Switch models from the Command Center (#2147)

* Switch models from the Command Center

Add a model switcher to the Command-K Command Center. Typing surfaces a
flat, filterable list of "Model › Provider › Name" breadcrumb rows with
provider icons:

- Running agent: its own provider's models (a live agent can't change
  provider); selecting calls setAgentModel.
- New draft tab: every available provider's models in one flat list;
  selecting sets provider + model on the draft via a focused-draft
  controller published to a global store (the draft form state is local
  to the composer subtree and otherwise unreachable from the global
  Command Center).

Models only appear once the user starts typing, so the default palette
view is unchanged. Reuses useProvidersSnapshot and the existing
setAgentModel RPC — no protocol changes.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

* Update packages/app/src/components/command-center.tsx

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

* Update packages/app/src/hooks/use-command-center.ts

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>

* refactor(app): make Command Center extensible

Let focused features register stable actions while the palette owns search, selection, and a single virtualized result projection.

* fix(app): save model preference after agent switch

Persist the shared model choice only after the daemon confirms the live agent switched successfully.

---------

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>
Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>
Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>

packages/app/src/composer/draft/workspace-tab.tsx

@@ -24,6 +24,9 @@ import { useCreateFlowStore } from "@/stores/create-flow-store";
 import type { Agent } from "@/stores/session-store";
 import { useWorkspaceFields } from "@/stores/session-store-hooks";
 import { useWorkspaceDraftSubmissionStore } from "@/stores/workspace-draft-submission-store";
+import { useCommandCenterActions } from "@/command-center/provider";
+import { buildModelChoiceContributions } from "@/command-center/model-contributions";
+import { getCommandCenterProviderIcon } from "@/command-center/provider-icon";
 import { encodeImages } from "@/utils/encode-images";
 import type { WorkspaceFileOpenRequest } from "@/workspace/file-open";
 import { shouldAutoFocusWorkspaceDraftComposer } from "@/screens/workspace/workspace-draft-pane-focus";
@@ -375,6 +378,28 @@ export function WorkspaceDraftAgentTab({
   if (!composerState) {
     throw new Error("Workspace draft composer state is required");
   }
+
+  const draftModelActions = useMemo(
+    () =>
+      buildModelChoiceContributions({
+        serverId,
+        providers: composerState.modelSelectorProviders,
+        selectedProvider: composerState.selectedProvider,
+        selectedModelId: composerState.effectiveModelId || null,
+        groupLabel: t("shell.commandCenter.modelGroupLabel"),
+        searchKeywords: t("shell.commandCenter.modelSearchKeywords"),
+        getIcon: getCommandCenterProviderIcon,
+        select: composerState.setProviderAndModelFromUser,
+      }),
+    [
+      composerState.effectiveModelId,
+      composerState.modelSelectorProviders,
+      composerState.selectedProvider,
+      composerState.setProviderAndModelFromUser,
+      serverId,
+      t,
+    ],
+  );
   const clearDraftInput = draftInput.clear;
   const setDraftText = draftInput.setText;
   const setDraftAttachments = draftInput.setAttachments;
@@ -517,6 +542,11 @@ export function WorkspaceDraftAgentTab({
       onCreated(result);
     },
   });
+  useCommandCenterActions({
+    sourceId: `draft:${serverId}:${tabId}`,
+    enabled: isPaneFocused && !isSubmitting,
+    actions: draftModelActions,
+  });
 
   const isReadyForPendingAutoSubmit = Boolean(
     pendingAutoSubmit &&