fix: prevent duplicate outreach and follow-ups

src/database/client.ts

@@ -217,6 +217,40 @@ export function runMigrations(db: Database.Database): void {
         );
       `);
     },
+    () => db.exec(`
+      CREATE INDEX IF NOT EXISTS idx_reddit_conversations_global_username
+        ON reddit_conversations(username COLLATE NOCASE);
+      CREATE INDEX IF NOT EXISTS idx_sent_messages_global_recipient
+        ON sent_messages(recipient COLLATE NOCASE);
+
+      INSERT OR IGNORE INTO recipient_suppressions (recipient, reason, created_at)
+      SELECT recipient, 'sent-message-history', MIN(sent_at)
+      FROM sent_messages
+      WHERE trim(recipient) <> ''
+      GROUP BY recipient COLLATE NOCASE;
+
+      INSERT OR IGNORE INTO recipient_suppressions (recipient, reason, created_at)
+      SELECT rc.username, 'historical-conversation', MIN(rc.updated_at)
+      FROM reddit_conversations rc
+      WHERE trim(rc.username) <> ''
+        AND lower(trim(rc.username)) NOT IN ('unknown', '[deleted]')
+        AND lower(trim(rc.username)) NOT LIKE 't2\\_%' ESCAPE '\\'
+        AND trim(rc.username) NOT LIKE '@%'
+      GROUP BY rc.username COLLATE NOCASE;
+
+      CREATE TABLE conversation_automation_claims (
+        account_id TEXT NOT NULL,
+        conversation_id TEXT NOT NULL,
+        incoming_key TEXT NOT NULL,
+        status TEXT NOT NULL CHECK(status IN ('pending', 'sent')),
+        claimed_at INTEGER NOT NULL,
+        sent_at INTEGER,
+        PRIMARY KEY (account_id, conversation_id, incoming_key),
+        FOREIGN KEY (account_id) REFERENCES reddit_accounts(account_id) ON DELETE CASCADE
+      );
+      CREATE INDEX idx_conversation_automation_claims_status
+        ON conversation_automation_claims(account_id, status, claimed_at);
+    `),
   ];
 
   let currentVersion = db.pragma('user_version', { simple: true }) as number;