Fix sub-session completion flow: navigate to next incomplete sub-session

Instead of returning to parent (which creates a redirect loop), the
handleNext function now finds the next incomplete sub-session and opens
it directly. When all sub-sessions are done, returns to session list.

Also fixes openSession auto-redirect to prefer the first incomplete
sub-session over the most advanced one.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

admin-lehrer/app/(admin)/ai/ocr-pipeline/page.tsx

@@ -73,12 +73,17 @@ export default function OcrPipelinePage() {
       if (data.sub_sessions && data.sub_sessions.length > 0) {
         setSubSessions(data.sub_sessions)
         setParentSessionId(sid)
-        // Parent has sub-sessions — open the most advanced one automatically
-        const sorted = [...data.sub_sessions].sort(
-          (a: SubSession, b: SubSession) => (b.current_step || 0) - (a.current_step || 0),
+        // Parent has sub-sessions — open the first incomplete one (or most advanced if all done)
+        const incomplete = data.sub_sessions.find(
+          (s: SubSession) => !s.current_step || s.current_step < 10,
         )
-        openSession(sorted[0].id, true)
-        return
+        const target = incomplete || [...data.sub_sessions].sort(
+          (a: SubSession, b: SubSession) => (b.current_step || 0) - (a.current_step || 0),
+        )[0]
+        if (target) {
+          openSession(target.id, true)
+          return
+        }
       } else if (data.parent_session_id) {
         // This is a sub-session — keep parent info but don't reset sub-session list
         setParentSessionId(data.parent_session_id)
@@ -217,12 +222,28 @@ export default function OcrPipelinePage() {
     if (currentStep >= steps.length - 1) {
       // Last step completed
       if (parentSessionId && sessionId !== parentSessionId) {
-        // Sub-session completed — update its status and stay in tab view
-        setSubSessions((prev) =>
-          prev.map((s) => s.id === sessionId ? { ...s, status: 'completed', current_step: 10 } : s)
+        // Sub-session completed — mark it and find next incomplete one
+        const updatedSubs = subSessions.map((s) =>
+          s.id === sessionId ? { ...s, status: 'completed' as const, current_step: 10 } : s,
         )
-        // Switch back to parent
-        handleSessionChange(parentSessionId)
+        setSubSessions(updatedSubs)
+
+        // Find next incomplete sub-session
+        const nextIncomplete = updatedSubs.find(
+          (s) => s.id !== sessionId && (!s.current_step || s.current_step < 10),
+        )
+        if (nextIncomplete) {
+          // Open next incomplete sub-session
+          openSession(nextIncomplete.id, true)
+        } else {
+          // All sub-sessions done — return to session list
+          setSteps(PIPELINE_STEPS.map((s, i) => ({ ...s, status: i === 0 ? 'active' : 'pending' })))
+          setCurrentStep(0)
+          setSessionId(null)
+          setSubSessions([])
+          setParentSessionId(null)
+          loadSessions()
+        }
         return
       }
       // Main session: return to session list