Merge pull request #18 from bitechdev/feature-auth-mcp

feat(security): implement OAuth2 authorization server with database s…

pkg/common/adapters/database/bun.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"reflect"
 	"strings"
+	"sync"
 	"time"
 
 	"github.com/uptrace/bun"
@@ -95,6 +96,8 @@ func debugScanIntoStruct(rows interface{}, dest interface{}) error {
 // This demonstrates how the abstraction works with different ORMs
 type BunAdapter struct {
 	db         *bun.DB
+	dbMu       sync.RWMutex
+	dbFactory  func() (*bun.DB, error)
 	driverName string
 }
 
@@ -106,10 +109,36 @@ func NewBunAdapter(db *bun.DB) *BunAdapter {
 	return adapter
 }
 
+// WithDBFactory configures a factory used to reopen the database connection if it is closed.
+func (b *BunAdapter) WithDBFactory(factory func() (*bun.DB, error)) *BunAdapter {
+	b.dbFactory = factory
+	return b
+}
+
+func (b *BunAdapter) getDB() *bun.DB {
+	b.dbMu.RLock()
+	defer b.dbMu.RUnlock()
+	return b.db
+}
+
+func (b *BunAdapter) reconnectDB() error {
+	if b.dbFactory == nil {
+		return fmt.Errorf("no db factory configured for reconnect")
+	}
+	newDB, err := b.dbFactory()
+	if err != nil {
+		return err
+	}
+	b.dbMu.Lock()
+	b.db = newDB
+	b.dbMu.Unlock()
+	return nil
+}
+
 // 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{})
+	b.getDB().AddQueryHook(&QueryDebugHook{})
 	logger.Info("Bun query debug mode enabled - all SQL queries will be logged")
 }
 
@@ -130,22 +159,22 @@ func (b *BunAdapter) DisableQueryDebug() {
 
 func (b *BunAdapter) NewSelect() common.SelectQuery {
 	return &BunSelectQuery{
-		query:      b.db.NewSelect(),
+		query:      b.getDB().NewSelect(),
 		db:         b.db,
 		driverName: b.driverName,
 	}
 }
 
 func (b *BunAdapter) NewInsert() common.InsertQuery {
-	return &BunInsertQuery{query: b.db.NewInsert()}
+	return &BunInsertQuery{query: b.getDB().NewInsert()}
 }
 
 func (b *BunAdapter) NewUpdate() common.UpdateQuery {
-	return &BunUpdateQuery{query: b.db.NewUpdate()}
+	return &BunUpdateQuery{query: b.getDB().NewUpdate()}
 }
 
 func (b *BunAdapter) NewDelete() common.DeleteQuery {
-	return &BunDeleteQuery{query: b.db.NewDelete()}
+	return &BunDeleteQuery{query: b.getDB().NewDelete()}
 }
 
 func (b *BunAdapter) Exec(ctx context.Context, query string, args ...interface{}) (res common.Result, err error) {
@@ -154,7 +183,14 @@ func (b *BunAdapter) Exec(ctx context.Context, query string, args ...interface{}
 			err = logger.HandlePanic("BunAdapter.Exec", r)
 		}
 	}()
-	result, err := b.db.ExecContext(ctx, query, args...)
+	var result sql.Result
+	run := func() error { var e error; result, e = b.getDB().ExecContext(ctx, query, args...); return e }
+	err = run()
+	if isDBClosed(err) {
+		if reconnErr := b.reconnectDB(); reconnErr == nil {
+			err = run()
+		}
+	}
 	return &BunResult{result: result}, err
 }
 
@@ -164,11 +200,17 @@ func (b *BunAdapter) Query(ctx context.Context, dest interface{}, query string,
 			err = logger.HandlePanic("BunAdapter.Query", r)
 		}
 	}()
-	return b.db.NewRaw(query, args...).Scan(ctx, dest)
+	err = b.getDB().NewRaw(query, args...).Scan(ctx, dest)
+	if isDBClosed(err) {
+		if reconnErr := b.reconnectDB(); reconnErr == nil {
+			err = b.getDB().NewRaw(query, args...).Scan(ctx, dest)
+		}
+	}
+	return err
 }
 
 func (b *BunAdapter) BeginTx(ctx context.Context) (common.Database, error) {
-	tx, err := b.db.BeginTx(ctx, &sql.TxOptions{})
+	tx, err := b.getDB().BeginTx(ctx, &sql.TxOptions{})
 	if err != nil {
 		return nil, err
 	}
@@ -194,7 +236,7 @@ func (b *BunAdapter) RunInTransaction(ctx context.Context, fn func(common.Databa
 			err = logger.HandlePanic("BunAdapter.RunInTransaction", r)
 		}
 	}()
-	return b.db.RunInTx(ctx, &sql.TxOptions{}, func(ctx context.Context, tx bun.Tx) error {
+	return b.getDB().RunInTx(ctx, &sql.TxOptions{}, func(ctx context.Context, tx bun.Tx) error {
 		// Create adapter with transaction
 		adapter := &BunTxAdapter{tx: tx, driverName: b.driverName}
 		return fn(adapter)
@@ -202,7 +244,7 @@ func (b *BunAdapter) RunInTransaction(ctx context.Context, fn func(common.Databa
 }
 
 func (b *BunAdapter) GetUnderlyingDB() interface{} {
-	return b.db
+	return b.getDB()
 }
 
 func (b *BunAdapter) DriverName() string {

pkg/common/adapters/database/pgsql.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"reflect"
 	"strings"
+	"sync"
 
 	"github.com/bitechdev/ResolveSpec/pkg/common"
 	"github.com/bitechdev/ResolveSpec/pkg/logger"
@@ -17,6 +18,8 @@ import (
 // This provides a lightweight PostgreSQL adapter without ORM overhead
 type PgSQLAdapter struct {
 	db         *sql.DB
+	dbMu       sync.RWMutex
+	dbFactory  func() (*sql.DB, error)
 	driverName string
 }
 
@@ -31,6 +34,36 @@ func NewPgSQLAdapter(db *sql.DB, driverName ...string) *PgSQLAdapter {
 	return &PgSQLAdapter{db: db, driverName: name}
 }
 
+// WithDBFactory configures a factory used to reopen the database connection if it is closed.
+func (p *PgSQLAdapter) WithDBFactory(factory func() (*sql.DB, error)) *PgSQLAdapter {
+	p.dbFactory = factory
+	return p
+}
+
+func (p *PgSQLAdapter) getDB() *sql.DB {
+	p.dbMu.RLock()
+	defer p.dbMu.RUnlock()
+	return p.db
+}
+
+func (p *PgSQLAdapter) reconnectDB() error {
+	if p.dbFactory == nil {
+		return fmt.Errorf("no db factory configured for reconnect")
+	}
+	newDB, err := p.dbFactory()
+	if err != nil {
+		return err
+	}
+	p.dbMu.Lock()
+	p.db = newDB
+	p.dbMu.Unlock()
+	return nil
+}
+
+func isDBClosed(err error) bool {
+	return err != nil && strings.Contains(err.Error(), "sql: database is closed")
+}
+
 // EnableQueryDebug enables query debugging for development
 func (p *PgSQLAdapter) EnableQueryDebug() {
 	logger.Info("PgSQL query debug mode - logging enabled via logger")
@@ -38,7 +71,7 @@ func (p *PgSQLAdapter) EnableQueryDebug() {
 
 func (p *PgSQLAdapter) NewSelect() common.SelectQuery {
 	return &PgSQLSelectQuery{
-		db:         p.db,
+		db:         p.getDB(),
 		driverName: p.driverName,
 		columns:    []string{"*"},
 		args:       make([]interface{}, 0),
@@ -47,7 +80,7 @@ func (p *PgSQLAdapter) NewSelect() common.SelectQuery {
 
 func (p *PgSQLAdapter) NewInsert() common.InsertQuery {
 	return &PgSQLInsertQuery{
-		db:         p.db,
+		db:         p.getDB(),
 		driverName: p.driverName,
 		values:     make(map[string]interface{}),
 	}
@@ -55,7 +88,7 @@ func (p *PgSQLAdapter) NewInsert() common.InsertQuery {
 
 func (p *PgSQLAdapter) NewUpdate() common.UpdateQuery {
 	return &PgSQLUpdateQuery{
-		db:           p.db,
+		db:           p.getDB(),
 		driverName:   p.driverName,
 		sets:         make(map[string]interface{}),
 		args:         make([]interface{}, 0),
@@ -65,7 +98,7 @@ func (p *PgSQLAdapter) NewUpdate() common.UpdateQuery {
 
 func (p *PgSQLAdapter) NewDelete() common.DeleteQuery {
 	return &PgSQLDeleteQuery{
-		db:           p.db,
+		db:           p.getDB(),
 		driverName:   p.driverName,
 		args:         make([]interface{}, 0),
 		whereClauses: make([]string, 0),
@@ -79,7 +112,14 @@ func (p *PgSQLAdapter) Exec(ctx context.Context, query string, args ...interface
 		}
 	}()
 	logger.Debug("PgSQL Exec: %s [args: %v]", query, args)
-	result, err := p.db.ExecContext(ctx, query, args...)
+	var result sql.Result
+	run := func() error { var e error; result, e = p.getDB().ExecContext(ctx, query, args...); return e }
+	err = run()
+	if isDBClosed(err) {
+		if reconnErr := p.reconnectDB(); reconnErr == nil {
+			err = run()
+		}
+	}
 	if err != nil {
 		logger.Error("PgSQL Exec failed: %v", err)
 		return nil, err
@@ -94,7 +134,14 @@ func (p *PgSQLAdapter) Query(ctx context.Context, dest interface{}, query string
 		}
 	}()
 	logger.Debug("PgSQL Query: %s [args: %v]", query, args)
-	rows, err := p.db.QueryContext(ctx, query, args...)
+	var rows *sql.Rows
+	run := func() error { var e error; rows, e = p.getDB().QueryContext(ctx, query, args...); return e }
+	err = run()
+	if isDBClosed(err) {
+		if reconnErr := p.reconnectDB(); reconnErr == nil {
+			err = run()
+		}
+	}
 	if err != nil {
 		logger.Error("PgSQL Query failed: %v", err)
 		return err
@@ -105,7 +152,7 @@ func (p *PgSQLAdapter) Query(ctx context.Context, dest interface{}, query string
 }
 
 func (p *PgSQLAdapter) BeginTx(ctx context.Context) (common.Database, error) {
-	tx, err := p.db.BeginTx(ctx, nil)
+	tx, err := p.getDB().BeginTx(ctx, nil)
 	if err != nil {
 		return nil, err
 	}
@@ -127,7 +174,7 @@ func (p *PgSQLAdapter) RunInTransaction(ctx context.Context, fn func(common.Data
 		}
 	}()
 
-	tx, err := p.db.BeginTx(ctx, nil)
+	tx, err := p.getDB().BeginTx(ctx, nil)
 	if err != nil {
 		return err
 	}

pkg/common/recursive_crud.go

@@ -98,8 +98,8 @@ func (p *NestedCUDProcessor) ProcessNestedCUD(
 		}
 	}
 
-	// Filter regularData to only include fields that exist in the model
+	// Filter regularData to only include fields that exist in the model,
-	// Use MapToStruct to validate and filter fields
+	// and translate JSON keys to their actual database column names.
 	regularData = p.filterValidFields(regularData, model)
 
 	// Inject parent IDs for foreign key resolution
@@ -191,14 +191,15 @@ func (p *NestedCUDProcessor) extractCRUDRequest(data map[string]interface{}) str
 	return ""
 }
 
-// filterValidFields filters input data to only include fields that exist in the model
+// filterValidFields filters input data to only include fields that exist in the model,
-// Uses reflection.MapToStruct to validate fields and extract only those that match the model
+// and translates JSON key names to their actual database column names.
+// For example, a field tagged `json:"_changed_date" bun:"changed_date"` will be
+// included in the result as "changed_date", not "_changed_date".
 func (p *NestedCUDProcessor) filterValidFields(data map[string]interface{}, model interface{}) map[string]interface{} {
 	if len(data) == 0 {
 		return data
 	}
 
-	// Create a new instance of the model to use with MapToStruct
 	modelType := reflect.TypeOf(model)
 	for modelType != nil && (modelType.Kind() == reflect.Ptr || modelType.Kind() == reflect.Slice || modelType.Kind() == reflect.Array) {
 		modelType = modelType.Elem()
@@ -208,25 +209,16 @@ func (p *NestedCUDProcessor) filterValidFields(data map[string]interface{}, mode
 		return data
 	}
 
-	// Create a new instance of the model
+	// Build a mapping from JSON key -> DB column name for all writable fields.
-	tempModel := reflect.New(modelType).Interface()
+	// This both validates which fields belong to the model and translates their names
+	// to the correct column names for use in SQL insert/update queries.
+	jsonToDBCol := reflection.BuildJSONToDBColumnMap(modelType)
 
-	// Use MapToStruct to map the data - this will only map valid fields
-	err := reflection.MapToStruct(data, tempModel)
-	if err != nil {
-		logger.Debug("Error mapping data to model: %v", err)
-		return data
-	}
-
-	// Extract the mapped fields back into a map
-	// This effectively filters out any fields that don't exist in the model
 	filteredData := make(map[string]interface{})
-	tempModelValue := reflect.ValueOf(tempModel).Elem()
-
 	for key, value := range data {
-		// Check if the field was successfully mapped
+		dbColName, exists := jsonToDBCol[key]
-		if fieldWasMapped(tempModelValue, modelType, key) {
+		if exists {
-			filteredData[key] = value
+			filteredData[dbColName] = value
 		} else {
 			logger.Debug("Skipping invalid field '%s' - not found in model %v", key, modelType)
 		}
@@ -235,72 +227,8 @@ func (p *NestedCUDProcessor) filterValidFields(data map[string]interface{}, mode
 	return filteredData
 }
 
-// fieldWasMapped checks if a field with the given key was mapped to the model
+// injectForeignKeys injects parent IDs into data for foreign key fields.
-func fieldWasMapped(modelValue reflect.Value, modelType reflect.Type, key string) bool {
+// data is expected to be keyed by DB column names (as returned by filterValidFields).
-	// Look for the field by JSON tag or field name
-	for i := 0; i < modelType.NumField(); i++ {
-		field := modelType.Field(i)
-
-		// Skip unexported fields
-		if !field.IsExported() {
-			continue
-		}
-
-		// Check JSON tag
-		jsonTag := field.Tag.Get("json")
-		if jsonTag != "" && jsonTag != "-" {
-			parts := strings.Split(jsonTag, ",")
-			if len(parts) > 0 && parts[0] == key {
-				return true
-			}
-		}
-
-		// Check bun tag
-		bunTag := field.Tag.Get("bun")
-		if bunTag != "" && bunTag != "-" {
-			if colName := reflection.ExtractColumnFromBunTag(bunTag); colName == key {
-				return true
-			}
-		}
-
-		// Check gorm tag
-		gormTag := field.Tag.Get("gorm")
-		if gormTag != "" && gormTag != "-" {
-			if colName := reflection.ExtractColumnFromGormTag(gormTag); colName == key {
-				return true
-			}
-		}
-
-		// Check lowercase field name
-		if strings.EqualFold(field.Name, key) {
-			return true
-		}
-
-		// Handle embedded structs recursively
-		if field.Anonymous {
-			fieldType := field.Type
-			if fieldType.Kind() == reflect.Ptr {
-				fieldType = fieldType.Elem()
-			}
-			if fieldType.Kind() == reflect.Struct {
-				embeddedValue := modelValue.Field(i)
-				if embeddedValue.Kind() == reflect.Ptr {
-					if embeddedValue.IsNil() {
-						continue
-					}
-					embeddedValue = embeddedValue.Elem()
-				}
-				if fieldWasMapped(embeddedValue, fieldType, key) {
-					return true
-				}
-			}
-		}
-	}
-
-	return false
-}
-
-// injectForeignKeys injects parent IDs into data for foreign key fields
 func (p *NestedCUDProcessor) injectForeignKeys(data map[string]interface{}, modelType reflect.Type, parentIDs map[string]interface{}) {
 	if len(parentIDs) == 0 {
 		return
@@ -319,10 +247,11 @@ func (p *NestedCUDProcessor) injectForeignKeys(data map[string]interface{}, mode
 			if strings.EqualFold(jsonName, parentKey+"_id") ||
 				strings.EqualFold(jsonName, parentKey+"id") ||
 				strings.EqualFold(field.Name, parentKey+"ID") {
-				// Only inject if not already present
+				// Use the DB column name as the key, since data is keyed by DB column names
-				if _, exists := data[jsonName]; !exists {
+				dbColName := reflection.GetColumnName(field)
-					logger.Debug("Injecting foreign key: %s = %v", jsonName, parentID)
+				if _, exists := data[dbColName]; !exists {
-					data[jsonName] = parentID
+					logger.Debug("Injecting foreign key: %s = %v", dbColName, parentID)
+					data[dbColName] = parentID
 				}
 			}
 		}

pkg/dbmanager/providers/postgres_listener_example_test.go

@@ -3,6 +3,7 @@ package providers_test
 import (
 	"context"
 	"fmt"
+	"log"
 	"time"
 
 	"github.com/bitechdev/ResolveSpec/pkg/dbmanager"
@@ -29,14 +30,14 @@ func ExamplePostgresListener_basic() {
 	ctx := context.Background()
 
 	if err := provider.Connect(ctx, cfg); err != nil {
-		panic(fmt.Sprintf("Failed to connect: %v", err))
+		log.Fatalf("Failed to connect: %v", err)
 	}
 	defer provider.Close()
 
 	// Get listener
 	listener, err := provider.GetListener(ctx)
 	if err != nil {
-		panic(fmt.Sprintf("Failed to get listener: %v", err))
+		log.Fatalf("Failed to get listener: %v", err)
 	}
 
 	// Subscribe to a channel with a handler
@@ -44,13 +45,13 @@ func ExamplePostgresListener_basic() {
 		fmt.Printf("Received notification on %s: %s\n", channel, payload)
 	})
 	if err != nil {
-		panic(fmt.Sprintf("Failed to listen: %v", err))
+		log.Fatalf("Failed to listen: %v", err)
 	}
 
 	// Send a notification
 	err = listener.Notify(ctx, "user_events", `{"event":"user_created","user_id":123}`)
 	if err != nil {
-		panic(fmt.Sprintf("Failed to notify: %v", err))
+		log.Fatalf("Failed to notify: %v", err)
 	}
 
 	// Wait for notification to be processed
@@ -58,7 +59,7 @@ func ExamplePostgresListener_basic() {
 
 	// Unsubscribe from the channel
 	if err := listener.Unlisten("user_events"); err != nil {
-		panic(fmt.Sprintf("Failed to unlisten: %v", err))
+		log.Fatalf("Failed to unlisten: %v", err)
 	}
 }
 
@@ -80,13 +81,13 @@ func ExamplePostgresListener_multipleChannels() {
 	ctx := context.Background()
 
 	if err := provider.Connect(ctx, cfg); err != nil {
-		panic(fmt.Sprintf("Failed to connect: %v", err))
+		log.Fatalf("Failed to connect: %v", err)
 	}
 	defer provider.Close()
 
 	listener, err := provider.GetListener(ctx)
 	if err != nil {
-		panic(fmt.Sprintf("Failed to get listener: %v", err))
+		log.Fatalf("Failed to get listener: %v", err)
 	}
 
 	// Listen to multiple channels
@@ -97,7 +98,7 @@ func ExamplePostgresListener_multipleChannels() {
 			fmt.Printf("[%s] %s\n", ch, payload)
 		})
 		if err != nil {
-			panic(fmt.Sprintf("Failed to listen on %s: %v", channel, err))
+			log.Fatalf("Failed to listen on %s: %v", channel, err)
 		}
 	}
 
@@ -140,14 +141,14 @@ func ExamplePostgresListener_withDBManager() {
 
 	provider := providers.NewPostgresProvider()
 	if err := provider.Connect(ctx, cfg); err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 	defer provider.Close()
 
 	// Get listener
 	listener, err := provider.GetListener(ctx)
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Subscribe to application events
@@ -186,13 +187,13 @@ func ExamplePostgresListener_errorHandling() {
 	ctx := context.Background()
 
 	if err := provider.Connect(ctx, cfg); err != nil {
-		panic(fmt.Sprintf("Failed to connect: %v", err))
+		log.Fatalf("Failed to connect: %v", err)
 	}
 	defer provider.Close()
 
 	listener, err := provider.GetListener(ctx)
 	if err != nil {
-		panic(fmt.Sprintf("Failed to get listener: %v", err))
+		log.Fatalf("Failed to get listener: %v", err)
 	}
 
 	// The listener automatically reconnects if the connection is lost

pkg/dbmanager/providers/provider.go

@@ -4,11 +4,17 @@ import (
 	"context"
 	"database/sql"
 	"errors"
+	"strings"
 	"time"
 
 	"go.mongodb.org/mongo-driver/mongo"
 )
 
+// isDBClosed reports whether err indicates the *sql.DB has been closed.
+func isDBClosed(err error) bool {
+	return err != nil && strings.Contains(err.Error(), "sql: database is closed")
+}
+
 // Common errors
 var (
 	// ErrNotSQLDatabase is returned when attempting SQL operations on a non-SQL database

pkg/dbmanager/providers/sqlite.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"database/sql"
 	"fmt"
+	"sync"
 	"time"
 
 	_ "github.com/glebarez/sqlite" // Pure Go SQLite driver
@@ -15,6 +16,8 @@ import (
 // SQLiteProvider implements Provider for SQLite databases
 type SQLiteProvider struct {
 	db        *sql.DB
+	dbMu      sync.RWMutex
+	dbFactory func() (*sql.DB, error)
 	config    ConnectionConfig
 }
 
@@ -129,7 +132,13 @@ func (p *SQLiteProvider) HealthCheck(ctx context.Context) error {
 
 	// Execute a simple query to verify the database is accessible
 	var result int
-	err := p.db.QueryRowContext(healthCtx, "SELECT 1").Scan(&result)
+	run := func() error { return p.getDB().QueryRowContext(healthCtx, "SELECT 1").Scan(&result) }
+	err := run()
+	if isDBClosed(err) {
+		if reconnErr := p.reconnectDB(); reconnErr == nil {
+			err = run()
+		}
+	}
 	if err != nil {
 		return fmt.Errorf("health check failed: %w", err)
 	}
@@ -141,6 +150,32 @@ func (p *SQLiteProvider) HealthCheck(ctx context.Context) error {
 	return nil
 }
 
+// WithDBFactory configures a factory used to reopen the database connection if it is closed.
+func (p *SQLiteProvider) WithDBFactory(factory func() (*sql.DB, error)) *SQLiteProvider {
+	p.dbFactory = factory
+	return p
+}
+
+func (p *SQLiteProvider) getDB() *sql.DB {
+	p.dbMu.RLock()
+	defer p.dbMu.RUnlock()
+	return p.db
+}
+
+func (p *SQLiteProvider) reconnectDB() error {
+	if p.dbFactory == nil {
+		return fmt.Errorf("no db factory configured for reconnect")
+	}
+	newDB, err := p.dbFactory()
+	if err != nil {
+		return err
+	}
+	p.dbMu.Lock()
+	p.db = newDB
+	p.dbMu.Unlock()
+	return nil
+}
+
 // GetNative returns the native *sql.DB connection
 func (p *SQLiteProvider) GetNative() (*sql.DB, error) {
 	if p.db == nil {

pkg/reflection/model_utils.go

@@ -196,6 +196,92 @@ func collectColumnsFromType(typ reflect.Type, columns *[]string) {
 	}
 }
 
+// GetColumnName extracts the database column name from a struct field.
+// Priority: bun tag -> gorm tag -> json tag -> lowercase field name.
+// This is the exported version for use by other packages.
+func GetColumnName(field reflect.StructField) string {
+	return getColumnNameFromField(field)
+}
+
+// BuildJSONToDBColumnMap returns a map from JSON key names to database column names
+// for the given model type. Only writable, non-relation fields are included.
+// This is used to translate incoming request data (keyed by JSON names) into
+// properly named database columns before insert/update operations.
+func BuildJSONToDBColumnMap(modelType reflect.Type) map[string]string {
+	result := make(map[string]string)
+	buildJSONToDBMap(modelType, result, false)
+	return result
+}
+
+func buildJSONToDBMap(modelType reflect.Type, result map[string]string, scanOnly bool) {
+	for i := 0; i < modelType.NumField(); i++ {
+		field := modelType.Field(i)
+		if !field.IsExported() {
+			continue
+		}
+
+		bunTag := field.Tag.Get("bun")
+		gormTag := field.Tag.Get("gorm")
+
+		// Handle embedded structs
+		if field.Anonymous {
+			ft := field.Type
+			if ft.Kind() == reflect.Ptr {
+				ft = ft.Elem()
+			}
+			isScanOnly := scanOnly
+			if bunTag != "" && isBunFieldScanOnly(bunTag) {
+				isScanOnly = true
+			}
+			if ft.Kind() == reflect.Struct {
+				buildJSONToDBMap(ft, result, isScanOnly)
+				continue
+			}
+		}
+
+		if scanOnly {
+			continue
+		}
+
+		// Skip explicitly excluded fields
+		if bunTag == "-" || gormTag == "-" {
+			continue
+		}
+
+		// Skip scan-only fields
+		if bunTag != "" && isBunFieldScanOnly(bunTag) {
+			continue
+		}
+
+		// Skip bun relation fields
+		if bunTag != "" && (strings.Contains(bunTag, "rel:") || strings.Contains(bunTag, "join:") || strings.Contains(bunTag, "m2m:")) {
+			continue
+		}
+
+		// Skip gorm relation fields
+		if gormTag != "" && (strings.Contains(gormTag, "foreignKey:") || strings.Contains(gormTag, "references:") || strings.Contains(gormTag, "many2many:")) {
+			continue
+		}
+
+		// Get JSON key (how the field appears in incoming request data)
+		jsonKey := ""
+		if jsonTag := field.Tag.Get("json"); jsonTag != "" && jsonTag != "-" {
+			parts := strings.Split(jsonTag, ",")
+			if len(parts) > 0 && parts[0] != "" {
+				jsonKey = parts[0]
+			}
+		}
+		if jsonKey == "" {
+			jsonKey = strings.ToLower(field.Name)
+		}
+
+		// Get the actual DB column name (bun > gorm > json > field name)
+		dbColName := getColumnNameFromField(field)
+
+		result[jsonKey] = dbColName
+	}
+}
+
 // getColumnNameFromField extracts the column name from a struct field
 // Priority: bun tag -> gorm tag -> json tag -> lowercase field name
 func getColumnNameFromField(field reflect.StructField) string {

pkg/reflection/model_utils_test.go

@@ -823,12 +823,12 @@ func TestToSnakeCase(t *testing.T) {
 		{
 			name:     "UserID",
 			input:    "UserID",
-			expected: "user_i_d",
+			expected: "user_id",
 		},
 		{
 			name:     "HTTPServer",
 			input:    "HTTPServer",
-			expected: "h_t_t_p_server",
+			expected: "http_server",
 		},
 		{
 			name:     "lowercase",
@@ -838,7 +838,7 @@ func TestToSnakeCase(t *testing.T) {
 		{
 			name:     "UPPERCASE",
 			input:    "UPPERCASE",
-			expected: "u_p_p_e_r_c_a_s_e",
+			expected: "uppercase",
 		},
 		{
 			name:     "Single",

pkg/resolvemcp/README.md

@@ -142,9 +142,138 @@ e.Any("/mcp", echo.WrapHandler(h))     // Echo
 
 ---
 
-### Authentication
+## OAuth2 Authentication
 
-Add middleware before the MCP routes. The handler itself has no auth layer.
+`resolvemcp` ships a full **MCP-standard OAuth2 authorization server** (`pkg/security.OAuthServer`) that MCP clients (Claude Desktop, Cursor, etc.) can discover and use automatically.
+
+It can operate as:
+- **Its own identity provider** — shows a login form, validates via `DatabaseAuthenticator.Login()`
+- **An OAuth2 federation layer** — delegates to external providers (Google, GitHub, Microsoft, etc.)
+- **Both simultaneously**
+
+### Standard endpoints served
+
+| Path | Spec | Purpose |
+|---|---|---|
+| `GET /.well-known/oauth-authorization-server` | RFC 8414 | MCP client auto-discovery |
+| `POST /oauth/register` | RFC 7591 | Dynamic client registration |
+| `GET /oauth/authorize` | OAuth 2.1 + PKCE | Start login (form or provider redirect) |
+| `POST /oauth/authorize` | — | Login form submission |
+| `POST /oauth/token` | OAuth 2.1 | Auth code → Bearer token exchange |
+| `POST /oauth/token` (refresh) | OAuth 2.1 | Refresh token rotation |
+| `GET /oauth/provider/callback` | Internal | External provider redirect target |
+
+MCP clients send `Authorization: Bearer <token>` on all subsequent requests.
+
+---
+
+### Mode 1 — Direct login (server as identity provider)
+
+```go
+import "github.com/bitechdev/ResolveSpec/pkg/security"
+
+db, _ := sql.Open("postgres", dsn)
+auth := security.NewDatabaseAuthenticator(db)
+
+handler := resolvemcp.NewHandlerWithGORM(gormDB, resolvemcp.Config{
+    BaseURL:  "https://api.example.com",
+    BasePath: "/mcp",
+})
+
+// Enable the OAuth2 server — auth enables the login form
+handler.EnableOAuthServer(security.OAuthServerConfig{
+    Issuer: "https://api.example.com",
+}, auth)
+
+provider, _ := security.NewCompositeSecurityProvider(auth, colSec, rowSec)
+securityList, _ := security.NewSecurityList(provider)
+security.RegisterSecurityHooks(handler, securityList)
+
+http.ListenAndServe(":8080", handler.HTTPHandler(securityList))
+```
+
+MCP client flow:
+1. Discovers server at `/.well-known/oauth-authorization-server`
+2. Registers itself at `/oauth/register`
+3. Redirects user to `/oauth/authorize` → login form appears
+4. On submit, exchanges code at `/oauth/token` → receives `Authorization: Bearer` token
+5. Uses token on all MCP tool calls
+
+---
+
+### Mode 2 — External provider (Google, GitHub, etc.)
+
+The `RedirectURL` in the provider config must point to `/oauth/provider/callback` on this server.
+
+```go
+auth := security.NewDatabaseAuthenticator(db).WithOAuth2(security.OAuth2Config{
+    ClientID:     os.Getenv("GOOGLE_CLIENT_ID"),
+    ClientSecret: os.Getenv("GOOGLE_CLIENT_SECRET"),
+    RedirectURL:  "https://api.example.com/oauth/provider/callback",
+    Scopes:       []string{"openid", "profile", "email"},
+    AuthURL:      "https://accounts.google.com/o/oauth2/auth",
+    TokenURL:     "https://oauth2.googleapis.com/token",
+    UserInfoURL:  "https://www.googleapis.com/oauth2/v2/userinfo",
+    ProviderName: "google",
+})
+
+// Pass `auth` so the OAuth server supports persistence, introspection, and revocation.
+// Google handles the end-user authentication flow via redirect.
+handler.EnableOAuthServer(security.OAuthServerConfig{
+    Issuer: "https://api.example.com",
+}, auth)
+handler.RegisterOAuth2Provider(auth, "google")
+```
+
+---
+
+### Mode 3 — Both (login form + external providers)
+
+```go
+handler.EnableOAuthServer(security.OAuthServerConfig{
+    Issuer:     "https://api.example.com",
+    LoginTitle: "My App Login",
+}, auth) // auth enables the username/password form
+
+handler.RegisterOAuth2Provider(googleAuth, "google")
+handler.RegisterOAuth2Provider(githubAuth, "github")
+```
+
+When external providers are registered they take priority; the login form is used as fallback when no providers are configured.
+
+---
+
+### Using `security.OAuthServer` standalone
+
+The authorization server lives in `pkg/security` and can be used with any HTTP framework independently of `resolvemcp`:
+
+```go
+oauthSrv := security.NewOAuthServer(security.OAuthServerConfig{
+    Issuer: "https://api.example.com",
+}, auth)
+oauthSrv.RegisterExternalProvider(googleAuth, "google")
+
+mux := http.NewServeMux()
+mux.Handle("/", oauthSrv.HTTPHandler())   // mounts all OAuth2 routes
+mux.Handle("/mcp/", myMCPHandler)
+http.ListenAndServe(":8080", mux)
+```
+
+---
+
+### Cookie-based flow (legacy)
+
+For simple setups without full MCP OAuth2 compliance, use the legacy helpers that set a session cookie after external provider login:
+
+```go
+resolvemcp.SetupMuxOAuth2Routes(r, auth, resolvemcp.OAuth2RouteConfig{
+    ProviderName:       "google",
+    LoginPath:          "/auth/google/login",
+    CallbackPath:       "/auth/google/callback",
+    AfterLoginRedirect: "/",
+})
+resolvemcp.SetupMuxRoutesWithAuth(r, handler, securityList)
+```
 
 ---
 

pkg/resolvemcp/handler.go

@@ -16,6 +16,7 @@ import (
 	"github.com/bitechdev/ResolveSpec/pkg/logger"
 	"github.com/bitechdev/ResolveSpec/pkg/modelregistry"
 	"github.com/bitechdev/ResolveSpec/pkg/reflection"
+	"github.com/bitechdev/ResolveSpec/pkg/security"
 )
 
 // Handler exposes registered database models as MCP tools and resources.
@@ -27,6 +28,8 @@ type Handler struct {
 	config     Config
 	name       string
 	version    string
+	oauth2Regs []oauth2Registration
+	oauthSrv   *security.OAuthServer
 }
 
 // NewHandler creates a Handler with the given database, model registry, and config.
@@ -197,8 +200,19 @@ func (h *Handler) getSchemaAndTable(defaultSchema, entity string, model interfac
 	return defaultSchema, entity
 }
 
+// recoverPanic catches a panic from the current goroutine and returns it as an error.
+// Usage: defer recoverPanic(&returnedErr)
+func recoverPanic(err *error) {
+	if r := recover(); r != nil {
+		msg := fmt.Sprintf("%v", r)
+		logger.Error("[resolvemcp] panic recovered: %s", msg)
+		*err = fmt.Errorf("internal error: %s", msg)
+	}
+}
+
 // executeRead reads records from the database and returns raw data + metadata.
-func (h *Handler) executeRead(ctx context.Context, schema, entity, id string, options common.RequestOptions) (interface{}, *common.Metadata, error) {
+func (h *Handler) executeRead(ctx context.Context, schema, entity, id string, options common.RequestOptions) (_ interface{}, _ *common.Metadata, retErr error) {
+	defer recoverPanic(&retErr)
 	model, err := h.registry.GetModelByEntity(schema, entity)
 	if err != nil {
 		return nil, nil, fmt.Errorf("model not found: %w", err)
@@ -254,15 +268,6 @@ func (h *Handler) executeRead(ctx context.Context, schema, entity, id string, op
 		query = query.ColumnExpr(fmt.Sprintf("(%s) AS %s", cu.Expression, cu.Name))
 	}
 
-	// Preloads
-	if len(options.Preload) > 0 {
-		var err error
-		query, err = h.applyPreloads(model, query, options.Preload)
-		if err != nil {
-			return nil, nil, fmt.Errorf("failed to apply preloads: %w", err)
-		}
-	}
-
 	// Filters
 	query = h.applyFilters(query, options.Filters)
 
@@ -304,7 +309,7 @@ func (h *Handler) executeRead(ctx context.Context, schema, entity, id string, op
 		}
 	}
 
-	// Count
+	// Count — must happen before preloads are applied; Bun panics when counting with relations.
 	total, err := query.Count(ctx)
 	if err != nil {
 		return nil, nil, fmt.Errorf("error counting records: %w", err)
@@ -318,6 +323,15 @@ func (h *Handler) executeRead(ctx context.Context, schema, entity, id string, op
 		query = query.Offset(*options.Offset)
 	}
 
+	// Preloads — applied after count to avoid Bun panic when counting with relations.
+	if len(options.Preload) > 0 {
+		var preloadErr error
+		query, preloadErr = h.applyPreloads(model, query, options.Preload)
+		if preloadErr != nil {
+			return nil, nil, fmt.Errorf("failed to apply preloads: %w", preloadErr)
+		}
+	}
+
 	// BeforeRead hook
 	hookCtx.Query = query
 	if err := h.hooks.Execute(BeforeRead, hookCtx); err != nil {
@@ -378,7 +392,8 @@ func (h *Handler) executeRead(ctx context.Context, schema, entity, id string, op
 }
 
 // executeCreate inserts one or more records.
-func (h *Handler) executeCreate(ctx context.Context, schema, entity string, data interface{}) (interface{}, error) {
+func (h *Handler) executeCreate(ctx context.Context, schema, entity string, data interface{}) (_ interface{}, retErr error) {
+	defer recoverPanic(&retErr)
 	model, err := h.registry.GetModelByEntity(schema, entity)
 	if err != nil {
 		return nil, fmt.Errorf("model not found: %w", err)
@@ -462,7 +477,8 @@ func (h *Handler) executeCreate(ctx context.Context, schema, entity string, data
 }
 
 // executeUpdate updates a record by ID.
-func (h *Handler) executeUpdate(ctx context.Context, schema, entity, id string, data interface{}) (interface{}, error) {
+func (h *Handler) executeUpdate(ctx context.Context, schema, entity, id string, data interface{}) (_ interface{}, retErr error) {
+	defer recoverPanic(&retErr)
 	model, err := h.registry.GetModelByEntity(schema, entity)
 	if err != nil {
 		return nil, fmt.Errorf("model not found: %w", err)
@@ -572,7 +588,8 @@ func (h *Handler) executeUpdate(ctx context.Context, schema, entity, id string,
 }
 
 // executeDelete deletes a record by ID.
-func (h *Handler) executeDelete(ctx context.Context, schema, entity, id string) (interface{}, error) {
+func (h *Handler) executeDelete(ctx context.Context, schema, entity, id string) (_ interface{}, retErr error) {
+	defer recoverPanic(&retErr)
 	if id == "" {
 		return nil, fmt.Errorf("delete requires an ID")
 	}
@@ -703,7 +720,7 @@ func (h *Handler) applyFilterGroup(query common.SelectQuery, filters []common.Fi
 	return query.Where("("+strings.Join(conditions, " OR ")+")", args...)
 }
 
-func (h *Handler) buildFilterCondition(filter common.FilterOption) (string, []interface{}) {
+func (h *Handler) buildFilterCondition(filter common.FilterOption) (condition string, args []interface{}) {
 	switch filter.Operator {
 	case "eq", "=":
 		return fmt.Sprintf("%s = ?", filter.Column), []interface{}{filter.Value}
@@ -733,7 +750,8 @@ func (h *Handler) buildFilterCondition(filter common.FilterOption) (string, []in
 }
 
 func (h *Handler) applyPreloads(model interface{}, query common.SelectQuery, preloads []common.PreloadOption) (common.SelectQuery, error) {
-	for _, preload := range preloads {
+	for i := range preloads {
+		preload := &preloads[i]
 		if preload.Relation == "" {
 			continue
 		}

pkg/resolvemcp/oauth2.go

@@ -0,0 +1,264 @@
+package resolvemcp
+
+import (
+	"encoding/json"
+	"net/http"
+
+	"github.com/gorilla/mux"
+
+	"github.com/bitechdev/ResolveSpec/pkg/security"
+)
+
+// --------------------------------------------------------------------------
+// OAuth2 registration on the Handler
+// --------------------------------------------------------------------------
+
+// oauth2Registration stores a configured auth provider and its route config.
+type oauth2Registration struct {
+	auth *security.DatabaseAuthenticator
+	cfg  OAuth2RouteConfig
+}
+
+// RegisterOAuth2 attaches an OAuth2 provider to the Handler.
+// The login and callback HTTP routes are served by HTTPHandler / StreamableHTTPMux.
+// Call this once per provider before serving requests.
+//
+// Example:
+//
+//	auth := security.NewGoogleAuthenticator(clientID, secret, redirectURL, db)
+//	handler.RegisterOAuth2(auth, resolvemcp.OAuth2RouteConfig{
+//	    ProviderName:       "google",
+//	    LoginPath:          "/auth/google/login",
+//	    CallbackPath:       "/auth/google/callback",
+//	    AfterLoginRedirect: "/",
+//	})
+func (h *Handler) RegisterOAuth2(auth *security.DatabaseAuthenticator, cfg OAuth2RouteConfig) {
+	h.oauth2Regs = append(h.oauth2Regs, oauth2Registration{auth: auth, cfg: cfg})
+}
+
+// HTTPHandler returns a single http.Handler that serves:
+//   - MCP OAuth2 authorization server endpoints (when EnableOAuthServer has been called)
+//   - OAuth2 login + callback routes for every registered provider (legacy cookie flow)
+//   - The MCP SSE transport wrapped with required authentication middleware
+//
+// Example:
+//
+//	auth := security.NewGoogleAuthenticator(...)
+//	handler.RegisterOAuth2(auth, cfg)
+//	handler.EnableOAuthServer(security.OAuthServerConfig{Issuer: "https://api.example.com"})
+//	security.RegisterSecurityHooks(handler, securityList)
+//	http.ListenAndServe(":8080", handler.HTTPHandler(securityList))
+func (h *Handler) HTTPHandler(securityList *security.SecurityList) http.Handler {
+	mux := http.NewServeMux()
+	if h.oauthSrv != nil {
+		h.mountOAuthServerRoutes(mux)
+	}
+	h.mountOAuth2Routes(mux)
+
+	mcpHandler := h.AuthedSSEServer(securityList)
+	basePath := h.config.BasePath
+	if basePath == "" {
+		basePath = "/mcp"
+	}
+	mux.Handle(basePath+"/sse", mcpHandler)
+	mux.Handle(basePath+"/message", mcpHandler)
+	mux.Handle(basePath+"/", http.StripPrefix(basePath, mcpHandler))
+
+	return mux
+}
+
+// StreamableHTTPMux returns a single http.Handler that serves:
+//   - MCP OAuth2 authorization server endpoints (when EnableOAuthServer has been called)
+//   - OAuth2 login + callback routes for every registered provider (legacy cookie flow)
+//   - The MCP streamable HTTP transport wrapped with required authentication middleware
+//
+// Example:
+//
+//	http.ListenAndServe(":8080", handler.StreamableHTTPMux(securityList))
+func (h *Handler) StreamableHTTPMux(securityList *security.SecurityList) http.Handler {
+	mux := http.NewServeMux()
+	if h.oauthSrv != nil {
+		h.mountOAuthServerRoutes(mux)
+	}
+	h.mountOAuth2Routes(mux)
+
+	mcpHandler := h.AuthedStreamableHTTPServer(securityList)
+	basePath := h.config.BasePath
+	if basePath == "" {
+		basePath = "/mcp"
+	}
+	mux.Handle(basePath+"/", http.StripPrefix(basePath, mcpHandler))
+	mux.Handle(basePath, mcpHandler)
+
+	return mux
+}
+
+// mountOAuth2Routes registers all stored OAuth2 login+callback routes onto mux.
+func (h *Handler) mountOAuth2Routes(mux *http.ServeMux) {
+	for _, reg := range h.oauth2Regs {
+		var cookieOpts []security.SessionCookieOptions
+		if reg.cfg.CookieOptions != nil {
+			cookieOpts = append(cookieOpts, *reg.cfg.CookieOptions)
+		}
+		mux.Handle(reg.cfg.LoginPath, OAuth2LoginHandler(reg.auth, reg.cfg.ProviderName))
+		mux.Handle(reg.cfg.CallbackPath, OAuth2CallbackHandler(reg.auth, reg.cfg.ProviderName, reg.cfg.AfterLoginRedirect, cookieOpts...))
+	}
+}
+
+// --------------------------------------------------------------------------
+// Auth-wrapped transports
+// --------------------------------------------------------------------------
+
+// AuthedSSEServer wraps SSEServer with required authentication middleware from pkg/security.
+// The middleware reads the session cookie / Authorization header and populates the user
+// context into the request context, making it available to BeforeHandle security hooks.
+// Unauthenticated requests receive 401 before reaching any MCP tool.
+func (h *Handler) AuthedSSEServer(securityList *security.SecurityList) http.Handler {
+	return security.NewAuthMiddleware(securityList)(h.SSEServer())
+}
+
+// OptionalAuthSSEServer wraps SSEServer with optional authentication middleware.
+// Unauthenticated requests continue as guest rather than returning 401.
+// Use together with RegisterSecurityHooks and per-model CanPublicRead/Write rules
+// to allow mixed public/private access.
+func (h *Handler) OptionalAuthSSEServer(securityList *security.SecurityList) http.Handler {
+	return security.NewOptionalAuthMiddleware(securityList)(h.SSEServer())
+}
+
+// AuthedStreamableHTTPServer wraps StreamableHTTPServer with required authentication middleware.
+func (h *Handler) AuthedStreamableHTTPServer(securityList *security.SecurityList) http.Handler {
+	return security.NewAuthMiddleware(securityList)(h.StreamableHTTPServer())
+}
+
+// OptionalAuthStreamableHTTPServer wraps StreamableHTTPServer with optional authentication middleware.
+func (h *Handler) OptionalAuthStreamableHTTPServer(securityList *security.SecurityList) http.Handler {
+	return security.NewOptionalAuthMiddleware(securityList)(h.StreamableHTTPServer())
+}
+
+// --------------------------------------------------------------------------
+// OAuth2 route config and standalone handlers
+// --------------------------------------------------------------------------
+
+// OAuth2RouteConfig configures the OAuth2 HTTP endpoints for a single provider.
+type OAuth2RouteConfig struct {
+	// ProviderName is the OAuth2 provider name as registered with WithOAuth2()
+	// (e.g. "google", "github", "microsoft").
+	ProviderName string
+
+	// LoginPath is the HTTP path that redirects the browser to the OAuth2 provider
+	// (e.g. "/auth/google/login").
+	LoginPath string
+
+	// CallbackPath is the HTTP path that the OAuth2 provider redirects back to
+	// (e.g. "/auth/google/callback"). Must match the RedirectURL in OAuth2Config.
+	CallbackPath string
+
+	// AfterLoginRedirect is the URL to redirect the browser to after a successful
+	// login. When empty the LoginResponse JSON is written directly to the response.
+	AfterLoginRedirect string
+
+	// CookieOptions customises the session cookie written on successful login.
+	// Defaults to HttpOnly, Secure, SameSite=Lax when nil.
+	CookieOptions *security.SessionCookieOptions
+}
+
+// OAuth2LoginHandler returns an http.HandlerFunc that redirects the browser to
+// the OAuth2 provider's authorization URL.
+//
+// Register it on any router:
+//
+//	mux.Handle("/auth/google/login", resolvemcp.OAuth2LoginHandler(auth, "google"))
+func OAuth2LoginHandler(auth *security.DatabaseAuthenticator, providerName string) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		state, err := auth.OAuth2GenerateState()
+		if err != nil {
+			http.Error(w, "failed to generate state", http.StatusInternalServerError)
+			return
+		}
+		authURL, err := auth.OAuth2GetAuthURL(providerName, state)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+		http.Redirect(w, r, authURL, http.StatusTemporaryRedirect)
+	}
+}
+
+// OAuth2CallbackHandler returns an http.HandlerFunc that handles the OAuth2 provider
+// callback: exchanges the authorization code for a session token, writes the session
+// cookie, then either redirects to afterLoginRedirect or writes the LoginResponse as JSON.
+//
+// Register it on any router:
+//
+//	mux.Handle("/auth/google/callback", resolvemcp.OAuth2CallbackHandler(auth, "google", "/dashboard"))
+func OAuth2CallbackHandler(auth *security.DatabaseAuthenticator, providerName, afterLoginRedirect string, cookieOpts ...security.SessionCookieOptions) http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		code := r.URL.Query().Get("code")
+		state := r.URL.Query().Get("state")
+		if code == "" {
+			http.Error(w, "missing code parameter", http.StatusBadRequest)
+			return
+		}
+
+		loginResp, err := auth.OAuth2HandleCallback(r.Context(), providerName, code, state)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusUnauthorized)
+			return
+		}
+
+		security.SetSessionCookie(w, loginResp, cookieOpts...)
+
+		if afterLoginRedirect != "" {
+			http.Redirect(w, r, afterLoginRedirect, http.StatusTemporaryRedirect)
+			return
+		}
+		w.Header().Set("Content-Type", "application/json")
+		json.NewEncoder(w).Encode(loginResp) //nolint:errcheck
+	}
+}
+
+// --------------------------------------------------------------------------
+// Gorilla Mux convenience helpers
+// --------------------------------------------------------------------------
+
+// SetupMuxOAuth2Routes registers the OAuth2 login and callback routes on a Gorilla Mux router.
+//
+// Example:
+//
+//	resolvemcp.SetupMuxOAuth2Routes(r, auth, resolvemcp.OAuth2RouteConfig{
+//	    ProviderName: "google", LoginPath: "/auth/google/login",
+//	    CallbackPath: "/auth/google/callback", AfterLoginRedirect: "/",
+//	})
+func SetupMuxOAuth2Routes(muxRouter *mux.Router, auth *security.DatabaseAuthenticator, cfg OAuth2RouteConfig) {
+	var cookieOpts []security.SessionCookieOptions
+	if cfg.CookieOptions != nil {
+		cookieOpts = append(cookieOpts, *cfg.CookieOptions)
+	}
+
+	muxRouter.Handle(cfg.LoginPath,
+		OAuth2LoginHandler(auth, cfg.ProviderName),
+	).Methods(http.MethodGet)
+
+	muxRouter.Handle(cfg.CallbackPath,
+		OAuth2CallbackHandler(auth, cfg.ProviderName, cfg.AfterLoginRedirect, cookieOpts...),
+	).Methods(http.MethodGet)
+}
+
+// SetupMuxRoutesWithAuth mounts the MCP SSE endpoints on a Gorilla Mux router
+// with required authentication middleware applied.
+func SetupMuxRoutesWithAuth(muxRouter *mux.Router, handler *Handler, securityList *security.SecurityList) {
+	basePath := handler.config.BasePath
+	h := handler.AuthedSSEServer(securityList)
+
+	muxRouter.Handle(basePath+"/sse", h).Methods(http.MethodGet, http.MethodOptions)
+	muxRouter.Handle(basePath+"/message", h).Methods(http.MethodPost, http.MethodOptions)
+	muxRouter.PathPrefix(basePath).Handler(http.StripPrefix(basePath, h))
+}
+
+// SetupMuxStreamableHTTPRoutesWithAuth mounts the MCP streamable HTTP endpoint on a
+// Gorilla Mux router with required authentication middleware applied.
+func SetupMuxStreamableHTTPRoutesWithAuth(muxRouter *mux.Router, handler *Handler, securityList *security.SecurityList) {
+	basePath := handler.config.BasePath
+	h := handler.AuthedStreamableHTTPServer(securityList)
+	muxRouter.PathPrefix(basePath).Handler(http.StripPrefix(basePath, h))
+}

pkg/resolvemcp/oauth2_server.go

@@ -0,0 +1,51 @@
+package resolvemcp
+
+import (
+	"net/http"
+
+	"github.com/bitechdev/ResolveSpec/pkg/security"
+)
+
+// EnableOAuthServer activates the MCP-standard OAuth2 authorization server on this Handler.
+//
+// Pass a DatabaseAuthenticator to enable direct username/password login — the server acts as
+// its own identity provider and renders a login form at /oauth/authorize. Pass nil to use
+// only external providers registered via RegisterOAuth2Provider.
+//
+// After calling this, HTTPHandler and StreamableHTTPMux serve the full set of RFC-compliant
+// endpoints required by MCP clients alongside the MCP transport:
+//
+//	GET  /.well-known/oauth-authorization-server   RFC 8414 — auto-discovery
+//	POST /oauth/register                            RFC 7591 — dynamic client registration
+//	GET  /oauth/authorize                           OAuth 2.1 + PKCE — start login
+//	POST /oauth/authorize                           Login form submission (password flow)
+//	POST /oauth/token                               Bearer token exchange + refresh
+//	GET  /oauth/provider/callback                   External provider redirect target
+func (h *Handler) EnableOAuthServer(cfg security.OAuthServerConfig, auth *security.DatabaseAuthenticator) {
+	h.oauthSrv = security.NewOAuthServer(cfg, auth)
+	// Wire any external providers already registered via RegisterOAuth2
+	for _, reg := range h.oauth2Regs {
+		h.oauthSrv.RegisterExternalProvider(reg.auth, reg.cfg.ProviderName)
+	}
+}
+
+// RegisterOAuth2Provider adds an external OAuth2 provider to the MCP OAuth2 authorization server.
+// EnableOAuthServer must be called before this. The auth must have been configured with
+// WithOAuth2(providerName, ...) for the given provider name.
+func (h *Handler) RegisterOAuth2Provider(auth *security.DatabaseAuthenticator, providerName string) {
+	if h.oauthSrv != nil {
+		h.oauthSrv.RegisterExternalProvider(auth, providerName)
+	}
+}
+
+// mountOAuthServerRoutes mounts the security.OAuthServer's HTTP handler onto mux.
+func (h *Handler) mountOAuthServerRoutes(mux *http.ServeMux) {
+	oauthHandler := h.oauthSrv.HTTPHandler()
+	// Delegate all /oauth/ and /.well-known/ paths to the OAuth server
+	mux.Handle("/.well-known/", oauthHandler)
+	mux.Handle("/oauth/", oauthHandler)
+	if h.oauthSrv != nil {
+		// Also mount the external provider callback path if it differs from /oauth/
+		mux.Handle(h.oauthSrv.ProviderCallbackPath(), oauthHandler)
+	}
+}

pkg/security/KEYSTORE.md

@@ -0,0 +1,153 @@
+# Keystore
+
+Per-user named auth keys with pluggable storage. Each user can hold multiple keys of different types — JWT secrets, header API keys, OAuth2 client credentials, or generic API keys. Keys are identified by a human-readable name ("CI deploy", "mobile app") and can carry scopes and arbitrary metadata.
+
+## Key types
+
+| Constant | Value | Use case |
+|---|---|---|
+| `KeyTypeJWTSecret` | `jwt_secret` | Per-user JWT signing secret |
+| `KeyTypeHeaderAPI` | `header_api` | Static API key sent in a request header |
+| `KeyTypeOAuth2` | `oauth2` | OAuth2 client credentials |
+| `KeyTypeGenericAPI` | `api` | General-purpose application key |
+
+## Storage backends
+
+### ConfigKeyStore
+
+In-memory store seeded from a static list. Suitable for a small, fixed set of service-account keys loaded from a config file. Keys created at runtime via `CreateKey` are held in memory and lost on restart.
+
+```go
+// Pre-load keys from config (KeyHash = SHA-256 hex of the raw key)
+store := security.NewConfigKeyStore([]security.UserKey{
+    {
+        UserID:  1,
+        KeyType: security.KeyTypeGenericAPI,
+        KeyHash: "e3b0c44298fc1c149afb...", // sha256(rawKey)
+        Name:    "CI deploy",
+        Scopes:  []string{"deploy"},
+        IsActive: true,
+    },
+})
+```
+
+### DatabaseKeyStore
+
+Backed by PostgreSQL stored procedures. Supports optional caching (default 2-minute TTL). Apply `keystore_schema.sql` before use.
+
+```go
+db, _ := sql.Open("postgres", dsn)
+
+store := security.NewDatabaseKeyStore(db)
+
+// With options
+store = security.NewDatabaseKeyStore(db, security.DatabaseKeyStoreOptions{
+    CacheTTL: 5 * time.Minute,
+    SQLNames: &security.KeyStoreSQLNames{
+        ValidateKey: "myapp_keystore_validate", // override one procedure name
+    },
+})
+```
+
+## Managing keys
+
+```go
+ctx := context.Background()
+
+// Create — raw key returned once; store it securely
+resp, err := store.CreateKey(ctx, security.CreateKeyRequest{
+    UserID:  42,
+    KeyType: security.KeyTypeGenericAPI,
+    Name:    "mobile app",
+    Scopes:  []string{"read", "write"},
+})
+fmt.Println(resp.RawKey) // only shown here; hashed internally
+
+// List
+keys, err := store.GetUserKeys(ctx, 42, "") // "" = all types
+keys, err  = store.GetUserKeys(ctx, 42, security.KeyTypeGenericAPI)
+
+// Revoke
+err = store.DeleteKey(ctx, 42, resp.Key.ID)
+
+// Validate (used by authenticators internally)
+key, err := store.ValidateKey(ctx, rawKey, "")
+```
+
+## HTTP authentication
+
+`KeyStoreAuthenticator` wraps any `KeyStore` and implements the `Authenticator` interface. It is drop-in compatible with `DatabaseAuthenticator` and works in `CompositeSecurityProvider`.
+
+Keys are extracted from the request in this order:
+
+1. `Authorization: Bearer <key>`
+2. `Authorization: ApiKey <key>`
+3. `X-API-Key: <key>`
+
+```go
+auth := security.NewKeyStoreAuthenticator(store, "") // "" = accept any key type
+// Restrict to a specific type:
+auth = security.NewKeyStoreAuthenticator(store, security.KeyTypeGenericAPI)
+```
+
+Plug it into a handler:
+
+```go
+handler := resolvespec.NewHandler(db, registry,
+    resolvespec.WithAuthenticator(auth),
+)
+```
+
+`Login` and `Logout` return an error — key lifecycle is managed through `KeyStore` directly.
+
+On successful validation the request context receives a `UserContext` where:
+
+- `UserID` — from the key
+- `Roles` — the key's `Scopes`
+- `Claims["key_type"]` — key type string
+- `Claims["key_name"]` — key name
+
+## Database setup
+
+Apply `keystore_schema.sql` to your PostgreSQL database. It requires the `users` table from the main `database_schema.sql`.
+
+```sql
+\i pkg/security/keystore_schema.sql
+```
+
+This creates:
+
+- `user_keys` table with indexes on `user_id`, `key_hash`, and `key_type`
+- `resolvespec_keystore_get_user_keys(p_user_id, p_key_type)`
+- `resolvespec_keystore_create_key(p_request jsonb)`
+- `resolvespec_keystore_delete_key(p_user_id, p_key_id)`
+- `resolvespec_keystore_validate_key(p_key_hash, p_key_type)`
+
+### Custom procedure names
+
+```go
+store := security.NewDatabaseKeyStore(db, security.DatabaseKeyStoreOptions{
+    SQLNames: &security.KeyStoreSQLNames{
+        GetUserKeys: "myschema_get_keys",
+        CreateKey:   "myschema_create_key",
+        DeleteKey:   "myschema_delete_key",
+        ValidateKey: "myschema_validate_key",
+    },
+})
+
+// Validate names at startup
+names := &security.KeyStoreSQLNames{
+    GetUserKeys: "myschema_get_keys",
+    // ...
+}
+if err := security.ValidateKeyStoreSQLNames(names); err != nil {
+    log.Fatal(err)
+}
+```
+
+## Security notes
+
+- Raw keys are never stored. Only the SHA-256 hex digest is persisted.
+- The raw key is generated with `crypto/rand` (32 bytes, base64url-encoded) and returned exactly once in `CreateKeyResponse.RawKey`.
+- Hash comparisons in `ConfigKeyStore` use `crypto/subtle.ConstantTimeCompare` to prevent timing side-channels.
+- `DeleteKey` performs a soft delete (`is_active = false`). The `DatabaseKeyStore` invalidates the cache entry immediately, but due to the cache TTL a revoked key may authenticate for up to `CacheTTL` (default 2 minutes) in a distributed environment. Set `CacheTTL: 0` to disable caching if immediate revocation is required.

pkg/security/README.md

@@ -12,6 +12,7 @@ Type-safe, composable security system for ResolveSpec with support for authentic
 - ✅ **Testable** - Easy to mock and test
 - ✅ **Extensible** - Implement custom providers for your needs
 - ✅ **Stored Procedures** - All database operations use PostgreSQL stored procedures for security and maintainability
+- ✅ **OAuth2 Authorization Server** - Built-in OAuth 2.1 + PKCE server (RFC 8414, 7591, 7009, 7662) with login form and external provider federation
 
 ## Stored Procedure Architecture
 
@@ -38,6 +39,12 @@ Type-safe, composable security system for ResolveSpec with support for authentic
 | `resolvespec_jwt_logout` | JWT token blacklist | JWTAuthenticator |
 | `resolvespec_column_security` | Load column rules | DatabaseColumnSecurityProvider |
 | `resolvespec_row_security` | Load row templates | DatabaseRowSecurityProvider |
+| `resolvespec_oauth_register_client` | Persist OAuth2 client (RFC 7591) | OAuthServer / DatabaseAuthenticator |
+| `resolvespec_oauth_get_client` | Retrieve OAuth2 client by ID | OAuthServer / DatabaseAuthenticator |
+| `resolvespec_oauth_save_code` | Persist authorization code | OAuthServer / DatabaseAuthenticator |
+| `resolvespec_oauth_exchange_code` | Consume authorization code (single-use) | OAuthServer / DatabaseAuthenticator |
+| `resolvespec_oauth_introspect` | Token introspection (RFC 7662) | OAuthServer / DatabaseAuthenticator |
+| `resolvespec_oauth_revoke` | Token revocation (RFC 7009) | OAuthServer / DatabaseAuthenticator |
 
 See `database_schema.sql` for complete stored procedure definitions and examples.
 
@@ -897,6 +904,156 @@ securityList := security.NewSecurityList(provider)
 restheadspec.RegisterSecurityHooks(handler, securityList) // or funcspec/resolvespec
 ```
 
+## OAuth2 Authorization Server
+
+`OAuthServer` is a generic OAuth 2.1 + PKCE authorization server. It is not tied to any spec — `pkg/resolvemcp` uses it, but it can be used standalone with any `http.ServeMux`.
+
+### Endpoints
+
+| Method | Path | RFC |
+|--------|------|-----|
+| `GET` | `/.well-known/oauth-authorization-server` | RFC 8414 — server metadata |
+| `POST` | `/oauth/register` | RFC 7591 — dynamic client registration |
+| `GET` | `/oauth/authorize` | OAuth 2.1 — start authorization / provider selection |
+| `POST` | `/oauth/authorize` | OAuth 2.1 — login form submission |
+| `POST` | `/oauth/token` | OAuth 2.1 — code exchange + refresh |
+| `POST` | `/oauth/revoke` | RFC 7009 — token revocation |
+| `POST` | `/oauth/introspect` | RFC 7662 — token introspection |
+| `GET` | `{ProviderCallbackPath}` | External provider redirect target |
+
+### Config
+
+```go
+cfg := security.OAuthServerConfig{
+    Issuer:               "https://example.com",      // Required — token issuer URL
+    ProviderCallbackPath: "/oauth/provider/callback", // External provider redirect target
+    LoginTitle:           "My App Login",             // HTML login page title
+    PersistClients:       true,  // Store clients in DB (multi-instance safe)
+    PersistCodes:         true,  // Store codes in DB (multi-instance safe)
+    DefaultScopes:        []string{"openid", "profile"}, // Returned when no scope requested
+    AccessTokenTTL:       time.Hour,
+    AuthCodeTTL:          5 * time.Minute,
+}
+```
+
+| Field | Default | Notes |
+|-------|---------|-------|
+| `Issuer` | — | Required; trailing slash is trimmed automatically |
+| `ProviderCallbackPath` | `/oauth/provider/callback` | |
+| `LoginTitle` | `"Sign in"` | |
+| `PersistClients` | `false` | Set `true` for multi-instance |
+| `PersistCodes` | `false` | Set `true` for multi-instance; does not require `PersistClients` |
+| `DefaultScopes` | `["openid","profile","email"]` | |
+| `AccessTokenTTL` | `24h` | Also used as `expires_in` in token responses |
+| `AuthCodeTTL` | `2m` | |
+
+### Operating Modes
+
+**Mode 1 — Direct login (username/password form)**
+
+Pass a `*DatabaseAuthenticator` to `NewOAuthServer`. The server renders a login form at `GET /oauth/authorize` and issues tokens via the stored session after login.
+
+```go
+auth := security.NewDatabaseAuthenticator(db)
+srv := security.NewOAuthServer(cfg, auth)
+```
+
+**Mode 2 — External provider federation**
+
+Pass a `*DatabaseAuthenticator` for persistence (authorization codes, revoke, introspect) and register external providers. The authorize endpoint redirects to the specified provider (via the `provider` query param) or to the first registered provider by default.
+
+```go
+auth := security.NewDatabaseAuthenticator(db)
+srv := security.NewOAuthServer(cfg, auth)
+srv.RegisterExternalProvider(googleAuth, "google")
+srv.RegisterExternalProvider(githubAuth, "github")
+```
+
+**Mode 3 — Both**
+
+Pass auth for the login form and also register external providers. The authorize page shows both a login form and provider buttons.
+
+```go
+srv := security.NewOAuthServer(cfg, auth)
+srv.RegisterExternalProvider(googleAuth, "google")
+```
+
+### Standalone Usage
+
+```go
+mux := http.NewServeMux()
+mux.Handle("/.well-known/", srv.HTTPHandler())
+mux.Handle("/oauth/", srv.HTTPHandler())
+mux.Handle(cfg.ProviderCallbackPath, srv.HTTPHandler())
+
+http.ListenAndServe(":8080", mux)
+```
+
+### DB Persistence
+
+When `PersistClients: true` or `PersistCodes: true`, the server calls the corresponding `DatabaseAuthenticator` methods. Both flags default to `false` (in-memory maps). Enable both for multi-instance deployments.
+
+Requires `oauth_clients` and `oauth_codes` tables + 6 stored procedures from `database_schema.sql`.
+
+#### New DB Types
+
+```go
+type OAuthServerClient struct {
+    ClientID      string   `json:"client_id"`
+    RedirectURIs  []string `json:"redirect_uris"`
+    ClientName    string   `json:"client_name,omitempty"`
+    GrantTypes    []string `json:"grant_types"`
+    AllowedScopes []string `json:"allowed_scopes,omitempty"`
+}
+
+type OAuthCode struct {
+    Code                string    `json:"code"`
+    ClientID            string    `json:"client_id"`
+    RedirectURI         string    `json:"redirect_uri"`
+    ClientState         string    `json:"client_state,omitempty"`
+    CodeChallenge       string    `json:"code_challenge"`
+    CodeChallengeMethod string    `json:"code_challenge_method"`
+    SessionToken        string    `json:"session_token"`
+    Scopes              []string  `json:"scopes,omitempty"`
+    ExpiresAt           time.Time `json:"expires_at"`
+}
+
+type OAuthTokenInfo struct {
+    Active   bool     `json:"active"`
+    Sub      string   `json:"sub,omitempty"`
+    Username string   `json:"username,omitempty"`
+    Email    string   `json:"email,omitempty"`
+    Roles    []string `json:"roles,omitempty"`
+    Exp      int64    `json:"exp,omitempty"`
+    Iat      int64    `json:"iat,omitempty"`
+}
+```
+
+#### DatabaseAuthenticator OAuth Methods
+
+```go
+auth.OAuthRegisterClient(ctx, client)  // RFC 7591 — persist client
+auth.OAuthGetClient(ctx, clientID)     // retrieve client
+auth.OAuthSaveCode(ctx, code)          // persist authorization code
+auth.OAuthExchangeCode(ctx, code)      // consume code (single-use, deletes on read)
+auth.OAuthIntrospectToken(ctx, token)  // RFC 7662 — returns OAuthTokenInfo
+auth.OAuthRevokeToken(ctx, token)      // RFC 7009 — revoke session
+```
+
+#### SQLNames Fields
+
+```go
+type SQLNames struct {
+    // ... existing fields ...
+    OAuthRegisterClient string // default: "resolvespec_oauth_register_client"
+    OAuthGetClient      string // default: "resolvespec_oauth_get_client"
+    OAuthSaveCode       string // default: "resolvespec_oauth_save_code"
+    OAuthExchangeCode   string // default: "resolvespec_oauth_exchange_code"
+    OAuthIntrospect     string // default: "resolvespec_oauth_introspect"
+    OAuthRevoke         string // default: "resolvespec_oauth_revoke"
+}
+```
+
 The main changes:
 1. Security package no longer knows about specific spec types
 2. Each spec registers its own security hooks

pkg/security/database_schema.sql

@@ -1397,3 +1397,180 @@ $$ LANGUAGE plpgsql;
 
 -- Get credentials by username
 -- SELECT * FROM resolvespec_passkey_get_credentials_by_username('admin');
+
+-- ============================================
+-- OAuth2 Server Tables (OAuthServer persistence)
+-- ============================================
+
+-- oauth_clients: persistent RFC 7591 registered clients
+CREATE TABLE IF NOT EXISTS oauth_clients (
+    id SERIAL PRIMARY KEY,
+    client_id VARCHAR(255) NOT NULL UNIQUE,
+    redirect_uris TEXT[] NOT NULL,
+    client_name VARCHAR(255),
+    grant_types TEXT[] DEFAULT ARRAY['authorization_code'],
+    allowed_scopes TEXT[] DEFAULT ARRAY['openid','profile','email'],
+    is_active BOOLEAN DEFAULT true,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+
+-- oauth_codes: short-lived authorization codes (for multi-instance deployments)
+-- Note: client_id is stored without a foreign key so codes can be persisted even
+-- when OAuth clients are managed in memory rather than persisted in oauth_clients.
+CREATE TABLE IF NOT EXISTS oauth_codes (
+    id SERIAL PRIMARY KEY,
+    code VARCHAR(255) NOT NULL UNIQUE,
+    client_id VARCHAR(255) NOT NULL,
+    redirect_uri TEXT NOT NULL,
+    client_state TEXT,
+    code_challenge VARCHAR(255) NOT NULL,
+    code_challenge_method VARCHAR(10) DEFAULT 'S256',
+    session_token TEXT NOT NULL,
+    refresh_token TEXT,
+    scopes TEXT[],
+    expires_at TIMESTAMP NOT NULL,
+    created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP
+);
+CREATE INDEX IF NOT EXISTS idx_oauth_codes_code ON oauth_codes(code);
+CREATE INDEX IF NOT EXISTS idx_oauth_codes_expires ON oauth_codes(expires_at);
+
+-- ============================================
+-- OAuth2 Server Stored Procedures
+-- ============================================
+
+CREATE OR REPLACE FUNCTION resolvespec_oauth_register_client(p_data jsonb)
+RETURNS TABLE(p_success bool, p_error text, p_data jsonb)
+LANGUAGE plpgsql AS $$
+DECLARE
+    v_client_id   text;
+    v_row         jsonb;
+BEGIN
+    v_client_id := p_data->>'client_id';
+
+    INSERT INTO oauth_clients (client_id, redirect_uris, client_name, grant_types, allowed_scopes)
+    VALUES (
+        v_client_id,
+        ARRAY(SELECT jsonb_array_elements_text(p_data->'redirect_uris')),
+        p_data->>'client_name',
+        COALESCE(ARRAY(SELECT jsonb_array_elements_text(p_data->'grant_types')), ARRAY['authorization_code']),
+        COALESCE(ARRAY(SELECT jsonb_array_elements_text(p_data->'allowed_scopes')), ARRAY['openid','profile','email'])
+    )
+    RETURNING to_jsonb(oauth_clients.*) INTO v_row;
+
+    RETURN QUERY SELECT true, null::text, v_row;
+EXCEPTION WHEN OTHERS THEN
+    RETURN QUERY SELECT false, SQLERRM, null::jsonb;
+END;
+$$;
+
+CREATE OR REPLACE FUNCTION resolvespec_oauth_get_client(p_client_id text)
+RETURNS TABLE(p_success bool, p_error text, p_data jsonb)
+LANGUAGE plpgsql AS $$
+DECLARE
+    v_row jsonb;
+BEGIN
+    SELECT to_jsonb(oauth_clients.*)
+    INTO v_row
+    FROM oauth_clients
+    WHERE client_id = p_client_id AND is_active = true;
+
+    IF v_row IS NULL THEN
+        RETURN QUERY SELECT false, 'client not found'::text, null::jsonb;
+    ELSE
+        RETURN QUERY SELECT true, null::text, v_row;
+    END IF;
+END;
+$$;
+
+CREATE OR REPLACE FUNCTION resolvespec_oauth_save_code(p_data jsonb)
+RETURNS TABLE(p_success bool, p_error text)
+LANGUAGE plpgsql AS $$
+BEGIN
+    INSERT INTO oauth_codes (code, client_id, redirect_uri, client_state, code_challenge, code_challenge_method, session_token, refresh_token, scopes, expires_at)
+    VALUES (
+        p_data->>'code',
+        p_data->>'client_id',
+        p_data->>'redirect_uri',
+        p_data->>'client_state',
+        p_data->>'code_challenge',
+        COALESCE(p_data->>'code_challenge_method', 'S256'),
+        p_data->>'session_token',
+        p_data->>'refresh_token',
+        ARRAY(SELECT jsonb_array_elements_text(p_data->'scopes')),
+        (p_data->>'expires_at')::timestamp
+    );
+
+    RETURN QUERY SELECT true, null::text;
+EXCEPTION WHEN OTHERS THEN
+    RETURN QUERY SELECT false, SQLERRM;
+END;
+$$;
+
+CREATE OR REPLACE FUNCTION resolvespec_oauth_exchange_code(p_code text)
+RETURNS TABLE(p_success bool, p_error text, p_data jsonb)
+LANGUAGE plpgsql AS $$
+DECLARE
+    v_row jsonb;
+BEGIN
+    DELETE FROM oauth_codes
+    WHERE code = p_code AND expires_at > now()
+    RETURNING jsonb_build_object(
+        'client_id',             client_id,
+        'redirect_uri',          redirect_uri,
+        'client_state',          client_state,
+        'code_challenge',        code_challenge,
+        'code_challenge_method', code_challenge_method,
+        'session_token',         session_token,
+        'refresh_token',         refresh_token,
+        'scopes',                to_jsonb(scopes)
+    ) INTO v_row;
+
+    IF v_row IS NULL THEN
+        RETURN QUERY SELECT false, 'invalid or expired code'::text, null::jsonb;
+    ELSE
+        RETURN QUERY SELECT true, null::text, v_row;
+    END IF;
+END;
+$$;
+
+CREATE OR REPLACE FUNCTION resolvespec_oauth_introspect(p_token text)
+RETURNS TABLE(p_success bool, p_error text, p_data jsonb)
+LANGUAGE plpgsql AS $$
+DECLARE
+    v_row jsonb;
+BEGIN
+    SELECT jsonb_build_object(
+        'active',     true,
+        'sub',        u.id::text,
+        'username',   u.username,
+        'email',      u.email,
+        'user_level', u.user_level,
+        -- NULLIF converts empty string to NULL; string_to_array(NULL) returns NULL;
+        -- to_jsonb(NULL) returns NULL; COALESCE then returns '[]' for NULL/empty roles.
+        'roles',      COALESCE(to_jsonb(string_to_array(NULLIF(u.roles, ''), ',')), '[]'::jsonb),
+        'exp',        EXTRACT(EPOCH FROM s.expires_at)::bigint,
+        'iat',        EXTRACT(EPOCH FROM s.created_at)::bigint
+    )
+    INTO v_row
+    FROM user_sessions s
+    JOIN users u ON u.id = s.user_id
+    WHERE s.session_token = p_token
+      AND s.expires_at > now()
+      AND u.is_active = true;
+
+    IF v_row IS NULL THEN
+        RETURN QUERY SELECT true, null::text, '{"active":false}'::jsonb;
+    ELSE
+        RETURN QUERY SELECT true, null::text, v_row;
+    END IF;
+END;
+$$;
+
+CREATE OR REPLACE FUNCTION resolvespec_oauth_revoke(p_token text)
+RETURNS TABLE(p_success bool, p_error text)
+LANGUAGE plpgsql AS $$
+BEGIN
+    DELETE FROM user_sessions WHERE session_token = p_token;
+    RETURN QUERY SELECT true, null::text;
+END;
+$$;

pkg/security/keystore.go

@@ -0,0 +1,81 @@
+package security
+
+import (
+	"context"
+	"crypto/sha256"
+	"encoding/hex"
+	"time"
+)
+
+// hashSHA256Hex returns the lowercase hex SHA-256 digest of the given string.
+// Used by all keystore implementations to hash raw keys before storage or lookup.
+func hashSHA256Hex(raw string) string {
+	sum := sha256.Sum256([]byte(raw))
+	return hex.EncodeToString(sum[:])
+}
+
+// KeyType identifies the category of an auth key.
+type KeyType string
+
+const (
+	// KeyTypeJWTSecret is a per-user JWT signing secret for token generation.
+	KeyTypeJWTSecret KeyType = "jwt_secret"
+	// KeyTypeHeaderAPI is a static API key sent via a request header.
+	KeyTypeHeaderAPI KeyType = "header_api"
+	// KeyTypeOAuth2 holds OAuth2 client credentials (client_id / client_secret).
+	KeyTypeOAuth2 KeyType = "oauth2"
+	// KeyTypeGenericAPI is a generic application API key.
+	KeyTypeGenericAPI KeyType = "api"
+)
+
+// UserKey represents a single named auth key belonging to a user.
+// KeyHash stores the SHA-256 hex digest of the raw key; the raw key is never persisted.
+type UserKey struct {
+	ID         int64          `json:"id"`
+	UserID     int            `json:"user_id"`
+	KeyType    KeyType        `json:"key_type"`
+	KeyHash    string         `json:"key_hash"` // SHA-256 hex; never the raw key
+	Name       string         `json:"name"`
+	Scopes     []string       `json:"scopes,omitempty"`
+	Meta       map[string]any `json:"meta,omitempty"`
+	ExpiresAt  *time.Time     `json:"expires_at,omitempty"`
+	CreatedAt  time.Time      `json:"created_at"`
+	LastUsedAt *time.Time     `json:"last_used_at,omitempty"`
+	IsActive   bool           `json:"is_active"`
+}
+
+// CreateKeyRequest specifies the parameters for a new key.
+type CreateKeyRequest struct {
+	UserID    int
+	KeyType   KeyType
+	Name      string
+	Scopes    []string
+	Meta      map[string]any
+	ExpiresAt *time.Time
+}
+
+// CreateKeyResponse is returned exactly once when a key is created.
+// The caller is responsible for persisting RawKey; it is not stored anywhere.
+type CreateKeyResponse struct {
+	Key    UserKey
+	RawKey string // crypto/rand 32 bytes, base64url-encoded
+}
+
+// KeyStore manages per-user auth keys with pluggable storage backends.
+// Implementations: ConfigKeyStore (static list) and DatabaseKeyStore (stored procedures).
+type KeyStore interface {
+	// CreateKey generates a new key, stores its hash, and returns the raw key once.
+	CreateKey(ctx context.Context, req CreateKeyRequest) (*CreateKeyResponse, error)
+
+	// GetUserKeys returns all active, non-expired keys for a user.
+	// Pass an empty KeyType to return all types.
+	GetUserKeys(ctx context.Context, userID int, keyType KeyType) ([]UserKey, error)
+
+	// DeleteKey soft-deletes a key by ID after verifying ownership.
+	DeleteKey(ctx context.Context, userID int, keyID int64) error
+
+	// ValidateKey checks a raw key, returns the matching UserKey on success.
+	// The implementation hashes the raw key before any lookup.
+	// Pass an empty KeyType to accept any type.
+	ValidateKey(ctx context.Context, rawKey string, keyType KeyType) (*UserKey, error)
+}

pkg/security/keystore_authenticator.go

@@ -0,0 +1,97 @@
+package security
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"strings"
+)
+
+// KeyStoreAuthenticator implements the Authenticator interface using a KeyStore.
+// It is suitable for long-lived application credentials (API keys, JWT secrets, etc.)
+// rather than interactive sessions. Login and Logout are not supported — key lifecycle
+// is managed directly through the KeyStore.
+//
+// Key extraction order:
+//  1. Authorization: Bearer <key>
+//  2. Authorization: ApiKey <key>
+//  3. X-API-Key header
+type KeyStoreAuthenticator struct {
+	keyStore KeyStore
+	keyType  KeyType // empty = accept any type
+}
+
+// NewKeyStoreAuthenticator creates a KeyStoreAuthenticator.
+// Pass an empty keyType to accept keys of any type.
+func NewKeyStoreAuthenticator(ks KeyStore, keyType KeyType) *KeyStoreAuthenticator {
+	return &KeyStoreAuthenticator{keyStore: ks, keyType: keyType}
+}
+
+// Login is not supported for keystore authentication.
+func (a *KeyStoreAuthenticator) Login(_ context.Context, _ LoginRequest) (*LoginResponse, error) {
+	return nil, fmt.Errorf("keystore authenticator does not support login")
+}
+
+// Logout is not supported for keystore authentication.
+func (a *KeyStoreAuthenticator) Logout(_ context.Context, _ LogoutRequest) error {
+	return nil
+}
+
+// Authenticate extracts an API key from the request and validates it against the KeyStore.
+// Returns a UserContext built from the matching UserKey on success.
+func (a *KeyStoreAuthenticator) Authenticate(r *http.Request) (*UserContext, error) {
+	rawKey := extractAPIKey(r)
+	if rawKey == "" {
+		return nil, fmt.Errorf("API key required (Authorization: Bearer/ApiKey <key> or X-API-Key header)")
+	}
+
+	userKey, err := a.keyStore.ValidateKey(r.Context(), rawKey, a.keyType)
+	if err != nil {
+		return nil, fmt.Errorf("invalid API key: %w", err)
+	}
+
+	return userKeyToUserContext(userKey), nil
+}
+
+// extractAPIKey extracts a raw key from the request using the following precedence:
+//  1. Authorization: Bearer <key>
+//  2. Authorization: ApiKey <key>
+//  3. X-API-Key header
+func extractAPIKey(r *http.Request) string {
+	if auth := r.Header.Get("Authorization"); auth != "" {
+		if after, ok := strings.CutPrefix(auth, "Bearer "); ok {
+			return strings.TrimSpace(after)
+		}
+		if after, ok := strings.CutPrefix(auth, "ApiKey "); ok {
+			return strings.TrimSpace(after)
+		}
+	}
+	return strings.TrimSpace(r.Header.Get("X-API-Key"))
+}
+
+// userKeyToUserContext converts a UserKey into a UserContext.
+// Scopes are mapped to Roles. Key type and name are stored in Claims.
+func userKeyToUserContext(k *UserKey) *UserContext {
+	claims := map[string]any{
+		"key_type": string(k.KeyType),
+		"key_name": k.Name,
+	}
+
+	meta := k.Meta
+	if meta == nil {
+		meta = map[string]any{}
+	}
+
+	roles := k.Scopes
+	if roles == nil {
+		roles = []string{}
+	}
+
+	return &UserContext{
+		UserID:    k.UserID,
+		SessionID: fmt.Sprintf("key:%d", k.ID),
+		Roles:     roles,
+		Claims:    claims,
+		Meta:      meta,
+	}
+}

pkg/security/keystore_config.go

@@ -0,0 +1,149 @@
+package security
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/subtle"
+	"encoding/base64"
+	"encoding/hex"
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+// ConfigKeyStore is an in-memory keystore backed by a static slice of UserKey values.
+// It is designed for config-file driven setups (e.g. service accounts defined in YAML)
+// with a small, bounded number of keys. For large or dynamic key sets use DatabaseKeyStore.
+//
+// Pre-existing entries must have KeyHash set to the SHA-256 hex of the intended raw key.
+// Keys created at runtime via CreateKey are held in memory only and lost on restart.
+type ConfigKeyStore struct {
+	mu   sync.RWMutex
+	keys []UserKey
+	next int64 // monotonic ID counter for runtime-created keys (atomic)
+}
+
+// NewConfigKeyStore creates a ConfigKeyStore seeded with the provided keys.
+// Pass nil or an empty slice to start with no pre-loaded keys.
+// Zero-value entries (CreatedAt is zero) are treated as active and assigned the current time.
+func NewConfigKeyStore(keys []UserKey) *ConfigKeyStore {
+	var maxID int64
+	copied := make([]UserKey, len(keys))
+	copy(copied, keys)
+	for i := range copied {
+		if copied[i].CreatedAt.IsZero() {
+			copied[i].IsActive = true
+			copied[i].CreatedAt = time.Now()
+		}
+		if copied[i].ID > maxID {
+			maxID = copied[i].ID
+		}
+	}
+	return &ConfigKeyStore{keys: copied, next: maxID}
+}
+
+// CreateKey generates a new raw key, stores its SHA-256 hash, and returns the raw key once.
+func (s *ConfigKeyStore) CreateKey(_ context.Context, req CreateKeyRequest) (*CreateKeyResponse, error) {
+	rawBytes := make([]byte, 32)
+	if _, err := rand.Read(rawBytes); err != nil {
+		return nil, fmt.Errorf("failed to generate key material: %w", err)
+	}
+	rawKey := base64.RawURLEncoding.EncodeToString(rawBytes)
+	hash := hashSHA256Hex(rawKey)
+
+	id := atomic.AddInt64(&s.next, 1)
+	key := UserKey{
+		ID:        id,
+		UserID:    req.UserID,
+		KeyType:   req.KeyType,
+		KeyHash:   hash,
+		Name:      req.Name,
+		Scopes:    req.Scopes,
+		Meta:      req.Meta,
+		ExpiresAt: req.ExpiresAt,
+		CreatedAt: time.Now(),
+		IsActive:  true,
+	}
+
+	s.mu.Lock()
+	s.keys = append(s.keys, key)
+	s.mu.Unlock()
+
+	return &CreateKeyResponse{Key: key, RawKey: rawKey}, nil
+}
+
+// GetUserKeys returns all active, non-expired keys for the given user.
+// Pass an empty KeyType to return all types.
+func (s *ConfigKeyStore) GetUserKeys(_ context.Context, userID int, keyType KeyType) ([]UserKey, error) {
+	now := time.Now()
+	s.mu.RLock()
+	defer s.mu.RUnlock()
+
+	var result []UserKey
+	for i := range s.keys {
+		k := &s.keys[i]
+		if k.UserID != userID || !k.IsActive {
+			continue
+		}
+		if k.ExpiresAt != nil && k.ExpiresAt.Before(now) {
+			continue
+		}
+		if keyType != "" && k.KeyType != keyType {
+			continue
+		}
+		result = append(result, *k)
+	}
+	return result, nil
+}
+
+// DeleteKey soft-deletes a key by setting IsActive to false after ownership verification.
+func (s *ConfigKeyStore) DeleteKey(_ context.Context, userID int, keyID int64) error {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	for i := range s.keys {
+		if s.keys[i].ID == keyID {
+			if s.keys[i].UserID != userID {
+				return fmt.Errorf("key not found or permission denied")
+			}
+			s.keys[i].IsActive = false
+			return nil
+		}
+	}
+	return fmt.Errorf("key not found")
+}
+
+// ValidateKey hashes the raw key and finds a matching, active, non-expired entry.
+// Uses constant-time comparison to prevent timing side-channels.
+// Pass an empty KeyType to accept any type.
+func (s *ConfigKeyStore) ValidateKey(_ context.Context, rawKey string, keyType KeyType) (*UserKey, error) {
+	hash := hashSHA256Hex(rawKey)
+	hashBytes, _ := hex.DecodeString(hash)
+	now := time.Now()
+
+	// Write lock: ValidateKey updates LastUsedAt on the matched entry.
+	s.mu.Lock()
+	defer s.mu.Unlock()
+
+	for i := range s.keys {
+		k := &s.keys[i]
+		if !k.IsActive {
+			continue
+		}
+		if k.ExpiresAt != nil && k.ExpiresAt.Before(now) {
+			continue
+		}
+		if keyType != "" && k.KeyType != keyType {
+			continue
+		}
+		stored, _ := hex.DecodeString(k.KeyHash)
+		if subtle.ConstantTimeCompare(hashBytes, stored) != 1 {
+			continue
+		}
+		k.LastUsedAt = &now
+		result := *k
+		return &result, nil
+	}
+	return nil, fmt.Errorf("invalid or expired key")
+}

pkg/security/keystore_database.go

@@ -0,0 +1,256 @@
+package security
+
+import (
+	"context"
+	"crypto/rand"
+	"database/sql"
+	"encoding/base64"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/bitechdev/ResolveSpec/pkg/cache"
+)
+
+// DatabaseKeyStoreOptions configures DatabaseKeyStore.
+type DatabaseKeyStoreOptions struct {
+	// Cache is an optional cache instance. If nil, uses the default cache.
+	Cache *cache.Cache
+	// CacheTTL is the duration to cache ValidateKey results.
+	// Default: 2 minutes.
+	CacheTTL time.Duration
+	// SQLNames provides custom procedure names. If nil, uses DefaultKeyStoreSQLNames().
+	SQLNames *KeyStoreSQLNames
+	// DBFactory is called to obtain a fresh *sql.DB when the existing connection is closed.
+	// If nil, reconnection is disabled.
+	DBFactory func() (*sql.DB, error)
+}
+
+// DatabaseKeyStore is a KeyStore backed by PostgreSQL stored procedures.
+// All DB operations go through configurable procedure names; the raw key is
+// never passed to the database.
+//
+// See keystore_schema.sql for the required table and procedure definitions.
+//
+// Note: DeleteKey invalidates the cache entry for the deleted key. Due to the
+// cache TTL, a deleted key may continue to authenticate for up to CacheTTL
+// (default 2 minutes) if the cache entry cannot be invalidated.
+type DatabaseKeyStore struct {
+	db        *sql.DB
+	dbMu      sync.RWMutex
+	dbFactory func() (*sql.DB, error)
+	sqlNames  *KeyStoreSQLNames
+	cache     *cache.Cache
+	cacheTTL  time.Duration
+}
+
+// NewDatabaseKeyStore creates a DatabaseKeyStore with optional configuration.
+func NewDatabaseKeyStore(db *sql.DB, opts ...DatabaseKeyStoreOptions) *DatabaseKeyStore {
+	o := DatabaseKeyStoreOptions{}
+	if len(opts) > 0 {
+		o = opts[0]
+	}
+	if o.CacheTTL == 0 {
+		o.CacheTTL = 2 * time.Minute
+	}
+	c := o.Cache
+	if c == nil {
+		c = cache.GetDefaultCache()
+	}
+	names := MergeKeyStoreSQLNames(DefaultKeyStoreSQLNames(), o.SQLNames)
+	return &DatabaseKeyStore{
+		db:        db,
+		dbFactory: o.DBFactory,
+		sqlNames:  names,
+		cache:     c,
+		cacheTTL:  o.CacheTTL,
+	}
+}
+
+func (ks *DatabaseKeyStore) getDB() *sql.DB {
+	ks.dbMu.RLock()
+	defer ks.dbMu.RUnlock()
+	return ks.db
+}
+
+func (ks *DatabaseKeyStore) reconnectDB() error {
+	if ks.dbFactory == nil {
+		return fmt.Errorf("no db factory configured for reconnect")
+	}
+	newDB, err := ks.dbFactory()
+	if err != nil {
+		return err
+	}
+	ks.dbMu.Lock()
+	ks.db = newDB
+	ks.dbMu.Unlock()
+	return nil
+}
+
+// CreateKey generates a raw key, stores its SHA-256 hash via the create procedure,
+// and returns the raw key once.
+func (ks *DatabaseKeyStore) CreateKey(ctx context.Context, req CreateKeyRequest) (*CreateKeyResponse, error) {
+	rawBytes := make([]byte, 32)
+	if _, err := rand.Read(rawBytes); err != nil {
+		return nil, fmt.Errorf("failed to generate key material: %w", err)
+	}
+	rawKey := base64.RawURLEncoding.EncodeToString(rawBytes)
+	hash := hashSHA256Hex(rawKey)
+
+	type createRequest struct {
+		UserID    int            `json:"user_id"`
+		KeyType   KeyType        `json:"key_type"`
+		KeyHash   string         `json:"key_hash"`
+		Name      string         `json:"name"`
+		Scopes    []string       `json:"scopes,omitempty"`
+		Meta      map[string]any `json:"meta,omitempty"`
+		ExpiresAt *time.Time     `json:"expires_at,omitempty"`
+	}
+
+	reqJSON, err := json.Marshal(createRequest{
+		UserID:    req.UserID,
+		KeyType:   req.KeyType,
+		KeyHash:   hash,
+		Name:      req.Name,
+		Scopes:    req.Scopes,
+		Meta:      req.Meta,
+		ExpiresAt: req.ExpiresAt,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal create key request: %w", err)
+	}
+
+	var success bool
+	var errorMsg sql.NullString
+	var keyJSON sql.NullString
+
+	query := fmt.Sprintf(`SELECT p_success, p_error, p_key::text FROM %s($1::jsonb)`, ks.sqlNames.CreateKey)
+	if err = ks.getDB().QueryRowContext(ctx, query, string(reqJSON)).Scan(&success, &errorMsg, &keyJSON); err != nil {
+		return nil, fmt.Errorf("create key procedure failed: %w", err)
+	}
+	if !success {
+		return nil, errors.New(nullStringOr(errorMsg, "create key failed"))
+	}
+
+	var key UserKey
+	if err = json.Unmarshal([]byte(keyJSON.String), &key); err != nil {
+		return nil, fmt.Errorf("failed to parse created key: %w", err)
+	}
+
+	return &CreateKeyResponse{Key: key, RawKey: rawKey}, nil
+}
+
+// GetUserKeys returns all active, non-expired keys for the given user.
+// Pass an empty KeyType to return all types.
+func (ks *DatabaseKeyStore) GetUserKeys(ctx context.Context, userID int, keyType KeyType) ([]UserKey, error) {
+	var success bool
+	var errorMsg sql.NullString
+	var keysJSON sql.NullString
+
+	query := fmt.Sprintf(`SELECT p_success, p_error, p_keys::text FROM %s($1, $2)`, ks.sqlNames.GetUserKeys)
+	if err := ks.getDB().QueryRowContext(ctx, query, userID, string(keyType)).Scan(&success, &errorMsg, &keysJSON); err != nil {
+		return nil, fmt.Errorf("get user keys procedure failed: %w", err)
+	}
+	if !success {
+		return nil, errors.New(nullStringOr(errorMsg, "get user keys failed"))
+	}
+
+	var keys []UserKey
+	if keysJSON.Valid && keysJSON.String != "" && keysJSON.String != "[]" {
+		if err := json.Unmarshal([]byte(keysJSON.String), &keys); err != nil {
+			return nil, fmt.Errorf("failed to parse user keys: %w", err)
+		}
+	}
+	if keys == nil {
+		keys = []UserKey{}
+	}
+	return keys, nil
+}
+
+// DeleteKey soft-deletes a key after verifying ownership and invalidates its cache entry.
+// The delete procedure returns the key_hash so no separate lookup is needed.
+// Note: cache invalidation is best-effort; a cached entry may persist for up to CacheTTL.
+func (ks *DatabaseKeyStore) DeleteKey(ctx context.Context, userID int, keyID int64) error {
+	var success bool
+	var errorMsg sql.NullString
+	var keyHash sql.NullString
+
+	query := fmt.Sprintf(`SELECT p_success, p_error, p_key_hash FROM %s($1, $2)`, ks.sqlNames.DeleteKey)
+	if err := ks.getDB().QueryRowContext(ctx, query, userID, keyID).Scan(&success, &errorMsg, &keyHash); err != nil {
+		return fmt.Errorf("delete key procedure failed: %w", err)
+	}
+	if !success {
+		return errors.New(nullStringOr(errorMsg, "delete key failed"))
+	}
+
+	if keyHash.Valid && keyHash.String != "" && ks.cache != nil {
+		_ = ks.cache.Delete(ctx, keystoreCacheKey(keyHash.String))
+	}
+	return nil
+}
+
+// ValidateKey hashes the raw key and calls the validate procedure.
+// Results are cached for CacheTTL to reduce DB load on hot paths.
+func (ks *DatabaseKeyStore) ValidateKey(ctx context.Context, rawKey string, keyType KeyType) (*UserKey, error) {
+	hash := hashSHA256Hex(rawKey)
+	cacheKey := keystoreCacheKey(hash)
+
+	if ks.cache != nil {
+		var cached UserKey
+		if err := ks.cache.Get(ctx, cacheKey, &cached); err == nil {
+			if cached.IsActive {
+				return &cached, nil
+			}
+			return nil, errors.New("invalid or expired key")
+		}
+	}
+
+	var success bool
+	var errorMsg sql.NullString
+	var keyJSON sql.NullString
+
+	runQuery := func() error {
+		query := fmt.Sprintf(`SELECT p_success, p_error, p_key::text FROM %s($1, $2)`, ks.sqlNames.ValidateKey)
+		return ks.getDB().QueryRowContext(ctx, query, hash, string(keyType)).Scan(&success, &errorMsg, &keyJSON)
+	}
+	if err := runQuery(); err != nil {
+		if isDBClosed(err) {
+			if reconnErr := ks.reconnectDB(); reconnErr == nil {
+				err = runQuery()
+			}
+			if err != nil {
+				return nil, fmt.Errorf("validate key procedure failed: %w", err)
+			}
+		} else {
+			return nil, fmt.Errorf("validate key procedure failed: %w", err)
+		}
+	}
+	if !success {
+		return nil, errors.New(nullStringOr(errorMsg, "invalid or expired key"))
+	}
+
+	var key UserKey
+	if err := json.Unmarshal([]byte(keyJSON.String), &key); err != nil {
+		return nil, fmt.Errorf("failed to parse validated key: %w", err)
+	}
+
+	if ks.cache != nil {
+		_ = ks.cache.Set(ctx, cacheKey, key, ks.cacheTTL)
+	}
+
+	return &key, nil
+}
+
+func keystoreCacheKey(hash string) string {
+	return "keystore:validate:" + hash
+}
+
+// nullStringOr returns s.String if valid, otherwise the fallback.
+func nullStringOr(s sql.NullString, fallback string) string {
+	if s.Valid && s.String != "" {
+		return s.String
+	}
+	return fallback
+}

pkg/security/keystore_schema.sql

@@ -0,0 +1,187 @@
+-- Keystore schema for per-user auth keys
+-- Apply alongside database_schema.sql (requires the users table)
+
+CREATE TABLE IF NOT EXISTS user_keys (
+    id           BIGSERIAL PRIMARY KEY,
+    user_id      INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    key_type     VARCHAR(50) NOT NULL,
+    key_hash     VARCHAR(64) NOT NULL UNIQUE,  -- SHA-256 hex digest (64 chars)
+    name         VARCHAR(255) NOT NULL DEFAULT '',
+    scopes       TEXT,                          -- JSON array, e.g. '["read","write"]'
+    meta         JSONB,
+    expires_at   TIMESTAMP,
+    created_at   TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
+    last_used_at TIMESTAMP,
+    is_active    BOOLEAN DEFAULT true
+);
+
+CREATE INDEX IF NOT EXISTS idx_user_keys_user_id  ON user_keys(user_id);
+CREATE INDEX IF NOT EXISTS idx_user_keys_key_hash ON user_keys(key_hash);
+CREATE INDEX IF NOT EXISTS idx_user_keys_key_type ON user_keys(key_type);
+
+-- resolvespec_keystore_get_user_keys
+-- Returns all active, non-expired keys for a user.
+-- Pass empty p_key_type to return all key types.
+CREATE OR REPLACE FUNCTION resolvespec_keystore_get_user_keys(
+    p_user_id  INTEGER,
+    p_key_type TEXT DEFAULT ''
+)
+RETURNS TABLE(p_success BOOLEAN, p_error TEXT, p_keys JSONB)
+LANGUAGE plpgsql AS $$
+DECLARE
+    v_keys JSONB;
+BEGIN
+    SELECT COALESCE(
+        jsonb_agg(
+            jsonb_build_object(
+                'id',           k.id,
+                'user_id',      k.user_id,
+                'key_type',     k.key_type,
+                'name',         k.name,
+                'scopes',       CASE WHEN k.scopes IS NOT NULL THEN k.scopes::jsonb ELSE '[]'::jsonb END,
+                'meta',         COALESCE(k.meta, '{}'::jsonb),
+                'expires_at',   k.expires_at,
+                'created_at',   k.created_at,
+                'last_used_at', k.last_used_at,
+                'is_active',    k.is_active
+            )
+        ),
+        '[]'::jsonb
+    )
+    INTO v_keys
+    FROM user_keys k
+    WHERE k.user_id = p_user_id
+      AND k.is_active = true
+      AND (k.expires_at IS NULL OR k.expires_at > NOW())
+      AND (p_key_type = '' OR k.key_type = p_key_type);
+
+    RETURN QUERY SELECT true, NULL::TEXT, v_keys;
+EXCEPTION WHEN OTHERS THEN
+    RETURN QUERY SELECT false, SQLERRM, NULL::JSONB;
+END;
+$$;
+
+-- resolvespec_keystore_create_key
+-- Inserts a new key row. key_hash is provided by the caller (Go hashes the raw key).
+-- Returns the created key record (without key_hash).
+CREATE OR REPLACE FUNCTION resolvespec_keystore_create_key(
+    p_request JSONB
+)
+RETURNS TABLE(p_success BOOLEAN, p_error TEXT, p_key JSONB)
+LANGUAGE plpgsql AS $$
+DECLARE
+    v_id         BIGINT;
+    v_created_at TIMESTAMP;
+    v_key        JSONB;
+BEGIN
+    INSERT INTO user_keys (user_id, key_type, key_hash, name, scopes, meta, expires_at)
+    VALUES (
+        (p_request->>'user_id')::INTEGER,
+        p_request->>'key_type',
+        p_request->>'key_hash',
+        COALESCE(p_request->>'name', ''),
+        p_request->>'scopes',
+        p_request->'meta',
+        CASE WHEN p_request->>'expires_at' IS NOT NULL
+             THEN (p_request->>'expires_at')::TIMESTAMP
+             ELSE NULL
+        END
+    )
+    RETURNING id, created_at INTO v_id, v_created_at;
+
+    v_key := jsonb_build_object(
+        'id',         v_id,
+        'user_id',    (p_request->>'user_id')::INTEGER,
+        'key_type',   p_request->>'key_type',
+        'name',       COALESCE(p_request->>'name', ''),
+        'scopes',     CASE WHEN p_request->>'scopes' IS NOT NULL
+                           THEN (p_request->>'scopes')::jsonb
+                           ELSE '[]'::jsonb END,
+        'meta',       COALESCE(p_request->'meta', '{}'::jsonb),
+        'expires_at', p_request->>'expires_at',
+        'created_at', v_created_at,
+        'is_active',  true
+    );
+
+    RETURN QUERY SELECT true, NULL::TEXT, v_key;
+EXCEPTION WHEN OTHERS THEN
+    RETURN QUERY SELECT false, SQLERRM, NULL::JSONB;
+END;
+$$;
+
+-- resolvespec_keystore_delete_key
+-- Soft-deletes a key (is_active = false) after verifying ownership.
+-- Returns p_key_hash so the caller can invalidate cache entries without a separate query.
+CREATE OR REPLACE FUNCTION resolvespec_keystore_delete_key(
+    p_user_id INTEGER,
+    p_key_id  BIGINT
+)
+RETURNS TABLE(p_success BOOLEAN, p_error TEXT, p_key_hash TEXT)
+LANGUAGE plpgsql AS $$
+DECLARE
+    v_hash TEXT;
+BEGIN
+    UPDATE user_keys
+    SET is_active = false
+    WHERE id = p_key_id AND user_id = p_user_id AND is_active = true
+    RETURNING key_hash INTO v_hash;
+
+    IF NOT FOUND THEN
+        RETURN QUERY SELECT false, 'key not found or already deleted'::TEXT, NULL::TEXT;
+        RETURN;
+    END IF;
+
+    RETURN QUERY SELECT true, NULL::TEXT, v_hash;
+EXCEPTION WHEN OTHERS THEN
+    RETURN QUERY SELECT false, SQLERRM, NULL::TEXT;
+END;
+$$;
+
+-- resolvespec_keystore_validate_key
+-- Looks up a key by its SHA-256 hash, checks active status and expiry,
+-- updates last_used_at, and returns the key record.
+-- p_key_type can be empty to accept any key type.
+CREATE OR REPLACE FUNCTION resolvespec_keystore_validate_key(
+    p_key_hash TEXT,
+    p_key_type TEXT DEFAULT ''
+)
+RETURNS TABLE(p_success BOOLEAN, p_error TEXT, p_key JSONB)
+LANGUAGE plpgsql AS $$
+DECLARE
+    v_key_rec user_keys%ROWTYPE;
+    v_key     JSONB;
+BEGIN
+    SELECT * INTO v_key_rec
+    FROM user_keys
+    WHERE key_hash = p_key_hash
+      AND is_active = true
+      AND (expires_at IS NULL OR expires_at > NOW())
+      AND (p_key_type = '' OR key_type = p_key_type);
+
+    IF NOT FOUND THEN
+        RETURN QUERY SELECT false, 'invalid or expired key'::TEXT, NULL::JSONB;
+        RETURN;
+    END IF;
+
+    UPDATE user_keys SET last_used_at = NOW() WHERE id = v_key_rec.id;
+
+    v_key := jsonb_build_object(
+        'id',           v_key_rec.id,
+        'user_id',      v_key_rec.user_id,
+        'key_type',     v_key_rec.key_type,
+        'name',         v_key_rec.name,
+        'scopes',       CASE WHEN v_key_rec.scopes IS NOT NULL
+                             THEN v_key_rec.scopes::jsonb
+                             ELSE '[]'::jsonb END,
+        'meta',         COALESCE(v_key_rec.meta, '{}'::jsonb),
+        'expires_at',   v_key_rec.expires_at,
+        'created_at',   v_key_rec.created_at,
+        'last_used_at', NOW(),
+        'is_active',    v_key_rec.is_active
+    );
+
+    RETURN QUERY SELECT true, NULL::TEXT, v_key;
+EXCEPTION WHEN OTHERS THEN
+    RETURN QUERY SELECT false, SQLERRM, NULL::JSONB;
+END;
+$$;

pkg/security/keystore_sql_names.go

@@ -0,0 +1,61 @@
+package security
+
+import "fmt"
+
+// KeyStoreSQLNames holds the configurable stored procedure names used by DatabaseKeyStore.
+// Use DefaultKeyStoreSQLNames() for defaults and MergeKeyStoreSQLNames() for partial overrides.
+type KeyStoreSQLNames struct {
+	GetUserKeys string // default: "resolvespec_keystore_get_user_keys"
+	CreateKey   string // default: "resolvespec_keystore_create_key"
+	DeleteKey   string // default: "resolvespec_keystore_delete_key"
+	ValidateKey string // default: "resolvespec_keystore_validate_key"
+}
+
+// DefaultKeyStoreSQLNames returns a KeyStoreSQLNames with all default resolvespec_keystore_* values.
+func DefaultKeyStoreSQLNames() *KeyStoreSQLNames {
+	return &KeyStoreSQLNames{
+		GetUserKeys: "resolvespec_keystore_get_user_keys",
+		CreateKey:   "resolvespec_keystore_create_key",
+		DeleteKey:   "resolvespec_keystore_delete_key",
+		ValidateKey: "resolvespec_keystore_validate_key",
+	}
+}
+
+// MergeKeyStoreSQLNames returns a copy of base with any non-empty fields from override applied.
+// If override is nil, a copy of base is returned.
+func MergeKeyStoreSQLNames(base, override *KeyStoreSQLNames) *KeyStoreSQLNames {
+	if override == nil {
+		copied := *base
+		return &copied
+	}
+	merged := *base
+	if override.GetUserKeys != "" {
+		merged.GetUserKeys = override.GetUserKeys
+	}
+	if override.CreateKey != "" {
+		merged.CreateKey = override.CreateKey
+	}
+	if override.DeleteKey != "" {
+		merged.DeleteKey = override.DeleteKey
+	}
+	if override.ValidateKey != "" {
+		merged.ValidateKey = override.ValidateKey
+	}
+	return &merged
+}
+
+// ValidateKeyStoreSQLNames checks that all non-empty procedure names are valid SQL identifiers.
+func ValidateKeyStoreSQLNames(names *KeyStoreSQLNames) error {
+	fields := map[string]string{
+		"GetUserKeys": names.GetUserKeys,
+		"CreateKey":   names.CreateKey,
+		"DeleteKey":   names.DeleteKey,
+		"ValidateKey": names.ValidateKey,
+	}
+	for field, val := range fields {
+		if val != "" && !validSQLIdentifier.MatchString(val) {
+			return fmt.Errorf("KeyStoreSQLNames.%s contains invalid characters: %q", field, val)
+		}
+	}
+	return nil
+}

pkg/security/oauth2_methods.go

@@ -244,7 +244,7 @@ func (a *DatabaseAuthenticator) oauth2GetOrCreateUser(ctx context.Context, userC
 	var errMsg *string
 	var userID *int
 
-	err = a.db.QueryRowContext(ctx, fmt.Sprintf(`
+	err = a.getDB().QueryRowContext(ctx, fmt.Sprintf(`
 		SELECT p_success, p_error, p_user_id
 		FROM %s($1::jsonb)
 	`, a.sqlNames.OAuthGetOrCreateUser), userJSON).Scan(&success, &errMsg, &userID)
@@ -287,7 +287,7 @@ func (a *DatabaseAuthenticator) oauth2CreateSession(ctx context.Context, session
 	var success bool
 	var errMsg *string
 
-	err = a.db.QueryRowContext(ctx, fmt.Sprintf(`
+	err = a.getDB().QueryRowContext(ctx, fmt.Sprintf(`
 		SELECT p_success, p_error
 		FROM %s($1::jsonb)
 	`, a.sqlNames.OAuthCreateSession), sessionJSON).Scan(&success, &errMsg)
@@ -385,7 +385,7 @@ func (a *DatabaseAuthenticator) OAuth2RefreshToken(ctx context.Context, refreshT
 	var errMsg *string
 	var sessionData []byte
 
-	err = a.db.QueryRowContext(ctx, fmt.Sprintf(`
+	err = a.getDB().QueryRowContext(ctx, fmt.Sprintf(`
 		SELECT p_success, p_error, p_data::text
 		FROM %s($1)
 	`, a.sqlNames.OAuthGetRefreshToken), refreshToken).Scan(&success, &errMsg, &sessionData)
@@ -451,7 +451,7 @@ func (a *DatabaseAuthenticator) OAuth2RefreshToken(ctx context.Context, refreshT
 	var updateSuccess bool
 	var updateErrMsg *string
 
-	err = a.db.QueryRowContext(ctx, fmt.Sprintf(`
+	err = a.getDB().QueryRowContext(ctx, fmt.Sprintf(`
 		SELECT p_success, p_error
 		FROM %s($1::jsonb)
 	`, a.sqlNames.OAuthUpdateRefreshToken), updateJSON).Scan(&updateSuccess, &updateErrMsg)
@@ -472,7 +472,7 @@ func (a *DatabaseAuthenticator) OAuth2RefreshToken(ctx context.Context, refreshT
 	var userErrMsg *string
 	var userData []byte
 
-	err = a.db.QueryRowContext(ctx, fmt.Sprintf(`
+	err = a.getDB().QueryRowContext(ctx, fmt.Sprintf(`
 		SELECT p_success, p_error, p_data::text
 		FROM %s($1)
 	`, a.sqlNames.OAuthGetUser), session.UserID).Scan(&userSuccess, &userErrMsg, &userData)

pkg/security/oauth_server.go

@@ -0,0 +1,917 @@
+package security
+
+import (
+	"context"
+	"crypto/rand"
+	"crypto/sha256"
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+	"strings"
+	"sync"
+	"time"
+)
+
+// OAuthServerConfig configures the MCP-standard OAuth2 authorization server.
+type OAuthServerConfig struct {
+	// Issuer is the public base URL of this server (e.g. "https://api.example.com").
+	// Used in /.well-known/oauth-authorization-server and to build endpoint URLs.
+	Issuer string
+
+	// ProviderCallbackPath is the path on this server that external OAuth2 providers
+	// redirect back to. Defaults to "/oauth/provider/callback".
+	ProviderCallbackPath string
+
+	// LoginTitle is shown on the built-in login form when the server acts as its own
+	// identity provider. Defaults to "Sign in".
+	LoginTitle string
+
+	// PersistClients stores registered clients in the database when a DatabaseAuthenticator is provided.
+	// Clients registered during a session survive server restarts.
+	PersistClients bool
+
+	// PersistCodes stores authorization codes in the database.
+	// Useful for multi-instance deployments. Defaults to in-memory.
+	PersistCodes bool
+
+	// DefaultScopes lists scopes advertised in server metadata. Defaults to ["openid","profile","email"].
+	DefaultScopes []string
+
+	// AccessTokenTTL is the issued token lifetime. Defaults to 24h.
+	AccessTokenTTL time.Duration
+
+	// AuthCodeTTL is the auth code lifetime. Defaults to 2 minutes.
+	AuthCodeTTL time.Duration
+}
+
+// oauthClient is a dynamically registered OAuth2 client (RFC 7591).
+type oauthClient struct {
+	ClientID      string   `json:"client_id"`
+	RedirectURIs  []string `json:"redirect_uris"`
+	ClientName    string   `json:"client_name,omitempty"`
+	GrantTypes    []string `json:"grant_types"`
+	AllowedScopes []string `json:"allowed_scopes,omitempty"`
+}
+
+// pendingAuth tracks an in-progress authorization code exchange.
+type pendingAuth struct {
+	ClientID            string
+	RedirectURI         string
+	ClientState         string
+	CodeChallenge       string
+	CodeChallengeMethod string
+	ProviderName        string // empty = password login
+	ExpiresAt           time.Time
+	SessionToken        string   // set after authentication completes
+	RefreshToken        string   // set after authentication completes when refresh tokens are issued
+	Scopes              []string // requested scopes
+}
+
+// externalProvider pairs a DatabaseAuthenticator with its provider name.
+type externalProvider struct {
+	auth         *DatabaseAuthenticator
+	providerName string
+}
+
+// OAuthServer implements the MCP-standard OAuth2 authorization server (OAuth 2.1 + PKCE).
+//
+// It can act as both:
+//   - A direct identity provider using DatabaseAuthenticator username/password login
+//   - A federation layer that delegates authentication to external OAuth2 providers
+//     (Google, GitHub, Microsoft, etc.) registered via RegisterExternalProvider
+//
+// The server exposes these RFC-compliant endpoints:
+//
+//	GET  /.well-known/oauth-authorization-server   RFC 8414 — server metadata discovery
+//	POST /oauth/register                            RFC 7591 — dynamic client registration
+//	GET  /oauth/authorize                           OAuth 2.1 + PKCE — start authorization
+//	POST /oauth/authorize                           Direct login form submission
+//	POST /oauth/token                               Token exchange and refresh
+//	POST /oauth/revoke                              RFC 7009 — token revocation
+//	POST /oauth/introspect                          RFC 7662 — token introspection
+//	GET  {ProviderCallbackPath}                     Internal — external provider callback
+type OAuthServer struct {
+	cfg       OAuthServerConfig
+	auth      *DatabaseAuthenticator // nil = only external providers
+	providers []externalProvider
+
+	mu      sync.RWMutex
+	clients map[string]*oauthClient
+	pending map[string]*pendingAuth // provider_state → pending (external flow)
+	codes   map[string]*pendingAuth // auth_code     → pending (post-auth)
+
+	done chan struct{} // closed by Close() to stop background goroutines
+}
+
+// NewOAuthServer creates a new MCP OAuth2 authorization server.
+//
+// Pass a DatabaseAuthenticator to enable direct username/password login (the server
+// acts as its own identity provider). Pass nil to use only external providers.
+// External providers are added separately via RegisterExternalProvider.
+//
+// Call Close() to stop background goroutines when the server is no longer needed.
+func NewOAuthServer(cfg OAuthServerConfig, auth *DatabaseAuthenticator) *OAuthServer {
+	if cfg.ProviderCallbackPath == "" {
+		cfg.ProviderCallbackPath = "/oauth/provider/callback"
+	}
+	if cfg.LoginTitle == "" {
+		cfg.LoginTitle = "Sign in"
+	}
+	if len(cfg.DefaultScopes) == 0 {
+		cfg.DefaultScopes = []string{"openid", "profile", "email"}
+	}
+	if cfg.AccessTokenTTL == 0 {
+		cfg.AccessTokenTTL = 24 * time.Hour
+	}
+	if cfg.AuthCodeTTL == 0 {
+		cfg.AuthCodeTTL = 2 * time.Minute
+	}
+	// Normalize issuer: remove trailing slash to ensure consistent endpoint URL construction.
+	cfg.Issuer = strings.TrimSuffix(cfg.Issuer, "/")
+	s := &OAuthServer{
+		cfg:     cfg,
+		auth:    auth,
+		clients: make(map[string]*oauthClient),
+		pending: make(map[string]*pendingAuth),
+		codes:   make(map[string]*pendingAuth),
+		done:    make(chan struct{}),
+	}
+	go s.cleanupExpired()
+	return s
+}
+
+// Close stops the background goroutines started by NewOAuthServer.
+// It is safe to call Close multiple times.
+func (s *OAuthServer) Close() {
+	select {
+	case <-s.done:
+		// already closed
+	default:
+		close(s.done)
+	}
+}
+
+// RegisterExternalProvider adds an external OAuth2 provider (Google, GitHub, Microsoft, etc.)
+// that handles user authentication via redirect. The DatabaseAuthenticator must have been
+// configured with WithOAuth2(providerName, ...) before calling this.
+// Multiple providers can be registered; the first is used as the default.
+// All providers must be registered before the server starts serving requests.
+func (s *OAuthServer) RegisterExternalProvider(auth *DatabaseAuthenticator, providerName string) {
+	s.mu.Lock()
+	s.providers = append(s.providers, externalProvider{auth: auth, providerName: providerName})
+	s.mu.Unlock()
+}
+
+// ProviderCallbackPath returns the configured path for external provider callbacks.
+func (s *OAuthServer) ProviderCallbackPath() string {
+	return s.cfg.ProviderCallbackPath
+}
+
+// HTTPHandler returns an http.Handler that serves all RFC-required OAuth2 endpoints.
+// Mount it at the root of your HTTP server alongside the MCP transport.
+//
+//	mux := http.NewServeMux()
+//	mux.Handle("/", oauthServer.HTTPHandler())
+//	mux.Handle("/mcp/", mcpTransport)
+func (s *OAuthServer) HTTPHandler() http.Handler {
+	mux := http.NewServeMux()
+	mux.HandleFunc("/.well-known/oauth-authorization-server", s.metadataHandler)
+	mux.HandleFunc("/oauth/register", s.registerHandler)
+	mux.HandleFunc("/oauth/authorize", s.authorizeHandler)
+	mux.HandleFunc("/oauth/token", s.tokenHandler)
+	mux.HandleFunc("/oauth/revoke", s.revokeHandler)
+	mux.HandleFunc("/oauth/introspect", s.introspectHandler)
+	mux.HandleFunc(s.cfg.ProviderCallbackPath, s.providerCallbackHandler)
+	return mux
+}
+
+// cleanupExpired removes stale pending auths and codes every 5 minutes.
+func (s *OAuthServer) cleanupExpired() {
+	ticker := time.NewTicker(5 * time.Minute)
+	defer ticker.Stop()
+	for {
+		select {
+		case <-s.done:
+			return
+		case <-ticker.C:
+			now := time.Now()
+			s.mu.Lock()
+			for k, p := range s.pending {
+				if now.After(p.ExpiresAt) {
+					delete(s.pending, k)
+				}
+			}
+			for k, p := range s.codes {
+				if now.After(p.ExpiresAt) {
+					delete(s.codes, k)
+				}
+			}
+			s.mu.Unlock()
+		}
+	}
+}
+
+// --------------------------------------------------------------------------
+// RFC 8414 — Server metadata
+// --------------------------------------------------------------------------
+
+func (s *OAuthServer) metadataHandler(w http.ResponseWriter, r *http.Request) {
+	issuer := s.cfg.Issuer
+	meta := map[string]interface{}{
+		"issuer":                                issuer,
+		"authorization_endpoint":                issuer + "/oauth/authorize",
+		"token_endpoint":                        issuer + "/oauth/token",
+		"registration_endpoint":                 issuer + "/oauth/register",
+		"revocation_endpoint":                   issuer + "/oauth/revoke",
+		"introspection_endpoint":                issuer + "/oauth/introspect",
+		"scopes_supported":                      s.cfg.DefaultScopes,
+		"response_types_supported":              []string{"code"},
+		"grant_types_supported":                 []string{"authorization_code", "refresh_token"},
+		"code_challenge_methods_supported":      []string{"S256"},
+		"token_endpoint_auth_methods_supported": []string{"none"},
+	}
+	w.Header().Set("Content-Type", "application/json")
+	json.NewEncoder(w).Encode(meta) //nolint:errcheck
+}
+
+// --------------------------------------------------------------------------
+// RFC 7591 — Dynamic client registration
+// --------------------------------------------------------------------------
+
+func (s *OAuthServer) registerHandler(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	var req struct {
+		RedirectURIs  []string `json:"redirect_uris"`
+		ClientName    string   `json:"client_name"`
+		GrantTypes    []string `json:"grant_types"`
+		AllowedScopes []string `json:"allowed_scopes"`
+	}
+	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
+		writeOAuthError(w, "invalid_request", "malformed JSON", http.StatusBadRequest)
+		return
+	}
+	if len(req.RedirectURIs) == 0 {
+		writeOAuthError(w, "invalid_request", "redirect_uris required", http.StatusBadRequest)
+		return
+	}
+	grantTypes := req.GrantTypes
+	if len(grantTypes) == 0 {
+		grantTypes = []string{"authorization_code"}
+	}
+	allowedScopes := req.AllowedScopes
+	if len(allowedScopes) == 0 {
+		allowedScopes = s.cfg.DefaultScopes
+	}
+	clientID, err := randomOAuthToken()
+	if err != nil {
+		http.Error(w, "server error", http.StatusInternalServerError)
+		return
+	}
+	client := &oauthClient{
+		ClientID:      clientID,
+		RedirectURIs:  req.RedirectURIs,
+		ClientName:    req.ClientName,
+		GrantTypes:    grantTypes,
+		AllowedScopes: allowedScopes,
+	}
+
+	if s.cfg.PersistClients && s.auth != nil {
+		dbClient := &OAuthServerClient{
+			ClientID:      client.ClientID,
+			RedirectURIs:  client.RedirectURIs,
+			ClientName:    client.ClientName,
+			GrantTypes:    client.GrantTypes,
+			AllowedScopes: client.AllowedScopes,
+		}
+		if _, err := s.auth.OAuthRegisterClient(r.Context(), dbClient); err != nil {
+			http.Error(w, "server error", http.StatusInternalServerError)
+			return
+		}
+	}
+
+	s.mu.Lock()
+	s.clients[clientID] = client
+	s.mu.Unlock()
+
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(http.StatusCreated)
+	json.NewEncoder(w).Encode(client) //nolint:errcheck
+}
+
+// --------------------------------------------------------------------------
+// Authorization endpoint — GET + POST /oauth/authorize
+// --------------------------------------------------------------------------
+
+func (s *OAuthServer) authorizeHandler(w http.ResponseWriter, r *http.Request) {
+	switch r.Method {
+	case http.MethodGet:
+		s.authorizeGet(w, r)
+	case http.MethodPost:
+		s.authorizePost(w, r)
+	default:
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+	}
+}
+
+// authorizeGet validates the request and either:
+//   - Redirects to an external provider (if providers are registered)
+//   - Renders a login form (if the server is its own identity provider)
+func (s *OAuthServer) authorizeGet(w http.ResponseWriter, r *http.Request) {
+	q := r.URL.Query()
+	clientID := q.Get("client_id")
+	redirectURI := q.Get("redirect_uri")
+	clientState := q.Get("state")
+	codeChallenge := q.Get("code_challenge")
+	codeChallengeMethod := q.Get("code_challenge_method")
+	providerName := q.Get("provider")
+	scopeStr := q.Get("scope")
+	var scopes []string
+	if scopeStr != "" {
+		scopes = strings.Fields(scopeStr)
+	}
+
+	if q.Get("response_type") != "code" {
+		writeOAuthError(w, "unsupported_response_type", "only 'code' is supported", http.StatusBadRequest)
+		return
+	}
+	if codeChallenge == "" {
+		writeOAuthError(w, "invalid_request", "code_challenge required (PKCE S256)", http.StatusBadRequest)
+		return
+	}
+	if codeChallengeMethod != "" && codeChallengeMethod != "S256" {
+		writeOAuthError(w, "invalid_request", "only S256 code_challenge_method is supported", http.StatusBadRequest)
+		return
+	}
+	client, ok := s.lookupOrFetchClient(r.Context(), clientID)
+	if !ok {
+		writeOAuthError(w, "invalid_client", "unknown client_id", http.StatusBadRequest)
+		return
+	}
+	if !oauthSliceContains(client.RedirectURIs, redirectURI) {
+		writeOAuthError(w, "invalid_request", "redirect_uri not registered", http.StatusBadRequest)
+		return
+	}
+
+	// External provider path
+	if len(s.providers) > 0 {
+		s.redirectToExternalProvider(w, r, clientID, redirectURI, clientState, codeChallenge, codeChallengeMethod, providerName, scopes)
+		return
+	}
+
+	// Direct login form path (server is its own identity provider)
+	if s.auth == nil {
+		http.Error(w, "no authentication provider configured", http.StatusInternalServerError)
+		return
+	}
+	s.renderLoginForm(w, r, clientID, redirectURI, clientState, codeChallenge, codeChallengeMethod, scopeStr, "")
+}
+
+// authorizePost handles login form submission for the direct login flow.
+func (s *OAuthServer) authorizePost(w http.ResponseWriter, r *http.Request) {
+	if err := r.ParseForm(); err != nil {
+		http.Error(w, "invalid form", http.StatusBadRequest)
+		return
+	}
+
+	clientID := r.FormValue("client_id")
+	redirectURI := r.FormValue("redirect_uri")
+	clientState := r.FormValue("client_state")
+	codeChallenge := r.FormValue("code_challenge")
+	codeChallengeMethod := r.FormValue("code_challenge_method")
+	username := r.FormValue("username")
+	password := r.FormValue("password")
+	scopeStr := r.FormValue("scope")
+	var scopes []string
+	if scopeStr != "" {
+		scopes = strings.Fields(scopeStr)
+	}
+
+	client, ok := s.lookupOrFetchClient(r.Context(), clientID)
+	if !ok || !oauthSliceContains(client.RedirectURIs, redirectURI) {
+		http.Error(w, "invalid client or redirect_uri", http.StatusBadRequest)
+		return
+	}
+	if s.auth == nil {
+		http.Error(w, "no authentication provider configured", http.StatusInternalServerError)
+		return
+	}
+
+	loginResp, err := s.auth.Login(r.Context(), LoginRequest{
+		Username: username,
+		Password: password,
+	})
+	if err != nil {
+		s.renderLoginForm(w, r, clientID, redirectURI, clientState, codeChallenge, codeChallengeMethod, scopeStr, "Invalid username or password")
+		return
+	}
+
+	s.issueCodeAndRedirect(w, r, loginResp.Token, loginResp.RefreshToken, clientID, redirectURI, clientState, codeChallenge, codeChallengeMethod, "", scopes)
+}
+
+// redirectToExternalProvider stores the pending auth and redirects to the configured provider.
+func (s *OAuthServer) redirectToExternalProvider(w http.ResponseWriter, r *http.Request, clientID, redirectURI, clientState, codeChallenge, codeChallengeMethod, providerName string, scopes []string) {
+	var provider *externalProvider
+	if providerName != "" {
+		for i := range s.providers {
+			if s.providers[i].providerName == providerName {
+				provider = &s.providers[i]
+				break
+			}
+		}
+		if provider == nil {
+			http.Error(w, fmt.Sprintf("provider %q not found", providerName), http.StatusBadRequest)
+			return
+		}
+	} else {
+		provider = &s.providers[0]
+	}
+
+	providerState, err := randomOAuthToken()
+	if err != nil {
+		http.Error(w, "server error", http.StatusInternalServerError)
+		return
+	}
+
+	pending := &pendingAuth{
+		ClientID:            clientID,
+		RedirectURI:         redirectURI,
+		ClientState:         clientState,
+		CodeChallenge:       codeChallenge,
+		CodeChallengeMethod: codeChallengeMethod,
+		ProviderName:        provider.providerName,
+		ExpiresAt:           time.Now().Add(10 * time.Minute),
+		Scopes:              scopes,
+	}
+	s.mu.Lock()
+	s.pending[providerState] = pending
+	s.mu.Unlock()
+
+	authURL, err := provider.auth.OAuth2GetAuthURL(provider.providerName, providerState)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	http.Redirect(w, r, authURL, http.StatusFound)
+}
+
+// --------------------------------------------------------------------------
+// External provider callback — GET {ProviderCallbackPath}
+// --------------------------------------------------------------------------
+
+func (s *OAuthServer) providerCallbackHandler(w http.ResponseWriter, r *http.Request) {
+	code := r.URL.Query().Get("code")
+	providerState := r.URL.Query().Get("state")
+
+	if code == "" {
+		http.Error(w, "missing code", http.StatusBadRequest)
+		return
+	}
+
+	s.mu.Lock()
+	pending, ok := s.pending[providerState]
+	if ok {
+		delete(s.pending, providerState)
+	}
+	s.mu.Unlock()
+
+	if !ok || time.Now().After(pending.ExpiresAt) {
+		http.Error(w, "invalid or expired state", http.StatusBadRequest)
+		return
+	}
+
+	provider := s.providerByName(pending.ProviderName)
+	if provider == nil {
+		http.Error(w, fmt.Sprintf("provider %q not found", pending.ProviderName), http.StatusInternalServerError)
+		return
+	}
+
+	loginResp, err := provider.auth.OAuth2HandleCallback(r.Context(), pending.ProviderName, code, providerState)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusUnauthorized)
+		return
+	}
+
+	s.issueCodeAndRedirect(w, r, loginResp.Token, loginResp.RefreshToken,
+		pending.ClientID, pending.RedirectURI, pending.ClientState,
+		pending.CodeChallenge, pending.CodeChallengeMethod, pending.ProviderName, pending.Scopes)
+}
+
+// issueCodeAndRedirect generates a short-lived auth code and redirects to the MCP client.
+func (s *OAuthServer) issueCodeAndRedirect(w http.ResponseWriter, r *http.Request, sessionToken, refreshToken, clientID, redirectURI, clientState, codeChallenge, codeChallengeMethod, providerName string, scopes []string) {
+	authCode, err := randomOAuthToken()
+	if err != nil {
+		http.Error(w, "server error", http.StatusInternalServerError)
+		return
+	}
+
+	pending := &pendingAuth{
+		ClientID:            clientID,
+		RedirectURI:         redirectURI,
+		ClientState:         clientState,
+		CodeChallenge:       codeChallenge,
+		CodeChallengeMethod: codeChallengeMethod,
+		ProviderName:        providerName,
+		SessionToken:        sessionToken,
+		RefreshToken:        refreshToken,
+		ExpiresAt:           time.Now().Add(s.cfg.AuthCodeTTL),
+		Scopes:              scopes,
+	}
+
+	if s.cfg.PersistCodes && s.auth != nil {
+		oauthCode := &OAuthCode{
+			Code:                authCode,
+			ClientID:            clientID,
+			RedirectURI:         redirectURI,
+			ClientState:         clientState,
+			CodeChallenge:       codeChallenge,
+			CodeChallengeMethod: codeChallengeMethod,
+			SessionToken:        sessionToken,
+			RefreshToken:        refreshToken,
+			Scopes:              scopes,
+			ExpiresAt:           pending.ExpiresAt,
+		}
+		if err := s.auth.OAuthSaveCode(r.Context(), oauthCode); err != nil {
+			http.Error(w, "server error", http.StatusInternalServerError)
+			return
+		}
+	} else {
+		s.mu.Lock()
+		s.codes[authCode] = pending
+		s.mu.Unlock()
+	}
+
+	redirectURL, err := url.Parse(redirectURI)
+	if err != nil {
+		http.Error(w, "invalid redirect_uri", http.StatusInternalServerError)
+		return
+	}
+	qp := redirectURL.Query()
+	qp.Set("code", authCode)
+	if clientState != "" {
+		qp.Set("state", clientState)
+	}
+	redirectURL.RawQuery = qp.Encode()
+	http.Redirect(w, r, redirectURL.String(), http.StatusFound)
+}
+
+// --------------------------------------------------------------------------
+// Token endpoint — POST /oauth/token
+// --------------------------------------------------------------------------
+
+func (s *OAuthServer) tokenHandler(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	if err := r.ParseForm(); err != nil {
+		writeOAuthError(w, "invalid_request", "cannot parse form", http.StatusBadRequest)
+		return
+	}
+	switch r.FormValue("grant_type") {
+	case "authorization_code":
+		s.handleAuthCodeGrant(w, r)
+	case "refresh_token":
+		s.handleRefreshGrant(w, r)
+	default:
+		writeOAuthError(w, "unsupported_grant_type", "", http.StatusBadRequest)
+	}
+}
+
+func (s *OAuthServer) handleAuthCodeGrant(w http.ResponseWriter, r *http.Request) {
+	code := r.FormValue("code")
+	redirectURI := r.FormValue("redirect_uri")
+	clientID := r.FormValue("client_id")
+	codeVerifier := r.FormValue("code_verifier")
+
+	if code == "" || codeVerifier == "" {
+		writeOAuthError(w, "invalid_request", "code and code_verifier required", http.StatusBadRequest)
+		return
+	}
+
+	var sessionToken string
+	var refreshToken string
+	var scopes []string
+
+	if s.cfg.PersistCodes && s.auth != nil {
+		oauthCode, err := s.auth.OAuthExchangeCode(r.Context(), code)
+		if err != nil {
+			writeOAuthError(w, "invalid_grant", "code expired or invalid", http.StatusBadRequest)
+			return
+		}
+		if oauthCode.ClientID != clientID {
+			writeOAuthError(w, "invalid_client", "", http.StatusBadRequest)
+			return
+		}
+		if oauthCode.RedirectURI != redirectURI {
+			writeOAuthError(w, "invalid_grant", "redirect_uri mismatch", http.StatusBadRequest)
+			return
+		}
+		if !validatePKCESHA256(oauthCode.CodeChallenge, codeVerifier) {
+			writeOAuthError(w, "invalid_grant", "code_verifier invalid", http.StatusBadRequest)
+			return
+		}
+		sessionToken = oauthCode.SessionToken
+		refreshToken = oauthCode.RefreshToken
+		scopes = oauthCode.Scopes
+	} else {
+		s.mu.Lock()
+		pending, ok := s.codes[code]
+		if ok {
+			delete(s.codes, code)
+		}
+		s.mu.Unlock()
+
+		if !ok || time.Now().After(pending.ExpiresAt) {
+			writeOAuthError(w, "invalid_grant", "code expired or invalid", http.StatusBadRequest)
+			return
+		}
+		if pending.ClientID != clientID {
+			writeOAuthError(w, "invalid_client", "", http.StatusBadRequest)
+			return
+		}
+		if pending.RedirectURI != redirectURI {
+			writeOAuthError(w, "invalid_grant", "redirect_uri mismatch", http.StatusBadRequest)
+			return
+		}
+		if !validatePKCESHA256(pending.CodeChallenge, codeVerifier) {
+			writeOAuthError(w, "invalid_grant", "code_verifier invalid", http.StatusBadRequest)
+			return
+		}
+		sessionToken = pending.SessionToken
+		refreshToken = pending.RefreshToken
+		scopes = pending.Scopes
+	}
+
+	s.writeOAuthToken(w, sessionToken, refreshToken, scopes)
+}
+
+func (s *OAuthServer) handleRefreshGrant(w http.ResponseWriter, r *http.Request) {
+	refreshToken := r.FormValue("refresh_token")
+	providerName := r.FormValue("provider")
+	if refreshToken == "" {
+		writeOAuthError(w, "invalid_request", "refresh_token required", http.StatusBadRequest)
+		return
+	}
+
+	// Try external providers first, then fall back to DatabaseAuthenticator
+	provider := s.providerByName(providerName)
+	if provider != nil {
+		loginResp, err := provider.auth.OAuth2RefreshToken(r.Context(), refreshToken, providerName)
+		if err != nil {
+			writeOAuthError(w, "invalid_grant", err.Error(), http.StatusBadRequest)
+			return
+		}
+		s.writeOAuthToken(w, loginResp.Token, loginResp.RefreshToken, nil)
+		return
+	}
+
+	if s.auth != nil {
+		loginResp, err := s.auth.RefreshToken(r.Context(), refreshToken)
+		if err != nil {
+			writeOAuthError(w, "invalid_grant", err.Error(), http.StatusBadRequest)
+			return
+		}
+		s.writeOAuthToken(w, loginResp.Token, loginResp.RefreshToken, nil)
+		return
+	}
+
+	writeOAuthError(w, "invalid_grant", "no provider available for refresh", http.StatusBadRequest)
+}
+
+// --------------------------------------------------------------------------
+// RFC 7009 — Token revocation
+// --------------------------------------------------------------------------
+
+func (s *OAuthServer) revokeHandler(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	if err := r.ParseForm(); err != nil {
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+	token := r.FormValue("token")
+	if token == "" {
+		w.WriteHeader(http.StatusOK)
+		return
+	}
+
+	if s.auth != nil {
+		s.auth.OAuthRevokeToken(r.Context(), token) //nolint:errcheck
+	} else {
+		// In external-provider-only mode, attempt revocation via the first provider's auth.
+		s.mu.RLock()
+		var providerAuth *DatabaseAuthenticator
+		if len(s.providers) > 0 {
+			providerAuth = s.providers[0].auth
+		}
+		s.mu.RUnlock()
+		if providerAuth != nil {
+			providerAuth.OAuthRevokeToken(r.Context(), token) //nolint:errcheck
+		}
+	}
+	w.WriteHeader(http.StatusOK)
+}
+
+// --------------------------------------------------------------------------
+// RFC 7662 — Token introspection
+// --------------------------------------------------------------------------
+
+func (s *OAuthServer) introspectHandler(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodPost {
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+	if err := r.ParseForm(); err != nil {
+		w.Header().Set("Content-Type", "application/json")
+		w.Write([]byte(`{"active":false}`)) //nolint:errcheck
+		return
+	}
+	token := r.FormValue("token")
+	w.Header().Set("Content-Type", "application/json")
+
+	if token == "" {
+		w.Write([]byte(`{"active":false}`)) //nolint:errcheck
+		return
+	}
+
+	// Resolve the authenticator to use: prefer the primary auth, then the first provider's auth.
+	authToUse := s.auth
+	if authToUse == nil {
+		s.mu.RLock()
+		if len(s.providers) > 0 {
+			authToUse = s.providers[0].auth
+		}
+		s.mu.RUnlock()
+	}
+	if authToUse == nil {
+		w.Write([]byte(`{"active":false}`)) //nolint:errcheck
+		return
+	}
+
+	info, err := authToUse.OAuthIntrospectToken(r.Context(), token)
+	if err != nil {
+		w.Write([]byte(`{"active":false}`)) //nolint:errcheck
+		return
+	}
+	json.NewEncoder(w).Encode(info) //nolint:errcheck
+}
+
+// --------------------------------------------------------------------------
+// Login form (direct identity provider mode)
+// --------------------------------------------------------------------------
+
+func (s *OAuthServer) renderLoginForm(w http.ResponseWriter, r *http.Request, clientID, redirectURI, clientState, codeChallenge, codeChallengeMethod, scope, errMsg string) {
+	w.Header().Set("Content-Type", "text/html; charset=utf-8")
+	errHTML := ""
+	if errMsg != "" {
+		errHTML = `<p style="color:red">` + errMsg + `</p>`
+	}
+	fmt.Fprintf(w, loginFormHTML,
+		s.cfg.LoginTitle,
+		s.cfg.LoginTitle,
+		errHTML,
+		clientID,
+		htmlEscape(redirectURI),
+		htmlEscape(clientState),
+		htmlEscape(codeChallenge),
+		htmlEscape(codeChallengeMethod),
+		htmlEscape(scope),
+	)
+}
+
+const loginFormHTML = `<!DOCTYPE html>
+<html><head><meta charset="utf-8"><title>%s</title>
+<style>body{font-family:sans-serif;display:flex;justify-content:center;align-items:center;min-height:100vh;margin:0;background:#f5f5f5}
+.card{background:#fff;padding:2rem;border-radius:8px;box-shadow:0 2px 8px rgba(0,0,0,.15);width:320px}
+h2{margin:0 0 1.5rem;font-size:1.25rem}
+label{display:block;margin-bottom:.25rem;font-size:.875rem;color:#555}
+input[type=text],input[type=password]{width:100%%;box-sizing:border-box;padding:.5rem;border:1px solid #ccc;border-radius:4px;margin-bottom:1rem;font-size:1rem}
+button{width:100%%;padding:.6rem;background:#0070f3;color:#fff;border:none;border-radius:4px;font-size:1rem;cursor:pointer}
+button:hover{background:#005fd4}.err{color:#d32f2f;margin-bottom:1rem;font-size:.875rem}</style>
+</head><body><div class="card">
+<h2>%s</h2>%s
+<form method="POST" action="authorize">
+<input type="hidden" name="client_id" value="%s">
+<input type="hidden" name="redirect_uri" value="%s">
+<input type="hidden" name="client_state" value="%s">
+<input type="hidden" name="code_challenge" value="%s">
+<input type="hidden" name="code_challenge_method" value="%s">
+<input type="hidden" name="scope" value="%s">
+<label>Username</label><input type="text" name="username" autofocus autocomplete="username">
+<label>Password</label><input type="password" name="password" autocomplete="current-password">
+<button type="submit">Sign in</button>
+</form></div></body></html>`
+
+// --------------------------------------------------------------------------
+// Helpers
+// --------------------------------------------------------------------------
+
+// lookupOrFetchClient checks in-memory first, then DB if PersistClients is enabled.
+func (s *OAuthServer) lookupOrFetchClient(ctx context.Context, clientID string) (*oauthClient, bool) {
+	s.mu.RLock()
+	c, ok := s.clients[clientID]
+	s.mu.RUnlock()
+	if ok {
+		return c, true
+	}
+
+	if !s.cfg.PersistClients || s.auth == nil {
+		return nil, false
+	}
+
+	dbClient, err := s.auth.OAuthGetClient(ctx, clientID)
+	if err != nil {
+		return nil, false
+	}
+
+	c = &oauthClient{
+		ClientID:      dbClient.ClientID,
+		RedirectURIs:  dbClient.RedirectURIs,
+		ClientName:    dbClient.ClientName,
+		GrantTypes:    dbClient.GrantTypes,
+		AllowedScopes: dbClient.AllowedScopes,
+	}
+	s.mu.Lock()
+	s.clients[clientID] = c
+	s.mu.Unlock()
+	return c, true
+}
+
+func (s *OAuthServer) providerByName(name string) *externalProvider {
+	for i := range s.providers {
+		if s.providers[i].providerName == name {
+			return &s.providers[i]
+		}
+	}
+	// If name is empty and only one provider exists, return it
+	if name == "" && len(s.providers) == 1 {
+		return &s.providers[0]
+	}
+	return nil
+}
+
+func validatePKCESHA256(challenge, verifier string) bool {
+	h := sha256.Sum256([]byte(verifier))
+	return base64.RawURLEncoding.EncodeToString(h[:]) == challenge
+}
+
+func randomOAuthToken() (string, error) {
+	b := make([]byte, 32)
+	if _, err := rand.Read(b); err != nil {
+		return "", err
+	}
+	return base64.RawURLEncoding.EncodeToString(b), nil
+}
+
+func oauthSliceContains(slice []string, s string) bool {
+	for _, v := range slice {
+		if v == s {
+			return true
+		}
+	}
+	return false
+}
+
+func (s *OAuthServer) writeOAuthToken(w http.ResponseWriter, accessToken, refreshToken string, scopes []string) {
+	expiresIn := int64(s.cfg.AccessTokenTTL.Seconds())
+	resp := map[string]interface{}{
+		"access_token": accessToken,
+		"token_type":   "Bearer",
+		"expires_in":   expiresIn,
+	}
+	if refreshToken != "" {
+		resp["refresh_token"] = refreshToken
+	}
+	if len(scopes) > 0 {
+		resp["scope"] = strings.Join(scopes, " ")
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Cache-Control", "no-store")
+	w.Header().Set("Pragma", "no-cache")
+	json.NewEncoder(w).Encode(resp) //nolint:errcheck
+}
+
+func writeOAuthError(w http.ResponseWriter, errCode, description string, status int) {
+	resp := map[string]string{"error": errCode}
+	if description != "" {
+		resp["error_description"] = description
+	}
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	json.NewEncoder(w).Encode(resp) //nolint:errcheck
+}
+
+func htmlEscape(s string) string {
+	s = strings.ReplaceAll(s, "&", "&amp;")
+	s = strings.ReplaceAll(s, `"`, "&#34;")
+	s = strings.ReplaceAll(s, "<", "&lt;")
+	s = strings.ReplaceAll(s, ">", "&gt;")
+	return s
+}

pkg/security/oauth_server_db.go

@@ -0,0 +1,204 @@
+package security
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"time"
+)
+
+// OAuthServerClient is a persisted RFC 7591 registered OAuth2 client.
+type OAuthServerClient struct {
+	ClientID      string   `json:"client_id"`
+	RedirectURIs  []string `json:"redirect_uris"`
+	ClientName    string   `json:"client_name,omitempty"`
+	GrantTypes    []string `json:"grant_types"`
+	AllowedScopes []string `json:"allowed_scopes,omitempty"`
+}
+
+// OAuthCode is a short-lived authorization code.
+type OAuthCode struct {
+	Code                string    `json:"code"`
+	ClientID            string    `json:"client_id"`
+	RedirectURI         string    `json:"redirect_uri"`
+	ClientState         string    `json:"client_state,omitempty"`
+	CodeChallenge       string    `json:"code_challenge"`
+	CodeChallengeMethod string    `json:"code_challenge_method"`
+	SessionToken        string    `json:"session_token"`
+	RefreshToken        string    `json:"refresh_token,omitempty"`
+	Scopes              []string  `json:"scopes,omitempty"`
+	ExpiresAt           time.Time `json:"expires_at"`
+}
+
+// OAuthTokenInfo is the RFC 7662 token introspection response.
+type OAuthTokenInfo struct {
+	Active    bool     `json:"active"`
+	Sub       string   `json:"sub,omitempty"`
+	Username  string   `json:"username,omitempty"`
+	Email     string   `json:"email,omitempty"`
+	UserLevel int      `json:"user_level,omitempty"`
+	Roles     []string `json:"roles,omitempty"`
+	Exp       int64    `json:"exp,omitempty"`
+	Iat       int64    `json:"iat,omitempty"`
+}
+
+// OAuthRegisterClient persists an OAuth2 client registration.
+func (a *DatabaseAuthenticator) OAuthRegisterClient(ctx context.Context, client *OAuthServerClient) (*OAuthServerClient, error) {
+	input, err := json.Marshal(client)
+	if err != nil {
+		return nil, fmt.Errorf("failed to marshal client: %w", err)
+	}
+
+	var success bool
+	var errMsg *string
+	var data []byte
+
+	err = a.db.QueryRowContext(ctx, fmt.Sprintf(`
+		SELECT p_success, p_error, p_data::text
+		FROM %s($1::jsonb)
+	`, a.sqlNames.OAuthRegisterClient), input).Scan(&success, &errMsg, &data)
+	if err != nil {
+		return nil, fmt.Errorf("failed to register client: %w", err)
+	}
+	if !success {
+		if errMsg != nil {
+			return nil, fmt.Errorf("%s", *errMsg)
+		}
+		return nil, fmt.Errorf("failed to register client")
+	}
+
+	var result OAuthServerClient
+	if err := json.Unmarshal(data, &result); err != nil {
+		return nil, fmt.Errorf("failed to parse registered client: %w", err)
+	}
+	return &result, nil
+}
+
+// OAuthGetClient retrieves a registered client by ID.
+func (a *DatabaseAuthenticator) OAuthGetClient(ctx context.Context, clientID string) (*OAuthServerClient, error) {
+	var success bool
+	var errMsg *string
+	var data []byte
+
+	err := a.db.QueryRowContext(ctx, fmt.Sprintf(`
+		SELECT p_success, p_error, p_data::text
+		FROM %s($1)
+	`, a.sqlNames.OAuthGetClient), clientID).Scan(&success, &errMsg, &data)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get client: %w", err)
+	}
+	if !success {
+		if errMsg != nil {
+			return nil, fmt.Errorf("%s", *errMsg)
+		}
+		return nil, fmt.Errorf("client not found")
+	}
+
+	var result OAuthServerClient
+	if err := json.Unmarshal(data, &result); err != nil {
+		return nil, fmt.Errorf("failed to parse client: %w", err)
+	}
+	return &result, nil
+}
+
+// OAuthSaveCode persists an authorization code.
+func (a *DatabaseAuthenticator) OAuthSaveCode(ctx context.Context, code *OAuthCode) error {
+	input, err := json.Marshal(code)
+	if err != nil {
+		return fmt.Errorf("failed to marshal code: %w", err)
+	}
+
+	var success bool
+	var errMsg *string
+
+	err = a.db.QueryRowContext(ctx, fmt.Sprintf(`
+		SELECT p_success, p_error
+		FROM %s($1::jsonb)
+	`, a.sqlNames.OAuthSaveCode), input).Scan(&success, &errMsg)
+	if err != nil {
+		return fmt.Errorf("failed to save code: %w", err)
+	}
+	if !success {
+		if errMsg != nil {
+			return fmt.Errorf("%s", *errMsg)
+		}
+		return fmt.Errorf("failed to save code")
+	}
+	return nil
+}
+
+// OAuthExchangeCode retrieves and deletes an authorization code (single use).
+func (a *DatabaseAuthenticator) OAuthExchangeCode(ctx context.Context, code string) (*OAuthCode, error) {
+	var success bool
+	var errMsg *string
+	var data []byte
+
+	err := a.db.QueryRowContext(ctx, fmt.Sprintf(`
+		SELECT p_success, p_error, p_data::text
+		FROM %s($1)
+	`, a.sqlNames.OAuthExchangeCode), code).Scan(&success, &errMsg, &data)
+	if err != nil {
+		return nil, fmt.Errorf("failed to exchange code: %w", err)
+	}
+	if !success {
+		if errMsg != nil {
+			return nil, fmt.Errorf("%s", *errMsg)
+		}
+		return nil, fmt.Errorf("invalid or expired code")
+	}
+
+	var result OAuthCode
+	if err := json.Unmarshal(data, &result); err != nil {
+		return nil, fmt.Errorf("failed to parse code data: %w", err)
+	}
+	result.Code = code
+	return &result, nil
+}
+
+// OAuthIntrospectToken validates a token and returns its metadata (RFC 7662).
+func (a *DatabaseAuthenticator) OAuthIntrospectToken(ctx context.Context, token string) (*OAuthTokenInfo, error) {
+	var success bool
+	var errMsg *string
+	var data []byte
+
+	err := a.db.QueryRowContext(ctx, fmt.Sprintf(`
+		SELECT p_success, p_error, p_data::text
+		FROM %s($1)
+	`, a.sqlNames.OAuthIntrospect), token).Scan(&success, &errMsg, &data)
+	if err != nil {
+		return nil, fmt.Errorf("failed to introspect token: %w", err)
+	}
+	if !success {
+		if errMsg != nil {
+			return nil, fmt.Errorf("%s", *errMsg)
+		}
+		return nil, fmt.Errorf("introspection failed")
+	}
+
+	var result OAuthTokenInfo
+	if err := json.Unmarshal(data, &result); err != nil {
+		return nil, fmt.Errorf("failed to parse token info: %w", err)
+	}
+	return &result, nil
+}
+
+// OAuthRevokeToken revokes a token by deleting the session (RFC 7009).
+func (a *DatabaseAuthenticator) OAuthRevokeToken(ctx context.Context, token string) error {
+	var success bool
+	var errMsg *string
+
+	err := a.db.QueryRowContext(ctx, fmt.Sprintf(`
+		SELECT p_success, p_error
+		FROM %s($1)
+	`, a.sqlNames.OAuthRevoke), token).Scan(&success, &errMsg)
+	if err != nil {
+		return fmt.Errorf("failed to revoke token: %w", err)
+	}
+	if !success {
+		if errMsg != nil {
+			return fmt.Errorf("%s", *errMsg)
+		}
+		return fmt.Errorf("failed to revoke token")
+	}
+	return nil
+}

pkg/security/passkey_provider.go

@@ -7,6 +7,7 @@ import (
 	"encoding/base64"
 	"encoding/json"
 	"fmt"
+	"sync"
 	"time"
 )
 
@@ -14,6 +15,8 @@ import (
 // Procedure names are configurable via SQLNames (see DefaultSQLNames for defaults)
 type DatabasePasskeyProvider struct {
 	db        *sql.DB
+	dbMu      sync.RWMutex
+	dbFactory func() (*sql.DB, error)
 	rpID      string // Relying Party ID (domain)
 	rpName    string // Relying Party display name
 	rpOrigin  string // Expected origin for WebAuthn
@@ -33,6 +36,9 @@ type DatabasePasskeyProviderOptions struct {
 	Timeout int64
 	// SQLNames provides custom SQL procedure/function names. If nil, uses DefaultSQLNames().
 	SQLNames *SQLNames
+	// DBFactory is called to obtain a fresh *sql.DB when the existing connection is closed.
+	// If nil, reconnection is disabled.
+	DBFactory func() (*sql.DB, error)
 }
 
 // NewDatabasePasskeyProvider creates a new database-backed passkey provider
@@ -45,6 +51,7 @@ func NewDatabasePasskeyProvider(db *sql.DB, opts DatabasePasskeyProviderOptions)
 
 	return &DatabasePasskeyProvider{
 		db:        db,
+		dbFactory: opts.DBFactory,
 		rpID:      opts.RPID,
 		rpName:    opts.RPName,
 		rpOrigin:  opts.RPOrigin,
@@ -53,6 +60,26 @@ func NewDatabasePasskeyProvider(db *sql.DB, opts DatabasePasskeyProviderOptions)
 	}
 }
 
+func (p *DatabasePasskeyProvider) getDB() *sql.DB {
+	p.dbMu.RLock()
+	defer p.dbMu.RUnlock()
+	return p.db
+}
+
+func (p *DatabasePasskeyProvider) reconnectDB() error {
+	if p.dbFactory == nil {
+		return fmt.Errorf("no db factory configured for reconnect")
+	}
+	newDB, err := p.dbFactory()
+	if err != nil {
+		return err
+	}
+	p.dbMu.Lock()
+	p.db = newDB
+	p.dbMu.Unlock()
+	return nil
+}
+
 // BeginRegistration creates registration options for a new passkey
 func (p *DatabasePasskeyProvider) BeginRegistration(ctx context.Context, userID int, username, displayName string) (*PasskeyRegistrationOptions, error) {
 	// Generate challenge
@@ -140,7 +167,7 @@ func (p *DatabasePasskeyProvider) CompleteRegistration(ctx context.Context, user
 	var credentialID sql.NullInt64
 
 	query := fmt.Sprintf(`SELECT p_success, p_error, p_credential_id FROM %s($1::jsonb)`, p.sqlNames.PasskeyStoreCredential)
-	err = p.db.QueryRowContext(ctx, query, string(credJSON)).Scan(&success, &errorMsg, &credentialID)
+	err = p.getDB().QueryRowContext(ctx, query, string(credJSON)).Scan(&success, &errorMsg, &credentialID)
 	if err != nil {
 		return nil, fmt.Errorf("failed to store credential: %w", err)
 	}
@@ -181,7 +208,7 @@ func (p *DatabasePasskeyProvider) BeginAuthentication(ctx context.Context, usern
 		var credentialsJSON sql.NullString
 
 		query := fmt.Sprintf(`SELECT p_success, p_error, p_user_id, p_credentials::text FROM %s($1)`, p.sqlNames.PasskeyGetCredsByUsername)
-		err := p.db.QueryRowContext(ctx, query, username).Scan(&success, &errorMsg, &userID, &credentialsJSON)
+		err := p.getDB().QueryRowContext(ctx, query, username).Scan(&success, &errorMsg, &userID, &credentialsJSON)
 		if err != nil {
 			return nil, fmt.Errorf("failed to get credentials: %w", err)
 		}
@@ -240,8 +267,16 @@ func (p *DatabasePasskeyProvider) CompleteAuthentication(ctx context.Context, re
 	var errorMsg sql.NullString
 	var credentialJSON sql.NullString
 
+	runQuery := func() error {
 		query := fmt.Sprintf(`SELECT p_success, p_error, p_credential::text FROM %s($1)`, p.sqlNames.PasskeyGetCredential)
-	err := p.db.QueryRowContext(ctx, query, response.RawID).Scan(&success, &errorMsg, &credentialJSON)
+		return p.getDB().QueryRowContext(ctx, query, response.RawID).Scan(&success, &errorMsg, &credentialJSON)
+	}
+	err := runQuery()
+	if isDBClosed(err) {
+		if reconnErr := p.reconnectDB(); reconnErr == nil {
+			err = runQuery()
+		}
+	}
 	if err != nil {
 		return 0, fmt.Errorf("failed to get credential: %w", err)
 	}
@@ -272,7 +307,7 @@ func (p *DatabasePasskeyProvider) CompleteAuthentication(ctx context.Context, re
 	var cloneWarning sql.NullBool
 
 	updateQuery := fmt.Sprintf(`SELECT p_success, p_error, p_clone_warning FROM %s($1, $2)`, p.sqlNames.PasskeyUpdateCounter)
-	err = p.db.QueryRowContext(ctx, updateQuery, response.RawID, newCounter).Scan(&updateSuccess, &updateError, &cloneWarning)
+	err = p.getDB().QueryRowContext(ctx, updateQuery, response.RawID, newCounter).Scan(&updateSuccess, &updateError, &cloneWarning)
 	if err != nil {
 		return 0, fmt.Errorf("failed to update counter: %w", err)
 	}
@@ -291,7 +326,7 @@ func (p *DatabasePasskeyProvider) GetCredentials(ctx context.Context, userID int
 	var credentialsJSON sql.NullString
 
 	query := fmt.Sprintf(`SELECT p_success, p_error, p_credentials::text FROM %s($1)`, p.sqlNames.PasskeyGetUserCredentials)
-	err := p.db.QueryRowContext(ctx, query, userID).Scan(&success, &errorMsg, &credentialsJSON)
+	err := p.getDB().QueryRowContext(ctx, query, userID).Scan(&success, &errorMsg, &credentialsJSON)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get credentials: %w", err)
 	}
@@ -370,7 +405,7 @@ func (p *DatabasePasskeyProvider) DeleteCredential(ctx context.Context, userID i
 	var errorMsg sql.NullString
 
 	query := fmt.Sprintf(`SELECT p_success, p_error FROM %s($1, $2)`, p.sqlNames.PasskeyDeleteCredential)
-	err = p.db.QueryRowContext(ctx, query, userID, credID).Scan(&success, &errorMsg)
+	err = p.getDB().QueryRowContext(ctx, query, userID, credID).Scan(&success, &errorMsg)
 	if err != nil {
 		return fmt.Errorf("failed to delete credential: %w", err)
 	}
@@ -396,7 +431,7 @@ func (p *DatabasePasskeyProvider) UpdateCredentialName(ctx context.Context, user
 	var errorMsg sql.NullString
 
 	query := fmt.Sprintf(`SELECT p_success, p_error FROM %s($1, $2, $3)`, p.sqlNames.PasskeyUpdateName)
-	err = p.db.QueryRowContext(ctx, query, userID, credID, name).Scan(&success, &errorMsg)
+	err = p.getDB().QueryRowContext(ctx, query, userID, credID, name).Scan(&success, &errorMsg)
 	if err != nil {
 		return fmt.Errorf("failed to update credential name: %w", err)
 	}

pkg/security/providers.go

@@ -64,6 +64,8 @@ func (a *HeaderAuthenticator) Authenticate(r *http.Request) (*UserContext, error
 // Also supports passkey authentication configured with WithPasskey()
 type DatabaseAuthenticator struct {
 	db        *sql.DB
+	dbMu      sync.RWMutex
+	dbFactory func() (*sql.DB, error)
 	cache     *cache.Cache
 	cacheTTL  time.Duration
 	sqlNames  *SQLNames
@@ -88,6 +90,9 @@ type DatabaseAuthenticatorOptions struct {
 	// SQLNames provides custom SQL procedure/function names. If nil, uses DefaultSQLNames().
 	// Partial overrides are supported: only set the fields you want to change.
 	SQLNames *SQLNames
+	// DBFactory is called to obtain a fresh *sql.DB when the existing connection is closed.
+	// If nil, reconnection is disabled.
+	DBFactory func() (*sql.DB, error)
 }
 
 func NewDatabaseAuthenticator(db *sql.DB) *DatabaseAuthenticator {
@@ -110,6 +115,7 @@ func NewDatabaseAuthenticatorWithOptions(db *sql.DB, opts DatabaseAuthenticatorO
 
 	return &DatabaseAuthenticator{
 		db:              db,
+		dbFactory:       opts.DBFactory,
 		cache:           cacheInstance,
 		cacheTTL:        opts.CacheTTL,
 		sqlNames:        sqlNames,
@@ -117,6 +123,26 @@ func NewDatabaseAuthenticatorWithOptions(db *sql.DB, opts DatabaseAuthenticatorO
 	}
 }
 
+func (a *DatabaseAuthenticator) getDB() *sql.DB {
+	a.dbMu.RLock()
+	defer a.dbMu.RUnlock()
+	return a.db
+}
+
+func (a *DatabaseAuthenticator) reconnectDB() error {
+	if a.dbFactory == nil {
+		return fmt.Errorf("no db factory configured for reconnect")
+	}
+	newDB, err := a.dbFactory()
+	if err != nil {
+		return err
+	}
+	a.dbMu.Lock()
+	a.db = newDB
+	a.dbMu.Unlock()
+	return nil
+}
+
 func (a *DatabaseAuthenticator) Login(ctx context.Context, req LoginRequest) (*LoginResponse, error) {
 	// Convert LoginRequest to JSON
 	reqJSON, err := json.Marshal(req)
@@ -128,8 +154,16 @@ func (a *DatabaseAuthenticator) Login(ctx context.Context, req LoginRequest) (*L
 	var errorMsg sql.NullString
 	var dataJSON sql.NullString
 
+	runLoginQuery := func() error {
 		query := fmt.Sprintf(`SELECT p_success, p_error, p_data::text FROM %s($1::jsonb)`, a.sqlNames.Login)
-	err = a.db.QueryRowContext(ctx, query, string(reqJSON)).Scan(&success, &errorMsg, &dataJSON)
+		return a.getDB().QueryRowContext(ctx, query, string(reqJSON)).Scan(&success, &errorMsg, &dataJSON)
+	}
+	err = runLoginQuery()
+	if isDBClosed(err) {
+		if reconnErr := a.reconnectDB(); reconnErr == nil {
+			err = runLoginQuery()
+		}
+	}
 	if err != nil {
 		return nil, fmt.Errorf("login query failed: %w", err)
 	}
@@ -163,7 +197,7 @@ func (a *DatabaseAuthenticator) Register(ctx context.Context, req RegisterReques
 	var dataJSON sql.NullString
 
 	query := fmt.Sprintf(`SELECT p_success, p_error, p_data::text FROM %s($1::jsonb)`, a.sqlNames.Register)
-	err = a.db.QueryRowContext(ctx, query, string(reqJSON)).Scan(&success, &errorMsg, &dataJSON)
+	err = a.getDB().QueryRowContext(ctx, query, string(reqJSON)).Scan(&success, &errorMsg, &dataJSON)
 	if err != nil {
 		return nil, fmt.Errorf("register query failed: %w", err)
 	}
@@ -196,7 +230,7 @@ func (a *DatabaseAuthenticator) Logout(ctx context.Context, req LogoutRequest) e
 	var dataJSON sql.NullString
 
 	query := fmt.Sprintf(`SELECT p_success, p_error, p_data::text FROM %s($1::jsonb)`, a.sqlNames.Logout)
-	err = a.db.QueryRowContext(ctx, query, string(reqJSON)).Scan(&success, &errorMsg, &dataJSON)
+	err = a.getDB().QueryRowContext(ctx, query, string(reqJSON)).Scan(&success, &errorMsg, &dataJSON)
 	if err != nil {
 		return fmt.Errorf("logout query failed: %w", err)
 	}
@@ -270,7 +304,7 @@ func (a *DatabaseAuthenticator) Authenticate(r *http.Request) (*UserContext, err
 			var userJSON sql.NullString
 
 			query := fmt.Sprintf(`SELECT p_success, p_error, p_user::text FROM %s($1, $2)`, a.sqlNames.Session)
-			err := a.db.QueryRowContext(r.Context(), query, token, reference).Scan(&success, &errorMsg, &userJSON)
+			err := a.getDB().QueryRowContext(r.Context(), query, token, reference).Scan(&success, &errorMsg, &userJSON)
 			if err != nil {
 				return nil, fmt.Errorf("session query failed: %w", err)
 			}
@@ -346,7 +380,7 @@ func (a *DatabaseAuthenticator) updateSessionActivity(ctx context.Context, sessi
 	var updatedUserJSON sql.NullString
 
 	query := fmt.Sprintf(`SELECT p_success, p_error, p_user::text FROM %s($1, $2::jsonb)`, a.sqlNames.SessionUpdate)
-	_ = a.db.QueryRowContext(ctx, query, sessionToken, string(userJSON)).Scan(&success, &errorMsg, &updatedUserJSON)
+	_ = a.getDB().QueryRowContext(ctx, query, sessionToken, string(userJSON)).Scan(&success, &errorMsg, &updatedUserJSON)
 }
 
 // RefreshToken implements Refreshable interface
@@ -357,7 +391,7 @@ func (a *DatabaseAuthenticator) RefreshToken(ctx context.Context, refreshToken s
 	var userJSON sql.NullString
 	// Get current session to pass to refresh
 	query := fmt.Sprintf(`SELECT p_success, p_error, p_user::text FROM %s($1, $2)`, a.sqlNames.Session)
-	err := a.db.QueryRowContext(ctx, query, refreshToken, "refresh").Scan(&success, &errorMsg, &userJSON)
+	err := a.getDB().QueryRowContext(ctx, query, refreshToken, "refresh").Scan(&success, &errorMsg, &userJSON)
 	if err != nil {
 		return nil, fmt.Errorf("refresh token query failed: %w", err)
 	}
@@ -374,7 +408,7 @@ func (a *DatabaseAuthenticator) RefreshToken(ctx context.Context, refreshToken s
 	var newUserJSON sql.NullString
 
 	refreshQuery := fmt.Sprintf(`SELECT p_success, p_error, p_user::text FROM %s($1, $2::jsonb)`, a.sqlNames.RefreshToken)
-	err = a.db.QueryRowContext(ctx, refreshQuery, refreshToken, userJSON).Scan(&newSuccess, &newErrorMsg, &newUserJSON)
+	err = a.getDB().QueryRowContext(ctx, refreshQuery, refreshToken, userJSON).Scan(&newSuccess, &newErrorMsg, &newUserJSON)
 	if err != nil {
 		return nil, fmt.Errorf("refresh token generation failed: %w", err)
 	}
@@ -406,6 +440,8 @@ func (a *DatabaseAuthenticator) RefreshToken(ctx context.Context, refreshToken s
 type JWTAuthenticator struct {
 	secretKey []byte
 	db        *sql.DB
+	dbMu      sync.RWMutex
+	dbFactory func() (*sql.DB, error)
 	sqlNames  *SQLNames
 }
 
@@ -417,13 +453,47 @@ func NewJWTAuthenticator(secretKey string, db *sql.DB, names ...*SQLNames) *JWTA
 	}
 }
 
+// WithDBFactory configures a factory used to reopen the database connection if it is closed.
+func (a *JWTAuthenticator) WithDBFactory(factory func() (*sql.DB, error)) *JWTAuthenticator {
+	a.dbFactory = factory
+	return a
+}
+
+func (a *JWTAuthenticator) getDB() *sql.DB {
+	a.dbMu.RLock()
+	defer a.dbMu.RUnlock()
+	return a.db
+}
+
+func (a *JWTAuthenticator) reconnectDB() error {
+	if a.dbFactory == nil {
+		return fmt.Errorf("no db factory configured for reconnect")
+	}
+	newDB, err := a.dbFactory()
+	if err != nil {
+		return err
+	}
+	a.dbMu.Lock()
+	a.db = newDB
+	a.dbMu.Unlock()
+	return nil
+}
+
 func (a *JWTAuthenticator) Login(ctx context.Context, req LoginRequest) (*LoginResponse, error) {
 	var success bool
 	var errorMsg sql.NullString
 	var userJSON []byte
 
+	runLoginQuery := func() error {
 		query := fmt.Sprintf(`SELECT p_success, p_error, p_user FROM %s($1, $2)`, a.sqlNames.JWTLogin)
-	err := a.db.QueryRowContext(ctx, query, req.Username, req.Password).Scan(&success, &errorMsg, &userJSON)
+		return a.getDB().QueryRowContext(ctx, query, req.Username, req.Password).Scan(&success, &errorMsg, &userJSON)
+	}
+	err := runLoginQuery()
+	if isDBClosed(err) {
+		if reconnErr := a.reconnectDB(); reconnErr == nil {
+			err = runLoginQuery()
+		}
+	}
 	if err != nil {
 		return nil, fmt.Errorf("login query failed: %w", err)
 	}
@@ -476,7 +546,7 @@ func (a *JWTAuthenticator) Logout(ctx context.Context, req LogoutRequest) error
 	var errorMsg sql.NullString
 
 	query := fmt.Sprintf(`SELECT p_success, p_error FROM %s($1, $2)`, a.sqlNames.JWTLogout)
-	err := a.db.QueryRowContext(ctx, query, req.Token, req.UserID).Scan(&success, &errorMsg)
+	err := a.getDB().QueryRowContext(ctx, query, req.Token, req.UserID).Scan(&success, &errorMsg)
 	if err != nil {
 		return fmt.Errorf("logout query failed: %w", err)
 	}
@@ -514,6 +584,8 @@ func (a *JWTAuthenticator) Authenticate(r *http.Request) (*UserContext, error) {
 // Procedure names are configurable via SQLNames (see DefaultSQLNames for defaults)
 type DatabaseColumnSecurityProvider struct {
 	db        *sql.DB
+	dbMu      sync.RWMutex
+	dbFactory func() (*sql.DB, error)
 	sqlNames  *SQLNames
 }
 
@@ -521,6 +593,31 @@ func NewDatabaseColumnSecurityProvider(db *sql.DB, names ...*SQLNames) *Database
 	return &DatabaseColumnSecurityProvider{db: db, sqlNames: resolveSQLNames(names...)}
 }
 
+func (p *DatabaseColumnSecurityProvider) WithDBFactory(factory func() (*sql.DB, error)) *DatabaseColumnSecurityProvider {
+	p.dbFactory = factory
+	return p
+}
+
+func (p *DatabaseColumnSecurityProvider) getDB() *sql.DB {
+	p.dbMu.RLock()
+	defer p.dbMu.RUnlock()
+	return p.db
+}
+
+func (p *DatabaseColumnSecurityProvider) reconnectDB() error {
+	if p.dbFactory == nil {
+		return fmt.Errorf("no db factory configured for reconnect")
+	}
+	newDB, err := p.dbFactory()
+	if err != nil {
+		return err
+	}
+	p.dbMu.Lock()
+	p.db = newDB
+	p.dbMu.Unlock()
+	return nil
+}
+
 func (p *DatabaseColumnSecurityProvider) GetColumnSecurity(ctx context.Context, userID int, schema, table string) ([]ColumnSecurity, error) {
 	var rules []ColumnSecurity
 
@@ -528,8 +625,16 @@ func (p *DatabaseColumnSecurityProvider) GetColumnSecurity(ctx context.Context,
 	var errorMsg sql.NullString
 	var rulesJSON []byte
 
+	runQuery := func() error {
 		query := fmt.Sprintf(`SELECT p_success, p_error, p_rules FROM %s($1, $2, $3)`, p.sqlNames.ColumnSecurity)
-	err := p.db.QueryRowContext(ctx, query, userID, schema, table).Scan(&success, &errorMsg, &rulesJSON)
+		return p.getDB().QueryRowContext(ctx, query, userID, schema, table).Scan(&success, &errorMsg, &rulesJSON)
+	}
+	err := runQuery()
+	if isDBClosed(err) {
+		if reconnErr := p.reconnectDB(); reconnErr == nil {
+			err = runQuery()
+		}
+	}
 	if err != nil {
 		return nil, fmt.Errorf("failed to load column security: %w", err)
 	}
@@ -579,6 +684,8 @@ func (p *DatabaseColumnSecurityProvider) GetColumnSecurity(ctx context.Context,
 // Procedure names are configurable via SQLNames (see DefaultSQLNames for defaults)
 type DatabaseRowSecurityProvider struct {
 	db        *sql.DB
+	dbMu      sync.RWMutex
+	dbFactory func() (*sql.DB, error)
 	sqlNames  *SQLNames
 }
 
@@ -586,13 +693,45 @@ func NewDatabaseRowSecurityProvider(db *sql.DB, names ...*SQLNames) *DatabaseRow
 	return &DatabaseRowSecurityProvider{db: db, sqlNames: resolveSQLNames(names...)}
 }
 
+func (p *DatabaseRowSecurityProvider) WithDBFactory(factory func() (*sql.DB, error)) *DatabaseRowSecurityProvider {
+	p.dbFactory = factory
+	return p
+}
+
+func (p *DatabaseRowSecurityProvider) getDB() *sql.DB {
+	p.dbMu.RLock()
+	defer p.dbMu.RUnlock()
+	return p.db
+}
+
+func (p *DatabaseRowSecurityProvider) reconnectDB() error {
+	if p.dbFactory == nil {
+		return fmt.Errorf("no db factory configured for reconnect")
+	}
+	newDB, err := p.dbFactory()
+	if err != nil {
+		return err
+	}
+	p.dbMu.Lock()
+	p.db = newDB
+	p.dbMu.Unlock()
+	return nil
+}
+
 func (p *DatabaseRowSecurityProvider) GetRowSecurity(ctx context.Context, userID int, schema, table string) (RowSecurity, error) {
 	var template string
 	var hasBlock bool
 
+	runQuery := func() error {
 		query := fmt.Sprintf(`SELECT p_template, p_block FROM %s($1, $2, $3)`, p.sqlNames.RowSecurity)
-
+		return p.getDB().QueryRowContext(ctx, query, schema, table, userID).Scan(&template, &hasBlock)
-	err := p.db.QueryRowContext(ctx, query, schema, table, userID).Scan(&template, &hasBlock)
+	}
+	err := runQuery()
+	if isDBClosed(err) {
+		if reconnErr := p.reconnectDB(); reconnErr == nil {
+			err = runQuery()
+		}
+	}
 	if err != nil {
 		return RowSecurity{}, fmt.Errorf("failed to load row security: %w", err)
 	}
@@ -662,6 +801,11 @@ func (p *ConfigRowSecurityProvider) GetRowSecurity(ctx context.Context, userID i
 // Helper functions
 // ================
 
+// isDBClosed reports whether err indicates the *sql.DB has been closed.
+func isDBClosed(err error) bool {
+	return err != nil && strings.Contains(err.Error(), "sql: database is closed")
+}
+
 func parseRoles(rolesStr string) []string {
 	if rolesStr == "" {
 		return []string{}
@@ -780,8 +924,16 @@ func (a *DatabaseAuthenticator) LoginWithPasskey(ctx context.Context, req Passke
 	var errorMsg sql.NullString
 	var dataJSON sql.NullString
 
+	runPasskeyQuery := func() error {
 		query := fmt.Sprintf(`SELECT p_success, p_error, p_data::text FROM %s($1::jsonb)`, a.sqlNames.PasskeyLogin)
-	err = a.db.QueryRowContext(ctx, query, string(reqJSON)).Scan(&success, &errorMsg, &dataJSON)
+		return a.getDB().QueryRowContext(ctx, query, string(reqJSON)).Scan(&success, &errorMsg, &dataJSON)
+	}
+	err = runPasskeyQuery()
+	if isDBClosed(err) {
+		if reconnErr := a.reconnectDB(); reconnErr == nil {
+			err = runPasskeyQuery()
+		}
+	}
 	if err != nil {
 		return nil, fmt.Errorf("passkey login query failed: %w", err)
 	}

pkg/security/sql_names.go

@@ -54,6 +54,13 @@ type SQLNames struct {
 	OAuthUpdateRefreshToken string // default: "resolvespec_oauth_updaterefreshtoken"
 	OAuthGetUser            string // default: "resolvespec_oauth_getuser"
 
+	// OAuth2 server procedures (OAuthServer persistence)
+	OAuthRegisterClient string // default: "resolvespec_oauth_register_client"
+	OAuthGetClient      string // default: "resolvespec_oauth_get_client"
+	OAuthSaveCode       string // default: "resolvespec_oauth_save_code"
+	OAuthExchangeCode   string // default: "resolvespec_oauth_exchange_code"
+	OAuthIntrospect     string // default: "resolvespec_oauth_introspect"
+	OAuthRevoke         string // default: "resolvespec_oauth_revoke"
 }
 
 // DefaultSQLNames returns an SQLNames with all default resolvespec_* values.
@@ -93,6 +100,13 @@ func DefaultSQLNames() *SQLNames {
 		OAuthGetRefreshToken:    "resolvespec_oauth_getrefreshtoken",
 		OAuthUpdateRefreshToken: "resolvespec_oauth_updaterefreshtoken",
 		OAuthGetUser:            "resolvespec_oauth_getuser",
+
+		OAuthRegisterClient: "resolvespec_oauth_register_client",
+		OAuthGetClient:      "resolvespec_oauth_get_client",
+		OAuthSaveCode:       "resolvespec_oauth_save_code",
+		OAuthExchangeCode:   "resolvespec_oauth_exchange_code",
+		OAuthIntrospect:     "resolvespec_oauth_introspect",
+		OAuthRevoke:         "resolvespec_oauth_revoke",
 	}
 }
 
@@ -191,6 +205,24 @@ func MergeSQLNames(base, override *SQLNames) *SQLNames {
 	if override.OAuthGetUser != "" {
 		merged.OAuthGetUser = override.OAuthGetUser
 	}
+	if override.OAuthRegisterClient != "" {
+		merged.OAuthRegisterClient = override.OAuthRegisterClient
+	}
+	if override.OAuthGetClient != "" {
+		merged.OAuthGetClient = override.OAuthGetClient
+	}
+	if override.OAuthSaveCode != "" {
+		merged.OAuthSaveCode = override.OAuthSaveCode
+	}
+	if override.OAuthExchangeCode != "" {
+		merged.OAuthExchangeCode = override.OAuthExchangeCode
+	}
+	if override.OAuthIntrospect != "" {
+		merged.OAuthIntrospect = override.OAuthIntrospect
+	}
+	if override.OAuthRevoke != "" {
+		merged.OAuthRevoke = override.OAuthRevoke
+	}
 	return &merged
 }
 

pkg/server/example_test.go

@@ -3,6 +3,7 @@ package server_test
 import (
 	"context"
 	"fmt"
+	"log"
 	"net/http"
 	"time"
 
@@ -29,18 +30,18 @@ func ExampleManager_basic() {
 		GZIP:    true, // Enable GZIP compression
 	})
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Start all servers
 	if err := mgr.StartAll(); err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Server is now running...
 	// When done, stop gracefully
 	if err := mgr.StopAll(); err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 }
 
@@ -61,7 +62,7 @@ func ExampleManager_https() {
 		SSLKey:  "/path/to/key.pem",
 	})
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Option 2: Self-signed certificate (for development)
@@ -73,7 +74,7 @@ func ExampleManager_https() {
 		SelfSignedSSL: true,
 	})
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Option 3: Let's Encrypt / AutoTLS (for production)
@@ -88,12 +89,12 @@ func ExampleManager_https() {
 		AutoTLSCacheDir: "./certs-cache",
 	})
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Start all servers
 	if err := mgr.StartAll(); err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Cleanup
@@ -136,7 +137,7 @@ func ExampleManager_gracefulShutdown() {
 		IdleTimeout:     120 * time.Second,
 	})
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Start servers and block until shutdown signal (SIGINT/SIGTERM)
@@ -164,7 +165,7 @@ func ExampleManager_healthChecks() {
 		Handler: mux,
 	})
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Add health and readiness endpoints
@@ -173,7 +174,7 @@ func ExampleManager_healthChecks() {
 
 	// Start the server
 	if err := mgr.StartAll(); err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Health check returns:
@@ -204,7 +205,7 @@ func ExampleManager_multipleServers() {
 		GZIP:    true,
 	})
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Admin API server (different port)
@@ -218,7 +219,7 @@ func ExampleManager_multipleServers() {
 		Handler: adminHandler,
 	})
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Metrics server (internal only)
@@ -232,18 +233,18 @@ func ExampleManager_multipleServers() {
 		Handler: metricsHandler,
 	})
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Start all servers at once
 	if err := mgr.StartAll(); err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Get specific server instance
 	publicInstance, err := mgr.Get("public-api")
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 	fmt.Printf("Public API running on: %s\n", publicInstance.Addr())
 
@@ -253,7 +254,7 @@ func ExampleManager_multipleServers() {
 
 	// Stop all servers gracefully (in parallel)
 	if err := mgr.StopAll(); err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 }
 
@@ -273,11 +274,11 @@ func ExampleManager_monitoring() {
 		Handler: handler,
 	})
 	if err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	if err := mgr.StartAll(); err != nil {
-		panic(err)
+		log.Fatal(err)
 	}
 
 	// Check server status