Fix path modal support for multibyte

frontend/src/components/MessageList.tsx

@@ -380,8 +380,9 @@ export function MessageList({
       publicKeyOrPrefix: config?.public_key || '',
       lat: config?.lat ?? null,
       lon: config?.lon ?? null,
+      pathHashMode: config?.path_hash_mode ?? null,
     }),
-    [config?.name, config?.public_key, config?.lat, config?.lon]
+    [config?.name, config?.public_key, config?.lat, config?.lon, config?.path_hash_mode]
   );
 
   // Derive live so the byte-perfect button disables if the 30s window expires while modal is open
@@ -411,6 +412,7 @@ export function MessageList({
         publicKeyOrPrefix: contact.public_key,
         lat: contact.lat,
         lon: contact.lon,
+        pathHashMode: contact.out_path_hash_mode,
       };
     }
     // For channel messages, try to find contact by parsed sender name
@@ -422,6 +424,7 @@ export function MessageList({
           publicKeyOrPrefix: senderContact.public_key,
           lat: senderContact.lat,
           lon: senderContact.lon,
+          pathHashMode: senderContact.out_path_hash_mode,
         };
       }
     }
@@ -431,6 +434,7 @@ export function MessageList({
       publicKeyOrPrefix: msg.conversation_key || '',
       lat: null,
       lon: null,
+      pathHashMode: null,
     };
   };
 

frontend/src/test/pathUtils.test.ts

@@ -324,6 +324,33 @@ describe('resolvePath', () => {
     expect(result.receiver.name).toBe('MyRadio');
   });
 
+  it('uses explicit sender and receiver multibyte modes for endpoint prefixes', () => {
+    const result = resolvePath(
+      '',
+      { ...sender, pathHashMode: 1 },
+      contacts,
+      createConfig({
+        public_key: 'ABCDEF' + 'F'.repeat(58),
+        path_hash_mode: 2,
+      })
+    );
+
+    expect(result.sender.prefix).toBe('5EEE');
+    expect(result.receiver.prefix).toBe('ABCDEF');
+  });
+
+  it('derives sender multibyte width from path metadata when sender mode is unknown', () => {
+    const result = resolvePath(
+      '1A2B3C4D',
+      { ...sender, publicKeyOrPrefix: 'AABBCCDDEEFF' + '0'.repeat(52), pathHashMode: null },
+      contacts,
+      config,
+      2
+    );
+
+    expect(result.sender.prefix).toBe('AABB');
+  });
+
   it('handles null config gracefully', () => {
     const result = resolvePath('1A', sender, contacts, null);
 

frontend/src/utils/pathUtils.ts

@@ -29,6 +29,46 @@ export interface SenderInfo {
   publicKeyOrPrefix: string;
   lat: number | null;
   lon: number | null;
+  pathHashMode?: number | null;
+}
+
+function normalizePathHashMode(mode: number | null | undefined): number | null {
+  if (mode == null || !Number.isInteger(mode) || mode < 0 || mode > 2) {
+    return null;
+  }
+  return mode;
+}
+
+function inferPathHashMode(
+  path: string | null | undefined,
+  hopCount?: number | null
+): number | null {
+  if (!path || path.length === 0 || hopCount == null || hopCount <= 0) {
+    return null;
+  }
+
+  const charsPerHop = path.length / hopCount;
+  if (
+    charsPerHop < 2 ||
+    charsPerHop > 6 ||
+    charsPerHop % 2 !== 0 ||
+    charsPerHop * hopCount !== path.length
+  ) {
+    return null;
+  }
+
+  return charsPerHop / 2 - 1;
+}
+
+function formatEndpointPrefix(key: string | null | undefined, pathHashMode: number | null): string {
+  if (!key) {
+    return '??';
+  }
+
+  const normalized = key.toUpperCase();
+  const hashMode = normalizePathHashMode(pathHashMode) ?? 0;
+  const chars = (hashMode + 1) * 2;
+  return normalized.slice(0, Math.min(chars, normalized.length));
 }
 
 /**
@@ -269,9 +309,13 @@ export function resolvePath(
   hopCount?: number | null
 ): ResolvedPath {
   const hopPrefixes = parsePathHops(path, hopCount);
+  const inferredPathHashMode = inferPathHashMode(path, hopCount);
 
   // Build sender info
-  const senderPrefix = sender.publicKeyOrPrefix.toUpperCase().slice(0, 2);
+  const senderPrefix = formatEndpointPrefix(
+    sender.publicKeyOrPrefix,
+    normalizePathHashMode(sender.pathHashMode) ?? inferredPathHashMode
+  );
   const resolvedSender = {
     name: sender.name,
     prefix: senderPrefix,
@@ -280,7 +324,10 @@ export function resolvePath(
   };
 
   // Build receiver info from radio config
-  const receiverPrefix = config?.public_key?.toUpperCase().slice(0, 2) || '??';
+  const receiverPrefix = formatEndpointPrefix(
+    config?.public_key,
+    normalizePathHashMode(config?.path_hash_mode) ?? inferredPathHashMode
+  );
   const resolvedReceiver = {
     name: config?.name || 'Unknown',
     prefix: receiverPrefix,