fix(auth): bound device match codes to eight letters (#535)

* fix(auth): bound device match codes to eight letters

* fix(auth): use farm-themed device match codes

---------

Co-authored-by: rxwatcher <rxwatcher@users.noreply.github.com>
Co-authored-by: Quick104 <31828688+Quick104@users.noreply.github.com>

internal/auth/device_login_words.go

@@ -6,24 +6,14 @@ import (
 )
 
 var deviceMatchAdjectives = []string{
-	"amber", "brisk", "calm", "cedar", "clear", "cloud", "copper", "crisp",
-	"delta", "ember", "fable", "fern", "frost", "gentle", "golden", "harbor",
-	"hazel", "hollow", "indigo", "ivy", "jade", "juniper", "kindle", "lagoon",
-	"linen", "lunar", "maple", "meadow", "misty", "navy", "nova", "oak",
-	"olive", "opal", "orbit", "pepper", "pine", "plum", "prairie", "quiet",
-	"raven", "river", "rose", "rustic", "sable", "sage", "scarlet", "silver",
-	"smoky", "solstice", "spruce", "stone", "summer", "sunny", "timber", "topaz",
-	"velvet", "violet", "willow", "winter", "woodland", "zephyr",
+	"blue", "busy", "calm", "cozy", "fast", "gold",
+	"kind", "soft", "tall", "tame", "tiny", "warm",
 }
 
 var deviceMatchNouns = []string{
-	"anchor", "apple", "birch", "brook", "canyon", "castle", "comet", "cove",
-	"crest", "dawn", "ember", "field", "fjord", "forest", "glade", "grove",
-	"harbor", "hawk", "hill", "island", "lake", "lantern", "meadow", "mesa",
-	"moon", "oasis", "ocean", "orchard", "owl", "pine", "planet", "pond",
-	"quartz", "rain", "reef", "ridge", "river", "rock", "shadow", "shore",
-	"signal", "snow", "spark", "star", "stone", "stream", "summit", "sun",
-	"thunder", "trail", "tree", "valley", "wave", "whisper", "wind", "wolf",
+	"barn", "bell", "cart", "coop", "corn", "cow", "duck", "goat",
+	"hay", "hen", "lamb", "milk", "oats", "pail", "pond", "pony",
+	"rake", "shed", "silo", "wool",
 }
 
 func randomMatchCode() (string, error) {

internal/auth/device_login_words_test.go

@@ -0,0 +1,21 @@
+package auth
+
+import "testing"
+
+func TestDeviceMatchCodeWordsStayWithinEightLetters(t *testing.T) {
+	const maxLetters = 8
+	const wantCombinations = 240
+	for _, adjective := range deviceMatchAdjectives {
+		for _, noun := range deviceMatchNouns {
+			if got := len(adjective) + len(noun); got > maxLetters {
+				t.Fatalf("match code %q has %d letters, want at most %d", adjective+" "+noun, got, maxLetters)
+			}
+		}
+	}
+
+	// The match phrase is a human confirmation signal, not the login secret,
+	// but keep enough combinations that accidental collisions remain uncommon.
+	if combinations := len(deviceMatchAdjectives) * len(deviceMatchNouns); combinations != wantCombinations {
+		t.Fatalf("match-code word lists have %d combinations, want exactly %d", combinations, wantCombinations)
+	}
+}