web: pin Connection Info modal header while body scrolls (#1754) (#1755)

Same fix as #1698, applied to the Connection Info modal, which had the same
pattern: a custom header Group (title + close) inside a Stack in the modal body,
using the default `<Modal>` with no `scrollAreaComponent`. With a long server
`instructions` section (e.g. the everything server) the details overflow the
viewport and the whole modal scrolled, taking the header out of view.

Switch to the compound `Modal.Root`/`Content`/`Header`/`Body` API, move the
header into `Modal.Header` (sticky by design) and set
`scrollAreaComponent={ScrollArea.Autosize}` so only the body scrolls. The
fade-down transition is supplied app-wide by `ThemeModalRoot` (added in #1753),
so no `transitionProps` literal is needed here.

Closes #1754


Claude-Session: https://claude.ai/code/session_01XNdjEPKLG637X8YmhDiEk5

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/web/src/components/groups/ConnectionInfoModal/ConnectionInfoModal.tsx

@@ -1,4 +1,4 @@
-import { CloseButton, Group, Modal, Stack } from "@mantine/core";
+import { CloseButton, Group, Modal, ScrollArea } from "@mantine/core";
 import type {
   ClientCapabilities,
   DiscoverResult,
@@ -35,30 +35,40 @@ export function ConnectionInfoModal({
   onClearOAuth,
 }: ConnectionInfoModalProps) {
   return (
-    <Modal
+    // Compound Modal so the header lives in `Modal.Header` (sticky by design)
+    // while `scrollAreaComponent` confines overflow to `Modal.Body` — otherwise
+    // a long connection-info payload grows the whole modal past the viewport and
+    // scrolls the header out of view (#1754, same fix as the settings modals in
+    // #1698). The fade-down transition is supplied app-wide by `ThemeModalRoot`.
+    <Modal.Root
       opened={opened}
       onClose={onClose}
-      withCloseButton={false}
       size="lg"
       centered
+      scrollAreaComponent={ScrollArea.Autosize}
     >
-      <Stack gap="md">
-        <Group justify="space-between" wrap="nowrap">
-          {/* `Modal.Title` (not a bare `Title`) registers the modal's
-              accessible name — it wires the dialog's `aria-labelledby`. */}
-          <Modal.Title flex={1}>Connection Info</Modal.Title>
-          <CloseButton aria-label="Close" onClick={onClose} />
-        </Group>
-        <ConnectionInfoContent
-          initializeResult={initializeResult}
-          clientCapabilities={clientCapabilities}
-          transport={transport}
-          protocolEra={protocolEra}
-          discoverResult={discoverResult}
-          oauth={oauth}
-          onClearOAuth={onClearOAuth}
-        />
-      </Stack>
-    </Modal>
+      <Modal.Overlay />
+      <Modal.Content>
+        <Modal.Header>
+          <Group justify="space-between" wrap="nowrap" w="100%">
+            {/* `Modal.Title` (not a bare `Title`) registers the modal's
+                accessible name — it wires the dialog's `aria-labelledby`. */}
+            <Modal.Title flex={1}>Connection Info</Modal.Title>
+            <CloseButton aria-label="Close" onClick={onClose} />
+          </Group>
+        </Modal.Header>
+        <Modal.Body>
+          <ConnectionInfoContent
+            initializeResult={initializeResult}
+            clientCapabilities={clientCapabilities}
+            transport={transport}
+            protocolEra={protocolEra}
+            discoverResult={discoverResult}
+            oauth={oauth}
+            onClearOAuth={onClearOAuth}
+          />
+        </Modal.Body>
+      </Modal.Content>
+    </Modal.Root>
   );
 }

pr-screenshots/README.md

@@ -1,3 +1,25 @@
+# Connection Info modal: sticky header while body scrolls (#1754) — proof screenshots
+
+Same fix as #1698, applied to the **Connection Info** modal. With a real server
+whose `instructions` are long (e.g. the everything server in a typical config),
+the connection details overflow the viewport; before the fix the whole modal
+scrolled and the header left the view. Captured from the `ConnectionInfoModal`
+Storybook story (`WithOAuth`, ~620px viewport) via Playwright.
+
+![Connection Info scrolled to the top — header pinned, Server Implementation visible](ci-1754-header-pinned-top.png)
+
+Top of scroll: the **Connection Info** header (title + close) sits above the
+first section.
+
+![Connection Info scrolled down — same header still pinned while the body shows Server Instructions / OAuth Details](ci-1754-header-pinned-scrolled.png)
+
+Scrolled down (now showing Server Instructions → OAuth Details): the **same
+header stays pinned**. Measured in-page: the body scroll container is
+`scrollHeight` 1172 × `clientHeight` 558 (scrolls internally), header
+`position: sticky` flush to the dialog top.
+
+---
+
 # Server/Client Settings modal: sticky header while body scrolls (#1698) — proof screenshots
 
 Expanding enough accordion sections grew the Server Settings modal past the