Add a persistent event log for shop and prep actions.

internal/game/log.go

@@ -0,0 +1,55 @@
+package game
+
+import (
+	"fmt"
+	"strings"
+)
+
+// LogEntry is one human-readable line in the game's running event log. The
+// log is public — both players see the same entries across every phase — and
+// explains not just what happened but why (e.g. which pet granted an apple).
+type LogEntry struct {
+	Seq    int    `json:"seq"`   // stable, monotonically increasing id
+	Round  int    `json:"round"` // round the entry belongs to
+	Phase  Phase  `json:"phase"`
+	Seat   int    `json:"seat"`             // acting seat, or -1 when none
+	Icon   string `json:"icon,omitempty"`   // leading emoji
+	Text   string `json:"text"`             // the sentence itself
+	Source string `json:"source,omitempty"` // card id that caused a spawn
+	Spawn  string `json:"spawn,omitempty"`  // "apple" | "bee" for spawn entries
+}
+
+// addLog appends an entry, stamping it with the next sequence number and the
+// current round/phase. Callers set Seat/Icon/Text (and Source/Spawn when the
+// entry represents something spawning off a card).
+func (g *Game) addLog(e LogEntry) {
+	g.LogSeq++
+	e.Seq = g.LogSeq
+	e.Round = g.Round
+	e.Phase = g.Phase
+	g.Log = append(g.Log, e)
+}
+
+// logf is the common case: an entry with just a seat, icon, and message.
+func (g *Game) logf(seat int, icon, format string, args ...any) {
+	g.addLog(LogEntry{Seat: seat, Icon: icon, Text: fmt.Sprintf(format, args...)})
+}
+
+// article returns "a" or "an" to suit the following word.
+func article(word string) string {
+	if word == "" {
+		return "a"
+	}
+	if strings.ContainsRune("aeiouAEIOU", rune(word[0])) {
+		return "an"
+	}
+	return "a"
+}
+
+// plural returns "s" when n is not 1, for simple "N apple(s)" phrasing.
+func plural(n int) string {
+	if n == 1 {
+		return ""
+	}
+	return "s"
+}