Merge branch 'vk/d2b2-opening-training'

src/app/learning/openings/family/[familyName]/page.tsx

@@ -0,0 +1,194 @@
+'use client';
+
+import { useEffect, useState, useMemo } from 'react';
+import { useParams, useRouter } from 'next/navigation';
+import { ArrowLeft } from 'lucide-react';
+import Header from '@/components/Header';
+import { useTranslation } from '@/lib/i18n/useTranslation';
+import { SupportedLanguage } from '@/lib/i18n/translations';
+import { OpeningMetadata } from '@/lib/openings';
+import { OpeningTrainingProvider } from '@/contexts/OpeningTrainingContext';
+import OpeningTrainer from '@/components/OpeningTrainer/OpeningTrainer';
+import { OpeningTrainerErrorBoundary } from '@/components/OpeningTrainer/ErrorBoundary';
+import { getOpeningsByFamily } from '@/lib/openingTrainer/openingLoader';
+import { buildVariationTree, VariationTree } from '@/lib/openingTrainer/gameLogic';
+import { Personality, PERSONALITIES } from '@/lib/personalities';
+
+/**
+ * Family Training Page
+ *
+ * This page enables training on an entire opening family (e.g., "Italian Game")
+ * instead of a single specific variation. Users can play any moves that exist
+ * in any variation, and the tutor will guide them through the repertoire.
+ */
+export default function FamilyTrainingPage() {
+  const params = useParams();
+  const router = useRouter();
+  const familyName = decodeURIComponent(params.familyName as string);
+
+  const [language, setLanguage] = useState<SupportedLanguage>('en');
+  const [mounted, setMounted] = useState(false);
+  const [variations, setVariations] = useState<OpeningMetadata[]>([]);
+  const [variationTree, setVariationTree] = useState<VariationTree | null>(null);
+  const [isLoading, setIsLoading] = useState(true);
+  const [selectedPersonality, setSelectedPersonality] = useState<Personality>(PERSONALITIES[0]);
+  const [apiKey, setApiKey] = useState<string>('');
+
+  useEffect(() => {
+    const storedLang = localStorage.getItem('chess_tutor_language');
+    if (storedLang) setLanguage(storedLang as SupportedLanguage);
+
+    // Load API key
+    const storedApiKey = localStorage.getItem('gemini_api_key');
+    if (storedApiKey) setApiKey(storedApiKey);
+
+    // Load personality
+    const storedPersonalityId = localStorage.getItem('chess_tutor_personality');
+    if (storedPersonalityId) {
+      const personality = PERSONALITIES.find(p => p.id === storedPersonalityId);
+      if (personality) setSelectedPersonality(personality);
+    }
+
+    setMounted(true);
+  }, []);
+
+  const t = useTranslation(language);
+
+  useEffect(() => {
+    if (mounted) {
+      loadFamilyVariations();
+    }
+  }, [familyName, mounted]);
+
+  const loadFamilyVariations = () => {
+    setIsLoading(true);
+
+    // Get all variations for this family
+    const familyVariations = getOpeningsByFamily(familyName);
+
+    if (familyVariations.length === 0) {
+      // No variations found - redirect back to selection
+      router.push('/learning/openings');
+      return;
+    }
+
+    setVariations(familyVariations);
+
+    // Build the variation tree for efficient lookup
+    const tree = buildVariationTree(familyVariations, familyName);
+    setVariationTree(tree);
+
+    setIsLoading(false);
+  };
+
+  // Create a "representative" opening for the family
+  // Uses the first ECO code and combines info from all variations
+  const familyOpening: OpeningMetadata | null = useMemo(() => {
+    if (variations.length === 0) return null;
+
+    // Get all unique ECO codes
+    const ecoCodes = [...new Set(variations.map((v: OpeningMetadata) => v.eco))].sort();
+    const ecoRange = ecoCodes.length === 1
+      ? ecoCodes[0]
+      : `${ecoCodes[0]}-${ecoCodes[ecoCodes.length - 1]}`;
+
+    // Find the variation with the most moves (for the initial repertoire display)
+    const longestVariation = variations[0]; // Already sorted by move count
+
+    // Create a combined opening metadata
+    return {
+      eco: longestVariation.eco,
+      name: familyName,
+      moves: longestVariation.moves, // Use longest for display, but tree handles all
+      src: 'family',
+      isEcoRoot: true,
+      wikipediaSlug: longestVariation.wikipediaSlug,
+    };
+  }, [variations, familyName]);
+
+  if (!mounted) return null;
+
+  if (isLoading) {
+    return (
+      <>
+        <Header language={language} />
+        <div className="flex-grow bg-gray-100 dark:bg-gray-900 p-4 flex flex-col">
+          <div className="max-w-6xl mx-auto w-full">
+            <div className="flex items-center justify-center min-h-[400px]">
+              <div className="text-center space-y-4">
+                <div className="w-12 h-12 border-4 border-blue-600 border-t-transparent rounded-full animate-spin mx-auto"></div>
+                <p className="text-gray-600 dark:text-gray-400">{t.learning.openingTrainer.loadingSession}</p>
+              </div>
+            </div>
+          </div>
+        </div>
+      </>
+    );
+  }
+
+  if (!familyOpening || !variationTree) {
+    return (
+      <>
+        <Header language={language} />
+        <div className="flex-grow bg-gray-100 dark:bg-gray-900 p-4 flex flex-col">
+          <div className="max-w-6xl mx-auto w-full">
+            <div className="text-center py-12">
+              <h2 className="text-2xl font-bold text-gray-900 dark:text-white mb-4">
+                {t.learning.openingTrainer.openingNotFound}
+              </h2>
+              <p className="text-gray-600 dark:text-gray-400 mb-6">
+                No variations found for &quot;{familyName}&quot;
+              </p>
+              <button
+                onClick={() => router.push('/learning/openings')}
+                className="px-6 py-2 bg-blue-600 text-white rounded-lg hover:bg-blue-700 transition-colors"
+              >
+                {t.learning.openingTrainer.backToOpeningSelection}
+              </button>
+            </div>
+          </div>
+        </div>
+      </>
+    );
+  }
+
+  return (
+    <>
+      <Header language={language} />
+      <div className="flex-grow bg-gray-100 dark:bg-gray-900 p-4 flex flex-col">
+        <div className="max-w-6xl mx-auto w-full">
+          {/* Header */}
+          <div className="mb-6 flex items-center justify-between">
+            <button
+              onClick={() => router.push('/learning/openings')}
+              className="p-2 md:px-4 md:py-2 bg-gray-200 dark:bg-gray-700 rounded-lg hover:bg-gray-300 dark:hover:bg-gray-600 text-sm font-medium transition-colors flex items-center gap-2"
+            >
+              <ArrowLeft size={20} />
+              <span className="hidden md:inline">{t.learning.openingTrainer.backToOpeningSelection}</span>
+            </button>
+          </div>
+
+          <div className="mb-6">
+            <h1 className="text-3xl font-bold text-gray-900 dark:text-white">{familyName}</h1>
+            <p className="text-gray-600 dark:text-gray-400">
+              {variations.length} variation{variations.length !== 1 ? 's' : ''} available
+            </p>
+          </div>
+
+          <OpeningTrainerErrorBoundary>
+            <OpeningTrainingProvider>
+              <OpeningTrainer
+                opening={familyOpening}
+                personality={selectedPersonality}
+                apiKey={apiKey}
+                language={language}
+                variationTree={variationTree}
+                allVariations={variations}
+              />
+            </OpeningTrainingProvider>
+          </OpeningTrainerErrorBoundary>
+        </div>
+      </div>
+    </>
+  );
+}

src/app/learning/openings/page.tsx

@@ -4,7 +4,6 @@ import { useState, useEffect, useMemo } from 'react';
 import { useRouter } from 'next/navigation';
 import { ArrowLeft } from 'lucide-react';
 import Header from '@/components/Header';
-import OpeningSelector from '@/components/OpeningTrainer/OpeningSelector';
 import FamilySelector from '@/components/OpeningTrainer/FamilySelector';
 import { useTranslation } from '@/lib/i18n/useTranslation';
 import { SupportedLanguage } from '@/lib/i18n/translations';
@@ -15,7 +14,6 @@ export default function OpeningsPage() {
   const router = useRouter();
   const [language, setLanguage] = useState<SupportedLanguage>('en');
   const [mounted, setMounted] = useState(false);
-  const [selectedFamily, setSelectedFamily] = useState<string | null>(null);
 
   useEffect(() => {
     const storedLang = localStorage.getItem('chess_tutor_language');
@@ -35,14 +33,6 @@ export default function OpeningsPage() {
     return groupOpeningsByFamily(allOpenings);
   }, [allOpenings]);
 
-  const handleSelectFamily = (familyName: string) => {
-    setSelectedFamily(familyName);
-  };
-
-  const handleBackToFamilies = () => {
-    setSelectedFamily(null);
-  };
-
   if (!mounted) return null;
 
   return (
@@ -61,28 +51,15 @@ export default function OpeningsPage() {
             </button>
           </div>
 
-          {!selectedFamily ? (
-            <>
-              <h1 className="text-3xl font-bold text-gray-900 dark:text-white mb-2">
-                Opening Training
-              </h1>
-              <p className="text-gray-600 dark:text-gray-400 mb-8">
-                Select an opening family to explore. Each family contains multiple variations
-                with engine-backed feedback and AI-powered explanations.
-              </p>
+          <h1 className="text-3xl font-bold text-gray-900 dark:text-white mb-2">
+            Opening Training
+          </h1>
+          <p className="text-gray-600 dark:text-gray-400 mb-8">
+            Select an opening family to train. You can play any variation within the family,
+            and your AI coach will guide you through the different lines.
+          </p>
 
-              <FamilySelector
-                families={openingFamilies}
-                onSelectFamily={handleSelectFamily}
-              />
-            </>
-          ) : (
-            <OpeningSelector
-              openings={allOpenings}
-              selectedFamily={selectedFamily}
-              onBackToFamilies={handleBackToFamilies}
-            />
-          )}
+          <FamilySelector families={openingFamilies} />
         </div>
       </div>
     </>

src/components/ChessGame.test.tsx

@@ -67,9 +67,11 @@ jest.mock("./StartScreen", () => ({
 
 describe("ChessGame Component", () => {
     const mockPersonality = {
+        id: "test",
         name: "Test Personality",
         systemPrompt: "You are a helpful assistant.",
         image: "🤖",
+        description: "Test description",
     };
 
     beforeEach(() => {

src/components/EvaluationBar.test.tsx

@@ -4,7 +4,7 @@ import "@testing-library/jest-dom";
 
 describe("EvaluationBar", () => {
     it("renders 0.0 for initial state", () => {
-        render(<EvaluationBar score={0} />);
+        render(<EvaluationBar score={0} isPlayerWhite={true} />);
         expect(screen.getByText("0.0")).toBeInTheDocument();
     });
 
@@ -19,12 +19,12 @@ describe("EvaluationBar", () => {
     });
 
     it("renders mate score", () => {
-        render(<EvaluationBar mate={3} />);
+        render(<EvaluationBar mate={3} isPlayerWhite={true} />);
         expect(screen.getByText("M3")).toBeInTheDocument();
     });
 
     it("renders negative mate score", () => {
-        render(<EvaluationBar mate={-5} />);
+        render(<EvaluationBar mate={-5} isPlayerWhite={true} />);
         expect(screen.getByText("M5")).toBeInTheDocument();
     });
 });

src/components/OpeningTrainer/FamilySelector.tsx

@@ -1,14 +1,23 @@
 'use client';
 
 import { useMemo } from 'react';
+import { useRouter } from 'next/navigation';
 import { OpeningFamily } from '@/lib/openingTrainer/openingFamilies';
 
 interface FamilySelectorProps {
   families: OpeningFamily[];
-  onSelectFamily: (familyName: string) => void;
+  onSelectFamily?: (familyName: string) => void; // Made optional - now navigates directly
 }
 
 export default function FamilySelector({ families, onSelectFamily }: FamilySelectorProps) {
+  const router = useRouter();
+
+  const handleSelectFamily = (familyName: string) => {
+    // Navigate directly to family training page
+    const encodedName = encodeURIComponent(familyName);
+    router.push(`/learning/openings/family/${encodedName}`);
+  };
+
   // Group families by ECO range for display
   const groupedFamilies = useMemo(() => {
     const groups: Record<string, OpeningFamily[]> = {
@@ -52,7 +61,7 @@ export default function FamilySelector({ families, onSelectFamily }: FamilySelec
               {categoryFamilies.map((family) => (
                 <button
                   key={family.name}
-                  onClick={() => onSelectFamily(family.name)}
+                  onClick={() => handleSelectFamily(family.name)}
                   className="block p-6 border-2 border-gray-200 dark:border-gray-700 bg-white dark:bg-gray-800 rounded-lg hover:border-blue-500 dark:hover:border-blue-400 hover:shadow-lg transition-all text-left"
                   aria-label={`Select ${family.name} opening family`}
                 >

src/components/OpeningTrainer/OpeningTrainer.tsx

@@ -6,7 +6,15 @@ import { Chessboard } from 'react-chessboard';
 import { OpeningMetadata } from '@/lib/openings';
 import { useOpeningTraining, useChessInstance } from '@/contexts/OpeningTrainingContext';
 import { loadSession } from '@/lib/openingTrainer/sessionManager';
-import { parseMoveSequence, getUserColor } from '@/lib/openingTrainer/gameLogic';
+import {
+  parseMoveSequence,
+  getUserColor,
+  VariationTree,
+  getAllPossibleNextMoves,
+  identifyCurrentVariation,
+  isMoveInVariationTree,
+  describeCurrentPosition,
+} from '@/lib/openingTrainer/gameLogic';
 import { getWikipediaSummary } from '@/lib/openingTrainer/wikipediaService';
 import { WikipediaSummary as WikipediaSummaryType } from '@/types/openingTraining';
 import { extractFamilyName } from '@/lib/openingTrainer/openingFamilies';
@@ -22,10 +30,21 @@ interface OpeningTrainerProps {
   personality: Personality;
   apiKey: string;
   language: SupportedLanguage;
+  // Family training mode - allows multiple variations
+  variationTree?: VariationTree;
+  allVariations?: OpeningMetadata[];
 }
 
-export default function OpeningTrainer({ opening, personality, apiKey, language }: OpeningTrainerProps) {
+export default function OpeningTrainer({
+  opening,
+  personality,
+  apiKey,
+  language,
+  variationTree,
+  allVariations,
+}: OpeningTrainerProps) {
   const router = useRouter();
+  const isFamilyMode = !!variationTree && !!allVariations;
 
   const {
     session,
@@ -33,6 +52,7 @@ export default function OpeningTrainer({ opening, personality, apiKey, language
     currentFeedback,
     initializeSession,
     makeMove,
+    undoToMove,
     navigateToMove,
   } = useOpeningTraining();
 
@@ -206,12 +226,12 @@ export default function OpeningTrainer({ opening, personality, apiKey, language
   const handleUndoDeviation = () => {
     if (!session || session.deviationMoveIndex === null) return;
 
-    // Navigate back to the move before deviation
-    navigateToMove(session.deviationMoveIndex - 1);
-    setShowDeviationDialog(false);
+    // Undo to the move before deviation (this truncates move history)
+    const targetIndex = session.deviationMoveIndex - 1;
+    undoToMove(targetIndex);
 
-    // After a brief delay, make another legal move to continue in theory
-    // This allows the player to try again
+    // Close the dialog
+    setShowDeviationDialog(false);
   };
 
   const handleStartGameFromPosition = () => {
@@ -257,6 +277,44 @@ export default function OpeningTrainer({ opening, personality, apiKey, language
     setLastTutorMessageMoveIndex(moveCount);
   };
 
+  // ============================================================================
+  // Family mode hooks - MUST be called before any early returns
+  // ============================================================================
+
+  // Family mode: compute current position info from variation tree
+  // IMPORTANT: Always call useMemo, even if not in family mode (React Hooks rule)
+  const variationPositionInfo = useMemo(() => {
+    if (!isFamilyMode || !variationTree || !session) {
+      return null;
+    }
+    const positionDesc = describeCurrentPosition(variationTree, session.moveHistory);
+    const currentVariations = identifyCurrentVariation(variationTree, session.moveHistory);
+    const possibleMoves = getAllPossibleNextMoves(variationTree, session.moveHistory);
+
+    return {
+      ...positionDesc,
+      currentVariations,
+      possibleMoves,
+      isInAnyVariation: positionDesc.matchingCount > 0,
+    };
+  }, [isFamilyMode, variationTree, session]);
+
+  // Get all possible next moves (for display and tutor context)
+  const theoreticalMoves = useMemo(() => {
+    if (isFamilyMode && variationPositionInfo) {
+      return variationPositionInfo.nextMoves;
+    }
+    // Single variation mode
+    if (!session) return [];
+    const moves = parseMoveSequence(opening.moves);
+    const nextMove = moves[session.moveHistory.length];
+    return nextMove ? [nextMove] : [];
+  }, [isFamilyMode, variationPositionInfo, opening.moves, session]);
+
+  // ============================================================================
+  // Early returns for loading/error states
+  // ============================================================================
+
   // Session recovery dialog
   if (showRecoveryDialog && existingSession) {
     return (
@@ -365,12 +423,16 @@ export default function OpeningTrainer({ opening, personality, apiKey, language
   const lastUserMove = userMoves.length > 0 ? userMoves[userMoves.length - 1] : null;
   const lastTutorMove = tutorMoves.length > 0 ? tutorMoves[tutorMoves.length - 1] : null;
 
+  // Note: variationPositionInfo and theoreticalMoves are computed above (before early returns)
+
   const openingPracticeMode = {
     openingName: opening.name,
     openingEco: opening.eco,
     repertoireMoves,
     currentMoveIndex: session.moveHistory.length,
-    isInTheory: session.deviationMoveIndex === null,
+    isInTheory: isFamilyMode
+      ? (variationPositionInfo?.isInAnyVariation ?? false)
+      : session.deviationMoveIndex === null,
     deviationMoveIndex: session.deviationMoveIndex,
     lastUserMove: lastUserMove ? {
       from: lastUserMove.uci.substring(0, 2),
@@ -395,11 +457,23 @@ export default function OpeningTrainer({ opening, personality, apiKey, language
     currentFeedback: currentFeedback ? {
       category: currentFeedback.classification.category,
       evaluationChange: currentFeedback.classification.evaluationChange,
-      theoreticalAlternatives: currentFeedback.classification.theoreticalAlternatives
-    } : null,
+      theoreticalAlternatives: isFamilyMode ? theoreticalMoves : currentFeedback.classification.theoreticalAlternatives
+    } : (isFamilyMode ? {
+      category: 'in-theory' as const,
+      evaluationChange: 0,
+      theoreticalAlternatives: theoreticalMoves
+    } : null),
     wikipediaSummary: wikipediaSummary?.extract || undefined,
     shouldTutorSpeak,
     onTutorMessageSent: handleTutorMessageSent,
+    // Family mode specific info
+    isFamilyMode,
+    variationInfo: isFamilyMode && variationPositionInfo ? {
+      matchingVariations: variationPositionInfo.matchingCount,
+      currentVariationNames: variationPositionInfo.currentVariationNames,
+      possibleMoves: variationPositionInfo.nextMoves,
+      isEndOfLine: variationPositionInfo.isEndOfLine,
+    } : undefined,
   };
 
   return (
@@ -572,13 +646,81 @@ export default function OpeningTrainer({ opening, personality, apiKey, language
             <span className="text-gray-600 dark:text-gray-400">Moves played:</span>
             <span className="font-medium text-gray-900 dark:text-white">{moveCount}</span>
           </div>
-          {session.deviationMoveIndex !== null && (
+
+          {/* Family mode: show variation info */}
+          {isFamilyMode && variationPositionInfo && (
+            <>
+              <div className="pt-2 border-t border-gray-300 dark:border-gray-600">
+                <div className="flex justify-between mb-1">
+                  <span className="text-gray-600 dark:text-gray-400">Matching variations:</span>
+                  <span className="font-medium text-blue-600 dark:text-blue-400">
+                    {variationPositionInfo.matchingCount}
+                  </span>
+                </div>
+
+                {/* Show possible moves */}
+                {variationPositionInfo.nextMoves.length > 0 && (
+                  <div className="mt-2">
+                    <span className="text-gray-600 dark:text-gray-400 block mb-1">Possible moves:</span>
+                    <div className="flex flex-wrap gap-1">
+                      {variationPositionInfo.nextMoves.map((move) => (
+                        <span
+                          key={move}
+                          className="inline-block px-2 py-1 bg-green-100 dark:bg-green-900/30 text-green-800 dark:text-green-400 rounded text-xs font-mono"
+                        >
+                          {move}
+                        </span>
+                      ))}
+                    </div>
+                  </div>
+                )}
+
+                {/* Show current variation names (if narrowed down) */}
+                {variationPositionInfo.matchingCount > 0 && variationPositionInfo.matchingCount <= 3 && (
+                  <div className="mt-2">
+                    <span className="text-gray-600 dark:text-gray-400 block mb-1">Current line:</span>
+                    <div className="space-y-1">
+                      {variationPositionInfo.currentVariationNames.slice(0, 3).map((name) => (
+                        <span
+                          key={name}
+                          className="block text-xs text-gray-700 dark:text-gray-300 truncate"
+                          title={name}
+                        >
+                          {name}
+                        </span>
+                      ))}
+                    </div>
+                  </div>
+                )}
+
+                {variationPositionInfo.isEndOfLine && (
+                  <div className="mt-2">
+                    <span className="inline-block px-2 py-1 bg-purple-100 dark:bg-purple-900/30 text-purple-800 dark:text-purple-400 rounded text-xs">
+                      End of repertoire line
+                    </span>
+                  </div>
+                )}
+              </div>
+            </>
+          )}
+
+          {/* Show off-book indicator (non-family mode or when truly off-book) */}
+          {!isFamilyMode && session.deviationMoveIndex !== null && (
             <div className="pt-2 border-t border-gray-300 dark:border-gray-600">
               <span className="inline-block px-2 py-1 bg-orange-100 dark:bg-orange-900/30 text-orange-800 dark:text-orange-400 rounded text-xs">
                 Off-book since move {session.deviationMoveIndex + 1}
               </span>
             </div>
           )}
+
+          {/* Family mode: show off-book when not in any variation */}
+          {isFamilyMode && variationPositionInfo && !variationPositionInfo.isInAnyVariation && moveCount > 0 && (
+            <div className="pt-2 border-t border-gray-300 dark:border-gray-600">
+              <span className="inline-block px-2 py-1 bg-orange-100 dark:bg-orange-900/30 text-orange-800 dark:text-orange-400 rounded text-xs">
+                Off-book - move not in any variation
+              </span>
+            </div>
+          )}
         </div>
       </div>
 

src/components/Tutor.tsx

@@ -82,6 +82,14 @@ interface TutorProps {
         wikipediaSummary?: string;  // Optional Wikipedia context
         shouldTutorSpeak?: boolean;  // Guardrail: controls when tutor can send messages
         onTutorMessageSent?: () => void;  // Callback when tutor sends a message
+        // Family mode: training with multiple variations
+        isFamilyMode?: boolean;
+        variationInfo?: {
+            matchingVariations: number;
+            currentVariationNames: string[];
+            possibleMoves: string[];
+            isEndOfLine: boolean;
+        };
     };
 }
 
@@ -359,6 +367,8 @@ Acknowledge this new puzzle briefly (1 sentence) and encourage the student to fi
     const isInTheory = openingPracticeMode?.isInTheory ?? true;
     const currentFeedback = openingPracticeMode?.currentFeedback;
     const repertoireMovesLength = openingPracticeMode?.repertoireMoves?.length ?? 0;
+    const isFamilyMode = openingPracticeMode?.isFamilyMode ?? false;
+    const variationInfo = openingPracticeMode?.variationInfo;
 
     // Automatic commentary for opening practice mode
     useEffect(() => {
@@ -382,6 +392,14 @@ Acknowledge this new puzzle briefly (1 sentence) and encourage the student to fi
         if (userMoveKey && userMoveKey !== lastUserMoveRef.current) {
             lastUserMoveRef.current = userMoveKey;
 
+            // Build variation context for family mode
+            const variationContext = isFamilyMode && variationInfo ? `
+Variation info:
+- Matching variations: ${variationInfo.matchingVariations}
+- Current line(s): ${variationInfo.currentVariationNames.slice(0, 3).join(', ')}${variationInfo.currentVariationNames.length > 3 ? '...' : ''}
+- Possible next moves: ${variationInfo.possibleMoves.join(', ') || 'none (end of line)'}
+${variationInfo.isEndOfLine ? '- This is the end of this variation line' : ''}` : '';
+
             // Generate commentary about user's move
             const moveCommentary = `
 [SYSTEM TRIGGER: user_move_in_opening]
@@ -391,13 +409,25 @@ Move category: ${currentFeedback?.category || 'unknown'}
 Position status: ${isInTheory ? 'In theory' : 'Deviated from repertoire'}
 ${currentFeedback?.evaluationChange !== undefined ? `Evaluation change: ${currentFeedback.evaluationChange.toFixed(2)}` : ''}
 ${currentFeedback?.theoreticalAlternatives && currentFeedback.theoreticalAlternatives.length > 0 ? `Theory suggested: ${currentFeedback.theoreticalAlternatives.join(', ')}` : ''}
+${variationContext}
 
 INSTRUCTIONS:
 ${isInTheory
-    ? `- The student is following the repertoire correctly - praise them briefly
+    ? isFamilyMode
+        ? `- The student is playing a valid move in the ${openingName} family
+- Tell them which specific variation(s) they're now in (if narrowed down)
+- Explain the key idea behind this move (1-2 sentences)
+- If there are multiple possible moves at this position, you can briefly mention alternatives
+- If you're about to make the next move, explain what it accomplishes`
+        : `- The student is following the repertoire correctly - praise them briefly
 - Explain the key idea behind this move (1-2 sentences)
 - If you're about to make the next move, you can mention it naturally`
-    : `- The student deviated from theory
+    : isFamilyMode
+        ? `- The student played a move not in any known variation of ${openingName}
+- Gently mention which moves would have been in theory (${currentFeedback?.theoreticalAlternatives?.join(' or ') || 'the main lines'})
+- Explain why those moves are preferred in the ${openingName}
+- Encourage them to explore or try a different move`
+        : `- The student deviated from theory
 - Gently point out what the repertoire move was
 - Explain why the repertoire move is preferred
 - Ask if they want to try again or continue exploring`}
@@ -469,7 +499,9 @@ Remember: You are both the opponent AND the tutor. Explain your move as if you'r
         language,
         openingName,
         currentFeedback,
-        repertoireMovesLength
+        repertoireMovesLength,
+        isFamilyMode,
+        variationInfo
     ]);
 
     // Scroll chat container to bottom (not the whole page)

src/components/__tests__/Tutor.test.tsx

@@ -46,14 +46,16 @@ describe('Tutor', () => {
           stockfish={stockfish}
           evalP0={null}
           evalP2={null}
-          openingData={null}
+          openingData={[]}
           missedTactics={null}
           onAnalysisComplete={() => {}}
           apiKey="test-api-key"
           personality={{
+              id: "test",
               name: "Test Personality",
               systemPrompt: "Test Prompt",
-              image: "🤖"
+              image: "🤖",
+              description: "Test description"
           }}
           language="en"
           playerColor="white"
@@ -103,14 +105,16 @@ describe('Tutor', () => {
           stockfish={stockfish}
           evalP0={null}
           evalP2={null}
-          openingData={null}
+          openingData={[]}
           missedTactics={null}
           onAnalysisComplete={() => {}}
           apiKey="test-api-key"
           personality={{
+              id: "test",
               name: "Test Personality",
               systemPrompt: "Test Prompt",
-              image: "🤖"
+              image: "🤖",
+              description: "Test description"
           }}
           language="en"
           playerColor="white"

src/contexts/OpeningTrainingContext.tsx

@@ -38,6 +38,7 @@ interface OpeningTrainingContextType {
   // Actions
   initializeSession: (opening: OpeningMetadata, forceNew?: boolean) => Promise<void>;
   makeMove: (san: string) => Promise<void>;
+  undoToMove: (index: number) => void;
   navigateToMove: (index: number) => void;
   resetSession: () => void;
 }
@@ -294,6 +295,17 @@ export function OpeningTrainingProvider({
     }
   };
 
+  const undoToMove = (index: number) => {
+    if (!session) return;
+
+    console.log('[OpeningTraining] Undoing to move index:', index);
+
+    dispatch({ type: 'UNDO_TO_MOVE', index });
+
+    // Clear feedback when undoing
+    setCurrentFeedback(null);
+  };
+
   const navigateToMove = (index: number) => {
     if (!session) return;
 
@@ -355,6 +367,7 @@ export function OpeningTrainingProvider({
     currentFeedback,
     initializeSession,
     makeMove,
+    undoToMove,
     navigateToMove,
     resetSession,
   };

src/contexts/__tests__/OpeningTrainingContext.test.tsx

@@ -96,6 +96,7 @@ const mockOpening: OpeningMetadata = {
   eco: 'C00',
   name: 'French Defense',
   moves: '1. e4 e6 2. d4 d5',
+  src: 'test',
   wikipediaSlug: 'French_Defence',
 };
 

src/lib/openingTrainer/__tests__/familyTraining.test.ts

@@ -0,0 +1,381 @@
+/**
+ * Integration tests for Family Training Mode
+ * Tests the variation tree and multi-variation support
+ */
+
+import {
+  buildVariationTree,
+  getTreeNodeAtPosition,
+  getMatchingVariations,
+  getAllPossibleNextMoves,
+  isMoveInVariationTree,
+  identifyCurrentVariation,
+  describeCurrentPosition,
+} from '../gameLogic';
+import { OpeningMetadata } from '@/lib/openings';
+import { MoveHistoryEntry } from '@/types/openingTraining';
+
+// ============================================================================
+// Test Data - Italian Game variations
+// ============================================================================
+
+const italianGameVariations: OpeningMetadata[] = [
+  {
+    eco: 'C50',
+    name: 'Italian Game',
+    moves: '1. e4 e5 2. Nf3 Nc6 3. Bc4',
+    src: 'test',
+    isEcoRoot: true,
+  },
+  {
+    eco: 'C53',
+    name: 'Italian Game: Classical Variation',
+    moves: '1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3',
+    src: 'test',
+  },
+  {
+    eco: 'C54',
+    name: 'Italian Game: Giuoco Piano',
+    moves: '1. e4 e5 2. Nf3 Nc6 3. Bc4 Bc5 4. c3 Nf6 5. d4',
+    src: 'test',
+  },
+  {
+    eco: 'C55',
+    name: 'Italian Game: Two Knights Defense',
+    moves: '1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6',
+    src: 'test',
+  },
+];
+
+function createMoveEntry(
+  san: string,
+  color: 'white' | 'black',
+  moveNumber: number
+): MoveHistoryEntry {
+  return {
+    moveNumber,
+    color,
+    san,
+    uci: 'e2e4',
+    fen: 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1',
+    timestamp: Date.now(),
+    evaluation: { score: 0, mate: null, depth: 15, bestMove: 'e4', ponder: null },
+    classification: {
+      category: 'in-theory',
+      inRepertoire: true,
+      evaluationChange: 0,
+      isSignificantSwing: false,
+      theoreticalAlternatives: [],
+    },
+  };
+}
+
+// ============================================================================
+// Tests
+// ============================================================================
+
+describe('Family Training Mode - Variation Tree', () => {
+  describe('buildVariationTree', () => {
+    it('should build a tree from multiple variations', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      expect(tree.familyName).toBe('Italian Game');
+      expect(tree.allVariations).toHaveLength(4);
+      expect(tree.children.size).toBe(1); // Only 1. e4 at root
+      expect(tree.children.has('e4')).toBe(true);
+    });
+
+    it('should create correct branching structure', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      // After 1. e4 e5 2. Nf3 Nc6 3. Bc4, there should be 2 branches
+      const e4Node = tree.children.get('e4')!;
+      const e5Node = e4Node.children.get('e5')!;
+      const nf3Node = e5Node.children.get('Nf3')!;
+      const nc6Node = nf3Node.children.get('Nc6')!;
+      const bc4Node = nc6Node.children.get('Bc4')!;
+
+      // After Bc4, should have Bc5 and Nf6 as options
+      expect(bc4Node.children.size).toBe(2);
+      expect(bc4Node.children.has('Bc5')).toBe(true);
+      expect(bc4Node.children.has('Nf6')).toBe(true);
+    });
+
+    it('should track variations at each node', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      const e4Node = tree.children.get('e4')!;
+      // All variations start with e4
+      expect(e4Node.variations).toHaveLength(4);
+    });
+
+    it('should mark end of line correctly', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      // Navigate to end of "Italian Game" (shortest variation)
+      const e4Node = tree.children.get('e4')!;
+      const e5Node = e4Node.children.get('e5')!;
+      const nf3Node = e5Node.children.get('Nf3')!;
+      const nc6Node = nf3Node.children.get('Nc6')!;
+      const bc4Node = nc6Node.children.get('Bc4')!;
+
+      expect(bc4Node.isEndOfLine).toBe(true); // End of C50 variation
+    });
+  });
+
+  describe('getTreeNodeAtPosition', () => {
+    it('should return root node for empty move history', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+      const node = getTreeNodeAtPosition(tree, []);
+
+      expect(node).not.toBeNull();
+      expect(node!.variations).toHaveLength(4);
+    });
+
+    it('should navigate to correct position', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+      const moveHistory = [
+        createMoveEntry('e4', 'white', 1),
+        createMoveEntry('e5', 'black', 1),
+        createMoveEntry('Nf3', 'white', 2),
+      ];
+
+      const node = getTreeNodeAtPosition(tree, moveHistory);
+
+      expect(node).not.toBeNull();
+      expect(node!.move).toBe('Nf3');
+    });
+
+    it('should return null for moves not in any variation', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+      const moveHistory = [
+        createMoveEntry('d4', 'white', 1), // Not in Italian Game!
+      ];
+
+      const node = getTreeNodeAtPosition(tree, moveHistory);
+
+      expect(node).toBeNull();
+    });
+  });
+
+  describe('getMatchingVariations', () => {
+    it('should return all variations at start', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+      const variations = getMatchingVariations(tree, []);
+
+      expect(variations).toHaveLength(4);
+    });
+
+    it('should narrow down variations as moves are played', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      // After 1. e4 e5 2. Nf3 Nc6 3. Bc4 Nf6
+      const moveHistory = [
+        createMoveEntry('e4', 'white', 1),
+        createMoveEntry('e5', 'black', 1),
+        createMoveEntry('Nf3', 'white', 2),
+        createMoveEntry('Nc6', 'black', 2),
+        createMoveEntry('Bc4', 'white', 3),
+        createMoveEntry('Nf6', 'black', 3),
+      ];
+
+      const variations = getMatchingVariations(tree, moveHistory);
+
+      // Only Two Knights Defense
+      expect(variations).toHaveLength(1);
+      expect(variations[0].name).toBe('Italian Game: Two Knights Defense');
+    });
+
+    it('should return empty array for off-book moves', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+      const moveHistory = [
+        createMoveEntry('e4', 'white', 1),
+        createMoveEntry('c5', 'black', 1), // Sicilian, not Italian!
+      ];
+
+      const variations = getMatchingVariations(tree, moveHistory);
+
+      expect(variations).toHaveLength(0);
+    });
+  });
+
+  describe('getAllPossibleNextMoves', () => {
+    it('should return all possible first moves', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+      const moves = getAllPossibleNextMoves(tree, []);
+
+      expect(moves).toHaveLength(1);
+      expect(moves[0].move).toBe('e4');
+      expect(moves[0].variations).toHaveLength(4);
+    });
+
+    it('should return multiple options at branch points', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      // After 1. e4 e5 2. Nf3 Nc6 3. Bc4
+      const moveHistory = [
+        createMoveEntry('e4', 'white', 1),
+        createMoveEntry('e5', 'black', 1),
+        createMoveEntry('Nf3', 'white', 2),
+        createMoveEntry('Nc6', 'black', 2),
+        createMoveEntry('Bc4', 'white', 3),
+      ];
+
+      const moves = getAllPossibleNextMoves(tree, moveHistory);
+
+      // Should have Bc5 (Classical/Giuoco Piano) and Nf6 (Two Knights)
+      expect(moves).toHaveLength(2);
+      const moveNames = moves.map(m => m.move).sort();
+      expect(moveNames).toEqual(['Bc5', 'Nf6']);
+    });
+
+    it('should return empty array at end of all variations', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      // Go to end of longest variation (Giuoco Piano)
+      const moveHistory = [
+        createMoveEntry('e4', 'white', 1),
+        createMoveEntry('e5', 'black', 1),
+        createMoveEntry('Nf3', 'white', 2),
+        createMoveEntry('Nc6', 'black', 2),
+        createMoveEntry('Bc4', 'white', 3),
+        createMoveEntry('Bc5', 'black', 3),
+        createMoveEntry('c3', 'white', 4),
+        createMoveEntry('Nf6', 'black', 4),
+        createMoveEntry('d4', 'white', 5),
+      ];
+
+      const moves = getAllPossibleNextMoves(tree, moveHistory);
+
+      expect(moves).toHaveLength(0);
+    });
+  });
+
+  describe('isMoveInVariationTree', () => {
+    it('should return true for valid moves', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      const isValid = isMoveInVariationTree(tree, [], 'e4');
+      expect(isValid).toBe(true);
+    });
+
+    it('should return false for invalid moves', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      const isValid = isMoveInVariationTree(tree, [], 'd4');
+      expect(isValid).toBe(false);
+    });
+
+    it('should validate moves at branch points', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      const moveHistory = [
+        createMoveEntry('e4', 'white', 1),
+        createMoveEntry('e5', 'black', 1),
+        createMoveEntry('Nf3', 'white', 2),
+        createMoveEntry('Nc6', 'black', 2),
+        createMoveEntry('Bc4', 'white', 3),
+      ];
+
+      expect(isMoveInVariationTree(tree, moveHistory, 'Bc5')).toBe(true);
+      expect(isMoveInVariationTree(tree, moveHistory, 'Nf6')).toBe(true);
+      expect(isMoveInVariationTree(tree, moveHistory, 'd6')).toBe(false);
+    });
+  });
+
+  describe('describeCurrentPosition', () => {
+    it('should describe starting position', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+      const desc = describeCurrentPosition(tree, []);
+
+      expect(desc.matchingCount).toBe(4);
+      expect(desc.isEndOfLine).toBe(false);
+      expect(desc.nextMoves).toContain('e4');
+    });
+
+    it('should identify branch points', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      const moveHistory = [
+        createMoveEntry('e4', 'white', 1),
+        createMoveEntry('e5', 'black', 1),
+        createMoveEntry('Nf3', 'white', 2),
+        createMoveEntry('Nc6', 'black', 2),
+        createMoveEntry('Bc4', 'white', 3),
+      ];
+
+      const desc = describeCurrentPosition(tree, moveHistory);
+
+      expect(desc.matchingCount).toBe(4); // All 4 variations pass through this position
+      expect(desc.nextMoves).toHaveLength(2);
+      expect(desc.nextMoves).toContain('Bc5');
+      expect(desc.nextMoves).toContain('Nf6');
+    });
+
+    it('should detect end of line', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      // Go to actual end of a line (Giuoco Piano)
+      const moveHistory = [
+        createMoveEntry('e4', 'white', 1),
+        createMoveEntry('e5', 'black', 1),
+        createMoveEntry('Nf3', 'white', 2),
+        createMoveEntry('Nc6', 'black', 2),
+        createMoveEntry('Bc4', 'white', 3),
+        createMoveEntry('Bc5', 'black', 3),
+        createMoveEntry('c3', 'white', 4),
+        createMoveEntry('Nf6', 'black', 4),
+        createMoveEntry('d4', 'white', 5),
+      ];
+
+      const desc = describeCurrentPosition(tree, moveHistory);
+
+      expect(desc.isEndOfLine).toBe(true); // End of Giuoco Piano
+      expect(desc.matchingCount).toBe(1); // Only Giuoco Piano reaches here
+      expect(desc.nextMoves).toHaveLength(0); // No more moves in repertoire
+    });
+  });
+
+  describe('identifyCurrentVariation', () => {
+    it('should identify specific variation', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      // Two Knights Defense
+      const moveHistory = [
+        createMoveEntry('e4', 'white', 1),
+        createMoveEntry('e5', 'black', 1),
+        createMoveEntry('Nf3', 'white', 2),
+        createMoveEntry('Nc6', 'black', 2),
+        createMoveEntry('Bc4', 'white', 3),
+        createMoveEntry('Nf6', 'black', 3),
+      ];
+
+      const result = identifyCurrentVariation(tree, moveHistory);
+
+      expect(result.exact).toHaveLength(1);
+      expect(result.exact[0].name).toBe('Italian Game: Two Knights Defense');
+    });
+
+    it('should return multiple variations when moves overlap', () => {
+      const tree = buildVariationTree(italianGameVariations, 'Italian Game');
+
+      // After Bc5, both Classical and Giuoco Piano are possible
+      const moveHistory = [
+        createMoveEntry('e4', 'white', 1),
+        createMoveEntry('e5', 'black', 1),
+        createMoveEntry('Nf3', 'white', 2),
+        createMoveEntry('Nc6', 'black', 2),
+        createMoveEntry('Bc4', 'white', 3),
+        createMoveEntry('Bc5', 'black', 3),
+      ];
+
+      const result = identifyCurrentVariation(tree, moveHistory);
+
+      // No exact matches at this position, but multiple possible continuations
+      expect(result.possible.length).toBeGreaterThanOrEqual(2);
+      const names = result.possible.map(v => v.name);
+      expect(names).toContain('Italian Game: Classical Variation');
+      expect(names).toContain('Italian Game: Giuoco Piano');
+    });
+  });
+});

src/lib/openingTrainer/__tests__/frenchDefenseFamily.test.ts

@@ -0,0 +1,132 @@
+/**
+ * Test French Defense Family Mode
+ *
+ * This tests the actual scenario where the tutor recommends wrong moves
+ */
+
+import {
+  buildVariationTree,
+  getAllPossibleNextMoves,
+  parseMoveSequence,
+} from '../gameLogic';
+import { getOpeningsByFamily } from '../openingLoader';
+import { MoveHistoryEntry } from '@/types/openingTraining';
+
+function createMoveEntry(
+  san: string,
+  color: 'white' | 'black',
+  moveNumber: number
+): MoveHistoryEntry {
+  return {
+    moveNumber,
+    color,
+    san,
+    uci: 'e2e4',
+    fen: 'rnbqkbnr/pppppppp/8/8/8/8/PPPPPPPP/RNBQKBNR w KQkq - 0 1',
+    timestamp: Date.now(),
+    evaluation: { score: 0, mate: null, depth: 15, bestMove: 'e4', ponder: null },
+    classification: {
+      category: 'in-theory',
+      inRepertoire: true,
+      evaluationChange: 0,
+      isSignificantSwing: false,
+      theoreticalAlternatives: [],
+    },
+  };
+}
+
+describe('French Defense - Family Mode Bug', () => {
+  it('should load French Defense variations', () => {
+    const variations = getOpeningsByFamily('French Defense');
+
+    expect(variations.length).toBeGreaterThan(0);
+    console.log(`Loaded ${variations.length} French Defense variations`);
+  });
+
+  it('should build variation tree for French Defense', () => {
+    const variations = getOpeningsByFamily('French Defense');
+    const tree = buildVariationTree(variations, 'French Defense');
+
+    expect(tree.familyName).toBe('French Defense');
+    expect(tree.allVariations.length).toBe(variations.length);
+  });
+
+  it('should show correct moves after 1. e4 e6', () => {
+    const variations = getOpeningsByFamily('French Defense');
+    const tree = buildVariationTree(variations, 'French Defense');
+
+    const moveHistory = [
+      createMoveEntry('e4', 'white', 1),
+      createMoveEntry('e6', 'black', 1),
+    ];
+
+    const possibleMoves = getAllPossibleNextMoves(tree, moveHistory);
+
+    console.log('After 1. e4 e6, possible 2nd moves for White:');
+    console.log(possibleMoves.map(m => m.move).join(', '));
+
+    // White should have d4 as an option
+    const moveNames = possibleMoves.map(m => m.move);
+    expect(moveNames).toContain('d4');
+  });
+
+  it('should show correct moves after 1. e4 e6 2. d4', () => {
+    const variations = getOpeningsByFamily('French Defense');
+    const tree = buildVariationTree(variations, 'French Defense');
+
+    const moveHistory = [
+      createMoveEntry('e4', 'white', 1),
+      createMoveEntry('e6', 'black', 1),
+      createMoveEntry('d4', 'white', 2),
+    ];
+
+    const possibleMoves = getAllPossibleNextMoves(tree, moveHistory);
+
+    console.log('After 1. e4 e6 2. d4, possible moves for Black:');
+    console.log(possibleMoves.map(m => m.move).join(', '));
+
+    // Black should have d5 as the main option
+    const moveNames = possibleMoves.map(m => m.move);
+    expect(moveNames).toContain('d5');
+  });
+
+  it('should show correct moves after 1. e4 e6 2. d4 d5', () => {
+    const variations = getOpeningsByFamily('French Defense');
+    const tree = buildVariationTree(variations, 'French Defense');
+
+    const moveHistory = [
+      createMoveEntry('e4', 'white', 1),
+      createMoveEntry('e6', 'black', 1),
+      createMoveEntry('d4', 'white', 2),
+      createMoveEntry('d5', 'black', 2),
+    ];
+
+    const possibleMoves = getAllPossibleNextMoves(tree, moveHistory);
+
+    console.log('After 1. e4 e6 2. d4 d5, possible 3rd moves for White:');
+    const moveNames = possibleMoves.map(m => m.move).sort();
+    console.log(moveNames.join(', '));
+
+    // These are the moves from the earlier test
+    const expectedMoves = ['Nd2', 'Nc3', 'e5', 'exd5', 'Qe2', 'Nf3', 'c4', 'Be3', 'Nh3', 'Bd3'];
+
+    expectedMoves.forEach(move => {
+      expect(moveNames).toContain(move);
+    });
+
+    // Make sure we don't have any random moves
+    expect(moveNames.length).toBeGreaterThan(0);
+    console.log(`Total ${moveNames.length} possible moves found`);
+  });
+
+  it('should parse moves correctly from opening string', () => {
+    // Test the parseMoveSequence function
+    const testOpening = '1. e4 e6 2. d4 d5 3. Nd2';
+    const moves = parseMoveSequence(testOpening);
+
+    console.log('Parsed moves from "1. e4 e6 2. d4 d5 3. Nd2":');
+    console.log(moves);
+
+    expect(moves).toEqual(['e4', 'e6', 'd4', 'd5', 'Nd2']);
+  });
+});

src/lib/openingTrainer/__tests__/gameLogic.test.ts

@@ -29,6 +29,7 @@ const mockOpening: OpeningMetadata = {
   eco: 'C00',
   name: 'French Defense',
   moves: '1. e4 e6 2. d4 d5',
+  src: 'test',
   wikipediaSlug: 'French_Defence',
 };
 
@@ -36,6 +37,7 @@ const mockBlackOpening: OpeningMetadata = {
   eco: 'D00',
   name: "Queen's Pawn Opening",
   moves: '1. d4 d5',
+  src: 'test',
   wikipediaSlug: 'Queens_Pawn_Game',
 };
 

src/lib/openingTrainer/__tests__/openingLoader.test.ts

@@ -0,0 +1,83 @@
+import { getOpeningsByFamily, getAllOpenings } from '../openingLoader';
+
+describe('openingLoader - French Defense', () => {
+  it('should load French Defense variations', () => {
+    const frenchVariations = getOpeningsByFamily('French Defense');
+
+    console.log('French Defense variations found:', frenchVariations.length);
+    console.log('First 5 variations:');
+    frenchVariations.slice(0, 5).forEach(v => {
+      console.log(`  - ${v.name} (${v.eco}): ${v.moves}`);
+    });
+
+    expect(frenchVariations.length).toBeGreaterThan(0);
+  });
+
+  it('should have moves starting with e4 e6', () => {
+    const frenchVariations = getOpeningsByFamily('French Defense');
+
+    // All French Defense variations should start with 1. e4 e6 (allowing for extra spaces)
+    const allStartCorrectly = frenchVariations.every(v => {
+      const normalized = v.moves.replace(/\s+/g, ' ').trim();
+      return normalized.startsWith('1. e4 e6') || normalized.startsWith('1. e4 c5'); // Marshall Gambit starts differently
+    });
+
+    if (!allStartCorrectly) {
+      console.log('Variations NOT starting with e4 e6:');
+      frenchVariations
+        .filter(v => {
+          const normalized = v.moves.replace(/\s+/g, ' ').trim();
+          return !normalized.startsWith('1. e4 e6') && !normalized.startsWith('1. e4 c5');
+        })
+        .slice(0, 3)
+        .forEach(v => {
+          console.log(`  - ${v.name}: ${v.moves}`);
+        });
+    }
+
+    expect(allStartCorrectly).toBe(true);
+  });
+
+  it('should find variation after 1. e4 e6 2. d4', () => {
+    const frenchVariations = getOpeningsByFamily('French Defense');
+
+    // Find variations that have at least 2. d4
+    const withD4 = frenchVariations.filter(v =>
+      v.moves.includes('2. d4')
+    );
+
+    console.log(`Variations with 2. d4: ${withD4.length}`);
+    console.log('Examples:');
+    withD4.slice(0, 5).forEach(v => {
+      console.log(`  - ${v.name}: ${v.moves.split(' ').slice(0, 8).join(' ')}...`);
+    });
+
+    expect(withD4.length).toBeGreaterThan(0);
+  });
+
+  it('should show what moves are available after 1. e4 e6 2. d4 d5', () => {
+    const frenchVariations = getOpeningsByFamily('French Defense');
+
+    // Find all variations with 1. e4 e6 2. d4 d5
+    const afterD5 = frenchVariations.filter(v =>
+      v.moves.startsWith('1. e4 e6 2. d4 d5')
+    );
+
+    console.log(`Variations after 1. e4 e6 2. d4 d5: ${afterD5.length}`);
+
+    // Get all possible 3rd moves for White
+    const thirdMoves = new Set<string>();
+    afterD5.forEach(v => {
+      const moves = v.moves.split(' ');
+      // Find "3." and get the next move
+      const thirdMoveIndex = moves.findIndex(m => m === '3.');
+      if (thirdMoveIndex >= 0 && moves[thirdMoveIndex + 1]) {
+        thirdMoves.add(moves[thirdMoveIndex + 1]);
+      }
+    });
+
+    console.log('Possible 3rd moves for White:', Array.from(thirdMoves).join(', '));
+
+    expect(thirdMoves.size).toBeGreaterThan(0);
+  });
+});

src/lib/openingTrainer/__tests__/sessionOrchestrator.test.ts

@@ -52,6 +52,7 @@ const mockOpening: OpeningMetadata = {
   eco: 'C00',
   name: 'French Defense',
   moves: '1. e4 e6 2. d4 d5',
+  src: 'test',
   wikipediaSlug: 'French_Defence',
 };
 

src/lib/openingTrainer/__tests__/sessionReducer.test.ts

@@ -20,6 +20,7 @@ const mockOpening: OpeningMetadata = {
   eco: 'C00',
   name: 'French Defense',
   moves: '1. e4 e6 2. d4 d5',
+  src: 'test',
   wikipediaSlug: 'French_Defence',
 };
 
@@ -27,6 +28,7 @@ const mockBlackOpening: OpeningMetadata = {
   eco: 'D00',
   name: "Queen's Pawn",
   moves: '1. d4 d5',
+  src: 'test',
 };
 
 function createMockMove(

src/lib/openingTrainer/gameLogic.ts

@@ -434,3 +434,221 @@ export function shouldUseWikipediaContext(opening: OpeningMetadata): boolean {
   // Use Wikipedia if available and not too obscure
   return hasWikipediaPage(opening);
 }
+
+// ============================================================================
+// Multi-Variation Support (Family Training)
+// ============================================================================
+
+/**
+ * Node in the variation tree
+ * Each node represents a position after a move, with children for possible continuations
+ */
+export interface VariationTreeNode {
+  move: string; // SAN notation of the move leading to this position
+  children: Map<string, VariationTreeNode>; // key = SAN, value = child node
+  variations: OpeningMetadata[]; // Openings that pass through this position
+  isEndOfLine: boolean; // True if this is the end of at least one variation
+}
+
+/**
+ * Root of the variation tree (starting position)
+ */
+export interface VariationTree {
+  children: Map<string, VariationTreeNode>;
+  allVariations: OpeningMetadata[];
+  familyName: string;
+}
+
+/**
+ * Build a variation tree from multiple openings
+ * This allows efficient lookup of which variations are still possible
+ */
+export function buildVariationTree(variations: OpeningMetadata[], familyName: string): VariationTree {
+  const tree: VariationTree = {
+    children: new Map(),
+    allVariations: variations,
+    familyName,
+  };
+
+  for (const opening of variations) {
+    const moves = parseMoveSequence(opening.moves);
+    let currentChildren = tree.children;
+
+    for (let i = 0; i < moves.length; i++) {
+      const move = moves[i];
+      const isLast = i === moves.length - 1;
+
+      if (!currentChildren.has(move)) {
+        currentChildren.set(move, {
+          move,
+          children: new Map(),
+          variations: [],
+          isEndOfLine: false,
+        });
+      }
+
+      const node = currentChildren.get(move)!;
+      node.variations.push(opening);
+
+      if (isLast) {
+        node.isEndOfLine = true;
+      }
+
+      currentChildren = node.children;
+    }
+  }
+
+  return tree;
+}
+
+/**
+ * Get the node at a specific position in the variation tree
+ * Returns null if the move sequence doesn't exist in any variation
+ */
+export function getTreeNodeAtPosition(
+  tree: VariationTree,
+  moveHistory: MoveHistoryEntry[]
+): VariationTreeNode | null {
+  if (moveHistory.length === 0) {
+    // Return a virtual root node
+    return {
+      move: '',
+      children: tree.children,
+      variations: tree.allVariations,
+      isEndOfLine: false,
+    };
+  }
+
+  let currentChildren = tree.children;
+  let currentNode: VariationTreeNode | null = null;
+
+  for (const entry of moveHistory) {
+    const node = currentChildren.get(entry.san);
+    if (!node) {
+      return null; // Move sequence not in any variation
+    }
+    currentNode = node;
+    currentChildren = node.children;
+  }
+
+  return currentNode;
+}
+
+/**
+ * Get all variations that match the current move history
+ */
+export function getMatchingVariations(
+  tree: VariationTree,
+  moveHistory: MoveHistoryEntry[]
+): OpeningMetadata[] {
+  const node = getTreeNodeAtPosition(tree, moveHistory);
+  return node ? node.variations : [];
+}
+
+/**
+ * Get all possible next moves from the current position across all matching variations
+ * Returns moves with their associated variations
+ */
+export function getAllPossibleNextMoves(
+  tree: VariationTree,
+  moveHistory: MoveHistoryEntry[]
+): Array<{ move: string; variations: OpeningMetadata[] }> {
+  const node = getTreeNodeAtPosition(tree, moveHistory);
+  if (!node) return [];
+
+  const result: Array<{ move: string; variations: OpeningMetadata[] }> = [];
+
+  for (const [move, childNode] of node.children) {
+    result.push({
+      move,
+      variations: childNode.variations,
+    });
+  }
+
+  return result;
+}
+
+/**
+ * Check if a move is in any of the loaded variations
+ */
+export function isMoveInVariationTree(
+  tree: VariationTree,
+  moveHistory: MoveHistoryEntry[],
+  proposedMove: string
+): boolean {
+  const node = getTreeNodeAtPosition(tree, moveHistory);
+  if (!node) return false;
+  return node.children.has(proposedMove);
+}
+
+/**
+ * Get the specific variation name(s) that match the exact move sequence
+ * This identifies which variation the user is currently playing
+ */
+export function identifyCurrentVariation(
+  tree: VariationTree,
+  moveHistory: MoveHistoryEntry[]
+): { exact: OpeningMetadata[]; possible: OpeningMetadata[] } {
+  const node = getTreeNodeAtPosition(tree, moveHistory);
+  if (!node) {
+    return { exact: [], possible: [] };
+  }
+
+  // Exact matches: variations that end exactly at this position
+  const exact = node.variations.filter(v => {
+    const moves = parseMoveSequence(v.moves);
+    return moves.length === moveHistory.length;
+  });
+
+  // Possible: variations that could continue from here
+  const possible = node.variations.filter(v => {
+    const moves = parseMoveSequence(v.moves);
+    return moves.length > moveHistory.length;
+  });
+
+  return { exact, possible };
+}
+
+/**
+ * Check if we're still in theory (any variation)
+ */
+export function isInAnyVariation(
+  tree: VariationTree,
+  moveHistory: MoveHistoryEntry[]
+): boolean {
+  return getTreeNodeAtPosition(tree, moveHistory) !== null;
+}
+
+/**
+ * Get a human-readable description of the current position in the variation tree
+ */
+export function describeCurrentPosition(
+  tree: VariationTree,
+  moveHistory: MoveHistoryEntry[]
+): {
+  matchingCount: number;
+  nextMoves: string[];
+  currentVariationNames: string[];
+  isEndOfLine: boolean;
+} {
+  const node = getTreeNodeAtPosition(tree, moveHistory);
+
+  if (!node) {
+    return {
+      matchingCount: 0,
+      nextMoves: [],
+      currentVariationNames: [],
+      isEndOfLine: false,
+    };
+  }
+
+  const nextMoves = Array.from(node.children.keys());
+  const variationNames = [...new Set(node.variations.map(v => v.name))];
+
+  return {
+    matchingCount: node.variations.length,
+    nextMoves,
+    currentVariationNames: variationNames,
+    isEndOfLine: node.isEndOfLine && nextMoves.length === 0,
+  };
+}

src/lib/openingTrainer/openingLoader.ts

@@ -83,3 +83,47 @@ export function getAllOpeningsByFen(): Record<string, OpeningMetadata> {
 export function getAllOpeningsByEco(): Record<string, OpeningMetadata> {
   return OPENINGS_BY_ECO;
 }
+
+/**
+ * Extract the family name from an opening name
+ */
+function extractFamilyName(openingName: string): string {
+  const separators = [':', ',', '–', '—', ' - '];
+  for (const sep of separators) {
+    if (openingName.includes(sep)) {
+      return openingName.split(sep)[0].trim();
+    }
+  }
+  // Handle "Queen's Gambit Declined" -> "Queen's Gambit"
+  if (openingName.includes('Declined') || openingName.includes('Accepted')) {
+    return openingName.replace(/\s+(Declined|Accepted).*$/, '').trim();
+  }
+  return openingName;
+}
+
+/**
+ * Count moves in an opening's move string
+ */
+function countMoves(movesString: string): number {
+  if (!movesString) return 0;
+  return movesString.split(' ').filter(m => !m.match(/^\d+\.$/)).length;
+}
+
+/**
+ * Get all openings belonging to a specific family
+ * Returns variations sorted by move count (most moves first)
+ */
+export function getOpeningsByFamily(familyName: string): OpeningMetadata[] {
+  return OPENINGS_ARRAY
+    .filter((opening) => {
+      const family = extractFamilyName(opening.name);
+      return family === familyName && countMoves(opening.moves) > 1;
+    })
+    .sort((a, b) => {
+      // Sort by move count descending (more moves = deeper line)
+      const movesA = countMoves(a.moves);
+      const movesB = countMoves(b.moves);
+      if (movesA !== movesB) return movesB - movesA;
+      return a.eco.localeCompare(b.eco);
+    });
+}

src/lib/openingTrainer/sessionReducer.ts

@@ -93,6 +93,7 @@ export type SessionAction =
   | { type: 'NAVIGATE_PREVIOUS' }
   | { type: 'NAVIGATE_NEXT' }
   | { type: 'NAVIGATE_TO_CURRENT' } // Jump back to end of history
+  | { type: 'UNDO_TO_MOVE'; index: number } // Navigate and truncate history
 
   // Theory tracking
   | { type: 'DEVIATION_DETECTED'; moveIndex: number }
@@ -348,6 +349,47 @@ export function sessionReducer(
       });
     }
 
+    case 'UNDO_TO_MOVE': {
+      const { index } = action;
+
+      // Clamp index to valid range (-1 means start position, truncate all moves)
+      const clampedIndex = Math.max(-1, Math.min(index, state.moveHistory.length - 1));
+
+      // Truncate move history to this point
+      const newHistory = clampedIndex < 0 ? [] : state.moveHistory.slice(0, clampedIndex + 1);
+
+      // Build FEN at target index
+      const newFEN = buildFenAtIndex(newHistory, newHistory.length);
+
+      // Reset deviation if we're now back in theory
+      const isNowInTheory = isInTheory(state.opening, newHistory);
+      const newDeviationIndex = isNowInTheory ? null : state.deviationMoveIndex;
+
+      // Determine phase
+      let phase: SessionPhase;
+      if (newDeviationIndex !== null) {
+        phase = 'off_book';
+      } else if (isEndOfRepertoire(state.opening, newHistory.length)) {
+        phase = 'end_of_repertoire';
+      } else if (isOpponentTurn(state.opening, newHistory)) {
+        phase = 'opponent_turn';
+      } else {
+        phase = 'user_turn';
+      }
+
+      return {
+        ...state,
+        moveHistory: newHistory,
+        currentMoveIndex: newHistory.length,
+        currentFEN: newFEN,
+        deviationMoveIndex: newDeviationIndex,
+        isInTheory: isNowInTheory,
+        phase,
+        pendingOpponentMove: null,
+        lastUpdatedAt: Date.now(),
+      };
+    }
+
     case 'NAVIGATE_TO_CURRENT': {
       // Jump to the end of history (current position)
       const atEnd = state.currentMoveIndex === state.moveHistory.length;