docs(readme): clarify /loop runs a prompt or custom command, not built-ins

- stopLoop re-arms the poll ticker after removing one loop, so stopping one of
  several no longer strands the rest with no tick scheduled (jatmn).
- a bare self-paced /command is rejected with a pointer to the interval form:
  self-paced drives a free-form goal via the playbook + LOOP: control line, which
  a custom command's expanded template never carries, so it would silently
  degrade to adaptive polling (jatmn).
- /resume only tears loops down on an actual session-id change; /resume latest or
  /resume <currentID> can resolve to the already-active session, whose loops are
  its own, not a "previous" session's (CodeRabbit).
- tests: skipped-behind-modal loop stays scheduled, footer carries the next-wake
  time, the confirmed /clear actually wipes the transcript, plus multi-loop stop
  keeping the ticker alive and self-paced-/command rejection.

README.md

@@ -186,6 +186,7 @@ Common slash commands:
 | `/spec`, `/plan` | draft and review a plan before building |
 | `/image` | attach an image for vision-capable models |
 | `/resume`, `/rewind` | continue or roll back local sessions |
+| `/loop` | repeat a prompt or custom `/command` on an interval (`/loop 5m /babysit-prs`) or self-paced |
 | `/compact`, `/context` | manage context usage |
 | `/permissions`, `/tools` | inspect available tools and policy |
 | `/add-dir` | allow an extra write directory for this session |

internal/tui/commands.go

@@ -47,6 +47,7 @@ const (
 	commandExport
 	commandNew
 	commandSkills
+	commandLoop
 	commandUnknown
 )
 
@@ -297,6 +298,13 @@ var commandDefinitions = []commandDefinition{
 		description: "Write the conversation transcript to a file.",
 		kind:        commandExport,
 	},
+	{
+		name:        "/loop",
+		usage:       "/loop [interval] <prompt|/command> | /loop list | /loop stop [id|all]",
+		group:       commandGroupSession,
+		description: "Repeat a prompt or command on an interval (e.g. /loop 5m /babysit-prs), or self-paced when no interval is given.",
+		kind:        commandLoop,
+	},
 	{
 		name:        "/help",
 		usage:       "/help",

internal/tui/loop.go

@@ -0,0 +1,693 @@
+package tui
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+
+	tea "charm.land/bubbletea/v2"
+)
+
+// The /loop command repeats a prompt or slash command in one of two modes:
+//
+//   - Fixed interval — `/loop 5m <prompt>` re-fires on a wall-clock cadence.
+//   - Self-paced     — bare `/loop <prompt>` runs a maintenance playbook: the model
+//     does one increment of work each iteration and ends its reply with a control
+//     line (`LOOP: DONE` / `LOOP: CONTINUE [interval]`) that stops the loop or picks
+//     the next wake. With no control line it falls back to an adaptive cadence.
+//
+// Loops are foreground and session-scoped: a tick only fires while the session is
+// idle between turns (it never interrupts a streaming turn), the loop lives with the
+// session that created it, and switching sessions (/new, /resume) stops it. Safety
+// rails cap iterations, age, consecutive failures, and no-progress repetition.
+// Everything here is pure/loop-local; the turn-lifecycle wiring (ticker, launch,
+// continuation) lives in model.go.
+
+type loopMode int
+
+const (
+	loopModeFixed     loopMode = iota // re-fire every fixed interval
+	loopModeSelfPaced                 // model chooses the next wake each iteration
+)
+
+// Safety bounds. A loop is foreground + session-scoped, but these keep a runaway
+// or forgotten loop from burning tokens forever.
+const (
+	loopMinInterval   = 30 * time.Second
+	loopMaxInterval   = 24 * time.Hour
+	loopMaxIterations = 500 // hard ceiling; the loop auto-stops after this many
+
+	// loopMaxAge auto-expires a loop this long after it was created, so a forgotten
+	// loop stops on its own even if it never reaches the iteration cap.
+	loopMaxAge = 24 * time.Hour
+
+	loopSelfPaceMin     = 1 * time.Minute
+	loopSelfPaceMax     = 1 * time.Hour
+	loopSelfPaceDefault = 15 * time.Minute
+
+	// loopDoomThreshold ends a loop after this many consecutive identical final
+	// answers — a self-paced or interval loop that gets stuck repeating the same
+	// no-progress result should stop rather than churn.
+	loopDoomThreshold = 5
+
+	// loopMaxFailures ends a loop after this many consecutive failed iterations, so
+	// a loop whose iterations keep erroring stops instead of churning to the
+	// iteration cap (a failed turn has no final answer, so the doom guard can't see
+	// the lack of progress).
+	loopMaxFailures = 3
+
+	// loopPollInterval is how often the controller checks whether a loop is due.
+	// A loop only fires while idle, so this is a cheap between-turn poll.
+	loopPollInterval = 1 * time.Second
+)
+
+// loopState is one active loop owned by the current session.
+type loopState struct {
+	id        string
+	mode      loopMode
+	prompt    string // the prompt or "/command" re-run each iteration
+	interval  time.Duration
+	iteration int
+	maxIter   int // 0 => loopMaxIterations
+	createdAt time.Time
+	nextRunAt time.Time
+	// lastResult / repeatRun drive doom-loop detection: consecutive identical
+	// final answers past loopDoomThreshold end the loop.
+	lastResult string
+	repeatRun  int
+	// failRun counts consecutive failed iterations; past loopMaxFailures the loop
+	// stops (a failed turn has no final answer for the doom guard to compare).
+	failRun int
+	paused  bool
+}
+
+func (l *loopState) iterationCap() int {
+	if l.maxIter > 0 {
+		return l.maxIter
+	}
+	return loopMaxIterations
+}
+
+// due reports whether the loop should fire at now (active, not paused, past its
+// next-run mark).
+func (l *loopState) due(now time.Time) bool {
+	return !l.paused && !l.nextRunAt.IsZero() && !now.Before(l.nextRunAt)
+}
+
+// cadenceText renders the loop's cadence for status lines.
+func (l *loopState) cadenceText() string {
+	if l.mode == loopModeSelfPaced {
+		return "self-paced"
+	}
+	return "every " + formatLoopDuration(l.interval)
+}
+
+type loopAction int
+
+const (
+	loopActionUsage   loopAction = iota // show usage / list when empty
+	loopActionStart                     // start a new loop
+	loopActionStop                      // stop one by id
+	loopActionStopAll                   // stop every loop
+	loopActionList                      // list active loops
+)
+
+// loopCommand is the parsed form of a `/loop ...` invocation (the text after the
+// command name).
+type loopCommand struct {
+	action   loopAction
+	targetID string
+	mode     loopMode
+	prompt   string
+	interval time.Duration
+	// note carries a non-fatal advisory (e.g. an interval that was clamped) to
+	// surface back to the user.
+	note string
+}
+
+var loopIntervalRe = regexp.MustCompile(`^(\d+)(s|m|h|d)$`)
+
+// loopControlRe matches a self-paced loop's control line at the start of a line,
+// tolerant of a leading markdown bullet/quote marker and any trailing note after
+// the keyword: "LOOP: DONE", "- loop: continue", "LOOP: CONTINUE 10m — still tidying".
+// The leading ^ anchor keeps a mid-sentence mention ("I'll emit LOOP: DONE when…")
+// from matching; parseLoopControl normalizes CRLF first so `$` can reach line end.
+var loopControlRe = regexp.MustCompile(`(?im)^[^\S\r\n]*(?:[-*>•][^\S\r\n]*)?loop:[^\S\r\n]*(done|continue)\b(?:[^\S\r\n]+(\d+[smhd])\b)?.*$`)
+
+// parseLoopCommand interprets the arguments to `/loop`. Forms:
+//
+//	(empty)                 -> usage/list
+//	list | status          -> list active loops
+//	stop | stop all | stop <id>
+//	<interval> <prompt>     -> fixed-interval loop (e.g. "5m /babysit")
+//	<prompt> every <interval>
+//	<prompt>                -> self-paced loop (no interval)
+func parseLoopCommand(args string) loopCommand {
+	trimmed := strings.TrimSpace(args)
+	if trimmed == "" {
+		return loopCommand{action: loopActionUsage}
+	}
+
+	first := strings.ToLower(strings.Fields(trimmed)[0])
+	switch first {
+	case "list", "status", "ls":
+		return loopCommand{action: loopActionList}
+	case "stop", "cancel", "kill":
+		rest := strings.TrimSpace(trimmed[len(strings.Fields(trimmed)[0]):])
+		if rest == "" || strings.EqualFold(rest, "all") {
+			if strings.EqualFold(rest, "all") {
+				return loopCommand{action: loopActionStopAll}
+			}
+			// bare "stop" stops all when ambiguous; the caller may special-case a
+			// single active loop.
+			return loopCommand{action: loopActionStop, targetID: ""}
+		}
+		return loopCommand{action: loopActionStop, targetID: strings.TrimSpace(rest)}
+	}
+
+	// Leading interval token: "5m <prompt>".
+	if fields := strings.Fields(trimmed); len(fields) >= 2 {
+		if d, ok := parseLoopInterval(fields[0]); ok {
+			prompt := strings.TrimSpace(trimmed[len(fields[0]):])
+			cmd := loopCommand{action: loopActionStart, mode: loopModeFixed, prompt: prompt}
+			cmd.interval, cmd.note = clampLoopInterval(d)
+			return cmd
+		}
+	}
+
+	// Trailing "every <interval>".
+	if prompt, d, ok := splitTrailingEvery(trimmed); ok {
+		cmd := loopCommand{action: loopActionStart, mode: loopModeFixed, prompt: prompt}
+		cmd.interval, cmd.note = clampLoopInterval(d)
+		return cmd
+	}
+
+	// No interval anywhere -> self-paced.
+	return loopCommand{action: loopActionStart, mode: loopModeSelfPaced, prompt: trimmed}
+}
+
+// splitTrailingEvery matches "<prompt> every <interval>" (the interval must be a
+// real duration token so "check every PR" is not mis-parsed as a cadence).
+func splitTrailingEvery(input string) (string, time.Duration, bool) {
+	fields := strings.Fields(input)
+	if len(fields) < 3 {
+		return "", 0, false
+	}
+	last := fields[len(fields)-1]
+	prev := fields[len(fields)-2]
+	if !strings.EqualFold(prev, "every") {
+		return "", 0, false
+	}
+	d, ok := parseLoopInterval(last)
+	if !ok {
+		return "", 0, false
+	}
+	prompt := strings.TrimSpace(strings.Join(fields[:len(fields)-2], " "))
+	if prompt == "" {
+		return "", 0, false
+	}
+	return prompt, d, true
+}
+
+// parseLoopInterval parses a bare "<N><unit>" token (s/m/h/d) into a duration.
+func parseLoopInterval(token string) (time.Duration, bool) {
+	m := loopIntervalRe.FindStringSubmatch(strings.ToLower(strings.TrimSpace(token)))
+	if m == nil {
+		return 0, false
+	}
+	n, err := strconv.Atoi(m[1])
+	if err != nil || n <= 0 {
+		return 0, false
+	}
+	unit := map[string]time.Duration{
+		"s": time.Second,
+		"m": time.Minute,
+		"h": time.Hour,
+		"d": 24 * time.Hour,
+	}[m[2]]
+	return time.Duration(n) * unit, true
+}
+
+// clampLoopInterval bounds an interval to [loopMinInterval, loopMaxInterval] and
+// returns an advisory note when it was adjusted.
+func clampLoopInterval(d time.Duration) (time.Duration, string) {
+	switch {
+	case d < loopMinInterval:
+		return loopMinInterval, fmt.Sprintf("interval raised to the %s minimum", formatLoopDuration(loopMinInterval))
+	case d > loopMaxInterval:
+		return loopMaxInterval, fmt.Sprintf("interval lowered to the %s maximum", formatLoopDuration(loopMaxInterval))
+	default:
+		return d, ""
+	}
+}
+
+// loopTickMsg is the between-turn poll that fires a due loop while the session is
+// idle. seq invalidates a tick left over from before the loop set changed.
+type loopTickMsg struct{ seq int }
+
+// handleLoopCommand dispatches a parsed `/loop ...` invocation.
+func (m model) handleLoopCommand(args string) (model, tea.Cmd) {
+	cmd := parseLoopCommand(args)
+	switch cmd.action {
+	case loopActionList:
+		return m.appendLoopSystem(m.loopListText()), nil
+	case loopActionUsage:
+		if len(m.loops) > 0 {
+			return m.appendLoopSystem(m.loopListText()), nil
+		}
+		return m.appendLoopSystem(loopUsageText()), nil
+	case loopActionStop:
+		return m.stopLoop(cmd.targetID)
+	case loopActionStopAll:
+		return m.stopAllLoops()
+	case loopActionStart:
+		return m.startLoop(cmd)
+	}
+	return m, nil
+}
+
+// startLoop registers a new loop and (re)starts the idle poll ticker. The first
+// iteration fires on the next idle tick (nextRunAt = now).
+func (m model) startLoop(cmd loopCommand) (model, tea.Cmd) {
+	if reason, ok := m.validateLoopTarget(cmd.prompt); !ok {
+		return m.appendLoopSystem(reason), nil
+	}
+	// A /command loop must be fixed-interval. Self-paced mode drives a free-form
+	// goal through the playbook + LOOP: control line (see firePrompt), which a
+	// custom command's expanded template never carries — so a bare self-paced
+	// /command would silently degrade to adaptive polling with no way to report
+	// done. Require an explicit interval for command loops instead.
+	if cmd.mode == loopModeSelfPaced && strings.HasPrefix(strings.TrimSpace(cmd.prompt), "/") {
+		return m.appendLoopSystem("A /command loop needs an interval — e.g. /loop 5m " + strings.Fields(cmd.prompt)[0] + ". Self-paced mode (no interval) is for a free-form goal."), nil
+	}
+	m.loopCounter++
+	id := "L" + strconv.Itoa(m.loopCounter)
+	loop := &loopState{
+		id:        id,
+		mode:      cmd.mode,
+		prompt:    cmd.prompt,
+		interval:  cmd.interval,
+		createdAt: m.now(),
+		nextRunAt: m.now(), // fire the first iteration on the next idle tick
+	}
+	m.loops = append(m.loops, loop)
+	note := ""
+	if cmd.note != "" {
+		note = " (" + cmd.note + ")"
+	}
+	m = m.appendLoopSystem(fmt.Sprintf(
+		"Loop %s started — %s%s. Runs while this session is idle; stop with /loop stop %s.",
+		id, loop.cadenceText(), note, id))
+	return m.ensureLoopTick()
+}
+
+// stopLoop stops one loop by id, or the single active loop when the id is omitted.
+func (m model) stopLoop(id string) (model, tea.Cmd) {
+	if len(m.loops) == 0 {
+		return m.appendLoopSystem("No active loops."), nil
+	}
+	if id == "" {
+		if len(m.loops) == 1 {
+			return m.removeLoop(m.loops[0].id, "Loop "+m.loops[0].id+" stopped.").ensureLoopTick()
+		}
+		return m.appendLoopSystem("Multiple loops active — use /loop stop <id> or /loop stop all.\n" + m.loopListText()), nil
+	}
+	if m.findLoop(id) == nil {
+		return m.appendLoopSystem("No loop " + id + ". " + m.loopListText()), nil
+	}
+	// removeLoop stops the poll ticker; re-arm it so any OTHER loops that remain
+	// keep firing (ensureLoopTick no-ops when this was the last loop).
+	return m.removeLoop(id, "Loop "+id+" stopped.").ensureLoopTick()
+}
+
+func (m model) stopAllLoops() (model, tea.Cmd) {
+	if len(m.loops) == 0 {
+		return m.appendLoopSystem("No active loops."), nil
+	}
+	n := len(m.loops)
+	m.loops = nil
+	m.loopSeq++ // invalidate the pending poll tick
+	m.loopTicking = false
+	return m.appendLoopSystem(fmt.Sprintf("Stopped all %d loop(s).", n)), nil
+}
+
+// fireDueLoopIfIdle fires the earliest due loop when the session is idle. Called
+// from the poll tick; a no-op while a turn, modal, or queued user message is
+// pending (the loop simply waits for the next idle tick).
+func (m model) fireDueLoopIfIdle() (model, tea.Cmd) {
+	if m.loopBusy() || len(m.loops) == 0 {
+		return m, nil
+	}
+	now := m.now()
+	var due *loopState
+	for _, l := range m.loops {
+		if l.due(now) && (due == nil || l.nextRunAt.Before(due.nextRunAt)) {
+			due = l
+		}
+	}
+	if due == nil {
+		return m, nil
+	}
+	m.activeLoopID = due.id
+	due.nextRunAt = time.Time{} // mark running
+	return m.fireLoopPrompt(due.firePrompt())
+}
+
+// firePrompt is the text actually sent for this iteration. A self-paced plain
+// prompt is wrapped in the maintenance playbook so the model knows to do one
+// increment of work and end with a LOOP: control line; a /command or a
+// fixed-interval prompt is sent verbatim.
+func (l *loopState) firePrompt() string {
+	if l.mode == loopModeSelfPaced && !strings.HasPrefix(strings.TrimSpace(l.prompt), "/") {
+		return loopSelfPacePlaybook(l)
+	}
+	return l.prompt
+}
+
+// fireLoopPrompt runs a loop's prompt as a turn — a custom /command if it resolves
+// to one, otherwise a plain prompt.
+func (m model) fireLoopPrompt(prompt string) (model, tea.Cmd) {
+	if strings.HasPrefix(strings.TrimSpace(prompt), "/") {
+		if next, teaCmd, ok := m.handleUserCommand(prompt); ok {
+			return next, teaCmd
+		}
+	}
+	return m.launchPrompt(prompt)
+}
+
+// advanceLoop updates a loop after one of its iterations completes: it folds the
+// result into the failure/no-progress guards, honors a self-paced DONE/next-wake
+// control line, enforces the iteration and age caps, then schedules the next wake
+// (or stops the loop).
+func (m model) advanceLoop(id, finalAnswer string, runErr error) model {
+	l := m.findLoop(id)
+	if l == nil {
+		return m // stopped mid-run
+	}
+	l.iteration++
+	if runErr != nil {
+		l.failRun++
+	} else {
+		l.failRun = 0
+	}
+	res := strings.TrimSpace(finalAnswer)
+	if res != "" && res == l.lastResult {
+		l.repeatRun++
+	} else {
+		l.repeatRun = 0
+	}
+	l.lastResult = res
+
+	// Only self-paced iterations run the playbook, so only they can carry a control
+	// line; a failed turn has no trustworthy final answer to read one from.
+	done, wake := false, time.Duration(0)
+	if l.mode == loopModeSelfPaced && runErr == nil {
+		done, wake = parseLoopControl(finalAnswer)
+	}
+
+	switch {
+	case done:
+		return m.removeLoop(id, fmt.Sprintf("Loop %s finished — the task reported done after %d iteration(s).", id, l.iteration))
+	case l.failRun >= loopMaxFailures:
+		return m.removeLoop(id, fmt.Sprintf("Loop %s stopped after %d consecutive failed iterations.", id, l.failRun))
+	case l.iteration >= l.iterationCap():
+		return m.removeLoop(id, fmt.Sprintf("Loop %s stopped at its %d-iteration cap.", id, l.iteration))
+	case !l.createdAt.IsZero() && m.now().Sub(l.createdAt) >= loopMaxAge:
+		return m.removeLoop(id, fmt.Sprintf("Loop %s expired after %s.", id, formatLoopDuration(loopMaxAge)))
+	case l.repeatRun >= loopDoomThreshold:
+		return m.removeLoop(id, fmt.Sprintf("Loop %s stopped — %d identical results in a row (no progress).", id, l.repeatRun))
+	}
+
+	if l.mode == loopModeSelfPaced {
+		// A model-chosen next wake (from the control line) wins; otherwise fall back to
+		// an adaptive cadence that checks back often while work is fresh and settles to
+		// a slow heartbeat as iterations accrue.
+		delay := wake
+		if delay <= 0 {
+			delay = adaptiveSelfPaceDelay(l.iteration)
+		}
+		l.nextRunAt = m.now().Add(clampSelfPaceDelay(delay))
+	} else {
+		l.nextRunAt = m.now().Add(l.interval)
+	}
+	return m
+}
+
+// parseLoopControl reads a self-paced loop's control signal from the model's final
+// answer. The last control line wins (the model may reference the protocol before
+// emitting it). Returns done=true to stop the loop, or a next-wake hint (0 = none).
+func parseLoopControl(answer string) (done bool, wake time.Duration) {
+	// Normalize CRLF/CR so the line-end anchor can reach `$` (Go's (?m)$ sits right
+	// before `\n`, and the horizontal-whitespace class can't consume a stray `\r`).
+	norm := strings.ReplaceAll(answer, "\r\n", "\n")
+	norm = strings.ReplaceAll(norm, "\r", "\n")
+	matches := loopControlRe.FindAllStringSubmatch(norm, -1)
+	if len(matches) == 0 {
+		return false, 0
+	}
+	last := matches[len(matches)-1]
+	if strings.EqualFold(last[1], "done") {
+		return true, 0
+	}
+	if last[2] != "" {
+		if d, ok := parseLoopInterval(last[2]); ok {
+			return false, d
+		}
+	}
+	return false, 0
+}
+
+// loopSelfPacePlaybook wraps a self-paced loop's goal in the maintenance-loop
+// instructions the model follows each iteration: do one real increment of work,
+// then emit a single control line so the harness knows whether to stop or when to
+// wake next — the self-paced maintenance playbook the feature ships with.
+func loopSelfPacePlaybook(l *loopState) string {
+	var b strings.Builder
+	b.WriteString("You are running in a self-paced maintenance loop (iteration ")
+	b.WriteString(strconv.Itoa(l.iteration + 1))
+	b.WriteString("). Do one concrete increment of work toward the goal below — actual work, not just a plan — then stop and report.\n\n")
+	b.WriteString("Goal: ")
+	b.WriteString(strings.TrimSpace(l.prompt))
+	b.WriteString("\n\nEnd your reply with a control line — on its own line, starting with \"LOOP:\":\n")
+	b.WriteString("  LOOP: DONE          — the goal is fully met; the loop stops.\n")
+	b.WriteString("  LOOP: CONTINUE      — more to do; the loop wakes again automatically.\n")
+	b.WriteString("  LOOP: CONTINUE 10m  — more to do; wake after the delay you name (e.g. 5m, 1h).\n")
+	b.WriteString("A short note after the keyword is fine. Report DONE only when the goal is genuinely complete — the loop trusts that signal to stop.")
+	return b.String()
+}
+
+// adaptiveSelfPaceDelay picks a self-paced loop's next-wake by iteration: frequent
+// early (work is actively progressing), slowing to a heartbeat as it matures.
+func adaptiveSelfPaceDelay(iteration int) time.Duration {
+	switch {
+	case iteration < 2:
+		return 2 * time.Minute
+	case iteration < 5:
+		return 5 * time.Minute
+	case iteration < 10:
+		return 15 * time.Minute
+	default:
+		return 30 * time.Minute
+	}
+}
+
+func (m model) findLoop(id string) *loopState {
+	for _, l := range m.loops {
+		if l.id == id {
+			return l
+		}
+	}
+	return nil
+}
+
+func (m model) removeLoop(id, note string) model {
+	kept := make([]*loopState, 0, len(m.loops))
+	for _, l := range m.loops {
+		if l.id != id {
+			kept = append(kept, l)
+		}
+	}
+	m.loops = kept
+	m.loopSeq++ // invalidate the pending poll tick; a fresh one is scheduled if loops remain
+	m.loopTicking = false
+	if note != "" {
+		m = m.appendLoopSystem(note)
+	}
+	return m
+}
+
+// ensureLoopTick starts the idle poll ticker if it is not already running.
+func (m model) ensureLoopTick() (model, tea.Cmd) {
+	if m.loopTicking || len(m.loops) == 0 {
+		return m, nil
+	}
+	m.loopTicking = true
+	return m, m.scheduleLoopTick()
+}
+
+func (m model) scheduleLoopTick() tea.Cmd {
+	seq := m.loopSeq
+	return tea.Tick(loopPollInterval, func(time.Time) tea.Msg {
+		return loopTickMsg{seq: seq}
+	})
+}
+
+// loopBusy reports whether the session is too busy for a loop to fire — a turn,
+// queued user message, compaction, or ANY blocking modal (permission/askUser/spec
+// review, provider or MCP wizard, MCP manager, or an open picker) is in flight.
+// The modal check is load-bearing: a loop must not launch a run behind an open
+// /resume picker, or that run would complete into whatever session the user then
+// switches to. Mirrors launchQueuedMessageIfReady so loops and queued prompts never
+// collide.
+func (m model) loopBusy() bool {
+	return m.pending || m.exiting || m.compactInFlight || m.hasQueuedMessage() || !m.noBlockingModal()
+}
+
+func (m model) appendLoopSystem(text string) model {
+	m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionAppendSystem, text: text})
+	return m
+}
+
+// loopActive reports whether any loop is running (for the footer + leave warning).
+func (m model) loopActive() bool { return len(m.loops) > 0 }
+
+// loopFooterSummary renders the persistent "N loops · next 3:05pm" footer segment,
+// or "" when no loops are active.
+func (m model) loopFooterSummary() string {
+	if len(m.loops) == 0 {
+		return ""
+	}
+	var next time.Time
+	for _, l := range m.loops {
+		if l.nextRunAt.IsZero() || l.paused {
+			continue
+		}
+		if next.IsZero() || l.nextRunAt.Before(next) {
+			next = l.nextRunAt
+		}
+	}
+	label := fmt.Sprintf("%d loop", len(m.loops))
+	if len(m.loops) != 1 {
+		label += "s"
+	}
+	if next.IsZero() {
+		return label
+	}
+	return label + " · next " + next.Format("3:04pm")
+}
+
+func (m model) loopListText() string {
+	if len(m.loops) == 0 {
+		return "No active loops."
+	}
+	var b strings.Builder
+	b.WriteString("Active loops:\n")
+	now := m.now()
+	for _, l := range m.loops {
+		when := "running"
+		if !l.nextRunAt.IsZero() {
+			if d := l.nextRunAt.Sub(now); d > 0 {
+				when = "next in " + formatLoopDuration(d.Round(time.Second))
+			} else {
+				when = "due"
+			}
+		}
+		b.WriteString(fmt.Sprintf("  %s · %s · iter %d · %s · %s\n",
+			l.id, l.cadenceText(), l.iteration, when, truncateLoopPrompt(l.prompt)))
+	}
+	b.WriteString("Stop with /loop stop <id> or /loop stop all.")
+	return b.String()
+}
+
+func loopUsageText() string {
+	return "Repeat a prompt or command:\n" +
+		"  /loop 5m /babysit-prs   — run a command every 5 minutes\n" +
+		"  /loop watch CI every 2m — trailing interval form\n" +
+		"  /loop keep tidying docs — self-paced (the model picks its own cadence and stops when done)\n" +
+		"  /loop list              — show active loops\n" +
+		"  /loop stop [id|all]     — stop a loop\n" +
+		"Loops run while this session is idle and stop when you close it."
+}
+
+// validateLoopTarget rejects looping a built-in command or an unresolved custom
+// command — only a prompt or an existing custom /command (.zero/commands/<name>.md)
+// may loop. Resolving custom commands up front stops a typo'd `/loop 5m /nope` from
+// being scheduled and then re-sent as literal text on every tick.
+func (m model) validateLoopTarget(prompt string) (string, bool) {
+	p := strings.TrimSpace(prompt)
+	if p == "" {
+		return "Nothing to loop — give a prompt or a /command.", false
+	}
+	if strings.HasPrefix(p, "/") {
+		switch parseCommand(p).kind {
+		case commandPrompt:
+			// A bare "/" or similar that isn't a command — treat as a plain prompt.
+		case commandUnknown:
+			name, _ := splitUserCommand(p)
+			if _, ok := m.lookupUserCommand(name); !ok {
+				return "No command /" + name + " — a loop can only run a prompt or an existing custom /command.", false
+			}
+		default:
+			return "A loop can only run a prompt or a custom /command, not a built-in like " + strings.Fields(p)[0] + ".", false
+		}
+	}
+	return "", true
+}
+
+// clearLoopsForSessionSwitch drops every active loop and its ticker. Loops belong to
+// the session that created them; carrying them across /new or /resume would fire the
+// old session's prompt into an unrelated conversation. Returns the count cleared so
+// the caller can note it. Pure state reset — no transcript writes.
+func (m model) clearLoopsForSessionSwitch() (model, int) {
+	n := len(m.loops)
+	if n == 0 {
+		return m, 0
+	}
+	m.loops = nil
+	m.activeLoopID = ""
+	m.loopTicking = false
+	m.loopSeq++ // invalidate any pending poll tick
+	return m, n
+}
+
+func truncateLoopPrompt(prompt string) string {
+	const max = 48
+	p := strings.TrimSpace(strings.ReplaceAll(prompt, "\n", " "))
+	runes := []rune(p)
+	if len(runes) <= max {
+		return p
+	}
+	return strings.TrimSpace(string(runes[:max])) + "…"
+}
+
+// clampSelfPaceDelay bounds a model-chosen self-paced delay to the self-pace
+// band, defaulting an unset/invalid value.
+func clampSelfPaceDelay(d time.Duration) time.Duration {
+	switch {
+	case d <= 0:
+		return loopSelfPaceDefault
+	case d < loopSelfPaceMin:
+		return loopSelfPaceMin
+	case d > loopSelfPaceMax:
+		return loopSelfPaceMax
+	default:
+		return d
+	}
+}
+
+// formatLoopDuration renders a duration compactly (90s, 5m, 2h, 1d) for status
+// text, preferring the largest whole unit.
+func formatLoopDuration(d time.Duration) string {
+	switch {
+	case d%(24*time.Hour) == 0 && d >= 24*time.Hour:
+		return strconv.Itoa(int(d/(24*time.Hour))) + "d"
+	case d%time.Hour == 0 && d >= time.Hour:
+		return strconv.Itoa(int(d/time.Hour)) + "h"
+	case d%time.Minute == 0 && d >= time.Minute:
+		return strconv.Itoa(int(d/time.Minute)) + "m"
+	default:
+		return strconv.Itoa(int(d/time.Second)) + "s"
+	}
+}

internal/tui/loop_controller_test.go

@@ -0,0 +1,460 @@
+package tui
+
+import (
+	"context"
+	"errors"
+	"strings"
+	"testing"
+	"time"
+
+	tea "charm.land/bubbletea/v2"
+
+	"github.com/Gitlawb/zero/internal/usercommands"
+)
+
+func loopTestModel(t *testing.T, now time.Time) model {
+	t.Helper()
+	m := newModel(context.Background(), Options{})
+	m.now = func() time.Time { return now }
+	return m
+}
+
+func startFixedLoop(m model, prompt string, interval time.Duration) model {
+	m, _ = m.startLoop(loopCommand{action: loopActionStart, mode: loopModeFixed, prompt: prompt, interval: interval})
+	return m
+}
+
+func TestStartLoopRegistersAndSchedules(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "check the build", 5*time.Minute)
+
+	if len(m.loops) != 1 {
+		t.Fatalf("want 1 loop, got %d", len(m.loops))
+	}
+	l := m.loops[0]
+	if l.mode != loopModeFixed || l.interval != 5*time.Minute || l.prompt != "check the build" {
+		t.Fatalf("unexpected loop %+v", l)
+	}
+	// First iteration is due immediately (nextRunAt == now).
+	if !l.due(now) {
+		t.Errorf("first iteration should be due at creation")
+	}
+	if !m.loopTicking {
+		t.Errorf("starting a loop should start the poll ticker")
+	}
+}
+
+func TestAdvanceLoopSchedulesNextWake(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "poll", 5*time.Minute)
+	id := m.loops[0].id
+
+	m = m.advanceLoop(id, "did some work", nil)
+	l := m.loops[0]
+	if l.iteration != 1 {
+		t.Fatalf("iteration = %d, want 1", l.iteration)
+	}
+	if !l.nextRunAt.Equal(now.Add(5 * time.Minute)) {
+		t.Fatalf("nextRunAt = %v, want +5m", l.nextRunAt)
+	}
+}
+
+func TestSelfPacedUsesModelDelay(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m, _ = m.startLoop(loopCommand{action: loopActionStart, mode: loopModeSelfPaced, prompt: "keep tidying"})
+	id := m.loops[0].id
+	// The model carries its chosen next wake in the reply's control line.
+	m = m.advanceLoop(id, "made progress\nLOOP: CONTINUE 10m", nil)
+	if len(m.loops) == 0 {
+		t.Fatal("a CONTINUE control line should keep the loop running")
+	}
+	if !m.loops[0].nextRunAt.Equal(now.Add(10 * time.Minute)) {
+		t.Fatalf("self-paced nextRunAt = %v, want +10m", m.loops[0].nextRunAt)
+	}
+}
+
+func TestLoopDoneStops(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m, _ = m.startLoop(loopCommand{action: loopActionStart, mode: loopModeSelfPaced, prompt: "finish the task"})
+	id := m.loops[0].id
+	m = m.advanceLoop(id, "all done\nLOOP: DONE", nil)
+	if len(m.loops) != 0 {
+		t.Fatalf("loop should stop when the task reports done, %d remain", len(m.loops))
+	}
+}
+
+func TestFixedLoopIgnoresControlLine(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "watch CI", time.Minute)
+	id := m.loops[0].id
+	// A fixed-interval loop never runs the playbook, so a stray control line in the
+	// output is not a completion signal — it keeps its wall-clock cadence.
+	m = m.advanceLoop(id, "LOOP: DONE", nil)
+	if len(m.loops) != 1 {
+		t.Fatal("a fixed-interval loop should ignore a control line and keep running")
+	}
+	if !m.loops[0].nextRunAt.Equal(now.Add(time.Minute)) {
+		t.Fatalf("fixed nextRunAt = %v, want +1m", m.loops[0].nextRunAt)
+	}
+}
+
+func TestLoopExpiresByAge(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "forgotten", time.Minute)
+	id := m.loops[0].id
+	m.loops[0].createdAt = now.Add(-loopMaxAge - time.Hour) // created past the age cap
+	m = m.advanceLoop(id, "still going", nil)
+	if len(m.loops) != 0 {
+		t.Fatal("a loop past its age cap should auto-expire")
+	}
+}
+
+func TestLoopDoomGuardStops(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "spin", time.Minute)
+	id := m.loops[0].id
+	for i := 0; i < loopDoomThreshold+1 && len(m.loops) > 0; i++ {
+		m = m.advanceLoop(id, "identical answer", nil)
+	}
+	if len(m.loops) != 0 {
+		t.Fatalf("doom guard should stop a loop repeating identical results")
+	}
+}
+
+func TestLoopIterationCapStops(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "bounded", time.Minute)
+	m.loops[0].maxIter = 3
+	id := m.loops[0].id
+	for i := 0; i < 3 && len(m.loops) > 0; i++ {
+		m = m.advanceLoop(id, "answer "+string(rune('a'+i)), nil) // distinct answers so doom doesn't fire
+	}
+	if len(m.loops) != 0 {
+		t.Fatalf("loop should stop at its iteration cap")
+	}
+}
+
+func TestStopLoopByID(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "a", time.Minute)
+	m = startFixedLoop(m, "b", time.Minute)
+	id := m.loops[0].id
+	m, cmd := m.stopLoop(id)
+	if len(m.loops) != 1 || m.findLoop(id) != nil {
+		t.Fatalf("stopLoop(%s) should remove exactly that loop", id)
+	}
+	// Stopping one of several loops must keep the poll ticker alive for the rest:
+	// removeLoop kills the ticker, so stopLoop has to re-arm it (jatmn).
+	if cmd == nil || !m.loopTicking {
+		t.Fatal("stopping one of several loops must leave the remaining loop scheduled (ticker re-armed)")
+	}
+	// Bare stop with a single active loop stops that sole loop (parseLoopCommand
+	// leaves the target empty and stopLoop special-cases the one-loop case).
+	soleID := m.loops[0].id
+	m, _ = m.stopLoop("")
+	if len(m.loops) != 0 || m.findLoop(soleID) != nil {
+		t.Fatalf("bare stop should remove the sole active loop")
+	}
+	m = startFixedLoop(m, "c", time.Minute)
+	m = startFixedLoop(m, "d", time.Minute)
+	m, _ = m.stopAllLoops()
+	if len(m.loops) != 0 {
+		t.Fatalf("stopAllLoops should clear all loops")
+	}
+}
+
+func TestFireDueLoopSkipsWhenBusy(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "x", time.Minute)
+	m.pending = true // a turn is in flight
+	got, cmd := m.fireDueLoopIfIdle()
+	if got.activeLoopID != "" || cmd != nil {
+		t.Fatalf("a due loop must not fire while a turn is pending")
+	}
+}
+
+func TestFireDueLoopSkipsBehindModal(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "poll", time.Minute) // due immediately
+	m.picker = &commandPicker{}                // e.g. an open /resume session picker
+	got, cmd := m.fireDueLoopIfIdle()
+	if got.activeLoopID != "" || cmd != nil {
+		t.Fatal("a due loop must not launch a run behind an open picker/modal — it would complete into whatever session the user switches to")
+	}
+	if got.loops[0].nextRunAt.IsZero() {
+		t.Fatal("a loop skipped because a modal is open must stay scheduled, not have its next run cleared")
+	}
+}
+
+func TestAdaptiveSelfPaceDelayWidensOverTime(t *testing.T) {
+	if adaptiveSelfPaceDelay(0) >= adaptiveSelfPaceDelay(5) {
+		t.Error("early iterations should check back sooner than later ones")
+	}
+	if adaptiveSelfPaceDelay(20) != 30*time.Minute {
+		t.Errorf("a mature loop should settle to a 30m heartbeat, got %v", adaptiveSelfPaceDelay(20))
+	}
+}
+
+func TestLoopFooterSummary(t *testing.T) {
+	now := time.Date(2026, 7, 5, 15, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	if m.loopFooterSummary() != "" {
+		t.Error("no loops -> empty footer summary")
+	}
+	m = startFixedLoop(m, "a", 5*time.Minute)
+	m.loops[0].nextRunAt = now.Add(5 * time.Minute)
+	got := m.loopFooterSummary()
+	wantWake := "next " + now.Add(5*time.Minute).Format("3:04pm")
+	if !strings.HasPrefix(got, "1 loop") || !strings.Contains(got, wantWake) {
+		t.Fatalf("footer summary = %q, want it to start with a loop count and contain %q", got, wantWake)
+	}
+}
+
+func TestLoopCommandThroughSubmit(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m.input.SetValue("/loop 5m tidy the imports")
+	updated, _ := m.Update(testKey(tea.KeyEnter))
+	next := updated.(model)
+	if len(next.loops) != 1 {
+		t.Fatalf("submitting /loop should create a loop, got %d", len(next.loops))
+	}
+	if next.loops[0].mode != loopModeFixed || next.loops[0].interval != 5*time.Minute {
+		t.Fatalf("unexpected loop from submit: %+v", next.loops[0])
+	}
+	if !next.loopTicking {
+		t.Fatalf("submitting /loop should start the poll ticker")
+	}
+
+	// /loop stop all through the same path clears it.
+	next.input.SetValue("/loop stop all")
+	updated2, _ := next.Update(testKey(tea.KeyEnter))
+	final := updated2.(model)
+	if len(final.loops) != 0 {
+		t.Fatalf("/loop stop all should clear loops, got %d", len(final.loops))
+	}
+}
+
+func TestStaleLoopTickIgnored(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "x", time.Minute)
+	m.loopSeq = 7
+	// A tick from before the seq changed must be dropped and stop the ticker.
+	updated, cmd := m.Update(loopTickMsg{seq: 3})
+	next := updated.(model)
+	if next.loopTicking {
+		t.Error("a stale loop tick should stop the ticker")
+	}
+	if cmd != nil {
+		t.Error("a stale loop tick should not reschedule")
+	}
+}
+
+func TestLoopStopsAfterConsecutiveFailures(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "flaky", time.Minute)
+	id := m.loops[0].id
+	boom := errors.New("boom")
+	for i := 0; i < loopMaxFailures && len(m.loops) > 0; i++ {
+		m = m.advanceLoop(id, "", boom)
+	}
+	if len(m.loops) != 0 {
+		t.Fatalf("loop should stop after %d consecutive failed iterations", loopMaxFailures)
+	}
+}
+
+func TestLoopFailureCounterResetsOnSuccess(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "recovers", time.Minute)
+	id := m.loops[0].id
+	m = m.advanceLoop(id, "", errors.New("x"))
+	m = m.advanceLoop(id, "", errors.New("x"))
+	m = m.advanceLoop(id, "back to healthy", nil) // a success resets the streak
+	if len(m.loops) != 1 {
+		t.Fatalf("a recovered failure streak should not stop the loop")
+	}
+	if m.loops[0].failRun != 0 {
+		t.Fatalf("a successful iteration should reset failRun, got %d", m.loops[0].failRun)
+	}
+}
+
+func TestCancelRunClearsActiveLoopAndRearms(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "x", 5*time.Minute)
+	m.activeLoopID = m.loops[0].id
+	m.loops[0].nextRunAt = time.Time{} // as if the iteration is running
+	m.pending = true
+	m.activeRunID = 7
+	m.runCancel = func() {}
+
+	m.cancelRun()
+
+	if m.activeLoopID != "" {
+		t.Fatal("cancel should clear the active-loop tag so the next turn isn't misattributed")
+	}
+	if m.loops[0].nextRunAt.IsZero() {
+		t.Fatal("cancel should re-arm the interrupted loop, not leave it running forever")
+	}
+	if !m.loops[0].nextRunAt.Equal(now.Add(5 * time.Minute)) {
+		t.Fatalf("re-armed nextRunAt = %v, want +5m", m.loops[0].nextRunAt)
+	}
+}
+
+func TestValidateLoopTargetRejectsBuiltin(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	if _, ok := m.validateLoopTarget("/model list"); ok {
+		t.Error("looping a built-in command should be rejected")
+	}
+	if _, ok := m.validateLoopTarget("keep improving docs"); !ok {
+		t.Error("a plain prompt should be a valid loop target")
+	}
+	if _, ok := m.validateLoopTarget(""); ok {
+		t.Error("an empty target should be rejected")
+	}
+	// A custom command that does not exist is rejected up front, so it is never
+	// scheduled and then re-sent as literal "/…" text on every tick.
+	if _, ok := m.validateLoopTarget("/babysit-prs"); ok {
+		t.Error("an unresolved custom command should be rejected")
+	}
+	// A registered custom command is accepted.
+	m.userCommands = []usercommands.Command{{Name: "babysit-prs", Template: "check the PRs"}}
+	if _, ok := m.validateLoopTarget("/babysit-prs"); !ok {
+		t.Error("an existing custom command should be a valid loop target")
+	}
+}
+
+func TestSelfPacedCommandLoopRejected(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m.userCommands = []usercommands.Command{{Name: "babysit-prs", Template: "check the PRs"}}
+	// A /command with no interval parses as self-paced, but self-paced mode drives
+	// a free-form goal via the playbook + LOOP: protocol, which a command's
+	// expanded template never carries — so a bare self-paced /command is rejected.
+	m, _ = m.startLoop(loopCommand{action: loopActionStart, mode: loopModeSelfPaced, prompt: "/babysit-prs"})
+	if len(m.loops) != 0 {
+		t.Fatal("a bare self-paced /command loop should be rejected (a command loop needs an interval)")
+	}
+	// The same command with an interval (fixed) is accepted.
+	m, _ = m.startLoop(loopCommand{action: loopActionStart, mode: loopModeFixed, prompt: "/babysit-prs", interval: 5 * time.Minute})
+	if len(m.loops) != 1 {
+		t.Fatal("a fixed-interval /command loop should be accepted")
+	}
+}
+
+func TestClearLoopsForSessionSwitch(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "a", time.Minute)
+	m = startFixedLoop(m, "b", time.Minute)
+	m.activeLoopID = m.loops[0].id
+	m, n := m.clearLoopsForSessionSwitch()
+	if n != 2 || len(m.loops) != 0 || m.activeLoopID != "" || m.loopTicking {
+		t.Fatalf("session switch should clear all loop state; got n=%d loops=%d active=%q ticking=%v",
+			n, len(m.loops), m.activeLoopID, m.loopTicking)
+	}
+}
+
+func TestStartNewSessionStopsLoops(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "x", time.Minute)
+	m = m.startNewSession()
+	if len(m.loops) != 0 || m.loopTicking {
+		t.Fatal("/new should stop loops tied to the previous session")
+	}
+}
+
+func TestLoopClearRequiresConfirm(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "x", time.Minute)
+
+	// First /clear with a loop active arms the confirm and does not clear yet.
+	m.input.SetValue("/clear")
+	u1, _ := m.Update(testKey(tea.KeyEnter))
+	n1 := u1.(model)
+	if n1.loopLeavePrompt != commandClear {
+		t.Fatal("first /clear with active loops should arm the confirm, not clear")
+	}
+	if len(n1.loops) != 1 {
+		t.Fatal("the loop should still be active after the warning")
+	}
+
+	// A different command disarms the confirm.
+	n1.input.SetValue("/loop list")
+	u2, _ := n1.Update(testKey(tea.KeyEnter))
+	n2 := u2.(model)
+	if n2.loopLeavePrompt != commandEmpty {
+		t.Fatal("an intervening command should disarm the leave confirm")
+	}
+
+	// Re-arm, then a second consecutive /clear confirms (disarms + clears).
+	n2.input.SetValue("/clear")
+	u3, _ := n2.Update(testKey(tea.KeyEnter))
+	n3 := u3.(model)
+	n3.input.SetValue("/clear")
+	u4, _ := n3.Update(testKey(tea.KeyEnter))
+	n4 := u4.(model)
+	if n4.loopLeavePrompt != commandEmpty {
+		t.Fatal("a second consecutive /clear should confirm and disarm")
+	}
+	if len(n4.loops) != 1 {
+		t.Fatal("/clear keeps loops running (it wipes the screen, not the session)")
+	}
+	// The confirmed clear must actually wipe the transcript, not silently no-op:
+	// only the clear path appends the "Transcript cleared" note, and the pre-clear
+	// loop-start row must be gone.
+	clearedNote, staleRow := false, false
+	for _, r := range n4.transcript {
+		if strings.Contains(r.text, "Transcript cleared") {
+			clearedNote = true
+		}
+		if strings.Contains(r.text, "Loop L1 started") {
+			staleRow = true
+		}
+	}
+	if !clearedNote || staleRow {
+		t.Fatalf("the second /clear must wipe the transcript (clearedNote=%v staleRow=%v)", clearedNote, staleRow)
+	}
+}
+
+func TestLeaveConfirmDisarmedByQueuedPrompt(t *testing.T) {
+	now := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	m := loopTestModel(t, now)
+	m = startFixedLoop(m, "x", time.Minute)
+
+	// Arm the /clear confirm.
+	m.input.SetValue("/clear")
+	u1, _ := m.Update(testKey(tea.KeyEnter))
+	n1 := u1.(model)
+	if n1.loopLeavePrompt != commandClear {
+		t.Fatal("first /clear should arm the confirm")
+	}
+
+	// A prompt submitted while a run streams is queued via an early return in
+	// handleSubmit; it must still disarm the confirm (the disarm runs before those
+	// returns). Otherwise a later /clear would be treated as the second press.
+	n1.pending = true
+	n1.input.SetValue("a follow-up question")
+	u2, _ := n1.Update(testKey(tea.KeyEnter))
+	n2 := u2.(model)
+	if n2.loopLeavePrompt != commandEmpty {
+		t.Fatal("a queued prompt should disarm the leave confirm; the early return must not skip the disarm")
+	}
+}

internal/tui/loop_test.go

@@ -0,0 +1,156 @@
+package tui
+
+import (
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestParseLoopCommandModes(t *testing.T) {
+	cases := []struct {
+		in       string
+		action   loopAction
+		mode     loopMode
+		prompt   string
+		interval time.Duration
+	}{
+		{"", loopActionUsage, 0, "", 0},
+		{"list", loopActionList, 0, "", 0},
+		{"status", loopActionList, 0, "", 0},
+		{"stop all", loopActionStopAll, 0, "", 0},
+		{"stop ab12", loopActionStop, 0, "", 0},
+		{"5m /babysit-prs", loopActionStart, loopModeFixed, "/babysit-prs", 5 * time.Minute},
+		{"90s check the build", loopActionStart, loopModeFixed, "check the build", 90 * time.Second},
+		{"watch CI every 2m", loopActionStart, loopModeFixed, "watch CI", 2 * time.Minute},
+		{"keep improving the docs", loopActionStart, loopModeSelfPaced, "keep improving the docs", 0},
+		// "every PR" is not a cadence — the token after "every" isn't a duration.
+		{"review every PR", loopActionStart, loopModeSelfPaced, "review every PR", 0},
+	}
+	for _, c := range cases {
+		got := parseLoopCommand(c.in)
+		if got.action != c.action {
+			t.Errorf("%q action = %v, want %v", c.in, got.action, c.action)
+		}
+		if c.action == loopActionStart {
+			if got.mode != c.mode {
+				t.Errorf("%q mode = %v, want %v", c.in, got.mode, c.mode)
+			}
+			if got.prompt != c.prompt {
+				t.Errorf("%q prompt = %q, want %q", c.in, got.prompt, c.prompt)
+			}
+			if got.interval != c.interval {
+				t.Errorf("%q interval = %v, want %v", c.in, got.interval, c.interval)
+			}
+		}
+	}
+}
+
+func TestParseLoopCommandStopTarget(t *testing.T) {
+	if got := parseLoopCommand("stop"); got.action != loopActionStop || got.targetID != "" {
+		t.Fatalf("bare stop = %+v, want stop with empty target", got)
+	}
+	if got := parseLoopCommand("stop XyZ9"); got.targetID != "XyZ9" {
+		t.Fatalf("stop target = %q, want XyZ9", got.targetID)
+	}
+}
+
+func TestClampLoopInterval(t *testing.T) {
+	if d, note := clampLoopInterval(5 * time.Second); d != loopMinInterval || note == "" {
+		t.Fatalf("below-min = (%v,%q), want raised to min with note", d, note)
+	}
+	if d, note := clampLoopInterval(48 * time.Hour); d != loopMaxInterval || note == "" {
+		t.Fatalf("above-max = (%v,%q), want lowered to max with note", d, note)
+	}
+	if d, note := clampLoopInterval(5 * time.Minute); d != 5*time.Minute || note != "" {
+		t.Fatalf("in-range = (%v,%q), want unchanged, no note", d, note)
+	}
+}
+
+func TestClampSelfPaceDelay(t *testing.T) {
+	if got := clampSelfPaceDelay(0); got != loopSelfPaceDefault {
+		t.Errorf("zero delay = %v, want default %v", got, loopSelfPaceDefault)
+	}
+	if got := clampSelfPaceDelay(10 * time.Second); got != loopSelfPaceMin {
+		t.Errorf("below-min = %v, want %v", got, loopSelfPaceMin)
+	}
+	if got := clampSelfPaceDelay(3 * time.Hour); got != loopSelfPaceMax {
+		t.Errorf("above-max = %v, want %v", got, loopSelfPaceMax)
+	}
+	if got := clampSelfPaceDelay(10 * time.Minute); got != 10*time.Minute {
+		t.Errorf("in-band = %v, want unchanged", got)
+	}
+}
+
+func TestFormatLoopDuration(t *testing.T) {
+	cases := map[time.Duration]string{
+		30 * time.Second: "30s",
+		90 * time.Second: "90s",
+		5 * time.Minute:  "5m",
+		2 * time.Hour:    "2h",
+		24 * time.Hour:   "1d",
+	}
+	for d, want := range cases {
+		if got := formatLoopDuration(d); got != want {
+			t.Errorf("formatLoopDuration(%v) = %q, want %q", d, got, want)
+		}
+	}
+}
+
+func TestParseLoopControl(t *testing.T) {
+	cases := []struct {
+		in   string
+		done bool
+		wake time.Duration
+	}{
+		{"did the work\nLOOP: DONE", true, 0},
+		{"progress\nLOOP: CONTINUE", false, 0},
+		{"progress\nLOOP: CONTINUE 10m", false, 10 * time.Minute},
+		{"progress\n- loop: continue 1h", false, time.Hour},                     // markdown bullet, lowercase
+		{"LOOP: CONTINUE 5m\n...more...\nLOOP: DONE", true, 0},                  // last control line wins
+		{"no control line here", false, 0},                                      // absent -> adaptive
+		{"LOOP: DONE — all tests pass", true, 0},                                // a trailing note is fine
+		{"progress\nLOOP: CONTINUE 5m — still tidying", false, 5 * time.Minute}, // note after the interval
+		{"work done.\r\nLOOP: DONE\r\n", true, 0},                               // CRLF endings still parse
+		{"work\r\nLOOP: CONTINUE 10m\r\n", false, 10 * time.Minute},             // CRLF + interval
+		{"I will emit LOOP: DONE when finished", false, 0},                      // mid-sentence mention doesn't match
+		{"LOOP: CONTINUE 99z", false, 0},                                        // bad unit -> continue, no wake hint
+	}
+	for _, c := range cases {
+		done, wake := parseLoopControl(c.in)
+		if done != c.done || wake != c.wake {
+			t.Errorf("parseLoopControl(%q) = (%v,%v), want (%v,%v)", c.in, done, wake, c.done, c.wake)
+		}
+	}
+}
+
+func TestFirePromptWrapsSelfPacedOnly(t *testing.T) {
+	self := &loopState{mode: loopModeSelfPaced, prompt: "tidy the docs"}
+	got := self.firePrompt()
+	if !strings.Contains(got, "LOOP: DONE") || !strings.Contains(got, "tidy the docs") {
+		t.Errorf("self-paced firePrompt should embed the playbook and goal, got %q", got)
+	}
+	fixed := &loopState{mode: loopModeFixed, prompt: "check the build"}
+	if fixed.firePrompt() != "check the build" {
+		t.Errorf("fixed-interval firePrompt should be verbatim, got %q", fixed.firePrompt())
+	}
+	// A self-paced /command is a real command, not a goal — send it verbatim, no playbook.
+	cmd := &loopState{mode: loopModeSelfPaced, prompt: "/babysit"}
+	if cmd.firePrompt() != "/babysit" {
+		t.Errorf("self-paced /command firePrompt should be verbatim, got %q", cmd.firePrompt())
+	}
+}
+
+func TestLoopStateDue(t *testing.T) {
+	base := time.Date(2026, 7, 5, 12, 0, 0, 0, time.UTC)
+	l := &loopState{nextRunAt: base}
+	if l.due(base.Add(-time.Second)) {
+		t.Error("loop should not be due before nextRunAt")
+	}
+	if !l.due(base) {
+		t.Error("loop should be due at nextRunAt")
+	}
+	l.paused = true
+	if l.due(base.Add(time.Hour)) {
+		t.Error("paused loop should never be due")
+	}
+}

internal/tui/model.go

@@ -190,10 +190,22 @@ type model struct {
 	// like a frozen terminal (for ANY provider, not just slow ones). Zero = idle.
 	turnStartedAt time.Time
 	queuedMessage string
-	exiting       bool
-	runCancel     context.CancelFunc
-	runID         int
-	activeRunID   int
+	// loops holds the session's active /loop definitions (see loop.go). activeLoopID
+	// tags the in-flight run when it is a loop iteration (empty = a user turn), so the
+	// completion seam knows whether to advance a loop. loopSeq invalidates a stale
+	// pending poll tick when loops are stopped; loopTicking guards against scheduling
+	// a second poll ticker. loopLeavePrompt arms a one-shot confirm before /clear or
+	// /quit while loops are active (see handleSubmit).
+	loops           []*loopState
+	activeLoopID    string
+	loopSeq         int
+	loopCounter     int
+	loopTicking     bool
+	loopLeavePrompt commandKind
+	exiting         bool
+	runCancel       context.CancelFunc
+	runID           int
+	activeRunID     int
 	// flushRunIDs holds the ids of runs cancelled while still in flight, mapped
 	// to the session they were recording into AT CANCEL TIME. Each cancelled
 	// agent goroutine keeps running to completion and returns its accumulated
@@ -1896,6 +1908,16 @@ func (m model) updateModel(msg tea.Msg) (tea.Model, tea.Cmd) {
 		m.clearComposer()
 		m.clearSuggestions()
 		return m, nil
+	case loopTickMsg:
+		// Idle poll for due loops. A stale tick (loops changed) or an empty loop set
+		// ends the ticker; otherwise fire the earliest due loop if idle and reschedule.
+		if msg.seq != m.loopSeq || len(m.loops) == 0 {
+			m.loopTicking = false
+			return m, nil
+		}
+		var fireCmd tea.Cmd
+		m, fireCmd = m.fireDueLoopIfIdle()
+		return m, tea.Batch(fireCmd, m.scheduleLoopTick())
 	case agentResponseMsg:
 		if msg.runID != m.activeRunID {
 			// A run cancelled while in flight still finishes in its goroutine and
@@ -2065,8 +2087,25 @@ func (m model) updateModel(msg tea.Msg) (tea.Model, tea.Cmd) {
 		// complete once the turn settles.
 		var sweepCmd tea.Cmd
 		m, sweepCmd = m.maybeGitSweep()
+		// If this run was a loop iteration, advance that loop (schedule its next wake
+		// or stop it). Done before launchQueuedMessageIfReady so a user's queued prompt
+		// still wins the immediate re-launch; the loop fires on the next idle tick.
+		var loopTickCmd tea.Cmd
+		if loopID := m.activeLoopID; loopID != "" {
+			m.activeLoopID = ""
+			loopFinalAnswer := ""
+			for _, row := range msg.rows {
+				if row.kind == rowAssistant && row.final {
+					loopFinalAnswer = row.text
+				}
+			}
+			m = m.advanceLoop(loopID, loopFinalAnswer, msg.err)
+			// advanceLoop -> removeLoop may have stopped the ticker; restart it if
+			// other loops remain.
+			m, loopTickCmd = m.ensureLoopTick()
+		}
 		next, queuedCmd := m.launchQueuedMessageIfReady()
-		return next, tea.Batch(titleCmd, recapCmd, sweepCmd, queuedCmd)
+		return next, tea.Batch(titleCmd, recapCmd, sweepCmd, queuedCmd, loopTickCmd)
 	case sessionTitleGeneratedMsg:
 		return m.handleSessionTitleGenerated(msg)
 	case recapGeneratedMsg:
@@ -3789,6 +3828,13 @@ func (m model) handleSubmit() (tea.Model, tea.Cmd) {
 		return m, nil
 	}
 	command := parseCommand(input)
+	// A pending /clear or /quit leave-confirmation is armed for the immediately-next
+	// repeat of that same command only; any other submission — including one queued
+	// or deferred by the early returns below — disarms it. Runs before those returns
+	// so an interposed prompt can't be skipped over and leave the gate falsely armed.
+	if m.loopLeavePrompt != commandEmpty && command.kind != m.loopLeavePrompt {
+		m.loopLeavePrompt = commandEmpty
+	}
 	// While exiting (Ctrl+C waiting on the cancelled run's checkpoint flush) a
 	// new run must not start: the deferred tea.Quit would abort it mid-flight
 	// and orphan its checkpoint blobs — the exact loss flushRunIDs prevents.
@@ -3822,6 +3868,14 @@ func (m model) handleSubmit() (tea.Model, tea.Cmd) {
 		m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionAppendSystem, text: helpText()})
 		return m, nil
 	case commandClear:
+		// A foreground loop keeps firing after /clear (it wipes the screen, not the
+		// session), so warn once before clearing the context it will run into.
+		if m.loopActive() && m.loopLeavePrompt != commandClear {
+			m.loopLeavePrompt = commandClear
+			m = m.appendLoopSystem(m.loopFooterSummary() + " still running — /clear keeps them firing behind a cleared screen. Run /clear again to confirm, or /loop stop all first.")
+			return m, nil
+		}
+		m.loopLeavePrompt = commandEmpty
 		m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionClear})
 		// Clearing wipes the visible transcript only — the session's context is
 		// intact, so the next prompt still replays the full history. Say so, and
@@ -3830,6 +3884,11 @@ func (m model) handleSubmit() (tea.Model, tea.Cmd) {
 		// Scrollback above can't be un-printed; a faint divider marks where the
 		// cleared surface ended and the frontier restarts for the fresh transcript.
 		m.resetFlushFrontier("· cleared ·")
+		// /clear wipes the transcript but not the session, so loops keep running;
+		// say so rather than let them silently fire into a "cleared" screen.
+		if m.loopActive() {
+			m = m.appendLoopSystem(m.loopFooterSummary() + " still running — /loop stop all to end them.")
+		}
 		return m, nil
 	case commandNew:
 		// A fresh session mid-run would strand the in-flight turn's events; make the
@@ -3840,7 +3899,17 @@ func (m model) handleSubmit() (tea.Model, tea.Cmd) {
 			return m, nil
 		}
 		return m.startNewSession(), nil
+	case commandLoop:
+		return m.handleLoopCommand(command.text)
 	case commandExit:
+		// Closing the session stops its foreground loops mid-task; warn once so a
+		// token-spending loop isn't ended by reflex.
+		if m.loopActive() && m.loopLeavePrompt != commandExit {
+			m.loopLeavePrompt = commandExit
+			m = m.appendLoopSystem(m.loopFooterSummary() + " active — closing the session stops them. Run /exit again to confirm, or /loop stop all first.")
+			return m, nil
+		}
+		m.loopLeavePrompt = commandEmpty
 		// /exit gets the same protection as Ctrl+C: cancel any in-flight run and
 		// defer the quit until its checkpoint session events flush — quitting
 		// immediately would orphan the blobs and break /rewind.
@@ -4333,6 +4402,21 @@ func (m *model) cancelRun() {
 		m.runCancel()
 	}
 	m.clearStreamingToolCall() // a cancelled file-write must not linger into the next run
+	// A cancelled loop iteration bypasses the agentResponseMsg completion seam (its
+	// late message is drained through flushRunIDs, not advanceLoop), so clear the
+	// loop tag here and re-arm the interrupted loop for its next cadence. Otherwise
+	// the loop is left "running" forever (nextRunAt stays zero) and the NEXT
+	// unrelated turn would be misattributed as this loop's completion.
+	if m.activeLoopID != "" {
+		if l := m.findLoop(m.activeLoopID); l != nil {
+			if l.mode == loopModeSelfPaced {
+				l.nextRunAt = m.now().Add(clampSelfPaceDelay(adaptiveSelfPaceDelay(l.iteration)))
+			} else {
+				l.nextRunAt = m.now().Add(l.interval)
+			}
+		}
+		m.activeLoopID = ""
+	}
 	// Remember the in-flight run — and the session it was recording into — so
 	// its final agentResponseMsg is still drained for session-event persistence
 	// after activeRunID is cleared. Otherwise the checkpoint blobs it captured

internal/tui/session.go

@@ -99,6 +99,12 @@ func (m model) startNewSession() model {
 	// Scrollback above can't be un-printed; a faint divider marks the boundary and
 	// the flush frontier restarts for the fresh transcript (mirrors /clear, /resume).
 	m.resetFlushFrontier("· new session ·")
+	// Loops belong to the previous session; stop them so they don't fire the old
+	// conversation's prompt into the fresh one.
+	if updated, cleared := m.clearLoopsForSessionSwitch(); cleared > 0 {
+		m = updated
+		m.transcript = reduceTranscript(m.transcript, transcriptAction{kind: actionAppendSystem, text: fmt.Sprintf("Stopped %d loop(s) tied to the previous session.", cleared)})
+	}
 	return m
 }
 
@@ -205,6 +211,10 @@ func (m model) handleResumeCommand(args string) (model, string) {
 		return m, "Sessions\nerror: " + err.Error()
 	}
 
+	// Capture the current session id before switching so loops are only torn down
+	// on a real change — `/resume latest` or `/resume <currentID>` can resolve to
+	// the already-active session, whose loops belong to it, not a "previous" one.
+	previousID := m.activeSession.SessionID
 	m.activeSession = *session
 	m.sessionEvents = append([]sessions.Event{}, events...)
 	if m.providerName == "" {
@@ -213,9 +223,16 @@ func (m model) handleResumeCommand(args string) (model, string) {
 	if m.modelName == "" {
 		m.modelName = session.ModelID
 	}
+	loopsCleared := 0
+	if session.SessionID != previousID {
+		m, loopsCleared = m.clearLoopsForSessionSwitch()
+	}
 
 	rows := initialTranscript()
 	rows = appendRow(rows, rowSystem, m.formatResumeSummary(*session, len(events)))
+	if loopsCleared > 0 {
+		rows = appendRow(rows, rowSystem, fmt.Sprintf("Stopped %d loop(s) tied to the previous session.", loopsCleared))
+	}
 	rows = appendTranscriptRowsDedup(rows, transcriptRowsFromSessionEvents(events))
 	m.transcript = rows
 	// Every rehydrated row is settled by construction, so resetting the flush

internal/tui/view.go

@@ -218,6 +218,13 @@ func (m model) statusLine(width int) string {
 	} else if summary := m.backgroundTerminalSummary(); summary != "" {
 		left += separator + zeroTheme.muted.Render(summary)
 	}
+	// Active loops surface a persistent "↻ N loops · next 3:05pm" segment so a
+	// running loop is always visible (hidden during an exit/cancel confirm above).
+	if !m.exitConfirmActive && !m.cancelConfirmActive {
+		if loopSummary := m.loopFooterSummary(); loopSummary != "" {
+			left += separator + zeroTheme.accent.Render("↻ ") + zeroTheme.muted.Render(loopSummary)
+		}
+	}
 
 	rightGroups := []string{}
 	// Context-fill gauge: surface it down to the narrow tier (where it matters