package main

// The holder of the operator-channel seat (novox/hq to-be 45 §5, ADR 0227): what is sent, to whom,
// when, and how often. The controller decides what is wrong; this decides what is said.
//
// **History is never news** (novox/hq issue 271). The events stream keeps what it was given and hands
// all of it to a consumer that is new, recreated or was away; on 2026-10-06 a newly made consumer
// replayed three hours of raised-and-cleared conditions and each was said as if it had just happened.
// So what is said is decided by the state now and by when a thing happened, never by when it arrived:
//
//   - On start, and whenever it may have missed something (every ten minutes, and at once when an
//     old event arrives), the holder reads what is open now from the controller (`conditions`) and
//     takes it as state: nothing it says is sent for what it already said, what cleared meanwhile is
//     forgotten without a word (a Telegram message is edited, which notifies nobody), an urgent
//     condition open and never said is said — all of them in one message — and a warning raised in
//     the last ten minutes is said like any other; an older warning is state.
//   - An event older than that reading is already in it, and is not acted on. An event older than
//     FreshFor (ten minutes) by its own time is state only: it is recorded, never said.
//   - A clearing of something never said says nothing; a held message whose condition cleared before
//     it went out is dropped.
//   - Nothing is sent in the first minute after start (StartGrace) but the one message of urgent
//     conditions open in the controller's state; what arrives meanwhile waits for the minute's end.
//
// What is said, and how often:
//
//   - On `condition-raised`: one message, deduplicated by the condition's key. Said again with the
//     same key while open, it is the same message, not a second.
//   - Once more if still open after 1 hour (urgent) or 12 hours (warning), counted from when it was last
//     said; a reminder or an escalation replaces its message, never stands beside it (issue 373).
//   - On `condition-cleared`: once it stays cleared ClearSettle, its message is edited where the channel can
//     (both can). Raised again before that, nothing is said: to the operator it never ended. Cleared, said
//     so, and raised again within ten minutes, it is the same message, edited back to open.
//   - A silenced condition sends nothing.
//   - Urgent to both channels; warning to the desktop when the operator's session is there,
//     otherwise to Telegram.
//   - **Bursts are one message.** Messages for a channel are held for BurstWindow (30 s) from the
//     first and go out together: one alone is sent as itself, several as one digest ("5 new
//     warnings: …"). An urgent message is sent at once when nothing went out on its channel in the
//     last 30 s.
//   - **The desktop is gentle:** warnings reach it as at most one message every DesktopWarningEvery
//     (15 min); urgent ones are not held to that.
//   - At most twenty messages an hour per channel — a last line of defence, since the above keeps a
//     channel far below it. Reached, it is said once in a message of its own and the rest is held,
//     to go out as one digest when the hour allows.
//   - A message carrying an address, a path or a secret is refused (content.go); what is sent in its
//     place says `channel-refused`, with the offending part withheld.
//   - A channel that cannot send says so in the status and the log, and is tried again every
//     minute while what it holds is still open.

import (
	"fmt"
	"sort"
	"strings"
	"sync"
	"time"
)

// BurstWindow: what arrives for a channel within it goes out as one message. A variable, so the test bundle
// shortens it.
var BurstWindow = 30 * time.Second

// StartGrace: after start, nothing but the urgent conditions open in the controller's state. A variable, as
// kindsEvery is, so the test bundle shortens it.
var StartGrace = time.Minute

const (
	RemindUrgent  = time.Hour
	RemindWarning = 12 * time.Hour
	// QuietRemindAfter: a warning kept quiet as needing nothing is said once after this.
	QuietRemindAfter = 24 * time.Hour
	ReopenWindow     = 10 * time.Minute
	// ClearSettle: a clearing is said once the condition stayed cleared this long. One raised again sooner
	// (a unit failing again after each apply, issue 373) continues its message without a word, and its
	// clearing is never said. Once it has come back, its next clearing waits the reopen window less a minute.
	ClearSettle  = 2 * time.Minute
	CapPerHour   = 20
	KeptSends    = 200
	KeptRefusals = 50

	// FreshFor: an event older than this by its own time is history — state, never a message.
	FreshFor = 10 * time.Minute
	// DesktopWarningEvery: warnings reach the desktop at most this often.
	DesktopWarningEvery = 15 * time.Minute
	// ResyncEvery: how often the open set is read from the controller again.
	ResyncEvery = 10 * time.Minute
	// RetryEvery: a channel that failed is tried again after this.
	RetryEvery = time.Minute
	// ClockSlack: the controller's clock and this one may differ by this much; an event this close
	// to the reading is taken rather than assumed to be in it (taking one twice is harmless).
	ClockSlack = 5 * time.Second
	// DigestLines: a digest names at most this many, then says how many more.
	DigestLines = 15
)

// Message is what a channel shows: a title line and a body, and the answers it offers.
type Message struct {
	Title string
	Body  string
	// Note is the secondary words, after the body and the answers: who asked, what each answer does, the
	// expiry, the asker's Details (asks.Message.Note, issue 639).
	Note    string
	Urgent  bool
	Quiet   bool // a clearing: shown without urgency
	Actions []Choice
	// Reply is the answer this message answers, by its id: the channel shows it where that was given.
	Reply string
	// To is the account it is for, when not the one linked: a notice to an account being unlinked, or an
	// ask put to the account a relink replaces.
	To string
	// Secret: shown once, and kept by no channel (a link's code).
	Secret bool
}

// Choice is one answer a message offers: the token a channel hands back when it is chosen, and its label.
type Choice struct {
	Token string `json:"token"`
	Label string `json:"label"`
}

func (m Message) Text() string {
	t := m.Title
	for _, more := range []string{m.Body, m.Note} {
		if more != "" {
			t += "\n" + more
		}
	}
	return t
}

// Channel is one way to the operator.
type Channel interface {
	Name() string
	Ready() error
	Send(Message) (string, error)
	Edit(id string, m Message) error
	CanEdit() bool
}

// replacer is a channel that can say a message again in place of the one it showed under that id: the earlier
// one goes, the new one is shown as a new message is — it rings as its kind rings (issue 373). A reminder or
// an escalation is then one message per problem, never one more beside it.
type replacer interface {
	Replace(id string, m Message) error
}

func replaces(ch Channel) bool {
	_, ok := ch.(replacer)
	return ok
}

// silentEditor is a channel whose edits notify nobody (Telegram's are): what is over is said there
// even when it ended while the holder was away, since saying it costs the operator nothing.
type silentEditor interface{ SilentEdit() bool }

func editsSilently(ch Channel) bool {
	s, ok := ch.(silentEditor)
	return ok && s.SilentEdit()
}

// Record is one open message, kept in the module's own state so a restart forgets nothing.
type Record struct {
	Key      string `json:"key"`
	Kind     string `json:"kind"`
	Subject  string `json:"subject"`
	Severity string `json:"severity"`
	Summary  string `json:"summary"`
	// Scope, SubjectID and Machine are the condition's subject as the controller gave it, which a walk's touches
	// are matched against (ADR 0308 §2); empty for a record kept before, whose key names them.
	Scope     string `json:"scope,omitempty"`
	SubjectID string `json:"subject_id,omitempty"`
	Machine   string `json:"machine,omitempty"`
	// Headline, Explanation and Resolved are the plain words the operator reads (novox/hq ADR 0253):
	// the controller's, or a module's through notify; empty, the message is said from the summary.
	Headline    string `json:"headline,omitempty"`
	Explanation string `json:"explanation,omitempty"`
	Resolved    string `json:"resolved,omitempty"`
	// Needs is what the operator does, empty for nothing; Actions the answers offered, each by a token
	// (Tokens: token -> its grant; Index -1 is Details, one per message shown) a channel hands back when chosen.
	Needs   string   `json:"needs,omitempty"`
	Actions []Action `json:"actions,omitempty"`
	// Kept as "grants": the build before ADR 0258 kept "tokens" as token -> index, which this form cannot
	// read; under its own name it is ignored and the record loads (the old tokens die, as they must).
	Tokens map[string]Grant `json:"grants,omitempty"`
	// QuietReminded: a warning kept quiet as needing nothing was said once after QuietRemindAfter, so
	// nothing stays silent for ever.
	QuietReminded bool `json:"quiet_reminded,omitempty"`
	// Answered is what the operator chose from a notification, and what came of it.
	Answered string `json:"answered,omitempty"`
	// Ask is the open ask about this record, `<asker>.<id>`: its options are this record's answers
	// (novox/hq ADR 0259).
	Ask    string `json:"ask,omitempty"`
	Origin string `json:"origin"`
	// Publisher is the module that said it on the operator channel's one subject; empty for the controller's.
	Publisher    string    `json:"publisher,omitempty"`
	More         string    `json:"more"`
	Raised       time.Time `json:"raised"`
	SilencedTill time.Time `json:"silenced_till,omitempty"`
	// SilencedWhy is the reason the silence was given with; SilenceSaid: the message shown was edited to say
	// it is silenced (issue 373: a critical popup silenced for a week stood on the desk as if still open).
	SilencedWhy string            `json:"silenced_why,omitempty"`
	SilenceSaid bool              `json:"silence_said,omitempty"`
	Sent        map[string]string `json:"sent,omitempty"` // channel -> its message's id; "" when said in a digest
	FirstSent   time.Time         `json:"first_sent,omitempty"`
	// LastSaid is when a message about it last went out: a reminder is due its bound after it, never sooner
	// (an escalation followed by a reminder 31 s later, issue 373).
	LastSaid time.Time `json:"last_said,omitempty"`
	// ClearUnsaid: cleared, and the clearing not said yet — it is said once it stays cleared ClearSettle;
	// raised again before, the message continues as if it never cleared. ClearSilent: said only where an edit
	// notifies nobody (it ended while this holder was away).
	ClearUnsaid bool `json:"clear_unsaid,omitempty"`
	ClearSilent bool `json:"clear_silent,omitempty"`
	// ClearHeld is what was waiting to be said of it when it cleared (a reminder, an escalation): said after
	// all if it comes back before its clearing was said. Blips counts those comebacks, never said, so a
	// condition that flaps is known as one and its message's "again, Nth time" counts only what was said.
	ClearHeld string `json:"clear_held,omitempty"`
	Blips     int    `json:"blips,omitempty"`
	Reminded  bool   `json:"reminded,omitempty"`
	Pending   string `json:"pending,omitempty"` // what could not be said yet: raised, reminder, …
	// Owed is what a walk held of it and has not told yet (ADR 0308 §4, §5): kept in the state until a message
	// carrying it was sent, so a router that restarts before says it on its own (issue 538), never history.
	Owed    string    `json:"owed,omitempty"`
	Folded  bool      `json:"folded,omitempty"` // held by the cap
	Cleared time.Time `json:"cleared,omitempty"`
	Count   int       `json:"count"`
	Refused string    `json:"refused,omitempty"`
	// History: known from the state or from an old event, and never said — not news.
	History bool `json:"history,omitempty"`
	// Seen is when this holder last took word of it; the open set read after it is authoritative.
	Seen time.Time `json:"seen,omitempty"`
}

// recordOf is a condition as this holder keeps it.
func recordOf(c Condition) Record {
	return Record{Key: c.Key, Kind: c.Kind, Subject: c.SubjectWords(), Scope: c.Scope, SubjectID: c.ID, Machine: c.Machine,
		Severity: c.Severity, Summary: c.Summary,
		Headline: c.Headline, Explanation: c.Explanation, Resolved: c.Resolved, Needs: c.Needs, Actions: c.Actions,
		Origin: "condition", Publisher: c.Publisher,
		More: "conditions show " + c.Key, Raised: c.Raised, SilencedTill: c.SilencedTill, SilencedWhy: c.SilencedWhy}
}

// takeWords keeps the plain words current, as the summary is: a condition's words follow what is seen.
func (r *Record) takeWords(from Record) {
	r.Headline, r.Explanation, r.Resolved, r.Needs = from.Headline, from.Explanation, from.Resolved, from.Needs
	if !sameActions(r.Actions, from.Actions) {
		// Details performs nothing and names no action, so its tickets outlive a change of the actions:
		// every message still shown keeps its Details (issue 371). Any other ticket dies with its action.
		r.Actions = from.Actions
		for t, g := range r.Tokens {
			if g.Index != -1 {
				delete(r.Tokens, t)
			}
		}
	}
}

// takeSubject keeps the subject as the controller says it now, when it says one.
func (r *Record) takeSubject(from Record) {
	if from.Scope != "" || from.SubjectID != "" || from.Machine != "" {
		r.Scope, r.SubjectID, r.Machine = from.Scope, from.SubjectID, from.Machine
	}
}

func (r *Record) silenced(now time.Time) bool {
	return !r.SilencedTill.IsZero() && now.Before(r.SilencedTill)
}

func (r *Record) told() bool { return len(r.Sent) > 0 }

// Sent is one message that went out, or was held, for the history.
type Sent struct {
	At      time.Time `json:"at"`
	Channel string    `json:"channel"`
	Key     string    `json:"key"`
	What    string    `json:"what"`
	Outcome string    `json:"outcome"` // sent, edited, held, in digest, failed: <why>
}

// RefusalNote is one refused message: never its text.
type RefusalNote struct {
	At    time.Time `json:"at"`
	Key   string    `json:"key"`
	Class string    `json:"class"`
	What  string    `json:"what"`
}

// Store is the module's own state (ADR 0201): the open messages, and the recent sends.
type Store interface {
	Put(r Record) error
	Delete(key string) error
	All() ([]Record, error)
	PutRecent([]Sent) error
	Recent() ([]Sent, error)
}

// Holder is the seat's holder: the router (novox/hq ADR 0234 §5, ADR 0259). It keeps no channel's client:
// Away is the channel that reaches the operator away from the machines (a kind promising reaches-away),
// Desk the one at the machines; each is a kind of the `channel` bench, held by a module of its own.
type Holder struct {
	Away  Channel
	Desk  Channel
	Store Store
	// Asks keeps the asks, the operator's identities and their links (asks.go, link.go); Bench is what
	// the controller says of every channel kind and what each says of itself; Publish says on a seat.
	Asks    AskStore
	Bench   *Bench
	Publish func(subject string, body any, id string) error
	// Node is the machine this router runs on; StateDir its own directory, where root leaves a break-glass
	// request (selfact.go).
	Node     string
	StateDir string
	Now      func() time.Time
	Logf     func(string, ...any)
	// Emit states a fact as this module (refused); nil states nothing.
	Emit func(event string, body any) error
	// Ask calls a seat verb through the mesh, as this module: the answers the operator chooses.
	Ask Asker
	// RootFree asks the controller's verb root-free about machines; nil asks it through Ask (askRootFree).
	RootFree func(machines []string) (map[string]RootVerdict, error)
	// Zone is the operator's time zone, which every time in a message is said in; nil is this machine's.
	Zone func() *time.Location
	// Tracking asks the issue tracker which issues track which conditions; nil asks it through Ask (tracking.go).
	Tracking func() (map[string][]TrackedIssue, error)
	// NeedsOnly says whether a kind is set to say only what needs the operator (the setting
	// `only-what-needs-me`, ADR 0308 §4); nil, none is.
	NeedsOnly func(kind string) bool

	work sync.Mutex // one event, call or tick at a time
	mu   sync.Mutex // what the status reads

	open        map[string]*Record
	recent      []Sent
	refusals    []RefusalNote
	outbox      map[string][]item
	lastSend    map[string]time.Time
	lastWarn    map[string]time.Time
	lastTry     map[string]time.Time
	capSaid     map[string]time.Time
	tellCapSaid map[string]time.Time
	chanErr     map[string]string
	chanErrAt   map[string]time.Time
	chanOK      map[string]time.Time
	unreadable  int
	lastBad     string
	lastBadAt   time.Time
	saidOnce    map[string]time.Time
	storeErr    string
	heard       map[string]int
	lastHeard   time.Time
	started     time.Time
	syncedAt    time.Time
	syncErr     string
	wantSync    bool
	history     int
	stale       int
	// tellSeq makes every tell's key its own, even when two calls land in the same instant.
	tellSeq int
	// answered is what came of each answer event, by its id: a redelivered one is acted on once.
	answered map[string]string
	// asks are the asks this router holds, by `<asker>.<id>`, and tickets each ask's tickets to it.
	asks    map[string]*askEntry
	tickets map[string]string
	// lastUnlink is the last unlink of each kind.
	lastUnlink map[string]Unlinked
	// rootWord is the controller's last word on whether an agent can become root, by the machines asked.
	rootWord map[string]rootWord
	// passes is, by kind, the restart pass this router last made in full, kept in its state (restart.go); lost
	// the loss of answers it has yet to act on, by kind.
	passes map[string]Pass
	lost   map[string]time.Time
	// walks are the walks open now, by id, each with what it holds (walks.go, ADR 0308).
	walks map[string]*Walk
	// ended are the walks whose end was heard, by id: what a start heard after its end is matched against.
	ended map[string]*Walk
	// track is the issue tracker's last word on which issues track which conditions (tracking.go).
	track trackWord
}

func (h *Holder) init() {
	if h.open == nil {
		h.open = map[string]*Record{}
		h.outbox = map[string][]item{}
		h.lastSend = map[string]time.Time{}
		h.lastWarn = map[string]time.Time{}
		h.lastTry = map[string]time.Time{}
		h.capSaid = map[string]time.Time{}
		h.tellCapSaid = map[string]time.Time{}
		h.chanErr = map[string]string{}
		h.chanErrAt = map[string]time.Time{}
		h.chanOK = map[string]time.Time{}
		h.saidOnce = map[string]time.Time{}
		h.heard = map[string]int{}
		h.passes = map[string]Pass{}
		h.lost = map[string]time.Time{}
		h.walks = map[string]*Walk{}
		h.ended = map[string]*Walk{}
	}
	if h.Now == nil {
		h.Now = time.Now
	}
	if h.Logf == nil {
		h.Logf = func(string, ...any) {}
	}
}

// Load reads back what was open and what was sent before a restart. What was waiting to be said is
// not said now: it is history, and the controller's state, read next, decides what is still news.
func (h *Holder) Load() error {
	h.work.Lock()
	defer h.work.Unlock()
	h.mu.Lock()
	defer h.mu.Unlock()
	h.init()
	if h.Store == nil {
		return nil
	}
	recs, err := h.Store.All()
	if err != nil {
		h.storeErr = err.Error()
		return err
	}
	for i := range recs {
		r := recs[i]
		if r.Pending != "" || r.Folded {
			r.Pending, r.Folded = "", false
			if !r.told() {
				r.History = true
			}
		}
		if r.Owed != "" && r.Cleared.IsZero() {
			// Held from the operator on purpose and not told yet: said on its own, as the next tick tries what is
			// unsent (issue 538). What the operator could have heard is history; this they could not.
			r.Pending, r.History = r.Owed, false
		}
		h.open[r.Key] = &r
	}
	if sent, err := h.Store.Recent(); err == nil {
		h.recent = sent
	}
	if err := h.loadWalks(); err != nil {
		h.storeErr = err.Error()
		return err
	}
	h.mu.Unlock()
	err = h.loadAsks()
	h.mu.Lock()
	return err
}

// Start marks the holder's start: the grace minute counts from here.
func (h *Holder) Start() {
	h.work.Lock()
	defer h.work.Unlock()
	h.mu.Lock()
	defer h.mu.Unlock()
	h.init()
	h.started = h.Now()
}

func (h *Holder) inGrace(now time.Time) bool {
	return !h.started.IsZero() && now.Sub(h.started) < StartGrace
}

// Condition takes one of the controller's condition events. Whether it is news is decided by its own
// time, never by its arrival.
func (h *Holder) Condition(event string, c Condition) {
	h.warmTracking() // outside the work: what is said inside it reads a recent word
	h.work.Lock()
	defer h.work.Unlock()
	h.mu.Lock()
	h.init()
	now := h.Now()
	h.heard[event]++
	h.lastHeard = now
	synced := h.syncedAt
	h.mu.Unlock()
	rec := recordOf(c)
	when := c.When(event)
	quiet := false
	switch {
	case !when.IsZero() && !synced.IsZero() && when.Before(synced.Add(-ClockSlack)):
		// Already in the state read from the controller after it: nothing to take.
		h.mu.Lock()
		h.history++
		h.mu.Unlock()
		return
	case !when.IsZero() && now.Sub(when) > FreshFor:
		// Old: a replay, a redelivery, or the holder was away. State, never a message — and the
		// controller's state is read again, since what came between may be missing too.
		quiet = true
		h.mu.Lock()
		h.stale++
		first := !h.wantSync
		h.wantSync = true
		h.mu.Unlock()
		if first {
			h.Logf("[messenger] %s %s happened %s ago: taken as state, not news; reading the open conditions again",
				event, c.Key, roughly(now.Sub(when)))
		}
	}
	switch event {
	case EventRaised:
		h.raised(rec, quiet)
	case EventChanged:
		h.changed(rec, quiet)
	case EventCleared:
		h.cleared(rec.Key, quiet)
	}
}

// Unreadable records an event that could not be read, and tells the operator — once an hour.
func (h *Holder) Unreadable(key string, err error) {
	h.work.Lock()
	defer h.work.Unlock()
	h.mu.Lock()
	h.init()
	h.unreadable++
	h.lastBad = err.Error()
	h.lastBadAt = h.Now()
	n := h.unreadable
	h.mu.Unlock()
	h.Logf("[messenger] refused %s: %v (unreadable events since start: %d)", key, err, n)
	h.sayOnce("messenger.unreadable-event", time.Hour, Message{
		Title: "A mesh message could not be read",
		Body: fmt.Sprintf("The messenger could not read %d update(s) from the controller, so a problem may be open "+
			"that was not said. An agent can find out why in the messenger's status.", n),
	})
}

func (h *Holder) raised(rec Record, quiet bool) {
	now := h.Now()
	h.mu.Lock()
	old := h.open[rec.Key]
	h.mu.Unlock()
	if old != nil && old.Cleared.IsZero() {
		// Said again while open: the same message. Its words are kept current; nothing is sent — unless
		// it was kept quiet as needing nothing and now needs the operator.
		h.mu.Lock()
		wasQuiet := needsNothing(old)
		wasSilenced := old.silenced(now)
		old.Summary, old.Subject, old.Kind = rec.Summary, rec.Subject, rec.Kind
		old.takeSubject(rec)
		old.SilencedTill, old.SilencedWhy = rec.SilencedTill, rec.SilencedWhy
		old.takeWords(rec)
		if rec.Severity != "" {
			old.Severity = rec.Severity
		}
		old.Seen = now
		h.mu.Unlock()
		h.silenceWords(old, wasSilenced)
		h.nowNeeded(old, wasQuiet, quiet)
		h.persist(old)
		return
	}
	if old != nil && now.Sub(old.Cleared) < ReopenWindow {
		// Cleared and raised again within ten minutes: the same message, back to open (to-be 45 §2).
		h.mu.Lock()
		blip := old.ClearUnsaid
		held := old.ClearHeld
		escalated := old.Severity == Warning && rec.Severity == Urgent
		gone := now.Sub(old.Cleared)
		old.Cleared = time.Time{}
		old.ClearUnsaid, old.ClearSilent, old.ClearHeld = false, false, ""
		if blip {
			old.Blips++
		} else {
			old.Count++
		}
		old.Summary, old.Severity, old.SilencedTill, old.SilencedWhy = rec.Summary, rec.Severity, rec.SilencedTill, rec.SilencedWhy
		old.takeWords(rec)
		old.Seen = now
		h.mu.Unlock()
		switch {
		case quiet || old.silenced(now):
		case blip && escalated:
			// Back before its clearing was said, and urgent now: said as an escalation, which rings.
			h.deliver(old, "escalated")
		case blip && held != "":
			// Back before its clearing was said: what was waiting to be said of it when it cleared is said now.
			h.deliver(old, held)
		case blip:
			// Its clearing was never said (issue 373): to the operator it never ended, so nothing is said now.
			h.Logf("[messenger] %s back %s after it cleared, which was not said yet: the same message continues, nothing said",
				old.Key, roughly(gone))
			h.record(Sent{At: now, Channel: "-", Key: old.Key, What: "reopened", Outcome: "quiet: back before its clearing was said"})
		case old.told() && old.Severity == Urgent:
			// Its end was said, and it is back: urgent, it rings again, in place of its message.
			h.deliver(old, "reopened")
		case old.told():
			h.edit(old, "reopened", false)
		case !needsNothing(old) && !h.queued(old.Key):
			// Cleared before it was ever said, and back: a problem the operator has not heard of is said.
			h.deliver(old, "raised")
		}
		h.persist(old)
		return
	}
	r := rec
	r.Count = 1
	if r.Raised.IsZero() {
		r.Raised = now
	}
	r.Sent = map[string]string{}
	r.Seen = now
	r.History = quiet
	h.mu.Lock()
	h.open[r.Key] = &r
	h.mu.Unlock()
	switch {
	case quiet:
	case r.silenced(now):
		h.Logf("[messenger] %s raised while silenced until %s: nothing sent", r.Key, r.SilencedTill.Format(time.RFC3339))
	default:
		h.deliver(&r, "raised")
	}
	h.persist(&r)
}

// nowNeeded says a record kept quiet as needing nothing, once its words say it needs the operator.
func (h *Holder) nowNeeded(r *Record, wasQuiet, quiet bool) {
	if wasQuiet && !needsNothing(r) && !r.told() && !quiet && !r.silenced(h.Now()) && !h.queued(r.Key) {
		h.deliver(r, "raised")
	}
}

func (h *Holder) changed(rec Record, quiet bool) {
	h.mu.Lock()
	old := h.open[rec.Key]
	h.mu.Unlock()
	if old == nil || !old.Cleared.IsZero() {
		// A change to something this holder never heard raised: read as a raise, so it is said
		// (when it is news).
		h.Logf("[messenger] %s changed and was not open here; taken as raised", rec.Key)
		h.raised(rec, quiet)
		return
	}
	h.mu.Lock()
	escalated := old.Severity == Warning && rec.Severity == Urgent
	wasQuiet := needsNothing(old)
	wasSilenced := old.silenced(h.Now())
	old.Summary, old.Subject = rec.Summary, rec.Subject
	old.takeSubject(rec)
	old.SilencedTill, old.SilencedWhy = rec.SilencedTill, rec.SilencedWhy
	old.takeWords(rec)
	if rec.Severity != "" {
		old.Severity = rec.Severity
	}
	old.Seen = h.Now()
	h.mu.Unlock()
	h.silenceWords(old, wasSilenced)
	switch {
	case escalated && !quiet && !old.silenced(h.Now()):
		// Routing differs for urgent: said once more, to both channels.
		h.deliver(old, "escalated")
	default:
		h.nowNeeded(old, wasQuiet, quiet)
	}
	h.persist(old)
}

// silenceWords keeps a shown message true to a silence (issue 373). Silenced, the message is edited in place
// to say so — until when, and why — with no answers and no urgency, so the desk's popup times out instead of
// standing as if still open. When the silence ends and the condition is still open, the message is edited back
// to its open words, and the usual rules apply again.
func (h *Holder) silenceWords(r *Record, wasSilenced bool) {
	now := h.Now()
	h.mu.Lock()
	silenced, told, said := r.silenced(now), r.told(), r.SilenceSaid
	key, till, why := r.Key, r.SilencedTill, r.SilencedWhy
	h.mu.Unlock()
	switch {
	case silenced && !wasSilenced && told && !said:
		h.mu.Lock()
		r.SilenceSaid = true
		h.mu.Unlock()
		h.Logf("[messenger] %s silenced until %s (%s): its message says so, and nothing more is said of it",
			key, till.Format(time.RFC3339), why)
		h.edit(r, "silenced", false)
	case !silenced && said:
		h.mu.Lock()
		r.SilenceSaid = false
		h.mu.Unlock()
		h.Logf("[messenger] %s is no longer silenced and still open: its message says it is open again", key)
		h.edit(r, "raised", false)
	}
}

// cleared ends a record. Something never said is ended without a word; what was waiting to be said
// about it is dropped. quiet: it ended while this holder was not listening, so it is said only where
// an edit notifies nobody.
func (h *Holder) cleared(key string, quiet bool) {
	now := h.Now()
	h.mu.Lock()
	old := h.open[key]
	h.mu.Unlock()
	if old == nil || !old.Cleared.IsZero() {
		h.Logf("[messenger] %s cleared and was not open here: nothing to say", key)
		return
	}
	held := h.queuedWhat(key)
	h.mu.Lock()
	if held == "" {
		held = old.Pending
	}
	old.Cleared = now
	old.Pending = ""
	old.Owed = "" // what a walk held of it is owed no more: it ended (the review of PR 238)
	old.Folded = false
	old.Seen = now
	told := old.told()
	h.mu.Unlock()
	dropped := h.unqueue(key)
	switch {
	case old.silenced(now) && !old.SilenceSaid:
		// A silenced condition sends nothing, its clearing included.
	case old.silenced(now):
		// Its message says it is silenced: said resolved where an edit notifies nobody, so it does not stand.
		h.mu.Lock()
		old.ClearUnsaid, old.ClearSilent, old.ClearHeld = true, true, ""
		h.mu.Unlock()
	case !told:
		if dropped > 0 {
			h.Logf("[messenger] %s cleared before it was said: nothing to unsay", key)
		}
	default:
		// Said once it stays cleared (ClearSettle; a condition that came back, ReopenWindow): a blip of a few
		// seconds is not said at all (issue 373).
		h.mu.Lock()
		old.ClearUnsaid, old.ClearSilent, old.ClearHeld = true, quiet, held
		h.mu.Unlock()
	}
	h.persist(old)
}

// clearSettle is how long a record stays cleared before its clearing is said: one that came back before
// waits the whole reopen window, so a condition that flaps is said cleared once, when it stopped flapping.
func clearSettle(r *Record) time.Duration {
	if r.Count > 1 || r.Blips > 0 {
		return ReopenWindow - time.Minute
	}
	return ClearSettle
}

// lastSaid is when a message about a record last went out.
func lastSaid(r *Record) time.Time {
	if !r.LastSaid.IsZero() {
		return r.LastSaid
	}
	return r.FirstSent
}

// Tick does what time asks: reminders, retries, what is held, and forgetting what cleared long
// enough ago that a new raise is a new message.
func (h *Holder) Tick() {
	h.warmRootFree(false) // outside the work: what is offered inside it reads a recent word
	h.warmTracking()
	h.work.Lock()
	defer h.work.Unlock()
	h.mu.Lock()
	h.init()
	now := h.Now()
	var recs []*Record
	for _, r := range h.open {
		recs = append(recs, r)
	}
	h.mu.Unlock()
	sort.Slice(recs, func(i, j int) bool { return recs[i].Raised.Before(recs[j].Raised) })
	h.sweepAsks(now)
	h.releaseHeld()
	h.breakGlass()
	h.boundWalks(now)
	h.duePasses(now)
	for _, r := range recs {
		switch {
		case !r.Cleared.IsZero():
			if r.ClearUnsaid && now.Sub(r.Cleared) >= clearSettle(r) {
				h.mu.Lock()
				r.ClearUnsaid = false
				silent := r.ClearSilent
				h.mu.Unlock()
				if !r.silenced(now) || r.SilenceSaid {
					h.edit(r, "cleared", silent || r.silenced(now))
				}
				h.persist(r)
			}
			if !r.ClearUnsaid && now.Sub(r.Cleared) >= ReopenWindow && !h.queued(r.Key) {
				h.mu.Lock()
				delete(h.open, r.Key)
				h.mu.Unlock()
				if h.Store != nil {
					if err := h.Store.Delete(r.Key); err != nil {
						h.noteStore(err)
					}
				}
			}
		case r.silenced(now):
		case r.SilenceSaid:
			// Its silence ran out while it is still open: the message is open again.
			h.silenceWords(r, true)
			h.persist(r)
		case r.Pending != "" && !h.queued(r.Key):
			// No channel could take it when it was said: tried again.
			h.deliver(r, r.Pending)
			h.persist(r)
		case needsNothing(r) && !r.told() && !r.QuietReminded && now.Sub(r.Raised) >= QuietRemindAfter:
			// Quiet for a day: said once, so nothing stays silent for ever (ADR 0258).
			h.mu.Lock()
			r.QuietReminded = true
			h.mu.Unlock()
			h.deliver(r, "quiet-reminder")
			h.persist(r)
		case !r.Reminded && !r.FirstSent.IsZero() && now.Sub(r.Raised) >= remindAfter(r.Severity) &&
			now.Sub(lastSaid(r)) >= remindAfter(r.Severity):
			// Once more after its bound — counted from its raising, and never sooner after it was
			// last said (an old condition said at a reading of the state is not reminded at once, nor one
			// just escalated: issue 373).
			h.mu.Lock()
			r.Reminded = true
			h.mu.Unlock()
			h.deliver(r, "reminder")
			h.persist(r)
		}
	}
	h.flush(now, false)
}

// Flush sends what is due on each channel; the runtime calls it every few seconds, so a held
// message waits its window and not a minute more.
func (h *Holder) Flush() {
	h.warmRootFree(false) // outside the work: what is offered inside it reads a recent word
	h.warmTracking()
	h.work.Lock()
	defer h.work.Unlock()
	h.mu.Lock()
	h.init()
	now := h.Now()
	h.mu.Unlock()
	h.duePasses(now)
	h.flush(now, false)
}

func remindAfter(severity string) time.Duration {
	if severity == Urgent {
		return RemindUrgent
	}
	return RemindWarning
}

// say composes a record's message under the content rule: refused, it is composed again with less of
// it, until what remains may leave. The refusal is recorded and stated once per record.
func (h *Holder) say(r *Record, what string) Message { return h.sayOn(r, what, "") }

// sayOn is a record's message on one channel kind: its words, what came of an answer, the answers that kind
// can carry, and where the others can be given. An empty kind is the words alone.
func (h *Holder) sayOn(r *Record, what, kind string) Message {
	m := h.words(r, what)
	if what == "cleared" || what == "silenced" || m.Title == "A mesh message was withheld" {
		return m
	}
	// On a kind that proves who answers, an ask's explanation is shown with its values whole (issue 383): the
	// path or the address the operator approves is readable there; a secret's shape still is not.
	whole := h.wholeOf(r, kind)
	if whole != "" {
		if wm, ok := h.wholeWords(r, what, whole); ok {
			m = wm
		} else {
			whole = ""
		}
	}
	if r.Answered != "" {
		m = h.answeredWords(r, m, kind)
	}
	if kind == "" {
		return m
	}
	withheld := map[string]bool{} // the labels of answers whose effect could not be said
	if rec := h.openAsk(r); rec != nil {
		// The note (issue 639): who asks, as the bus proves it (the asker is the subject's, never the body's), what
		// each answer does, what happens if nobody answers (the review of 2026-10-09), where else it is answered,
		// and the asker's Details. The body stays the asker's summary and points, read at a glance.
		var note []string
		for _, line := range h.askLines(rec, r) {
			if _, ok := Check(line); ok {
				note = append(note, line)
			}
		}
		// **An answer whose effect is not said is not offered** (the confirmation review of 2026-10-09): its line
		// refused by the content rule, its button went out all the same, and a tap would authorise what the
		// person was not shown.
		for _, o := range rec.Ask.Options {
			if _, ok := Check(o.Label + ": " + o.Does + "."); !ok || strings.TrimSpace(o.Does) == "" {
				withheld[o.Label] = true
			}
		}
		if line := h.elsewhere(rec, kind); line != "" {
			if _, ok := Check(line); ok {
				note = append(note, line)
			}
		}
		// On a kind that proves who answers, the Details whole (issue 383): every value an approval sets, held to
		// the secret rule alone, as the whole words are.
		details, passes := rec.Ask.Details, Check
		if wd := h.wholeDetailsOf(r, kind); wd != "" {
			details, passes = wd, CheckSecret
		}
		for _, line := range strings.Split(strings.TrimSpace(details), "\n") {
			if line = strings.TrimSpace(line); line == "" {
				continue
			}
			if refusal, ok := passes(line); !ok {
				line = withheldLine(line, refusal, passes)
			}
			note = append(note, line)
		}
		m.Note = strings.Join(note, "\n")
	}
	for _, c := range h.choices(r, kind) {
		if !withheld[c.Label] {
			m.Actions = append(m.Actions, c)
		}
	}
	return m
}

// answeredWords is a message that says what came of its question. An ask's own message keeps the question
// whole — its headline as the title, the asker's summary, points and link as the body, its Details after them —
// so the operator can read back what they answered (issue 714, which undid issue 639's one line). How it ended
// ("You chose Approve at 13:30 on Telegram.") and what the router knows of the asker after it are the note,
// below the question, and its answers are gone (issue 372). A channel that must shorten it cuts the body from
// its end, the Details first; never the headline or the note. A condition's message keeps its own title, and
// says how it ended first.
func (h *Holder) answeredWords(r *Record, m Message, kind string) Message {
	if r.Origin == "ask" {
		headline, _ := wordsOf(r)
		body := []string{}
		if b := strings.TrimSpace(m.Body); b != "" {
			body = append(body, b)
		}
		body = append(body, h.answeredDetails(r, kind)...)
		out := Message{Title: headline, Body: strings.Join(body, "\n"), Note: strings.TrimSpace(r.Answered),
			Urgent: m.Urgent, Quiet: m.Quiet}
		if _, ok := Check(out.Title + "\n" + out.Note); ok {
			return out
		}
		// Its headline refused (it is the asker's): the outcome is still said, before what may leave.
	}
	m.Body = strings.TrimSpace(r.Answered + "\n" + m.Body)
	return m
}

// answeredDetails are an answered ask's Details, line by line, as its open message noted them (issue 714): whole
// on a kind that proves who answers, a line that may not leave withheld and said so.
func (h *Holder) answeredDetails(r *Record, kind string) []string {
	if r.Ask == "" {
		return nil
	}
	e := h.askOf(r.Ask)
	if e == nil {
		return nil
	}
	details, passes := e.rec.Ask.Details, Check
	if wd := h.wholeDetailsOf(r, kind); wd != "" {
		details, passes = wd, CheckSecret
	}
	var lines []string
	for _, line := range strings.Split(strings.TrimSpace(details), "\n") {
		if line = strings.TrimSpace(line); line == "" {
			continue
		}
		if refusal, ok := passes(line); !ok {
			line = withheldLine(line, refusal, passes)
		}
		lines = append(lines, line)
	}
	return lines
}

// wholeWords is a record's message with the ask's whole words in place of its explanation, when they carry no
// secret's shape once composed; else false, and the message under the whole content rule stands.
func (h *Holder) wholeWords(r *Record, what, whole string) (Message, bool) {
	c := *r
	c.Explanation = whole
	m := compose(&c, what, h.Now(), h.zone(), 0)
	if refusal, ok := CheckSecret(m.Text()); !ok {
		h.Logf("[messenger] the whole words of %s carry %s; shown as on a channel that proves nothing", r.Key, refusal)
		return Message{}, false
	}
	return m, true
}

// askLines are what an ask's message notes of the ask itself, in two lines: who asks and when, with what happens
// if nobody answers; then each option's effect.
func (h *Holder) askLines(rec *AskRecord, r *Record) []string {
	asker := rec.Asker
	if asker == SelfAsker {
		asker = "the router itself"
	}
	first := "Asked by " + asker + " at " + when(r.Raised, h.Now(), h.zone()) + "."
	if !rec.Ask.Expires.IsZero() && rec.Ask.OnExpiry != "" {
		first += " Unanswered by " + by(rec.Ask.Expires, h.Now(), h.zone()) + ": " + strings.TrimSuffix(rec.Ask.OnExpiry, ".") + "."
	}
	lines := []string{first}
	var does []string
	for _, o := range rec.Ask.Options {
		if o.Does != "" {
			does = append(does, o.Label+": "+strings.TrimSuffix(o.Does, ".")+".")
		}
	}
	if len(does) > 0 {
		lines = append(lines, strings.Join(does, " "))
	}
	return lines
}

// words is a record's message under the content rule: refused, it is composed again with less of it,
// until what remains may leave. The refusal is recorded and stated once per record.
func (h *Holder) words(r *Record, what string) Message {
	now := h.Now()
	said, _, refusal, ok := h.allowedWords(r, what, now)
	if ok || r.Refused != "" {
		return said
	}
	h.mu.Lock()
	r.Refused = refusal.What
	h.mu.Unlock()
	key := r.Key
	if _, keyOK := Check(key); !keyOK {
		key = "(withheld)"
	}
	h.mu.Lock()
	h.refusals = append(h.refusals, RefusalNote{At: now, Key: key, Class: refusal.Class, What: refusal.What})
	if len(h.refusals) > KeptRefusals {
		h.refusals = h.refusals[len(h.refusals)-KeptRefusals:]
	}
	h.mu.Unlock()
	h.Logf("[messenger] refused the message for %s: it carried %s; sending channel-refused with its words withheld", key, refusal)
	if h.Emit != nil {
		if err := h.Emit("refused", map[string]any{"key": key, "class": refusal.Class, "what": refusal.What}); err != nil {
			h.Logf("[messenger] could not state the refusal on the bus: %v", err)
		}
	}
	return said
}

// composeTracked is compose with the line on the issues that track the condition (tracking.go), so the content
// rule judges the message as it is sent.
func (h *Holder) composeTracked(r *Record, what string, now time.Time, withhold int) (Message, string) {
	m := compose(r, what, now, h.zone(), withhold)
	if !h.tracksAsked() || withhold >= 2 {
		return m, ""
	}
	issues, known := h.trackedBy(r.Key)
	return withTracking(m, r, what, issues, known, now, h.zone())
}

// allowedWords is the message the content rule leaves of a record: its own words when they may leave the
// mesh, else the same message composed again with less of it until what remains may, else the withheld
// one. It answers the tracking line it carries, what its own words carried, and whether those words are
// what it says. **It changes nothing**: `words` is this walk with the refusal recorded and stated once,
// and `Preview` (preview.go) is this walk alone, so a read of a wording cannot alter what a send says.
func (h *Holder) allowedWords(r *Record, what string, now time.Time) (Message, string, Refusal, bool) {
	if r.Refused != "" {
		// Refused before: its words stay withheld in every later message too.
		for w := 1; w <= 3; w++ {
			if m, line := h.composeTracked(r, what, now, w); allowed(m) {
				return m, line, Refusal{What: r.Refused}, false
			}
		}
	}
	m, line := h.composeTracked(r, what, now, 0)
	refusal, ok := Check(m.Text())
	if ok {
		return m, line, Refusal{}, true
	}
	// Composed from a copy carrying the reason, because a withheld message says what it carried.
	reduced := *r
	reduced.Refused = refusal.What
	for w := 1; w <= 3; w++ {
		if m, line := h.composeTracked(&reduced, what, now, w); allowed(m) {
			return m, line, refusal, false
		}
	}
	return withheld(refusal.What, r.Severity == Urgent), "", refusal, false
}

// allowed says whether a message's words may leave the mesh.
func allowed(m Message) bool {
	_, ok := Check(m.Text())
	return ok
}

// deliver sends a record's message where its severity routes it.

func (h *Holder) channels() []Channel {
	var out []Channel
	for _, c := range []Channel{h.Away, h.Desk} {
		if c != nil {
			out = append(out, c)
		}
	}
	return out
}

func (h *Holder) record(s Sent) {
	h.mu.Lock()
	h.recent = append(h.recent, s)
	if len(h.recent) > KeptSends {
		h.recent = h.recent[len(h.recent)-KeptSends:]
	}
	recent := append([]Sent(nil), h.recent...)
	h.mu.Unlock()
	if h.Store != nil {
		if err := h.Store.PutRecent(recent); err != nil {
			h.noteStore(err)
		}
	}
}

func (h *Holder) persist(r *Record) {
	if h.Store == nil {
		return
	}
	h.mu.Lock()
	c := *r
	h.mu.Unlock()
	if err := h.Store.Put(c); err != nil {
		h.noteStore(err)
	}
}

func (h *Holder) noteStore(err error) {
	h.mu.Lock()
	first := h.storeErr == ""
	h.storeErr = err.Error()
	h.mu.Unlock()
	if first {
		h.Logf("[messenger] cannot write its state (open messages are held in memory only until it can): %v", err)
	}
}

func (h *Holder) noteChannel(name string, err error) {
	h.mu.Lock()
	defer h.mu.Unlock()
	now := h.Now()
	if err == nil {
		if h.chanErr[name] != "" {
			h.Logf("[messenger] %s sends again", name)
		}
		h.chanErr[name] = ""
		h.chanOK[name] = now
		return
	}
	// Said in the log when it changes, and at most every ten minutes while it holds.
	if h.chanErr[name] != err.Error() || now.Sub(h.chanErrAt[name]) >= 10*time.Minute {
		h.Logf("[messenger] %s cannot send: %v", name, err)
		h.chanErrAt[name] = now
	}
	h.chanErr[name] = err.Error()
}

func (h *Holder) whyNot() string {
	var parts []string
	for _, ch := range h.channels() {
		if err := ch.Ready(); err != nil {
			parts = append(parts, ch.Name()+": "+err.Error())
			continue
		}
		h.mu.Lock()
		e := h.chanErr[ch.Name()]
		h.mu.Unlock()
		if e != "" {
			parts = append(parts, ch.Name()+": "+e)
		}
	}
	if len(parts) == 0 {
		return "no channel"
	}
	return strings.Join(parts, "; ")
}

func roughly(d time.Duration) string {
	switch {
	case d < 0:
		return "a moment"
	case d < 2*time.Minute:
		return fmt.Sprintf("%d s", int(d.Seconds()))
	case d < 2*time.Hour:
		return fmt.Sprintf("%d min", int(d.Minutes()))
	case d < 48*time.Hour:
		return fmt.Sprintf("%.1f h", d.Hours())
	}
	return fmt.Sprintf("%d days", int(d.Hours()/24))
}

// withheldLine is a note line the rule refused, said withheld: a change's line ("+ key: value") keeps its key's name,
// so the operator knows which setting holds a value they are not shown (the review of mesh-controller #304); any
// other line, or one whose key the rule refuses too, is said withheld whole.
func withheldLine(line string, refusal Refusal, passes func(string) (Refusal, bool)) string {
	if len(line) > 2 && strings.ContainsRune("+~-=", rune(line[0])) && line[1] == ' ' {
		key := line[2:]
		if i := strings.IndexAny(key, ": "); i > 0 {
			key = key[:i]
		}
		named := line[:2] + key + " (a value carrying " + refusal.What + " is withheld here)"
		if _, ok := passes(named); ok {
			return named
		}
	}
	return "(a line carrying " + refusal.What + " is withheld here)"
}