diff --git a/internal/database/postgres/migrations/000053_executions_account_fk_restrict_test.go b/internal/database/postgres/migrations/000053_executions_account_fk_restrict_test.go
index bb48a5d61..b0a3ff1ba 100644
--- a/internal/database/postgres/migrations/000053_executions_account_fk_restrict_test.go
+++ b/internal/database/postgres/migrations/000053_executions_account_fk_restrict_test.go
@@ -18,6 +18,7 @@ import (
 // purchase_executions.cloud_account_id FK must be ON DELETE RESTRICT after
 // the migration runs. Issue #606 — silent-orphan regression guard.
 func TestMigration_ExecutionsAccountFKRestrict(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
@@ -99,6 +100,7 @@ func TestMigration_ExecutionsAccountFKRestrict(t *testing.T) {
 // emergency rollback re-introduces the (documented) silent-orphan
 // behavior rather than leaving the database in an indeterminate state.
 func TestMigration_ExecutionsAccountFKRestrict_Rollback(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000057_drop_user_role_to_groups_test.go b/internal/database/postgres/migrations/000057_drop_user_role_to_groups_test.go
index 18ceee325..01827f9b7 100644
--- a/internal/database/postgres/migrations/000057_drop_user_role_to_groups_test.go
+++ b/internal/database/postgres/migrations/000057_drop_user_role_to_groups_test.go
@@ -39,6 +39,7 @@ func queryGroupIDs(t *testing.T, ctx context.Context, pool *pgxpool.Pool, email
 // no user loses access; guarantees no user can be left with zero groups; and
 // removes the role column from both users and sessions.
 func TestMigration_DropUserRoleToGroups(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
@@ -132,6 +133,7 @@ func assertColumnAbsent(t *testing.T, ctx context.Context, pool *pgxpool.Pool, t
 // TestMigration_DropUserRoleToGroups_Down restores the role column and
 // reconstructs role from group membership.
 func TestMigration_DropUserRoleToGroups_Down(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000060_cleanup_universal_plans_test.go b/internal/database/postgres/migrations/000060_cleanup_universal_plans_test.go
index 75cb09e0d..1d936d8a9 100644
--- a/internal/database/postgres/migrations/000060_cleanup_universal_plans_test.go
+++ b/internal/database/postgres/migrations/000060_cleanup_universal_plans_test.go
@@ -33,6 +33,7 @@ import (
 // The down migration is a no-op by design (deleted rows cannot be recovered
 // from SQL alone), so no rollback assertion is made.
 func TestMigration_CleanupUniversalPlans(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000064_relocate_purchaser_group_test.go b/internal/database/postgres/migrations/000064_relocate_purchaser_group_test.go
index 19092d65e..cce44427b 100644
--- a/internal/database/postgres/migrations/000064_relocate_purchaser_group_test.go
+++ b/internal/database/postgres/migrations/000064_relocate_purchaser_group_test.go
@@ -45,10 +45,12 @@ func queryGroupIDsByEmail(t *testing.T, ctx context.Context, pool *pgxpool.Pool,
 // collision with Standard Users (000057), and must backfill all Administrators
 // group members into Purchaser.
 func TestMigration_RelocatePurchaserGroup(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
 	t.Run("Purchaser seeded at new UUID after full migration run", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireMigratedDatabase(ctx, t, migrationsPath)
 		pool := container.DB.Pool()
 
@@ -66,6 +68,7 @@ func TestMigration_RelocatePurchaserGroup(t *testing.T) {
 	})
 
 	t.Run("admin-backfill: Administrators members land in Purchaser", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -98,6 +101,7 @@ func TestMigration_RelocatePurchaserGroup(t *testing.T) {
 	})
 
 	t.Run("idempotent: re-running migrations does not duplicate Purchaser membership", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
diff --git a/internal/database/postgres/migrations/000065_enforce_min_one_admin_test.go b/internal/database/postgres/migrations/000065_enforce_min_one_admin_test.go
index 2cea63e68..43166bdc2 100644
--- a/internal/database/postgres/migrations/000065_enforce_min_one_admin_test.go
+++ b/internal/database/postgres/migrations/000065_enforce_min_one_admin_test.go
@@ -61,6 +61,7 @@ func countActiveAdmins(t *testing.T, ctx context.Context, pool *pgxpool.Pool) in
 // error string and would pass even if the SQL were wrong), this test runs the
 // actual migration SQL against a real PostgreSQL instance.
 func TestMigration_EnforceMinOneAdmin_ConcurrentRace(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
@@ -142,16 +143,19 @@ func TestMigration_EnforceMinOneAdmin_ConcurrentRace(t *testing.T) {
 	}
 
 	t.Run("concurrent deactivation never removes the last admin", func(t *testing.T) {
+		t.Parallel()
 		commits, remaining := runConcurrentRace(t, `UPDATE users SET active = false WHERE id = $1`)
 		assertRaceSafe(t, commits, remaining, "deactivations")
 	})
 
 	t.Run("concurrent deletion never removes the last admin", func(t *testing.T) {
+		t.Parallel()
 		commits, remaining := runConcurrentRace(t, `DELETE FROM users WHERE id = $1`)
 		assertRaceSafe(t, commits, remaining, "deletions")
 	})
 
 	t.Run("concurrent group removal never removes the last admin", func(t *testing.T) {
+		t.Parallel()
 		commits, remaining := runConcurrentRace(t, `UPDATE users SET group_ids = '{}'::uuid[] WHERE id = $1`)
 		assertRaceSafe(t, commits, remaining, "group removals")
 	})
@@ -163,6 +167,7 @@ func TestMigration_EnforceMinOneAdmin_ConcurrentRace(t *testing.T) {
 // removal that leaves another active admin must succeed. This pins the
 // trigger's COUNT/active semantics against the real migration SQL.
 func TestMigration_EnforceMinOneAdmin_BlocksLastAdminRemoval(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
@@ -176,6 +181,7 @@ func TestMigration_EnforceMinOneAdmin_BlocksLastAdminRemoval(t *testing.T) {
 	}
 
 	t.Run("deactivating the sole admin is rejected", func(t *testing.T) {
+		t.Parallel()
 		pool := freshPool(t)
 		id := seedActiveAdmin(t, ctx, pool, "sole-admin@test.example")
 		require.Equal(t, 1, countActiveAdmins(t, ctx, pool))
@@ -189,6 +195,7 @@ func TestMigration_EnforceMinOneAdmin_BlocksLastAdminRemoval(t *testing.T) {
 	})
 
 	t.Run("deleting the sole admin is rejected", func(t *testing.T) {
+		t.Parallel()
 		pool := freshPool(t)
 		id := seedActiveAdmin(t, ctx, pool, "sole-admin-del@test.example")
 		require.Equal(t, 1, countActiveAdmins(t, ctx, pool))
@@ -202,6 +209,7 @@ func TestMigration_EnforceMinOneAdmin_BlocksLastAdminRemoval(t *testing.T) {
 	})
 
 	t.Run("removing one of two admins succeeds", func(t *testing.T) {
+		t.Parallel()
 		pool := freshPool(t)
 		a := seedActiveAdmin(t, ctx, pool, "two-admins-a@test.example")
 		_ = seedActiveAdmin(t, ctx, pool, "two-admins-b@test.example")
diff --git a/internal/database/postgres/migrations/000078_monthly_summary_nested_rollup_test.go b/internal/database/postgres/migrations/000078_monthly_summary_nested_rollup_test.go
index 1fe4bce6a..c39e97dfc 100644
--- a/internal/database/postgres/migrations/000078_monthly_summary_nested_rollup_test.go
+++ b/internal/database/postgres/migrations/000078_monthly_summary_nested_rollup_test.go
@@ -32,6 +32,7 @@ import (
 // shape): provider/service total = AVG(250, 400) = 325. The pre-fix flat AVG
 // returned 650/6 = 108.33.
 func TestAnalyticsNestedRollup_COR02(t *testing.T) {
+	t.Parallel()
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
 	defer cancel()
 
diff --git a/internal/database/postgres/migrations/000086_remove_approve_own_from_standard_users_test.go b/internal/database/postgres/migrations/000086_remove_approve_own_from_standard_users_test.go
index ac24b3b17..ca4dbfb95 100644
--- a/internal/database/postgres/migrations/000086_remove_approve_own_from_standard_users_test.go
+++ b/internal/database/postgres/migrations/000086_remove_approve_own_from_standard_users_test.go
@@ -38,10 +38,12 @@ func standardUsersHasPurchaseVerb(t *testing.T, ctx context.Context, pool *pgxpo
 // virtue of ownership. The removal must be surgical -- the sibling own-scoped
 // verbs (cancel-own, retry-own) seeded alongside it in 000057 must be retained.
 func TestMigration_RemoveApproveOwnFromStandardUsers(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
 	t.Run("approve-own removed, sibling own-verbs retained", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -75,6 +77,7 @@ func TestMigration_RemoveApproveOwnFromStandardUsers(t *testing.T) {
 	})
 
 	t.Run("down migration restores approve-own", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
diff --git a/internal/database/postgres/migrations/000087_purchase_history_marketplace_listing_test.go b/internal/database/postgres/migrations/000087_purchase_history_marketplace_listing_test.go
index 810a42cd6..4c354c4ba 100644
--- a/internal/database/postgres/migrations/000087_purchase_history_marketplace_listing_test.go
+++ b/internal/database/postgres/migrations/000087_purchase_history_marketplace_listing_test.go
@@ -23,6 +23,7 @@ import (
 // 000087 applied) would fail because the columns do not exist; after 000087 the
 // test passes.
 func TestMigration087_MarketplaceColumns(t *testing.T) {
+	t.Parallel()
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
 	defer cancel()
 
diff --git a/internal/database/postgres/migrations/000088_grant_view_config_to_nonadmin_groups_test.go b/internal/database/postgres/migrations/000088_grant_view_config_to_nonadmin_groups_test.go
index 438e39dcb..bb4f5db8d 100644
--- a/internal/database/postgres/migrations/000088_grant_view_config_to_nonadmin_groups_test.go
+++ b/internal/database/postgres/migrations/000088_grant_view_config_to_nonadmin_groups_test.go
@@ -38,10 +38,12 @@ func groupHasPermission(t *testing.T, ctx context.Context, pool *pgxpool.Pool, g
 // 403 for those groups. The grant must be surgical: no other permissions are
 // touched on either group, and the write-gating verb (update:config) is not added.
 func TestMigration_GrantViewConfigToNonAdminGroups(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
 	t.Run("view:config granted to Standard Users and Read-Only Users", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -66,6 +68,7 @@ func TestMigration_GrantViewConfigToNonAdminGroups(t *testing.T) {
 	})
 
 	t.Run("update:config is NOT granted (write gate is unaffected)", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -79,6 +82,7 @@ func TestMigration_GrantViewConfigToNonAdminGroups(t *testing.T) {
 	})
 
 	t.Run("sibling permissions on Standard Users are preserved", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -102,6 +106,7 @@ func TestMigration_GrantViewConfigToNonAdminGroups(t *testing.T) {
 	})
 
 	t.Run("down migration removes view:config from both groups", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -126,6 +131,7 @@ func TestMigration_GrantViewConfigToNonAdminGroups(t *testing.T) {
 	})
 
 	t.Run("idempotent: applying to a group already holding view:config is safe", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
diff --git a/internal/database/postgres/migrations/000089_rename_cancelled_to_canceled_test.go b/internal/database/postgres/migrations/000089_rename_cancelled_to_canceled_test.go
index fc7b8e9bf..9549e591b 100644
--- a/internal/database/postgres/migrations/000089_rename_cancelled_to_canceled_test.go
+++ b/internal/database/postgres/migrations/000089_rename_cancelled_to_canceled_test.go
@@ -47,6 +47,7 @@ const (
 //
 //nolint:misspell // test body deliberately exercises the legacy British DB spelling under test -- see migration 000089
 func TestMigration_000089_RollbackWithCanceledRows(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
@@ -164,6 +165,7 @@ func TestMigration_000089_RollbackWithCanceledRows(t *testing.T) {
 //
 //nolint:misspell // test body deliberately exercises the legacy British DB spelling under test -- see migration 000089
 func TestMigration_000089_UpIsAdditiveAndDualCompatible(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000093_recommendations_state_owner_id_test.go b/internal/database/postgres/migrations/000093_recommendations_state_owner_id_test.go
index 38384d9ca..8b1909137 100644
--- a/internal/database/postgres/migrations/000093_recommendations_state_owner_id_test.go
+++ b/internal/database/postgres/migrations/000093_recommendations_state_owner_id_test.go
@@ -18,6 +18,7 @@ import (
 // column (issue #261's compare-and-clear guard), and the down migration
 // removes it cleanly.
 func TestMigration_RecommendationsStateOwnerID(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000095_purchase_history_account_id_width_test.go b/internal/database/postgres/migrations/000095_purchase_history_account_id_width_test.go
index 86739355f..379961389 100644
--- a/internal/database/postgres/migrations/000095_purchase_history_account_id_width_test.go
+++ b/internal/database/postgres/migrations/000095_purchase_history_account_id_width_test.go
@@ -106,6 +106,7 @@ func accountIDMaxLength(ctx context.Context, t *testing.T, pool *pgxpool.Pool) i
 // 22001, which is precisely how the audit row for an already-billed commitment
 // is lost. After 000095 both succeed and round-trip untruncated.
 func TestMigration095_PurchaseHistoryAccountIDWidth(t *testing.T) {
+	t.Parallel()
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
 	defer cancel()
 
@@ -194,6 +195,7 @@ func TestMigration095_PurchaseHistoryAccountIDWidth(t *testing.T) {
 // must actually happen. Without this the ALTER branch after the guard is never
 // executed by any test and a typo in it would ship green.
 func TestMigration095_DownNarrowsWhenSafe(t *testing.T) {
+	t.Parallel()
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
 	defer cancel()
 
@@ -229,6 +231,7 @@ func TestMigration095_DownNarrowsWhenSafe(t *testing.T) {
 // VARCHAR(20) with an Azure subscription GUID present would destroy the audit
 // trail this table exists to provide, so the down migration must refuse.
 func TestMigration095_DownRefusesToTruncate(t *testing.T) {
+	t.Parallel()
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
 	defer cancel()
 
diff --git a/internal/database/postgres/migrations/000096_seed_ri_exchanger_group_test.go b/internal/database/postgres/migrations/000096_seed_ri_exchanger_group_test.go
index dd2ac81db..f2c31f0ee 100644
--- a/internal/database/postgres/migrations/000096_seed_ri_exchanger_group_test.go
+++ b/internal/database/postgres/migrations/000096_seed_ri_exchanger_group_test.go
@@ -31,10 +31,12 @@ const riExchangerGroupIDTest = "00000000-0000-5000-8000-000000000008"
 // (#942), by running ON CONFLICT DO NOTHING onto an already-occupied UUID.
 // These assertions exist so that failure is loud.
 func TestMigration_SeedRIExchangerGroup(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
 	t.Run("RI Exchanger seeded, system-managed, granting execute:ri-exchange", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireMigratedDatabase(ctx, t, migrationsPath)
 		pool := container.DB.Pool()
 
@@ -70,6 +72,7 @@ func TestMigration_SeedRIExchangerGroup(t *testing.T) {
 	})
 
 	t.Run("admin-backfill: Administrators members land in RI Exchanger", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -98,6 +101,7 @@ func TestMigration_SeedRIExchangerGroup(t *testing.T) {
 	})
 
 	t.Run("backfill is idempotent and leaves no duplicate entry", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireMigratedDatabase(ctx, t, migrationsPath)
 		pool := container.DB.Pool()
 
diff --git a/internal/database/postgres/migrations/000098_backfill_execution_step_number_test.go b/internal/database/postgres/migrations/000098_backfill_execution_step_number_test.go
index 5d0f41b43..400bbac82 100644
--- a/internal/database/postgres/migrations/000098_backfill_execution_step_number_test.go
+++ b/internal/database/postgres/migrations/000098_backfill_execution_step_number_test.go
@@ -57,6 +57,7 @@ func stepNumberOf(ctx context.Context, t *testing.T, pool *pgxpool.Pool, execID
 // steps) are retargeted at the step they will actually complete, while
 // correctly-stamped rows and terminal rows are left alone.
 func TestMigration_BackfillExecutionStepNumber(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000099_user_deactivated_at_test.go b/internal/database/postgres/migrations/000099_user_deactivated_at_test.go
index 98f3f182d..aa04a9d6c 100644
--- a/internal/database/postgres/migrations/000099_user_deactivated_at_test.go
+++ b/internal/database/postgres/migrations/000099_user_deactivated_at_test.go
@@ -51,6 +51,7 @@ func deactivatedAtOf(ctx context.Context, t *testing.T, pool *pgxpool.Pool, user
 // could self-reactivate via password reset regardless of how it went
 // inactive.
 func TestMigration_UserDeactivatedAtBackfill(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000100_hash_approval_tokens_at_rest_test.go b/internal/database/postgres/migrations/000100_hash_approval_tokens_at_rest_test.go
index 1f357493d..e21e80d7b 100644
--- a/internal/database/postgres/migrations/000100_hash_approval_tokens_at_rest_test.go
+++ b/internal/database/postgres/migrations/000100_hash_approval_tokens_at_rest_test.go
@@ -112,6 +112,7 @@ func runUpSQL(ctx context.Context, t *testing.T, pool *pgxpool.Pool, migrationsP
 // destroying migrated hashes; and the no-op down keeps the hashes so a
 // down-then-up is lossless.
 func TestMigration_HashApprovalTokensAtRest(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
@@ -184,6 +185,7 @@ func TestMigration_HashApprovalTokensAtRest(t *testing.T) {
 // or execution history, pending lists and the scheduler break. A row the new
 // store writes must also stay readable by pre-#103 code.
 func TestMigration_HashApprovalTokensAtRest_StoreReadsTokenlessRows(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000102_purchase_plan_update_token_test.go b/internal/database/postgres/migrations/000102_purchase_plan_update_token_test.go
index 2959b58dc..04c8075fe 100644
--- a/internal/database/postgres/migrations/000102_purchase_plan_update_token_test.go
+++ b/internal/database/postgres/migrations/000102_purchase_plan_update_token_test.go
@@ -13,6 +13,7 @@ import (
 )
 
 func TestMigration_PurchasePlanUpdateToken(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	path := getMigrationsPath()
 	container := testhelpers.RequireMigratedDatabase(ctx, t, path)
diff --git a/internal/database/postgres/migrations/000103_api_key_password_version_test.go b/internal/database/postgres/migrations/000103_api_key_password_version_test.go
index 321688272..8197e48fe 100644
--- a/internal/database/postgres/migrations/000103_api_key_password_version_test.go
+++ b/internal/database/postgres/migrations/000103_api_key_password_version_test.go
@@ -12,6 +12,7 @@ import (
 )
 
 func TestMigration_APIKeyPasswordVersion(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	path := getMigrationsPath()
 	container := testhelpers.RequireMigratedDatabase(ctx, t, path)
diff --git a/internal/database/postgres/migrations/000104_user_mfa_last_totp_counter_test.go b/internal/database/postgres/migrations/000104_user_mfa_last_totp_counter_test.go
index 0383a9392..59c9bb8fc 100644
--- a/internal/database/postgres/migrations/000104_user_mfa_last_totp_counter_test.go
+++ b/internal/database/postgres/migrations/000104_user_mfa_last_totp_counter_test.go
@@ -15,6 +15,7 @@ import (
 // Migration 000104 adds users.mfa_last_totp_counter. Existing rows start at 0
 // (no code accepted yet), and the down migration removes the column.
 func TestMigration_UserMFALastTOTPCounter(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000105_purchase_history_listing_attempt_test.go b/internal/database/postgres/migrations/000105_purchase_history_listing_attempt_test.go
index bb66bcb9e..656523e5b 100644
--- a/internal/database/postgres/migrations/000105_purchase_history_listing_attempt_test.go
+++ b/internal/database/postgres/migrations/000105_purchase_history_listing_attempt_test.go
@@ -17,6 +17,7 @@ import (
 // purchase_history: existing rows have no unresolved attempt, and the down
 // migration removes both columns.
 func TestMigration_PurchaseHistoryListingAttempt(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000106_invalidate_azure_recs_lookback_units_test.go b/internal/database/postgres/migrations/000106_invalidate_azure_recs_lookback_units_test.go
index 43b13c608..e61f50c99 100644
--- a/internal/database/postgres/migrations/000106_invalidate_azure_recs_lookback_units_test.go
+++ b/internal/database/postgres/migrations/000106_invalidate_azure_recs_lookback_units_test.go
@@ -16,6 +16,7 @@ import (
 )
 
 func TestMigration_InvalidateAzureRecsLookbackUnits(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	path := getMigrationsPath()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
diff --git a/internal/database/postgres/migrations/000107_ladder_tranche_amendments_test.go b/internal/database/postgres/migrations/000107_ladder_tranche_amendments_test.go
index c47a927b2..94f1c181a 100644
--- a/internal/database/postgres/migrations/000107_ladder_tranche_amendments_test.go
+++ b/internal/database/postgres/migrations/000107_ladder_tranche_amendments_test.go
@@ -13,6 +13,7 @@ import (
 )
 
 func TestMigration_LadderTrancheAmendments(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	path := getMigrationsPath()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
@@ -87,6 +88,7 @@ func TestMigration_LadderTrancheAmendments(t *testing.T) {
 }
 
 func TestMigration_LadderTrancheAmendmentsRollbackWhenEmpty(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	path := getMigrationsPath()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
diff --git a/internal/database/postgres/migrations/000109_recommendations_availability_zone_test.go b/internal/database/postgres/migrations/000109_recommendations_availability_zone_test.go
index f9b780c3c..b7436524e 100644
--- a/internal/database/postgres/migrations/000109_recommendations_availability_zone_test.go
+++ b/internal/database/postgres/migrations/000109_recommendations_availability_zone_test.go
@@ -26,6 +26,7 @@ const insertRecForMigration109 = `
 // both payload shapes, the 8-column index is kept so the current upsert still
 // works, and rollback removes the column and the new index.
 func TestMigration_RecommendationsAvailabilityZone(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000110_drop_recommendations_8col_natural_key_test.go b/internal/database/postgres/migrations/000110_drop_recommendations_8col_natural_key_test.go
index a0e8ed062..66bfe28b0 100644
--- a/internal/database/postgres/migrations/000110_drop_recommendations_8col_natural_key_test.go
+++ b/internal/database/postgres/migrations/000110_drop_recommendations_8col_natural_key_test.go
@@ -25,6 +25,7 @@ const insertRecForMigration110 = `
 // the 8-column index is gone, the 9-column index still dedupes per AZ, and the
 // rollback recreates the 8-column index after collapsing AZ-only duplicates.
 func TestMigration_DropRecommendations8ColNaturalKey(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000111_recommendations_platform_tenancy_test.go b/internal/database/postgres/migrations/000111_recommendations_platform_tenancy_test.go
index 940660641..acfbf1cf0 100644
--- a/internal/database/postgres/migrations/000111_recommendations_platform_tenancy_test.go
+++ b/internal/database/postgres/migrations/000111_recommendations_platform_tenancy_test.go
@@ -27,6 +27,7 @@ const insertRecForMigration111 = `
 // upsert still works, the 11-column index is added, and rollback removes only
 // the new column pair and index.
 func TestMigration_RecommendationsPlatformTenancy(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000112_plan_step_cap_auto_purchase_switch_test.go b/internal/database/postgres/migrations/000112_plan_step_cap_auto_purchase_switch_test.go
index 9e5706c2e..edb406952 100644
--- a/internal/database/postgres/migrations/000112_plan_step_cap_auto_purchase_switch_test.go
+++ b/internal/database/postgres/migrations/000112_plan_step_cap_auto_purchase_switch_test.go
@@ -19,6 +19,7 @@ import (
 // switch defaults to FALSE, the CHECK rejects a non-positive cap, and the down
 // migration removes both columns.
 func TestMigration_PlanStepCapAndAutoPurchaseSwitch(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000113_purchase_executions_no_submission_test.go b/internal/database/postgres/migrations/000113_purchase_executions_no_submission_test.go
index 4f0a8ac02..88245fa88 100644
--- a/internal/database/postgres/migrations/000113_purchase_executions_no_submission_test.go
+++ b/internal/database/postgres/migrations/000113_purchase_executions_no_submission_test.go
@@ -20,6 +20,7 @@ import (
 // (no proof, fail closed), the up statement is idempotent, and the down
 // migration drops the column.
 func TestMigration_PurchaseExecutionsNoSubmission(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000114_ladder_tranches_status_reason_test.go b/internal/database/postgres/migrations/000114_ladder_tranches_status_reason_test.go
index d3909616c..b74d833ad 100644
--- a/internal/database/postgres/migrations/000114_ladder_tranches_status_reason_test.go
+++ b/internal/database/postgres/migrations/000114_ladder_tranches_status_reason_test.go
@@ -19,6 +19,7 @@ import (
 // PostgreSQL: a pre-existing tranche gets a NULL reason, the up statement is
 // idempotent, and the down migration drops the column.
 func TestMigration_LadderTranchesStatusReason(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000115_auto_purchase_switch_stamps_test.go b/internal/database/postgres/migrations/000115_auto_purchase_switch_stamps_test.go
index e505f769c..7b8ee00ae 100644
--- a/internal/database/postgres/migrations/000115_auto_purchase_switch_stamps_test.go
+++ b/internal/database/postgres/migrations/000115_auto_purchase_switch_stamps_test.go
@@ -20,6 +20,7 @@ import (
 // NULL stamps, the up statement is idempotent, and the down migration drops
 // the three columns.
 func TestMigration_AutoPurchaseSwitchStamps(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000117_ladder_tranches_settled_at_test.go b/internal/database/postgres/migrations/000117_ladder_tranches_settled_at_test.go
index 1987d43a1..49c1cdb3b 100644
--- a/internal/database/postgres/migrations/000117_ladder_tranches_settled_at_test.go
+++ b/internal/database/postgres/migrations/000117_ladder_tranches_settled_at_test.go
@@ -22,6 +22,7 @@ import (
 // row still works (the ON DELETE SET NULL updates re-evaluate the CHECK), and
 // the up statement is idempotent.
 func TestMigration_LadderTranchesSettledAt(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	path := getMigrationsPath()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
diff --git a/internal/database/postgres/migrations/000118_purchase_plans_ramp_baseline_test.go b/internal/database/postgres/migrations/000118_purchase_plans_ramp_baseline_test.go
index 87fae5bd5..b84ef7a53 100644
--- a/internal/database/postgres/migrations/000118_purchase_plans_ramp_baseline_test.go
+++ b/internal/database/postgres/migrations/000118_purchase_plans_ramp_baseline_test.go
@@ -19,6 +19,7 @@ import (
 // PostgreSQL: existing plans get a NULL baseline (no backfill), the up
 // statement is idempotent, and down removes the column.
 func TestMigration_PurchasePlansRampBaseline(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	path := getMigrationsPath()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
diff --git a/internal/database/postgres/migrations/000119_drop_recommendations_9col_natural_key_test.go b/internal/database/postgres/migrations/000119_drop_recommendations_9col_natural_key_test.go
index 3fceb3aab..c10183fcd 100644
--- a/internal/database/postgres/migrations/000119_drop_recommendations_9col_natural_key_test.go
+++ b/internal/database/postgres/migrations/000119_drop_recommendations_9col_natural_key_test.go
@@ -25,6 +25,7 @@ const insertRecForMigration119 = `
 // the 9-column index is gone, the 11-column index still dedupes, and the
 // rollback recreates the 9-column index after collapsing those duplicates.
 func TestMigration_DropRecommendations9ColNaturalKey(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000120_recommendations_source_account_test.go b/internal/database/postgres/migrations/000120_recommendations_source_account_test.go
index e2cd6dbd3..91aa9ca5f 100644
--- a/internal/database/postgres/migrations/000120_recommendations_source_account_test.go
+++ b/internal/database/postgres/migrations/000120_recommendations_source_account_test.go
@@ -16,6 +16,7 @@ import (
 )
 
 func TestMigration_RecommendationsSourceAccount(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
 	pool := container.DB.Pool()
diff --git a/internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance_test.go b/internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance_test.go
index e934aea13..c933c5a34 100644
--- a/internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance_test.go
+++ b/internal/database/postgres/migrations/000121_ladder_tranche_amount_provenance_test.go
@@ -12,6 +12,7 @@ import (
 )
 
 func TestMigration_LadderTrancheAmountProvenance(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
 	pool, path := container.DB.Pool(), getMigrationsPath()
diff --git a/internal/database/postgres/migrations/000123_purchase_execution_fan_out_shapes_test.go b/internal/database/postgres/migrations/000123_purchase_execution_fan_out_shapes_test.go
index 966d315ad..cd69d9770 100644
--- a/internal/database/postgres/migrations/000123_purchase_execution_fan_out_shapes_test.go
+++ b/internal/database/postgres/migrations/000123_purchase_execution_fan_out_shapes_test.go
@@ -21,6 +21,7 @@ import (
 // "multi", a lineage without one is left unpinned, the up statement is
 // idempotent, and the down migration drops the table.
 func TestMigration_PurchaseExecutionFanOutShapes(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000125_lock_default_user_groups_test.go b/internal/database/postgres/migrations/000125_lock_default_user_groups_test.go
index 4e7152bc2..bd4fdd79e 100644
--- a/internal/database/postgres/migrations/000125_lock_default_user_groups_test.go
+++ b/internal/database/postgres/migrations/000125_lock_default_user_groups_test.go
@@ -12,6 +12,7 @@ import (
 )
 
 func TestMigration_LockDefaultUserGroups(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
 	pool, path := container.DB.Pool(), getMigrationsPath()
diff --git a/internal/database/postgres/migrations/000126_purchase_history_active_expiry_idx_test.go b/internal/database/postgres/migrations/000126_purchase_history_active_expiry_idx_test.go
index d5d6e3b68..ab465bc3c 100644
--- a/internal/database/postgres/migrations/000126_purchase_history_active_expiry_idx_test.go
+++ b/internal/database/postgres/migrations/000126_purchase_history_active_expiry_idx_test.go
@@ -16,6 +16,7 @@ import (
 // value still inserts once the index exists, and that the down migration
 // removes it.
 func TestMigration_PurchaseHistoryActiveExpiryIndex(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
 	pool, path := container.DB.Pool(), getMigrationsPath()
diff --git a/internal/database/postgres/migrations/000128_executions_detach_keeps_updated_at_test.go b/internal/database/postgres/migrations/000128_executions_detach_keeps_updated_at_test.go
index 01dbb23f5..e6c3d7730 100644
--- a/internal/database/postgres/migrations/000128_executions_detach_keeps_updated_at_test.go
+++ b/internal/database/postgres/migrations/000128_executions_detach_keeps_updated_at_test.go
@@ -18,6 +18,7 @@ import (
 // account keeps updated_at, every other UPDATE still stamps NOW(), and the
 // down migration restores the stamp-everything trigger (issue #265).
 func TestMigration_ExecutionsDetachKeepsUpdatedAt(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
 	pool, path := container.DB.Pool(), getMigrationsPath()
diff --git a/internal/database/postgres/migrations/000129_recommendations_state_partial_test.go b/internal/database/postgres/migrations/000129_recommendations_state_partial_test.go
index fecb4f5d2..c8e77ae6a 100644
--- a/internal/database/postgres/migrations/000129_recommendations_state_partial_test.go
+++ b/internal/database/postgres/migrations/000129_recommendations_state_partial_test.go
@@ -19,6 +19,7 @@ import (
 // the logs), the seeded singleton row starts out NULL (= complete), and the
 // down migration removes the column cleanly.
 func TestMigration_RecommendationsStatePartial(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000130_purchase_executions_created_by_system_test.go b/internal/database/postgres/migrations/000130_purchase_executions_created_by_system_test.go
index ad8e5f1d5..ca20cbc6e 100644
--- a/internal/database/postgres/migrations/000130_purchase_executions_created_by_system_test.go
+++ b/internal/database/postgres/migrations/000130_purchase_executions_created_by_system_test.go
@@ -13,6 +13,7 @@ import (
 
 // TestMigration_PurchaseExecutionsCreatedBySystem covers 000130 up, down and the CHECK (#233).
 func TestMigration_PurchaseExecutionsCreatedBySystem(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
 	pool, path := container.DB.Pool(), getMigrationsPath()
diff --git a/internal/database/postgres/migrations/000131_ri_exchange_direct_executions_test.go b/internal/database/postgres/migrations/000131_ri_exchange_direct_executions_test.go
index a5c7fe093..f787bdc3e 100644
--- a/internal/database/postgres/migrations/000131_ri_exchange_direct_executions_test.go
+++ b/internal/database/postgres/migrations/000131_ri_exchange_direct_executions_test.go
@@ -21,6 +21,7 @@ import (
 // idempotent, the approval flow's ri_exchange_history is untouched, and the
 // down migration drops the table.
 func TestMigration_RIExchangeDirectExecutions(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/000132_savings_partition_utc_bounds_test.go b/internal/database/postgres/migrations/000132_savings_partition_utc_bounds_test.go
index fbc11fbf7..176e0b628 100644
--- a/internal/database/postgres/migrations/000132_savings_partition_utc_bounds_test.go
+++ b/internal/database/postgres/migrations/000132_savings_partition_utc_bounds_test.go
@@ -114,6 +114,7 @@ func utc(s string) time.Time {
 // created under any session TimeZone span UTC months, and partitions that the
 // old function cut at local midnight are rebuilt with their rows re-routed.
 func TestMigration_SavingsPartitionUTCBounds(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
 	pool, path := container.DB.Pool(), getMigrationsPath()
@@ -206,6 +207,7 @@ func TestMigration_SavingsPartitionUTCBounds(t *testing.T) {
 // not committed, waits and then succeeds instead of failing with "relation
 // already exists".
 func TestMigration_SavingsPartitionConcurrentCreate(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
 	pool := container.DB.Pool()
diff --git a/internal/database/postgres/migrations/000133_purchase_history_reverify_ec2_offering_class_test.go b/internal/database/postgres/migrations/000133_purchase_history_reverify_ec2_offering_class_test.go
index 0e6eadd7a..38f3cbf3a 100644
--- a/internal/database/postgres/migrations/000133_purchase_history_reverify_ec2_offering_class_test.go
+++ b/internal/database/postgres/migrations/000133_purchase_history_reverify_ec2_offering_class_test.go
@@ -49,6 +49,7 @@ func offeringClassOf(ctx context.Context, t *testing.T, pool *pgxpool.Pool, purc
 // Fail-before: with the UPDATE removed from the up file, the cleared rows keep
 // 'convertible' and the NULL assertions fail.
 func TestMigration133_ClearsConvertibleEC2Stamps(t *testing.T) {
+	t.Parallel()
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
 	defer cancel()
 
@@ -100,6 +101,7 @@ func TestMigration133_ClearsConvertibleEC2Stamps(t *testing.T) {
 // commits, the UPDATE re-checks its WHERE clause on the new row version and
 // must leave the authoritative 'standard' in place rather than clearing it.
 func TestMigration133_ConcurrentStandardStampWins(t *testing.T) {
+	t.Parallel()
 	ctx, cancel := context.WithTimeout(context.Background(), 3*time.Minute)
 	defer cancel()
 
diff --git a/internal/database/postgres/migrations/000134_purchase_suppressions_variant_test.go b/internal/database/postgres/migrations/000134_purchase_suppressions_variant_test.go
index 314c48ac4..1eb558d38 100644
--- a/internal/database/postgres/migrations/000134_purchase_suppressions_variant_test.go
+++ b/internal/database/postgres/migrations/000134_purchase_suppressions_variant_test.go
@@ -45,6 +45,7 @@ func requireUniqueViolation134(t *testing.T, err error, constraint string) {
 // execution and 6-tuple), old-code inserts still working, and a down that
 // merges variant rows back into one row per execution and 6-tuple.
 func TestMigration_PurchaseSuppressionsVariant(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	container := testhelpers.RequireEmptyDatabase(ctx, t)
 	pool, path := container.DB.Pool(), getMigrationsPath()
diff --git a/internal/database/postgres/migrations/backfill_admin_group_ids_test.go b/internal/database/postgres/migrations/backfill_admin_group_ids_test.go
index 8408a2015..de86ad42e 100644
--- a/internal/database/postgres/migrations/backfill_admin_group_ids_test.go
+++ b/internal/database/postgres/migrations/backfill_admin_group_ids_test.go
@@ -24,6 +24,7 @@ import (
 // re-run migrations with NO admin email so only the SQL migration can repair
 // the row. A pass therefore proves the migration (not the Go path) did it.
 func TestMigration_BackfillAdminGroupIDs(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 	const adminEmail = "restore-path@test.example"
diff --git a/internal/database/postgres/migrations/ensure_admin_user_test.go b/internal/database/postgres/migrations/ensure_admin_user_test.go
index 19af8105c..fbcbf57b5 100644
--- a/internal/database/postgres/migrations/ensure_admin_user_test.go
+++ b/internal/database/postgres/migrations/ensure_admin_user_test.go
@@ -42,11 +42,13 @@ func queryAdminGroupIDs(t *testing.T, ctx context.Context, pool *pgxpool.Pool, e
 // drift must self-heal on the next boot, and operator-customized
 // group_ids must be preserved.
 func TestEnsureAdminUser_GroupAssignment(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 	const adminEmail = "admin@test.example"
 
 	t.Run("fresh insert no password", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -58,6 +60,7 @@ func TestEnsureAdminUser_GroupAssignment(t *testing.T) {
 	})
 
 	t.Run("fresh insert with password", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -69,6 +72,7 @@ func TestEnsureAdminUser_GroupAssignment(t *testing.T) {
 	})
 
 	t.Run("re-run with existing correct admin (post-057 idempotency)", func(t *testing.T) {
+		t.Parallel()
 		// Migration 000057 added a CHECK constraint (users_min_one_group)
 		// that prevents group_ids from being NULL or empty, so the
 		// pre-057 drift scenario (empty group_ids on an existing admin row)
@@ -97,6 +101,7 @@ func TestEnsureAdminUser_GroupAssignment(t *testing.T) {
 	})
 
 	t.Run("idempotency", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -113,6 +118,7 @@ func TestEnsureAdminUser_GroupAssignment(t *testing.T) {
 	})
 
 	t.Run("operator customisation preserved", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
diff --git a/internal/database/postgres/migrations/helpers_test.go b/internal/database/postgres/migrations/helpers_test.go
index 3f73842fe..ec63b6af2 100644
--- a/internal/database/postgres/migrations/helpers_test.go
+++ b/internal/database/postgres/migrations/helpers_test.go
@@ -69,6 +69,7 @@ func previousMigrationVersion(t *testing.T, version uint) uint {
 
 // captureStdout redirects os.Stdout to a pipe and returns a function that
 // closes the pipe, restores stdout, and returns everything written to it.
+// os.Stdout is process-wide, so a test using it must not call t.Parallel.
 //
 // Mirrors the helper of the same name in migrate_security_test.go; the
 // duplication is forced by the package boundary (that file lives in
@@ -93,7 +94,9 @@ func captureStdout(t *testing.T) func() string {
 }
 
 // captureLogOutput redirects the standard logger to a buffer for the duration
-// of the test, restoring the original flags and writer on cleanup.
+// of the test, restoring the original flags and writer on cleanup. Every
+// RunMigrations call logs through that logger, so a test using it must not
+// call t.Parallel.
 //
 // Mirrors the helper of the same name in migrate_security_test.go for the
 // same package-boundary reason described on captureStdout.
diff --git a/internal/database/postgres/migrations/migrate_autoheal_test.go b/internal/database/postgres/migrations/migrate_autoheal_test.go
index bb4df2e09..35e75f2d9 100644
--- a/internal/database/postgres/migrations/migrate_autoheal_test.go
+++ b/internal/database/postgres/migrations/migrate_autoheal_test.go
@@ -47,6 +47,7 @@ func markDirty(ctx context.Context, t *testing.T, container *testhelpers.Postgre
 // conservative choice is to refuse to auto-clear and let an operator confirm
 // the schema state before forcing.
 func TestMigrations_AutoHealDirty(t *testing.T) {
+	// Not parallel: the subtests t.Setenv CUDLY_MIGRATION_AUTOHEAL, which RunMigrations reads process-wide.
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/migrate_cancel_integration_test.go b/internal/database/postgres/migrations/migrate_cancel_integration_test.go
index c6d9c6da0..6d0dd266b 100644
--- a/internal/database/postgres/migrations/migrate_cancel_integration_test.go
+++ b/internal/database/postgres/migrations/migrate_cancel_integration_test.go
@@ -100,6 +100,7 @@ func requireNoBackend(t *testing.T, pool *pgxpool.Pool, db, prefix string) {
 }
 
 func TestRunMigrations_DeadlineStopsMigrationSQLBlockedByForeignLock(t *testing.T) {
+	// Not parallel: asserts a 1s deadline is honored within fixed wall-clock bounds.
 	pool, db := migrationDB(t)
 	ctx := context.Background()
 	_, err := pool.Exec(ctx, "CREATE TABLE locktarget (id int)")
@@ -137,6 +138,7 @@ func TestRunMigrations_DeadlineStopsMigrationSQLBlockedByForeignLock(t *testing.
 }
 
 func TestRunMigrations_DeadlineStopsAdvisoryLockWait(t *testing.T) {
+	// Not parallel: asserts a 1s deadline is honored within a fixed wall-clock bound.
 	pool, db := migrationDB(t)
 	ctx := context.Background()
 
@@ -160,6 +162,7 @@ func TestRunMigrations_DeadlineStopsAdvisoryLockWait(t *testing.T) {
 }
 
 func TestRunMigrations_CancelStopsSetupBlockedOnVersionTable(t *testing.T) {
+	// Not parallel: asserts a 1s deadline is honored within a fixed wall-clock bound.
 	pool, db := migrationDB(t)
 	ctx := context.Background()
 	_, err := pool.Exec(ctx, "CREATE TABLE schema_migrations (version bigint NOT NULL PRIMARY KEY, dirty boolean NOT NULL)")
@@ -181,6 +184,7 @@ func TestRunMigrations_CancelStopsSetupBlockedOnVersionTable(t *testing.T) {
 }
 
 func TestRunMigrations_CompletesWithinDeadline(t *testing.T) {
+	// Not parallel: asserts the run finishes inside a fixed wall-clock deadline.
 	pool, _ := migrationDB(t)
 	dir := migrationDir(t, "CREATE TABLE widgets (id int);")
 
@@ -198,6 +202,7 @@ func TestRunMigrations_CompletesWithinDeadline(t *testing.T) {
 // is a clean no-op, so the replacement for migrate.New changes nothing for the
 // normal path.
 func TestRunMigrations_AppliesFullSchemaThroughCancelableMigrator(t *testing.T) {
+	t.Parallel()
 	pool, _ := migrationDB(t)
 	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
 	defer cancel()
diff --git a/internal/database/postgres/migrations/migrate_down_all_test.go b/internal/database/postgres/migrations/migrate_down_all_test.go
index c47de6cec..96fece35b 100644
--- a/internal/database/postgres/migrations/migrate_down_all_test.go
+++ b/internal/database/postgres/migrations/migrate_down_all_test.go
@@ -18,6 +18,7 @@ import (
 // its own up against the schema the later migrations left behind; a down that
 // assumes an object a later migration removed leaves the DB dirty (issue #205).
 func TestMigrations_DownAllRoundTrip(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/migrate_idempotency_test.go b/internal/database/postgres/migrations/migrate_idempotency_test.go
index 9aa74e2e8..31ff34b91 100644
--- a/internal/database/postgres/migrations/migrate_idempotency_test.go
+++ b/internal/database/postgres/migrations/migrate_idempotency_test.go
@@ -31,6 +31,7 @@ import (
 // CUDLY_FORCE_MIGRATION_VERSION. Per-migration re-run safety is therefore not
 // an invariant that auto-heal depends on, and is tracked separately.
 func TestMigrations_FullStackIdempotent(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/migrations/migrate_pgpassword_integration_test.go b/internal/database/postgres/migrations/migrate_pgpassword_integration_test.go
index 9318eca1d..57f225973 100644
--- a/internal/database/postgres/migrations/migrate_pgpassword_integration_test.go
+++ b/internal/database/postgres/migrations/migrate_pgpassword_integration_test.go
@@ -44,6 +44,7 @@ func hostilePasswords() map[string]string {
 //
 // A wrong PGPASSWORD must fail, proving the server really checks it.
 func TestPGPasswordAndKeywordDSN_ConnectWithHostilePassword(t *testing.T) {
+	// Not parallel: t.Setenv("PGPASSWORD") changes the process environment.
 	ctx := context.Background()
 	// Dedicated server: ALTER ROLE ... PASSWORD changes the cluster-wide role that
 	// every shared-server test database logs in as.
diff --git a/internal/database/postgres/migrations/migrate_security_integration_test.go b/internal/database/postgres/migrations/migrate_security_integration_test.go
index d1abdf4f9..6e5d632d5 100644
--- a/internal/database/postgres/migrations/migrate_security_integration_test.go
+++ b/internal/database/postgres/migrations/migrate_security_integration_test.go
@@ -25,6 +25,7 @@ import (
 // This test therefore exercises the "Admin user created" log path, which
 // is emitted on the first cold-start bootstrap and must reach stderr.
 func TestAdminBootstrap_LogsToStderr_NotStdout(t *testing.T) {
+	// Not parallel: it swaps os.Stdout and the standard logger, which other tests write to.
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 	const adminEmail = "stderr-bootstrap@test.example"
diff --git a/internal/database/postgres/migrations/savings_snapshots_pk_test.go b/internal/database/postgres/migrations/savings_snapshots_pk_test.go
index ab6f2d15d..fd5a12dd2 100644
--- a/internal/database/postgres/migrations/savings_snapshots_pk_test.go
+++ b/internal/database/postgres/migrations/savings_snapshots_pk_test.go
@@ -22,10 +22,12 @@ import (
 // EXISTS guard makes 000027 safe to apply regardless of whether 000018 has
 // already created the constraint.
 func TestMigration_SavingsSnapshotsPK(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
 	t.Run("full migration from scratch succeeds (000018 + 000027 coexist)", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -49,6 +51,7 @@ func TestMigration_SavingsSnapshotsPK(t *testing.T) {
 	})
 
 	t.Run("rollback to 000026 then re-apply 000027 succeeds", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
diff --git a/internal/database/postgres/migrations/split_savingsplans_test.go b/internal/database/postgres/migrations/split_savingsplans_test.go
index adca2c26f..c7a99d06f 100644
--- a/internal/database/postgres/migrations/split_savingsplans_test.go
+++ b/internal/database/postgres/migrations/split_savingsplans_test.go
@@ -19,6 +19,7 @@ import (
 // #71's sagemaker row, and fresh install. Round-trips up/down to verify
 // no row identity is lost in the lossy down migration.
 func TestMigration_SplitSavingsPlans(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
@@ -54,6 +55,7 @@ func TestMigration_SplitSavingsPlans(t *testing.T) {
 	}
 
 	t.Run("scenario 1: umbrella only", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -111,6 +113,7 @@ func TestMigration_SplitSavingsPlans(t *testing.T) {
 	})
 
 	t.Run("scenario 2: umbrella + PR #71 sagemaker row (different values)", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -158,6 +161,7 @@ func TestMigration_SplitSavingsPlans(t *testing.T) {
 	})
 
 	t.Run("scenario 3: fresh install (no SP rows)", func(t *testing.T) {
+		t.Parallel()
 		container := testhelpers.RequireEmptyDatabase(ctx, t)
 		pool := container.DB.Pool()
 
@@ -189,6 +193,7 @@ func TestMigration_SplitSavingsPlans(t *testing.T) {
 // source key should be removed. Plans without an SP entry should be
 // untouched.
 func TestMigration_SplitSavingsPlans_PurchasePlansJSONB(t *testing.T) {
+	t.Parallel()
 	ctx := context.Background()
 	migrationsPath := getMigrationsPath()
 
diff --git a/internal/database/postgres/testhelpers/postgres.go b/internal/database/postgres/testhelpers/postgres.go
index 68ceb7d75..f655d39ad 100644
--- a/internal/database/postgres/testhelpers/postgres.go
+++ b/internal/database/postgres/testhelpers/postgres.go
@@ -39,18 +39,26 @@ type PostgresContainer struct {
 // would be noise rather than guidance.
 func SetupPostgresContainer(ctx context.Context, t *testing.T) (*PostgresContainer, error) {
 	t.Helper()
+	return setupPostgresContainer(ctx, t)
+}
+
+// setupPostgresContainer is SetupPostgresContainer with extra container
+// options, applied after the defaults; the shared server uses it to raise
+// max_connections.
+func setupPostgresContainer(ctx context.Context, t *testing.T, extra ...testcontainers.ContainerCustomizer) (*PostgresContainer, error) {
+	t.Helper()
 
 	// Create PostgreSQL container
-	postgresContainer, err := postgres.Run(ctx,
-		"postgres:16-alpine",
+	opts := append([]testcontainers.ContainerCustomizer{
 		postgres.WithDatabase("cudly_test"),
 		postgres.WithUsername("cudly_test"),
 		postgres.WithPassword("test_password"),
 		testcontainers.WithWaitStrategy(
 			wait.ForLog("database system is ready to accept connections").
 				WithOccurrence(2).
-				WithStartupTimeout(30*time.Second)),
-	)
+				WithStartupTimeout(30 * time.Second)),
+	}, extra...)
+	postgresContainer, err := postgres.Run(ctx, "postgres:16-alpine", opts...)
 	if err != nil {
 		return nil, fmt.Errorf("failed to start postgres container: %w", err)
 	}
diff --git a/internal/database/postgres/testhelpers/shared.go b/internal/database/postgres/testhelpers/shared.go
index 41aabf957..9f28cd8af 100644
--- a/internal/database/postgres/testhelpers/shared.go
+++ b/internal/database/postgres/testhelpers/shared.go
@@ -27,7 +27,8 @@ import (
 // One mutex covers all of it. Holding it while the container starts and the
 // template migrates makes concurrent first callers wait for the one setup
 // instead of racing to do their own, and holding it across CREATE DATABASE
-// keeps clones of one template from contending with each other.
+// keeps clones of one template from contending with each other. Drops take it
+// too, so TerminateSharedPostgres cannot pull the server out from under one.
 type sharedServer struct {
 	mu        sync.Mutex
 	admin     *PostgresContainer // connected to the maintenance database, never handed to a test
@@ -86,7 +87,13 @@ func RequireEmptyDatabase(ctx context.Context, t *testing.T) *PostgresContainer
 func requireSharedDatabase(ctx context.Context, t *testing.T, migrationsPath string) *PostgresContainer {
 	t.Helper()
 
-	testcontainers.SkipIfProviderIsNotHealthy(t)
+	// Probe Docker only until the shared server is up. Once it is, the server
+	// answering is the evidence that matters, and a probe that times out under
+	// load would otherwise skip a test whose database is reachable, the false
+	// green #1597 is about.
+	if !shared.running() {
+		providerProbe(t)
+	}
 
 	name, cfg, err := shared.newDatabase(ctx, t, migrationsPath)
 	require.NoError(t, err,
@@ -103,6 +110,17 @@ func requireSharedDatabase(ctx context.Context, t *testing.T, migrationsPath str
 	return &PostgresContainer{Config: cfg, DB: conn}
 }
 
+// providerProbe skips t when Docker is unusable. A variable so a test can
+// observe when it runs.
+var providerProbe = testcontainers.SkipIfProviderIsNotHealthy
+
+// running reports whether the shared server is up.
+func (s *sharedServer) running() bool {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	return s.admin != nil
+}
+
 // TerminateSharedPostgres stops the shared container if one was started. Call
 // it from TestMain after m.Run. Ryuk reaps the container if the process dies
 // first, so this is tidiness rather than the only line of defense.
@@ -162,10 +180,23 @@ func (s *sharedServer) start(ctx context.Context, t *testing.T) error {
 	}
 	// Detached from ctx: the container outlives the test that happened to be
 	// first, so that test's deadline or cancellation must not reach it.
-	s.admin, s.startErr = SetupPostgresContainer(context.WithoutCancel(ctx), t)
+	s.admin, s.startErr = setupPostgresContainer(context.WithoutCancel(ctx), t,
+		testcontainers.WithCmdArgs("-c", fmt.Sprintf("max_connections=%d", sharedMaxConnections)))
 	return s.startErr
 }
 
+// sharedMaxConnections is the shared server's max_connections, raised from
+// PostgreSQL's default of 100 because tests on it may run in parallel
+// (t.Parallel), up to -parallel (GOMAXPROCS by default) at once. Each running
+// test can hold a pool of up to 10 connections (MaxConnections in
+// SetupPostgresContainer) plus the migrator's own connection and a spare
+// session or two, about 13 at worst, and the admin pool adds up to 10 more.
+// 500 covers that worst case up to -parallel=36. Real use is far lower, since
+// pools only open what they need: the migrations package peaked at 50
+// connections with -parallel=16 and 21 with -parallel=4. Raising the server limit instead of
+// shrinking the per-database pool leaves every test's pool exactly as it was.
+const sharedMaxConnections = 500
+
 // templateKey identifies the migrations directory a template was built from.
 // It is absolute so that "../database/postgres/migrations" and a
 // runtime.Caller-derived path to the same directory share one template instead
@@ -188,11 +219,20 @@ func (s *sharedServer) template(ctx context.Context, migrationsPath string) (str
 		s.templates = map[string]templateDB{}
 	}
 	tmpl := templateDB{name: fmt.Sprintf("cudly_template_%d", len(s.templates)+1)}
-	tmpl.err = s.buildTemplate(ctx, tmpl.name, key)
+	// Detached from ctx, like the container in start: the outcome is cached for
+	// every later caller, so the first caller's cancellation or deadline must
+	// not be what decides it. templateBuildTimeout still bounds a hung build.
+	buildCtx, cancel := context.WithTimeout(context.WithoutCancel(ctx), templateBuildTimeout)
+	defer cancel()
+	tmpl.err = s.buildTemplate(buildCtx, tmpl.name, key)
 	s.templates[key] = tmpl
 	return tmpl.name, tmpl.err
 }
 
+// templateBuildTimeout bounds one template build. The full chain takes seconds;
+// this is a backstop against a hang, generous enough for a loaded CI runner.
+const templateBuildTimeout = 10 * time.Minute
+
 // buildTemplate creates name, applies every migration under migrationsPath to
 // it, and then closes it to connections.
 func (s *sharedServer) buildTemplate(ctx context.Context, name, migrationsPath string) error {
@@ -219,7 +259,17 @@ func (s *sharedServer) buildTemplate(ctx context.Context, name, migrationsPath s
 
 // dropDatabase removes a per-test database. FORCE ends any connection the test
 // leaked, which would otherwise block the drop and leave the database behind.
+//
+// It holds s.mu so TerminateSharedPostgres cannot close the admin connection
+// mid-drop. With no server left there is nothing to drop: terminating the
+// container took every database on it along.
 func (s *sharedServer) dropDatabase(t *testing.T, name string) {
+	s.mu.Lock()
+	defer s.mu.Unlock()
+	if s.admin == nil {
+		return
+	}
+
 	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
 	defer cancel()
 
@@ -229,12 +279,14 @@ func (s *sharedServer) dropDatabase(t *testing.T, name string) {
 }
 
 // configFor returns a copy of the shared container's config pointed at name.
+// Callers hold s.mu.
 func (s *sharedServer) configFor(name string) *database.Config {
 	cfg := *s.admin.Config
 	cfg.Database = name
 	return &cfg
 }
 
+// exec runs sql on the admin connection. Callers hold s.mu.
 func (s *sharedServer) exec(ctx context.Context, sql string) error {
 	_, err := s.admin.DB.Exec(ctx, sql)
 	return err
diff --git a/internal/database/postgres/testhelpers/shared_integration_test.go b/internal/database/postgres/testhelpers/shared_integration_test.go
index 5b6a5a2dd..26734413f 100644
--- a/internal/database/postgres/testhelpers/shared_integration_test.go
+++ b/internal/database/postgres/testhelpers/shared_integration_test.go
@@ -192,6 +192,66 @@ func TestRequireMigratedDatabase_ConcurrentFirstUse(t *testing.T) {
 	assert.Len(t, shared.templates, 1, "concurrent first callers must share one template")
 }
 
+// TestRequireMigratedDatabase_CanceledFirstCallerDoesNotPoisonTemplate has the
+// caller that triggers the template build arrive with its context already
+// canceled. The build's outcome is cached for the whole binary, so it must not
+// depend on that caller's context: later callers get a migrated database.
+func TestRequireMigratedDatabase_CanceledFirstCallerDoesNotPoisonTemplate(t *testing.T) {
+	require.NoError(t, TerminateSharedPostgres(), "reset to a cold start, so this caller builds the template")
+
+	canceled, cancel := context.WithCancel(context.Background())
+	cancel()
+	// The caller's own CREATE DATABASE may fail on its dead context; that
+	// failure is the caller's alone and is not what this test is about.
+	if name, _, err := shared.newDatabase(canceled, t, sharedTestMigrationsPath()); err == nil {
+		t.Cleanup(func() { shared.dropDatabase(t, name) })
+	}
+
+	shared.mu.Lock()
+	tmpl, built := shared.templates[templateKey(sharedTestMigrationsPath())]
+	shared.mu.Unlock()
+	require.True(t, built, "the canceled first caller must still have built the template")
+	require.NoError(t, tmpl.err, "a canceled first caller must not cache a failed template")
+
+	ctx, stop := context.WithTimeout(context.Background(), 2*time.Minute)
+	defer stop()
+	db := RequireMigratedDatabase(ctx, t, sharedTestMigrationsPath())
+	requireFullyMigrated(ctx, t, db.DB, latestMigrationVersion(t))
+}
+
+// TestRequireEmptyDatabase_CleanupAfterTerminate stops the shared server while
+// a test still holds a database on it, as a TestMain teardown racing a late
+// cleanup would. The cleanup must find nothing to drop, not fail or panic.
+func TestRequireEmptyDatabase_CleanupAfterTerminate(t *testing.T) {
+	passed := t.Run("terminates the server mid-test", func(t *testing.T) {
+		ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
+		defer cancel()
+		db := RequireEmptyDatabase(ctx, t)
+		require.NoError(t, db.DB.Ping(ctx))
+		require.NoError(t, TerminateSharedPostgres())
+	})
+	assert.True(t, passed, "cleanup after the shared server stopped must not fail the test")
+}
+
+// TestRequireSharedDatabase_ProbesDockerOnlyUntilServerIsUp pins that the
+// Docker probe runs on a cold start but not once the server is up. A probe
+// that times out under load would skip a test whose database is reachable,
+// a false green.
+func TestRequireSharedDatabase_ProbesDockerOnlyUntilServerIsUp(t *testing.T) {
+	require.NoError(t, TerminateSharedPostgres(), "reset to a cold start")
+	probes := 0
+	orig := providerProbe
+	providerProbe = func(t *testing.T) { probes++; orig(t) }
+	t.Cleanup(func() { providerProbe = orig })
+
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
+	defer cancel()
+	RequireEmptyDatabase(ctx, t)
+	assert.Equal(t, 1, probes, "a cold start must probe Docker before starting the server")
+	RequireEmptyDatabase(ctx, t)
+	assert.Equal(t, 1, probes, "a running server must not be probed again")
+}
+
 // connString points cfg's server and credentials at dbName.
 func connString(cfg *database.Config, dbName string) string {
 	u := url.URL{