fix(sso): repair SSO login bounce + migrate to @better-auth/oauth-provider (#307)

Resolves #306. SSO sign-in via OIDC (Authentik / Keycloak / etc.) now links the
SSO identity to an existing email/password admin instead of bouncing to /login
with `?error=UNKNOWN`. Account-linking is gated on the operator-supplied
**Domain** field — cross-domain claims from a compromised IdP are refused.

Also bundles the deprecated `oidcProvider` → `@better-auth/oauth-provider`
migration. **Operators using the OAuth-provider feature must rotate registered
client secrets after upgrade** (legacy plaintext → hashed storage; see the
0012 migration notes).

Verified end-to-end on the pr-307 image against a real Authentik instance:
SSO login lands on the dashboard, `accounts` table gets both `credential` and
`authentik` rows for the same user. See PR description for full details.

scripts/validate-migrations.ts

@@ -188,6 +188,108 @@ function verify0011Migration(db: any) {
   assert(parsed.provider === "ntfy", "Expected default notification_config.provider to be 'ntfy'");
 }
 
+function seedPre0012Database(db: any) {
+  // The harness has already run migrations 0000-0011, so the legacy
+  // oidc-provider tables exist. Seed a registered client (with the legacy
+  // comma-separated redirect_urls format) plus the related token/consent rows
+  // to exercise the create/transform/drop paths in 0012.
+  db.run("INSERT INTO users (id, email, username, name) VALUES ('u1', 'u1@example.com', 'user1', 'User One')");
+  db.run("INSERT INTO oauth_applications (id, client_id, client_secret, name, redirect_urls, type, disabled, user_id) VALUES ('app1', 'client-1', 'secret-1', 'Example App', 'https://example.com/callback,https://example.com/cb2', 'web', false, 'u1')");
+  db.run("INSERT INTO oauth_access_tokens (id, access_token, refresh_token, access_token_expires_at, refresh_token_expires_at, client_id, user_id, scopes) VALUES ('oat1', 'tok', 'rtok', 7000, 8000, 'client-1', 'u1', '[\"repo\"]')");
+  db.run("INSERT INTO oauth_consent (id, user_id, client_id, scopes, consent_given) VALUES ('cons1', 'u1', 'client-1', '[\"repo\"]', true)");
+}
+
+function verify0012Migration(db: any) {
+  // Old provider tables are dropped.
+  for (const table of ["oauth_applications", "oauth_consent"]) {
+    const row = db
+      .query("SELECT name FROM sqlite_master WHERE type='table' AND name = ?")
+      .get(table) as { name: string } | null;
+    assert(!row, `Expected ${table} table to be dropped after migration`);
+  }
+
+  // New provider tables exist.
+  for (const table of ["oauth_clients", "oauth_access_tokens", "oauth_refresh_tokens", "oauth_consents", "jwks"]) {
+    const row = db
+      .query("SELECT name FROM sqlite_master WHERE type='table' AND name = ?")
+      .get(table) as { name: string } | null;
+    assert(row, `Expected ${table} table to exist after migration`);
+  }
+
+  // The registered client is preserved and its redirect URIs converted from
+  // the legacy comma-separated string into a JSON string[].
+  const client = db
+    .query("SELECT client_id, client_secret, name, redirect_uris, type, user_id FROM oauth_clients WHERE id = 'app1'")
+    .get() as { client_id: string; client_secret: string; name: string; redirect_uris: string; type: string; user_id: string } | null;
+  assert(client, "Expected migrated oauth_clients row for app1");
+  assert(client.client_id === "client-1", "Expected client_id to be preserved");
+  assert(client.name === "Example App", "Expected client name to be preserved");
+  assert(client.user_id === "u1", "Expected owner user_id to be preserved");
+
+  const uris = JSON.parse(client.redirect_uris);
+  assert(
+    Array.isArray(uris) && uris.length === 2 && uris[0] === "https://example.com/callback" && uris[1] === "https://example.com/cb2",
+    `Expected redirect_uris to be a JSON array of the two callbacks, got ${client.redirect_uris}`,
+  );
+
+  // The reshaped tables accept the new column layout.
+  db.run("INSERT INTO oauth_clients (id, client_id, redirect_uris) VALUES ('app2', 'client-2', '[\"https://example.com/cb\"]')");
+  db.run("INSERT INTO oauth_refresh_tokens (id, token, client_id, user_id, scopes) VALUES ('rt1', 'refresh-1', 'client-2', 'u1', '[\"openid\"]')");
+  db.run("INSERT INTO oauth_access_tokens (id, token, client_id, user_id, scopes) VALUES ('at1', 'access-1', 'client-2', 'u1', '[\"openid\"]')");
+  db.run("INSERT INTO oauth_consents (id, client_id, user_id, scopes) VALUES ('co1', 'client-2', 'u1', '[\"openid\"]')");
+  db.run("INSERT INTO jwks (id, public_key, private_key) VALUES ('jwk1', 'public', 'private')");
+}
+
+function seedPre0013Database(db: any) {
+  // Migrations 0000-0012 have run, so sso_providers lacks samlConfig /
+  // domainVerified and the organizations table still carries the inherited
+  // DEFAULT '' on normalized_name from 0007. Seed both so the table-rebuild
+  // and the column-adds can be verified end-to-end.
+  db.run("INSERT INTO users (id, email, username, name) VALUES ('u-sso', 'sso@example.com', 'sso', 'SSO User')");
+  db.run("INSERT INTO configs (id, user_id, name, is_active, github_config, gitea_config, schedule_config, cleanup_config) VALUES ('cfg-pre13', 'u-sso', 'Default', 1, '{}', '{}', '{}', '{}')");
+  db.run("INSERT INTO sso_providers (id, issuer, domain, oidc_config, user_id, provider_id) VALUES ('sso-pre13', 'https://idp.example.com', 'example.com', '{\"clientId\":\"x\"}', 'u-sso', 'idp-pre13')");
+  db.run("INSERT INTO organizations (id, user_id, config_id, name, avatar_url, normalized_name) VALUES ('org-pre13', 'u-sso', 'cfg-pre13', 'Example', 'https://example.com/a.png', 'example')");
+}
+
+function verify0013Migration(db: any) {
+  // New columns on sso_providers.
+  const ssoCols = db
+    .query("PRAGMA table_info(sso_providers)")
+    .all() as Array<{ name: string; notnull: number; dflt_value: string | null }>;
+  const saml = ssoCols.find((c) => c.name === "saml_config");
+  const domainVerified = ssoCols.find((c) => c.name === "domain_verified");
+  assert(saml, "Expected sso_providers.saml_config column to exist");
+  assert(saml.notnull === 0, "Expected saml_config to be nullable");
+  assert(domainVerified, "Expected sso_providers.domain_verified column to exist");
+  assert(domainVerified.notnull === 1, "Expected domain_verified to be NOT NULL");
+  assert(
+    domainVerified.dflt_value === "true",
+    `Expected domain_verified DEFAULT true, got ${domainVerified.dflt_value}`,
+  );
+
+  // Pre-existing SSO row picked up the default (1 = true) on domain_verified.
+  const ssoRow = db
+    .query("SELECT provider_id, saml_config, domain_verified FROM sso_providers WHERE id = 'sso-pre13'")
+    .get() as { provider_id: string; saml_config: string | null; domain_verified: number } | null;
+  assert(ssoRow, "Expected pre-existing OIDC provider row to survive migration");
+  assert(ssoRow.saml_config === null, `Expected saml_config NULL, got ${ssoRow.saml_config}`);
+  assert(ssoRow.domain_verified === 1, `Expected domain_verified=1, got ${ssoRow.domain_verified}`);
+
+  // Organizations rebuild preserved the seeded row and dropped the inherited
+  // DEFAULT '' on normalized_name (drizzle reconciles to schema.ts).
+  const orgRow = db
+    .query("SELECT id, normalized_name FROM organizations WHERE id = 'org-pre13'")
+    .get() as { id: string; normalized_name: string } | null;
+  assert(orgRow, "Expected pre-existing organization row to survive table rebuild");
+  assert(orgRow.normalized_name === "example", `Expected organization normalized_name preserved, got ${orgRow.normalized_name}`);
+  const orgCols = db
+    .query("PRAGMA table_info(organizations)")
+    .all() as Array<{ name: string; dflt_value: string | null }>;
+  const normName = orgCols.find((c) => c.name === "normalized_name");
+  assert(normName, "Expected organizations.normalized_name column to exist");
+  assert(normName.dflt_value === null, `Expected normalized_name to have no default, got ${normName.dflt_value}`);
+}
+
 const latestUpgradeFixtures: Record<string, UpgradeFixture> = {
   "0009_nervous_tyger_tiger": {
     seed: seedPre0009Database,
@@ -201,6 +303,14 @@ const latestUpgradeFixtures: Record<string, UpgradeFixture> = {
     seed: seedPre0011Database,
     verify: verify0011Migration,
   },
+  "0012_oauth_provider_migration": {
+    seed: seedPre0012Database,
+    verify: verify0012Migration,
+  },
+  "0013_slim_galactus": {
+    seed: seedPre0013Database,
+    verify: verify0013Migration,
+  },
 };
 
 function lintMigrations(selectedMigrations: Migration[]) {