refactor: remove legacy patterns system, unify on workflows

Remove the entire patterns domain model, IPC channels, sidecar services,
renderer components, and tests. Sessions now bind exclusively to workflows
via workflowId. Builtin workflows replace builtin patterns.

Backend:
- Make AgentNodeConfig standalone (no longer extends PatternAgentDefinition)
- Add WorkflowOrchestrationMode and WorkflowExecutionDefinition
- Create builtin workflows (single-agent, sequential, concurrent, handoff, group-chat)
- Rewrite session model config helpers for workflow-only
- Remove pattern IPC channels, handlers, and preload bindings
- Merge createSession/createWorkflowSession into single method
- Remove sidecar PatternGraphResolver, PatternValidator, pattern DTOs
- Add workspace migration for legacy sessions (patternId -> workflowId)

Frontend:
- Delete PatternEditor, pattern-graph components, patternGraph lib
- Delete NewSessionModal (session creation uses workflows directly)
- Remove PatternsSection from SettingsPanel
- Update App.tsx, ChatPane, ActivityPanel, Sidebar, RunTimeline,
  AgentConfigFields, InlinePills, sessionActivity to use workflow types
- Delete pattern.ts domain module

78 files changed across backend and frontend.

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

sidecar/tests/Aryx.AgentHost.Tests/AgentIdentityResolverTests.cs

@@ -8,14 +8,14 @@ public sealed class AgentIdentityResolverTests
     [Fact]
     public void TryResolveKnownAgentIdentity_MatchesRuntimeExecutorIdentifier()
     {
-        PatternDefinitionDto pattern = CreatePattern(
+        WorkflowDefinitionDto workflow = CreateWorkflow(
         [
-            CreateAgent(id: "agent-concurrent-architect", name: "Architect"),
-            CreateAgent(id: "agent-concurrent-product", name: "Product"),
+            CreateAgent("agent-concurrent-architect", "Architect"),
+            CreateAgent("agent-concurrent-product", "Product"),
         ]);
 
         bool resolved = AgentIdentityResolver.TryResolveKnownAgentIdentity(
-            pattern,
+            workflow,
             "Architect_agent_concurrent_architect",
             out AgentIdentity agent);
 
@@ -27,14 +27,14 @@ public sealed class AgentIdentityResolverTests
     [Fact]
     public void TryResolveKnownAgentIdentity_MatchesSanitizedNameAndId()
     {
-        PatternDefinitionDto pattern = CreatePattern(
+        WorkflowDefinitionDto workflow = CreateWorkflow(
         [
-            CreateAgent(id: "agent-single-primary", name: "Primary Agent"),
+            CreateAgent("agent-single-primary", "Primary Agent"),
         ],
-        mode: "single");
+        orchestrationMode: "single");
 
         bool resolved = AgentIdentityResolver.TryResolveKnownAgentIdentity(
-            pattern,
+            workflow,
             "Primary_Agent_agent_single_primary",
             out AgentIdentity agent);
 
@@ -46,14 +46,14 @@ public sealed class AgentIdentityResolverTests
     [Fact]
     public void TryResolveKnownAgentIdentity_MapsAssistantToSingleAgent()
     {
-        PatternDefinitionDto pattern = CreatePattern(
+        WorkflowDefinitionDto workflow = CreateWorkflow(
         [
-            CreateAgent(id: "agent-single-primary", name: "Primary Agent"),
+            CreateAgent("agent-single-primary", "Primary Agent"),
         ],
-        mode: "single");
+        orchestrationMode: "single");
 
         bool resolved = AgentIdentityResolver.TryResolveKnownAgentIdentity(
-            pattern,
+            workflow,
             "assistant",
             out AgentIdentity agent);
 
@@ -63,16 +63,16 @@ public sealed class AgentIdentityResolverTests
     }
 
     [Fact]
-    public void TryResolveKnownAgentIdentity_DoesNotGuessAssistantForMultiAgentPattern()
+    public void TryResolveKnownAgentIdentity_DoesNotGuessAssistantForMultiAgentWorkflow()
     {
-        PatternDefinitionDto pattern = CreatePattern(
+        WorkflowDefinitionDto workflow = CreateWorkflow(
         [
-            CreateAgent(id: "agent-concurrent-architect", name: "Architect"),
-            CreateAgent(id: "agent-concurrent-product", name: "Product"),
+            CreateAgent("agent-concurrent-architect", "Architect"),
+            CreateAgent("agent-concurrent-product", "Product"),
         ]);
 
         bool resolved = AgentIdentityResolver.TryResolveKnownAgentIdentity(
-            pattern,
+            workflow,
             "assistant",
             out _);
 
@@ -82,14 +82,14 @@ public sealed class AgentIdentityResolverTests
     [Fact]
     public void ResolveDisplayAuthorName_UsesCanonicalAgentName()
     {
-        PatternDefinitionDto pattern = CreatePattern(
+        WorkflowDefinitionDto workflow = CreateWorkflow(
         [
-            CreateAgent(id: "agent-concurrent-implementer", name: "Implementer"),
+            CreateAgent("agent-concurrent-implementer", "Implementer"),
         ],
-        mode: "single");
+        orchestrationMode: "single");
 
         string authorName = AgentIdentityResolver.ResolveDisplayAuthorName(
-            pattern,
+            workflow,
             "Implementer_agent_concurrent_implementer");
 
         Assert.Equal("Implementer", authorName);
@@ -98,14 +98,14 @@ public sealed class AgentIdentityResolverTests
     [Fact]
     public void TryResolveObservedAgentIdentity_UsesFallbackAgentForGenericAssistant()
     {
-        PatternDefinitionDto pattern = CreatePattern(
+        WorkflowDefinitionDto workflow = CreateWorkflow(
         [
-            CreateAgent(id: "agent-handoff-ux", name: "UX Specialist"),
-            CreateAgent(id: "agent-handoff-runtime", name: "Runtime Specialist"),
+            CreateAgent("agent-handoff-ux", "UX Specialist"),
+            CreateAgent("agent-handoff-runtime", "Runtime Specialist"),
         ]);
 
         bool resolved = AgentIdentityResolver.TryResolveObservedAgentIdentity(
-            pattern,
+            workflow,
             "assistant",
             new AgentIdentity("agent-handoff-ux", "UX Specialist"),
             out AgentIdentity agent);
@@ -115,28 +115,43 @@ public sealed class AgentIdentityResolverTests
         Assert.Equal("UX Specialist", agent.AgentName);
     }
 
-    private static PatternDefinitionDto CreatePattern(
-        IReadOnlyList<PatternAgentDefinitionDto> agents,
-        string mode = "concurrent")
+    private static WorkflowDefinitionDto CreateWorkflow(
+        IReadOnlyList<WorkflowNodeDto> agents,
+        string orchestrationMode = "concurrent")
     {
-        return new PatternDefinitionDto
+        return new WorkflowDefinitionDto
         {
-            Id = $"{mode}-pattern",
-            Name = "Pattern",
-            Mode = mode,
-            Availability = "available",
-            Agents = agents,
+            Id = $"{orchestrationMode}-workflow",
+            Name = "Workflow",
+            Graph = new WorkflowGraphDto
+            {
+                Nodes =
+                [
+                    .. agents,
+                ],
+            },
+            Settings = new WorkflowSettingsDto
+            {
+                OrchestrationMode = orchestrationMode,
+            },
         };
     }
 
-    private static PatternAgentDefinitionDto CreateAgent(string id, string name)
+    private static WorkflowNodeDto CreateAgent(string id, string name)
     {
-        return new PatternAgentDefinitionDto
+        return new WorkflowNodeDto
         {
             Id = id,
-            Name = name,
-            Model = "gpt-5.4",
-            Instructions = "Help with the request.",
+            Kind = "agent",
+            Label = name,
+            Config = new WorkflowNodeConfigDto
+            {
+                Kind = "agent",
+                Id = id,
+                Name = name,
+                Model = "gpt-5.4",
+                Instructions = "Help with the request.",
+            },
         };
     }
 }

sidecar/tests/Aryx.AgentHost.Tests/AgentInstructionComposerTests.cs

@@ -8,19 +8,10 @@ public sealed class AgentInstructionComposerTests
     [Fact]
     public void Compose_LeavesNonHandoffInstructionsUnchanged()
     {
-        PatternDefinitionDto pattern = new()
-        {
-            Id = "pattern-sequential",
-            Name = "Sequential",
-            Mode = "sequential",
-            Availability = "available",
-        };
-        PatternAgentDefinitionDto agent = CreateAgent(
-            id: "agent-reviewer",
-            name: "Reviewer",
-            instructions: "Review the proposal.");
+        WorkflowDefinitionDto workflow = CreateWorkflow("sequential");
+        WorkflowNodeDto agent = CreateAgent("agent-reviewer", "Reviewer", "Review the proposal.");
 
-        string instructions = AgentInstructionComposer.Compose(pattern, agent, agentIndex: 0);
+        string instructions = AgentInstructionComposer.Compose(workflow, agent, agentIndex: 0);
 
         Assert.Equal("Review the proposal.", instructions);
     }
@@ -28,24 +19,12 @@ public sealed class AgentInstructionComposerTests
     [Fact]
     public void Compose_StrengthensGroupChatCollaborationRoles()
     {
-        PatternDefinitionDto pattern = new()
-        {
-            Id = "pattern-group-chat",
-            Name = "Group Chat",
-            Mode = "group-chat",
-            Availability = "available",
-        };
-        PatternAgentDefinitionDto writer = CreateAgent(
-            id: "agent-group-writer",
-            name: "Writer",
-            instructions: "Draft an answer.");
-        PatternAgentDefinitionDto reviewer = CreateAgent(
-            id: "agent-group-reviewer",
-            name: "Reviewer",
-            instructions: "Review the draft.");
+        WorkflowDefinitionDto workflow = CreateWorkflow("group-chat");
+        WorkflowNodeDto writer = CreateAgent("agent-group-writer", "Writer", "Draft an answer.");
+        WorkflowNodeDto reviewer = CreateAgent("agent-group-reviewer", "Reviewer", "Review the draft.");
 
-        string writerInstructions = AgentInstructionComposer.Compose(pattern, writer, agentIndex: 0);
-        string reviewerInstructions = AgentInstructionComposer.Compose(pattern, reviewer, agentIndex: 1);
+        string writerInstructions = AgentInstructionComposer.Compose(workflow, writer, agentIndex: 0);
+        string reviewerInstructions = AgentInstructionComposer.Compose(workflow, reviewer, agentIndex: 1);
 
         Assert.Contains("collaborative multi-turn group chat", writerInstructions, StringComparison.OrdinalIgnoreCase);
         Assert.Contains("refine your earlier draft", writerInstructions, StringComparison.OrdinalIgnoreCase);
@@ -56,19 +35,13 @@ public sealed class AgentInstructionComposerTests
     [Fact]
     public void Compose_LeavesHandoffTriagePromptFocusedOnAgentInstructions()
     {
-        PatternDefinitionDto pattern = new()
-        {
-            Id = "pattern-handoff",
-            Name = "Handoff",
-            Mode = "handoff",
-            Availability = "available",
-        };
-        PatternAgentDefinitionDto triage = CreateAgent(
-            id: "agent-handoff-triage",
-            name: "Triage",
-            instructions: "You triage requests and must hand them off to the most appropriate specialist.");
+        WorkflowDefinitionDto workflow = CreateWorkflow("handoff");
+        WorkflowNodeDto triage = CreateAgent(
+            "agent-handoff-triage",
+            "Triage",
+            "You triage requests and must hand them off to the most appropriate specialist.");
 
-        string instructions = AgentInstructionComposer.Compose(pattern, triage, agentIndex: 0);
+        string instructions = AgentInstructionComposer.Compose(workflow, triage, agentIndex: 0);
 
         Assert.Equal("You triage requests and must hand them off to the most appropriate specialist.", instructions);
         Assert.DoesNotContain("routing", instructions, StringComparison.OrdinalIgnoreCase);
@@ -78,19 +51,13 @@ public sealed class AgentInstructionComposerTests
     [Fact]
     public void Compose_LeavesHandoffSpecialistPromptFocusedOnAgentInstructions()
     {
-        PatternDefinitionDto pattern = new()
-        {
-            Id = "pattern-handoff",
-            Name = "Handoff",
-            Mode = "handoff",
-            Availability = "available",
-        };
-        PatternAgentDefinitionDto specialist = CreateAgent(
-            id: "agent-handoff-ux",
-            name: "UX Specialist",
-            instructions: "You focus on navigation, UX, and interaction details.");
+        WorkflowDefinitionDto workflow = CreateWorkflow("handoff");
+        WorkflowNodeDto specialist = CreateAgent(
+            "agent-handoff-ux",
+            "UX Specialist",
+            "You focus on navigation, UX, and interaction details.");
 
-        string instructions = AgentInstructionComposer.Compose(pattern, specialist, agentIndex: 1);
+        string instructions = AgentInstructionComposer.Compose(workflow, specialist, agentIndex: 1);
 
         Assert.Equal("You focus on navigation, UX, and interaction details.", instructions);
         Assert.DoesNotContain("triage agent", instructions, StringComparison.OrdinalIgnoreCase);
@@ -100,20 +67,11 @@ public sealed class AgentInstructionComposerTests
     [Fact]
     public void Compose_AddsScratchpadGuidanceForProjectlessQaSessions()
     {
-        PatternDefinitionDto pattern = new()
-        {
-            Id = "pattern-single",
-            Name = "Single",
-            Mode = "single",
-            Availability = "available",
-        };
-        PatternAgentDefinitionDto agent = CreateAgent(
-            id: "agent-primary",
-            name: "Primary Agent",
-            instructions: "You are a helpful assistant.");
+        WorkflowDefinitionDto workflow = CreateWorkflow("single");
+        WorkflowNodeDto agent = CreateAgent("agent-primary", "Primary Agent", "You are a helpful assistant.");
 
         string instructions = AgentInstructionComposer.Compose(
-            pattern,
+            workflow,
             agent,
             agentIndex: 0,
             workspaceKind: "scratchpad");
@@ -127,20 +85,11 @@ public sealed class AgentInstructionComposerTests
     [Fact]
     public void Compose_AddsPlanModeGuidanceWhenRequested()
     {
-        PatternDefinitionDto pattern = new()
-        {
-            Id = "pattern-single",
-            Name = "Single",
-            Mode = "single",
-            Availability = "available",
-        };
-        PatternAgentDefinitionDto agent = CreateAgent(
-            id: "agent-primary",
-            name: "Primary Agent",
-            instructions: "You are a helpful assistant.");
+        WorkflowDefinitionDto workflow = CreateWorkflow("single");
+        WorkflowNodeDto agent = CreateAgent("agent-primary", "Primary Agent", "You are a helpful assistant.");
 
         string instructions = AgentInstructionComposer.Compose(
-            pattern,
+            workflow,
             agent,
             agentIndex: 0,
             interactionMode: "plan");
@@ -154,20 +103,11 @@ public sealed class AgentInstructionComposerTests
     [Fact]
     public void Compose_InsertsProjectInstructionsBetweenBaseAndRuntimeGuidance()
     {
-        PatternDefinitionDto pattern = new()
-        {
-            Id = "pattern-single",
-            Name = "Single",
-            Mode = "single",
-            Availability = "available",
-        };
-        PatternAgentDefinitionDto agent = CreateAgent(
-            id: "agent-primary",
-            name: "Primary Agent",
-            instructions: "You are a helpful assistant.");
+        WorkflowDefinitionDto workflow = CreateWorkflow("single");
+        WorkflowNodeDto agent = CreateAgent("agent-primary", "Primary Agent", "You are a helpful assistant.");
 
         string instructions = AgentInstructionComposer.Compose(
-            pattern,
+            workflow,
             agent,
             agentIndex: 0,
             workspaceKind: "scratchpad",
@@ -187,20 +127,11 @@ public sealed class AgentInstructionComposerTests
     [Fact]
     public void Compose_AppendsPromptInvocationAsATaskDirective()
     {
-        PatternDefinitionDto pattern = new()
-        {
-            Id = "pattern-single",
-            Name = "Single",
-            Mode = "single",
-            Availability = "available",
-        };
-        PatternAgentDefinitionDto agent = CreateAgent(
-            id: "agent-primary",
-            name: "Primary Agent",
-            instructions: "You are a helpful assistant.");
+        WorkflowDefinitionDto workflow = CreateWorkflow("single");
+        WorkflowNodeDto agent = CreateAgent("agent-primary", "Primary Agent", "You are a helpful assistant.");
 
         string instructions = AgentInstructionComposer.Compose(
-            pattern,
+            workflow,
             agent,
             agentIndex: 0,
             promptInvocation: new RunTurnPromptInvocationDto
@@ -228,14 +159,34 @@ public sealed class AgentInstructionComposerTests
             StringComparison.Ordinal);
     }
 
-    private static PatternAgentDefinitionDto CreateAgent(string id, string name, string instructions)
+    private static WorkflowDefinitionDto CreateWorkflow(string orchestrationMode)
     {
-        return new PatternAgentDefinitionDto
+        return new WorkflowDefinitionDto
+        {
+            Id = $"{orchestrationMode}-workflow",
+            Name = "Workflow",
+            Settings = new WorkflowSettingsDto
+            {
+                OrchestrationMode = orchestrationMode,
+            },
+        };
+    }
+
+    private static WorkflowNodeDto CreateAgent(string id, string name, string instructions)
+    {
+        return new WorkflowNodeDto
         {
             Id = id,
-            Name = name,
-            Instructions = instructions,
-            Model = "gpt-5.4",
+            Kind = "agent",
+            Label = name,
+            Config = new WorkflowNodeConfigDto
+            {
+                Kind = "agent",
+                Id = id,
+                Name = name,
+                Instructions = instructions,
+                Model = "gpt-5.4",
+            },
         };
     }
 }

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

@@ -158,34 +158,17 @@ public sealed class CopilotAgentBundleTests
         Assert.Equal(HandoffWorkflowGuidance.CreateWorkflowInstructions(), builder.HandoffInstructions);
     }
 
-    [Theory]
-    [InlineData("single", 1)]
-    [InlineData("sequential", 2)]
-    [InlineData("concurrent", 2)]
-    [InlineData("group-chat", 2)]
-    public void BuildWorkflow_ExplicitlyConfiguresAgentHostOptions(string mode, int agentCount)
+    [Fact]
+    public void CreateAgentHostOptions_UsesExpectedAryxDefaults()
     {
-        CopilotAgentBundle bundle = new(CreateAgents(agentCount), hasConfiguredHooks: false);
-        PatternDefinitionDto pattern = CreatePattern(mode, agentCount);
+        AIAgentHostOptions options = CopilotAgentBundle.CreateAgentHostOptions();
 
-        Workflow workflow = bundle.BuildWorkflow(pattern);
-
-        AIAgentBinding[] bindings = workflow.ReflectExecutors().Values
-            .OfType<AIAgentBinding>()
-            .ToArray();
-
-        Assert.Equal(agentCount, bindings.Length);
-
-        foreach (AIAgentBinding binding in bindings)
-        {
-            AIAgentHostOptions options = Assert.IsType<AIAgentHostOptions>(binding.Options);
-            Assert.Null(options.EmitAgentUpdateEvents);
-            Assert.False(options.EmitAgentResponseEvents);
-            Assert.False(options.InterceptUserInputRequests);
-            Assert.False(options.InterceptUnterminatedFunctionCalls);
-            Assert.True(options.ReassignOtherAgentsAsUsers);
-            Assert.True(options.ForwardIncomingMessages);
-        }
+        Assert.Null(options.EmitAgentUpdateEvents);
+        Assert.False(options.EmitAgentResponseEvents);
+        Assert.False(options.InterceptUserInputRequests);
+        Assert.False(options.InterceptUnterminatedFunctionCalls);
+        Assert.True(options.ReassignOtherAgentsAsUsers);
+        Assert.True(options.ForwardIncomingMessages);
     }
 
     [Fact]
@@ -387,28 +370,12 @@ public sealed class CopilotAgentBundleTests
             ProjectPath = @"C:\workspace\project",
             WorkspaceKind = "project",
             Mode = "interactive",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-1",
-                Name = "Pattern",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    new PatternAgentDefinitionDto
-                    {
-                        Id = "agent-1",
-                        Name = "Primary",
-                        Model = "gpt-5.4",
-                        Instructions = "Help.",
-                    },
-                ],
-            },
+            Workflow = CreateWorkflow("single", 1),
         };
 
         SessionConfig sessionConfig = CopilotAgentBundle.CreateSessionConfig(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             agentIndex: 0);
 
         Assert.Null(sessionConfig.SessionId);
@@ -427,28 +394,12 @@ public sealed class CopilotAgentBundleTests
             WorkspaceKind = "project",
             Mode = "interactive",
             ProjectInstructions = "Follow repository guidance.",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-1",
-                Name = "Pattern",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    new PatternAgentDefinitionDto
-                    {
-                        Id = "agent-1",
-                        Name = "Primary",
-                        Model = "gpt-5.4",
-                        Instructions = "Help.",
-                    },
-                ],
-            },
+            Workflow = CreateWorkflow("single", 1),
         };
 
         SessionConfig sessionConfig = CopilotAgentBundle.CreateSessionConfig(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             agentIndex: 0);
 
         Assert.Equal("Help.\n\nFollow repository guidance.", sessionConfig.SystemMessage?.Content);
@@ -471,28 +422,12 @@ public sealed class CopilotAgentBundleTests
                 Agent = "designer",
                 ResolvedPrompt = "Review the docs for missing steps.",
             },
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-1",
-                Name = "Pattern",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    new PatternAgentDefinitionDto
-                    {
-                        Id = "agent-1",
-                        Name = "Primary",
-                        Model = "gpt-5.4",
-                        Instructions = "Help.",
-                    },
-                ],
-            },
+            Workflow = CreateWorkflow("single", 1),
         };
 
         SessionConfig sessionConfig = CopilotAgentBundle.CreateSessionConfig(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             agentIndex: 0);
 
         Assert.Equal("designer", sessionConfig.Agent);
@@ -516,28 +451,12 @@ public sealed class CopilotAgentBundleTests
                 ResolvedPrompt = "Review the docs for missing steps.",
                 Tools = ["view"],
             },
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-1",
-                Name = "Pattern",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    new PatternAgentDefinitionDto
-                    {
-                        Id = "agent-1",
-                        Name = "Primary",
-                        Model = "gpt-5.4",
-                        Instructions = "Help.",
-                    },
-                ],
-            },
+            Workflow = CreateWorkflow("single", 1),
         };
 
         SessionConfig sessionConfig = CopilotAgentBundle.CreateSessionConfig(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             agentIndex: 0);
 
         Assert.Equal("agent", sessionConfig.Agent);
@@ -550,13 +469,10 @@ public sealed class CopilotAgentBundleTests
         {
             RequestId = "turn-1",
             SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-1",
-                Name = "Pattern",
-                Mode = "single",
-                Availability = "available",
-                ApprovalPolicy = new ApprovalPolicyDto
+            Workflow = CreateWorkflow(
+                "single",
+                1,
+                new ApprovalPolicyDto
                 {
                     Rules =
                     [
@@ -566,21 +482,10 @@ public sealed class CopilotAgentBundleTests
                             AgentIds = ["agent-1"],
                         },
                     ],
-                },
-                Agents =
-                [
-                    new PatternAgentDefinitionDto
-                    {
-                        Id = "agent-1",
-                        Name = "Primary",
-                        Model = "gpt-5.4",
-                        Instructions = "Help.",
-                    },
-                ],
-            },
+                }),
         };
 
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0]);
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0]);
         PreToolUseHookOutput? decision = await hooks.OnPreToolUse!(
             new PreToolUseHookInput
             {
@@ -630,25 +535,41 @@ public sealed class CopilotAgentBundleTests
             .Select(index => (AIAgent)CreateChatClientAgent($"agent-{index}", $"Agent {index}"))
             .ToArray();
 
-    private static PatternDefinitionDto CreatePattern(string mode, int agentCount)
+    private static WorkflowDefinitionDto CreateWorkflow(
+        string mode,
+        int agentCount,
+        ApprovalPolicyDto? approvalPolicy = null)
     {
-        return new PatternDefinitionDto
+        return new WorkflowDefinitionDto
         {
-            Id = $"pattern-{mode}",
-            Name = $"Pattern {mode}",
-            Mode = mode,
-            Availability = "available",
-            Agents =
-            [
-                .. Enumerable.Range(1, agentCount).Select(index => new PatternAgentDefinitionDto
-                {
-                    Id = $"agent-{index}",
-                    Name = $"Agent {index}",
-                    Description = $"Agent {index} description.",
-                    Instructions = $"Agent {index} instructions.",
-                    Model = "gpt-5.4",
-                }),
-            ],
+            Id = $"workflow-{mode}",
+            Name = $"Workflow {mode}",
+            Graph = new WorkflowGraphDto
+            {
+                Nodes =
+                [
+                    .. Enumerable.Range(1, agentCount).Select(index => new WorkflowNodeDto
+                    {
+                        Id = $"agent-{index}",
+                        Kind = "agent",
+                        Label = $"Agent {index}",
+                        Config = new WorkflowNodeConfigDto
+                        {
+                            Kind = "agent",
+                            Id = $"agent-{index}",
+                            Name = $"Agent {index}",
+                            Description = $"Agent {index} description.",
+                            Instructions = "Help.",
+                            Model = "gpt-5.4",
+                        },
+                    }),
+                ],
+            },
+            Settings = new WorkflowSettingsDto
+            {
+                OrchestrationMode = mode,
+                ApprovalPolicy = approvalPolicy,
+            },
         };
     }
 
@@ -697,3 +618,4 @@ public sealed class CopilotAgentBundleTests
         }
     }
 }
+

sidecar/tests/Aryx.AgentHost.Tests/CopilotExitPlanModeCoordinatorTests.cs

@@ -14,7 +14,7 @@ public sealed class CopilotExitPlanModeCoordinatorTests
 
         ExitPlanModeRequestedEventDto exitPlanEvent = coordinator.RecordExitPlanModeRequest(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             new ExitPlanModeRequestedEvent
             {
                 Data = new ExitPlanModeRequestedData
@@ -50,23 +50,36 @@ public sealed class CopilotExitPlanModeCoordinatorTests
         {
             RequestId = "turn-1",
             SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
+            Workflow = new WorkflowDefinitionDto
             {
-                Id = "pattern-1",
-                Name = "Plan Mode Pattern",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    new PatternAgentDefinitionDto
-                    {
-                        Id = "agent-1",
-                        Name = "Primary",
-                        Model = "gpt-5.4",
-                        Instructions = "Help with the request.",
-                    },
-                ],
+                Id = "workflow-1",
+                Name = "Plan Mode Workflow",
+                Graph = new WorkflowGraphDto
+                {
+                    Nodes =
+                    [
+                        new WorkflowNodeDto
+                        {
+                            Id = "agent-1",
+                            Kind = "agent",
+                            Label = "Primary",
+                            Config = new WorkflowNodeConfigDto
+                            {
+                                Kind = "agent",
+                                Id = "agent-1",
+                                Name = "Primary",
+                                Model = "gpt-5.4",
+                                Instructions = "Help with the request.",
+                            },
+                        },
+                    ],
+                },
+                Settings = new WorkflowSettingsDto
+                {
+                    OrchestrationMode = "single",
+                },
             },
         };
     }
 }
+

sidecar/tests/Aryx.AgentHost.Tests/CopilotMcpOAuthCoordinatorTests.cs

@@ -14,7 +14,7 @@ public sealed class CopilotMcpOAuthCoordinatorTests
 
         McpOauthRequiredEventDto oauthEvent = coordinator.BuildMcpOauthRequiredEvent(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             new McpOauthRequiredEvent
             {
                 Data = new McpOauthRequiredData
@@ -49,23 +49,36 @@ public sealed class CopilotMcpOAuthCoordinatorTests
         {
             RequestId = "turn-1",
             SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
+            Workflow = new WorkflowDefinitionDto
             {
-                Id = "pattern-1",
-                Name = "MCP OAuth Pattern",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    new PatternAgentDefinitionDto
-                    {
-                        Id = "agent-1",
-                        Name = "Primary",
-                        Model = "gpt-5.4",
-                        Instructions = "Help with the request.",
-                    },
-                ],
+                Id = "workflow-1",
+                Name = "MCP OAuth Workflow",
+                Graph = new WorkflowGraphDto
+                {
+                    Nodes =
+                    [
+                        new WorkflowNodeDto
+                        {
+                            Id = "agent-1",
+                            Kind = "agent",
+                            Label = "Primary",
+                            Config = new WorkflowNodeConfigDto
+                            {
+                                Kind = "agent",
+                                Id = "agent-1",
+                                Name = "Primary",
+                                Model = "gpt-5.4",
+                                Instructions = "Help with the request.",
+                            },
+                        },
+                    ],
+                },
+                Settings = new WorkflowSettingsDto
+                {
+                    OrchestrationMode = "single",
+                },
             },
         };
     }
 }
+

sidecar/tests/Aryx.AgentHost.Tests/CopilotSessionHooksTests.cs

@@ -23,7 +23,7 @@ public sealed class CopilotSessionHooksTests
             ],
         };
 
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0], configuredHooks, runner);
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0], configuredHooks, runner);
 
         PreToolUseHookOutput? decision = await hooks.OnPreToolUse!(
             new PreToolUseHookInput
@@ -64,7 +64,7 @@ public sealed class CopilotSessionHooksTests
             ],
         };
 
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0], configuredHooks, runner);
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0], configuredHooks, runner);
 
         PreToolUseHookOutput? decision = await hooks.OnPreToolUse!(
             new PreToolUseHookInput
@@ -93,7 +93,7 @@ public sealed class CopilotSessionHooksTests
             ],
         };
 
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0], configuredHooks, runner);
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0], configuredHooks, runner);
 
         PreToolUseHookOutput? decision = await hooks.OnPreToolUse!(
             new PreToolUseHookInput
@@ -123,7 +123,7 @@ public sealed class CopilotSessionHooksTests
     public async Task Create_PreToolUseAutoAllowsInternalOrchestrationTools(string toolName)
     {
         RunTurnCommandDto command = CreateCommandWithToolApproval();
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
 
         PreToolUseHookOutput? decision = await hooks.OnPreToolUse!(
             new PreToolUseHookInput
@@ -139,7 +139,7 @@ public sealed class CopilotSessionHooksTests
     public async Task Create_PreToolUseKeepsStoreMemoryUnderApprovalPolicy()
     {
         RunTurnCommandDto command = CreateCommandWithToolApproval();
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
 
         PreToolUseHookOutput? decision = await hooks.OnPreToolUse!(
             new PreToolUseHookInput
@@ -159,7 +159,7 @@ public sealed class CopilotSessionHooksTests
     public async Task Create_PreToolUseAutoAllowsWhenCategoryIsApproved(string toolName, string category)
     {
         RunTurnCommandDto command = CreateCommandWithAutoApprovedCategory(category);
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
 
         PreToolUseHookOutput? decision = await hooks.OnPreToolUse!(
             new PreToolUseHookInput
@@ -177,7 +177,7 @@ public sealed class CopilotSessionHooksTests
         RunTurnCommandDto command = CreateCommandWithConfiguredMcpServers(
             ["icm-mcp"],
             ["mcp_server:icm-mcp"]);
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
 
         PreToolUseHookOutput? decision = await hooks.OnPreToolUse!(
             new PreToolUseHookInput
@@ -193,7 +193,7 @@ public sealed class CopilotSessionHooksTests
     public async Task Create_PreToolUseRequiresApprovalWhenMcpServerIsNotApproved()
     {
         RunTurnCommandDto command = CreateCommandWithConfiguredMcpServers(["icm-mcp"]);
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
 
         PreToolUseHookOutput? decision = await hooks.OnPreToolUse!(
             new PreToolUseHookInput
@@ -219,7 +219,7 @@ public sealed class CopilotSessionHooksTests
             ErrorOccurred = [CreateHookCommand("error-hook")],
         };
 
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0], configuredHooks, runner);
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0], configuredHooks, runner);
 
         await hooks.OnSessionStart!(
             new SessionStartHookInput
@@ -293,7 +293,7 @@ public sealed class CopilotSessionHooksTests
     public async Task Create_WithoutConfiguredFileHooksPreservesExistingApprovalBehavior()
     {
         RunTurnCommandDto command = CreateCommandWithoutApprovalRules();
-        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Pattern.Agents[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
+        SessionHooks hooks = CopilotSessionHooks.Create(command, command.Workflow.GetAgentNodes()[0], ResolvedHookSet.Empty, new RecordingHookCommandRunner());
 
         PreToolUseHookOutput? decision = await hooks.OnPreToolUse!(
             new PreToolUseHookInput
@@ -312,34 +312,17 @@ public sealed class CopilotSessionHooksTests
             RequestId = "turn-1",
             SessionId = "session-1",
             ProjectPath = @"C:\workspace\project",
-            Pattern = new PatternDefinitionDto
+            Workflow = CreateWorkflow(new ApprovalPolicyDto
             {
-                Id = "pattern-1",
-                Name = "Pattern",
-                Mode = "single",
-                Availability = "available",
-                ApprovalPolicy = new ApprovalPolicyDto
-                {
-                    Rules =
-                    [
-                        new ApprovalCheckpointRuleDto
-                        {
-                            Kind = "tool-call",
-                            AgentIds = ["agent-1"],
-                        },
-                    ],
-                },
-                Agents =
+                Rules =
                 [
-                    new PatternAgentDefinitionDto
+                    new ApprovalCheckpointRuleDto
                     {
-                        Id = "agent-1",
-                        Name = "Primary",
-                        Model = "gpt-5.4",
-                        Instructions = "Help.",
+                        Kind = "tool-call",
+                        AgentIds = ["agent-1"],
                     },
                 ],
-            },
+            }),
         };
     }
 
@@ -351,15 +334,7 @@ public sealed class CopilotSessionHooksTests
             RequestId = command.RequestId,
             SessionId = command.SessionId,
             ProjectPath = command.ProjectPath,
-            Pattern = new PatternDefinitionDto
-            {
-                Id = command.Pattern.Id,
-                Name = command.Pattern.Name,
-                Mode = command.Pattern.Mode,
-                Availability = command.Pattern.Availability,
-                ApprovalPolicy = new ApprovalPolicyDto(),
-                Agents = command.Pattern.Agents,
-            },
+            Workflow = CreateWorkflow(new ApprovalPolicyDto()),
         };
     }
 
@@ -370,35 +345,18 @@ public sealed class CopilotSessionHooksTests
             RequestId = "turn-1",
             SessionId = "session-1",
             ProjectPath = @"C:\workspace\project",
-            Pattern = new PatternDefinitionDto
+            Workflow = CreateWorkflow(new ApprovalPolicyDto
             {
-                Id = "pattern-1",
-                Name = "Pattern",
-                Mode = "single",
-                Availability = "available",
-                ApprovalPolicy = new ApprovalPolicyDto
-                {
-                    Rules =
-                    [
-                        new ApprovalCheckpointRuleDto
-                        {
-                            Kind = "tool-call",
-                            AgentIds = ["agent-1"],
-                        },
-                    ],
-                    AutoApprovedToolNames = [category],
-                },
-                Agents =
+                Rules =
                 [
-                    new PatternAgentDefinitionDto
+                    new ApprovalCheckpointRuleDto
                     {
-                        Id = "agent-1",
-                        Name = "Primary",
-                        Model = "gpt-5.4",
-                        Instructions = "Help.",
+                        Kind = "tool-call",
+                        AgentIds = ["agent-1"],
                     },
                 ],
-            },
+                AutoApprovedToolNames = [category],
+            }),
         };
     }
 
@@ -416,18 +374,44 @@ public sealed class CopilotSessionHooksTests
             {
                 McpServers = [.. serverNames.Select(CreateMcpServerConfig)],
             },
-            Pattern = new PatternDefinitionDto
+            Workflow = CreateWorkflow(new ApprovalPolicyDto
             {
-                Id = command.Pattern.Id,
-                Name = command.Pattern.Name,
-                Mode = command.Pattern.Mode,
-                Availability = command.Pattern.Availability,
-                ApprovalPolicy = new ApprovalPolicyDto
-                {
-                    Rules = command.Pattern.ApprovalPolicy?.Rules ?? [],
-                    AutoApprovedToolNames = autoApprovedToolNames ?? [],
-                },
-                Agents = command.Pattern.Agents,
+                Rules = command.Workflow.Settings.ApprovalPolicy?.Rules ?? [],
+                AutoApprovedToolNames = autoApprovedToolNames ?? [],
+            }),
+        };
+    }
+
+    private static WorkflowDefinitionDto CreateWorkflow(ApprovalPolicyDto approvalPolicy)
+    {
+        return new WorkflowDefinitionDto
+        {
+            Id = "workflow-1",
+            Name = "Workflow",
+            Graph = new WorkflowGraphDto
+            {
+                Nodes =
+                [
+                    new WorkflowNodeDto
+                    {
+                        Id = "agent-1",
+                        Kind = "agent",
+                        Label = "Primary",
+                        Config = new WorkflowNodeConfigDto
+                        {
+                            Kind = "agent",
+                            Id = "agent-1",
+                            Name = "Primary",
+                            Model = "gpt-5.4",
+                            Instructions = "Help.",
+                        },
+                    },
+                ],
+            },
+            Settings = new WorkflowSettingsDto
+            {
+                OrchestrationMode = "single",
+                ApprovalPolicy = approvalPolicy,
             },
         };
     }
@@ -477,3 +461,4 @@ public sealed class CopilotSessionHooksTests
         string InputJson,
         string ProjectPath);
 }
+

sidecar/tests/Aryx.AgentHost.Tests/CopilotTurnExecutionStateTests.cs

@@ -14,7 +14,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             new McpOauthRequiredEvent
             {
                 Data = new McpOauthRequiredData
@@ -37,7 +37,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -66,7 +66,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """{"type":"tool.execution_start","data":{"toolCallId":"tool-call-1","toolName":"view"},"id":"33333333-3333-3333-3333-333333333333","timestamp":"2026-03-27T00:00:00Z"}"""));
 
@@ -85,7 +85,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """{"type":"tool.execution_start","data":{"toolCallId":"tool-call-1","toolName":"handoff_to_specialist"},"id":"1ce9d1dc-68f1-4df5-9728-f97017233279","timestamp":"2026-03-27T00:00:00Z"}"""));
 
@@ -101,7 +101,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -142,7 +142,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -158,7 +158,7 @@ public sealed class CopilotTurnExecutionStateTests
         _ = state.DrainPendingEvents();
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -172,7 +172,7 @@ public sealed class CopilotTurnExecutionStateTests
                 }
                 """));
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -207,7 +207,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -231,7 +231,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -267,7 +267,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -298,7 +298,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -356,7 +356,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -386,7 +386,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -417,7 +417,7 @@ public sealed class CopilotTurnExecutionStateTests
         RunTurnCommandDto command = CreateCommand();
         CopilotTurnExecutionState state = new(command);
 
-        state.ObserveSessionEvent(command.Pattern.Agents[0], CreateHookStartEvent());
+        state.ObserveSessionEvent(command.Workflow.GetAgentNodes()[0], CreateHookStartEvent());
 
         HookLifecycleEventDto evt = Assert.Single(state.DrainPendingEvents().OfType<HookLifecycleEventDto>());
         Assert.Equal("start", evt.Phase);
@@ -432,7 +432,7 @@ public sealed class CopilotTurnExecutionStateTests
         RunTurnCommandDto command = CreateCommand();
         CopilotTurnExecutionState state = new(command);
 
-        state.ObserveSessionEvent(command.Pattern.Agents[0], CreateHookEndEvent());
+        state.ObserveSessionEvent(command.Workflow.GetAgentNodes()[0], CreateHookEndEvent());
 
         HookLifecycleEventDto evt = Assert.Single(state.DrainPendingEvents().OfType<HookLifecycleEventDto>());
         Assert.Equal("end", evt.Phase);
@@ -450,8 +450,8 @@ public sealed class CopilotTurnExecutionStateTests
             SuppressHookLifecycleEvents = true,
         };
 
-        state.ObserveSessionEvent(command.Pattern.Agents[0], CreateHookStartEvent());
-        state.ObserveSessionEvent(command.Pattern.Agents[0], CreateHookEndEvent());
+        state.ObserveSessionEvent(command.Workflow.GetAgentNodes()[0], CreateHookStartEvent());
+        state.ObserveSessionEvent(command.Workflow.GetAgentNodes()[0], CreateHookEndEvent());
 
         Assert.Empty(state.DrainPendingEvents());
     }
@@ -463,7 +463,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -526,7 +526,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -561,7 +561,7 @@ public sealed class CopilotTurnExecutionStateTests
         CopilotTurnExecutionState state = new(command);
 
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -624,7 +624,7 @@ public sealed class CopilotTurnExecutionStateTests
 
         // Simulate assistant message with tool requests → triggers reclassification
         state.ObserveSessionEvent(
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             SessionEvent.FromJson(
                 """
                 {
@@ -672,23 +672,36 @@ public sealed class CopilotTurnExecutionStateTests
         {
             RequestId = "turn-1",
             SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
+            Workflow = new WorkflowDefinitionDto
             {
-                Id = "pattern-1",
-                Name = "MCP OAuth Pattern",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    new PatternAgentDefinitionDto
-                    {
-                        Id = "agent-1",
-                        Name = "Primary",
-                        Model = "gpt-5.4",
-                        Instructions = "Help with the request.",
-                    },
-                ],
+                Id = "workflow-1",
+                Name = "Execution State Workflow",
+                Graph = new WorkflowGraphDto
+                {
+                    Nodes =
+                    [
+                        new WorkflowNodeDto
+                        {
+                            Id = "agent-1",
+                            Kind = "agent",
+                            Label = "Primary",
+                            Config = new WorkflowNodeConfigDto
+                            {
+                                Kind = "agent",
+                                Id = "agent-1",
+                                Name = "Primary",
+                                Model = "gpt-5.4",
+                                Instructions = "Help with the request.",
+                            },
+                        },
+                    ],
+                },
+                Settings = new WorkflowSettingsDto
+                {
+                    OrchestrationMode = "single",
+                },
             },
         };
     }
 }
+

sidecar/tests/Aryx.AgentHost.Tests/CopilotUserInputCoordinatorTests.cs

@@ -15,7 +15,7 @@ public sealed class CopilotUserInputCoordinatorTests
 
         Task<UserInputResponse> pending = coordinator.RequestUserInputAsync(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             new UserInputRequest
             {
                 Question = "How should I proceed?",
@@ -76,33 +76,40 @@ public sealed class CopilotUserInputCoordinatorTests
         Assert.Contains("is not pending", error.Message);
     }
 
-    private static PatternAgentDefinitionDto CreateAgent(string id, string name)
-    {
-        return new PatternAgentDefinitionDto
-        {
-            Id = id,
-            Name = name,
-            Model = "gpt-5.4",
-            Instructions = "Help with the request.",
-        };
-    }
-
     private static RunTurnCommandDto CreateUserInputCommand()
     {
         return new RunTurnCommandDto
         {
             RequestId = "turn-1",
             SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
+            Workflow = new WorkflowDefinitionDto
             {
-                Id = "pattern-1",
-                Name = "User Input Pattern",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent("agent-1", "Primary"),
-                ],
+                Id = "workflow-1",
+                Name = "User Input Workflow",
+                Graph = new WorkflowGraphDto
+                {
+                    Nodes =
+                    [
+                        new WorkflowNodeDto
+                        {
+                            Id = "agent-1",
+                            Kind = "agent",
+                            Label = "Primary",
+                            Config = new WorkflowNodeConfigDto
+                            {
+                                Kind = "agent",
+                                Id = "agent-1",
+                                Name = "Primary",
+                                Model = "gpt-5.4",
+                                Instructions = "Help with the request.",
+                            },
+                        },
+                    ],
+                },
+                Settings = new WorkflowSettingsDto
+                {
+                    OrchestrationMode = "single",
+                },
             },
         };
     }

sidecar/tests/Aryx.AgentHost.Tests/CopilotWorkflowRunnerTests.cs

@@ -95,23 +95,10 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_FallsBackToStreamingSegmentsWhenWorkflowOutputIsMissing()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-concurrent",
-                Name = "Concurrent Brainstorm",
-                Mode = "concurrent",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-concurrent-architect", name: "Architect"),
-                    CreateAgent(id: "agent-concurrent-implementer", name: "Implementer"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "concurrent",
+            CreateAgent(id: "agent-concurrent-architect", name: "Architect"),
+            CreateAgent(id: "agent-concurrent-implementer", name: "Implementer"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -140,22 +127,9 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_CanonicalizesWorkflowOutputAuthorNames()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-single",
-                Name = "Single Agent",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-single-primary", name: "Primary Agent"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "single",
+            CreateAgent(id: "agent-single-primary", name: "Primary Agent"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -178,22 +152,9 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_UsesFinalAssistantPayloadWhenStreamingTextIsMissing()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-single",
-                Name = "Single Agent",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-single-primary", name: "Primary Agent"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "single",
+            CreateAgent(id: "agent-single-primary", name: "Primary Agent"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -222,24 +183,11 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_PreservesSequentialConversationHistory()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-sequential",
-                Name = "Sequential Trio Review",
-                Mode = "sequential",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-sequential-analyst", name: "Analyst"),
-                    CreateAgent(id: "agent-sequential-builder", name: "Builder"),
-                    CreateAgent(id: "agent-sequential-reviewer", name: "Reviewer"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "sequential",
+            CreateAgent(id: "agent-sequential-analyst", name: "Analyst"),
+            CreateAgent(id: "agent-sequential-builder", name: "Builder"),
+            CreateAgent(id: "agent-sequential-reviewer", name: "Reviewer"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -272,24 +220,11 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_PreservesConcurrentAggregatedResponses()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-concurrent",
-                Name = "Concurrent Brainstorm",
-                Mode = "concurrent",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-concurrent-architect", name: "Architect"),
-                    CreateAgent(id: "agent-concurrent-product", name: "Product"),
-                    CreateAgent(id: "agent-concurrent-implementer", name: "Implementer"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "concurrent",
+            CreateAgent(id: "agent-concurrent-architect", name: "Architect"),
+            CreateAgent(id: "agent-concurrent-product", name: "Product"),
+            CreateAgent(id: "agent-concurrent-implementer", name: "Implementer"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -310,24 +245,11 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_ConcurrentUsesLastStreamedMessagePerAgentForGenericOutput()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-concurrent",
-                Name = "Concurrent Brainstorm",
-                Mode = "concurrent",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-concurrent-architect", name: "Architect"),
-                    CreateAgent(id: "agent-concurrent-product", name: "Product"),
-                    CreateAgent(id: "agent-concurrent-implementer", name: "Implementer"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "concurrent",
+            CreateAgent(id: "agent-concurrent-architect", name: "Architect"),
+            CreateAgent(id: "agent-concurrent-product", name: "Product"),
+            CreateAgent(id: "agent-concurrent-implementer", name: "Implementer"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -379,23 +301,10 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_PreservesGroupChatConversationHistory()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-group-chat",
-                Name = "Collaborative Group Chat",
-                Mode = "group-chat",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-group-writer", name: "Writer"),
-                    CreateAgent(id: "agent-group-reviewer", name: "Reviewer"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "group-chat",
+            CreateAgent(id: "agent-group-writer", name: "Writer"),
+            CreateAgent(id: "agent-group-reviewer", name: "Reviewer"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -428,23 +337,10 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_FallsBackToPositionWhenOutputTextDiffers()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-group-chat",
-                Name = "Collaborative Group Chat",
-                Mode = "group-chat",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-group-writer", name: "Writer"),
-                    CreateAgent(id: "agent-group-reviewer", name: "Reviewer"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "group-chat",
+            CreateAgent(id: "agent-group-writer", name: "Writer"),
+            CreateAgent(id: "agent-group-reviewer", name: "Reviewer"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -482,23 +378,10 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_UsesFallbackAgentForGenericAssistantOutput()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-handoff",
-                Name = "Handoff Support Flow",
-                Mode = "handoff",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-handoff-triage", name: "Triage"),
-                    CreateAgent(id: "agent-handoff-ux", name: "UX Specialist"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "handoff",
+            CreateAgent(id: "agent-handoff-triage", name: "Triage"),
+            CreateAgent(id: "agent-handoff-ux", name: "UX Specialist"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -519,23 +402,10 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_PrefersContentMatchedStreamingSegmentOverPosition()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-handoff",
-                Name = "Handoff Support Flow",
-                Mode = "handoff",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-handoff-triage", name: "Triage"),
-                    CreateAgent(id: "agent-handoff-runtime", name: "Runtime Specialist"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "handoff",
+            CreateAgent(id: "agent-handoff-triage", name: "Triage"),
+            CreateAgent(id: "agent-handoff-runtime", name: "Runtime Specialist"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -560,23 +430,10 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_UsesFallbackAgentForSingleGenericAssistantOutputWithMultipleSegments()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-handoff",
-                Name = "Handoff Support Flow",
-                Mode = "handoff",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-handoff-triage", name: "Triage"),
-                    CreateAgent(id: "agent-handoff-runtime", name: "Runtime Specialist"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "handoff",
+            CreateAgent(id: "agent-handoff-triage", name: "Triage"),
+            CreateAgent(id: "agent-handoff-runtime", name: "Runtime Specialist"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -601,23 +458,10 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public void ProjectCompletedMessages_DropsBlankAssistantOutputMessages()
     {
-        RunTurnCommandDto command = new()
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-handoff",
-                Name = "Handoff Support Flow",
-                Mode = "handoff",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(id: "agent-handoff-triage", name: "Triage"),
-                    CreateAgent(id: "agent-handoff-ux", name: "UX Specialist"),
-                ],
-            },
-        };
+        RunTurnCommandDto command = CreateCommand(
+            "handoff",
+            CreateAgent(id: "agent-handoff-triage", name: "Triage"),
+            CreateAgent(id: "agent-handoff-ux", name: "UX Specialist"));
 
         IReadOnlyList<ChatMessageDto> messages = WorkflowTranscriptProjector.ProjectCompletedMessages(
             command,
@@ -835,7 +679,7 @@ public sealed class CopilotWorkflowRunnerTests
     [Fact]
     public async Task RunTurnAsync_RequestPortWorkflowUsesUserInputBridge()
     {
-        CopilotWorkflowRunner runner = new(new PatternValidator());
+        CopilotWorkflowRunner runner = new(new WorkflowValidator());
         List<UserInputRequestedEventDto> requests = [];
 
         IReadOnlyList<ChatMessageDto> messages = await runner.RunTurnAsync(
@@ -927,6 +771,25 @@ public sealed class CopilotWorkflowRunnerTests
     public async Task HandleWorkflowEventAsync_EmitsWorkflowCheckpointSavedEvent()
     {
         RunTurnCommandDto command = CreateHandoffCommand();
+        command = new RunTurnCommandDto
+        {
+            RequestId = command.RequestId,
+            SessionId = command.SessionId,
+            Workflow = new WorkflowDefinitionDto
+            {
+                Id = command.Workflow.Id,
+                Name = command.Workflow.Name,
+                Graph = command.Workflow.Graph,
+                Settings = new WorkflowSettingsDto
+                {
+                    OrchestrationMode = command.Workflow.Settings.OrchestrationMode,
+                    Checkpointing = new WorkflowCheckpointSettingsDto
+                    {
+                        Enabled = true,
+                    },
+                },
+            },
+        };
         CopilotTurnExecutionState state = new(command);
         List<WorkflowCheckpointSavedEventDto> checkpoints = [];
 
@@ -1831,7 +1694,7 @@ public sealed class CopilotWorkflowRunnerTests
 
         Task<PermissionRequestResult> pending = coordinator.RequestApprovalAsync(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             new PermissionRequestCustomTool
             {
                 Kind = "custom tool",
@@ -1875,7 +1738,7 @@ public sealed class CopilotWorkflowRunnerTests
 
         Task<PermissionRequestResult> pending = coordinator.RequestApprovalAsync(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             new PermissionRequestWrite
             {
                 Kind = "write",
@@ -1938,7 +1801,7 @@ public sealed class CopilotWorkflowRunnerTests
 
         PermissionRequestResult result = await coordinator.RequestApprovalAsync(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             new PermissionRequestCustomTool
             {
                 Kind = "custom tool",
@@ -1972,7 +1835,7 @@ public sealed class CopilotWorkflowRunnerTests
 
         PermissionRequestResult result = await coordinator.RequestApprovalAsync(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             new PermissionRequestHook
             {
                 Kind = "hook",
@@ -2007,7 +1870,7 @@ public sealed class CopilotWorkflowRunnerTests
 
         Task<PermissionRequestResult> firstPending = coordinator.RequestApprovalAsync(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             new PermissionRequestRead
             {
                 Kind = "read",
@@ -2048,7 +1911,7 @@ public sealed class CopilotWorkflowRunnerTests
         bool sawSecondApproval = false;
         PermissionRequestResult secondResult = await coordinator.RequestApprovalAsync(
             command,
-            command.Pattern.Agents[0],
+            command.Workflow.GetAgentNodes()[0],
             new PermissionRequestRead
             {
                 Kind = "read",
@@ -2084,7 +1947,7 @@ public sealed class CopilotWorkflowRunnerTests
 
         Task<PermissionRequestResult> firstPending = coordinator.RequestApprovalAsync(
             firstCommand,
-            firstCommand.Pattern.Agents[0],
+            firstCommand.Workflow.GetAgentNodes()[0],
             new PermissionRequestRead
             {
                 Kind = "read",
@@ -2124,7 +1987,7 @@ public sealed class CopilotWorkflowRunnerTests
         RunTurnCommandDto secondCommand = CreateApprovalCommand(requestId: "turn-2");
         Task<PermissionRequestResult> secondPending = coordinator.RequestApprovalAsync(
             secondCommand,
-            secondCommand.Pattern.Agents[0],
+            secondCommand.Workflow.GetAgentNodes()[0],
             new PermissionRequestRead
             {
                 Kind = "read",
@@ -2179,38 +2042,56 @@ public sealed class CopilotWorkflowRunnerTests
         Assert.Contains("is not pending", error.Message);
     }
 
-    private static PatternAgentDefinitionDto CreateAgent(string id, string name)
+    private static WorkflowNodeDto CreateAgent(string id, string name)
     {
-        return new PatternAgentDefinitionDto
+        return new WorkflowNodeDto
         {
             Id = id,
-            Name = name,
-            Model = "gpt-5.4",
-            Instructions = "Help with the request.",
+            Kind = "agent",
+            Label = name,
+            Config = new WorkflowNodeConfigDto
+            {
+                Kind = "agent",
+                Id = id,
+                Name = name,
+                Model = "gpt-5.4",
+                Instructions = "Help with the request.",
+            },
         };
     }
 
-    private static RunTurnCommandDto CreateHandoffCommand()
+    private static RunTurnCommandDto CreateCommand(
+        string orchestrationMode,
+        params WorkflowNodeDto[] agents)
     {
         return new RunTurnCommandDto
         {
             RequestId = "turn-1",
             SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
+            Workflow = new WorkflowDefinitionDto
             {
-                Id = "pattern-handoff",
-                Name = "Handoff Flow",
-                Mode = "handoff",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent("agent-handoff-triage", "Triage"),
-                    CreateAgent("agent-handoff-ux", "UX Specialist"),
-                ],
+                Id = $"workflow-{orchestrationMode}",
+                Name = $"Workflow {orchestrationMode}",
+                Graph = new WorkflowGraphDto
+                {
+                    Nodes = [.. agents],
+                },
+                Settings = new WorkflowSettingsDto
+                {
+                    OrchestrationMode = orchestrationMode,
+                },
             },
         };
     }
 
+    private static RunTurnCommandDto CreateHandoffCommand()
+    {
+        return CreateCommand(
+            "handoff",
+            CreateAgent("agent-handoff-triage", "Triage"),
+            CreateAgent("agent-handoff-ux", "UX Specialist"));
+    }
+
     private static RequestInfoEvent CreateRequestInfoEvent(object payload)
     {
         RequestPort port = RequestPort.Create<object, object>("test-port");
@@ -2253,30 +2134,35 @@ public sealed class CopilotWorkflowRunnerTests
                 {
                     McpServers = [.. mcpServers],
                 },
-            Pattern = new PatternDefinitionDto
+            Workflow = new WorkflowDefinitionDto
             {
-                Id = "pattern-1",
-                Name = "Approval Pattern",
-                Mode = "single",
-                Availability = "available",
-                ApprovalPolicy = new ApprovalPolicyDto
+                Id = "workflow-1",
+                Name = "Approval Workflow",
+                Graph = new WorkflowGraphDto
                 {
-                    Rules =
+                    Nodes =
                     [
-                        new ApprovalCheckpointRuleDto
-                        {
-                            Kind = "tool-call",
-                            AgentIds = ["agent-1"],
-                        },
+                        CreateAgent("agent-1", "Primary"),
                     ],
-                    AutoApprovedToolNames = autoApprovedToolNames is null
-                        ? ["web_fetch"]
-                        : [.. autoApprovedToolNames],
                 },
-                Agents =
-                [
-                    CreateAgent("agent-1", "Primary"),
-                ],
+                Settings = new WorkflowSettingsDto
+                {
+                    OrchestrationMode = "single",
+                    ApprovalPolicy = new ApprovalPolicyDto
+                    {
+                        Rules =
+                        [
+                            new ApprovalCheckpointRuleDto
+                            {
+                                Kind = "tool-call",
+                                AgentIds = ["agent-1"],
+                            },
+                        ],
+                        AutoApprovedToolNames = autoApprovedToolNames is null
+                            ? ["web_fetch"]
+                            : [.. autoApprovedToolNames],
+                    },
+                },
             },
         };
     }
@@ -2288,14 +2174,6 @@ public sealed class CopilotWorkflowRunnerTests
             RequestId = "turn-request-port",
             SessionId = "session-request-port",
             ProjectPath = "c:\\workspace\\personal\\projects\\aryx.worktrees\\copilot-powerful-vulture",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-request-port",
-                Name = "Request Port Pattern",
-                Mode = "single",
-                Availability = "available",
-                Agents = [],
-            },
             Messages =
             [
                 new ChatMessageDto
@@ -2407,3 +2285,4 @@ public sealed class CopilotWorkflowRunnerTests
         }
     }
 }
+

sidecar/tests/Aryx.AgentHost.Tests/HandoffWorkflowGuidanceTests.cs

@@ -23,13 +23,20 @@ public sealed class HandoffWorkflowGuidanceTests
     [Fact]
     public void CreateForwardReason_UsesTargetSpecialtyAndOwnership()
     {
-        PatternAgentDefinitionDto specialist = new()
+        WorkflowNodeDto specialist = new()
         {
             Id = "agent-handoff-ux",
-            Name = "UX Specialist",
-            Description = "Handles user experience questions.",
-            Instructions = "Focus on UX.",
-            Model = "claude-opus-4.5",
+            Kind = "agent",
+            Label = "UX Specialist",
+            Config = new WorkflowNodeConfigDto
+            {
+                Kind = "agent",
+                Id = "agent-handoff-ux",
+                Name = "UX Specialist",
+                Description = "Handles user experience questions.",
+                Instructions = "Focus on UX.",
+                Model = "claude-opus-4.5",
+            },
         };
 
         string reason = HandoffWorkflowGuidance.CreateForwardReason(specialist);
@@ -42,13 +49,20 @@ public sealed class HandoffWorkflowGuidanceTests
     [Fact]
     public void CreateReturnReason_RestrictsReturnToReroutingCases()
     {
-        PatternAgentDefinitionDto triage = new()
+        WorkflowNodeDto triage = new()
         {
             Id = "agent-handoff-triage",
-            Name = "Triage",
-            Description = "Routes the request to the right specialist.",
-            Instructions = "Triages requests.",
-            Model = "gpt-5.4",
+            Kind = "agent",
+            Label = "Triage",
+            Config = new WorkflowNodeConfigDto
+            {
+                Kind = "agent",
+                Id = "agent-handoff-triage",
+                Name = "Triage",
+                Description = "Routes the request to the right specialist.",
+                Instructions = "Triages requests.",
+                Model = "gpt-5.4",
+            },
         };
 
         string reason = HandoffWorkflowGuidance.CreateReturnReason(triage);

sidecar/tests/Aryx.AgentHost.Tests/PatternGraphResolverTests.cs

@@ -1,127 +0,0 @@
-using Aryx.AgentHost.Contracts;
-using Aryx.AgentHost.Services;
-
-namespace Aryx.AgentHost.Tests;
-
-public sealed class PatternGraphResolverTests
-{
-    [Fact]
-    public void ResolveOrderedAgentIds_UsesSequentialGraphPath()
-    {
-        PatternDefinitionDto pattern = CreatePattern(
-            "sequential",
-            [
-                CreateAgent("agent-1", "Analyst"),
-                CreateAgent("agent-2", "Builder"),
-                CreateAgent("agent-3", "Reviewer"),
-            ],
-            new PatternGraphDto
-            {
-                Nodes =
-                [
-                    CreateSystemNode("system-user-input", "user-input"),
-                    CreateAgentNode("agent-1", 0),
-                    CreateAgentNode("agent-2", 1),
-                    CreateAgentNode("agent-3", 2),
-                    CreateSystemNode("system-user-output", "user-output"),
-                ],
-                Edges =
-                [
-                    CreateEdge("system-user-input", "agent-node-agent-3"),
-                    CreateEdge("agent-node-agent-3", "agent-node-agent-1"),
-                    CreateEdge("agent-node-agent-1", "agent-node-agent-2"),
-                    CreateEdge("agent-node-agent-2", "system-user-output"),
-                ],
-            });
-
-        IReadOnlyList<string> orderedAgentIds = PatternGraphResolver.ResolveOrderedAgentIds(pattern);
-
-        Assert.Equal(["agent-3", "agent-1", "agent-2"], orderedAgentIds);
-    }
-
-    [Fact]
-    public void ResolveHandoff_UsesExplicitEntryAndRoutes()
-    {
-        PatternDefinitionDto pattern = CreatePattern(
-            "handoff",
-            [
-                CreateAgent("agent-1", "Triage"),
-                CreateAgent("agent-2", "UX"),
-                CreateAgent("agent-3", "Runtime"),
-            ],
-            new PatternGraphDto
-            {
-                Nodes =
-                [
-                    CreateSystemNode("system-user-input", "user-input"),
-                    CreateSystemNode("system-user-output", "user-output"),
-                    CreateAgentNode("agent-1", 0),
-                    CreateAgentNode("agent-2", 1),
-                    CreateAgentNode("agent-3", 2),
-                ],
-                Edges =
-                [
-                    CreateEdge("system-user-input", "agent-node-agent-3"),
-                    CreateEdge("agent-node-agent-3", "agent-node-agent-2"),
-                    CreateEdge("agent-node-agent-2", "agent-node-agent-1"),
-                    CreateEdge("agent-node-agent-2", "system-user-output"),
-                ],
-            });
-
-        PatternHandoffTopology topology = PatternGraphResolver.ResolveHandoff(pattern);
-
-        Assert.Equal("agent-3", topology.EntryAgentId);
-        Assert.Contains(new PatternHandoffRoute("agent-3", "agent-2"), topology.Routes);
-        Assert.Contains(new PatternHandoffRoute("agent-2", "agent-1"), topology.Routes);
-        Assert.DoesNotContain(new PatternHandoffRoute("agent-1", "agent-2"), topology.Routes);
-    }
-
-    private static PatternDefinitionDto CreatePattern(
-        string mode,
-        IReadOnlyList<PatternAgentDefinitionDto> agents,
-        PatternGraphDto graph)
-        => new()
-        {
-            Id = $"{mode}-pattern",
-            Name = "Pattern",
-            Mode = mode,
-            Availability = "available",
-            Agents = agents,
-            Graph = graph,
-        };
-
-    private static PatternAgentDefinitionDto CreateAgent(string id, string name)
-        => new()
-        {
-            Id = id,
-            Name = name,
-            Model = "gpt-5.4",
-            Instructions = "Help with the user's request.",
-        };
-
-    private static PatternGraphNodeDto CreateSystemNode(string id, string kind)
-        => new()
-        {
-            Id = id,
-            Kind = kind,
-            Position = new PatternGraphPositionDto(),
-        };
-
-    private static PatternGraphNodeDto CreateAgentNode(string agentId, int order)
-        => new()
-        {
-            Id = $"agent-node-{agentId}",
-            Kind = "agent",
-            AgentId = agentId,
-            Order = order,
-            Position = new PatternGraphPositionDto(),
-        };
-
-    private static PatternGraphEdgeDto CreateEdge(string source, string target)
-        => new()
-        {
-            Id = $"edge-{source}-to-{target}",
-            Source = source,
-            Target = target,
-        };
-}

sidecar/tests/Aryx.AgentHost.Tests/SidecarProtocolHostTests.cs

@@ -62,52 +62,6 @@ public sealed class SidecarProtocolHostTests
             });
     }
 
-    [Fact]
-    public async Task ValidatePatternCommand_ReturnsIssuesAndCompletion()
-    {
-        IReadOnlyList<JsonElement> events = await RunHostAsync(new ValidatePatternCommandDto
-        {
-            Type = "validate-pattern",
-            RequestId = "validate-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "single-pattern",
-                Name = "",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(),
-                    CreateAgent(id: "agent-2", name: "Reviewer", model: ""),
-                ],
-            },
-        });
-
-        Assert.Collection(
-            events,
-            validationEvent =>
-            {
-                Assert.Equal("pattern-validation", validationEvent.GetProperty("type").GetString());
-                Assert.Equal("validate-1", validationEvent.GetProperty("requestId").GetString());
-
-                JsonElement[] issues = validationEvent.GetProperty("issues").EnumerateArray().ToArray();
-                Assert.Contains(issues, issue =>
-                    issue.GetProperty("field").GetString() == "name"
-                    && issue.GetProperty("message").GetString() == "Pattern name is required.");
-                Assert.Contains(issues, issue =>
-                    issue.GetProperty("field").GetString() == "agents"
-                    && issue.GetProperty("message").GetString() == "Single-agent chat requires exactly one agent.");
-                Assert.Contains(issues, issue =>
-                    issue.GetProperty("field").GetString() == "agents.model"
-                    && issue.GetProperty("message").GetString() == "Agent \"Reviewer\" requires a model identifier.");
-            },
-            completionEvent =>
-            {
-                Assert.Equal("command-complete", completionEvent.GetProperty("type").GetString());
-                Assert.Equal("validate-1", completionEvent.GetProperty("requestId").GetString());
-            });
-    }
-
     [Fact]
     public async Task ValidateWorkflowCommand_ReturnsIssuesAndCompletion()
     {
@@ -182,7 +136,7 @@ public sealed class SidecarProtocolHostTests
     public async Task RunTurnCommand_ReturnsActivityEventsAndCompletion()
     {
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) =>
             {
                 await onActivity(new AgentActivityEventDto
@@ -230,37 +184,7 @@ public sealed class SidecarProtocolHostTests
                 ];
             }));
 
-        IReadOnlyList<JsonElement> events = await RunHostAsync(
-            new RunTurnCommandDto
-            {
-                Type = "run-turn",
-                RequestId = "turn-1",
-                SessionId = "session-1",
-                ProjectPath = "C:\\workspace\\project",
-                Pattern = new PatternDefinitionDto
-                {
-                    Id = "pattern-1",
-                    Name = "Single Agent",
-                    Mode = "single",
-                    Availability = "available",
-                    Agents =
-                    [
-                        CreateAgent(name: "Primary"),
-                    ],
-                },
-                Messages =
-                [
-                    new ChatMessageDto
-                    {
-                        Id = "user-1",
-                        Role = "user",
-                        AuthorName = "You",
-                        Content = "Hello",
-                        CreatedAt = "2026-01-01T00:00:00.0000000Z",
-                    },
-                ],
-            },
-            host);
+        IReadOnlyList<JsonElement> events = await RunHostAsync(CreateRunTurnCommand(), host);
 
         Assert.Collection(
             events,
@@ -306,7 +230,7 @@ public sealed class SidecarProtocolHostTests
     public async Task RunTurnCommand_ReturnsWorkflowDiagnosticEventsAndCompletion()
     {
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) =>
             {
                 await onActivity(new WorkflowDiagnosticEventDto
@@ -327,25 +251,7 @@ public sealed class SidecarProtocolHostTests
             }));
 
         IReadOnlyList<JsonElement> events = await RunHostAsync(
-            new RunTurnCommandDto
-            {
-                Type = "run-turn",
-                RequestId = "turn-diagnostic",
-                SessionId = "session-1",
-                ProjectPath = "C:\\workspace\\project",
-                Pattern = new PatternDefinitionDto
-                {
-                    Id = "pattern-1",
-                    Name = "Single Agent",
-                    Mode = "single",
-                    Availability = "available",
-                    Agents =
-                    [
-                        CreateAgent(name: "Primary"),
-                    ],
-                },
-                Messages = [],
-            },
+            CreateRunTurnCommand(requestId: "turn-diagnostic", messages: []),
             host);
 
         Assert.Collection(
@@ -378,7 +284,7 @@ public sealed class SidecarProtocolHostTests
     {
         string? capturedMode = null;
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) =>
             {
                 capturedMode = command.Mode;
@@ -386,25 +292,7 @@ public sealed class SidecarProtocolHostTests
             }));
 
         await RunHostAsync(
-            new RunTurnCommandDto
-            {
-                Type = "run-turn",
-                RequestId = "turn-plan",
-                SessionId = "session-1",
-                ProjectPath = "C:\\workspace\\project",
-                Mode = "plan",
-                Pattern = new PatternDefinitionDto
-                {
-                    Id = "pattern-1",
-                    Name = "Single Agent",
-                    Mode = "single",
-                    Availability = "available",
-                    Agents =
-                    [
-                        CreateAgent(name: "Primary"),
-                    ],
-                },
-            },
+            CreateRunTurnCommand(requestId: "turn-plan", interactionMode: "plan"),
             host);
 
         Assert.Equal("plan", capturedMode);
@@ -414,7 +302,7 @@ public sealed class SidecarProtocolHostTests
     public async Task RunTurnCommand_ReturnsApprovalEvents()
     {
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) =>
             {
                 await onApproval(new ApprovalRequestedEventDto
@@ -441,24 +329,7 @@ public sealed class SidecarProtocolHostTests
             }));
 
         IReadOnlyList<JsonElement> events = await RunHostAsync(
-            new RunTurnCommandDto
-            {
-                Type = "run-turn",
-                RequestId = "turn-approval",
-                SessionId = "session-1",
-                ProjectPath = "C:\\workspace\\project",
-                Pattern = new PatternDefinitionDto
-                {
-                    Id = "pattern-1",
-                    Name = "Single Agent",
-                    Mode = "single",
-                    Availability = "available",
-                    Agents =
-                    [
-                        CreateAgent(name: "Primary"),
-                    ],
-                },
-            },
+            CreateRunTurnCommand(requestId: "turn-approval"),
             host);
 
         Assert.Collection(
@@ -492,7 +363,7 @@ public sealed class SidecarProtocolHostTests
     public async Task RunTurnCommand_ReturnsUserInputEvents()
     {
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) =>
             {
                 await onUserInput(new UserInputRequestedEventDto
@@ -512,24 +383,7 @@ public sealed class SidecarProtocolHostTests
             }));
 
         IReadOnlyList<JsonElement> events = await RunHostAsync(
-            new RunTurnCommandDto
-            {
-                Type = "run-turn",
-                RequestId = "turn-user-input",
-                SessionId = "session-1",
-                ProjectPath = "C:\\workspace\\project",
-                Pattern = new PatternDefinitionDto
-                {
-                    Id = "pattern-1",
-                    Name = "Single Agent",
-                    Mode = "single",
-                    Availability = "available",
-                    Agents =
-                    [
-                        CreateAgent(name: "Primary"),
-                    ],
-                },
-            },
+            CreateRunTurnCommand(requestId: "turn-user-input"),
             host);
 
         Assert.Collection(
@@ -565,7 +419,7 @@ public sealed class SidecarProtocolHostTests
     public async Task RunTurnCommand_ReturnsMcpOauthRequiredEvents()
     {
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) =>
             {
                 await onMcpOAuthRequired(new McpOauthRequiredEventDto
@@ -623,7 +477,7 @@ public sealed class SidecarProtocolHostTests
     public async Task RunTurnCommand_ReturnsExitPlanModeEvents()
     {
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) =>
             {
                 await onExitPlanMode(new ExitPlanModeRequestedEventDto
@@ -644,25 +498,7 @@ public sealed class SidecarProtocolHostTests
             }));
 
         IReadOnlyList<JsonElement> events = await RunHostAsync(
-            new RunTurnCommandDto
-            {
-                Type = "run-turn",
-                RequestId = "turn-plan-mode",
-                SessionId = "session-1",
-                ProjectPath = "C:\\workspace\\project",
-                Mode = "plan",
-                Pattern = new PatternDefinitionDto
-                {
-                    Id = "pattern-1",
-                    Name = "Single Agent",
-                    Mode = "single",
-                    Availability = "available",
-                    Agents =
-                    [
-                        CreateAgent(name: "Primary"),
-                    ],
-                },
-            },
+            CreateRunTurnCommand(requestId: "turn-plan-mode", interactionMode: "plan"),
             host);
 
         Assert.Collection(
@@ -698,7 +534,7 @@ public sealed class SidecarProtocolHostTests
     public async Task CancelTurnCommand_CancelsInProgressTurnAndCompletesBothCommands()
     {
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) =>
             {
                 await Task.Delay(Timeout.Infinite, cancellationToken);
@@ -746,7 +582,7 @@ public sealed class SidecarProtocolHostTests
     public async Task CancelTurnCommand_AfterTurnCompletion_IsNoOp()
     {
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) => []));
 
         await RunHostAsync(CreateRunTurnCommand(requestId: "turn-completed"), host);
@@ -768,7 +604,7 @@ public sealed class SidecarProtocolHostTests
     {
         ResolveApprovalCommandDto? captured = null;
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(
                 handler: async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) => [],
                 resolveApprovalHandler: (command, cancellationToken) =>
@@ -801,7 +637,7 @@ public sealed class SidecarProtocolHostTests
     {
         ResolveUserInputCommandDto? captured = null;
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             new FakeWorkflowRunner(
                 handler: async (command, onDelta, onActivity, onApproval, onUserInput, onMcpOAuthRequired, onExitPlanMode, cancellationToken) => [],
                 resolveUserInputHandler: (command, cancellationToken) =>
@@ -925,7 +761,7 @@ public sealed class SidecarProtocolHostTests
     public async Task ListSessionsCommand_ReturnsSessionsListedEvent()
     {
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             sessionManager: new FakeSessionManager
             {
                 Sessions =
@@ -972,7 +808,7 @@ public sealed class SidecarProtocolHostTests
             ],
         };
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             sessionManager: sessionManager);
 
         IReadOnlyList<JsonElement> events = await RunHostAsync(
@@ -995,7 +831,7 @@ public sealed class SidecarProtocolHostTests
     public async Task GetQuotaCommand_ReturnsQuotaResultEvent()
     {
         SidecarProtocolHost host = new(
-            new PatternValidator(),
+            new WorkflowValidator(),
             sessionManager: new FakeSessionManager
             {
                 QuotaSnapshots = new Dictionary<string, QuotaSnapshotDto>(StringComparer.Ordinal)
@@ -1037,7 +873,7 @@ public sealed class SidecarProtocolHostTests
             await Task.Delay(Timeout.InfiniteTimeSpan, cancellationToken);
             return [];
         });
-        SidecarProtocolHost host = new(new PatternValidator(), runner);
+        SidecarProtocolHost host = new(new WorkflowValidator(), runner);
 
         IReadOnlyList<JsonElement> events = await RunHostAsync(
         [
@@ -1098,7 +934,7 @@ public sealed class SidecarProtocolHostTests
     private static SidecarProtocolHost CreateHostForTests()
     {
         return new SidecarProtocolHost(
-            new PatternValidator(),
+            new WorkflowValidator(),
             capabilitiesProvider: _ => Task.FromResult(new SidecarCapabilitiesDto
             {
                 Modes = new Dictionary<string, SidecarModeCapabilityDto>(StringComparer.OrdinalIgnoreCase)
@@ -1176,24 +1012,35 @@ public sealed class SidecarProtocolHostTests
         return events;
     }
 
-    private static PatternAgentDefinitionDto CreateAgent(
+    private static WorkflowNodeDto CreateAgent(
         string id = "agent-1",
         string name = "Primary",
         string model = "gpt-5.4",
         string instructions = "Help with the user's request.")
     {
-        return new PatternAgentDefinitionDto
+        return new WorkflowNodeDto
         {
             Id = id,
-            Name = name,
-            Model = model,
-            Instructions = instructions,
+            Kind = "agent",
+            Label = name,
+            Config = new WorkflowNodeConfigDto
+            {
+                Kind = "agent",
+                Id = id,
+                Name = name,
+                Model = model,
+                Instructions = instructions,
+            },
         };
     }
 
     private static RunTurnCommandDto CreateRunTurnCommand(
         string requestId = "turn-1",
-        string sessionId = "session-1")
+        string sessionId = "session-1",
+        string mode = "single",
+        string interactionMode = "interactive",
+        IReadOnlyList<WorkflowNodeDto>? agents = null,
+        IReadOnlyList<ChatMessageDto>? messages = null)
     {
         return new RunTurnCommandDto
         {
@@ -1201,18 +1048,9 @@ public sealed class SidecarProtocolHostTests
             RequestId = requestId,
             SessionId = sessionId,
             ProjectPath = "C:\\workspace\\project",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-1",
-                Name = "Single Agent",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent(name: "Primary"),
-                ],
-            },
-            Messages =
+            Mode = interactionMode,
+            Workflow = CreateWorkflow(mode, agents),
+            Messages = messages ??
             [
                 new ChatMessageDto
                 {
@@ -1226,6 +1064,25 @@ public sealed class SidecarProtocolHostTests
         };
     }
 
+    private static WorkflowDefinitionDto CreateWorkflow(
+        string mode = "single",
+        IReadOnlyList<WorkflowNodeDto>? agents = null)
+    {
+        return new WorkflowDefinitionDto
+        {
+            Id = $"workflow-{mode}",
+            Name = "Single Agent",
+            Graph = new WorkflowGraphDto
+            {
+                Nodes = [.. agents ?? [CreateAgent(name: "Primary")]],
+            },
+            Settings = new WorkflowSettingsDto
+            {
+                OrchestrationMode = mode,
+            },
+        };
+    }
+
     private sealed class FakeWorkflowRunner : ITurnWorkflowRunner
     {
         private readonly Func<
@@ -1325,3 +1182,4 @@ public sealed class SidecarProtocolHostTests
         }
     }
 }
+

sidecar/tests/Aryx.AgentHost.Tests/UnitTest1.cs

@@ -1,169 +0,0 @@
-using Aryx.AgentHost.Contracts;
-using Aryx.AgentHost.Services;
-
-namespace Aryx.AgentHost.Tests;
-
-public sealed class PatternValidatorTests
-{
-    private readonly PatternValidator _validator = new();
-
-    [Fact]
-    public void SingleAgentPattern_WithExactlyOneAgent_IsValid()
-    {
-        IReadOnlyList<PatternValidationIssueDto> issues = _validator.Validate(
-            CreatePattern(
-                "single",
-                [CreateAgent()]));
-
-        Assert.Empty(issues);
-    }
-
-    [Fact]
-    public void HandoffPattern_WithSingleAgent_IsReportedAsInvalid()
-    {
-        IReadOnlyList<PatternValidationIssueDto> issues = _validator.Validate(
-            CreatePattern(
-                "handoff",
-                [CreateAgent()]));
-
-        Assert.Contains(issues, issue =>
-            issue.Field == "agents"
-            && issue.Message == "Handoff orchestration requires at least two agents.");
-    }
-
-    [Fact]
-    public void AgentWithoutModel_IsReportedAsInvalid()
-    {
-        IReadOnlyList<PatternValidationIssueDto> issues = _validator.Validate(
-            CreatePattern(
-                "sequential",
-                [
-                    CreateAgent(model: ""),
-                    CreateAgent(id: "agent-2", name: "Reviewer"),
-                ]));
-
-        Assert.Contains(issues, issue =>
-            issue.Field == "agents.model"
-            && issue.Message == "Agent \"Primary\" requires a model identifier.");
-    }
-
-    [Fact]
-    public void MagenticPattern_IsReportedAsUnavailable()
-    {
-        IReadOnlyList<PatternValidationIssueDto> issues = _validator.Validate(
-            CreatePattern(
-                "magentic",
-                [
-                    CreateAgent(id: "agent-1", name: "Planner", instructions: "Plan the task."),
-                    CreateAgent(
-                        id: "agent-2",
-                        name: "Specialist",
-                        model: "claude-opus-4.5",
-                        instructions: "Complete the task."),
-                ],
-                availability: "unavailable",
-                unavailabilityReason: "Unsupported in C#.",
-                name: "Magentic"));
-
-        Assert.Contains(issues, issue =>
-            issue.Field == "availability"
-            && issue.Message.Contains("Unsupported", StringComparison.OrdinalIgnoreCase));
-        Assert.Contains(issues, issue =>
-            issue.Field == "mode"
-            && issue.Message.Contains("Unsupported", StringComparison.OrdinalIgnoreCase));
-    }
-
-    [Fact]
-    public void SequentialPattern_WithBranchedGraph_IsReportedAsInvalid()
-    {
-        IReadOnlyList<PatternValidationIssueDto> issues = _validator.Validate(
-            CreatePattern(
-                "sequential",
-                [
-                    CreateAgent(id: "agent-1", name: "Analyst"),
-                    CreateAgent(id: "agent-2", name: "Builder"),
-                ],
-                graph: new PatternGraphDto
-                {
-                    Nodes =
-                    [
-                        CreateSystemNode("system-user-input", "user-input"),
-                        CreateAgentNode("agent-1", 0),
-                        CreateAgentNode("agent-2", 1),
-                        CreateSystemNode("system-user-output", "user-output"),
-                    ],
-                    Edges =
-                    [
-                        CreateEdge("system-user-input", "agent-node-agent-1"),
-                        CreateEdge("system-user-input", "agent-node-agent-2"),
-                        CreateEdge("agent-node-agent-1", "agent-node-agent-2"),
-                        CreateEdge("agent-node-agent-2", "system-user-output"),
-                    ],
-                }));
-
-        Assert.Contains(issues, issue =>
-            issue.Field == "graph"
-            && issue.Message.Contains("single path", StringComparison.OrdinalIgnoreCase));
-    }
-
-    private static PatternDefinitionDto CreatePattern(
-        string mode,
-        IReadOnlyList<PatternAgentDefinitionDto> agents,
-        string availability = "available",
-        string? unavailabilityReason = null,
-        string name = "Pattern",
-        PatternGraphDto? graph = null)
-    {
-        return new PatternDefinitionDto
-        {
-            Id = $"{mode}-pattern",
-            Name = name,
-            Mode = mode,
-            Availability = availability,
-            UnavailabilityReason = unavailabilityReason,
-            Agents = agents,
-            Graph = graph,
-        };
-    }
-
-    private static PatternAgentDefinitionDto CreateAgent(
-        string id = "agent-1",
-        string name = "Primary",
-        string model = "gpt-5.4",
-        string instructions = "Help with the user's request.")
-    {
-        return new PatternAgentDefinitionDto
-        {
-            Id = id,
-            Name = name,
-            Model = model,
-            Instructions = instructions,
-        };
-    }
-
-    private static PatternGraphNodeDto CreateSystemNode(string id, string kind)
-        => new()
-        {
-            Id = id,
-            Kind = kind,
-            Position = new PatternGraphPositionDto(),
-        };
-
-    private static PatternGraphNodeDto CreateAgentNode(string agentId, int order)
-        => new()
-        {
-            Id = $"agent-node-{agentId}",
-            Kind = "agent",
-            AgentId = agentId,
-            Order = order,
-            Position = new PatternGraphPositionDto(),
-        };
-
-    private static PatternGraphEdgeDto CreateEdge(string source, string target)
-        => new()
-        {
-            Id = $"edge-{source}-to-{target}",
-            Source = source,
-            Target = target,
-        };
-}

sidecar/tests/Aryx.AgentHost.Tests/WorkflowRequestInfoInterpreterTests.cs

@@ -186,54 +186,52 @@ public sealed class WorkflowRequestInfoInterpreterTests
     }
 
     private static RunTurnCommandDto CreateSingleAgentCommand()
-    {
-        return new RunTurnCommandDto
-        {
-            RequestId = "turn-1",
-            SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
-            {
-                Id = "pattern-single",
-                Name = "Single Agent",
-                Mode = "single",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent("agent-1", "Primary"),
-                ],
-            },
-        };
-    }
+        => CreateCommand("single", [CreateAgent("agent-1", "Primary")]);
 
     private static RunTurnCommandDto CreateHandoffCommand()
+        => CreateCommand("handoff",
+        [
+            CreateAgent("agent-handoff-triage", "Triage"),
+            CreateAgent("agent-handoff-ux", "UX Specialist"),
+        ]);
+
+    private static RunTurnCommandDto CreateCommand(string orchestrationMode, IReadOnlyList<WorkflowNodeDto> agents)
     {
         return new RunTurnCommandDto
         {
             RequestId = "turn-1",
             SessionId = "session-1",
-            Pattern = new PatternDefinitionDto
+            Workflow = new WorkflowDefinitionDto
             {
-                Id = "pattern-handoff",
-                Name = "Handoff Flow",
-                Mode = "handoff",
-                Availability = "available",
-                Agents =
-                [
-                    CreateAgent("agent-handoff-triage", "Triage"),
-                    CreateAgent("agent-handoff-ux", "UX Specialist"),
-                ],
+                Id = $"{orchestrationMode}-workflow",
+                Name = "Workflow",
+                Graph = new WorkflowGraphDto
+                {
+                    Nodes = [.. agents],
+                },
+                Settings = new WorkflowSettingsDto
+                {
+                    OrchestrationMode = orchestrationMode,
+                },
             },
         };
     }
 
-    private static PatternAgentDefinitionDto CreateAgent(string id, string name)
+    private static WorkflowNodeDto CreateAgent(string id, string name)
     {
-        return new PatternAgentDefinitionDto
+        return new WorkflowNodeDto
         {
             Id = id,
-            Name = name,
-            Model = "gpt-5.4",
-            Instructions = "Help with the request.",
+            Kind = "agent",
+            Label = name,
+            Config = new WorkflowNodeConfigDto
+            {
+                Kind = "agent",
+                Id = id,
+                Name = name,
+                Model = "gpt-5.4",
+                Instructions = "Help with the request.",
+            },
         };
     }
 

sidecar/tests/Aryx.AgentHost.Tests/WorkflowRunnerTests.cs

@@ -15,7 +15,6 @@ public sealed class WorkflowRunnerTests
         WorkflowRunner runner = new();
         Workflow workflow = runner.BuildWorkflow(
             CreateSubworkflowParent(inlineWorkflow: CreateAgentWorkflow("child-inline", "agent-child")),
-            CreatePattern("agent-child"),
             [CreateChatClientAgent("agent-child", "Child Agent")]);
 
         ProtocolDescriptor descriptor = await workflow.DescribeProtocolAsync();
@@ -30,7 +29,6 @@ public sealed class WorkflowRunnerTests
         WorkflowDefinitionDto childWorkflow = CreateAgentWorkflow("child-ref", "agent-child");
         Workflow workflow = runner.BuildWorkflow(
             CreateSubworkflowParent(workflowId: childWorkflow.Id),
-            CreatePattern("agent-child"),
             [CreateChatClientAgent("agent-child", "Child Agent")],
             [childWorkflow]);
 
@@ -46,7 +44,6 @@ public sealed class WorkflowRunnerTests
 
         InvalidOperationException error = Assert.Throws<InvalidOperationException>(() => runner.BuildWorkflow(
             CreateSubworkflowParent(workflowId: "missing-child"),
-            CreatePattern("agent-child"),
             [CreateChatClientAgent("agent-child", "Child Agent")],
             []));
 
@@ -65,7 +62,6 @@ public sealed class WorkflowRunnerTests
                     Kind = "code-executor",
                     Implementation = "return-text:done",
                 }),
-            CreateEmptyPattern(),
             []);
 
         List<ChatMessage> output = await RunWorkflowToOutputAsync(workflow);
@@ -81,7 +77,6 @@ public sealed class WorkflowRunnerTests
         WorkflowRunner runner = new();
         Workflow workflow = runner.BuildWorkflow(
             CreateStatefulFunctionWorkflow(),
-            CreateEmptyPattern(),
             []);
 
         List<ChatMessage> output = await RunWorkflowToOutputAsync(workflow);
@@ -105,7 +100,6 @@ public sealed class WorkflowRunnerTests
                     ResponseType = "string",
                     Prompt = "Approve the workflow?",
                 }),
-            CreateEmptyPattern(),
             []);
 
         ChatMessage[] input =
@@ -153,33 +147,11 @@ public sealed class WorkflowRunnerTests
                     Kind = "function-executor",
                     FunctionRef = "missing-function",
                 }),
-            CreateEmptyPattern(),
             []));
 
         Assert.Contains("unsupported functionRef", error.Message, StringComparison.OrdinalIgnoreCase);
     }
 
-    private static PatternDefinitionDto CreatePattern(string agentId)
-    {
-        return new PatternDefinitionDto
-        {
-            Id = "pattern-1",
-            Name = "Workflow Pattern",
-            Mode = "single",
-            Availability = "available",
-            Agents =
-            [
-                new PatternAgentDefinitionDto
-                {
-                    Id = agentId,
-                    Name = "Child Agent",
-                    Instructions = "Help with the request.",
-                    Model = "gpt-5.4",
-                },
-            ],
-        };
-    }
-
     private static WorkflowDefinitionDto CreateAgentWorkflow(string id, string agentId)
     {
         return new WorkflowDefinitionDto
@@ -243,18 +215,6 @@ public sealed class WorkflowRunnerTests
         };
     }
 
-    private static PatternDefinitionDto CreateEmptyPattern()
-    {
-        return new PatternDefinitionDto
-        {
-            Id = "pattern-empty",
-            Name = "Workflow Pattern",
-            Mode = "single",
-            Availability = "available",
-            Agents = [],
-        };
-    }
-
     private static WorkflowDefinitionDto CreateSubworkflowParent(
         string? workflowId = null,
         WorkflowDefinitionDto? inlineWorkflow = null)