fix(plugin): batch achievement notifications to prevent text wall

packages/claude-code-plugin/hooks/lib/achievement_tracker.py

@@ -73,22 +73,27 @@
     "en": {
         "unlocked": "Achievement Unlocked!",
         "congrats": "Congratulations!",
+        "more_unlocked": "+{n} more achievements unlocked!",
     },
     "ko": {
         "unlocked": "업적 달성!",
         "congrats": "축하합니다!",
+        "more_unlocked": "+{n}개의 업적을 추가 달성!",
     },
     "ja": {
         "unlocked": "実績解除!",
         "congrats": "おめでとうございます!",
+        "more_unlocked": "+{n}件の実績を解除!",
     },
     "zh": {
         "unlocked": "成就解锁!",
         "congrats": "恭喜!",
+        "more_unlocked": "+{n}个成就已解锁!",
     },
     "es": {
         "unlocked": "Logro desbloqueado!",
         "congrats": "Felicitaciones!",
+        "more_unlocked": "+{n} logros más desbloqueados!",
     },
 }
 
@@ -383,6 +388,37 @@ def render_achievement_celebration(
     return "\n".join(lines)
 
 
+def render_batch_celebration(
+    newly_unlocked: List[Dict[str, Any]],
+    language: str = "en",
+) -> str:
+    """Render a batch celebration for one or more newly unlocked achievements.
+
+    When a single achievement is unlocked, delegates to render_achievement_celebration.
+    When multiple are unlocked, shows the first in detail and summarises the rest.
+
+    Args:
+        newly_unlocked: List of achievement definition dicts just unlocked.
+        language: Language code.
+
+    Returns:
+        Formatted celebration string, or empty string if list is empty.
+    """
+    if not newly_unlocked:
+        return ""
+
+    if len(newly_unlocked) == 1:
+        return render_achievement_celebration(newly_unlocked[0], language)
+
+    # Multiple: show first achievement in detail, summarise the rest
+    top = newly_unlocked[0]
+    detail = render_achievement_celebration(top, language)
+    msgs = CELEBRATION_MESSAGES.get(language, CELEBRATION_MESSAGES["en"])
+    remaining = len(newly_unlocked) - 1
+    summary_line = f"  {msgs['more_unlocked'].format(n=remaining)}"
+    return f"{detail}\n{summary_line}"
+
+
 def render_achievement_badges(
     unlocked: List[Dict[str, Any]],
     language: str = "en",

packages/claude-code-plugin/hooks/stop.py

@@ -131,7 +131,7 @@ def handle_stop(data: dict):
         try:
             from achievement_tracker import (
                 AchievementTracker,
-                render_achievement_celebration,
+                render_batch_celebration,
                 render_achievement_badges,
             )
 
@@ -145,10 +145,10 @@ def handle_stop(data: dict):
 
             newly_unlocked = tracker.check_achievements()
             if newly_unlocked:
-                for achievement in newly_unlocked:
-                    celebration = render_achievement_celebration(
-                        achievement, language
-                    )
+                celebration = render_batch_celebration(
+                    newly_unlocked, language
+                )
+                if celebration:
                     print(celebration, file=sys.stderr)
 
             # Show badge summary if any unlocked

packages/claude-code-plugin/hooks/tests/test_achievement_tracker.py

@@ -20,6 +20,7 @@
     get_achievement_definitions,
     render_achievement_badges,
     render_achievement_celebration,
+    render_batch_celebration,
 )
 
 
@@ -350,3 +351,54 @@ def test_render_unknown_id(self):
         unlocked = [{"id": "unknown_xyz", "name": "Mystery"}]
         result = render_achievement_badges(unlocked, "en")
         assert "Mystery" in result
+
+
+class TestRenderBatchCelebration:
+    """Test batch celebration rendering (#1042)."""
+
+    def test_empty_list(self):
+        result = render_batch_celebration([], "en")
+        assert result == ""
+
+    def test_single_achievement(self):
+        defn = get_achievement_by_id("tdd_champion")
+        result = render_batch_celebration([defn], "en")
+        expected = render_achievement_celebration(defn, "en")
+        assert result == expected
+
+    def test_three_achievements(self):
+        ids = ["tdd_champion", "agent_master", "streak"]
+        achievements = []
+        for aid in ids:
+            defn = get_achievement_by_id(aid)
+            if defn:
+                achievements.append(defn)
+        # Pad with fallback dicts if not enough real definitions
+        while len(achievements) < 3:
+            achievements.append({"name": f"Test{len(achievements)}", "icon": "\U0001f3c6"})
+
+        result = render_batch_celebration(achievements, "en")
+        # First achievement should be detailed
+        assert achievements[0]["name"] in result
+        assert "Achievement Unlocked!" in result
+        # Summary line for remaining
+        assert "+2 more achievements unlocked!" in result
+
+    def test_three_achievements_korean(self):
+        achievements = [
+            {"name": "First", "icon": "\U0001f3c6", "face": "\u2605\u203f\u2605"},
+            {"name": "Second", "icon": "\U0001f3c6"},
+            {"name": "Third", "icon": "\U0001f3c6"},
+        ]
+        result = render_batch_celebration(achievements, "ko")
+        assert "업적 달성!" in result
+        assert "+2개의 업적을 추가 달성!" in result
+
+    def test_two_achievements(self):
+        achievements = [
+            {"name": "Alpha", "icon": "\U0001f3c6", "face": "\u2605\u203f\u2605"},
+            {"name": "Beta", "icon": "\U0001f3c6"},
+        ]
+        result = render_batch_celebration(achievements, "en")
+        assert "Alpha" in result
+        assert "+1 more achievements unlocked!" in result