feat(azure): use GA full caching for ephemeral OS disks

docs/commands/checkpoint.md

@@ -186,7 +186,7 @@ the checkpoint for inspection.
 - Azure cannot create a managed image from an active VM, so the Azure native
   path uses a managed OS-disk snapshot. That snapshot requires a managed OS disk
   (the default); creation refuses leases started with
-  `--azure-os-disk ephemeral` or `--azure-os-disk ephemeral-preview`, where
+  `--azure-os-disk ephemeral`, where
   Azure reports success but does not capture live disk state.
 - Direct Azure Windows disk snapshots support `windows.mode=normal` leases and
   require `--no-reboot=false`. Crabbox

docs/commands/run.md

@@ -1132,10 +1132,11 @@ config rather than argv.
 
 Azure one-shot leases use managed `StandardSSD_LRS` OS disks by default so they
 can become native checkpoint sources. Use `--azure-os-disk ephemeral` only for
-stateless leases that do not need native Azure checkpoint/fork support;
-`--azure-os-disk ephemeral-preview` opts into Azure's public-preview
-full-caching ephemeral OS disk mode. `--azure-os-disk auto` is accepted for
-compatibility and resolves to managed.
+stateless leases that do not need native Azure checkpoint/fork support. This
+mode enables GA full caching and requires at least eight vCPUs, a supported VM
+family, and sufficient local storage. See [Azure disk requirements](../features/azure.md#os-disk-mode).
+`ephemeral-preview` is removed; use `ephemeral`. `--azure-os-disk auto` resolves
+to managed.
 
 ## Flags
 

docs/commands/warmup.md

@@ -305,9 +305,11 @@ sync/run/actions contract. Azure Windows does not provision browser/code.
 Azure leases use managed `StandardSSD_LRS` OS disks by default so native
 disk-snapshot checkpoints can be created and forked. Use
 `--azure-os-disk ephemeral` only for stateless leases that don't need native
-Azure checkpoint/fork support. Use `--azure-os-disk ephemeral-preview` for
-Azure's public-preview full-caching ephemeral OS disk mode; `--azure-os-disk
-auto` resolves to managed.
+Azure checkpoint/fork support. This mode enables GA full caching and requires
+at least eight vCPUs plus sufficient local storage on a supported VM family.
+See [Azure disk requirements](../features/azure.md#os-disk-mode).
+`ephemeral-preview` is removed; use `ephemeral`. `--azure-os-disk auto` resolves
+to managed.
 
 `--azure-backend dynamic-sessions` keeps `--provider azure` as the family
 selector while routing to the `azure-dynamic-sessions` delegated backend.
@@ -412,7 +414,7 @@ bootstrap, key migration, or failure cleanup.
 --reclaim                          overwrite an existing local claim for this lease
 --timing-json                      print a final JSON timing record on stderr
 --azure-backend vm|dynamic-sessions
---azure-os-disk managed|ephemeral|ephemeral-preview|auto
+--azure-os-disk managed|ephemeral|auto
 ```
 
 Provider-specific flags (for example `--azure-backend`, `--e2b-template`,

docs/features/azure.md

@@ -44,7 +44,6 @@ dynamic-sessions`; see the [Provider Reference](../providers/README.md).
 crabbox warmup --provider azure --class beast
 crabbox warmup --provider azure --arch arm64 --class fast
 crabbox warmup --provider azure --class beast --azure-os-disk ephemeral
-crabbox warmup --provider azure --class beast --azure-os-disk ephemeral-preview
 crabbox run --provider azure --class standard -- pnpm test
 crabbox warmup --provider azure --target windows --class standard
 crabbox warmup --provider azure --target windows --desktop --class standard
@@ -130,12 +129,17 @@ SSH, Windows, and loopback-only VNC credentials. A per-fork deny-all network
 security group keeps the copied VM unreachable until credential rotation
 finishes, then Crabbox attaches the normal shared SSH allowlist.
 
-`azure.osDisk: ephemeral-preview` opts into Azure's public-preview
-full-caching mode for ephemeral OS disks. Crabbox sends Compute API
-`2025-04-01` with `diffDiskSettings.enableFullCaching: true`; for known
-Crabbox Azure fallback lists it skips 2-core, 4-core, and no-local-disk SKUs
-that the preview cannot support. `azure.osDisk: auto` is accepted for
-compatibility and resolves to managed.
+`azure.osDisk: ephemeral` selects generally available full caching. Crabbox
+sets `diffDiskSettings.enableFullCaching: true` with Compute API `2026-04-01`.
+Full caching requires at least eight vCPUs and local storage greater than twice
+the OS disk size plus 1 GiB. Supported families are N/L/M/H, D/DC/E/Eb/EC v5-v7,
+and F v6-v7. Azure validates local storage capacity for the selected image.
+Crabbox filters known unsupported sizes from class fallback lists.
+See [Microsoft's prerequisites](https://learn.microsoft.com/en-us/azure/virtual-machines/ephemeral-os-disks#prerequisites-for-full-caching).
+
+`ephemeral-preview` is removed. Replace it with `ephemeral` in config, flags,
+and environment variables. Existing `ephemeral` settings now request full caching;
+small VMs and Fsv2 no longer qualify. `auto` still resolves to `managed`.
 
 Snapshot performance can be selected explicitly without changing those
 defaults. `azure.snapshotSKU` / `--azure-snapshot-sku` controls the storage SKU

docs/features/checkpoints.md

@@ -185,7 +185,7 @@ for new Azure leases. Crabbox refuses native checkpoint creation from Azure
 ephemeral-OS-disk leases (Azure reports success but does not capture live disk
 state). Azure disk-snapshot forks boot from a specialized OS disk and may inherit
 the source machine identity — treat them as exact clones. Use
-`--azure-os-disk ephemeral` or `--azure-os-disk ephemeral-preview` only for
+`--azure-os-disk ephemeral` only for
 stateless leases that do not need native checkpoints.
 
 **Parallels notes.** A forkable Parallels snapshot must be taken from a

docs/features/configuration.md

@@ -347,18 +347,18 @@ azure:
   backend: vm           # vm | dynamic-sessions
   location: eastus
   resourceGroup: crabbox-leases
-  osDisk: managed       # managed | ephemeral | ephemeral-preview | auto
+  osDisk: managed       # managed | ephemeral | auto
   vnet: crabbox-vnet
   subnet: crabbox-subnet
   nsg: crabbox-nsg
 ```
 
 Azure uses managed `StandardSSD_LRS` OS disks by default so leases can support
-native disk-snapshot checkpoints. `ephemeral` opts into local OS disks for
-stateless leases and disables native Azure checkpoint/fork support.
-`ephemeral-preview` opts into Azure's public-preview full-caching ephemeral OS
-disk mode and skips known unsupported Crabbox Azure SKUs. `auto` is accepted for
-compatibility and resolves to managed.
+native disk-snapshot checkpoints. `ephemeral` enables GA full caching for
+stateless leases and disables native Azure checkpoint/fork support. It requires
+at least eight vCPUs, a supported VM family, and sufficient local storage.
+See [Azure disk requirements](azure.md#os-disk-mode). `ephemeral-preview` is
+removed; replace it with `ephemeral`. `auto` resolves to `managed`.
 
 ### Azure Dynamic Sessions
 

docs/providers/azure.md

@@ -74,7 +74,6 @@ Azure supports both execution modes:
 crabbox warmup --provider azure --class beast
 crabbox warmup --provider azure --arch arm64 --class fast
 crabbox warmup --provider azure --class beast --azure-os-disk ephemeral
-crabbox warmup --provider azure --class beast --azure-os-disk ephemeral-preview
 crabbox run --provider azure --class standard -- pnpm test
 crabbox run --provider azure --azure-backend dynamic-sessions -- pnpm test
 crabbox warmup --provider azure --target windows --class standard
@@ -89,9 +88,8 @@ crabbox cleanup --provider azure
 `--type` is exact (for example `--type Standard_D32ads_v6`). Use `--class` when
 you want SKU fallback. Azure leases use managed OS disks by default, so native
 checkpoint/fork works without extra flags. Pass `--azure-os-disk ephemeral` only
-for stateless leases that do not need native checkpoint/fork. Pass
-`--azure-os-disk ephemeral-preview` to opt into Azure's public-preview
-full-caching mode for ephemeral OS disks.
+for stateless leases that do not need native checkpoint/fork. This mode enables
+generally available full caching and requires at least eight vCPUs.
 
 ## Fixed operation IDs
 
@@ -107,8 +105,8 @@ SKU unless `--type` is explicit). They do not perform SKU, market, or region
 fallback, and do not roll back an ambiguous allocation. VM creation is
 create-only. Replay observes the original attempt and never submits a second
 allocation. This supports VM-image leases, including native Windows and WSL2;
-snapshot forks and `ephemeral-preview` disks are not supported on this direct
-fixed-ID path. Ordinary direct leases retain their existing fallback behavior.
+snapshot forks are not supported on this direct fixed-ID path. Full-caching
+ephemeral disks support fixed IDs through create-only SDK requests. Ordinary direct leases retain their existing fallback behavior.
 
 Use `stop --provider azure <lease-id>` for owned cleanup. Successful deletion
 retains a terminal tombstone; the ID cannot create another VM. If a failed
@@ -169,19 +167,22 @@ not supported because those VM sizes do not support nested virtualization.
 VM public IP, `private` uses the NIC private IP from the vnet. Use `private` when
 connecting through a VPN to the Azure virtual network.
 
-`azure.osDisk` accepts `managed`, `ephemeral`, `ephemeral-preview`, or `auto`:
+`azure.osDisk` accepts `managed`, `ephemeral`, or `auto`:
 
 - `managed` (default) provisions a managed `StandardSSD_LRS` OS disk so Azure
   native disk-snapshot checkpoints work.
-- `ephemeral` opts into a local OS disk. It requires a SKU with ephemeral OS disk
-  support, fails during provisioning when the selected SKU cannot support it, and
-  disables native Azure checkpoint/fork.
-- `ephemeral-preview` enables Azure ephemeral OS disk full caching with Compute
-  API `2025-04-01`. It is public preview, has the same checkpoint/fork limits as
-  `ephemeral`, and skips known unsupported 2-core, 4-core, and no-local-disk
-  Azure SKUs from Crabbox fallback lists.
+- `ephemeral` enables GA full caching with Compute API `2026-04-01`.
+  It requires ephemeral OS support, at least eight vCPUs, and local storage
+  greater than twice the OS disk size plus 1 GiB. Supported families are
+  N/L/M/H, D/DC/E/Eb/EC v5-v7, and F v6-v7. Azure validates image capacity.
+  Crabbox filters known unsupported class fallbacks. Native checkpoint/fork
+  remains unavailable.
 - `auto` is accepted for compatibility and resolves to `managed`.
 
+`ephemeral-preview` is removed; replace it with `ephemeral`. Existing `ephemeral`
+settings now enable full caching, so smaller VMs and Fsv2 no longer qualify.
+See [Microsoft's full caching prerequisites](https://learn.microsoft.com/en-us/azure/virtual-machines/ephemeral-os-disks#prerequisites-for-full-caching).
+
 ### Environment variables
 
 Direct-mode config can be supplied entirely via environment:
@@ -196,7 +197,7 @@ CRABBOX_AZURE_LOCATION
 CRABBOX_AZURE_RESOURCE_GROUP
 CRABBOX_AZURE_IMAGE
 CRABBOX_AZURE_WINDOWS_ARM64_IMAGE
-CRABBOX_AZURE_OS_DISK            # managed | ephemeral | ephemeral-preview | auto
+CRABBOX_AZURE_OS_DISK            # managed | ephemeral | auto
 CRABBOX_AZURE_VNET
 CRABBOX_AZURE_SUBNET
 CRABBOX_AZURE_NSG