feat(paywalls): fall back to the offerings paywall when the workflow fetch fails

The /v1/config endpoint can be disabled for the session after a 4xx (the
kill switch), be unreachable, or simply have no workflow for the offering
yet. In all of those cases the offering still carries the paywall that
/offerings delivered, so render that through the regular components path
instead of surfacing PaywallState.Error — apps keep showing a paywall
when the config layer can't serve one. The error state remains for
offerings with nothing to fall back to.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

Author: vegaro

ui/revenuecatui/src/main/kotlin/com/revenuecat/purchases/ui/revenuecatui/data/PaywallViewModel.kt

@@ -801,14 +801,26 @@ internal class PaywallViewModelImpl(
         val resolvedOfferingSelection = resolveOfferingSelection(offeringSelection)
         val selectedOffering = resolvedOfferingSelection.selectedOffering
 
-        // When workflows are enabled, every non-legacy paywall is served through the /workflows
-        // endpoint. `offering.paywall == null` is the durable marker of a non-legacy (workflow)
+        // When workflows are enabled, every non-legacy paywall is served through the workflows
+        // path. `offering.paywall == null` is the durable marker of a non-legacy (workflow)
         // paywall: a legacy v1 paywall always carries `offering.paywall`, and that field stays
         // even after `paywallComponents` is removed and all V2 paywalls move to workflows. We
         // deliberately do NOT gate on `paywallComponents`, which is going away.
         if (useWorkflowsEndpoint && selectedOffering != null && selectedOffering.paywall == null) {
-            presentWorkflow(selectedOffering, resolvedOfferingSelection.offeringsForExitOfferLookup)
-            return
+            try {
+                presentWorkflow(selectedOffering, resolvedOfferingSelection.offeringsForExitOfferLookup)
+                return
+            } catch (e: PurchasesException) {
+                // The workflow could not be served — the config endpoint is disabled for the session
+                // (4xx kill switch), unreachable, or the offering has no workflow yet. Degrade to the
+                // paywall /offerings already delivered so the app still shows something; rethrow
+                // (→ PaywallState.Error) only when there is nothing to fall back to.
+                if (selectedOffering.paywallComponents == null) throw e
+                Logger.w(
+                    "Paywalls: Failed to fetch workflow for offering '${selectedOffering.identifier}' " +
+                        "(${e.message}). Falling back to the offerings-provided paywall.",
+                )
+            }
         }
 
         val exitOfferingId = selectedOffering?.paywallComponents?.data?.exitOffers?.dismiss?.offeringId

ui/revenuecatui/src/test/kotlin/com/revenuecat/purchases/ui/revenuecatui/data/PaywallViewModelTest.kt

@@ -3223,6 +3223,64 @@ class PaywallViewModelTest {
         coVerify(exactly = 1) { purchases.awaitGetWorkflow(offeringWithWPL.identifier) }
     }
 
+    @Test
+    fun `when useWorkflows is true and the workflow fetch fails, falls back to the offerings-provided paywall`() {
+        // The config endpoint may be disabled for the session (4xx kill switch) or unreachable, or the
+        // offering may have no workflow yet. The offering still carries the paywall /offerings delivered,
+        // so the paywall renders through the regular components path instead of erroring.
+        coEvery { purchases.workflowIdForOfferingId(offeringWithWPL.identifier) } returns null
+        coEvery { purchases.awaitGetWorkflow(offeringWithWPL.identifier) } throws PurchasesException(
+            PurchasesError(PurchasesErrorCode.UnknownError, "Workflow is unavailable from remote config."),
+        )
+
+        val model = PaywallViewModelImpl(
+            MockResourceProvider(),
+            purchases,
+            PaywallOptions.Builder(dismissRequest = { dismissInvoked = true })
+                .setListener(listener)
+                .setOffering(offeringWithWPL)
+                .build(),
+            TestData.Constants.currentColorScheme,
+            isDarkMode = false,
+            shouldDisplayBlock = null,
+            useWorkflowsEndpoint = true,
+        )
+
+        assertThat(model.state.value).isInstanceOf(PaywallState.Loaded.Components::class.java)
+        coVerify(exactly = 1) { purchases.awaitGetWorkflow(offeringWithWPL.identifier) }
+    }
+
+    @Test
+    fun `when useWorkflows is true and the workflow fetch fails with no fallback paywall, surfaces the error`() {
+        val offeringWithoutPaywallData = Offering(
+            identifier = "offering-no-paywall-data",
+            serverDescription = "description",
+            metadata = emptyMap(),
+            availablePackages = listOf(TestData.Packages.monthly),
+            paywallComponents = null,
+            webCheckoutURL = null,
+        )
+        coEvery { purchases.workflowIdForOfferingId(offeringWithoutPaywallData.identifier) } returns null
+        coEvery { purchases.awaitGetWorkflow(offeringWithoutPaywallData.identifier) } throws PurchasesException(
+            PurchasesError(PurchasesErrorCode.UnknownError, "Workflow is unavailable from remote config."),
+        )
+
+        val model = PaywallViewModelImpl(
+            MockResourceProvider(),
+            purchases,
+            PaywallOptions.Builder(dismissRequest = { dismissInvoked = true })
+                .setListener(listener)
+                .setOffering(offeringWithoutPaywallData)
+                .build(),
+            TestData.Constants.currentColorScheme,
+            isDarkMode = false,
+            shouldDisplayBlock = null,
+            useWorkflowsEndpoint = true,
+        )
+
+        assertThat(model.state.value).isInstanceOf(PaywallState.Error::class.java)
+    }
+
     private fun create(
         offering: Offering? = null,
         customPurchaseLogic: PaywallPurchaseLogic? = null,