perf: sync protocol and core hardening updates

deploy/migrations/0070_dispatch_outbox_head_readiness.down.sql

@@ -0,0 +1,46 @@
+DROP TRIGGER IF EXISTS dispatch_outbox_update_user_head ON dispatch_outbox;
+
+CREATE OR REPLACE FUNCTION dispatch_outbox_maintain_user_head()
+RETURNS trigger
+LANGUAGE plpgsql
+AS $$
+DECLARE
+    removed_head bigint;
+BEGIN
+    IF TG_OP = 'INSERT' THEN
+        INSERT INTO dispatch_outbox_user_heads (target_user_id, head_id, head_pts)
+        VALUES (NEW.target_user_id, NEW.id, NEW.pts)
+        ON CONFLICT (target_user_id) DO UPDATE
+        SET head_id = EXCLUDED.head_id,
+            head_pts = EXCLUDED.head_pts
+        WHERE (EXCLUDED.head_pts, EXCLUDED.head_id) <
+              (dispatch_outbox_user_heads.head_pts, dispatch_outbox_user_heads.head_id);
+        RETURN NULL;
+    END IF;
+
+    DELETE FROM dispatch_outbox_user_heads
+    WHERE target_user_id = OLD.target_user_id
+      AND head_id = OLD.id
+    RETURNING head_id INTO removed_head;
+
+    IF removed_head IS NOT NULL THEN
+        INSERT INTO dispatch_outbox_user_heads (target_user_id, head_id, head_pts)
+        SELECT target_user_id, id, pts
+        FROM dispatch_outbox
+        WHERE target_user_id = OLD.target_user_id
+        ORDER BY pts ASC, id ASC
+        LIMIT 1
+        ON CONFLICT (target_user_id) DO UPDATE
+        SET head_id = EXCLUDED.head_id,
+            head_pts = EXCLUDED.head_pts
+        WHERE (EXCLUDED.head_pts, EXCLUDED.head_id) <
+              (dispatch_outbox_user_heads.head_pts, dispatch_outbox_user_heads.head_id);
+    END IF;
+    RETURN NULL;
+END;
+$$;
+
+ALTER TABLE dispatch_outbox_user_heads
+    DROP COLUMN updated_at,
+    DROP COLUMN next_attempt_at,
+    DROP COLUMN status;