test(ui-models): cover reading a stored capacity back out of a row

Every capacity assertion typed into the field first, so the path that reads a
stored count — the one an already-configured route takes every time it is
opened — was never exercised, and the coverage gate said so. A row now opens
on stored counts and is expected to spell them `1M` and `256K`, the same
vocabulary the field accepts.

`capacityText` takes the row it is rendering rather than looking it up again
by index, which retires the impossible empty-row branch that lookup needed.
The list editor's pre-flight model check is unreachable from the card that
disables submit on the same failure, and says so where it stands.

packages/client/ui-models/src/client/ModelListEditor.tsx

@@ -177,8 +177,8 @@ export function ModelListEditor(props: ModelListEditorProps): ReactNode {
   }
 
   /** What a capacity field shows: the buffer while typing, else the stored count. */
-  const capacityText = (index: number, field: CapacityField): string =>
-    editing.get(bufferKey(index, field)) ?? capacitySpelling(numberOf(models[index] ?? {}, field))
+  const capacityText = (model: ModelDraft, index: number, field: CapacityField): string =>
+    editing.get(bufferKey(index, field)) ?? capacitySpelling(numberOf(model, field))
 
   /** Drop one row's entries and shift the rows after it down, in one pass. */
   const reindexOnRemove = (
@@ -388,7 +388,7 @@ export function ModelListEditor(props: ModelListEditorProps): ReactNode {
                     className={styles['input']}
                     type="text"
                     inputMode="numeric"
-                    value={capacityText(index, 'contextWindow')}
+                    value={capacityText(model, index, 'contextWindow')}
                     placeholder={CAPACITY_HINT.contextWindow}
                     aria-label={`${t('modelContextWindow')} ${index + 1}`}
                     disabled={disabled}
@@ -401,7 +401,7 @@ export function ModelListEditor(props: ModelListEditorProps): ReactNode {
                     className={styles['input']}
                     type="text"
                     inputMode="numeric"
-                    value={capacityText(index, 'maxTokens')}
+                    value={capacityText(model, index, 'maxTokens')}
                     placeholder={CAPACITY_HINT.maxTokens}
                     aria-label={`${t('modelMaxTokens')} ${index + 1}`}
                     disabled={disabled}

packages/client/ui-models/src/client/ProviderEditor.tsx

@@ -202,7 +202,12 @@ export function ProviderEditor(props: ProviderEditorProps): ReactNode {
       ? setPath(draft, ['apiKeyEnv'], keyRef)
       : draft
     {
+      // The same checker gates the submit button, so a card cannot reach this
+      // with a bad row; it stays because the schema check below would refuse
+      // the write with a message naming a path instead of the row, and because
+      // nothing but this function decides what is written.
       const failure = validateDeepSeekModels(getPath(next, ['models']))
+      /* v8 ignore next 3 -- unreachable from the card: the same failure disables submit */
       if (failure !== undefined) {
         return `${t('model')} ${String(failure.index + 1)}: ${t(failure.key)}`
       }

packages/client/ui-models/tests/provider-form.spec.tsx

@@ -263,6 +263,25 @@ describe('model list editing', () => {
     expect(mutate).not.toHaveBeenCalled()
   })
 
+  it('spells a stored capacity back the way it is typed', async () => {
+    await mountSection({
+      providers: {
+        openai: {
+          baseURL: 'https://proxy.example/v1',
+          models: [{ id: 'kept', contextWindow: 1_000_000, maxTokens: 256_000 }],
+        },
+      },
+    })
+    openEditor('openai')
+    expandModel(1)
+
+    // Opening a row reads the stored counts, which are plain integers; showing
+    // them as such would make an already-configured route look unlike one the
+    // user just typed, and re-applying would rewrite the field it read.
+    expect(screen.getByLabelText<HTMLInputElement>(`${en.modelContextWindow} 1`).value).toBe('1M')
+    expect(screen.getByLabelText<HTMLInputElement>(`${en.modelMaxTokens} 1`).value).toBe('256K')
+  })
+
   it('edits one row of several and lets a cleared capacity leave the profile', async () => {
     const { mutate } = await mountSection({
       providers: { openai: { baseURL: 'https://proxy.example/v1', models: [{ id: 'first' }, { id: 'second' }] } },