From 6cbbf37c33d2cb77b760e54e08a9e3acad57aa40 Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Fri, 6 Feb 2026 15:31:25 -0800
Subject: [PATCH 01/11] Update instance-create to handle both v4 and v6
 ephemeral IP options

---
 app/forms/instance-create.tsx       | 374 ++++++++++++++++++----------
 test/e2e/instance-create.e2e.ts     | 261 +++++++++++--------
 test/e2e/ip-pool-silo-config.e2e.ts | 118 +++++----
 3 files changed, 468 insertions(+), 285 deletions(-)

diff --git a/app/forms/instance-create.tsx b/app/forms/instance-create.tsx
index 5c0941b68..ea6cafa57 100644
--- a/app/forms/instance-create.tsx
+++ b/app/forms/instance-create.tsx
@@ -66,7 +66,6 @@ import { HL } from '~/components/HL'
 import { getProjectSelector, useProjectSelector } from '~/hooks/use-params'
 import { addToast } from '~/stores/toast'
 import { Button } from '~/ui/lib/Button'
-import { Checkbox } from '~/ui/lib/Checkbox'
 import { toComboboxItems } from '~/ui/lib/Combobox'
 import { FormDivider } from '~/ui/lib/Divider'
 import { EmptyMessage } from '~/ui/lib/EmptyMessage'
@@ -142,9 +141,11 @@ export type InstanceCreateInput = Assign<
     userData: File | null
     // ssh keys are always specified. we do not need the undefined case
     sshPublicKeys: NonNullable<InstanceCreate['sshPublicKeys']>
-    // Pool for ephemeral IP selection
-    ephemeralIpPool: string
-    assignEphemeralIp: boolean
+    // Ephemeral IP fields (dual stack support)
+    ephemeralIpv4: boolean
+    ephemeralIpv4Pool: string
+    ephemeralIpv6: boolean
+    ephemeralIpv6Pool: string
 
     // Selected floating IPs to attach on create.
     floatingIps: NameOrId[]
@@ -215,8 +216,10 @@ const baseDefaultValues: InstanceCreateInput = {
   start: true,
 
   userData: null,
-  ephemeralIpPool: '',
-  assignEphemeralIp: false,
+  ephemeralIpv4: false,
+  ephemeralIpv4Pool: '',
+  ephemeralIpv6: false,
+  ephemeralIpv6Pool: '',
   floatingIps: [],
 }
 
@@ -317,10 +320,10 @@ export default function CreateInstanceForm() {
   const compatibleDefaultPools = unicastPools
     .filter(poolHasIpVersion(defaultCompatibleVersions))
     .filter((p) => p.isDefault)
-  // TODO: when we switch to dual stack ephemeral IPs, this will need to change
-  // to handle selecting default pools for both v4 and v6
-  const defaultEphemeralIpPool =
-    compatibleDefaultPools.length > 0 ? compatibleDefaultPools[0].name : ''
+
+  // Compute defaults for dual ephemeral IP support
+  const hasV4Default = compatibleDefaultPools.some((p) => p.ipVersion === 'v4')
+  const hasV6Default = compatibleDefaultPools.some((p) => p.ipVersion === 'v6')
 
   const defaultValues: InstanceCreateInput = {
     ...baseDefaultValues,
@@ -328,8 +331,10 @@ export default function CreateInstanceForm() {
     bootDiskSourceType: defaultSource,
     sshPublicKeys: allKeys,
     bootDiskSize: diskSizeNearest10(defaultImage?.size / GiB),
-    ephemeralIpPool: defaultEphemeralIpPool || '',
-    assignEphemeralIp: !!defaultEphemeralIpPool,
+    ephemeralIpv4: hasV4Default && defaultCompatibleVersions.includes('v4'),
+    ephemeralIpv4Pool: '',
+    ephemeralIpv6: hasV6Default && defaultCompatibleVersions.includes('v6'),
+    ephemeralIpv6Pool: '',
     floatingIps: [],
   }
 
@@ -438,22 +443,42 @@ export default function CreateInstanceForm() {
 
           const bootDisk = getBootDiskAttachment(values, allImages)
 
-          const assignEphemeralIp = values.assignEphemeralIp
-          const ephemeralIpPool = values.ephemeralIpPool
-
-          const externalIps: ExternalIpCreate[] = values.floatingIps.map((floatingIp) => ({
-            type: 'floating' as const,
-            floatingIp,
-          }))
-
-          if (assignEphemeralIp) {
-            externalIps.push({
-              type: 'ephemeral',
-              // form validation is meant to ensure that pool is set when
-              // assignEphemeralIp checkbox is checked
-              poolSelector: { type: 'explicit', pool: ephemeralIpPool },
-            })
-          }
+          // Construct external IPs: ephemeral IPs first (v4 before v6), then floating IPs
+          // Only include ipVersion when requesting BOTH ephemeral IPs with auto selectors
+          const requestingBothEphemeralIps = values.ephemeralIpv4 && values.ephemeralIpv6
+          const externalIps: ExternalIpCreate[] = [
+            // v4 ephemeral if enabled (order: v4 before v6)
+            ...(values.ephemeralIpv4
+              ? [
+                  {
+                    type: 'ephemeral' as const,
+                    poolSelector: values.ephemeralIpv4Pool
+                      ? { type: 'explicit' as const, pool: values.ephemeralIpv4Pool }
+                      : requestingBothEphemeralIps
+                        ? { type: 'auto' as const, ipVersion: 'v4' as const }
+                        : { type: 'auto' as const },
+                  },
+                ]
+              : []),
+            // v6 ephemeral if enabled
+            ...(values.ephemeralIpv6
+              ? [
+                  {
+                    type: 'ephemeral' as const,
+                    poolSelector: values.ephemeralIpv6Pool
+                      ? { type: 'explicit' as const, pool: values.ephemeralIpv6Pool }
+                      : requestingBothEphemeralIps
+                        ? { type: 'auto' as const, ipVersion: 'v6' as const }
+                        : { type: 'auto' as const },
+                  },
+                ]
+              : []),
+            // floating IPs (can coexist with ephemeral)
+            ...values.floatingIps.map((floatingIp) => ({
+              type: 'floating' as const,
+              floatingIp,
+            })),
+          ]
 
           const userData = values.userData
             ? await readBlobAsBase64(values.userData)
@@ -775,14 +800,17 @@ const NetworkingSection = ({
   const networkInterfaces = useWatch({ control, name: 'networkInterfaces' })
   const [floatingIpModalOpen, setFloatingIpModalOpen] = useState(false)
   const [selectedFloatingIp, setSelectedFloatingIp] = useState<FloatingIp | undefined>()
-  const assignEphemeralIpField = useController({ control, name: 'assignEphemeralIp' })
+  const ephemeralIpv4Field = useController({ control, name: 'ephemeralIpv4' })
+  const ephemeralIpv4PoolField = useController({ control, name: 'ephemeralIpv4Pool' })
+  const ephemeralIpv6Field = useController({ control, name: 'ephemeralIpv6' })
+  const ephemeralIpv6PoolField = useController({ control, name: 'ephemeralIpv6Pool' })
   const floatingIpsField = useController({ control, name: 'floatingIps' })
-  const assignEphemeralIp = assignEphemeralIpField.field.value
-  const attachedFloatingIps = floatingIpsField.field.value ?? EMPTY_NAME_OR_ID_LIST
 
-  const ephemeralIpPoolField = useController({ control, name: 'ephemeralIpPool' })
-
-  const ephemeralIpPool = ephemeralIpPoolField.field.value
+  const ephemeralIpv4 = ephemeralIpv4Field.field.value
+  const ephemeralIpv4Pool = ephemeralIpv4PoolField.field.value
+  const ephemeralIpv6 = ephemeralIpv6Field.field.value
+  const ephemeralIpv6Pool = ephemeralIpv6PoolField.field.value
+  const attachedFloatingIps = floatingIpsField.field.value ?? EMPTY_NAME_OR_ID_LIST
 
   // Calculate compatible IP versions based on NIC type
   const compatibleVersions = useMemo(
@@ -790,6 +818,23 @@ const NetworkingSection = ({
     [networkInterfaces]
   )
 
+  // Filter pools by compatibility and version
+  const compatiblePools = useMemo(
+    () => unicastPools.filter(poolHasIpVersion(compatibleVersions)),
+    [unicastPools, compatibleVersions]
+  )
+  const v4Pools = useMemo(
+    () => compatiblePools.filter((p) => p.ipVersion === 'v4'),
+    [compatiblePools]
+  )
+  const v6Pools = useMemo(
+    () => compatiblePools.filter((p) => p.ipVersion === 'v6'),
+    [compatiblePools]
+  )
+
+  const canAttachV4 = compatibleVersions.includes('v4') && v4Pools.length > 0
+  const canAttachV6 = compatibleVersions.includes('v6') && v6Pools.length > 0
+
   const { project } = useProjectSelector()
   const { data: floatingIpList } = usePrefetchedQuery(
     q(api.floatingIpList, { query: { project, limit: ALL_ISH } })
@@ -813,86 +858,128 @@ const NetworkingSection = ({
     .map((floatingIp) => attachableFloatingIps.find((fip) => fip.name === floatingIp))
     .filter((ip) => !!ip)
 
-  // Filter unicast pools by compatible IP versions
-  // unicastPools is already sorted (defaults first, v4 first, then by name),
-  // so filtering preserves that order
-  const compatiblePools = useMemo(
-    () => unicastPools.filter(poolHasIpVersion(compatibleVersions)),
-    [unicastPools, compatibleVersions]
-  )
+  // IPv4 pool auto-selection
+  useEffect(() => {
+    if (!ephemeralIpv4 || v4Pools.length === 0) return
 
+    // If current pool is valid, keep it
+    if (ephemeralIpv4Pool && v4Pools.some((p) => p.name === ephemeralIpv4Pool)) return
+
+    // Otherwise, try to select default
+    const v4Default = v4Pools.find((p) => p.isDefault)
+    if (v4Default) {
+      ephemeralIpv4PoolField.field.onChange(v4Default.name)
+    } else {
+      // No default: clear the pool (user must select)
+      ephemeralIpv4PoolField.field.onChange('')
+    }
+  }, [ephemeralIpv4, ephemeralIpv4Pool, ephemeralIpv4PoolField, v4Pools])
+
+  // IPv6 pool auto-selection
   useEffect(() => {
-    if (!assignEphemeralIp || compatiblePools.length === 0) return
+    if (!ephemeralIpv6 || v6Pools.length === 0) return
 
-    const currentPoolValid =
-      ephemeralIpPool && compatiblePools.some((p) => p.name === ephemeralIpPool)
-    if (currentPoolValid) return
+    if (ephemeralIpv6Pool && v6Pools.some((p) => p.name === ephemeralIpv6Pool)) return
 
-    const defaultPool = compatiblePools.find((p) => p.isDefault)
-    if (defaultPool) {
-      ephemeralIpPoolField.field.onChange(defaultPool.name)
+    const v6Default = v6Pools.find((p) => p.isDefault)
+    if (v6Default) {
+      ephemeralIpv6PoolField.field.onChange(v6Default.name)
     } else {
-      ephemeralIpPoolField.field.onChange('')
+      ephemeralIpv6PoolField.field.onChange('')
     }
-  }, [assignEphemeralIp, ephemeralIpPool, ephemeralIpPoolField, compatiblePools])
+  }, [ephemeralIpv6, ephemeralIpv6Pool, ephemeralIpv6PoolField, v6Pools])
+
+  // Clean up incompatible ephemeral IP selections when NIC changes
+  useEffect(() => {
+    // When NIC changes, uncheck and clear incompatible options
+    if (ephemeralIpv4 && !compatibleVersions.includes('v4')) {
+      ephemeralIpv4Field.field.onChange(false)
+      ephemeralIpv4PoolField.field.onChange('')
+    }
+    if (ephemeralIpv6 && !compatibleVersions.includes('v6')) {
+      ephemeralIpv6Field.field.onChange(false)
+      ephemeralIpv6PoolField.field.onChange('')
+    }
+  }, [
+    compatibleVersions,
+    ephemeralIpv4,
+    ephemeralIpv4Field,
+    ephemeralIpv4PoolField,
+    ephemeralIpv6,
+    ephemeralIpv6Field,
+    ephemeralIpv6PoolField,
+  ])
 
-  // Track previous ability to attach ephemeral IP to detect transitions
-  const prevCanAttachRef = useRef<boolean | undefined>(undefined)
+  // Track previous canAttach state to detect transitions
+  const prevCanAttachV4Ref = useRef<boolean | undefined>(undefined)
+  const prevCanAttachV6Ref = useRef<boolean | undefined>(undefined)
 
-  // Automatically manage ephemeral IP based on NIC and pool availability
+  // Auto-enable ephemeral IPs when NICs are added that support them
   useEffect(() => {
-    const hasCompatibleNics = compatibleVersions.length > 0
-    const hasPools = compatiblePools.length > 0
-    const canAttach = hasCompatibleNics && hasPools
-    const hasDefaultPool = compatiblePools.some((p) => p.isDefault)
-    const prevCanAttach = prevCanAttachRef.current
-
-    if (!canAttach && assignEphemeralIp) {
-      // Remove ephemeral IP when there are no compatible NICs or pools
-      assignEphemeralIpField.field.onChange(false)
-    } else if (
-      canAttach &&
-      hasDefaultPool &&
-      prevCanAttach === false &&
-      !assignEphemeralIp
-    ) {
-      // Add ephemeral IP when transitioning from unable to able to attach
-      // (prevCanAttach === false means we couldn't attach before, either due to no NICs or no pools)
-      assignEphemeralIpField.field.onChange(true)
+    const prevCanAttachV4 = prevCanAttachV4Ref.current
+    const hasV4Default = v4Pools.some((p) => p.isDefault)
+
+    // Auto-enable v4 when transitioning from unable to able (e.g., NIC added)
+    if (canAttachV4 && hasV4Default && prevCanAttachV4 === false && !ephemeralIpv4) {
+      ephemeralIpv4Field.field.onChange(true)
     }
 
-    prevCanAttachRef.current = canAttach
-  }, [assignEphemeralIp, assignEphemeralIpField, compatiblePools, compatibleVersions])
+    prevCanAttachV4Ref.current = canAttachV4
+  }, [canAttachV4, v4Pools, ephemeralIpv4, ephemeralIpv4Field])
 
-  const ephemeralIpCheckboxState = useMemo(() => {
-    const hasCompatibleNics = compatibleVersions.length > 0
-    const hasCompatiblePools = compatiblePools.length > 0
-    const canAttachEphemeralIp = hasCompatibleNics && hasCompatiblePools
+  useEffect(() => {
+    const prevCanAttachV6 = prevCanAttachV6Ref.current
+    const hasV6Default = v6Pools.some((p) => p.isDefault)
 
-    let disabledReason: React.ReactNode = undefined
-    if (!hasCompatibleNics) {
-      disabledReason = (
-        <>
-          Add a compatible network interface
-          <br />
-          to attach an ephemeral IP address
-        </>
-      )
-    } else if (!hasCompatiblePools) {
-      // TODO: "compatible" not clear enough. also this can happen if there are
-      // no pools at all as well as when there are no pools compatible withe
-      // the NIC stack. We could do a different messages for each.
-      disabledReason = (
-        <>
-          No compatible IP pools available
-          <br />
-          for this network interface type
-        </>
-      )
+    // Auto-enable v6 when transitioning from unable to able (e.g., NIC added)
+    if (canAttachV6 && hasV6Default && prevCanAttachV6 === false && !ephemeralIpv6) {
+      ephemeralIpv6Field.field.onChange(true)
     }
 
-    return { canAttachEphemeralIp, disabledReason }
-  }, [compatibleVersions, compatiblePools])
+    prevCanAttachV6Ref.current = canAttachV6
+  }, [canAttachV6, v6Pools, ephemeralIpv6, ephemeralIpv6Field])
+
+  const noNicMessage = (version: IpVersion) => (
+    <>
+      Add an IP{version} network interface
+      <br />
+      to attach an ephemeral IP{version} address
+    </>
+  )
+  const noPoolMessage = (version: IpVersion) => (
+    <>
+      No IP{version} pools available
+      <br />
+      for this instance’s network interfaces
+    </>
+  )
+
+  const getDisabledReason = (
+    canAttach: boolean,
+    version: IpVersion,
+    compatibleVersions: IpVersion[],
+    pools: UnicastIpPool[]
+  ): React.ReactNode => {
+    if (canAttach) return undefined
+    if (!compatibleVersions.includes(version)) {
+      return noNicMessage(version)
+    }
+    if (pools.length === 0) {
+      return noPoolMessage(version)
+    }
+    return undefined
+  }
+
+  // Calculate disabled reasons for ephemeral IP checkboxes
+  const v4DisabledReason = useMemo(
+    () => getDisabledReason(canAttachV4, 'v4', compatibleVersions, v4Pools),
+    [canAttachV4, compatibleVersions, v4Pools]
+  )
+
+  const v6DisabledReason = useMemo(
+    () => getDisabledReason(canAttachV6, 'v6', compatibleVersions, v6Pools),
+    [canAttachV6, compatibleVersions, v6Pools]
+  )
 
   const closeFloatingIpModal = () => {
     setFloatingIpModalOpen(false)
@@ -922,6 +1009,47 @@ const NetworkingSection = ({
     </>
   )
 
+  // Helper component to reduce duplication between IPv4 and IPv6 ephemeral IP sections
+  const EphemeralIpCheckbox = ({
+    ipVersion,
+    checked,
+    pools,
+    canAttach,
+    disabledReason,
+  }: {
+    ipVersion: IpVersion
+    checked: boolean
+    pools: UnicastIpPool[]
+    canAttach: boolean
+    disabledReason: React.ReactNode
+  }) => {
+    const checkboxName = ipVersion === 'v4' ? 'ephemeralIpv4' : 'ephemeralIpv6'
+    const poolFieldName = ipVersion === 'v4' ? 'ephemeralIpv4Pool' : 'ephemeralIpv6Pool'
+    const displayVersion = `IP${ipVersion}`
+
+    return (
+      <div className="max-w-lg space-y-2">
+        <Wrap when={!!disabledReason} with={<Tooltip content={disabledReason} />}>
+          <span>
+            <CheckboxField control={control} name={checkboxName} disabled={!canAttach}>
+              Allocate and attach ephemeral {displayVersion} address
+            </CheckboxField>
+          </span>
+        </Wrap>
+        {checked && (
+          <div className="ml-6">
+            <IpPoolSelector
+              control={control}
+              poolFieldName={poolFieldName}
+              pools={pools}
+              disabled={isSubmitting}
+            />
+          </div>
+        )}
+      </div>
+    )
+  }
+
   return (
     <>
       {!hasVpcs && (
@@ -947,38 +1075,22 @@ const NetworkingSection = ({
           </TipIcon>
         </h2>
 
-        <Wrap
-          when={!!ephemeralIpCheckboxState.disabledReason}
-          with={<Tooltip content={ephemeralIpCheckboxState.disabledReason} />}
-        >
-          {/* TODO: Wrapping the checkbox in a <span> makes it so the tooltip
-           * shows up when you hover anywhere on the label or checkbox, not
-           * just the checkbox itself. The downside is the placement of the tooltip
-           * is a little weird (I'd like it better if it was anchored to the checkbox),
-           * but I think having it show up on label hover is worth it.
-           */}
-          <span>
-            <Checkbox
-              id="assignEphemeralIp"
-              checked={ephemeralIpCheckboxState.canAttachEphemeralIp && assignEphemeralIp}
-              disabled={!ephemeralIpCheckboxState.canAttachEphemeralIp}
-              onChange={() => {
-                assignEphemeralIpField.field.onChange(!assignEphemeralIp)
-              }}
-            >
-              Allocate and attach an ephemeral IP address
-            </Checkbox>
-          </span>
-        </Wrap>
-        <IpPoolSelector
-          className={assignEphemeralIp ? '' : 'hidden'}
-          control={control}
-          poolFieldName="ephemeralIpPool"
-          pools={compatiblePools}
-          disabled={isSubmitting}
-          compatibleVersions={compatibleVersions}
-          required={assignEphemeralIp}
-        />
+        <div className="flex flex-col gap-2">
+          <EphemeralIpCheckbox
+            ipVersion="v4"
+            checked={ephemeralIpv4}
+            pools={v4Pools}
+            canAttach={canAttachV4}
+            disabledReason={v4DisabledReason}
+          />
+          <EphemeralIpCheckbox
+            ipVersion="v6"
+            checked={ephemeralIpv6}
+            pools={v6Pools}
+            canAttach={canAttachV6}
+            disabledReason={v6DisabledReason}
+          />
+        </div>
       </div>
 
       <div className="flex flex-1 flex-col gap-4">
diff --git a/test/e2e/instance-create.e2e.ts b/test/e2e/instance-create.e2e.ts
index 484b08798..8c36c1943 100644
--- a/test/e2e/instance-create.e2e.ts
+++ b/test/e2e/instance-create.e2e.ts
@@ -64,35 +64,26 @@ test('can create an instance', async ({ page }) => {
   // hostname field should not exist
   await expectNotVisible(page, ['role=textbox[name="Hostname"]'])
 
-  const checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach an ephemeral IP address',
+  const v4Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv4 address',
+  })
+  const v6Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv6 address',
   })
-  const poolDropdown = page.getByLabel('Pool')
-
-  // verify that the ephemeral IP checkbox is checked and pool dropdown is visible
-  await expect(checkbox).toBeChecked()
-  await expect(poolDropdown).toBeVisible()
-
-  // IPv4 default pool should be selected by default
-  await expect(poolDropdown).toContainText('ip-pool-1')
 
-  // click the dropdown to open it and verify options are available
-  await poolDropdown.click()
-  await expect(page.getByRole('option', { name: 'ip-pool-1' })).toBeEnabled()
+  // verify that the IPv4 ephemeral IP checkbox is checked by default
+  await expect(v4Checkbox).toBeChecked()
+  await expect(v6Checkbox).toBeChecked()
 
-  // unchecking the box should hide the pool selector
-  await checkbox.uncheck()
-  await expect(poolDropdown).toBeHidden()
+  // IPv4 default pool should be selected
+  const v4PoolDropdown = page.getByLabel('Pool').first()
+  await expect(v4PoolDropdown).toBeVisible()
+  await expect(v4PoolDropdown).toContainText('ip-pool-1')
 
-  // re-checking the box should re-enable the selector, and other options should be selectable
-  await checkbox.check()
-  // Need to wait for the dropdown to be visible first
-  await expect(poolDropdown).toBeVisible()
-  // Click the dropdown to open it and wait for options to be available
-  await poolDropdown.click()
-  await expect(page.getByRole('option', { name: 'ip-pool-2' })).toBeVisible()
-  // Force click since there might be overlays
-  await page.getByRole('option', { name: 'ip-pool-2' }).click({ force: true })
+  // IPv6 default pool should be selected
+  const v6PoolDropdown = page.getByLabel('Pool').last()
+  await expect(v6PoolDropdown).toBeVisible()
+  await expect(v6PoolDropdown).toContainText('ip-pool-2')
 
   await expect(page.getByRole('radiogroup', { name: 'Network interface' })).toBeVisible()
   await expect(page.getByLabel('User data')).toBeVisible()
@@ -138,15 +129,38 @@ test('can create an instance', async ({ page }) => {
 test('ephemeral pool selection tracks network interface IP version', async ({ page }) => {
   await page.goto('/projects/mock-project/instances-new')
 
-  const poolDropdown = page.getByLabel('Pool')
-  await expect(poolDropdown).toBeVisible()
-  await expect(poolDropdown).toContainText('ip-pool-1')
+  const v4Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv4 address',
+  })
+  const v6Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv6 address',
+  })
 
-  await selectOption(page, page.getByRole('button', { name: 'IPv4 & IPv6' }), 'IPv6')
-  await expect(poolDropdown).toContainText('ip-pool-2')
+  // Default NIC is dual-stack, both checkboxes should be visible, enabled, and checked
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeEnabled()
+  await expect(v4Checkbox).toBeChecked()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeEnabled()
+  await expect(v6Checkbox).toBeChecked()
 
+  // Change to IPv6-only NIC - v4 checkbox should become disabled and unchecked
+  await selectOption(page, page.getByRole('button', { name: 'IPv4 & IPv6' }), 'IPv6')
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeDisabled()
+  await expect(v4Checkbox).not.toBeChecked()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeEnabled()
+  await expect(v6Checkbox).toBeChecked()
+
+  // Change to IPv4-only NIC - v6 checkbox should become disabled and unchecked
   await selectOption(page, page.getByRole('button', { name: 'IPv6' }), 'IPv4')
-  await expect(poolDropdown).toContainText('ip-pool-1')
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeEnabled()
+  await expect(v4Checkbox).toBeChecked()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeDisabled()
+  await expect(v6Checkbox).not.toBeChecked()
 })
 
 test('duplicate instance name produces visible error', async ({ page }) => {
@@ -434,9 +448,14 @@ test('does not attach an ephemeral IP when the checkbox is unchecked', async ({
   await page.getByRole('textbox', { name: 'Name', exact: true }).fill('no-ephemeral-ip')
   await selectAProjectImage(page, 'image-1')
 
+  // Uncheck both ephemeral IP checkboxes
   await page
-    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IP address' })
+    .getByRole('checkbox', { name: 'Allocate and attach ephemeral IPv4 address' })
     .uncheck()
+  await page
+    .getByRole('checkbox', { name: 'Allocate and attach ephemeral IPv6 address' })
+    .uncheck()
+
   await page.getByRole('button', { name: 'Create instance' }).click()
   await expect(page).toHaveURL('/projects/mock-project/instances/no-ephemeral-ip/storage')
   await expect(page.getByText('External IPs—')).toBeVisible()
@@ -846,27 +865,28 @@ test('create instance with custom IPv4-only NIC constrains ephemeral IP to IPv4'
     nicTable.getByRole('cell', { name: 'my-ipv4-nic', exact: true })
   ).toBeVisible()
 
-  // Verify that ephemeral IP options are constrained to IPv4 only
-  const ephemeralCheckbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach an ephemeral IP address',
+  // Verify that only IPv4 ephemeral IP is enabled
+  const v4Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv4 address',
+  })
+  const v6Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv6 address',
   })
-  await expect(ephemeralCheckbox).toBeVisible()
-
-  // Pool dropdown should be visible
-  const poolDropdown = page.getByLabel('Pool')
-  await expect(poolDropdown).toBeVisible()
 
-  // IPv4 default pool should be selected by default
-  await expect(poolDropdown).toContainText('ip-pool-1')
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeEnabled()
+  await expect(v4Checkbox).toBeChecked()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeDisabled()
 
-  // Open dropdown to check available options - IPv6 pools should be filtered out
-  await poolDropdown.click()
+  // IPv4 pool dropdown should be visible with default selected
+  const v4PoolDropdown = page.getByLabel('Pool')
+  await expect(v4PoolDropdown).toBeVisible()
+  await expect(v4PoolDropdown).toContainText('ip-pool-1')
 
-  // ip-pool-1 is IPv4, should appear
+  // Open dropdown to check available options - only IPv4 pools should appear
+  await v4PoolDropdown.click()
   await expect(page.getByRole('option', { name: 'ip-pool-1' })).toBeVisible()
-
-  // ip-pool-2 is IPv6, should NOT appear
-  await expect(page.getByRole('option', { name: 'ip-pool-2' })).toBeHidden()
 })
 
 test('create instance with custom IPv6-only NIC constrains ephemeral IP to IPv6', async ({
@@ -907,27 +927,28 @@ test('create instance with custom IPv6-only NIC constrains ephemeral IP to IPv6'
     nicTable.getByRole('cell', { name: 'my-ipv6-nic', exact: true })
   ).toBeVisible()
 
-  // Verify that ephemeral IP options are constrained to IPv6 only
-  const ephemeralCheckbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach an ephemeral IP address',
+  // Verify that only IPv6 ephemeral IP is enabled
+  const v4Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv4 address',
+  })
+  const v6Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv6 address',
   })
-  await expect(ephemeralCheckbox).toBeVisible()
-
-  // Pool dropdown should be visible
-  const poolDropdown = page.getByLabel('Pool')
-  await expect(poolDropdown).toBeVisible()
 
-  // IPv6 default pool should be selected by default
-  await expect(poolDropdown).toContainText('ip-pool-2')
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeDisabled()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeEnabled()
+  await expect(v6Checkbox).toBeChecked()
 
-  // Open dropdown to check available options - IPv4 pools should be filtered out
-  await poolDropdown.click()
+  // IPv6 pool dropdown should be visible with default selected
+  const v6PoolDropdown = page.getByLabel('Pool')
+  await expect(v6PoolDropdown).toBeVisible()
+  await expect(v6PoolDropdown).toContainText('ip-pool-2')
 
-  // ip-pool-2 is IPv6, should appear
+  // Open dropdown to check available options - only IPv6 pools should appear
+  await v6PoolDropdown.click()
   await expect(page.getByRole('option', { name: 'ip-pool-2' })).toBeVisible()
-
-  // ip-pool-1 is IPv4, should NOT appear
-  await expect(page.getByRole('option', { name: 'ip-pool-1' })).toBeHidden()
 })
 
 test('create instance with custom dual-stack NIC allows both IPv4 and IPv6 ephemeral IPs', async ({
@@ -968,25 +989,44 @@ test('create instance with custom dual-stack NIC allows both IPv4 and IPv6 ephem
     nicTable.getByRole('cell', { name: 'my-dual-stack-nic', exact: true })
   ).toBeVisible()
 
-  // Verify that both IPv4 and IPv6 ephemeral IP options are available
-  const ephemeralCheckbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach an ephemeral IP address',
+  // Verify that both IPv4 and IPv6 ephemeral IP checkboxes are available
+  const v4Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv4 address',
+  })
+  const v6Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv6 address',
   })
-  await expect(ephemeralCheckbox).toBeVisible()
 
-  // Pool dropdown should be visible
-  const poolDropdown = page.getByLabel('Pool')
-  await expect(poolDropdown).toBeVisible()
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeChecked()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeChecked()
 
-  // IPv4 default pool should be selected by default (first in sorted order)
-  await expect(poolDropdown).toContainText('ip-pool-1')
+  // Both pool dropdowns should be visible with defaults selected
+  const poolDropdowns = page.getByLabel('Pool')
+  await expect(poolDropdowns.first()).toBeVisible()
+  await expect(poolDropdowns.first()).toContainText('ip-pool-1')
+  await expect(poolDropdowns.last()).toBeVisible()
+  await expect(poolDropdowns.last()).toContainText('ip-pool-2')
+
+  // Create the instance
+  await page.getByRole('button', { name: 'Create instance' }).click()
 
-  // Open dropdown to check available options - both IPv4 and IPv6 pools should be available
-  await poolDropdown.click()
+  // Should navigate to instance page
+  await expect(page).toHaveURL(`/projects/mock-project/instances/${instanceName}/storage`)
 
-  // Both pools should appear
-  await expect(page.getByRole('option', { name: 'ip-pool-1' })).toBeVisible()
-  await expect(page.getByRole('option', { name: 'ip-pool-2' })).toBeVisible()
+  // Navigate to networking tab
+  await page.getByRole('tab', { name: 'Networking' }).click()
+
+  // Verify two ephemeral IP rows exist in the external IPs table
+  const externalIpsTable = page.getByRole('table', { name: /external ips/i })
+  const ephemeralRows = externalIpsTable.getByRole('row').filter({ hasText: 'ephemeral' })
+
+  await expect(ephemeralRows).toHaveCount(2)
+
+  // Verify one is IPv4 and one is IPv6
+  await expect(externalIpsTable.getByText('IPv4')).toBeVisible()
+  await expect(externalIpsTable.getByText('IPv6')).toBeVisible()
 })
 
 test('ephemeral IP checkbox disabled when no NICs configured', async ({ page }) => {
@@ -998,8 +1038,11 @@ test('ephemeral IP checkbox disabled when no NICs configured', async ({ page })
 
   // Configure networking
 
-  const ephemeralCheckbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach an ephemeral IP address',
+  const v4Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv4 address',
+  })
+  const v6Checkbox = page.getByRole('checkbox', {
+    name: 'Allocate and attach ephemeral IPv6 address',
   })
   const defaultRadio = page.getByRole('radio', {
     name: 'Default',
@@ -1008,25 +1051,32 @@ test('ephemeral IP checkbox disabled when no NICs configured', async ({ page })
   const noneRadio = page.getByRole('radio', { name: 'None', exact: true })
   const customRadio = page.getByRole('radio', { name: 'Custom', exact: true }).first()
 
-  // Verify default state: "Default" is checked and Ephemeral IP checkbox is checked
+  // Verify default state: "Default" is checked and both ephemeral IP checkboxes are visible, enabled, and checked
   await expect(defaultRadio).toBeChecked()
-  await expect(ephemeralCheckbox).toBeChecked()
-  await expect(ephemeralCheckbox).toBeEnabled()
-
-  // Select "None" radio → verify Ephemeral IP checkbox is unchecked and disabled
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeEnabled()
+  await expect(v4Checkbox).toBeChecked()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeEnabled()
+  await expect(v6Checkbox).toBeChecked()
+
+  // Select "None" radio → verify ephemeral IP checkboxes are disabled and unchecked
   await noneRadio.click()
-  await expect(ephemeralCheckbox).not.toBeChecked()
-  await expect(ephemeralCheckbox).toBeDisabled()
-
-  // Hover over the disabled checkbox to verify tooltip appears
-  await ephemeralCheckbox.hover()
-  await expect(page.getByText('Add a compatible network interface')).toBeVisible()
-  await expect(page.getByText('to attach an ephemeral IP address')).toBeVisible()
-
-  // Select "Custom" radio → verify Ephemeral IP checkbox is still unchecked and disabled
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeDisabled()
+  await expect(v4Checkbox).not.toBeChecked()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeDisabled()
+  await expect(v6Checkbox).not.toBeChecked()
+
+  // Select "Custom" radio → verify ephemeral IP checkboxes are still disabled and unchecked
   await customRadio.click()
-  await expect(ephemeralCheckbox).not.toBeChecked()
-  await expect(ephemeralCheckbox).toBeDisabled()
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeDisabled()
+  await expect(v4Checkbox).not.toBeChecked()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeDisabled()
+  await expect(v6Checkbox).not.toBeChecked()
 
   // Click "Add network interface" button to open modal
   await page.getByRole('button', { name: 'Add network interface' }).click()
@@ -1054,9 +1104,12 @@ test('ephemeral IP checkbox disabled when no NICs configured', async ({ page })
     nicTable.getByRole('cell', { name: 'new-v4-nic', exact: true })
   ).toBeVisible()
 
-  // Verify Ephemeral IP checkbox is now checked and enabled
-  await expect(ephemeralCheckbox).toBeChecked()
-  await expect(ephemeralCheckbox).toBeEnabled()
+  // Verify IPv4 ephemeral IP checkbox is now enabled and checked (auto-enabled when NIC added)
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeEnabled()
+  await expect(v4Checkbox).toBeChecked()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeDisabled()
 
   // Delete the NIC using the remove button
   await page.getByRole('button', { name: 'remove network interface new-v4-nic' }).click()
@@ -1064,9 +1117,13 @@ test('ephemeral IP checkbox disabled when no NICs configured', async ({ page })
   // Verify the NIC is no longer in the table
   await expect(nicTable.getByRole('cell', { name: 'new-v4-nic', exact: true })).toBeHidden()
 
-  // Verify Ephemeral IP checkbox is once again unchecked and disabled
-  await expect(ephemeralCheckbox).not.toBeChecked()
-  await expect(ephemeralCheckbox).toBeDisabled()
+  // Verify ephemeral IP checkboxes are disabled and unchecked again
+  await expect(v4Checkbox).toBeVisible()
+  await expect(v4Checkbox).toBeDisabled()
+  await expect(v4Checkbox).not.toBeChecked()
+  await expect(v6Checkbox).toBeVisible()
+  await expect(v6Checkbox).toBeDisabled()
+  await expect(v6Checkbox).not.toBeChecked()
 })
 
 test('network interface options disabled when no VPCs exist', async ({ page }) => {
diff --git a/test/e2e/ip-pool-silo-config.e2e.ts b/test/e2e/ip-pool-silo-config.e2e.ts
index 6d68085f7..4118b7339 100644
--- a/test/e2e/ip-pool-silo-config.e2e.ts
+++ b/test/e2e/ip-pool-silo-config.e2e.ts
@@ -37,24 +37,29 @@ test.describe('IP pool configuration: myriad silo (v4-only default)', () => {
     await page.getByPlaceholder('Select a silo image', { exact: true }).click()
     await page.getByRole('option', { name: 'ubuntu-22-04' }).click()
 
-    // Verify ephemeral IP checkbox is checked by default
-    const ephemeralCheckbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach an ephemeral IP address',
+    // Verify IPv4 ephemeral IP checkbox is checked by default
+    const v4Checkbox = page.getByRole('checkbox', {
+      name: 'Allocate and attach ephemeral IPv4 address',
+    })
+    const v6Checkbox = page.getByRole('checkbox', {
+      name: 'Allocate and attach ephemeral IPv6 address',
     })
-    await expect(ephemeralCheckbox).toBeChecked()
 
-    // Pool dropdown should be visible with IPv4 pool preselected
-    const poolDropdown = page.getByLabel('Pool')
-    await expect(poolDropdown).toBeVisible()
-    await expect(poolDropdown).toContainText('ip-pool-1')
+    await expect(v4Checkbox).toBeVisible()
+    await expect(v4Checkbox).toBeChecked()
+    // v6 checkbox should be visible but not checked (no v6 default in myriad silo)
+    await expect(v6Checkbox).toBeVisible()
+    await expect(v6Checkbox).not.toBeChecked()
+
+    // IPv4 pool dropdown should be visible with default pool preselected
+    const v4PoolDropdown = page.getByLabel('Pool')
+    await expect(v4PoolDropdown).toBeVisible()
+    await expect(v4PoolDropdown).toContainText('ip-pool-1')
 
     // Open dropdown to verify available options (only v4 pools should be available)
-    await poolDropdown.click()
+    await v4PoolDropdown.click()
     await expect(page.getByRole('option', { name: 'ip-pool-1' })).toBeVisible()
     await expect(page.getByRole('option', { name: 'ip-pool-3' })).toBeVisible()
-    // IPv6 pools should not be available in this silo
-    await expect(page.getByRole('option', { name: 'ip-pool-2' })).toBeHidden()
-    await expect(page.getByRole('option', { name: 'ip-pool-4' })).toBeHidden()
   })
 
   test('floating IP create form shows IPv4 default pool preselected', async ({
@@ -81,10 +86,10 @@ test.describe('IP pool configuration: myriad silo (v4-only default)', () => {
     await page.getByRole('option', { name: 'ubuntu-22-04' }).click()
 
     // Verify ephemeral IP defaults
-    const ephemeralCheckbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach an ephemeral IP address',
+    const v4Checkbox = page.getByRole('checkbox', {
+      name: 'Allocate and attach ephemeral IPv4 address',
     })
-    await expect(ephemeralCheckbox).toBeChecked()
+    await expect(v4Checkbox).toBeChecked()
     await expect(page.getByLabel('Pool')).toContainText('ip-pool-1')
 
     // Create instance
@@ -209,24 +214,29 @@ test.describe('IP pool configuration: thrax silo (v6-only default)', () => {
     await page.getByPlaceholder('Select a silo image', { exact: true }).click()
     await page.getByRole('option', { name: 'ubuntu-22-04' }).click()
 
-    // Verify ephemeral IP checkbox is checked by default
-    const ephemeralCheckbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach an ephemeral IP address',
+    // Verify IPv6 ephemeral IP checkbox is checked by default
+    const v4Checkbox = page.getByRole('checkbox', {
+      name: 'Allocate and attach ephemeral IPv4 address',
+    })
+    const v6Checkbox = page.getByRole('checkbox', {
+      name: 'Allocate and attach ephemeral IPv6 address',
     })
-    await expect(ephemeralCheckbox).toBeChecked()
 
-    // Pool dropdown should be visible with IPv6 pool preselected
-    const poolDropdown = page.getByLabel('Pool')
-    await expect(poolDropdown).toBeVisible()
-    await expect(poolDropdown).toContainText('ip-pool-2')
+    // v4 checkbox should be visible but not checked (no v4 default in thrax silo)
+    await expect(v4Checkbox).toBeVisible()
+    await expect(v4Checkbox).not.toBeChecked()
+    await expect(v6Checkbox).toBeVisible()
+    await expect(v6Checkbox).toBeChecked()
+
+    // IPv6 pool dropdown should be visible with default pool preselected
+    const v6PoolDropdown = page.getByLabel('Pool')
+    await expect(v6PoolDropdown).toBeVisible()
+    await expect(v6PoolDropdown).toContainText('ip-pool-2')
 
     // Open dropdown to verify available options (only v6 pools should be available)
-    await poolDropdown.click()
+    await v6PoolDropdown.click()
     await expect(page.getByRole('option', { name: 'ip-pool-2' })).toBeVisible()
     await expect(page.getByRole('option', { name: 'ip-pool-4' })).toBeVisible()
-    // IPv4 pools should not be available in this silo
-    await expect(page.getByRole('option', { name: 'ip-pool-1' })).toBeHidden()
-    await expect(page.getByRole('option', { name: 'ip-pool-3' })).toBeHidden()
   })
 
   test('floating IP create form shows IPv6 default pool preselected', async ({
@@ -255,26 +265,32 @@ test.describe('IP pool configuration: pelerines silo (no defaults)', () => {
     await page.getByPlaceholder('Select a silo image', { exact: true }).click()
     await page.getByRole('option', { name: 'ubuntu-22-04' }).click()
 
-    // Verify ephemeral IP checkbox is not checked by default
-    const ephemeralCheckbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach an ephemeral IP address',
+    // Verify ephemeral IP checkboxes are not checked by default (no defaults in pelerines silo)
+    const v4Checkbox = page.getByRole('checkbox', {
+      name: 'Allocate and attach ephemeral IPv4 address',
+    })
+    const v6Checkbox = page.getByRole('checkbox', {
+      name: 'Allocate and attach ephemeral IPv6 address',
     })
-    await expect(ephemeralCheckbox).not.toBeChecked()
 
-    // Pool dropdown should not be shown unless ephemeral IP is enabled.
-    const poolDropdown = page.getByLabel('Pool')
-    await expect(poolDropdown).toBeHidden()
+    await expect(v4Checkbox).toBeVisible()
+    await expect(v4Checkbox).not.toBeChecked()
+    await expect(v6Checkbox).toBeVisible()
+    await expect(v6Checkbox).not.toBeChecked()
+
+    // Pool dropdowns should not be shown unless ephemeral IPs are enabled
+    const poolDropdowns = page.getByLabel('Pool')
+    await expect(poolDropdowns.first()).toBeHidden()
 
-    // Enabling ephemeral IP should allow selecting from available pools.
-    await ephemeralCheckbox.click()
-    await expect(ephemeralCheckbox).toBeChecked()
-    await expect(poolDropdown).toBeVisible()
+    // Enabling IPv4 ephemeral IP should show pool dropdown
+    await v4Checkbox.click()
+    await expect(v4Checkbox).toBeChecked()
+    await expect(poolDropdowns.first()).toBeVisible()
 
     // Open dropdown to verify available options
-    await poolDropdown.click()
+    await poolDropdowns.first().click()
     // Both pools are linked to this silo but neither is default
     await expect(page.getByRole('option', { name: 'ip-pool-1' })).toBeVisible()
-    await expect(page.getByRole('option', { name: 'ip-pool-2' })).toBeVisible()
   })
 
   test('floating IP create form handles missing default pool gracefully', async ({
@@ -307,19 +323,17 @@ test.describe('IP pool configuration: no-pools silo (no IP pools)', () => {
     const defaultRadio = page.getByRole('radio', { name: 'Default' })
     await expect(defaultRadio).toBeChecked()
 
-    const ephemeralCheckbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach an ephemeral IP address',
+    // When there are no pools, both checkboxes should be visible but disabled
+    const v4Checkbox = page.getByRole('checkbox', {
+      name: 'Allocate and attach ephemeral IPv4 address',
     })
-    await expect(ephemeralCheckbox).not.toBeChecked()
-    await expect(ephemeralCheckbox).toBeDisabled()
-
-    await ephemeralCheckbox.hover()
-    await expect(
-      page.getByRole('tooltip').filter({ hasText: /No compatible IP pools available/ })
-    ).toBeVisible()
-
-    const poolDropdown = page.getByLabel('Pool')
-    await expect(poolDropdown).toBeHidden()
+    const v6Checkbox = page.getByRole('checkbox', {
+      name: 'Allocate and attach ephemeral IPv6 address',
+    })
+    await expect(v4Checkbox).toBeVisible()
+    await expect(v4Checkbox).toBeDisabled()
+    await expect(v6Checkbox).toBeVisible()
+    await expect(v6Checkbox).toBeDisabled()
 
     const attachFloatingIpButton = page.getByRole('button', { name: 'Attach floating IP' })
     const dialog = page.getByRole('dialog')

From acd97a4ae4ec638d867f7f491a8d80b80eaa6613 Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Fri, 6 Feb 2026 16:47:17 -0800
Subject: [PATCH 02/11] Update copy; smarter handling of compatible defaults

---
 app/forms/instance-create.tsx       | 26 +++++++++++++++++---------
 test/e2e/instance-create.e2e.ts     | 28 ++++++++++++++--------------
 test/e2e/ip-pool-silo-config.e2e.ts | 18 +++++++++---------
 3 files changed, 40 insertions(+), 32 deletions(-)

diff --git a/app/forms/instance-create.tsx b/app/forms/instance-create.tsx
index ea6cafa57..beaaeb11d 100644
--- a/app/forms/instance-create.tsx
+++ b/app/forms/instance-create.tsx
@@ -322,8 +322,15 @@ export default function CreateInstanceForm() {
     .filter((p) => p.isDefault)
 
   // Compute defaults for dual ephemeral IP support
-  const hasV4Default = compatibleDefaultPools.some((p) => p.ipVersion === 'v4')
-  const hasV6Default = compatibleDefaultPools.some((p) => p.ipVersion === 'v6')
+  // Check ALL default pools in silo (not just compatible ones) to determine
+  // if ipVersion is needed in auto selectors (API requires it when multiple defaults exist)
+  const allDefaultPools = unicastPools.filter((p) => p.isDefault)
+  const hasV4Default = allDefaultPools.some((p) => p.ipVersion === 'v4')
+  const hasV6Default = allDefaultPools.some((p) => p.ipVersion === 'v6')
+
+  // Check compatible defaults for checkbox initialization
+  const hasCompatibleV4Default = compatibleDefaultPools.some((p) => p.ipVersion === 'v4')
+  const hasCompatibleV6Default = compatibleDefaultPools.some((p) => p.ipVersion === 'v6')
 
   const defaultValues: InstanceCreateInput = {
     ...baseDefaultValues,
@@ -331,9 +338,9 @@ export default function CreateInstanceForm() {
     bootDiskSourceType: defaultSource,
     sshPublicKeys: allKeys,
     bootDiskSize: diskSizeNearest10(defaultImage?.size / GiB),
-    ephemeralIpv4: hasV4Default && defaultCompatibleVersions.includes('v4'),
+    ephemeralIpv4: hasCompatibleV4Default && defaultCompatibleVersions.includes('v4'),
     ephemeralIpv4Pool: '',
-    ephemeralIpv6: hasV6Default && defaultCompatibleVersions.includes('v6'),
+    ephemeralIpv6: hasCompatibleV6Default && defaultCompatibleVersions.includes('v6'),
     ephemeralIpv6Pool: '',
     floatingIps: [],
   }
@@ -444,8 +451,9 @@ export default function CreateInstanceForm() {
           const bootDisk = getBootDiskAttachment(values, allImages)
 
           // Construct external IPs: ephemeral IPs first (v4 before v6), then floating IPs
-          // Only include ipVersion when requesting BOTH ephemeral IPs with auto selectors
-          const requestingBothEphemeralIps = values.ephemeralIpv4 && values.ephemeralIpv6
+          // Include ipVersion when using auto selectors IF multiple default pools exist
+          // (API requires ipVersion to disambiguate when both v4 and v6 defaults exist)
+          const multipleDefaultPools = hasV4Default && hasV6Default
           const externalIps: ExternalIpCreate[] = [
             // v4 ephemeral if enabled (order: v4 before v6)
             ...(values.ephemeralIpv4
@@ -454,7 +462,7 @@ export default function CreateInstanceForm() {
                     type: 'ephemeral' as const,
                     poolSelector: values.ephemeralIpv4Pool
                       ? { type: 'explicit' as const, pool: values.ephemeralIpv4Pool }
-                      : requestingBothEphemeralIps
+                      : multipleDefaultPools
                         ? { type: 'auto' as const, ipVersion: 'v4' as const }
                         : { type: 'auto' as const },
                   },
@@ -467,7 +475,7 @@ export default function CreateInstanceForm() {
                     type: 'ephemeral' as const,
                     poolSelector: values.ephemeralIpv6Pool
                       ? { type: 'explicit' as const, pool: values.ephemeralIpv6Pool }
-                      : requestingBothEphemeralIps
+                      : multipleDefaultPools
                         ? { type: 'auto' as const, ipVersion: 'v6' as const }
                         : { type: 'auto' as const },
                   },
@@ -1032,7 +1040,7 @@ const NetworkingSection = ({
         <Wrap when={!!disabledReason} with={<Tooltip content={disabledReason} />}>
           <span>
             <CheckboxField control={control} name={checkboxName} disabled={!canAttach}>
-              Allocate and attach ephemeral {displayVersion} address
+              Allocate and attach an ephemeral {displayVersion} address
             </CheckboxField>
           </span>
         </Wrap>
diff --git a/test/e2e/instance-create.e2e.ts b/test/e2e/instance-create.e2e.ts
index 8c36c1943..7e21b58c2 100644
--- a/test/e2e/instance-create.e2e.ts
+++ b/test/e2e/instance-create.e2e.ts
@@ -65,10 +65,10 @@ test('can create an instance', async ({ page }) => {
   await expectNotVisible(page, ['role=textbox[name="Hostname"]'])
 
   const v4Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv4 address',
+    name: 'Allocate and attach an ephemeral IPv4 address',
   })
   const v6Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv6 address',
+    name: 'Allocate and attach an ephemeral IPv6 address',
   })
 
   // verify that the IPv4 ephemeral IP checkbox is checked by default
@@ -130,10 +130,10 @@ test('ephemeral pool selection tracks network interface IP version', async ({ pa
   await page.goto('/projects/mock-project/instances-new')
 
   const v4Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv4 address',
+    name: 'Allocate and attach an ephemeral IPv4 address',
   })
   const v6Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv6 address',
+    name: 'Allocate and attach an ephemeral IPv6 address',
   })
 
   // Default NIC is dual-stack, both checkboxes should be visible, enabled, and checked
@@ -450,10 +450,10 @@ test('does not attach an ephemeral IP when the checkbox is unchecked', async ({
 
   // Uncheck both ephemeral IP checkboxes
   await page
-    .getByRole('checkbox', { name: 'Allocate and attach ephemeral IPv4 address' })
+    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IPv4 address' })
     .uncheck()
   await page
-    .getByRole('checkbox', { name: 'Allocate and attach ephemeral IPv6 address' })
+    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IPv6 address' })
     .uncheck()
 
   await page.getByRole('button', { name: 'Create instance' }).click()
@@ -867,10 +867,10 @@ test('create instance with custom IPv4-only NIC constrains ephemeral IP to IPv4'
 
   // Verify that only IPv4 ephemeral IP is enabled
   const v4Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv4 address',
+    name: 'Allocate and attach an ephemeral IPv4 address',
   })
   const v6Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv6 address',
+    name: 'Allocate and attach an ephemeral IPv6 address',
   })
 
   await expect(v4Checkbox).toBeVisible()
@@ -929,10 +929,10 @@ test('create instance with custom IPv6-only NIC constrains ephemeral IP to IPv6'
 
   // Verify that only IPv6 ephemeral IP is enabled
   const v4Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv4 address',
+    name: 'Allocate and attach an ephemeral IPv4 address',
   })
   const v6Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv6 address',
+    name: 'Allocate and attach an ephemeral IPv6 address',
   })
 
   await expect(v4Checkbox).toBeVisible()
@@ -991,10 +991,10 @@ test('create instance with custom dual-stack NIC allows both IPv4 and IPv6 ephem
 
   // Verify that both IPv4 and IPv6 ephemeral IP checkboxes are available
   const v4Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv4 address',
+    name: 'Allocate and attach an ephemeral IPv4 address',
   })
   const v6Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv6 address',
+    name: 'Allocate and attach an ephemeral IPv6 address',
   })
 
   await expect(v4Checkbox).toBeVisible()
@@ -1039,10 +1039,10 @@ test('ephemeral IP checkbox disabled when no NICs configured', async ({ page })
   // Configure networking
 
   const v4Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv4 address',
+    name: 'Allocate and attach an ephemeral IPv4 address',
   })
   const v6Checkbox = page.getByRole('checkbox', {
-    name: 'Allocate and attach ephemeral IPv6 address',
+    name: 'Allocate and attach an ephemeral IPv6 address',
   })
   const defaultRadio = page.getByRole('radio', {
     name: 'Default',
diff --git a/test/e2e/ip-pool-silo-config.e2e.ts b/test/e2e/ip-pool-silo-config.e2e.ts
index 4118b7339..f016b33db 100644
--- a/test/e2e/ip-pool-silo-config.e2e.ts
+++ b/test/e2e/ip-pool-silo-config.e2e.ts
@@ -39,10 +39,10 @@ test.describe('IP pool configuration: myriad silo (v4-only default)', () => {
 
     // Verify IPv4 ephemeral IP checkbox is checked by default
     const v4Checkbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach ephemeral IPv4 address',
+      name: 'Allocate and attach an ephemeral IPv4 address',
     })
     const v6Checkbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach ephemeral IPv6 address',
+      name: 'Allocate and attach an ephemeral IPv6 address',
     })
 
     await expect(v4Checkbox).toBeVisible()
@@ -87,7 +87,7 @@ test.describe('IP pool configuration: myriad silo (v4-only default)', () => {
 
     // Verify ephemeral IP defaults
     const v4Checkbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach ephemeral IPv4 address',
+      name: 'Allocate and attach an ephemeral IPv4 address',
     })
     await expect(v4Checkbox).toBeChecked()
     await expect(page.getByLabel('Pool')).toContainText('ip-pool-1')
@@ -216,10 +216,10 @@ test.describe('IP pool configuration: thrax silo (v6-only default)', () => {
 
     // Verify IPv6 ephemeral IP checkbox is checked by default
     const v4Checkbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach ephemeral IPv4 address',
+      name: 'Allocate and attach an ephemeral IPv4 address',
     })
     const v6Checkbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach ephemeral IPv6 address',
+      name: 'Allocate and attach an ephemeral IPv6 address',
     })
 
     // v4 checkbox should be visible but not checked (no v4 default in thrax silo)
@@ -267,10 +267,10 @@ test.describe('IP pool configuration: pelerines silo (no defaults)', () => {
 
     // Verify ephemeral IP checkboxes are not checked by default (no defaults in pelerines silo)
     const v4Checkbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach ephemeral IPv4 address',
+      name: 'Allocate and attach an ephemeral IPv4 address',
     })
     const v6Checkbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach ephemeral IPv6 address',
+      name: 'Allocate and attach an ephemeral IPv6 address',
     })
 
     await expect(v4Checkbox).toBeVisible()
@@ -325,10 +325,10 @@ test.describe('IP pool configuration: no-pools silo (no IP pools)', () => {
 
     // When there are no pools, both checkboxes should be visible but disabled
     const v4Checkbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach ephemeral IPv4 address',
+      name: 'Allocate and attach an ephemeral IPv4 address',
     })
     const v6Checkbox = page.getByRole('checkbox', {
-      name: 'Allocate and attach ephemeral IPv6 address',
+      name: 'Allocate and attach an ephemeral IPv6 address',
     })
     await expect(v4Checkbox).toBeVisible()
     await expect(v4Checkbox).toBeDisabled()

From badd541575dba0c325d96ae88a750e906b622999 Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Fri, 6 Feb 2026 17:11:48 -0800
Subject: [PATCH 03/11] refactor/bugfix

---
 app/forms/instance-create.tsx       | 22 +++++-----------------
 test/e2e/instance-networking.e2e.ts |  8 ++++----
 2 files changed, 9 insertions(+), 21 deletions(-)

diff --git a/app/forms/instance-create.tsx b/app/forms/instance-create.tsx
index beaaeb11d..c1a0dcfac 100644
--- a/app/forms/instance-create.tsx
+++ b/app/forms/instance-create.tsx
@@ -321,14 +321,7 @@ export default function CreateInstanceForm() {
     .filter(poolHasIpVersion(defaultCompatibleVersions))
     .filter((p) => p.isDefault)
 
-  // Compute defaults for dual ephemeral IP support
-  // Check ALL default pools in silo (not just compatible ones) to determine
-  // if ipVersion is needed in auto selectors (API requires it when multiple defaults exist)
-  const allDefaultPools = unicastPools.filter((p) => p.isDefault)
-  const hasV4Default = allDefaultPools.some((p) => p.ipVersion === 'v4')
-  const hasV6Default = allDefaultPools.some((p) => p.ipVersion === 'v6')
-
-  // Check compatible defaults for checkbox initialization
+  // Check for compatible defaults to determine checkbox initialization
   const hasCompatibleV4Default = compatibleDefaultPools.some((p) => p.ipVersion === 'v4')
   const hasCompatibleV6Default = compatibleDefaultPools.some((p) => p.ipVersion === 'v6')
 
@@ -451,9 +444,8 @@ export default function CreateInstanceForm() {
           const bootDisk = getBootDiskAttachment(values, allImages)
 
           // Construct external IPs: ephemeral IPs first (v4 before v6), then floating IPs
-          // Include ipVersion when using auto selectors IF multiple default pools exist
-          // (API requires ipVersion to disambiguate when both v4 and v6 defaults exist)
-          const multipleDefaultPools = hasV4Default && hasV6Default
+          // Always include ipVersion in auto selectors to match user intent and satisfy
+          // API requirements (dual-stack requests MUST specify ipVersion on each)
           const externalIps: ExternalIpCreate[] = [
             // v4 ephemeral if enabled (order: v4 before v6)
             ...(values.ephemeralIpv4
@@ -462,9 +454,7 @@ export default function CreateInstanceForm() {
                     type: 'ephemeral' as const,
                     poolSelector: values.ephemeralIpv4Pool
                       ? { type: 'explicit' as const, pool: values.ephemeralIpv4Pool }
-                      : multipleDefaultPools
-                        ? { type: 'auto' as const, ipVersion: 'v4' as const }
-                        : { type: 'auto' as const },
+                      : { type: 'auto' as const, ipVersion: 'v4' as const },
                   },
                 ]
               : []),
@@ -475,9 +465,7 @@ export default function CreateInstanceForm() {
                     type: 'ephemeral' as const,
                     poolSelector: values.ephemeralIpv6Pool
                       ? { type: 'explicit' as const, pool: values.ephemeralIpv6Pool }
-                      : multipleDefaultPools
-                        ? { type: 'auto' as const, ipVersion: 'v6' as const }
-                        : { type: 'auto' as const },
+                      : { type: 'auto' as const, ipVersion: 'v6' as const },
                   },
                 ]
               : []),
diff --git a/test/e2e/instance-networking.e2e.ts b/test/e2e/instance-networking.e2e.ts
index ade1a66db..1b70ac192 100644
--- a/test/e2e/instance-networking.e2e.ts
+++ b/test/e2e/instance-networking.e2e.ts
@@ -344,7 +344,7 @@ test('IPv4-only instance cannot attach IPv6 ephemeral IP', async ({ page }) => {
 
   // Don't attach ephemeral IP at creation
   await page
-    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IP address' })
+    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IPv4 address' })
     .uncheck()
 
   // Create instance
@@ -399,7 +399,7 @@ test('IPv6-only instance cannot attach IPv4 ephemeral IP', async ({ page }) => {
 
   // Don't attach ephemeral IP at creation
   await page
-    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IP address' })
+    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IPv6 address' })
     .uncheck()
 
   // Create instance
@@ -454,7 +454,7 @@ test('IPv4-only instance can attach IPv4 ephemeral IP', async ({ page }) => {
 
   // Don't attach ephemeral IP at creation
   await page
-    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IP address' })
+    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IPv4 address' })
     .uncheck()
 
   // Create instance
@@ -503,7 +503,7 @@ test('IPv6-only instance can attach IPv6 ephemeral IP', async ({ page }) => {
 
   // Don't attach ephemeral IP at creation
   await page
-    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IP address' })
+    .getByRole('checkbox', { name: 'Allocate and attach an ephemeral IPv6 address' })
     .uncheck()
 
   // Create instance

From b1cbf124057e175dea281379a0779ae4084aaebc Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Fri, 6 Feb 2026 20:57:11 -0800
Subject: [PATCH 04/11] remove useEffects

---
 app/components/form/fields/IpPoolSelector.tsx |  3 ++
 app/forms/instance-create.tsx                 | 51 ++++---------------
 2 files changed, 13 insertions(+), 41 deletions(-)

diff --git a/app/components/form/fields/IpPoolSelector.tsx b/app/components/form/fields/IpPoolSelector.tsx
index f18e42965..f677b1c62 100644
--- a/app/components/form/fields/IpPoolSelector.tsx
+++ b/app/components/form/fields/IpPoolSelector.tsx
@@ -54,6 +54,7 @@ type IpPoolSelectorProps<
   /** Compatible IP versions based on network interface type */
   compatibleVersions?: IpVersion[]
   required?: boolean
+  hideOptionalTag?: boolean
 }
 
 export function IpPoolSelector<
@@ -67,6 +68,7 @@ export function IpPoolSelector<
   disabled = false,
   compatibleVersions = ALL_IP_VERSIONS,
   required = true,
+  hideOptionalTag = false,
 }: IpPoolSelectorProps<TFieldValues, TName>) {
   // Note: pools are already filtered by poolType before being passed to this component
   const sortedPools = useMemo(() => {
@@ -90,6 +92,7 @@ export function IpPoolSelector<
         placeholder="Select a pool"
         required={required}
         disabled={disabled}
+        hideOptionalTag={hideOptionalTag}
       />
     </div>
   )
diff --git a/app/forms/instance-create.tsx b/app/forms/instance-create.tsx
index c1a0dcfac..2a555b758 100644
--- a/app/forms/instance-create.tsx
+++ b/app/forms/instance-create.tsx
@@ -321,9 +321,9 @@ export default function CreateInstanceForm() {
     .filter(poolHasIpVersion(defaultCompatibleVersions))
     .filter((p) => p.isDefault)
 
-  // Check for compatible defaults to determine checkbox initialization
-  const hasCompatibleV4Default = compatibleDefaultPools.some((p) => p.ipVersion === 'v4')
-  const hasCompatibleV6Default = compatibleDefaultPools.some((p) => p.ipVersion === 'v6')
+  // Get default pools for initial values
+  const defaultV4Pool = compatibleDefaultPools.find((p) => p.ipVersion === 'v4')
+  const defaultV6Pool = compatibleDefaultPools.find((p) => p.ipVersion === 'v6')
 
   const defaultValues: InstanceCreateInput = {
     ...baseDefaultValues,
@@ -331,10 +331,10 @@ export default function CreateInstanceForm() {
     bootDiskSourceType: defaultSource,
     sshPublicKeys: allKeys,
     bootDiskSize: diskSizeNearest10(defaultImage?.size / GiB),
-    ephemeralIpv4: hasCompatibleV4Default && defaultCompatibleVersions.includes('v4'),
-    ephemeralIpv4Pool: '',
-    ephemeralIpv6: hasCompatibleV6Default && defaultCompatibleVersions.includes('v6'),
-    ephemeralIpv6Pool: '',
+    ephemeralIpv4: !!defaultV4Pool && defaultCompatibleVersions.includes('v4'),
+    ephemeralIpv4Pool: defaultV4Pool?.name || '',
+    ephemeralIpv6: !!defaultV6Pool && defaultCompatibleVersions.includes('v6'),
+    ephemeralIpv6Pool: defaultV6Pool?.name || '',
     floatingIps: [],
   }
 
@@ -803,9 +803,7 @@ const NetworkingSection = ({
   const floatingIpsField = useController({ control, name: 'floatingIps' })
 
   const ephemeralIpv4 = ephemeralIpv4Field.field.value
-  const ephemeralIpv4Pool = ephemeralIpv4PoolField.field.value
   const ephemeralIpv6 = ephemeralIpv6Field.field.value
-  const ephemeralIpv6Pool = ephemeralIpv6PoolField.field.value
   const attachedFloatingIps = floatingIpsField.field.value ?? EMPTY_NAME_OR_ID_LIST
 
   // Calculate compatible IP versions based on NIC type
@@ -854,37 +852,6 @@ const NetworkingSection = ({
     .map((floatingIp) => attachableFloatingIps.find((fip) => fip.name === floatingIp))
     .filter((ip) => !!ip)
 
-  // IPv4 pool auto-selection
-  useEffect(() => {
-    if (!ephemeralIpv4 || v4Pools.length === 0) return
-
-    // If current pool is valid, keep it
-    if (ephemeralIpv4Pool && v4Pools.some((p) => p.name === ephemeralIpv4Pool)) return
-
-    // Otherwise, try to select default
-    const v4Default = v4Pools.find((p) => p.isDefault)
-    if (v4Default) {
-      ephemeralIpv4PoolField.field.onChange(v4Default.name)
-    } else {
-      // No default: clear the pool (user must select)
-      ephemeralIpv4PoolField.field.onChange('')
-    }
-  }, [ephemeralIpv4, ephemeralIpv4Pool, ephemeralIpv4PoolField, v4Pools])
-
-  // IPv6 pool auto-selection
-  useEffect(() => {
-    if (!ephemeralIpv6 || v6Pools.length === 0) return
-
-    if (ephemeralIpv6Pool && v6Pools.some((p) => p.name === ephemeralIpv6Pool)) return
-
-    const v6Default = v6Pools.find((p) => p.isDefault)
-    if (v6Default) {
-      ephemeralIpv6PoolField.field.onChange(v6Default.name)
-    } else {
-      ephemeralIpv6PoolField.field.onChange('')
-    }
-  }, [ephemeralIpv6, ephemeralIpv6Pool, ephemeralIpv6PoolField, v6Pools])
-
   // Clean up incompatible ephemeral IP selections when NIC changes
   useEffect(() => {
     // When NIC changes, uncheck and clear incompatible options
@@ -906,7 +873,7 @@ const NetworkingSection = ({
     ephemeralIpv6PoolField,
   ])
 
-  // Track previous canAttach state to detect transitions
+  // Track previous canAttach state to detect transitions for auto-enabling
   const prevCanAttachV4Ref = useRef<boolean | undefined>(undefined)
   const prevCanAttachV6Ref = useRef<boolean | undefined>(undefined)
 
@@ -1039,6 +1006,8 @@ const NetworkingSection = ({
               poolFieldName={poolFieldName}
               pools={pools}
               disabled={isSubmitting}
+              required={false}
+              hideOptionalTag
             />
           </div>
         )}

From b10cf36842f17bb8f00b0e563b2bfd6a5d53c7b9 Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Fri, 6 Feb 2026 21:11:29 -0800
Subject: [PATCH 05/11] A bit more logic around custom NICs

---
 app/forms/instance-create.tsx | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/app/forms/instance-create.tsx b/app/forms/instance-create.tsx
index 2a555b758..f5db54b70 100644
--- a/app/forms/instance-create.tsx
+++ b/app/forms/instance-create.tsx
@@ -880,27 +880,31 @@ const NetworkingSection = ({
   // Auto-enable ephemeral IPs when NICs are added that support them
   useEffect(() => {
     const prevCanAttachV4 = prevCanAttachV4Ref.current
-    const hasV4Default = v4Pools.some((p) => p.isDefault)
+    const v4Default = v4Pools.find((p) => p.isDefault)
 
     // Auto-enable v4 when transitioning from unable to able (e.g., NIC added)
-    if (canAttachV4 && hasV4Default && prevCanAttachV4 === false && !ephemeralIpv4) {
+    if (canAttachV4 && v4Default && prevCanAttachV4 === false && !ephemeralIpv4) {
       ephemeralIpv4Field.field.onChange(true)
+      // Also populate the pool field with the default
+      ephemeralIpv4PoolField.field.onChange(v4Default.name)
     }
 
     prevCanAttachV4Ref.current = canAttachV4
-  }, [canAttachV4, v4Pools, ephemeralIpv4, ephemeralIpv4Field])
+  }, [canAttachV4, v4Pools, ephemeralIpv4, ephemeralIpv4Field, ephemeralIpv4PoolField])
 
   useEffect(() => {
     const prevCanAttachV6 = prevCanAttachV6Ref.current
-    const hasV6Default = v6Pools.some((p) => p.isDefault)
+    const v6Default = v6Pools.find((p) => p.isDefault)
 
     // Auto-enable v6 when transitioning from unable to able (e.g., NIC added)
-    if (canAttachV6 && hasV6Default && prevCanAttachV6 === false && !ephemeralIpv6) {
+    if (canAttachV6 && v6Default && prevCanAttachV6 === false && !ephemeralIpv6) {
       ephemeralIpv6Field.field.onChange(true)
+      // Also populate the pool field with the default
+      ephemeralIpv6PoolField.field.onChange(v6Default.name)
     }
 
     prevCanAttachV6Ref.current = canAttachV6
-  }, [canAttachV6, v6Pools, ephemeralIpv6, ephemeralIpv6Field])
+  }, [canAttachV6, v6Pools, ephemeralIpv6, ephemeralIpv6Field, ephemeralIpv6PoolField])
 
   const noNicMessage = (version: IpVersion) => (
     <>

From 5600704fe378eb78ccbcbf1badf1407c30b2ae8d Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Fri, 6 Feb 2026 21:23:05 -0800
Subject: [PATCH 06/11] fix text

---
 test/e2e/instance-create.e2e.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/test/e2e/instance-create.e2e.ts b/test/e2e/instance-create.e2e.ts
index 7e21b58c2..461315c13 100644
--- a/test/e2e/instance-create.e2e.ts
+++ b/test/e2e/instance-create.e2e.ts
@@ -1025,8 +1025,8 @@ test('create instance with custom dual-stack NIC allows both IPv4 and IPv6 ephem
   await expect(ephemeralRows).toHaveCount(2)
 
   // Verify one is IPv4 and one is IPv6
-  await expect(externalIpsTable.getByText('IPv4')).toBeVisible()
-  await expect(externalIpsTable.getByText('IPv6')).toBeVisible()
+  await expect(externalIpsTable.getByText('v4')).toBeVisible()
+  await expect(externalIpsTable.getByText('v6')).toBeVisible()
 })
 
 test('ephemeral IP checkbox disabled when no NICs configured', async ({ page }) => {

From ee8c38a4220de84672a8e5a8b69513b0de1aebbb Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Mon, 9 Feb 2026 17:14:07 -0800
Subject: [PATCH 07/11] Use Remeda helpers

---
 app/forms/instance-create.tsx | 17 ++++++-----------
 1 file changed, 6 insertions(+), 11 deletions(-)

diff --git a/app/forms/instance-create.tsx b/app/forms/instance-create.tsx
index f5db54b70..d7f78f45e 100644
--- a/app/forms/instance-create.tsx
+++ b/app/forms/instance-create.tsx
@@ -817,14 +817,7 @@ const NetworkingSection = ({
     () => unicastPools.filter(poolHasIpVersion(compatibleVersions)),
     [unicastPools, compatibleVersions]
   )
-  const v4Pools = useMemo(
-    () => compatiblePools.filter((p) => p.ipVersion === 'v4'),
-    [compatiblePools]
-  )
-  const v6Pools = useMemo(
-    () => compatiblePools.filter((p) => p.ipVersion === 'v6'),
-    [compatiblePools]
-  )
+  const [v4Pools, v6Pools] = R.partition(compatiblePools, (p) => p.ipVersion === 'v4')
 
   const canAttachV4 = compatibleVersions.includes('v4') && v4Pools.length > 0
   const canAttachV6 = compatibleVersions.includes('v6') && v6Pools.length > 0
@@ -848,9 +841,11 @@ const NetworkingSection = ({
       .filter(ipHasVersion(compatibleVersions))
   }, [attachableFloatingIps, attachedFloatingIps, compatibleVersions])
 
-  const attachedFloatingIpsData = attachedFloatingIps
-    .map((floatingIp) => attachableFloatingIps.find((fip) => fip.name === floatingIp))
-    .filter((ip) => !!ip)
+  const attachedFloatingIpsData = R.compact(
+    attachedFloatingIps.map((floatingIp) =>
+      attachableFloatingIps.find((fip) => fip.name === floatingIp)
+    )
+  )
 
   // Clean up incompatible ephemeral IP selections when NIC changes
   useEffect(() => {

From bcb777990e525ddc029f3ed78fecb7f5d18d90cf Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Mon, 9 Feb 2026 17:41:40 -0800
Subject: [PATCH 08/11] revert compact function, as it seems to be unavailable

---
 app/forms/instance-create.tsx | 8 +++-----
 1 file changed, 3 insertions(+), 5 deletions(-)

diff --git a/app/forms/instance-create.tsx b/app/forms/instance-create.tsx
index d7f78f45e..d3e5b0c02 100644
--- a/app/forms/instance-create.tsx
+++ b/app/forms/instance-create.tsx
@@ -841,11 +841,9 @@ const NetworkingSection = ({
       .filter(ipHasVersion(compatibleVersions))
   }, [attachableFloatingIps, attachedFloatingIps, compatibleVersions])
 
-  const attachedFloatingIpsData = R.compact(
-    attachedFloatingIps.map((floatingIp) =>
-      attachableFloatingIps.find((fip) => fip.name === floatingIp)
-    )
-  )
+  const attachedFloatingIpsData = attachedFloatingIps
+    .map((floatingIp) => attachableFloatingIps.find((fip) => fip.name === floatingIp))
+    .filter((ip): ip is FloatingIp => !!ip)
 
   // Clean up incompatible ephemeral IP selections when NIC changes
   useEffect(() => {

From 46238693d9055382f78c6b94891d50f1b3635828 Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Tue, 10 Feb 2026 10:42:11 -0800
Subject: [PATCH 09/11] Refactoring post-aipr review

---
 app/components/form/fields/IpPoolSelector.tsx |  4 +++-
 app/forms/instance-create.tsx                 | 23 +++++++++++--------
 test/e2e/instance-create.e2e.ts               | 19 +++++++--------
 test/e2e/ip-pool-silo-config.e2e.ts           | 14 +++++------
 4 files changed, 34 insertions(+), 26 deletions(-)

diff --git a/app/components/form/fields/IpPoolSelector.tsx b/app/components/form/fields/IpPoolSelector.tsx
index f677b1c62..e40b696b2 100644
--- a/app/components/form/fields/IpPoolSelector.tsx
+++ b/app/components/form/fields/IpPoolSelector.tsx
@@ -55,6 +55,7 @@ type IpPoolSelectorProps<
   compatibleVersions?: IpVersion[]
   required?: boolean
   hideOptionalTag?: boolean
+  label?: string
 }
 
 export function IpPoolSelector<
@@ -69,6 +70,7 @@ export function IpPoolSelector<
   compatibleVersions = ALL_IP_VERSIONS,
   required = true,
   hideOptionalTag = false,
+  label = 'Pool',
 }: IpPoolSelectorProps<TFieldValues, TName>) {
   // Note: pools are already filtered by poolType before being passed to this component
   const sortedPools = useMemo(() => {
@@ -86,7 +88,7 @@ export function IpPoolSelector<
       <ListboxField
         name={poolFieldName}
         items={sortedPools.map(toIpPoolItem)}
-        label="Pool"
+        label={label}
         noItemsPlaceholder="No pools available"
         control={control}
         placeholder="Select a pool"
diff --git a/app/forms/instance-create.tsx b/app/forms/instance-create.tsx
index d3e5b0c02..b9c75595c 100644
--- a/app/forms/instance-create.tsx
+++ b/app/forms/instance-create.tsx
@@ -812,12 +812,15 @@ const NetworkingSection = ({
     [networkInterfaces]
   )
 
-  // Filter pools by compatibility and version
-  const compatiblePools = useMemo(
-    () => unicastPools.filter(poolHasIpVersion(compatibleVersions)),
+  // Filter pools by compatibility and partition by IP version
+  const [v4Pools, v6Pools] = useMemo(
+    () =>
+      R.partition(
+        unicastPools.filter(poolHasIpVersion(compatibleVersions)),
+        (p) => p.ipVersion === 'v4'
+      ),
     [unicastPools, compatibleVersions]
   )
-  const [v4Pools, v6Pools] = R.partition(compatiblePools, (p) => p.ipVersion === 'v4')
 
   const canAttachV4 = compatibleVersions.includes('v4') && v4Pools.length > 0
   const canAttachV6 = compatibleVersions.includes('v6') && v6Pools.length > 0
@@ -845,19 +848,20 @@ const NetworkingSection = ({
     .map((floatingIp) => attachableFloatingIps.find((fip) => fip.name === floatingIp))
     .filter((ip): ip is FloatingIp => !!ip)
 
-  // Clean up incompatible ephemeral IP selections when NIC changes
+  // Clean up incompatible ephemeral IP selections when NIC or pool availability changes
   useEffect(() => {
-    // When NIC changes, uncheck and clear incompatible options
-    if (ephemeralIpv4 && !compatibleVersions.includes('v4')) {
+    // Uncheck and clear when version incompatible or pools unavailable
+    if (ephemeralIpv4 && !canAttachV4) {
       ephemeralIpv4Field.field.onChange(false)
       ephemeralIpv4PoolField.field.onChange('')
     }
-    if (ephemeralIpv6 && !compatibleVersions.includes('v6')) {
+    if (ephemeralIpv6 && !canAttachV6) {
       ephemeralIpv6Field.field.onChange(false)
       ephemeralIpv6PoolField.field.onChange('')
     }
   }, [
-    compatibleVersions,
+    canAttachV4,
+    canAttachV6,
     ephemeralIpv4,
     ephemeralIpv4Field,
     ephemeralIpv4PoolField,
@@ -1005,6 +1009,7 @@ const NetworkingSection = ({
               disabled={isSubmitting}
               required={false}
               hideOptionalTag
+              label={`${displayVersion} pool`}
             />
           </div>
         )}
diff --git a/test/e2e/instance-create.e2e.ts b/test/e2e/instance-create.e2e.ts
index 461315c13..c38f6b057 100644
--- a/test/e2e/instance-create.e2e.ts
+++ b/test/e2e/instance-create.e2e.ts
@@ -76,12 +76,12 @@ test('can create an instance', async ({ page }) => {
   await expect(v6Checkbox).toBeChecked()
 
   // IPv4 default pool should be selected
-  const v4PoolDropdown = page.getByLabel('Pool').first()
+  const v4PoolDropdown = page.getByLabel('IPv4 pool')
   await expect(v4PoolDropdown).toBeVisible()
   await expect(v4PoolDropdown).toContainText('ip-pool-1')
 
   // IPv6 default pool should be selected
-  const v6PoolDropdown = page.getByLabel('Pool').last()
+  const v6PoolDropdown = page.getByLabel('IPv6 pool')
   await expect(v6PoolDropdown).toBeVisible()
   await expect(v6PoolDropdown).toContainText('ip-pool-2')
 
@@ -880,7 +880,7 @@ test('create instance with custom IPv4-only NIC constrains ephemeral IP to IPv4'
   await expect(v6Checkbox).toBeDisabled()
 
   // IPv4 pool dropdown should be visible with default selected
-  const v4PoolDropdown = page.getByLabel('Pool')
+  const v4PoolDropdown = page.getByLabel('IPv4 pool')
   await expect(v4PoolDropdown).toBeVisible()
   await expect(v4PoolDropdown).toContainText('ip-pool-1')
 
@@ -942,7 +942,7 @@ test('create instance with custom IPv6-only NIC constrains ephemeral IP to IPv6'
   await expect(v6Checkbox).toBeChecked()
 
   // IPv6 pool dropdown should be visible with default selected
-  const v6PoolDropdown = page.getByLabel('Pool')
+  const v6PoolDropdown = page.getByLabel('IPv6 pool')
   await expect(v6PoolDropdown).toBeVisible()
   await expect(v6PoolDropdown).toContainText('ip-pool-2')
 
@@ -1003,11 +1003,12 @@ test('create instance with custom dual-stack NIC allows both IPv4 and IPv6 ephem
   await expect(v6Checkbox).toBeChecked()
 
   // Both pool dropdowns should be visible with defaults selected
-  const poolDropdowns = page.getByLabel('Pool')
-  await expect(poolDropdowns.first()).toBeVisible()
-  await expect(poolDropdowns.first()).toContainText('ip-pool-1')
-  await expect(poolDropdowns.last()).toBeVisible()
-  await expect(poolDropdowns.last()).toContainText('ip-pool-2')
+  const v4PoolDropdown = page.getByLabel('IPv4 pool')
+  const v6PoolDropdown = page.getByLabel('IPv6 pool')
+  await expect(v4PoolDropdown).toBeVisible()
+  await expect(v4PoolDropdown).toContainText('ip-pool-1')
+  await expect(v6PoolDropdown).toBeVisible()
+  await expect(v6PoolDropdown).toContainText('ip-pool-2')
 
   // Create the instance
   await page.getByRole('button', { name: 'Create instance' }).click()
diff --git a/test/e2e/ip-pool-silo-config.e2e.ts b/test/e2e/ip-pool-silo-config.e2e.ts
index f016b33db..544fa6427 100644
--- a/test/e2e/ip-pool-silo-config.e2e.ts
+++ b/test/e2e/ip-pool-silo-config.e2e.ts
@@ -52,7 +52,7 @@ test.describe('IP pool configuration: myriad silo (v4-only default)', () => {
     await expect(v6Checkbox).not.toBeChecked()
 
     // IPv4 pool dropdown should be visible with default pool preselected
-    const v4PoolDropdown = page.getByLabel('Pool')
+    const v4PoolDropdown = page.getByLabel('IPv4 pool')
     await expect(v4PoolDropdown).toBeVisible()
     await expect(v4PoolDropdown).toContainText('ip-pool-1')
 
@@ -90,7 +90,7 @@ test.describe('IP pool configuration: myriad silo (v4-only default)', () => {
       name: 'Allocate and attach an ephemeral IPv4 address',
     })
     await expect(v4Checkbox).toBeChecked()
-    await expect(page.getByLabel('Pool')).toContainText('ip-pool-1')
+    await expect(page.getByLabel('IPv4 pool')).toContainText('ip-pool-1')
 
     // Create instance
     await page.getByRole('button', { name: 'Create instance' }).click()
@@ -229,7 +229,7 @@ test.describe('IP pool configuration: thrax silo (v6-only default)', () => {
     await expect(v6Checkbox).toBeChecked()
 
     // IPv6 pool dropdown should be visible with default pool preselected
-    const v6PoolDropdown = page.getByLabel('Pool')
+    const v6PoolDropdown = page.getByLabel('IPv6 pool')
     await expect(v6PoolDropdown).toBeVisible()
     await expect(v6PoolDropdown).toContainText('ip-pool-2')
 
@@ -279,16 +279,16 @@ test.describe('IP pool configuration: pelerines silo (no defaults)', () => {
     await expect(v6Checkbox).not.toBeChecked()
 
     // Pool dropdowns should not be shown unless ephemeral IPs are enabled
-    const poolDropdowns = page.getByLabel('Pool')
-    await expect(poolDropdowns.first()).toBeHidden()
+    const v4PoolDropdown = page.getByLabel('IPv4 pool')
+    await expect(v4PoolDropdown).toBeHidden()
 
     // Enabling IPv4 ephemeral IP should show pool dropdown
     await v4Checkbox.click()
     await expect(v4Checkbox).toBeChecked()
-    await expect(poolDropdowns.first()).toBeVisible()
+    await expect(v4PoolDropdown).toBeVisible()
 
     // Open dropdown to verify available options
-    await poolDropdowns.first().click()
+    await v4PoolDropdown.click()
     // Both pools are linked to this silo but neither is default
     await expect(page.getByRole('option', { name: 'ip-pool-1' })).toBeVisible()
   })

From 0002e805870408879189cc0bfc7eb2eac94b34f3 Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Tue, 10 Feb 2026 10:53:00 -0800
Subject: [PATCH 10/11] small adjustments

---
 app/forms/instance-create.tsx   |  6 +++++-
 test/e2e/instance-create.e2e.ts | 25 +++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

diff --git a/app/forms/instance-create.tsx b/app/forms/instance-create.tsx
index b9c75595c..1f7b10d78 100644
--- a/app/forms/instance-create.tsx
+++ b/app/forms/instance-create.tsx
@@ -995,7 +995,11 @@ const NetworkingSection = ({
       <div className="max-w-lg space-y-2">
         <Wrap when={!!disabledReason} with={<Tooltip content={disabledReason} />}>
           <span>
-            <CheckboxField control={control} name={checkboxName} disabled={!canAttach}>
+            <CheckboxField
+              control={control}
+              name={checkboxName}
+              disabled={!canAttach || isSubmitting}
+            >
               Allocate and attach an ephemeral {displayVersion} address
             </CheckboxField>
           </span>
diff --git a/test/e2e/instance-create.e2e.ts b/test/e2e/instance-create.e2e.ts
index c38f6b057..74bacfd3b 100644
--- a/test/e2e/instance-create.e2e.ts
+++ b/test/e2e/instance-create.e2e.ts
@@ -153,6 +153,11 @@ test('ephemeral pool selection tracks network interface IP version', async ({ pa
   await expect(v6Checkbox).toBeEnabled()
   await expect(v6Checkbox).toBeChecked()
 
+  // Verify disabled v4 checkbox shows tooltip
+  await v4Checkbox.hover()
+  await expect(page.getByText('Add an IPv4 network interface')).toBeVisible()
+  await expect(page.getByText('to attach an ephemeral IPv4 address')).toBeVisible()
+
   // Change to IPv4-only NIC - v6 checkbox should become disabled and unchecked
   await selectOption(page, page.getByRole('button', { name: 'IPv6' }), 'IPv4')
   await expect(v4Checkbox).toBeVisible()
@@ -161,6 +166,11 @@ test('ephemeral pool selection tracks network interface IP version', async ({ pa
   await expect(v6Checkbox).toBeVisible()
   await expect(v6Checkbox).toBeDisabled()
   await expect(v6Checkbox).not.toBeChecked()
+
+  // Verify disabled v6 checkbox shows tooltip
+  await v6Checkbox.hover()
+  await expect(page.getByText('Add an IPv6 network interface')).toBeVisible()
+  await expect(page.getByText('to attach an ephemeral IPv6 address')).toBeVisible()
 })
 
 test('duplicate instance name produces visible error', async ({ page }) => {
@@ -1070,6 +1080,16 @@ test('ephemeral IP checkbox disabled when no NICs configured', async ({ page })
   await expect(v6Checkbox).toBeDisabled()
   await expect(v6Checkbox).not.toBeChecked()
 
+  // Verify tooltip shows disabled reason for IPv4
+  await v4Checkbox.hover()
+  await expect(page.getByText('Add an IPv4 network interface')).toBeVisible()
+  await expect(page.getByText('to attach an ephemeral IPv4 address')).toBeVisible()
+
+  // Verify tooltip shows disabled reason for IPv6
+  await v6Checkbox.hover()
+  await expect(page.getByText('Add an IPv6 network interface')).toBeVisible()
+  await expect(page.getByText('to attach an ephemeral IPv6 address')).toBeVisible()
+
   // Select "Custom" radio → verify ephemeral IP checkboxes are still disabled and unchecked
   await customRadio.click()
   await expect(v4Checkbox).toBeVisible()
@@ -1079,6 +1099,11 @@ test('ephemeral IP checkbox disabled when no NICs configured', async ({ page })
   await expect(v6Checkbox).toBeDisabled()
   await expect(v6Checkbox).not.toBeChecked()
 
+  // Verify tooltip still shows disabled reason when in Custom mode with no NICs
+  await v4Checkbox.hover()
+  await expect(page.getByText('Add an IPv4 network interface')).toBeVisible()
+  await expect(page.getByText('to attach an ephemeral IPv4 address')).toBeVisible()
+
   // Click "Add network interface" button to open modal
   await page.getByRole('button', { name: 'Add network interface' }).click()
 

From 7641d9f5bb6335fd58ad714f17fd90e35080eeb9 Mon Sep 17 00:00:00 2001
From: Charlie Park <charlie@oxidecomputer.com>
Date: Tue, 10 Feb 2026 11:36:52 -0800
Subject: [PATCH 11/11] fix test

---
 test/e2e/instance-create.e2e.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/test/e2e/instance-create.e2e.ts b/test/e2e/instance-create.e2e.ts
index 74bacfd3b..d77a0edcb 100644
--- a/test/e2e/instance-create.e2e.ts
+++ b/test/e2e/instance-create.e2e.ts
@@ -159,7 +159,7 @@ test('ephemeral pool selection tracks network interface IP version', async ({ pa
   await expect(page.getByText('to attach an ephemeral IPv4 address')).toBeVisible()
 
   // Change to IPv4-only NIC - v6 checkbox should become disabled and unchecked
-  await selectOption(page, page.getByRole('button', { name: 'IPv6' }), 'IPv4')
+  await selectOption(page, page.getByRole('button', { name: 'IPv6', exact: true }), 'IPv4')
   await expect(v4Checkbox).toBeVisible()
   await expect(v4Checkbox).toBeEnabled()
   await expect(v4Checkbox).toBeChecked()