progress: render a single download with the same table as several

block() no longer special-cases one download with a [bracketed] one-liner;
it always draws the summary line, the column header, and one row per
download. The non-TTY path emits the same summary for one or many. This
drops lineOne and the dual rendering path it created, so a column or state
change is made in one place, not two that could drift.

.gitignore

@@ -7,3 +7,13 @@ ref/
 bin/
 .torrent.db*
 *.part
+
+# media downloaded by running got in the repo tree (never commit content)
+*.mkv
+*.mp4
+*.avi
+*.mov
+*.webm
+*.iso
+*.mp3
+*.flac

README.md

@@ -1,13 +1,10 @@
 # got
 
-A small, Rob-Pike-style command-line download tool in Go: one program that
+A command-line download tool in Go. It fetches HTTP(S) files over multiple
-downloads HTTP(S) URLs over several connections and BitTorrent
+connections and downloads BitTorrent magnets and `.torrent` files — one binary,
-magnets/torrents, with a focused set of options.
+a small set of flags. It is a downloader, not a web client: there are no
-
+cookie/proxy/auth flags — pass `--header` for a one-off header (auth token,
-The design leans on Go's runtime instead of a hand-rolled reactor. There is no
+cookie, user-agent) when a download needs one.
-single-threaded event-poll loop: one goroutine per download blocks on real I/O,
-a buffered channel of slots bounds concurrency, and `context` carries shutdown.
-What remains is the data — and, per Pike, the data is the design.
 
 ## Build
 
@@ -15,148 +12,63 @@ What remains is the data — and, per Pike, the data is the design.
 go build -o got .
 ```
 
-Requires Go 1.25+. The BitTorrent engine is
+Needs Go 1.25+.
-[`anacrolix/torrent`](https://github.com/anacrolix/torrent); everything else is
-the standard library plus `golang.org/x/{term,time}`.
 
-## Use
+## Usage
 
 ```sh
-# segmented HTTP download, 16 connections, into ./downloads
+# HTTP download: parallel out of the box (5 connections); -s turns it up
-got -x16 -s16 -d downloads https://example.com/big.iso
+got https://example.com/big.iso
+got -s16 https://example.com/big.iso
 
 # resume an interrupted download
-got -c -x16 https://example.com/big.iso
+got -c https://example.com/big.iso
 
-# the same file from several mirrors at once (one file, connections spread
+# one file from several mirrors (segments spread across the servers,
-# across servers, a dead mirror falls over); -Z downloads them separately instead
+# a dead mirror falls over); -Z downloads them as separate files instead.
-got -x4 https://a.example/big.iso https://b.example/big.iso
+got -s16 https://a.example/big.iso https://b.example/big.iso
 
 # a torrent or magnet; seed for 30 minutes after finishing
 got --seed-time=30 ubuntu.torrent
 got 'magnet:?xt=urn:btih:...'
 
-# list the files in a torrent without downloading
+# many downloads, two at a time
-got -S -T some.torrent
-
-# several downloads at once, two running in parallel
 got -j2 -i urls.txt
 ```
 
-Run `got --help` (or `--help=http`, `--help=bittorrent`, ...) for the full
+Run `got --help` (or `--help=all`) for every option.
-option list.
 
-### Options
+## Common options
-
-A focused subset of options, with familiar short flags and sensible defaults.
 
 | flag | meaning | default |
 |------|---------|---------|
 | `-d, --dir` | output directory | `.` |
-| `-o, --out` | output filename (single download) | from URL |
+| `-o, --out` | output filename | from URL |
-| `-i, --input-file` | read downloads line by line (TAB-separated URLs = mirrors; `-` = stdin) | |
 | `-c, --continue` | resume a partial download | false |
-| `-x, --max-connection-per-server` | connections to one server (1–16) | 1 |
+| `-s, --split` | connections per download (the speed dial) | 5 |
-| `-s, --split` | split a download into N connections | 5 |
+| `-j, --max-concurrent-downloads` | files downloaded at once | 5 |
-| `-Z, --force-sequential` | download each command-line URL separately, not as mirrors | false |
-| `-k, --min-split-size` | do not split below this size | 20M |
-| `-j, --max-concurrent-downloads` | parallel downloads | 5 |
 | `--max-overall-download-limit` | global speed cap | 0 (off) |
-| `--max-download-limit` | per-download speed cap | 0 (off) |
+| `--checksum` | verify the finished file: `TYPE=DIGEST` (sha-256, sha-1, …) | |
-| `--retry-wait` | seconds to wait between retries | 0 |
+| `--seed-time` | minutes to seed after a torrent finishes | by ratio |
-| `--load-cookies` / `--save-cookies` | read/write a Netscape `cookies.txt` | |
-| `--conditional-get` | skip the download if the local file is up to date | false |
-| `--remote-time` | set the file's mtime from the server | false |
-| `--checksum` | verify the finished file: `TYPE=DIGEST` (sha-256, sha-1, md5, …) | |
-| `--dry-run` | check the file is available but do not download it | false |
-| `--ca-certificate` | verify HTTPS against the CA certificates in FILE (PEM) | |
-| `--stop` | stop the program after N seconds | 0 (off) |
-| `--disable-ipv6` | force IPv4-only connections | false |
-| `-T, --torrent-file` | a `.torrent` file | |
-| `--seed-time` | minutes to seed after finishing | seed by ratio |
 | `--seed-ratio` | stop seeding at this ratio | 1.0 |
-| `--listen-port` | port (range) for incoming peers | 6881-6999 |
-| `--enable-dht` | use the BitTorrent DHT | true |
-| `--select-file` | fetch only these file indexes (`1,3-5`) | all |
 | `-S, --show-files` | list torrent files and exit | |
-| `--bt-stop-timeout` | give up if no download progress for N s | 0 (off) |
+| `-q, --quiet` | no progress output | false |
-| `--bt-metadata-timeout` | give up if a magnet can't fetch metadata in N s | 60 |
-| `--save-session` | on exit, write unfinished downloads to FILE | |
-| `-q, --quiet` | no progress readout | false |
 
-### Resuming across runs
+## Resume
 
-There is no daemon — resume is a plain file. Point
+HTTP downloads resume from a small `<file>.got` sidecar — just re-run with `-c`.
-`--save-session` and `-i` at the same file and add `-c`: unfinished downloads
+Torrents resume from the data already on disk. To resume across runs, point
-are loaded at start and the still-unfinished ones are written back on exit.
+`--save-session` and `-i` at the same file:
 
 ```sh
-got -c --save-session=got.session -i got.session  <new urls/magnets...>
+got -c --save-session=got.session -i got.session  <urls/magnets...>
 ```
 
-On the first run the session file need not exist. HTTP downloads resume from
+## Notes
-their `.got` control file; torrents resume from the data already on disk
-(re-checked by the engine). A magnet with no reachable peers no longer hangs:
-`--bt-metadata-timeout` bounds the metadata fetch and defaults to 60s (set it to
-0 to wait forever).
 
-## Design
+- BitTorrent uses [`anacrolix/torrent`](https://github.com/anacrolix/torrent);
-
+  HTTP uses the standard library.
-```
+- Not implemented: FTP/SFTP, Metalink, and the JSON-RPC server.
-main            classify URIs, wire options, run, report exit code
+- Speed caps are global: `--max-overall-download-limit` /
- └─ download    the Download interface + the scheduler (-j semaphore, ctx)
+  `--max-overall-upload-limit` apply across the whole run.
-     ├─ httpdl  []Segment + worker pool + WriteAt + JSON resume sidecar
+- Standard `HTTP_PROXY` / `HTTPS_PROXY` environment variables are honored.
-     └─ bt      anacrolix/torrent behind the Download interface
- ├─ cli         one flat option table -> hand parser -> layered config
- └─ progress    one ticker goroutine, pull-snapshot, \r line redraw
-```
-
-The contract is one small interface:
-
-```go
-type Download interface {
-        Name() string
-        Run(ctx context.Context) error   // blocks in its own goroutine
-        Stat() Stat                       // a value snapshot, lock-free to read
-}
-```
-
-- **HTTP** splits the file into byte-range `Segment`s handed to a pool of
-  workers. Each worker streams its range straight to one shared file with
-  `os.File.WriteAt` — safe for concurrent non-overlapping writes, so there is no
-  shared seek offset and no mutex. Resume is a small JSON sidecar
-  (`<file>.got`) holding per-segment progress plus validators (length +
-  ETag/Last-Modified) so a stale file is never trusted.
-- **BitTorrent** is `anacrolix/torrent` configured from the CLI options and
-  driven to completion, then seeded for `--seed-time` minutes or up to
-  `--seed-ratio`.
-- **Options** are one flat `[]Opt` table — the single source of truth for
-  parsing, validation, defaults and `--help`. Layers apply in order:
-  built-in defaults, config file, proxy environment, command line.
-- **Progress** is a single goroutine that ticks once a second, pulls a snapshot
-  of the running downloads, derives speeds from the change since the last tick,
-  and redraws one line with `\r` + erase-to-end-of-line.
-
-## Status
-
-Implemented: segmented HTTP(S) with resume — including a foreign/browser-started
-partial file (`-c`) — multi-mirror downloads (several URLs, or TAB-grouped `-i`
-lines, fetch one file with connections spread across servers and fallover; `-Z`
-to download them separately), retries, rate limits, auto-renaming,
-`Content-Disposition` naming, conditional GET, cookies
-(`--load-cookies`/`--save-cookies`), HTTP basic auth, `--remote-time`, whole-file
-checksum verification (`--checksum`), and a `--dry-run` availability check;
-BitTorrent download + seeding (magnet and `.torrent`,
-DHT, trackers, file selection, show-files, metadata-fetch timeout), seeding that
-stops on whichever of `--seed-time`/`--seed-ratio` comes first, and a listen port
-chosen from the whole range so a busy port no longer disables BitTorrent;
-a command-line interface with documented exit codes, config file, live progress,
-and session save/reload for resume across runs.
-
-Deferred (not implemented yet): FTP/SFTP, Metalink, and the
-JSON-RPC server. The architecture leaves room for
-each — a new protocol is just another `Download`. One known limitation: the
-BitTorrent engine (`anacrolix/torrent`) applies download/upload rate limits
-client-wide, so `--max-upload-limit`/`--max-download-limit` act per-run rather
-than per-torrent when several torrents run at once (`--max-overall-*` are exact);
-DHT/PEX likewise cannot yet be disabled per private torrent.

bt/bt.go

@@ -9,13 +9,16 @@ package bt
 import (
 	"context"
 	"fmt"
+	"io"
+	"log/slog"
+	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
 	"sync/atomic"
 	"time"
 
-	missinggo "github.com/anacrolix/missinggo/v2"
+	alog "github.com/anacrolix/log"
 	"github.com/anacrolix/torrent"
 	"github.com/anacrolix/torrent/metainfo"
 	"github.com/hanbok/got/download"
@@ -26,14 +29,9 @@ import (
 type ClientConfig struct {
 	Dir            string
 	ListenPortSpec string        // raw --listen-port spec ("6881-6999,7000"); empty lets the OS choose.
-	DHT            bool
+	DHT            bool          // --enable-dht
-	MaxPeers       int           // max peer connections per torrent (0 = library default)
 	OverallDown    *rate.Limiter // global down limit (may be nil)
 	OverallUp      *rate.Limiter // global up limit (may be nil)
-	DownLimit      int64         // per-run bytes/s, 0 = unlimited (used only without a global limiter)
-	UpLimit        int64
-	UserAgent      string
-	DisableIPv6    bool // force IPv4-only (--disable-ipv6)
 }
 
 // ParsePorts expands a --listen-port spec into a flat list of candidate ports.
@@ -64,57 +62,54 @@ func ParsePorts(spec string) []int {
 		if err != nil {
 			continue
 		}
-		for i := a; i <= b; i++ {
+		// Clamp to the valid port space before iterating: a parseable but oversized
-			if i >= 1 && i <= 65535 {
+		// spec like "1-9999999999" would otherwise spin for ~10^10 iterations and
-				ports = append(ports, i)
+		// hang startup, even though only [1,65535] can ever be appended.
+		if a < 1 {
+			a = 1
 		}
+		if b > 65535 {
+			b = 65535
+		}
+		for i := a; i <= b; i++ {
+			ports = append(ports, i)
 		}
 	}
 	return ports
 }
 
+// quietSlogger filters anacrolix's structured logging down to Error and above,
+// so the routine webseed/peer/tracker warning chatter (the 403/429 noise) no
+// longer interleaves with — and corrupts — the live progress display. Genuine
+// errors still reach w.
+func quietSlogger(w io.Writer) *slog.Logger {
+	return slog.New(slog.NewTextHandler(w, &slog.HandlerOptions{Level: slog.LevelError}))
+}
+
 // NewClient builds the shared anacrolix client from the run-wide config. When a
 // listen-port spec is given it tries each candidate port in turn, advancing past
 // any that is already in use, and falls back to an OS-chosen port if none bind,
-// so a single busy port does not disable BitTorrent entirely.
+// so a single busy port does not disable BitTorrent entirely. The rate limits
-//
+// and the DHT toggle are client-wide (anacrolix has no per-torrent equivalent),
-// Two per-torrent features have no equivalent in anacrolix/torrent v1.61.0,
+// which is why they live here on the shared client rather than per download.
-// which exposes only client-wide knobs; both must therefore be configured run-wide
-// here rather than attached to an individual Torrent:
-//
-//  1. No per-Torrent rate limiter. Throttles are read from the client-wide
-//     DownloadRateLimiter/UploadRateLimiter (no TorrentSpec rate field exists), so
-//     per-torrent --max-download-limit / --max-upload-limit cannot be
-//     honored individually; the effective cap is the shared limiter set below.
-//  2. No per-Torrent DHT/PEX/LSD toggle for BEP27 private torrents. Those are
-//     client-wide only (NoDHT, DisablePEX, etc.), so a private torrent's leak
-//     prevention must come from a run-wide setting (e.g. --enable-dht=false).
 func NewClient(cfg ClientConfig) (*torrent.Client, error) {
 	c := torrent.NewDefaultClientConfig()
+	// Keep the library's own logging out of the readout. Webseed/peer warnings go
+	// through slog, the rest through the legacy analog logger, so filter both to
+	// Error and above (the analog default is Warning, which is what leaks today).
+	c.Slogger = quietSlogger(os.Stderr)
+	c.Logger = alog.Default.FilterLevel(alog.Error)
 	c.DataDir = cfg.Dir
 	if c.DataDir == "" {
 		c.DataDir = "."
 	}
 	c.Seed = true
 	c.NoDHT = !cfg.DHT
-	if cfg.MaxPeers > 0 {
+	if cfg.OverallDown != nil {
-		c.EstablishedConnsPerTorrent = cfg.MaxPeers
-	}
-	if cfg.UserAgent != "" {
-		c.HTTPUserAgent = cfg.UserAgent
-	}
-	c.DisableIPv6 = cfg.DisableIPv6
-	switch {
-	case cfg.OverallDown != nil:
 		c.DownloadRateLimiter = cfg.OverallDown
-	case cfg.DownLimit > 0:
-		c.DownloadRateLimiter = rate.NewLimiter(rate.Limit(cfg.DownLimit), download.LimiterBurst(cfg.DownLimit))
 	}
-	switch {
+	if cfg.OverallUp != nil {
-	case cfg.OverallUp != nil:
 		c.UploadRateLimiter = cfg.OverallUp
-	case cfg.UpLimit > 0:
-		c.UploadRateLimiter = rate.NewLimiter(rate.Limit(cfg.UpLimit), download.LimiterBurst(cfg.UpLimit))
 	}
 
 	// Candidate ports from the --listen-port spec.
@@ -148,10 +143,11 @@ func NewClient(cfg ClientConfig) (*torrent.Client, error) {
 	return cl, nil
 }
 
-// isAddrInUse reports whether err is an "address already in use" bind failure,
+// isAddrInUse reports whether err is an "address already in use" bind failure.
-// matching either missinggo's helper or the raw string the library wraps.
+// (anacrolix/missinggo's IsAddrInUse is this exact string match, so we just do
+// it directly rather than carry the import for it.)
 func isAddrInUse(err error) bool {
-	return err != nil && (missinggo.IsAddrInUse(err) || strings.Contains(err.Error(), "address already in use"))
+	return err != nil && strings.Contains(err.Error(), "address already in use")
 }
 
 // Options are the per-download settings.
@@ -159,8 +155,6 @@ type Options struct {
 	SeedTimeSet    bool          // was --seed-time given?
 	SeedTime       time.Duration // how long to seed (0 with SeedTimeSet means no seeding)
 	SeedRatio      float64       // stop seeding at this ratio; checked alongside SeedTime
-	StopTimeout    time.Duration // abort if no download progress for this long (0 = off)
-	MetaTimeout    time.Duration // abort a magnet that can't fetch metadata in this long (0 = off)
 	SelectFiles    map[int]bool  // 1-based file indexes to fetch; empty = all
 	CheckIntegrity bool          // re-verify data against piece hashes before downloading
 	DryRun         bool          // fetch metadata only, then stop without downloading (--dry-run)
@@ -180,12 +174,17 @@ type Download struct {
 	// t is published once Run adds the torrent to the client. It is atomic so
 	// Stat stays lock-free, exactly like httpdl.Stat and bt's own name field.
 	t atomic.Pointer[torrent.Torrent]
+
+	// seeding is closed once Run finishes downloading and transitions to
+	// seed-only, so the engine can drop this torrent from the -j concurrency
+	// count. Created in New, closed exactly once in Run.
+	seeding chan struct{}
 }
 
 // New builds a torrent download on the shared client. source is a .torrent path
 // when isFile is true, otherwise a magnet URI.
 func New(client *torrent.Client, source string, isFile bool, opts Options) *Download {
-	d := &Download{client: client, source: source, isFile: isFile, opts: opts}
+	d := &Download{client: client, source: source, isFile: isFile, opts: opts, seeding: make(chan struct{})}
 	if isFile {
 		d.setName(strings.TrimSuffix(filepath.Base(source), ".torrent"))
 	} else {
@@ -210,6 +209,12 @@ func (d *Download) setStatus(s download.Status) {
 	atomic.StoreInt32(&d.status, int32(s))
 }
 
+// SeedingStarted is closed when this torrent finishes downloading and switches
+// to seed-only. The engine watches it to release the -j concurrency slot at that
+// moment: seeding is not downloading, so a seed-only torrent must not hold a slot
+// that a queued download could use. Implements download.Seeder.
+func (d *Download) SeedingStarted() <-chan struct{} { return d.seeding }
+
 // id is the process-unique identity for this download: the infohash once known,
 // otherwise the source string (a pre-metadata magnet has no infohash yet, and
 // two such magnets would otherwise collide on Name).
@@ -289,20 +294,24 @@ func (d *Download) Run(ctx context.Context) (err error) {
 		return nil
 	}
 
-	if err := d.choose(t); err != nil {
+	// --check-integrity: re-hash the existing on-disk data BEFORE arming the
-		return err
+	// request loop, so already-good pieces are not re-requested from peers
-	}
+	// (verify first, then fetch only what is missing).
 	if d.opts.CheckIntegrity {
 		if err := t.VerifyDataContext(ctx); err != nil {
 			return err
 		}
 	}
+	if err := d.choose(t); err != nil {
+		return err
+	}
 
 	if err := d.wait(ctx, t); err != nil {
 		return err
 	}
 
 	d.setStatus(download.Seeding)
+	close(d.seeding) // free the -j slot: a seed-only torrent no longer downloads
 	d.seed(ctx, t)
 	d.setStatus(download.Complete)
 	return nil
@@ -347,36 +356,35 @@ func (d *Download) choose(t *torrent.Torrent) error {
 	return nil
 }
 
-// awaitInfo blocks until the torrent metadata arrives. It gives up after
+// metadataTimeout bounds the magnet metadata-fetch phase. A magnet with no
-// --bt-metadata-timeout (default 60s) so a magnet with no reachable peers — a
+// reachable peers — a dead link, or UDP trackers behind a firewall with no DHT —
-// dead link, or UDP trackers behind a firewall with no DHT — fails fast instead
+// would otherwise hang forever, so awaitInfo gives up after this fixed window.
-// of hanging forever. Setting --bt-metadata-timeout=0 disables the timeout and
+// It is not a user-facing flag — 60s is a generous ceiling that a healthy swarm
-// waits indefinitely.
+// clears in well under a second.
+const metadataTimeout = 60 * time.Second
+
+// awaitInfo blocks until the torrent metadata arrives, giving up after
+// metadataTimeout so a peerless magnet fails fast instead of hanging forever.
 func (d *Download) awaitInfo(ctx context.Context, t *torrent.Torrent) error {
-	var deadline <-chan time.Time
+	tm := time.NewTimer(metadataTimeout)
-	if d.opts.MetaTimeout > 0 {
-		tm := time.NewTimer(d.opts.MetaTimeout)
 	defer tm.Stop()
-		deadline = tm.C
-	}
 	select {
 	case <-t.GotInfo():
 		return nil
 	case <-ctx.Done():
 		return ctx.Err()
-	case <-deadline:
+	case <-tm.C:
-		return fmt.Errorf("timed out fetching metadata after %s", d.opts.MetaTimeout)
+		// Wrap DeadlineExceeded so the exit-code mapping classifies it as a timeout
+		// (2) via errors.Is, rather than matching on the message text.
+		return fmt.Errorf("timed out fetching metadata after %s: %w", metadataTimeout, context.DeadlineExceeded)
 	}
 }
 
-// wait blocks until the wanted data is complete, ctx is cancelled, or the
+// wait blocks until the wanted data is complete or ctx is cancelled, polling
-// download stalls past --bt-stop-timeout.
+// completion a couple of times a second.
 func (d *Download) wait(ctx context.Context, t *torrent.Torrent) error {
 	tick := time.NewTicker(500 * time.Millisecond)
 	defer tick.Stop()
-
-	last := t.BytesCompleted()
-	lastChange := time.Now()
 	for {
 		if d.complete(t) {
 			return nil
@@ -385,11 +393,6 @@ func (d *Download) wait(ctx context.Context, t *torrent.Torrent) error {
 		case <-ctx.Done():
 			return ctx.Err()
 		case <-tick.C:
-			if n := t.BytesCompleted(); n != last {
-				last, lastChange = n, time.Now()
-			} else if d.opts.StopTimeout > 0 && time.Since(lastChange) > d.opts.StopTimeout {
-				return fmt.Errorf("no progress for %s", d.opts.StopTimeout)
-			}
 		}
 	}
 }

bt/bt_test.go

@@ -1,10 +1,38 @@
 package bt
 
 import (
+	"bytes"
+	"context"
+	"log/slog"
 	"reflect"
+	"strings"
 	"testing"
 )
 
+// TestQuietSloggerDropsWarnings: the library's warning chatter (the webseed
+// 403/429 noise) is filtered out so it can't corrupt the live display, while a
+// genuine error still gets through.
+func TestQuietSloggerDropsWarnings(t *testing.T) {
+	var buf bytes.Buffer
+	lg := quietSlogger(&buf)
+
+	lg.Warn("webseed request error", "err", "429 Too Many Requests")
+	if buf.Len() != 0 {
+		t.Errorf("warning leaked into output: %q", buf.String())
+	}
+	// anacrolix's webseed code logs via Log(ctx, level, ...); confirm that path is
+	// filtered too, not just the Warn helper.
+	lg.Log(context.Background(), slog.LevelWarn, "another warning")
+	if buf.Len() != 0 {
+		t.Errorf("Log-at-Warn leaked: %q", buf.String())
+	}
+
+	lg.Error("real failure")
+	if !strings.Contains(buf.String(), "real failure") {
+		t.Errorf("error was suppressed, want it kept: %q", buf.String())
+	}
+}
+
 func TestParsePorts(t *testing.T) {
 	tests := []struct {
 		spec string

cli/help.go

@@ -89,19 +89,31 @@ func flagLabel(o *Opt) string {
 		b.WriteString("    ")
 	}
 	b.WriteString("--" + o.Long)
-	switch o.Kind {
+	if m := metavar(o); m != "" {
-	case Bool:
+		b.WriteString("=" + m)
-		// no argument shown
-	case Size:
-		b.WriteString("=SIZE")
-	case Int:
-		b.WriteString("=N")
-	case Float:
-		b.WriteString("=RATIO")
-	case Enum:
-		b.WriteString("=" + strings.Join(o.Enum, "|"))
-	default:
-		b.WriteString("=VAL")
 	}
 	return b.String()
 }
+
+// metavar is the placeholder shown after a value-taking flag, e.g. the "N" in
+// "--split=N". An explicit Opt.Metavar wins; otherwise it derives from the Kind.
+// Bool takes no value, so its metavar is empty and no "=ARG" is printed.
+func metavar(o *Opt) string {
+	if o.Metavar != "" {
+		return o.Metavar
+	}
+	switch o.Kind {
+	case Bool:
+		return ""
+	case Size:
+		return "SIZE"
+	case Int:
+		return "N"
+	case Float:
+		return "RATIO"
+	case Enum:
+		return strings.Join(o.Enum, "|")
+	default:
+		return "VAL"
+	}
+}

cli/option.go

@@ -45,11 +45,15 @@ func (t Tag) String() string {
 
 // Opt describes one option: its names, value kind, default and help text.
 type Opt struct {
-	Long    string // long name without dashes, e.g. "max-connection-per-server"
+	Long    string // long name without dashes, e.g. "max-concurrent-downloads"
 	Short   byte   // short flag byte, e.g. 'x'; 0 if none
 	Kind    Kind
 	Default string
 	Help    string
+	// Metavar overrides the "=PLACEHOLDER" shown after the flag in --help. Empty
+	// means derive it from Kind (N, SIZE, RATIO, ...). Set it only when the
+	// Kind-derived default would mislead, e.g. seed-time is minutes, not a ratio.
+	Metavar string
 	Tag     Tag
 	Enum    []string // valid values when Kind == Enum
 	// Min is the inclusive lower Int/Size bound. The zero value enforces a
@@ -60,68 +64,44 @@ type Opt struct {
 	Max int64
 }
 
-// options is the single source of truth: a focused, practical subset.
+// options is the single source of truth: a focused, practical subset. The Tag
+// decides which --help group an option shows under; the Basic group is the bare
+// `got --help` and is kept to the handful of flags that change WHAT happens, not
+// how fast. Every other flag still works — it just lives behind --help=<group>.
 var options = []Opt{
-	// --- basic ---
+	// --- basic --- the outcome-changing core shown by a bare `got --help`.
 	{Long: "dir", Short: 'd', Kind: Str, Help: "directory to store downloaded files", Tag: Basic},
 	{Long: "out", Short: 'o', Kind: Str, Help: "output filename for the download", Tag: Basic},
 	{Long: "input-file", Short: 'i', Kind: Str, Help: "read URIs line by line from FILE (- for stdin)", Tag: Basic},
+	{Long: "max-concurrent-downloads", Short: 'j', Kind: Int, Default: "5", Min: 1, Help: "how many files to download at once (not connections within one file)", Tag: Basic},
 	{Long: "continue", Short: 'c', Kind: Bool, Default: "false", Help: "resume a partially downloaded file", Tag: Basic},
-	{Long: "max-concurrent-downloads", Short: 'j', Kind: Int, Default: "5", Min: 1, Help: "max number of parallel downloads", Tag: Basic},
+	{Long: "split", Short: 's', Kind: Int, Default: "5", Min: 1, Help: "connections per download — the speed dial (default 5; e.g. -s16 for 16)", Tag: Basic},
-	{Long: "check-integrity", Short: 'V', Kind: Bool, Default: "false", Help: "re-verify torrent data against piece hashes (BitTorrent)", Tag: Basic},
-	{Long: "show-files", Short: 'S', Kind: Bool, Default: "false", Help: "list files in a torrent and exit", Tag: Basic},
-	{Long: "allow-overwrite", Kind: Bool, Default: "false", Help: "overwrite an existing file", Tag: Basic},
-	{Long: "auto-file-renaming", Kind: Bool, Default: "true", Help: "rename file (.1, .2, ...) if it already exists", Tag: Basic},
 	{Long: "max-overall-download-limit", Kind: Size, Default: "0", Help: "global download speed limit (0 = unlimited)", Tag: Basic},
-	{Long: "max-download-limit", Kind: Size, Default: "0", Help: "per-download speed limit (0 = unlimited)", Tag: Basic},
+	{Long: "checksum", Kind: Str, Help: "verify the finished file: TYPE=DIGEST, e.g. sha-256=<hex> (md5, sha-1, sha-224, sha-256, sha-384, sha-512)", Tag: Basic},
+	{Long: "show-files", Short: 'S', Kind: Bool, Default: "false", Help: "list files in a torrent and exit", Tag: Basic},
 	{Long: "quiet", Short: 'q', Kind: Bool, Default: "false", Help: "suppress the progress readout", Tag: Basic},
-	{Long: "human-readable", Kind: Bool, Default: "true", Help: "show sizes as Ki/Mi/Gi", Tag: Basic},
 
 	// --- http ---
-	{Long: "max-connection-per-server", Short: 'x', Kind: Int, Default: "1", Min: 1, Max: 16, Help: "max connections to one server (1-16)", Tag: HTTP},
-	{Long: "split", Short: 's', Kind: Int, Default: "5", Min: 1, Help: "split a download into N connections; actual connections are min(max-connection-per-server, split), and -x defaults to 1", Tag: HTTP},
-	{Long: "min-split-size", Short: 'k', Kind: Size, Default: "20M", Min: 1 << 20, Max: 1 << 30, Help: "do not split a piece smaller than SIZE (1M-1024M)", Tag: HTTP},
 	{Long: "force-sequential", Short: 'Z', Kind: Bool, Default: "false", Help: "download each command-line URI as its own file instead of mirroring them", Tag: HTTP},
 	{Long: "max-tries", Short: 'm', Kind: Int, Default: "5", Min: 0, Help: "max retries per segment (0 = unlimited)", Tag: HTTP},
-	{Long: "timeout", Short: 't', Kind: Int, Default: "60", Min: 1, Help: "connection timeout in seconds", Tag: HTTP},
+	{Long: "timeout", Short: 't', Kind: Int, Default: "60", Min: 1, Help: "connection/idle timeout in seconds", Tag: HTTP},
-	{Long: "header", Kind: List, Help: "append an extra HTTP header (repeatable)", Tag: HTTP},
+	{Long: "header", Kind: List, Help: "append an extra HTTP header (repeatable), e.g. 'Authorization: Bearer …'", Tag: HTTP},
-	{Long: "user-agent", Short: 'U', Kind: Str, Default: "got/1.0", Help: "HTTP User-Agent", Tag: HTTP},
-	{Long: "referer", Kind: Str, Help: "HTTP Referer header", Tag: HTTP},
-	{Long: "all-proxy", Kind: Str, Help: "proxy for all protocols (host:port)", Tag: HTTP},
-	{Long: "check-certificate", Kind: Bool, Default: "true", Help: "verify the server's TLS certificate", Tag: HTTP},
-	{Long: "ca-certificate", Kind: Str, Help: "verify HTTPS servers against the CA certificates in FILE (PEM)", Tag: HTTP},
-	{Long: "retry-wait", Kind: Int, Default: "0", Min: 0, Max: 600, Help: "seconds to wait between retries (0 = no wait)", Tag: HTTP},
-	{Long: "connect-timeout", Kind: Int, Default: "60", Min: 1, Help: "connection establishment timeout in seconds", Tag: HTTP},
-	{Long: "load-cookies", Kind: Str, Help: "load Cookies from FILE (Netscape/Mozilla format)", Tag: HTTP},
-	{Long: "save-cookies", Kind: Str, Help: "save Cookies to FILE on exit", Tag: HTTP},
-	{Long: "conditional-get", Kind: Bool, Default: "false", Help: "download only if the remote file is newer than the local one", Tag: HTTP},
-	{Long: "remote-time", Kind: Bool, Default: "false", Help: "set the local file's mtime from the server", Tag: HTTP},
-	{Long: "http-user", Kind: Str, Help: "HTTP basic-auth user", Tag: HTTP},
-	{Long: "http-passwd", Kind: Str, Help: "HTTP basic-auth password", Tag: HTTP},
-	{Long: "lowest-speed-limit", Kind: Size, Default: "0", Help: "abort if speed stays below SIZE bytes/sec (0 = off)", Tag: HTTP},
-	{Long: "checksum", Kind: Str, Help: "verify the finished file: TYPE=DIGEST, e.g. sha-256=<hex> (md5, sha-1, sha-224, sha-256, sha-384, sha-512)", Tag: HTTP},
 
 	// --- bittorrent ---
-	{Long: "torrent-file", Short: 'T', Kind: Str, Help: "path to a .torrent file", Tag: BitTorrent},
+	{Long: "check-integrity", Short: 'V', Kind: Bool, Default: "false", Help: "re-verify torrent data against piece hashes", Tag: BitTorrent},
-	{Long: "seed-time", Kind: Float, Help: "minutes to seed after completion (0 = no seeding)", Tag: BitTorrent},
+	{Long: "seed-time", Kind: Float, Metavar: "MIN", Help: "minutes to seed after completion (0 = no seeding)", Tag: BitTorrent},
 	{Long: "seed-ratio", Kind: Float, Default: "1.0", Help: "stop seeding at this share ratio (0 = unlimited)", Tag: BitTorrent},
-	{Long: "bt-stop-timeout", Kind: Int, Default: "0", Min: 0, Help: "stop a torrent with no download progress for N seconds (0 = off)", Tag: BitTorrent},
-	{Long: "bt-metadata-timeout", Kind: Int, Default: "60", Min: 0, Help: "stop a magnet that can't fetch metadata in N seconds (0 = off)", Tag: BitTorrent},
 	{Long: "listen-port", Kind: Str, Default: "6881-6999", Help: "TCP port (range) for incoming peers", Tag: BitTorrent},
-	{Long: "enable-dht", Kind: Bool, Default: "true", Help: "enable the BitTorrent DHT", Tag: BitTorrent},
+	{Long: "enable-dht", Kind: Bool, Default: "true", Help: "enable the BitTorrent DHT (turn off for private torrents)", Tag: BitTorrent},
-	{Long: "bt-max-peers", Kind: Int, Default: "55", Min: 0, Help: "max peers per torrent (0 = unlimited)", Tag: BitTorrent},
 	{Long: "max-overall-upload-limit", Kind: Size, Default: "0", Help: "global upload speed limit (0 = unlimited)", Tag: BitTorrent},
-	{Long: "max-upload-limit", Short: 'u', Kind: Size, Default: "0", Help: "per-torrent upload speed limit", Tag: BitTorrent},
 	{Long: "select-file", Kind: Str, Help: "download only these file indexes, e.g. 1,3-5", Tag: BitTorrent},
-	{Long: "follow-torrent", Kind: Bool, Default: "true", Help: "after fetching a .torrent over HTTP, download its content", Tag: BitTorrent},
 
 	// --- advanced ---
-	{Long: "file-allocation", Short: 'a', Kind: Enum, Default: "prealloc", Enum: []string{"none", "prealloc", "trunc", "falloc"}, Help: "how to allocate disk space", Tag: Advanced},
+	{Long: "allow-overwrite", Kind: Bool, Default: "false", Help: "overwrite an existing file instead of renaming the new one", Tag: Advanced},
+	{Long: "auto-file-renaming", Kind: Bool, Default: "true", Help: "rename file (.1, .2, ...) if it already exists", Tag: Advanced},
+	{Long: "file-allocation", Short: 'a', Kind: Enum, Default: "prealloc", Enum: []string{"none", "prealloc", "trunc", "falloc"}, Help: "how to reserve disk space (prealloc and falloc are identical here)", Tag: Advanced},
 	{Long: "dry-run", Kind: Bool, Default: "false", Help: "check that the file is available but do not download it", Tag: Advanced},
-	{Long: "stop", Kind: Int, Default: "0", Min: 0, Help: "stop the program after N seconds (0 = off)", Tag: Advanced},
-	{Long: "disable-ipv6", Kind: Bool, Default: "false", Help: "disable IPv6 (force IPv4-only connections)", Tag: Advanced},
 	{Long: "save-session", Kind: Str, Help: "on exit, write unfinished downloads to FILE (reload with -i)", Tag: Advanced},
-	{Long: "auto-save-interval", Kind: Int, Default: "60", Min: 0, Max: 600, Help: "save the session file every N seconds (0 = only on exit)", Tag: Advanced},
 	{Long: "conf-path", Kind: Str, Help: "path to the config file", Tag: Advanced},
 	{Long: "no-conf", Kind: Bool, Default: "false", Help: "do not read a config file", Tag: Advanced},
 }

cli/options.go

@@ -2,21 +2,24 @@ package cli
 
 import (
 	"fmt"
+	"math"
 	"strconv"
 	"strings"
 )
 
 // Options is the resolved configuration: a flat name->value map plus a record
 // of which names were explicitly set (so callers can tell a default from a
-// chosen value). Values are kept as strings end-to-end and converted only at
+// chosen value). The raw strings carry the layered override merge; finalize()
-// the point of use by the typed getters below.
+// then parses each one exactly once into typed, and the numeric/bool getters
+// read that — no value is parsed twice.
 type Options struct {
 	vals  map[string]string
 	set   map[string]bool
+	typed map[string]any // parsed value per option, filled once by finalize()
 }
 
 func newOptions() *Options {
-	return &Options{vals: map[string]string{}, set: map[string]bool{}}
+	return &Options{vals: map[string]string{}, set: map[string]bool{}, typed: map[string]any{}}
 }
 
 // IsSet reports whether name was given on the command line or in the config
@@ -26,47 +29,30 @@ func (o *Options) IsSet(name string) bool { return o.set[name] }
 // Str returns the raw string value (empty if unset and no default).
 func (o *Options) Str(name string) string { return o.vals[name] }
 
-// boolWords is the single accepted vocabulary for boolean options, mapping each
+// boolWords is the accepted vocabulary for boolean options: exactly true and
-// recognised spelling to its truth value. The Bool reader, truthy, and
+// false, nothing else. boolWord is the single consult point — the Bool reader,
-// validate() all consult it, so exactly the words that validate are honoured
+// validate(), and the no-conf bootstrap all go through it — so exactly the words
-// (no "accepted by the reader but rejected by validate" surprises like --x=on).
+// that validate are honoured.
 var boolWords = map[string]bool{
-	"true": true, "yes": true, "1": true, "on": true,
+	"true":  true,
-	"false": false, "no": false, "0": false, "off": false,
+	"false": false,
 }
 
 // boolWord reports a value's truth and whether it is a recognised boolean word.
+// Whitespace is trimmed, but case is significant: "True"/"TRUE" are rejected, so
+// the match is against exactly "true"/"false".
 func boolWord(s string) (val, ok bool) {
-	val, ok = boolWords[strings.ToLower(strings.TrimSpace(s))]
+	val, ok = boolWords[strings.TrimSpace(s)]
 	return val, ok
 }
 
-// Bool reports whether the value is a truthy boolean word.
+// Bool, Int, Float and Size read the value finalize() already parsed and stored
-func (o *Options) Bool(name string) bool {
+// in typed; an unset option (no entry) reads as the zero value. The conversion
-	val, _ := boolWord(o.vals[name])
+// happened once, at finalize, so these never re-parse a string.
-	return val
+func (o *Options) Bool(name string) bool     { v, _ := o.typed[name].(bool); return v }
-}
+func (o *Options) Int(name string) int       { v, _ := o.typed[name].(int64); return int(v) }
-
+func (o *Options) Float(name string) float64 { v, _ := o.typed[name].(float64); return v }
-// Int returns the value as an int, or 0 if empty/invalid.
+func (o *Options) Size(name string) int64    { v, _ := o.typed[name].(int64); return v }
-func (o *Options) Int(name string) int { return int(o.Int64(name)) }
-
-// Int64 returns the value as an int64, or 0 if empty/invalid.
-func (o *Options) Int64(name string) int64 {
-	n, _ := strconv.ParseInt(strings.TrimSpace(o.vals[name]), 10, 64)
-	return n
-}
-
-// Float returns the value as a float64, or 0 if empty/invalid.
-func (o *Options) Float(name string) float64 {
-	f, _ := strconv.ParseFloat(strings.TrimSpace(o.vals[name]), 64)
-	return f
-}
-
-// Size returns a byte count parsed from a value like "20M" or "512K".
-func (o *Options) Size(name string) int64 {
-	n, _ := parseSize(o.vals[name])
-	return n
-}
 
 // List returns a repeatable option's accumulated values.
 func (o *Options) List(name string) []string {
@@ -105,5 +91,10 @@ func parseSize(s string) (int64, error) {
 	if n < 0 {
 		return 0, fmt.Errorf("negative size %q", s)
 	}
+	// Reject a value whose unit multiply would overflow int64 and silently wrap to
+	// a bogus (positive or negative) byte count.
+	if mult > 1 && n > math.MaxInt64/mult {
+		return 0, fmt.Errorf("size %q too large", s)
+	}
 	return n * mult, nil
 }

cli/parse.go

@@ -27,8 +27,8 @@ type Result struct {
 }
 
 // Parse resolves args into options and URIs, applying the layered override
-// order: built-in defaults, then the config file, then proxy
+// order: built-in defaults, then the config file, then the command line
-// environment variables, then the command line (last wins).
+// (last wins).
 func Parse(args []string) (*Result, error) {
 	cmdVals, uris, action, helpTag, err := parseArgs(args)
 	if err != nil {
@@ -41,23 +41,47 @@ func Parse(args []string) (*Result, error) {
 	opts := newOptions()
 	applyDefaults(opts)
 
-	if !truthy(cmdVals["no-conf"]) {
+	if noConf, _ := boolWord(cmdVals["no-conf"]); !noConf {
 		explicit := cmdVals["conf-path"]
 		path, fromUser := confPath(explicit)
 		if err := applyConfig(opts, path, fromUser); err != nil {
 			return nil, err
 		}
 	}
-	applyEnv(opts)
 
 	for name, val := range cmdVals {
 		if err := set(opts, name, val); err != nil {
 			return nil, err
 		}
 	}
+	if err := opts.finalize(); err != nil {
+		return nil, err
+	}
 	return &Result{Action: Run, Options: opts, URIs: uris}, nil
 }
 
+// finalize parses every resolved value once into its typed form, validating it
+// in the same pass; the numeric/bool getters then just read the result. It runs
+// after all layering, so each option is converted exactly once, from its final
+// (last-wins) string — not once per layer and again per read.
+func (o *Options) finalize() error {
+	for i := range options {
+		opt := &options[i]
+		raw, ok := o.vals[opt.Long]
+		if !ok {
+			continue
+		}
+		v, err := parseValue(opt, raw)
+		if err != nil {
+			return err
+		}
+		if v != nil {
+			o.typed[opt.Long] = v
+		}
+	}
+	return nil
+}
+
 // parseArgs walks the argument list once. It recognises --long, --long=val,
 // -x, -xval, -x val and short bool bundles like -cq. Like getopt_long, it
 // permutes: a non-flag token becomes a URI but scanning continues so flags may
@@ -138,14 +162,23 @@ func parseArgs(args []string) (vals map[string]string, uris []string, action Act
 // accumulate stores a value, joining repeatable List options with newlines.
 func accumulate(vals map[string]string, o *Opt, val string) {
 	if o.Kind == List {
-		if prev, ok := vals[o.Long]; ok {
+		vals[o.Long] = appendList(vals[o.Long], val)
-			vals[o.Long] = prev + "\n" + val
 		return
 	}
-	}
 	vals[o.Long] = val
 }
 
+// appendList is the single home of the List newline-join rule, shared by the
+// raw-parse layer (accumulate) and the resolved layer (set). An empty prev (the
+// option not yet seen) yields val unchanged, so the first value carries no
+// leading newline.
+func appendList(prev, val string) string {
+	if prev == "" {
+		return val
+	}
+	return prev + "\n" + val
+}
+
 func applyDefaults(o *Options) {
 	for i := range options {
 		opt := &options[i]
@@ -191,86 +224,73 @@ func applyConfig(o *Options, path string, explicit bool) error {
 	return sc.Err()
 }
 
-// applyEnv folds the conventional proxy environment variables into all-proxy
+// set stores a raw value, marking the option as explicitly set. Validation and
-// unless it was already set explicitly.
+// conversion happen later, once, in finalize(); set only records the string.
-func applyEnv(o *Options) {
-	if o.set["all-proxy"] {
-		return
-	}
-	for _, key := range []string{"all_proxy", "https_proxy", "http_proxy"} {
-		if v := os.Getenv(key); v != "" {
-			o.vals["all-proxy"] = v
-			return
-		}
-	}
-}
-
-// set validates a value against its option descriptor and stores it, marking
-// the option as explicitly set.
 func set(o *Options, name, val string) error {
 	opt := byLong[name]
 	if opt == nil {
 		return fmt.Errorf("unknown option %q", name)
 	}
-	if err := validate(opt, val); err != nil {
+	if opt.Kind == List && o.set[name] {
-		return err
+		val = appendList(o.vals[name], val)
-	}
-	if opt.Kind == List {
-		if prev, ok := o.vals[name]; ok && o.set[name] {
-			val = prev + "\n" + val
-		}
 	}
 	o.vals[name] = val
 	o.set[name] = true
 	return nil
 }
 
-func validate(o *Opt, val string) error {
+// parseValue converts a raw string to the typed value for o.Kind, validating it
+// in the process: it is the single place a value is parsed. Bool/Int/Size/Float
+// return their typed value (read back by the getters); Str/List/Enum need no
+// stored conversion and return nil, with Enum still checked for membership.
+func parseValue(o *Opt, val string) (any, error) {
 	switch o.Kind {
 	case Bool:
-		// Booleans accept true/false plus the yes/no/1/0/on/off spellings, but
+		// Booleans accept exactly true/false (the boolWords vocabulary the Bool
-		// nothing else, so e.g. --enable-dht=flase is a parse error. The accepted
+		// getter honours); --enable-dht=flase is a parse error.
-		// set is boolWords, the same vocabulary the readers honour.
+		v, ok := boolWord(val)
-		if _, ok := boolWord(val); !ok {
+		if !ok {
-			return fmt.Errorf("--%s: %q is not a boolean (true/false)", o.Long, val)
+			return nil, fmt.Errorf("--%s: %q is not a boolean (true/false)", o.Long, val)
 		}
+		return v, nil
 	case Int:
 		n, err := strconv.ParseInt(strings.TrimSpace(val), 10, 64)
 		if err != nil {
-			return fmt.Errorf("--%s: %q is not an integer", o.Long, val)
+			return nil, fmt.Errorf("--%s: %q is not an integer", o.Long, val)
 		}
 		if err := checkBounds(o, n); err != nil {
-			return err
+			return nil, err
 		}
+		return n, nil
 	case Size:
 		n, err := parseSize(val)
 		if err != nil {
-			return fmt.Errorf("--%s: %v", o.Long, err)
+			return nil, fmt.Errorf("--%s: %v", o.Long, err)
 		}
 		if err := checkBounds(o, n); err != nil {
-			return err
+			return nil, err
 		}
+		return n, nil
 	case Float:
-		// seed-time and seed-ratio are both rates/durations that must be
+		// seed-time and seed-ratio must be non-negative: a negative SeedTime would
-		// non-negative; a negative SeedTime would fire the seed timer immediately
+		// fire the seed timer immediately and a negative SeedRatio is meaningless.
-		// and a negative SeedRatio is silently ignored. Reject negatives here.
-		// Opt.Min/Max are int64, so we only enforce the floor, not full bounds.
 		f, err := strconv.ParseFloat(strings.TrimSpace(val), 64)
 		if err != nil {
-			return fmt.Errorf("--%s: %q is not a number", o.Long, val)
+			return nil, fmt.Errorf("--%s: %q is not a number", o.Long, val)
 		}
 		if f < 0 {
-			return fmt.Errorf("--%s: %v below minimum 0", o.Long, f)
+			return nil, fmt.Errorf("--%s: %v below minimum 0", o.Long, f)
 		}
+		return f, nil
 	case Enum:
 		for _, e := range o.Enum {
 			if val == e {
-				return nil
+				return nil, nil
 			}
 		}
-		return fmt.Errorf("--%s: %q not one of %s", o.Long, val, strings.Join(o.Enum, "|"))
+		return nil, fmt.Errorf("--%s: %q not one of %s", o.Long, val, strings.Join(o.Enum, "|"))
 	}
-	return nil
+	return nil, nil
 }
 
 // checkBounds enforces an Int/Size option's numeric range. Min defaults to a
@@ -304,8 +324,3 @@ func confPath(explicit string) (path string, fromUser bool) {
 	}
 	return filepath.Join(home, ".config", "got", "got.conf"), false
 }
-
-func truthy(s string) bool {
-	val, _ := boolWord(s)
-	return val
-}

cli/parse_test.go

@@ -13,7 +13,7 @@ func TestParseArgs(t *testing.T) {
 		wantVal map[string]string
 		uris    []string
 	}{
-		{"short attached", []string{"-x16", "https://e.com"}, Run, map[string]string{"max-connection-per-server": "16"}, []string{"https://e.com"}},
+		{"short attached", []string{"-m3", "https://e.com"}, Run, map[string]string{"max-tries": "3"}, []string{"https://e.com"}},
 		{"long equals + bool", []string{"--split=8", "-c", "u"}, Run, map[string]string{"split": "8", "continue": "true"}, []string{"u"}},
 		{"long separate value", []string{"--out", "f.bin", "u"}, Run, map[string]string{"out": "f.bin"}, []string{"u"}},
 		{"bool bundle", []string{"-cq", "u"}, Run, map[string]string{"continue": "true", "quiet": "true"}, []string{"u"}},
@@ -22,7 +22,7 @@ func TestParseArgs(t *testing.T) {
 		{"permute flag after uri", []string{"u", "--split=8"}, Run, map[string]string{"split": "8"}, []string{"u"}},
 		{"permute interleaved", []string{"a", "-c", "b", "--quiet"}, Run, map[string]string{"continue": "true", "quiet": "true"}, []string{"a", "b"}},
 		{"dash dash terminator", []string{"--split=8", "--", "--not-a-flag", "u"}, Run, map[string]string{"split": "8"}, []string{"--not-a-flag", "u"}},
-		{"bt metadata timeout", []string{"--bt-metadata-timeout=120", "magnet:x"}, Run, map[string]string{"bt-metadata-timeout": "120"}, []string{"magnet:x"}},
+		{"long int + magnet uri", []string{"--timeout=120", "magnet:x"}, Run, map[string]string{"timeout": "120"}, []string{"magnet:x"}},
 		{"help", []string{"--help"}, ShowHelp, nil, nil},
 		{"help short", []string{"-h"}, ShowHelp, nil, nil},
 		{"version", []string{"-v"}, ShowVersion, nil, nil},
@@ -68,21 +68,6 @@ func TestParseArgsErrors(t *testing.T) {
 	}
 }
 
-// got bounds the magnet metadata fetch by default rather than waiting forever;
-// guard the default value and its zero floor.
-func TestBTMetadataTimeoutDefault(t *testing.T) {
-	o, ok := byLong["bt-metadata-timeout"]
-	if !ok {
-		t.Fatal("bt-metadata-timeout option is missing")
-	}
-	if o.Default != "60" {
-		t.Errorf("bt-metadata-timeout default = %q, want %q", o.Default, "60")
-	}
-	if o.Min != 0 {
-		t.Errorf("bt-metadata-timeout Min = %d, want 0 (reject negatives, allow 0=off)", o.Min)
-	}
-}
-
 func TestParseSize(t *testing.T) {
 	tests := []struct {
 		in   string
@@ -109,73 +94,84 @@ func TestParseSize(t *testing.T) {
 	}
 }
 
-func TestValidateRange(t *testing.T) {
+func TestParseValueRange(t *testing.T) {
-	x := byLong["max-connection-per-server"]
+	// A synthetic bounded Int exercises the Min/Max range check independent of
-	if err := validate(x, "16"); err != nil {
+	// which options happen to carry bounds.
-		t.Errorf("validate 16: %v", err)
+	o := &Opt{Long: "n", Kind: Int, Min: 1, Max: 16}
+	if _, err := parseValue(o, "16"); err != nil {
+		t.Errorf("parseValue 16: %v", err)
 	}
-	if err := validate(x, "99"); err == nil {
+	if _, err := parseValue(o, "99"); err == nil {
-		t.Errorf("validate 99: want out-of-range error")
+		t.Errorf("parseValue 99: want out-of-range error")
+	}
+	if _, err := parseValue(o, "0"); err == nil {
+		t.Errorf("parseValue 0: want below-minimum error")
 	}
 	a := byLong["file-allocation"]
-	if err := validate(a, "bogus"); err == nil {
+	if _, err := parseValue(a, "bogus"); err == nil {
-		t.Errorf("validate enum bogus: want error")
+		t.Errorf("parseValue enum bogus: want error")
 	}
 }
 
-func TestValidateIntFloor(t *testing.T) {
+func TestParseValueIntFloor(t *testing.T) {
-	// Min:0 now enforces a floor of 0: negatives are rejected.
+	// Min:0 enforces a floor of 0: negatives are rejected.
 	m := byLong["max-tries"] // Min 0, "0 = unlimited" runtime meaning preserved
-	if err := validate(m, "0"); err != nil {
+	if _, err := parseValue(m, "0"); err != nil {
-		t.Errorf("validate max-tries 0: %v, want nil (0 stays a valid input)", err)
+		t.Errorf("parseValue max-tries 0: %v, want nil (0 stays a valid input)", err)
 	}
-	if err := validate(m, "-1"); err == nil {
+	if _, err := parseValue(m, "-1"); err == nil {
-		t.Errorf("validate max-tries -1: want below-minimum error")
+		t.Errorf("parseValue max-tries -1: want below-minimum error")
 	}
 }
 
-func TestValidateFloatNonNegative(t *testing.T) {
+func TestParseValueFloatNonNegative(t *testing.T) {
 	// Float options (seed-time, seed-ratio) reject negatives: a negative
 	// SeedTime would fire the seed timer immediately and a negative SeedRatio
 	// is silently ignored, so neither is a meaningful input.
 	for _, name := range []string{"seed-ratio", "seed-time"} {
 		o := byLong[name]
-		if err := validate(o, "-1"); err == nil {
+		if _, err := parseValue(o, "-1"); err == nil {
-			t.Errorf("validate %s -1: want below-minimum error", name)
+			t.Errorf("parseValue %s -1: want below-minimum error", name)
 		}
-		if err := validate(o, "0"); err != nil {
+		if _, err := parseValue(o, "0"); err != nil {
-			t.Errorf("validate %s 0: %v, want nil", name, err)
+			t.Errorf("parseValue %s 0: %v, want nil", name, err)
 		}
-		if err := validate(o, "1.5"); err != nil {
+		if _, err := parseValue(o, "1.5"); err != nil {
-			t.Errorf("validate %s 1.5: %v, want nil", name, err)
+			t.Errorf("parseValue %s 1.5: %v, want nil", name, err)
 		}
 	}
 }
 
-func TestValidateBool(t *testing.T) {
+func TestParseValueBool(t *testing.T) {
 	b := byLong["enable-dht"]
-	for _, ok := range []string{"true", "false", "yes", "no", "1", "0", "on", "off"} {
+	// Only literal true/false are accepted (case-sensitive), with surrounding
-		if err := validate(b, ok); err != nil {
+	// whitespace trimmed.
-			t.Errorf("validate bool %q: %v", ok, err)
+	for _, ok := range []string{"true", "false", " true ", "false\t"} {
+		if _, err := parseValue(b, ok); err != nil {
+			t.Errorf("parseValue bool %q: %v", ok, err)
 		}
 	}
-	if err := validate(b, "flase"); err == nil {
+	// The invented spellings and any case variant must fail.
-		t.Errorf("validate bool flase: want error")
+	for _, bad := range []string{"yes", "no", "1", "0", "on", "off", "flase",
+		"True", "TRUE", "tRuE", "False", "FALSE"} {
+		if _, err := parseValue(b, bad); err == nil {
+			t.Errorf("parseValue bool %q: want error (only true/false accepted)", bad)
+		}
 	}
 }
 
-func TestValidateSizeBounds(t *testing.T) {
+func TestParseValueSizeBounds(t *testing.T) {
-	k := byLong["min-split-size"] // 1M..1024M (no G unit)
+	k := &Opt{Long: "sz", Kind: Size, Min: 1 << 20, Max: 1 << 30} // 1M..1024M
-	if err := validate(k, "20M"); err != nil {
+	if _, err := parseValue(k, "20M"); err != nil {
-		t.Errorf("validate min-split-size 20M: %v", err)
+		t.Errorf("parseValue 20M: %v", err)
 	}
-	if err := validate(k, "512K"); err == nil {
+	if _, err := parseValue(k, "512K"); err == nil {
-		t.Errorf("validate min-split-size 512K: want below-minimum error")
+		t.Errorf("parseValue 512K: want below-minimum error")
 	}
 	// 1025M exceeds the 1<<30 cap and still parses, so it tests the bounds path
 	// (where "2G" would have failed earlier as an unknown unit).
-	if err := validate(k, "1025M"); err == nil {
+	if _, err := parseValue(k, "1025M"); err == nil {
-		t.Errorf("validate min-split-size 1025M: want above-maximum error")
+		t.Errorf("parseValue 1025M: want above-maximum error")
 	}
 }
 
@@ -213,14 +209,17 @@ func TestExplicitConfMissingFatal(t *testing.T) {
 func TestOptionsGetters(t *testing.T) {
 	o := newOptions()
 	o.vals["split"] = "8"
-	o.vals["min-split-size"] = "20M"
+	o.vals["max-overall-download-limit"] = "20M"
 	o.vals["continue"] = "true"
 	o.vals["seed-ratio"] = "1.5"
+	if err := o.finalize(); err != nil { // parse the raw values once, as Parse does
+		t.Fatalf("finalize: %v", err)
+	}
 	if o.Int("split") != 8 {
 		t.Errorf("Int split = %d", o.Int("split"))
 	}
-	if o.Size("min-split-size") != 20<<20 {
+	if o.Size("max-overall-download-limit") != 20<<20 {
-		t.Errorf("Size min-split-size = %d", o.Size("min-split-size"))
+		t.Errorf("Size max-overall-download-limit = %d", o.Size("max-overall-download-limit"))
 	}
 	if !o.Bool("continue") {
 		t.Errorf("Bool continue = false")

download/download.go

@@ -55,9 +55,6 @@ type Stat struct {
 	Seeders   int   // connected seeders (BitTorrent only)
 }
 
-// Done reports whether the download has reached a terminal state.
-func (s Stat) Done() bool { return s.Status == Complete || s.Status == Errored }
-
 // A Download is one logical job: a URL, a torrent, a magnet. Run blocks in its
 // own goroutine until the work finishes, fails, or ctx is cancelled. Stat may
 // be called concurrently at any time and must not block; implementations back
@@ -67,3 +64,14 @@ type Download interface {
 	Run(ctx context.Context) error
 	Stat() Stat
 }
+
+// Seeder is an optional capability of a Download whose work continues after its
+// content is fully downloaded — a torrent that keeps running to seed.
+// SeedingStarted is closed at that download->seed transition. The engine uses it
+// to free the concurrency slot the moment a download stops downloading: a
+// seed-only torrent is no longer a download, so it must not count against
+// --max-concurrent-downloads (-j) and block a queued download. HTTP downloads do
+// not implement this, so they hold their slot until they finish.
+type Seeder interface {
+	SeedingStarted() <-chan struct{}
+}

download/engine.go

@@ -46,6 +46,12 @@ func (e *Engine) Run(ctx context.Context, downloads []Download) []Result {
 		go func(i int, d Download) {
 			defer wg.Done()
 
+			// Track immediately so a download still queued for a concurrency slot
+			// is visible to the progress reporter as Waiting, rather than hidden
+			// until it starts running.
+			e.track(d)
+			defer e.untrack(d)
+
 			// Acquire a concurrency slot, or bail if we're shutting down
 			// before this download ever started.
 			select {
@@ -54,10 +60,24 @@ func (e *Engine) Run(ctx context.Context, downloads []Download) []Result {
 				results <- Result{Name: d.Name(), Index: i, Err: ctx.Err(), Stat: d.Stat()}
 				return
 			}
-			defer func() { <-slots }()
+			// Release the slot exactly once — whether the download finishes or, for
-
+			// a torrent, first detaches into seed-only. A seeding torrent is no
-			e.track(d)
+			// longer downloading, so it stops counting against -j and lets a queued
-			defer e.untrack(d)
+			// download start; this goroutine lives on to seed.
+			var once sync.Once
+			release := func() { once.Do(func() { <-slots }) }
+			defer release()
+			if s, ok := d.(Seeder); ok {
+				done := make(chan struct{})
+				defer close(done)
+				go func() {
+					select {
+					case <-s.SeedingStarted():
+						release()
+					case <-done:
+					}
+				}()
+			}
 
 			err := d.Run(ctx)
 			results <- Result{Name: d.Name(), Index: i, Err: err, Stat: d.Stat()}
@@ -74,7 +94,8 @@ func (e *Engine) Run(ctx context.Context, downloads []Download) []Result {
 	return out
 }
 
-// Snapshot returns a Stat for every currently running download.
+// Snapshot returns a Stat for every tracked download — those running plus those
+// still queued for a concurrency slot (reported as Waiting).
 func (e *Engine) Snapshot() []Stat {
 	e.mu.Lock()
 	defer e.mu.Unlock()
@@ -91,6 +112,10 @@ func (e *Engine) track(d Download) {
 	e.mu.Unlock()
 }
 
+// untrack removes d from the active set. Every Download implementation is a
+// pointer type, so the == compares identities — never the fields of a value,
+// which could panic on a non-comparable one. (Keying on Stat().ID is not an
+// option: a torrent's ID changes from source to infohash once metadata loads.)
 func (e *Engine) untrack(d Download) {
 	e.mu.Lock()
 	defer e.mu.Unlock()

download/engine_test.go

@@ -0,0 +1,107 @@
+package download
+
+import (
+	"context"
+	"testing"
+	"time"
+)
+
+// fakeDownload is a Download that blocks in Run until released, and (optionally)
+// announces a download->seed transition so the engine can free its -j slot.
+type fakeDownload struct {
+	name    string
+	started chan struct{} // closed when Run begins
+	seeding chan struct{} // SeedingStarted signal
+	release chan struct{} // Run returns once this is closed
+	detach  bool          // if set, Run signals seeding right after starting
+}
+
+func newFake(name string, detach bool) *fakeDownload {
+	return &fakeDownload{
+		name:    name,
+		started: make(chan struct{}),
+		seeding: make(chan struct{}),
+		release: make(chan struct{}),
+		detach:  detach,
+	}
+}
+
+func (f *fakeDownload) Name() string                    { return f.name }
+func (f *fakeDownload) Stat() Stat                      { return Stat{Name: f.name} }
+func (f *fakeDownload) SeedingStarted() <-chan struct{} { return f.seeding }
+
+func (f *fakeDownload) Run(ctx context.Context) error {
+	close(f.started)
+	if f.detach {
+		close(f.seeding)
+	}
+	select {
+	case <-f.release:
+		return nil
+	case <-ctx.Done():
+		return ctx.Err()
+	}
+}
+
+func started(f *fakeDownload, d time.Duration) bool {
+	select {
+	case <-f.started:
+		return true
+	case <-time.After(d):
+		return false
+	}
+}
+
+// A torrent that has finished downloading and is now seeding must not keep
+// occupying a -j slot: with -j 1, a seeding download has to let a queued one run.
+func TestEngineSeedingFreesSlot(t *testing.T) {
+	eng := NewEngine(1)
+	a := newFake("a", true)
+	b := newFake("b", true)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	done := make(chan []Result, 1)
+	go func() { done <- eng.Run(ctx, []Download{a, b}) }()
+
+	// Neither is ever released, yet both must start: each frees the single slot
+	// the instant it detaches into seeding.
+	if !started(a, time.Second) || !started(b, time.Second) {
+		t.Fatal("both downloads should start once seeding frees the -j slot")
+	}
+	close(a.release)
+	close(b.release)
+	<-done
+}
+
+// Control: without a seeding transition, -j 1 still serializes — the second
+// download waits for the first to finish before it starts.
+func TestEngineLimitsConcurrentDownloads(t *testing.T) {
+	eng := NewEngine(1)
+	a := newFake("a", false)
+	b := newFake("b", false)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	done := make(chan []Result, 1)
+	go func() { done <- eng.Run(ctx, []Download{a, b}) }()
+
+	var first, second *fakeDownload
+	select {
+	case <-a.started:
+		first, second = a, b
+	case <-b.started:
+		first, second = b, a
+	case <-time.After(time.Second):
+		t.Fatal("one download should start")
+	}
+	if started(second, 100*time.Millisecond) {
+		t.Fatal("second download must not start while the only slot is held")
+	}
+	close(first.release) // first finishes, freeing the slot
+	if !started(second, time.Second) {
+		t.Fatal("second download should start after the first frees the slot")
+	}
+	close(second.release)
+	<-done
+}

go.mod

@@ -3,7 +3,7 @@ module github.com/hanbok/got
 go 1.25
 
 require (
-	github.com/anacrolix/missinggo/v2 v2.10.0
+	github.com/anacrolix/log v0.17.1-0.20251118025802-918f1157b7bb
 	github.com/anacrolix/torrent v1.61.0
 	golang.org/x/sys v0.38.0
 	golang.org/x/term v0.37.0
@@ -19,9 +19,9 @@ require (
 	github.com/anacrolix/envpprof v1.4.0 // indirect
 	github.com/anacrolix/generics v0.1.1-0.20251125230353-15d98d46693b // indirect
 	github.com/anacrolix/go-libutp v1.3.2 // indirect
-	github.com/anacrolix/log v0.17.1-0.20251118025802-918f1157b7bb // indirect
 	github.com/anacrolix/missinggo v1.3.0 // indirect
 	github.com/anacrolix/missinggo/perf v1.0.0 // indirect
+	github.com/anacrolix/missinggo/v2 v2.10.0 // indirect
 	github.com/anacrolix/mmsg v1.0.1 // indirect
 	github.com/anacrolix/multiless v0.4.0 // indirect
 	github.com/anacrolix/stm v0.5.0 // indirect

httpdl/ca_test.go

@@ -1,22 +0,0 @@
-package httpdl
-
-import (
-	"os"
-	"path/filepath"
-	"testing"
-)
-
-func TestLoadCAPool(t *testing.T) {
-	// A missing file is an error, not a silent fall-back to the system roots.
-	if _, err := loadCAPool(filepath.Join(t.TempDir(), "absent.pem")); err == nil {
-		t.Errorf("loadCAPool(missing): want error")
-	}
-	// A file with no PEM certificates is an error (AppendCertsFromPEM found none).
-	bad := filepath.Join(t.TempDir(), "bad.pem")
-	if err := os.WriteFile(bad, []byte("not a certificate\n"), 0o644); err != nil {
-		t.Fatal(err)
-	}
-	if _, err := loadCAPool(bad); err == nil {
-		t.Errorf("loadCAPool(garbage): want error (no certificates)")
-	}
-}

httpdl/conditional_test.go

@@ -1,97 +0,0 @@
-package httpdl
-
-import (
-	"context"
-	"net/http"
-	"net/http/httptest"
-	"os"
-	"path/filepath"
-	"testing"
-
-	"github.com/hanbok/got/download"
-)
-
-// TestConditionalGet304 checks that --conditional-get sends If-Modified-Since
-// for an existing local file and treats a 304 as success without rewriting the
-// file.
-func TestConditionalGet304(t *testing.T) {
-	dir := t.TempDir()
-	out := filepath.Join(dir, "file.bin")
-	const existing = "already here"
-	if err := os.WriteFile(out, []byte(existing), 0o644); err != nil {
-		t.Fatal(err)
-	}
-
-	gotIfModSince := false
-	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if r.Header.Get("If-Modified-Since") != "" {
-			gotIfModSince = true
-		}
-		w.WriteHeader(http.StatusNotModified)
-	}))
-	defer srv.Close()
-
-	d := New([]string{srv.URL + "/file.bin"}, Config{
-		Dir:              dir,
-		Out:              "file.bin",
-		MaxConnPerServer: 1,
-		ConditionalGet:   true,
-		AllowOverwrite:   true,
-		UserAgent:        "got-test",
-	})
-	if err := d.Run(context.Background()); err != nil {
-		t.Fatalf("conditional-get 304 should succeed, got %v", err)
-	}
-	if !gotIfModSince {
-		t.Fatal("expected an If-Modified-Since header on the request")
-	}
-	if d.Stat().Status != download.Complete {
-		t.Fatalf("status = %v, want Complete", d.Stat().Status)
-	}
-	// The file must be untouched: 304 means "up to date".
-	b, err := os.ReadFile(out)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if string(b) != existing {
-		t.Fatalf("file was rewritten: %q, want %q", b, existing)
-	}
-}
-
-// TestConditionalGetSkippedWithControlFile verifies the rule that
-// --conditional-get is ignored when a .got control file exists, so an
-// in-progress resume is never short-circuited by a 304.
-func TestConditionalGetSkippedWithControlFile(t *testing.T) {
-	dir := t.TempDir()
-	out := filepath.Join(dir, "file.bin")
-	if err := os.WriteFile(out, []byte("partial"), 0o644); err != nil {
-		t.Fatal(err)
-	}
-	// A control file present means a resume is in flight.
-	if err := os.WriteFile(controlPath(out), []byte("{}"), 0o644); err != nil {
-		t.Fatal(err)
-	}
-
-	sawIfModSince := false
-	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
-		if r.Header.Get("If-Modified-Since") != "" {
-			sawIfModSince = true
-		}
-		// Serve a small body so the run can complete.
-		http.Error(w, "no range", http.StatusOK)
-	}))
-	defer srv.Close()
-
-	d := New([]string{srv.URL + "/file.bin"}, Config{
-		Dir:              dir,
-		Out:              "file.bin",
-		MaxConnPerServer: 1,
-		ConditionalGet:   true,
-		AllowOverwrite:   true,
-		UserAgent:        "got-test",
-	})
-	_ = d.Run(context.Background())
-	if sawIfModSince {
-		t.Fatal("If-Modified-Since must not be sent when a control file exists")
-	}
-}

httpdl/control.go

@@ -27,7 +27,9 @@ type segState struct {
 
 func controlPath(out string) string { return out + ".got" }
 
-// snapshot builds a control record from the live segments.
+// snapshot builds a control record from the live segments. The segment slice is
+// fixed once the file is divided and each segment's frontier is owned by one
+// worker, so reading written atomically gives a consistent record with no lock.
 func snapshot(url string, total int64, etag, lastmod string, segs []seg) control {
 	c := control{URL: url, Total: total, ETag: etag, LastModified: lastmod, Segs: make([]segState, len(segs))}
 	for i := range segs {
@@ -73,7 +75,34 @@ func loadControl(out, url string, total int64, etag, lastmod string) *control {
 	if (lastmod != "" || c.LastModified != "") && c.LastModified != lastmod {
 		return nil
 	}
+	// Reject a control file whose segments do not exactly tile [0,total): a
+	// truncated/corrupted/hand-edited sidecar that still parses as JSON could
+	// otherwise mark a segment done() without its bytes on disk (inflated Written)
+	// or leave an un-downloaded hole, both of which would be reported as a complete
+	// file. We restart cleanly instead of trusting it.
+	if !validSegs(c.Segs, c.Total) {
+		return nil
+	}
 	return &c
 }
 
+// validSegs reports whether segs cover [0,total) with no gap or overlap and a
+// sane written count for each. got always writes segments in ascending start
+// order, so coverage is checked in place; an out-of-order sidecar (only possible
+// from a hand-edited or corrupted file) is rejected, which restarts cleanly.
+func validSegs(segs []segState, total int64) bool {
+	if total <= 0 || len(segs) == 0 {
+		return false
+	}
+	var next int64
+	for _, s := range segs {
+		length := s.End - s.Start + 1
+		if s.Start != next || s.End < s.Start || s.Written < 0 || s.Written > length {
+			return false
+		}
+		next = s.End + 1
+	}
+	return next == total
+}
+
 func removeControl(out string) { os.Remove(controlPath(out)) }

httpdl/cookies.go

@@ -1,177 +0,0 @@
-package httpdl
-
-import (
-	"bufio"
-	"fmt"
-	"math"
-	"net/http"
-	"net/http/cookiejar"
-	"net/url"
-	"os"
-	"strconv"
-	"strings"
-	"time"
-)
-
-// Cookie handling implements the --load-cookies / --save-cookies options, which
-// read and write the Netscape/Mozilla cookies.txt format (one tab-separated
-// cookie per line). We back it with the standard net/http/cookiejar so the
-// http.Client applies and tracks Set-Cookie headers automatically; the file
-// format is just the on-disk representation of that jar.
-
-// loadCookieJar builds a cookie jar seeded from a Netscape cookies.txt file. A
-// missing file yields an empty jar (not an error): there are simply no cookies
-// to load. A malformed line is skipped, giving per-line tolerance.
-func loadCookieJar(path string) (*cookiejar.Jar, error) {
-	jar, err := cookiejar.New(nil)
-	if err != nil {
-		return nil, err
-	}
-	if path == "" {
-		return jar, nil
-	}
-	f, err := os.Open(path)
-	if err != nil {
-		if os.IsNotExist(err) {
-			return jar, nil // nothing to load yet
-		}
-		return nil, fmt.Errorf("load-cookies %s: %w", path, err)
-	}
-	defer f.Close()
-
-	// Group cookies by the URL their domain implies, since SetCookies keys on a
-	// URL. We synthesise a representative URL per (domain, secure, path).
-	byURL := map[string][]*http.Cookie{}
-	urls := map[string]*url.URL{}
-	sc := bufio.NewScanner(f)
-	for sc.Scan() {
-		line := sc.Text()
-		c, u := parseNetscapeCookie(line)
-		if c == nil {
-			continue
-		}
-		key := u.String()
-		if _, ok := urls[key]; !ok {
-			urls[key] = u
-		}
-		byURL[key] = append(byURL[key], c)
-	}
-	if err := sc.Err(); err != nil {
-		return nil, fmt.Errorf("load-cookies %s: %w", path, err)
-	}
-	for key, cs := range byURL {
-		jar.SetCookies(urls[key], cs)
-	}
-	return jar, nil
-}
-
-// parseNetscapeCookie parses one cookies.txt line into a cookie plus the URL it
-// belongs to, or (nil, nil) for a comment, blank or malformed line. The format
-// is seven tab-separated fields:
-//
-//	domain  includeSubdomains  path  secure  expiry  name  value
-//
-// Curl marks HttpOnly cookies with a "#HttpOnly_" line prefix rather than a
-// real comment, so we recognise that prefix instead of dropping the line.
-// Honouring HttpOnly_ rather than skipping every "#" line never loses a cookie.
-func parseNetscapeCookie(line string) (*http.Cookie, *url.URL) {
-	httpOnly := false
-	if strings.HasPrefix(line, "#HttpOnly_") {
-		httpOnly = true
-		line = strings.TrimPrefix(line, "#HttpOnly_")
-	} else if strings.HasPrefix(line, "#") {
-		return nil, nil
-	}
-	if strings.TrimSpace(line) == "" {
-		return nil, nil
-	}
-	f := strings.Split(line, "\t")
-	if len(f) < 6 {
-		return nil, nil
-	}
-	domain := f[0]
-	hostOnly := !strings.EqualFold(f[1], "TRUE")
-	path := f[2]
-	secure := strings.EqualFold(f[3], "TRUE")
-	name := f[5]
-	value := ""
-	if len(f) >= 7 {
-		value = f[6]
-	}
-	if name == "" || domain == "" {
-		return nil, nil
-	}
-
-	c := &http.Cookie{
-		Name:     name,
-		Value:    value,
-		Path:     path,
-		Secure:   secure,
-		HttpOnly: httpOnly,
-	}
-	// A non-host-only cookie (includeSubdomains TRUE) carries a Domain attribute
-	// so the jar applies it to subdomains; a host-only one leaves Domain empty so
-	// the jar binds it to the exact request host.
-	if !hostOnly {
-		c.Domain = domain
-	}
-	// expiry 0 means a session cookie; otherwise it is a Unix timestamp. The jar
-	// drops already-expired cookies on load.
-	if exp, err := strconv.ParseInt(strings.TrimSpace(f[4]), 10, 64); err == nil && exp > 0 {
-		c.Expires = time.Unix(exp, 0)
-	}
-
-	// The jar needs a URL whose host and scheme match the cookie. A leading dot
-	// denotes a domain cookie; strip it for the host but keep the cookie Domain
-	// so the jar treats it as domain-wide.
-	host := strings.TrimPrefix(domain, ".")
-	scheme := "http"
-	if secure {
-		scheme = "https"
-	}
-	u := &url.URL{Scheme: scheme, Host: host, Path: path}
-	return c, u
-}
-
-// saveCookieJar writes every cookie the jar holds (for the hosts we have
-// contacted) back to path in Netscape format, implementing --save-cookies on
-// exit. Because net/http/cookiejar exposes cookies only per URL, we ask it for
-// the cookies of each host we recorded a request against.
-func saveCookieJar(jar *cookiejar.Jar, urls []*url.URL, path string) error {
-	if path == "" || jar == nil {
-		return nil
-	}
-	var b strings.Builder
-	b.WriteString("# Netscape HTTP Cookie File\n")
-	seen := map[string]bool{}
-	for _, u := range urls {
-		for _, c := range jar.Cookies(u) {
-			// Cookies() drops the domain/path/expiry, so reconstruct sensible
-			// values: host-only domain, root path, far-future expiry. This is the
-			// best a host-only readback can do; it round-trips the name/value pair
-			// that authenticated downloads actually need.
-			key := u.Host + "\x00" + c.Name
-			if seen[key] {
-				continue
-			}
-			seen[key] = true
-			expiry := int64(math.MaxInt32) // session-stable far future
-			line := strings.Join([]string{
-				u.Host, "FALSE", "/",
-				boolToTRUE(u.Scheme == "https"),
-				strconv.FormatInt(expiry, 10),
-				c.Name, c.Value,
-			}, "\t")
-			b.WriteString(line)
-			b.WriteByte('\n')
-		}
-	}
-	return os.WriteFile(path, []byte(b.String()), 0o600)
-}
-
-func boolToTRUE(b bool) string {
-	if b {
-		return "TRUE"
-	}
-	return "FALSE"
-}

httpdl/cookies_test.go

@@ -1,126 +0,0 @@
-package httpdl
-
-import (
-	"net/http"
-	"os"
-	"path/filepath"
-	"strconv"
-	"testing"
-	"time"
-)
-
-func TestParseNetscapeCookie(t *testing.T) {
-	future := time.Now().Add(24 * time.Hour).Unix()
-	tests := []struct {
-		name      string
-		line      string
-		wantNil   bool
-		wantName  string
-		wantValue string
-		wantDom   string // expected http.Cookie.Domain (empty for host-only)
-		wantHTTP  bool
-	}{
-		{
-			name:      "domain cookie",
-			line:      ".example.com\tTRUE\t/\tFALSE\t" + itoa(future) + "\tSID\tabc123",
-			wantName:  "SID",
-			wantValue: "abc123",
-			wantDom:   ".example.com",
-		},
-		{
-			name:      "host-only cookie",
-			line:      "example.com\tFALSE\t/\tTRUE\t" + itoa(future) + "\ttoken\txyz",
-			wantName:  "token",
-			wantValue: "xyz",
-			wantDom:   "", // host-only: no Domain attribute
-		},
-		{
-			name:      "httponly prefix kept",
-			line:      "#HttpOnly_example.com\tFALSE\t/\tFALSE\t" + itoa(future) + "\tHO\tsecret",
-			wantName:  "HO",
-			wantValue: "secret",
-			wantHTTP:  true,
-		},
-		{
-			name:      "empty value field",
-			line:      "example.com\tFALSE\t/\tFALSE\t0\tflag\t",
-			wantName:  "flag",
-			wantValue: "",
-		},
-		{
-			name:    "comment line",
-			line:    "# this is a comment",
-			wantNil: true,
-		},
-		{
-			name:    "blank line",
-			line:    "   ",
-			wantNil: true,
-		},
-		{
-			name:    "too few fields",
-			line:    "example.com\tFALSE\t/\tFALSE\t0",
-			wantNil: true,
-		},
-	}
-	for _, tc := range tests {
-		t.Run(tc.name, func(t *testing.T) {
-			c, u := parseNetscapeCookie(tc.line)
-			if tc.wantNil {
-				if c != nil {
-					t.Fatalf("expected nil cookie, got %+v", c)
-				}
-				return
-			}
-			if c == nil {
-				t.Fatal("expected a cookie, got nil")
-			}
-			if c.Name != tc.wantName || c.Value != tc.wantValue {
-				t.Fatalf("name/value = %q/%q, want %q/%q", c.Name, c.Value, tc.wantName, tc.wantValue)
-			}
-			if c.Domain != tc.wantDom {
-				t.Fatalf("domain = %q, want %q", c.Domain, tc.wantDom)
-			}
-			if c.HttpOnly != tc.wantHTTP {
-				t.Fatalf("httponly = %v, want %v", c.HttpOnly, tc.wantHTTP)
-			}
-			if u == nil {
-				t.Fatal("expected a URL, got nil")
-			}
-		})
-	}
-}
-
-func itoa(n int64) string   { return strconv.FormatInt(n, 10) }
-func itoa64(n int64) string { return strconv.FormatInt(n, 10) }
-
-func TestLoadCookieJarMissingFile(t *testing.T) {
-	// A missing cookies file is not an error: there are simply no cookies to load.
-	jar, err := loadCookieJar(filepath.Join(t.TempDir(), "nope.txt"))
-	if err != nil {
-		t.Fatalf("missing file should not error: %v", err)
-	}
-	if jar == nil {
-		t.Fatal("expected an empty jar, got nil")
-	}
-}
-
-func TestLoadCookieJarAppliesCookie(t *testing.T) {
-	dir := t.TempDir()
-	path := filepath.Join(dir, "cookies.txt")
-	future := time.Now().Add(24 * time.Hour).Unix()
-	data := "# Netscape HTTP Cookie File\n" +
-		".example.com\tTRUE\t/\tFALSE\t" + itoa64(future) + "\tSID\tabc123\n"
-	if err := os.WriteFile(path, []byte(data), 0o600); err != nil {
-		t.Fatal(err)
-	}
-	jar, err := loadCookieJar(path)
-	if err != nil {
-		t.Fatal(err)
-	}
-	req, _ := http.NewRequest(http.MethodGet, "http://www.example.com/file", nil)
-	got := jar.Cookies(req.URL)
-	if len(got) != 1 || got[0].Name != "SID" || got[0].Value != "abc123" {
-		t.Fatalf("jar did not apply the domain cookie to a subdomain: %+v", got)
-	}
-}

httpdl/httpdl.go

@@ -1,6 +1,6 @@
 // Package httpdl downloads a single HTTP(S) resource over one or more
 // connections. The model is deliberately flat: split the file into byte-range
-// segments, hand them to a pool of worker goroutines, and have each worker
+// segments, give each segment its own worker goroutine, and have each worker
 // stream its range straight to disk with WriteAt (safe for concurrent,
 // non-overlapping writes — no shared seek, no mutex). Goroutines blocking on
 // real I/O keep the model simple: no segment manager, no piece storage, no
@@ -9,8 +9,6 @@ package httpdl
 
 import (
 	"context"
-	"crypto/tls"
-	"crypto/x509"
 	"errors"
 	"fmt"
 	"hash"
@@ -18,7 +16,6 @@ import (
 	"mime"
 	"net"
 	"net/http"
-	"net/http/cookiejar"
 	"net/url"
 	"os"
 	"path"
@@ -35,6 +32,15 @@ import (
 
 const readBuf = 32 * 1024
 
+// minSplitSize is the smallest piece a file is split into: a segment shorter
+// than this is not worth its own connection, so makeSegments stops dividing once
+// the pieces would fall below it.
+const minSplitSize = 20 << 20
+
+// userAgent is sent on every request; there is no flag to change it. A site that
+// needs a different one can be given a User-Agent header via --header.
+const userAgent = "got/1.0"
+
 // ErrOutputExists reports that the resolved output file already exists and
 // neither --allow-overwrite nor -c was given. main maps it to a distinct exit
 // code via errors.Is, so it must stay on the error chain (CONTRACT).
@@ -45,60 +51,21 @@ var ErrOutputExists = errors.New("output file already exists")
 // (CONTRACT).
 var ErrNotFound = errors.New("not found")
 
-// ErrTooSlow reports a transfer aborted by --lowest-speed-limit. main maps it to
-// exit code 5 via errors.Is, so it must stay on the error chain (CONTRACT).
-var ErrTooSlow = errors.New("download speed too low")
-
 // Config holds everything one HTTP download needs. It is assembled by main from
 // the resolved CLI options.
 type Config struct {
 	Dir            string
 	Out            string
 	Split          int   // --split: total connections across all mirrors
-	MaxConnPerServer int // --max-connection-per-server: per-host connection cap
+	MinSplit       int64 // smallest piece to split into; 0 = minSplitSize default (internal, no flag)
-	MinSplit         int64
+	Tries          int   // --max-tries: 0 = unlimited
-	Tries            int // 0 = unlimited
 	Timeout        time.Duration
 	FileAlloc      string // none | prealloc | trunc | falloc
 	Continue       bool
 	AllowOverwrite bool
 	AutoRename     bool
-	Headers          []string
+	Headers        []string      // --header: extra request headers
-	UserAgent        string
-	Referer          string
-	Proxy            string
-	CheckCert        bool
-	Limit            int64         // per-download bytes/s, 0 = unlimited
 	OverallLimiter *rate.Limiter // shared across all downloads, may be nil
-
-	// RetryWait is the pause between retries of a transient failure
-	// (--retry-wait). 0 means retry immediately with no sleep.
-	RetryWait time.Duration
-	// AutoSaveInterval controls how often the .got control file is rewritten
-	// (--auto-save-interval). <=0 falls back to 60s.
-	AutoSaveInterval time.Duration
-
-	// ConnectTimeout is the time allowed to establish the TCP/TLS connection
-	// (--connect-timeout, default 60s), distinct from Timeout which
-	// covers stalls once data is flowing. <=0 falls back to Timeout.
-	ConnectTimeout time.Duration
-	// LoadCookies / SaveCookies are paths to a Netscape cookies.txt read into
-	// the client's jar before the download and written back on exit.
-	LoadCookies string
-	SaveCookies string
-	// ConditionalGet sends If-Modified-Since (from the existing local file's
-	// mtime) so a 304 reports success without re-downloading
-	// (--conditional-get).
-	ConditionalGet bool
-	// RemoteTime sets the finished file's mtime from the server's Last-Modified
-	// header (-R / --remote-time).
-	RemoteTime bool
-	// HTTPUser / HTTPPasswd enable HTTP Basic auth (--http-user/passwd).
-	HTTPUser   string
-	HTTPPasswd string
-	// LowestSpeedLimit aborts a download whose speed stays at or below this many
-	// bytes/sec for a sustained window (--lowest-speed-limit). 0 = off.
-	LowestSpeedLimit int64
 	// Checksum is a "<type>=<digest>" spec (e.g. "sha-256=ab…"); when set,
 	// the finished file is hashed and compared, failing with ErrChecksum on a
 	// mismatch (--checksum). Empty means no verification.
@@ -106,11 +73,6 @@ type Config struct {
 	// DryRun probes the resource — proving it exists and its size — but downloads
 	// nothing, then reports success (--dry-run).
 	DryRun bool
-	// CACert is a path to a PEM bundle of CA certificates used to verify HTTPS
-	// servers (--ca-certificate). Empty uses the system roots.
-	CACert string
-	// DisableIPv6 forces IPv4-only dialing (--disable-ipv6).
-	DisableIPv6 bool
 }
 
 // Download implements download.Download for one HTTP(S) file, fetched from one
@@ -119,26 +81,21 @@ type Config struct {
 // connections.
 type Download struct {
 	uris     []string // mirror list; uris[0] is the primary (naming + resume key)
-	maxConns int      // segment workers = min(split, len(uris)*max-connection-per-server)
+	maxConns int      // segment-worker cap = min(split, len(uris))
 	cfg      Config
 	client   *http.Client
 	limit    []*rate.Limiter
-	jar      *cookiejar.Jar // non-nil when cookies are in use, for save-cookies
 
 	// name and out are resolved in Run after the probe response is known (the
-	// final post-redirect URL and any Content-Disposition can change them), then
+	// final post-redirect URL and any Content-Disposition can change them). The
-	// never mutated again, so Stat can read name from another goroutine without a
+	// engine publishes a Download to the progress reporter before Run starts, so
-	// lock once Run has set it. They are seeded in New so a Stat before Run still
+	// Stat reads these from the reporter goroutine while resolveName writes them;
-	// has a sensible best-effort name.
+	// they are atomic.Pointer[string] (exactly like bt.Download.name) to keep that
-	name    string
+	// read/write race-free. Seeded in New so a Stat before Run has a best-effort name.
-	out     string
+	name    atomic.Pointer[string]
+	out     atomic.Pointer[string]
 	initErr error
 
-	// mu guards seenURLs, which records every URL we sent a request to so
-	// SaveCookies can ask the jar for the cookies of each contacted host.
-	mu       sync.Mutex
-	seenURLs []*url.URL
-
 	// live counters, read by Stat from any goroutine
 	total     int64 // -1 until known
 	completed int64
@@ -146,21 +103,6 @@ type Download struct {
 	conns     int32 // active connections
 }
 
-// loadCAPool reads a PEM bundle of CA certificates for verifying HTTPS servers
-// (--ca-certificate). An unreadable file or one containing no
-// certificates is an error rather than a silent fall-back to the system roots.
-func loadCAPool(path string) (*x509.CertPool, error) {
-	pem, err := os.ReadFile(path)
-	if err != nil {
-		return nil, err
-	}
-	pool := x509.NewCertPool()
-	if !pool.AppendCertsFromPEM(pem) {
-		return nil, fmt.Errorf("ca-certificate %s: no certificates found", path)
-	}
-	return pool, nil
-}
-
 // primary is the canonical URL — used for naming and the resume sidecar so they
 // stay stable regardless of which mirror served the bytes.
 func (d *Download) primary() string { return d.uris[0] }
@@ -173,82 +115,27 @@ func (d *Download) mirror(n int) string { return d.uris[n%len(d.uris)] }
 // New builds an HTTP download for uris, which must all serve identical content
 // (mirrors). uris[0] is the primary.
 func New(uris []string, cfg Config) *Download {
-	// --connect-timeout bounds only connection establishment; once data flows
-	// --timeout (the idle guard) takes over. The dial and the TLS handshake each
-	// get the full connectTimeout (Go applies it per phase), so an HTTPS connect
-	// can take up to ~2x connectTimeout in the worst case — there is no single
-	// shared connect budget.
-	connectTimeout := cfg.ConnectTimeout
-	if connectTimeout <= 0 {
-		connectTimeout = cfg.Timeout
-	}
 	var initErr error
-
+	if cfg.MinSplit <= 0 {
-	// --ca-certificate: verify HTTPS servers against a custom CA bundle instead of
+		cfg.MinSplit = minSplitSize
-	// the system roots. A bad bundle becomes an initErr so Run fails loudly.
-	tlsCfg := &tls.Config{InsecureSkipVerify: !cfg.CheckCert}
-	if cfg.CACert != "" {
-		if pool, err := loadCAPool(cfg.CACert); err != nil {
-			initErr = err
-		} else {
-			tlsCfg.RootCAs = pool
-		}
 	}
 
-	// --disable-ipv6: force IPv4 by dialing "tcp4"; a plain "tcp" would let the
+	// One connect budget: --timeout bounds both establishing the connection and
-	// resolver hand back a v6 address.
+	// idle stalls once data flows. Proxies still come from the standard
-	dialer := &net.Dialer{Timeout: connectTimeout}
+	// HTTP_PROXY/HTTPS_PROXY environment, and TLS uses the system roots.
-	dialContext := dialer.DialContext
-	if cfg.DisableIPv6 {
-		dialContext = func(ctx context.Context, network, addr string) (net.Conn, error) {
-			if network == "tcp" {
-				network = "tcp4"
-			}
-			return dialer.DialContext(ctx, network, addr)
-		}
-	}
-
-	// MaxConnsPerHost is the per-host cap (--max-connection-per-server): with
-	// mirrors the total worker count can exceed it, but no single host does.
-	perHost := cfg.MaxConnPerServer
-	if perHost < 1 {
-		perHost = 1
-	}
 	tr := &http.Transport{
 		Proxy:                 http.ProxyFromEnvironment,
-		MaxConnsPerHost:       perHost,
+		MaxConnsPerHost:       cfg.Split,
-		MaxIdleConnsPerHost:   perHost,
+		MaxIdleConnsPerHost:   cfg.Split,
 		ResponseHeaderTimeout: cfg.Timeout,
-		TLSHandshakeTimeout:   connectTimeout,
+		TLSHandshakeTimeout:   cfg.Timeout,
-		DialContext:           dialContext,
+		DialContext:           (&net.Dialer{Timeout: cfg.Timeout}).DialContext,
-		TLSClientConfig:       tlsCfg,
-	}
-	if cfg.Proxy != "" {
-		if pu, err := url.Parse(cfg.Proxy); err == nil {
-			tr.Proxy = http.ProxyURL(pu)
-		}
-	}
-
-	// Seed the cookie jar from --load-cookies; a load error becomes an initErr so
-	// Run surfaces it rather than silently downloading uncredentialed.
-	var jar *cookiejar.Jar
-	if cfg.LoadCookies != "" || cfg.SaveCookies != "" {
-		if j, err := loadCookieJar(cfg.LoadCookies); err != nil {
-			if initErr == nil {
-				initErr = err
-			}
-		} else {
-			jar = j
-		}
 	}
 
 	var limit []*rate.Limiter
 	if cfg.OverallLimiter != nil {
 		limit = append(limit, cfg.OverallLimiter)
 	}
-	if cfg.Limit > 0 {
-		limit = append(limit, rate.NewLimiter(rate.Limit(cfg.Limit), download.LimiterBurst(cfg.Limit)))
-	}
 
 	// Seed a best-effort name from -o or the primary URL. The real name is
 	// finalised in Run after probe(), where Content-Disposition and the
@@ -268,47 +155,54 @@ func New(uris []string, cfg Config) *Download {
 	if len(uris) == 0 && initErr == nil {
 		initErr = errors.New("no URL to download")
 	}
-	// Worker count: --split connections are spread across the mirrors, capped
+	// Worker count is --split: the file is cut into that many byte-range segments,
-	// at --max-connection-per-server per host, so the ceiling is
+	// each its own connection, whether served by one host or spread across mirrors.
-	// min(split, M*max-conn-per-server). One mirror reduces to min(split, x).
 	maxConns := cfg.Split
-	if m := max(1, len(uris)) * perHost; maxConns > m {
-		maxConns = m
-	}
 	if maxConns < 1 {
 		maxConns = 1
 	}
 
-	// Only attach the jar when one was built: a typed-nil *cookiejar.Jar stored
+	d := &Download{
-	// in the http.Client.Jar interface is non-nil and would panic on use.
-	client := &http.Client{Transport: tr}
-	if jar != nil {
-		client.Jar = jar
-	}
-
-	return &Download{
 		uris:     uris,
 		maxConns: maxConns,
 		cfg:      cfg,
-		client:   client,
+		client:   &http.Client{Transport: tr},
 		limit:    limit,
-		jar:      jar,
-		name:     name,
-		out:      out,
 		total:    -1,
 		initErr:  initErr,
 	}
+	d.setName(name)
+	d.setOut(out)
+	return d
 }
 
-func (d *Download) Name() string { return d.name }
+func (d *Download) Name() string { return d.loadName() }
 
-// Path returns the resolved output file path (used by --follow-torrent).
+// Path returns the resolved output file path, so a fetched .torrent can be
-func (d *Download) Path() string { return d.out }
+// followed into a BitTorrent download of its content.
+func (d *Download) Path() string { return d.loadOut() }
+
+// name and out are read by Stat from the reporter goroutine while Run resolves
+// them, so they are stored atomically (mirroring bt.Download.name).
+func (d *Download) setName(s string) { d.name.Store(&s) }
+func (d *Download) setOut(s string)  { d.out.Store(&s) }
+func (d *Download) loadName() string {
+	if p := d.name.Load(); p != nil {
+		return *p
+	}
+	return ""
+}
+func (d *Download) loadOut() string {
+	if p := d.out.Load(); p != nil {
+		return *p
+	}
+	return ""
+}
 
 func (d *Download) Stat() download.Stat {
 	return download.Stat{
-		Name:      d.name,
+		Name:      d.loadName(),
-		ID:        d.out, // resolved output path; stable per process (CONTRACT)
+		ID:        d.loadOut(), // resolved output path; stable per process (CONTRACT)
 		IsBT:      false,
 		Status:    download.Status(atomic.LoadInt32(&d.status)),
 		Total:     atomic.LoadInt64(&d.total),
@@ -332,7 +226,6 @@ type probeResult struct {
 	lastmod  string
 	cdisp    string // raw Content-Disposition header
 	finalURL *url.URL
-	notModified bool // server answered 304 to a conditional GET
 }
 
 // Run probes the resource, finalises the output name, decides between a single
@@ -355,12 +248,6 @@ func (d *Download) Run(ctx context.Context) (err error) {
 	if err != nil {
 		return err
 	}
-	// --conditional-get: the server said our local copy is current, so there is
-	// nothing to download. Report success without touching the file.
-	if pr.notModified {
-		d.setStatus(download.Complete)
-		return nil
-	}
 	atomic.StoreInt64(&d.total, pr.total)
 
 	// Finalise name/out now that the post-redirect URL and Content-Disposition
@@ -388,36 +275,22 @@ func (d *Download) Run(ctx context.Context) (err error) {
 		return nil
 	}
 
-	// --lowest-speed-limit: cancel the transfer if its speed stays at or below
+	out := d.loadOut()
-	// the limit past a startup grace. The watcher cancels xferCtx and sets a
-	// flag so we can return the distinct "too slow" error rather than a bare
-	// cancellation.
-	xferCtx, stopGuard, tooSlow := d.speedGuard(ctx)
 	if !pr.ranged || pr.total <= 0 {
-		err = d.single(xferCtx, d.out)
+		err = d.single(ctx, out)
 	} else {
-		err = d.segmented(xferCtx, d.out, pr.total, pr.etag, pr.lastmod)
+		err = d.segmented(ctx, out, pr.total, pr.etag, pr.lastmod)
 	}
-	stopGuard()
 	if err != nil {
-		if tooSlow() {
-			return fmt.Errorf("%s: %w (<= %d bytes/sec)", d.primary(), ErrTooSlow, d.cfg.LowestSpeedLimit)
-		}
 		return err
 	}
 	// --checksum: verify the finished file before declaring success, so a
 	// corrupted or tampered download fails (--checksum, exit code 32).
 	if newSum != nil {
-		if err = verifyFile(d.out, newSum, sumWant); err != nil {
+		if err = verifyFile(out, newSum, sumWant); err != nil {
 			return err
 		}
 	}
-	// -R / --remote-time: stamp the finished file with the server's mtime.
-	if d.cfg.RemoteTime && pr.lastmod != "" {
-		if t, err := http.ParseTime(pr.lastmod); err == nil {
-			os.Chtimes(d.out, t, t)
-		}
-	}
 	d.setStatus(download.Complete)
 	return nil
 }
@@ -427,6 +300,7 @@ func (d *Download) Run(ctx context.Context) (err error) {
 // the original URL. Overwrite / auto-rename is then resolved against the final
 // path, honouring -c so a resumable file is never renamed (items [2],[8],[13]).
 func (d *Download) resolveName(pr probeResult) error {
+	out := d.loadOut()
 	if d.cfg.Out == "" {
 		name := ""
 		if cd := pr.cdisp; cd != "" {
@@ -438,8 +312,9 @@ func (d *Download) resolveName(pr probeResult) error {
 		if name == "" {
 			name = nameFromURL(d.primary())
 		}
-		d.name = name
+		out = filepath.Join(d.cfg.Dir, name)
-		d.out = filepath.Join(d.cfg.Dir, name)
+		d.setName(name)
+		d.setOut(out)
 	}
 
 	// --dry-run writes nothing, so skip overwrite/auto-rename resolution; the name
@@ -450,38 +325,24 @@ func (d *Download) resolveName(pr probeResult) error {
 
 	// -c resumes either our own .got sidecar or a foreign/browser partial file,
 	// so an existing file is never auto-renamed under -c (item [2]).
-	if d.cfg.Continue && fileExists(d.out) {
+	if d.cfg.Continue && fileExists(out) {
 		return nil
 	}
-	if fileExists(d.out) && !d.cfg.AllowOverwrite {
+	if fileExists(out) && !d.cfg.AllowOverwrite {
 		if d.cfg.AutoRename {
-			u, err := uniqueName(d.out)
+			u, err := uniqueName(out)
 			if err != nil {
 				return err
 			}
-			d.out = u
+			d.setOut(u)
-			d.name = filepath.Base(u)
+			d.setName(filepath.Base(u))
 			return nil
 		}
-		return fmt.Errorf("%s: %w (use --allow-overwrite or -c)", d.out, ErrOutputExists)
+		return fmt.Errorf("%s: %w (use --allow-overwrite or -c)", out, ErrOutputExists)
 	}
 	return nil
 }
 
-// backoff waits RetryWait between attempts, but never after the final attempt,
-// and returns ctx.Err() if cancelled while waiting (item [20]).
-func backoff(ctx context.Context, wait time.Duration, tries, attempt int) error {
-	if wait <= 0 || (tries != 0 && attempt >= tries-1) {
-		return nil
-	}
-	select {
-	case <-ctx.Done():
-		return ctx.Err()
-	case <-time.After(wait):
-		return nil
-	}
-}
-
 // retriesExhausted wraps the final cause once the retry budget is spent, so the
 // caller — and the exit-code mapping in main — can still see whether it was DNS,
 // a refused connection, or a timeout, rather than an opaque "too many retries".
@@ -499,12 +360,11 @@ func retriesExhausted(what string, tries int, cause error) error {
 }
 
 // withRetries runs attempt up to d.cfg.Tries times (0 = unlimited), the shared
-// tries/backoff/fatal policy that probe, the single stream, and each segment all
+// tries/fatal policy that probe, the single stream, and each segment all use so
-// use so one transient DNS/connect/5xx does not fail the whole download (item
+// one transient DNS/connect/5xx does not fail the whole download (item [18]). It
-// [18]). It returns immediately on success (nil), on context cancellation, or on
+// returns immediately on success (nil), on context cancellation, or on a fatal{}
-// a fatal{} error (retrying cannot help), sleeps RetryWait between attempts, and
+// error (retrying cannot help), and wraps the final cause with retriesExhausted
-// wraps the final cause with retriesExhausted(what, ...) once the budget is
+// once the budget is spent so the underlying cause stays inspectable.
-// spent so the underlying cause stays inspectable.
 func (d *Download) withRetries(ctx context.Context, what string, attempt func() error) error {
 	tries := d.cfg.Tries
 	var lastErr error
@@ -521,37 +381,48 @@ func (d *Download) withRetries(ctx context.Context, what string, attempt func()
 		if errors.As(err, &fe) {
 			return err // permanent: retrying cannot help
 		}
-		if err := backoff(ctx, d.cfg.RetryWait, tries, n); err != nil {
-			return err
-		}
 	}
 	return retriesExhausted(what, tries, lastErr)
 }
 
+// overMirrors calls fn against each mirror URL in turn, starting at offset start
+// so callers can spread work across mirrors (segment index) and rotate on retry.
+// It returns nil on the first success, ctx.Err() if cancelled between mirrors, or
+// the last error once every mirror is spent.
+func (d *Download) overMirrors(ctx context.Context, start int, fn func(uri string) error) error {
+	var lastErr error
+	for i := range d.uris {
+		if ctx.Err() != nil {
+			return ctx.Err()
+		}
+		if err := fn(d.mirror(start + i)); err != nil {
+			lastErr = err
+			continue
+		}
+		return nil
+	}
+	return lastErr
+}
+
 // probeRetry runs probe within the shared retry policy (item [18]). The probe
 // result is captured through pr because withRetries only carries an error.
 func (d *Download) probeRetry(ctx context.Context) (probeResult, error) {
 	// Probe mirrors in order (primary first); the first that answers anchors the
 	// size and validators for the whole download. A dead/404 primary falls over
 	// to the next mirror.
-	var lastErr error
-	for _, u := range d.uris {
-		if ctx.Err() != nil {
-			return probeResult{}, ctx.Err()
-		}
 	var pr probeResult
-		err := d.withRetries(ctx, u, func() error {
+	err := d.overMirrors(ctx, 0, func(uri string) error {
+		return d.withRetries(ctx, uri, func() error {
 			var perr error
-			pr, perr = d.probe(ctx, u)
+			pr, perr = d.probe(ctx, uri)
 			return perr
 		})
-		if err == nil {
+	})
+	if err != nil {
+		return probeResult{}, err
+	}
 	return pr, nil
 }
-		lastErr = err
-	}
-	return probeResult{}, lastErr
-}
 
 // probe issues a one-byte ranged GET to learn the total size, whether the
 // server honours ranges, and the validator headers used for safe resume. It
@@ -561,15 +432,6 @@ func (d *Download) probe(ctx context.Context, uri string) (probeResult, error) {
 	if err != nil {
 		return probeResult{}, err
 	}
-	// --conditional-get: ask the server to skip the transfer when our local file
-	// is already current. Only done when there is no .got control file (an
-	// in-progress resume must not be short-circuited), using the local file's
-	// mtime for If-Modified-Since.
-	if d.cfg.ConditionalGet && !fileExists(controlPath(d.out)) {
-		if fi, err := os.Stat(d.out); err == nil {
-			req.Header.Set("If-Modified-Since", fi.ModTime().UTC().Format(http.TimeFormat))
-		}
-	}
 	resp, err := d.client.Do(req)
 	if err != nil {
 		return probeResult{}, err
@@ -586,11 +448,6 @@ func (d *Download) probe(ctx context.Context, uri string) (probeResult, error) {
 		pr.finalURL = resp.Request.URL
 	}
 
-	if resp.StatusCode == http.StatusNotModified {
-		pr.notModified = true
-		return pr, nil
-	}
-
 	switch resp.StatusCode {
 	case http.StatusPartialContent:
 		// Content-Range: bytes 0-0/12345
@@ -652,37 +509,23 @@ func (d *Download) segmented(ctx context.Context, out string, total int64, etag,
 	saveDone := make(chan struct{})
 	go d.saveLoop(ctx, out, total, etag, lastmod, segs, saveDone)
 
-	jobs := make(chan *seg)
+	// One worker per segment. Segments are non-overlapping byte ranges written
-	go func() {
+	// with WriteAt, so the workers share no cursor and need no coordination — a
-		defer close(jobs)
+	// finished worker simply exits. The division (makeSegments / a resumed
-		for i := range segs {
+	// control) fixes the parallelism up front; there is no rebalancing.
-			if segs[i].done() {
-				continue
-			}
-			select {
-			case jobs <- &segs[i]:
-			case <-ctx.Done(): // stop feeding once we're tearing down
-				return
-			}
-		}
-	}()
-
 	var (
 		wg      sync.WaitGroup
 		errOnce sync.Once
 		runErr  error
 	)
-	for w := 0; w < d.maxConns; w++ {
+	for i := range segs {
 		wg.Add(1)
-		go func() {
+		go func(s *seg) {
 			defer wg.Done()
-			for s := range jobs {
 			if err := d.fetchSeg(ctx, f, s, total); err != nil {
 				errOnce.Do(func() { runErr = err; cancel() })
-					return
 			}
-			}
+		}(&segs[i])
-		}()
 	}
 	wg.Wait()
 	cancel()
@@ -706,24 +549,14 @@ func (d *Download) fetchSeg(ctx context.Context, f *os.File, s *seg, total int64
 	// The segment fails only once every mirror is spent. Starting at s.index
 	// spreads the segments across mirrors round-robin, and each attempt resumes
 	// from s.offset().
-	var lastErr error
+	return d.overMirrors(ctx, s.index, func(uri string) error {
-	for i := range d.uris {
+		return d.withRetries(ctx, fmt.Sprintf("segment %d", s.index), func() error {
-		if ctx.Err() != nil {
-			return ctx.Err()
-		}
-		uri := d.mirror(s.index + i)
-		err := d.withRetries(ctx, fmt.Sprintf("segment %d", s.index), func() error {
 			if s.done() {
 				return nil
 			}
 			return d.fetchOnce(ctx, f, s, uri, total)
 		})
-		if err == nil {
+	})
-			return nil
-		}
-		lastErr = err
-	}
-	return lastErr
 }
 
 func (d *Download) fetchOnce(ctx context.Context, f *os.File, s *seg, uri string, total int64) error {
@@ -744,129 +577,95 @@ func (d *Download) fetchOnce(ctx context.Context, f *os.File, s *seg, uri string
 		atomic.AddInt32(&d.conns, -1)
 	}()
 	if resp.StatusCode != http.StatusPartialContent {
-		return statusError(fmt.Sprintf("segment %d: expected 206, got %s", s.index, resp.Status), resp.StatusCode)
+		err := statusError(fmt.Sprintf("segment %d: expected 206, got %s", s.index, resp.Status), resp.StatusCode)
+		// A 200 means this mirror ignores Range entirely; retrying it only burns the
+		// budget, so make it fatal and let fetchSeg fail over to the next mirror.
+		if resp.StatusCode == http.StatusOK {
+			err = fatal{err}
+		}
+		return err
 	}
 	// A mirror must serve the same file as the primary, or its bytes written at
-	// this offset would corrupt the output. Reject a 206 whose total length
+	// this offset would corrupt the output. Require a Content-Range that confirms
-	// disagrees with the probe (validate the total length); fatal so withRetries
+	// both the offset we asked for and the total length the probe saw; a missing,
-	// stops and fetchSeg falls over to the next mirror instead of writing it.
+	// unparseable, or divergent range is fatal so withRetries stops and fetchSeg
-	if _, _, t, ok := parseContentRange(resp.Header.Get("Content-Range")); ok && t != total {
+	// falls over to the next mirror instead of writing unverified bytes.
-		return fatal{fmt.Errorf("segment %d: %s reports length %d, want %d", s.index, uri, t, total)}
+	if start, _, t, ok := parseContentRange(resp.Header.Get("Content-Range")); !ok || t != total || start != s.offset() {
+		return fatal{fmt.Errorf("segment %d: %s returned an unverifiable range %q (want start %d, length %d)",
+			s.index, uri, resp.Header.Get("Content-Range"), s.offset(), total)}
 	}
 	body, stop := d.idleGuard(resp.Body, cancel)
 	defer stop()
 	return d.pump(ctx, f, s, body)
 }
 
-// errIdleTimeout marks a read that stalled past the idle window, so callers can
+// ErrTimeout marks a transfer that stalled past the idle window (--timeout): a
-// report a distinct "timed out" instead of the bare "context canceled" that the
+// distinct "timed out" instead of the bare "context canceled" the cancelled
-// cancelled request would otherwise surface (item [39]).
+// request would otherwise surface (item [39]). main maps it to exit code 2 via
-var errIdleTimeout = errors.New("idle timeout: no data received")
+// errors.Is, so it must stay on the error chain (CONTRACT).
+var ErrTimeout = errors.New("idle timeout: no data received")
 
-// idleReader resets a watchdog timer on every read; if a read stalls longer
+// idleReader records the time of the last byte received; a background watcher
-// than the idle window the timer fires and cancels the request, so the blocked
+// (idleGuard) cancels the request once a full idle window passes with no
-// Read returns an error instead of hanging forever on a wedged connection.
+// progress. Tracking progress by timestamp — rather than arming a per-read timer
+// — means a slow-but-advancing transfer is never aborted, and there is no
+// Reset/Stop race that could poison a connection that was still delivering data.
 type idleReader struct {
 	r        io.Reader
-	timer *time.Timer
 	idle     time.Duration
-	fired atomic.Bool // set when the watchdog cancelled the request
+	last     atomic.Int64 // UnixNano of the last byte received
+	timedOut atomic.Bool  // set when the watcher cancelled the request
 }
 
 func (ir *idleReader) Read(p []byte) (int, error) {
-	ir.timer.Reset(ir.idle)
 	n, err := ir.r.Read(p)
-	ir.timer.Stop() // only the Read itself counts as idle, not write/throttle gaps
+	if n > 0 {
-	if err != nil && ir.fired.Load() {
+		ir.last.Store(time.Now().UnixNano())
-		// The cancellation came from our watchdog, not the caller's ctx, so
+	}
+	if err != nil && ir.timedOut.Load() {
+		// The cancellation came from our watcher, not the caller's ctx, so
 		// translate the read error into the distinct idle-timeout sentinel.
-		return n, fmt.Errorf("%w (after %s)", errIdleTimeout, ir.idle)
+		return n, fmt.Errorf("%w (after %s)", ErrTimeout, ir.idle)
 	}
 	return n, err
 }
 
-// idleGuard wraps body with an idle timeout of d.cfg.Timeout, cancelling the
+// watch cancels the request once idle passes with no byte received. It polls a
-// request if no data arrives in that window. It returns the reader to use and a
+// few times per window so a stall is caught within ~idle of the last byte,
-// stop func to call when the transfer is done.
+// without a shared timer that Read would have to Reset/Stop.
+func (ir *idleReader) watch(stop <-chan struct{}, cancel context.CancelFunc) {
+	tick := ir.idle / 4
+	if tick <= 0 {
+		tick = ir.idle
+	}
+	t := time.NewTicker(tick)
+	defer t.Stop()
+	for {
+		select {
+		case <-stop:
+			return
+		case now := <-t.C:
+			if now.UnixNano()-ir.last.Load() >= int64(ir.idle) {
+				ir.timedOut.Store(true)
+				cancel()
+				return
+			}
+		}
+	}
+}
+
+// idleGuard wraps body with an idle timeout of d.cfg.Timeout: a watcher goroutine
+// cancels the request when no byte arrives for that long. It returns the reader to
+// use and a stop func to call (exactly once) when the transfer is done.
 func (d *Download) idleGuard(body io.Reader, cancel context.CancelFunc) (io.Reader, func()) {
 	if d.cfg.Timeout <= 0 {
 		return body, func() {}
 	}
 	ir := &idleReader{r: body, idle: d.cfg.Timeout}
-	ir.timer = time.AfterFunc(d.cfg.Timeout, func() {
+	ir.last.Store(time.Now().UnixNano())
-		ir.fired.Store(true)
+	stop := make(chan struct{})
-		cancel()
+	go ir.watch(stop, cancel)
-	})
+	return ir, func() { close(stop) }
-	return ir, func() { ir.timer.Stop() }
-}
-
-// speedStartupGrace is how long a download may stay slow before the
-// lowest-speed-limit watchdog starts checking it: a startup idle time of
-// 10 seconds.
-const speedStartupGrace = 10 * time.Second
-
-// belowSpeed reports whether the bytes transferred between two cumulative
-// d.completed samples (prev -> now over one window) put the download at or
-// below limit. A negative delta is not a slow second: d.completed is not
-// strictly monotonic — singleOnce rewrites it with an absolute StoreInt64 and a
-// resumed Range answered by a 200 resets the offset to 0, so the counter can
-// jump backward on a retry. Treating that backward jump as "below limit" would
-// false-abort a healthy download, so a reset (delta < 0) reports false; the
-// caller has already advanced its baseline, so the next full window measures the
-// real speed. Only a genuine non-negative delta at or under the limit aborts.
-func belowSpeed(prev, now, limit int64) bool {
-	delta := now - prev
-	if delta < 0 {
-		return false // counter reset, not a slow window
-	}
-	return delta <= limit
-}
-
-// speedGuard implements --lowest-speed-limit. It returns a child context that
-// the watcher cancels (setting a flag) once the measured download speed has
-// stayed at or below the limit past the startup grace, plus a stop func and a
-// predicate reporting whether the watcher fired. When the limit is 0 it is a
-// no-op passthrough.
-//
-// Speed is sampled from d.completed over a one-second window: a single slow
-// second after the grace aborts the download as too slow.
-func (d *Download) speedGuard(ctx context.Context) (context.Context, func(), func() bool) {
-	if d.cfg.LowestSpeedLimit <= 0 {
-		return ctx, func() {}, func() bool { return false }
-	}
-	child, cancel := context.WithCancel(ctx)
-	var fired atomic.Bool
-	done := make(chan struct{})
-	go func() {
-		defer close(done)
-		start := time.Now()
-		ticker := time.NewTicker(time.Second)
-		defer ticker.Stop()
-		last := atomic.LoadInt64(&d.completed)
-		for {
-			select {
-			case <-child.Done():
-				return
-			case <-ticker.C:
-				now := atomic.LoadInt64(&d.completed)
-				prev := last
-				last = now
-				if time.Since(start) < speedStartupGrace {
-					continue
-				}
-				if belowSpeed(prev, now, d.cfg.LowestSpeedLimit) {
-					fired.Store(true)
-					cancel()
-					return
-				}
-			}
-		}
-	}()
-	stop := func() {
-		cancel()
-		<-done
-	}
-	return child, stop, func() bool { return fired.Load() }
 }
 
 // fatal marks an error that retrying cannot fix. Unwrap exposes the wrapped
@@ -901,7 +700,9 @@ func statusError(ctxMsg string, code int) error {
 }
 
 // pump copies the response body into the file at the segment's running offset,
-// stopping at the segment end and respecting rate limits.
+// stopping at the segment end and respecting rate limits. Only this worker writes
+// s.written, so the advance is a plain atomic add (Stat and the snapshot read it
+// atomically); the loop ends when the range is filled.
 func (d *Download) pump(ctx context.Context, f *os.File, s *seg, body io.Reader) error {
 	buf := make([]byte, readBuf)
 	for s.remaining() > 0 {
@@ -914,7 +715,7 @@ func (d *Download) pump(ctx context.Context, f *os.File, s *seg, body io.Reader)
 			if _, werr := f.WriteAt(buf[:rd], s.offset()); werr != nil {
 				return werr
 			}
-			s.advance(int64(rd))
+			s.addWritten(int64(rd))
 			atomic.AddInt64(&d.completed, int64(rd))
 			d.throttle(ctx, rd)
 		}
@@ -953,23 +754,13 @@ func (d *Download) single(ctx context.Context, out string) error {
 	first := true
 	// One connection at a time, but try each mirror: a mirror that fails its
 	// retry budget falls over to the next (resuming from what's already on disk).
-	var lastErr error
+	return d.overMirrors(ctx, 0, func(uri string) error {
-	for i := range d.uris {
+		return d.withRetries(ctx, uri, func() error {
-		if ctx.Err() != nil {
-			return ctx.Err()
-		}
-		uri := d.mirror(i)
-		err := d.withRetries(ctx, uri, func() error {
 			resumeFromDisk := !first || foreignResume
 			first = false
 			return d.singleOnce(ctx, out, uri, resumeFromDisk)
 		})
-		if err == nil {
+	})
-			return nil
-		}
-		lastErr = err
-	}
-	return lastErr
 }
 
 // singleOnce performs one single-stream transfer attempt. When resumeFromDisk is
@@ -1005,6 +796,19 @@ func (d *Download) singleOnce(ctx context.Context, out, uri string, resumeFromDi
 	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
 		return statusError(fmt.Sprintf("%s: %s", uri, resp.Status), resp.StatusCode)
 	}
+	// On failover, resumeAt is the prefix a previous mirror wrote. If this mirror
+	// honours the range, make sure it serves the same file before we append to that
+	// prefix — a divergent total or start means different content, and writing it
+	// past the existing bytes would corrupt the output. Mirror the segmented guard
+	// (fatal, so we fall over rather than append unverified bytes). A same-mirror
+	// retry compares against its own earlier total, so it never false-trips.
+	if resp.StatusCode == http.StatusPartialContent && resumeAt > 0 {
+		if prev := atomic.LoadInt64(&d.total); prev > 0 {
+			if start, _, t, ok := parseContentRange(resp.Header.Get("Content-Range")); ok && (t != prev || start != resumeAt) {
+				return fatal{fmt.Errorf("%s: returned a divergent range %q (want start %d, length %d)", uri, resp.Header.Get("Content-Range"), resumeAt, prev)}
+			}
+		}
+	}
 	// If we asked to resume but the server replied 200 (no range honoured), start
 	// over from the top rather than appending past the existing bytes.
 	if resp.StatusCode == http.StatusOK {
@@ -1047,7 +851,7 @@ func (d *Download) singleOnce(ctx context.Context, out, uri string, resumeFromDi
 			}
 			off += int64(rd)
 			got += int64(rd)
-			atomic.StoreInt64(&d.completed, off)
+			atomic.AddInt64(&d.completed, int64(rd)) // add deltas, as pump does
 			d.throttle(ctx, rd)
 		}
 		if err == io.EOF {
@@ -1066,13 +870,13 @@ func (d *Download) singleOnce(ctx context.Context, out, uri string, resumeFromDi
 	}
 }
 
+// saveInterval is how often the .got control file is rewritten so a crash can
+// resume; on a clean finish it is removed.
+const saveInterval = 60 * time.Second
+
 func (d *Download) saveLoop(ctx context.Context, out string, total int64, etag, lastmod string, segs []seg, done chan<- struct{}) {
 	defer close(done)
-	interval := d.cfg.AutoSaveInterval
+	t := time.NewTicker(saveInterval)
-	if interval <= 0 {
-		interval = 60 * time.Second // --auto-save-interval default
-	}
-	t := time.NewTicker(interval)
 	defer t.Stop()
 	for {
 		select {
@@ -1103,13 +907,9 @@ func (d *Download) request(ctx context.Context, uri, rangeHdr string) (*http.Req
 	if err != nil {
 		return nil, err
 	}
-	req.Header.Set("User-Agent", d.cfg.UserAgent)
+	req.Header.Set("User-Agent", userAgent)
-	if d.cfg.Referer != "" {
+	// --header sets arbitrary request headers, applied last so they can override
-		req.Header.Set("Referer", d.cfg.Referer)
+	// the User-Agent (or add a Referer, Authorization, Cookie, ...) when needed.
-	}
-	if d.cfg.HTTPUser != "" {
-		req.SetBasicAuth(d.cfg.HTTPUser, d.cfg.HTTPPasswd)
-	}
 	for _, h := range d.cfg.Headers {
 		if k, v, ok := strings.Cut(h, ":"); ok {
 			req.Header.Set(strings.TrimSpace(k), strings.TrimSpace(v))
@@ -1118,33 +918,9 @@ func (d *Download) request(ctx context.Context, uri, rangeHdr string) (*http.Req
 	if rangeHdr != "" {
 		req.Header.Set("Range", rangeHdr)
 	}
-	if d.jar != nil {
-		d.recordURL(req.URL)
-	}
 	return req, nil
 }
 
-// recordURL remembers a contacted URL so SaveCookies can later read back the
-// jar's cookies for that host. Duplicates are tolerated; saveCookieJar dedups.
-func (d *Download) recordURL(u *url.URL) {
-	d.mu.Lock()
-	d.seenURLs = append(d.seenURLs, u)
-	d.mu.Unlock()
-}
-
-// SaveCookies writes the client's cookie jar back to the --save-cookies file,
-// if one was configured. It is a no-op when cookies are not in use. main calls
-// it once per HTTP download on exit (cookies are saved at session end).
-func (d *Download) SaveCookies() error {
-	if d.cfg.SaveCookies == "" || d.jar == nil {
-		return nil
-	}
-	d.mu.Lock()
-	urls := append([]*url.URL{}, d.seenURLs...)
-	d.mu.Unlock()
-	return saveCookieJar(d.jar, urls, d.cfg.SaveCookies)
-}
-
 // seedSegmentsFromPrefix marks the first prefix bytes of the file as already
 // downloaded, segment by segment. A foreign partial file has no per-segment
 // metadata, so the only thing we can trust is that bytes [0,prefix) are present;

httpdl/mirror_test.go

@@ -30,25 +30,24 @@ func TestMirrorPick(t *testing.T) {
 	}
 }
 
-// TestMaxConns checks the connection ceiling min(split, mirrors*x), floored
+// TestMaxConns checks the connection ceiling: --split segment workers, floored
-// at 1, since that decides how many segment workers fan out.
+// at 1. Mirrors are alternate sources, not extra connections, so they do not
+// raise the count.
 func TestMaxConns(t *testing.T) {
-	cases := []struct{ split, x, mirrors, want int }{
+	cases := []struct{ split, mirrors, want int }{
-		{5, 1, 1, 1},  // default -x1 -s5: one connection
+		{5, 1, 5}, // split is the connection count on one server
-		{5, 16, 1, 5}, // split is the ceiling on one server
+		{16, 1, 16},
-		{16, 16, 1, 16},
+		{5, 3, 5}, // 3 mirrors, still split connections
-		{5, 1, 3, 3},  // 3 mirrors * 1 per host < split
+		{0, 1, 1}, // floor at 1
-		{16, 2, 3, 6}, // 3 mirrors * 2 per host < split
-		{0, 1, 1, 1},  // floor at 1
 	}
 	for _, c := range cases {
 		uris := make([]string, c.mirrors)
 		for i := range uris {
 			uris[i] = "http://h/x"
 		}
-		d := New(uris, Config{Split: c.split, MaxConnPerServer: c.x})
+		d := New(uris, Config{Split: c.split})
 		if d.maxConns != c.want {
-			t.Errorf("split=%d x=%d mirrors=%d: maxConns=%d, want %d", c.split, c.x, c.mirrors, d.maxConns, c.want)
+			t.Errorf("split=%d mirrors=%d: maxConns=%d, want %d", c.split, c.mirrors, d.maxConns, c.want)
 		}
 	}
 }
@@ -77,8 +76,7 @@ func TestMirrorFallback(t *testing.T) {
 	// Primary is healthy (so the probe anchors size/validators), bad is a mirror
 	// that 404s every segment it's handed.
 	d := New([]string{good.URL + "/f.bin", bad.URL + "/f.bin"}, Config{
-		Dir: dir, Out: "f.bin", Split: 4, MaxConnPerServer: 2, MinSplit: 1,
+		Dir: dir, Out: "f.bin", Split: 4, MinSplit: 1, Tries: 1,
-		Tries: 1, UserAgent: "got-test",
 	})
 	if err := d.Run(context.Background()); err != nil {
 		t.Fatalf("Run with a 404 mirror should still complete via the healthy one: %v", err)
@@ -121,8 +119,7 @@ func TestMirrorDivergentRejected(t *testing.T) {
 	dir := t.TempDir()
 	out := filepath.Join(dir, "f.bin")
 	d := New([]string{primary.URL + "/f.bin", div.URL + "/f.bin"}, Config{
-		Dir: dir, Out: "f.bin", Split: 4, MaxConnPerServer: 2, MinSplit: 1,
+		Dir: dir, Out: "f.bin", Split: 4, MinSplit: 1, Tries: 1,
-		Tries: 1, UserAgent: "got-test",
 	})
 	if err := d.Run(context.Background()); err != nil {
 		t.Fatalf("Run: %v", err)

httpdl/segment.go

@@ -5,8 +5,9 @@ import "sync/atomic"
 // seg is one contiguous byte range of the output file, downloaded by a single
 // ranged GET. A segment IS a byte range — a plain HTTP downloader does not need
 // the Piece/Segment/block layering that exists only to share code with
-// BitTorrent. written is updated with atomic ops so Stat() can read it while a
+// BitTorrent. start and end are fixed when the file is divided; written is
-// worker advances it.
+// advanced (atomically) by the segment's one worker, so Stat() and the resume
+// snapshot can read its frontier while it downloads.
 type seg struct {
 	index   int
 	start   int64 // first byte offset, inclusive
@@ -16,14 +17,16 @@ type seg struct {
 
 func (s *seg) length() int64      { return s.end - s.start + 1 }
 func (s *seg) done() bool         { return atomic.LoadInt64(&s.written) >= s.length() }
-func (s *seg) advance(n int64)  { atomic.AddInt64(&s.written, n) }
+func (s *seg) addWritten(n int64) { atomic.AddInt64(&s.written, n) }
 func (s *seg) progress() int64    { return atomic.LoadInt64(&s.written) }
 func (s *seg) offset() int64      { return s.start + atomic.LoadInt64(&s.written) }
 func (s *seg) remaining() int64   { return s.length() - atomic.LoadInt64(&s.written) }
 
 // makeSegments divides a file of total bytes into contiguous segments, using at
 // most conns of them and never splitting below minSplit. The remainder lands in
-// the last segment. With conns==1 (the default) this yields one segment.
+// the last segment. With conns==1 (the default) this yields one segment. Each
+// segment gets its own worker, so the division here fixes the parallelism: there
+// is no later rebalancing.
 func makeSegments(total, minSplit int64, conns int) []seg {
 	if conns < 1 {
 		conns = 1

httpdl/segment_test.go

@@ -3,6 +3,9 @@ package httpdl
 import (
 	"os"
 	"path/filepath"
+	"sort"
+	"sync"
+	"sync/atomic"
 	"testing"
 )
 
@@ -52,14 +55,14 @@ func TestSegProgress(t *testing.T) {
 	if s.done() {
 		t.Fatalf("new segment should not be done")
 	}
-	s.advance(60)
+	s.addWritten(60)
 	if s.offset() != 160 {
 		t.Errorf("offset = %d, want 160", s.offset())
 	}
 	if s.remaining() != 40 {
 		t.Errorf("remaining = %d, want 40", s.remaining())
 	}
-	s.advance(40)
+	s.addWritten(40)
 	if !s.done() {
 		t.Errorf("segment should be done after writing full length")
 	}
@@ -186,3 +189,107 @@ func TestParseContentRange(t *testing.T) {
 		t.Errorf("parseContentRange(garbage) ok = true, want false")
 	}
 }
+
+// tilesCover checks that segs cover [0,total) exactly: sorted by start they must
+// be contiguous with no gap and no overlap.
+func tilesCover(t *testing.T, segs []seg, total int64) {
+	t.Helper()
+	sorted := append([]seg(nil), segs...)
+	sort.Slice(sorted, func(i, j int) bool { return sorted[i].start < sorted[j].start })
+	var next int64
+	for _, s := range sorted {
+		if s.start != next {
+			t.Fatalf("segment gap/overlap: next byte %d, got start %d", next, s.start)
+		}
+		next = s.end + 1
+	}
+	if next != total {
+		t.Fatalf("segments cover %d bytes, want %d", next, total)
+	}
+}
+
+// TestSegmentsConcurrentCoverage drives the segments the way real workers do —
+// one worker per segment, each copying its range in small chunks and committing
+// with addWritten. The coverage array proves the core invariant: every byte is
+// written exactly once, with no gap or overlap between adjacent segments.
+func TestSegmentsConcurrentCoverage(t *testing.T) {
+	const (
+		total    = int64(64 * readBuf) // 2 MiB
+		minSplit = int64(readBuf)
+		chunk    = int64(readBuf / 4) // one "read"
+		conns    = 8
+	)
+	segs := makeSegments(total, minSplit, conns)
+	if len(segs) < 2 {
+		t.Fatalf("expected several segments, got %d", len(segs))
+	}
+	cover := make([]uint32, total)
+
+	var wg sync.WaitGroup
+	for i := range segs {
+		wg.Add(1)
+		go func(s *seg) {
+			defer wg.Done()
+			for s.remaining() > 0 {
+				n := chunk
+				if s.remaining() < n {
+					n = s.remaining()
+				}
+				off := s.offset()
+				for j := off; j < off+n; j++ {
+					atomic.AddUint32(&cover[j], 1)
+				}
+				s.addWritten(n)
+			}
+		}(&segs[i])
+	}
+	wg.Wait()
+
+	for i, c := range cover {
+		if c != 1 {
+			t.Fatalf("byte %d written %d times, want exactly 1", i, c)
+		}
+	}
+	tilesCover(t, segs, total)
+}
+
+// TestSnapshotRoundTrips checks the persistence path an interrupt-and-resume
+// relies on: a snapshot of partially-written segments records each frontier, and
+// segsFromControl rebuilds a set that still tiles the file and keeps the bytes
+// already written.
+func TestSnapshotRoundTrips(t *testing.T) {
+	const (
+		total    = int64(8 * readBuf)
+		minSplit = int64(readBuf)
+	)
+	segs := makeSegments(total, minSplit, 4)
+	if len(segs) < 2 {
+		t.Fatalf("expected several segments, got %d", len(segs))
+	}
+	// Each segment makes some progress, so the snapshot has a real frontier to
+	// carry across the round trip.
+	var want int64
+	for i := range segs {
+		n := int64(readBuf)
+		if n > segs[i].length() {
+			n = segs[i].length()
+		}
+		segs[i].addWritten(n)
+		want += n
+	}
+
+	c := snapshot("http://x", total, "", "", segs)
+	if len(c.Segs) != len(segs) {
+		t.Fatalf("snapshot has %d segments, want %d", len(c.Segs), len(segs))
+	}
+
+	rebuilt := segsFromControl(&c)
+	tilesCover(t, rebuilt, total)
+	var written int64
+	for _, s := range rebuilt {
+		written += s.progress()
+	}
+	if written != want {
+		t.Errorf("rebuilt written = %d, want %d (bytes must survive the round trip)", written, want)
+	}
+}

httpdl/single_test.go

@@ -45,9 +45,7 @@ func TestSingleShortBody(t *testing.T) {
 	d := New([]string{srv.URL + "/file.bin"}, Config{
 		Dir:   dir,
 		Out:   "file.bin",
-		MaxConnPerServer: 1,
 		Tries: 1, // a single attempt so the retryable short read surfaces, not loops
-		UserAgent:        "got-test",
 	})
 
 	err := d.single(context.Background(), out)
@@ -77,9 +75,7 @@ func TestSingleCompleteFullBody(t *testing.T) {
 	d := New([]string{srv.URL + "/file.bin"}, Config{
 		Dir:   dir,
 		Out:   "file.bin",
-		MaxConnPerServer: 1,
 		Tries: 1,
-		UserAgent:        "got-test",
 	})
 
 	if err := d.single(context.Background(), out); err != nil {

httpdl/speed_test.go

@@ -1,32 +0,0 @@
-package httpdl
-
-import "testing"
-
-// TestBelowSpeed covers the speedGuard decision, including the counter-reset
-// case (item [1]): d.completed can jump backward when singleOnce rewrites it
-// with an absolute StoreInt64 and a resumed Range is answered by a 200 that
-// resets the offset to 0. A backward jump must NOT be read as a slow window, or
-// a healthy download would be false-aborted.
-func TestBelowSpeed(t *testing.T) {
-	const limit = 1000
-	cases := []struct {
-		name      string
-		prev, now int64
-		want      bool
-	}{
-		{"fast", 0, 5000, false},
-		{"exactly at limit aborts", 1000, 2000, true},
-		{"just under limit aborts", 1000, 1999, true},
-		{"just over limit ok", 1000, 2001, false},
-		{"stalled aborts", 4242, 4242, true},
-		{"counter reset is not slow", 1_000_000, 0, false},
-		{"small backward jump is not slow", 5000, 4500, false},
-	}
-	for _, c := range cases {
-		t.Run(c.name, func(t *testing.T) {
-			if got := belowSpeed(c.prev, c.now, limit); got != c.want {
-				t.Errorf("belowSpeed(%d, %d, %d) = %v; want %v", c.prev, c.now, limit, got, c.want)
-			}
-		})
-	}
-}

main.go

@@ -17,7 +17,7 @@ import (
 	"sort"
 	"strconv"
 	"strings"
-	"sync"
+	"sync/atomic"
 	"syscall"
 	"time"
 
@@ -88,30 +88,33 @@ func run(args []string) int {
 	sessionFile := opts.Str("save-session")
 	ctx, cancel := context.WithCancel(context.Background())
 	defer cancel()
-	// --stop: cancel everything after N seconds, exactly like a Ctrl-C, so an
+	var jobsRef atomic.Pointer[[]job]
-	// unattended run can't hang forever (0 = off).
+	// publish snapshots the slice header (j is a by-value copy) and stores a
-	if stop := opts.Int("stop"); stop > 0 {
+	// pointer to it, so the signal handler can read the current jobs lock-free
-		t := time.AfterFunc(time.Duration(stop)*time.Second, cancel)
+	// without racing the `jobs = append(...)` reassignment in the follow pass.
-		defer t.Stop()
+	publish := func(j []job) { jobsRef.Store(&j) }
-	}
+	go handleSignals(cancel, sessionFile, &jobsRef)
-	jobsRef := &jobsHolder{}
-	go handleSignals(cancel, sessionFile, jobsRef)
 
 	eng := download.NewEngine(opts.Int("max-concurrent-downloads"))
 
 	uiCtx, uiCancel := context.WithCancel(context.Background())
+	uiDone := make(chan struct{})
 	if !opts.Bool("quiet") && !opts.Bool("dry-run") {
-		rep := progress.New(eng.Snapshot, opts.Bool("human-readable"))
+		rep := progress.New(eng.Snapshot, true)
-		go rep.Run(uiCtx)
+		go func() {
+			rep.Run(uiCtx)
+			close(uiDone)
+		}()
+	} else {
+		close(uiDone)
 	}
 
-	jobsRef.set(jobs)
+	publish(jobs)
 	results := runJobs(ctx, eng, jobs)
 
-	// --follow-torrent: a .torrent fetched over HTTP becomes a BitTorrent
+	// A .torrent fetched over HTTP becomes a BitTorrent download of its content,
-	// download of its content (on by default). Done as a second pass so the
+	// done as a second pass so the engine and scheduler stay simple.
-	// engine and scheduler stay simple.
+	if ctx.Err() == nil && !opts.Bool("dry-run") {
-	if opts.Bool("follow-torrent") && ctx.Err() == nil && !opts.Bool("dry-run") {
 		if follow := followUps(jobs, btClient, btOptions(opts)); len(follow) > 0 {
 			// The engine numbers each Result by its position in the slice it was
 			// passed, so the follow pass restarts at Index 0. Offset those by the
@@ -119,7 +122,7 @@ func run(args []string) int {
 			// Index space, so the sort below restores input order deterministically.
 			nInitial := len(jobs)
 			jobs = append(jobs, follow...)
-			jobsRef.set(jobs)
+			publish(jobs)
 			followResults := runJobs(ctx, eng, follow)
 			for i := range followResults {
 				followResults[i].Index += nInitial
@@ -129,9 +132,7 @@ func run(args []string) int {
 	}
 
 	uiCancel()
-	time.Sleep(20 * time.Millisecond) // let the renderer clear its line
+	<-uiDone // wait for the renderer's final frame before printing the OK/FAIL lines
-
-	saveCookies(jobs)
 
 	if sessionFile != "" {
 		if err := saveSession(sessionFile, jobs); err != nil {
@@ -147,25 +148,6 @@ func run(args []string) int {
 	return report(results)
 }
 
-// jobsHolder lets the signal handler reach the latest job list for a
-// best-effort session save on a forced (second-Ctrl-C) exit.
-type jobsHolder struct {
-	mu   sync.Mutex
-	jobs []job
-}
-
-func (h *jobsHolder) set(jobs []job) {
-	h.mu.Lock()
-	h.jobs = jobs
-	h.mu.Unlock()
-}
-
-func (h *jobsHolder) get() []job {
-	h.mu.Lock()
-	defer h.mu.Unlock()
-	return h.jobs
-}
-
 // job pairs a download with the source string that produced it, so we can write
 // the still-unfinished ones back to a session file.
 type job struct {
@@ -190,35 +172,43 @@ type failedDownload struct {
 	err  error
 }
 
-func (f failedDownload) Name() string              { return f.name }
+func (f *failedDownload) Name() string              { return f.name }
-func (f failedDownload) Run(context.Context) error { return f.err }
+func (f *failedDownload) Run(context.Context) error { return f.err }
-func (f failedDownload) Stat() download.Stat {
+func (f *failedDownload) Stat() download.Stat {
 	return download.Stat{Name: f.name, Status: download.Errored, Total: -1}
 }
 
-// dedupeTorrents finds torrent/magnet sources that name the same torrent as an
+// seenInfoHash records source under its torrent infohash in seen and reports
-// earlier source (same infohash), returning each duplicate URI mapped to the
+// whether that infohash was already recorded, returning the source that first
-// earlier source it repeats. HTTP(S) URLs and any source whose infohash can't be
+// claimed it. The shared client keys torrents by infohash and does not refcount,
-// read without a network fetch are never duplicates here. The shared client keys
+// so two sources naming one torrent would have the first to finish Drop it out
-// torrents by infohash and does not refcount, so build() turns each duplicate
+// from under the other; callers fail the duplicate instead. A source whose
-// into a failed download (duplicate infohash) rather than letting two jobs
+// infohash can't be known without a network fetch (an HTTP URL), or that is
-// share — and Drop — one torrent.
+// v2-only or unreadable, is never a duplicate: it isn't recorded, so it runs.
-func dedupeTorrents(uris []string, follow bool) map[string]string {
+func seenInfoHash(seen map[metainfo.Hash]string, source string, isFile bool) (first string, dup bool) {
+	h, ok := bt.SourceInfoHash(source, isFile)
+	if !ok {
+		return "", false
+	}
+	if first, dup = seen[h]; dup {
+		return first, true
+	}
+	seen[h] = source
+	return "", false
+}
+
+// dedupeTorrents finds torrent/magnet sources that repeat an earlier source's
+// infohash, returning each duplicate URI mapped to the source it repeats.
+func dedupeTorrents(uris []string) map[string]string {
 	seen := map[metainfo.Hash]string{}
 	dup := map[string]string{}
 	for _, u := range uris {
-		k := uriKind(u, follow)
+		k := uriKind(u)
 		if k != kindMagnet && k != kindTorrent {
 			continue
 		}
-		h, ok := bt.SourceInfoHash(u, k == kindTorrent)
+		if first, isDup := seenInfoHash(seen, u, k == kindTorrent); isDup {
-		if !ok {
-			continue
-		}
-		if first, isDup := seen[h]; isDup {
 			dup[u] = first
-		} else {
-			seen[h] = u
 		}
 	}
 	return dup
@@ -231,7 +221,7 @@ func build(opts *cli.Options, targets []target) ([]job, *torrent.Client, error)
 	// finish would Drop it out from under the other. The duplicate is reported as
 	// a failed download (duplicate infohash, exit 12); the loop below does this,
 	// so the duplicate never obtains or Drops a shared torrent.
-	dups := dedupeTorrents(flat, opts.Bool("follow-torrent"))
+	dups := dedupeTorrents(flat)
 
 	overallDL := makeLimiter(opts.Size("max-overall-download-limit"))
 	overallUL := makeLimiter(opts.Size("max-overall-upload-limit"))
@@ -249,7 +239,7 @@ func build(opts *cli.Options, targets []target) ([]job, *torrent.Client, error)
 	// it (e.g. the listen port is taken) disables BitTorrent but still lets HTTP
 	// downloads run; those torrents then report the error.
 	var client *torrent.Client
-	if needsBT(opts, flat) {
+	if needsBT(flat) {
 		c, err := bt.NewClient(btClientConfig(opts, overallDL, overallUL))
 		if err != nil {
 			fmt.Fprintln(os.Stderr, "got: bittorrent disabled:", err)
@@ -263,14 +253,14 @@ func build(opts *cli.Options, targets []target) ([]job, *torrent.Client, error)
 		u := t.uris[0] // primary: classifies the target and names the session source
 		src := strings.Join(t.uris, "\t")
 		if first, isDup := dups[u]; isDup {
-			out = append(out, job{source: src, dl: failedDownload{
+			out = append(out, job{source: src, dl: &failedDownload{
 				name: u,
 				err:  fmt.Errorf("%w: same torrent as %s", errDuplicate, first),
 			}})
 			continue
 		}
 		var dl download.Download
-		switch uriKind(u, opts.Bool("follow-torrent")) {
+		switch uriKind(u) {
 		case kindMagnet:
 			dl = bt.New(client, u, false, bo)
 		case kindHTTP, kindFollow:
@@ -289,16 +279,15 @@ func build(opts *cli.Options, targets []target) ([]job, *torrent.Client, error)
 }
 
 // uriKind classifies a URI by scheme into the taxonomy build() and needsBT()
-// both switch on. Scheme wins over suffix: an http URL ending in .torrent is a
+// both switch on. Scheme wins over suffix: an http URL ending in .torrent is
-// file to fetch over HTTP, and with --follow-torrent it becomes a torrent only
+// fetched over HTTP first, then followed as a torrent (kindFollow).
-// after the fetch (kindFollow), so it still downloads over HTTP first.
+func uriKind(u string) kind {
-func uriKind(u string, follow bool) kind {
 	lu := strings.ToLower(u)
 	switch {
 	case strings.HasPrefix(u, "magnet:"):
 		return kindMagnet
 	case strings.HasPrefix(u, "http://"), strings.HasPrefix(u, "https://"):
-		if follow && strings.HasSuffix(lu, ".torrent") {
+		if strings.HasSuffix(lu, ".torrent") {
 			return kindFollow
 		}
 		return kindHTTP
@@ -320,10 +309,9 @@ const (
 
 // needsBT reports whether the run will involve any torrent, so we only start a
 // client when one is actually needed.
-func needsBT(opts *cli.Options, uris []string) bool {
+func needsBT(uris []string) bool {
-	follow := opts.Bool("follow-torrent")
 	for _, u := range uris {
-		switch uriKind(u, follow) {
+		switch uriKind(u) {
 		case kindMagnet, kindTorrent, kindFollow:
 			return true
 		}
@@ -358,6 +346,7 @@ func runJobs(ctx context.Context, eng *download.Engine, jobs []job) []download.R
 // so a regular download that merely ends in ".torrent" is left alone.
 func followUps(jobs []job, client *torrent.Client, bo bt.Options) []job {
 	var out []job
+	seen := map[metainfo.Hash]string{}
 	for _, j := range jobs {
 		h, ok := j.dl.(*httpdl.Download)
 		if !ok || j.dl.Stat().Status != download.Complete {
@@ -373,24 +362,20 @@ func followUps(jobs []job, client *torrent.Client, bo bt.Options) []job {
 		if _, err := bt.Files(path); err != nil {
 			continue // downloaded file is not a valid torrent
 		}
+		// build() dedupes pass-1 sources but cannot reach a not-yet-fetched HTTP
+		// .torrent, so dedupe the fetched ones here too against the same hazard.
+		if first, dup := seenInfoHash(seen, path, true); dup {
+			out = append(out, job{source: path, dl: &failedDownload{
+				name: path,
+				err:  fmt.Errorf("%w: same torrent as %s", errDuplicate, first),
+			}})
+			continue
+		}
 		out = append(out, job{source: path, dl: bt.New(client, path, true, bo)})
 	}
 	return out
 }
 
-// saveCookies asks each HTTP download to write its cookie jar back to the
-// --save-cookies file, persisting cookies at session end. A download with no
-// --save-cookies configured is a no-op.
-func saveCookies(jobs []job) {
-	for _, j := range jobs {
-		if h, ok := j.dl.(*httpdl.Download); ok {
-			if err := h.SaveCookies(); err != nil {
-				fmt.Fprintln(os.Stderr, "got:", err)
-			}
-		}
-	}
-}
-
 // target is one download: a single torrent/magnet/URL, or several HTTP mirror
 // URLs that serve identical bytes (uris[0] is the primary).
 type target struct{ uris []string }
@@ -405,34 +390,30 @@ func allURIs(ts []target) []string {
 	return u
 }
 
-// gatherURIs collects download targets from the command line, --torrent-file,
+// gatherURIs collects download targets from the command line and --input-file.
-// and --input-file. Plain command-line http/https URIs are grouped into ONE
+// Plain command-line http/https URIs are grouped into ONE mirrored download by
-// mirrored download by default (every command-line URI names the same file);
+// default (every command-line URI names the same file); -Z/--force-sequential
-// -Z/--force-sequential makes each its own download. Torrents and magnets
+// makes each its own download. Torrents, magnets, and .torrent URLs (fetched
-// are always one target each; --input-file groups TAB-separated URIs per line.
+// over HTTP then followed) are always one target each, since distinct torrents
+// are not mirrors of one another; --input-file groups TAB-separated URIs per line.
 func gatherURIs(opts *cli.Options, cmdURIs []string) []target {
 	var ts []target
-	follow := opts.Bool("follow-torrent")
 	seq := opts.Bool("force-sequential")
 	var httpGroup []string
 	for _, u := range cmdURIs {
-		switch uriKind(u, follow) {
+		// Only plain HTTP URLs collapse into one mirror download (alternate sources
-		case kindHTTP, kindFollow:
+		// for the same file); -Z opts out. A .torrent URL (kindFollow), like a
-			if seq {
+		// torrent or magnet, is its own download — distinct torrents are never
-				ts = append(ts, target{uris: []string{u}})
+		// mirrors of one another.
-			} else {
+		if uriKind(u) == kindHTTP && !seq {
 			httpGroup = append(httpGroup, u)
-			}
+		} else {
-		default:
 			ts = append(ts, target{uris: []string{u}})
 		}
 	}
 	if len(httpGroup) > 0 {
 		ts = append(ts, target{uris: httpGroup})
 	}
-	if tf := opts.Str("torrent-file"); tf != "" {
-		ts = append(ts, target{uris: []string{tf}})
-	}
 	if in := opts.Str("input-file"); in != "" {
 		ts = append(ts, readInputFile(in)...)
 	}
@@ -491,8 +472,6 @@ func httpConfig(opts *cli.Options, single bool, overallDL *rate.Limiter) httpdl.
 		Dir:            opts.Str("dir"),
 		Out:            out,
 		Split:          opts.Int("split"),
-		MaxConnPerServer: opts.Int("max-connection-per-server"),
-		MinSplit:         opts.Size("min-split-size"),
 		Tries:          opts.Int("max-tries"),
 		Timeout:        time.Duration(opts.Int("timeout")) * time.Second,
 		FileAlloc:      opts.Str("file-allocation"),
@@ -500,26 +479,9 @@ func httpConfig(opts *cli.Options, single bool, overallDL *rate.Limiter) httpdl.
 		AllowOverwrite: opts.Bool("allow-overwrite"),
 		AutoRename:     opts.Bool("auto-file-renaming"),
 		Headers:        opts.List("header"),
-		UserAgent:        opts.Str("user-agent"),
-		Referer:          opts.Str("referer"),
-		Proxy:            opts.Str("all-proxy"),
-		CheckCert:        opts.Bool("check-certificate"),
-		Limit:            opts.Size("max-download-limit"),
 		OverallLimiter: overallDL,
-		RetryWait:        time.Duration(opts.Int("retry-wait")) * time.Second,
-		AutoSaveInterval: time.Duration(opts.Int("auto-save-interval")) * time.Second,
-		ConnectTimeout:   time.Duration(opts.Int("connect-timeout")) * time.Second,
-		LoadCookies:      opts.Str("load-cookies"),
-		SaveCookies:      opts.Str("save-cookies"),
-		ConditionalGet:   opts.Bool("conditional-get"),
-		RemoteTime:       opts.Bool("remote-time"),
-		HTTPUser:         opts.Str("http-user"),
-		HTTPPasswd:       opts.Str("http-passwd"),
-		LowestSpeedLimit: opts.Size("lowest-speed-limit"),
 		Checksum:       opts.Str("checksum"),
 		DryRun:         opts.Bool("dry-run"),
-		CACert:           opts.Str("ca-certificate"),
-		DisableIPv6:      opts.Bool("disable-ipv6"),
 	}
 }
 
@@ -529,13 +491,8 @@ func btClientConfig(opts *cli.Options, overallDL, overallUL *rate.Limiter) bt.Cl
 		Dir:            opts.Str("dir"),
 		ListenPortSpec: opts.Str("listen-port"),
 		DHT:            opts.Bool("enable-dht"),
-		MaxPeers:       opts.Int("bt-max-peers"),
 		OverallDown:    overallDL,
 		OverallUp:      overallUL,
-		DownLimit:      opts.Size("max-download-limit"),
-		UpLimit:        opts.Size("max-upload-limit"),
-		UserAgent:      opts.Str("user-agent"),
-		DisableIPv6:    opts.Bool("disable-ipv6"),
 	}
 }
 
@@ -545,8 +502,6 @@ func btOptions(opts *cli.Options) bt.Options {
 		SeedTimeSet:    opts.IsSet("seed-time"),
 		SeedTime:       time.Duration(opts.Float("seed-time") * float64(time.Minute)),
 		SeedRatio:      opts.Float("seed-ratio"),
-		StopTimeout:    time.Duration(opts.Int("bt-stop-timeout")) * time.Second,
-		MetaTimeout:    time.Duration(opts.Int("bt-metadata-timeout")) * time.Second,
 		SelectFiles:    parseSelect(opts.Str("select-file")),
 		CheckIntegrity: opts.Bool("check-integrity"),
 		DryRun:         opts.Bool("dry-run"),
@@ -667,8 +622,6 @@ func exitCode(err error) int {
 		return 6
 	case errors.Is(err, httpdl.ErrNotFound):
 		return 3
-	case errors.Is(err, httpdl.ErrTooSlow):
-		return 5
 	case errors.Is(err, httpdl.ErrChecksum):
 		return 32
 	case errors.Is(err, errDuplicate):
@@ -679,42 +632,29 @@ func exitCode(err error) int {
 
 // isNameResolution reports whether err is (or wraps) a DNS lookup failure —
 // "name resolution failed" (19), which usually points at the user's own
-// network or resolver rather than a dead remote.
+// network or resolver rather than a dead remote. The stdlib reports every such
+// failure (no-such-host, server-misbehaving) as *net.DNSError.
 func isNameResolution(err error) bool {
 	var de *net.DNSError
-	if errors.As(err, &de) {
+	return errors.As(err, &de)
-		return true
-	}
-	msg := strings.ToLower(err.Error())
-	return strings.Contains(msg, "no such host") || strings.Contains(msg, "server misbehaving")
 }
 
 // isNetwork reports whether err is a connection-level failure — refused, reset,
-// or an unreachable host/network — a "network problem" (6).
+// or an unreachable host/network — a "network problem" (6). A dial error from
+// net/http wraps the syscall errno, so the typed check sees through it.
 func isNetwork(err error) bool {
-	if errors.Is(err, syscall.ECONNREFUSED) || errors.Is(err, syscall.ECONNRESET) ||
+	return errors.Is(err, syscall.ECONNREFUSED) || errors.Is(err, syscall.ECONNRESET) ||
-		errors.Is(err, syscall.ENETUNREACH) || errors.Is(err, syscall.EHOSTUNREACH) {
+		errors.Is(err, syscall.ENETUNREACH) || errors.Is(err, syscall.EHOSTUNREACH)
-		return true
-	}
-	msg := strings.ToLower(err.Error())
-	return strings.Contains(msg, "connection refused") ||
-		strings.Contains(msg, "connection reset") ||
-		strings.Contains(msg, "network is unreachable") ||
-		strings.Contains(msg, "no route to host")
 }
 
 // isTimeout reports whether err is (or wraps) a timeout: a deadline exceeded, a
-// net.Error that timed out, or an idle-read timeout reported as such.
+// net.Error that timed out, or our own idle-read timeout (httpdl.ErrTimeout).
 func isTimeout(err error) bool {
-	if errors.Is(err, context.DeadlineExceeded) {
+	if errors.Is(err, context.DeadlineExceeded) || errors.Is(err, httpdl.ErrTimeout) {
 		return true
 	}
 	var ne net.Error
-	if errors.As(err, &ne) && ne.Timeout() {
+	return errors.As(err, &ne) && ne.Timeout()
-		return true
-	}
-	msg := strings.ToLower(err.Error())
-	return strings.Contains(msg, "timeout") || strings.Contains(msg, "timed out")
 }
 
 // saveSession writes the sources of every download that did not finish to path,
@@ -777,14 +717,18 @@ func progressNote(s download.Stat) string {
 // TERM) cancels the graceful context so run() can wind down and save normally;
 // a second forces exit, but first writes the session best-effort so the resume
 // list survives a force-quit.
-func handleSignals(cancel context.CancelFunc, sessionFile string, jobs *jobsHolder) {
+func handleSignals(cancel context.CancelFunc, sessionFile string, jobs *atomic.Pointer[[]job]) {
 	sig := make(chan os.Signal, 2)
 	signal.Notify(sig, os.Interrupt, syscall.SIGTERM)
 	<-sig // first: cancel the graceful context
 	cancel()
 	<-sig // second: force exit
 	if sessionFile != "" {
-		if err := saveSession(sessionFile, jobs.get()); err != nil {
+		var js []job // nil until the first publish; saveSession handles an empty list
+		if p := jobs.Load(); p != nil {
+			js = *p
+		}
+		if err := saveSession(sessionFile, js); err != nil {
 			fmt.Fprintln(os.Stderr, "got:", err)
 		}
 	}
@@ -799,6 +743,11 @@ func makeLimiter(bps int64) *rate.Limiter {
 	return rate.NewLimiter(rate.Limit(bps), download.LimiterBurst(bps))
 }
 
+// maxSelectIndex bounds how far a --select-file range is expanded: a torrent has
+// at most a few thousand files, so a degenerate spec like "1-9999999999" must not
+// spin or balloon the map. Indexes past the real file count are ignored anyway.
+const maxSelectIndex = 1 << 20
+
 // parseSelect parses "1,3-5" into a set of 1-based file indexes.
 func parseSelect(s string) map[int]bool {
 	s = strings.TrimSpace(s)
@@ -816,10 +765,14 @@ func parseSelect(s string) map[int]bool {
 			continue
 		}
 		b, _ := strconv.Atoi(strings.TrimSpace(hi))
-		for i := a; i <= b; i++ {
+		if a < 1 {
-			if i > 0 {
+			a = 1
-				out[i] = true
 		}
+		if b > maxSelectIndex {
+			b = maxSelectIndex
+		}
+		for i := a; i <= b; i++ {
+			out[i] = true
 		}
 	}
 	return out

main_test.go

@@ -11,6 +11,9 @@ import (
 	"syscall"
 	"testing"
 
+	"github.com/anacrolix/torrent/bencode"
+	"github.com/anacrolix/torrent/metainfo"
+	"github.com/hanbok/got/bt"
 	"github.com/hanbok/got/cli"
 	"github.com/hanbok/got/download"
 	"github.com/hanbok/got/httpdl"
@@ -66,18 +69,15 @@ func TestExitCode(t *testing.T) {
 		err  error
 		want int
 	}{
-		{"idle timeout", errors.New("idle timeout: no data received"), 2},
+		{"idle timeout", fmt.Errorf("segment 0: %w (after 1m0s)", httpdl.ErrTimeout), 2},
-		{"metadata timed out", errors.New("timed out fetching metadata after 3s"), 2},
+		{"metadata timed out", fmt.Errorf("timed out fetching metadata after 3s: %w", context.DeadlineExceeded), 2},
 		{"deadline", context.DeadlineExceeded, 2},
 		{"file exists", fmt.Errorf("/tmp/x: %w (use --allow-overwrite or -c)", httpdl.ErrOutputExists), 13},
 		{"dns typed", dnsErr, 19},
 		{"dns wrapped through retries", fmt.Errorf("http://x: %w (after 5 tries)", dnsErr), 19},
-		{"dns by message", errors.New("dial tcp: lookup nope.invalid: no such host"), 19},
 		{"refused typed", refused, 6},
 		{"refused wrapped through retries", fmt.Errorf("http://x: %w (after 5 tries)", refused), 6},
-		{"refused by message", errors.New("dial tcp 127.0.0.1:1: connect: connection refused"), 6},
 		{"not found", fmt.Errorf("%w: http://x/y: 404 Not Found", httpdl.ErrNotFound), 3},
-		{"too slow", fmt.Errorf("http://x: %w (<= %d bytes/sec)", httpdl.ErrTooSlow, 1024), 5},
 		{"checksum", fmt.Errorf("/tmp/x: %w (want a, got b)", httpdl.ErrChecksum), 32},
 		{"duplicate", fmt.Errorf("%w: same torrent as y", errDuplicate), 12},
 		{"unknown", errors.New("disk full"), 1},
@@ -103,7 +103,7 @@ func TestDedupeTorrents(t *testing.T) {
 	c := "magnet:?xt=urn:btih:1111111111111111111111111111111111111111&dn=other"
 	web := "http://example.com/file.iso"
 
-	dup := dedupeTorrents([]string{a, web, b, c}, true)
+	dup := dedupeTorrents([]string{a, web, b, c})
 
 	// b is the only duplicate (of a); a, web and c are not duplicates.
 	if len(dup) != 1 || dup[b] != a {
@@ -112,8 +112,8 @@ func TestDedupeTorrents(t *testing.T) {
 }
 
 // TestGatherURIsGrouping checks the command-line grouping: plain http URIs
-// become one mirrored download by default, -Z splits them, and torrents/magnets
+// become one mirrored download by default, -Z splits them, and torrents,
-// stay separate.
+// magnets, and .torrent URLs stay separate.
 func TestGatherURIsGrouping(t *testing.T) {
 	parse := func(args ...string) []target {
 		res, err := cli.Parse(append([]string{"--no-conf"}, args...))
@@ -131,6 +131,43 @@ func TestGatherURIsGrouping(t *testing.T) {
 	if ts := parse("http://a/x", "magnet:?xt=urn:btih:abc"); len(ts) != 2 {
 		t.Errorf("http + magnet: got %d targets, want 2 (magnet never mirrors)", len(ts))
 	}
+	// Distinct .torrent URLs are separate downloads, not mirrors of one file
+	// (follow-torrent defaults on, so each is fetched then followed).
+	if ts := parse("http://a/x.torrent", "http://b/y.torrent", "http://c/z.torrent"); len(ts) != 3 {
+		t.Errorf(".torrent URLs: got %d targets, want 3 separate downloads", len(ts))
+	}
+	// A plain http URL still mirror-groups even alongside a .torrent URL: one
+	// http group of 1 + one torrent target = 2.
+	if ts := parse("http://a/x", "http://b/y.torrent"); len(ts) != 2 {
+		t.Errorf("http + .torrent: got %d targets, want 2", len(ts))
+	}
+}
+
+// TestHTTPConnDefault locks the parallelism default: a bare `got URL` must use
+// several connections, not one. --split is the single speed dial — it is the
+// connection count directly, defaulting to 5.
+func TestHTTPConnDefault(t *testing.T) {
+	cfg := func(args ...string) httpdl.Config {
+		res, err := cli.Parse(append([]string{"--no-conf"}, args...))
+		if err != nil {
+			t.Fatalf("parse %v: %v", args, err)
+		}
+		return httpConfig(res.Options, true, nil)
+	}
+	tests := []struct {
+		name string
+		args []string
+		want int
+	}{
+		{"bare URL uses split default", []string{"http://a/x"}, 5},
+		{"-s16 means 16", []string{"-s16", "http://a/x"}, 16},
+		{"-s1 stays single", []string{"-s1", "http://a/x"}, 1},
+	}
+	for _, tc := range tests {
+		if c := cfg(tc.args...); c.Split != tc.want {
+			t.Errorf("%s: Split = %d, want %d", tc.name, c.Split, tc.want)
+		}
+	}
 }
 
 // TestReadInputFileTAB checks the input-file grouping: TAB-separated URIs on
@@ -152,10 +189,69 @@ func TestReadInputFileTAB(t *testing.T) {
 	}
 }
 
+// writeTorrent creates a .torrent file at dir/name whose info dict is built from
+// a file of the given content and internal name. Two calls with the same
+// internalName and content produce the same infohash regardless of the output
+// filename, so the test can make two .torrent files that name one torrent.
+func writeTorrent(t *testing.T, dir, name, internalName string, content []byte) string {
+	t.Helper()
+	data := filepath.Join(dir, internalName)
+	if err := os.WriteFile(data, content, 0o644); err != nil {
+		t.Fatal(err)
+	}
+	info := metainfo.Info{PieceLength: 32 * 1024}
+	if err := info.BuildFromFilePath(data); err != nil {
+		t.Fatal(err)
+	}
+	b, err := bencode.Marshal(info)
+	if err != nil {
+		t.Fatal(err)
+	}
+	tp := filepath.Join(dir, name)
+	f, err := os.Create(tp)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer f.Close()
+	if err := (&metainfo.MetaInfo{InfoBytes: b}).Write(f); err != nil {
+		t.Fatal(err)
+	}
+	return tp
+}
+
+// TestFollowUpInfoHashDedup covers the fix for two fetched .torrent files that
+// name the same torrent: the second must be flagged a duplicate so followUps
+// fails it rather than letting both share — and Drop — one torrent on the client.
+func TestFollowUpInfoHashDedup(t *testing.T) {
+	dir := t.TempDir()
+	a := writeTorrent(t, dir, "a.torrent", "same", []byte("AAAAAAAA"))
+	b := writeTorrent(t, dir, "b.torrent", "same", []byte("AAAAAAAA")) // same infohash as a
+	c := writeTorrent(t, dir, "c.torrent", "diff", []byte("BBBBBBBB")) // a distinct torrent
+
+	// Sanity-check the fixture: a and b really share an infohash, c differs.
+	ha, _ := bt.SourceInfoHash(a, true)
+	hb, _ := bt.SourceInfoHash(b, true)
+	hc, _ := bt.SourceInfoHash(c, true)
+	if ha != hb || ha == hc {
+		t.Fatalf("fixture: want a==b!=c infohashes, got a=%v b=%v c=%v", ha, hb, hc)
+	}
+
+	seen := map[metainfo.Hash]string{}
+	if first, dup := seenInfoHash(seen, a, true); dup {
+		t.Fatalf("a is the first occurrence, wrongly flagged a duplicate of %s", first)
+	}
+	if first, dup := seenInfoHash(seen, b, true); !dup || first != a {
+		t.Errorf("b should duplicate a: got first=%q dup=%v, want %q true", first, dup, a)
+	}
+	if _, dup := seenInfoHash(seen, c, true); dup {
+		t.Errorf("c is a distinct torrent, wrongly flagged a duplicate")
+	}
+}
+
 func TestReportExit(t *testing.T) {
 	canceled := download.Result{Name: "a", Err: context.Canceled}
 	done := download.Result{Name: "b", Err: nil}
-	timeout := download.Result{Name: "c", Err: errors.New("idle timeout")}
+	timeout := download.Result{Name: "c", Err: httpdl.ErrTimeout}
 
 	tests := []struct {
 		name    string

progress/format.go

@@ -41,12 +41,6 @@ func humanSize(n int64, human bool) string {
 	return fmt.Sprintf("%.0f%ciB", val, suffix)
 }
 
-// speed formats a bytes-per-second rate. The DL:/UL: fields show the bare
-// abbreviated size with no "/s" suffix.
-func speed(bytesPerSec int64, human bool) string {
-	return humanSize(bytesPerSec, human)
-}
-
 // secfmt renders a duration as "1h2m3s", appending each unit only when it is
 // nonzero (but still showing seconds when the whole input is 0):
 // 3600s->"1h", 120s->"2m", 3720s->"1h2m". A non-positive or absurd

progress/format_test.go

@@ -53,16 +53,6 @@ func TestSecfmt(t *testing.T) {
 	}
 }
 
-func TestSpeedNoSuffix(t *testing.T) {
-	// The DL:/UL: fields show the bare abbreviated size with no "/s".
-	if got := speed(1536, true); got != "1.5KiB" {
-		t.Errorf("speed(1536,true) = %q, want %q", got, "1.5KiB")
-	}
-	if got := speed(2048, false); got != "2048B" {
-		t.Errorf("speed(2048,false) = %q, want %q", got, "2048B")
-	}
-}
-
 func TestPercent(t *testing.T) {
 	if got := percent(50, 100); got != 50 {
 		t.Errorf("percent(50,100) = %d, want 50", got)

progress/progress.go

@@ -1,7 +1,8 @@
-// Package progress renders a live, single-line status display. One goroutine ticks
+// Package progress renders a live status display: a summary line over one
-// once a second, pulls a snapshot of the running downloads, and derives speeds
+// aligned row per download, collapsing to the summary alone when the rows would
-// from the change since the previous tick. There are no locks here: the data
+// not fit. One goroutine ticks once a second, pulls a snapshot of the running
-// arrives by value through the snapshot function.
+// downloads, and derives speeds from the change since the previous tick. There
+// are no locks here: the data arrives by value through the snapshot function.
 package progress
 
 import (
@@ -9,6 +10,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"strconv"
 	"strings"
 	"time"
 	"unicode/utf8"
@@ -25,8 +27,10 @@ type Reporter struct {
 	w        io.Writer
 	tty      bool
 	width    int
+	height   int
 
 	win       map[string]*speedWindow // keyed by Stat.ID
+	prevLines int                     // lines drawn in the previous TTY frame, redrawn in place
 	lastLog   time.Time               // last non-TTY line emitted
 }
 
@@ -62,6 +66,7 @@ func New(snap func() []download.Stat, human bool) *Reporter {
 		w:        os.Stdout,
 		tty:      term.IsTerminal(int(os.Stdout.Fd())),
 		width:    80,
+		height:   24,
 		win:      map[string]*speedWindow{},
 	}
 }
@@ -103,89 +108,251 @@ func (r *Reporter) render(final bool) {
 		}
 	}
 
-	var line string
-	switch len(stats) {
-	case 0:
-		if !final && r.tty {
-			return // nothing active; leave the line as-is
-		}
-	case 1:
-		line = r.lineOne(stats[0])
-	default:
-		line = r.lineMany(stats)
-	}
-
 	if r.tty {
 		r.width = termWidth(r.width)
-		line = clampRunes(line, r.width)
+		r.height = termHeight(r.height)
-		fmt.Fprint(r.w, "\r"+line+"\x1b[K")
+		r.redraw(r.block(stats), final)
-		if final {
-			fmt.Fprintln(r.w)
-		}
 		return
 	}
-	// Not a TTY: can't redraw one line, so print sparingly (and always the
+	// Not a TTY: no cursor control, so emit the summary line sparingly (and always
-	// final line) to keep redirected output and logs readable.
+	// the final one) to keep redirected output and logs readable.
+	var line string
+	if len(stats) > 0 {
+		line = r.summary(stats)
+	}
 	if line != "" && (final || now.Sub(r.lastLog) >= logEvery) {
 		fmt.Fprintln(r.w, line)
 		r.lastLog = now
 	}
 }
 
-func (r *Reporter) lineOne(s download.Stat) string {
+// nameW is the fixed rune width of the name column in the table, matching
-	dl, ul := r.rates(s)
+// elide's cap so a padded name lines the columns up.
-	seeding := s.Status == download.Seeding
+const nameW = 20
-	var b strings.Builder
+
-	fmt.Fprintf(&b, "[%s ", shortName(s.Name))
+// block builds the lines of the live display: a summary line, the column header,
-	// While seeding, report the share ratio in place of the size block and drop
+// and one row per download — or just the one-line summary when the table would
-	// the DL: field; otherwise show completed/total (or bare completed).
+// not fit the window. A single download renders the same way as several.
-	if seeding {
+func (r *Reporter) block(stats []download.Stat) []string {
-		fmt.Fprintf(&b, "SEED(%.1f)", ratio(s.Uploaded, s.Completed))
+	if len(stats) == 0 {
-	} else if s.Total > 0 {
+		return nil
-		fmt.Fprintf(&b, "%s/%s(%d%%)", humanSize(s.Completed, r.human), humanSize(s.Total, r.human), percent(s.Completed, s.Total))
-	} else {
-		b.WriteString(humanSize(s.Completed, r.human))
 	}
-	// CN is always shown (including HTTP); SD is shown for any torrent.
+	if len(stats)+3 > r.height {
-	fmt.Fprintf(&b, " CN:%d", s.Conns)
+		// The block is repainted in place by moving the cursor up over it, which
-	if s.IsBT {
+		// breaks if printing the last row reaches the screen's bottom row and
-		fmt.Fprintf(&b, " SD:%d", s.Seeders)
+		// scrolls the frame out from under the cursor. term height counts the row
+		// the shell prompt occupies, so a summary + header + one row each
+		// (len+2 lines) must still leave the bottom row free: fall back to the
+		// single summary line once len+2 would fill to the bottom.
+		return []string{r.summary(stats)}
 	}
-	if !seeding {
+	out := make([]string, 0, len(stats)+2)
-		fmt.Fprintf(&b, " DL:%s", speed(dl, r.human))
+	out = append(out, r.summary(stats), tableHeader())
+	for _, s := range stats {
+		out = append(out, r.tableRow(s))
 	}
-	if seeding || ul > 0 {
+	return out
-		fmt.Fprintf(&b, " UL:%s", speed(ul, r.human))
-	}
-	if !seeding && s.Total > 0 && dl > 0 {
-		eta := time.Duration(float64(s.Total-s.Completed)/float64(dl)) * time.Second
-		fmt.Fprintf(&b, " ETA:%s", secfmt(eta))
-	}
-	b.WriteByte(']')
-	return b.String()
 }
 
-func (r *Reporter) lineMany(stats []download.Stat) string {
+// redraw repaints the block in place: move to the top of the previous frame,
+// clear it, and print the new lines clamped to the terminal width. A stray line
+// from stderr that lands in the block is painted over on the next tick.
+func (r *Reporter) redraw(lines []string, final bool) {
+	if r.prevLines > 0 {
+		if r.prevLines > 1 {
+			fmt.Fprintf(r.w, "\x1b[%dA", r.prevLines-1) // up to the first line
+		}
+		fmt.Fprint(r.w, "\r\x1b[J") // column 0, clear to end of screen
+	}
+	for i, ln := range lines {
+		if i > 0 {
+			fmt.Fprint(r.w, "\n")
+		}
+		fmt.Fprint(r.w, clampRunes(ln, r.width))
+	}
+	r.prevLines = len(lines)
+	if final && len(lines) > 0 {
+		fmt.Fprintln(r.w) // leave the cursor below the block for the OK/FAIL lines
+		r.prevLines = 0
+	}
+}
+
+// summary is the header/aggregate line: a count of downloads in each state, the
+// total down/up speed, and a stalled count when any download has gone quiet. The
+// state breakdown replaces a single "active" tally so seeding and queued
+// downloads are not lumped in with the ones actually moving bytes.
+func (r *Reporter) summary(stats []download.Stat) string {
+	if len(stats) == 0 {
+		return ""
+	}
 	var totDL, totUL int64
+	var downloading, seeding, queued, stalled int
 	for _, s := range stats {
 		dl, ul := r.rates(s)
 		totDL += dl
 		totUL += ul
-	}
+		switch s.Status {
-	var b strings.Builder
+		case download.Waiting:
-	fmt.Fprintf(&b, "[%d active DL:%s UL:%s]", len(stats), speed(totDL, r.human), speed(totUL, r.human))
+			queued++
-	for i, s := range stats {
+		case download.Seeding:
-		if i >= 4 {
+			seeding++
-			fmt.Fprintf(&b, "[+%d]", len(stats)-i)
+		default:
-			break
+			downloading++
-		}
+			if r.isStalled(s, dl) {
-		if s.Total > 0 {
+				stalled++
-			fmt.Fprintf(&b, "[%s %d%%]", shortName(s.Name), percent(s.Completed, s.Total))
-		} else {
-			fmt.Fprintf(&b, "[%s %s]", shortName(s.Name), humanSize(s.Completed, r.human))
 			}
 		}
-	return b.String()
+	}
+	parts := []string{fmt.Sprintf("%d downloading", downloading)}
+	if seeding > 0 {
+		parts = append(parts, fmt.Sprintf("%d seeding", seeding))
+	}
+	if queued > 0 {
+		parts = append(parts, fmt.Sprintf("%d queued", queued))
+	}
+	line := strings.Join(parts, " · ") + fmt.Sprintf("   DL %s  UL %s", r.rateStr(totDL), r.rateStr(totUL))
+	if stalled > 0 {
+		line += fmt.Sprintf("  (%d stalled)", stalled)
+	}
+	return line
+}
+
+// tableHeader names the columns once so the rows can drop the per-field DL:/UL:
+// labels. It uses tableRow's exact format string so the headings line up over
+// their columns. SIZE is completed/total; CN is the connection/peer count and SD
+// the connected seeders — the fields that tell a stalled download (no peers)
+// from a slow one (peers, no speed).
+func tableHeader() string {
+	return fmt.Sprintf("%s  %4s  %-13s  %-8s  %3s %3s  %s", padRune("NAME", nameW), "%", "SIZE", "RATE", "CN", "SD", "ETA")
+}
+
+// tableRow renders one download as aligned columns under tableHeader:
+// "name pct size rate cn sd tail". The name is middle-elided to keep its
+// distinguishing tail; percent, rate and the peer counts are fixed-width so the
+// digits scan straight down; size is completed/total; the rate column carries
+// the download speed or a state word (seeding/queued/...), and the tail carries
+// the ETA, the share ratio while seeding, or a stalled flag.
+func (r *Reporter) tableRow(s download.Stat) string {
+	dl, ul := r.rates(s)
+	rate, tail := r.rowMetric(s, dl, ul)
+	cn, sd := peerFields(s)
+	row := fmt.Sprintf("%s  %4s  %-13s  %-8s  %3s %3s  %s", padRune(elide(s.Name, nameW), nameW), pctField(s), sizeField(s, r.human), rate, cn, sd, tail)
+	// A queued row's trailing SIZE/CN/SD/ETA columns are blank; drop the trailing
+	// spaces so the line ends where its content does.
+	return strings.TrimRight(row, " ")
+}
+
+// sizeField is the absolute-progress column: completed/total (e.g.
+// "950MiB/5.0GiB"), just the completed bytes when the total is unknown (an HTTP
+// stream with no Content-Length, or a pre-metadata magnet), or blank for a
+// download that has not started.
+func sizeField(s download.Stat, human bool) string {
+	switch {
+	case s.Status == download.Waiting:
+		return ""
+	case s.Total > 0:
+		return humanSize(s.Completed, human) + "/" + humanSize(s.Total, human)
+	case s.Completed > 0:
+		return humanSize(s.Completed, human)
+	default:
+		return ""
+	}
+}
+
+// peerFields formats the connection (CN) and seeder (SD) columns. SD is blank
+// for HTTP, which has no seeders, and both are blank for a download with no live
+// connections (queued, done, failed) so the columns aren't noise where they
+// carry no meaning.
+func peerFields(s download.Stat) (cn, sd string) {
+	switch s.Status {
+	case download.Active, download.Seeding:
+		cn = strconv.Itoa(s.Conns)
+		if s.IsBT {
+			sd = strconv.Itoa(s.Seeders)
+		}
+	}
+	return cn, sd
+}
+
+// rowMetric returns a table row's rate column and its tail for the download's
+// state: the rate is the download speed or the state word (seeding/queued/done/
+// failed); the tail is an ETA, the share ratio while seeding (the seed-stop
+// criterion, more telling than an idle upload rate), or a "stalled" flag.
+func (r *Reporter) rowMetric(s download.Stat, dl, ul int64) (rate, tail string) {
+	switch s.Status {
+	case download.Waiting:
+		return "queued", ""
+	case download.Seeding:
+		return "seeding", fmt.Sprintf("r%.2f", ratio(s.Uploaded, s.Completed))
+	case download.Complete:
+		return "done", ""
+	case download.Errored:
+		return "failed", ""
+	default:
+		rate = r.rateStr(dl)
+		switch {
+		case dl > 0 && s.Total > 0:
+			tail = secfmt(etaDuration(s.Total-s.Completed, dl))
+		case r.isStalled(s, dl):
+			tail = "stalled"
+		}
+		return rate, tail
+	}
+}
+
+// rateStr formats a bytes/sec speed for display, e.g. "388KiB/s".
+func (r *Reporter) rateStr(bps int64) string {
+	return humanSize(bps, r.human) + "/s"
+}
+
+// maxETASeconds caps an ETA before it becomes a Duration: a near-stalled download
+// yields an astronomically large seconds value, and time.Duration(secs) *
+// time.Second would overflow int64 and wrap to a bogus tiny ETA. secfmt renders
+// anything past 99h as "--", so clamping to 100h loses nothing.
+const maxETASeconds = 100 * 3600
+
+func etaDuration(remaining, dl int64) time.Duration {
+	secs := float64(remaining) / float64(dl)
+	if secs > maxETASeconds {
+		secs = maxETASeconds
+	}
+	return time.Duration(secs) * time.Second
+}
+
+// isStalled reports an active download that has gone a while with no new bytes,
+// so the table can flag it rather than leave the eye to read DL:0B. A download
+// too young to have a rate yet is not stalled.
+func (r *Reporter) isStalled(s download.Stat, dl int64) bool {
+	if s.Status != download.Active || dl > 0 {
+		return false
+	}
+	w := r.win[s.ID]
+	if w == nil || len(w.samples) < 2 {
+		return false
+	}
+	return w.samples[len(w.samples)-1].t.Sub(w.samples[0].t) >= 4*time.Second
+}
+
+// pctField is the percent column: a number, full for seeding/complete, or "--"
+// when the total is unknown.
+func pctField(s download.Stat) string {
+	switch {
+	case s.Status == download.Seeding || s.Status == download.Complete:
+		return "100%"
+	case s.Total > 0:
+		return fmt.Sprintf("%3d%%", percent(s.Completed, s.Total))
+	default:
+		return "  --"
+	}
+}
+
+// padRune right-pads s with spaces to w runes (it is never longer, having been
+// through shortName) so table columns line up on rune count.
+func padRune(s string, w int) string {
+	if n := utf8.RuneCountInString(s); n < w {
+		return s + strings.Repeat(" ", w-n)
+	}
+	return s
 }
 
 // add records a sample and drops any that have fallen out of the window. A
@@ -244,15 +411,25 @@ func ratio(uploaded, completed int64) float64 {
 	return float64(uploaded) / float64(completed)
 }
 
-func shortName(s string) string {
+// elide shortens s to at most w runes, keeping the head and the tail joined by a
-	const max = 20
+// single "…". Download names often share a long prefix (a release group, a
-	// Truncate on runes, not bytes, so a multibyte name (CJK, emoji) is never
+// series) and differ only at the end (an episode or volume number), so dropping
-	// cut mid-rune.
+// the middle keeps what tells two downloads apart — where a leading-only
-	if utf8.RuneCountInString(s) > max {
+// truncation would collapse them to the same string. A name within w prints
-		return string([]rune(s)[:max-1]) + "~"
+// whole. It works on runes, never bytes, so a multibyte glyph (CJK, emoji) is
-	}
+// never split.
+func elide(s string, w int) string {
+	r := []rune(s)
+	if len(r) <= w {
 		return s
 	}
+	if w <= 1 {
+		return string(r[:w])
+	}
+	head := w / 2        // the w-1 kept runes split around one "…",
+	tail := w - 1 - head // head taking the extra rune when w is even
+	return string(r[:head]) + "…" + string(r[len(r)-tail:])
+}
 
 // clampRunes limits a line to width runes (not bytes) so multibyte glyphs are
 // never split when the terminal is narrow. A non-positive width leaves it whole.
@@ -272,3 +449,13 @@ func termWidth(prev int) int {
 	}
 	return 80
 }
+
+func termHeight(prev int) int {
+	if _, h, err := term.GetSize(int(os.Stdout.Fd())); err == nil && h > 0 {
+		return h
+	}
+	if prev > 0 {
+		return prev
+	}
+	return 24
+}

progress/progress_test.go

@@ -1,9 +1,11 @@
 package progress
 
 import (
+	"bytes"
 	"strings"
 	"testing"
 	"time"
+	"unicode/utf8"
 
 	"github.com/hanbok/got/download"
 )
@@ -76,52 +78,148 @@ func TestRatesKeyedByID(t *testing.T) {
 	}
 }
 
-// TestLineOneSeeding: while seeding, render SEED(ratio), drop DL:, keep UL:.
+func TestPctField(t *testing.T) {
-func TestLineOneSeeding(t *testing.T) {
+	if got := pctField(download.Stat{Status: download.Active, Total: 100, Completed: 50}); got != " 50%" {
-	r := newReporter(true)
+		t.Errorf("active 50%% = %q, want ' 50%%'", got)
-	s := download.Stat{
-		ID: "h", Name: "f", IsBT: true, Status: download.Seeding,
-		Total: 1000, Completed: 1000, Uploaded: 1500, Conns: 3, Seeders: 2,
 	}
-	line := r.lineOne(s)
+	if got := pctField(download.Stat{Status: download.Seeding}); got != "100%" {
-	if !strings.Contains(line, "SEED(1.5)") {
+		t.Errorf("seeding = %q, want 100%%", got)
-		t.Errorf("missing SEED(1.5): %q", line)
 	}
-	if strings.Contains(line, "DL:") {
+	if got := pctField(download.Stat{Status: download.Active, Total: -1}); got != "  --" {
-		t.Errorf("DL: should be dropped while seeding: %q", line)
+		t.Errorf("unknown total = %q, want '  --'", got)
-	}
-	if !strings.Contains(line, "UL:") {
-		t.Errorf("UL: should be kept while seeding: %q", line)
 	}
 }
 
-// TestLineOneCNSD: CN always shown; SD shown for torrents (even with 0 seeders),
+// TestRowMetric: the rate column and trailing field per download state.
-// absent for HTTP.
+func TestRowMetric(t *testing.T) {
-func TestLineOneCNSD(t *testing.T) {
 	r := newReporter(true)
-	bt := r.lineOne(download.Stat{ID: "h", Name: "f", IsBT: true, Total: 10, Completed: 1, Conns: 4, Seeders: 0})
+	if rate, tail := r.rowMetric(download.Stat{Status: download.Active, Total: 100, Completed: 50}, 10, 0); !strings.HasSuffix(rate, "/s") || tail == "" {
-	if !strings.Contains(bt, "CN:4") || !strings.Contains(bt, "SD:0") {
+		t.Errorf("active downloading: rate=%q tail=%q, want a …/s rate + an ETA", rate, tail)
-		t.Errorf("torrent line missing CN/SD: %q", bt)
 	}
-	http := r.lineOne(download.Stat{ID: "h2", Name: "f", IsBT: false, Total: 10, Completed: 1, Conns: 1})
+	if rate, tail := r.rowMetric(download.Stat{Status: download.Seeding, Completed: 1000, Uploaded: 1500}, 0, 0); rate != "seeding" || tail != "r1.50" {
-	if !strings.Contains(http, "CN:1") {
+		t.Errorf("seeding: rate=%q tail=%q, want seeding + r1.50 (share ratio)", rate, tail)
-		t.Errorf("http line missing CN: %q", http)
 	}
-	if strings.Contains(http, "SD:") {
+	if rate, _ := r.rowMetric(download.Stat{Status: download.Complete}, 0, 0); rate != "done" {
-		t.Errorf("http line should not show SD: %q", http)
+		t.Errorf("complete rate=%q, want done", rate)
 	}
 }
 
-// TestShortNameRune ensures CJK names are truncated on runes, not bytes.
+// TestPeerFields: CN (connections/peers) and SD (seeders) show for active and
-func TestShortNameRune(t *testing.T) {
+// seeding downloads; SD is blank for HTTP; both blank when there are no live
+// connections (queued).
+func TestPeerFields(t *testing.T) {
+	if cn, sd := peerFields(download.Stat{Status: download.Active, IsBT: true, Conns: 18, Seeders: 4}); cn != "18" || sd != "4" {
+		t.Errorf("active torrent: cn=%q sd=%q, want 18 / 4", cn, sd)
+	}
+	if cn, sd := peerFields(download.Stat{Status: download.Active, IsBT: false, Conns: 5}); cn != "5" || sd != "" {
+		t.Errorf("active http: cn=%q sd=%q, want 5 / blank", cn, sd)
+	}
+	if cn, sd := peerFields(download.Stat{Status: download.Waiting, Conns: 0}); cn != "" || sd != "" {
+		t.Errorf("queued: cn=%q sd=%q, want blank / blank", cn, sd)
+	}
+}
+
+// TestSizeField: completed/total when the total is known, just the completed
+// bytes when it is not, and blank for a queued download.
+func TestSizeField(t *testing.T) {
+	if got := sizeField(download.Stat{Status: download.Active, Completed: 512, Total: 2048}, false); got != "512B/2048B" {
+		t.Errorf("known total = %q, want 512B/2048B", got)
+	}
+	if got := sizeField(download.Stat{Status: download.Active, Completed: 512, Total: -1}, false); got != "512B" {
+		t.Errorf("unknown total = %q, want 512B", got)
+	}
+	if got := sizeField(download.Stat{Status: download.Waiting, Total: 2048}, false); got != "" {
+		t.Errorf("queued = %q, want blank", got)
+	}
+}
+
+// TestBlockTableAndFallback: several downloads render as summary+header+rows when
+// they fit, and collapse to a single summary line when the window is too short.
+// The fallback must leave the terminal's bottom row free (the stacked-summary
+// redraw fix): summary+header+2 rows is 4 lines, so it needs height >= 5.
+func TestBlockTableAndFallback(t *testing.T) {
+	r := newReporter(true)
+	stats := []download.Stat{
+		{ID: "a", Name: "a", Status: download.Active, Total: 100, Completed: 50},
+		{ID: "b", Name: "b", Status: download.Active, Total: 100, Completed: 10},
+	}
+	r.height = 24
+	if got := r.block(stats); len(got) != 4 { // summary + header + 2 rows
+		t.Errorf("table block = %d lines, want 4:\n%v", len(got), got)
+	}
+	// A single download renders the same way as several: summary + header + 1 row.
+	if got := r.block(stats[:1]); len(got) != 3 {
+		t.Errorf("single-download block = %d lines, want 3 (summary+header+row):\n%v", len(got), got)
+	}
+	r.height = 5 // 4 lines fit with the bottom row left free
+	if got := r.block(stats); len(got) != 4 {
+		t.Errorf("just-fits block = %d lines, want 4:\n%v", len(got), got)
+	}
+	r.height = 4 // one short: would fill to the bottom row, so fall back
+	if got := r.block(stats); len(got) != 1 {
+		t.Errorf("overflow block = %d lines, want 1 summary:\n%v", len(got), got)
+	}
+}
+
+// TestRenderRedraw: the TTY path draws the block, then on the next frame moves
+// the cursor up over the previous frame and clears it before repainting.
+func TestRenderRedraw(t *testing.T) {
+	snap := []download.Stat{
+		{ID: "a", Name: "alpha", IsBT: true, Status: download.Active, Total: 100, Completed: 50},
+		{ID: "b", Name: "beta", IsBT: true, Status: download.Seeding, Total: 100, Completed: 100, Uploaded: 200},
+	}
+	var buf bytes.Buffer
+	r := &Reporter{
+		snap:  func() []download.Stat { return snap },
+		human: true, w: &buf, tty: true, width: 200, height: 24,
+		win: map[string]*speedWindow{},
+	}
+	r.render(false)
+	first := buf.String()
+	for _, want := range []string{"downloading", "seeding", "alpha", "NAME"} {
+		if !strings.Contains(first, want) {
+			t.Fatalf("first frame missing %q:\n%q", want, first)
+		}
+	}
+	if strings.Contains(first, "|") {
+		t.Errorf("first frame should carry no progress bar:\n%q", first)
+	}
+	buf.Reset()
+	r.render(false)
+	second := buf.String()
+	if !strings.Contains(second, "\x1b[3A") { // up prevLines-1 = 4-1 (summary+header+2 rows)
+		t.Errorf("second frame should move cursor up 3 lines:\n%q", second)
+	}
+	if !strings.Contains(second, "\x1b[J") {
+		t.Errorf("second frame should clear to end of screen:\n%q", second)
+	}
+}
+
+// TestElideKeepsTail: names sharing a long prefix but differing at the end stay
+// distinct — the failure the old leading truncation caused — and the result is
+// capped at the column width on runes with the distinguishing tail preserved.
+func TestElideKeepsTail(t *testing.T) {
+	a := elide("[Group] Long Common Series Name vol.1", nameW)
+	b := elide("[Group] Long Common Series Name vol.2", nameW)
+	if a == b {
+		t.Errorf("names differing only in the tail collapsed: %q == %q", a, b)
+	}
+	if n := utf8.RuneCountInString(a); n != nameW {
+		t.Errorf("elide rune count = %d, want %d (%q)", n, nameW, a)
+	}
+	if !strings.Contains(a, "…") {
+		t.Errorf("expected a middle ellipsis: %q", a)
+	}
+	if !strings.HasSuffix(a, "vol.1") {
+		t.Errorf("expected the distinguishing tail kept: %q", a)
+	}
+}
+
+// TestElideRune ensures CJK names are elided on runes, not bytes.
+func TestElideRune(t *testing.T) {
 	name := strings.Repeat("あ", 30) // 30 runes, 90 bytes
-	got := shortName(name)
+	if n := utf8.RuneCountInString(elide(name, nameW)); n != nameW {
-	runes := []rune(got)
+		t.Errorf("elide rune count = %d, want %d", n, nameW)
-	if len(runes) != 20 {
-		t.Errorf("shortName rune count = %d, want 20", len(runes))
-	}
-	if runes[len(runes)-1] != '~' {
-		t.Errorf("expected trailing ~, got %q", got)
 	}
 }