Warn when masterfeat expansion silently drops unobtainable feats (#31)

`classFeatExpansionCanUseFeat` excludes `ALLCLASSESCANUSE=0` feats from class feat table masterfeat expansion. When such a feat also has no `MinLevelClass`, no class can ever obtain it — a data bug that previously failed silently (Spell Focus vanishing from the wizard table, Favored Enemy from ranger, proficiencies from commoner).

New `validateClassFeatMasterfeatAccessibility` warns for exactly that case; exclusions with an explicit `MinLevelClass` (deliberate class restrictions, e.g. fighter weapon specialization) and `ALLCLASSESCANUSE=1` feats stay silent. No keys are hardcoded — everything is derived from the datasets.

Verified: new test + full `go test ./internal/topdata/` pass; against live sow-topdata data it flagged 36 real drops (all fixed by the companion sow-topdata PR, after which it reports 0).

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Reviewed-on: #31
Reviewed-by: xtul <mpiasecki720@protonmail.com>
Co-authored-by: vickydotbat <vickydotbat@tutamail.com>
Co-committed-by: vickydotbat <vickydotbat@tutamail.com>

internal/topdata/class_feat_accessibility.go

@@ -0,0 +1,98 @@
+package topdata
+
+import (
+	"fmt"
+	"path/filepath"
+	"slices"
+	"strings"
+)
+
+// validateClassFeatMasterfeatAccessibility warns when a class feat table
+// references a masterfeat whose member feats are silently dropped from
+// expansion by classFeatExpansionCanUseFeat. Only the ambiguous case is
+// flagged: ALLCLASSESCANUSE=0 with no MinLevelClass, where the feat cannot
+// be obtained by any class at all. Exclusions with an explicit MinLevelClass
+// are deliberate cross-class restrictions and stay silent.
+func validateClassFeatMasterfeatAccessibility(dataDir string, report *ValidationReport) {
+	datasets, err := discoverNativeDatasets(dataDir)
+	if err != nil {
+		return
+	}
+	keyToID := map[string]int{}
+	var featRowByKey map[string]map[string]any
+	type classFeatTable struct {
+		path     string
+		classKey string
+		rows     []map[string]any
+	}
+	classTables := []classFeatTable{}
+	for _, dataset := range datasets {
+		name := filepath.ToSlash(dataset.Name)
+		isClassFeats := strings.HasPrefix(name, "classes/feats/")
+		if name != "feat" && name != "masterfeats" && name != "classes/core" && !isClassFeats {
+			continue
+		}
+		collected, err := collectNativeDataset(dataset)
+		if err != nil {
+			return
+		}
+		for key, id := range collected.LockData {
+			keyToID[key] = id
+		}
+		switch {
+		case name == "feat":
+			featRowByKey = rowsByKey(collected.Rows)
+		case isClassFeats:
+			classTables = append(classTables, classFeatTable{
+				path:     dataset.BasePath,
+				classKey: "classes:" + name[strings.LastIndex(name, "/")+1:],
+				rows:     collected.Rows,
+			})
+		}
+	}
+	if featRowByKey == nil {
+		return
+	}
+	for _, table := range classTables {
+		for _, row := range table.rows {
+			featRef, ok := row["FeatIndex"].(map[string]any)
+			if !ok {
+				continue
+			}
+			refKey, _ := featRef["id"].(string)
+			if !strings.HasPrefix(refKey, "masterfeats:") {
+				continue
+			}
+			masterfeatKey := resolveCanonicalDatasetKey(refKey, keyToID)
+			if _, ok := keyToID[masterfeatKey]; !ok {
+				continue
+			}
+			featKeys := make([]string, 0, len(featRowByKey))
+			for featKey := range featRowByKey {
+				if strings.HasPrefix(featKey, "feat:") {
+					featKeys = append(featKeys, featKey)
+				}
+			}
+			slices.Sort(featKeys)
+			for _, featKey := range featKeys {
+				featRow := featRowByKey[featKey]
+				if !rowReferencesMasterfeat(featRow, masterfeatKey, keyToID) {
+					continue
+				}
+				if classFeatExpansionCanUseFeat(featRow, table.classKey, keyToID) {
+					continue
+				}
+				if minLevelClass, ok := lookupField(featRow, "MinLevelClass"); ok && !isNullishValue(minLevelClass) {
+					continue
+				}
+				report.Diagnostics = append(report.Diagnostics, Diagnostic{
+					Severity: SeverityWarning,
+					Path:     table.path,
+					Message: fmt.Sprintf(
+						"%s references %s but %s is excluded from expansion (ALLCLASSESCANUSE=0 with no MinLevelClass makes it unobtainable); override ALLCLASSESCANUSE or set MinLevelClass",
+						table.classKey, masterfeatKey, featKey),
+				})
+			}
+		}
+	}
+}

internal/topdata/class_feat_accessibility_test.go

@@ -0,0 +1,82 @@
+package topdata
+
+import (
+	"path/filepath"
+	"strings"
+	"testing"
+)
+
+func TestValidateClassFeatMasterfeatAccessibilityWarnsOnUnobtainableExpansion(t *testing.T) {
+	root := testProjectRoot(t)
+	mkdirAll(t, filepath.Join(root, "topdata", "data", "classes", "feats"))
+	mkdirAll(t, filepath.Join(root, "topdata", "data", "feat"))
+	mkdirAll(t, filepath.Join(root, "topdata", "data", "masterfeats"))
+	writeFile(t, filepath.Join(root, "topdata", "data", "classes", "base.json"), `{
+  "output": "classes.2da",
+  "columns": ["Label", "Name", "FeatsTable"],
+  "rows": [
+    {"id": 4, "key": "classes:fighter", "Label": "Fighter", "Name": "111", "FeatsTable": "cls_feat_fighter"},
+    {"id": 10, "key": "classes:wizard", "Label": "Wizard", "Name": "112", "FeatsTable": "cls_feat_wizard"}
+  ]
+}`+"\n")
+	writeFile(t, filepath.Join(root, "topdata", "data", "classes", "lock.json"), `{"classes:fighter":4,"classes:wizard":10}`+"\n")
+	writeFile(t, filepath.Join(root, "topdata", "data", "classes", "feats", "wizard.json"), `{
+  "key": "classes/feats:wizard",
+  "output": "cls_feat_wizard.2da",
+  "columns": ["FeatLabel", "FeatIndex", "List", "GrantedOnLevel", "OnMenu"],
+  "rows": [
+    {"FeatIndex": {"id": "masterfeats:spellfocus"}, "List": "1", "GrantedOnLevel": "-1", "OnMenu": "0"},
+    {"FeatIndex": {"id": "masterfeats:weaponspecialization"}, "List": "1", "GrantedOnLevel": "-1", "OnMenu": "0"}
+  ]
+}`+"\n")
+	writeFile(t, filepath.Join(root, "topdata", "data", "feat", "base.json"), `{
+  "output": "feat.2da",
+  "columns": ["LABEL", "FEAT", "DESCRIPTION", "MASTERFEAT", "ALLCLASSESCANUSE", "MinLevelClass"],
+  "rows": [
+    {"id": 100, "key": "feat:spellfocus_abjuration", "LABEL": "SpellFocusAbj", "FEAT": "1000", "DESCRIPTION": "1001", "MASTERFEAT": "1", "ALLCLASSESCANUSE": "0", "MinLevelClass": "****"},
+    {"id": 101, "key": "feat:spellfocus_conjuration", "LABEL": "SpellFocusCon", "FEAT": "1002", "DESCRIPTION": "1003", "MASTERFEAT": "1", "ALLCLASSESCANUSE": "1", "MinLevelClass": "****"},
+    {"id": 200, "key": "feat:weaponspecialization_longsword", "LABEL": "WeaponSpecLongsword", "FEAT": "2000", "DESCRIPTION": "2001", "MASTERFEAT": "2", "ALLCLASSESCANUSE": "0", "MinLevelClass": {"id": "classes:fighter"}}
+  ]
+}`+"\n")
+	writeFile(t, filepath.Join(root, "topdata", "data", "feat", "lock.json"), `{
+  "feat:spellfocus_abjuration": 100,
+  "feat:spellfocus_conjuration": 101,
+  "feat:weaponspecialization_longsword": 200
+}`+"\n")
+	writeFile(t, filepath.Join(root, "topdata", "data", "masterfeats", "base.json"), `{
+  "output": "masterfeats.2da",
+  "columns": ["LABEL", "STRREF", "DESCRIPTION", "ICON"],
+  "rows": [
+    {"id": 1, "key": "masterfeats:spellfocus", "LABEL": "SpellFocus", "STRREF": "6492", "DESCRIPTION": "426", "ICON": "ife_magic"},
+    {"id": 2, "key": "masterfeats:weaponspecialization", "LABEL": "WeaponSpecialization", "STRREF": "6491", "DESCRIPTION": "437", "ICON": "ife_wepspec"}
+  ]
+}`+"\n")
+	writeFile(t, filepath.Join(root, "topdata", "data", "masterfeats", "lock.json"), `{
+  "masterfeats:spellfocus": 1,
+  "masterfeats:weaponspecialization": 2
+}`+"\n")
+
+	report := ValidationReport{}
+	validateClassFeatMasterfeatAccessibility(filepath.Join(root, "topdata", "data"), &report)
+
+	warned := map[string]bool{}
+	for _, diagnostic := range report.Diagnostics {
+		if diagnostic.Severity != SeverityWarning {
+			continue
+		}
+		for _, featKey := range []string{"feat:spellfocus_abjuration", "feat:spellfocus_conjuration", "feat:weaponspecialization_longsword"} {
+			if strings.Contains(diagnostic.Message, featKey) {
+				warned[featKey] = true
+			}
+		}
+	}
+	if !warned["feat:spellfocus_abjuration"] {
+		t.Fatalf("expected warning for unobtainable ALLCLASSESCANUSE=0 feat, got: %+v", report.Diagnostics)
+	}
+	if warned["feat:spellfocus_conjuration"] {
+		t.Fatalf("did not expect warning for ALLCLASSESCANUSE=1 feat, got: %+v", report.Diagnostics)
+	}
+	if warned["feat:weaponspecialization_longsword"] {
+		t.Fatalf("did not expect warning for feat with explicit MinLevelClass, got: %+v", report.Diagnostics)
+	}
+}

internal/topdata/topdata.go

@@ -268,6 +268,7 @@ func ValidateProject(p *project.Project) ValidationReport {
 	validateNativeLockAllocation(dataDir, p.EffectiveConfig().TopData.RowGeneration, &report)
 	validateGeneratedFeatFamilies(dataDir, &report)
 	validateClassSpellbooks(dataDir, &report)
+	validateClassFeatMasterfeatAccessibility(dataDir, &report)
 	validateItempropsRegistryGraph(dataDir, &report)
 	if _, err := os.Stat(statePath); err == nil {
 		report.Files++