1 files changed, 162 insertions, 0 deletions
diff --git a/internal/validate/validate.go b/internal/validate/validate.go
new file mode 100644
index 0000000..5557f72
--- /dev/null
+++ b/internal/validate/validate.go
@@ -0,0 +1,162 @@
+// Package validate runs startup integrity checks across all data files:
+// duplicate IDs, referential integrity (rooms, mobs, objects, items, drops,
+// courses, techs), and world wiring (orphan rooms). It depends only on the
+// data packages (world, object, item, behavior), never on the game
+// orchestrator, so it can be reused and tested in isolation.
+package validate
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"sort"
+	"strings"
+
+	"thehouseoficarus/internal/behavior"
+	"thehouseoficarus/internal/item"
+	"thehouseoficarus/internal/object"
+	"thehouseoficarus/internal/world"
+)
+
+// Issue is a single validation finding.
+type Issue struct {
+	Level   string // "ERROR" or "WARN"
+	Type    string // "duplicate", "reference", "integrity"
+	Message string
+}
+
+// CourseView is the subset of a course definition needed for validation.
+type CourseView struct {
+	ID            string
+	StartRoom     int
+	ObstacleRooms []int
+}
+
+// TechView is the subset of a tech definition needed for validation.
+type TechView struct {
+	ID        string
+	Name      string
+	Category  string
+	DrainRate float64
+}
+
+// Source bundles everything the validator reads. The game package builds this
+// from its stores and passes it to Run.
+type Source struct {
+	DataDir           string
+	Items             *item.ItemStore
+	Objects           *object.ObjectStore
+	Mobs              *world.MobStore
+	World             *world.World
+	Courses           []CourseView
+	Techs             []TechView
+	TechIDs           map[string]bool
+	CheckSources      []int
+	IgnoreUnreachable []int
+}
+
+// Run executes all checks and returns the collected issues.
+func Run(s Source) []Issue {
+	var issues []Issue
+
+	for _, dir := range []struct{ sub, label string }{
+		{"items", "item"}, {"rooms", "room"}, {"mobs", "mob"},
+		{"objects", "object"}, {"drops", "drop table"}, {"courses", "course"},
+		{"modules", "module"}, {"techs", "tech"}, {"help", "help topic"},
+	} {
+		issues = append(issues, validateIDs(s.DataDir, dir.sub, dir.label)...)
+	}
+
+	issues = append(issues, validateRooms(s)...)
+	issues = append(issues, validateMobs(s)...)
+	issues = append(issues, validateHazards(s)...)
+	issues = append(issues, validateObjects(s)...)
+	issues = append(issues, validateItems(s)...)
+	issues = append(issues, validateCraftBlocks(s)...)
+	issues = append(issues, validateDropTables(s)...)
+	issues = append(issues, validateCourses(s)...)
+	issues = append(issues, validateTechs(s)...)
+	issues = append(issues, validateRoomWiring(s)...)
+
+	return issues
+}
+
+func validateIDs(dataDir, subDir, label string) []Issue {
+	dir := filepath.Join(dataDir, subDir)
+	dups := behavior.CheckDuplicateIDs(dir)
+	var issues []Issue
+	for _, d := range dups {
+		short := make([]string, len(d.Paths))
+		for i, p := range d.Paths {
+			short[i] = strings.TrimPrefix(p, dir+"/")
+		}
+		issues = append(issues, Issue{
+			Level: "ERROR",
+			Type:  "duplicate",
+			Message: fmt.Sprintf("Duplicate %s ID %q found in: %s",
+				label, d.ID, strings.Join(short, ", ")),
+		})
+	}
+	return issues
+}
+
+func dropTableIDSet(dataDir string) map[string]bool {
+	dir := filepath.Join(dataDir, "drops")
+	ids := make(map[string]bool)
+	behavior.WalkYAMLDir(dir, func(path, id string, data []byte) error {
+		ids[id] = true
+		return nil
+	})
+	return ids
+}
+
+// LogIssues prints validation results to stderr, sorted with errors first.
+func LogIssues(issues []Issue) {
+	if len(issues) == 0 {
+		fmt.Fprintf(os.Stderr, "Startup validation: OK\n")
+		return
+	}
+
+	errors := 0
+	warns := 0
+	for _, issue := range issues {
+		if issue.Level == "ERROR" {
+			errors++
+		} else {
+			warns++
+		}
+	}
+
+	fmt.Fprintf(os.Stderr, "\n=== Startup Validation: %d error(s), %d warning(s) ===\n\n", errors, warns)
+
+	sort.Slice(issues, func(i, j int) bool {
+		if issues[i].Level != issues[j].Level {
+			return issues[i].Level == "ERROR"
+		}
+		return issues[i].Message < issues[j].Message
+	})
+
+	for _, issue := range issues {
+		tag := fmt.Sprintf("[%s]", issue.Level)
+		fmt.Fprintf(os.Stderr, "  %-7s %s\n", tag, issue.Message)
+	}
+	fmt.Fprintln(os.Stderr)
+
+	if errors > 0 {
+		fmt.Fprintf(os.Stderr, "*** %d startup errors detected. The server may behave unexpectedly. ***\n", errors)
+	}
+}
+
+var knownTechCategories = map[string]bool{
+	"accuracy": true, "strength": true, "defense": true, "ranged": true,
+	"science": true, "protection": true, "utility": true, "combo": true,
+}
+
+// reservedTechIDs are tech IDs whose semantics are coupled to code logic and
+// must exist in YAML (damage protection mapping + death retribution).
+var reservedTechIDs = map[string]bool{
+	"protect_melee":   true,
+	"protect_ranged":  true,
+	"protect_science": true,
+	"retribution":     true,
+}