// Package skill loads invokable playbooks ("skills") from Markdown files. A skill
// is a named, described prompt body the model can invoke via the run_skill tool
// (or the user via a slash name): an "inline" skill folds its body into the turn as
// a tool result, a "subagent" skill runs in an isolated child loop and returns
// only its final answer. Project scope wins over global; only names+descriptions
// enter the cache-stable system-prompt index (see index.go) — bodies load on
// demand. Discovery scans several conventions (.reasonix / .agents / .agent /
// .claude under the project root and the home dir — see config.ConventionDirs) so
// skills authored for other agent tools migrate in unchanged. Directory skills
// use <name>/SKILL.md; flat <name>.md files from Claude roots are loaded only
// when they carry skill frontmatter. Discovery follows symlinks, so linked
// skills are picked up like real ones.
package skill

import (
	"errors"
	"fmt"
	"io"
	"os"
	"path"
	"path/filepath"
	"slices"
	"sort"
	"strings"

	"reasonix/internal/config"
	"reasonix/internal/fileutil"
	fileencoding "reasonix/internal/fileutil/encoding"
	"reasonix/internal/frontmatter"
	"reasonix/internal/tool"
)

// ErrInvocationUnavailable marks a profile/dependency gate that can become
// runnable after switching profile or connecting the required capability.
var ErrInvocationUnavailable = errors.New("skill invocation unavailable")

// Scope records where a skill was loaded from. Higher-priority scopes win on a
// name collision: project > custom > global > builtin.
type Scope string

const (
	ScopeProject Scope = "project"
	ScopeCustom  Scope = "custom"
	ScopeGlobal  Scope = "global"
	ScopeBuiltin Scope = "builtin"
)

// RunAs selects how an invoked skill executes. Inline folds the body into the
// parent turn; subagent spawns an isolated child loop and returns only the final
// answer (its tool calls and reasoning never enter the parent context).
type RunAs string

const (
	RunInline   RunAs = "inline"
	RunSubagent RunAs = "subagent"
)

const (
	// SkillsDirname is the directory under each root that holds skills.
	SkillsDirname = "skills"
	// SkillFile is the canonical filename inside a directory-layout skill.
	SkillFile = "SKILL.md"
)

// Skill is a loaded playbook.
type Skill struct {
	Name        string // canonical identifier; matches the directory / filename stem
	Description string // one-liner shown in the pinned index
	Body        string // full markdown body (post-frontmatter), loaded eagerly
	Scope       Scope  // where it came from
	Path        string // absolute path to the SKILL.md / <name>.md, or "(builtin)"
	Plugin      string // installed plugin package name; empty for non-plugin skills
	// runtimeBindingsPrepared is session-local invocation state. It must not be
	// inferred from untrusted Markdown content or persisted skill metadata.
	runtimeBindingsPrepared bool
	// SlashPrefix overrides Plugin only for the user-facing invocation name.
	// Imported Claude agents use <plugin>:agent so an agent and skill may safely
	// share the same upstream name.
	SlashPrefix string
	// AllowedTools, when non-empty, scopes a subagent skill's tool registry to
	// these literal tool names (from the `allowed-tools` frontmatter).
	AllowedTools []string
	RunAs        RunAs  // inline | subagent
	Model        string // optional model override for runAs=subagent (frontmatter `model:`)
	Effort       string // optional effort for runAs=subagent (frontmatter `effort:`)
	// ReadOnly, when true, runs a subagent skill against the read-only tool
	// registry: writer tools are stripped and bash enforces the read-only
	// command policy at execution time (frontmatter `read-only:`). This is a
	// tool-boundary contract, not a prompt promise.
	ReadOnly bool
	Color    string // optional display tag for UI surfaces (frontmatter `color:`); no runtime effect
	// Invocation gates whether this skill enters the pinned Skills index the
	// model reads every turn. "auto" (default) behaves like every skill always
	// has. "manual" keeps the skill invocable by name (/<name>, run_skill) but
	// invisible to model-initiated discovery — for user-authored subagent
	// profiles meant to be triggered deliberately, not autonomously.
	Invocation string // auto | manual (frontmatter `invocation:`)
	// Routing metadata is intentionally kept out of the cache-stable Skills
	// index; it feeds per-turn capability hints only.
	Triggers         []string
	NegativeTriggers []string
	AutoUse          string // off | suggest | prefer | require
	NeedsFreshData   bool
	Cost             string // low | medium | high (advisory)
	// Requires lists capability IDs this skill depends on (e.g. mcp-server:github).
	// Optional; empty keeps full backward compatibility with older skills.
	Requires []string
	// Profiles restricts availability to economy|balanced|delivery. Empty means
	// the skill is eligible in every profile.
	Profiles []string
	// InvalidProfiles preserves rejected profiles frontmatter values so doctor
	// can warn about typos; the parser drops them from Profiles silently.
	InvalidProfiles []string
}

// SlashName returns the user-facing slash identifier. Plugin skills use a
// package-qualified name while the internal Name remains stable for run_skill.
func (s Skill) SlashName() string {
	prefix := strings.TrimSpace(s.SlashPrefix)
	if prefix == "" {
		prefix = strings.TrimSpace(s.Plugin)
	}
	if prefix == "" {
		return s.Name
	}
	return prefix + ":" + s.Name
}

// IsValidName reports whether name is a usable skill identifier.
func IsValidName(name string) bool { return config.IsValidSkillName(name) }

// Options configure a Store. ProjectRoot "" reads only the global + custom
// scopes. HomeDir "" resolves to the OS home dir (tests point it at a tmpdir).
// ReasonixHomeDir overrides the canonical Reasonix home; empty uses
// config.ReasonixHomeDir(), or HomeDir/.reasonix when HomeDir is explicitly set.
type Options struct {
	HomeDir          string
	ReasonixHomeDir  string
	ProjectRoot      string
	CustomPaths      []string
	PluginPaths      map[string][]string // canonical custom root -> installed plugin package names
	PluginAgentPaths map[string][]string // plugin roots whose flat Markdown files are Claude agents
	ExcludedPaths    []string
	DisabledNames    []string
	MaxDepth         int
	DisableBuiltins  bool // suppress shipped built-ins (test-only knob)
	// DisableDiscovery returns an empty store without probing project, custom,
	// global, plugin, or built-in skill sources. It is a test-only isolation knob.
	DisableDiscovery bool
	// Stderr is the writer for diagnostic warnings. When nil, defaults to
	// os.Stderr. Set to io.Discard to suppress output (e.g. during model
	// switch inside a bubbletea session).
	Stderr io.Writer
}

// Store resolves skills across the configured roots.
type Store struct {
	homeDir          string
	reasonixHomeDir  string
	projectRoot      string
	customPaths      []string
	pluginPaths      map[string][]string
	pluginAgentPaths map[string][]string
	excludedPaths    map[string]bool
	disabled         map[string]bool
	maxDepth         int
	disableBuiltins  bool
	disableDiscovery bool
	stderr           io.Writer
	runtimeProfile   string
	requiresReady    func([]string) []string
	toolBindings     func(Skill) []tool.MCPBinding
}

// New builds a Store. Relative custom paths and a relative project root are made
// absolute; "~" in a custom path expands to the home dir.
func New(opts Options) *Store {
	home := opts.HomeDir
	if home == "" {
		if h, err := os.UserHomeDir(); err == nil {
			home = h
		}
	}
	reasonixHome := opts.ReasonixHomeDir
	if reasonixHome == "" {
		if opts.HomeDir != "" {
			reasonixHome = filepath.Join(home, ".reasonix")
		} else {
			reasonixHome = config.ReasonixHomeDir()
		}
	}
	root := opts.ProjectRoot
	if root != "" {
		if abs, err := filepath.Abs(root); err == nil {
			root = abs
		}
	}
	base := root
	if base == "" {
		if wd, err := os.Getwd(); err == nil {
			base = wd
		}
	}
	custom := dedupePaths(resolveCustomPaths(opts.CustomPaths, base, home))
	pluginPaths := normalizePluginPaths(opts.PluginPaths)
	pluginAgentPaths := normalizePluginPaths(opts.PluginAgentPaths)
	excluded := map[string]bool{}
	for _, p := range dedupePaths(resolveCustomPaths(opts.ExcludedPaths, base, home)) {
		excluded[config.CanonicalSkillPath(p)] = true
	}
	stderr := opts.Stderr
	if stderr == nil {
		stderr = os.Stderr
	}
	return &Store{
		homeDir:          home,
		reasonixHomeDir:  reasonixHome,
		projectRoot:      root,
		customPaths:      custom,
		pluginPaths:      pluginPaths,
		pluginAgentPaths: pluginAgentPaths,
		excludedPaths:    excluded,
		disabled:         disabledNameSet(opts.DisabledNames),
		maxDepth:         normalizeMaxDepth(opts.MaxDepth),
		disableBuiltins:  opts.DisableBuiltins,
		disableDiscovery: opts.DisableDiscovery,
		stderr:           stderr,
	}
}

// ConfigureInvocationPolicy installs session-local runtime constraints for
// skill calls. It does not alter discovery or the provider-visible tool schema;
// callers validate the selected skill immediately before execution.
func (s *Store) ConfigureInvocationPolicy(profile string, requiresReady func([]string) []string) {
	if s == nil {
		return
	}
	s.runtimeProfile = normalizeRuntimeProfile(profile)
	s.requiresReady = requiresReady
}

// ConfigureToolBindings installs a session-local resolver for plugin-owned MCP
// tools. It affects only an invoked skill body and never the cache-stable index.
func (s *Store) ConfigureToolBindings(resolve func(Skill) []tool.MCPBinding) {
	if s == nil {
		return
	}
	s.toolBindings = resolve
}

// Prepare binds a plugin skill's portable MCP references to this session's
// exact callable names. Non-plugin skills and sessions without bindings are
// returned byte-for-byte unchanged.
func (s *Store) Prepare(sk Skill) Skill {
	if s == nil || s.toolBindings == nil || strings.TrimSpace(sk.Plugin) == "" || sk.runtimeBindingsPrepared {
		return sk
	}
	bindings := append([]tool.MCPBinding(nil), s.toolBindings(sk)...)
	if len(bindings) == 0 {
		return sk
	}
	sort.Slice(bindings, func(i, j int) bool { return bindings[i].CallableName < bindings[j].CallableName })
	seen := map[string]bool{}
	unique := bindings[:0]
	for _, binding := range bindings {
		if binding.CallableName == "" || seen[binding.CallableName] {
			continue
		}
		seen[binding.CallableName] = true
		unique = append(unique, binding)
	}
	bindings = unique
	if len(bindings) == 0 {
		return sk
	}
	sk.AllowedTools = bindAllowedTools(sk.AllowedTools, bindings)
	sk.runtimeBindingsPrepared = true

	var b strings.Builder
	b.WriteString(strings.TrimRight(sk.Body, " \t\r\n"))
	b.WriteString("\n\n## Runtime MCP tool bindings\n\n")
	b.WriteString("These host-generated bindings are authoritative for this invocation. Use the exact direct name below; if only `use_capability` is available, use the stable capability ID. Short or Claude-style MCP names in this skill refer to these bindings.\n")
	for _, binding := range bindings {
		fmt.Fprintf(&b, "\n- `%s/%s` → `%s` (capability `%s`)", binding.Server, binding.RawName, binding.CallableName, binding.CapabilityID)
	}
	sk.Body = b.String()
	return sk
}

// Render prepares and renders a skill for a direct slash invocation.
func (s *Store) Render(sk Skill, args string) string { return Render(s.Prepare(sk), args) }

func bindAllowedTools(refs []string, bindings []tool.MCPBinding) []string {
	if len(refs) == 0 {
		return refs
	}
	out := make([]string, 0, len(refs))
	seen := map[string]bool{}
	appendOne := func(name string) {
		if name != "" && !seen[name] {
			seen[name] = true
			out = append(out, name)
		}
	}
	for _, ref := range refs {
		matches := map[string]tool.MCPBinding{}
		isPattern := strings.ContainsAny(ref, "*?[")
		for _, binding := range bindings {
			aliases := append(tool.MCPBindingAliases(binding), binding.CallableName)
			for _, alias := range aliases {
				matched := ref == alias
				if isPattern {
					matched, _ = path.Match(ref, alias)
				}
				if matched {
					matches[binding.CallableName] = binding
					break
				}
			}
		}
		if isPattern {
			// Preserve the original pattern so an existing broad allowlist such as
			// "*" keeps all of its prior tools. Add only canonical MCP names the
			// upstream/Claude pattern itself cannot match in Reasonix.
			appendOne(ref)
			names := make([]string, 0, len(matches))
			for name := range matches {
				names = append(names, name)
			}
			sort.Strings(names)
			for _, name := range names {
				if matched, err := path.Match(ref, name); err != nil || !matched {
					appendOne(name)
				}
				// Capability IDs are host-only allowlist entries consumed when the
				// session exposes this MCP tool solely through use_capability. Do not
				// add one when the authored pattern already grants the proxy itself.
				proxyMatched, _ := path.Match(ref, "use_capability")
				if !proxyMatched {
					appendOne(matches[name].CapabilityID)
				}
			}
			continue
		}
		if len(matches) == 1 {
			for name, binding := range matches {
				appendOne(name)
				appendOne(binding.CapabilityID)
			}
			continue
		}
		// Preserve unresolved or ambiguous literals. The child registry will not
		// gain any broader permission from them.
		appendOne(ref)
	}
	return out
}

// ValidateInvocation enforces profiles/requires frontmatter at the host tool
// boundary, including direct run_skill calls that bypass capability routing.
// Skill profiles frontmatter is diagnostic-only: it never blocks invocation.
// Required capabilities still gate execution.
func (s *Store) ValidateInvocation(sk Skill) error {
	if s == nil {
		return nil
	}
	if len(sk.Requires) > 0 && s.requiresReady != nil {
		if missing := s.requiresReady(sk.Requires); len(missing) > 0 {
			return fmt.Errorf("%w: skill %q requires unavailable capabilities: %s", ErrInvocationUnavailable, sk.Name, strings.Join(missing, ", "))
		}
	}
	return nil
}

// AllowedInProfile reports whether a skill lists profile among its frontmatter
// profiles. Empty profiles mean "all". Role settings no longer filter the
// model-visible skill index or block run_skill; this helper remains for doctor
// diagnostics and capability inventory reports.
func AllowedInProfile(sk Skill, profile string) bool {
	if len(sk.Profiles) == 0 {
		return true
	}
	want := normalizeRuntimeProfile(profile)
	if want == "" {
		return true
	}
	for _, candidate := range sk.Profiles {
		if normalizeRuntimeProfile(candidate) == want {
			return true
		}
	}
	return false
}

// FilterForProfile returns skills that declare eligibility for profile.
// Host boot no longer uses this to hide skills from the model; doctor and
// inventory tooling may still call it for recommended-profile diagnostics.
func FilterForProfile(skills []Skill, profile string) []Skill {
	out := make([]Skill, 0, len(skills))
	for _, sk := range skills {
		if AllowedInProfile(sk, profile) {
			out = append(out, sk)
		}
	}
	return out
}

func normalizeRuntimeProfile(profile string) string {
	switch strings.ToLower(strings.TrimSpace(profile)) {
	case "economy":
		return "economy"
	case "delivery":
		return "delivery"
	case "balanced", "full":
		return "balanced"
	default:
		return ""
	}
}

// HasProjectScope reports whether the store was configured with a project root.
func (s *Store) HasProjectScope() bool { return s.projectRoot != "" }

// PathStatus describes a root directory's readability, surfaced by `/skill paths`.
type PathStatus string

const (
	StatusOK           PathStatus = "ok"
	StatusMissing      PathStatus = "missing"
	StatusNotDirectory PathStatus = "not-directory"
	StatusUnreadable   PathStatus = "unreadable"
)

// Root is one discovery directory with its scope, priority, and status.
type Root struct {
	Dir      string
	Scope    Scope
	Priority int
	Status   PathStatus
}

type discoveryRoot struct {
	Root
	requireFlatMarker bool
	plugins           []string
	forceSubagent     bool
}

// roots returns the discovery directories, highest priority first: the
// convention dirs (config.ConventionDirs: .reasonix / .agents / .agent / .claude)
// under the project root → custom paths → the Reasonix home skills dir → other
// home-dir convention dirs. A later root never overrides an earlier one.
func (s *Store) roots() []discoveryRoot {
	if s == nil || s.disableDiscovery {
		return nil
	}
	type de struct {
		dir               string
		scope             Scope
		requireFlatMarker bool
	}
	var dirs []de
	if s.projectRoot != "" {
		for _, c := range config.ConventionDirs {
			dirs = append(dirs, de{filepath.Join(s.projectRoot, c, SkillsDirname), ScopeProject, c == ".claude"})
		}
	}
	for _, d := range s.customPaths {
		dirs = append(dirs, de{d, ScopeCustom, false})
	}
	if s.reasonixHomeDir != "" {
		dirs = append(dirs, de{filepath.Join(s.reasonixHomeDir, SkillsDirname), ScopeGlobal, false})
	}
	if config.IsolatedHomeDir() == "" {
		for _, c := range config.ConventionDirs {
			dir := filepath.Join(s.homeDir, c, SkillsDirname)
			if s.reasonixHomeDir != "" && config.CanonicalSkillPath(filepath.Dir(dir)) == config.CanonicalSkillPath(s.reasonixHomeDir) {
				continue
			}
			dirs = append(dirs, de{dir, ScopeGlobal, c == ".claude"})
		}
	}
	out := make([]discoveryRoot, 0, len(dirs))
	for _, d := range dirs {
		if s.excludedPaths[config.CanonicalSkillPath(d.dir)] {
			continue
		}
		key := config.CanonicalSkillPath(d.dir)
		out = append(out, discoveryRoot{
			Root:              Root{Dir: d.dir, Scope: d.scope, Priority: len(out), Status: pathStatus(d.dir)},
			requireFlatMarker: d.requireFlatMarker,
			plugins:           append([]string(nil), s.pluginPaths[key]...),
			forceSubagent:     len(s.pluginAgentPaths[key]) > 0,
		})
	}
	return out
}

func normalizePluginPaths(paths map[string][]string) map[string][]string {
	out := map[string][]string{}
	for path, plugins := range paths {
		key := config.CanonicalSkillPath(path)
		if key == "" {
			continue
		}
		for _, plugin := range plugins {
			plugin = strings.TrimSpace(plugin)
			if plugin == "" || stringSliceContains(out[key], plugin) {
				continue
			}
			out[key] = append(out[key], plugin)
		}
		sort.Strings(out[key])
	}
	return out
}

func stringSliceContains(items []string, want string) bool {
	return slices.Contains(items, want)
}

// Roots exposes the discovery directories with their status for `/skill paths`.
func (s *Store) Roots() []Root {
	roots := s.roots()
	out := make([]Root, 0, len(roots))
	for _, r := range roots {
		out = append(out, r.Root)
	}
	return out
}

func disabledNameSet(names []string) map[string]bool {
	out := map[string]bool{}
	for _, name := range names {
		if key := config.SkillNameKey(name); key != "" {
			out[key] = true
		}
	}
	return out
}

func (s *Store) disabledName(name string) bool {
	return s.disabled[config.SkillNameKey(name)]
}

func normalizeMaxDepth(depth int) int {
	const (
		defaultDepth = 3
		maxDepth     = 5
	)
	if depth == 0 {
		return defaultDepth
	}
	if depth < 1 {
		return 1
	}
	if depth > maxDepth {
		return maxDepth
	}
	return depth
}

// pathStatus classifies a root directory without failing on the common case of
// "not created yet".
func pathStatus(dir string) PathStatus {
	info, err := os.Stat(dir)
	if err != nil {
		if os.IsNotExist(err) {
			return StatusMissing
		}
		return StatusUnreadable
	}
	if !info.IsDir() {
		return StatusNotDirectory
	}
	if f, err := os.Open(dir); err != nil {
		return StatusUnreadable
	} else {
		_ = f.Close()
	}
	return StatusOK
}

func (s *Store) discoveredSkills() []Skill {
	if s == nil || s.disableDiscovery {
		return nil
	}
	var out []Skill
	for _, r := range s.roots() {
		if r.Status != StatusOK {
			continue
		}
		for _, sk := range s.discoverRoot(r) {
			if s.disabledName(sk.Name) {
				continue
			}
			if len(r.plugins) == 0 {
				out = append(out, sk)
				continue
			}
			for _, plugin := range r.plugins {
				owned := sk
				owned.Plugin = plugin
				if r.forceSubagent {
					owned.SlashPrefix = plugin + ":agent"
				}
				out = append(out, owned)
			}
		}
	}
	if !s.disableBuiltins {
		for _, sk := range builtinSkills() {
			if !s.disabledName(sk.Name) {
				out = append(out, sk)
			}
		}
	}
	return out
}

func (s *Store) enabledSkills() []Skill {
	byName := map[string]Skill{}
	for _, sk := range s.discoveredSkills() {
		if _, dup := byName[sk.Name]; !dup {
			byName[sk.Name] = sk
		}
	}
	out := make([]Skill, 0, len(byName))
	for _, sk := range byName {
		out = append(out, sk)
	}
	sort.Slice(out, func(i, j int) bool { return out[i].Name < out[j].Name })
	return out
}

// List returns every model-visible skill, deduped by its bare internal name
// (first/highest-priority root wins) and sorted for a cache-stable index.
// Role-setting profiles do not filter this surface.
func (s *Store) List() []Skill {
	return s.enabledSkills()
}

// SlashList returns the visible user-facing skill directory. Plugin skills are
// retained per package under /<plugin>:<name>, even when their bare names
// collide; non-plugin skills keep their existing short names.
func (s *Store) SlashList() []Skill {
	return VisibleSlashSkills(s.discoveredSkills())
}

// VisibleSlashSkills deduplicates skills by their user-facing slash name and
// returns them in deterministic display order.
func VisibleSlashSkills(skills []Skill) []Skill {
	byName := map[string]Skill{}
	for _, sk := range skills {
		name := sk.SlashName()
		if name == "" {
			continue
		}
		if _, dup := byName[name]; !dup {
			byName[name] = sk
		}
	}
	out := make([]Skill, 0, len(byName))
	for _, sk := range byName {
		out = append(out, sk)
	}
	sort.Slice(out, func(i, j int) bool { return out[i].SlashName() < out[j].SlashName() })
	return out
}

// ResolveSlashSkill resolves a visible qualified plugin name or a compatible
// short name. A short plugin name is rejected when multiple plugin packages
// contribute it; a higher-priority non-plugin winner keeps its short name.
func ResolveSlashSkill(skills []Skill, name string) (Skill, bool) {
	name = strings.TrimPrefix(strings.TrimSpace(name), "/")
	if name == "" {
		return Skill{}, false
	}
	for _, sk := range skills {
		if sk.SlashName() == name {
			return sk, true
		}
	}
	if strings.Contains(name, ":") || !IsValidName(name) {
		return Skill{}, false
	}
	var winner Skill
	var found bool
	plugins := map[string]bool{}
	for _, sk := range skills {
		if sk.Name != name {
			continue
		}
		if !found {
			winner, found = sk, true
		}
		if sk.Plugin != "" {
			plugins[sk.Plugin] = true
		}
	}
	if !found || winner.Plugin != "" && len(plugins) > 1 {
		return Skill{}, false
	}
	return winner, true
}

// Read resolves one skill by name, scanning the roots in priority order then the
// built-ins. ok is false when no such skill exists or the file is unreadable.
func (s *Store) Read(name string) (Skill, bool) {
	if !IsValidName(name) {
		return Skill{}, false
	}
	if s.disabledName(name) {
		return Skill{}, false
	}
	for _, sk := range s.enabledSkills() {
		if sk.Name == name {
			return sk, true
		}
	}
	return Skill{}, false
}

// ReadSlash resolves a user-entered slash identifier without changing the
// bare identifiers accepted by Read/run_skill.
func (s *Store) ReadSlash(name string) (Skill, bool) {
	return ResolveSlashSkill(s.discoveredSkills(), name)
}

func (s *Store) discoverRoot(r discoveryRoot) []Skill {
	var out []Skill
	s.scanDir(r.Dir, r.Scope, r.requireFlatMarker, 1, map[string]bool{}, &out)
	if r.forceSubagent {
		for i := range out {
			out[i].RunAs = RunSubagent
			out[i].Invocation = "manual"
			out[i].AllowedTools = mapClaudeAgentTools(out[i].AllowedTools)
			if isClaudeModelAlias(out[i].Model) {
				out[i].Model = ""
			}
		}
	}
	return out
}

func (s *Store) scanDir(dir string, scope Scope, requireFlatMarker bool, depth int, seen map[string]bool, out *[]Skill) {
	key := filepath.Clean(dir)
	if resolved, err := filepath.EvalSymlinks(dir); err == nil {
		key = filepath.Clean(resolved)
	}
	if seen[key] {
		return
	}
	seen[key] = true

	entries, err := os.ReadDir(dir)
	if err != nil {
		return
	}
	for _, e := range entries {
		sk, ok := s.readEntry(dir, scope, requireFlatMarker, e)
		if ok {
			if depth == 1 || strings.TrimSpace(sk.Description) != "" {
				*out = append(*out, sk)
			}
			continue
		}
		if depth >= s.maxDepth || !s.canScanChildDir(dir, e) {
			continue
		}
		s.scanDir(filepath.Join(dir, e.Name()), scope, requireFlatMarker, depth+1, seen, out)
	}
}

func (s *Store) canScanChildDir(dir string, e os.DirEntry) bool {
	name := e.Name()
	if shouldSkipScanDir(name) {
		return false
	}
	if e.IsDir() {
		return true
	}
	if !shouldStatEntryTarget(e.Type()) {
		return false
	}
	info, err := os.Stat(filepath.Join(dir, name))
	return err == nil && info.IsDir()
}

func shouldStatEntryTarget(mode os.FileMode) bool {
	return mode&os.ModeSymlink != 0 || mode&os.ModeIrregular != 0
}

func shouldSkipScanDir(name string) bool {
	if strings.HasPrefix(name, ".") {
		return true
	}
	switch strings.ToLower(name) {
	case "assets", "node_modules", "references", "scripts":
		return true
	default:
		return false
	}
}

// readEntry turns one directory entry into a skill. It resolves symlink and
// Windows reparse-style entries via os.Stat (os.ReadDir can report the link's
// own type, not its target's), so a linked skill directory or flat <name>.md is
// discovered like a real one; a broken link fails Stat and is skipped.
func (s *Store) readEntry(dir string, scope Scope, requireFlatMarker bool, e os.DirEntry) (Skill, bool) {
	name := e.Name()
	full := filepath.Join(dir, name)

	isDir := e.IsDir()
	isFile := e.Type().IsRegular()
	if !isDir && !isFile && shouldStatEntryTarget(e.Type()) {
		info, err := os.Stat(full) // follows the link
		if err != nil {
			return Skill{}, false // broken link
		}
		isDir = info.IsDir()
		isFile = info.Mode().IsRegular()
	}

	if isDir {
		if !IsValidName(name) {
			return Skill{}, false
		}
		file := filepath.Join(full, SkillFile)
		if _, err := os.Stat(file); err != nil {
			return Skill{}, false // a directory without a SKILL.md is not a skill
		}
		return s.parse(file, name, scope)
	}
	if isFile && strings.EqualFold(filepath.Ext(name), ".md") {
		stem := strings.TrimSuffix(name, filepath.Ext(name))
		if !IsValidName(stem) {
			return Skill{}, false
		}
		return s.parseFlat(full, stem, scope, requireFlatMarker)
	}
	return Skill{}, false
}

// parse reads and decodes one skill file. The frontmatter `name:` overrides the
// filename stem when valid; a missing `description:` is a warning, not a failure
// (the skill loads but won't appear in the model's index).
func (s *Store) parse(path, stem string, scope Scope) (Skill, bool) {
	return s.parseSkill(path, stem, scope, false)
}

// parseFlat reads a flat <name>.md skill candidate. Claude skill roots can also
// contain ordinary documentation, so those flat files need explicit skill
// frontmatter before they are treated as skills.
func (s *Store) parseFlat(path, stem string, scope Scope, requireSkillMarker bool) (Skill, bool) {
	return s.parseSkill(path, stem, scope, requireSkillMarker)
}

func (s *Store) parseSkill(path, stem string, scope Scope, requireSkillMarker bool) (Skill, bool) {
	b, err := fileencoding.ReadFileUTF8(path)
	if err != nil {
		return Skill{}, false
	}
	content := strings.TrimPrefix(strings.ReplaceAll(string(b), "\r\n", "\n"), "\uFEFF")
	fm, body := splitFrontmatter(content)
	if requireSkillMarker && !hasSkillMarker(content, fm) {
		return Skill{}, false
	}

	name := stem
	if v := fm[skillFrontmatterName]; v != "" && IsValidName(v) {
		name = v
	}
	desc := strings.TrimSpace(fm[skillFrontmatterDescription])
	if desc == "" {
		fmt.Fprintf(s.stderr, "warning: skill %q at %s has no description: — it will load but won't appear in the skills index\n", name, path)
	}
	sk := Skill{
		Name:         name,
		Description:  desc,
		Body:         loadBodyWithScripts(path, loadBodyWithReferences(path, strings.TrimSpace(body))),
		Scope:        scope,
		Path:         path,
		AllowedTools: parseAllowedTools(firstNonEmptySkillValue(fm[skillFrontmatterAllowedTools], fm["tools"])),
		RunAs:        parseRunAs(fm[skillFrontmatterRunAs], fm[skillFrontmatterContext], fm[skillFrontmatterAgent]),
		Model:        strings.TrimSpace(fm[skillFrontmatterModel]),
		Effort:       strings.TrimSpace(fm[skillFrontmatterEffort]),
		ReadOnly:     parseBoolFrontmatter(fm[skillFrontmatterReadOnly]),
		Triggers:     parseCSVFrontmatter(fm[skillFrontmatterTriggers]),
		NegativeTriggers: parseCSVFrontmatter(
			fm[skillFrontmatterNegativeTriggers],
		),
		AutoUse:        parseAutoUse(fm[skillFrontmatterAutoUse]),
		NeedsFreshData: parseBoolFrontmatter(fm[skillFrontmatterNeedsFreshData]),
		Cost:           parseCost(fm[skillFrontmatterCost]),
		Color:          strings.TrimSpace(fm[skillFrontmatterColor]),
		Invocation:     parseInvocation(fm[skillFrontmatterInvocation]),
		Requires:       parseCSVFrontmatter(fm[skillFrontmatterRequires]),
	}
	sk.Profiles, sk.InvalidProfiles = parseProfilesFrontmatter(fm[skillFrontmatterProfiles])
	return sk, true
}

func firstNonEmptySkillValue(values ...string) string {
	for _, value := range values {
		if strings.TrimSpace(value) != "" {
			return value
		}
	}
	return ""
}

func isClaudeModelAlias(model string) bool {
	switch strings.ToLower(strings.TrimSpace(model)) {
	case "sonnet", "opus", "haiku", "inherit":
		return true
	default:
		return false
	}
}

func mapClaudeAgentTools(in []string) []string {
	mapping := map[string]string{
		"read": "read_file", "write": "write_file", "edit": "edit_file",
		"bash": "bash", "grep": "grep", "glob": "glob", "ls": "ls",
		"webfetch": "web_fetch", "websearch": "web_search",
	}
	out := make([]string, 0, len(in))
	seen := map[string]bool{}
	for _, name := range in {
		mapped := strings.TrimSpace(name)
		if replacement := mapping[strings.ToLower(mapped)]; replacement != "" {
			mapped = replacement
		}
		if mapped != "" && !seen[mapped] {
			seen[mapped] = true
			out = append(out, mapped)
		}
	}
	return out
}

const (
	skillFrontmatterDescription      = "description"
	skillFrontmatterName             = "name"
	skillFrontmatterRunAs            = "runas"
	skillFrontmatterContext          = "context"
	skillFrontmatterAgent            = "agent"
	skillFrontmatterAllowedTools     = "allowed-tools"
	skillFrontmatterModel            = "model"
	skillFrontmatterEffort           = "effort"
	skillFrontmatterReadOnly         = "read-only"
	skillFrontmatterTriggers         = "triggers"
	skillFrontmatterNegativeTriggers = "negative-triggers"
	skillFrontmatterAutoUse          = "auto-use"
	skillFrontmatterNeedsFreshData   = "needs-fresh-data"
	skillFrontmatterCost             = "cost"
	skillFrontmatterColor            = "color"
	skillFrontmatterInvocation       = "invocation"
	skillFrontmatterRequires         = "requires"
	skillFrontmatterProfiles         = "profiles"
)

var skillMarkerFrontmatterKeys = []string{
	skillFrontmatterDescription,
	skillFrontmatterName,
	skillFrontmatterRunAs,
	skillFrontmatterContext,
	skillFrontmatterAgent,
	skillFrontmatterAllowedTools,
	skillFrontmatterModel,
	skillFrontmatterEffort,
	skillFrontmatterReadOnly,
	skillFrontmatterTriggers,
	skillFrontmatterNegativeTriggers,
	skillFrontmatterAutoUse,
	skillFrontmatterNeedsFreshData,
	skillFrontmatterCost,
	skillFrontmatterColor,
	skillFrontmatterInvocation,
	skillFrontmatterRequires,
	skillFrontmatterProfiles,
}

func hasSkillMarker(content string, fm map[string]string) bool {
	for _, key := range skillMarkerFrontmatterKeys {
		if strings.TrimSpace(fm[key]) != "" {
			return true
		}
	}
	return frontmatterHasSkillMarkerKey(content)
}

func frontmatterHasSkillMarkerKey(content string) bool {
	lines := strings.Split(content, "\n")
	if len(lines) == 0 || strings.TrimSpace(lines[0]) != "---" {
		return false
	}
	end := -1
	for i := 1; i < len(lines); i++ {
		if strings.TrimSpace(lines[i]) == "---" {
			end = i
			break
		}
	}
	if end < 0 {
		return false
	}
	for _, line := range lines[1:end] {
		key, _, ok := strings.Cut(line, ":")
		if ok && isSkillMarkerFrontmatterKey(strings.ToLower(strings.TrimSpace(key))) {
			return true
		}
	}
	return false
}

func isSkillMarkerFrontmatterKey(key string) bool {
	return slices.Contains(skillMarkerFrontmatterKeys, key)
}

// Create scaffolds a new skill stub at the chosen scope. Refuses to overwrite.
func (s *Store) Create(name string, scope Scope) (string, error) {
	return s.CreateWithContent(name, scope, stubBody(name))
}

// CreateWithContent writes caller-supplied file contents as a canonical
// <name>/SKILL.md skill, refusing to clobber an existing directory-layout or
// legacy flat skill of the same name. Returns the written path.
func (s *Store) CreateWithContent(name string, scope Scope, content string) (string, error) {
	if !IsValidName(name) {
		return "", fmt.Errorf("invalid skill name %q — use letters, digits, '_', '-', '.'", name)
	}
	var root string
	switch scope {
	case ScopeProject:
		if s.projectRoot == "" {
			return "", fmt.Errorf("project scope requires a workspace — run from a project directory, or use global scope")
		}
		root = filepath.Join(s.projectRoot, ".reasonix", SkillsDirname)
	default:
		root = s.globalSkillsRoot()
	}
	flat := filepath.Join(root, name+".md")
	folder := filepath.Join(root, name, SkillFile)
	if _, err := os.Stat(flat); err == nil {
		return "", fmt.Errorf("skill %q already exists at %s", name, flat)
	}
	if _, err := os.Stat(folder); err == nil {
		return "", fmt.Errorf("skill %q already exists at %s", name, folder)
	}
	if err := os.MkdirAll(filepath.Dir(folder), 0o755); err != nil {
		return "", err
	}
	// O_EXCL so a concurrent create (or an existing file) is reported, not clobbered.
	f, err := os.OpenFile(folder, os.O_CREATE|os.O_EXCL|os.O_WRONLY, 0o644)
	if err != nil {
		if os.IsExist(err) {
			return "", fmt.Errorf("skill %q already exists at %s", name, folder)
		}
		return "", err
	}
	defer f.Close()
	if _, err := f.WriteString(content); err != nil {
		return "", err
	}
	return folder, nil
}

// UpdateContent overwrites an existing user-authored skill's file contents in
// place. Refuses built-ins and a scope mismatch, mirroring Delete's rules —
// see Delete for why a mismatch must refuse rather than silently target the
// wrong file.
func (s *Store) UpdateContent(name string, scope Scope, content string) error {
	if scope == ScopeBuiltin {
		return fmt.Errorf("skill %q is built in and cannot be edited", name)
	}
	sk, ok := s.Read(name)
	if !ok {
		return fmt.Errorf("skill %q not found", name)
	}
	if sk.Scope != scope {
		return fmt.Errorf("skill %q resolves at scope %q, not %q — refusing to edit a different scope's file", name, sk.Scope, scope)
	}
	if sk.Path == "" || sk.Path == "(builtin)" {
		return fmt.Errorf("skill %q has no file to update", name)
	}
	if err := s.validateMutablePath(sk.Path, scope); err != nil {
		return fmt.Errorf("skill %q cannot be edited: %w", name, err)
	}
	info, err := os.Stat(sk.Path)
	if err != nil {
		return err
	}
	return fileutil.AtomicWriteFile(sk.Path, []byte(content), info.Mode().Perm())
}

// validateMutablePath rejects writes through linked files or directories. Skill
// discovery intentionally follows symlinks for read compatibility, but editing
// one must never replace content outside the configured scope root.
func (s *Store) validateMutablePath(path string, scope Scope) error {
	absPath, err := filepath.Abs(path)
	if err != nil {
		return err
	}
	for _, root := range s.roots() {
		if root.Scope != scope {
			continue
		}
		absRoot, err := filepath.Abs(root.Dir)
		if err != nil {
			continue
		}
		rel, err := filepath.Rel(absRoot, absPath)
		if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) {
			continue
		}
		current := absRoot
		parts := []string{"."}
		if rel != "." {
			parts = strings.Split(rel, string(filepath.Separator))
		}
		for _, part := range parts {
			if part != "." {
				current = filepath.Join(current, part)
			}
			info, err := os.Lstat(current)
			if err != nil {
				return err
			}
			if info.Mode()&os.ModeSymlink != 0 {
				return fmt.Errorf("path uses symbolic link %s", current)
			}
		}
		realRoot, err := filepath.EvalSymlinks(absRoot)
		if err != nil {
			return err
		}
		realPath, err := filepath.EvalSymlinks(absPath)
		if err != nil {
			return err
		}
		realRel, err := filepath.Rel(realRoot, realPath)
		if err != nil || realRel == ".." || strings.HasPrefix(realRel, ".."+string(filepath.Separator)) {
			return fmt.Errorf("resolved path is outside scope root %s", absRoot)
		}
		return nil
	}
	return fmt.Errorf("path is outside configured %s skill roots", scope)
}

// Delete removes a user-authored skill. Refuses built-ins (no file backs
// them) and refuses when the resolved skill's actual scope doesn't match the
// requested one — e.g. a project-scope delete for a name that only resolves
// at global scope, which would otherwise silently no-op against the wrong
// file while a same-named project-scope shadow kept showing up in List().
func (s *Store) Delete(name string, scope Scope) error {
	if scope == ScopeBuiltin {
		return fmt.Errorf("skill %q is built in and cannot be deleted", name)
	}
	sk, ok := s.Read(name)
	if !ok {
		return fmt.Errorf("skill %q not found", name)
	}
	if sk.Scope != scope {
		return fmt.Errorf("skill %q resolves at scope %q, not %q — refusing to delete a different scope's file", name, sk.Scope, scope)
	}
	if sk.Path == "" || sk.Path == "(builtin)" {
		return fmt.Errorf("skill %q has no file to delete", name)
	}
	if filepath.Base(sk.Path) == SkillFile {
		return os.RemoveAll(filepath.Dir(sk.Path)) // directory-layout skill: <name>/SKILL.md + siblings
	}
	return os.Remove(sk.Path) // legacy flat <name>.md skill
}

func (s *Store) globalSkillsRoot() string {
	if s.reasonixHomeDir != "" {
		return filepath.Join(s.reasonixHomeDir, SkillsDirname)
	}
	return filepath.Join(s.homeDir, ".reasonix", SkillsDirname)
}

// loadBodyWithReferences appends a directory-layout skill's sibling
// references/*.md files to its body (Anthropic Skills compatibility), so depth
// material is available without on-demand resolution. Flat skills have no
// references dir and are returned unchanged.
func loadBodyWithReferences(skillPath, body string) string {
	if filepath.Base(skillPath) != SkillFile {
		return body
	}
	refsDir := filepath.Join(filepath.Dir(skillPath), "references")
	entries, err := os.ReadDir(refsDir)
	if err != nil {
		return body
	}
	var names []string
	for _, e := range entries {
		if !e.IsDir() && strings.EqualFold(filepath.Ext(e.Name()), ".md") {
			names = append(names, e.Name())
		}
	}
	if len(names) == 0 {
		return body
	}
	sort.Strings(names)
	var b strings.Builder
	b.WriteString(body)
	for _, n := range names {
		content, err := fileencoding.ReadFileUTF8(filepath.Join(refsDir, n))
		if err != nil {
			continue
		}
		trimmed := strings.TrimSpace(string(content))
		if trimmed == "" {
			continue
		}
		slug := strings.TrimSuffix(n, filepath.Ext(n))
		b.WriteString("\n\n## Reference: " + slug + "\n\n" + trimmed)
	}
	return b.String()
}

// loadBodyWithScripts appends a directory-layout skill's sibling scripts/
// directory listing to the body, so the model knows what scripts are
// available and can run them via bash (inheriting sandbox, gate, hooks).
func loadBodyWithScripts(skillPath, body string) string {
	if filepath.Base(skillPath) != SkillFile {
		return body
	}
	scriptsDir := filepath.Join(filepath.Dir(skillPath), "scripts")
	entries, err := os.ReadDir(scriptsDir)
	if err != nil {
		return body
	}
	var names []string
	for _, e := range entries {
		// Filter hidden files — bash should not see config dotfiles in scripts/.
		if e.IsDir() || strings.HasPrefix(e.Name(), ".") {
			continue
		}
		if !isScriptExt(filepath.Ext(e.Name())) {
			continue
		}
		names = append(names, e.Name())
	}
	if len(names) == 0 {
		return body
	}
	sort.Strings(names)
	var b strings.Builder
	b.WriteString(body)
	b.WriteString("\n\n## Scripts\n\nRun a listed script with bash using the exact path shown below; quote the path if it contains spaces.\n\n")
	for _, n := range names {
		b.WriteString("- `" + filepath.Join(scriptsDir, n) + "`\n")
	}
	return b.String()
}

func isScriptExt(ext string) bool {
	switch strings.ToLower(ext) {
	case "", ".sh", ".py", ".js", ".ts", ".rb", ".pl", ".php", ".ps1":
		return true
	default:
		return false
	}
}

// parseAllowedTools splits a comma-separated `allowed-tools` value into trimmed,
// non-empty tool names; nil when absent.
func parseAllowedTools(raw string) []string {
	return parseCSVFrontmatter(raw)
}

// parseCSVFrontmatter splits simple comma-separated frontmatter values. Full
// YAML lists are intentionally out of scope for the existing frontmatter parser.
func parseCSVFrontmatter(raw string) []string {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return nil
	}
	if strings.HasPrefix(raw, "[") && strings.HasSuffix(raw, "]") {
		raw = strings.TrimSpace(raw[1 : len(raw)-1])
	}
	var out []string
	for p := range strings.SplitSeq(raw, ",") {
		if t := strings.Trim(strings.TrimSpace(p), `"'`); t != "" {
			out = append(out, t)
		}
	}
	return out
}

func parseAutoUse(raw string) string {
	switch strings.ToLower(strings.TrimSpace(raw)) {
	case "off", "suggest", "prefer", "require":
		return strings.ToLower(strings.TrimSpace(raw))
	default:
		return ""
	}
}

// parseProfilesFrontmatter keeps only economy|balanced|delivery values and
// returns the rejected ones separately so doctor can surface typos instead of
// the parser hiding them.
func parseProfilesFrontmatter(raw string) (valid, invalid []string) {
	seen := map[string]bool{}
	for _, p := range parseCSVFrontmatter(raw) {
		p = strings.ToLower(strings.TrimSpace(p))
		switch p {
		case "economy", "balanced", "delivery":
			if !seen[p] {
				seen[p] = true
				valid = append(valid, p)
			}
		case "":
		default:
			if !seen[p] {
				seen[p] = true
				invalid = append(invalid, p)
			}
		}
	}
	return valid, invalid
}

func parseBoolFrontmatter(raw string) bool {
	switch strings.ToLower(strings.TrimSpace(raw)) {
	case "true", "yes", "1", "on":
		return true
	default:
		return false
	}
}

func parseCost(raw string) string {
	switch strings.ToLower(strings.TrimSpace(raw)) {
	case "low", "medium", "high":
		return strings.ToLower(strings.TrimSpace(raw))
	default:
		return ""
	}
}

// parseInvocation maps frontmatter to an invocation mode. Anything other than
// "manual" (including absent) is "auto" — the existing, universal behavior.
func parseInvocation(raw string) string {
	if strings.EqualFold(strings.TrimSpace(raw), "manual") {
		return "manual"
	}
	return "auto"
}

// parseRunAs maps frontmatter to a run mode. An unknown value defaults to the
// safe (non-spawning) inline mode; a `context: fork` or a non-empty `agent:`
// field (cross-tool conventions) signals subagent isolation.
func parseRunAs(runAs, context, agent string) RunAs {
	if strings.TrimSpace(runAs) == "subagent" {
		return RunSubagent
	}
	if strings.EqualFold(strings.TrimSpace(context), "fork") {
		return RunSubagent
	}
	if strings.TrimSpace(agent) != "" {
		return RunSubagent
	}
	return RunInline
}

// stubBody is the scaffold written by `/skill new` — minimal frontmatter plus
// guidance the author fills in.
func stubBody(name string) string {
	return "---\nname: " + name + "\ndescription: One-liner — what does this skill do?\n---\n\n# " + name + `

Replace this body with the playbook the model should follow when this skill is invoked.

Tips:
- Reference tools by name (bash, edit_file, grep, read_file, ...)
- Add ` + "`runAs: subagent`" + ` to frontmatter to spawn an isolated subagent loop
- Add ` + "`allowed-tools: read_file, grep`" + ` to scope a subagent's tools
`
}

// resolveCustomPaths expands "~" and makes each custom path absolute relative to
// baseDir.
func resolveCustomPaths(paths []string, baseDir, homeDir string) []string {
	out := make([]string, 0, len(paths))
	for _, p := range paths {
		trimmed := strings.TrimSpace(p)
		if trimmed == "" {
			continue
		}
		switch {
		case trimmed == "~":
			trimmed = homeDir
		case strings.HasPrefix(trimmed, "~/") || strings.HasPrefix(trimmed, `~\`):
			trimmed = filepath.Join(homeDir, trimmed[2:])
		}
		if !filepath.IsAbs(trimmed) {
			trimmed = filepath.Join(baseDir, trimmed)
		}
		out = append(out, filepath.Clean(trimmed))
	}
	return out
}

// dedupePaths drops duplicate custom roots, preserving order.
func dedupePaths(paths []string) []string {
	seen := map[string]bool{}
	out := paths[:0]
	for _, p := range paths {
		if seen[p] {
			continue
		}
		seen[p] = true
		out = append(out, p)
	}
	return out
}

// splitFrontmatter is a thin wrapper kept for internal use; the real parser
// lives in internal/frontmatter.
func splitFrontmatter(s string) (map[string]string, string) {
	return frontmatter.Split(s)
}