fix: address PR review feedback for per-agent skills (#995)

- Add skills field to Python wire format converter
- Explicitly select agents in all E2E tests for deterministic behavior

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: MackinnonBuck

dotnet/test/SkillsTests.cs

@@ -105,7 +105,8 @@ public async Task Should_Allow_Agent_With_Skills_To_Invoke_Skill()
         var session = await CreateSessionAsync(new SessionConfig
         {
             SkillDirectories = [skillsDir],
-            CustomAgents = customAgents
+            CustomAgents = customAgents,
+            Agent = "skill-agent"
         });
 
         Assert.Matches(@"^[a-f0-9-]+$", session.SessionId);
@@ -135,7 +136,8 @@ public async Task Should_Not_Provide_Skills_To_Agent_Without_Skills_Field()
         var session = await CreateSessionAsync(new SessionConfig
         {
             SkillDirectories = [skillsDir],
-            CustomAgents = customAgents
+            CustomAgents = customAgents,
+            Agent = "no-skill-agent"
         });
 
         Assert.Matches(@"^[a-f0-9-]+$", session.SessionId);

go/internal/e2e/skills_test.go

@@ -126,6 +126,7 @@ func TestSkills(t *testing.T) {
 			OnPermissionRequest: copilot.PermissionHandler.ApproveAll,
 			SkillDirectories:    []string{skillsDir},
 			CustomAgents:        customAgents,
+			Agent:               "skill-agent",
 		})
 		if err != nil {
 			t.Fatalf("Failed to create session: %v", err)
@@ -163,6 +164,7 @@ func TestSkills(t *testing.T) {
 			OnPermissionRequest: copilot.PermissionHandler.ApproveAll,
 			SkillDirectories:    []string{skillsDir},
 			CustomAgents:        customAgents,
+			Agent:               "no-skill-agent",
 		})
 		if err != nil {
 			t.Fatalf("Failed to create session: %v", err)

nodejs/test/e2e/skills.test.ts

@@ -108,6 +108,7 @@ IMPORTANT: You MUST include the exact text "${SKILL_MARKER}" somewhere in EVERY
                 onPermissionRequest: approveAll,
                 skillDirectories: [skillsDir],
                 customAgents,
+                agent: "skill-agent",
             });
 
             expect(session.sessionId).toBeDefined();
@@ -136,6 +137,7 @@ IMPORTANT: You MUST include the exact text "${SKILL_MARKER}" somewhere in EVERY
                 onPermissionRequest: approveAll,
                 skillDirectories: [skillsDir],
                 customAgents,
+                agent: "no-skill-agent",
             });
 
             expect(session.sessionId).toBeDefined();

python/copilot/client.py

@@ -2021,6 +2021,8 @@ def _convert_custom_agent_to_wire_format(
             wire_agent["mcpServers"] = agent["mcp_servers"]
         if "infer" in agent:
             wire_agent["infer"] = agent["infer"]
+        if "skills" in agent:
+            wire_agent["skills"] = agent["skills"]
         return wire_agent
 
     async def _start_cli_server(self) -> None:

python/e2e/test_skills.py

@@ -104,6 +104,7 @@ async def test_should_allow_agent_with_skills_to_invoke_skill(self, ctx: E2ETest
             on_permission_request=PermissionHandler.approve_all,
             skill_directories=[skills_dir],
             custom_agents=custom_agents,
+            agent="skill-agent",
         )
 
         assert session.session_id is not None
@@ -132,6 +133,7 @@ async def test_should_not_provide_skills_to_agent_without_skills_field(
             on_permission_request=PermissionHandler.approve_all,
             skill_directories=[skills_dir],
             custom_agents=custom_agents,
+            agent="no-skill-agent",
         )
 
         assert session.session_id is not None