package main

// The agent's configuration, registered through this module at three scopes (novox/hq ADR 0216, to-be 36 §8).
//
// Every registration is one key in the module's `config` state (ADR 0201):
//
//	mesh.<kind>.<name>          every node running the agent
//	node.<node>.<kind>.<name>   one node — a list of nodes is one key each
//	home.<node>.<kind>.<name>   the operator account's own agent directory on one node
//
// Every instance watches the state and takes what applies to it. What it takes lands in one place per kind,
// the one place the vendor honours for it:
//
//	skill, agent, command, output-style   the plugin `nox-mesh`, in a marketplace in the managed directory
//	                                     (at the home scope: the home's own directories)
//	instructions                         sections of the managed instruction file (home: a rule file)
//
// **What a session runs or obeys is not registered here** (novox/hq issue 340). A hook runs a command, and the
// managed settings say what runs without asking, in every session on every node the registration reaches, as
// whoever starts it — the operator, whose account holds root. The tool runner acts for any caller of the mesh MCP
// server and is not told who called, so a registration through these tools could come from an agent confined on
// another node. Hooks, permissions and the rest of the managed settings are the operator's, set at the
// controller's terminal in this module's `managed_settings` setting (the controller refuses that key through a
// verb); the kinds `hook` and `settings` are refused at registration and never taken from the state, and an
// item that would run something itself — a skill's or a command's shell lines, a hook, a server or a mode in its
// front matter, tools it pre-approves — is refused too. What may still be registered is text a session reads.
//
// Tool servers keep their own state and file (`servers`, the managed tool-server file): the exclusive file
// would block a plugin's.

import (
	"crypto/sha256"
	"encoding/hex"
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"path"
	"path/filepath"
	"regexp"
	"sort"
	"strings"
	"sync"
	"time"

	"gopkg.in/yaml.v3"
)

// Plugin is the plugin's name, and its marketplace's: what its items are called in a session, `nox-mesh:<name>`.
const Plugin = "nox-mesh"

// MarketplaceDir is where the marketplace is written, inside the managed directory.
const MarketplaceDir = "marketplace"

// MaxItemBytes is the most one registration may carry, its files included: well under the bus's message limit.
const MaxItemBytes = 256 << 10

// The kinds a registration may be.
const (
	KindSkill        = "skill"
	KindAgent        = "agent"
	KindCommand      = "command"
	KindHook         = "hook"
	KindOutputStyle  = "output-style"
	KindInstructions = "instructions"
	KindSettings     = "settings"
)

// Kinds is every kind, in the order a list shows them.
var Kinds = []string{KindSkill, KindAgent, KindCommand, KindHook, KindOutputStyle, KindInstructions, KindSettings}

// The scopes.
const (
	ScopeMesh = "mesh"
	ScopeNode = "node"
	ScopeHome = "home"
)

// SettingsName is the one name a settings registration has: a scope holds one set of settings.
const SettingsName = "settings"

var itemName = regexp.MustCompile(`^[a-z0-9][a-z0-9-]{0,63}$`)

// nodeName is what a node may be called in a key.
var nodeName = regexp.MustCompile(`^[a-z0-9][a-z0-9-]{0,62}$`)

// AtTheTerminal is how a hook, a permission rule or any other managed setting is set now (novox/hq issue 340):
// in this module's `managed_settings` setting, at the controller's terminal, which refuses it through a verb.
const AtTheTerminal = "mesh-cli settings set claude-code '{\"managed_settings\": {...}}' [--node <node>], " +
	"typed by the operator at the controller's terminal: mesh-cli (nox) on the control-node (novox/hq ADR 0272)"

// RunsInASession says why a kind is never registered through this module: what it holds runs in, or is obeyed
// by, every session it reaches, as whoever starts that session (novox/hq issue 340).
func RunsInASession(kind string) string {
	what := map[string]string{
		KindHook:     "a hook runs its command in every session it reaches",
		KindSettings: "the managed settings say what runs in every session without asking — permissions, hooks, the status line, the environment",
	}[kind]
	return what + ", as whoever starts that session — the operator, whose account holds root — and the tool runner is " +
		"not told who called it, so an agent on another node could register one. It is set at the controller's " +
		"terminal only: " + AtTheTerminal + " (novox/hq issue 340)"
}

// runsFrontMatter are the front matter keys of a skill, a subagent or a command that make it run something
// itself or loosen what runs (novox/hq issue 340): a hook, a tool server, a permission mode, tools it
// pre-approves. Compared lower-case with - and _ taken out.
var runsFrontMatter = map[string]string{
	"hooks":          "hooks run a command when the item is used",
	"mcpservers":     "a tool server starts a program",
	"permissionmode": "a permission mode changes what runs without asking",
	"allowedtools":   "allowed-tools lets the tools it names run without asking",
}

// shellLine is a skill's or a command's shell line, run when it is loaded and its output put in the prompt:
// !`command` inline, or a fenced block opened with ```!.
var shellLine = regexp.MustCompile("!`[^`\n]+`|(?m)^[ \t]*```!")

// fileRef is a file the agent may read into the prompt when it loads a skill or a command: `@` and a path, at the
// start of a line or after a space, a bracket or a quote. Any such word counts, a path without a dot or a slash
// (`@Makefile`) as much as one with: refused unless it is one of the item's own files, rather than guessed at.
var fileRef = regexp.MustCompile(`(?:^|[\s(\[{"'<])@([^\s` + "`" + `"')\]}>]+)`)

// runsProblem says why an item's text would run something in a session by itself, or "": the shell lines the
// agent runs when it loads a skill or a command, the front matter keys that start, run or pre-approve, front
// matter the module cannot read for certain, and a file outside the item that the agent would read in.
func runsProblem(it Item) string {
	if it.Kind != KindSkill && it.Kind != KindAgent && it.Kind != KindCommand {
		return ""
	}
	rels := make([]string, 0, len(it.Files))
	for rel := range it.Files {
		rels = append(rels, rel)
	}
	sort.Strings(rels)
	for _, rel := range rels {
		if !strings.HasSuffix(rel, ".md") {
			continue // a script beside a skill runs only when the agent runs it, through the session's own rules
		}
		content := strings.TrimPrefix(it.Files[rel], "\ufeff")
		if shellLine.MatchString(content) {
			return fmt.Sprintf("%s holds a shell line (!`…` or ```!), which the agent runs when it loads the %s, "+
				"before any permission is asked; nothing registered through this module runs by itself in a "+
				"session (novox/hq issue 340)", rel, it.Kind)
		}
		keys, problem := frontMatterKeys(content)
		if problem != "" {
			return fmt.Sprintf("%s: %s, so what it asks of a session cannot be judged; it is refused rather than "+
				"guessed at (novox/hq issue 340)", rel, problem)
		}
		for _, key := range keys {
			norm := strings.ToLower(strings.NewReplacer("-", "", "_", "").Replace(key))
			if why, ok := runsFrontMatter[norm]; ok {
				return fmt.Sprintf("%s says %q in its front matter: %s. Nothing registered through this module "+
					"runs or loosens what runs in a session; that is the operator's, at the controller's "+
					"terminal (novox/hq issue 340)", rel, key, why)
			}
		}
		if it.Kind == KindSkill || it.Kind == KindCommand {
			for _, m := range fileRef.FindAllStringSubmatch(content, -1) {
				ref := strings.TrimRight(m[1], ".,;:!?")
				if ref == "" {
					continue
				}
				if _, own := it.Files[ref]; !own || pathProblem(ref) != "" {
					return fmt.Sprintf("%s refers to @%s, a file outside the %s that the agent reads into its "+
						"prompt when it loads it; a registered item refers only to its own files (novox/hq issue 340)",
						rel, ref, it.Kind)
				}
			}
		}
	}
	return ""
}

// frontMatterKeys are the top-level keys of a markdown file's front matter, read as YAML: the block between a
// first line `---` (after a byte-order mark) and the next. A block that does not close, does not parse, or is not
// a mapping is a problem: the agent's own reader may take from it what this one cannot see.
func frontMatterKeys(content string) ([]string, string) {
	content = strings.ReplaceAll(strings.TrimPrefix(content, "\ufeff"), "\r\n", "\n")
	lines := strings.Split(content, "\n")
	first := 0
	for first < len(lines) && strings.TrimSpace(lines[first]) == "" {
		first++
	}
	if first == len(lines) || strings.TrimSpace(lines[first]) != "---" {
		return nil, ""
	}
	end := -1
	for i := first + 1; i < len(lines); i++ {
		if t := strings.TrimSpace(lines[i]); t == "---" || t == "..." {
			end = i
			break
		}
	}
	if end < 0 {
		return nil, "its front matter does not close"
	}
	block := strings.Join(lines[first+1:end], "\n")
	if strings.TrimSpace(block) == "" {
		return nil, ""
	}
	var node yaml.Node
	if err := yaml.Unmarshal([]byte(block), &node); err != nil {
		return nil, "its front matter is not YAML (" + err.Error() + ")"
	}
	var top map[string]any
	if err := node.Decode(&top); err != nil {
		return nil, "its front matter is not a mapping of keys (" + err.Error() + ")"
	}
	keys := make([]string, 0, len(top))
	for k := range top {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	return keys, ""
}

// Item is one registration, as the state keeps it.
type Item struct {
	Kind  string `json:"kind"`
	Name  string `json:"name"`
	Scope string `json:"scope"`
	// Files are the item's files by path relative to the item: a skill's SKILL.md and whatever sits beside
	// it; for the one-file kinds, `<name>.md`; a hook's scripts.
	Files map[string]string `json:"files,omitempty"`
	// A hook's event, matcher and command. In the command, ${HOOK_DIR} is the directory its files are in.
	Event   string `json:"event,omitempty"`
	Matcher string `json:"matcher,omitempty"`
	Command string `json:"command,omitempty"`
	// Settings, for the settings kind: keys of the vendor's settings file.
	Settings map[string]any `json:"settings,omitempty"`
	// Where it was registered from, and when.
	By string `json:"by,omitempty"`
	At string `json:"at,omitempty"`
}

// Key is where an item lives in the state, for one node (ignored at the mesh scope).
func (it Item) Key(node string) string {
	if it.Scope == ScopeMesh {
		return ScopeMesh + "." + it.Kind + "." + it.Name
	}
	return it.Scope + "." + node + "." + it.Kind + "." + it.Name
}

// ParseKey reads a key back: its scope, the node it is for ("" at the mesh scope), the kind and the name.
func ParseKey(key string) (scope, node, kind, name string, ok bool) {
	parts := strings.Split(key, ".")
	switch {
	case len(parts) == 3 && parts[0] == ScopeMesh:
		return ScopeMesh, "", parts[1], parts[2], true
	case len(parts) == 4 && (parts[0] == ScopeNode || parts[0] == ScopeHome):
		return parts[0], parts[1], parts[2], parts[3], true
	}
	return "", "", "", "", false
}

func knownKind(k string) bool {
	for _, x := range Kinds {
		if x == k {
			return true
		}
	}
	return false
}

// Problem says why an item cannot be registered, or "".
func (it Item) Problem() string {
	if problem := it.shapeProblem(); problem != "" {
		return problem
	}
	return runsProblem(it)
}

// shapeProblem says why an item is not well formed, or "": its kind, scope, name, paths, files and size, without
// judging what its text asks of a session — which the operator's own text, set at the terminal, may.
func (it Item) shapeProblem() string {
	if !knownKind(it.Kind) {
		return fmt.Sprintf("%q is not a kind: %s", it.Kind, strings.Join(Kinds, ", "))
	}
	if it.Scope != ScopeMesh && it.Scope != ScopeNode && it.Scope != ScopeHome {
		return fmt.Sprintf("%q is not a scope: mesh, node or home", it.Scope)
	}
	if it.Kind == KindHook || it.Kind == KindSettings {
		return RunsInASession(it.Kind)
	}
	if !itemName.MatchString(it.Name) {
		return fmt.Sprintf("%q is not a name: lower-case letters, digits and -, at most 64", it.Name)
	}
	for rel := range it.Files {
		if problem := pathProblem(rel); problem != "" {
			return problem
		}
		for other := range it.Files {
			if strings.HasPrefix(other, rel+"/") {
				return fmt.Sprintf("%q is a file and also the directory of %q", rel, other)
			}
		}
	}
	switch it.Kind {
	case KindSkill:
		if _, ok := it.Files["SKILL.md"]; !ok {
			return "a skill needs a SKILL.md"
		}
	case KindAgent, KindCommand, KindOutputStyle, KindInstructions:
		if len(it.Files) != 1 || strings.TrimSpace(it.Files[it.Name+".md"]) == "" {
			return "this kind is one file, " + it.Name + ".md, with content"
		}
	}
	if n := it.size(); n > MaxItemBytes {
		return fmt.Sprintf("%d bytes: more than the %d one registration may carry", n, MaxItemBytes)
	}
	return ""
}

// pathProblem says why a file's path is not one inside the item, or "": relative, slash-separated, every
// segment a real name — never empty, `.` or `..`.
func pathProblem(rel string) string {
	if rel == "" || path.IsAbs(rel) || strings.ContainsAny(rel, "\\\x00") {
		return fmt.Sprintf("%q is not a path inside the item", rel)
	}
	for _, seg := range strings.Split(rel, "/") {
		if seg == "" || seg == "." || seg == ".." {
			return fmt.Sprintf("%q is not a path inside the item", rel)
		}
	}
	return ""
}

func (it Item) size() int {
	raw, _ := json.Marshal(it)
	return len(raw)
}

// ---- the view -------------------------------------------------------------------------------------

// ConfigView is what this node takes from the `config` state: every mesh item, and the node and home items
// for this node — kept in memory from the watch and written through to the module's own file, so the
// managed directory renders without the bus.
type ConfigView struct {
	p     Paths
	mu    sync.Mutex
	items map[string]Item
}

// NewConfigView is the view as last written through, or empty.
func NewConfigView(p Paths) *ConfigView {
	var kept map[string]Item
	_ = readJSON(p.config(), &kept)
	return &ConfigView{p: p, items: Taken(kept)}
}

// Taken is what of the items kept in the module's own file may be rendered: each judged again as the state's watch
// judges it, so what was written through before this module refused some kinds — a hook, settings, an item that
// runs something by itself — is never rendered (novox/hq issue 340).
func Taken(kept map[string]Item) map[string]Item {
	out := map[string]Item{}
	for key, it := range kept {
		_, node, _, _, ok := ParseKey(key)
		if ok && it.Problem() == "" && it.Key(node) == key {
			out[key] = it
		}
	}
	return out
}

// Applies says whether a key is this node's to take.
func (v *ConfigView) Applies(key string) bool {
	scope, node, _, _, ok := ParseKey(key)
	return ok && (scope == ScopeMesh || node == v.p.Node)
}

// Take takes one change, and answers whether what applies to this node changed.
func (v *ConfigView) Take(key, op string, item *Item) bool {
	if !v.Applies(key) {
		return false
	}
	_, node, _, _, _ := ParseKey(key)
	v.mu.Lock()
	defer v.mu.Unlock()
	// Only an item that is what its key says: a key decides which nodes take an item, the item where it
	// lands, and the two must agree — a mesh key holding a home item would land in every home.
	if op == "put" && item != nil && item.Problem() == "" && item.Key(node) == key {
		v.items[key] = *item
	} else {
		delete(v.items, key)
	}
	return v.writeThroughLocked()
}

// Prune drops what the view holds and the state no longer does: a registration removed while this node
// was away is never handed over by the watch, which hands over what is there, not what went.
func (v *ConfigView) Prune(present []string) bool {
	keep := map[string]bool{}
	for _, k := range present {
		keep[k] = true
	}
	v.mu.Lock()
	defer v.mu.Unlock()
	for k := range v.items {
		if !keep[k] {
			delete(v.items, k)
		}
	}
	return v.writeThroughLocked()
}

// Items is what applies here, by key.
func (v *ConfigView) Items() map[string]Item {
	v.mu.Lock()
	defer v.mu.Unlock()
	out := make(map[string]Item, len(v.items))
	for k, it := range v.items {
		out[k] = it
	}
	return out
}

// writeThroughLocked writes the view to its file, with v.mu held: the snapshot and the write are one step, so
// an older snapshot never lands after a newer one.
func (v *ConfigView) writeThroughLocked() bool {
	now, _ := indented(v.items)
	before, _ := fsys.ReadFile(v.p.config())
	if string(before) == string(now) {
		return false
	}
	_ = fsys.WriteFile(v.p.config(), now, 0o600)
	return true
}

// Config is what applies to this node, sorted for rendering.
type Config struct {
	Mesh, Node, Home []Item
	// Terminal is the shared text the operator set at the controller's terminal, in this module's settings
	// (novox/hq issue 340): laid over what was registered for the mesh and the node, for every session here.
	Terminal []Item
	// Approved is the sections the operator approved through the operator channel (novox/hq ADR 0274), as this
	// node proved and keeps them, that reach this node.
	Approved []ApprovedSection
}

// ConfigOf sorts the items that apply here by scope, each scope by kind and name.
func ConfigOf(items map[string]Item) Config {
	var c Config
	for _, it := range items {
		switch it.Scope {
		case ScopeMesh:
			c.Mesh = append(c.Mesh, it)
		case ScopeNode:
			c.Node = append(c.Node, it)
		case ScopeHome:
			c.Home = append(c.Home, it)
		}
	}
	for _, list := range [][]Item{c.Mesh, c.Node, c.Home} {
		sort.Slice(list, func(i, j int) bool {
			if list[i].Kind != list[j].Kind {
				return list[i].Kind < list[j].Kind
			}
			return list[i].Name < list[j].Name
		})
	}
	return c
}

// ---- rendering --------------------------------------------------------------------------------------

// PluginFile is one file of the marketplace: its content and whether it is run — or, for a binary, the
// file it is copied from (the guard's, which is this module's own executable).
type PluginFile struct {
	Content    string
	Executable bool
	From       string `json:",omitempty"`
}

// GuardDir is where the guard on the agent's shell lives in the plugin (novox/hq ADR 0245): its binary and
// what it is given. Outside hooks/, so no registered hook's name can be it.
const GuardDir = "guard"

// GuardFiles are the guard as the plugin carries it: the binary to copy and the data it judges with.
type GuardFiles struct {
	Exe  string
	Data GuardData
}

// GuardMatcher is what the guard is asked about: every tool. Its own rules judge the shell and the agent's file
// edits and let every other tool through; the rule of the account agents run as (novox/hq ADR 0266) refuses
// every tool of a session running as another, reading and the mesh's tools included, so that session can do
// nothing at all.
const GuardMatcher = "*"

// GuardCommand is the hook's command line: by its path under the managed directory, root's — never the
// copy the agent may keep of a plugin, which the session could change.
func GuardCommand() string {
	dir := filepath.Join(ManagedDir, MarketplaceDir, "plugins", Plugin, GuardDir)
	return `"` + filepath.Join(dir, "guard") + `" guard "` + filepath.Join(dir, "guard.json") + `"`
}

// Marketplace is the marketplace directory's whole content, by path inside it. A node item of a name laid
// over a mesh item of the same kind and name: the node's wins.
func Marketplace(c Config) map[string]PluginFile { return MarketplaceWith(c, nil) }

// MarketplaceWith is the marketplace with the guard on the agent's shell, when there is one to place: its
// hook first, before any registered one.
func MarketplaceWith(c Config, guard *GuardFiles) map[string]PluginFile {
	root := "plugins/" + Plugin + "/"
	out := map[string]PluginFile{
		".claude-plugin/marketplace.json": {Content: jsonFile(map[string]any{
			"name":  Plugin,
			"owner": map[string]any{"name": "the mesh"},
			"plugins": []any{map[string]any{"name": Plugin, "source": "./plugins/" + Plugin,
				"description": "What the mesh registered for the agent: written by the claude-code module, never by hand."}},
		})},
		root + ".claude-plugin/plugin.json": {Content: jsonFile(map[string]any{
			"name": Plugin, "version": "1.0.0",
			"description": "What the mesh registered for the agent: written by the claude-code module, never by hand.",
			"author":      map[string]any{"name": "the mesh"},
		})},
	}
	chosen := map[string]Item{}
	for _, layer := range [][]Item{c.Mesh, c.Node, c.Terminal} {
		for _, it := range layer {
			chosen[it.Kind+"/"+it.Name] = it
		}
	}
	keys := make([]string, 0, len(chosen))
	for k := range chosen {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	hooks := map[string][]any{}
	if guard != nil && guard.Exe != "" {
		out[root+GuardDir+"/guard"] = PluginFile{From: guard.Exe, Executable: true}
		out[root+GuardDir+"/guard.json"] = PluginFile{Content: jsonFile(guard.Data)}
		hooks["PreToolUse"] = append(hooks["PreToolUse"], map[string]any{"matcher": GuardMatcher,
			"hooks": []any{map[string]any{"type": "command", "command": GuardCommand(), "timeout": 15}}})
	}
	for _, k := range keys {
		it := chosen[k]
		switch it.Kind {
		case KindSkill:
			for rel, content := range it.Files {
				out[root+"skills/"+it.Name+"/"+rel] = PluginFile{Content: content, Executable: isScript(rel, content)}
			}
		case KindAgent:
			out[root+"agents/"+it.Name+".md"] = PluginFile{Content: it.Files[it.Name+".md"]}
		case KindCommand:
			out[root+"commands/"+it.Name+".md"] = PluginFile{Content: it.Files[it.Name+".md"]}
		case KindOutputStyle:
			out[root+"output-styles/"+it.Name+".md"] = PluginFile{Content: it.Files[it.Name+".md"]}
		}
		// A hook is never rendered from a registration (novox/hq issue 340): the plugin's hooks are the mesh's own
		// guard alone, and any other is the operator's, in the managed settings set at the controller's terminal.
	}
	if len(hooks) > 0 {
		out[root+"hooks/hooks.json"] = PluginFile{Content: jsonFile(map[string]any{"hooks": hooks})}
	}
	return out
}

func isScript(rel, content string) bool {
	return strings.HasPrefix(content, "#!") || strings.HasSuffix(rel, ".sh")
}

// MarketplaceKeys are the two managed settings keys that name the marketplace and enable the plugin.
func MarketplaceKeys() map[string]any {
	return map[string]any{
		"extraKnownMarketplaces": map[string]any{Plugin: map[string]any{
			"source": map[string]any{"source": "directory", "path": filepath.Join(ManagedDir, MarketplaceDir)}}},
		"enabledPlugins": map[string]any{Plugin + "@" + Plugin: true},
	}
}

// mergeSettings lays b over a: objects are merged key by key, lists are joined without repeats (a
// permission rule or an auto-mode rule added for a node adds to the mesh's), and anything else is b's.
func mergeSettings(a, b map[string]any) map[string]any {
	out := map[string]any{}
	for k, v := range a {
		out[k] = v
	}
	for k, v := range b {
		switch nb := v.(type) {
		case map[string]any:
			if na, ok := out[k].(map[string]any); ok {
				out[k] = mergeSettings(na, nb)
				continue
			}
		case []any:
			if la, ok := out[k].([]any); ok {
				joined := append([]any{}, la...)
				seen := map[string]bool{}
				for _, x := range la {
					raw, _ := json.Marshal(x)
					seen[string(raw)] = true
				}
				for _, x := range nb {
					raw, _ := json.Marshal(x)
					if !seen[string(raw)] {
						seen[string(raw)] = true
						joined = append(joined, x)
					}
				}
				out[k] = joined
				continue
			}
		}
		out[k] = v
	}
	return out
}

// InstructionSections is what the managed instruction file adds after the mesh's own text: the sections
// registered for the mesh, then those for this node.
func InstructionSections(c Config) string {
	var b strings.Builder
	registered := "Registered through the `claude-code` module before that moved to the controller's terminal; change them there, in the module's `instructions` setting."
	for _, part := range []struct {
		title, note string
		items       []Item
	}{{"Instructions for every node", registered, c.Mesh}, {"Instructions for this node", registered, c.Node},
		{"Instructions set at the controller's terminal", "Set in the `claude-code` module's `instructions` setting, at the controller's terminal.", c.Terminal}} {
		var sections []Item
		for _, it := range part.items {
			if it.Kind == KindInstructions {
				sections = append(sections, it)
			}
		}
		if len(sections) == 0 {
			continue
		}
		fmt.Fprintf(&b, "\n## %s\n\n%s\n", part.title, part.note)
		for _, it := range sections {
			fmt.Fprintf(&b, "\n### %s\n\n%s\n", it.Name, strings.TrimSpace(it.Files[it.Name+".md"]))
		}
	}
	if len(c.Approved) > 0 {
		b.WriteString("\n## Instructions the operator approved\n\nProposed by an agent through the `claude-code` module and " +
			"approved by the operator on a channel that proves who answered (novox/hq ADR 0274). Changed or removed only the " +
			"same way: `claude_code_instructions_propose`.\n")
		for _, s := range c.Approved {
			fmt.Fprintf(&b, "\n### %s\n\n*Proposed from %s; approved %s.*\n\n%s\n", s.Name, s.From,
				s.Approved.UTC().Format("2006-01-02 15:04 UTC"), strings.TrimSpace(s.Text))
		}
	}
	return b.String()
}

// HomeFiles is what the home scope places in the operator account's agent directory, by path relative to
// that directory.
func HomeFiles(c Config) map[string]string {
	out := map[string]string{}
	for _, it := range c.Home {
		switch it.Kind {
		case KindSkill:
			for rel, content := range it.Files {
				out["skills/"+it.Name+"/"+rel] = content
			}
		case KindAgent:
			out["agents/"+it.Name+".md"] = it.Files[it.Name+".md"]
		case KindCommand:
			out["commands/"+it.Name+".md"] = it.Files[it.Name+".md"]
		case KindOutputStyle:
			out["output-styles/"+it.Name+".md"] = it.Files[it.Name+".md"]
		case KindInstructions:
			out["rules/"+it.Name+".md"] = it.Files[it.Name+".md"]
		}
	}
	return out
}

// ---- the home ---------------------------------------------------------------------------------------

// Placed is what this module placed in the home, by path relative to the agent directory, with the digest
// of what it wrote (ADR 0182: the mesh owns what it places, and only that).
type Placed map[string]string

func digest(s string) string {
	sum := sha256.Sum256([]byte(s))
	return hex.EncodeToString(sum[:])
}

// deletedByHand marks, in the record, a path the mesh placed and the person then deleted: their choice,
// kept until the item is unregistered.
const deletedByHand = "deleted-by-hand"

// PlaceHome brings the home in line with what the home scope wants (ADR 0182): it writes what is wanted and
// absent, or its own; it never writes a path the person made, nor through a directory that is a symbolic
// link; it removes what it placed and is no longer wanted, unless the person changed it since; and a file it
// placed that the person deleted stays deleted until the item is unregistered. Answers what it did and what
// it left alone, and why.
func PlaceHome(p Paths, want map[string]string) (done []string, left []string) {
	return placeHomeIn(filepath.Join(p.Home, ".claude"), p.placed(), want)
}

// placeHomeIn is PlaceHome for one agent directory and its own record of what was placed there.
func placeHomeIn(dir, record string, want map[string]string) (done []string, left []string) {
	var placed Placed
	if !readJSON(record, &placed) {
		placed = Placed{}
	}
	paths := make([]string, 0, len(want))
	for rel := range want {
		paths = append(paths, rel)
	}
	sort.Strings(paths)
	for _, rel := range paths {
		full := filepath.Join(dir, filepath.FromSlash(rel))
		content := want[rel]
		if why := linkedParent(dir, rel); why != "" {
			left = append(left, rel+": "+why+", left alone")
			continue
		}
		current, err := fsys.ReadFile(full)
		exists := err == nil
		ours, wasPlaced := placed[rel]
		switch {
		case !exists && wasPlaced && ours == deletedByHand:
			continue
		case !exists && wasPlaced:
			placed[rel] = deletedByHand
			left = append(left, rel+": deleted by hand, left deleted until the item is unregistered")
			continue
		case exists && !wasPlaced:
			left = append(left, rel+": the person's own, left alone")
			continue
		case exists && ours == deletedByHand:
			left = append(left, rel+": made again by hand after the mesh's was deleted, left alone")
			continue
		case exists && string(current) == content:
			continue
		case exists && digest(string(current)) != ours:
			left = append(left, rel+": changed by hand since it was placed, left alone")
			continue
		}
		if err := fsys.MkdirAll(filepath.Dir(full), 0o755); err != nil {
			left = append(left, rel+": "+err.Error())
			continue
		}
		mode := os.FileMode(0o644)
		if isScript(rel, content) {
			mode = 0o755
		}
		if err := fsys.WriteFile(full, []byte(content), mode); err != nil {
			left = append(left, rel+": "+err.Error())
			continue
		}
		placed[rel] = digest(content)
		done = append(done, rel+": placed")
	}
	for rel, ours := range placed {
		if _, wanted := want[rel]; wanted {
			continue
		}
		full := filepath.Join(dir, filepath.FromSlash(rel))
		if ours == deletedByHand {
			delete(placed, rel)
			continue
		}
		if why := linkedParent(dir, rel); why != "" {
			left = append(left, rel+": no longer registered, but "+why+", left alone")
			continue
		}
		current, err := fsys.ReadFile(full)
		if err == nil && digest(string(current)) != ours {
			left = append(left, rel+": no longer registered, but changed by hand, left alone")
			delete(placed, rel)
			continue
		}
		if err := fsys.Remove(full); err != nil && !os.IsNotExist(err) {
			left = append(left, rel+": no longer registered, and could not be removed: "+err.Error())
			continue
		}
		// Up to the kind's own directory, never it: `skills/<name>` goes when empty, `skills` stays.
		removeEmptyParents(filepath.Join(dir, strings.SplitN(rel, "/", 2)[0]), filepath.Dir(full))
		delete(placed, rel)
		done = append(done, rel+": removed")
	}
	raw, _ := indented(placed)
	if err := fsys.WriteFile(record, raw, 0o600); err != nil {
		left = append(left, "the record of what was placed could not be saved: "+err.Error())
	}
	return done, left
}

// linkedParent says, when a directory between the agent directory and a file is a symbolic link, which one:
// writing through it would write wherever it points.
func linkedParent(dir, rel string) string {
	parts := strings.Split(rel, "/")
	at := dir
	for _, seg := range parts[:len(parts)-1] {
		at = filepath.Join(at, seg)
		if info, err := fsys.Lstat(at); err == nil && info.Mode()&os.ModeSymlink != 0 {
			return at + " is a symbolic link"
		}
	}
	return ""
}

// removeEmptyParents removes empty directories from dir up to, not including, root.
func removeEmptyParents(root, dir string) {
	for dir != root && strings.HasPrefix(dir, root+string(filepath.Separator)) {
		if err := fsys.Remove(dir); err != nil {
			return
		}
		dir = filepath.Dir(dir)
	}
}

// HomeConflict says whether registering an item at the home scope here would collide with something the
// person made: "" when it would not.
func HomeConflict(p Paths, it Item) string {
	var placed Placed
	_ = readJSON(p.placed(), &placed)
	for rel := range HomeFiles(Config{Home: []Item{it}}) {
		if _, ours := placed[rel]; ours {
			continue
		}
		if _, err := fsys.Stat(filepath.Join(p.Home, ".claude", filepath.FromSlash(rel))); err == nil {
			return fmt.Sprintf("%s already exists in this home and the mesh did not place it; pick another name, or import it", rel)
		}
	}
	return ""
}

// ---- what the module did not place ------------------------------------------------------------------

// HomeItem is one item found in the home.
type HomeItem struct {
	Kind   string   `json:"kind"`
	Name   string   `json:"name"`
	Path   string   `json:"path"`
	Placed bool     `json:"placedByTheMesh"`
	Notes  []string `json:"notes,omitempty"`
}

var mcpToolRef = regexp.MustCompile(`mcp__([A-Za-z0-9_-]+)__[A-Za-z0-9_-]+`)

// HomeItems lists the home's skills, subagents, commands, output styles, rule files and its own memory (CLAUDE.md), says which the mesh
// placed, and notes those that share a name with a mesh item or call a tool server that is not loaded here.
func HomeItems(p Paths, c Config, loaded Servers) []HomeItem {
	dir := filepath.Join(p.Home, ".claude")
	var placed Placed
	_ = readJSON(p.placed(), &placed)
	inPlugin := map[string]bool{}
	for _, layer := range [][]Item{c.Mesh, c.Node, c.Terminal} {
		for _, it := range layer {
			inPlugin[it.Kind+"/"+it.Name] = true
		}
	}
	var out []HomeItem
	add := func(kind, name, rel, body string) {
		h := HomeItem{Kind: kind, Name: name, Path: filepath.Join(dir, filepath.FromSlash(rel))}
		_, h.Placed = placed[rel]
		if inPlugin[kind+"/"+name] {
			h.Notes = append(h.Notes, "the mesh also registers a "+kind+" of this name, offered as "+Plugin+":"+name)
		}
		seen := map[string]bool{}
		for _, m := range mcpToolRef.FindAllStringSubmatch(body, -1) {
			if server := m[1]; !seen[server] && server != meshEntry && loaded[server] == nil {
				seen[server] = true
				h.Notes = append(h.Notes, "calls tools of `"+server+"`, a tool server not loaded on this node")
			}
		}
		out = append(out, h)
	}
	if entries, err := fsys.ReadDir(filepath.Join(dir, "skills")); err == nil {
		for _, e := range entries {
			if !e.IsDir() {
				continue
			}
			body, err := fsys.ReadFile(filepath.Join(dir, "skills", e.Name(), "SKILL.md"))
			if err != nil {
				continue // the vendor's own synced folders carry none at their top
			}
			add(KindSkill, e.Name(), "skills/"+e.Name()+"/SKILL.md", string(body))
		}
	}
	for kind, sub := range map[string]string{KindAgent: "agents", KindCommand: "commands", KindOutputStyle: "output-styles", KindInstructions: "rules"} {
		entries, err := fsys.ReadDir(filepath.Join(dir, sub))
		if err != nil {
			continue
		}
		for _, e := range entries {
			if e.IsDir() || !strings.HasSuffix(e.Name(), ".md") {
				continue
			}
			body, _ := fsys.ReadFile(filepath.Join(dir, sub, e.Name()))
			add(kind, strings.TrimSuffix(e.Name(), ".md"), sub+"/"+e.Name(), string(body))
		}
	}
	if body, err := fsys.ReadFile(filepath.Join(dir, "CLAUDE.md")); err == nil {
		add(KindMemory, memoryName, "CLAUDE.md", string(body))
	}
	sort.Slice(out, func(i, j int) bool {
		if out[i].Kind != out[j].Kind {
			return out[i].Kind < out[j].Kind
		}
		return out[i].Name < out[j].Name
	})
	return out
}

// ImportFromHome reads one item of this node's home as an item to register. A rule file becomes instructions.
func ImportFromHome(p Paths, kind, name string) (Item, error) {
	dir := filepath.Join(p.Home, ".claude")
	it := Item{Kind: kind, Name: name, Files: map[string]string{}}
	switch kind {
	case KindSkill:
		root := filepath.Join(dir, "skills", name)
		err := fsys.WalkDir(root, func(full string, d os.DirEntry, err error) error {
			if err != nil || d.IsDir() {
				return err
			}
			rel, _ := filepath.Rel(root, full)
			raw, err := fsys.ReadFile(full)
			if err != nil {
				return err
			}
			it.Files[filepath.ToSlash(rel)] = string(raw)
			return nil
		})
		if err != nil {
			return Item{}, fmt.Errorf("the skill %s in this home: %w", name, err)
		}
	case KindAgent, KindCommand, KindOutputStyle, KindInstructions:
		sub := map[string]string{KindAgent: "agents", KindCommand: "commands", KindOutputStyle: "output-styles", KindInstructions: "rules"}[kind]
		raw, err := fsys.ReadFile(filepath.Join(dir, sub, name+".md"))
		if err != nil {
			return Item{}, fmt.Errorf("the %s %s in this home: %w", kind, name, err)
		}
		it.Files[name+".md"] = string(raw)
	default:
		return Item{}, fmt.Errorf("a %s is not imported from a home", kind)
	}
	return it, nil
}

// ---- registering ------------------------------------------------------------------------------------

// ConfigState is the `config` state as this module reaches it through the runtime.
type ConfigState interface {
	Put(key string, value any) error
	Delete(key string) error
	Keys() ([]string, error)
	Get(key string) (json.RawMessage, bool, error)
}

// SharedTextAtTheTerminal is why text for every node or some is not registered through this module (novox/hq issue
// 340, the operator's decision of 2026-10-09): an instruction section, an output style, a skill, a command or a
// subagent at the mesh or node scope reaches every session on those nodes as the mesh's own word, and the tool
// runner cannot tell an agent from the operator. Until a surface of the operator's own updates it, it is set at
// the controller's terminal, in this module's settings; a person's own home stays theirs to register into.
func SharedTextAtTheTerminal(kind string) string {
	key := map[string]string{KindSkill: "skills", KindAgent: "agents", KindCommand: "commands",
		KindOutputStyle: "output_styles", KindInstructions: "instructions"}[kind]
	return "a " + kind + " for every node or some reaches every session there as the mesh's own word, and this tool " +
		"cannot tell an agent from the operator. It is set at the controller's terminal only, under `" + key +
		"` in this module's settings, its text as a list of lines, on the control-node: mesh-cli settings set claude-code " +
		"'{\"" + key + "\": {\"<name>\": [\"line\", …]}}' [--node <node>] (novox/hq issue 340)." +
		proposeInstead(kind) + " The home scope, " +
		"one account's own directory, is still registered here. Nothing was registered"
}

// proposeInstead is, for an instruction section, the way an agent may still bring one to every node: proposed for
// the operator's approval (novox/hq ADR 0274).
func proposeInstead(kind string) string {
	if kind != KindInstructions {
		return ""
	}
	return " An agent may instead propose it for the operator's approval with claude_code_instructions_propose: it " +
		"becomes active only when the operator approves it on a channel that proves who answered (novox/hq ADR 0274)."
}

// Register puts an item (or, with unregister, removes it) at its scope: at the mesh scope one key, at the
// node and home scopes one key per node — this node when none is given. Taken into this node's view at once,
// so the answer says what it did here.
func Register(p Paths, it Item, nodes []string, unregister bool, state ConfigState, v *ConfigView, write WriteManaged) (map[string]any, error) {
	if !unregister && it.Scope != ScopeHome && it.Kind != KindHook && it.Kind != KindSettings && knownKind(it.Kind) {
		return nil, errors.New(SharedTextAtTheTerminal(it.Kind))
	}
	if !unregister {
		it.By, it.At = p.Node, time.Now().UTC().Format(time.RFC3339)
		if problem := it.Problem(); problem != "" {
			return map[string]any{"registered": false, "reason": problem}, nil
		}
	} else if !knownKind(it.Kind) {
		return map[string]any{"unregistered": false, "reason": fmt.Sprintf("%q is not a kind", it.Kind)}, nil
	}
	if it.Scope == ScopeMesh {
		nodes = []string{""}
	} else if len(nodes) == 0 {
		nodes = []string{p.Node}
	} else if problem := nodesProblem(nodes); problem != "" {
		return map[string]any{verbOf(unregister): false, "reason": problem}, nil
	}
	if !unregister && it.Scope == ScopeHome {
		// Every target judged before anything is put: a list is refused whole (novox/hq issue 340).
		for _, n := range nodes {
			if why := HomeScopeRefused(p, n); why != "" {
				return nil, errors.New(why)
			}
			if conflict := HomeConflict(p, it); conflict != "" {
				return map[string]any{"registered": false, "reason": conflict}, nil
			}
		}
	}
	// Compared before and after rather than read from Take: this node's own watch may take the same change
	// first, and then Take here finds nothing new although this call made it.
	before, _ := json.Marshal(v.Items())
	var keys []string
	for _, n := range nodes {
		key := it.Key(n)
		keys = append(keys, key)
		var err error
		if unregister {
			err = state.Delete(key)
		} else {
			err = state.Put(key, it)
		}
		if err != nil {
			return nil, err
		}
		op := "put"
		if unregister {
			op = "delete"
		}
		item := it
		v.Take(key, op, &item)
	}
	after, _ := json.Marshal(v.Items())
	here := string(before) != string(after)
	for _, k := range keys {
		here = here || v.Applies(k)
	}
	verb := map[bool]string{false: "registered", true: "unregistered"}[unregister]
	answer := map[string]any{verb: it.Kind + " " + it.Name, "keys": keys}
	if !unregister {
		switch {
		case it.Scope == ScopeHome && it.Kind == KindCommand:
			answer["offered as"] = "/" + it.Name
		case it.Scope == ScopeHome:
			answer["offered as"] = it.Name + ", from the home"
		case it.Kind == KindSkill || it.Kind == KindAgent || it.Kind == KindOutputStyle:
			answer["offered as"] = Plugin + ":" + it.Name
		case it.Kind == KindCommand:
			answer["offered as"] = "/" + Plugin + ":" + it.Name
		}
	}
	if here {
		// Rendered whenever it applies here, so the answer says what this node wrote, whichever of the
		// watch and this call took the change.
		rendered, err := RenderNow(p, write)
		answer["rendered here"] = rendered
		if err != nil {
			answer["not written here"] = err.Error() // kept on the bus all the same; the next render tries again
		}
		answer["sessions"] = "a new session takes it; a running one at /reload-plugins"
	} else {
		answer["here"] = "not this node: each node it is for takes it from the bus"
	}
	return answer, nil
}

func verbOf(unregister bool) string {
	return map[bool]string{false: "registered", true: "unregistered"}[unregister]
}

// nodesProblem says why a list of nodes cannot name keys, or "". "all" has been expanded before this.
func nodesProblem(nodes []string) string {
	for _, n := range nodes {
		if !nodeName.MatchString(n) {
			return fmt.Sprintf("%q is not a node's name", n)
		}
	}
	return ""
}

// ExpandNodes turns `all` into every node running the module; anything else is kept.
func ExpandNodes(nodes []string, running func() ([]string, error)) ([]string, error) {
	if len(nodes) != 1 || nodes[0] != "all" {
		return nodes, nil
	}
	all, err := running()
	if err != nil {
		return nil, fmt.Errorf("which nodes run claude-code: %w", err)
	}
	if len(all) == 0 {
		return nil, fmt.Errorf("no node is known to run claude-code")
	}
	return all, nil
}

// List is every registration of a kind ("" for every kind) on the mesh, by key, read from the state.
func List(state ConfigState, kind string) (map[string]any, error) {
	keys, err := state.Keys()
	if err != nil {
		return nil, err
	}
	sort.Strings(keys)
	out := map[string]any{}
	for _, key := range keys {
		_, _, k, _, ok := ParseKey(key)
		if !ok || (kind != "" && k != kind) {
			continue
		}
		raw, found, err := state.Get(key)
		if err != nil || !found {
			continue
		}
		var it Item
		if json.Unmarshal(raw, &it) != nil {
			continue
		}
		files := make([]string, 0, len(it.Files))
		for f := range it.Files {
			files = append(files, f)
		}
		sort.Strings(files)
		summary := map[string]any{"by": it.By, "at": it.At}
		if len(files) > 0 {
			summary["files"] = files
		}
		if it.Kind == KindHook {
			summary["event"], summary["matcher"], summary["command"] = it.Event, it.Matcher, it.Command
		}
		if it.Kind == KindSettings {
			summary["settings"] = it.Settings
		}
		out[key] = summary
	}
	return out, nil
}

// Show is one registration in full: its files' content included.
func Show(state ConfigState, key string) (any, error) {
	raw, found, err := state.Get(key)
	if err != nil {
		return nil, err
	}
	if !found {
		return nil, fmt.Errorf("nothing is registered at %s", key)
	}
	var it Item
	if err := json.Unmarshal(raw, &it); err != nil {
		return nil, err
	}
	return it, nil
}