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/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
         }
     }
 }
+