Add every(N) bind event and FZF_IDLE_TIME env var (#4797)

- every(N) fires every N seconds (fractional, floored to 0.01s)
- Encoded as tui.Every with duration in Char as milliseconds, so
  every(1) and every(2) coexist as distinct keymap entries
- FZF_IDLE_TIME exposes whole seconds since the last user activity
  (keystroke or mouse event); pair with every() for idle-based
  patterns like auto-accept/auto-quit

Close #1211

Author: junegunn

CHANGELOG.md

@@ -3,6 +3,19 @@ CHANGELOG
 
 0.73.0
 ------
+- Timer-driven `every(N)` event for `--bind`, where `N` is seconds (fractional, floored to `0.01`). Ticks that overlap an in-flight action are coalesced, so a slow `reload` cannot accumulate a backlog.
+- New `FZF_IDLE_TIME` (whole seconds) and `FZF_IDLE_TIME_MS` (milliseconds) environment variables exported to child processes, holding the elapsed time since the last user activity. Pair with `every(N)` to build idle-based behavior such as auto-accept or auto-quit (#1211).
+      ```sh
+      # Live process list; --track --id-nth 2 keeps the cursor on the same PID across reloads
+      fzf --header-lines 1 --track --id-nth 2 --bind 'start,every(2):reload-sync:ps -ef'
+
+      # Auto-accept after 10 seconds of inactivity, with a countdown in the footer after 5s
+      fzf --bind 'every(1):bg-transform:
+        if   [[ $FZF_IDLE_TIME -lt 5  ]]; then echo change-footer:
+        elif [[ $FZF_IDLE_TIME -lt 10 ]]; then echo "change-footer:auto-accept in $((10 - FZF_IDLE_TIME))s"
+        else echo accept
+        fi'
+      ```
 - Bug fixes
     - `change-preview-window` no longer resets `wrap` / `wrap-word` state set via `toggle-preview-wrap` / `toggle-preview-wrap-word`. Layout fields still snap to the preset, so cycling and the empty-token reset behave as before. The new spec can still override by including `wrap` or `nowrap` explicitly. (#4791)
 

man/man1/fzf.1

@@ -1500,6 +1500,10 @@ fzf exports the following environment variables to its child processes.
 .br
 .BR FZF_KEY "             The name of the last key pressed"
 .br
+.BR FZF_IDLE_TIME "       Whole seconds since the last user activity"
+.br
+.BR FZF_IDLE_TIME_MS "    Milliseconds since the last user activity"
+.br
 .BR FZF_PORT "            Port number when \-\-listen option is used"
 .br
 .BR FZF_SOCK "            Unix socket path when \-\-listen option is used"
@@ -1939,6 +1943,30 @@ variables starting from 1. It optionally sets \fBFZF_CLICK_FOOTER_WORD\fR
 if clicked on a word.
 .RE
 
+\fIevery(N)\fR
+.RS
+Triggered every \fIN\fR seconds (\fIN\fR can be a fractional number, e.g.
+\fB0.5\fR). The minimum interval is \fB0.01\fR seconds; values are floored
+to that.
+
+Combine with the \fBFZF_IDLE_TIME\fR (whole seconds) and
+\fBFZF_IDLE_TIME_MS\fR (milliseconds) environment variables to build
+idle\-based behavior without a separate event.
+
+e.g.
+     \fB# Live process list, refreshed every 2 seconds.
+     # --track --id-nth 2 keeps the cursor on the same PID across reloads.
+     fzf \-\-header\-lines 1 \-\-track \-\-id\-nth 2 \\
+         \-\-bind 'start,every(2):reload\-sync:ps \-ef'
+
+     # Auto\-accept after 10 seconds of inactivity, with a countdown in the footer after 5s.
+     fzf \-\-bind 'every(1):bg\-transform:
+       if   [[ $FZF_IDLE_TIME \-lt 5  ]]; then echo change\-footer:
+       elif [[ $FZF_IDLE_TIME \-lt 10 ]]; then echo "change\-footer:auto\-accept in $((10 \- FZF_IDLE_TIME))s"
+       else echo accept
+       fi'\fR
+.RE
+
 .SS AVAILABLE ACTIONS:
 A key or an event can be bound to one or more of the following actions.
 

src/options.go

@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"maps"
+	"math"
 	"os"
 	"regexp"
 	"strconv"
@@ -1257,7 +1258,14 @@ func parseKeyChords(str string, message string) (map[tui.Event]string, []tui.Eve
 			add(tui.F12)
 		default:
 			runes := []rune(key)
-			if len(key) == 10 && strings.HasPrefix(lkey, "ctrl-alt-") && isAlphabet(lkey[9]) {
+			if strings.HasPrefix(lkey, "every(") && strings.HasSuffix(lkey, ")") {
+				evt, err := parseEveryEvent(key[6 : len(key)-1])
+				if err != nil {
+					return nil, list, err
+				}
+				chords[evt] = key
+				list = append(list, evt)
+			} else if len(key) == 10 && strings.HasPrefix(lkey, "ctrl-alt-") && isAlphabet(lkey[9]) {
 				r := rune(lkey[9])
 				evt := tui.CtrlAltKey(r)
 				if r == 'h' && !util.IsWindows() {
@@ -1299,6 +1307,21 @@ func parseKeyChords(str string, message string) (map[tui.Event]string, []tui.Eve
 	return chords, list, nil
 }
 
+func parseEveryEvent(arg string) (tui.Event, error) {
+	secs, err := strconv.ParseFloat(strings.TrimSpace(arg), 64)
+	if err != nil || math.IsNaN(secs) || math.IsInf(secs, 0) || secs <= 0 {
+		return tui.Event{}, errors.New("every() requires a positive number of seconds")
+	}
+	if secs < 0.01 {
+		secs = 0.01
+	}
+	ms := math.Round(secs * 1000)
+	if ms > math.MaxInt32 {
+		return tui.Event{}, errors.New("every() interval is too large")
+	}
+	return tui.Event{Type: tui.Every, Char: rune(int32(ms))}, nil
+}
+
 func parseScheme(str string) (string, []criterion, error) {
 	str = strings.ToLower(str)
 	switch str {

src/options_test.go

@@ -299,6 +299,39 @@ func TestBind(t *testing.T) {
 	check(tui.F1.AsEvent(), "", actAbort)
 }
 
+func TestParseEveryEvent(t *testing.T) {
+	pairs, _, err := parseKeyChords("every(2),every(0.5)", "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if len(pairs) != 2 {
+		t.Errorf("expected 2 distinct every events, got %d", len(pairs))
+	}
+	if pairs[(tui.Event{Type: tui.Every, Char: 2000})] != "every(2)" {
+		t.Errorf("every(2) not registered")
+	}
+	if pairs[(tui.Event{Type: tui.Every, Char: 500})] != "every(0.5)" {
+		t.Errorf("every(0.5) not registered")
+	}
+
+	// Floor at 0.01s -> 10ms
+	pairs, _, err = parseKeyChords("every(0.001)", "")
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if pairs[(tui.Event{Type: tui.Every, Char: 10})] != "every(0.001)" {
+		t.Errorf("every(0.001) should floor to 10ms")
+	}
+
+	// Reject zero, negatives, and overflow (>= 2^31 ms = ~24.85 days)
+	for _, bad := range []string{"every(0)", "every(-1)", "every(abc)", "every()", "every(2147484)"} {
+		if _, _, err := parseKeyChords(bad, ""); err == nil {
+			t.Errorf("%s should be rejected", bad)
+		}
+	}
+
+}
+
 func TestColorSpec(t *testing.T) {
 	var base *tui.ColorTheme
 	theme := tui.Dark256

src/terminal.go

@@ -436,6 +436,7 @@ type Terminal struct {
 	bgSemaphores         map[action]chan struct{}
 	keyChan              chan tui.Event
 	eventChan            chan tui.Event
+	timerChan            chan tui.Event
 	slab                 *util.Slab
 	theme                *tui.ColorTheme
 	tui                  tui.Renderer
@@ -456,6 +457,7 @@ type Terminal struct {
 	proxyScript          string
 	numLinesCache        map[int32]numLinesCacheValue
 	raw                  bool
+	lastActivity         time.Time
 }
 
 type numLinesCacheValue struct {
@@ -1151,13 +1153,15 @@ func NewTerminal(opts *Options, eventBox *util.EventBox, executor *util.Executor
 		bgSemaphores:       make(map[action]chan struct{}),
 		keyChan:            make(chan tui.Event),
 		eventChan:          make(chan tui.Event, 6), // start | (load + result + zero|one) | (focus) | (resize)
+		timerChan:          make(chan tui.Event),    // unbuffered: every() ticks coalesce when main loop is busy
 		tui:                renderer,
 		ttyDefault:         opts.TtyDefault,
 		ttyin:              ttyin,
 		initFunc:           func() error { return renderer.Init() },
 		executing:          util.NewAtomicBool(false),
 		lastAction:         actStart,
 		lastFocus:          minItem.Index(),
+		lastActivity:       time.Now(),
 		numLinesCache:      make(map[int32]numLinesCacheValue)}
 	if opts.AcceptNth != nil {
 		t.acceptNth = opts.AcceptNth(t.delimiter)
@@ -1385,6 +1389,9 @@ func (t *Terminal) environImpl(forPreview bool) []string {
 	env = append(env, "FZF_QUERY="+string(t.input))
 	env = append(env, "FZF_ACTION="+t.lastAction.Name())
 	env = append(env, "FZF_KEY="+t.lastKey)
+	idleMs := time.Since(t.lastActivity).Milliseconds()
+	env = append(env, fmt.Sprintf("FZF_IDLE_TIME=%d", idleMs/1000))
+	env = append(env, fmt.Sprintf("FZF_IDLE_TIME_MS=%d", idleMs))
 	env = append(env, "FZF_PROMPT="+string(t.promptString))
 	env = append(env, "FZF_GHOST="+string(t.ghost))
 	env = append(env, "FZF_POINTER="+string(t.pointer))
@@ -5807,6 +5814,35 @@ func (t *Terminal) addClickFooterWord(env []string) []string {
 	return env
 }
 
+// startTimers spawns a goroutine per every() bind event. Forwarding ticks
+// onto the unbuffered timerChan lets the ticker drop overlapping ticks
+// while the main loop is busy.
+func (t *Terminal) startTimers(ctx context.Context) {
+	for evt := range t.keymap {
+		switch evt.Type {
+		case tui.Every:
+			d := time.Duration(evt.Char) * time.Millisecond
+			evt := evt
+			go func() {
+				ticker := time.NewTicker(d)
+				defer ticker.Stop()
+				for {
+					select {
+					case <-ctx.Done():
+						return
+					case <-ticker.C:
+						select {
+						case <-ctx.Done():
+							return
+						case t.timerChan <- evt:
+						}
+					}
+				}
+			}()
+		}
+	}
+}
+
 // Loop is called to start Terminal I/O
 func (t *Terminal) Loop() error {
 	// prof := profile.Start(profile.ProfilePath("/tmp/"))
@@ -6314,6 +6350,7 @@ func (t *Terminal) Loop() error {
 			}
 		}
 	}()
+	t.startTimers(ctx)
 	previewDraggingPos := -1
 	barDragging := false
 	pbarDragging := false
@@ -6373,6 +6410,7 @@ func (t *Terminal) Loop() error {
 		select {
 		case event = <-t.keyChan:
 			needBarrier = true
+		case event = <-t.timerChan:
 		case event = <-t.eventChan:
 			// Drain channel to process all queued events at once without rendering
 			// the intermediate states
@@ -6437,7 +6475,10 @@ func (t *Terminal) Loop() error {
 		previousInput := t.input
 		previousCx := t.cx
 		previousVersion := t.version
-		t.lastKey = event.KeyName()
+		if event.Type < tui.Invalid {
+			t.lastKey = event.KeyName()
+			t.lastActivity = time.Now()
+		}
 		updatePreviewWindow := func(forcePreview bool) {
 			t.resizeWindows(forcePreview, false)
 			req(reqPrompt, reqList, reqInfo, reqHeader, reqFooter)

src/tui/eventtype_string.go

@@ -196,11 +196,6 @@ const (
 	CtrlAltShiftPageUp
 	CtrlAltShiftPageDown
 
-	Invalid
-	Fatal
-	BracketedPasteBegin
-	BracketedPasteEnd
-
 	Mouse
 	DoubleClick
 	LeftClick
@@ -214,7 +209,15 @@ const (
 	PreviewScrollUp
 	PreviewScrollDown
 
-	// Events
+	// Synthetic / non-user events. Everything from Invalid onward is
+	// either internally generated or a state-change notification, not
+	// direct user input. Use `>= Invalid` to gate activity tracking.
+	// BracketedPasteBegin/End sit here too: they enclose user input
+	// (which arrives as Rune events) and should not appear in FZF_KEY.
+	Invalid
+	Fatal
+	BracketedPasteBegin
+	BracketedPasteEnd
 	Resize
 	Change
 	BackwardEOF
@@ -229,6 +232,7 @@ const (
 	ClickHeader
 	ClickFooter
 	Multi
+	Every
 )
 
 func (t EventType) AsEvent() Event {