fix: disambiguate bridged tool names

src/serve.ts

@@ -163,26 +163,36 @@ export function selectServedServers(
 }
 
 export function encodeToolName(server: string, tool: string): string {
-  return `${server}${TOOL_SEPARATOR}${tool}`;
+  return `${encodeToolNamePart(server)}${TOOL_SEPARATOR}${encodeToolNamePart(tool)}`;
 }
 
 export function decodeToolName(
   name: string,
   servedServers: readonly Pick<ServedServer, 'name'>[]
 ): { server: string; tool: string } | undefined {
-  const sorted = [...servedServers].toSorted((a, b) => b.name.length - a.name.length);
-  for (const server of sorted) {
-    const prefix = `${server.name}${TOOL_SEPARATOR}`;
-    if (name.startsWith(prefix)) {
-      const tool = name.slice(prefix.length);
-      if (tool.length > 0) {
-        return { server: server.name, tool };
-      }
-    }
+  const separatorIndex = name.indexOf(TOOL_SEPARATOR);
+  if (separatorIndex === -1) {
+    return undefined;
+  }
+  const server = decodeToolNamePart(name.slice(0, separatorIndex));
+  const tool = decodeToolNamePart(name.slice(separatorIndex + TOOL_SEPARATOR.length));
+  if (tool.length === 0) {
+    return undefined;
+  }
+  if (servedServers.some((served) => served.name === server)) {
+    return { server, tool };
   }
   return undefined;
 }
 
+function encodeToolNamePart(value: string): string {
+  return value.replaceAll('%', '%25').replaceAll('_', '%5F');
+}
+
+function decodeToolNamePart(value: string): string {
+  return value.replaceAll('%5F', '_').replaceAll('%25', '%');
+}
+
 function describeTool(server: string, description: string | undefined): string | undefined {
   if (!description) {
     return `Tool from MCPorter server '${server}'.`;

tests/serve.test.ts

@@ -39,12 +39,31 @@ describe('mcporter serve bridge', () => {
 
   it('encodes and decodes namespaced tool names with longest-prefix matching', () => {
     expect(encodeToolName('alpha', 'ping')).toBe('alpha__ping');
-    expect(decodeToolName('alpha-long__tool__with__separator', [{ name: 'alpha' }, { name: 'alpha-long' }])).toEqual({
+    expect(
+      decodeToolName('alpha-long__tool%5F%5Fwith%5F%5Fseparator', [{ name: 'alpha' }, { name: 'alpha-long' }])
+    ).toEqual({
       server: 'alpha-long',
       tool: 'tool__with__separator',
     });
   });
 
+  it('escapes namespaced tool parts to avoid server/tool collisions', () => {
+    const first = encodeToolName('alpha', 'beta__ping');
+    const second = encodeToolName('alpha__beta', 'ping');
+
+    expect(first).toBe('alpha__beta%5F%5Fping');
+    expect(second).toBe('alpha%5F%5Fbeta__ping');
+    expect(first).not.toBe(second);
+    expect(decodeToolName(first, [{ name: 'alpha' }, { name: 'alpha__beta' }])).toEqual({
+      server: 'alpha',
+      tool: 'beta__ping',
+    });
+    expect(decodeToolName(second, [{ name: 'alpha' }, { name: 'alpha__beta' }])).toEqual({
+      server: 'alpha__beta',
+      tool: 'ping',
+    });
+  });
+
   it('exposes daemon tools through a single MCP server', async () => {
     const runtime = {
       listTools: vi.fn().mockImplementation(async (server: string) => [