diff --git a/apps/desktop/src/app/settings/model-settings.test.tsx b/apps/desktop/src/app/settings/model-settings.test.tsx
index 5a53812bf0..93c43972d3 100644
--- a/apps/desktop/src/app/settings/model-settings.test.tsx
+++ b/apps/desktop/src/app/settings/model-settings.test.tsx
@@ -281,6 +281,41 @@ describe('ModelSettings', () => {
     )
   })
 
+  it('matches a saved custom:<key> main provider to its catalog row', async () => {
+    // model.info reports a user-defined provider as `custom:<key>`, while the
+    // catalog row carries the bare key as its slug plus the alias list.
+    getGlobalModelInfo.mockResolvedValueOnce({ provider: 'custom:lab', model: 'lab-large' })
+    getGlobalModelOptions.mockResolvedValueOnce({
+      providers: [
+        {
+          name: 'Lab',
+          slug: 'lab',
+          aliases: ['custom:lab', 'lab'],
+          models: ['lab-small', 'lab-large'],
+          authenticated: true,
+          is_user_defined: true,
+          api_url: 'http://lab.local/v1'
+        }
+      ]
+    })
+
+    renderModelSettings()
+
+    await waitFor(() => expect(screen.getAllByRole('combobox')[0].textContent).toBe('Lab'))
+    expect(screen.queryByRole('button', { name: 'Set up provider' })).toBeNull()
+
+    fireEvent.click(await screen.findByRole('button', { name: 'Apply' }))
+
+    await waitFor(() =>
+      expect(setModelAssignment).toHaveBeenCalledWith({
+        model: 'lab-large',
+        provider: 'custom:lab',
+        scope: 'main',
+        base_url: 'http://lab.local/v1'
+      })
+    )
+  })
+
   it('writes the profile default speed (service_tier) as a sparse patch, never the cached snapshot', async () => {
     // The cached record is a default-expanded snapshot; a CLI pin made after it
     // loaded is not in it. Echoing the whole record back would reset that
diff --git a/apps/desktop/src/app/settings/model-settings.tsx b/apps/desktop/src/app/settings/model-settings.tsx
index a38272feb9..5b396afcdb 100644
--- a/apps/desktop/src/app/settings/model-settings.tsx
+++ b/apps/desktop/src/app/settings/model-settings.tsx
@@ -30,6 +30,7 @@ import { useI18n } from '@/i18n'
 import { isCodeSkewRestartRequired } from '@/lib/code-skew-error'
 import { AlertTriangle, Cpu, Loader2 } from '@/lib/icons'
 import { isSubmitEnter } from '@/lib/ime'
+import { findCatalogProvider } from '@/lib/model-options'
 import { cn } from '@/lib/utils'
 import { $customModels, withCustomModels } from '@/store/custom-models'
 import { setMainModelAssignment } from '@/store/model-assignment'
@@ -394,7 +395,7 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
   // leaving it out of the real inventory used for readiness/setup metadata.
   const mainProviderOptions = useMemo(
     () =>
-      selectedProvider && !providers.some(provider => provider.slug === selectedProvider)
+      selectedProvider && !findCatalogProvider(providers, selectedProvider)
         ? [{ name: selectedProvider, slug: selectedProvider, models: [] }, ...providers]
         : providerOptions,
     [providerOptions, providers, selectedProvider]
@@ -406,7 +407,7 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
   const moaSlotProviderOptions = providerOptions.filter(provider => (provider.slug || '').toLowerCase() !== 'moa')
 
   const selectedProviderRow = useMemo(
-    () => providers.find(provider => provider.slug === selectedProvider),
+    () => findCatalogProvider(providers, selectedProvider),
     [providers, selectedProvider]
   )
 
@@ -424,12 +425,12 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
   }, [selectedProvider])
 
   const auxDraftProviderModels = useMemo(
-    () => providers.find(provider => provider.slug === auxDraft.provider)?.models ?? [],
+    () => findCatalogProvider(providers, auxDraft.provider)?.models ?? [],
     [auxDraft.provider, providers]
   )
 
   const modelsForProvider = useCallback(
-    (provider: string) => providers.find(row => row.slug === provider)?.models ?? [],
+    (provider: string) => findCatalogProvider(providers, provider)?.models ?? [],
     [providers]
   )
 
@@ -585,7 +586,7 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
   // reasoning/speed controls the same way the composer picker gates per-model
   // edits (reasoning defaults on, fast defaults off when unreported).
   const mainCaps = useMemo(() => {
-    const row = providers.find(provider => provider.slug === mainModel?.provider)
+    const row = mainModel ? findCatalogProvider(providers, mainModel.provider) : undefined
 
     return mainModel ? row?.capabilities?.[mainModel.model] : undefined
   }, [providers, mainModel])
@@ -761,7 +762,7 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
   // main endpoint.
   const endpointForProvider = useCallback(
     (provider: string) => {
-      const row = providers.find(entry => entry.slug === provider)
+      const row = findCatalogProvider(providers, provider)
 
       return row?.api_url ? { base_url: row.api_url } : {}
     },
@@ -916,7 +917,7 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
         <section>
           <p className="mb-3 text-xs text-muted-foreground">{m.appliesDesc}</p>
           <div className="flex flex-wrap items-center gap-2">
-            <Select onValueChange={setSelectedProvider} value={selectedProvider}>
+            <Select onValueChange={setSelectedProvider} value={selectedProviderRow?.slug ?? selectedProvider}>
               <SelectTrigger className={cn('min-w-40', CONTROL_TEXT)}>
                 <SelectValue placeholder={m.provider} />
               </SelectTrigger>
@@ -1099,7 +1100,7 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
                           <div className="flex flex-wrap items-center gap-2">
                             <Select
                               onValueChange={value => setAuxDraft(prev => ({ ...prev, provider: value, model: '' }))}
-                              value={auxDraft.provider}
+                              value={findCatalogProvider(providers, auxDraft.provider)?.slug ?? auxDraft.provider}
                             >
                               <SelectTrigger
                                 aria-label={`${copy.label} provider`}
@@ -1120,7 +1121,7 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
                               className="min-w-48"
                               models={auxDraftProviderModels}
                               onValueChange={value => setAuxDraft(prev => ({ ...prev, model: value }))}
-                              provider={providers.find(row => row.slug === auxDraft.provider)}
+                              provider={findCatalogProvider(providers, auxDraft.provider)}
                               providerSlug={auxDraft.provider}
                               value={auxDraft.model}
                             />
@@ -1352,7 +1353,7 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
                           )
                         }))
                       }
-                      provider={providers.find(row => row.slug === slot.provider)}
+                      provider={findCatalogProvider(providers, slot.provider)}
                       providerSlug={slot.provider}
                       value={slot.model}
                     />
@@ -1438,7 +1439,7 @@ export function ModelSettings({ onMainModelChanged, scopeProfile, subpage }: Mod
                         aggregator: updateMoaSlot(prev.aggregator, { model: value })
                       }))
                     }
-                    provider={providers.find(row => row.slug === currentMoaPreset.aggregator.provider)}
+                    provider={findCatalogProvider(providers, currentMoaPreset.aggregator.provider)}
                     providerSlug={currentMoaPreset.aggregator.provider}
                     value={currentMoaPreset.aggregator.model}
                   />
diff --git a/apps/desktop/src/lib/model-options.ts b/apps/desktop/src/lib/model-options.ts
index 90554c8a41..2c8635c7f3 100644
--- a/apps/desktop/src/lib/model-options.ts
+++ b/apps/desktop/src/lib/model-options.ts
@@ -2,7 +2,8 @@ import type { ModelCapabilities, ModelOptionProvider, ModelOptionsResult } from
 
 import { getGlobalModelOptions, type HermesGateway } from '@/hermes'
 
-type CatalogProviderIdentity = Pick<ModelOptionProvider, 'aliases' | 'name' | 'slug'>
+type CatalogProviderIdentity = Partial<Pick<ModelOptionProvider, 'aliases' | 'name'>> &
+  Pick<ModelOptionProvider, 'slug'>
 
 /** True when `currentProvider` is this catalog row — slug, display name, or
  *  a custom-provider alias (`custom:<key>` vs the bare config key, #87035). */
@@ -18,6 +19,15 @@ export function catalogProviderMatches(provider: CatalogProviderIdentity, curren
   )
 }
 
+/** The catalog row for `currentProvider`, matched the same way as
+ *  `catalogProviderMatches` (so a saved `custom:<key>` finds its row). */
+export function findCatalogProvider<T extends CatalogProviderIdentity>(
+  providers: readonly T[],
+  currentProvider: string
+): T | undefined {
+  return providers.find(row => catalogProviderMatches(row, currentProvider))
+}
+
 /** The catalog's option support for the current pick, or undefined while the
  *  catalog is loading / doesn't say. Callers treat undefined as "assume
  *  reasoning" so controls never flicker away during the fetch. */
@@ -26,7 +36,7 @@ export function currentModelCapabilities(
   provider: string,
   model: string
 ): ModelCapabilities | undefined {
-  return options?.providers?.find(row => catalogProviderMatches(row, provider))?.capabilities?.[model]
+  return findCatalogProvider(options?.providers ?? [], provider)?.capabilities?.[model]
 }
 
 // A picked (provider, model) pair is never retargeted from catalog membership.
diff --git a/apps/desktop/src/plugins/hermes-bots/model-picker.test.tsx b/apps/desktop/src/plugins/hermes-bots/model-picker.test.tsx
index 5173350078..b80bcc6a11 100644
--- a/apps/desktop/src/plugins/hermes-bots/model-picker.test.tsx
+++ b/apps/desktop/src/plugins/hermes-bots/model-picker.test.tsx
@@ -38,10 +38,11 @@ const { hostMock } = vi.hoisted(() => ({
 
 vi.mock('@hermes/plugin-sdk', async () => {
   const { useQuery } = await import('@tanstack/react-query')
-  const { useI18n } = await vi.importActual<typeof HermesSdk>('@hermes/plugin-sdk')
+  const { catalogProviderMatches, useI18n } = await vi.importActual<typeof HermesSdk>('@hermes/plugin-sdk')
 
   return {
     Button: (props: React.ComponentProps<'button'>) => <button {...props} />,
+    catalogProviderMatches,
     GlyphSpinner: () => <span data-testid="spinner" />,
     host: hostMock,
     Input: (props: React.ComponentProps<'input'>) => <input {...props} />,
@@ -211,3 +212,19 @@ describe('the manual-entry form vs the dropdowns (#121875)', () => {
     await waitFor(() => expect(isFreeText(container)).toBe(false))
   })
 })
+
+describe('a saved custom provider', () => {
+  it('matches its catalog row through the custom:<key> alias', async () => {
+    // model.options reports a user-defined provider as `custom:<key>`, while
+    // the catalog row carries the bare key as its slug plus the alias list.
+    hostMock.requestProfile.mockResolvedValue({
+      providers: [{ aliases: ['custom:lab', 'lab'], models: ['lab-small', 'lab-large'], name: 'Lab', slug: 'lab' }]
+    })
+
+    const { container } = mountWithSelection(remoteBot, { model: 'lab-large', provider: 'custom:lab' })
+
+    await waitFor(() => expect(container.querySelector('[data-testid="spinner"]')).toBeNull())
+    expect(isFreeText(container)).toBe(false)
+    expect(screen.getByText('lab-small')).toBeTruthy()
+  })
+})
diff --git a/apps/desktop/src/plugins/hermes-bots/model-picker.tsx b/apps/desktop/src/plugins/hermes-bots/model-picker.tsx
index 59510a6b63..abe8afb7e6 100644
--- a/apps/desktop/src/plugins/hermes-bots/model-picker.tsx
+++ b/apps/desktop/src/plugins/hermes-bots/model-picker.tsx
@@ -8,6 +8,7 @@
 
 import {
   Button,
+  catalogProviderMatches,
   GlyphSpinner,
   Input,
   Select,
@@ -63,6 +64,7 @@ function boundedModelOptionsFetch<T>(fetch: Promise<T>, settleMs = MODEL_OPTIONS
 /** One provider row of the gateway's `model.options` inventory. Entries in
  *  `models` are bare slugs on current gateways and objects on older ones. */
 interface ModelProviderOption {
+  aliases?: null | string[]
   models?: Array<string | { id?: string; name?: string }>
   name?: string
   slug: string
@@ -128,7 +130,10 @@ export function ModelPicker({ bot = null, value, onChange, placeholderModel }: M
   const NONE = '__default__'
   const CUSTOM = '__custom__'
   const providers = (data?.providers || []).filter(p => p && p.slug)
-  const isKnown = !value.provider || value.provider === NONE || providers.some(p => p.slug === value.provider)
+
+  const isKnown =
+    !value.provider || value.provider === NONE || providers.some(p => catalogProviderMatches(p, value.provider))
+
   // The manual-entry latch is the USER's choice only. Seeding it from
   // `isKnown` froze whatever the catalog state was at first paint: on the
   // first open the async read had not resolved yet, so a configured provider
@@ -221,7 +226,7 @@ export function ModelPicker({ bot = null, value, onChange, placeholderModel }: M
     )
   }
 
-  const activeProvider = providers.find(p => p.slug === value.provider) || null
+  const activeProvider = providers.find(p => catalogProviderMatches(p, value.provider)) || null
 
   const models = activeProvider
     ? (activeProvider.models || []).map(m => (typeof m === 'string' ? m : m.id || m.name || ''))
@@ -250,7 +255,7 @@ export function ModelPicker({ bot = null, value, onChange, placeholderModel }: M
               })
             }
           }}
-          value={value.provider || NONE}
+          value={activeProvider?.slug || value.provider || NONE}
         >
           <SelectTrigger className="h-8 rounded-md">
             <SelectValue />
diff --git a/apps/desktop/src/sdk/index.ts b/apps/desktop/src/sdk/index.ts
index b67078b705..a10b90d794 100644
--- a/apps/desktop/src/sdk/index.ts
+++ b/apps/desktop/src/sdk/index.ts
@@ -1930,6 +1930,9 @@ export { formatModifierToken } from '@/lib/keybinds/combo'
 export { LruCache } from '@/lib/lru-cache'
 /** Capture a gateway file download alongside a REST read (see the SDK guide). */
 export { captureGatewayFileDownload } from '@/lib/media'
+/** True when a saved provider id names this `model.options` row: its slug,
+ *  display name, or a custom-provider alias (`custom:<key>` vs the bare key). */
+export { catalogProviderMatches } from '@/lib/model-options'
 /** The app's deterministic identity color for a name (profiles, assignees,
  *  authors), its translucent tag fill, and the curated picker swatches — so
  *  plugin-rendered identities read the same hue as everywhere else. The
diff --git a/website/docs/developer-guide/desktop-plugin-sdk.md b/website/docs/developer-guide/desktop-plugin-sdk.md
index 790b60d946..9a3122cc35 100644
--- a/website/docs/developer-guide/desktop-plugin-sdk.md
+++ b/website/docs/developer-guide/desktop-plugin-sdk.md
@@ -1554,7 +1554,7 @@ pipeline as a trust boundary.
 | React / state | `useValue`, `atom`, `computed`, `useQuery`, `useMutation`, `useQueryClient`, `queryClient`, `Contribute` |
 | Theming | `useTheme`, `requestTheme`, `setAccentOverride`, `$accentOverride`, `retintTheme`, `themeHue`, `DesktopTheme`, `DesktopThemeColors`, plus OKLCH math (`hexToOklch`, `oklchToHex`, `oklchToSrgb255`, `mixOklab`, `maxChroma`, `hueDelta`, `normalizeHex`) and sRGB measures (`contrastRatio` — `number | null`, null for unparseable input — `readableOn`) |
 | UI kit | `Button`, `Input`, `Textarea`, `Select*`, `Switch`, `Checkbox`, `SegmentedControl`, `Tabs*`, `Dialog*`, `ConfirmDialog`, `DropdownMenu*`, `ContextMenu*`, `Popover*`, `Tip`/`Tooltip*`, `Badge`, `Kbd`/`KbdGroup`, `SearchField`, `ScrollArea`, `Separator`, `Skeleton`, `GlyphSpinner`, `Loader`, `EmptyState`, `ErrorState`, `CopyButton`, `StatusDot`, `LogView`, `Codicon`, `DecodeText`, `SandboxedFrame` |
-| Helpers | `cn`, `icons`, `haptic`, `useI18n`, `profileColor`, `profileColorSoft`, `relativeTime`, `fmtDateTime`, `fmtDayTime`, `coarseElapsed`, `evaluateRuntimeReadiness` |
+| Helpers | `cn`, `icons`, `haptic`, `useI18n`, `profileColor`, `profileColorSoft`, `relativeTime`, `fmtDateTime`, `fmtDayTime`, `coarseElapsed`, `evaluateRuntimeReadiness`, `catalogProviderMatches` |
 
 The canonical, always-current export list is `apps/desktop/src/sdk/index.ts`.