Fix ext build: separate dirs per Ruby variant, -I for loading

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: samuel-williams-shopify

.github/workflows/test-ruby-gc-bug.yaml

@@ -93,48 +93,25 @@ jobs:
         path: /tmp/*.asm
 
     # ── Build io-event extension and run tests ─────────────────────────────
-    - name: Build io-event extension (FIXED Ruby)
+    - name: Build + test all variants
       run: |
-        export PATH=$HOME/.rubies/ruby-fixed/bin:$PATH
-        gem install sus --no-document
-        ruby ext/io/event/extconf.rb
-        make -C ext/io/event
-
-    - name: Run worker_pool test with FIXED Ruby
-      id: test_fixed
-      run: |
-        export PATH=$HOME/.rubies/ruby-fixed/bin:$PATH
-        ruby -I lib -rsus test/io/event/worker_pool.rb 2>&1 | tail -5
-        echo "exit:$?"
-      continue-on-error: true
-
-    - name: Build io-event extension (BUGGY Ruby)
-      run: |
-        export PATH=$HOME/.rubies/ruby-buggy/bin:$PATH
-        gem install sus --no-document
-        ruby ext/io/event/extconf.rb
-        make -C ext/io/event
-
-    - name: Run worker_pool test with BUGGY Ruby (expect crash)
-      id: test_buggy
-      run: |
-        export PATH=$HOME/.rubies/ruby-buggy/bin:$PATH
-        (ruby -I lib -rsus test/io/event/worker_pool.rb 2>&1 | tail -5; echo "exit:$?") || true
-      continue-on-error: true
-
-    - name: Build io-event extension (CASE_C Ruby)
-      run: |
-        export PATH=$HOME/.rubies/ruby-caseC/bin:$PATH
-        gem install sus --no-document
-        ruby ext/io/event/extconf.rb
-        make -C ext/io/event
-
-    - name: Run worker_pool test with CASE_C Ruby (does O0 fix the crash?)
-      id: test_caseC
-      run: |
-        export PATH=$HOME/.rubies/ruby-caseC/bin:$PATH
-        (ruby -I lib -rsus test/io/event/worker_pool.rb 2>&1 | tail -5; echo "exit:$?") || true
-      continue-on-error: true
+        for variant in fixed buggy caseC; do
+          echo "=== Building io-event for ruby-${variant} ==="
+          export PATH=$HOME/.rubies/ruby-${variant}/bin:$PATH
+          gem install sus --no-document -q
+
+          mkdir -p /tmp/ext-${variant}
+          cp -r ext/* /tmp/ext-${variant}/
+          cd /tmp/ext-${variant}
+          ruby $GITHUB_WORKSPACE/ext/extconf.rb
+          make -j$(nproc) 2>&1 | tail -3
+          cd $GITHUB_WORKSPACE
+
+          echo "=== Running worker_pool test with ruby-${variant} ==="
+          (timeout 60 ruby -I lib -I /tmp/ext-${variant} -rsus \
+            test/io/event/worker_pool.rb 2>&1 | tail -10; echo "exit_${variant}:$?") || true
+          echo "--- end ${variant} ---"
+        done
 
     - name: Summary
       if: always()