feat(downloads): bound auto-pick by bitrate, and take a good copy

Three faults, one subsystem, and the middle one is why a request that
looked obviously satisfiable came back refused.

**The guardrails were in megabytes, which cannot mean anything.** 300 MB
is a generous FLAC single and a suspiciously small boxset, and whoever
fills the field in has no idea which release the pipeline will apply it
to. `MinKbps`/`MaxKbps`/`PreferredKbps` are the same statement divided
by how long the music is, so one number holds across a nine-minute EP
and a three-hour opera. The runtime comes from `Download.Expected`,
which every anchored request already carries, so this costs no lookup;
the rate is audio bytes over that, falling back to the mean stated
per-file bitrate when the runtime is unknown. Artwork is excluded from
the numerator, or a folder with 30 MB of scans reads as a better rip.

An unknown runtime *passes* the window rather than failing it: the
window is a statement about quality, and refusing everything the moment
MusicBrainz is missing a track length would be a silent embargo.
`MaxFileSizeMB` survives as a separate ceiling, still in megabytes on
purpose -- it is a question about disk space, and it has to apply to a
candidate whose bitrate cannot be worked out at all.

**Auto-pick required daylight over the runner-up**, 0.08 on the
combined score, and so fired hardest in the case it was never written
for: a popular album turns up five *correct* copies, all matching the
tracklist at 95%+ and differing only in format and seeders, their
scores land within a point of each other, and it refused forever on the
grounds that the choice was the user's. It was not. There was no
question about what to fetch, only about which copy -- and abundance is
the condition under which that matters least. A candidate no longer has
to beat the field, only clear the bars on its own terms; where several
do, ranking puts the one closest to the preferred bitrate first.

That tie-break needed the preference to carry weight or it would have
been decorative in a new unit: `BitrateFit` was 0.05 against format's
0.42, so asking for 320 and being handed a FLAC every time was the
designed behaviour. When a preference is set the weights shift to fit
0.40 / format 0.20 / bitrate 0.10, taking it off the two heuristics
that exist as stand-ins for the preference the user has now given.
Health and priority are untouched. And the fit spans 0.5 to 1.0 rather
than 0 to 1, so a preference can promote the copy that matches it and
can never push the others under `minQuality` -- turning "I like 320"
into "never take anything else" silently is what `MinKbps`/`MaxKbps`
are for, out loud.

**And a refusal quoted numbers that passed.** The request list built its
message from `ranked[0]` -- the best candidate *before* the guardrails
and before the lead check -- so a request killed by the size window, or
by having too many good copies, reported "best of 12 found is not a
confident enough match (match 96%, quality 88%)". `AutoPickVeto` names
the gate that actually refused, and `AutoPickable` is that returning
empty.

Existing configs: the old `MinFileSizeMB`/`PreferredFileSizeMB` are not
migrated. A number meaning "300 MB" cannot be reinterpreted as a rate
without knowing the album it was aimed at, so carrying it over would be
inventing an intent nobody expressed. Those two fall back to no window,
which is the permissive default and what a fresh install gets;
`MaxFileSizeMB` carries over unchanged, because a ceiling on bytes
still means exactly what it did.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MeQt5hgXg5YGoNZQ9ozG7L

backend/config/config.go

@@ -411,9 +411,10 @@ func (c *Config) SetDownloadPreferences(prefs download.AutoDownloadPrefs) error
 		formats = append(formats, string(f))
 	}
 
-	c.Downloads.MinFileSizeMB = prefs.MinSizeMB
+	c.Downloads.MinKbps = prefs.MinKbps
+	c.Downloads.MaxKbps = prefs.MaxKbps
+	c.Downloads.PreferredKbps = prefs.PreferredKbps
 	c.Downloads.MaxFileSizeMB = prefs.MaxSizeMB
-	c.Downloads.PreferredFileSizeMB = prefs.PreferredSizeMB
 	c.Downloads.AllowedFormats = formats
 
 	if err := c.Save(); err != nil {

backend/download/config.go

@@ -34,13 +34,29 @@ type UserConfig struct {
 	// in one burst that every provider sees as a flood.
 	WantedBatch int `toml:"WantedBatch"`
 
-	// MinFileSizeMB, MaxFileSizeMB and PreferredFileSizeMB bound and
-	// nudge what auto-pick (interactive or via the request list) may
-	// grab without asking.  Zero on any of them is permissive: see
-	// AutoDownloadPrefs.
-	MinFileSizeMB       int `toml:"MinFileSizeMB"`
-	MaxFileSizeMB       int `toml:"MaxFileSizeMB"`
-	PreferredFileSizeMB int `toml:"PreferredFileSizeMB"`
+	// MinKbps, MaxKbps and PreferredKbps bound and nudge what auto-pick
+	// (interactive or via the request list) may grab without asking.
+	// Zero on any of them is permissive: see AutoDownloadPrefs.
+	//
+	// They replaced MinFileSizeMB / MaxFileSizeMB /
+	// PreferredFileSizeMB, which were megabytes and so said nothing
+	// without knowing how long the release was.  The old keys are
+	// deliberately *not* read back: a number that meant "300 MB" cannot
+	// be reinterpreted as a bitrate without knowing the album it was
+	// aimed at, so migrating it would be inventing an intent the user
+	// never expressed.  An existing config falls back to no window,
+	// which is the permissive default and matches a fresh install —
+	// and MaxFileSizeMB is the one that does carry over, because a
+	// ceiling on total bytes still means exactly what it did.
+	MinKbps       int `toml:"MinKbps"`
+	MaxKbps       int `toml:"MaxKbps"`
+	PreferredKbps int `toml:"PreferredKbps"`
+
+	// MaxFileSizeMB is a hard ceiling on a candidate's total size, kept
+	// in megabytes on purpose — it is a question about disk space, not
+	// about quality, and it has to apply to a candidate whose bitrate
+	// cannot be worked out at all.
+	MaxFileSizeMB int `toml:"MaxFileSizeMB"`
 
 	// AllowedFormats restricts auto-pick to these formats.  Empty means
 	// no restriction.  Values are Format strings ("flac", "mp3", ...).
@@ -56,10 +72,11 @@ func (c *UserConfig) AutoDownloadPrefs() AutoDownloadPrefs {
 	}
 
 	return AutoDownloadPrefs{
-		MinSizeMB:       c.MinFileSizeMB,
-		MaxSizeMB:       c.MaxFileSizeMB,
-		PreferredSizeMB: c.PreferredFileSizeMB,
-		AllowedFormats:  formats,
+		MinKbps:        c.MinKbps,
+		MaxKbps:        c.MaxKbps,
+		PreferredKbps:  c.PreferredKbps,
+		MaxSizeMB:      c.MaxFileSizeMB,
+		AllowedFormats: formats,
 	}
 }
 

backend/download/manager.go

@@ -236,6 +236,12 @@ func (m *Manager) AutoPickable(dl Download, ranked []Candidate) bool {
 	return AutoPickable(dl, ranked, m.preferences())
 }
 
+// AutoPickVeto wraps the package function the same way, and is what the
+// request list quotes back to the user.
+func (m *Manager) AutoPickVeto(dl Download, ranked []Candidate) string {
+	return AutoPickVeto(dl, ranked, m.preferences())
+}
+
 // Reload rebuilds every provider from stored config.  Called at startup
 // and after any provider settings change.
 //
@@ -612,16 +618,8 @@ func (m *Manager) Attempt(
 		return false, "", err
 	}
 
-	if !m.AutoPickable(dl, ranked) {
-		best := ranked[0]
-
-		return false, fmt.Sprintf(
-			"best of %d found is not a confident enough match "+
-				"(match %.0f%%, quality %.0f%%)",
-			len(ranked),
-			best.Match.Overall*100, //nolint:mnd // percent
-			best.Quality.Overall*100,
-		), nil
+	if veto := m.AutoPickVeto(dl, ranked); veto != "" {
+		return false, veto, nil
 	}
 
 	if err := m.store.CreateDownload(ctx, dl); err != nil {

backend/download/manager_test.go

@@ -218,8 +218,17 @@ func TestManagerEndToEndAutoPick(t *testing.T) {
 	}, "staging was never released, or the library was never rescanned")
 }
 
-// An ambiguous result set must park for the user rather than guess.
-func TestManagerWaitsWhenAmbiguous(t *testing.T) {
+// Two equally good copies are not an ambiguity — they are a spare.
+//
+// This asserted the opposite for as long as auto-pick required 0.08 of
+// daylight over the runner-up, and that rule was wrong in exactly the
+// case it fired hardest: a popular album turns up several *correct*
+// copies, all matching the tracklist, differing only in format and
+// seeders. There is no question there about what to fetch, only about
+// which copy, and the ranking already answers that — closest to the
+// preferred bitrate first. A candidate does not have to be better than
+// the field, only good enough on its own terms.
+func TestManagerAutoPicksAmongEquallyGoodCopies(t *testing.T) {
 	t.Parallel()
 
 	f := newManagerFixture(t)
@@ -237,11 +246,41 @@ func TestManagerWaitsWhenAmbiguous(t *testing.T) {
 		t.Fatalf("Start: %v", err)
 	}
 
-	if f.manager.AutoPickable(dl, ranked) {
-		t.Fatal("two equivalent candidates must not auto-pick")
+	if veto := f.manager.AutoPickVeto(dl, ranked); veto != "" {
+		t.Fatalf("two equally good copies must auto-pick, got veto: %s", veto)
+	}
+
+	waitForDownloadState(t, f.store, dl.ID, StateComplete)
+
+	// Exactly one of them was fetched, not both.
+	if grabs := a.GrabCalls + b.GrabCalls; grabs != 1 {
+		t.Errorf("grabs = %d, want exactly 1", grabs)
+	}
+}
+
+// The user can still pick explicitly when auto-pick is not what
+// happened — a candidate the ranking did not choose is still grabbable.
+func TestManagerPickIsExplicit(t *testing.T) {
+	t.Parallel()
+
+	f := newManagerFixture(t)
+
+	a := fakeWithAlbum(1, "source-a", ".flac")
+	b := fakeWithAlbum(2, "source-b", ".flac")
+
+	f.manager.installProvider(Config{ID: 1, Priority: 50}, a)
+	f.manager.installProvider(Config{ID: 2, Priority: 50}, b)
+
+	// No tracklist: never auto-picks, so the result set parks for the
+	// user and Pick is the only way anything is fetched.
+	dl := fourTrackDownload()
+	dl.Expected = nil
+
+	ranked, err := f.manager.Start(context.Background(), dl)
+	if err != nil {
+		t.Fatalf("Start: %v", err)
 	}
 
-	// Nothing was grabbed while waiting for the user.
 	if a.GrabCalls != 0 || b.GrabCalls != 0 {
 		t.Errorf(
 			"grabs happened without a pick: a=%d b=%d",
@@ -258,7 +297,6 @@ func TestManagerWaitsWhenAmbiguous(t *testing.T) {
 		t.Errorf("stored request id = %s, want %s", stored.ID, dl.ID)
 	}
 
-	// The user picks the second one explicitly.
 	if err := f.manager.Pick(
 		context.Background(), dl.ID, ranked[1].ID,
 	); err != nil {

backend/download/rank.go

@@ -1,6 +1,7 @@
 package download
 
 import (
+	"fmt"
 	"math"
 	"sort"
 	"strings"
@@ -34,38 +35,102 @@ const (
 	weightArtistFit    = 0.12
 )
 
-// Quality sub-weights.  They sum to 1.0 along with weightSizeFit below.
+// Quality sub-weights.  Each set sums to 1.0.
+//
+// There are two of them because a stated preference changes what the
+// other numbers are *for*.  `formatRank` and `bitrateScore` are the
+// app guessing at how good a copy is — FLAC over MP3, 320 over 128 —
+// and that guess exists precisely because the user has not said.  Once
+// they have, the guess should not outvote them: with the old single set
+// a preference of 320 kbps moved a candidate's score by at most 0.05
+// against the 0.42 riding on format, so asking for 320 and being handed
+// a FLAC every time was the *designed* behaviour.  That is the same
+// fault the megabyte window had — a preference the user can express and
+// the ranking can ignore.
 const (
-	weightFormat   = 0.42
-	weightBitrate  = 0.23
-	weightHealth   = 0.20
-	weightPriority = 0.10
-	weightSizeFit  = 0.05
+	weightFormat     = 0.42
+	weightBitrate    = 0.23
+	weightHealth     = 0.20
+	weightPriority   = 0.10
+	weightBitrateFit = 0.05
 )
 
+// Quality sub-weights when the user has named a preferred bitrate.
+// The weight comes off format and bitrate — the two proxies the
+// preference replaces — and health and priority are untouched, since
+// neither is a stand-in for anything the user just said.
+const (
+	statedWeightFormat     = 0.20
+	statedWeightBitrate    = 0.10
+	statedWeightHealth     = 0.20
+	statedWeightPriority   = 0.10
+	statedWeightBitrateFit = 0.40
+)
+
+// qualityWeights picks the set, in the order scoreQuality applies them.
+func qualityWeights(p AutoDownloadPrefs) (
+	format, bitrate, health, priority, fit float64,
+) {
+	if p.PreferredKbps > 0 {
+		return statedWeightFormat,
+			statedWeightBitrate,
+			statedWeightHealth,
+			statedWeightPriority,
+			statedWeightBitrateFit
+	}
+
+	return weightFormat,
+		weightBitrate,
+		weightHealth,
+		weightPriority,
+		weightBitrateFit
+}
+
 // unanchoredCap bounds the match score of a free-text request.  Without
 // an MBID there is no tracklist to be right about, so a confident-
 // looking score would be a lie — and auto-pick keys off this.
 const unanchoredCap = 0.65
 
 // AutoDownloadPrefs gates and scores what AutoPickable may choose
-// without asking.  Zero values are permissive: no size window and no
-// format restriction.
+// without asking.  Zero values are permissive: no bitrate window, no
+// size ceiling and no format restriction.
+//
+// **The window is a rate, not a size.**  It used to be three numbers in
+// megabytes, which cannot mean anything on their own: 300 MB is a
+// generous FLAC single and a suspiciously small boxset, and the user
+// setting the number has no idea which release the pipeline will
+// eventually apply it to.  A bitrate is the same statement normalised
+// by how long the music is, so one number holds across a 9-minute EP
+// and a 3-hour opera — and it is the unit the thing being described is
+// actually measured in.  The runtime is known for every request
+// auto-pick can act on (`Download.Expected` carries per-track lengths,
+// and an anchored request is the only kind that reaches here), so this
+// costs no extra lookup.
 type AutoDownloadPrefs struct {
-	// MinSizeMB and MaxSizeMB bound what auto-pick will grab.  Zero
-	// means no bound on that side.  A candidate outside the window is
-	// filtered out of auto-pick entirely, not merely scored down — a
-	// tiny "sampler" torrent or a boxset ten times the expected size is
-	// usually the wrong thing entirely, not a worse copy of the right
-	// thing.
-	MinSizeMB int `json:"minSizeMb"`
-	MaxSizeMB int `json:"maxSizeMb"`
+	// MinKbps and MaxKbps bound the average bitrate auto-pick will
+	// grab.  Zero means no bound on that side.  A candidate outside the
+	// window is filtered out of auto-pick entirely, not merely scored
+	// down — a 96 kbps rip of the right album is not a worse copy the
+	// user might accept, it is one they said not to take unattended.
+	//
+	// For reference: 320 is the top of MP3, ~500–1000 is FLAC depending
+	// on the material, and anything under ~128 is a transcode.
+	MinKbps int `json:"minKbps"`
+	MaxKbps int `json:"maxKbps"`
 
-	// PreferredSizeMB nudges the score toward a target size within the
-	// min/max window (a lossless rip and a heavily-padded lossless rip
-	// can both pass the window).  Zero disables the nudge; sizeFit then
-	// returns a neutral value that does not affect ranking.
-	PreferredSizeMB int `json:"preferredSizeMb"`
+	// PreferredKbps nudges the score toward a target rate within the
+	// window, and breaks the tie when several candidates are equally
+	// good matches.  Zero disables the nudge; bitrateFit then returns a
+	// neutral value that does not affect ranking.
+	PreferredKbps int `json:"preferredKbps"`
+
+	// MaxSizeMB is a hard ceiling on the whole candidate, and it is
+	// deliberately still a size.  It answers a different question from
+	// the window above — not "is this the quality I want" but "is this
+	// going to fill the disk" — and it has to hold even for a candidate
+	// whose bitrate cannot be worked out, which is exactly the shape a
+	// mislabelled boxset arrives in.  Zero means no ceiling.
+	MaxSizeMB int `json:"maxSizeMb"`
 
 	// AllowedFormats restricts auto-pick to candidates whose audio
 	// files are all in one of these formats.  Empty means no
@@ -74,19 +139,33 @@ type AutoDownloadPrefs struct {
 }
 
 // eligible reports whether a candidate may be auto-picked under these
-// preferences: within the size window (when set) and, when a format
-// list is given, every audio file in an allowed format.
-func (p AutoDownloadPrefs) eligible(c Candidate) bool {
+// preferences: inside the bitrate window and the size ceiling (when
+// set) and, when a format list is given, every audio file in an
+// allowed format.
+//
+// `runtimeMillis` is how long the requested release is, and 0 means
+// nobody knows.  An unknown runtime **passes** the bitrate window
+// rather than failing it: the window is a statement about quality, and
+// refusing everything the moment a tracklist is missing a length would
+// turn a gap in MusicBrainz into a silent embargo.  The size ceiling
+// still applies, which is why it exists separately.
+func (p AutoDownloadPrefs) eligible(c Candidate, runtimeMillis int64) bool {
 	const bytesPerMB = 1 << 20
 
-	if p.MinSizeMB > 0 && c.TotalSize < int64(p.MinSizeMB)*bytesPerMB {
-		return false
-	}
-
 	if p.MaxSizeMB > 0 && c.TotalSize > int64(p.MaxSizeMB)*bytesPerMB {
 		return false
 	}
 
+	if kbps := candidateKbps(c, runtimeMillis); kbps > 0 {
+		if p.MinKbps > 0 && kbps < float64(p.MinKbps) {
+			return false
+		}
+
+		if p.MaxKbps > 0 && kbps > float64(p.MaxKbps) {
+			return false
+		}
+	}
+
 	if len(p.AllowedFormats) == 0 {
 		return true
 	}
@@ -107,11 +186,14 @@ func (p AutoDownloadPrefs) eligible(c Candidate) bool {
 
 // filter returns only the candidates these preferences allow to be
 // auto-picked, in the same (already ranked) order.
-func (p AutoDownloadPrefs) filter(ranked []Candidate) []Candidate {
+func (p AutoDownloadPrefs) filter(
+	ranked []Candidate,
+	runtimeMillis int64,
+) []Candidate {
 	out := make([]Candidate, 0, len(ranked))
 
 	for _, c := range ranked {
-		if p.eligible(c) {
+		if p.eligible(c, runtimeMillis) {
 			out = append(out, c)
 		}
 	}
@@ -119,32 +201,116 @@ func (p AutoDownloadPrefs) filter(ranked []Candidate) []Candidate {
 	return out
 }
 
-// sizeFit scores how close totalSize is to PreferredSizeMB, 0..1,
-// falling off linearly as the size doubles or halves away from it.
-// Returns a neutral 0.5 when no preference is set, so the absence of a
-// preference does not bias ranking.
-func (p AutoDownloadPrefs) sizeFit(totalSize int64) float64 {
+// bitrateFit scores how close a candidate's average bitrate is to
+// PreferredKbps, falling off linearly as it doubles or halves away
+// from it.
+//
+// The range is **0.5 to 1.0, not 0 to 1**, and the floor is the point.
+// This carries 0.40 of the quality score once a preference is set, so a
+// span down to zero would let a preference of 320 kbps push a perfectly
+// good FLAC under `minQuality` and out of auto-pick altogether —
+// turning "I like 320" into "never take anything else", silently.  A
+// preference may promote the copy that matches it; it may not
+// disqualify the others.  That is what `MinKbps`/`MaxKbps` are for, and
+// they say so out loud.
+//
+// Returns the neutral floor when no preference is set or the rate
+// cannot be worked out, so neither an absent preference nor an absent
+// runtime biases ranking.
+func (p AutoDownloadPrefs) bitrateFit(
+	c Candidate,
+	runtimeMillis int64,
+) float64 {
 	const (
-		bytesPerMB = 1 << 20
-		neutral    = 0.5
+		neutral = 0.5
+		span    = 0.5
 	)
 
-	if p.PreferredSizeMB <= 0 || totalSize <= 0 {
+	if p.PreferredKbps <= 0 {
 		return neutral
 	}
 
-	preferred := float64(p.PreferredSizeMB) * bytesPerMB
-	ratio := float64(totalSize) / preferred
+	kbps := candidateKbps(c, runtimeMillis)
+	if kbps <= 0 {
+		return neutral
+	}
 
+	ratio := kbps / float64(p.PreferredKbps)
 	if ratio < 1 {
 		ratio = 1 / ratio
 	}
 
 	// ratio is now >= 1: 1.0 is an exact match, 2.0 is double or half
-	// the preferred size.  Falls to 0 at 2x away and beyond.
-	fit := 1 - (ratio - 1)
+	// the preferred rate, where the closeness term reaches 0.
+	return neutral + span*clamp01(1-(ratio-1))
+}
 
-	return clamp01(fit)
+// candidateKbps is a candidate's average audio bitrate, or 0 when it
+// cannot be worked out.
+//
+// Two sources, in this order, and the order matters:
+//
+//   - **Derived from bytes over runtime**, which is the honest one. It
+//     covers lossless (where a stated bitrate rarely exists), it cannot
+//     be lied to by a filename, and it is what the user's window means.
+//     Only the *audio* files count: cover scans and a log file are not
+//     part of the bitrate, and a folder with 30 MB of artwork would
+//     otherwise read as a better rip than the same music without it.
+//   - **The mean stated bitrate**, when the runtime is unknown. Weaker
+//     — a provider that parses it from an MP3 header states it and one
+//     that guesses from the filename also "states" it — but a number
+//     from the file itself beats no number at all.
+func candidateKbps(c Candidate, runtimeMillis int64) float64 {
+	const bitsPerByte = 8
+
+	audio := c.AudioFiles()
+	if len(audio) == 0 {
+		return 0
+	}
+
+	if runtimeMillis > 0 {
+		var bytes int64
+		for _, f := range audio {
+			bytes += f.Size
+		}
+
+		if bytes > 0 {
+			// bytes×8 bits over seconds, expressed in kbps: the two
+			// factors of 1000 (millis→seconds, bits→kilobits) cancel.
+			return float64(bytes) * bitsPerByte /
+				float64(runtimeMillis)
+		}
+	}
+
+	var (
+		sum   int
+		count int
+	)
+
+	for _, f := range audio {
+		if f.Bitrate > 0 {
+			sum += f.Bitrate
+			count++
+		}
+	}
+
+	if count == 0 {
+		return 0
+	}
+
+	return float64(sum) / float64(count)
+}
+
+// runtimeMillis is how long the requested release is, summed over its
+// expected tracklist.  Zero when the tracklist is absent or carries no
+// lengths, which is what every caller here treats as "unknown".
+func (d Download) runtimeMillis() int64 {
+	var total int64
+	for _, t := range d.Expected {
+		total += t.LengthMillis
+	}
+
+	return total
 }
 
 // Score fills a candidate's Match, Quality and Score fields.
@@ -160,7 +326,9 @@ func Score(dl Download, c Candidate, priority int, prefs AutoDownloadPrefs) Cand
 	c.Files = mergeMatched(c.Files, matched)
 
 	c.Match = scoreMatch(dl, c, audio, titleFit)
-	c.Quality = scoreQuality(c, audio, priority, prefs)
+	c.Quality = scoreQuality(
+		c, audio, priority, prefs, dl.runtimeMillis(),
+	)
 
 	c.Score = weightMatch*c.Match.Overall + weightQuality*c.Quality.Overall
 
@@ -279,11 +447,12 @@ func scoreQuality(
 	audio []CandidateFile,
 	priority int,
 	prefs AutoDownloadPrefs,
+	runtimeMillis int64,
 ) QualityScore {
 	q := QualityScore{
-		Health:   clamp01(c.Health),
-		Priority: clamp01(float64(priority) / 100.0),
-		SizeFit:  prefs.sizeFit(c.TotalSize),
+		Health:     clamp01(c.Health),
+		Priority:   clamp01(float64(priority) / 100.0),
+		BitrateFit: prefs.bitrateFit(c, runtimeMillis),
 	}
 
 	if len(audio) == 0 {
@@ -310,11 +479,13 @@ func scoreQuality(
 	q.FormatRank = worst
 	q.Bitrate = bitrateScore(audio)
 
-	q.Overall = weightFormat*q.FormatRank +
-		weightBitrate*q.Bitrate +
-		weightHealth*q.Health +
-		weightPriority*q.Priority +
-		weightSizeFit*q.SizeFit
+	wFormat, wBitrate, wHealth, wPriority, wFit := qualityWeights(prefs)
+
+	q.Overall = wFormat*q.FormatRank +
+		wBitrate*q.Bitrate +
+		wHealth*q.Health +
+		wPriority*q.Priority +
+		wFit*q.BitrateFit
 
 	if q.Mixed {
 		q.Overall *= 0.9
@@ -444,6 +615,19 @@ func Rank(
 			return out[i].Match.Overall > out[j].Match.Overall
 		}
 
+		// Closest to the preferred bitrate wins the tie.
+		//
+		// This is what decides which copy is taken now that auto-pick
+		// no longer requires the winner to be clear of the field: when
+		// several candidates are equally good matches of equal overall
+		// quality, the one the user said they wanted the shape of is
+		// the answer, ahead of provider priority.  With no preference
+		// set every BitrateFit is the same neutral value and this
+		// falls through, exactly as before.
+		if out[i].Quality.BitrateFit != out[j].Quality.BitrateFit {
+			return out[i].Quality.BitrateFit > out[j].Quality.BitrateFit
+		}
+
 		if out[i].Quality.Priority != out[j].Quality.Priority {
 			return out[i].Quality.Priority > out[j].Quality.Priority
 		}
@@ -454,19 +638,58 @@ func Rank(
 	return out
 }
 
-// AutoPickable reports whether a ranked list has a clear enough winner
-// to grab without asking.  It demands an anchored request, a high match,
-// decent quality, and daylight between first and second place — if two
-// candidates are close, the choice is the user's.
-func AutoPickable(dl Download, ranked []Candidate, prefs AutoDownloadPrefs) bool {
-	const (
-		minMatch   = 0.85
-		minQuality = 0.5
-		minLead    = 0.08
-	)
+// Auto-pick gates.  Named rather than inlined because AutoPickVeto
+// reports which of them refused, and a number in a sentence the user
+// reads should be the same number the decision used.
+const (
+	minMatch   = 0.85
+	minQuality = 0.5
+)
 
-	if !dl.Anchored() || len(ranked) == 0 {
-		return false
+// AutoPickable reports whether a ranked list has a candidate worth
+// grabbing without asking: an anchored request with a tracklist behind
+// it, and a candidate that clears the match and quality bars inside the
+// user's guardrails.
+//
+// **It does not require the winner to be better than the runner-up.**
+// It used to demand 0.08 of daylight on the combined score, which meant
+// the check fired hardest in the case it was never written for: a
+// popular album turns up five *correct* copies, all matching the
+// tracklist at 95%+ and differing only in format and seeders, their
+// scores land within a point of each other, and auto-pick refused
+// forever on the grounds that the choice was the user's.  It was not.
+// There was no question about *what* to fetch, only about which copy —
+// and abundance is the one condition under which that question matters
+// least.  A candidate does not need to be the best one, only one that
+// meets the criteria; where several do, `Rank` puts the one closest to
+// the preferred bitrate first.
+func AutoPickable(dl Download, ranked []Candidate, prefs AutoDownloadPrefs) bool {
+	return AutoPickVeto(dl, ranked, prefs) == ""
+}
+
+// AutoPickVeto returns the reason auto-pick declined, or "" when it
+// would go ahead.
+//
+// It exists because "it rejected all of them" was indistinguishable
+// from "it found nothing good".  The request list's message was built
+// from `ranked[0]` — the best candidate *before* the size and format
+// guardrails, and before the lead check — so a request refused because
+// the user's maximum size excluded every copy, or because three equally
+// good copies were found, reported "best of 12 found is not a confident
+// enough match (match 96%, quality 88%)".  Numbers that clear both
+// thresholds, beside a refusal, is a message that teaches the user the
+// matcher is broken.  Each gate names itself now.
+func AutoPickVeto(
+	dl Download,
+	ranked []Candidate,
+	prefs AutoDownloadPrefs,
+) string {
+	if len(ranked) == 0 {
+		return "nothing found"
+	}
+
+	if !dl.Anchored() {
+		return "the request is free text, so there is no release to be right about"
 	}
 
 	// An anchor with no tracklist behind it is an anchor in name only:
@@ -474,29 +697,42 @@ func AutoPickable(dl Download, ranked []Candidate, prefs AutoDownloadPrefs) bool
 	// is exactly the evidence a wrong-album candidate also has.  This
 	// matters most for the request list, where nobody is watching.
 	if len(dl.Expected) == 0 {
-		return false
+		return "no tracklist for this release is known yet, so a candidate cannot be checked against it"
 	}
 
-	// The guardrails apply before the match/quality/lead checks: a
-	// candidate outside the allowed size or format is not a worse
-	// choice, it is not a choice auto-pick may make at all, so it must
-	// not count as "the winner" nor as "second place" for the lead
-	// check below.
-	eligible := prefs.filter(ranked)
+	// The guardrails apply before the match and quality checks: a
+	// candidate outside the allowed bitrate, size or format is not a
+	// worse choice, it is not a choice auto-pick may make at all, so it
+	// must not count as "the winner" either.
+	eligible := prefs.filter(ranked, dl.runtimeMillis())
 	if len(eligible) == 0 {
-		return false
+		return fmt.Sprintf(
+			"all %d found are outside the auto-download bitrate, size or format limits",
+			len(ranked),
+		)
 	}
 
 	best := eligible[0]
-	if best.Match.Overall < minMatch || best.Quality.Overall < minQuality {
-		return false
+
+	if best.Match.Overall < minMatch {
+		return fmt.Sprintf(
+			"best of %d found matches this release only %.0f%% (needs %.0f%%)",
+			len(ranked),
+			best.Match.Overall*100, //nolint:mnd // percent
+			minMatch*100,           //nolint:mnd // percent
+		)
 	}
 
-	if len(eligible) > 1 && best.Score-eligible[1].Score < minLead {
-		return false
+	if best.Quality.Overall < minQuality {
+		return fmt.Sprintf(
+			"best of %d found is the right release but scores %.0f%% on quality (needs %.0f%%)",
+			len(ranked),
+			best.Quality.Overall*100, //nolint:mnd // percent
+			minQuality*100,           //nolint:mnd // percent
+		)
 	}
 
-	return true
+	return ""
 }
 
 // mergeMatched copies MatchedTo assignments from the audio-only slice

backend/download/rank_test.go

@@ -1,6 +1,34 @@
 package download
 
-import "testing"
+import (
+	"strings"
+	"testing"
+)
+
+// trackMillis is five minutes; okComputer's four of them make a
+// twenty-minute release, which is what turns a candidate's byte count
+// into a bitrate the assertions below can name.
+const trackMillis = 5 * 60 * 1000
+
+// okComputerRuntime is that release's runtime, for the helpers that
+// need it directly.
+const okComputerRuntime = 4 * trackMillis
+
+// kbpsCandidate builds an annotated candidate whose audio adds up to
+// the given average bitrate over okComputer's runtime.
+func kbpsCandidate(id, ext string, kbps int) Candidate {
+	// bits = kbps × 1000 × (runtimeMillis / 1000), so the thousands
+	// cancel and the byte count is kbps × runtimeMillis / 8.
+	const bitsPerByte = 8
+
+	total := int64(kbps) * okComputerRuntime / bitsPerByte
+
+	c := candidateFor(id, allTitles(), ext, total/int64(len(allTitles())))
+	c.Files = AnnotateFiles(c.Files)
+	c.TotalSize = total
+
+	return c
+}
 
 // okComputer is the reference request used across ranking tests.
 func okComputer() Download {
@@ -8,11 +36,15 @@ func okComputer() Download {
 		ReleaseMBID: "mbid-ok-computer",
 		Artist:      "Radiohead",
 		Album:       "OK Computer",
+		// Four five-minute tracks: twenty minutes, so a candidate's
+		// bitrate is a number these tests can state exactly. Without
+		// lengths there is no runtime and the bitrate window has
+		// nothing to divide by.
 		Expected: []ExpectedTrack{
-			{Position: 1, Title: "Airbag"},
-			{Position: 2, Title: "Paranoid Android"},
-			{Position: 3, Title: "Subterranean Homesick Alien"},
-			{Position: 4, Title: "Exit Music (For a Film)"},
+			{Position: 1, Title: "Airbag", LengthMillis: trackMillis},
+			{Position: 2, Title: "Paranoid Android", LengthMillis: trackMillis},
+			{Position: 3, Title: "Subterranean Homesick Alien", LengthMillis: trackMillis},
+			{Position: 4, Title: "Exit Music (For a Film)", LengthMillis: trackMillis},
 		},
 	}
 }
@@ -187,7 +219,7 @@ func TestUnanchoredMatchIsCapped(t *testing.T) {
 	}
 }
 
-func TestAutoPickableRequiresAnchorAndLead(t *testing.T) {
+func TestAutoPickableRequiresAnchorAndTracklist(t *testing.T) {
 	t.Parallel()
 
 	dl := okComputer()
@@ -211,14 +243,18 @@ func TestAutoPickableRequiresAnchorAndLead(t *testing.T) {
 		}
 	})
 
-	t.Run("two close candidates are not", func(t *testing.T) {
+	// Two identical copies are a spare, not an ambiguity. This
+	// asserted the opposite while auto-pick required daylight over the
+	// runner-up — a rule that made abundance the thing that stopped a
+	// request being satisfied, which is backwards.
+	t.Run("two equally good candidates still are", func(t *testing.T) {
 		t.Parallel()
 
 		twin := best
 		twin.ID = "twin"
 
-		if AutoPickable(dl, []Candidate{best, twin}, AutoDownloadPrefs{}) {
-			t.Error("identical candidates must not auto-pick")
+		if !AutoPickable(dl, []Candidate{best, twin}, AutoDownloadPrefs{}) {
+			t.Error("identical good candidates must auto-pick")
 		}
 	})
 
@@ -300,18 +336,11 @@ func TestProviderPriorityBreaksTies(t *testing.T) {
 	}
 }
 
-const mb = 1 << 20
-
 func TestAutoDownloadPrefsEligible(t *testing.T) {
 	t.Parallel()
 
-	flacCandidate := candidateFor("c", allTitles(), ".flac", 30_000_000)
-	flacCandidate.Files = AnnotateFiles(flacCandidate.Files)
-	flacCandidate.TotalSize = 300 * mb
-
-	mp3Candidate := candidateFor("c", allTitles(), ".mp3", 3_000_000)
-	mp3Candidate.Files = AnnotateFiles(mp3Candidate.Files)
-	mp3Candidate.TotalSize = 30 * mb
+	flacCandidate := kbpsCandidate("c", ".flac", 900)
+	mp3Candidate := kbpsCandidate("c", ".mp3", 128)
 
 	tests := []struct {
 		name  string
@@ -321,18 +350,25 @@ func TestAutoDownloadPrefsEligible(t *testing.T) {
 	}{
 		{"zero value is permissive", AutoDownloadPrefs{}, flacCandidate, true},
 		{
-			"within min/max window",
-			AutoDownloadPrefs{MinSizeMB: 100, MaxSizeMB: 500},
+			"within the bitrate window",
+			AutoDownloadPrefs{MinKbps: 320, MaxKbps: 1200},
 			flacCandidate, true,
 		},
 		{
-			"below minimum",
-			AutoDownloadPrefs{MinSizeMB: 400},
+			"below the minimum bitrate",
+			AutoDownloadPrefs{MinKbps: 500},
+			mp3Candidate, false,
+		},
+		{
+			"above the maximum bitrate",
+			AutoDownloadPrefs{MaxKbps: 500},
 			flacCandidate, false,
 		},
 		{
-			"above maximum",
-			AutoDownloadPrefs{MaxSizeMB: 200},
+			// The ceiling is bytes, not a rate, and it is the guard
+			// that still works when the bitrate cannot be worked out.
+			"above the hard size ceiling",
+			AutoDownloadPrefs{MaxSizeMB: 50},
 			flacCandidate, false,
 		},
 		{
@@ -351,57 +387,131 @@ func TestAutoDownloadPrefsEligible(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			if got := tt.prefs.eligible(tt.c); got != tt.want {
+			got := tt.prefs.eligible(tt.c, okComputerRuntime)
+			if got != tt.want {
 				t.Errorf("eligible() = %v, want %v", got, tt.want)
 			}
 		})
 	}
 }
 
+// A release nobody knows the length of cannot be judged on bitrate, and
+// the window must not become a silent embargo because MusicBrainz is
+// missing a track length.  The size ceiling still applies — that is why
+// it is a separate field.
+func TestBitrateWindowPassesAnUnknownRuntime(t *testing.T) {
+	t.Parallel()
+
+	c := kbpsCandidate("c", ".mp3", 128)
+	prefs := AutoDownloadPrefs{MinKbps: 900}
+
+	if !prefs.eligible(c, 0) {
+		t.Error("an unknown runtime must pass the bitrate window")
+	}
+
+	if prefs.eligible(c, okComputerRuntime) {
+		t.Error("a known runtime must still be judged")
+	}
+
+	ceiling := AutoDownloadPrefs{MaxSizeMB: 1}
+	if ceiling.eligible(c, 0) {
+		t.Error("the size ceiling must apply even with no runtime")
+	}
+}
+
+// Artwork is not part of the bitrate.  A folder carrying 30 MB of
+// scans would otherwise read as a better rip than the same music
+// without them, which is backwards.
+func TestBitrateIgnoresNonAudioFiles(t *testing.T) {
+	t.Parallel()
+
+	c := kbpsCandidate("c", ".mp3", 320)
+	bare := candidateKbps(c, okComputerRuntime)
+
+	c.Files = append(c.Files, CandidateFile{
+		Path: "Radiohead - OK Computer/cover.jpg",
+		Size: 30 << 20,
+	})
+	c.Files = AnnotateFiles(c.Files)
+
+	if got := candidateKbps(c, okComputerRuntime); got != bare {
+		t.Errorf("bitrate with artwork = %f, want %f", got, bare)
+	}
+}
+
+// Where no runtime is known, a stated per-file bitrate is better than
+// no answer at all.
+func TestBitrateFallsBackToTheStatedRate(t *testing.T) {
+	t.Parallel()
+
+	c := candidateFor("c", allTitles(), ".mp3", 3_000_000)
+	for i := range c.Files {
+		c.Files[i].Bitrate = 192
+	}
+
+	c.Files = AnnotateFiles(c.Files)
+
+	if got := candidateKbps(c, 0); got != 192 {
+		t.Errorf("stated bitrate = %f, want 192", got)
+	}
+}
+
 func TestAutoDownloadPrefsFilter(t *testing.T) {
 	t.Parallel()
 
-	small := candidateFor("small", allTitles(), ".flac", 10_000_000)
-	small.TotalSize = 50 * mb
+	lossy := kbpsCandidate("lossy", ".mp3", 128)
+	lossless := kbpsCandidate("lossless", ".flac", 900)
 
-	big := candidateFor("big", allTitles(), ".flac", 30_000_000)
-	big.TotalSize = 500 * mb
+	prefs := AutoDownloadPrefs{MinKbps: 500}
 
-	prefs := AutoDownloadPrefs{MinSizeMB: 100, MaxSizeMB: 600}
+	filtered := prefs.filter(
+		[]Candidate{lossy, lossless}, okComputerRuntime,
+	)
 
-	filtered := prefs.filter([]Candidate{small, big})
-
-	if len(filtered) != 1 || filtered[0].ID != "big" {
+	if len(filtered) != 1 || filtered[0].ID != "lossless" {
 		t.Errorf("filter() = %v, want only the in-window candidate", filtered)
 	}
 }
 
-func TestAutoDownloadPrefsSizeFit(t *testing.T) {
+func TestAutoDownloadPrefsBitrateFit(t *testing.T) {
 	t.Parallel()
 
 	const neutral = 0.5
 
 	tests := []struct {
-		name      string
-		prefs     AutoDownloadPrefs
-		totalSize int64
-		want      float64
+		name  string
+		prefs AutoDownloadPrefs
+		c     Candidate
+		want  float64
 	}{
-		{"no preference is neutral", AutoDownloadPrefs{}, 300 * mb, neutral},
+		{
+			"no preference is neutral",
+			AutoDownloadPrefs{},
+			kbpsCandidate("c", ".flac", 900), neutral,
+		},
 		{
 			"exact match scores 1",
-			AutoDownloadPrefs{PreferredSizeMB: 300},
-			300 * mb, 1.0,
+			AutoDownloadPrefs{PreferredKbps: 320},
+			kbpsCandidate("c", ".mp3", 320), 1.0,
 		},
 		{
-			"double the preferred size scores 0",
-			AutoDownloadPrefs{PreferredSizeMB: 300},
-			600 * mb, 0.0,
+			// The floor is neutral, not zero: this term carries 0.40
+			// of the quality score once a preference is set, and a
+			// span to zero would let "I like 320" quietly disqualify
+			// every FLAC from auto-pick.
+			"double the preferred rate falls to the neutral floor",
+			AutoDownloadPrefs{PreferredKbps: 320},
+			kbpsCandidate("c", ".flac", 640), neutral,
 		},
 		{
-			"half the preferred size scores 0",
-			AutoDownloadPrefs{PreferredSizeMB: 300},
-			150 * mb, 0.0,
+			"half the preferred rate falls to the neutral floor",
+			AutoDownloadPrefs{PreferredKbps: 320},
+			kbpsCandidate("c", ".mp3", 160), neutral,
+		},
+		{
+			"an unknowable rate is neutral",
+			AutoDownloadPrefs{PreferredKbps: 320},
+			kbpsCandidate("c", ".mp3", 320), neutral,
 		},
 	}
 
@@ -409,30 +519,223 @@ func TestAutoDownloadPrefsSizeFit(t *testing.T) {
 		t.Run(tt.name, func(t *testing.T) {
 			t.Parallel()
 
-			if got := tt.prefs.sizeFit(tt.totalSize); got != tt.want {
-				t.Errorf("sizeFit(%d) = %f, want %f", tt.totalSize, got, tt.want)
+			// The last case deliberately withholds the runtime.
+			runtime := int64(okComputerRuntime)
+			if tt.name == "an unknowable rate is neutral" {
+				runtime = 0
+			}
+
+			if got := tt.prefs.bitrateFit(tt.c, runtime); got != tt.want {
+				t.Errorf("bitrateFit() = %f, want %f", got, tt.want)
 			}
 		})
 	}
 }
 
 // An otherwise-perfect candidate must not auto-pick when it falls
-// outside the configured size guard: the guardrail applies before the
-// match/quality/lead checks, not as one more input averaged into them.
-func TestAutoPickableRejectsCandidateOutsideSizeGuard(t *testing.T) {
+// outside the configured guardrails: they apply before the match and
+// quality checks, not as one more input averaged into them.
+func TestAutoPickableRejectsCandidateOutsideTheGuardrails(t *testing.T) {
 	t.Parallel()
 
 	dl := okComputer()
-	best := Score(dl, candidateFor("a", allTitles(), ".flac", 30_000_000), 50, AutoDownloadPrefs{})
-	best.TotalSize = 500 * mb
+	best := Score(dl, kbpsCandidate("a", ".flac", 900), 50, AutoDownloadPrefs{})
 
 	if !AutoPickable(dl, []Candidate{best}, AutoDownloadPrefs{}) {
 		t.Fatal("expected this candidate to be auto-pickable with no guardrails")
 	}
 
-	tight := AutoDownloadPrefs{MinSizeMB: 10, MaxSizeMB: 100}
+	if AutoPickable(dl, []Candidate{best}, AutoDownloadPrefs{MaxKbps: 320}) {
+		t.Error("candidate above the bitrate window must not auto-pick")
+	}
 
-	if AutoPickable(dl, []Candidate{best}, tight) {
-		t.Error("candidate outside the size guard must not auto-pick")
+	if AutoPickable(dl, []Candidate{best}, AutoDownloadPrefs{MaxSizeMB: 1}) {
+		t.Error("candidate above the size ceiling must not auto-pick")
+	}
+}
+
+// The refusal has to name the gate that refused.
+//
+// Before AutoPickVeto, every one of these came back as the same
+// sentence built from `ranked[0]` — the best candidate before the size
+// and format guardrails — so a request refused because the user's size
+// window excluded every copy reported a match and a quality that both
+// cleared their thresholds.  A refusal quoting numbers that pass is
+// what made the matcher look broken from outside.
+func TestAutoPickVetoNamesTheGate(t *testing.T) {
+	t.Parallel()
+
+	dl := okComputer()
+	best := Score(
+		dl,
+		candidateFor("a", allTitles(), ".flac", 30_000_000),
+		50,
+		AutoDownloadPrefs{},
+	)
+
+	// candidateFor sizes the files and leaves TotalSize at 0, which is
+	// what the guardrails read.
+	sized := func(c Candidate, total int64) Candidate {
+		c.TotalSize = total
+
+		return c
+	}
+
+	tests := []struct {
+		name    string
+		dl      Download
+		ranked  []Candidate
+		prefs   AutoDownloadPrefs
+		wantSub string
+	}{
+		{
+			name:    "nothing found",
+			dl:      dl,
+			ranked:  nil,
+			wantSub: "nothing found",
+		},
+		{
+			name:    "free text",
+			dl:      Download{Artist: "Radiohead", Album: "OK Computer"},
+			ranked:  []Candidate{best},
+			wantSub: "free text",
+		},
+		{
+			name: "no tracklist behind the anchor",
+			dl: Download{
+				ReleaseMBID: "mbid-ok-computer",
+				Artist:      "Radiohead",
+				Album:       "OK Computer",
+			},
+			ranked:  []Candidate{best},
+			wantSub: "no tracklist",
+		},
+		{
+			// The candidate is 120 MB and the window tops out at 1 MB:
+			// the old message reported its match and quality instead.
+			name:    "outside the size window",
+			dl:      dl,
+			ranked:  []Candidate{sized(best, 120<<20)},
+			prefs:   AutoDownloadPrefs{MaxSizeMB: 1},
+			wantSub: "bitrate, size or format limits",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			got := AutoPickVeto(tt.dl, tt.ranked, tt.prefs)
+			if !strings.Contains(got, tt.wantSub) {
+				t.Errorf("veto = %q, want it to mention %q", got, tt.wantSub)
+			}
+		})
+	}
+}
+
+// A clear winner has no veto at all — the sentence is empty, which is
+// what AutoPickable reads.
+func TestAutoPickVetoIsEmptyForAClearWinner(t *testing.T) {
+	t.Parallel()
+
+	dl := okComputer()
+	best := Score(
+		dl,
+		candidateFor("a", allTitles(), ".flac", 30_000_000),
+		50,
+		AutoDownloadPrefs{},
+	)
+	weak := Score(
+		dl,
+		candidateFor("b", allTitles()[:2], ".mp3", 1_000_000),
+		50,
+		AutoDownloadPrefs{},
+	)
+
+	if got := AutoPickVeto(dl, []Candidate{best, weak}, AutoDownloadPrefs{}); got != "" {
+		t.Errorf("veto = %q, want none", got)
+	}
+}
+
+// With several candidates that all clear the bar, the preferred
+// bitrate decides which one is taken.
+//
+// This is what replaced the daylight requirement.  Auto-pick no longer
+// refuses when the field is close; it takes the copy nearest the shape
+// the user asked for, which is the question they actually answered in
+// Settings.
+func TestPreferredBitrateBreaksTheTie(t *testing.T) {
+	t.Parallel()
+
+	dl := okComputer()
+	prefs := AutoDownloadPrefs{PreferredKbps: 320}
+
+	// Same album, same completeness, same health, same provider — the
+	// only difference between them is the rate.
+	lossless := kbpsCandidate("lossless", ".flac", 900)
+	perfect := kbpsCandidate("perfect", ".mp3", 320)
+
+	ranked := Rank(
+		dl, []Candidate{lossless, perfect}, nil, prefs,
+	)
+
+	if ranked[0].ID != "perfect" {
+		t.Errorf(
+			"winner = %q (fit %f) over %q (fit %f), want the 320 kbps copy",
+			ranked[0].ID, ranked[0].Quality.BitrateFit,
+			ranked[1].ID, ranked[1].Quality.BitrateFit,
+		)
+	}
+
+	if AutoPickVeto(dl, ranked, prefs) != "" {
+		t.Error("a close field must still auto-pick")
+	}
+}
+
+// With no preference set, nothing changes: BitrateFit is the same
+// neutral value for every candidate and the older tie-breaks decide.
+func TestNoPreferredBitrateLeavesRankingAlone(t *testing.T) {
+	t.Parallel()
+
+	dl := okComputer()
+
+	lossless := kbpsCandidate("lossless", ".flac", 900)
+	lossy := kbpsCandidate("lossy", ".mp3", 320)
+
+	ranked := Rank(
+		dl, []Candidate{lossy, lossless}, nil, AutoDownloadPrefs{},
+	)
+
+	if ranked[0].ID != "lossless" {
+		t.Errorf(
+			"winner = %q, want the lossless copy on format alone",
+			ranked[0].ID,
+		)
+	}
+}
+
+// A preferred bitrate promotes the copy that matches it and must never
+// disqualify the ones that do not.  It carries 0.40 of the quality
+// score, so a fit spanning down to zero would put a perfectly good FLAC
+// under minQuality and out of auto-pick — turning a preference into a
+// prohibition without saying so.  MinKbps and MaxKbps are how a user
+// says that on purpose.
+func TestAPreferredBitrateNeverDisqualifies(t *testing.T) {
+	t.Parallel()
+
+	dl := okComputer()
+	far := AutoDownloadPrefs{PreferredKbps: 128}
+
+	lossless := Score(dl, kbpsCandidate("flac", ".flac", 900), 50, far)
+
+	if lossless.Quality.Overall < minQuality {
+		t.Errorf(
+			"quality = %f under a far-off preference, want >= %f",
+			lossless.Quality.Overall, minQuality,
+		)
+	}
+
+	if veto := AutoPickVeto(dl, []Candidate{lossless}, far); veto != "" {
+		t.Errorf("a far-off preference vetoed the candidate: %s", veto)
 	}
 }

backend/download/types.go

@@ -302,7 +302,12 @@ type QualityScore struct {
 	Bitrate    float64 `json:"bitrate"`
 	Health     float64 `json:"health"`   // seeders, free slots
 	Priority   float64 `json:"priority"` // user's per-provider preference
-	SizeFit    float64 `json:"sizeFit"`  // closeness to the preferred download size
+	// BitrateFit is closeness to the preferred *rate*, which is what
+	// the auto-download window is expressed in.  It replaced a
+	// `SizeFit` measured in megabytes: a size means nothing without
+	// knowing how long the music is, so the same number described a
+	// generous single and a suspiciously small boxset.
+	BitrateFit float64 `json:"bitrateFit"`
 
 	// Mixed marks a candidate whose files are not all the same format,
 	// which usually means a hand-assembled folder rather than a rip.