feat: replace top-level New Session button with contextual buttons

Remove the single New Session button from the sidebar top and replace it
with contextual creation buttons scoped to each section:

- Scratchpad section: 'New Scratchpad' button that auto-creates a
  scratchpad session with the first available single-agent pattern
- Project groups: 'New Session' button that opens the pattern picker
  modal pre-scoped to that project
- WelcomePane: primary action updated to 'New Scratchpad'

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

src/renderer/App.tsx

@@ -22,7 +22,7 @@ import {
   resolveReasoningEffort,
 } from '@shared/domain/models';
 import type { PatternDefinition } from '@shared/domain/pattern';
-import { isScratchpadProject } from '@shared/domain/project';
+import { isScratchpadProject, SCRATCHPAD_PROJECT_ID } from '@shared/domain/project';
 import { applyScratchpadSessionConfig } from '@shared/domain/session';
 import type { LspProfileDefinition, McpServerDefinition } from '@shared/domain/tooling';
 import type { WorkspaceState } from '@shared/domain/workspace';
@@ -89,7 +89,7 @@ export default function App() {
   const [isRefreshingCapabilities, setIsRefreshingCapabilities] = useState(false);
 
   const [showSettings, setShowSettings] = useState(false);
-  const [showNewSession, setShowNewSession] = useState(false);
+  const [newSessionProjectId, setNewSessionProjectId] = useState<string>();
 
   // Load workspace on mount
   useEffect(() => {
@@ -201,6 +201,21 @@ export default function App() {
     }
   };
 
+  const handleCreateScratchpad = () => {
+    const singlePatterns = workspace.patterns
+      .filter((p) => p.mode === 'single' && p.availability !== 'unavailable')
+      .sort((a, b) => {
+        if (a.isFavorite && !b.isFavorite) return -1;
+        if (!a.isFavorite && b.isFavorite) return 1;
+        return 0;
+      });
+
+    const defaultPattern = singlePatterns[0];
+    if (defaultPattern) {
+      void api.createSession({ projectId: SCRATCHPAD_PROJECT_ID, patternId: defaultPattern.id });
+    }
+  };
+
   // Determine main content
   let content: React.ReactNode;
   let detailPanel: React.ReactNode | undefined;
@@ -253,7 +268,7 @@ export default function App() {
       <WelcomePane
         hasProjects={hasUserProjects}
         onAddProject={() => void api.addProject()}
-        onNewSession={() => setShowNewSession(true)}
+        onNewScratchpad={() => handleCreateScratchpad()}
         onOpenSettings={() => setShowSettings(true)}
       />
     );
@@ -309,7 +324,10 @@ export default function App() {
         sidebar={
           <Sidebar
             onAddProject={() => void api.addProject()}
-            onNewSession={() => setShowNewSession(true)}
+            onCreateScratchpad={() => handleCreateScratchpad()}
+            onNewProjectSession={(projectId) => {
+              setNewSessionProjectId(projectId);
+            }}
             onOpenSettings={() => setShowSettings(true)}
             onProjectSelect={(projectId) => {
               void api.selectProject(projectId);
@@ -337,12 +355,12 @@ export default function App() {
         }
       />
 
-      {showNewSession && (
+      {newSessionProjectId && (
         <NewSessionModal
-          defaultProjectId={workspace.selectedProjectId}
-          onClose={() => setShowNewSession(false)}
+          defaultProjectId={newSessionProjectId}
+          onClose={() => setNewSessionProjectId(undefined)}
           onCreate={(projectId, patternId) => {
-            setShowNewSession(false);
+            setNewSessionProjectId(undefined);
             void api.createSession({ projectId, patternId });
           }}
           onTogglePatternFavorite={(patternId, isFavorite) => {

src/renderer/components/Sidebar.tsx

@@ -35,7 +35,8 @@ import type { WorkspaceState } from '@shared/domain/workspace';
 interface SidebarProps {
   workspace: WorkspaceState;
   onAddProject: () => void;
-  onNewSession: () => void;
+  onCreateScratchpad: () => void;
+  onNewProjectSession: (projectId: string) => void;
   onProjectSelect: (projectId?: string) => void;
   onSessionSelect: (sessionId: string) => void;
   onOpenSettings: () => void;
@@ -310,6 +311,8 @@ function ProjectGroup({
   onRenameSubmit,
   onRenameCancel,
   onRefreshGitContext,
+  onNewSession,
+  newSessionLabel,
 }: {
   project: ProjectRecord;
   sessions: SessionRecord[];
@@ -321,6 +324,8 @@ function ProjectGroup({
   onRenameSubmit: (sessionId: string, title: string) => void;
   onRenameCancel: () => void;
   onRefreshGitContext?: (projectId: string) => void;
+  onNewSession?: () => void;
+  newSessionLabel?: string;
 }){
   const [expanded, setExpanded] = useState(true);
   const isScratchpad = isScratchpadProject(project);
@@ -414,6 +419,16 @@ function ProjectGroup({
               />
             ))
           )}
+          {onNewSession && (
+            <button
+              className="flex w-full items-center justify-center gap-1.5 rounded-md border border-dashed border-zinc-700/60 bg-zinc-800/20 px-2.5 py-1.5 text-[12px] font-medium text-zinc-500 transition hover:border-indigo-500/40 hover:bg-indigo-500/5 hover:text-indigo-300"
+              onClick={onNewSession}
+              type="button"
+            >
+              <Plus className="size-3.5" />
+              {newSessionLabel ?? 'New Session'}
+            </button>
+          )}
         </div>
       )}
     </div>
@@ -425,7 +440,8 @@ function ProjectGroup({
 export function Sidebar({
   workspace,
   onAddProject,
-  onNewSession,
+  onCreateScratchpad,
+  onNewProjectSession,
   onProjectSelect,
   onSessionSelect,
   onOpenSettings,
@@ -537,18 +553,6 @@ export function Sidebar({
         </div>
       </div>
 
-      {/* New session CTA */}
-      <div className="px-3 pt-2 pb-1">
-        <button
-          className="flex w-full items-center justify-center gap-2 rounded-lg border border-dashed border-zinc-700 bg-zinc-800/30 px-3 py-2 text-[13px] font-medium text-zinc-400 transition hover:border-indigo-500/40 hover:bg-indigo-500/5 hover:text-indigo-300"
-          onClick={onNewSession}
-          type="button"
-        >
-          <Plus className="size-4" />
-          New Session
-        </button>
-      </div>
-
       {/* Session list */}
       <div
         className="flex-1 overflow-y-auto px-2 py-2"
@@ -600,6 +604,8 @@ export function Sidebar({
                   project={scratchpadProject}
                   selectedSessionId={workspace.selectedSessionId}
                   sessions={workspace.sessions.filter((session) => session.projectId === scratchpadProject.id)}
+                  onNewSession={onCreateScratchpad}
+                  newSessionLabel="New Scratchpad"
                 />
               </div>
             )}
@@ -646,6 +652,7 @@ export function Sidebar({
                     project={project}
                     selectedSessionId={workspace.selectedSessionId}
                     sessions={workspace.sessions.filter((session) => session.projectId === project.id)}
+                    onNewSession={() => onNewProjectSession(project.id)}
                   />
                 ))}
               </div>

src/renderer/components/WelcomePane.tsx

@@ -2,14 +2,14 @@ import { MessageSquare, Plus, Settings } from 'lucide-react';
 
 interface WelcomePaneProps {
   hasProjects: boolean;
-  onNewSession: () => void;
+  onNewScratchpad: () => void;
   onAddProject: () => void;
   onOpenSettings: () => void;
 }
 
 export function WelcomePane({
   hasProjects,
-  onNewSession,
+  onNewScratchpad,
   onAddProject,
   onOpenSettings,
 }: WelcomePaneProps) {
@@ -31,11 +31,11 @@ export function WelcomePane({
         <div className="flex flex-col items-center gap-2">
           <button
             className="flex items-center gap-2 rounded-lg bg-indigo-600 px-5 py-2.5 text-sm font-medium text-white transition hover:bg-indigo-500"
-            onClick={onNewSession}
+            onClick={onNewScratchpad}
             type="button"
           >
             <Plus className="size-4" />
-            New Session
+            New Scratchpad
           </button>
           {!hasProjects && (
             <button