Show the progress rate over the last 5 seconds, and where a phase waits after 10 seconds with no item done (closes #125)

The rate was the phase's average, so a burst after a long wait read as
over 1,000 files a second. It now covers the items completed over the
last 5 seconds, or since the line before off a terminal; the ETA still
comes from the average. Once no item has completed for 10 seconds, the
rate gives way to "stalled" and where the phase waits, as "stalled
disk/db": disk, db, out (stdout) or cpu, or two of them. A line too
wide for the terminal loses its bar first, then its rate or those
words, so the phase, progress, elapsed time and ETA stay whole. The
content phase's last partial batch is now written under a display of
its own. The tests set the display's clock by hand.

Deviation: the stall words hold no time and name where the phase waits, not what it does.
Judgement call: trees' group phase, which works in memory, says "cpu".

Model: opus-5-5

README.md

@@ -799,7 +799,8 @@ A scan has five phases (`[1/5] load`, `[2/5] walk`, `[3/5] hash`,
   `head`, and `tail`, without fetching the records. It then says it is searching
   the database until SQLite returns the first record; the checks, and their rate
   and ETA, start there. The files to read then get a display of their own, with
-  their count as its total.
+  their count as its total, and so does the writing of the last of their records
+  to the database, with the count of those records as its total.
 
 `trees` has four phases (`[1/4] open`, `[2/4] read`, `[3/4] group`,
 `[4/4] write`, see "`trees` mode"):
@@ -837,7 +838,7 @@ Each display is one line holding:
   or, when stderr is not a terminal, since the line before, so it falls to 0
   while nothing completes, and a burst of items after a wait shows as a burst
   rather than as a steady rate. Once no item has completed for 10 seconds, the
-  word `stalled` and what the phase is doing take the rate's place (see below).
+  word `stalled` and where the phase waits take the rate's place (see below).
 - elapsed time
 - estimated time remaining, or `unknown`. It comes from the phase's average rate
   since it started counting, so that it does not swing with each burst.
@@ -847,18 +848,20 @@ Example shape (exact layout is flexible, content is not):
 ```
 [3/5] hash: [12345/98765] 12% |████      | 92 files/s elapsed 2:32 eta 17:54
 [2/5] walk: [1234567/~1200000] 103%, 5120 files/s, elapsed 4m1s, eta unknown
-[3/5] hash: [12345/45678] 27%, stalled reading, elapsed 4m30s, eta 12m9s
+[3/5] hash: [12345/45678] 27%, stalled disk/db, elapsed 4m30s, eta 12m9s
 ```
 
 When no item has completed for 10 seconds, as while one large file is read, a
-disk is slow or the database is busy, the line says `stalled` and what the phase
-is doing in place of the rate, which would read 0: `walk` is `listing`
-directories; `hash` and the content phase's reads are `reading` files; `update`
-is `writing` to the database; `load` and the `read` phase of `trees` are
-`reading` the database; the content phase's checks are `searching` the database;
-`trees`' `group` is `grouping` directories, and its `write` is `writing` the
-report. The `read` phase of `report` writes the report while it reads the
-records and may be waiting on either, so it says `read/write`. A phase still
+disk is slow or the database is busy, the line says `stalled` and where the
+phase waits in place of the rate, which would read 0: `disk` for files, `db` for
+the database, `out` for stdout, and two of them, as `disk/db`, for a phase that
+may wait on either. `walk` says `disk`. `hash` and the content phase's reads say
+`disk/db`, as they read files and write their records to the database between
+them, and so do the content phase's checks, which `lstat` each record's file as
+the database search returns it. `load`, `update`, the content phase's last write
+and the `read` phase of `trees` say `db`. `trees`' `write` says `out`, and its
+`group`, which works in memory, says `cpu`. The `read` phase of `report` writes
+the report while it reads the records, so it says `db/out`. A phase still
 waiting for its total already says what it waits for, and says nothing more.
 
 Additional requirements:
@@ -872,18 +875,18 @@ Additional requirements:
   times a second, so its elapsed time keeps moving while a phase waits for its
   next item.
 - On a terminal no line reaches the terminal's last column, however narrow the
-  terminal is. The phase and its place, the progress, what a stalled phase is
-  doing, the elapsed time and the ETA are kept whole: a line too wide for the
-  terminal leaves out its rate (or what the phase is waiting for), and a bar
-  with no room beside the parts kept whole gives way to the spinner. The words a
-  stalled phase shows are short, so that a line like the stalled one in the
-  example above, with tens of thousands of files and times in minutes, fits on
-  an 80-column terminal. Only when the parts kept whole are too wide, as on a
-  terminal narrower than about 70 columns hours into a scan of millions of
-  files, or about 90 once the phase has stalled, is the line cut short at the
-  terminal's edge, so the end of the ETA is lost first. A terminal made narrower
-  while a phase runs gets the same: the next draw erases the line within the new
-  width and fits the line to it, and the display goes on redrawing in place.
+  terminal is. A line too wide for the terminal first loses its bar, which gives
+  way to the spinner, then its rate, the words of a stalled phase, or what the
+  phase is waiting for. The phase and its place, the progress, the elapsed time
+  and the ETA are kept whole. On an 80-column terminal, a stalled line at counts
+  and times like those of the stalled line in the example above keeps its words
+  whole in every phase; where the words and the ETA do not both fit, as at
+  millions of files and times in hours, the words give way. Only when those four
+  alone are too wide, as on a terminal narrower than about 70 columns hours into
+  a scan of millions of files, is the line cut short at the terminal's edge, so
+  the end of the ETA is lost first. A terminal made narrower while a phase runs
+  gets the same: the next draw erases the line within the new width and fits the
+  line to it, and the display goes on redrawing in place.
 - When stderr is not a terminal (a pipe, a file, `/dev/null`), do not emit ANSI
   redraws: print the line the moment each phase starts, every 5 seconds while it
   runs (whether or not an item has completed, and never more often), and once

TODO.md

@@ -34,12 +34,14 @@
   to 0 while nothing completes, and a burst after a wait no longer reads as a
   steady rate of over 1,000 files a second; the ETA still comes from the phase's
   average. Once no item has completed for 10 seconds, the word `stalled` and
-  what the phase is doing take the rate's place, as `stalled reading`, each
-  phase naming its own work where it is defined; `report`'s `read` says
-  `read/write`, as it writes the report while it reads. Those words are kept
-  whole with the phase, progress, elapsed time and ETA, so only the bar gives
-  way before them, and they fit on an 80-column terminal in an ordinary scan
-  (2026-10-16, https://git.eeqj.de/sneak/sfdupes/issues/125)
+  where the phase waits take the rate's place, as `stalled disk/db`: `disk`,
+  `db`, `out` for stdout or `cpu`, or two of them for a phase that may wait on
+  either, each phase giving its word where it is defined. A line too wide for
+  the terminal loses its bar first, then its rate or those words, so the phase,
+  progress, elapsed time and ETA stay whole; on an 80-column terminal the words
+  fit beside them in an ordinary scan. The content phase's last partial batch is
+  now written under a display of its own (2026-10-16,
+  https://git.eeqj.de/sneak/sfdupes/issues/125)
 
 - new subcommand `info` prints the database's details on stdout, one per line as
   a name, a tab and the value: its path and where it came from, the sizes of the

progress.go

@@ -28,7 +28,7 @@ const redrawInterval = 100 * time.Millisecond
 const rateWindow = 5 * time.Second
 
 // stallTime is how long a phase goes with no item completed before its
-// line says it has stalled, and what it is doing, in place of the rate.
+// line says it has stalled, and where it waits, in place of the rate.
 const stallTime = 10 * time.Second
 
 // spinnerType selects the progressbar library's spinner style.
@@ -68,10 +68,6 @@ const (
 	openingDatabase = "opening the database"
 )
 
-// reading is what the display of a phase that reads files or records
-// says it is doing once it has stalled; see stallTime.
-const reading = "reading"
-
 // stderrIsTTY reports whether stderr is attached to a terminal.
 func stderrIsTTY() bool {
 	return term.IsTerminal(int(os.Stderr.Fd()))
@@ -102,7 +98,7 @@ type progressParams struct {
 	total      int64  // the items the phase will complete; -1 when not known
 	estimate   bool   // total is an estimate, which the count may pass
 	waitingFor string // what the phase waits for until setTotal is called
-	doing      string // what the phase is doing, as "reading"; see stallTime
+	stalledOn  string // where the phase waits, as "disk/db"; see stallTime
 }
 
 // drawnCount is the count of items completed as of one draw, and when
@@ -142,7 +138,7 @@ type progress struct {
 	total      int64
 	estimate   bool
 	waitingFor string
-	doing      string
+	stalledOn  string
 	count      int64
 	start      time.Time // when the phase started, for the elapsed time
 	rateStart  time.Time // when the count started, for the ETA
@@ -176,7 +172,7 @@ func startProgress(params progressParams, width func() int,
 		stop: make(chan struct{}), done: make(chan struct{}),
 		label: params.label, unit: params.unit, total: params.total,
 		estimate: params.estimate, waitingFor: params.waitingFor,
-		doing: params.doing, start: start, rateStart: start,
+		stalledOn: params.stalledOn, start: start, rateStart: start,
 		lastItem: start, drawn: []drawnCount{{at: start}},
 	}
 
@@ -219,26 +215,27 @@ func (p *progress) draw() {
 	}
 
 	if p.width == nil {
-		text, _ := p.line(now, math.MaxInt, true)
-		fmt.Fprintln(os.Stderr, text)
+		fmt.Fprintln(os.Stderr, p.line(now, math.MaxInt, true))
 
 		return
 	}
 
 	width := p.width()
 
-	// A phase with an exact total gets the library's bar when its line,
-	// without the percent the bar shows, fits whole beside the bar. A
-	// total of 0 leaves the bar nothing to fill.
+	// A phase with an exact total gets the library's bar when its whole
+	// line, without the percent the bar shows, fits beside the bar: the
+	// bar gives way before any part of the line. A total of 0 leaves the
+	// bar nothing to fill.
 	text, withBar := "", false
 	if p.total > 0 && !p.estimate {
-		text, withBar = p.line(now, width-barMargin, false)
+		text = p.line(now, math.MaxInt, false)
+		withBar = len(text) <= width-barMargin
 	}
 
 	margin := barMargin
 	if !withBar {
 		margin = spinnerMargin
-		text, _ = p.line(now, width-margin, true)
+		text = p.line(now, width-margin, true)
 	}
 
 	// The library makes a bar or a spinner, and before each draw erases
@@ -449,17 +446,14 @@ func (p *progress) finish() {
 // rate is that since the first draw in drawn, and the ETA comes from
 // the rate since the count started. Once no item has been completed for
 // stallTime, the rate, which would read 0, gives way to the word
-// "stalled" and what the phase is doing, as "stalled reading".
+// "stalled" and where the phase waits, as "stalled disk/db".
 //
-// The phase and its place, the progress, what a stalled phase is doing,
-// the elapsed time and the ETA are kept whole. A line wider than room
-// leaves out the rate, or what the phase waits for; only if it is still
-// wider is it cut at room, and line reports that it does not fit. Every
-// part is ASCII, so its length is its width in columns. p.mu must be
-// held.
-func (p *progress) line(now time.Time, room int,
-	percent bool,
-) (string, bool) {
+// The phase and its place, the progress, the elapsed time and the ETA
+// are kept whole. A line wider than room leaves out the rate, the words
+// of a stalled phase, or what the phase waits for; only if it is still
+// wider is it cut at room. Every part is ASCII, so its length is its
+// width in columns. p.mu must be held.
+func (p *progress) line(now time.Time, room int, percent bool) string {
 	elapsed := now.Sub(p.start).Round(time.Second)
 
 	// head and tail hold the parts kept whole; extra, between them, is
@@ -479,8 +473,7 @@ func (p *progress) line(now time.Time, room int,
 		tail = fmt.Sprintf("elapsed %s, eta %s", elapsed, p.eta(average))
 
 		if now.Sub(p.lastItem) >= stallTime {
-			head += "stalled " + p.doing + ", "
-			extra = ""
+			extra = "stalled " + p.stalledOn + ", "
 		}
 	}
 
@@ -488,12 +481,12 @@ func (p *progress) line(now time.Time, room int,
 
 	switch {
 	case len(full) <= room:
-		return full, true
+		return full
 	case len(kept) <= room:
-		return kept, true
+		return kept
 	}
 
-	return kept[:max(room, 0)], false
+	return kept[:max(room, 0)]
 }
 
 // perSecond returns count items over d as items a second, or 0 when no

progress_test.go

@@ -22,6 +22,10 @@ const testRedraw = time.Millisecond
 // it expects.
 const testDeadline = 5 * time.Second
 
+// hashStalledOn is where the hash phase says it waits once it has
+// stalled, as readRuns gives it.
+const hashStalledOn = "disk/db"
+
 // testClock is a clock a test moves by hand, for a display that reads
 // it from its own goroutine too.
 type testClock struct {
@@ -159,7 +163,7 @@ func TestProgressLine(t *testing.T) {
 		tc.p.start, tc.p.rateStart, tc.p.lastItem = ago, ago, now
 		tc.p.drawn = []drawnCount{{at: ago}}
 
-		if got, _ := tc.p.line(now, math.MaxInt, true); got != tc.want {
+		if got := tc.p.line(now, math.MaxInt, true); got != tc.want {
 			t.Errorf("line = %q, want %q", got, tc.want)
 		}
 	}
@@ -167,9 +171,9 @@ func TestProgressLine(t *testing.T) {
 
 // TestLineFitsRoom checks how a line is fitted to the room it has, ten
 // seconds into the phase, and fifty into a phase with no file read for
-// the last 42: it leaves out the rate, or what the phase waits for, but
-// not what a stalled phase is doing, and is cut only when what is left
-// is still too wide.
+// the last 42: it leaves out the rate, what the phase waits for, or the
+// words of a stalled phase, and is cut only when what is left is still
+// too wide.
 func TestLineFitsRoom(t *testing.T) {
 	t.Parallel()
 
@@ -188,7 +192,7 @@ func TestLineFitsRoom(t *testing.T) {
 	started := now.Add(-50 * time.Second)
 	stalled := &progress{
 		label: scanPhase("hash"), unit: scanUnit, total: 100, count: 20,
-		doing: reading, start: started, rateStart: started,
+		stalledOn: hashStalledOn, start: started, rateStart: started,
 		lastItem: now.Add(-42 * time.Second),
 		drawn:    []drawnCount{{at: now.Add(-rateWindow), count: 20}},
 	}
@@ -198,52 +202,44 @@ func TestLineFitsRoom(t *testing.T) {
 		room    int
 		percent bool
 		want    string
-		fits    bool
 	}{{
 		p: hash, room: 57, percent: true,
 		want: "[3/5] hash: [20/100] 20%, 2 files/s, elapsed 10s, eta 40s",
-		fits: true,
 	}, {
 		p: hash, room: 56, percent: true,
 		want: "[3/5] hash: [20/100] 20%, elapsed 10s, eta 40s",
-		fits: true,
 	}, {
 		p: hash, room: 45, percent: true,
 		want: "[3/5] hash: [20/100] 20%, elapsed 10s, eta 40",
-		fits: false,
 	}, {
 		// Before the library's bar, which shows the percent.
 		p: hash, room: 57, percent: false,
 		want: "[3/5] hash: [20/100], 2 files/s, elapsed 10s, eta 40s",
-		fits: true,
 	}, {
 		p: content, room: 40, percent: true,
 		want: "[5/5] content: elapsed 10s, eta unknown",
-		fits: true,
 	}, {
 		p: stalled, room: 65, percent: true,
-		want: "[3/5] hash: [20/100] 20%, stalled reading, elapsed 50s, " +
+		want: "[3/5] hash: [20/100] 20%, stalled disk/db, elapsed 50s, " +
 			"eta 3m20s",
-		fits: true,
 	}, {
 		p: stalled, room: 64, percent: true,
-		want: "[3/5] hash: [20/100] 20%, stalled reading, elapsed 50s, " +
-			"eta 3m20",
-		fits: false,
+		want: "[3/5] hash: [20/100] 20%, elapsed 50s, eta 3m20s",
 	}}
 
 	for _, tc := range cases {
-		got, fits := tc.p.line(now, tc.room, tc.percent)
-		if got != tc.want || fits != tc.fits {
-			t.Errorf("line(%d, %t) = %q, %t, want %q, %t",
-				tc.room, tc.percent, got, fits, tc.want, tc.fits)
+		if got := tc.p.line(now, tc.room, tc.percent); got != tc.want {
+			t.Errorf("line(%d, %t) = %q, want %q",
+				tc.room, tc.percent, got, tc.want)
 		}
 	}
 }
 
 // TestSetTotalStartsRate checks that setTotal starts a phase's rate,
 // its ETA and its time with no record read from when the total becomes
-// known, not from when the phase started waiting for it.
+// known, not from when the phase started waiting for it: after 20
+// seconds of waiting for the total, the phase has not stalled 5 seconds
+// after it, and has 10 seconds after it with no record read.
 func TestSetTotalStartsRate(t *testing.T) {
 	t.Parallel()
 
@@ -251,28 +247,33 @@ func TestSetTotalStartsRate(t *testing.T) {
 	waited := clock.Now().Add(-20 * time.Second)
 	p := &progress{
 		now: clock.Now, label: scanPhase("load"), unit: scanUnit, total: -1,
-		doing: reading, start: waited, rateStart: waited,
+		stalledOn: "db", start: waited, rateStart: waited,
 		lastItem: waited, drawn: []drawnCount{{at: waited}},
 	}
 
 	p.setTotal(100)
 
-	// Ten seconds after the total came, no record has been read yet.
-	clock.Add(10 * time.Second)
+	clock.Add(5 * time.Second)
 
-	want := "[1/5] load: [0/100] 0%, stalled reading, elapsed 30s, " +
-		"eta unknown"
-	if got, _ := p.line(clock.Now(), math.MaxInt, true); got != want {
+	want := "[1/5] load: [0/100] 0%, 0 files/s, elapsed 25s, eta unknown"
+	if got := p.line(clock.Now(), math.MaxInt, true); got != want {
 		t.Errorf("line = %q, want %q", got, want)
 	}
 
-	// Then 20 are.
+	clock.Add(5 * time.Second)
+
+	want = "[1/5] load: [0/100] 0%, stalled db, elapsed 30s, eta unknown"
+	if got := p.line(clock.Now(), math.MaxInt, true); got != want {
+		t.Errorf("line = %q, want %q", got, want)
+	}
+
+	// Then 20 records are read.
 	for range 20 {
 		p.increment()
 	}
 
 	want = "[1/5] load: [20/100] 20%, 2 files/s, elapsed 30s, eta 40s"
-	if got, _ := p.line(clock.Now(), math.MaxInt, true); got != want {
+	if got := p.line(clock.Now(), math.MaxInt, true); got != want {
 		t.Errorf("line = %q, want %q", got, want)
 	}
 }
@@ -343,8 +344,8 @@ func TestPlainProgressPrintsWhileWaiting(t *testing.T) {
 // coming, as when one large file is being read or a disk is slow, goes
 // on printing its line every interval: the rate falls to 0 once no file
 // has been read for rateWindow, and once none has for stallTime the
-// line says the phase has stalled, and what it is doing, in place of
-// the rate. The test moves the display's clock by hand.
+// line says the phase has stalled, and where it waits, in place of the
+// rate. The test moves the display's clock by hand.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestPlainProgressStalledProducer(t *testing.T) {
@@ -352,7 +353,7 @@ func TestPlainProgressStalledProducer(t *testing.T) {
 	clock := &testClock{now: time.Now()}
 	p := startProgress(progressParams{
 		label: scanPhase("hash"), unit: scanUnit, total: 100,
-		doing: reading,
+		stalledOn: hashStalledOn,
 	}, nil, testRedraw, clock.Now)
 
 	// Pass or fail, the display ends before stderr is put back.
@@ -373,7 +374,7 @@ func TestPlainProgressStalledProducer(t *testing.T) {
 
 	clock.Add(4 * time.Second)
 	awaitOutput(t, stderr,
-		"[3/5] hash: [20/100] 20%, stalled reading, elapsed 10s, eta 40s\n",
+		"[3/5] hash: [20/100] 20%, stalled disk/db, elapsed 10s, eta 40s\n",
 		3)
 }
 
@@ -391,7 +392,7 @@ func TestPlainProgressRateAfterStall(t *testing.T) {
 	// No timed draws: the test draws.
 	p := startProgress(progressParams{
 		label: scanPhase("hash"), unit: scanUnit, total: 1000,
-		doing: reading,
+		stalledOn: hashStalledOn,
 	}, nil, time.Hour, clock.Now)
 
 	late := plainInterval + time.Millisecond
@@ -411,7 +412,7 @@ func TestPlainProgressRateAfterStall(t *testing.T) {
 	want := []string{
 		"[3/5] hash: [0/1000] 0%, 0 files/s, elapsed 0s, eta unknown",
 		"[3/5] hash: [0/1000] 0%, 0 files/s, elapsed 5s, eta unknown",
-		"[3/5] hash: [0/1000] 0%, stalled reading, elapsed 10s, eta unknown",
+		"[3/5] hash: [0/1000] 0%, stalled disk/db, elapsed 10s, eta unknown",
 		"[3/5] hash: [100/1000] 10%, 20 files/s, elapsed 15s, eta 2m15s",
 	}
 
@@ -436,7 +437,7 @@ func TestProgressRateAfterStallRedrawn(t *testing.T) {
 	// No timed draws: the test draws.
 	p := startProgress(progressParams{
 		label: scanPhase("hash"), unit: scanUnit, total: 1000,
-		doing: reading,
+		stalledOn: hashStalledOn,
 	}, nil, time.Hour, clock.Now)
 
 	// redraw draws the display every redrawInterval for d.
@@ -599,56 +600,81 @@ func TestTerminalLinesKeepETA(t *testing.T) {
 	}
 }
 
-// TestTerminalStalledLineKeepsWords draws a stalled phase on an
-// 80-column terminal at an ordinary scan's counts and times, 12345 of
-// 45678 files read four and a half minutes in, the last 42 seconds ago,
-// and report's read phase at the same counts: the bar gives way, and
-// what the phase is doing shows whole in place of the rate, beside the
-// phase, progress, elapsed time and ETA.
+// TestTerminalStalledLines draws every phase's line on an 80-column
+// terminal once the phase has stalled, its last item done 42 seconds
+// before. At an ordinary scan's counts and times, 12345 of 45678 items
+// done four and a half minutes in, the line shows where the phase waits
+// whole, beside the phase, progress, elapsed time and ETA. At a large
+// scan's, 1234567 of 9876543 two and a half hours in, those four still
+// show whole, as the words give way first where they do not fit.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
-func TestTerminalStalledLineKeepsWords(t *testing.T) {
+func TestTerminalStalledLines(t *testing.T) {
 	stderr := captureStderr(t)
 
-	cases := []struct {
-		params progressParams
-		want   string
-	}{{
-		params: progressParams{
-			label: scanPhase("hash"), unit: scanUnit, total: 45678,
-			doing: reading,
-		},
-		want: "[3/5] hash: [12345/45678] 27%, stalled reading, " +
-			"elapsed 4m30s, eta 12m9s",
-	}, {
-		params: progressParams{
-			label: reportPhase("read"), total: 45678, doing: "read/write",
-		},
-		want: "[2/2] read: [12345/45678] 27%, stalled read/write, " +
-			"elapsed 4m30s, eta 12m9s",
-	}}
-
-	for _, tc := range cases {
+	// drawStalled draws the display params describes as it starts and
+	// once more as it ends, with count of total items done elapsed into
+	// the phase, and returns what the terminal shows.
+	drawStalled := func(params progressParams, total, count int64,
+		elapsed time.Duration,
+	) string {
 		before := len(stderr())
 		clock := &testClock{now: time.Now()}
+		params.total = total
 
-		// No timed draws: the display is drawn as it starts and as it
-		// ends.
-		p := startProgress(tc.params, func() int { return 80 }, time.Hour,
+		// No timed draws come between the two.
+		p := startProgress(params, func() int { return 80 }, time.Hour,
 			clock.Now)
 
-		clock.Add(4*time.Minute + 30*time.Second - 42*time.Second)
+		clock.Add(elapsed - 42*time.Second)
 
 		p.mu.Lock()
-		p.count, p.lastItem = 12345, clock.Now()
+		p.count, p.lastItem = count, clock.Now()
 		p.mu.Unlock()
 
 		clock.Add(42 * time.Second)
 		p.finish()
 
-		shown := lastFrame(stderr()[before:])
-		if !strings.Contains(shown, tc.want) {
-			t.Errorf("terminal shows %q, want %q", shown, tc.want)
+		return lastFrame(stderr()[before:])
+	}
+
+	phases := []progressParams{
+		{label: scanPhase("load"), stalledOn: "db"},
+		{label: scanPhase("walk"), estimate: true, stalledOn: "disk"},
+		{label: scanPhase("hash"), stalledOn: hashStalledOn},
+		{label: scanPhase("update"), stalledOn: "db"},
+		// The content phase's checks and reads, then its last write.
+		{label: scanPhase("content"), stalledOn: "disk/db"},
+		{label: scanPhase("content"), stalledOn: "db"},
+		{label: treesPhase("read"), stalledOn: "db"},
+		{label: treesPhase("group"), stalledOn: "cpu"},
+		{label: treesPhase("write"), stalledOn: "out"},
+		{label: reportPhase("read"), stalledOn: "db/out"},
+	}
+
+	for _, params := range phases {
+		approx := ""
+		if params.estimate {
+			approx = "~"
+		}
+
+		shown := drawStalled(params, 45678, 12345,
+			4*time.Minute+30*time.Second)
+		want := params.label + ": [12345/" + approx + "45678] 27%, stalled " +
+			params.stalledOn + ", elapsed 4m30s, eta 12m9s"
+
+		if !strings.Contains(shown, want) {
+			t.Errorf("terminal shows %q, want %q", shown, want)
+		}
+
+		shown = drawStalled(params, 9876543, 1234567, 150*time.Minute)
+		for _, want := range []string{
+			params.label + ": [1234567/" + approx + "9876543] 12%, ",
+			", elapsed 2h30m0s, eta 17h30m0s",
+		} {
+			if !strings.Contains(shown, want) {
+				t.Errorf("terminal shows %q, want %q", shown, want)
+			}
 		}
 	}
 }
@@ -695,7 +721,7 @@ func TestTerminalLinesFitWidth(t *testing.T) {
 // times. Nothing written after that, the erase before each redraw
 // included, may reach the narrower terminal's last column: it would
 // wrap, and every redraw would leave a line behind. At these widths the
-// spinner stays a spinner and the bar stays a bar.
+// spinner stays a spinner and the bar gives way to the spinner.
 //
 //nolint:paralleltest // captureStderr replaces the process-wide os.Stderr
 func TestTerminalNarrowedRedrawsInPlace(t *testing.T) {

report.go

@@ -74,11 +74,11 @@ func runReport(ctx context.Context, stdout io.Writer) error {
 
 	defer func() { _ = db.Close() }()
 
-	// The read phase writes the report while it reads the records, so a
-	// stall may be in either.
+	// The read phase writes the report to stdout while it reads the
+	// records, so it may wait on either.
 	prog = newProgress(progressParams{
 		label: reportPhase("read"), unit: "records", total: -1,
-		waitingFor: countingRecords, doing: "read/write",
+		waitingFor: countingRecords, stalledOn: "db/out",
 	})
 	report, err := readReport(ctx, db, dbPath, stdout, prog)
 

scan.go

@@ -446,7 +446,7 @@ func (s *scanState) loadIndex(ctx context.Context, roots []string) error {
 	// first gives the display its total.
 	prog := newProgress(progressParams{
 		label: scanPhase("load"), unit: scanUnit, total: -1,
-		waitingFor: countingRecords, doing: reading,
+		waitingFor: countingRecords, stalledOn: "db",
 	})
 	defer prog.finish()
 
@@ -497,7 +497,7 @@ func (s *scanState) walkPhase(
 
 	prog := newProgress(progressParams{
 		label: scanPhase("walk"), unit: scanUnit, total: estimate,
-		estimate: true, doing: "listing",
+		estimate: true, stalledOn: "disk",
 	})
 
 	var (
@@ -687,9 +687,11 @@ func (s *scanState) readRuns(ctx context.Context, workers int,
 	pool := startHashPool(ctx, runs, workers, hash)
 	defer pool.stop()
 
+	// Between results the phase may wait on a file being read or on a
+	// batch of records being written.
 	prog := newProgress(progressParams{
 		label: scanPhase(label), unit: scanUnit, total: int64(len(runs)),
-		doing: reading,
+		stalledOn: "disk/db",
 	})
 	defer prog.finish()
 
@@ -779,7 +781,7 @@ func (s *scanState) updatePhase(ctx context.Context) error {
 	total := len(s.batch) + len(s.sentinels) + len(deletes)
 	prog := newProgress(progressParams{
 		label: scanPhase("update"), unit: scanUnit, total: int64(total),
-		doing: "writing",
+		stalledOn: "db",
 	})
 
 	defer prog.finish()
@@ -842,7 +844,15 @@ func (s *scanState) contentPhase(ctx context.Context, workers int) error {
 		return err
 	}
 
-	return applyChanges(ctx, s.db, s.batch, nil, nil)
+	// The last partial batch is written under a display of its own, as
+	// the update phase writes the hash phase's.
+	prog := newProgress(progressParams{
+		label: scanPhase("content"), unit: scanUnit,
+		total: int64(len(s.batch)), stalledOn: "db",
+	})
+	defer prog.finish()
+
+	return applyChanges(ctx, s.db, s.batch, nil, prog)
 }
 
 // contentCandidates returns the files the content phase reads, and
@@ -865,10 +875,11 @@ func (s *scanState) contentCandidates(
 	// without a display the scan looks hung before the reads begin.
 	// The display says it is searching until SQLite returns the first
 	// record. The checks start there, against a count of the records
-	// the search returns, and so do their rate and ETA.
+	// the search returns, and so do their rate and ETA. Between records
+	// they may wait on a file's lstat or on the search.
 	prog := newProgress(progressParams{
 		label: scanPhase("content"), unit: scanUnit, total: -1,
-		waitingFor: "searching the database", doing: "searching",
+		waitingFor: "searching the database", stalledOn: "disk/db",
 	})
 	defer prog.finish()
 

trees.go

@@ -72,7 +72,7 @@ func runTrees(ctx context.Context, stdout io.Writer) error {
 
 	prog = newProgress(progressParams{
 		label: treesPhase("read"), unit: "records", total: -1,
-		waitingFor: countingRecords, doing: reading,
+		waitingFor: countingRecords, stalledOn: "db",
 	})
 	records, super, allDirs, err := readTree(ctx, db, prog)
 
@@ -82,9 +82,11 @@ func runTrees(ctx context.Context, stdout io.Writer) error {
 		return fmt.Errorf("database %s: %w", dbPath, err)
 	}
 
+	// Grouping works in memory, so it waits on nothing but the
+	// processor.
 	prog = newProgress(progressParams{
 		label: treesPhase("group"), unit: "directories",
-		total: int64(len(allDirs)), doing: "grouping",
+		total: int64(len(allDirs)), stalledOn: "cpu",
 	})
 	dupes := collectTreeGroups(allDirs, super, prog)
 
@@ -92,7 +94,7 @@ func runTrees(ctx context.Context, stdout io.Writer) error {
 
 	prog = newProgress(progressParams{
 		label: treesPhase("write"), unit: "groups", total: int64(len(dupes)),
-		doing: "writing",
+		stalledOn: "out",
 	})
 	dupeTrees, reclaimable, err := writeTreeGroups(stdout, dupes, prog)