feat: isolate Claude and Codex session sources

Persist platform_source across session creation, transcript ingestion, API query paths, and viewer state so Claude and Codex data can coexist without bleeding into each other.

- add platform-source normalization helpers and persist platform_source in sdk_sessions via migration 24 with backfill and indexing
- thread platformSource through CLI hooks, transcript processing, context generation, pagination, search routes, SSE payloads, and session management
- expose source-aware project catalogs, viewer tabs, context preview selectors, and source badges for observations, prompts, and summaries
- start the transcript watcher from the worker for transcript-based clients and preserve platform source during Codex ingestion
- auto-start the worker from the MCP server for MCP-only clients and tighten stdio-driven cleanup during shutdown
- keep createSDKSession backward compatible with existing custom-title callers while allowing explicit platform source forwarding

src/ui/viewer/components/Header.tsx

@@ -7,8 +7,11 @@ import { useSpinningFavicon } from '../hooks/useSpinningFavicon';
 interface HeaderProps {
   isConnected: boolean;
   projects: string[];
+  sources: string[];
   currentFilter: string;
+  currentSource: string;
   onFilterChange: (filter: string) => void;
+  onSourceChange: (source: string) => void;
   isProcessing: boolean;
   queueDepth: number;
   themePreference: ThemePreference;
@@ -16,11 +19,26 @@ interface HeaderProps {
   onContextPreviewToggle: () => void;
 }
 
+function formatSourceLabel(source: string): string {
+  if (source === 'all') return 'All';
+  if (source === 'claude') return 'Claude';
+  if (source === 'codex') return 'Codex';
+  return source.charAt(0).toUpperCase() + source.slice(1);
+}
+
+function buildSourceTabs(sources: string[]): string[] {
+  const merged = ['all', 'claude', 'codex', ...sources];
+  return Array.from(new Set(merged.filter(Boolean)));
+}
+
 export function Header({
   isConnected,
   projects,
+  sources,
   currentFilter,
+  currentSource,
   onFilterChange,
+  onSourceChange,
   isProcessing,
   queueDepth,
   themePreference,
@@ -28,20 +46,36 @@ export function Header({
   onContextPreviewToggle
 }: HeaderProps) {
   useSpinningFavicon(isProcessing);
+  const availableSources = buildSourceTabs(sources);
 
   return (
     <div className="header">
-      <h1>
-        <div style={{ position: 'relative', display: 'inline-block' }}>
-          <img src="claude-mem-logomark.webp" alt="" className={`logomark ${isProcessing ? 'spinning' : ''}`} />
-          {queueDepth > 0 && (
-            <div className="queue-bubble">
-              {queueDepth}
-            </div>
-          )}
+      <div className="header-main">
+        <h1>
+          <div style={{ position: 'relative', display: 'inline-block' }}>
+            <img src="claude-mem-logomark.webp" alt="" className={`logomark ${isProcessing ? 'spinning' : ''}`} />
+            {queueDepth > 0 && (
+              <div className="queue-bubble">
+                {queueDepth}
+              </div>
+            )}
+          </div>
+          <span className="logo-text">claude-mem</span>
+        </h1>
+        <div className="source-tabs" role="tablist" aria-label="Context source tabs">
+          {availableSources.map(source => (
+            <button
+              key={source}
+              type="button"
+              className={`source-tab ${currentSource === source ? 'active' : ''}`}
+              onClick={() => onSourceChange(source)}
+              aria-pressed={currentSource === source}
+            >
+              {formatSourceLabel(source)}
+            </button>
+          ))}
         </div>
-        <span className="logo-text">claude-mem</span>
-      </h1>
+      </div>
       <div className="status">
         <a
           href="https://docs.claude-mem.ai"