feat: init

migrate/012_im_message_seq.sql

@@ -0,0 +1,13 @@
+ALTER TABLE message ADD COLUMN IF NOT EXISTS seq BIGINT NOT NULL DEFAULT 0;
+
+WITH ranked AS (
+    SELECT id, ROW_NUMBER() OVER (PARTITION BY channel_id ORDER BY created_at ASC, id ASC) AS rn
+    FROM message
+    WHERE seq = 0
+)
+UPDATE message m
+SET seq = ranked.rn
+FROM ranked
+WHERE m.id = ranked.id;
+
+CREATE UNIQUE INDEX IF NOT EXISTS idx_message_channel_seq ON message (channel_id, seq);