diff --git a/src/agents/agent-command.live-model-switch.test.ts b/src/agents/agent-command.live-model-switch.test.ts
index 0f5d68f02e1e..db5acdd74c98 100644
--- a/src/agents/agent-command.live-model-switch.test.ts
+++ b/src/agents/agent-command.live-model-switch.test.ts
@@ -397,6 +397,9 @@ vi.mock("../skills/discovery/chat-commands.runtime.js", () => ({
 
 vi.mock("../config/runtime-snapshot.js", () => ({
   getRuntimeConfigSnapshot: () => state.runtimeConfigMock ?? state.defaultRuntimeConfig,
+  // No source snapshot: runtime-source projection no-ops and resolvers read the
+  // provided config directly, matching this suite's pre-projection world.
+  getRuntimeConfigSourceSnapshot: () => null,
   registerRuntimeConfigSnapshotPreparer: vi.fn(),
   setRuntimeConfigSnapshot: vi.fn(),
 }));
diff --git a/ui/docs/design-system/settings-design.md b/ui/docs/design-system/settings-design.md
index a3aa0381ff20..ee8ee32f8f2a 100644
--- a/ui/docs/design-system/settings-design.md
+++ b/ui/docs/design-system/settings-design.md
@@ -14,6 +14,7 @@ Every settings surface (the `/settings` takeover pages plus the Plugins/Skills h
 ```
 
 - **Sections are typography, not chrome.** Grouping comes from whitespace + a small uppercase heading — never a card header.
+- **Embedded surfaces keep the rhythm.** A container that hosts sections without `.settings-page`'s centered column (tab panels, split layouts) takes `.settings-stack`; never re-space sections with page-local margin rules.
 - **Exactly one level of elevation.** A group never contains another card, callout, or bordered box. Nested detail uses `.settings-subrows` (indented rows), a stacked row, or a drill-in nav row.
 - **Row anatomy:** left is title (`--control-ui-text-md`, weight 500) over an optional one-line description (muted, sm). Right is exactly one control: toggle, select, segmented, button, plain value, or chevron (nav). Wide editors use the `stacked` variant.
 - **Lists are rows too.** An entity list (plugin, device, session) is a group whose rows carry an action cluster in the control slot — same anatomy as a toggle row.
diff --git a/ui/src/pages/agents/view.ts b/ui/src/pages/agents/view.ts
index 094475b84a8c..10f45d7e09d4 100644
--- a/ui/src/pages/agents/view.ts
+++ b/ui/src/pages/agents/view.ts
@@ -330,6 +330,7 @@ export function renderAgents(props: AgentsProps) {
               )}
               <div
                 id="agent-panel"
+                class="settings-stack"
                 role="tabpanel"
                 aria-labelledby=${`agents-tab-${props.activePanel}`}
               >
diff --git a/ui/src/styles/agents.css b/ui/src/styles/agents.css
index 28c881db519e..ffdb2c1a765a 100644
--- a/ui/src/styles/agents.css
+++ b/ui/src/styles/agents.css
@@ -15,9 +15,3 @@
 .agents-panel-body + .settings-kv {
   border-top: 1px solid color-mix(in srgb, var(--border) 60%, transparent);
 }
-
-/* .agents-main is a 14px-gap grid (components.css); settings sections need
-   more whitespace between each other than panel chrome does. */
-.agents-main > .settings-section:not(:first-child) {
-  margin-top: var(--space-4);
-}
diff --git a/ui/src/styles/settings.css b/ui/src/styles/settings.css
index 8f7d700c7b72..879ca44fd1e3 100644
--- a/ui/src/styles/settings.css
+++ b/ui/src/styles/settings.css
@@ -87,6 +87,15 @@
   max-width: 1120px;
 }
 
+/* Section rhythm for embedded surfaces (tab panels, split layouts) that host
+   settings sections without .settings-page's centered column. Sections crammed
+   into a plain wrapper collapse to zero separation. */
+.settings-stack {
+  display: flex;
+  flex-direction: column;
+  gap: var(--space-8);
+}
+
 .settings-page__intro {
   margin: 0;
   font-size: var(--control-ui-text-sm);
@@ -130,6 +139,12 @@
   color: var(--muted);
 }
 
+/* Control-height header actions overhang the one-line heading; keep the
+   description's negative pull from squeezing it against the button row. */
+.settings-section__header:has(.settings-section__actions) + .settings-section__desc {
+  margin-top: 0;
+}
+
 .settings-section__actions {
   display: flex;
   align-items: center;