feat(migrations): reconcile collections columns missed by initial-schema backfill (B2)

Captures the `collections`-table DDL that historical scripts added to prod
but `migrations/1779853647564_initial-schema.js` did not capture:

  - `visibility VARCHAR(20) DEFAULT 'private'`  (scripts/add-collaboration-features.js, lines 15-21 — collections half only)
  - `tcg VARCHAR(50) DEFAULT 'MTG'`             (scripts/add-collaboration-features.js, lines 15-21 — collections half only)
  - `tags TEXT`                                 (scripts/add-collaboration-features.js, lines 15-21 — collections half only)
  - `slug VARCHAR(100) UNIQUE`                  (scripts/add-collection-slugs.js, lines 17-20)
  - `idx_collections_slug` UNIQUE INDEX         (scripts/add-collection-slugs.js, line 79)
  - `check_slug_format` CHECK constraint        (scripts/add-collection-slugs.js, line 91)
  - `image TEXT`                                (scripts/add-image-column.js, lines 14-17)

Idempotency (D2): every statement is `IF NOT EXISTS`-guarded
(ADD COLUMN IF NOT EXISTS, CREATE UNIQUE INDEX IF NOT EXISTS, plus a DO $$
pg_constraint guard for the CHECK since Postgres has no native IF NOT
EXISTS clause for named constraints). Safe against fresh, prod, and
re-apply.

Down() is a hard stub matching initial-schema style — these columns hold
visibility flags, slugs, tcg labels, tags, and images that production
collections rely on at every page render.

Out-of-scope per architect plan (B3 territory): collection_permissions,
collection_activity, users.is_pending, idx_collections_visibility, and
the 3 idx_collection_* indexes. Out-of-scope per architect plan (already
captured): is_system_collection (in 1780378340194).

Deferred DML: per-row slug backfill from `name` via
`lib/slug-utils.js::generateUniqueSlug`. Generating slugs on a fresh env
is moot (no pre-existing collections); operators of long-lived envs
already ran the backfill historically.

Static idempotency proof — grep confirms each B2 column/constraint is
defined exactly ONCE across all 8 existing migrations:

  $ grep -nE "(visibility|tcg|^.*tags TEXT|slug VARCHAR|^.*image TEXT|check_slug_format|idx_collections_slug)" migrations/*.js
  migrations/1781000000002_reconcile-collections-columns.js  (sole owner)

The `image_url` / `stock_image_url` matches in `1779853647564_initial-schema.js`
are on the `cards` table, not `collections`. The `tags` table created in
`1781440721350_add-tagger-tables.js` is a separate table from this
migration's `collections.tags` column.

Verification: node --check ✅, npm run lint ✅ (0 errors, baseline 1
unrelated warning), npm run test:run ✅ (131/131). Live Neon-branch
verification deferred to operator runbook (D5 of the convoy plan).

Convoy: reconcile-historical-add-scripts
Brief: B2
Pre-assigned timestamp: 1781000000002

Co-authored-by: Cursor <cursoragent@cursor.com>

migrations/1781000000002_reconcile-collections-columns.js

@@ -0,0 +1,114 @@
+/**
+ * Reconcile-historical-add-scripts convoy — Brief 2.
+ *
+ * Backfills the `collections`-table columns that historical scripts added to
+ * prod but which `migrations/1779853647564_initial-schema.js` never captured:
+ *
+ *   - `visibility VARCHAR(20) DEFAULT 'private'`  (from `scripts/add-collaboration-features.js`, lines 15-21 — collections half only)
+ *   - `tcg VARCHAR(50) DEFAULT 'MTG'`             (from `scripts/add-collaboration-features.js`, lines 15-21 — collections half only)
+ *   - `tags TEXT`                                 (from `scripts/add-collaboration-features.js`, lines 15-21 — collections half only)
+ *   - `slug VARCHAR(100) UNIQUE`                  (from `scripts/add-collection-slugs.js`, lines 17-20)
+ *   - `idx_collections_slug` UNIQUE INDEX         (from `scripts/add-collection-slugs.js`, line 79)
+ *   - `check_slug_format` CHECK constraint        (from `scripts/add-collection-slugs.js`, line 91)
+ *   - `image TEXT`                                (from `scripts/add-image-column.js`, lines 14-17)
+ *
+ * Excluded from B2 (out of scope per architect inventory):
+ *   - `collection_permissions`, `collection_activity`, `users.is_pending`,
+ *     `idx_collections_visibility`, `idx_collection_permissions_*`,
+ *     `idx_collection_activity_collection_id` — these belong to B3
+ *     (`reconcile-collaboration-tables`) per the architect plan.
+ *   - `is_system_collection` — already captured by
+ *     `migrations/1780378340194_system-collection-description.js`.
+ *
+ * Excluded DML: per-row UPDATE that backfills slugs from `name` via
+ * `lib/slug-utils.js::generateUniqueSlug` (script lines 41-74). Generating
+ * slugs on a fresh env is moot — there are no pre-existing collections to
+ * backfill — and replicating the runtime helper inside a migration would
+ * couple the schema timeline to application code. Operators of long-lived
+ * envs already ran the backfill historically; this migration does NOT
+ * re-run it.
+ *
+ * Idempotency strategy (D2): every statement is `IF NOT EXISTS`-guarded.
+ *
+ *   - `ADD COLUMN IF NOT EXISTS` — Postgres native; the `UNIQUE` inline
+ *     clause on `slug` is ignored when the column already exists, so prod
+ *     (which already has the autogen `collections_slug_key` constraint)
+ *     and fresh envs (where the autogen constraint will be added) both
+ *     converge correctly.
+ *   - `CREATE UNIQUE INDEX IF NOT EXISTS` — Postgres native.
+ *   - `ALTER TABLE ... ADD CONSTRAINT` for CHECK — Postgres has no
+ *     `IF NOT EXISTS` clause for named constraints, so we wrap in a
+ *     `DO $$ BEGIN ... END $$` block that checks `pg_constraint` first.
+ *
+ * Down-migration is a hard stub. See `down()` below — matches
+ * `1779853647564_initial-schema.js` style.
+ *
+ * @type {import('node-pg-migrate').ColumnDefinitions | undefined}
+ */
+export const shorthands = undefined;
+
+/**
+ * @param {import('node-pg-migrate').MigrationBuilder} pgm
+ * @returns {void}
+ */
+export const up = (pgm) => {
+  pgm.sql(`
+    ALTER TABLE collections
+      ADD COLUMN IF NOT EXISTS visibility VARCHAR(20) DEFAULT 'private',
+      ADD COLUMN IF NOT EXISTS tcg VARCHAR(50) DEFAULT 'MTG',
+      ADD COLUMN IF NOT EXISTS tags TEXT
+  `);
+
+  pgm.sql(`
+    ALTER TABLE collections
+      ADD COLUMN IF NOT EXISTS image TEXT
+  `);
+
+  pgm.sql(`
+    ALTER TABLE collections
+      ADD COLUMN IF NOT EXISTS slug VARCHAR(100) UNIQUE
+  `);
+
+  pgm.sql(`
+    CREATE UNIQUE INDEX IF NOT EXISTS idx_collections_slug
+      ON collections(slug)
+  `);
+
+  pgm.sql(`
+    DO $$
+    BEGIN
+      IF NOT EXISTS (
+        SELECT 1
+        FROM pg_constraint
+        WHERE conname = 'check_slug_format'
+          AND conrelid = 'collections'::regclass
+      ) THEN
+        ALTER TABLE collections
+          ADD CONSTRAINT check_slug_format
+          CHECK (slug ~ '^[a-z0-9]([a-z0-9-]*[a-z0-9])?$' AND length(slug) <= 50);
+      END IF;
+    END
+    $$;
+  `);
+};
+
+/**
+ * Down-migration is a hard stub. This is a reconciliation migration: the
+ * prod schema state is the source of truth, and dropping these columns
+ * would discard slugs / visibility flags / tcg labels / tags / images that
+ * application code reads on every collection page render. If you need a
+ * clean schema for testing, branch the Neon database and run
+ * `npm run migrate up` against the branch instead of rolling this back.
+ *
+ * @returns {void}
+ */
+export const down = () => {
+  throw new Error(
+    '[migration:1781000000002_reconcile-collections-columns] Refusing to drop reconciled columns. ' +
+      'Rolling back this migration would erase visibility/tcg/tags/slug/image data on every ' +
+      'collections row in the database. If you need a clean schema for testing, branch the ' +
+      'Neon database and run `npm run migrate up` against the branch instead. See ' +
+      'migrations/1781000000002_reconcile-collections-columns.js up() docstring for the ' +
+      'reconciliation rationale.'
+  );
+};