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/hooks/useContextPreview.ts

@@ -1,5 +1,5 @@
 import { useState, useEffect, useCallback } from 'react';
-import type { Settings } from '../types';
+import type { ProjectCatalog, Settings } from '../types';
 
 interface UseContextPreviewResult {
   preview: string;
@@ -7,15 +7,31 @@ interface UseContextPreviewResult {
   error: string | null;
   refresh: () => Promise<void>;
   projects: string[];
+  sources: string[];
+  selectedSource: string | null;
+  setSelectedSource: (source: string) => void;
   selectedProject: string | null;
   setSelectedProject: (project: string) => void;
 }
 
+function getPreferredSource(sources: string[]): string | null {
+  if (sources.includes('claude')) return 'claude';
+  if (sources.includes('codex')) return 'codex';
+  return sources[0] || null;
+}
+
+function withDefaultSources(sources: string[]): string[] {
+  const merged = ['claude', 'codex', ...sources];
+  return Array.from(new Set(merged));
+}
+
 export function useContextPreview(settings: Settings): UseContextPreviewResult {
   const [preview, setPreview] = useState<string>('');
   const [isLoading, setIsLoading] = useState(false);
   const [error, setError] = useState<string | null>(null);
+  const [catalog, setCatalog] = useState<ProjectCatalog>({ projects: [], sources: [], projectsBySource: {} });
   const [projects, setProjects] = useState<string[]>([]);
+  const [selectedSource, setSelectedSource] = useState<string | null>(null);
   const [selectedProject, setSelectedProject] = useState<string | null>(null);
 
   // Fetch projects on mount
@@ -23,11 +39,27 @@ export function useContextPreview(settings: Settings): UseContextPreviewResult {
     async function fetchProjects() {
       try {
         const response = await fetch('/api/projects');
-        const data = await response.json();
-        if (data.projects && data.projects.length > 0) {
-          setProjects(data.projects);
-          setSelectedProject(data.projects[0]); // Default to first project
+        const data = await response.json() as ProjectCatalog;
+        const nextCatalog: ProjectCatalog = {
+          projects: data.projects || [],
+          sources: withDefaultSources(data.sources || []),
+          projectsBySource: data.projectsBySource || {}
+        };
+
+        setCatalog(nextCatalog);
+
+        const preferredSource = getPreferredSource(nextCatalog.sources);
+        setSelectedSource(preferredSource);
+
+        if (preferredSource) {
+          const sourceProjects = nextCatalog.projectsBySource[preferredSource] || [];
+          setProjects(sourceProjects);
+          setSelectedProject(sourceProjects[0] || null);
+          return;
         }
+
+        setProjects(nextCatalog.projects);
+        setSelectedProject(nextCatalog.projects[0] || null);
       } catch (err) {
         console.error('Failed to fetch projects:', err);
       }
@@ -35,6 +67,18 @@ export function useContextPreview(settings: Settings): UseContextPreviewResult {
     fetchProjects();
   }, []);
 
+  useEffect(() => {
+    if (!selectedSource) {
+      setProjects(catalog.projects);
+      setSelectedProject(prev => (prev && catalog.projects.includes(prev) ? prev : catalog.projects[0] || null));
+      return;
+    }
+
+    const sourceProjects = catalog.projectsBySource[selectedSource] || [];
+    setProjects(sourceProjects);
+    setSelectedProject(prev => (prev && sourceProjects.includes(prev) ? prev : sourceProjects[0] || null));
+  }, [catalog, selectedSource]);
+
   const refresh = useCallback(async () => {
     if (!selectedProject) {
       setPreview('No project selected');
@@ -48,6 +92,10 @@ export function useContextPreview(settings: Settings): UseContextPreviewResult {
       project: selectedProject
     });
 
+    if (selectedSource) {
+      params.append('platformSource', selectedSource);
+    }
+
     const response = await fetch(`/api/context/preview?${params}`);
     const text = await response.text();
 
@@ -58,7 +106,7 @@ export function useContextPreview(settings: Settings): UseContextPreviewResult {
     }
 
     setIsLoading(false);
-  }, [selectedProject]);
+  }, [selectedProject, selectedSource]);
 
   // Debounced refresh when settings or selectedProject change
   useEffect(() => {
@@ -68,5 +116,16 @@ export function useContextPreview(settings: Settings): UseContextPreviewResult {
     return () => clearTimeout(timeout);
   }, [settings, refresh]);
 
-  return { preview, isLoading, error, refresh, projects, selectedProject, setSelectedProject };
+  return {
+    preview,
+    isLoading,
+    error,
+    refresh,
+    projects,
+    sources: catalog.sources,
+    selectedSource,
+    setSelectedSource,
+    selectedProject,
+    setSelectedProject
+  };
 }