Finds the most complete/reliable generation

2 files changed, 585 insertions, 53 deletions

diff --git a/weed/worker/tasks/ec_vacuum/ec_vacuum_logic.go b/weed/worker/tasks/ec_vacuum/ec_vacuum_logic.go
index 7ef8a92db..f110cba5c 100644
--- a/weed/worker/tasks/ec_vacuum/ec_vacuum_logic.go
+++ b/weed/worker/tasks/ec_vacuum/ec_vacuum_logic.go
@@ -45,6 +45,7 @@ type VacuumPlan struct {
 }
 
 // DetermineGenerationsFromParams extracts generation information from task parameters
+// Now supports multiple generations and finds the most complete one for vacuum
 func (logic *EcVacuumLogic) DetermineGenerationsFromParams(params *worker_pb.TaskParams) (sourceGen, targetGen uint32, err error) {
 	if params == nil {
 		return 0, 0, fmt.Errorf("task parameters cannot be nil")
@@ -55,29 +56,27 @@ func (logic *EcVacuumLogic) DetermineGenerationsFromParams(params *worker_pb.Tas
 		return 0, 1, nil
 	}
 
-	// Use generation from first source (all sources should have same generation)
-	if params.Sources[0].Generation > 0 {
-		sourceGen = params.Sources[0].Generation
-		targetGen = sourceGen + 1
-	} else {
-		// Generation 0 case
-		sourceGen = 0
-		targetGen = 1
+	// Group sources by generation and analyze completeness
+	generationAnalysis, err := logic.AnalyzeGenerationCompleteness(params)
+	if err != nil {
+		return 0, 0, fmt.Errorf("failed to analyze generation completeness: %w", err)
 	}
 
-	// Validate consistency - all sources should have the same generation
-	for i, source := range params.Sources {
-		if source.Generation != sourceGen {
-			return 0, 0, fmt.Errorf("inconsistent generations in sources: source[0]=%d, source[%d]=%d",
-				sourceGen, i, source.Generation)
-		}
+	// Find the most complete generation that can be used for reconstruction
+	mostCompleteGen, found := logic.FindMostCompleteGeneration(generationAnalysis)
+	if !found {
+		return 0, 0, fmt.Errorf("no generation has sufficient shards for reconstruction")
 	}
 
-	return sourceGen, targetGen, nil
+	// Target generation is max(all generations) + 1
+	maxGen := logic.FindMaxGeneration(generationAnalysis)
+	targetGen = maxGen + 1
+
+	return mostCompleteGen, targetGen, nil
 }
 
-// ParseSourceNodes extracts source node information from task parameters
-func (logic *EcVacuumLogic) ParseSourceNodes(params *worker_pb.TaskParams) (map[pb.ServerAddress]erasure_coding.ShardBits, error) {
+// ParseSourceNodes extracts source node information from task parameters for a specific generation
+func (logic *EcVacuumLogic) ParseSourceNodes(params *worker_pb.TaskParams, targetGeneration uint32) (map[pb.ServerAddress]erasure_coding.ShardBits, error) {
 	if params == nil {
 		return nil, fmt.Errorf("task parameters cannot be nil")
 	}
@@ -85,7 +84,7 @@ func (logic *EcVacuumLogic) ParseSourceNodes(params *worker_pb.TaskParams) (map[
 	sourceNodes := make(map[pb.ServerAddress]erasure_coding.ShardBits)
 
 	for _, source := range params.Sources {
-		if source.Node == "" {
+		if source.Node == "" || source.Generation != targetGeneration {
 			continue
 		}
 
@@ -105,7 +104,7 @@ func (logic *EcVacuumLogic) ParseSourceNodes(params *worker_pb.TaskParams) (map[
 	}
 
 	if len(sourceNodes) == 0 {
-		return nil, fmt.Errorf("no valid source nodes found: sources=%d", len(params.Sources))
+		return nil, fmt.Errorf("no valid source nodes found for generation %d: sources=%d", targetGeneration, len(params.Sources))
 	}
 
 	return sourceNodes, nil
@@ -113,14 +112,14 @@ func (logic *EcVacuumLogic) ParseSourceNodes(params *worker_pb.TaskParams) (map[
 
 // CreateVacuumPlan creates a comprehensive plan for the EC vacuum operation
 func (logic *EcVacuumLogic) CreateVacuumPlan(volumeID uint32, collection string, params *worker_pb.TaskParams) (*VacuumPlan, error) {
-	// Extract generations
+	// Extract generations and analyze completeness
 	sourceGen, targetGen, err := logic.DetermineGenerationsFromParams(params)
 	if err != nil {
 		return nil, fmt.Errorf("failed to determine generations: %w", err)
 	}
 
-	// Parse source nodes
-	sourceNodes, err := logic.ParseSourceNodes(params)
+	// Parse source nodes from the selected generation
+	sourceNodes, err := logic.ParseSourceNodes(params, sourceGen)
 	if err != nil {
 		return nil, fmt.Errorf("failed to parse source nodes: %w", err)
 	}
@@ -137,8 +136,18 @@ func (logic *EcVacuumLogic) CreateVacuumPlan(volumeID uint32, collection string,
 		Nodes:      sourceNodes, // Same nodes, new generation
 	}
 
-	// Determine what to cleanup (simplified: just source generation)
-	generationsToCleanup := []uint32{sourceGen}
+	// Get all available generations for cleanup calculation
+	generationAnalysis, err := logic.AnalyzeGenerationCompleteness(params)
+	if err != nil {
+		return nil, fmt.Errorf("failed to analyze generations for cleanup: %w", err)
+	}
+
+	// All generations except target should be cleaned up
+	var allGenerations []uint32
+	for generation := range generationAnalysis {
+		allGenerations = append(allGenerations, generation)
+	}
+	generationsToCleanup := logic.CalculateCleanupGenerations(sourceGen, targetGen, allGenerations)
 
 	// Generate safety checks
 	safetyChecks := logic.generateSafetyChecks(sourceDistribution, targetGen)
@@ -243,6 +252,100 @@ type CleanupImpact struct {
 	ShardsToDelete       int
 }
 
+// GenerationAnalysis represents the analysis of shard completeness per generation
+type GenerationAnalysis struct {
+	Generation     uint32
+	ShardBits      erasure_coding.ShardBits
+	ShardCount     int
+	Nodes          map[pb.ServerAddress]erasure_coding.ShardBits
+	CanReconstruct bool // Whether this generation has enough shards for reconstruction
+}
+
+// AnalyzeGenerationCompleteness analyzes each generation's shard completeness
+func (logic *EcVacuumLogic) AnalyzeGenerationCompleteness(params *worker_pb.TaskParams) (map[uint32]*GenerationAnalysis, error) {
+	if params == nil {
+		return nil, fmt.Errorf("task parameters cannot be nil")
+	}
+
+	generationMap := make(map[uint32]*GenerationAnalysis)
+
+	// Group sources by generation
+	for _, source := range params.Sources {
+		if source.Node == "" {
+			continue
+		}
+
+		generation := source.Generation
+		if _, exists := generationMap[generation]; !exists {
+			generationMap[generation] = &GenerationAnalysis{
+				Generation: generation,
+				ShardBits:  erasure_coding.ShardBits(0),
+				Nodes:      make(map[pb.ServerAddress]erasure_coding.ShardBits),
+			}
+		}
+
+		analysis := generationMap[generation]
+		serverAddr := pb.ServerAddress(source.Node)
+		var shardBits erasure_coding.ShardBits
+
+		// Convert shard IDs to ShardBits
+		for _, shardId := range source.ShardIds {
+			if shardId < erasure_coding.TotalShardsCount {
+				shardBits = shardBits.AddShardId(erasure_coding.ShardId(shardId))
+			}
+		}
+
+		if shardBits.ShardIdCount() > 0 {
+			analysis.Nodes[serverAddr] = shardBits
+			analysis.ShardBits = analysis.ShardBits.Plus(shardBits)
+		}
+	}
+
+	// Calculate completeness for each generation
+	for _, analysis := range generationMap {
+		analysis.ShardCount = analysis.ShardBits.ShardIdCount()
+		analysis.CanReconstruct = analysis.ShardCount >= erasure_coding.DataShardsCount
+	}
+
+	return generationMap, nil
+}
+
+// FindMostCompleteGeneration finds the generation with the most complete set of shards
+// that can be used for reconstruction
+func (logic *EcVacuumLogic) FindMostCompleteGeneration(generationMap map[uint32]*GenerationAnalysis) (uint32, bool) {
+	var bestGeneration uint32
+	var bestShardCount int
+	found := false
+
+	for generation, analysis := range generationMap {
+		// Only consider generations that can reconstruct
+		if !analysis.CanReconstruct {
+			continue
+		}
+
+		// Prefer the generation with the most shards, or if tied, the highest generation number
+		if !found || analysis.ShardCount > bestShardCount ||
+			(analysis.ShardCount == bestShardCount && generation > bestGeneration) {
+			bestGeneration = generation
+			bestShardCount = analysis.ShardCount
+			found = true
+		}
+	}
+
+	return bestGeneration, found
+}
+
+// FindMaxGeneration finds the highest generation number among all available generations
+func (logic *EcVacuumLogic) FindMaxGeneration(generationMap map[uint32]*GenerationAnalysis) uint32 {
+	var maxGen uint32
+	for generation := range generationMap {
+		if generation > maxGen {
+			maxGen = generation
+		}
+	}
+	return maxGen
+}
+
 // countShardsToDelete counts how many shard files will be deleted
 func (logic *EcVacuumLogic) countShardsToDelete(plan *VacuumPlan) int {
 	totalShards := 0
diff --git a/weed/worker/tasks/ec_vacuum/ec_vacuum_logic_test.go b/weed/worker/tasks/ec_vacuum/ec_vacuum_logic_test.go
index e4bc242fa..60de16b05 100644
--- a/weed/worker/tasks/ec_vacuum/ec_vacuum_logic_test.go
+++ b/weed/worker/tasks/ec_vacuum/ec_vacuum_logic_test.go
@@ -35,7 +35,11 @@ func TestDetermineGenerationsFromParams(t *testing.T) {
 			name: "generation 0 source",
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{
-					{Generation: 0},
+					{
+						Node:       "node1:8080",
+						Generation: 0,
+						ShardIds:   []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, // 10 shards - sufficient
+					},
 				},
 			},
 			expectSrc: 0,
@@ -45,7 +49,11 @@ func TestDetermineGenerationsFromParams(t *testing.T) {
 			name: "generation 1 source",
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{
-					{Generation: 1},
+					{
+						Node:       "node1:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, // 10 shards - sufficient
+					},
 				},
 			},
 			expectSrc: 1,
@@ -55,29 +63,54 @@ func TestDetermineGenerationsFromParams(t *testing.T) {
 			name: "generation 5 source",
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{
-					{Generation: 5},
+					{
+						Node:       "node1:8080",
+						Generation: 5,
+						ShardIds:   []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, // 10 shards - sufficient
+					},
 				},
 			},
 			expectSrc: 5,
 			expectTgt: 6,
 		},
 		{
-			name: "inconsistent generations",
+			name: "multiple generations - finds most complete",
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{
-					{Generation: 1},
-					{Generation: 2}, // Different generation!
+					{
+						Node:       "node1:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2}, // Only 3 shards - insufficient
+					},
+					{
+						Node:       "node2:8080",
+						Generation: 2,
+						ShardIds:   []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, // 10 shards - sufficient
+					},
 				},
 			},
-			expectError: true,
+			expectSrc: 2, // Should pick generation 2 (most complete)
+			expectTgt: 3, // Target should be max(1,2) + 1 = 3
 		},
 		{
 			name: "multiple sources same generation",
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{
-					{Generation: 3},
-					{Generation: 3},
-					{Generation: 3},
+					{
+						Node:       "node1:8080",
+						Generation: 3,
+						ShardIds:   []uint32{0, 1, 2, 3, 4},
+					},
+					{
+						Node:       "node2:8080",
+						Generation: 3,
+						ShardIds:   []uint32{5, 6, 7, 8, 9}, // Combined = 10 shards - sufficient
+					},
+					{
+						Node:       "node3:8080",
+						Generation: 3,
+						ShardIds:   []uint32{10, 11, 12, 13},
+					},
 				},
 			},
 			expectSrc: 3,
@@ -118,6 +151,7 @@ func TestParseSourceNodes(t *testing.T) {
 	tests := []struct {
 		name         string
 		params       *worker_pb.TaskParams
+		generation   uint32
 		expectNodes  int
 		expectShards map[string][]int // node -> shard IDs
 		expectError  bool
@@ -125,6 +159,7 @@ func TestParseSourceNodes(t *testing.T) {
 		{
 			name:        "nil params",
 			params:      nil,
+			generation:  0,
 			expectError: true,
 		},
 		{
@@ -132,6 +167,7 @@ func TestParseSourceNodes(t *testing.T) {
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{},
 			},
+			generation:  0,
 			expectError: true,
 		},
 		{
@@ -139,11 +175,13 @@ func TestParseSourceNodes(t *testing.T) {
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{
 					{
-						Node:     "node1:8080",
-						ShardIds: []uint32{0, 1, 2, 3, 4, 5},
+						Node:       "node1:8080",
+						Generation: 0,
+						ShardIds:   []uint32{0, 1, 2, 3, 4, 5},
 					},
 				},
 			},
+			generation:  0,
 			expectNodes: 1,
 			expectShards: map[string][]int{
 				"node1:8080": {0, 1, 2, 3, 4, 5},
@@ -154,19 +192,23 @@ func TestParseSourceNodes(t *testing.T) {
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{
 					{
-						Node:     "node1:8080",
-						ShardIds: []uint32{0, 1, 2, 3, 4},
+						Node:       "node1:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2, 3, 4},
 					},
 					{
-						Node:     "node2:8080",
-						ShardIds: []uint32{5, 6, 7, 8, 9},
+						Node:       "node2:8080",
+						Generation: 1,
+						ShardIds:   []uint32{5, 6, 7, 8, 9},
 					},
 					{
-						Node:     "node3:8080",
-						ShardIds: []uint32{10, 11, 12, 13},
+						Node:       "node3:8080",
+						Generation: 1,
+						ShardIds:   []uint32{10, 11, 12, 13},
 					},
 				},
 			},
+			generation:  1,
 			expectNodes: 3,
 			expectShards: map[string][]int{
 				"node1:8080": {0, 1, 2, 3, 4},
@@ -179,15 +221,18 @@ func TestParseSourceNodes(t *testing.T) {
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{
 					{
-						Node:     "node1:8080",
-						ShardIds: []uint32{0, 1, 2},
+						Node:       "node1:8080",
+						Generation: 2,
+						ShardIds:   []uint32{0, 1, 2},
 					},
 					{
-						Node:     "node2:8080",
-						ShardIds: []uint32{0, 3, 4}, // Shard 0 is on both nodes
+						Node:       "node2:8080",
+						Generation: 2,
+						ShardIds:   []uint32{0, 3, 4}, // Shard 0 is on both nodes
 					},
 				},
 			},
+			generation:  2,
 			expectNodes: 2,
 			expectShards: map[string][]int{
 				"node1:8080": {0, 1, 2},
@@ -199,15 +244,18 @@ func TestParseSourceNodes(t *testing.T) {
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{
 					{
-						Node:     "",
-						ShardIds: []uint32{0, 1, 2},
+						Node:       "",
+						Generation: 3,
+						ShardIds:   []uint32{0, 1, 2},
 					},
 					{
-						Node:     "node1:8080",
-						ShardIds: []uint32{3, 4, 5},
+						Node:       "node1:8080",
+						Generation: 3,
+						ShardIds:   []uint32{3, 4, 5},
 					},
 				},
 			},
+			generation:  3,
 			expectNodes: 1,
 			expectShards: map[string][]int{
 				"node1:8080": {3, 4, 5},
@@ -218,21 +266,51 @@ func TestParseSourceNodes(t *testing.T) {
 			params: &worker_pb.TaskParams{
 				Sources: []*worker_pb.TaskSource{
 					{
-						Node:     "node1:8080",
-						ShardIds: []uint32{0, 1, 14, 15, 100}, // 14+ are invalid
+						Node:       "node1:8080",
+						Generation: 4,
+						ShardIds:   []uint32{0, 1, 14, 15, 100}, // 14+ are invalid
 					},
 				},
 			},
+			generation:  4,
 			expectNodes: 1,
 			expectShards: map[string][]int{
 				"node1:8080": {0, 1}, // Only valid shards
 			},
 		},
+		{
+			name: "filter by generation - only matching generation",
+			params: &worker_pb.TaskParams{
+				Sources: []*worker_pb.TaskSource{
+					{
+						Node:       "node1:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2},
+					},
+					{
+						Node:       "node2:8080",
+						Generation: 2, // Different generation - should be ignored
+						ShardIds:   []uint32{3, 4, 5},
+					},
+					{
+						Node:       "node3:8080",
+						Generation: 1, // Same generation - should be included
+						ShardIds:   []uint32{6, 7, 8},
+					},
+				},
+			},
+			generation:  1,
+			expectNodes: 2,
+			expectShards: map[string][]int{
+				"node1:8080": {0, 1, 2},
+				"node3:8080": {6, 7, 8},
+			},
+		},
 	}
 
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
-			sourceNodes, err := logic.ParseSourceNodes(tt.params)
+			sourceNodes, err := logic.ParseSourceNodes(tt.params, tt.generation)
 
 			if tt.expectError {
 				if err == nil {
@@ -685,3 +763,354 @@ func createRealisticTopologyTest(t *testing.T) {
 func TestRealisticTopologyScenarios(t *testing.T) {
 	t.Run("3-node distributed shards", createRealisticTopologyTest)
 }
+
+func TestAnalyzeGenerationCompleteness(t *testing.T) {
+	logic := NewEcVacuumLogic()
+
+	tests := []struct {
+		name                   string
+		params                 *worker_pb.TaskParams
+		expectedGenerations    []uint32
+		expectedCanReconstruct map[uint32]bool
+		expectError            bool
+	}{
+		{
+			name:        "nil params",
+			params:      nil,
+			expectError: true,
+		},
+		{
+			name: "single generation sufficient shards",
+			params: &worker_pb.TaskParams{
+				Sources: []*worker_pb.TaskSource{
+					{
+						Node:       "node1:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, // 10 shards = sufficient
+					},
+				},
+			},
+			expectedGenerations:    []uint32{1},
+			expectedCanReconstruct: map[uint32]bool{1: true},
+		},
+		{
+			name: "single generation insufficient shards",
+			params: &worker_pb.TaskParams{
+				Sources: []*worker_pb.TaskSource{
+					{
+						Node:       "node1:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2}, // Only 3 shards = insufficient
+					},
+				},
+			},
+			expectedGenerations:    []uint32{1},
+			expectedCanReconstruct: map[uint32]bool{1: false},
+		},
+		{
+			name: "multiple generations mixed completeness",
+			params: &worker_pb.TaskParams{
+				Sources: []*worker_pb.TaskSource{
+					{
+						Node:       "node1:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2}, // 3 shards - insufficient
+					},
+					{
+						Node:       "node2:8080",
+						Generation: 2,
+						ShardIds:   []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, // 10 shards - sufficient
+					},
+					{
+						Node:       "node3:8080",
+						Generation: 3,
+						ShardIds:   []uint32{0, 1, 2, 3, 4, 5}, // 6 shards - insufficient
+					},
+				},
+			},
+			expectedGenerations:    []uint32{1, 2, 3},
+			expectedCanReconstruct: map[uint32]bool{1: false, 2: true, 3: false},
+		},
+		{
+			name: "multiple nodes same generation",
+			params: &worker_pb.TaskParams{
+				Sources: []*worker_pb.TaskSource{
+					{
+						Node:       "node1:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2, 3, 4},
+					},
+					{
+						Node:       "node2:8080",
+						Generation: 1,
+						ShardIds:   []uint32{5, 6, 7, 8, 9}, // Together = 10 shards = sufficient
+					},
+				},
+			},
+			expectedGenerations:    []uint32{1},
+			expectedCanReconstruct: map[uint32]bool{1: true},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			analysis, err := logic.AnalyzeGenerationCompleteness(tt.params)
+
+			if tt.expectError {
+				if err == nil {
+					t.Errorf("expected error but got none")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Errorf("unexpected error: %v", err)
+				return
+			}
+
+			// Check we have the expected generations
+			if len(analysis) != len(tt.expectedGenerations) {
+				t.Errorf("generation count: expected %d, got %d", len(tt.expectedGenerations), len(analysis))
+				return
+			}
+
+			for _, expectedGen := range tt.expectedGenerations {
+				genAnalysis, exists := analysis[expectedGen]
+				if !exists {
+					t.Errorf("expected generation %d not found", expectedGen)
+					continue
+				}
+
+				expectedCanReconstruct := tt.expectedCanReconstruct[expectedGen]
+				if genAnalysis.CanReconstruct != expectedCanReconstruct {
+					t.Errorf("generation %d CanReconstruct: expected %v, got %v",
+						expectedGen, expectedCanReconstruct, genAnalysis.CanReconstruct)
+				}
+			}
+		})
+	}
+}
+
+func TestFindMostCompleteGeneration(t *testing.T) {
+	logic := NewEcVacuumLogic()
+
+	tests := []struct {
+		name               string
+		generationAnalysis map[uint32]*GenerationAnalysis
+		expectedGeneration uint32
+		expectedFound      bool
+	}{
+		{
+			name:               "empty analysis",
+			generationAnalysis: map[uint32]*GenerationAnalysis{},
+			expectedFound:      false,
+		},
+		{
+			name: "single reconstructable generation",
+			generationAnalysis: map[uint32]*GenerationAnalysis{
+				1: {Generation: 1, ShardCount: 10, CanReconstruct: true},
+			},
+			expectedGeneration: 1,
+			expectedFound:      true,
+		},
+		{
+			name: "no reconstructable generations",
+			generationAnalysis: map[uint32]*GenerationAnalysis{
+				1: {Generation: 1, ShardCount: 5, CanReconstruct: false},
+				2: {Generation: 2, ShardCount: 3, CanReconstruct: false},
+			},
+			expectedFound: false,
+		},
+		{
+			name: "multiple reconstructable - picks most complete",
+			generationAnalysis: map[uint32]*GenerationAnalysis{
+				1: {Generation: 1, ShardCount: 10, CanReconstruct: true},
+				2: {Generation: 2, ShardCount: 14, CanReconstruct: true}, // Most complete
+				3: {Generation: 3, ShardCount: 12, CanReconstruct: true},
+			},
+			expectedGeneration: 2,
+			expectedFound:      true,
+		},
+		{
+			name: "tie in shard count - picks higher generation",
+			generationAnalysis: map[uint32]*GenerationAnalysis{
+				1: {Generation: 1, ShardCount: 10, CanReconstruct: true},
+				2: {Generation: 2, ShardCount: 10, CanReconstruct: true}, // Same count, higher generation
+			},
+			expectedGeneration: 2,
+			expectedFound:      true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			generation, found := logic.FindMostCompleteGeneration(tt.generationAnalysis)
+
+			if found != tt.expectedFound {
+				t.Errorf("found: expected %v, got %v", tt.expectedFound, found)
+				return
+			}
+
+			if tt.expectedFound && generation != tt.expectedGeneration {
+				t.Errorf("generation: expected %d, got %d", tt.expectedGeneration, generation)
+			}
+		})
+	}
+}
+
+func TestFindMaxGeneration(t *testing.T) {
+	logic := NewEcVacuumLogic()
+
+	tests := []struct {
+		name               string
+		generationAnalysis map[uint32]*GenerationAnalysis
+		expectedMax        uint32
+	}{
+		{
+			name:               "empty analysis",
+			generationAnalysis: map[uint32]*GenerationAnalysis{},
+			expectedMax:        0,
+		},
+		{
+			name: "single generation",
+			generationAnalysis: map[uint32]*GenerationAnalysis{
+				5: {Generation: 5},
+			},
+			expectedMax: 5,
+		},
+		{
+			name: "multiple generations",
+			generationAnalysis: map[uint32]*GenerationAnalysis{
+				1: {Generation: 1},
+				5: {Generation: 5},
+				3: {Generation: 3},
+				7: {Generation: 7}, // Highest
+			},
+			expectedMax: 7,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			maxGen := logic.FindMaxGeneration(tt.generationAnalysis)
+
+			if maxGen != tt.expectedMax {
+				t.Errorf("max generation: expected %d, got %d", tt.expectedMax, maxGen)
+			}
+		})
+	}
+}
+
+func TestMultiGenerationVacuumScenarios(t *testing.T) {
+	logic := NewEcVacuumLogic()
+
+	tests := []struct {
+		name                 string
+		params               *worker_pb.TaskParams
+		expectedSourceGen    uint32
+		expectedTargetGen    uint32
+		expectedCleanupCount int
+		expectError          bool
+	}{
+		{
+			name: "corrupted generation 1, good generation 2",
+			params: &worker_pb.TaskParams{
+				Sources: []*worker_pb.TaskSource{
+					{
+						Node:       "node1:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2}, // Insufficient - corrupted data
+					},
+					{
+						Node:       "node2:8080",
+						Generation: 2,
+						ShardIds:   []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9}, // Complete - good data
+					},
+				},
+			},
+			expectedSourceGen:    2, // Should use generation 2
+			expectedTargetGen:    3, // max(1,2) + 1 = 3
+			expectedCleanupCount: 2, // Clean up generations 1 and 2
+		},
+		{
+			name: "multiple old generations, one current good",
+			params: &worker_pb.TaskParams{
+				Sources: []*worker_pb.TaskSource{
+					{
+						Node:       "node1:8080",
+						Generation: 0,
+						ShardIds:   []uint32{0, 1}, // Old incomplete
+					},
+					{
+						Node:       "node2:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2, 3}, // Old incomplete
+					},
+					{
+						Node:       "node3:8080",
+						Generation: 2,
+						ShardIds:   []uint32{0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13}, // Complete - all shards
+					},
+				},
+			},
+			expectedSourceGen:    2, // Should use generation 2 (most complete)
+			expectedTargetGen:    3, // max(0,1,2) + 1 = 3
+			expectedCleanupCount: 3, // Clean up generations 0, 1, and 2
+		},
+		{
+			name: "no sufficient generations",
+			params: &worker_pb.TaskParams{
+				Sources: []*worker_pb.TaskSource{
+					{
+						Node:       "node1:8080",
+						Generation: 1,
+						ShardIds:   []uint32{0, 1, 2}, // Only 3 shards - insufficient
+					},
+					{
+						Node:       "node2:8080",
+						Generation: 2,
+						ShardIds:   []uint32{0, 1}, // Only 2 shards - insufficient
+					},
+				},
+			},
+			expectError: true, // No generation has enough shards
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			plan, err := logic.CreateVacuumPlan(123, "test", tt.params)
+
+			if tt.expectError {
+				if err == nil {
+					t.Errorf("expected error but got none")
+				}
+				return
+			}
+
+			if err != nil {
+				t.Errorf("unexpected error: %v", err)
+				return
+			}
+
+			if plan.CurrentGeneration != tt.expectedSourceGen {
+				t.Errorf("source generation: expected %d, got %d", tt.expectedSourceGen, plan.CurrentGeneration)
+			}
+
+			if plan.TargetGeneration != tt.expectedTargetGen {
+				t.Errorf("target generation: expected %d, got %d", tt.expectedTargetGen, plan.TargetGeneration)
+			}
+
+			if len(plan.GenerationsToCleanup) != tt.expectedCleanupCount {
+				t.Errorf("cleanup count: expected %d, got %d", tt.expectedCleanupCount, len(plan.GenerationsToCleanup))
+			}
+
+			// Verify cleanup generations don't include target
+			for _, gen := range plan.GenerationsToCleanup {
+				if gen == plan.TargetGeneration {
+					t.Errorf("cleanup generations should not include target generation %d", plan.TargetGeneration)
+				}
+			}
+		})
+	}
+}