fix: block tools for handoff triage\n\nCo-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

sidecar/src/Eryx.AgentHost/Services/CopilotAgentBundle.cs

@@ -56,7 +56,7 @@ internal sealed class CopilotAgentBundle : IAsyncDisposable
                 Streaming = true,
             };
 
-            if (isScratchpad)
+            if (ShouldDisableSessionTools(command.Pattern, definition, command.WorkspaceKind))
             {
                 sessionConfig.AvailableTools = [];
             }
@@ -90,6 +90,25 @@ internal sealed class CopilotAgentBundle : IAsyncDisposable
         return bundle;
     }
 
+    internal static bool ShouldDisableSessionTools(
+        PatternDefinitionDto pattern,
+        PatternAgentDefinitionDto definition,
+        string workspaceKind)
+    {
+        if (string.Equals(workspaceKind, "scratchpad", StringComparison.OrdinalIgnoreCase))
+        {
+            return true;
+        }
+
+        if (!string.Equals(pattern.Mode, "handoff", StringComparison.OrdinalIgnoreCase))
+        {
+            return false;
+        }
+
+        PatternHandoffTopology topology = PatternGraphResolver.ResolveHandoff(pattern);
+        return string.Equals(definition.Id, topology.EntryAgentId, StringComparison.OrdinalIgnoreCase);
+    }
+
     public Workflow BuildWorkflow(PatternDefinitionDto pattern)
     {
         return pattern.Mode switch

sidecar/tests/Eryx.AgentHost.Tests/CopilotAgentBundleTests.cs

@@ -0,0 +1,90 @@
+using Eryx.AgentHost.Contracts;
+using Eryx.AgentHost.Services;
+
+namespace Eryx.AgentHost.Tests;
+
+public sealed class CopilotAgentBundleTests
+{
+    [Fact]
+    public void ShouldDisableSessionTools_DisablesScratchpadAgents()
+    {
+        PatternDefinitionDto pattern = CreatePattern(
+            mode: "sequential",
+            CreateAgent("agent-primary", "Primary"));
+
+        bool disabled = CopilotAgentBundle.ShouldDisableSessionTools(
+            pattern,
+            pattern.Agents[0],
+            workspaceKind: "scratchpad");
+
+        Assert.True(disabled);
+    }
+
+    [Fact]
+    public void ShouldDisableSessionTools_DisablesOnlyHandoffEntryAgent()
+    {
+        PatternDefinitionDto pattern = CreatePattern(
+            mode: "handoff",
+            CreateAgent("agent-handoff-triage", "Triage"),
+            CreateAgent("agent-handoff-runtime", "Runtime Specialist"));
+
+        bool triageDisabled = CopilotAgentBundle.ShouldDisableSessionTools(
+            pattern,
+            pattern.Agents[0],
+            workspaceKind: "project");
+        bool specialistDisabled = CopilotAgentBundle.ShouldDisableSessionTools(
+            pattern,
+            pattern.Agents[1],
+            workspaceKind: "project");
+
+        Assert.True(triageDisabled);
+        Assert.False(specialistDisabled);
+    }
+
+    [Fact]
+    public void ShouldDisableSessionTools_LeavesNonHandoffProjectAgentsEnabled()
+    {
+        PatternDefinitionDto pattern = CreatePattern(
+            mode: "sequential",
+            CreateAgent("agent-analyst", "Analyst"),
+            CreateAgent("agent-builder", "Builder"));
+
+        bool disabled = CopilotAgentBundle.ShouldDisableSessionTools(
+            pattern,
+            pattern.Agents[0],
+            workspaceKind: "project");
+
+        Assert.False(disabled);
+    }
+
+    private static PatternDefinitionDto CreatePattern(string mode, params PatternAgentDefinitionDto[] agents)
+    {
+        return new PatternDefinitionDto
+        {
+            Id = $"pattern-{mode}",
+            Name = mode,
+            Mode = mode,
+            Availability = "available",
+            Agents = agents,
+            Graph = PatternGraphResolver.CreateDefault(new PatternDefinitionDto
+            {
+                Id = $"pattern-{mode}",
+                Name = mode,
+                Mode = mode,
+                Availability = "available",
+                Agents = agents,
+            }),
+        };
+    }
+
+    private static PatternAgentDefinitionDto CreateAgent(string id, string name)
+    {
+        return new PatternAgentDefinitionDto
+        {
+            Id = id,
+            Name = name,
+            Instructions = $"You are {name}.",
+            Model = "gpt-5.4",
+        };
+    }
+}