ci: capture healthy launching.prefs mid-session for baseline

Author: pzalutski-pixel

.github/workflows/repro-issue18.yml

@@ -70,6 +70,14 @@ jobs:
         {"jsonrpc":"2.0","id":4,"method":"tools/call","params":{"name":"get_diagnostics","arguments":{"filePath":"/tmp/proj/child_project/src/main/java/com/playground/ConfigReader.java"}}}'
 
         echo "=== launching product (java.home = SDKMAN Corretto) ==="
+        # Capture the launching prefs mid-session (before the launcher's shutdown hook
+        # cleans the workspace) so we can compare a healthy prefs file against the reporter's.
+        ( for i in $(seq 1 120); do
+            find /tmp/ws -name "org.eclipse.jdt.launching.prefs" -exec cp {} /tmp/healthy.prefs \; 2>/dev/null
+            sleep 0.5
+          done ) &
+        CAP_PID=$!
+
         # GitHub Actions sets CI=true, which suppresses JDT's DetectVMInstallationsJob.
         # The reporter's machine has no CI var, so that async VM-detection/reconciliation job
         # DOES run. Force it on (property=false bypasses the CI check) to match his environment.
@@ -87,14 +95,9 @@ jobs:
         echo "=== stdout (MCP responses) ==="
         echo "$OUT"
 
-        echo "=== workspace survival + prefs baseline (healthy run) ==="
-        echo "--- contents of /tmp/ws after exit ---"
-        ls -la /tmp/ws 2>/dev/null || echo "(no /tmp/ws)"
-        echo "--- any launching prefs files found ---"
-        find /tmp/ws -name "org.eclipse.jdt.launching.prefs" 2>/dev/null | while read -r f; do
-          echo ">>> $f"; cat "$f"; echo
-        done
-        find /tmp/ws -path "*org.eclipse.jdt.launching*" 2>/dev/null | head -20
+        kill "$CAP_PID" 2>/dev/null || true
+        echo "=== healthy launching.prefs captured mid-session ==="
+        if [ -f /tmp/healthy.prefs ]; then cat /tmp/healthy.prefs; echo; else echo "(prefs never appeared on disk during the session)"; fi
 
         echo "=== verdict ==="
         if echo "$OUT" | grep -q 'java.lang.Object cannot be resolved'; then