diff --git a/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/AgentTemplateControl.tsx b/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/AgentTemplateControl.tsx
index 3c354709cc..d34fe1768d 100644
--- a/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/AgentTemplateControl.tsx
+++ b/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/AgentTemplateControl.tsx
@@ -121,12 +121,15 @@ const ModelHarnessSectionBody = ({
     section,
     ...params
 }: {
-    section: "model-harness" | "advanced"
+    section: "model-harness" | "advanced" | "connect-key"
 } & Parameters<typeof useModelHarness>[0]) => {
     const mh = useModelHarness(params)
     if (section === "advanced") {
         return <>{mh.advancedDrawerBody}</>
     }
+    if (section === "connect-key") {
+        return <>{mh.providerCredentialsSection}</>
+    }
     return <>{mh.modelHarnessDrawerBody}</>
 }
 
@@ -490,6 +493,15 @@ export const AgentTemplateControl = memo(function AgentTemplateControl({
         }),
         [sectionChanges.draft, onChange, config, committed],
     )
+    // Whether this edit touched the provider/connection specifically, not just any model-harness field.
+    const credentialsPathChanged = useMemo(
+        () =>
+            (sectionChanges.draft.sectionsByKey.get("model-harness")?.scalarChanges ?? []).some(
+                (c) => c.key === "llm.provider" || c.key.startsWith("llm.connection"),
+            ),
+        [sectionChanges.draft],
+    )
+
     // The inline body for a drawer-backed section: its own controls, narrowed to what changed — the
     // same affordance as the Connect-key field, with a different filter (see SectionChangeBody).
     // The body is a COMPONENT rendered inside the providers, never `mh`'s pre-built output: the hook
@@ -817,7 +829,8 @@ export const AgentTemplateControl = memo(function AgentTemplateControl({
             // What the section surfaces inline, in precedence order. Dropping `onOpen` is what makes
             // a section expand inline instead of routing to the drawer.
             //   1. Required info missing (no provider key) — BLOCKING, so it wins: the same key field
-            //      the drawer uses, right here.
+            //      the drawer uses, right here, swapped for the changed-aware variant when this edit
+            //      touched the provider/connection (`credentialsPathChanged`) so that diff isn't lost.
             //   2. Uncommitted changes — informational: what changed (see `changeBodyFor`).
             //   3. Neither — the plain drawer row it has always been.
             ...(showKeyPane
@@ -832,7 +845,22 @@ export const AgentTemplateControl = memo(function AgentTemplateControl({
                                       onOpenDetails={() => openSectionDrawer("model-harness")}
                                       disabled={disabled}
                                   >
-                                      {mh.providerCredentialsInline}
+                                      {credentialsPathChanged ? (
+                                          <ChangedPathsProvider changes={panelChangedPaths}>
+                                              <ModelHarnessSectionBody
+                                                  section="connect-key"
+                                                  schema={schema}
+                                                  config={config}
+                                                  onChange={onChange}
+                                                  disabled={disabled}
+                                                  withTooltip={withTooltip}
+                                                  revisionId={revisionId}
+                                                  savedHarnessValue={savedHarnessValue}
+                                              />
+                                          </ChangedPathsProvider>
+                                      ) : (
+                                          mh.providerCredentialsInline
+                                      )}
                                   </SectionQuickAction>
                               </div>
                           </HeightCollapse>
diff --git a/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/agentTemplate/useModelHarness.tsx b/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/agentTemplate/useModelHarness.tsx
index 545b00ac6b..69254115e8 100644
--- a/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/agentTemplate/useModelHarness.tsx
+++ b/web/packages/agenta-entity-ui/src/DrillInView/SchemaControls/agentTemplate/useModelHarness.tsx
@@ -454,10 +454,24 @@ export function useModelHarness({
     // `harness.kind` (NOT all of `harness`) so a permissions edit doesn't light up the Harness header.
     const harnessKindChanged = useHasChangedUnder("harness.kind")
     const modelChanged = useHasChangedUnder("llm.model")
-    const credentialsChanged = useHasChangedUnder("llm.connection")
+    // Provider credentials cover both the connection (mode/slug) and the bare `llm.provider` field a
+    // catalog model switch can move on its own — track both, or a provider-only change gets a "Connect
+    // key" badge with no changed indicator or Restore to go with it.
+    const connectionChanged = useHasChangedUnder("llm.connection")
+    const providerFieldChanged = useHasChangedUnder("llm.provider")
+    const credentialsChanged = connectionChanged || providerFieldChanged
     const revertHarnessKind = useRevertUnder("harness.kind")
     const revertModel = useRevertUnder("llm.model")
-    const revertCredentials = useRevertUnder("llm.connection")
+    const revertConnection = useRevertUnder("llm.connection")
+    const revertProviderField = useRevertUnder("llm.provider")
+    // `writeModel` can move `llm.model` atomically with `llm.provider`/`llm.connection.slug` (a
+    // catalog pick clears the old custom slug) — revert all three together or the group's Restore
+    // reattaches a stale slug to the new model, a combination the backend rejects.
+    const revertCredentials = useCallback(() => {
+        revertConnection?.()
+        revertProviderField?.()
+        revertModel?.()
+    }, [revertConnection, revertProviderField, revertModel])
     // Confirmed, because unlike the per-row undo (which is reached THROUGH the popover showing the
     // exact value it restores — see `RailField`) this one discards every change in the group at once
     // and names none of them.
@@ -722,7 +736,7 @@ export function useModelHarness({
               disabled,
               revisionId: revisionId ?? null,
               indicator: changedIndicator(credentialsChanged),
-              revertControl: revertAction(revertCredentials),
+              revertControl: credentialsChanged ? revertAction(revertCredentials) : undefined,
           }
         : null
     // The full pane (own header + rail) for the drawer body; the `bare` variant (toggle + key form /
@@ -1094,6 +1108,10 @@ export function useModelHarness({
         // self-managed card; no nested header/badge, no rail) for the inline "Connect key"
         // quick-action under the section header — aligned with the drawer without duplicating it.
         providerCredentialsInline,
+        // The full accordion variant (header, "Connect key" badge, changed-path indicator, group
+        // revert) — used instead of the bare pane when the connect-key state coincides with an
+        // uncommitted change, so the change stays visible rather than being silently dropped.
+        providerCredentialsSection,
         // A model is selected but the chosen harness can't run it — a *model* problem (the harness
         // itself stays valid), so the config panel flags the Model & harness section as invalid.
         modelUnsupported: !!modelId && !selectedKeepsModel,