feat(subscriptions): pin the winning variant via env

Add SUBSCRIPTION_EXPERIMENT_FORCE_VARIANT: a Pennant before() override that
serves one variant to every user, so once a winner is chosen the split ends
with an env flip (no deploy, stored assignments untouched). Invalid values are
ignored and fall through to normal assignment.

app/Features/SubscriptionExperiment.php

@@ -13,9 +13,8 @@ use Carbon\CarbonImmutable;
  * registered on or after the start is split evenly into the three variants by a
  * stable hash of their id, so the bucket never changes for a given user.
  *
- * The split is deterministic (crc32(id) % 3); the funnel report mirrors the same
- * formula in SQL. Manual overrides via `feature:enable` are honoured at runtime
- * but are not reflected in that report — keep overrides to QA accounts.
+ * The split is deterministic (crc32(id) % 3) and persisted by Pennant; the funnel
+ * report reads that persisted value so it always matches what the user was served.
  *
  * @api
  */
@@ -29,6 +28,21 @@ class SubscriptionExperiment
 
     public const PAY_NOW = 'pay_now';
 
+    /**
+     * In-memory override that pins every user to the winning variant once the
+     * experiment is decided. Returning non-null skips both storage and resolve,
+     * so flipping SUBSCRIPTION_EXPERIMENT_FORCE_VARIANT rolls the winner out to
+     * everyone without a deploy and without rewriting stored assignments.
+     */
+    public function before(?User $user): ?string
+    {
+        $forced = config('subscriptions.experiment.force_variant');
+
+        return in_array($forced, [self::CONTROL, self::REDUCED_TRIAL, self::PAY_NOW], true)
+            ? $forced
+            : null;
+    }
+
     public function resolve(?User $user): string
     {
         $startedAt = config('subscriptions.experiment.started_at');

config/subscriptions.php

@@ -35,6 +35,9 @@ return [
 
     'experiment' => [
         'started_at' => env('SUBSCRIPTION_EXPERIMENT_STARTED_AT'),
+        // Once a winner is chosen, set this to control / reduced_trial / pay_now
+        // to give every user that variant and end the split (env-only, no deploy).
+        'force_variant' => env('SUBSCRIPTION_EXPERIMENT_FORCE_VARIANT'),
         'reduced_trial' => [
             'monthly' => (int) env('SUBSCRIPTION_EXPERIMENT_REDUCED_TRIAL_MONTHLY', 3),
             'yearly' => (int) env('SUBSCRIPTION_EXPERIMENT_REDUCED_TRIAL_YEARLY', 7),

tests/Feature/SubscriptionExperimentTest.php

@@ -36,6 +36,26 @@ it('treats everyone as legacy while the experiment is off', function () {
     expect(app(ExperimentOffer::class)->variantFor($user))->toBe(SubscriptionExperiment::LEGACY);
 });
 
+it('pins every user to the forced winner variant', function () {
+    config(['subscriptions.experiment.force_variant' => SubscriptionExperiment::PAY_NOW]);
+    $offer = app(ExperimentOffer::class);
+
+    $legacy = User::factory()->create(['created_at' => CarbonImmutable::parse('2026-05-01')]);
+    $fresh = User::factory()->create(['created_at' => CarbonImmutable::parse('2026-06-10')]);
+
+    expect($offer->variantFor($legacy))->toBe(SubscriptionExperiment::PAY_NOW)
+        ->and($offer->variantFor($fresh))->toBe(SubscriptionExperiment::PAY_NOW)
+        ->and($offer->trialDaysFor($fresh, 'monthly'))->toBe(0);
+});
+
+it('ignores an invalid forced variant', function () {
+    config(['subscriptions.experiment.force_variant' => 'bogus']);
+
+    $user = User::factory()->create(['created_at' => CarbonImmutable::parse('2026-05-01')]);
+
+    expect(app(ExperimentOffer::class)->variantFor($user))->toBe(SubscriptionExperiment::LEGACY);
+});
+
 it('splits post-start users across all three variants and stays stable per user', function () {
     $offer = app(ExperimentOffer::class);
     $variants = [];