feat(harness): allow disabling general-purpose subagent

agentscope-harness/src/main/java/io/agentscope/harness/agent/HarnessAgent.java

@@ -1096,6 +1096,7 @@ public static class Builder {
         boolean disableWorkspaceContext = false;
         boolean disableAtPathExpansion = false;
         boolean disableSubagents = false;
+        boolean disableGeneralPurposeSubagent = false;
         boolean disableDynamicSkills = false;
         boolean disableDefaultWorkspaceSkills = false;
         boolean disableDynamicSubagents = false;
@@ -1937,6 +1938,17 @@ public Builder disableSubagents() {
             return this;
         }
 
+        /**
+         * Disables the built-in {@code general-purpose} subagent while keeping declared and custom
+         * subagents available.
+         *
+         * @return this builder
+         */
+        public Builder disableGeneralPurposeSubagent() {
+            this.disableGeneralPurposeSubagent = true;
+            return this;
+        }
+
         public Builder disableToolsConfig() {
             this.disableToolsConfig = true;
             return this;

agentscope-harness/src/main/java/io/agentscope/harness/agent/HarnessAgentBuilderSupport.java

@@ -197,13 +197,15 @@ static List<SubagentEntry> buildSubagentEntries(
 
         List<SubagentEntry> entries = new ArrayList<>();
 
-        entries.add(
-                new SubagentEntry(
-                        "general-purpose",
-                        "General-purpose subagent with same capabilities as the main agent."
-                                + " Use for any isolated task that can be fully delegated.",
-                        buildGeneralPurposeFactory(b, resolvedWorkspace, sandboxFs),
-                        null));
+        if (!b.disableGeneralPurposeSubagent) {
+            entries.add(
+                    new SubagentEntry(
+                            "general-purpose",
+                            "General-purpose subagent with same capabilities as the main agent."
+                                    + " Use for any isolated task that can be fully delegated.",
+                            buildGeneralPurposeFactory(b, resolvedWorkspace, sandboxFs),
+                            null));
+        }
 
         for (SubagentDeclaration decl : allDeclarations) {
             entries.add(
@@ -240,13 +242,15 @@ static List<SubagentEntry> buildStaticSubagentEntries(
             HarnessAgent.Builder b, Path resolvedWorkspace, SandboxBackedFilesystem sandboxFs) {
         List<SubagentEntry> entries = new ArrayList<>();
 
-        entries.add(
-                new SubagentEntry(
-                        "general-purpose",
-                        "General-purpose subagent with same capabilities as the main agent."
-                                + " Use for any isolated task that can be fully delegated.",
-                        buildGeneralPurposeFactory(b, resolvedWorkspace, sandboxFs),
-                        null));
+        if (!b.disableGeneralPurposeSubagent) {
+            entries.add(
+                    new SubagentEntry(
+                            "general-purpose",
+                            "General-purpose subagent with same capabilities as the main agent."
+                                    + " Use for any isolated task that can be fully delegated.",
+                            buildGeneralPurposeFactory(b, resolvedWorkspace, sandboxFs),
+                            null));
+        }
 
         for (SubagentDeclaration decl : b.subagentDeclarations) {
             entries.add(

agentscope-harness/src/test/java/io/agentscope/harness/agent/HarnessAgentTest.java

@@ -479,6 +479,53 @@ void subagentMarkdown_registersIdsAndSubagentTools() throws Exception {
                 "built-in general-purpose entry should be listed");
     }
 
+    @Test
+    void disableGeneralPurposeSubagent_keepsDeclaredSubagentsAvailable() throws Exception {
+        Files.createDirectories(workspace);
+        Files.writeString(workspace.resolve(WorkspaceConstants.AGENTS_MD), "# workspace\n");
+        Path subagents = workspace.resolve("subagents");
+        Files.createDirectories(subagents);
+        Files.writeString(
+                subagents.resolve("specialist.md"),
+                """
+                ---
+                description: A custom specialist subagent
+                ---
+                You only reply OK.
+                """);
+
+        Model model = stubModel("done");
+        HarnessAgent.Builder builder =
+                HarnessAgent.builder()
+                        .name("main")
+                        .model(model)
+                        .workspace(workspace)
+                        .abstractFilesystem(new LocalFilesystem(workspace))
+                        .disableGeneralPurposeSubagent();
+
+        List<String> entryNames =
+                builder.buildSubagentEntries(workspace).stream()
+                        .map(SubagentEntry::name)
+                        .collect(Collectors.toList());
+        assertFalse(entryNames.contains("general-purpose"));
+        assertTrue(entryNames.contains("specialist"));
+
+        HarnessAgent agent = builder.build();
+        agent.call(userText("go"), RuntimeContext.builder().sessionId("s2").build()).block();
+
+        @SuppressWarnings("unchecked")
+        ArgumentCaptor<List<Msg>> captor = ArgumentCaptor.forClass(List.class);
+        verify(model, atLeast(1)).stream(captor.capture(), any(), any());
+        String combined =
+                captor.getAllValues().stream()
+                        .map(HarnessAgentTest::joinAllText)
+                        .filter(s -> s.contains("## Subagents"))
+                        .findFirst()
+                        .orElse("");
+        assertTrue(combined.contains("`specialist`"));
+        assertFalse(combined.contains("general-purpose"));
+    }
+
     @Test
     void subagentsDir_loadsMarkdownDeclarations() throws Exception {
         Files.createDirectories(workspace);