Merge solo sealed answers that unlock on pairing into staging

apps/api/drizzle/0021_solo_sealed_answers.sql

@@ -0,0 +1,25 @@
+-- Unpaired users previously hit a waiting room with no way to answer questions,
+-- because responses.couple_id was NOT NULL. This migration relaxes that column so
+-- a solo user can bank "sealed" answers before they have a couple. The foreign key
+-- and ON DELETE CASCADE are unchanged for non-null values: once a couple is deleted,
+-- the responses that belonged to it are still removed with it. Sealed answers keep
+-- couple_id NULL until claimed by the application at pairing time, so couple deletion
+-- has no effect on them; they are not tied to any couple's lifecycle until claimed.
+ALTER TABLE "responses" ALTER COLUMN "couple_id" DROP NOT NULL;
+--> statement-breakpoint
+-- A sealed answer (couple_id IS NULL) has no couple to digest a match notification
+-- for yet; the partner digest only makes sense once claim-on-pair assigns the
+-- response to a couple, at which point the claim path computes matches directly.
+CREATE OR REPLACE FUNCTION queue_response_digest() RETURNS trigger LANGUAGE plpgsql AS $$
+BEGIN
+  IF current_setting('sauci.suppress_operations',true)='on' THEN RETURN NEW; END IF;
+  IF NEW.couple_id IS NULL THEN RETURN NEW; END IF;
+  INSERT INTO pending_match_notifications(couple_id, active_user_id, notify_at)
+  VALUES(NEW.couple_id, NEW.user_id, now() + interval '5 minutes')
+  ON CONFLICT(couple_id) DO UPDATE SET
+    active_user_id=excluded.active_user_id,
+    response_count=pending_match_notifications.response_count+1,
+    notify_at=excluded.notify_at,
+    updated_at=now();
+  RETURN NEW;
+END $$;

apps/api/drizzle/meta/_journal.json

@@ -148,6 +148,13 @@
       "when": 1788168060000,
       "tag": "0020_quiz_question_pool",
       "breakpoints": true
+    },
+    {
+      "idx": 21,
+      "version": "7",
+      "when": 1788168120000,
+      "tag": "0021_solo_sealed_answers",
+      "breakpoints": true
     }
   ]
 }