feat(learning): 實作 Playbook 信心度調整機制 (ADR-030)

- 新增 _promote_playbook: 高評分提升信心度 +0.1
- 新增 _demote_playbook: 低評分降低信心度 -0.15
- 新增 find_by_source_incident: 按 incident_id 查詢 Playbook
- 新增 adjust_confidence: 信心度調整 + 狀態自動轉換
- 新增 Playbook.failure_rate 屬性

自動狀態轉換:
- ai_confidence >= 0.9 + DRAFT → 自動 APPROVED
- ai_confidence < 0.3 + failure_rate > 50% → 自動 DEPRECATED

測試: 13 案例全部通過

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/api/src/repositories/interfaces.py

@@ -244,6 +244,39 @@ class IPlaybookRepository(Protocol):
         """更新執行統計"""
         ...
 
+    async def find_by_source_incident(
+        self,
+        incident_id: str,
+    ) -> list[Playbook]:
+        """
+        根據來源 Incident ID 找 Playbook
+
+        2026-03-30 Claude Code: Learning Service 信心度調整用
+        尋找 source_incident_ids 包含此 incident_id 的 Playbooks
+        """
+        ...
+
+    async def adjust_confidence(
+        self,
+        playbook_id: str,
+        delta: float,
+        reason: str,
+    ) -> Playbook | None:
+        """
+        調整 Playbook 信心度
+
+        2026-03-30 Claude Code: Learning Service 信心度調整用
+
+        Args:
+            playbook_id: Playbook ID
+            delta: 調整量 (+/- 0.0~1.0)
+            reason: 調整原因 (審計用)
+
+        Returns:
+            更新後的 Playbook，或 None (如果不存在)
+        """
+        ...
+
 
 @runtime_checkable
 class ILearningRepository(Protocol):

apps/api/src/repositories/playbook_repository.py

@@ -393,6 +393,118 @@ class PlaybookRepository:
         except Exception as e:
             logger.warning("playbook_index_update_failed", error=str(e))
 
+    # === Learning Service 信心度調整 (2026-03-30 Claude Code) ===
+
+    async def find_by_source_incident(
+        self,
+        incident_id: str,
+    ) -> list[Playbook]:
+        """
+        根據來源 Incident ID 找 Playbook
+
+        2026-03-30 Claude Code: Learning Service 信心度調整用
+        尋找 source_incident_ids 包含此 incident_id 的 Playbooks
+        """
+        try:
+            redis_client = get_redis()
+
+            # 掃描所有 Playbook keys
+            pattern = f"{PLAYBOOK_KEY_PREFIX}PB-*"
+            results: list[Playbook] = []
+
+            async for key in redis_client.scan_iter(match=pattern, count=100):
+                data = await redis_client.get(key)
+                if data:
+                    playbook = Playbook.from_redis_dict(json.loads(data))
+                    if incident_id in playbook.source_incident_ids:
+                        results.append(playbook)
+
+            return results
+
+        except Exception as e:
+            logger.error(
+                "playbook_find_by_incident_failed",
+                incident_id=incident_id,
+                error=str(e),
+            )
+            return []
+
+    async def adjust_confidence(
+        self,
+        playbook_id: str,
+        delta: float,
+        reason: str,
+    ) -> Playbook | None:
+        """
+        調整 Playbook 信心度
+
+        2026-03-30 Claude Code: Learning Service 信心度調整用
+
+        邏輯:
+        - ai_confidence += delta (clamp 到 0.0~1.0)
+        - 若信心度 >= 0.9 且 status == DRAFT → 自動升級為 APPROVED
+        - 若信心度 < 0.3 且 failure_rate > 50% → 自動降級為 DEPRECATED
+        """
+        try:
+            playbook = await self.get_by_id(playbook_id)
+            if not playbook:
+                return None
+
+            old_confidence = playbook.ai_confidence
+
+            # 調整信心度 (clamp 到 0.0~1.0)
+            playbook.ai_confidence = max(0.0, min(1.0, playbook.ai_confidence + delta))
+
+            # 狀態自動轉換
+            old_status = playbook.status
+
+            # 高信心度自動升級
+            if (
+                playbook.ai_confidence >= 0.9
+                and playbook.status == PlaybookStatus.DRAFT
+            ):
+                playbook.status = PlaybookStatus.APPROVED
+                playbook.approved_by = "auto_learning"
+                playbook.approved_at = now_taipei()
+                note = f"\n[Auto-approved: confidence {playbook.ai_confidence:.2f}]"
+                playbook.notes = (playbook.notes or "") + note
+
+            # 低信心度 + 高失敗率 → 棄用
+            elif (
+                playbook.ai_confidence < 0.3
+                and playbook.total_executions >= 5
+                and playbook.failure_rate > 0.5
+            ):
+                playbook.status = PlaybookStatus.DEPRECATED
+                conf = playbook.ai_confidence
+                fail = playbook.failure_rate
+                note = f"\n[Auto-deprecated: conf={conf:.2f}, fail={fail:.0%}]"
+                playbook.notes = (playbook.notes or "") + note
+
+            # 儲存
+            updated = await self.update(playbook)
+
+            logger.info(
+                "playbook_confidence_adjusted",
+                playbook_id=playbook_id,
+                old_confidence=old_confidence,
+                new_confidence=playbook.ai_confidence,
+                old_status=old_status.value,
+                new_status=playbook.status.value,
+                reason=reason,
+            )
+
+            return updated
+
+        except Exception as e:
+            logger.error(
+                "playbook_confidence_adjust_failed",
+                playbook_id=playbook_id,
+                delta=delta,
+                error=str(e),
+            )
+            return None
+
 
 # =============================================================================
 # Singleton