fix: prevent duplicate outreach and follow-ups

tests/database.test.ts

@@ -107,7 +107,7 @@ describe('Database Client', () => {
         .prepare("SELECT name FROM sqlite_master WHERE type='table' AND name NOT LIKE 'sqlite_%'")
         .all() as { name: string }[];
       // Existing domain/config tables plus account, conversation, sync and media ownership stores.
-      expect(tables.length).toBe(14);
+      expect(tables.length).toBe(15);
     });
 
     it('tracks schema version and migrates a legacy sent_messages table transactionally', () => {
@@ -133,6 +133,38 @@ describe('Database Client', () => {
       });
     });
 
+    it('backfills global recipient suppression from sent messages and known conversations', () => {
+      runMigrations(db);
+      db.prepare(`
+        INSERT INTO reddit_conversations (
+          account_id, conversation_id, username, room_name, payload_json, updated_at
+        ) VALUES (?, 'old-room', 'Old_Contact', 'Old Contact', '{}', 20)
+      `).run('__legacy_unassigned__');
+      db.prepare(`
+        INSERT INTO processed_posts (account_id, id, subreddit, author, title, processed_at)
+        VALUES (?, 'old-post', 'test', 'sent-contact', 'title', 10)
+      `).run('__legacy_unassigned__');
+      db.prepare(`
+        INSERT INTO sent_messages (
+          account_id, post_id, recipient, subject, message, sent_at
+        ) VALUES (?, 'old-post', 'Sent_Contact', 'subject', 'message', 11)
+      `).run('__legacy_unassigned__');
+
+      const latestVersion = db.pragma('user_version', { simple: true }) as number;
+      db.exec(`
+        DELETE FROM recipient_suppressions;
+        DROP TABLE conversation_automation_claims;
+      `);
+      db.pragma(`user_version = ${latestVersion - 1}`);
+      runMigrations(db);
+
+      expect(db.prepare('SELECT recipient, reason FROM recipient_suppressions ORDER BY recipient COLLATE NOCASE').all())
+        .toEqual([
+          { recipient: 'Old_Contact', reason: 'historical-conversation' },
+          { recipient: 'Sent_Contact', reason: 'sent-message-history' },
+        ]);
+    });
+
     it('processed_posts has correct schema', () => {
       runMigrations(db);
       const columns = db.prepare('PRAGMA table_info(processed_posts)').all() as { name: string; notnull: number }[];