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;

src/database/repositories.ts

@@ -120,9 +120,12 @@ export interface DeliveryOutboxRecord {
   sentMessageId: number | null;
 }
 
-/** Read-only recipient history shared by every Reddit account runtime. */
+/** Global recipient history and durable pre-send claims shared by all account runtimes. */
 export class RecipientHistoryRepository {
   private readonly hasSentToStmt: Database.Statement;
+  private readonly tryClaimStmt: Database.Statement;
+  private readonly commitClaimStmt: Database.Statement;
+  private readonly releaseClaimStmt: Database.Statement;
 
   constructor(db: Database.Database) {
     this.hasSentToStmt = db.prepare(`
@@ -130,13 +133,49 @@ export class RecipientHistoryRepository {
         SELECT recipient FROM sent_messages WHERE recipient = ? COLLATE NOCASE
         UNION ALL
         SELECT recipient FROM recipient_suppressions WHERE recipient = ? COLLATE NOCASE
+        UNION ALL
+        SELECT username AS recipient
+        FROM reddit_conversations
+        WHERE username = ? COLLATE NOCASE
       )
       LIMIT 1
     `);
+    this.tryClaimStmt = db.prepare(`
+      INSERT INTO recipient_suppressions (recipient, reason, created_at)
+      SELECT ?, 'pending-send', ?
+      WHERE NOT EXISTS (
+        SELECT 1 FROM sent_messages WHERE recipient = ? COLLATE NOCASE
+      )
+        AND NOT EXISTS (
+          SELECT 1 FROM reddit_conversations
+          WHERE username = ? COLLATE NOCASE
+        )
+      ON CONFLICT(recipient) DO NOTHING
+    `);
+    this.commitClaimStmt = db.prepare(`
+      UPDATE recipient_suppressions SET reason = 'sent'
+      WHERE recipient = ? COLLATE NOCASE AND reason = 'pending-send'
+    `);
+    this.releaseClaimStmt = db.prepare(`
+      DELETE FROM recipient_suppressions
+      WHERE recipient = ? COLLATE NOCASE AND reason = 'pending-send'
+    `);
   }
 
   hasSentTo(recipient: string): boolean {
-    return this.hasSentToStmt.get(recipient, recipient) !== undefined;
+    return this.hasSentToStmt.get(recipient, recipient, recipient) !== undefined;
+  }
+
+  tryClaim(recipient: string, now: number = Date.now()): boolean {
+    return this.tryClaimStmt.run(recipient, now, recipient, recipient).changes === 1;
+  }
+
+  commitClaim(recipient: string): void {
+    this.commitClaimStmt.run(recipient);
+  }
+
+  releaseClaim(recipient: string): void {
+    this.releaseClaimStmt.run(recipient);
   }
 }
 
@@ -1022,6 +1061,31 @@ export class ConversationStateRepository {
   }
 }
 
+/** Durable idempotency claims for AI replies to individual inbound events. */
+export class ConversationAutomationClaimRepository {
+  constructor(
+    private readonly db: Database.Database,
+    private readonly accountId: string = LEGACY_UNASSIGNED_ACCOUNT_ID,
+  ) {}
+
+  tryClaim(conversationId: string, incomingKey: string, now: number = Date.now()): boolean {
+    return this.db.prepare(`
+      INSERT INTO conversation_automation_claims (
+        account_id, conversation_id, incoming_key, status, claimed_at
+      ) VALUES (?, ?, ?, 'pending', ?)
+      ON CONFLICT(account_id, conversation_id, incoming_key) DO NOTHING
+    `).run(this.accountId, conversationId, incomingKey, now).changes === 1;
+  }
+
+  markSent(conversationId: string, incomingKey: string, now: number = Date.now()): boolean {
+    return this.db.prepare(`
+      UPDATE conversation_automation_claims
+      SET status = 'sent', sent_at = ?
+      WHERE account_id = ? AND conversation_id = ? AND incoming_key = ? AND status = 'pending'
+    `).run(now, this.accountId, conversationId, incomingKey).changes === 1;
+  }
+}
+
 /** Outcome labels are recorded independently from a raw inbox response. */
 export class ConversationOutcomesRepository {
   constructor(