all: reword comments to state behavior directly

Comments (and one test comment) now describe the rules on their own terms
instead of by comparison to another downloader. No behavior change.

bt/bt.go

@@ -313,8 +313,8 @@ func (d *Download) Run(ctx context.Context) (err error) {
 	}
 
 	// --check-integrity: re-hash the existing on-disk data BEFORE arming the
-	// request loop, so already-good pieces are not re-requested from peers (aria2
-	// verifies first, then fetches only what is missing).
+	// 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
@@ -376,8 +376,8 @@ func (d *Download) choose(t *torrent.Torrent) error {
 // metadataTimeout bounds the magnet metadata-fetch phase. A magnet with no
 // reachable peers — a dead link, or UDP trackers behind a firewall with no DHT —
 // would otherwise hang forever, so awaitInfo gives up after this fixed window.
-// It is not a user-facing flag: aria2 has no --bt-metadata-timeout, and 60s is a
-// generous ceiling that a healthy swarm clears in well under a second.
+// It is not a user-facing flag — 60s is a generous ceiling that a healthy swarm
+// clears in well under a second.
 const metadataTimeout = 60 * time.Second
 
 // awaitInfo blocks until the torrent metadata arrives, giving up after

cli/options.go

@@ -27,9 +27,8 @@ 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 accepted vocabulary for boolean options. aria2 takes only
-// true/false (and rejects everything else), so we match it rather than inventing
-// extra spellings. boolWord is the single consult point — the Bool reader,
+// boolWords is the accepted vocabulary for boolean options: exactly true and
+// false, nothing else. boolWord is the single consult point — the Bool reader,
 // validate(), and the no-conf bootstrap all go through it — so exactly the words
 // that validate are honoured.
 var boolWords = map[string]bool{
@@ -38,9 +37,8 @@ var boolWords = map[string]bool{
 }
 
 // boolWord reports a value's truth and whether it is a recognised boolean word.
-// Whitespace is trimmed (aria2 strips config values too), but case is
-// significant: aria2 rejects "True"/"TRUE", so the match is against exactly
-// "true"/"false".
+// 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.TrimSpace(s)]
 	return val, ok

cli/parse_test.go

@@ -139,8 +139,8 @@ func TestValidateFloatNonNegative(t *testing.T) {
 
 func TestValidateBool(t *testing.T) {
 	b := byLong["enable-dht"]
-	// aria2 accepts only literal true/false (case-sensitive) but trims
-	// surrounding whitespace; match that exactly.
+	// Only literal true/false are accepted (case-sensitive), with surrounding
+	// whitespace trimmed.
 	for _, ok := range []string{"true", "false", " true ", "false\t"} {
 		if err := validate(b, ok); err != nil {
 			t.Errorf("validate bool %q: %v", ok, err)

main.go

@@ -509,7 +509,7 @@ func httpConfig(opts *cli.Options, single bool, overallDL *rate.Limiter) httpdl.
 	if single {
 		out = opts.Str("out")
 	}
-	// max-connection-per-server caps connections per host. aria2's default is 1,
+	// max-connection-per-server caps connections per host. Its default is 1,
 	// which on its own would clamp --split to a single connection, so a bare
 	// `got URL` would download single-threaded. Honor the literal default of 1
 	// only when the user actually set -x; otherwise let --split drive per-host

main_test.go

@@ -147,7 +147,7 @@ func TestGatherURIsGrouping(t *testing.T) {
 // TestHTTPConnDefault locks the parallelism default: a bare `got URL` must use
 // several connections, not one. With -x unset, --split drives the per-host
 // connection count (capped at the -x ceiling of 16); an explicit -x is honored
-// verbatim, including the aria2-faithful -x1 single connection.
+// verbatim, including -x1 for a single connection.
 func TestHTTPConnDefault(t *testing.T) {
 	cfg := func(args ...string) httpdl.Config {
 		res, err := cli.Parse(append([]string{"--no-conf"}, args...))