feat(moment): 動態打分改用專用模型（fallback 短內容，零停機）

.env.example

@@ -105,6 +105,7 @@ MATTERS_PASSPHRASES_SECRET=
 MATTERS_SPAM_DETECTION_API_URL=
 MATTERS_SHORT_CONTENT_SPAM_DETECTION_API_URL=
 MATTERS_COMMENT_SPAM_DETECTION_API_URL=
+MATTERS_MOMENT_SPAM_DETECTION_API_URL=
 MATTERS_COMMENT_SPAM_AUTO_COLLAPSE=false
 MATTERS_AWS_SPAM_SAMPLE_QUEUE_URL=
 MATTERS_SPAM_SAMPLE_HASH_SALT=

src/common/environment.ts

@@ -197,6 +197,11 @@ export const environment = {
     process.env.MATTERS_SHORT_CONTENT_SPAM_DETECTION_API_URL || '',
   commentSpamDetectionApiUrl:
     process.env.MATTERS_COMMENT_SPAM_DETECTION_API_URL || '',
+  // Dedicated moment spam model (label-fix retrain; fixes the shared short-content
+  // model's ~90% false-kill on Chinese moments). Falls back to the short-content
+  // model when unset, so this is a zero-downtime opt-in via env.
+  momentSpamDetectionApiUrl:
+    process.env.MATTERS_MOMENT_SPAM_DETECTION_API_URL || '',
   // When true, a comment whose spam score reaches the system spam threshold is
   // auto-collapsed (folded but still expandable in-thread — "不刪除，只是不再被
   // 看見"). Default off so scoring stays observe-only until ops opts in.

src/connectors/momentService.ts

@@ -461,8 +461,11 @@ export class MomentService {
     id: string
     content: string
   }) => {
+    // Prefer the dedicated moment model; fall back to the shared short-content
+    // model when MATTERS_MOMENT_SPAM_DETECTION_API_URL is unset (zero-downtime).
     const detector = new SpamDetector(
-      environment.shortContentSpamDetectionApiUrl
+      environment.momentSpamDetectionApiUrl ||
+        environment.shortContentSpamDetectionApiUrl
     )
     const score = await detector.detect(content)