feat(fls): write the topology of a .fls, loaded by Java as the original

topologyWriter.ts writes konfiguration.xml from Java's view of a project:
the version line, the node items (label position, device with name,
host label flags, interfaces or ports), the cable items and the
documentation items. What a device's constructor makes is changed through
getters, as XMLEncoder does, and more is added; fewer than it makes set the
list anew. Cable ends name the port objects the getters return (the writer
now names a getter's result, <void id="Port0" property="port"/>), and each
cable carries the nodes the editor draws it between.

Checked by Java against Java: every corpus file, read and written again,
loads in Java FILIUS (the oracle's loading method, --sha256 ties its result
to the written bytes) to the same devices, names, positions, interfaces,
cables and documentation as the original; so does a synthetic topology with
what the corpus never sets. The oracle and the reader now also report a
cable's drawing ends (JCablePanel ziel1/ziel2): in the corpus the nodes it
joins, for all 183 cables. Mutation probes rewrite the files and let Java
load each mutant.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/java-oracle/README.md

@@ -85,6 +85,17 @@ wird leer, der Eintrag bleibt trotzdem; Typen außer A/MX/NS (auch `a`,
 `CNAME`, eine Kommentarzeile) gelten als gültig; eine TTL, die kein `int`
 ist, wird still 3600.
 
+## Was Java aus unseren Dateien lädt
+
+`run.sh` lädt auch die Dateien unter `packages/fls/test/written/`, die
+`topologyWriter.test.ts` mit `UPDATE_WRITTEN=1` schreibt (nicht
+eingecheckt), mit derselben Lademethode wie den Korpus, und schreibt
+`packages/fls/test/written.java.json` samt SHA-256 jeder Datei
+(`--sha256`), damit der Test merkt, wenn der Befund nicht mehr zur Ausgabe
+passt. Je Kabel steht auch `panel`: die Geräte, zwischen denen die
+Oberfläche es zeichnet (`JCablePanel.ziel1/ziel2`) — im Korpus bei allen 183
+Kabeln die Geräte, die es verbindet.
+
 ## Was Java aus unserem XML macht
 
 `BeansDump` liest jede `*.xml` unter `packages/fls/test/beans/` mit

tools/java-oracle/run.sh

@@ -88,3 +88,13 @@ beans="$root/packages/fls/test/beans"
 rm -f "$beans/beans.java.json"
 HOME="$here/.build/home" xvfb-run -a java -cp "$classpath:$here/.build" BeansDump "$beans" "$beans/beans.java.json" 2>&1 | grep -v 'logback\|^$' || true
 test -s "$beans/beans.java.json"
+
+# What Java loads from the files packages/fls writes (topologyWriter.test.ts
+# writes them with UPDATE_WRITTEN=1; the files are not checked in, their
+# SHA-256 is).
+written="$root/packages/fls/test/written"
+if [ -d "$written" ]; then
+    rm -f "$written.java.json"
+    HOME="$here/.build/home" xvfb-run -a java -cp "$classpath:$here/.build" FlsOracle "$written" "$written.java.json" --sha256 2>&1 | grep -v 'logback\|^$' || true
+    test -s "$written.java.json"
+fi

tools/java-oracle/src/FlsOracle.java

@@ -6,6 +6,7 @@
 
 import filius.gui.netzwerksicht.GUIDocuItem;
 import filius.gui.netzwerksicht.GUIKabelItem;
+import filius.gui.netzwerksicht.JCablePanel;
 import filius.gui.netzwerksicht.GUIKnotenItem;
 import filius.hardware.Kabel;
 import filius.hardware.NetzwerkInterface;
@@ -72,7 +73,9 @@ public class FlsOracle {
         for (Path file : files) {
             String name = root.relativize(file).toString();
             try {
-                result.put(name, read(file));
+                Map<String, Object> view = read(file);
+                if (args.length > 2 && args[2].equals("--sha256")) view.put("sha256", sha256(Files.readAllBytes(file)));
+                result.put(name, view);
             } catch (Throwable error) {
                 Throwable cause = error instanceof java.lang.reflect.InvocationTargetException && error.getCause() != null
                         ? error.getCause()
@@ -96,6 +99,19 @@ public class FlsOracle {
         System.exit(0);
     }
 
+    /** The position of an item in a list by identity, null when absent. */
+    static Integer indexOf(List<?> list, Object item) {
+        if (item == null) return null;
+        for (int index = 0; index < list.size(); index++) if (list.get(index) == item) return index;
+        return null;
+    }
+
+    static String sha256(byte[] bytes) throws Exception {
+        StringBuilder hex = new StringBuilder();
+        for (byte value : java.security.MessageDigest.getInstance("SHA-256").digest(bytes)) hex.append(String.format("%02x", value));
+        return hex.toString();
+    }
+
     /**
      * Loads the file twice. What FILIUS does not find in a file it rolls at
      * random (MAC addresses, a switch's SSID) — such values differ between
@@ -208,6 +224,10 @@ public class FlsOracle {
             }
             json.put("ends", ends);
             json.put("wireless", cable != null && cable.getWireless());
+            // The nodes the editor draws the cable between (JCablePanel).
+            JCablePanel panel = item.getKabelpanel();
+            json.put("panel", panel == null ? null
+                    : Arrays.asList(indexOf(nodes, panel.getZiel1()), indexOf(nodes, panel.getZiel2())));
             cableList.add(json);
         }