refactor(server): share env parsing, shutdown and score capping helpers

Collapse the three env parsers into one generic helper, the duplicated
graceful-shutdown block into shutdownServer, and the score cap into
pointsFor. Behaviour is unchanged.

server/cmd/noitu-server/main.go

@@ -145,15 +145,20 @@ func run() error {
 	slog.Info("shutting down", "rooms", api.RoomCount(), "live_games", api.LiveGameCount())
 	api.Shutdown()
 
-	if debugSrv != nil {
-		shutdownCtx, cancel := context.WithTimeout(context.Background(), shutdownGrace)
-		_ = debugSrv.Shutdown(shutdownCtx)
-		cancel()
-	}
+	_ = shutdownServer(debugSrv)
+	return shutdownServer(srv)
+}
 
-	shutdownCtx, cancel := context.WithTimeout(context.Background(), shutdownGrace)
+// shutdownServer stops srv gracefully, giving in-flight requests up to
+// shutdownGrace. A nil srv — the debug listener when it is not configured —
+// is a no-op.
+func shutdownServer(srv *http.Server) error {
+	if srv == nil {
+		return nil
+	}
+	ctx, cancel := context.WithTimeout(context.Background(), shutdownGrace)
 	defer cancel()
-	return srv.Shutdown(shutdownCtx)
+	return srv.Shutdown(ctx)
 }
 
 // newDebugServer builds the expvar listener, or nil when NOITU_DEBUG_ADDR is
@@ -222,19 +227,12 @@ func loadConfig() config {
 	}
 }
 
-// envInt falls back loudly, like envDuration. Zero means "use the built-in
-// default", so it is what an unset or invalid value becomes.
+// envInt falls back loudly, like envDuration. Zero is a real value — for the
+// limits it configures it means "use the built-in default" — so only a
+// negative or unparseable one is rejected.
 func envInt(key string, fallback int) int {
-	raw := strings.TrimSpace(os.Getenv(key))
-	if raw == "" {
-		return fallback
-	}
-	n, err := strconv.Atoi(raw)
-	if err != nil || n < 0 {
-		slog.Warn("ignoring invalid integer", "key", key, "value", raw, "using", fallback)
-		return fallback
-	}
-	return n
+	return envParsed(key, fallback, "ignoring invalid integer", strconv.Atoi,
+		func(n int) bool { return n >= 0 })
 }
 
 func env(key, fallback string) string {
@@ -249,32 +247,32 @@ func env(key, fallback string) string {
 // unparseable, which is right for every duration except the drain timeout —
 // see envNonNegDuration.
 func envDuration(key string, fallback time.Duration) time.Duration {
-	raw := strings.TrimSpace(os.Getenv(key))
-	if raw == "" {
-		return fallback
-	}
-	d, err := time.ParseDuration(raw)
-	if err != nil || d <= 0 {
-		slog.Warn("ignoring invalid duration", "key", key, "value", raw, "using", fallback)
-		return fallback
-	}
-	return d
+	return envParsed(key, fallback, "ignoring invalid duration", time.ParseDuration,
+		func(d time.Duration) bool { return d > 0 })
 }
 
 // envNonNegDuration is envDuration with zero accepted as a real value rather
 // than a trigger for the fallback: NOITU_DRAIN_TIMEOUT=0 means "do not wait",
 // which is a deliberate choice an operator can make explicitly, not a typo.
 func envNonNegDuration(key string, fallback time.Duration) time.Duration {
+	return envParsed(key, fallback, "ignoring invalid duration", time.ParseDuration,
+		func(d time.Duration) bool { return d >= 0 })
+}
+
+// envParsed reads key through parse, returning fallback when it is unset or
+// blank, and — with a warning, so a misconfiguration is visible rather than
+// silently ignored — when it fails to parse or is not valid.
+func envParsed[T any](key string, fallback T, invalidMsg string, parse func(string) (T, error), valid func(T) bool) T {
 	raw := strings.TrimSpace(os.Getenv(key))
 	if raw == "" {
 		return fallback
 	}
-	d, err := time.ParseDuration(raw)
-	if err != nil || d < 0 {
-		slog.Warn("ignoring invalid duration", "key", key, "value", raw, "using", fallback)
+	v, err := parse(raw)
+	if err != nil || !valid(v) {
+		slog.Warn(invalidMsg, "key", key, "value", raw, "using", fallback)
 		return fallback
 	}
-	return d
+	return v
 }
 
 // envList returns nil for an unset variable, which coder/websocket reads as

server/internal/dictionary/store.go

@@ -19,6 +19,7 @@ import (
 	"errors"
 	"fmt"
 	"iter"
+	"math/rand/v2"
 	"net/url"
 	"os"
 	"slices"
@@ -27,8 +28,6 @@ import (
 	"strings"
 	"unicode"
 
-	"math/rand/v2"
-
 	"golang.org/x/text/unicode/norm"
 	_ "modernc.org/sqlite"
 )
@@ -98,7 +97,7 @@ func Open(path string) (*Store, error) {
 		return nil, fmt.Errorf("dictionary not found at %s — run 'make fetch-dict && make dict' first: %w", path, err)
 	}
 
-	db, err := sql.Open("sqlite", dsn(path))
+	db, err := sql.Open("sqlite", DSN(path, true))
 	if err != nil {
 		return nil, fmt.Errorf("open dictionary: %w", err)
 	}
@@ -148,9 +147,6 @@ func Open(path string) (*Store, error) {
 	return s, nil
 }
 
-// dsn is the read-only URI the store opens with.
-func dsn(path string) string { return DSN(path, true) }
-
 // DSN builds a SQLite URI for path. The path must be escaped: SQLite reads
 // '#' as a URI fragment delimiter, so a bare path containing one silently
 // opens a different (usually nonexistent) file and reports a confusing schema

server/internal/dictionary/store_test.go

@@ -269,20 +269,13 @@ func TestResolveUnknown(t *testing.T) {
 	}
 }
 
-// nearMissFixtureAt builds a tiny dictionary purpose-built for NearMiss: one
+// nearMissFixture builds a tiny dictionary purpose-built for NearMiss: one
 // word with a unique stripped form, one ambiguous pair that shares a stripped
 // form with each other, and nothing else that could coincidentally collide.
-func nearMissFixtureAt(tb testing.TB, dir string) string {
+func nearMissFixture(tb testing.TB) *Store {
 	tb.Helper()
 
-	path := filepath.Join(dir, "nearmiss.db")
-	db, err := sql.Open("sqlite", "file:"+path)
-	if err != nil {
-		tb.Fatal(err)
-	}
-	defer func() { _ = db.Close() }()
-
-	data := fixtureSchema + `
+	path := writeDB(tb, fixtureSchema+`
 INSERT INTO meta VALUES ('source_license','CC BY-SA 4.0'),('word_count','4'),('meaning_count','0');
 INSERT INTO words VALUES
   ('bình yên','bình','yên',2),
@@ -292,17 +285,8 @@ INSERT INTO words VALUES
   ('ngữ nghĩa','ngữ','nghĩa',2),
   ('ngừ nghĩa','ngừ','nghĩa',2);
 INSERT INTO syllables VALUES ('bình',1),('an',1),('ngữ',1),('ngừ',1);
-`
-	if _, err := db.Exec(data); err != nil {
-		tb.Fatal(err)
-	}
-	return path
-}
-
-func nearMissFixture(tb testing.TB) *Store {
-	tb.Helper()
-
-	store, err := Open(nearMissFixtureAt(tb, tb.TempDir()))
+`)
+	store, err := Open(path)
 	if err != nil {
 		tb.Fatalf("Open: %v", err)
 	}

server/internal/game/engine.go

@@ -298,44 +298,30 @@ func (e *Engine) pointsFor(syllables int, link string, now time.Time) (int, []Po
 		{Kind: PointKindSpeed, Value: e.speedPoints(now)},
 		{Kind: PointKindRarity, Value: e.rarityPoints(link)},
 	}
-	parts = capParts(parts)
 
-	total := 0
-	for _, p := range parts {
-		total += p.Value
+	// Anything over maxPointsPerWord is trimmed from the end: rarity first,
+	// then speed, then syllables. Base and the chain term never need touching
+	// to make room — the chain term is itself capped at chainBonusWords words
+	// (10 base + 2*15 chain = 40 at most), well under the cap — so the loop
+	// always finds enough in the later terms and stops before reaching them.
+	for i, overflow := len(parts)-1, sumParts(parts)-maxPointsPerWord; i >= 0 && overflow > 0; i-- {
+		cut := min(parts[i].Value, overflow)
+		parts[i].Value -= cut
+		overflow -= cut
 	}
-	return total, parts
+
+	// A PointPart exists only for a term that actually contributed.
+	parts = slices.DeleteFunc(parts, func(p PointPart) bool { return p.Value <= 0 })
+	return sumParts(parts), parts
 }
 
-// capParts trims a word's score down to maxPointsPerWord when the terms
-// pointsFor computed add up to more, and drops whatever term that leaves at
-// zero — a PointPart exists only for a term that actually contributed.
-//
-// Trimmed from the end: rarity first, then speed, then syllables, then chain.
-// Base and the chain term never need touching to make room — the chain term
-// is itself capped at chainBonusWords words (10 base + 2*15 chain = 40 at
-// most), well under the cap — so the loop always finds enough in the later
-// terms and stops before reaching them.
-func capParts(parts []PointPart) []PointPart {
+// sumParts is the total a word's score breakdown adds up to.
+func sumParts(parts []PointPart) int {
 	total := 0
 	for _, p := range parts {
 		total += p.Value
 	}
-	if overflow := total - maxPointsPerWord; overflow > 0 {
-		for i := len(parts) - 1; i >= 0 && overflow > 0; i-- {
-			cut := min(parts[i].Value, overflow)
-			parts[i].Value -= cut
-			overflow -= cut
-		}
-	}
-
-	kept := parts[:0]
-	for _, p := range parts {
-		if p.Value > 0 {
-			kept = append(kept, p)
-		}
-	}
-	return kept
+	return total
 }
 
 // speedPoints pays for the share of the turn the player left on the clock.

server/internal/game/engine_test.go

@@ -477,14 +477,6 @@ func TestSubmitScoringPartsAreTrimmedAtTheCap(t *testing.T) {
 	}
 }
 
-func sumParts(parts []PointPart) int {
-	sum := 0
-	for _, p := range parts {
-		sum += p.Value
-	}
-	return sum
-}
-
 func TestPointKindStrings(t *testing.T) {
 	seen := map[string]bool{}
 	for k := PointKind(0); k < NumPointKinds; k++ {

server/internal/game/state.go

@@ -198,7 +198,7 @@ type State struct {
 	Over        bool
 	Winner      PlayerID
 	EndReason   EndReason
-	// Standings is the final table, best first. Meaningless while the game is
-	// in play, for the same reason Winner is.
+	// Standings is the final table, best first. Nil while the game is in
+	// play, when it would be meaningless for the same reason Winner is.
 	Standings []Standing
 }