Add e2e test for async function compilation (issue #123) (#238)

Fixes #123

### Summary
Adds an e2e test to reproduce the async function compilation hang reported in issue #123. However, **the issue cannot be reproduced** in the current codebase - compilation with async function handlers co
mpletes successfully.

### Issue Description
@cpursley reported that compilation would hang when using async functions in flow step handlers. After removing the `async` keywords, compilation worked. The problematic pattern was:

```typescript
.step(
  { slug: 'process_company_logo' },
  async (input) => await processCompanyLogoTask({ ... })
)
```

### Changes Made
- **Test Flow**: Added `pkgs/cli/examples/async-function-hang.ts` - reproduces the exact pattern from the issue with dummy async tasks
- **E2E Test Script**: Added `pkgs/cli/scripts/test-async-hang-issue-123` - automated test with 30s timeout to detect hangs
- **Nx Target**: Added `test:e2e:async-hang-issue-123` to `pkgs/cli/project.json`

### Test Results
The test passes successfully, indicating:
1. Async functions in handlers compile without hanging
2. The compilation completes in under 30 seconds
3. Migration files are generated correctly

### Possible Explanations
The issue may have been:
- Fixed by other changes in the codebase
- Specific to the user's environment or the actual task imports used
- Related to network issues when Deno was fetching dependencies

The test now provides regression protection if this issue resurfaces.

Author: jumski

pkgs/cli/examples/async-function-hang.ts

@@ -0,0 +1,48 @@
+import { Flow } from '@pgflow/dsl';
+
+type Input = {
+  logo_url: string;
+  company_slug: string;
+  company_id: string;
+};
+
+// Dummy async task that simulates real async work
+async function processCompanyLogoTask(input: { logo_url: string; company_slug: string }) {
+  // Simulate some async work with a promise
+  await new Promise((resolve) => setTimeout(resolve, 100));
+  return {
+    file_path: `/uploads/${input.company_slug}/logo.png`,
+  };
+}
+
+// Another dummy async task
+async function updateCompanyLogoUrlTask(input: { company_id: string; file_path: string }) {
+  // Simulate some async work
+  await new Promise((resolve) => setTimeout(resolve, 50));
+  return {
+    success: true,
+    company_id: input.company_id,
+    logo_url: input.file_path,
+  };
+}
+
+export default new Flow<Input>({
+  slug: 'upload_company_logo',
+  maxAttempts: 3,
+  timeout: 60,
+  baseDelay: 2,
+})
+  .step(
+    { slug: 'process_company_logo' },
+    async (input) => await processCompanyLogoTask({
+      logo_url: input.run.logo_url,
+      company_slug: input.run.company_slug,
+    })
+  )
+  .step(
+    { slug: 'update_company_logo_url', dependsOn: ['process_company_logo'] },
+    async (input) => await updateCompanyLogoUrlTask({
+      company_id: input.run.company_id,
+      file_path: (input.process_company_logo as { file_path: string }).file_path,
+    })
+  );

pkgs/cli/project.json

@@ -37,7 +37,8 @@
         "test:vitest",
         "test:e2e:install",
         "test:e2e:install:duplicates",
-        "test:e2e:compile"
+        "test:e2e:compile",
+        "test:e2e:async-hang-issue-123"
       ],
       "options": {
         "parallel": false
@@ -77,6 +78,15 @@
         "cwd": "{projectRoot}",
         "parallel": false
       }
+    },
+    "test:e2e:async-hang-issue-123": {
+      "executor": "nx:run-commands",
+      "local": true,
+      "dependsOn": ["build"],
+      "options": {
+        "command": "./scripts/test-async-hang-issue-123",
+        "cwd": "{projectRoot}"
+      }
     }
   }
 }

pkgs/cli/scripts/test-async-hang-issue-123

@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+set -e
+
+# Script to test if pgflow CLI compile hangs on flows with async functions
+# This reproduces issue #123: https://github.com/pgflow-dev/pgflow/issues/123
+#
+# Issue: Compilation hangs on flow with async functions
+# Reporter: @cpursley
+# Description: Running compile on a flow with async function handlers was hanging.
+#              After commenting out the async keywords, compilation worked.
+
+cd "$(dirname "$0")/.."
+ROOT_DIR=$(pwd)
+
+echo "🧪 Testing async function compilation"
+echo "   Issue #123: https://github.com/pgflow-dev/pgflow/issues/123"
+echo ""
+
+# Clean up any existing output
+echo "🧹 Cleaning up old test directory"
+rm -rf supabase/
+
+# Initialize a fresh Supabase project
+echo "🏗️ Creating new Supabase project"
+npx -y supabase@latest init --force --with-vscode-settings --with-intellij-settings
+
+# Install pgflow with our CLI
+echo "📦 Installing pgflow with CLI"
+node dist/index.js install --supabase-path supabase/ --yes
+
+# Try to compile the flow with async functions
+echo "🔧 Compiling flow with async functions"
+timeout 30s node dist/index.js compile examples/async-function-hang.ts --deno-json examples/deno.json --supabase-path supabase || {
+  EXIT_CODE=$?
+  if [ $EXIT_CODE -eq 124 ]; then
+    echo "❌ FAILURE: Compilation hung and was killed by timeout (30s)"
+    echo "This confirms issue #123 - compilation hangs on flows with async functions"
+    exit 1
+  else
+    echo "❌ FAILURE: Compilation failed with exit code $EXIT_CODE"
+    exit $EXIT_CODE
+  fi
+}
+
+# Verify compilation succeeded
+echo "✅ Verifying flow compilation"
+if ! grep -q "create_flow.*upload_company_logo" supabase/migrations/*.sql; then
+  echo "❌ FAILURE: No migration found with create_flow for 'upload_company_logo'"
+  exit 1
+fi
+
+# Show success message
+echo ""
+echo "✨ Async function compilation test complete!"
+echo "   Issue #123 appears to be fixed or not reproducible in this environment."
+echo "   See: https://github.com/pgflow-dev/pgflow/issues/123"