feat: add Python and Java regex engines

src/components/MinimizePanel.tsx

@@ -211,6 +211,8 @@ export function MinimizePanel({
     () => optionsFor(activeFlavour, activeOptions, "pcre2"),
     [activeFlavour, activeOptions],
   );
+  const activeEngineSupported =
+    activeFlavour === "ecmascript" || activeFlavour === "pcre2";
 
   const unitExpectation = (): RegexTestExpectation => {
     switch (unitKind) {
@@ -244,10 +246,14 @@ export function MinimizePanel({
   const activeSide = {
     flavour:
       activeFlavour === "pcre2" ? ("pcre2" as const) : ("ecmascript" as const),
-    flavourVersion: activeFlavourVersion,
+    flavourVersion: activeEngineSupported
+      ? activeFlavourVersion
+      : ECMASCRIPT.defaultVersion,
     pattern: initialPattern,
-    flags: activeFlags,
-    options: activeOptions,
+    flags: activeEngineSupported ? activeFlags : ECMASCRIPT.defaultFlags,
+    options: activeEngineSupported
+      ? activeOptions
+      : defaultRegexOptions(ECMASCRIPT),
     ...(unitKind === "replacement" ? { replacement: initialReplacement } : {}),
   };
 
@@ -324,6 +330,12 @@ export function MinimizePanel({
   };
 
   const run = async () => {
+    if (mode !== "comparison-mismatch" && !activeEngineSupported) {
+      setStatus(
+        `Subject minimization is not yet implemented for ${activeFlavour}; select ECMAScript or PCRE2, or use the explicit ECMAScript ↔ PCRE2 comparison target.`,
+      );
+      return;
+    }
     const currentRevision = ++revision.current;
     setRunning(true);
     setResult(undefined);
@@ -384,6 +396,13 @@ export function MinimizePanel({
           replacement. It does not claim a globally or semantically minimal
           example.
         </p>
+        {!activeEngineSupported ? (
+          <p className="minimizer-advisory" role="status">
+            Python and Java execution remain available in the main workbench,
+            corpus and unit-test modes. This reducer currently has verified
+            failure oracles only for ECMAScript and PCRE2.
+          </p>
+        ) : null}
 
         <section className="minimizer-config" aria-labelledby="minimize-target">
           <header>
@@ -716,7 +735,10 @@ export function MinimizePanel({
           <button
             type="button"
             className="primary-button"
-            disabled={running}
+            disabled={
+              running ||
+              (mode !== "comparison-mismatch" && !activeEngineSupported)
+            }
             onClick={() => void run()}
           >
             {running ? "Minimizing…" : "Verify & minimize"}