Track per-node repset membership in repset-diff

Report tables that are in the repset on some nodes but not others.
All tables are still diffed (the data exists on all nodes), but
asymmetric repset membership is now surfaced in the summary.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: mason-sharp

internal/consistency/diff/repset_diff.go

@@ -135,8 +135,8 @@ func (c *RepsetDiffCmd) RunChecks(skipValidation bool) error {
 	// In a uni-directional setup the repset may only exist on the publisher, but
 	// the tables themselves exist on all nodes, so we still diff them across
 	// every node.
-	tableSet := make(map[string]bool)
-	var nodesWithRepset int
+	tablePresence := make(map[string]map[string]bool) // table -> {nodeName: true}
+	var repsetNodeNames []string
 
 	for _, nodeInfo := range c.clusterNodes {
 		nodeName := nodeInfo["Name"].(string)
@@ -165,7 +165,7 @@ func (c *RepsetDiffCmd) RunChecks(skipValidation bool) error {
 			logger.Warn("repset %s not found on node %s, skipping for table discovery", c.RepsetName, nodeName)
 			continue
 		}
-		nodesWithRepset++
+		repsetNodeNames = append(repsetNodeNames, nodeName)
 
 		tables, err := queries.GetTablesInRepSet(c.Ctx, pool, c.RepsetName)
 		pool.Close()
@@ -174,21 +174,47 @@ func (c *RepsetDiffCmd) RunChecks(skipValidation bool) error {
 		}
 
 		for _, t := range tables {
-			tableSet[t] = true
+			if tablePresence[t] == nil {
+				tablePresence[t] = make(map[string]bool)
+			}
+			tablePresence[t][nodeName] = true
 		}
 	}
 
-	if nodesWithRepset == 0 {
+	if len(repsetNodeNames) == 0 {
 		return fmt.Errorf("repset %s not found on any node", c.RepsetName)
 	}
 
+	// Build the full table list (union) and track tables not in the repset
+	// on every node. All tables are still diffed (the data exists on all
+	// nodes), but asymmetric repset membership is reported in the summary.
 	var allTables []string
-	for t := range tableSet {
-		allTables = append(allTables, t)
+	var missingTables []MissingTableInfo
+	for table, presence := range tablePresence {
+		allTables = append(allTables, table)
+		if len(presence) < len(repsetNodeNames) {
+			var presentOn, missingFrom []string
+			for _, n := range repsetNodeNames {
+				if presence[n] {
+					presentOn = append(presentOn, n)
+				} else {
+					missingFrom = append(missingFrom, n)
+				}
+			}
+			missingTables = append(missingTables, MissingTableInfo{
+				Table:       table,
+				PresentOn:   presentOn,
+				MissingFrom: missingFrom,
+			})
+		}
 	}
 	sort.Strings(allTables)
+	sort.Slice(missingTables, func(i, j int) bool {
+		return missingTables[i].Table < missingTables[j].Table
+	})
 
 	c.tableList = allTables
+	c.missingTables = missingTables
 
 	if len(c.tableList) == 0 {
 		return fmt.Errorf("no tables found in repset %s", c.RepsetName)

tests/integration/repset_diff_summary_test.go

@@ -88,11 +88,20 @@ func TestRepsetDiff_UniDirectional(t *testing.T) {
 	// still compares data across both nodes.
 	require.NoError(t, diffErr)
 
+	// Extract the summary section for precise assertions.
+	summarySection := extractSummarySection(t, logOutput)
+
 	// The table should have been compared and found identical.
-	assert.Contains(t, logOutput, "table(s) are identical",
-		"summary should show identical tables")
-	assert.Contains(t, logOutput, qualifiedTableName,
-		"the uni-directional table should appear in the summary")
+	identicalSection := extractBetween(summarySection, "table(s) are identical:", "table(s)")
+	assert.Contains(t, identicalSection, qualifiedTableName,
+		"the uni-directional table should be compared and found identical")
+
+	// The asymmetric repset membership should be reported.
+	missingSection := extractBetween(summarySection, "not present on all nodes:", "table(s)")
+	assert.Contains(t, missingSection, qualifiedTableName,
+		"table should be reported as not in repset on all nodes")
+	assert.Contains(t, missingSection, fmt.Sprintf("missing from [%s]", serviceN2),
+		"should indicate which node is missing the table in its repset")
 }
 
 // TestRepsetDiff_Summary verifies that the repset-diff summary correctly