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>

tests/main/appServiceInterruptedSessions.test.ts

@@ -2,12 +2,12 @@ import { describe, expect, mock, test } from 'bun:test';
 
 import type { PendingApprovalRecord } from '@shared/domain/approval';
 import type { PendingMcpAuthRecord } from '@shared/domain/mcpAuth';
-import type { PatternDefinition } from '@shared/domain/pattern';
 import type { PendingPlanReviewRecord } from '@shared/domain/planReview';
 import type { SessionRunRecord } from '@shared/domain/runTimeline';
 import type { SessionRecord } from '@shared/domain/session';
 import type { PendingUserInputRecord } from '@shared/domain/userInput';
 import { createWorkspaceSeed, type WorkspaceState } from '@shared/domain/workspace';
+import type { WorkflowDefinition } from '@shared/domain/workflow';
 
 const TIMESTAMP = '2026-03-28T00:00:00.000Z';
 const INTERRUPTED_RUN_ERROR =
@@ -44,20 +44,20 @@ mock.module('keytar', () => ({
 
 const { AryxAppService } = await import('@main/AryxAppService');
 
-function requireSinglePattern(workspace: WorkspaceState): PatternDefinition {
-  const pattern = workspace.patterns.find((candidate) => candidate.mode === 'single');
-  if (!pattern) {
-    throw new Error('Expected the workspace seed to include a single-agent pattern.');
+function requireSingleWorkflow(workspace: WorkspaceState): WorkflowDefinition {
+  const workflow = workspace.workflows.find((candidate) => candidate.settings.orchestrationMode === 'single');
+  if (!workflow) {
+    throw new Error('Expected the workspace seed to include a single-agent workflow.');
   }
 
-  return pattern;
+  return workflow;
 }
 
-function createSession(patternId: string, overrides?: Partial<SessionRecord>): SessionRecord {
+function createSession(workflowId: string, overrides?: Partial<SessionRecord>): SessionRecord {
   return {
     id: 'session-1',
     projectId: 'project-1',
-    patternId,
+    workflowId,
     title: 'Session',
     createdAt: TIMESTAMP,
     updatedAt: TIMESTAMP,
@@ -69,7 +69,7 @@ function createSession(patternId: string, overrides?: Partial<SessionRecord>): S
 }
 
 function createRun(
-  pattern: PatternDefinition,
+  workflow: WorkflowDefinition,
   overrides?: Partial<SessionRunRecord>,
 ): SessionRunRecord {
   return {
@@ -78,9 +78,9 @@ function createRun(
     projectId: 'project-1',
     projectPath: 'C:\\workspace\\personal\\repositories\\aryx',
     workspaceKind: 'project',
-    patternId: pattern.id,
-    patternName: pattern.name,
-    patternMode: pattern.mode,
+    workflowId: workflow.id,
+    workflowName: workflow.name,
+    workflowMode: workflow.settings.orchestrationMode ?? 'single',
     triggerMessageId: 'message-1',
     startedAt: TIMESTAMP,
     status: 'running',
@@ -171,9 +171,9 @@ function createService(
 describe('AryxAppService interrupted session cleanup', () => {
   test('clears stale approvals and user input, then fails the interrupted run on load', async () => {
     const workspace = createWorkspaceSeed();
-    const pattern = requireSinglePattern(workspace);
-    const runningRun = createRun(pattern);
-    const session = createSession(pattern.id, {
+    const workflow = requireSingleWorkflow(workspace);
+    const runningRun = createRun(workflow);
+    const session = createSession(workflow.id, {
       status: 'running',
       pendingApproval: createPendingApproval('approval-1', 'Approve reading the repo'),
       pendingApprovalQueue: [createPendingApproval('approval-2', 'Approve writing the repo')],
@@ -212,10 +212,10 @@ describe('AryxAppService interrupted session cleanup', () => {
 
   test('fails sessions that were left in running state even without pending interaction records', async () => {
     const workspace = createWorkspaceSeed();
-    const pattern = requireSinglePattern(workspace);
-    const session = createSession(pattern.id, {
+    const workflow = requireSingleWorkflow(workspace);
+    const session = createSession(workflow.id, {
       status: 'running',
-      runs: [createRun(pattern)],
+      runs: [createRun(workflow)],
     });
     workspace.sessions = [session];
 
@@ -235,10 +235,10 @@ describe('AryxAppService interrupted session cleanup', () => {
 
   test('preserves restart-safe plan review and MCP auth prompts', async () => {
     const workspace = createWorkspaceSeed();
-    const pattern = requireSinglePattern(workspace);
+    const workflow = requireSingleWorkflow(workspace);
     const planReview = createPendingPlanReview();
     const mcpAuth = createPendingMcpAuth();
-    const session = createSession(pattern.id, {
+    const session = createSession(workflow.id, {
       pendingPlanReview: planReview,
       pendingMcpAuth: mcpAuth,
     });