package jsplugin

import (
	"context"
	"errors"
	"fmt"
	"maps"
	"math"
	"net/url"
	"regexp"
	"slices"
	"sort"
	"strings"
	"sync"
	"sync/atomic"
	"time"
	"unicode"
	"unicode/utf8"

	"github.com/QuantumNous/new-api/common"
	"github.com/QuantumNous/new-api/constant"
	"github.com/QuantumNous/new-api/logger"
	relaycommon "github.com/QuantumNous/new-api/relay/common"
	"github.com/QuantumNous/new-api/relaykit/dto"
)

const APIVersion1 = 1

const (
	maxLocalizedTextLocales       = 16
	maxMetaDescriptionRunes       = 512
	maxUsageFieldDescriptionRunes = 256
)

var pluginKeyPattern = regexp.MustCompile(`^[a-z0-9][a-z0-9_-]*$`)
var pluginVersionPattern = regexp.MustCompile(`^(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)\.(0|[1-9][0-9]*)(?:-[0-9A-Za-z.-]+)?(?:\+[0-9A-Za-z.-]+)?$`)
var localeTagPattern = regexp.MustCompile(`^[a-zA-Z]{2,3}(-[a-zA-Z0-9]{2,8})*$`)

// LocalizedText is locale-keyed display copy. Plugin source may use a bare
// string (normalized to {"en": s}) or a map that must include "en". API
// responses always emit an object.
type LocalizedText map[string]string

func (t LocalizedText) MarshalJSON() ([]byte, error) {
	if t == nil {
		return common.Marshal(map[string]string{})
	}
	return common.Marshal(map[string]string(t))
}

func (t *LocalizedText) UnmarshalJSON(data []byte) error {
	trimmed := strings.TrimSpace(string(data))
	if trimmed == "" || trimmed == "null" {
		*t = nil
		return nil
	}
	switch trimmed[0] {
	case '"':
		var text string
		if err := common.Unmarshal(data, &text); err != nil {
			return err
		}
		*t = LocalizedText{"en": text}
		return nil
	case '{':
		var object map[string]string
		if err := common.Unmarshal(data, &object); err != nil {
			return err
		}
		*t = LocalizedText(object)
		return nil
	default:
		return fmt.Errorf("localized text must be a string or object")
	}
}

type Meta struct {
	APIVersion    int                         `json:"apiVersion"`
	Key           string                      `json:"key"`
	Name          string                      `json:"name"`
	Icon          string                      `json:"icon,omitempty"`
	Description   LocalizedText               `json:"description,omitempty"`
	Version       string                      `json:"version"`
	Author        AuthorMeta                  `json:"author"`
	ChannelTypes  []int                       `json:"channelTypes,omitempty"`
	Models        []string                    `json:"models"`
	FetchMode     string                      `json:"fetchMode"`
	AllowedHosts  []string                    `json:"allowedHosts"`
	Routes        []Route                     `json:"routes"`
	Protocols     []ProtocolClaim             `json:"protocols"`
	UsageSchema   map[string]UsageFieldSchema `json:"usageSchema,omitempty"`
	UsageExamples []UsageExample              `json:"usageExamples,omitempty"`
	Auth          AuthMeta                    `json:"auth"`
}

// ProtocolSupports reports whether the named protocol claim includes mode.
func (m Meta) ProtocolSupports(protocol, mode string) bool {
	for _, claim := range m.Protocols {
		if claim.Name == protocol {
			return slices.Contains(claim.Supports, mode)
		}
	}
	return false
}

// UsageExample is a display-only pricing sample: a labeled complete vector
// over usageSchema. It never participates in billing.
type UsageExample struct {
	Label string         `json:"label"`
	Facts map[string]any `json:"facts"`
}

type AuthorMeta struct {
	Name string `json:"name"`
	URL  string `json:"url,omitempty"`
}

type AuthMeta struct {
	Type string `json:"type"`
}

// UsageFieldSchema declares how one usage fact is validated before it can
// influence billing. Numeric facts use one of the host-owned canonical units;
// boolean facts are flags; enum facts constrain non-numeric pricing selectors.
type UsageFieldSchema struct {
	Type        string        `json:"type,omitempty"`
	Unit        string        `json:"unit,omitempty"`
	Enum        []string      `json:"enum,omitempty"`
	Description LocalizedText `json:"description,omitempty"`
}

type LoadedPlugin struct {
	Meta   Meta
	Engine *Engine
}

// RegistrySnapshot is a read-only copy of the metadata currently stored in
// each registry layer.
type RegistrySnapshot struct {
	Factory         []Meta
	Override        []Meta
	DisabledFactory []string
}

type PreparedRoutingGeneration struct {
	Generation *RoutingGeneration
	Errors     map[string]string
}

type RoutingRebuildOutcome struct {
	Status      string    `json:"status"`
	AttemptedAt time.Time `json:"attempted_at"`
	Generation  uint64    `json:"generation"`
	Error       string    `json:"error,omitempty"`
}

type RoutingStatus struct {
	Generation  *RoutingGeneration
	LastRebuild RoutingRebuildOutcome
	Errors      map[string]string
}

type RoutingGenerationPreparer func(candidate, current *RoutingGeneration) (PreparedRoutingGeneration, error)

type Registry struct {
	mu              sync.RWMutex
	factory         map[string]*LoadedPlugin
	override        map[string]*LoadedPlugin
	activeOverride  map[string]*LoadedPlugin
	disabledFactory map[string]struct{}
	masterEnabled   atomic.Bool
	overrideEnabled atomic.Bool
	generation      atomic.Pointer[RoutingGeneration]
	preparer        RoutingGenerationPreparer
	routingErrors   map[string]string
	lastRebuildErr  string
	lastRebuild     RoutingRebuildOutcome
}

func NewRegistry() *Registry {
	registry := &Registry{
		factory:        make(map[string]*LoadedPlugin),
		override:       make(map[string]*LoadedPlugin),
		activeOverride: make(map[string]*LoadedPlugin),
		routingErrors:  make(map[string]string),
	}
	registry.masterEnabled.Store(true)
	registry.overrideEnabled.Store(true)
	generation, _ := buildRoutingGeneration(registry.factory, registry.override, true, 0)
	registry.generation.Store(generation)
	registry.lastRebuild = RoutingRebuildOutcome{
		Status:      "success",
		AttemptedAt: generation.PublishedAt,
		Generation:  generation.Number,
	}
	return registry
}

var DefaultRegistry = NewRegistry()

func (r *Registry) Register(source string, options Options) (*LoadedPlugin, error) {
	return r.register(source, options, false)
}

func (r *Registry) RegisterFactory(source string, options Options) (*LoadedPlugin, error) {
	return r.register(source, options, true)
}

func (r *Registry) register(source string, options Options, factory bool) (*LoadedPlugin, error) {
	plugin, err := CompilePlugin(source, options)
	if err != nil {
		return nil, err
	}
	r.mu.Lock()
	defer r.mu.Unlock()

	factoryPlugins := clonePluginMap(r.factory)
	overridePlugins := clonePluginMap(r.override)
	if factory {
		factoryPlugins[plugin.Meta.Key] = plugin
	} else {
		overridePlugins[plugin.Meta.Key] = plugin
	}
	enabled := r.overrideEnabled.Load()
	generation, routingErrors, err := r.prepareGeneration(filterDisabledFactory(factoryPlugins, r.disabledFactory), overridePlugins, enabled, false, nil)
	if err != nil {
		r.recordRebuildFailure(err)
		return nil, err
	}
	if rejection := routingErrors[plugin.Meta.Key]; rejection != "" {
		r.recordRebuildFailure(errors.New(rejection))
		return nil, fmt.Errorf("%s", rejection)
	}
	r.factory = factoryPlugins
	r.override = overridePlugins
	r.publishGeneration(generation, routingErrors, r.resolveActiveOverrides(generation, overridePlugins, enabled))
	return plugin, nil
}

// CompilePlugin validates a plugin without publishing it. Callers that refresh
// multiple plugins use this together with ReplaceOverrides so readers observe a
// single generation transition.
func CompilePlugin(source string, options Options) (*LoadedPlugin, error) {
	engine, err := Compile(source, options)
	if err != nil {
		return nil, err
	}
	value, err := engine.Export(context.Background(), "meta")
	if err != nil {
		return nil, err
	}
	meta, err := decodeMeta(value)
	if err != nil {
		return nil, err
	}
	if err = normalizeV1Meta(&meta); err != nil {
		return nil, err
	}
	engine.key = meta.Key
	engine.version = meta.Version
	requiredHooks := []string{"buildSubmitRequest", "parseSubmitResponse", "parseTaskResult"}
	if meta.FetchMode == "batch" {
		requiredHooks = append(requiredHooks, "buildBatchQueryRequest", "parseBatchResult")
	} else {
		requiredHooks = append(requiredHooks, "buildQueryRequest")
	}
	for _, hook := range requiredHooks {
		has, hasErr := engine.HasCallablePath(context.Background(), hook)
		if hasErr != nil {
			return nil, hasErr
		}
		if !has {
			return nil, fmt.Errorf("plugin %s is missing required export %q", meta.Key, hook)
		}
	}
	artifactHooks := make(map[string]bool, 2)
	for _, hook := range []string{"listArtifacts", "buildContentRequest"} {
		exported, exportErr := engine.HasExport(context.Background(), hook)
		if exportErr != nil {
			return nil, exportErr
		}
		if !exported {
			continue
		}
		callable, callableErr := engine.HasCallablePath(context.Background(), hook)
		if callableErr != nil {
			return nil, callableErr
		}
		if !callable {
			return nil, fmt.Errorf("plugin %s export %q is not a function", meta.Key, hook)
		}
		artifactHooks[hook] = true
	}
	if artifactHooks["listArtifacts"] != artifactHooks["buildContentRequest"] {
		return nil, fmt.Errorf("plugin %s must export listArtifacts and buildContentRequest together", meta.Key)
	}
	for _, route := range meta.Routes {
		for kind, member := range map[string]string{"decode": route.Decode, "render": route.Render} {
			if member == "" {
				continue
			}
			has, hasErr := engine.HasCallablePath(context.Background(), "native", member)
			if hasErr != nil {
				return nil, hasErr
			}
			if !has {
				return nil, fmt.Errorf("plugin %s route %s %s references missing native %s %q", meta.Key, route.Method, route.Path, kind, member)
			}
		}
	}
	for _, claim := range meta.Protocols {
		protocol := claim.Name
		definition, _ := HostProtocol(protocol)
		required := make(map[string]struct{})
		allowed := make(map[string]struct{})
		modeHookUsers := make(map[string][]string)
		for _, operation := range definition.Operations {
			for _, hook := range operation.RequiredProtocolMembers {
				required[hook] = struct{}{}
				allowed[hook] = struct{}{}
			}
			for _, mode := range operation.Modes {
				allowed[mode.Hook] = struct{}{}
				if !slices.Contains(modeHookUsers[mode.Hook], mode.Name) {
					modeHookUsers[mode.Hook] = append(modeHookUsers[mode.Hook], mode.Name)
				}
				if slices.Contains(claim.Supports, mode.Name) {
					required[mode.Hook] = struct{}{}
				}
			}
			for _, hook := range operation.RequiredDriverHooks {
				has, hasErr := engine.HasCallablePath(context.Background(), hook)
				if hasErr != nil {
					return nil, hasErr
				}
				if !has {
					return nil, fmt.Errorf("plugin %s protocol %q is missing driver hook %q", meta.Key, protocol, hook)
				}
			}
		}
		requiredHooks := make([]string, 0, len(required))
		for hook := range required {
			requiredHooks = append(requiredHooks, hook)
		}
		sort.Strings(requiredHooks)
		for _, hook := range requiredHooks {
			has, hasErr := engine.HasCallablePath(context.Background(), "protocols", protocol, hook)
			if hasErr != nil {
				return nil, hasErr
			}
			if !has {
				if users := modeHookUsers[hook]; len(users) > 0 {
					mentioned := ""
					for _, name := range claim.Supports {
						if slices.Contains(users, name) {
							mentioned = name
							break
						}
					}
					suggested := make([]string, 0)
					for _, mode := range definition.DefinedModes() {
						exported, exportedErr := engine.HasCallablePath(context.Background(), "protocols", protocol, mode.Hook)
						if exportedErr != nil {
							return nil, exportedErr
						}
						if exported && !slices.Contains(suggested, mode.Name) {
							suggested = append(suggested, mode.Name)
						}
					}
					message := fmt.Sprintf("plugin %s protocol %q supports %q but does not export protocols.%s.%s; implement it", meta.Key, protocol, mentioned, protocol, hook)
					if len(suggested) > 0 {
						message += fmt.Sprintf(" or declare supports: [%s]", quotedJoin(suggested, ", "))
					}
					return nil, errors.New(message)
				}
				return nil, fmt.Errorf("plugin %s protocol %q is missing hook %q", meta.Key, protocol, hook)
			}
		}
		seenModeHook := make(map[string]struct{})
		for _, operation := range definition.Operations {
			for _, mode := range operation.Modes {
				if _, seen := seenModeHook[mode.Hook]; seen {
					continue
				}
				seenModeHook[mode.Hook] = struct{}{}
				if _, need := required[mode.Hook]; need {
					continue
				}
				has, hasErr := engine.HasCallablePath(context.Background(), "protocols", protocol, mode.Hook)
				if hasErr != nil {
					return nil, hasErr
				}
				if has {
					return nil, fmt.Errorf("plugin %s protocol %q exports protocols.%s.%s but no supported mode uses it; add %s to supports or remove the hook", meta.Key, protocol, protocol, mode.Hook, quotedJoin(modeHookUsers[mode.Hook], " or "))
				}
			}
		}
		protocolValue, exportErr := engine.Export(context.Background(), "protocols")
		if exportErr != nil {
			return nil, exportErr
		}
		protocolObject, ok := protocolValue.(map[string]any)
		if !ok {
			return nil, fmt.Errorf("plugin %s export protocols must be an object", meta.Key)
		}
		implementation, ok := protocolObject[protocol].(map[string]any)
		if !ok {
			return nil, fmt.Errorf("plugin %s protocol %q must be an object", meta.Key, protocol)
		}
		for member := range implementation {
			if _, accepted := allowed[member]; !accepted {
				return nil, fmt.Errorf("plugin %s protocol %q has unsupported member %q", meta.Key, protocol, member)
			}
		}
	}
	if protocolsValue, exportErr := engine.Export(context.Background(), "protocols"); exportErr == nil {
		if protocolsObject, ok := protocolsValue.(map[string]any); ok {
			claimed := make(map[string]struct{}, len(meta.Protocols))
			for _, claim := range meta.Protocols {
				claimed[claim.Name] = struct{}{}
			}
			for name := range protocolsObject {
				if _, ok := claimed[name]; !ok {
					return nil, fmt.Errorf("plugin %s implements unclaimed protocol %q", meta.Key, name)
				}
			}
		}
	}
	for _, removed := range []string{"resolveRequest", "renderError", "renderers"} {
		has, e := engine.HasExport(context.Background(), removed)
		if e != nil {
			return nil, e
		}
		if has {
			return nil, fmt.Errorf("plugin %s export %q is no longer supported", meta.Key, removed)
		}
	}
	return &LoadedPlugin{Meta: meta, Engine: engine}, nil
}

func (r *Registry) Get(platform string) (*LoadedPlugin, bool) {
	return r.Generation().Get(platform)
}

func (r *Registry) GetByChannelType(channelType int) (*LoadedPlugin, bool) {
	return r.Generation().GetByChannelType(channelType)
}

// Enabled reports the master switch position. When false the published
// routing generation contains no plugins regardless of the other layers.
func (r *Registry) Enabled() bool {
	return r.masterEnabled.Load()
}

func (r *Registry) SetEnabled(enabled bool) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if r.masterEnabled.Load() == enabled {
		return
	}
	previous := r.masterEnabled.Load()
	r.masterEnabled.Store(enabled)
	overrideEnabled := r.overrideEnabled.Load()
	var retainCurrent map[string]struct{}
	if enabled && overrideEnabled {
		retainCurrent = pluginMapKeys(r.override)
	}
	generation, routingErrors, err := r.prepareGeneration(filterDisabledFactory(r.factory, r.disabledFactory), r.override, overrideEnabled, true, retainCurrent)
	if err != nil {
		r.masterEnabled.Store(previous)
		r.recordRebuildFailure(err)
		return
	}
	r.publishGeneration(generation, routingErrors, r.resolveActiveOverrides(generation, r.override, overrideEnabled))
}

func (r *Registry) SetOverrideEnabled(enabled bool) {
	r.mu.Lock()
	defer r.mu.Unlock()
	if r.overrideEnabled.Load() == enabled {
		return
	}
	var retainCurrent map[string]struct{}
	if enabled {
		retainCurrent = pluginMapKeys(r.override)
	}
	generation, routingErrors, err := r.prepareGeneration(filterDisabledFactory(r.factory, r.disabledFactory), r.override, enabled, true, retainCurrent)
	if err != nil {
		r.recordRebuildFailure(err)
		return
	}
	r.overrideEnabled.Store(enabled)
	r.publishGeneration(generation, routingErrors, r.resolveActiveOverrides(generation, r.override, enabled))
}

func (r *Registry) SetDisabledFactoryKeys(keys []string) {
	r.mu.Lock()
	defer r.mu.Unlock()

	next := make(map[string]struct{}, len(keys))
	for _, key := range keys {
		key = strings.TrimSpace(key)
		if key == "" {
			continue
		}
		next[key] = struct{}{}
	}
	if len(next) == len(r.disabledFactory) {
		same := true
		for key := range next {
			if _, ok := r.disabledFactory[key]; !ok {
				same = false
				break
			}
		}
		if same {
			return
		}
	}

	enabled := r.overrideEnabled.Load()
	var retainCurrent map[string]struct{}
	if enabled {
		retainCurrent = pluginMapKeys(r.override)
	}
	generation, routingErrors, err := r.prepareGeneration(filterDisabledFactory(r.factory, next), r.override, enabled, true, retainCurrent)
	if err != nil {
		r.recordRebuildFailure(err)
		return
	}
	r.disabledFactory = next
	r.publishGeneration(generation, routingErrors, r.resolveActiveOverrides(generation, r.override, enabled))
}

func (r *Registry) Unregister(key string) error {
	r.mu.Lock()
	defer r.mu.Unlock()
	if _, exists := r.override[key]; !exists {
		return nil
	}
	overridePlugins := clonePluginMap(r.override)
	delete(overridePlugins, key)
	enabled := r.overrideEnabled.Load()
	var retainCurrent map[string]struct{}
	if enabled {
		retainCurrent = pluginMapKeys(overridePlugins)
	}
	generation, routingErrors, err := r.prepareGeneration(filterDisabledFactory(r.factory, r.disabledFactory), overridePlugins, enabled, true, retainCurrent)
	if err != nil {
		r.recordRebuildFailure(err)
		return err
	}
	r.override = overridePlugins
	r.publishGeneration(generation, routingErrors, r.resolveActiveOverrides(generation, overridePlugins, enabled))
	return nil
}

// ReplaceOverrides atomically publishes a complete override layer.
func (r *Registry) ReplaceOverrides(plugins []*LoadedPlugin) error {
	overridePlugins := make(map[string]*LoadedPlugin, len(plugins))
	for _, plugin := range plugins {
		if plugin == nil {
			return fmt.Errorf("cannot publish a nil plugin")
		}
		if _, exists := overridePlugins[plugin.Meta.Key]; exists {
			return fmt.Errorf("duplicate override plugin key %q", plugin.Meta.Key)
		}
		overridePlugins[plugin.Meta.Key] = plugin
	}

	r.mu.Lock()
	defer r.mu.Unlock()
	if samePluginMap(r.override, overridePlugins) {
		return nil
	}
	enabled := r.overrideEnabled.Load()
	var retainCurrent map[string]struct{}
	if enabled {
		retainCurrent = pluginMapKeys(overridePlugins)
	}
	generation, routingErrors, err := r.prepareGeneration(filterDisabledFactory(r.factory, r.disabledFactory), overridePlugins, enabled, true, retainCurrent)
	if err != nil {
		r.recordRebuildFailure(err)
		return err
	}
	r.override = overridePlugins
	r.publishGeneration(generation, routingErrors, r.resolveActiveOverrides(generation, overridePlugins, enabled))
	return nil
}

func (r *Registry) Generation() *RoutingGeneration {
	return r.generation.Load()
}

func (r *Registry) OverridePlugins() map[string]*LoadedPlugin {
	r.mu.RLock()
	defer r.mu.RUnlock()
	return clonePluginMap(r.override)
}

func (r *Registry) ActiveOverridePlugins() map[string]*LoadedPlugin {
	r.mu.RLock()
	defer r.mu.RUnlock()
	return clonePluginMap(r.activeOverride)
}

func (r *Registry) SetGenerationPreparer(preparer RoutingGenerationPreparer) error {
	r.mu.Lock()
	defer r.mu.Unlock()

	previous := r.preparer
	r.preparer = preparer
	enabled := r.overrideEnabled.Load()
	var retainCurrent map[string]struct{}
	if enabled {
		retainCurrent = pluginMapKeys(r.override)
	}
	generation, routingErrors, err := r.prepareGeneration(filterDisabledFactory(r.factory, r.disabledFactory), r.override, enabled, true, retainCurrent)
	if err != nil {
		r.preparer = previous
		r.recordRebuildFailure(err)
		return err
	}
	r.publishGeneration(generation, routingErrors, r.resolveActiveOverrides(generation, r.override, enabled))
	return nil
}

func (r *Registry) RoutingErrors() map[string]string {
	r.mu.RLock()
	defer r.mu.RUnlock()
	errorsCopy := make(map[string]string, len(r.routingErrors))
	maps.Copy(errorsCopy, r.routingErrors)
	return errorsCopy
}

func (r *Registry) LastRebuildError() string {
	r.mu.RLock()
	defer r.mu.RUnlock()
	return r.lastRebuildErr
}

func (r *Registry) LastRebuildOutcome() RoutingRebuildOutcome {
	r.mu.RLock()
	defer r.mu.RUnlock()
	return r.lastRebuild
}

func (r *Registry) RoutingStatus() RoutingStatus {
	r.mu.RLock()
	defer r.mu.RUnlock()
	errorsCopy := make(map[string]string, len(r.routingErrors))
	maps.Copy(errorsCopy, r.routingErrors)
	return RoutingStatus{
		Generation:  r.generation.Load(),
		LastRebuild: r.lastRebuild,
		Errors:      errorsCopy,
	}
}

func (r *Registry) prepareGeneration(
	factory, override map[string]*LoadedPlugin,
	enabled, tolerateConflicts bool,
	retainCurrent map[string]struct{},
) (*RoutingGeneration, map[string]string, error) {
	if !r.masterEnabled.Load() {
		factory = map[string]*LoadedPlugin{}
		override = map[string]*LoadedPlugin{}
	}
	current := r.generation.Load()
	number := uint64(1)
	if current != nil {
		number = current.Number + 1
	}
	var (
		generation    *RoutingGeneration
		routingErrors map[string]string
		err           error
	)
	if tolerateConflicts {
		generation, routingErrors, err = buildRoutingGenerationAdmitting(factory, override, enabled, number, current, retainCurrent)
	} else {
		generation, err = buildRoutingGeneration(factory, override, enabled, number)
		routingErrors = make(map[string]string)
	}
	if err != nil {
		return nil, nil, err
	}
	if !tolerateConflicts {
		// Both runtime switch positions must remain publishable so toggling the
		// override layer never exposes an invalid generation.
		if _, err = buildRoutingGeneration(factory, override, !enabled, number); err != nil {
			return nil, nil, err
		}
	}
	if r.preparer != nil {
		prepared, prepareErr := r.preparer(generation, current)
		if prepareErr != nil {
			return nil, nil, prepareErr
		}
		if prepared.Generation == nil {
			return nil, nil, fmt.Errorf("routing generation preparer returned a nil generation")
		}
		if prepared.Generation.Number != generation.Number {
			return nil, nil, fmt.Errorf("routing generation preparer changed generation number from %d to %d", generation.Number, prepared.Generation.Number)
		}
		generation = prepared.Generation
		maps.Copy(routingErrors, prepared.Errors)
	}
	return generation, routingErrors, nil
}

func (r *Registry) publishGeneration(
	generation *RoutingGeneration,
	routingErrors map[string]string,
	activeOverride map[string]*LoadedPlugin,
) {
	previous := r.generation.Load()
	var previousNumber uint64
	if previous != nil {
		previousNumber = previous.Number
	}
	r.routingErrors = routingErrors
	r.activeOverride = activeOverride
	r.lastRebuildErr = ""
	status := "success"
	if len(routingErrors) > 0 {
		status = "partial"
	}
	r.lastRebuild = RoutingRebuildOutcome{
		Status:      status,
		AttemptedAt: time.Now(),
		Generation:  generation.Number,
	}
	r.generation.Store(generation)
	logger.LogDebug(
		context.Background(),
		"task_plugin subsystem=registry event=publish previous_generation=%d generation=%d status=%q plugins=%d routes=%d endpoint_bindings=%d channel_types=%d active_overrides=%d rejected=%d",
		previousNumber,
		generation.Number,
		status,
		len(generation.plugins),
		len(generation.routes),
		len(generation.protocolIndex),
		len(generation.byChannelType),
		len(activeOverride),
		len(routingErrors),
	)
	if len(routingErrors) > 0 {
		keys := make([]string, 0, len(routingErrors))
		for key := range routingErrors {
			keys = append(keys, key)
		}
		sort.Strings(keys)
		for _, key := range keys {
			logger.LogDebug(
				context.Background(),
				"task_plugin subsystem=registry event=plugin_rejected generation=%d plugin=%q reason=generation_admission_failed admission_reason=%q",
				generation.Number,
				key,
				taskPluginRoutingDebugReason(routingErrors[key]),
			)
		}
	}
}

func (r *Registry) recordRebuildFailure(err error) {
	r.lastRebuildErr = err.Error()
	generation := r.generation.Load()
	var generationNumber uint64
	if generation != nil {
		generationNumber = generation.Number
	}
	r.lastRebuild = RoutingRebuildOutcome{
		Status:      "failed",
		AttemptedAt: time.Now(),
		Generation:  generationNumber,
		Error:       err.Error(),
	}
	logger.LogDebug(
		context.Background(),
		"task_plugin subsystem=registry event=publish_failed retained_generation=%d retained_generation_active=true reason=%q",
		generationNumber,
		taskPluginRoutingDebugReason(err.Error()),
	)
}

func taskPluginRoutingDebugReason(message string) string {
	lower := strings.ToLower(message)
	switch {
	case strings.Contains(lower, "channeltype"), strings.Contains(lower, "channel type"):
		return "channel_type_conflict"
	case strings.Contains(lower, "endpoint"):
		return "endpoint_conflict"
	case strings.Contains(lower, "inner gin"), strings.Contains(lower, "rebuilding public routes"):
		return "inner_router_build_failed"
	case strings.Contains(lower, "trusted prox"):
		return "trusted_proxy_configuration_failed"
	case strings.Contains(lower, "route"):
		return "route_conflict"
	case strings.Contains(lower, "nil generation"), strings.Contains(lower, "generation number"):
		return "invalid_prepared_generation"
	default:
		return "generation_rebuild_failed"
	}
}

func (r *Registry) Snapshot() RegistrySnapshot {
	r.mu.RLock()
	defer r.mu.RUnlock()

	snapshot := RegistrySnapshot{
		Factory:         make([]Meta, 0, len(r.factory)),
		Override:        make([]Meta, 0, len(r.override)),
		DisabledFactory: make([]string, 0, len(r.disabledFactory)),
	}
	for _, plugin := range r.factory {
		snapshot.Factory = append(snapshot.Factory, cloneMeta(plugin.Meta))
	}
	for _, plugin := range r.override {
		snapshot.Override = append(snapshot.Override, cloneMeta(plugin.Meta))
	}
	for key := range r.disabledFactory {
		snapshot.DisabledFactory = append(snapshot.DisabledFactory, key)
	}
	sort.Slice(snapshot.Factory, func(i, j int) bool { return snapshot.Factory[i].Key < snapshot.Factory[j].Key })
	sort.Slice(snapshot.Override, func(i, j int) bool { return snapshot.Override[i].Key < snapshot.Override[j].Key })
	sort.Strings(snapshot.DisabledFactory)
	return snapshot
}

func cloneMeta(meta Meta) Meta {
	meta.ChannelTypes = append([]int(nil), meta.ChannelTypes...)
	meta.Models = append([]string(nil), meta.Models...)
	meta.AllowedHosts = append([]string(nil), meta.AllowedHosts...)
	meta.Routes = append([]Route(nil), meta.Routes...)
	for index := range meta.Routes {
		meta.Routes[index].Models = append([]string(nil), meta.Routes[index].Models...)
	}
	meta.Protocols = append([]ProtocolClaim(nil), meta.Protocols...)
	for index := range meta.Protocols {
		meta.Protocols[index].Models = append([]string(nil), meta.Protocols[index].Models...)
		meta.Protocols[index].Supports = append([]string(nil), meta.Protocols[index].Supports...)
	}
	if meta.Description != nil {
		meta.Description = maps.Clone(meta.Description)
	}
	if meta.UsageSchema != nil {
		usageSchema := make(map[string]UsageFieldSchema, len(meta.UsageSchema))
		for key, field := range meta.UsageSchema {
			if field.Enum != nil {
				field.Enum = append([]string{}, field.Enum...)
			}
			if field.Description != nil {
				field.Description = maps.Clone(field.Description)
			}
			usageSchema[key] = field
		}
		meta.UsageSchema = usageSchema
	}
	meta.UsageExamples = cloneUsageExamples(meta.UsageExamples)
	return meta
}

func cloneUsageExamples(examples []UsageExample) []UsageExample {
	if examples == nil {
		return nil
	}
	cloned := make([]UsageExample, len(examples))
	for index, example := range examples {
		cloned[index] = UsageExample{Label: example.Label}
		if example.Facts == nil {
			continue
		}
		facts := make(map[string]any, len(example.Facts))
		maps.Copy(facts, example.Facts)
		cloned[index].Facts = facts
	}
	return cloned
}

func filterDisabledFactory(factory map[string]*LoadedPlugin, disabled map[string]struct{}) map[string]*LoadedPlugin {
	if len(disabled) == 0 {
		return factory
	}
	filtered := make(map[string]*LoadedPlugin, len(factory))
	for key, plugin := range factory {
		if _, skip := disabled[key]; skip {
			continue
		}
		filtered[key] = plugin
	}
	return filtered
}

func clonePluginMap(source map[string]*LoadedPlugin) map[string]*LoadedPlugin {
	clone := make(map[string]*LoadedPlugin, len(source))
	maps.Copy(clone, source)
	return clone
}

func samePluginMap(left, right map[string]*LoadedPlugin) bool {
	if len(left) != len(right) {
		return false
	}
	for key, plugin := range left {
		if right[key] != plugin {
			return false
		}
	}
	return true
}

func pluginMapKeys(plugins map[string]*LoadedPlugin) map[string]struct{} {
	keys := make(map[string]struct{}, len(plugins))
	for key := range plugins {
		keys[key] = struct{}{}
	}
	return keys
}

func (r *Registry) resolveActiveOverrides(
	generation *RoutingGeneration,
	override map[string]*LoadedPlugin,
	enabled bool,
) map[string]*LoadedPlugin {
	active := make(map[string]*LoadedPlugin)
	if !enabled {
		return active
	}
	for _, plugin := range generation.plugins {
		desired, hasOverride := override[plugin.Meta.Key]
		if !hasOverride {
			continue
		}
		if plugin == desired || plugin == r.activeOverride[plugin.Meta.Key] {
			active[plugin.Meta.Key] = plugin
		}
	}
	return active
}

func decodeMeta(value any) (Meta, error) {
	object, ok := value.(map[string]any)
	if !ok {
		return Meta{}, fmt.Errorf("plugin meta must be an object")
	}
	for field := range object {
		switch field {
		case "apiVersion", "key", "name", "icon", "description", "version", "author", "channelTypes", "channelType", "compatibleChannelTypes", "models", "fetchMode", "allowedHosts", "routes", "protocols", "usageSchema", "usageExamples", "auth", "endpoints", "submitPaths", "actions":
		default:
			return Meta{}, fmt.Errorf("plugin meta has unknown field %q", field)
		}
	}
	meta := Meta{}
	var err error
	meta.APIVersion, err = integerMetaField(object, "apiVersion")
	if err != nil {
		return Meta{}, err
	}
	if meta.Key, err = stringMetaField(object, "key"); err != nil {
		return Meta{}, err
	}
	if meta.Name, err = stringMetaField(object, "name"); err != nil {
		return Meta{}, err
	}
	if meta.Icon, err = stringMetaField(object, "icon"); err != nil {
		return Meta{}, err
	}
	meta.Icon = strings.TrimSpace(meta.Icon)
	if meta.Description, err = localizedTextMetaField(object, "description", maxMetaDescriptionRunes); err != nil {
		return Meta{}, err
	}
	if meta.Version, err = stringMetaField(object, "version"); err != nil {
		return Meta{}, err
	}
	author, ok := object["author"].(map[string]any)
	if !ok {
		return Meta{}, fmt.Errorf("plugin meta author must be an object")
	}
	for field := range author {
		if field != "name" && field != "url" {
			return Meta{}, fmt.Errorf("plugin meta author has unknown field %q", field)
		}
	}
	if meta.Author.Name, err = stringMetaField(author, "name"); err != nil {
		return Meta{}, err
	}
	if rawURL, exists := author["url"]; exists {
		meta.Author.URL, ok = rawURL.(string)
		if !ok {
			return Meta{}, fmt.Errorf("plugin meta author field %q must be a string", "url")
		}
	}
	if _, exists := object["channelType"]; exists {
		return Meta{}, fmt.Errorf("plugin meta channelType is no longer supported; declare channelTypes instead")
	}
	if _, exists := object["compatibleChannelTypes"]; exists {
		return Meta{}, fmt.Errorf("plugin meta compatibleChannelTypes is no longer supported; declare channelTypes instead")
	}
	meta.ChannelTypes, err = integerSliceMetaField(object, "channelTypes")
	if err != nil {
		return Meta{}, err
	}
	if meta.FetchMode, err = stringMetaField(object, "fetchMode"); err != nil {
		return Meta{}, err
	}
	meta.Models, err = strictStringSlice(object, "models")
	if err != nil {
		return Meta{}, err
	}
	meta.AllowedHosts, err = strictStringSlice(object, "allowedHosts")
	if err != nil {
		return Meta{}, err
	}
	meta.Routes, err = decodeRoutes(object["routes"])
	if err != nil {
		return Meta{}, err
	}
	if _, exists := object["endpoints"]; exists {
		return Meta{}, fmt.Errorf("plugin meta endpoints is no longer supported; declare protocols by name")
	}
	meta.Protocols, err = decodeProtocolClaims(object, "protocols")
	if err != nil {
		return Meta{}, err
	}
	if usageSchema, exists := object["usageSchema"]; exists {
		meta.UsageSchema, err = decodeUsageSchema(usageSchema)
		if err != nil {
			return Meta{}, err
		}
	}
	if usageExamples, exists := object["usageExamples"]; exists {
		meta.UsageExamples, err = decodeUsageExamples(usageExamples)
		if err != nil {
			return Meta{}, err
		}
	}
	for _, removedField := range []string{"submitPaths", "actions"} {
		if _, exists := object[removedField]; exists {
			return Meta{}, fmt.Errorf("plugin meta %s is no longer supported; declare routes instead", removedField)
		}
	}
	switch auth := object["auth"].(type) {
	case nil:
	case string:
		meta.Auth.Type = auth
	case map[string]any:
		for key := range auth {
			if key != "type" {
				return Meta{}, fmt.Errorf("plugin meta auth has unknown field %q", key)
			}
		}
		meta.Auth.Type, err = stringMetaField(auth, "type")
		if err != nil {
			return Meta{}, err
		}
	default:
		return Meta{}, fmt.Errorf("plugin meta auth must be a string or object")
	}
	meta.Auth.Type = strings.TrimSpace(meta.Auth.Type)
	if meta.Auth.Type == "vertex_oauth" {
		meta.Auth.Type = "oauth2_jwt"
	}
	if meta.Auth.Type != "" && meta.Auth.Type != "none" && meta.Auth.Type != "api_key" && meta.Auth.Type != "oauth2_jwt" {
		return Meta{}, fmt.Errorf("unsupported plugin auth type %q", meta.Auth.Type)
	}
	if meta.APIVersion != APIVersion1 {
		return Meta{}, fmt.Errorf("unsupported plugin apiVersion %d", meta.APIVersion)
	}
	if strings.TrimSpace(meta.Key) == "" || strings.TrimSpace(meta.Name) == "" || strings.TrimSpace(meta.Version) == "" {
		return Meta{}, fmt.Errorf("plugin meta key, name, and version are required")
	}
	if len(meta.Key) > 30 {
		return Meta{}, fmt.Errorf("plugin meta key must not exceed 30 characters")
	}
	return meta, nil
}

// ValidateV1Meta applies the metadata constraints published in
// docs/plugin-api/v1.schema.json to administrator uploads.
func ValidateV1Meta(meta Meta) error {
	meta = cloneMeta(meta)
	return normalizeV1Meta(&meta)
}

func normalizeV1Meta(meta *Meta) error {
	if meta.APIVersion != APIVersion1 {
		return fmt.Errorf("unsupported plugin apiVersion %d", meta.APIVersion)
	}
	if strings.TrimSpace(meta.Name) == "" {
		return fmt.Errorf("plugin meta name is required")
	}
	meta.Icon = strings.TrimSpace(meta.Icon)
	if meta.Icon != "" {
		if utf8.RuneCountInString(meta.Icon) > 128 {
			return fmt.Errorf("plugin meta icon must not exceed 128 characters")
		}
		for _, character := range meta.Icon {
			if unicode.IsControl(character) {
				return fmt.Errorf("plugin meta icon must not contain control characters")
			}
		}
	}
	if err := validateLocalizedText(meta.Description, "description", maxMetaDescriptionRunes); err != nil {
		return err
	}
	meta.Author.Name = strings.TrimSpace(meta.Author.Name)
	if meta.Author.Name == "" {
		return fmt.Errorf("plugin meta author name is required")
	}
	meta.Author.URL = strings.TrimSpace(meta.Author.URL)
	if meta.Author.URL != "" {
		parsedURL, err := url.Parse(meta.Author.URL)
		if err != nil || parsedURL.Host == "" || (parsedURL.Scheme != "http" && parsedURL.Scheme != "https") {
			return fmt.Errorf("plugin meta author url must be an absolute HTTP(S) URL")
		}
	}
	if !pluginKeyPattern.MatchString(meta.Key) {
		return fmt.Errorf("plugin meta key must match %s", pluginKeyPattern)
	}
	if len(meta.Key) > 30 {
		return fmt.Errorf("plugin meta key must not exceed 30 characters")
	}
	if !pluginVersionPattern.MatchString(meta.Version) {
		return fmt.Errorf("plugin meta version must be semver")
	}
	if meta.FetchMode != "per_task" && meta.FetchMode != "batch" {
		return fmt.Errorf("plugin meta fetchMode must be per_task or batch")
	}
	if len(meta.Models) == 0 {
		return fmt.Errorf("plugin meta models must contain at least one model")
	}
	seenChannelTypes := make(map[int]struct{}, len(meta.ChannelTypes))
	for _, channelType := range meta.ChannelTypes {
		if channelType <= 0 {
			return fmt.Errorf("plugin meta channelTypes must contain positive channel types")
		}
		if channelType == constant.ChannelTypeTaskPlugin {
			return fmt.Errorf("plugin meta channelTypes must not contain the task plugin channel type")
		}
		if _, duplicate := seenChannelTypes[channelType]; duplicate {
			return fmt.Errorf("plugin meta channelTypes must be unique")
		}
		seenChannelTypes[channelType] = struct{}{}
	}
	models := make(map[string]struct{}, len(meta.Models))
	seenFold := make(map[string]struct{}, len(meta.Models))
	for _, model := range meta.Models {
		if strings.TrimSpace(model) == "" || strings.TrimSpace(model) != model {
			return fmt.Errorf("plugin meta models must contain non-empty canonical names")
		}
		folded := asciiFold(model)
		if _, exists := seenFold[folded]; exists {
			return fmt.Errorf("plugin meta models must be unique case-insensitively")
		}
		seenFold[folded] = struct{}{}
		models[model] = struct{}{}
	}
	hosts := make(map[string]struct{}, len(meta.AllowedHosts))
	for _, host := range meta.AllowedHosts {
		if strings.TrimSpace(host) == "" || strings.ContainsAny(host, "/:?#") {
			return fmt.Errorf("plugin meta allowedHosts must contain hostnames without schemes, ports, or paths")
		}
		if _, exists := hosts[host]; exists {
			return fmt.Errorf("plugin meta allowedHosts must be unique")
		}
		hosts[host] = struct{}{}
	}
	routeKeys := make(map[string]struct{}, len(meta.Routes))
	for index := range meta.Routes {
		if err := validateRoute(&meta.Routes[index]); err != nil {
			return err
		}
		for _, model := range meta.Routes[index].Models {
			if _, exists := models[model]; !exists {
				return fmt.Errorf("plugin route %s %s model %q is not declared in plugin meta models", meta.Routes[index].Method, meta.Routes[index].Path, model)
			}
		}
		shape, err := routePathShape(meta.Routes[index].Path)
		if err != nil {
			return err
		}
		key := meta.Routes[index].Method + " " + shape
		if _, exists := routeKeys[key]; exists {
			return fmt.Errorf("plugin meta routes contain duplicate route %s %s", meta.Routes[index].Method, meta.Routes[index].Path)
		}
		routeKeys[key] = struct{}{}
	}
	protocols := make(map[string]struct{}, len(meta.Protocols))
	for index := range meta.Protocols {
		claim := &meta.Protocols[index]
		definition, known := HostProtocol(claim.Name)
		modes := definition.DefinedModes()
		if len(modes) > 0 {
			modeNames := make([]string, len(modes))
			for modeIndex, mode := range modes {
				modeNames[modeIndex] = mode.Name
			}
			choosingFrom := quotedJoin(modeNames, ", ")
			if claim.Supports == nil {
				if claim.objectForm {
					return fmt.Errorf("plugin %s protocol %q must declare supports; add supports: [...] choosing from %s", meta.Key, claim.Name, choosingFrom)
				}
				return fmt.Errorf("plugin %s protocol %q must declare supports; replace the bare string with {name: %q, supports: [...]} choosing from %s", meta.Key, claim.Name, claim.Name, choosingFrom)
			}
			if len(claim.Supports) == 0 {
				return fmt.Errorf("plugin %s protocol %q supports must contain at least one of %s", meta.Key, claim.Name, choosingFrom)
			}
			seenSupports := make(map[string]struct{}, len(claim.Supports))
			for _, support := range claim.Supports {
				if _, duplicate := seenSupports[support]; duplicate {
					return fmt.Errorf("plugin %s protocol %q supports must be unique", meta.Key, claim.Name)
				}
				seenSupports[support] = struct{}{}
				if !slices.Contains(modeNames, support) {
					if support == "retrieve" {
						return fmt.Errorf("plugin %s protocol %q has no mode %q; retrieval of a created response is always available and is never declared", meta.Key, claim.Name, support)
					}
					return fmt.Errorf("plugin %s protocol %q has no mode %q", meta.Key, claim.Name, support)
				}
			}
			claim.Supports = orderProtocolSupports(claim.Name, claim.Supports)
		} else if claim.Supports != nil {
			return fmt.Errorf("plugin %s protocol %q does not define modes; supports is not allowed", meta.Key, claim.Name)
		}
		if !known {
			return fmt.Errorf("plugin meta protocol %q is unknown", claim.Name)
		}
		if _, duplicate := protocols[claim.Name]; duplicate {
			return fmt.Errorf("plugin meta protocols must be unique")
		}
		protocols[claim.Name] = struct{}{}
		if err := validateModelScope(claim.Models, fmt.Sprintf("protocol %q", claim.Name)); err != nil {
			return err
		}
		for _, model := range claim.Models {
			if _, exists := models[model]; !exists {
				return fmt.Errorf("plugin protocol %q model %q is not declared in plugin meta models", claim.Name, model)
			}
		}
	}
	for name, field := range meta.UsageSchema {
		if strings.TrimSpace(name) == "" || strings.TrimSpace(name) != name {
			return fmt.Errorf("plugin meta usageSchema keys must be non-empty canonical names")
		}
		if err := validateUsageFieldSchema(name, field); err != nil {
			return err
		}
	}
	if err := validateUsageExamples(meta.UsageSchema, meta.UsageExamples); err != nil {
		return err
	}
	return nil
}

func decodeUsageSchema(value any) (map[string]UsageFieldSchema, error) {
	if value == nil {
		return nil, fmt.Errorf("plugin meta usageSchema must be an object")
	}
	object, ok := value.(map[string]any)
	if !ok {
		return nil, fmt.Errorf("plugin meta usageSchema must be an object")
	}
	schema := make(map[string]UsageFieldSchema, len(object))
	for name, rawField := range object {
		fieldObject, ok := rawField.(map[string]any)
		if !ok {
			return nil, fmt.Errorf("plugin meta usageSchema field %q must be an object", name)
		}
		for key := range fieldObject {
			switch key {
			case "type", "unit", "enum", "description":
			default:
				return nil, fmt.Errorf("plugin meta usageSchema field %q has unknown property %q", name, key)
			}
		}
		field := UsageFieldSchema{}
		var err error
		if field.Type, err = stringMetaField(fieldObject, "type"); err != nil {
			return nil, err
		}
		if field.Unit, err = stringMetaField(fieldObject, "unit"); err != nil {
			return nil, err
		}
		if field.Description, err = localizedTextMetaField(fieldObject, "description", maxUsageFieldDescriptionRunes); err != nil {
			return nil, err
		}
		if _, exists := fieldObject["enum"]; exists {
			if field.Enum, err = strictStringSlice(fieldObject, "enum"); err != nil {
				return nil, err
			}
		}
		if err = validateUsageFieldSchema(name, field); err != nil {
			return nil, err
		}
		schema[name] = field
	}
	return schema, nil
}

func validateUsageFieldSchema(name string, field UsageFieldSchema) error {
	if err := validateLocalizedText(field.Description, fmt.Sprintf("usageSchema field %q description", name), maxUsageFieldDescriptionRunes); err != nil {
		return err
	}
	if field.Enum != nil {
		if field.Type != "" || field.Unit != "" {
			return fmt.Errorf("plugin meta usageSchema field %q cannot combine enum with type or unit", name)
		}
		if len(field.Enum) == 0 {
			return fmt.Errorf("plugin meta usageSchema field %q enum must contain at least one value", name)
		}
		values := make(map[string]struct{}, len(field.Enum))
		for _, value := range field.Enum {
			if _, exists := values[value]; exists {
				return fmt.Errorf("plugin meta usageSchema field %q enum values must be unique", name)
			}
			values[value] = struct{}{}
		}
		return nil
	}
	if field.Type == "boolean" {
		if field.Unit != "" {
			return fmt.Errorf("plugin meta usageSchema field %q cannot combine boolean with unit", name)
		}
		return nil
	}
	if field.Type != "number" {
		return fmt.Errorf("plugin meta usageSchema field %q type must be number or boolean", name)
	}
	if field.Unit != "second" && field.Unit != "count" && field.Unit != "token" && field.Unit != "credit" {
		return fmt.Errorf("plugin meta usageSchema field %q unit must be second, count, token, or credit", name)
	}
	return nil
}

const maxUsageExamples = 16
const maxUsageExampleLabelRunes = 48

func decodeUsageExamples(value any) ([]UsageExample, error) {
	if value == nil {
		return nil, fmt.Errorf("plugin meta usageExamples must be an array")
	}
	items, ok := value.([]any)
	if !ok {
		return nil, fmt.Errorf("plugin meta usageExamples must be an array")
	}
	if len(items) > maxUsageExamples {
		return nil, fmt.Errorf("plugin meta usageExamples must not exceed %d entries", maxUsageExamples)
	}
	examples := make([]UsageExample, 0, len(items))
	for index, item := range items {
		object, ok := item.(map[string]any)
		if !ok {
			return nil, fmt.Errorf("plugin meta usageExamples[%d] must be an object", index)
		}
		for key := range object {
			if key != "label" && key != "facts" {
				return nil, fmt.Errorf("plugin meta usageExamples[%d] has unknown field %q", index, key)
			}
		}
		label, err := stringMetaField(object, "label")
		if err != nil {
			return nil, fmt.Errorf("plugin meta usageExamples[%d] %w", index, err)
		}
		rawFacts, exists := object["facts"]
		if !exists || rawFacts == nil {
			return nil, fmt.Errorf("plugin meta usageExamples[%d] facts must be an object", index)
		}
		facts, ok := rawFacts.(map[string]any)
		if !ok {
			return nil, fmt.Errorf("plugin meta usageExamples[%d] facts must be an object", index)
		}
		examples = append(examples, UsageExample{Label: label, Facts: facts})
	}
	return examples, nil
}

func usageSchemaHasTokenUnit(schema map[string]UsageFieldSchema) bool {
	for _, field := range schema {
		if field.Type == "number" && field.Unit == "token" {
			return true
		}
	}
	return false
}

func validateUsageExamples(schema map[string]UsageFieldSchema, examples []UsageExample) error {
	if len(examples) == 0 {
		if usageSchemaHasTokenUnit(schema) {
			return fmt.Errorf("plugin meta usageExamples is required when usageSchema declares a token unit")
		}
		return nil
	}
	if len(schema) == 0 {
		return fmt.Errorf("plugin meta usageExamples requires usageSchema")
	}
	if len(examples) > maxUsageExamples {
		return fmt.Errorf("plugin meta usageExamples must not exceed %d entries", maxUsageExamples)
	}
	for index := range examples {
		label := strings.TrimSpace(examples[index].Label)
		if label == "" {
			return fmt.Errorf("plugin meta usageExamples[%d] label is required", index)
		}
		if utf8.RuneCountInString(label) > maxUsageExampleLabelRunes {
			return fmt.Errorf("plugin meta usageExamples[%d] label must not exceed %d characters", index, maxUsageExampleLabelRunes)
		}
		examples[index].Label = label
		if examples[index].Facts == nil {
			return fmt.Errorf("plugin meta usageExamples[%d] facts must be an object", index)
		}
		for key := range schema {
			if _, exists := examples[index].Facts[key]; !exists {
				return fmt.Errorf("plugin meta usageExamples[%d] facts missing key %q", index, key)
			}
		}
		for key, value := range examples[index].Facts {
			field, declared := schema[key]
			if !declared {
				return fmt.Errorf("plugin meta usageExamples[%d] facts has undeclared key %q", index, key)
			}
			if err := validateUsageExampleValue(value, field); err != nil {
				return fmt.Errorf("plugin meta usageExamples[%d] facts field %q %s", index, key, err.Error())
			}
		}
	}
	return nil
}

func validateUsageExampleValue(value any, field UsageFieldSchema) error {
	if len(field.Enum) > 0 {
		text, ok := value.(string)
		if !ok {
			return fmt.Errorf("enum is not an allowed value")
		}
		if slices.Contains(field.Enum, text) {
			return nil
		}
		return fmt.Errorf("enum is not an allowed value")
	}
	if field.Type == "boolean" {
		if _, ok := value.(bool); !ok {
			return fmt.Errorf("must be a boolean")
		}
		return nil
	}
	number, ok := usageExampleNumber(value)
	if !ok {
		return fmt.Errorf("must be a finite non-negative number")
	}
	if math.IsNaN(number) || math.IsInf(number, 0) || number < 0 {
		return fmt.Errorf("must be a finite non-negative number")
	}
	limit := float64(relaycommon.MaxTaskDurationSeconds)
	if field.Unit == "count" {
		limit = float64(dto.MaxImageN)
	} else if field.Unit == "token" || field.Unit == "credit" {
		limit = float64(common.MaxQuota)
	}
	if number > limit {
		return fmt.Errorf("exceeds the host limit")
	}
	return nil
}

func usageExampleNumber(value any) (float64, bool) {
	switch number := value.(type) {
	case float64:
		return number, true
	case int64:
		return float64(number), true
	case int:
		return float64(number), true
	default:
		return 0, false
	}
}

func decodeRoutes(value any) ([]Route, error) {
	if value == nil {
		return []Route{}, nil
	}
	items, ok := value.([]any)
	if !ok {
		return nil, fmt.Errorf("plugin meta routes must be an array")
	}
	routes := make([]Route, 0, len(items))
	for index, item := range items {
		object, ok := item.(map[string]any)
		if !ok {
			return nil, fmt.Errorf("plugin meta route %d must be an object", index)
		}
		if _, exists := object["renderer"]; exists {
			return nil, fmt.Errorf("plugin meta route %d field renderer is no longer supported", index)
		}
		for key := range object {
			switch key {
			case "method", "path", "type", "action", "decode", "render", "taskIdParam", "models":
			default:
				return nil, fmt.Errorf("plugin meta route %d has unknown field %q", index, key)
			}
		}
		route := Route{}
		var err error
		if route.Method, err = stringMetaField(object, "method"); err != nil {
			return nil, err
		}
		if route.Path, err = stringMetaField(object, "path"); err != nil {
			return nil, err
		}
		routeType, err := stringMetaField(object, "type")
		if err != nil {
			return nil, err
		}
		route.Type = RouteType(routeType)
		if route.Action, err = stringMetaField(object, "action"); err != nil {
			return nil, err
		}
		if route.Decode, err = stringMetaField(object, "decode"); err != nil {
			return nil, err
		}
		if route.Render, err = stringMetaField(object, "render"); err != nil {
			return nil, err
		}
		if route.TaskIDParam, err = stringMetaField(object, "taskIdParam"); err != nil {
			return nil, err
		}
		if _, exists := object["models"]; exists {
			if route.Models, err = strictStringSlice(object, "models"); err != nil {
				return nil, err
			}
			if len(route.Models) == 0 {
				return nil, fmt.Errorf("plugin meta route %d models must contain at least one model", index)
			}
		}
		routes = append(routes, route)
	}
	return routes, nil
}

// decodeProtocolClaims accepts both protocol entry shapes: a bare protocol
// name string (binds every meta.models entry) and an object {name, models,
// supports}. An absent key is empty; a present null or non-array is rejected.
// The supports key is decoded only when present so an absent key stays nil.
func decodeProtocolClaims(object map[string]any, name string) ([]ProtocolClaim, error) {
	value, exists := object[name]
	if !exists {
		return []ProtocolClaim{}, nil
	}
	items, ok := value.([]any)
	if !ok {
		return nil, fmt.Errorf("plugin meta %s must be an array", name)
	}
	claims := make([]ProtocolClaim, 0, len(items))
	for index, item := range items {
		switch entry := item.(type) {
		case string:
			claims = append(claims, ProtocolClaim{Name: entry})
		case map[string]any:
			for key := range entry {
				switch key {
				case "name", "models", "supports":
				default:
					return nil, fmt.Errorf("plugin meta protocol %d has unknown field %q", index, key)
				}
			}
			claim := ProtocolClaim{objectForm: true}
			var err error
			if claim.Name, err = stringMetaField(entry, "name"); err != nil {
				return nil, err
			}
			if _, exists := entry["models"]; exists {
				if claim.Models, err = strictStringSlice(entry, "models"); err != nil {
					return nil, err
				}
				if len(claim.Models) == 0 {
					return nil, fmt.Errorf("plugin meta protocol %d models must contain at least one model", index)
				}
			}
			if _, exists := entry["supports"]; exists {
				if claim.Supports, err = strictStringSlice(entry, "supports"); err != nil {
					return nil, err
				}
				claim.Supports = orderProtocolSupports(claim.Name, claim.Supports)
			}
			claims = append(claims, claim)
		default:
			return nil, fmt.Errorf("plugin meta protocol %d must be a string or an object", index)
		}
	}
	return claims, nil
}

func integerMetaField(object map[string]any, name string) (int, error) {
	value, exists := object[name]
	if !exists {
		return 0, nil
	}
	switch number := value.(type) {
	case int64:
		converted := int(number)
		if int64(converted) != number {
			return 0, fmt.Errorf("plugin meta %s is outside the supported integer range", name)
		}
		return converted, nil
	case float64:
		if math.IsNaN(number) || math.IsInf(number, 0) || math.Trunc(number) != number {
			return 0, fmt.Errorf("plugin meta %s must be an integer", name)
		}
		converted := int(number)
		if float64(converted) != number {
			return 0, fmt.Errorf("plugin meta %s is outside the supported integer range", name)
		}
		return converted, nil
	default:
		return 0, fmt.Errorf("plugin meta %s must be an integer", name)
	}
}

func integerSliceMetaField(object map[string]any, name string) ([]int, error) {
	value, exists := object[name]
	if !exists {
		return nil, nil
	}
	items, ok := value.([]any)
	if !ok {
		return nil, fmt.Errorf("plugin meta %s must be an array of integers", name)
	}
	numbers := make([]int, 0, len(items))
	for index, item := range items {
		element := map[string]any{name: item}
		number, err := integerMetaField(element, name)
		if err != nil {
			return nil, fmt.Errorf("plugin meta %s element %d must be an integer", name, index+1)
		}
		numbers = append(numbers, number)
	}
	return numbers, nil
}

func stringMetaField(object map[string]any, name string) (string, error) {
	value, exists := object[name]
	if !exists {
		return "", nil
	}
	text, ok := value.(string)
	if !ok {
		return "", fmt.Errorf("plugin meta %s must be a string", name)
	}
	return text, nil
}

func localizedTextMetaField(object map[string]any, name string, maxRunes int) (LocalizedText, error) {
	value, exists := object[name]
	if !exists {
		return nil, nil
	}
	var text LocalizedText
	switch typed := value.(type) {
	case string:
		text = LocalizedText{"en": typed}
	case map[string]any:
		text = make(LocalizedText, len(typed))
		for locale, raw := range typed {
			item, ok := raw.(string)
			if !ok {
				return nil, fmt.Errorf("plugin meta %s locale %q must be a string", name, locale)
			}
			text[locale] = item
		}
	default:
		return nil, fmt.Errorf("plugin meta %s must be a string or object", name)
	}
	if err := validateLocalizedText(text, name, maxRunes); err != nil {
		return nil, err
	}
	return text, nil
}

func validateLocalizedText(text LocalizedText, name string, maxRunes int) error {
	if text == nil {
		return nil
	}
	if len(text) > maxLocalizedTextLocales {
		return fmt.Errorf("plugin meta %s must not exceed %d locales", name, maxLocalizedTextLocales)
	}
	canonical := make(map[string]string, len(text))
	for locale, value := range text {
		if !localeTagPattern.MatchString(locale) {
			return fmt.Errorf("plugin meta %s has invalid locale %q", name, locale)
		}
		canonicalLocale := canonicalLocaleTag(locale)
		if _, duplicate := canonical[canonicalLocale]; duplicate {
			return fmt.Errorf("plugin meta %s has duplicate locale %q", name, canonicalLocale)
		}
		trimmed := strings.TrimSpace(value)
		if trimmed == "" {
			return fmt.Errorf("plugin meta %s value for %q must be a non-empty string", name, locale)
		}
		for _, character := range trimmed {
			if unicode.IsControl(character) {
				return fmt.Errorf("plugin meta %s value for %q must not contain control characters", name, locale)
			}
		}
		if utf8.RuneCountInString(trimmed) > maxRunes {
			return fmt.Errorf("plugin meta %s must not exceed %d characters", name, maxRunes)
		}
		canonical[canonicalLocale] = trimmed
	}
	if strings.TrimSpace(canonical["en"]) == "" {
		return fmt.Errorf("plugin meta %s must include a non-empty \"en\" value", name)
	}
	for locale := range text {
		delete(text, locale)
	}
	for locale, value := range canonical {
		text[locale] = value
	}
	return nil
}

// canonicalLocaleTag applies BCP-47 case conventions so lookups can use
// exact matching: language lowercase, 2-letter region uppercase, 4-letter
// script title case (zh-tw -> zh-TW, EN -> en, zh-hans -> zh-Hans).
func canonicalLocaleTag(tag string) string {
	parts := strings.Split(tag, "-")
	parts[0] = strings.ToLower(parts[0])
	for index := 1; index < len(parts); index++ {
		switch len(parts[index]) {
		case 2:
			parts[index] = strings.ToUpper(parts[index])
		case 4:
			lowered := strings.ToLower(parts[index])
			parts[index] = strings.ToUpper(lowered[:1]) + lowered[1:]
		default:
			parts[index] = strings.ToLower(parts[index])
		}
	}
	return strings.Join(parts, "-")
}

func quotedJoin(items []string, sep string) string {
	parts := make([]string, len(items))
	for index, item := range items {
		parts[index] = fmt.Sprintf("%q", item)
	}
	return strings.Join(parts, sep)
}

func strictStringSlice(object map[string]any, name string) ([]string, error) {
	value, exists := object[name]
	if !exists {
		return []string{}, nil
	}
	items, ok := value.([]any)
	if !ok {
		return nil, fmt.Errorf("plugin meta %s must be an array of strings", name)
	}
	result := make([]string, 0, len(items))
	for _, item := range items {
		text, ok := item.(string)
		if !ok {
			return nil, fmt.Errorf("plugin meta %s must be an array of strings", name)
		}
		result = append(result, text)
	}
	return result, nil
}