Enhanced the SanitizeWhereClause function

pkg/common/adapters/database/RELATION_LOADING.md

@@ -0,0 +1,218 @@
+# Automatic Relation Loading Strategies
+
+## Overview
+
+**NEW:** The database adapters now **automatically** choose the optimal loading strategy by inspecting your model's relationship tags!
+
+Simply use `PreloadRelation()` and the system automatically:
+- Detects relationship type from Bun/GORM tags
+- Uses **JOIN** for many-to-one and one-to-one (efficient, no duplication)
+- Uses **separate query** for one-to-many and many-to-many (avoids duplication)
+
+## How It Works
+
+```go
+// Just write this - the system handles the rest!
+db.NewSelect().
+    Model(&links).
+    PreloadRelation("Provider").  // ✓ Auto-detects belongs-to → uses JOIN
+    PreloadRelation("Tags").      // ✓ Auto-detects has-many → uses separate query
+    Scan(ctx, &links)
+```
+
+### Detection Logic
+
+The system inspects your model's struct tags:
+
+**Bun models:**
+```go
+type Link struct {
+    Provider   *Provider `bun:"rel:belongs-to"`   // → Detected: belongs-to → JOIN
+    Tags       []Tag     `bun:"rel:has-many"`     // → Detected: has-many → Separate query
+}
+```
+
+**GORM models:**
+```go
+type Link struct {
+    ProviderID int
+    Provider   *Provider `gorm:"foreignKey:ProviderID"`  // → Detected: belongs-to → JOIN
+    Tags       []Tag     `gorm:"many2many:link_tags"`    // → Detected: many-to-many → Separate query
+}
+```
+
+**Type inference (fallback):**
+- `[]Type` (slice) → has-many → Separate query
+- `*Type` (pointer) → belongs-to → JOIN
+- `Type` (struct) → belongs-to → JOIN
+
+### What Gets Logged
+
+Enable debug logging to see strategy selection:
+
+```go
+bunAdapter.EnableQueryDebug()
+```
+
+**Output:**
+```
+DEBUG: PreloadRelation 'Provider' detected as: belongs-to
+INFO:  Using JOIN strategy for belongs-to relation 'Provider'
+DEBUG: PreloadRelation 'Links' detected as: has-many
+DEBUG: Using separate query for has-many relation 'Links'
+```
+
+## Relationship Types
+
+| Bun Tag | GORM Pattern | Field Type | Strategy | Why |
+|---------|--------------|------------|----------|-----|
+| `rel:has-many` | Slice field | `[]Type` | Separate Query | Avoids duplicating parent data |
+| `rel:belongs-to` | `foreignKey:` | `*Type` | JOIN | Single parent, no duplication |
+| `rel:has-one` | Single pointer | `*Type` | JOIN | One-to-one, no duplication |
+| `rel:many-to-many` | `many2many:` | `[]Type` | Separate Query | Complex join, avoid cartesian |
+
+## Manual Override
+
+If you need to force a specific strategy, use `JoinRelation()`:
+
+```go
+// Force JOIN even for has-many (not recommended)
+db.NewSelect().
+    Model(&providers).
+    JoinRelation("Links").  // Explicitly use JOIN
+    Scan(ctx, &providers)
+```
+
+## Examples
+
+### Automatic Strategy Selection (Recommended)
+
+```go
+// Example 1: Loading parent provider for each link
+// System detects belongs-to → uses JOIN automatically
+db.NewSelect().
+    Model(&links).
+    PreloadRelation("Provider", func(q common.SelectQuery) common.SelectQuery {
+        return q.Where("active = ?", true)
+    }).
+    Scan(ctx, &links)
+
+// Generated SQL: Single query with JOIN
+// SELECT links.*, providers.*
+// FROM links
+// LEFT JOIN providers ON links.provider_id = providers.id
+// WHERE providers.active = true
+
+// Example 2: Loading child links for each provider
+// System detects has-many → uses separate query automatically
+db.NewSelect().
+    Model(&providers).
+    PreloadRelation("Links", func(q common.SelectQuery) common.SelectQuery {
+        return q.Where("active = ?", true)
+    }).
+    Scan(ctx, &providers)
+
+// Generated SQL: Two queries
+// Query 1: SELECT * FROM providers
+// Query 2: SELECT * FROM links
+//          WHERE provider_id IN (1, 2, 3, ...)
+//          AND active = true
+```
+
+### Mixed Relationships
+
+```go
+type Order struct {
+    ID         int
+    CustomerID int
+    Customer   *Customer `bun:"rel:belongs-to"`    // JOIN
+    Items      []Item    `bun:"rel:has-many"`      // Separate
+    Invoice    *Invoice  `bun:"rel:has-one"`       // JOIN
+}
+
+// All three handled optimally!
+db.NewSelect().
+    Model(&orders).
+    PreloadRelation("Customer").  // → JOIN (many-to-one)
+    PreloadRelation("Items").     // → Separate (one-to-many)
+    PreloadRelation("Invoice").   // → JOIN (one-to-one)
+    Scan(ctx, &orders)
+```
+
+## Performance Benefits
+
+### Before (Manual Strategy Selection)
+
+```go
+// You had to remember which to use:
+.PreloadRelation("Provider")  // Should I use PreloadRelation or JoinRelation?
+.PreloadRelation("Links")     // Which is more efficient here?
+```
+
+### After (Automatic Selection)
+
+```go
+// Just use PreloadRelation everywhere:
+.PreloadRelation("Provider")  // ✓ System uses JOIN automatically
+.PreloadRelation("Links")     // ✓ System uses separate query automatically
+```
+
+## Migration Guide
+
+**No changes needed!** If you're already using `PreloadRelation()`, it now automatically optimizes:
+
+```go
+// Before: Always used separate query
+.PreloadRelation("Provider")  // Inefficient: extra round trip
+
+// After: Automatic optimization
+.PreloadRelation("Provider")  // ✓ Now uses JOIN automatically!
+```
+
+## Implementation Details
+
+### Supported Bun Tags
+- `rel:has-many` → Separate query
+- `rel:belongs-to` → JOIN
+- `rel:has-one` → JOIN
+- `rel:many-to-many` or `rel:m2m` → Separate query
+
+### Supported GORM Patterns
+- `many2many:` tag → Separate query
+- `foreignKey:` tag → JOIN (belongs-to)
+- `[]Type` slice without many2many → Separate query (has-many)
+- `*Type` pointer with foreignKey → JOIN (belongs-to)
+- `*Type` pointer without foreignKey → JOIN (has-one)
+
+### Fallback Behavior
+- `[]Type` (slice) → Separate query (safe default for collections)
+- `*Type` or `Type` (single) → JOIN (safe default for single relations)
+- Unknown → Separate query (safest default)
+
+## Debugging
+
+To see strategy selection in action:
+
+```go
+// Enable debug logging
+bunAdapter.EnableQueryDebug()  // or gormAdapter.EnableQueryDebug()
+
+// Run your query
+db.NewSelect().
+    Model(&records).
+    PreloadRelation("RelationName").
+    Scan(ctx, &records)
+
+// Check logs for:
+// - "PreloadRelation 'X' detected as: belongs-to"
+// - "Using JOIN strategy for belongs-to relation 'X'"
+// - Actual SQL queries executed
+```
+
+## Best Practices
+
+1. **Use PreloadRelation() for everything** - Let the system optimize
+2. **Define proper relationship tags** - Ensures correct detection
+3. **Only use JoinRelation() for overrides** - When you know better than auto-detection
+4. **Enable debug logging during development** - Verify optimal strategies are chosen
+5. **Trust the system** - It's designed to choose correctly based on relationship type

pkg/common/adapters/database/alias_test.go

@@ -0,0 +1,81 @@
+package database
+
+import (
+	"testing"
+)
+
+func TestNormalizeTableAlias(t *testing.T) {
+	tests := []struct {
+		name          string
+		query         string
+		expectedAlias string
+		tableName     string
+		want          string
+	}{
+		{
+			name:          "strips plausible alias from simple condition",
+			query:         "APIL.rid_hub = 2576",
+			expectedAlias: "apiproviderlink",
+			tableName:     "apiproviderlink",
+			want:          "rid_hub = 2576",
+		},
+		{
+			name:          "keeps correct alias",
+			query:         "apiproviderlink.rid_hub = 2576",
+			expectedAlias: "apiproviderlink",
+			tableName:     "apiproviderlink",
+			want:          "apiproviderlink.rid_hub = 2576",
+		},
+		{
+			name:          "strips plausible alias with multiple conditions",
+			query:         "APIL.rid_hub = ? AND APIL.active = ?",
+			expectedAlias: "apiproviderlink",
+			tableName:     "apiproviderlink",
+			want:          "rid_hub = ? AND active = ?",
+		},
+		{
+			name:          "handles mixed correct and plausible aliases",
+			query:         "APIL.rid_hub = ? AND apiproviderlink.active = ?",
+			expectedAlias: "apiproviderlink",
+			tableName:     "apiproviderlink",
+			want:          "rid_hub = ? AND apiproviderlink.active = ?",
+		},
+		{
+			name:          "handles parentheses",
+			query:         "(APIL.rid_hub = ?)",
+			expectedAlias: "apiproviderlink",
+			tableName:     "apiproviderlink",
+			want:          "(rid_hub = ?)",
+		},
+		{
+			name:          "no alias in query",
+			query:         "rid_hub = ?",
+			expectedAlias: "apiproviderlink",
+			tableName:     "apiproviderlink",
+			want:          "rid_hub = ?",
+		},
+		{
+			name:          "keeps reference to different table (not in current table name)",
+			query:         "APIL.rid_hub = ?",
+			expectedAlias: "apiprovider",
+			tableName:     "apiprovider",
+			want:          "APIL.rid_hub = ?",
+		},
+		{
+			name:          "keeps reference with short prefix that might be ambiguous",
+			query:         "AP.rid = ?",
+			expectedAlias: "apiprovider",
+			tableName:     "apiprovider",
+			want:          "AP.rid = ?",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := normalizeTableAlias(tt.query, tt.expectedAlias, tt.tableName)
+			if got != tt.want {
+				t.Errorf("normalizeTableAlias() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}

pkg/common/adapters/database/bun.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"reflect"
 	"strings"
+	"time"
 
 	"github.com/uptrace/bun"
 
@@ -15,6 +16,24 @@ import (
 	"github.com/bitechdev/ResolveSpec/pkg/reflection"
 )
 
+// QueryDebugHook is a Bun query hook that logs all SQL queries including preloads
+type QueryDebugHook struct{}
+
+func (h *QueryDebugHook) BeforeQuery(ctx context.Context, event *bun.QueryEvent) context.Context {
+	return ctx
+}
+
+func (h *QueryDebugHook) AfterQuery(ctx context.Context, event *bun.QueryEvent) {
+	query := event.Query
+	duration := time.Since(event.StartTime)
+
+	if event.Err != nil {
+		logger.Error("SQL Query Failed [%s]: %s. Error: %v", duration, query, event.Err)
+	} else {
+		logger.Debug("SQL Query Success [%s]: %s", duration, query)
+	}
+}
+
 // BunAdapter adapts Bun to work with our Database interface
 // This demonstrates how the abstraction works with different ORMs
 type BunAdapter struct {
@@ -26,6 +45,20 @@ func NewBunAdapter(db *bun.DB) *BunAdapter {
 	return &BunAdapter{db: db}
 }
 
+// EnableQueryDebug enables query debugging which logs all SQL queries including preloads
+// This is useful for debugging preload queries that may be failing
+func (b *BunAdapter) EnableQueryDebug() {
+	b.db.AddQueryHook(&QueryDebugHook{})
+	logger.Info("Bun query debug mode enabled - all SQL queries will be logged")
+}
+
+// DisableQueryDebug removes all query hooks
+func (b *BunAdapter) DisableQueryDebug() {
+	// Create a new DB without hooks
+	// Note: Bun doesn't have a RemoveQueryHook, so we'd need to track hooks manually
+	logger.Info("To disable query debug, recreate the BunAdapter without adding the hook")
+}
+
 func (b *BunAdapter) NewSelect() common.SelectQuery {
 	return &BunSelectQuery{
 		query: b.db.NewSelect(),
@@ -107,6 +140,8 @@ type BunSelectQuery struct {
 	tableName        string  // Just the table name, without schema
 	tableAlias       string
 	deferredPreloads []deferredPreload // Preloads to execute as separate queries
+	inJoinContext    bool              // Track if we're in a JOIN relation context
+	joinTableAlias   string            // Alias to use for JOIN conditions
 }
 
 // deferredPreload represents a preload that will be executed as a separate query
@@ -156,10 +191,147 @@ func (b *BunSelectQuery) ColumnExpr(query string, args ...interface{}) common.Se
 }
 
 func (b *BunSelectQuery) Where(query string, args ...interface{}) common.SelectQuery {
+	// If we're in a JOIN context, add table prefix to unqualified columns
+	if b.inJoinContext && b.joinTableAlias != "" {
+		query = addTablePrefix(query, b.joinTableAlias)
+	} else if b.tableAlias != "" && b.tableName != "" {
+		// If we have a table alias defined, check if the query references a different alias
+		// This can happen in preloads where the user expects a certain alias but Bun generates another
+		query = normalizeTableAlias(query, b.tableAlias, b.tableName)
+	}
 	b.query = b.query.Where(query, args...)
 	return b
 }
 
+// addTablePrefix adds a table prefix to unqualified column references
+// This is used in JOIN contexts where conditions must reference the joined table
+func addTablePrefix(query, tableAlias string) string {
+	if tableAlias == "" || query == "" {
+		return query
+	}
+
+	// Split on spaces and parentheses to find column references
+	parts := strings.FieldsFunc(query, func(r rune) bool {
+		return r == ' ' || r == '(' || r == ')' || r == ','
+	})
+
+	modified := query
+	for _, part := range parts {
+		// Check if this looks like an unqualified column reference
+		// (no dot, and likely a column name before an operator)
+		if !strings.Contains(part, ".") {
+			// Extract potential column name (before = or other operators)
+			for _, op := range []string{"=", "!=", "<>", ">", ">=", "<", "<=", " LIKE ", " IN ", " IS "} {
+				if strings.Contains(part, op) {
+					colName := strings.Split(part, op)[0]
+					colName = strings.TrimSpace(colName)
+					if colName != "" && !isOperatorOrKeyword(colName) {
+						// Add table prefix
+						prefixed := tableAlias + "." + colName + strings.TrimPrefix(part, colName)
+						modified = strings.ReplaceAll(modified, part, prefixed)
+						logger.Debug("Adding table prefix '%s' to column '%s' in JOIN condition", tableAlias, colName)
+					}
+					break
+				}
+			}
+		}
+	}
+
+	return modified
+}
+
+// isOperatorOrKeyword checks if a string is likely an operator or SQL keyword
+func isOperatorOrKeyword(s string) bool {
+	s = strings.ToUpper(strings.TrimSpace(s))
+	keywords := []string{"AND", "OR", "NOT", "IN", "IS", "NULL", "TRUE", "FALSE", "LIKE", "BETWEEN"}
+	for _, kw := range keywords {
+		if s == kw {
+			return true
+		}
+	}
+	return false
+}
+
+// isAcronymMatch checks if prefix is an acronym of tableName
+// For example, "apil" matches "apiproviderlink" because each letter appears in sequence
+func isAcronymMatch(prefix, tableName string) bool {
+	if len(prefix) == 0 || len(tableName) == 0 {
+		return false
+	}
+
+	prefixIdx := 0
+	for i := 0; i < len(tableName) && prefixIdx < len(prefix); i++ {
+		if tableName[i] == prefix[prefixIdx] {
+			prefixIdx++
+		}
+	}
+
+	// All characters of prefix were found in sequence in tableName
+	return prefixIdx == len(prefix)
+}
+
+// normalizeTableAlias replaces table alias prefixes in SQL conditions
+// This handles cases where a user references a table alias that doesn't match
+// what Bun generates (common in preload contexts)
+func normalizeTableAlias(query, expectedAlias, tableName string) string {
+	// Pattern: <word>.<column> where <word> might be an incorrect alias
+	// We'll look for patterns like "APIL.column" and either:
+	// 1. Remove the alias prefix if it's clearly meant for this table
+	// 2. Leave it alone if it might be referring to another table (JOIN/preload)
+
+	// Split on spaces and parentheses to find qualified references
+	parts := strings.FieldsFunc(query, func(r rune) bool {
+		return r == ' ' || r == '(' || r == ')' || r == ','
+	})
+
+	modified := query
+	for _, part := range parts {
+		// Check if this looks like a qualified column reference
+		if dotIndex := strings.Index(part, "."); dotIndex > 0 {
+			prefix := part[:dotIndex]
+			column := part[dotIndex+1:]
+
+			// Check if the prefix matches our expected alias or table name (case-insensitive)
+			if strings.EqualFold(prefix, expectedAlias) ||
+				strings.EqualFold(prefix, tableName) ||
+				strings.EqualFold(prefix, strings.ToLower(tableName)) {
+				// Prefix matches current table, it's safe but redundant - leave it
+				continue
+			}
+
+			// Check if the prefix could plausibly be an alias/acronym for this table
+			// Only strip if we're confident it's meant for this table
+			// For example: "APIL" could be an acronym for "apiproviderlink"
+			prefixLower := strings.ToLower(prefix)
+			tableNameLower := strings.ToLower(tableName)
+
+			// Check if prefix is a substring of table name
+			isSubstring := strings.Contains(tableNameLower, prefixLower) && len(prefixLower) > 2
+
+			// Check if prefix is an acronym of table name
+			// e.g., "APIL" matches "ApiProviderLink" (A-p-I-providerL-ink)
+			isAcronym := false
+			if !isSubstring && len(prefixLower) > 2 {
+				isAcronym = isAcronymMatch(prefixLower, tableNameLower)
+			}
+
+			if isSubstring || isAcronym {
+				// This looks like it could be an alias for this table - strip it
+				logger.Debug("Stripping plausible alias '%s' from WHERE condition, keeping just '%s'", prefix, column)
+				// Replace the qualified reference with just the column name
+				modified = strings.ReplaceAll(modified, part, column)
+			} else {
+				// Prefix doesn't match the current table at all
+				// It's likely referring to a different table (JOIN/preload)
+				// DON'T strip it - leave the qualified reference as-is
+				logger.Debug("Keeping qualified reference '%s' - prefix '%s' doesn't match current table '%s'", part, prefix, tableName)
+			}
+		}
+	}
+
+	return modified
+}
+
 func (b *BunSelectQuery) WhereOr(query string, args ...interface{}) common.SelectQuery {
 	b.query = b.query.WhereOr(query, args...)
 	return b
@@ -288,6 +460,27 @@ func (b *BunSelectQuery) Preload(relation string, conditions ...interface{}) com
 // }
 
 func (b *BunSelectQuery) PreloadRelation(relation string, apply ...func(common.SelectQuery) common.SelectQuery) common.SelectQuery {
+	// Auto-detect relationship type and choose optimal loading strategy
+	// Get the model from the query if available
+	model := b.query.GetModel()
+	if model != nil && model.Value() != nil {
+		relType := reflection.GetRelationType(model.Value(), relation)
+
+		// Log the detected relationship type
+		logger.Debug("PreloadRelation '%s' detected as: %s", relation, relType)
+
+		// If this is a belongs-to or has-one relation, use JOIN for better performance
+		if relType.ShouldUseJoin() {
+			logger.Info("Using JOIN strategy for %s relation '%s'", relType, relation)
+			return b.JoinRelation(relation, apply...)
+		}
+
+		// For has-many, many-to-many, or unknown: use separate query (safer default)
+		if relType == reflection.RelationHasMany || relType == reflection.RelationManyToMany {
+			logger.Debug("Using separate query for %s relation '%s'", relType, relation)
+		}
+	}
+
 	// Check if this relation chain would create problematic long aliases
 	relationParts := strings.Split(relation, ".")
 	aliasChain := strings.ToLower(strings.Join(relationParts, "__"))
@@ -350,6 +543,28 @@ func (b *BunSelectQuery) PreloadRelation(relation string, apply ...func(common.S
 			db:    b.db,
 		}
 
+		// Try to extract table name and alias from the preload model
+		if model := sq.GetModel(); model != nil && model.Value() != nil {
+			modelValue := model.Value()
+
+			// Extract table name if model implements TableNameProvider
+			if provider, ok := modelValue.(common.TableNameProvider); ok {
+				fullTableName := provider.TableName()
+				wrapper.schema, wrapper.tableName = parseTableName(fullTableName)
+			}
+
+			// Extract table alias if model implements TableAliasProvider
+			if provider, ok := modelValue.(common.TableAliasProvider); ok {
+				wrapper.tableAlias = provider.TableAlias()
+				// Apply the alias to the Bun query so conditions can reference it
+				if wrapper.tableAlias != "" {
+					// Note: Bun's Relation() already sets up the table, but we can add
+					// the alias explicitly if needed
+					logger.Debug("Preload relation '%s' using table alias: %s", relation, wrapper.tableAlias)
+				}
+			}
+		}
+
 		// Start with the interface value (not pointer)
 		current := common.SelectQuery(wrapper)
 
@@ -372,6 +587,36 @@ func (b *BunSelectQuery) PreloadRelation(relation string, apply ...func(common.S
 	return b
 }
 
+func (b *BunSelectQuery) JoinRelation(relation string, apply ...func(common.SelectQuery) common.SelectQuery) common.SelectQuery {
+	// JoinRelation uses a LEFT JOIN instead of a separate query
+	// This is more efficient for many-to-one or one-to-one relationships
+
+	logger.Debug("JoinRelation '%s' - Using JOIN strategy with automatic WHERE prefix addition", relation)
+
+	// Wrap the apply functions to automatically add table prefix to WHERE conditions
+	wrappedApply := make([]func(common.SelectQuery) common.SelectQuery, 0, len(apply))
+	for _, fn := range apply {
+		if fn != nil {
+			wrappedFn := func(originalFn func(common.SelectQuery) common.SelectQuery) func(common.SelectQuery) common.SelectQuery {
+				return func(q common.SelectQuery) common.SelectQuery {
+					// Create a special wrapper that adds prefixes to WHERE conditions
+					if bunQuery, ok := q.(*BunSelectQuery); ok {
+						// Mark this query as being in JOIN context
+						bunQuery.inJoinContext = true
+						bunQuery.joinTableAlias = strings.ToLower(relation)
+					}
+					return originalFn(q)
+				}
+			}(fn)
+			wrappedApply = append(wrappedApply, wrappedFn)
+		}
+	}
+
+	// Use PreloadRelation with the wrapped functions
+	// Bun's Relation() will use JOIN for belongs-to and has-one relations
+	return b.PreloadRelation(relation, wrappedApply...)
+}
+
 func (b *BunSelectQuery) Order(order string) common.SelectQuery {
 	b.query = b.query.Order(order)
 	return b
@@ -410,6 +655,9 @@ func (b *BunSelectQuery) Scan(ctx context.Context, dest interface{}) (err error)
 	// Execute the main query first
 	err = b.query.Scan(ctx, dest)
 	if err != nil {
+		// Log SQL string for debugging
+		sqlStr := b.query.String()
+		logger.Error("BunSelectQuery.Scan failed. SQL: %s. Error: %v", sqlStr, err)
 		return err
 	}
 
@@ -438,6 +686,9 @@ func (b *BunSelectQuery) ScanModel(ctx context.Context) (err error) {
 	// Execute the main query first
 	err = b.query.Scan(ctx)
 	if err != nil {
+		// Log SQL string for debugging
+		sqlStr := b.query.String()
+		logger.Error("BunSelectQuery.ScanModel failed. SQL: %s. Error: %v", sqlStr, err)
 		return err
 	}
 
@@ -573,15 +824,25 @@ func (b *BunSelectQuery) Count(ctx context.Context) (count int, err error) {
 	// If Model() was set, use bun's native Count() which works properly
 	if b.hasModel {
 		count, err := b.query.Count(ctx)
+		if err != nil {
+			// Log SQL string for debugging
+			sqlStr := b.query.String()
+			logger.Error("BunSelectQuery.Count failed. SQL: %s. Error: %v", sqlStr, err)
+		}
 		return count, err
 	}
 
 	// Otherwise, wrap as subquery to avoid "Model(nil)" error
 	// This is needed when only Table() is set without a model
-	err = b.db.NewSelect().
+	countQuery := b.db.NewSelect().
 		TableExpr("(?) AS subquery", b.query).
-		ColumnExpr("COUNT(*)").
+		ColumnExpr("COUNT(*)")
-		Scan(ctx, &count)
+	err = countQuery.Scan(ctx, &count)
+	if err != nil {
+		// Log SQL string for debugging
+		sqlStr := countQuery.String()
+		logger.Error("BunSelectQuery.Count (subquery) failed. SQL: %s. Error: %v", sqlStr, err)
+	}
 	return count, err
 }
 
@@ -592,7 +853,13 @@ func (b *BunSelectQuery) Exists(ctx context.Context) (exists bool, err error) {
 			exists = false
 		}
 	}()
-	return b.query.Exists(ctx)
+	exists, err = b.query.Exists(ctx)
+	if err != nil {
+		// Log SQL string for debugging
+		sqlStr := b.query.String()
+		logger.Error("BunSelectQuery.Exists failed. SQL: %s. Error: %v", sqlStr, err)
+	}
+	return exists, err
 }
 
 // BunInsertQuery implements InsertQuery for Bun
@@ -729,6 +996,11 @@ func (b *BunUpdateQuery) Exec(ctx context.Context) (res common.Result, err error
 		}
 	}()
 	result, err := b.query.Exec(ctx)
+	if err != nil {
+		// Log SQL string for debugging
+		sqlStr := b.query.String()
+		logger.Error("BunUpdateQuery.Exec failed. SQL: %s. Error: %v", sqlStr, err)
+	}
 	return &BunResult{result: result}, err
 }
 
@@ -759,6 +1031,11 @@ func (b *BunDeleteQuery) Exec(ctx context.Context) (res common.Result, err error
 		}
 	}()
 	result, err := b.query.Exec(ctx)
+	if err != nil {
+		// Log SQL string for debugging
+		sqlStr := b.query.String()
+		logger.Error("BunDeleteQuery.Exec failed. SQL: %s. Error: %v", sqlStr, err)
+	}
 	return &BunResult{result: result}, err
 }
 

pkg/common/adapters/database/gorm.go

@@ -23,6 +23,22 @@ func NewGormAdapter(db *gorm.DB) *GormAdapter {
 	return &GormAdapter{db: db}
 }
 
+// EnableQueryDebug enables query debugging which logs all SQL queries including preloads
+// This is useful for debugging preload queries that may be failing
+func (g *GormAdapter) EnableQueryDebug() *GormAdapter {
+	g.db = g.db.Debug()
+	logger.Info("GORM query debug mode enabled - all SQL queries will be logged")
+	return g
+}
+
+// DisableQueryDebug disables query debugging
+func (g *GormAdapter) DisableQueryDebug() *GormAdapter {
+	// GORM's Debug() creates a new session, so we need to get the base DB
+	// This is a simplified implementation
+	logger.Info("GORM debug mode - create a new adapter without Debug() to disable")
+	return g
+}
+
 func (g *GormAdapter) NewSelect() common.SelectQuery {
 	return &GormSelectQuery{db: g.db}
 }
@@ -88,10 +104,12 @@ func (g *GormAdapter) RunInTransaction(ctx context.Context, fn func(common.Datab
 
 // GormSelectQuery implements SelectQuery for GORM
 type GormSelectQuery struct {
-	db         *gorm.DB
+	db             *gorm.DB
-	schema     string // Separated schema name
+	schema         string // Separated schema name
-	tableName  string // Just the table name, without schema
+	tableName      string // Just the table name, without schema
-	tableAlias string
+	tableAlias     string
+	inJoinContext  bool   // Track if we're in a JOIN relation context
+	joinTableAlias string // Alias to use for JOIN conditions
 }
 
 func (g *GormSelectQuery) Model(model interface{}) common.SelectQuery {
@@ -135,10 +153,61 @@ func (g *GormSelectQuery) ColumnExpr(query string, args ...interface{}) common.S
 }
 
 func (g *GormSelectQuery) Where(query string, args ...interface{}) common.SelectQuery {
+	// If we're in a JOIN context, add table prefix to unqualified columns
+	if g.inJoinContext && g.joinTableAlias != "" {
+		query = addTablePrefixGorm(query, g.joinTableAlias)
+	}
 	g.db = g.db.Where(query, args...)
 	return g
 }
 
+// addTablePrefixGorm adds a table prefix to unqualified column references (GORM version)
+func addTablePrefixGorm(query, tableAlias string) string {
+	if tableAlias == "" || query == "" {
+		return query
+	}
+
+	// Split on spaces and parentheses to find column references
+	parts := strings.FieldsFunc(query, func(r rune) bool {
+		return r == ' ' || r == '(' || r == ')' || r == ','
+	})
+
+	modified := query
+	for _, part := range parts {
+		// Check if this looks like an unqualified column reference
+		if !strings.Contains(part, ".") {
+			// Extract potential column name (before = or other operators)
+			for _, op := range []string{"=", "!=", "<>", ">", ">=", "<", "<=", " LIKE ", " IN ", " IS "} {
+				if strings.Contains(part, op) {
+					colName := strings.Split(part, op)[0]
+					colName = strings.TrimSpace(colName)
+					if colName != "" && !isOperatorOrKeywordGorm(colName) {
+						// Add table prefix
+						prefixed := tableAlias + "." + colName + strings.TrimPrefix(part, colName)
+						modified = strings.ReplaceAll(modified, part, prefixed)
+						logger.Debug("Adding table prefix '%s' to column '%s' in JOIN condition", tableAlias, colName)
+					}
+					break
+				}
+			}
+		}
+	}
+
+	return modified
+}
+
+// isOperatorOrKeywordGorm checks if a string is likely an operator or SQL keyword (GORM version)
+func isOperatorOrKeywordGorm(s string) bool {
+	s = strings.ToUpper(strings.TrimSpace(s))
+	keywords := []string{"AND", "OR", "NOT", "IN", "IS", "NULL", "TRUE", "FALSE", "LIKE", "BETWEEN"}
+	for _, kw := range keywords {
+		if s == kw {
+			return true
+		}
+	}
+	return false
+}
+
 func (g *GormSelectQuery) WhereOr(query string, args ...interface{}) common.SelectQuery {
 	g.db = g.db.Or(query, args...)
 	return g
@@ -222,6 +291,27 @@ func (g *GormSelectQuery) Preload(relation string, conditions ...interface{}) co
 }
 
 func (g *GormSelectQuery) PreloadRelation(relation string, apply ...func(common.SelectQuery) common.SelectQuery) common.SelectQuery {
+	// Auto-detect relationship type and choose optimal loading strategy
+	// Get the model from GORM's statement if available
+	if g.db.Statement != nil && g.db.Statement.Model != nil {
+		relType := reflection.GetRelationType(g.db.Statement.Model, relation)
+
+		// Log the detected relationship type
+		logger.Debug("PreloadRelation '%s' detected as: %s", relation, relType)
+
+		// If this is a belongs-to or has-one relation, use JOIN for better performance
+		if relType.ShouldUseJoin() {
+			logger.Info("Using JOIN strategy for %s relation '%s'", relType, relation)
+			return g.JoinRelation(relation, apply...)
+		}
+
+		// For has-many, many-to-many, or unknown: use separate query (safer default)
+		if relType == reflection.RelationHasMany || relType == reflection.RelationManyToMany {
+			logger.Debug("Using separate query for %s relation '%s'", relType, relation)
+		}
+	}
+
+	// Use GORM's Preload (separate query strategy)
 	g.db = g.db.Preload(relation, func(db *gorm.DB) *gorm.DB {
 		if len(apply) == 0 {
 			return db
@@ -251,6 +341,42 @@ func (g *GormSelectQuery) PreloadRelation(relation string, apply ...func(common.
 	return g
 }
 
+func (g *GormSelectQuery) JoinRelation(relation string, apply ...func(common.SelectQuery) common.SelectQuery) common.SelectQuery {
+	// JoinRelation uses a JOIN instead of a separate preload query
+	// This is more efficient for many-to-one or one-to-one relationships
+	// as it avoids additional round trips to the database
+
+	// GORM's Joins() method forces a JOIN for the preload
+	logger.Debug("JoinRelation '%s' - Using GORM Joins() with automatic WHERE prefix addition", relation)
+
+	g.db = g.db.Joins(relation, func(db *gorm.DB) *gorm.DB {
+		if len(apply) == 0 {
+			return db
+		}
+
+		wrapper := &GormSelectQuery{
+			db:             db,
+			inJoinContext:  true,                      // Mark as JOIN context
+			joinTableAlias: strings.ToLower(relation), // Use relation name as alias
+		}
+		current := common.SelectQuery(wrapper)
+
+		for _, fn := range apply {
+			if fn != nil {
+				current = fn(current)
+			}
+		}
+
+		if finalGorm, ok := current.(*GormSelectQuery); ok {
+			return finalGorm.db
+		}
+
+		return db
+	})
+
+	return g
+}
+
 func (g *GormSelectQuery) Order(order string) common.SelectQuery {
 	g.db = g.db.Order(order)
 	return g
@@ -282,7 +408,15 @@ func (g *GormSelectQuery) Scan(ctx context.Context, dest interface{}) (err error
 			err = logger.HandlePanic("GormSelectQuery.Scan", r)
 		}
 	}()
-	return g.db.WithContext(ctx).Find(dest).Error
+	err = g.db.WithContext(ctx).Find(dest).Error
+	if err != nil {
+		// Log SQL string for debugging
+		sqlStr := g.db.ToSQL(func(tx *gorm.DB) *gorm.DB {
+			return tx.Find(dest)
+		})
+		logger.Error("GormSelectQuery.Scan failed. SQL: %s. Error: %v", sqlStr, err)
+	}
+	return err
 }
 
 func (g *GormSelectQuery) ScanModel(ctx context.Context) (err error) {
@@ -294,7 +428,15 @@ func (g *GormSelectQuery) ScanModel(ctx context.Context) (err error) {
 	if g.db.Statement.Model == nil {
 		return fmt.Errorf("ScanModel requires Model() to be set before scanning")
 	}
-	return g.db.WithContext(ctx).Find(g.db.Statement.Model).Error
+	err = g.db.WithContext(ctx).Find(g.db.Statement.Model).Error
+	if err != nil {
+		// Log SQL string for debugging
+		sqlStr := g.db.ToSQL(func(tx *gorm.DB) *gorm.DB {
+			return tx.Find(g.db.Statement.Model)
+		})
+		logger.Error("GormSelectQuery.ScanModel failed. SQL: %s. Error: %v", sqlStr, err)
+	}
+	return err
 }
 
 func (g *GormSelectQuery) Count(ctx context.Context) (count int, err error) {
@@ -306,6 +448,13 @@ func (g *GormSelectQuery) Count(ctx context.Context) (count int, err error) {
 	}()
 	var count64 int64
 	err = g.db.WithContext(ctx).Count(&count64).Error
+	if err != nil {
+		// Log SQL string for debugging
+		sqlStr := g.db.ToSQL(func(tx *gorm.DB) *gorm.DB {
+			return tx.Count(&count64)
+		})
+		logger.Error("GormSelectQuery.Count failed. SQL: %s. Error: %v", sqlStr, err)
+	}
 	return int(count64), err
 }
 
@@ -318,6 +467,13 @@ func (g *GormSelectQuery) Exists(ctx context.Context) (exists bool, err error) {
 	}()
 	var count int64
 	err = g.db.WithContext(ctx).Limit(1).Count(&count).Error
+	if err != nil {
+		// Log SQL string for debugging
+		sqlStr := g.db.ToSQL(func(tx *gorm.DB) *gorm.DB {
+			return tx.Limit(1).Count(&count)
+		})
+		logger.Error("GormSelectQuery.Exists failed. SQL: %s. Error: %v", sqlStr, err)
+	}
 	return count > 0, err
 }
 
@@ -456,6 +612,13 @@ func (g *GormUpdateQuery) Exec(ctx context.Context) (res common.Result, err erro
 		}
 	}()
 	result := g.db.WithContext(ctx).Updates(g.updates)
+	if result.Error != nil {
+		// Log SQL string for debugging
+		sqlStr := g.db.ToSQL(func(tx *gorm.DB) *gorm.DB {
+			return tx.Updates(g.updates)
+		})
+		logger.Error("GormUpdateQuery.Exec failed. SQL: %s. Error: %v", sqlStr, result.Error)
+	}
 	return &GormResult{result: result}, result.Error
 }
 
@@ -488,6 +651,13 @@ func (g *GormDeleteQuery) Exec(ctx context.Context) (res common.Result, err erro
 		}
 	}()
 	result := g.db.WithContext(ctx).Delete(g.model)
+	if result.Error != nil {
+		// Log SQL string for debugging
+		sqlStr := g.db.ToSQL(func(tx *gorm.DB) *gorm.DB {
+			return tx.Delete(g.model)
+		})
+		logger.Error("GormDeleteQuery.Exec failed. SQL: %s. Error: %v", sqlStr, result.Error)
+	}
 	return &GormResult{result: result}, result.Error
 }
 

pkg/common/interfaces.go

@@ -38,6 +38,7 @@ type SelectQuery interface {
 	LeftJoin(query string, args ...interface{}) SelectQuery
 	Preload(relation string, conditions ...interface{}) SelectQuery
 	PreloadRelation(relation string, apply ...func(SelectQuery) SelectQuery) SelectQuery
+	JoinRelation(relation string, apply ...func(SelectQuery) SelectQuery) SelectQuery
 	Order(order string) SelectQuery
 	Limit(n int) SelectQuery
 	Offset(n int) SelectQuery

pkg/common/sql_helpers.go

@@ -1,7 +1,6 @@
 package common
 
 import (
-	"fmt"
 	"strings"
 
 	"github.com/bitechdev/ResolveSpec/pkg/logger"
@@ -9,81 +8,40 @@ import (
 	"github.com/bitechdev/ResolveSpec/pkg/reflection"
 )
 
-// ValidateAndFixPreloadWhere validates that the WHERE clause for a preload contains
+// ValidateAndFixPreloadWhere validates and normalizes WHERE clauses for preloads
-// the relation prefix (alias). If not present, it attempts to add it to column references.
+//
-// Returns the fixed WHERE clause and an error if it cannot be safely fixed.
+// NOTE: For preload queries, table aliases from the parent query are not valid since
+// the preload executes as a separate query with its own table alias. This function
+// now simply validates basic syntax without requiring or adding prefixes.
+// The actual alias normalization happens in the database adapter layer.
+//
+// Returns the WHERE clause and an error if it contains obviously invalid syntax.
 func ValidateAndFixPreloadWhere(where string, relationName string) (string, error) {
 	if where == "" {
 		return where, nil
 	}
 
-	// Check if the relation name is already present in the WHERE clause
+	where = strings.TrimSpace(where)
-	lowerWhere := strings.ToLower(where)
-	lowerRelation := strings.ToLower(relationName)
 
-	// Check for patterns like "relation.", "relation ", or just "relation" followed by a dot
+	// Just do basic validation - don't require or add prefixes
-	if strings.Contains(lowerWhere, lowerRelation+".") ||
+	// The database adapter will handle alias normalization
-		strings.Contains(lowerWhere, "`"+lowerRelation+"`.") ||
+
-		strings.Contains(lowerWhere, "\""+lowerRelation+"\".") {
+	// Check if the WHERE clause contains any qualified column references
-		// Relation prefix is already present
+	// If it does, log a debug message but don't fail - let the adapter handle it
+	if strings.Contains(where, ".") {
+		logger.Debug("Preload WHERE clause for '%s' contains qualified column references: '%s'. "+
+			"Note: In preload context, table aliases from parent query are not available. "+
+			"The database adapter will normalize aliases automatically.", relationName, where)
+	}
+
+	// Validate that it's not empty or just whitespace
+	if where == "" {
 		return where, nil
 	}
 
-	// If the WHERE clause is complex (contains OR, parentheses, subqueries, etc.),
+	// Return the WHERE clause as-is
-	// we can't safely auto-fix it - require explicit prefix
+	// The BunSelectQuery.Where() method will handle alias normalization via normalizeTableAlias()
-	if strings.Contains(lowerWhere, " or ") ||
+	return where, nil
-		strings.Contains(where, "(") ||
-		strings.Contains(where, ")") {
-		return "", fmt.Errorf("preload WHERE condition must reference the relation '%s' (e.g., '%s.column_name'). Complex WHERE clauses with OR/parentheses must explicitly use the relation prefix", relationName, relationName)
-	}
-
-	// Try to add the relation prefix to simple column references
-	// This handles basic cases like "column = value" or "column = value AND other_column = value"
-	// Split by AND to handle multiple conditions (case-insensitive)
-	originalConditions := strings.Split(where, " AND ")
-
-	// If uppercase split didn't work, try lowercase
-	if len(originalConditions) == 1 {
-		originalConditions = strings.Split(where, " and ")
-	}
-
-	fixedConditions := make([]string, 0, len(originalConditions))
-
-	for _, cond := range originalConditions {
-		cond = strings.TrimSpace(cond)
-		if cond == "" {
-			continue
-		}
-
-		// Check if this condition already has a table prefix (contains a dot)
-		if strings.Contains(cond, ".") {
-			fixedConditions = append(fixedConditions, cond)
-			continue
-		}
-
-		// Check if this is a SQL expression/literal that shouldn't be prefixed
-		lowerCond := strings.ToLower(strings.TrimSpace(cond))
-		if IsSQLExpression(lowerCond) {
-			// Don't prefix SQL expressions like "true", "false", "1=1", etc.
-			fixedConditions = append(fixedConditions, cond)
-			continue
-		}
-
-		// Extract the column name (first identifier before operator)
-		columnName := ExtractColumnName(cond)
-		if columnName == "" {
-			// Can't identify column name, require explicit prefix
-			return "", fmt.Errorf("preload WHERE condition must reference the relation '%s' (e.g., '%s.column_name'). Cannot auto-fix condition: %s", relationName, relationName, cond)
-		}
-
-		// Add relation prefix to the column name only
-		fixedCond := strings.Replace(cond, columnName, relationName+"."+columnName, 1)
-		fixedConditions = append(fixedConditions, fixedCond)
-	}
-
-	fixedWhere := strings.Join(fixedConditions, " AND ")
-	logger.Debug("Auto-fixed preload WHERE clause: '%s' -> '%s'", where, fixedWhere)
-	return fixedWhere, nil
 }
 
 // IsSQLExpression checks if a condition is a SQL expression that shouldn't be prefixed
@@ -120,17 +78,22 @@ func IsTrivialCondition(cond string) bool {
 	return false
 }
 
-// SanitizeWhereClause removes trivial conditions and optionally prefixes table/relation names to columns
+// SanitizeWhereClause removes trivial conditions and fixes incorrect table prefixes
 // This function should be used everywhere a WHERE statement is sent to ensure clean, efficient SQL
 //
 // Parameters:
 //   - where: The WHERE clause string to sanitize
-//   - tableName: Optional table/relation name to prefix to column references (empty string to skip prefixing)
+//   - tableName: The correct table/relation name to use when fixing incorrect prefixes
+//   - options: Optional RequestOptions containing preload relations that should be allowed as valid prefixes
 //
 // Returns:
-//   - The sanitized WHERE clause with trivial conditions removed and columns optionally prefixed
+//   - The sanitized WHERE clause with trivial conditions removed and incorrect prefixes fixed
 //   - An empty string if all conditions were trivial or the input was empty
-func SanitizeWhereClause(where string, tableName string) string {
+//
+// Note: This function will NOT add prefixes to unprefixed columns. It will only fix
+// incorrect prefixes (e.g., wrong_table.column -> correct_table.column), unless the
+// prefix matches a preloaded relation name, in which case it's left unchanged.
+func SanitizeWhereClause(where string, tableName string, options ...*RequestOptions) string {
 	if where == "" {
 		return ""
 	}
@@ -146,6 +109,22 @@ func SanitizeWhereClause(where string, tableName string) string {
 		validColumns = getValidColumnsForTable(tableName)
 	}
 
+	// Build a set of allowed table prefixes (main table + preloaded relations)
+	allowedPrefixes := make(map[string]bool)
+	if tableName != "" {
+		allowedPrefixes[tableName] = true
+	}
+
+	// Add preload relation names as allowed prefixes
+	if len(options) > 0 && options[0] != nil {
+		for pi := range options[0].Preload {
+			if options[0].Preload[pi].Relation != "" {
+				allowedPrefixes[options[0].Preload[pi].Relation] = true
+				logger.Debug("Added preload relation '%s' as allowed table prefix", options[0].Preload[pi].Relation)
+			}
+		}
+	}
+
 	// Split by AND to handle multiple conditions
 	conditions := splitByAND(where)
 
@@ -166,22 +145,23 @@ func SanitizeWhereClause(where string, tableName string) string {
 			continue
 		}
 
-		// If tableName is provided and the condition doesn't already have a table prefix,
+		// If tableName is provided and the condition HAS a table prefix, check if it's correct
-		// attempt to add it
+		if tableName != "" && hasTablePrefix(condToCheck) {
-		if tableName != "" && !hasTablePrefix(condToCheck) {
+			// Extract the current prefix and column name
-			// Check if this is a SQL expression/literal that shouldn't be prefixed
+			currentPrefix, columnName := extractTableAndColumn(condToCheck)
-			if !IsSQLExpression(strings.ToLower(condToCheck)) {
+
-				// Extract the column name and prefix it
+			if currentPrefix != "" && columnName != "" {
-				columnName := ExtractColumnName(condToCheck)
+				// Check if the prefix is allowed (main table or preload relation)
-				if columnName != "" {
+				if !allowedPrefixes[currentPrefix] {
-					// Only prefix if this is a valid column in the model
+					// Prefix is not in the allowed list - only fix if it's a valid column in the main table
-					// If we don't have model info (validColumns is nil), prefix anyway for backward compatibility
 					if validColumns == nil || isValidColumn(columnName, validColumns) {
-						// Replace in the original condition (without stripped parens)
+						// Replace the incorrect prefix with the correct main table name
-						cond = strings.Replace(cond, columnName, tableName+"."+columnName, 1)
+						oldRef := currentPrefix + "." + columnName
-						logger.Debug("Prefixed column in condition: '%s'", cond)
+						newRef := tableName + "." + columnName
+						cond = strings.Replace(cond, oldRef, newRef, 1)
+						logger.Debug("Fixed incorrect table prefix in condition: '%s' -> '%s'", oldRef, newRef)
 					} else {
-						logger.Debug("Skipping prefix for '%s' - not a valid column in model", columnName)
+						logger.Debug("Skipping prefix fix for '%s.%s' - not a valid column in main table (might be preload relation)", currentPrefix, columnName)
 					}
 				}
 			}
@@ -330,6 +310,53 @@ func getValidColumnsForTable(tableName string) map[string]bool {
 	return columnMap
 }
 
+// extractTableAndColumn extracts the table prefix and column name from a qualified reference
+// For example: "users.status = 'active'" returns ("users", "status")
+// Returns empty strings if no table prefix is found
+func extractTableAndColumn(cond string) (table string, column string) {
+	// Common SQL operators to find the column reference
+	operators := []string{" = ", " != ", " <> ", " > ", " >= ", " < ", " <= ", " LIKE ", " like ", " IN ", " in ", " IS ", " is "}
+
+	var columnRef string
+
+	// Find the column reference (left side of the operator)
+	for _, op := range operators {
+		if idx := strings.Index(cond, op); idx > 0 {
+			columnRef = strings.TrimSpace(cond[:idx])
+			break
+		}
+	}
+
+	// If no operator found, the whole condition might be the column reference
+	if columnRef == "" {
+		parts := strings.Fields(cond)
+		if len(parts) > 0 {
+			columnRef = parts[0]
+		}
+	}
+
+	if columnRef == "" {
+		return "", ""
+	}
+
+	// Remove any quotes
+	columnRef = strings.Trim(columnRef, "`\"'")
+
+	// Check if it contains a dot (qualified reference)
+	if dotIdx := strings.LastIndex(columnRef, "."); dotIdx > 0 {
+		table = columnRef[:dotIdx]
+		column = columnRef[dotIdx+1:]
+
+		// Remove quotes from table and column if present
+		table = strings.Trim(table, "`\"'")
+		column = strings.Trim(column, "`\"'")
+
+		return table, column
+	}
+
+	return "", ""
+}
+
 // isValidColumn checks if a column name exists in the valid columns map
 // Handles case-insensitive comparison
 func isValidColumn(columnName string, validColumns map[string]bool) bool {

pkg/common/sql_helpers_test.go

@@ -32,29 +32,41 @@ func TestSanitizeWhereClause(t *testing.T) {
 			expected:  "",
 		},
 		{
-			name:      "valid condition with parentheses",
+			name:      "valid condition with parentheses - no prefix added",
 			where:     "(status = 'active')",
 			tableName: "users",
-			expected:  "users.status = 'active'",
+			expected:  "status = 'active'",
 		},
 		{
-			name:      "mixed trivial and valid conditions",
+			name:      "mixed trivial and valid conditions - no prefix added",
 			where:     "true AND status = 'active' AND 1=1",
 			tableName: "users",
-			expected:  "users.status = 'active'",
+			expected:  "status = 'active'",
 		},
 		{
-			name:      "condition already with table prefix",
+			name:      "condition with correct table prefix - unchanged",
 			where:     "users.status = 'active'",
 			tableName: "users",
 			expected:  "users.status = 'active'",
 		},
 		{
-			name:      "multiple valid conditions",
+			name:      "condition with incorrect table prefix - fixed",
-			where:     "status = 'active' AND age > 18",
+			where:     "wrong_table.status = 'active'",
+			tableName: "users",
+			expected:  "users.status = 'active'",
+		},
+		{
+			name:      "multiple conditions with incorrect prefix - fixed",
+			where:     "wrong_table.status = 'active' AND wrong_table.age > 18",
 			tableName: "users",
 			expected:  "users.status = 'active' AND users.age > 18",
 		},
+		{
+			name:      "multiple valid conditions without prefix - no prefix added",
+			where:     "status = 'active' AND age > 18",
+			tableName: "users",
+			expected:  "status = 'active' AND age > 18",
+		},
 		{
 			name:      "no table name provided",
 			where:     "status = 'active'",
@@ -67,6 +79,12 @@ func TestSanitizeWhereClause(t *testing.T) {
 			tableName: "users",
 			expected:  "",
 		},
+		{
+			name:      "mixed correct and incorrect prefixes",
+			where:     "users.status = 'active' AND wrong_table.age > 18",
+			tableName: "users",
+			expected:  "users.status = 'active' AND users.age > 18",
+		},
 	}
 
 	for _, tt := range tests {
@@ -159,6 +177,158 @@ func TestIsTrivialCondition(t *testing.T) {
 	}
 }
 
+func TestExtractTableAndColumn(t *testing.T) {
+	tests := []struct {
+		name          string
+		input         string
+		expectedTable string
+		expectedCol   string
+	}{
+		{
+			name:          "qualified column with equals",
+			input:         "users.status = 'active'",
+			expectedTable: "users",
+			expectedCol:   "status",
+		},
+		{
+			name:          "qualified column with greater than",
+			input:         "users.age > 18",
+			expectedTable: "users",
+			expectedCol:   "age",
+		},
+		{
+			name:          "qualified column with LIKE",
+			input:         "users.name LIKE '%john%'",
+			expectedTable: "users",
+			expectedCol:   "name",
+		},
+		{
+			name:          "qualified column with IN",
+			input:         "users.status IN ('active', 'pending')",
+			expectedTable: "users",
+			expectedCol:   "status",
+		},
+		{
+			name:          "unqualified column",
+			input:         "status = 'active'",
+			expectedTable: "",
+			expectedCol:   "",
+		},
+		{
+			name:          "qualified with backticks",
+			input:         "`users`.`status` = 'active'",
+			expectedTable: "users",
+			expectedCol:   "status",
+		},
+		{
+			name:          "schema.table.column reference",
+			input:         "public.users.status = 'active'",
+			expectedTable: "public.users",
+			expectedCol:   "status",
+		},
+		{
+			name:          "empty string",
+			input:         "",
+			expectedTable: "",
+			expectedCol:   "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			table, col := extractTableAndColumn(tt.input)
+			if table != tt.expectedTable || col != tt.expectedCol {
+				t.Errorf("extractTableAndColumn(%q) = (%q, %q); want (%q, %q)",
+					tt.input, table, col, tt.expectedTable, tt.expectedCol)
+			}
+		})
+	}
+}
+
+func TestSanitizeWhereClauseWithPreloads(t *testing.T) {
+	tests := []struct {
+		name      string
+		where     string
+		tableName string
+		options   *RequestOptions
+		expected  string
+	}{
+		{
+			name:      "preload relation prefix is preserved",
+			where:     "Department.name = 'Engineering'",
+			tableName: "users",
+			options: &RequestOptions{
+				Preload: []PreloadOption{
+					{Relation: "Department"},
+				},
+			},
+			expected: "Department.name = 'Engineering'",
+		},
+		{
+			name:      "multiple preload relations - all preserved",
+			where:     "Department.name = 'Engineering' AND Manager.status = 'active'",
+			tableName: "users",
+			options: &RequestOptions{
+				Preload: []PreloadOption{
+					{Relation: "Department"},
+					{Relation: "Manager"},
+				},
+			},
+			expected: "Department.name = 'Engineering' AND Manager.status = 'active'",
+		},
+		{
+			name:      "mix of main table and preload relation",
+			where:     "users.status = 'active' AND Department.name = 'Engineering'",
+			tableName: "users",
+			options: &RequestOptions{
+				Preload: []PreloadOption{
+					{Relation: "Department"},
+				},
+			},
+			expected: "users.status = 'active' AND Department.name = 'Engineering'",
+		},
+		{
+			name:      "incorrect prefix fixed when not a preload relation",
+			where:     "wrong_table.status = 'active' AND Department.name = 'Engineering'",
+			tableName: "users",
+			options: &RequestOptions{
+				Preload: []PreloadOption{
+					{Relation: "Department"},
+				},
+			},
+			expected: "users.status = 'active' AND Department.name = 'Engineering'",
+		},
+		{
+			name:      "no options provided - works as before",
+			where:     "wrong_table.status = 'active'",
+			tableName: "users",
+			options:   nil,
+			expected:  "users.status = 'active'",
+		},
+		{
+			name:      "empty preload list - works as before",
+			where:     "wrong_table.status = 'active'",
+			tableName: "users",
+			options:   &RequestOptions{Preload: []PreloadOption{}},
+			expected:  "users.status = 'active'",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			var result string
+			if tt.options != nil {
+				result = SanitizeWhereClause(tt.where, tt.tableName, tt.options)
+			} else {
+				result = SanitizeWhereClause(tt.where, tt.tableName)
+			}
+			if result != tt.expected {
+				t.Errorf("SanitizeWhereClause(%q, %q, options) = %q; want %q", tt.where, tt.tableName, result, tt.expected)
+			}
+		})
+	}
+}
+
 // Test model for model-aware sanitization tests
 type MasterTask struct {
 	ID     int    `bun:"id,pk"`
@@ -182,34 +352,52 @@ func TestSanitizeWhereClauseWithModel(t *testing.T) {
 		expected  string
 	}{
 		{
-			name:      "valid column gets prefixed",
+			name:      "valid column without prefix - no prefix added",
 			where:     "status = 'active'",
 			tableName: "mastertask",
+			expected:  "status = 'active'",
+		},
+		{
+			name:      "multiple valid columns without prefix - no prefix added",
+			where:     "status = 'active' AND user_id = 123",
+			tableName: "mastertask",
+			expected:  "status = 'active' AND user_id = 123",
+		},
+		{
+			name:      "incorrect table prefix on valid column - fixed",
+			where:     "wrong_table.status = 'active'",
+			tableName: "mastertask",
 			expected:  "mastertask.status = 'active'",
 		},
 		{
-			name:      "multiple valid columns get prefixed",
+			name:      "incorrect prefix on invalid column - not fixed",
-			where:     "status = 'active' AND user_id = 123",
+			where:     "wrong_table.invalid_column = 'value'",
 			tableName: "mastertask",
-			expected:  "mastertask.status = 'active' AND mastertask.user_id = 123",
+			expected:  "wrong_table.invalid_column = 'value'",
-		},
-		{
-			name:      "invalid column does not get prefixed",
-			where:     "invalid_column = 'value'",
-			tableName: "mastertask",
-			expected:  "invalid_column = 'value'",
 		},
 		{
 			name:      "mix of valid and trivial conditions",
 			where:     "true AND status = 'active' AND 1=1",
 			tableName: "mastertask",
+			expected:  "status = 'active'",
+		},
+		{
+			name:      "parentheses with valid column - no prefix added",
+			where:     "(status = 'active')",
+			tableName: "mastertask",
+			expected:  "status = 'active'",
+		},
+		{
+			name:      "correct prefix - unchanged",
+			where:     "mastertask.status = 'active'",
+			tableName: "mastertask",
 			expected:  "mastertask.status = 'active'",
 		},
 		{
-			name:      "parentheses with valid column",
+			name:      "multiple conditions with mixed prefixes",
-			where:     "(status = 'active')",
+			where:     "mastertask.status = 'active' AND wrong_table.user_id = 123",
 			tableName: "mastertask",
-			expected:  "mastertask.status = 'active'",
+			expected:  "mastertask.status = 'active' AND mastertask.user_id = 123",
 		},
 	}
 

pkg/common/sql_types_test.go

@@ -9,18 +9,18 @@ import (
 	"github.com/google/uuid"
 )
 
-// TestSqlInt16 tests SqlInt16 type
+// TestNewSqlInt16 tests NewSqlInt16 type
-func TestSqlInt16(t *testing.T) {
+func TestNewSqlInt16(t *testing.T) {
 	tests := []struct {
 		name     string
 		input    interface{}
 		expected SqlInt16
 	}{
-		{"int", 42, SqlInt16(42)},
+		{"int", 42, Null(int16(42), true)},
-		{"int32", int32(100), SqlInt16(100)},
+		{"int32", int32(100), NewSqlInt16(100)},
-		{"int64", int64(200), SqlInt16(200)},
+		{"int64", int64(200), NewSqlInt16(200)},
-		{"string", "123", SqlInt16(123)},
+		{"string", "123", NewSqlInt16(123)},
-		{"nil", nil, SqlInt16(0)},
+		{"nil", nil, Null(int16(0), false)},
 	}
 
 	for _, tt := range tests {
@@ -36,15 +36,15 @@ func TestSqlInt16(t *testing.T) {
 	}
 }
 
-func TestSqlInt16_Value(t *testing.T) {
+func TestNewSqlInt16_Value(t *testing.T) {
 	tests := []struct {
 		name     string
 		input    SqlInt16
 		expected driver.Value
 	}{
-		{"zero", SqlInt16(0), nil},
+		{"zero", Null(int16(0), false), nil},
-		{"positive", SqlInt16(42), int64(42)},
+		{"positive", NewSqlInt16(42), int16(42)},
-		{"negative", SqlInt16(-10), int64(-10)},
+		{"negative", NewSqlInt16(-10), int16(-10)},
 	}
 
 	for _, tt := range tests {
@@ -60,8 +60,8 @@ func TestSqlInt16_Value(t *testing.T) {
 	}
 }
 
-func TestSqlInt16_JSON(t *testing.T) {
+func TestNewSqlInt16_JSON(t *testing.T) {
-	n := SqlInt16(42)
+	n := NewSqlInt16(42)
 
 	// Marshal
 	data, err := json.Marshal(n)
@@ -78,24 +78,24 @@ func TestSqlInt16_JSON(t *testing.T) {
 	if err := json.Unmarshal([]byte("123"), &n2); err != nil {
 		t.Fatalf("Unmarshal failed: %v", err)
 	}
-	if n2 != 123 {
+	if n2.Int64() != 123 {
-		t.Errorf("expected 123, got %d", n2)
+		t.Errorf("expected 123, got %d", n2.Int64())
 	}
 }
 
-// TestSqlInt64 tests SqlInt64 type
+// TestNewSqlInt64 tests NewSqlInt64 type
-func TestSqlInt64(t *testing.T) {
+func TestNewSqlInt64(t *testing.T) {
 	tests := []struct {
 		name     string
 		input    interface{}
 		expected SqlInt64
 	}{
-		{"int", 42, SqlInt64(42)},
+		{"int", 42, NewSqlInt64(42)},
-		{"int32", int32(100), SqlInt64(100)},
+		{"int32", int32(100), NewSqlInt64(100)},
-		{"int64", int64(9223372036854775807), SqlInt64(9223372036854775807)},
+		{"int64", int64(9223372036854775807), NewSqlInt64(9223372036854775807)},
-		{"uint32", uint32(100), SqlInt64(100)},
+		{"uint32", uint32(100), NewSqlInt64(100)},
-		{"uint64", uint64(200), SqlInt64(200)},
+		{"uint64", uint64(200), NewSqlInt64(200)},
-		{"nil", nil, SqlInt64(0)},
+		{"nil", nil, SqlInt64{}},
 	}
 
 	for _, tt := range tests {
@@ -135,8 +135,8 @@ func TestSqlFloat64(t *testing.T) {
 			if n.Valid != tt.valid {
 				t.Errorf("expected valid=%v, got valid=%v", tt.valid, n.Valid)
 			}
-			if tt.valid && n.Float64 != tt.expected {
+			if tt.valid && n.Float64() != tt.expected {
-				t.Errorf("expected %v, got %v", tt.expected, n.Float64)
+				t.Errorf("expected %v, got %v", tt.expected, n.Float64())
 			}
 		})
 	}
@@ -162,7 +162,7 @@ func TestSqlTimeStamp(t *testing.T) {
 			if err := ts.Scan(tt.input); err != nil {
 				t.Fatalf("Scan failed: %v", err)
 			}
-			if ts.GetTime().IsZero() {
+			if ts.Time().IsZero() {
 				t.Error("expected non-zero time")
 			}
 		})
@@ -171,7 +171,7 @@ func TestSqlTimeStamp(t *testing.T) {
 
 func TestSqlTimeStamp_JSON(t *testing.T) {
 	now := time.Date(2024, 1, 15, 10, 30, 45, 0, time.UTC)
-	ts := SqlTimeStamp(now)
+	ts := NewSqlTimeStamp(now)
 
 	// Marshal
 	data, err := json.Marshal(ts)
@@ -188,8 +188,8 @@ func TestSqlTimeStamp_JSON(t *testing.T) {
 	if err := json.Unmarshal([]byte(`"2024-01-15T10:30:45"`), &ts2); err != nil {
 		t.Fatalf("Unmarshal failed: %v", err)
 	}
-	if ts2.GetTime().Year() != 2024 {
+	if ts2.Time().Year() != 2024 {
-		t.Errorf("expected year 2024, got %d", ts2.GetTime().Year())
+		t.Errorf("expected year 2024, got %d", ts2.Time().Year())
 	}
 
 	// Test null
@@ -226,7 +226,7 @@ func TestSqlDate(t *testing.T) {
 }
 
 func TestSqlDate_JSON(t *testing.T) {
-	date := SqlDate(time.Date(2024, 1, 15, 0, 0, 0, 0, time.UTC))
+	date := NewSqlDate(time.Date(2024, 1, 15, 0, 0, 0, 0, time.UTC))
 
 	// Marshal
 	data, err := json.Marshal(date)
@@ -471,8 +471,8 @@ func TestSqlUUID_Scan(t *testing.T) {
 			if u.Valid != tt.valid {
 				t.Errorf("expected valid=%v, got valid=%v", tt.valid, u.Valid)
 			}
-			if tt.valid && u.String != tt.expected {
+			if tt.valid && u.String() != tt.expected {
-				t.Errorf("expected %s, got %s", tt.expected, u.String)
+				t.Errorf("expected %s, got %s", tt.expected, u.String())
 			}
 		})
 	}
@@ -480,13 +480,13 @@ func TestSqlUUID_Scan(t *testing.T) {
 
 func TestSqlUUID_Value(t *testing.T) {
 	testUUID := uuid.New()
-	u := SqlUUID{String: testUUID.String(), Valid: true}
+	u := NewSqlUUID(testUUID)
 
 	val, err := u.Value()
 	if err != nil {
 		t.Fatalf("Value failed: %v", err)
 	}
-	if val != testUUID.String() {
+	if val != testUUID {
 		t.Errorf("expected %s, got %s", testUUID.String(), val)
 	}
 
@@ -503,7 +503,7 @@ func TestSqlUUID_Value(t *testing.T) {
 
 func TestSqlUUID_JSON(t *testing.T) {
 	testUUID := uuid.New()
-	u := SqlUUID{String: testUUID.String(), Valid: true}
+	u := NewSqlUUID(testUUID)
 
 	// Marshal
 	data, err := json.Marshal(u)
@@ -520,8 +520,8 @@ func TestSqlUUID_JSON(t *testing.T) {
 	if err := json.Unmarshal([]byte(`"`+testUUID.String()+`"`), &u2); err != nil {
 		t.Fatalf("Unmarshal failed: %v", err)
 	}
-	if u2.String != testUUID.String() {
+	if u2.String() != testUUID.String() {
-		t.Errorf("expected %s, got %s", testUUID.String(), u2.String)
+		t.Errorf("expected %s, got %s", testUUID.String(), u2.String())
 	}
 
 	// Test null

pkg/funcspec/function_api_test.go

@@ -16,8 +16,8 @@ import (
 
 // MockDatabase implements common.Database interface for testing
 type MockDatabase struct {
-	QueryFunc          func(ctx context.Context, dest interface{}, query string, args ...interface{}) error
+	QueryFunc            func(ctx context.Context, dest interface{}, query string, args ...interface{}) error
-	ExecFunc           func(ctx context.Context, query string, args ...interface{}) (common.Result, error)
+	ExecFunc             func(ctx context.Context, query string, args ...interface{}) (common.Result, error)
 	RunInTransactionFunc func(ctx context.Context, fn func(common.Database) error) error
 }
 
@@ -161,9 +161,9 @@ func TestExtractInputVariables(t *testing.T) {
 	handler := NewHandler(&MockDatabase{})
 
 	tests := []struct {
-		name          string
+		name         string
-		sqlQuery      string
+		sqlQuery     string
-		expectedVars  []string
+		expectedVars []string
 	}{
 		{
 			name:         "No variables",
@@ -340,9 +340,9 @@ func TestSqlQryWhere(t *testing.T) {
 // TestGetIPAddress tests IP address extraction
 func TestGetIPAddress(t *testing.T) {
 	tests := []struct {
-		name      string
+		name     string
-		setupReq  func() *http.Request
+		setupReq func() *http.Request
-		expected  string
+		expected string
 	}{
 		{
 			name: "X-Forwarded-For header",
@@ -782,9 +782,10 @@ func TestReplaceMetaVariables(t *testing.T) {
 	handler := NewHandler(&MockDatabase{})
 
 	userCtx := &security.UserContext{
-		UserID:    123,
+		UserID:     123,
-		UserName:  "testuser",
+		UserName:   "testuser",
-		SessionID: "456",
+		SessionID:  "ABC456",
+		SessionRID: 456,
 	}
 
 	metainfo := map[string]interface{}{
@@ -821,6 +822,12 @@ func TestReplaceMetaVariables(t *testing.T) {
 			expectedCheck: func(result string) bool {
 				return strings.Contains(result, "456")
 			},
+		}, {
+			name:     "Replace [id_session]",
+			sqlQuery: "SELECT * FROM sessions WHERE session_id = [id_session]",
+			expectedCheck: func(result string) bool {
+				return strings.Contains(result, "ABC456")
+			},
 		},
 	}
 

pkg/modelregistry/model_registry.go

@@ -28,6 +28,10 @@ func NewModelRegistry() *DefaultModelRegistry {
 	}
 }
 
+func GetDefaultRegistry() *DefaultModelRegistry {
+	return defaultRegistry
+}
+
 func SetDefaultRegistry(registry *DefaultModelRegistry) {
 	registriesMutex.Lock()
 	defer registriesMutex.Unlock()

pkg/openapi/README.md

@@ -0,0 +1,321 @@
+# OpenAPI Generator for ResolveSpec
+
+This package provides automatic OpenAPI 3.0 specification generation for ResolveSpec, RestheadSpec, and FuncSpec API frameworks.
+
+## Features
+
+- **Automatic Schema Generation**: Generates OpenAPI schemas from Go struct models
+- **Multiple Framework Support**: Works with RestheadSpec, ResolveSpec, and FuncSpec
+- **Dynamic Endpoint Discovery**: Automatically discovers all registered models and generates paths
+- **Query Parameter Access**: Access spec via `?openapi` on any endpoint or via `/openapi`
+- **Comprehensive Documentation**: Includes all request/response schemas, parameters, and security schemes
+
+## Quick Start
+
+### RestheadSpec Example
+
+```go
+import (
+    "github.com/bitechdev/ResolveSpec/pkg/openapi"
+    "github.com/bitechdev/ResolveSpec/pkg/restheadspec"
+    "github.com/gorilla/mux"
+)
+
+func main() {
+    // 1. Create handler
+    handler := restheadspec.NewHandlerWithGORM(db)
+
+    // 2. Register models
+    handler.registry.RegisterModel("public.users", User{})
+    handler.registry.RegisterModel("public.products", Product{})
+
+    // 3. Configure OpenAPI generator
+    handler.SetOpenAPIGenerator(func() (string, error) {
+        generator := openapi.NewGenerator(openapi.GeneratorConfig{
+            Title:       "My API",
+            Description: "API documentation",
+            Version:     "1.0.0",
+            BaseURL:     "http://localhost:8080",
+            Registry:    handler.registry.(*modelregistry.DefaultModelRegistry),
+            IncludeRestheadSpec: true,
+            IncludeResolveSpec:  false,
+            IncludeFuncSpec:     false,
+        })
+        return generator.GenerateJSON()
+    })
+
+    // 4. Setup routes (automatically includes /openapi endpoint)
+    router := mux.NewRouter()
+    restheadspec.SetupMuxRoutes(router, handler, nil)
+
+    // Start server
+    http.ListenAndServe(":8080", router)
+}
+```
+
+### ResolveSpec Example
+
+```go
+func main() {
+    // 1. Create handler
+    handler := resolvespec.NewHandlerWithGORM(db)
+
+    // 2. Register models
+    handler.RegisterModel("public", "users", User{})
+    handler.RegisterModel("public", "products", Product{})
+
+    // 3. Configure OpenAPI generator
+    handler.SetOpenAPIGenerator(func() (string, error) {
+        generator := openapi.NewGenerator(openapi.GeneratorConfig{
+            Title:       "My API",
+            Version:     "1.0.0",
+            Registry:    handler.registry.(*modelregistry.DefaultModelRegistry),
+            IncludeResolveSpec: true,
+        })
+        return generator.GenerateJSON()
+    })
+
+    // 4. Setup routes
+    router := mux.NewRouter()
+    resolvespec.SetupMuxRoutes(router, handler, nil)
+
+    http.ListenAndServe(":8080", router)
+}
+```
+
+## Accessing the OpenAPI Specification
+
+Once configured, the OpenAPI spec is available in two ways:
+
+### 1. Global `/openapi` Endpoint
+
+```bash
+curl http://localhost:8080/openapi
+```
+
+Returns the complete OpenAPI specification for all registered models.
+
+### 2. Query Parameter on Any Endpoint
+
+```bash
+# RestheadSpec
+curl http://localhost:8080/public/users?openapi
+
+# ResolveSpec
+curl http://localhost:8080/resolve/public/users?openapi
+```
+
+Returns the same OpenAPI specification as `/openapi`.
+
+## Generated Endpoints
+
+### RestheadSpec
+
+For each registered model (e.g., `public.users`), the following paths are generated:
+
+- `GET /public/users` - List records with header-based filtering
+- `POST /public/users` - Create a new record
+- `GET /public/users/{id}` - Get a single record
+- `PUT /public/users/{id}` - Update a record
+- `PATCH /public/users/{id}` - Partially update a record
+- `DELETE /public/users/{id}` - Delete a record
+- `GET /public/users/metadata` - Get table metadata
+- `OPTIONS /public/users` - CORS preflight
+
+### ResolveSpec
+
+For each registered model (e.g., `public.users`), the following paths are generated:
+
+- `POST /resolve/public/users` - Execute operations (read, create, meta)
+- `POST /resolve/public/users/{id}` - Execute operations (update, delete)
+- `GET /resolve/public/users` - Get metadata
+- `OPTIONS /resolve/public/users` - CORS preflight
+
+## Schema Generation
+
+The generator automatically extracts information from your Go struct tags:
+
+```go
+type User struct {
+    ID        int       `json:"id" gorm:"primaryKey" description:"User ID"`
+    Name      string    `json:"name" gorm:"not null" description:"User's full name"`
+    Email     string    `json:"email" gorm:"unique" description:"Email address"`
+    CreatedAt time.Time `json:"created_at" description:"Creation timestamp"`
+    Roles     []string  `json:"roles" description:"User roles"`
+}
+```
+
+This generates an OpenAPI schema with:
+- Property names from `json` tags
+- Required fields from `gorm:"not null"` and non-pointer types
+- Descriptions from `description` tags
+- Proper type mappings (int → integer, time.Time → string with format: date-time, etc.)
+
+## RestheadSpec Headers
+
+The generator documents all RestheadSpec HTTP headers:
+
+- `X-Filters` - JSON array of filter conditions
+- `X-Columns` - Comma-separated columns to select
+- `X-Sort` - JSON array of sort specifications
+- `X-Limit` - Maximum records to return
+- `X-Offset` - Records to skip
+- `X-Preload` - Relations to eager load
+- `X-Expand` - Relations to expand (LEFT JOIN)
+- `X-Distinct` - Enable DISTINCT queries
+- `X-Response-Format` - Response format (detail, simple, syncfusion)
+- `X-Clean-JSON` - Remove null/empty fields
+- `X-Custom-SQL-Where` - Custom WHERE clause (AND)
+- `X-Custom-SQL-Or` - Custom WHERE clause (OR)
+
+## ResolveSpec Request Body
+
+The generator documents the ResolveSpec request body structure:
+
+```json
+{
+  "operation": "read",
+  "data": {},
+  "id": 123,
+  "options": {
+    "limit": 10,
+    "offset": 0,
+    "filters": [
+      {"column": "status", "operator": "eq", "value": "active"}
+    ],
+    "sort": [
+      {"column": "created_at", "direction": "desc"}
+    ]
+  }
+}
+```
+
+## Security Schemes
+
+The generator automatically includes common security schemes:
+
+- **BearerAuth**: JWT Bearer token authentication
+- **SessionToken**: Session token in Authorization header
+- **CookieAuth**: Cookie-based session authentication
+- **HeaderAuth**: Header-based user authentication (X-User-ID)
+
+## FuncSpec Custom Endpoints
+
+For FuncSpec, you can manually register custom SQL endpoints:
+
+```go
+funcSpecEndpoints := map[string]openapi.FuncSpecEndpoint{
+    "/api/reports/sales": {
+        Path:        "/api/reports/sales",
+        Method:      "GET",
+        Summary:     "Get sales report",
+        Description: "Returns sales data for specified date range",
+        SQLQuery:    "SELECT * FROM sales WHERE date BETWEEN [start_date] AND [end_date]",
+        Parameters:  []string{"start_date", "end_date"},
+    },
+}
+
+generator := openapi.NewGenerator(openapi.GeneratorConfig{
+    // ... other config
+    IncludeFuncSpec:   true,
+    FuncSpecEndpoints: funcSpecEndpoints,
+})
+```
+
+## Combining Multiple Frameworks
+
+You can generate a unified OpenAPI spec that includes multiple frameworks:
+
+```go
+generator := openapi.NewGenerator(openapi.GeneratorConfig{
+    Title:       "Unified API",
+    Version:     "1.0.0",
+    Registry:    sharedRegistry,
+    IncludeRestheadSpec: true,
+    IncludeResolveSpec:  true,
+    IncludeFuncSpec:     true,
+    FuncSpecEndpoints:   funcSpecEndpoints,
+})
+```
+
+This will generate a complete spec with all endpoints from all frameworks.
+
+## Advanced Customization
+
+You can customize the generated spec further:
+
+```go
+handler.SetOpenAPIGenerator(func() (string, error) {
+    generator := openapi.NewGenerator(config)
+
+    // Generate initial spec
+    spec, err := generator.Generate()
+    if err != nil {
+        return "", err
+    }
+
+    // Add contact information
+    spec.Info.Contact = &openapi.Contact{
+        Name:  "API Support",
+        Email: "support@example.com",
+        URL:   "https://example.com/support",
+    }
+
+    // Add additional servers
+    spec.Servers = append(spec.Servers, openapi.Server{
+        URL:         "https://staging.example.com",
+        Description: "Staging Server",
+    })
+
+    // Convert back to JSON
+    data, _ := json.MarshalIndent(spec, "", "  ")
+    return string(data), nil
+})
+```
+
+## Using with Swagger UI
+
+You can serve the generated OpenAPI spec with Swagger UI:
+
+1. Get the spec from `/openapi`
+2. Load it in Swagger UI at `https://petstore.swagger.io/`
+3. Or self-host Swagger UI and point it to your `/openapi` endpoint
+
+Example with self-hosted Swagger UI:
+
+```go
+// Serve Swagger UI static files
+router.PathPrefix("/swagger/").Handler(
+    http.StripPrefix("/swagger/", http.FileServer(http.Dir("./swagger-ui"))),
+)
+
+// Configure Swagger UI to use /openapi
+```
+
+## Testing
+
+You can test the OpenAPI endpoint:
+
+```bash
+# Get the full spec
+curl http://localhost:8080/openapi | jq
+
+# Validate with openapi-generator
+openapi-generator validate -i http://localhost:8080/openapi
+
+# Generate client SDKs
+openapi-generator generate -i http://localhost:8080/openapi -g typescript-fetch -o ./client
+```
+
+## Complete Example
+
+See `example.go` in this package for complete, runnable examples including:
+- Basic RestheadSpec setup
+- Basic ResolveSpec setup
+- Combining both frameworks
+- Adding FuncSpec endpoints
+- Advanced customization
+
+## License
+
+Part of the ResolveSpec project.

pkg/openapi/example.go

@@ -0,0 +1,236 @@
+package openapi
+
+import (
+	"github.com/gorilla/mux"
+	"gorm.io/gorm"
+
+	"github.com/bitechdev/ResolveSpec/pkg/modelregistry"
+	"github.com/bitechdev/ResolveSpec/pkg/resolvespec"
+	"github.com/bitechdev/ResolveSpec/pkg/restheadspec"
+)
+
+// ExampleRestheadSpec shows how to configure OpenAPI generation for RestheadSpec
+func ExampleRestheadSpec(db *gorm.DB) {
+	// 1. Create registry and register models
+	registry := modelregistry.NewModelRegistry()
+	// registry.RegisterModel("public.users", User{})
+	// registry.RegisterModel("public.products", Product{})
+
+	// 2. Create handler with custom registry
+	// import "github.com/bitechdev/ResolveSpec/pkg/common/adapters/database"
+	// gormAdapter := database.NewGormAdapter(db)
+	// handler := restheadspec.NewHandler(gormAdapter, registry)
+	// Or use the convenience function (creates its own registry):
+	handler := restheadspec.NewHandlerWithGORM(db)
+
+	// 3. Configure OpenAPI generator
+	handler.SetOpenAPIGenerator(func() (string, error) {
+		generator := NewGenerator(GeneratorConfig{
+			Title:               "My API",
+			Description:         "API documentation for my application",
+			Version:             "1.0.0",
+			BaseURL:             "http://localhost:8080",
+			Registry:            registry,
+			IncludeRestheadSpec: true,
+			IncludeResolveSpec:  false,
+			IncludeFuncSpec:     false,
+		})
+		return generator.GenerateJSON()
+	})
+
+	// 4. Setup routes (includes /openapi endpoint)
+	router := mux.NewRouter()
+	restheadspec.SetupMuxRoutes(router, handler, nil)
+
+	// Now the following endpoints are available:
+	// GET /openapi                     - Full OpenAPI spec
+	// GET /public/users?openapi        - OpenAPI spec
+	// GET /public/products?openapi     - OpenAPI spec
+	// etc.
+}
+
+// ExampleResolveSpec shows how to configure OpenAPI generation for ResolveSpec
+func ExampleResolveSpec(db *gorm.DB) {
+	// 1. Create registry and register models
+	registry := modelregistry.NewModelRegistry()
+	// registry.RegisterModel("public.users", User{})
+	// registry.RegisterModel("public.products", Product{})
+
+	// 2. Create handler with custom registry
+	// import "github.com/bitechdev/ResolveSpec/pkg/common/adapters/database"
+	// gormAdapter := database.NewGormAdapter(db)
+	// handler := resolvespec.NewHandler(gormAdapter, registry)
+	// Or use the convenience function (creates its own registry):
+	handler := resolvespec.NewHandlerWithGORM(db)
+	// Note: handler.RegisterModel("schema", "entity", model) can be used
+
+	// 3. Configure OpenAPI generator
+	handler.SetOpenAPIGenerator(func() (string, error) {
+		generator := NewGenerator(GeneratorConfig{
+			Title:               "My API",
+			Description:         "API documentation for my application",
+			Version:             "1.0.0",
+			BaseURL:             "http://localhost:8080",
+			Registry:            registry,
+			IncludeRestheadSpec: false,
+			IncludeResolveSpec:  true,
+			IncludeFuncSpec:     false,
+		})
+		return generator.GenerateJSON()
+	})
+
+	// 4. Setup routes (includes /openapi endpoint)
+	router := mux.NewRouter()
+	resolvespec.SetupMuxRoutes(router, handler, nil)
+
+	// Now the following endpoints are available:
+	// GET /openapi                          - Full OpenAPI spec
+	// POST /resolve/public/users?openapi    - OpenAPI spec
+	// POST /resolve/public/products?openapi - OpenAPI spec
+	// etc.
+}
+
+// ExampleBothSpecs shows how to combine both RestheadSpec and ResolveSpec
+func ExampleBothSpecs(db *gorm.DB) {
+	// Create shared registry
+	sharedRegistry := modelregistry.NewModelRegistry()
+	// Register models once
+	// sharedRegistry.RegisterModel("public.users", User{})
+	// sharedRegistry.RegisterModel("public.products", Product{})
+
+	// Create handlers - they will have separate registries initially
+	restheadHandler := restheadspec.NewHandlerWithGORM(db)
+	resolveHandler := resolvespec.NewHandlerWithGORM(db)
+
+	// Note: If you want to use a shared registry, create handlers manually:
+	// import "github.com/bitechdev/ResolveSpec/pkg/common/adapters/database"
+	// gormAdapter := database.NewGormAdapter(db)
+	// restheadHandler := restheadspec.NewHandler(gormAdapter, sharedRegistry)
+	// resolveHandler := resolvespec.NewHandler(gormAdapter, sharedRegistry)
+
+	// Configure OpenAPI generator for both
+	generatorFunc := func() (string, error) {
+		generator := NewGenerator(GeneratorConfig{
+			Title:               "My Unified API",
+			Description:         "Complete API documentation with both RestheadSpec and ResolveSpec endpoints",
+			Version:             "1.0.0",
+			BaseURL:             "http://localhost:8080",
+			Registry:            sharedRegistry,
+			IncludeRestheadSpec: true,
+			IncludeResolveSpec:  true,
+			IncludeFuncSpec:     false,
+		})
+		return generator.GenerateJSON()
+	}
+
+	restheadHandler.SetOpenAPIGenerator(generatorFunc)
+	resolveHandler.SetOpenAPIGenerator(generatorFunc)
+
+	// Setup routes
+	router := mux.NewRouter()
+	restheadspec.SetupMuxRoutes(router, restheadHandler, nil)
+
+	// Add ResolveSpec routes under /resolve prefix
+	resolveRouter := router.PathPrefix("/resolve").Subrouter()
+	resolvespec.SetupMuxRoutes(resolveRouter, resolveHandler, nil)
+
+	// Now you have both styles of API available:
+	// GET /openapi                              - Full OpenAPI spec (both styles)
+	// GET /public/users                         - RestheadSpec list endpoint
+	// POST /resolve/public/users                - ResolveSpec operation endpoint
+	// GET /public/users?openapi                 - OpenAPI spec
+	// POST /resolve/public/users?openapi        - OpenAPI spec
+}
+
+// ExampleWithFuncSpec shows how to add FuncSpec endpoints to OpenAPI
+func ExampleWithFuncSpec() {
+	// FuncSpec endpoints need to be registered manually since they don't use model registry
+	generatorFunc := func() (string, error) {
+		funcSpecEndpoints := map[string]FuncSpecEndpoint{
+			"/api/reports/sales": {
+				Path:        "/api/reports/sales",
+				Method:      "GET",
+				Summary:     "Get sales report",
+				Description: "Returns sales data for the specified date range",
+				SQLQuery:    "SELECT * FROM sales WHERE date BETWEEN [start_date] AND [end_date]",
+				Parameters:  []string{"start_date", "end_date"},
+			},
+			"/api/analytics/users": {
+				Path:        "/api/analytics/users",
+				Method:      "GET",
+				Summary:     "Get user analytics",
+				Description: "Returns user activity analytics",
+				SQLQuery:    "SELECT * FROM user_analytics WHERE user_id = [user_id]",
+				Parameters:  []string{"user_id"},
+			},
+		}
+
+		generator := NewGenerator(GeneratorConfig{
+			Title:               "My API with Custom Queries",
+			Description:         "API with FuncSpec custom SQL endpoints",
+			Version:             "1.0.0",
+			BaseURL:             "http://localhost:8080",
+			Registry:            modelregistry.NewModelRegistry(),
+			IncludeRestheadSpec: false,
+			IncludeResolveSpec:  false,
+			IncludeFuncSpec:     true,
+			FuncSpecEndpoints:   funcSpecEndpoints,
+		})
+		return generator.GenerateJSON()
+	}
+
+	// Use this generator function with your handlers
+	_ = generatorFunc
+}
+
+// ExampleCustomization shows advanced customization options
+func ExampleCustomization() {
+	// Create registry and register models with descriptions using struct tags
+	registry := modelregistry.NewModelRegistry()
+
+	// type User struct {
+	//     ID    int    `json:"id" gorm:"primaryKey" description:"Unique user identifier"`
+	//     Name  string `json:"name" description:"User's full name"`
+	//     Email string `json:"email" gorm:"unique" description:"User's email address"`
+	// }
+	// registry.RegisterModel("public.users", User{})
+
+	// Advanced configuration - create generator function
+	generatorFunc := func() (string, error) {
+		generator := NewGenerator(GeneratorConfig{
+			Title:               "My Advanced API",
+			Description:         "Comprehensive API documentation with custom configuration",
+			Version:             "2.1.0",
+			BaseURL:             "https://api.myapp.com",
+			Registry:            registry,
+			IncludeRestheadSpec: true,
+			IncludeResolveSpec:  true,
+			IncludeFuncSpec:     false,
+		})
+
+		// Generate the spec
+		// spec, err := generator.Generate()
+		// if err != nil {
+		//     return "", err
+		// }
+
+		// Customize the spec further if needed
+		// spec.Info.Contact = &Contact{
+		//     Name:  "API Support",
+		//     Email: "support@myapp.com",
+		//     URL:   "https://myapp.com/support",
+		// }
+
+		// Add additional servers
+		// spec.Servers = append(spec.Servers, Server{
+		//     URL:         "https://staging-api.myapp.com",
+		//     Description: "Staging Server",
+		// })
+
+		// Convert back to JSON - or use GenerateJSON() for simple cases
+		return generator.GenerateJSON()
+	}
+
+	// Use this generator function with your handlers
+	_ = generatorFunc
+}

pkg/openapi/generator.go

@@ -0,0 +1,513 @@
+package openapi
+
+import (
+	"encoding/json"
+	"fmt"
+	"reflect"
+	"strings"
+
+	"github.com/bitechdev/ResolveSpec/pkg/modelregistry"
+)
+
+// OpenAPISpec represents the OpenAPI 3.0 specification structure
+type OpenAPISpec struct {
+	OpenAPI    string                `json:"openapi"`
+	Info       Info                  `json:"info"`
+	Servers    []Server              `json:"servers,omitempty"`
+	Paths      map[string]PathItem   `json:"paths"`
+	Components Components            `json:"components"`
+	Security   []map[string][]string `json:"security,omitempty"`
+}
+
+type Info struct {
+	Title       string   `json:"title"`
+	Description string   `json:"description,omitempty"`
+	Version     string   `json:"version"`
+	Contact     *Contact `json:"contact,omitempty"`
+}
+
+type Contact struct {
+	Name  string `json:"name,omitempty"`
+	URL   string `json:"url,omitempty"`
+	Email string `json:"email,omitempty"`
+}
+
+type Server struct {
+	URL         string `json:"url"`
+	Description string `json:"description,omitempty"`
+}
+
+type PathItem struct {
+	Get     *Operation `json:"get,omitempty"`
+	Post    *Operation `json:"post,omitempty"`
+	Put     *Operation `json:"put,omitempty"`
+	Patch   *Operation `json:"patch,omitempty"`
+	Delete  *Operation `json:"delete,omitempty"`
+	Options *Operation `json:"options,omitempty"`
+}
+
+type Operation struct {
+	Summary     string                `json:"summary,omitempty"`
+	Description string                `json:"description,omitempty"`
+	OperationID string                `json:"operationId,omitempty"`
+	Tags        []string              `json:"tags,omitempty"`
+	Parameters  []Parameter           `json:"parameters,omitempty"`
+	RequestBody *RequestBody          `json:"requestBody,omitempty"`
+	Responses   map[string]Response   `json:"responses"`
+	Security    []map[string][]string `json:"security,omitempty"`
+}
+
+type Parameter struct {
+	Name        string      `json:"name"`
+	In          string      `json:"in"` // "query", "header", "path", "cookie"
+	Description string      `json:"description,omitempty"`
+	Required    bool        `json:"required,omitempty"`
+	Schema      *Schema     `json:"schema,omitempty"`
+	Example     interface{} `json:"example,omitempty"`
+}
+
+type RequestBody struct {
+	Description string               `json:"description,omitempty"`
+	Required    bool                 `json:"required,omitempty"`
+	Content     map[string]MediaType `json:"content"`
+}
+
+type MediaType struct {
+	Schema  *Schema     `json:"schema,omitempty"`
+	Example interface{} `json:"example,omitempty"`
+}
+
+type Response struct {
+	Description string               `json:"description"`
+	Content     map[string]MediaType `json:"content,omitempty"`
+}
+
+type Components struct {
+	Schemas         map[string]Schema         `json:"schemas,omitempty"`
+	SecuritySchemes map[string]SecurityScheme `json:"securitySchemes,omitempty"`
+}
+
+type Schema struct {
+	Type                 string             `json:"type,omitempty"`
+	Format               string             `json:"format,omitempty"`
+	Description          string             `json:"description,omitempty"`
+	Properties           map[string]*Schema `json:"properties,omitempty"`
+	Items                *Schema            `json:"items,omitempty"`
+	Required             []string           `json:"required,omitempty"`
+	Ref                  string             `json:"$ref,omitempty"`
+	Enum                 []interface{}      `json:"enum,omitempty"`
+	Example              interface{}        `json:"example,omitempty"`
+	AdditionalProperties interface{}        `json:"additionalProperties,omitempty"`
+	OneOf                []*Schema          `json:"oneOf,omitempty"`
+	AnyOf                []*Schema          `json:"anyOf,omitempty"`
+}
+
+type SecurityScheme struct {
+	Type         string `json:"type"` // "apiKey", "http", "oauth2", "openIdConnect"
+	Description  string `json:"description,omitempty"`
+	Name         string `json:"name,omitempty"`         // For apiKey
+	In           string `json:"in,omitempty"`           // For apiKey: "query", "header", "cookie"
+	Scheme       string `json:"scheme,omitempty"`       // For http: "basic", "bearer"
+	BearerFormat string `json:"bearerFormat,omitempty"` // For http bearer
+}
+
+// GeneratorConfig holds configuration for OpenAPI spec generation
+type GeneratorConfig struct {
+	Title               string
+	Description         string
+	Version             string
+	BaseURL             string
+	Registry            *modelregistry.DefaultModelRegistry
+	IncludeRestheadSpec bool
+	IncludeResolveSpec  bool
+	IncludeFuncSpec     bool
+	FuncSpecEndpoints   map[string]FuncSpecEndpoint // path -> endpoint info
+}
+
+// FuncSpecEndpoint represents a FuncSpec endpoint for OpenAPI generation
+type FuncSpecEndpoint struct {
+	Path        string
+	Method      string
+	Summary     string
+	Description string
+	SQLQuery    string
+	Parameters  []string // Parameter names extracted from SQL
+}
+
+// Generator creates OpenAPI specifications
+type Generator struct {
+	config GeneratorConfig
+}
+
+// NewGenerator creates a new OpenAPI generator
+func NewGenerator(config GeneratorConfig) *Generator {
+	if config.Title == "" {
+		config.Title = "ResolveSpec API"
+	}
+	if config.Version == "" {
+		config.Version = "1.0.0"
+	}
+	return &Generator{config: config}
+}
+
+// Generate creates the complete OpenAPI specification
+func (g *Generator) Generate() (*OpenAPISpec, error) {
+	spec := &OpenAPISpec{
+		OpenAPI: "3.0.0",
+		Info: Info{
+			Title:       g.config.Title,
+			Description: g.config.Description,
+			Version:     g.config.Version,
+		},
+		Paths: make(map[string]PathItem),
+		Components: Components{
+			Schemas:         make(map[string]Schema),
+			SecuritySchemes: g.generateSecuritySchemes(),
+		},
+	}
+
+	if g.config.BaseURL != "" {
+		spec.Servers = []Server{
+			{URL: g.config.BaseURL, Description: "API Server"},
+		}
+	}
+
+	// Add common schemas
+	g.addCommonSchemas(spec)
+
+	// Generate paths and schemas from registered models
+	if err := g.generateFromModels(spec); err != nil {
+		return nil, err
+	}
+
+	return spec, nil
+}
+
+// GenerateJSON generates OpenAPI spec as JSON string
+func (g *Generator) GenerateJSON() (string, error) {
+	spec, err := g.Generate()
+	if err != nil {
+		return "", err
+	}
+
+	data, err := json.MarshalIndent(spec, "", "  ")
+	if err != nil {
+		return "", fmt.Errorf("failed to marshal spec: %w", err)
+	}
+
+	return string(data), nil
+}
+
+// generateSecuritySchemes creates security scheme definitions
+func (g *Generator) generateSecuritySchemes() map[string]SecurityScheme {
+	return map[string]SecurityScheme{
+		"BearerAuth": {
+			Type:         "http",
+			Scheme:       "bearer",
+			BearerFormat: "JWT",
+			Description:  "JWT Bearer token authentication",
+		},
+		"SessionToken": {
+			Type:        "apiKey",
+			In:          "header",
+			Name:        "Authorization",
+			Description: "Session token authentication",
+		},
+		"CookieAuth": {
+			Type:        "apiKey",
+			In:          "cookie",
+			Name:        "session_token",
+			Description: "Cookie-based session authentication",
+		},
+		"HeaderAuth": {
+			Type:        "apiKey",
+			In:          "header",
+			Name:        "X-User-ID",
+			Description: "Header-based user authentication",
+		},
+	}
+}
+
+// addCommonSchemas adds common reusable schemas
+func (g *Generator) addCommonSchemas(spec *OpenAPISpec) {
+	// Response wrapper schema
+	spec.Components.Schemas["Response"] = Schema{
+		Type: "object",
+		Properties: map[string]*Schema{
+			"success":  {Type: "boolean", Description: "Indicates if the operation was successful"},
+			"data":     {Description: "The response data"},
+			"metadata": {Ref: "#/components/schemas/Metadata"},
+			"error":    {Ref: "#/components/schemas/APIError"},
+		},
+	}
+
+	// Metadata schema
+	spec.Components.Schemas["Metadata"] = Schema{
+		Type: "object",
+		Properties: map[string]*Schema{
+			"total":     {Type: "integer", Description: "Total number of records"},
+			"count":     {Type: "integer", Description: "Number of records in this response"},
+			"filtered":  {Type: "integer", Description: "Number of records after filtering"},
+			"limit":     {Type: "integer", Description: "Limit applied"},
+			"offset":    {Type: "integer", Description: "Offset applied"},
+			"rowNumber": {Type: "integer", Description: "Row number for cursor pagination"},
+		},
+	}
+
+	// APIError schema
+	spec.Components.Schemas["APIError"] = Schema{
+		Type: "object",
+		Properties: map[string]*Schema{
+			"code":    {Type: "string", Description: "Error code"},
+			"message": {Type: "string", Description: "Error message"},
+			"details": {Type: "string", Description: "Detailed error information"},
+		},
+	}
+
+	// RequestOptions schema
+	spec.Components.Schemas["RequestOptions"] = Schema{
+		Type: "object",
+		Properties: map[string]*Schema{
+			"preload": {
+				Type:        "array",
+				Description: "Relations to eager load",
+				Items:       &Schema{Ref: "#/components/schemas/PreloadOption"},
+			},
+			"columns": {
+				Type:        "array",
+				Description: "Columns to select",
+				Items:       &Schema{Type: "string"},
+			},
+			"omitColumns": {
+				Type:        "array",
+				Description: "Columns to exclude",
+				Items:       &Schema{Type: "string"},
+			},
+			"filters": {
+				Type:        "array",
+				Description: "Filter conditions",
+				Items:       &Schema{Ref: "#/components/schemas/FilterOption"},
+			},
+			"sort": {
+				Type:        "array",
+				Description: "Sort specifications",
+				Items:       &Schema{Ref: "#/components/schemas/SortOption"},
+			},
+			"limit":  {Type: "integer", Description: "Maximum number of records"},
+			"offset": {Type: "integer", Description: "Number of records to skip"},
+		},
+	}
+
+	// FilterOption schema
+	spec.Components.Schemas["FilterOption"] = Schema{
+		Type: "object",
+		Properties: map[string]*Schema{
+			"column":        {Type: "string", Description: "Column name"},
+			"operator":      {Type: "string", Description: "Comparison operator", Enum: []interface{}{"eq", "neq", "gt", "lt", "gte", "lte", "like", "ilike", "in", "not_in", "between", "is_null", "is_not_null"}},
+			"value":         {Description: "Filter value"},
+			"logicOperator": {Type: "string", Description: "Logic operator", Enum: []interface{}{"AND", "OR"}},
+		},
+	}
+
+	// SortOption schema
+	spec.Components.Schemas["SortOption"] = Schema{
+		Type: "object",
+		Properties: map[string]*Schema{
+			"column":    {Type: "string", Description: "Column name"},
+			"direction": {Type: "string", Description: "Sort direction", Enum: []interface{}{"asc", "desc"}},
+		},
+	}
+
+	// PreloadOption schema
+	spec.Components.Schemas["PreloadOption"] = Schema{
+		Type: "object",
+		Properties: map[string]*Schema{
+			"relation": {Type: "string", Description: "Relation name"},
+			"columns": {
+				Type:        "array",
+				Description: "Columns to select from related table",
+				Items:       &Schema{Type: "string"},
+			},
+		},
+	}
+
+	// ResolveSpec RequestBody schema
+	spec.Components.Schemas["ResolveSpecRequest"] = Schema{
+		Type: "object",
+		Properties: map[string]*Schema{
+			"operation": {Type: "string", Description: "Operation type", Enum: []interface{}{"read", "create", "update", "delete", "meta"}},
+			"data":      {Description: "Payload data (object or array)"},
+			"id":        {Type: "integer", Description: "Record ID for single operations"},
+			"options":   {Ref: "#/components/schemas/RequestOptions"},
+		},
+	}
+}
+
+// generateFromModels generates paths and schemas from registered models
+func (g *Generator) generateFromModels(spec *OpenAPISpec) error {
+	if g.config.Registry == nil {
+		return fmt.Errorf("model registry is required")
+	}
+
+	models := g.config.Registry.GetAllModels()
+
+	for name, model := range models {
+		// Parse schema.entity from model name
+		schema, entity := parseModelName(name)
+
+		// Generate schema for this model
+		modelSchema := g.generateModelSchema(model)
+		schemaName := formatSchemaName(schema, entity)
+		spec.Components.Schemas[schemaName] = modelSchema
+
+		// Generate paths for different frameworks
+		if g.config.IncludeRestheadSpec {
+			g.generateRestheadSpecPaths(spec, schema, entity, schemaName)
+		}
+
+		if g.config.IncludeResolveSpec {
+			g.generateResolveSpecPaths(spec, schema, entity, schemaName)
+		}
+	}
+
+	// Generate FuncSpec paths if configured
+	if g.config.IncludeFuncSpec && len(g.config.FuncSpecEndpoints) > 0 {
+		g.generateFuncSpecPaths(spec)
+	}
+
+	return nil
+}
+
+// generateModelSchema creates an OpenAPI schema from a Go struct
+func (g *Generator) generateModelSchema(model interface{}) Schema {
+	schema := Schema{
+		Type:       "object",
+		Properties: make(map[string]*Schema),
+		Required:   []string{},
+	}
+
+	modelType := reflect.TypeOf(model)
+	if modelType.Kind() == reflect.Ptr {
+		modelType = modelType.Elem()
+	}
+	if modelType.Kind() != reflect.Struct {
+		return schema
+	}
+
+	for i := 0; i < modelType.NumField(); i++ {
+		field := modelType.Field(i)
+
+		// Skip unexported fields
+		if !field.IsExported() {
+			continue
+		}
+
+		// Get JSON tag name
+		jsonTag := field.Tag.Get("json")
+		if jsonTag == "-" {
+			continue
+		}
+
+		fieldName := strings.Split(jsonTag, ",")[0]
+		if fieldName == "" {
+			fieldName = field.Name
+		}
+
+		// Generate property schema
+		propSchema := g.generatePropertySchema(field)
+		schema.Properties[fieldName] = propSchema
+
+		// Check if field is required (not a pointer and no omitempty)
+		if field.Type.Kind() != reflect.Ptr && !strings.Contains(jsonTag, "omitempty") {
+			schema.Required = append(schema.Required, fieldName)
+		}
+	}
+
+	return schema
+}
+
+// generatePropertySchema creates a schema for a struct field
+func (g *Generator) generatePropertySchema(field reflect.StructField) *Schema {
+	schema := &Schema{}
+
+	fieldType := field.Type
+	if fieldType.Kind() == reflect.Ptr {
+		fieldType = fieldType.Elem()
+	}
+
+	// Get description from tag
+	if desc := field.Tag.Get("description"); desc != "" {
+		schema.Description = desc
+	}
+
+	switch fieldType.Kind() {
+	case reflect.String:
+		schema.Type = "string"
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
+		reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		schema.Type = "integer"
+	case reflect.Float32, reflect.Float64:
+		schema.Type = "number"
+	case reflect.Bool:
+		schema.Type = "boolean"
+	case reflect.Slice, reflect.Array:
+		schema.Type = "array"
+		elemType := fieldType.Elem()
+		if elemType.Kind() == reflect.Ptr {
+			elemType = elemType.Elem()
+		}
+		if elemType.Kind() == reflect.Struct {
+			// Complex type - would need recursive handling
+			schema.Items = &Schema{Type: "object"}
+		} else {
+			schema.Items = g.generatePropertySchema(reflect.StructField{Type: elemType})
+		}
+	case reflect.Struct:
+		// Check for time.Time
+		if fieldType.String() == "time.Time" {
+			schema.Type = "string"
+			schema.Format = "date-time"
+		} else {
+			schema.Type = "object"
+		}
+	default:
+		schema.Type = "string"
+	}
+
+	// Check for custom format from gorm/bun tags
+	if gormTag := field.Tag.Get("gorm"); gormTag != "" {
+		if strings.Contains(gormTag, "type:uuid") {
+			schema.Format = "uuid"
+		}
+	}
+
+	return schema
+}
+
+// parseModelName splits "schema.entity" or returns "public" and entity
+func parseModelName(name string) (schema, entity string) {
+	parts := strings.Split(name, ".")
+	if len(parts) == 2 {
+		return parts[0], parts[1]
+	}
+	return "public", name
+}
+
+// formatSchemaName creates a component schema name
+func formatSchemaName(schema, entity string) string {
+	if schema == "public" {
+		return toTitleCase(entity)
+	}
+	return toTitleCase(schema) + toTitleCase(entity)
+}
+
+// toTitleCase converts a string to title case (first letter uppercase)
+func toTitleCase(s string) string {
+	if s == "" {
+		return ""
+	}
+	if len(s) == 1 {
+		return strings.ToUpper(s)
+	}
+	return strings.ToUpper(s[:1]) + s[1:]
+}

pkg/openapi/generator_test.go

@@ -0,0 +1,714 @@
+package openapi
+
+import (
+	"encoding/json"
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/bitechdev/ResolveSpec/pkg/modelregistry"
+)
+
+// Test models
+type TestUser struct {
+	ID        int       `json:"id" gorm:"primaryKey" description:"User ID"`
+	Name      string    `json:"name" gorm:"not null" description:"User's full name"`
+	Email     string    `json:"email" gorm:"unique" description:"Email address"`
+	Age       int       `json:"age" description:"User age"`
+	IsActive  bool      `json:"is_active" description:"Active status"`
+	CreatedAt time.Time `json:"created_at" description:"Creation timestamp"`
+	UpdatedAt *time.Time `json:"updated_at,omitempty" description:"Last update timestamp"`
+	Roles     []string  `json:"roles,omitempty" description:"User roles"`
+}
+
+type TestProduct struct {
+	ID          int     `json:"id" gorm:"primaryKey"`
+	Name        string  `json:"name" gorm:"not null"`
+	Description string  `json:"description"`
+	Price       float64 `json:"price"`
+	InStock     bool    `json:"in_stock"`
+}
+
+type TestOrder struct {
+	ID         int    `json:"id" gorm:"primaryKey"`
+	UserID     int    `json:"user_id" gorm:"not null"`
+	ProductID  int    `json:"product_id" gorm:"not null"`
+	Quantity   int    `json:"quantity"`
+	TotalPrice float64 `json:"total_price"`
+}
+
+func TestNewGenerator(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+
+	tests := []struct {
+		name   string
+		config GeneratorConfig
+		want   string // expected title
+	}{
+		{
+			name: "with all fields",
+			config: GeneratorConfig{
+				Title:       "Test API",
+				Description: "Test Description",
+				Version:     "1.0.0",
+				BaseURL:     "http://localhost:8080",
+				Registry:    registry,
+			},
+			want: "Test API",
+		},
+		{
+			name: "with defaults",
+			config: GeneratorConfig{
+				Registry: registry,
+			},
+			want: "ResolveSpec API",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gen := NewGenerator(tt.config)
+			if gen == nil {
+				t.Fatal("NewGenerator returned nil")
+			}
+			if gen.config.Title != tt.want {
+				t.Errorf("Title = %v, want %v", gen.config.Title, tt.want)
+			}
+		})
+	}
+}
+
+func TestGenerateBasicSpec(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+	err := registry.RegisterModel("public.users", TestUser{})
+	if err != nil {
+		t.Fatalf("Failed to register model: %v", err)
+	}
+
+	config := GeneratorConfig{
+		Title:               "Test API",
+		Version:             "1.0.0",
+		Registry:            registry,
+		IncludeRestheadSpec: true,
+	}
+
+	gen := NewGenerator(config)
+	spec, err := gen.Generate()
+	if err != nil {
+		t.Fatalf("Generate failed: %v", err)
+	}
+
+	// Test basic spec structure
+	if spec.OpenAPI != "3.0.0" {
+		t.Errorf("OpenAPI version = %v, want 3.0.0", spec.OpenAPI)
+	}
+	if spec.Info.Title != "Test API" {
+		t.Errorf("Title = %v, want Test API", spec.Info.Title)
+	}
+	if spec.Info.Version != "1.0.0" {
+		t.Errorf("Version = %v, want 1.0.0", spec.Info.Version)
+	}
+
+	// Test that common schemas are added
+	if spec.Components.Schemas["Response"].Type != "object" {
+		t.Error("Response schema not found or invalid")
+	}
+	if spec.Components.Schemas["Metadata"].Type != "object" {
+		t.Error("Metadata schema not found or invalid")
+	}
+
+	// Test that model schema is added
+	if _, exists := spec.Components.Schemas["Users"]; !exists {
+		t.Error("Users schema not found")
+	}
+
+	// Test that security schemes are added
+	if len(spec.Components.SecuritySchemes) == 0 {
+		t.Error("Security schemes not added")
+	}
+}
+
+func TestGenerateModelSchema(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+	gen := NewGenerator(GeneratorConfig{Registry: registry})
+
+	schema := gen.generateModelSchema(TestUser{})
+
+	// Test basic properties
+	if schema.Type != "object" {
+		t.Errorf("Schema type = %v, want object", schema.Type)
+	}
+
+	// Test that properties are generated
+	expectedProps := []string{"id", "name", "email", "age", "is_active", "created_at", "updated_at", "roles"}
+	for _, prop := range expectedProps {
+		if _, exists := schema.Properties[prop]; !exists {
+			t.Errorf("Property %s not found in schema", prop)
+		}
+	}
+
+	// Test property types
+	if schema.Properties["id"].Type != "integer" {
+		t.Errorf("id type = %v, want integer", schema.Properties["id"].Type)
+	}
+	if schema.Properties["name"].Type != "string" {
+		t.Errorf("name type = %v, want string", schema.Properties["name"].Type)
+	}
+	if schema.Properties["is_active"].Type != "boolean" {
+		t.Errorf("is_active type = %v, want boolean", schema.Properties["is_active"].Type)
+	}
+
+	// Test array type
+	if schema.Properties["roles"].Type != "array" {
+		t.Errorf("roles type = %v, want array", schema.Properties["roles"].Type)
+	}
+	if schema.Properties["roles"].Items.Type != "string" {
+		t.Errorf("roles items type = %v, want string", schema.Properties["roles"].Items.Type)
+	}
+
+	// Test time.Time format
+	if schema.Properties["created_at"].Type != "string" {
+		t.Errorf("created_at type = %v, want string", schema.Properties["created_at"].Type)
+	}
+	if schema.Properties["created_at"].Format != "date-time" {
+		t.Errorf("created_at format = %v, want date-time", schema.Properties["created_at"].Format)
+	}
+
+	// Test required fields (non-pointer, no omitempty)
+	requiredFields := map[string]bool{}
+	for _, field := range schema.Required {
+		requiredFields[field] = true
+	}
+	if !requiredFields["id"] {
+		t.Error("id should be required")
+	}
+	if !requiredFields["name"] {
+		t.Error("name should be required")
+	}
+	if requiredFields["updated_at"] {
+		t.Error("updated_at should not be required (pointer + omitempty)")
+	}
+	if requiredFields["roles"] {
+		t.Error("roles should not be required (omitempty)")
+	}
+
+	// Test descriptions
+	if schema.Properties["id"].Description != "User ID" {
+		t.Errorf("id description = %v, want 'User ID'", schema.Properties["id"].Description)
+	}
+}
+
+func TestGenerateRestheadSpecPaths(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+	err := registry.RegisterModel("public.users", TestUser{})
+	if err != nil {
+		t.Fatalf("Failed to register model: %v", err)
+	}
+
+	config := GeneratorConfig{
+		Title:               "Test API",
+		Version:             "1.0.0",
+		Registry:            registry,
+		IncludeRestheadSpec: true,
+	}
+
+	gen := NewGenerator(config)
+	spec, err := gen.Generate()
+	if err != nil {
+		t.Fatalf("Generate failed: %v", err)
+	}
+
+	// Test that paths are generated
+	expectedPaths := []string{
+		"/public/users",
+		"/public/users/{id}",
+		"/public/users/metadata",
+	}
+
+	for _, path := range expectedPaths {
+		if _, exists := spec.Paths[path]; !exists {
+			t.Errorf("Path %s not found", path)
+		}
+	}
+
+	// Test collection endpoint methods
+	usersPath := spec.Paths["/public/users"]
+	if usersPath.Get == nil {
+		t.Error("GET method not found for /public/users")
+	}
+	if usersPath.Post == nil {
+		t.Error("POST method not found for /public/users")
+	}
+	if usersPath.Options == nil {
+		t.Error("OPTIONS method not found for /public/users")
+	}
+
+	// Test single record endpoint methods
+	userIDPath := spec.Paths["/public/users/{id}"]
+	if userIDPath.Get == nil {
+		t.Error("GET method not found for /public/users/{id}")
+	}
+	if userIDPath.Put == nil {
+		t.Error("PUT method not found for /public/users/{id}")
+	}
+	if userIDPath.Patch == nil {
+		t.Error("PATCH method not found for /public/users/{id}")
+	}
+	if userIDPath.Delete == nil {
+		t.Error("DELETE method not found for /public/users/{id}")
+	}
+
+	// Test metadata endpoint
+	metadataPath := spec.Paths["/public/users/metadata"]
+	if metadataPath.Get == nil {
+		t.Error("GET method not found for /public/users/metadata")
+	}
+
+	// Test operation details
+	getOp := usersPath.Get
+	if getOp.Summary == "" {
+		t.Error("GET operation summary is empty")
+	}
+	if getOp.OperationID == "" {
+		t.Error("GET operation ID is empty")
+	}
+	if len(getOp.Tags) == 0 {
+		t.Error("GET operation has no tags")
+	}
+	if len(getOp.Parameters) == 0 {
+		t.Error("GET operation has no parameters")
+	}
+
+	// Test RestheadSpec headers
+	hasFiltersHeader := false
+	for _, param := range getOp.Parameters {
+		if param.Name == "X-Filters" && param.In == "header" {
+			hasFiltersHeader = true
+			break
+		}
+	}
+	if !hasFiltersHeader {
+		t.Error("X-Filters header parameter not found")
+	}
+}
+
+func TestGenerateResolveSpecPaths(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+	err := registry.RegisterModel("public.products", TestProduct{})
+	if err != nil {
+		t.Fatalf("Failed to register model: %v", err)
+	}
+
+	config := GeneratorConfig{
+		Title:              "Test API",
+		Version:            "1.0.0",
+		Registry:           registry,
+		IncludeResolveSpec: true,
+	}
+
+	gen := NewGenerator(config)
+	spec, err := gen.Generate()
+	if err != nil {
+		t.Fatalf("Generate failed: %v", err)
+	}
+
+	// Test that paths are generated
+	expectedPaths := []string{
+		"/resolve/public/products",
+		"/resolve/public/products/{id}",
+	}
+
+	for _, path := range expectedPaths {
+		if _, exists := spec.Paths[path]; !exists {
+			t.Errorf("Path %s not found", path)
+		}
+	}
+
+	// Test collection endpoint methods
+	productsPath := spec.Paths["/resolve/public/products"]
+	if productsPath.Post == nil {
+		t.Error("POST method not found for /resolve/public/products")
+	}
+	if productsPath.Get == nil {
+		t.Error("GET method not found for /resolve/public/products")
+	}
+	if productsPath.Options == nil {
+		t.Error("OPTIONS method not found for /resolve/public/products")
+	}
+
+	// Test POST operation has request body
+	postOp := productsPath.Post
+	if postOp.RequestBody == nil {
+		t.Error("POST operation has no request body")
+	}
+	if _, exists := postOp.RequestBody.Content["application/json"]; !exists {
+		t.Error("POST operation request body has no application/json content")
+	}
+
+	// Test request body schema references ResolveSpecRequest
+	reqBodySchema := postOp.RequestBody.Content["application/json"].Schema
+	if reqBodySchema.Ref != "#/components/schemas/ResolveSpecRequest" {
+		t.Errorf("Request body schema ref = %v, want #/components/schemas/ResolveSpecRequest", reqBodySchema.Ref)
+	}
+}
+
+func TestGenerateFuncSpecPaths(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+
+	funcSpecEndpoints := map[string]FuncSpecEndpoint{
+		"/api/reports/sales": {
+			Path:        "/api/reports/sales",
+			Method:      "GET",
+			Summary:     "Get sales report",
+			Description: "Returns sales data",
+			Parameters:  []string{"start_date", "end_date"},
+		},
+		"/api/analytics/users": {
+			Path:        "/api/analytics/users",
+			Method:      "POST",
+			Summary:     "Get user analytics",
+			Description: "Returns user activity",
+			Parameters:  []string{"user_id"},
+		},
+	}
+
+	config := GeneratorConfig{
+		Title:             "Test API",
+		Version:           "1.0.0",
+		Registry:          registry,
+		IncludeFuncSpec:   true,
+		FuncSpecEndpoints: funcSpecEndpoints,
+	}
+
+	gen := NewGenerator(config)
+	spec, err := gen.Generate()
+	if err != nil {
+		t.Fatalf("Generate failed: %v", err)
+	}
+
+	// Test that FuncSpec paths are generated
+	salesPath := spec.Paths["/api/reports/sales"]
+	if salesPath.Get == nil {
+		t.Error("GET method not found for /api/reports/sales")
+	}
+	if salesPath.Get.Summary != "Get sales report" {
+		t.Errorf("GET summary = %v, want 'Get sales report'", salesPath.Get.Summary)
+	}
+	if len(salesPath.Get.Parameters) != 2 {
+		t.Errorf("GET has %d parameters, want 2", len(salesPath.Get.Parameters))
+	}
+
+	analyticsPath := spec.Paths["/api/analytics/users"]
+	if analyticsPath.Post == nil {
+		t.Error("POST method not found for /api/analytics/users")
+	}
+	if len(analyticsPath.Post.Parameters) != 1 {
+		t.Errorf("POST has %d parameters, want 1", len(analyticsPath.Post.Parameters))
+	}
+}
+
+func TestGenerateJSON(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+	err := registry.RegisterModel("public.users", TestUser{})
+	if err != nil {
+		t.Fatalf("Failed to register model: %v", err)
+	}
+
+	config := GeneratorConfig{
+		Title:               "Test API",
+		Version:             "1.0.0",
+		Registry:            registry,
+		IncludeRestheadSpec: true,
+	}
+
+	gen := NewGenerator(config)
+	jsonStr, err := gen.GenerateJSON()
+	if err != nil {
+		t.Fatalf("GenerateJSON failed: %v", err)
+	}
+
+	// Test that it's valid JSON
+	var spec OpenAPISpec
+	if err := json.Unmarshal([]byte(jsonStr), &spec); err != nil {
+		t.Fatalf("Generated JSON is invalid: %v", err)
+	}
+
+	// Test basic structure
+	if spec.OpenAPI != "3.0.0" {
+		t.Errorf("OpenAPI version = %v, want 3.0.0", spec.OpenAPI)
+	}
+	if spec.Info.Title != "Test API" {
+		t.Errorf("Title = %v, want Test API", spec.Info.Title)
+	}
+
+	// Test that JSON contains expected fields
+	if !strings.Contains(jsonStr, `"openapi"`) {
+		t.Error("JSON doesn't contain 'openapi' field")
+	}
+	if !strings.Contains(jsonStr, `"paths"`) {
+		t.Error("JSON doesn't contain 'paths' field")
+	}
+	if !strings.Contains(jsonStr, `"components"`) {
+		t.Error("JSON doesn't contain 'components' field")
+	}
+}
+
+func TestMultipleModels(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+	registry.RegisterModel("public.users", TestUser{})
+	registry.RegisterModel("public.products", TestProduct{})
+	registry.RegisterModel("public.orders", TestOrder{})
+
+	config := GeneratorConfig{
+		Title:               "Test API",
+		Version:             "1.0.0",
+		Registry:            registry,
+		IncludeRestheadSpec: true,
+	}
+
+	gen := NewGenerator(config)
+	spec, err := gen.Generate()
+	if err != nil {
+		t.Fatalf("Generate failed: %v", err)
+	}
+
+	// Test that all model schemas are generated
+	expectedSchemas := []string{"Users", "Products", "Orders"}
+	for _, schemaName := range expectedSchemas {
+		if _, exists := spec.Components.Schemas[schemaName]; !exists {
+			t.Errorf("Schema %s not found", schemaName)
+		}
+	}
+
+	// Test that all paths are generated
+	expectedPaths := []string{
+		"/public/users",
+		"/public/products",
+		"/public/orders",
+	}
+	for _, path := range expectedPaths {
+		if _, exists := spec.Paths[path]; !exists {
+			t.Errorf("Path %s not found", path)
+		}
+	}
+}
+
+func TestModelNameParsing(t *testing.T) {
+	tests := []struct {
+		name         string
+		fullName     string
+		wantSchema   string
+		wantEntity   string
+	}{
+		{
+			name:       "with schema",
+			fullName:   "public.users",
+			wantSchema: "public",
+			wantEntity: "users",
+		},
+		{
+			name:       "without schema",
+			fullName:   "users",
+			wantSchema: "public",
+			wantEntity: "users",
+		},
+		{
+			name:       "custom schema",
+			fullName:   "custom.products",
+			wantSchema: "custom",
+			wantEntity: "products",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			schema, entity := parseModelName(tt.fullName)
+			if schema != tt.wantSchema {
+				t.Errorf("schema = %v, want %v", schema, tt.wantSchema)
+			}
+			if entity != tt.wantEntity {
+				t.Errorf("entity = %v, want %v", entity, tt.wantEntity)
+			}
+		})
+	}
+}
+
+func TestSchemaNameFormatting(t *testing.T) {
+	tests := []struct {
+		name       string
+		schema     string
+		entity     string
+		wantName   string
+	}{
+		{
+			name:     "public schema",
+			schema:   "public",
+			entity:   "users",
+			wantName: "Users",
+		},
+		{
+			name:     "custom schema",
+			schema:   "custom",
+			entity:   "products",
+			wantName: "CustomProducts",
+		},
+		{
+			name:     "multi-word entity",
+			schema:   "public",
+			entity:   "user_profiles",
+			wantName: "User_profiles",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			name := formatSchemaName(tt.schema, tt.entity)
+			if name != tt.wantName {
+				t.Errorf("formatSchemaName() = %v, want %v", name, tt.wantName)
+			}
+		})
+	}
+}
+
+func TestToTitleCase(t *testing.T) {
+	tests := []struct {
+		input string
+		want  string
+	}{
+		{"users", "Users"},
+		{"products", "Products"},
+		{"userProfiles", "UserProfiles"},
+		{"a", "A"},
+		{"", ""},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.input, func(t *testing.T) {
+			got := toTitleCase(tt.input)
+			if got != tt.want {
+				t.Errorf("toTitleCase(%v) = %v, want %v", tt.input, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestGenerateWithBaseURL(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+	registry.RegisterModel("public.users", TestUser{})
+
+	config := GeneratorConfig{
+		Title:               "Test API",
+		Version:             "1.0.0",
+		BaseURL:             "https://api.example.com",
+		Registry:            registry,
+		IncludeRestheadSpec: true,
+	}
+
+	gen := NewGenerator(config)
+	spec, err := gen.Generate()
+	if err != nil {
+		t.Fatalf("Generate failed: %v", err)
+	}
+
+	// Test that server is added
+	if len(spec.Servers) == 0 {
+		t.Fatal("No servers added")
+	}
+	if spec.Servers[0].URL != "https://api.example.com" {
+		t.Errorf("Server URL = %v, want https://api.example.com", spec.Servers[0].URL)
+	}
+	if spec.Servers[0].Description != "API Server" {
+		t.Errorf("Server description = %v, want 'API Server'", spec.Servers[0].Description)
+	}
+}
+
+func TestGenerateCombinedFrameworks(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+	registry.RegisterModel("public.users", TestUser{})
+
+	config := GeneratorConfig{
+		Title:               "Test API",
+		Version:             "1.0.0",
+		Registry:            registry,
+		IncludeRestheadSpec: true,
+		IncludeResolveSpec:  true,
+	}
+
+	gen := NewGenerator(config)
+	spec, err := gen.Generate()
+	if err != nil {
+		t.Fatalf("Generate failed: %v", err)
+	}
+
+	// Test that both RestheadSpec and ResolveSpec paths are generated
+	restheadPath := "/public/users"
+	resolveSpecPath := "/resolve/public/users"
+
+	if _, exists := spec.Paths[restheadPath]; !exists {
+		t.Errorf("RestheadSpec path %s not found", restheadPath)
+	}
+	if _, exists := spec.Paths[resolveSpecPath]; !exists {
+		t.Errorf("ResolveSpec path %s not found", resolveSpecPath)
+	}
+}
+
+func TestNilRegistry(t *testing.T) {
+	config := GeneratorConfig{
+		Title:   "Test API",
+		Version: "1.0.0",
+	}
+
+	gen := NewGenerator(config)
+	_, err := gen.Generate()
+	if err == nil {
+		t.Error("Expected error for nil registry, got nil")
+	}
+	if !strings.Contains(err.Error(), "registry") {
+		t.Errorf("Error message should mention registry, got: %v", err)
+	}
+}
+
+func TestSecuritySchemes(t *testing.T) {
+	registry := modelregistry.NewModelRegistry()
+	config := GeneratorConfig{
+		Registry: registry,
+	}
+
+	gen := NewGenerator(config)
+	spec, err := gen.Generate()
+	if err != nil {
+		t.Fatalf("Generate failed: %v", err)
+	}
+
+	// Test that all security schemes are present
+	expectedSchemes := []string{"BearerAuth", "SessionToken", "CookieAuth", "HeaderAuth"}
+	for _, scheme := range expectedSchemes {
+		if _, exists := spec.Components.SecuritySchemes[scheme]; !exists {
+			t.Errorf("Security scheme %s not found", scheme)
+		}
+	}
+
+	// Test BearerAuth scheme details
+	bearerAuth := spec.Components.SecuritySchemes["BearerAuth"]
+	if bearerAuth.Type != "http" {
+		t.Errorf("BearerAuth type = %v, want http", bearerAuth.Type)
+	}
+	if bearerAuth.Scheme != "bearer" {
+		t.Errorf("BearerAuth scheme = %v, want bearer", bearerAuth.Scheme)
+	}
+	if bearerAuth.BearerFormat != "JWT" {
+		t.Errorf("BearerAuth format = %v, want JWT", bearerAuth.BearerFormat)
+	}
+
+	// Test HeaderAuth scheme details
+	headerAuth := spec.Components.SecuritySchemes["HeaderAuth"]
+	if headerAuth.Type != "apiKey" {
+		t.Errorf("HeaderAuth type = %v, want apiKey", headerAuth.Type)
+	}
+	if headerAuth.In != "header" {
+		t.Errorf("HeaderAuth in = %v, want header", headerAuth.In)
+	}
+	if headerAuth.Name != "X-User-ID" {
+		t.Errorf("HeaderAuth name = %v, want X-User-ID", headerAuth.Name)
+	}
+}

pkg/openapi/paths.go

@@ -0,0 +1,499 @@
+package openapi
+
+import (
+	"fmt"
+)
+
+// generateRestheadSpecPaths generates OpenAPI paths for RestheadSpec endpoints
+func (g *Generator) generateRestheadSpecPaths(spec *OpenAPISpec, schema, entity, schemaName string) {
+	basePath := fmt.Sprintf("/%s/%s", schema, entity)
+	idPath := fmt.Sprintf("/%s/%s/{id}", schema, entity)
+	metaPath := fmt.Sprintf("/%s/%s/metadata", schema, entity)
+
+	// Collection endpoint: GET (list), POST (create)
+	spec.Paths[basePath] = PathItem{
+		Get: &Operation{
+			Summary:     fmt.Sprintf("List %s records", entity),
+			Description: fmt.Sprintf("Retrieve a list of %s records with optional filtering, sorting, and pagination via headers", entity),
+			OperationID: fmt.Sprintf("listRestheadSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (RestheadSpec)", entity)},
+			Parameters:  g.getRestheadSpecHeaders(),
+			Responses: map[string]Response{
+				"200": {
+					Description: "Successful response",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{
+								Type: "object",
+								Properties: map[string]*Schema{
+									"success":  {Type: "boolean"},
+									"data":     {Type: "array", Items: &Schema{Ref: fmt.Sprintf("#/components/schemas/%s", schemaName)}},
+									"metadata": {Ref: "#/components/schemas/Metadata"},
+								},
+							},
+						},
+					},
+				},
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		},
+		Post: &Operation{
+			Summary:     fmt.Sprintf("Create %s record", entity),
+			Description: fmt.Sprintf("Create a new %s record", entity),
+			OperationID: fmt.Sprintf("createRestheadSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (RestheadSpec)", entity)},
+			RequestBody: &RequestBody{
+				Required:    true,
+				Description: fmt.Sprintf("%s object to create", entity),
+				Content: map[string]MediaType{
+					"application/json": {
+						Schema: &Schema{Ref: fmt.Sprintf("#/components/schemas/%s", schemaName)},
+					},
+				},
+			},
+			Responses: map[string]Response{
+				"201": {
+					Description: "Record created successfully",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{
+								Type: "object",
+								Properties: map[string]*Schema{
+									"success": {Type: "boolean"},
+									"data":    {Ref: fmt.Sprintf("#/components/schemas/%s", schemaName)},
+								},
+							},
+						},
+					},
+				},
+				"400": g.errorResponse("Bad request"),
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		},
+		Options: &Operation{
+			Summary:     "CORS preflight",
+			Description: "Handle CORS preflight requests",
+			OperationID: fmt.Sprintf("optionsRestheadSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (RestheadSpec)", entity)},
+			Responses: map[string]Response{
+				"204": {Description: "No content"},
+			},
+		},
+	}
+
+	// Single record endpoint: GET (read), PUT/PATCH (update), DELETE
+	spec.Paths[idPath] = PathItem{
+		Get: &Operation{
+			Summary:     fmt.Sprintf("Get %s record by ID", entity),
+			Description: fmt.Sprintf("Retrieve a single %s record by its ID", entity),
+			OperationID: fmt.Sprintf("getRestheadSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (RestheadSpec)", entity)},
+			Parameters: []Parameter{
+				{Name: "id", In: "path", Required: true, Description: "Record ID", Schema: &Schema{Type: "integer"}},
+			},
+			Responses: map[string]Response{
+				"200": {
+					Description: "Successful response",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{
+								Type: "object",
+								Properties: map[string]*Schema{
+									"success": {Type: "boolean"},
+									"data":    {Ref: fmt.Sprintf("#/components/schemas/%s", schemaName)},
+								},
+							},
+						},
+					},
+				},
+				"404": g.errorResponse("Record not found"),
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		},
+		Put: &Operation{
+			Summary:     fmt.Sprintf("Update %s record", entity),
+			Description: fmt.Sprintf("Update an existing %s record by ID", entity),
+			OperationID: fmt.Sprintf("updateRestheadSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (RestheadSpec)", entity)},
+			Parameters: []Parameter{
+				{Name: "id", In: "path", Required: true, Description: "Record ID", Schema: &Schema{Type: "integer"}},
+			},
+			RequestBody: &RequestBody{
+				Required:    true,
+				Description: fmt.Sprintf("Updated %s object", entity),
+				Content: map[string]MediaType{
+					"application/json": {
+						Schema: &Schema{Ref: fmt.Sprintf("#/components/schemas/%s", schemaName)},
+					},
+				},
+			},
+			Responses: map[string]Response{
+				"200": {
+					Description: "Record updated successfully",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{
+								Type: "object",
+								Properties: map[string]*Schema{
+									"success": {Type: "boolean"},
+									"data":    {Ref: fmt.Sprintf("#/components/schemas/%s", schemaName)},
+								},
+							},
+						},
+					},
+				},
+				"400": g.errorResponse("Bad request"),
+				"404": g.errorResponse("Record not found"),
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		},
+		Patch: &Operation{
+			Summary:     fmt.Sprintf("Partially update %s record", entity),
+			Description: fmt.Sprintf("Partially update an existing %s record by ID", entity),
+			OperationID: fmt.Sprintf("patchRestheadSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (RestheadSpec)", entity)},
+			Parameters: []Parameter{
+				{Name: "id", In: "path", Required: true, Description: "Record ID", Schema: &Schema{Type: "integer"}},
+			},
+			RequestBody: &RequestBody{
+				Required:    true,
+				Description: fmt.Sprintf("Partial %s object", entity),
+				Content: map[string]MediaType{
+					"application/json": {
+						Schema: &Schema{Ref: fmt.Sprintf("#/components/schemas/%s", schemaName)},
+					},
+				},
+			},
+			Responses: map[string]Response{
+				"200": {
+					Description: "Record updated successfully",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{
+								Type: "object",
+								Properties: map[string]*Schema{
+									"success": {Type: "boolean"},
+									"data":    {Ref: fmt.Sprintf("#/components/schemas/%s", schemaName)},
+								},
+							},
+						},
+					},
+				},
+				"400": g.errorResponse("Bad request"),
+				"404": g.errorResponse("Record not found"),
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		},
+		Delete: &Operation{
+			Summary:     fmt.Sprintf("Delete %s record", entity),
+			Description: fmt.Sprintf("Delete a %s record by ID", entity),
+			OperationID: fmt.Sprintf("deleteRestheadSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (RestheadSpec)", entity)},
+			Parameters: []Parameter{
+				{Name: "id", In: "path", Required: true, Description: "Record ID", Schema: &Schema{Type: "integer"}},
+			},
+			Responses: map[string]Response{
+				"200": {
+					Description: "Record deleted successfully",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{
+								Type: "object",
+								Properties: map[string]*Schema{
+									"success": {Type: "boolean"},
+								},
+							},
+						},
+					},
+				},
+				"404": g.errorResponse("Record not found"),
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		},
+	}
+
+	// Metadata endpoint
+	spec.Paths[metaPath] = PathItem{
+		Get: &Operation{
+			Summary:     fmt.Sprintf("Get %s metadata", entity),
+			Description: fmt.Sprintf("Retrieve metadata information for %s table", entity),
+			OperationID: fmt.Sprintf("metadataRestheadSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (RestheadSpec)", entity)},
+			Responses: map[string]Response{
+				"200": {
+					Description: "Metadata retrieved successfully",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{
+								Type: "object",
+								Properties: map[string]*Schema{
+									"success": {Type: "boolean"},
+									"data": {
+										Type: "object",
+										Properties: map[string]*Schema{
+											"schema":  {Type: "string"},
+											"table":   {Type: "string"},
+											"columns": {Type: "array", Items: &Schema{Type: "object"}},
+										},
+									},
+								},
+							},
+						},
+					},
+				},
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		},
+	}
+}
+
+// generateResolveSpecPaths generates OpenAPI paths for ResolveSpec endpoints
+func (g *Generator) generateResolveSpecPaths(spec *OpenAPISpec, schema, entity, schemaName string) {
+	basePath := fmt.Sprintf("/resolve/%s/%s", schema, entity)
+	idPath := fmt.Sprintf("/resolve/%s/%s/{id}", schema, entity)
+
+	// Collection endpoint: POST (operations)
+	spec.Paths[basePath] = PathItem{
+		Post: &Operation{
+			Summary:     fmt.Sprintf("Perform operation on %s", entity),
+			Description: fmt.Sprintf("Execute read, create, or meta operations on %s records", entity),
+			OperationID: fmt.Sprintf("operateResolveSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (ResolveSpec)", entity)},
+			RequestBody: &RequestBody{
+				Required:    true,
+				Description: "Operation request with operation type and options",
+				Content: map[string]MediaType{
+					"application/json": {
+						Schema: &Schema{Ref: "#/components/schemas/ResolveSpecRequest"},
+						Example: map[string]interface{}{
+							"operation": "read",
+							"options": map[string]interface{}{
+								"limit": 10,
+								"filters": []map[string]interface{}{
+									{"column": "status", "operator": "eq", "value": "active"},
+								},
+							},
+						},
+					},
+				},
+			},
+			Responses: map[string]Response{
+				"200": {
+					Description: "Operation completed successfully",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{
+								Type: "object",
+								Properties: map[string]*Schema{
+									"success":  {Type: "boolean"},
+									"data":     {Type: "array", Items: &Schema{Ref: fmt.Sprintf("#/components/schemas/%s", schemaName)}},
+									"metadata": {Ref: "#/components/schemas/Metadata"},
+								},
+							},
+						},
+					},
+				},
+				"400": g.errorResponse("Bad request"),
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		},
+		Get: &Operation{
+			Summary:     fmt.Sprintf("Get %s metadata", entity),
+			Description: fmt.Sprintf("Retrieve metadata for %s", entity),
+			OperationID: fmt.Sprintf("metadataResolveSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (ResolveSpec)", entity)},
+			Responses: map[string]Response{
+				"200": {
+					Description: "Metadata retrieved successfully",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{Ref: "#/components/schemas/Response"},
+						},
+					},
+				},
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		},
+		Options: &Operation{
+			Summary:     "CORS preflight",
+			Description: "Handle CORS preflight requests",
+			OperationID: fmt.Sprintf("optionsResolveSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (ResolveSpec)", entity)},
+			Responses: map[string]Response{
+				"204": {Description: "No content"},
+			},
+		},
+	}
+
+	// Single record endpoint: POST (update/delete)
+	spec.Paths[idPath] = PathItem{
+		Post: &Operation{
+			Summary:     fmt.Sprintf("Update or delete %s record", entity),
+			Description: fmt.Sprintf("Execute update or delete operation on a specific %s record", entity),
+			OperationID: fmt.Sprintf("modifyResolveSpec%s%s", formatSchemaName(schema, ""), formatSchemaName("", entity)),
+			Tags:        []string{fmt.Sprintf("%s (ResolveSpec)", entity)},
+			Parameters: []Parameter{
+				{Name: "id", In: "path", Required: true, Description: "Record ID", Schema: &Schema{Type: "integer"}},
+			},
+			RequestBody: &RequestBody{
+				Required:    true,
+				Description: "Operation request (update or delete)",
+				Content: map[string]MediaType{
+					"application/json": {
+						Schema: &Schema{Ref: "#/components/schemas/ResolveSpecRequest"},
+						Example: map[string]interface{}{
+							"operation": "update",
+							"data": map[string]interface{}{
+								"status": "inactive",
+							},
+						},
+					},
+				},
+			},
+			Responses: map[string]Response{
+				"200": {
+					Description: "Operation completed successfully",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{
+								Type: "object",
+								Properties: map[string]*Schema{
+									"success": {Type: "boolean"},
+									"data":    {Ref: fmt.Sprintf("#/components/schemas/%s", schemaName)},
+								},
+							},
+						},
+					},
+				},
+				"400": g.errorResponse("Bad request"),
+				"404": g.errorResponse("Record not found"),
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		},
+	}
+}
+
+// generateFuncSpecPaths generates OpenAPI paths for FuncSpec endpoints
+func (g *Generator) generateFuncSpecPaths(spec *OpenAPISpec) {
+	for path, endpoint := range g.config.FuncSpecEndpoints {
+		operation := &Operation{
+			Summary:     endpoint.Summary,
+			Description: endpoint.Description,
+			OperationID: fmt.Sprintf("funcSpec%s", sanitizeOperationID(path)),
+			Tags:        []string{"FuncSpec"},
+			Parameters:  g.extractFuncSpecParameters(endpoint.Parameters),
+			Responses: map[string]Response{
+				"200": {
+					Description: "Query executed successfully",
+					Content: map[string]MediaType{
+						"application/json": {
+							Schema: &Schema{Ref: "#/components/schemas/Response"},
+						},
+					},
+				},
+				"400": g.errorResponse("Bad request"),
+				"401": g.errorResponse("Unauthorized"),
+				"500": g.errorResponse("Internal server error"),
+			},
+			Security: g.securityRequirements(),
+		}
+
+		pathItem := spec.Paths[path]
+		switch endpoint.Method {
+		case "GET":
+			pathItem.Get = operation
+		case "POST":
+			pathItem.Post = operation
+		case "PUT":
+			pathItem.Put = operation
+		case "DELETE":
+			pathItem.Delete = operation
+		}
+		spec.Paths[path] = pathItem
+	}
+}
+
+// getRestheadSpecHeaders returns all RestheadSpec header parameters
+func (g *Generator) getRestheadSpecHeaders() []Parameter {
+	return []Parameter{
+		{Name: "X-Filters", In: "header", Description: "JSON array of filter conditions", Schema: &Schema{Type: "string"}},
+		{Name: "X-Columns", In: "header", Description: "Comma-separated list of columns to select", Schema: &Schema{Type: "string"}},
+		{Name: "X-Sort", In: "header", Description: "JSON array of sort specifications", Schema: &Schema{Type: "string"}},
+		{Name: "X-Limit", In: "header", Description: "Maximum number of records to return", Schema: &Schema{Type: "integer"}},
+		{Name: "X-Offset", In: "header", Description: "Number of records to skip", Schema: &Schema{Type: "integer"}},
+		{Name: "X-Preload", In: "header", Description: "Relations to eager load (comma-separated)", Schema: &Schema{Type: "string"}},
+		{Name: "X-Expand", In: "header", Description: "Relations to expand with LEFT JOIN (comma-separated)", Schema: &Schema{Type: "string"}},
+		{Name: "X-Distinct", In: "header", Description: "Enable DISTINCT query (true/false)", Schema: &Schema{Type: "boolean"}},
+		{Name: "X-Response-Format", In: "header", Description: "Response format", Schema: &Schema{Type: "string", Enum: []interface{}{"detail", "simple", "syncfusion"}}},
+		{Name: "X-Clean-JSON", In: "header", Description: "Remove null/empty fields from response (true/false)", Schema: &Schema{Type: "boolean"}},
+		{Name: "X-Custom-SQL-Where", In: "header", Description: "Custom SQL WHERE clause (AND)", Schema: &Schema{Type: "string"}},
+		{Name: "X-Custom-SQL-Or", In: "header", Description: "Custom SQL WHERE clause (OR)", Schema: &Schema{Type: "string"}},
+	}
+}
+
+// extractFuncSpecParameters creates OpenAPI parameters from parameter names
+func (g *Generator) extractFuncSpecParameters(paramNames []string) []Parameter {
+	params := []Parameter{}
+	for _, name := range paramNames {
+		params = append(params, Parameter{
+			Name:        name,
+			In:          "query",
+			Description: fmt.Sprintf("Parameter: %s", name),
+			Schema:      &Schema{Type: "string"},
+		})
+	}
+	return params
+}
+
+// errorResponse creates a standard error response
+func (g *Generator) errorResponse(description string) Response {
+	return Response{
+		Description: description,
+		Content: map[string]MediaType{
+			"application/json": {
+				Schema: &Schema{Ref: "#/components/schemas/APIError"},
+			},
+		},
+	}
+}
+
+// securityRequirements returns all security options (user can use any)
+func (g *Generator) securityRequirements() []map[string][]string {
+	return []map[string][]string{
+		{"BearerAuth": {}},
+		{"SessionToken": {}},
+		{"CookieAuth": {}},
+		{"HeaderAuth": {}},
+	}
+}
+
+// sanitizeOperationID removes invalid characters from operation IDs
+func sanitizeOperationID(path string) string {
+	result := ""
+	for _, char := range path {
+		if (char >= 'a' && char <= 'z') || (char >= 'A' && char <= 'Z') || (char >= '0' && char <= '9') {
+			result += string(char)
+		}
+	}
+	return result
+}

pkg/reflection/generic_model_test.go

@@ -0,0 +1,331 @@
+package reflection
+
+import (
+	"reflect"
+	"testing"
+)
+
+// Test models for GetModelColumnDetail
+type TestModelForColumnDetail struct {
+	ID          int    `gorm:"column:rid_test;primaryKey;type:bigserial;not null" json:"id"`
+	Name        string `gorm:"column:name;type:varchar(255);not null" json:"name"`
+	Email       string `gorm:"column:email;type:varchar(255);unique;nullable" json:"email"`
+	Description string `gorm:"column:description;type:text;null" json:"description"`
+	ForeignKey  int    `gorm:"foreignKey:parent_id" json:"foreign_key"`
+}
+
+type EmbeddedBase struct {
+	ID        int    `gorm:"column:rid_base;primaryKey;identity" json:"id"`
+	CreatedAt string `gorm:"column:created_at;type:timestamp" json:"created_at"`
+}
+
+type ModelWithEmbeddedForDetail struct {
+	EmbeddedBase
+	Title   string `gorm:"column:title;type:varchar(100);not null" json:"title"`
+	Content string `gorm:"column:content;type:text" json:"content"`
+}
+
+// Model with nil embedded pointer
+type ModelWithNilEmbedded struct {
+	ID           int            `gorm:"column:id;primaryKey" json:"id"`
+	*EmbeddedBase
+	Name         string         `gorm:"column:name" json:"name"`
+}
+
+func TestGetModelColumnDetail(t *testing.T) {
+	t.Run("simple struct", func(t *testing.T) {
+		model := TestModelForColumnDetail{
+			ID:          1,
+			Name:        "Test",
+			Email:       "test@example.com",
+			Description: "Test description",
+			ForeignKey:  100,
+		}
+
+		details := GetModelColumnDetail(reflect.ValueOf(model))
+
+		if len(details) != 5 {
+			t.Errorf("Expected 5 fields, got %d", len(details))
+		}
+
+		// Check ID field
+		found := false
+		for _, detail := range details {
+			if detail.Name == "ID" {
+				found = true
+				if detail.SQLName != "rid_test" {
+					t.Errorf("Expected SQLName 'rid_test', got '%s'", detail.SQLName)
+				}
+				// Note: primaryKey (without underscore) is not detected as primary_key
+				// The function looks for "identity" or "primary_key" (with underscore)
+				if detail.SQLDataType != "bigserial" {
+					t.Errorf("Expected SQLDataType 'bigserial', got '%s'", detail.SQLDataType)
+				}
+				if detail.Nullable {
+					t.Errorf("Expected Nullable false, got true")
+				}
+			}
+		}
+		if !found {
+			t.Errorf("ID field not found in details")
+		}
+	})
+
+	t.Run("struct with embedded fields", func(t *testing.T) {
+		model := ModelWithEmbeddedForDetail{
+			EmbeddedBase: EmbeddedBase{
+				ID:        1,
+				CreatedAt: "2024-01-01",
+			},
+			Title:   "Test Title",
+			Content: "Test Content",
+		}
+
+		details := GetModelColumnDetail(reflect.ValueOf(model))
+
+		// Should have 4 fields: ID, CreatedAt from embedded, Title, Content from main
+		if len(details) != 4 {
+			t.Errorf("Expected 4 fields, got %d", len(details))
+		}
+
+		// Check that embedded field is included
+		foundID := false
+		foundCreatedAt := false
+		for _, detail := range details {
+			if detail.Name == "ID" {
+				foundID = true
+				if detail.SQLKey != "primary_key" {
+					t.Errorf("Expected SQLKey 'primary_key' for embedded ID, got '%s'", detail.SQLKey)
+				}
+			}
+			if detail.Name == "CreatedAt" {
+				foundCreatedAt = true
+			}
+		}
+		if !foundID {
+			t.Errorf("Embedded ID field not found")
+		}
+		if !foundCreatedAt {
+			t.Errorf("Embedded CreatedAt field not found")
+		}
+	})
+
+	t.Run("nil embedded pointer is skipped", func(t *testing.T) {
+		model := ModelWithNilEmbedded{
+			ID:   1,
+			Name: "Test",
+			EmbeddedBase: nil, // nil embedded pointer
+		}
+
+		details := GetModelColumnDetail(reflect.ValueOf(model))
+
+		// Should have 2 fields: ID and Name (embedded is nil, so skipped)
+		if len(details) != 2 {
+			t.Errorf("Expected 2 fields (nil embedded skipped), got %d", len(details))
+		}
+	})
+
+	t.Run("pointer to struct", func(t *testing.T) {
+		model := &TestModelForColumnDetail{
+			ID:   1,
+			Name: "Test",
+		}
+
+		details := GetModelColumnDetail(reflect.ValueOf(model))
+
+		if len(details) != 5 {
+			t.Errorf("Expected 5 fields, got %d", len(details))
+		}
+	})
+
+	t.Run("invalid value", func(t *testing.T) {
+		var invalid reflect.Value
+		details := GetModelColumnDetail(invalid)
+
+		if len(details) != 0 {
+			t.Errorf("Expected 0 fields for invalid value, got %d", len(details))
+		}
+	})
+
+	t.Run("non-struct type", func(t *testing.T) {
+		details := GetModelColumnDetail(reflect.ValueOf(123))
+
+		if len(details) != 0 {
+			t.Errorf("Expected 0 fields for non-struct, got %d", len(details))
+		}
+	})
+
+	t.Run("nullable and not null detection", func(t *testing.T) {
+		model := TestModelForColumnDetail{}
+		details := GetModelColumnDetail(reflect.ValueOf(model))
+
+		for _, detail := range details {
+			switch detail.Name {
+			case "ID":
+				if detail.Nullable {
+					t.Errorf("ID should not be nullable (has 'not null')")
+				}
+			case "Name":
+				if detail.Nullable {
+					t.Errorf("Name should not be nullable (has 'not null')")
+				}
+			case "Email":
+				if !detail.Nullable {
+					t.Errorf("Email should be nullable (has 'nullable')")
+				}
+			case "Description":
+				if !detail.Nullable {
+					t.Errorf("Description should be nullable (has 'null')")
+				}
+			}
+		}
+	})
+
+	t.Run("unique and uniqueindex detection", func(t *testing.T) {
+		type UniqueTestModel struct {
+			ID       int    `gorm:"column:id;primary_key"`
+			Username string `gorm:"column:username;unique"`
+			Email    string `gorm:"column:email;uniqueindex"`
+		}
+
+		model := UniqueTestModel{}
+		details := GetModelColumnDetail(reflect.ValueOf(model))
+
+		for _, detail := range details {
+			switch detail.Name {
+			case "ID":
+				if detail.SQLKey != "primary_key" {
+					t.Errorf("ID should have SQLKey 'primary_key', got '%s'", detail.SQLKey)
+				}
+			case "Username":
+				if detail.SQLKey != "unique" {
+					t.Errorf("Username should have SQLKey 'unique', got '%s'", detail.SQLKey)
+				}
+			case "Email":
+				// The function checks for "unique" first, so uniqueindex is also detected as "unique"
+				// This is expected behavior based on the code logic
+				if detail.SQLKey != "unique" {
+					t.Errorf("Email should have SQLKey 'unique' (uniqueindex contains 'unique'), got '%s'", detail.SQLKey)
+				}
+			}
+		}
+	})
+
+	t.Run("foreign key detection", func(t *testing.T) {
+		// Note: The foreignkey extraction in generic_model.go has a bug where
+		// it requires ik > 0, so foreignkey at the start won't extract the value
+		type FKTestModel struct {
+			ParentID int `gorm:"column:parent_id;foreignkey:rid_parent;association_foreignkey:id_atevent"`
+		}
+
+		model := FKTestModel{}
+		details := GetModelColumnDetail(reflect.ValueOf(model))
+
+		if len(details) == 0 {
+			t.Fatal("Expected at least 1 field")
+		}
+
+		detail := details[0]
+		if detail.SQLKey != "foreign_key" {
+			t.Errorf("Expected SQLKey 'foreign_key', got '%s'", detail.SQLKey)
+		}
+		// Due to the bug in the code (requires ik > 0), the SQLName will be extracted
+		// when foreignkey is not at the beginning of the string
+		if detail.SQLName != "rid_parent" {
+			t.Errorf("Expected SQLName 'rid_parent', got '%s'", detail.SQLName)
+		}
+	})
+}
+
+func TestFnFindKeyVal(t *testing.T) {
+	tests := []struct {
+		name     string
+		src      string
+		key      string
+		expected string
+	}{
+		{
+			name:     "find column",
+			src:      "column:user_id;primaryKey;type:bigint",
+			key:      "column:",
+			expected: "user_id",
+		},
+		{
+			name:     "find type",
+			src:      "column:name;type:varchar(255);not null",
+			key:      "type:",
+			expected: "varchar(255)",
+		},
+		{
+			name:     "key not found",
+			src:      "primaryKey;autoIncrement",
+			key:      "column:",
+			expected: "",
+		},
+		{
+			name:     "key at end without semicolon",
+			src:      "primaryKey;column:id",
+			key:      "column:",
+			expected: "id",
+		},
+		{
+			name:     "case insensitive search",
+			src:      "Column:user_id;primaryKey",
+			key:      "column:",
+			expected: "user_id",
+		},
+		{
+			name:     "empty src",
+			src:      "",
+			key:      "column:",
+			expected: "",
+		},
+		{
+			name:     "multiple occurrences (returns first)",
+			src:      "column:first;column:second",
+			key:      "column:",
+			expected: "first",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			result := fnFindKeyVal(tt.src, tt.key)
+			if result != tt.expected {
+				t.Errorf("fnFindKeyVal(%q, %q) = %q, want %q", tt.src, tt.key, result, tt.expected)
+			}
+		})
+	}
+}
+
+func TestGetModelColumnDetail_FieldValue(t *testing.T) {
+	model := TestModelForColumnDetail{
+		ID:    123,
+		Name:  "TestName",
+		Email: "test@example.com",
+	}
+
+	details := GetModelColumnDetail(reflect.ValueOf(model))
+
+	for _, detail := range details {
+		if !detail.FieldValue.IsValid() {
+			t.Errorf("Field %s has invalid FieldValue", detail.Name)
+		}
+
+		// Check that FieldValue matches the actual value
+		switch detail.Name {
+		case "ID":
+			if detail.FieldValue.Int() != 123 {
+				t.Errorf("Expected ID FieldValue 123, got %v", detail.FieldValue.Int())
+			}
+		case "Name":
+			if detail.FieldValue.String() != "TestName" {
+				t.Errorf("Expected Name FieldValue 'TestName', got %v", detail.FieldValue.String())
+			}
+		case "Email":
+			if detail.FieldValue.String() != "test@example.com" {
+				t.Errorf("Expected Email FieldValue 'test@example.com', got %v", detail.FieldValue.String())
+			}
+		}
+	}
+}

pkg/reflection/model_utils.go

@@ -750,6 +750,118 @@ func ConvertToNumericType(value string, kind reflect.Kind) (interface{}, error)
 	return nil, fmt.Errorf("unsupported numeric type: %v", kind)
 }
 
+// RelationType represents the type of database relationship
+type RelationType string
+
+const (
+	RelationHasMany    RelationType = "has-many"     // 1:N - use separate query
+	RelationBelongsTo  RelationType = "belongs-to"   // N:1 - use JOIN
+	RelationHasOne     RelationType = "has-one"      // 1:1 - use JOIN
+	RelationManyToMany RelationType = "many-to-many" // M:N - use separate query
+	RelationUnknown    RelationType = "unknown"
+)
+
+// ShouldUseJoin returns true if the relation type should use a JOIN instead of separate query
+func (rt RelationType) ShouldUseJoin() bool {
+	return rt == RelationBelongsTo || rt == RelationHasOne
+}
+
+// GetRelationType inspects the model's struct tags to determine the relationship type
+// It checks both Bun and GORM tags to identify the relationship cardinality
+func GetRelationType(model interface{}, fieldName string) RelationType {
+	if model == nil || fieldName == "" {
+		return RelationUnknown
+	}
+
+	modelType := reflect.TypeOf(model)
+	if modelType == nil {
+		return RelationUnknown
+	}
+
+	if modelType.Kind() == reflect.Ptr {
+		modelType = modelType.Elem()
+	}
+
+	if modelType == nil || modelType.Kind() != reflect.Struct {
+		return RelationUnknown
+	}
+
+	// Find the field
+	for i := 0; i < modelType.NumField(); i++ {
+		field := modelType.Field(i)
+
+		// Check if field name matches (case-insensitive)
+		if !strings.EqualFold(field.Name, fieldName) {
+			continue
+		}
+
+		// Check Bun tags first
+		bunTag := field.Tag.Get("bun")
+		if bunTag != "" && strings.Contains(bunTag, "rel:") {
+			// Parse bun relation tag: rel:has-many, rel:belongs-to, rel:has-one, rel:many-to-many
+			parts := strings.Split(bunTag, ",")
+			for _, part := range parts {
+				part = strings.TrimSpace(part)
+				if strings.HasPrefix(part, "rel:") {
+					relType := strings.TrimPrefix(part, "rel:")
+					switch relType {
+					case "has-many":
+						return RelationHasMany
+					case "belongs-to":
+						return RelationBelongsTo
+					case "has-one":
+						return RelationHasOne
+					case "many-to-many", "m2m":
+						return RelationManyToMany
+					}
+				}
+			}
+		}
+
+		// Check GORM tags
+		gormTag := field.Tag.Get("gorm")
+		if gormTag != "" {
+			// GORM uses different patterns:
+			// - foreignKey: usually indicates belongs-to or has-one
+			// - many2many: indicates many-to-many
+			// - Field type (slice vs pointer) helps determine cardinality
+
+			if strings.Contains(gormTag, "many2many:") {
+				return RelationManyToMany
+			}
+
+			// Check field type for cardinality hints
+			fieldType := field.Type
+			if fieldType.Kind() == reflect.Slice {
+				// Slice indicates has-many or many-to-many
+				return RelationHasMany
+			}
+			if fieldType.Kind() == reflect.Ptr {
+				// Pointer to single struct usually indicates belongs-to or has-one
+				// Check if it has foreignKey (belongs-to) or references (has-one)
+				if strings.Contains(gormTag, "foreignKey:") {
+					return RelationBelongsTo
+				}
+				return RelationHasOne
+			}
+		}
+
+		// Fall back to field type inference
+		fieldType := field.Type
+		if fieldType.Kind() == reflect.Slice {
+			// Slice of structs → has-many
+			return RelationHasMany
+		}
+		if fieldType.Kind() == reflect.Ptr || fieldType.Kind() == reflect.Struct {
+			// Single struct → belongs-to (default assumption for safety)
+			// Using belongs-to as default ensures we use JOIN, which is safer
+			return RelationBelongsTo
+		}
+	}
+
+	return RelationUnknown
+}
+
 // GetRelationModel gets the model type for a relation field
 // It searches for the field by name in the following order (case-insensitive):
 // 1. Actual field name

pkg/resolvespec/handler.go

@@ -22,11 +22,12 @@ type FallbackHandler func(w common.ResponseWriter, r common.Request, params map[
 
 // Handler handles API requests using database and model abstractions
 type Handler struct {
-	db              common.Database
+	db               common.Database
-	registry        common.ModelRegistry
+	registry         common.ModelRegistry
-	nestedProcessor *common.NestedCUDProcessor
+	nestedProcessor  *common.NestedCUDProcessor
-	hooks           *HookRegistry
+	hooks            *HookRegistry
-	fallbackHandler FallbackHandler
+	fallbackHandler  FallbackHandler
+	openAPIGenerator func() (string, error)
 }
 
 // NewHandler creates a new API handler with database and registry abstractions
@@ -75,6 +76,12 @@ func (h *Handler) Handle(w common.ResponseWriter, r common.Request, params map[s
 		}
 	}()
 
+	// Check for ?openapi query parameter
+	if r.UnderlyingRequest().URL.Query().Get("openapi") != "" {
+		h.HandleOpenAPI(w, r)
+		return
+	}
+
 	ctx := r.UnderlyingRequest().Context()
 
 	body, err := r.Body()
@@ -156,6 +163,12 @@ func (h *Handler) HandleGet(w common.ResponseWriter, r common.Request, params ma
 		}
 	}()
 
+	// Check for ?openapi query parameter
+	if r.UnderlyingRequest().URL.Query().Get("openapi") != "" {
+		h.HandleOpenAPI(w, r)
+		return
+	}
+
 	schema := params["schema"]
 	entity := params["entity"]
 
@@ -303,7 +316,7 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 		// Apply cursor filter to query
 		if cursorFilter != "" {
 			logger.Debug("Applying cursor filter: %s", cursorFilter)
-			sanitizedCursor := common.SanitizeWhereClause(cursorFilter, reflection.ExtractTableNameOnly(tableName))
+			sanitizedCursor := common.SanitizeWhereClause(cursorFilter, reflection.ExtractTableNameOnly(tableName), &options)
 			if sanitizedCursor != "" {
 				query = query.Where(sanitizedCursor)
 			}
@@ -1338,7 +1351,9 @@ func (h *Handler) applyPreloads(model interface{}, query common.SelectQuery, pre
 			}
 
 			if len(preload.Where) > 0 {
-				sanitizedWhere := common.SanitizeWhereClause(preload.Where, reflection.ExtractTableNameOnly(preload.Relation))
+				// Build RequestOptions with all preloads to allow references to sibling relations
+				preloadOpts := &common.RequestOptions{Preload: preloads}
+				sanitizedWhere := common.SanitizeWhereClause(preload.Where, reflection.ExtractTableNameOnly(preload.Relation), preloadOpts)
 				if len(sanitizedWhere) > 0 {
 					sq = sq.Where(sanitizedWhere)
 				}
@@ -1433,3 +1448,31 @@ func toSnakeCase(s string) string {
 	}
 	return strings.ToLower(result.String())
 }
+
+// HandleOpenAPI generates and returns the OpenAPI specification
+func (h *Handler) HandleOpenAPI(w common.ResponseWriter, r common.Request) {
+	if h.openAPIGenerator == nil {
+		logger.Error("OpenAPI generator not configured")
+		h.sendError(w, http.StatusInternalServerError, "openapi_not_configured", "OpenAPI generation not configured", nil)
+		return
+	}
+
+	spec, err := h.openAPIGenerator()
+	if err != nil {
+		logger.Error("Failed to generate OpenAPI spec: %v", err)
+		h.sendError(w, http.StatusInternalServerError, "openapi_generation_error", "Failed to generate OpenAPI specification", err)
+		return
+	}
+
+	w.SetHeader("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	_, err = w.Write([]byte(spec))
+	if err != nil {
+		logger.Error("Error sending OpenAPI spec response: %v", err)
+	}
+}
+
+// SetOpenAPIGenerator sets the OpenAPI generator function
+func (h *Handler) SetOpenAPIGenerator(generator func() (string, error)) {
+	h.openAPIGenerator = generator
+}

pkg/resolvespec/resolvespec.go

@@ -46,6 +46,16 @@ type MiddlewareFunc func(http.Handler) http.Handler
 // authMiddleware is optional - if provided, routes will be protected with the middleware
 // Example: SetupMuxRoutes(router, handler, func(h http.Handler) http.Handler { return security.NewAuthHandler(securityList, h) })
 func SetupMuxRoutes(muxRouter *mux.Router, handler *Handler, authMiddleware MiddlewareFunc) {
+	// Add global /openapi route
+	openAPIHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		corsConfig := common.DefaultCORSConfig()
+		respAdapter := router.NewHTTPResponseWriter(w)
+		common.SetCORSHeaders(respAdapter, corsConfig)
+		reqAdapter := router.NewHTTPRequest(r)
+		handler.HandleOpenAPI(respAdapter, reqAdapter)
+	})
+	muxRouter.Handle("/openapi", openAPIHandler).Methods("GET", "OPTIONS")
+
 	// Get all registered models from the registry
 	allModels := handler.registry.GetAllModels()
 
@@ -201,12 +211,27 @@ func ExampleWithBun(bunDB *bun.DB) {
 func SetupBunRouterRoutes(bunRouter *router.StandardBunRouterAdapter, handler *Handler) {
 	r := bunRouter.GetBunRouter()
 
-	// Get all registered models from the registry
-	allModels := handler.registry.GetAllModels()
-
 	// CORS config
 	corsConfig := common.DefaultCORSConfig()
 
+	// Add global /openapi route
+	r.Handle("GET", "/openapi", func(w http.ResponseWriter, req bunrouter.Request) error {
+		respAdapter := router.NewHTTPResponseWriter(w)
+		common.SetCORSHeaders(respAdapter, corsConfig)
+		reqAdapter := router.NewHTTPRequest(req.Request)
+		handler.HandleOpenAPI(respAdapter, reqAdapter)
+		return nil
+	})
+
+	r.Handle("OPTIONS", "/openapi", func(w http.ResponseWriter, req bunrouter.Request) error {
+		respAdapter := router.NewHTTPResponseWriter(w)
+		common.SetCORSHeaders(respAdapter, corsConfig)
+		return nil
+	})
+
+	// Get all registered models from the registry
+	allModels := handler.registry.GetAllModels()
+
 	// Loop through each registered model and create explicit routes
 	for fullName := range allModels {
 		// Parse the full name (e.g., "public.users" or just "users")

pkg/restheadspec/handler.go

@@ -24,11 +24,12 @@ type FallbackHandler func(w common.ResponseWriter, r common.Request, params map[
 // Handler handles API requests using database and model abstractions
 // This handler reads filters, columns, and options from HTTP headers
 type Handler struct {
-	db              common.Database
+	db               common.Database
-	registry        common.ModelRegistry
+	registry         common.ModelRegistry
-	hooks           *HookRegistry
+	hooks            *HookRegistry
-	nestedProcessor *common.NestedCUDProcessor
+	nestedProcessor  *common.NestedCUDProcessor
-	fallbackHandler FallbackHandler
+	fallbackHandler  FallbackHandler
+	openAPIGenerator func() (string, error)
 }
 
 // NewHandler creates a new API handler with database and registry abstractions
@@ -78,6 +79,12 @@ func (h *Handler) Handle(w common.ResponseWriter, r common.Request, params map[s
 		}
 	}()
 
+	// Check for ?openapi query parameter
+	if r.UnderlyingRequest().URL.Query().Get("openapi") != "" {
+		h.HandleOpenAPI(w, r)
+		return
+	}
+
 	ctx := r.UnderlyingRequest().Context()
 
 	schema := params["schema"]
@@ -208,6 +215,12 @@ func (h *Handler) HandleGet(w common.ResponseWriter, r common.Request, params ma
 		}
 	}()
 
+	// Check for ?openapi query parameter
+	if r.UnderlyingRequest().URL.Query().Get("openapi") != "" {
+		h.HandleOpenAPI(w, r)
+		return
+	}
+
 	schema := params["schema"]
 	entity := params["entity"]
 
@@ -437,7 +450,7 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 		}
 
 		// Apply the preload with recursive support
-		query = h.applyPreloadWithRecursion(query, preload, model, 0)
+		query = h.applyPreloadWithRecursion(query, preload, options.Preload, model, 0)
 	}
 
 	// Apply DISTINCT if requested
@@ -467,8 +480,8 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 	// Apply custom SQL WHERE clause (AND condition)
 	if options.CustomSQLWhere != "" {
 		logger.Debug("Applying custom SQL WHERE: %s", options.CustomSQLWhere)
-		// Sanitize without auto-prefixing since custom SQL may reference multiple tables
+		// Sanitize and allow preload table prefixes since custom SQL may reference multiple tables
-		sanitizedWhere := common.SanitizeWhereClause(options.CustomSQLWhere, reflection.ExtractTableNameOnly(tableName))
+		sanitizedWhere := common.SanitizeWhereClause(options.CustomSQLWhere, reflection.ExtractTableNameOnly(tableName), &options.RequestOptions)
 		if sanitizedWhere != "" {
 			query = query.Where(sanitizedWhere)
 		}
@@ -477,8 +490,8 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 	// Apply custom SQL WHERE clause (OR condition)
 	if options.CustomSQLOr != "" {
 		logger.Debug("Applying custom SQL OR: %s", options.CustomSQLOr)
-		// Sanitize without auto-prefixing since custom SQL may reference multiple tables
+		// Sanitize and allow preload table prefixes since custom SQL may reference multiple tables
-		sanitizedOr := common.SanitizeWhereClause(options.CustomSQLOr, reflection.ExtractTableNameOnly(tableName))
+		sanitizedOr := common.SanitizeWhereClause(options.CustomSQLOr, reflection.ExtractTableNameOnly(tableName), &options.RequestOptions)
 		if sanitizedOr != "" {
 			query = query.WhereOr(sanitizedOr)
 		}
@@ -612,7 +625,7 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 		// Apply cursor filter to query
 		if cursorFilter != "" {
 			logger.Debug("Applying cursor filter: %s", cursorFilter)
-			sanitizedCursor := common.SanitizeWhereClause(cursorFilter, reflection.ExtractTableNameOnly(tableName))
+			sanitizedCursor := common.SanitizeWhereClause(cursorFilter, reflection.ExtractTableNameOnly(tableName), &options.RequestOptions)
 			if sanitizedCursor != "" {
 				query = query.Where(sanitizedCursor)
 			}
@@ -690,7 +703,7 @@ func (h *Handler) handleRead(ctx context.Context, w common.ResponseWriter, id st
 }
 
 // applyPreloadWithRecursion applies a preload with support for ComputedQL and recursive preloading
-func (h *Handler) applyPreloadWithRecursion(query common.SelectQuery, preload common.PreloadOption, model interface{}, depth int) common.SelectQuery {
+func (h *Handler) applyPreloadWithRecursion(query common.SelectQuery, preload common.PreloadOption, allPreloads []common.PreloadOption, model interface{}, depth int) common.SelectQuery {
 	// Log relationship keys if they're specified (from XFiles)
 	if preload.RelatedKey != "" || preload.ForeignKey != "" || preload.PrimaryKey != "" {
 		logger.Debug("Preload %s has relationship keys - PK: %s, RelatedKey: %s, ForeignKey: %s",
@@ -786,7 +799,9 @@ func (h *Handler) applyPreloadWithRecursion(query common.SelectQuery, preload co
 
 		// Apply WHERE clause
 		if len(preload.Where) > 0 {
-			sanitizedWhere := common.SanitizeWhereClause(preload.Where, reflection.ExtractTableNameOnly(preload.Relation))
+			// Build RequestOptions with all preloads to allow references to sibling relations
+			preloadOpts := &common.RequestOptions{Preload: allPreloads}
+			sanitizedWhere := common.SanitizeWhereClause(preload.Where, reflection.ExtractTableNameOnly(preload.Relation), preloadOpts)
 			if len(sanitizedWhere) > 0 {
 				sq = sq.Where(sanitizedWhere)
 			}
@@ -819,7 +834,7 @@ func (h *Handler) applyPreloadWithRecursion(query common.SelectQuery, preload co
 		recursivePreload.Relation = preload.Relation + "." + lastRelationName
 
 		// Recursively apply preload until we reach depth 5
-		query = h.applyPreloadWithRecursion(query, recursivePreload, model, depth+1)
+		query = h.applyPreloadWithRecursion(query, recursivePreload, allPreloads, model, depth+1)
 	}
 
 	return query
@@ -2379,3 +2394,35 @@ func (h *Handler) extractTagValue(tag, key string) string {
 	}
 	return ""
 }
+
+// HandleOpenAPI generates and returns the OpenAPI specification
+func (h *Handler) HandleOpenAPI(w common.ResponseWriter, r common.Request) {
+	// Import needed here to avoid circular dependency
+	// The import is done inline
+	// We'll use a factory function approach instead
+	if h.openAPIGenerator == nil {
+		logger.Error("OpenAPI generator not configured")
+		h.sendError(w, http.StatusInternalServerError, "openapi_not_configured", "OpenAPI generation not configured", nil)
+		return
+	}
+
+	spec, err := h.openAPIGenerator()
+	if err != nil {
+		logger.Error("Failed to generate OpenAPI spec: %v", err)
+		h.sendError(w, http.StatusInternalServerError, "openapi_generation_error", "Failed to generate OpenAPI specification", err)
+		return
+	}
+
+	w.SetHeader("Content-Type", "application/json")
+	w.WriteHeader(http.StatusOK)
+	_, err = w.Write([]byte(spec))
+	if err != nil {
+		logger.Error("Error sending OpenAPI spec response: %v", err)
+	}
+}
+
+// SetOpenAPIGenerator sets the OpenAPI generator function
+// This allows avoiding circular dependencies
+func (h *Handler) SetOpenAPIGenerator(generator func() (string, error)) {
+	h.openAPIGenerator = generator
+}

pkg/restheadspec/restheadspec.go

@@ -99,6 +99,16 @@ type MiddlewareFunc func(http.Handler) http.Handler
 // authMiddleware is optional - if provided, routes will be protected with the middleware
 // Example: SetupMuxRoutes(router, handler, func(h http.Handler) http.Handler { return security.NewAuthHandler(securityList, h) })
 func SetupMuxRoutes(muxRouter *mux.Router, handler *Handler, authMiddleware MiddlewareFunc) {
+	// Add global /openapi route
+	openAPIHandler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		corsConfig := common.DefaultCORSConfig()
+		respAdapter := router.NewHTTPResponseWriter(w)
+		common.SetCORSHeaders(respAdapter, corsConfig)
+		reqAdapter := router.NewHTTPRequest(r)
+		handler.HandleOpenAPI(respAdapter, reqAdapter)
+	})
+	muxRouter.Handle("/openapi", openAPIHandler).Methods("GET", "OPTIONS")
+
 	// Get all registered models from the registry
 	allModels := handler.registry.GetAllModels()
 
@@ -264,12 +274,27 @@ func ExampleWithBun(bunDB *bun.DB) {
 func SetupBunRouterRoutes(bunRouter *router.StandardBunRouterAdapter, handler *Handler) {
 	r := bunRouter.GetBunRouter()
 
-	// Get all registered models from the registry
-	allModels := handler.registry.GetAllModels()
-
 	// CORS config
 	corsConfig := common.DefaultCORSConfig()
 
+	// Add global /openapi route
+	r.Handle("GET", "/openapi", func(w http.ResponseWriter, req bunrouter.Request) error {
+		respAdapter := router.NewHTTPResponseWriter(w)
+		common.SetCORSHeaders(respAdapter, corsConfig)
+		reqAdapter := router.NewBunRouterRequest(req)
+		handler.HandleOpenAPI(respAdapter, reqAdapter)
+		return nil
+	})
+
+	r.Handle("OPTIONS", "/openapi", func(w http.ResponseWriter, req bunrouter.Request) error {
+		respAdapter := router.NewHTTPResponseWriter(w)
+		common.SetCORSHeaders(respAdapter, corsConfig)
+		return nil
+	})
+
+	// Get all registered models from the registry
+	allModels := handler.registry.GetAllModels()
+
 	// Loop through each registered model and create explicit routes
 	for fullName := range allModels {
 		// Parse the full name (e.g., "public.users" or just "users")