PQueue,
+  abortSignal: AbortSignal,
   progress: ProgressLogger,
   skipScreenshots: boolean,
   skipAxeTesting: boolean,
@@ -43,37 +46,41 @@ export async function serveAndTestApp(
         userJourneyAgentTaskInput,
       };
 
-      return await new Promise<ServeTestingResult>((resolve, reject) => {
-        const child: ChildProcess = fork(
-          path.resolve(
-            import.meta.dirname,
-            '../workers/serve-testing/worker.js'
-          )
-        );
-        child.send(serveParams);
+      return await workerConcurrencyQueue.add(
+        () =>
+          new Promise<ServeTestingResult>((resolve, reject) => {
+            const child: ChildProcess = fork(
+              path.resolve(
+                import.meta.dirname,
+                '../workers/serve-testing/worker.js'
+              ),
+              { signal: abortSignal }
+            );
+            child.send(serveParams);
 
-        child.on(
-          'message',
-          async (result: ServeTestingWorkerResponseMessage) => {
-            if (result.type === 'result') {
+            child.on(
+              'message',
+              async (result: ServeTestingWorkerResponseMessage) => {
+                if (result.type === 'result') {
+                  await killChildProcessGracefully(child);
+                  resolve(result.payload);
+                } else {
+                  progress.log(
+                    rootPromptDef,
+                    result.payload.state,
+                    result.payload.message,
+                    result.payload.details
+                  );
+                }
+              }
+            );
+            child.on('error', async (err) => {
               await killChildProcessGracefully(child);
-              resolve(result.payload);
-            } else {
-              progress.log(
-                rootPromptDef,
-                result.payload.state,
-                result.payload.message,
-                result.payload.details
-              );
-            }
-          }
-        );
-        child.on('error', async (err) => {
-          console.error('Caught error');
-          await killChildProcessGracefully(child);
-          reject(err);
-        });
-      });
+              reject(err);
+            });
+          }),
+        { throwOnTimeout: true }
+      );
     }
   );