feat: pin sessions to workspace revisions

frontend/src/shell/SteerInput.tsx

@@ -1,13 +1,14 @@
 // frontend/src/shell/SteerInput.tsx
 import { useEffect, useRef, useState } from "react";
 import { CornerDownLeft } from "lucide-react";
-import { useQuery, useQueryClient } from "@tanstack/react-query";
+import { useQuery } from "@tanstack/react-query";
 import { postSteer, createSession } from "../api/sessions";
 import { ApiError } from "../api/client";
-import { getSettings, putSettings, type Settings } from "../api/settings";
+import { getSettings } from "../api/settings";
 import { listWorkspaces } from "../api/workspaces";
 import { listModels } from "../api/models";
 import { useSessionStore } from "../store/sessionStore";
+import { workspacePreferences, type WorkspacePreference } from "../workspaces/preferences";
 
 const THINKING_LEVELS = ["low", "medium", "high"] as const;
 
@@ -151,25 +152,33 @@ export function SteerInput({
 
 /**
  * Status strip beneath the composer. Left: the active workspace selector.
- * Right: live context usage plus model + thinking-level selectors (these replace
- * the old Settings dialog and persist through PUT /settings).
+ * Right: live context usage plus browser-local workspace/model/thinking selectors.
  */
 export function ComposerFooter() {
-  const qc = useQueryClient();
   const { data: settings } = useQuery({ queryKey: ["settings"], queryFn: getSettings });
   const { data: workspaces = [] } = useQuery({ queryKey: ["workspaces"], queryFn: listWorkspaces });
   const { data: modelsData } = useQuery({ queryKey: ["models"], queryFn: listModels });
   const models = modelsData?.models ?? [];
   const tokenUsage = useSessionStore((state) => state.tokenUsage);
+  const [preferences, setPreferences] = useState<WorkspacePreference>(() => workspacePreferences.load());
 
-  const workspace = settings?.workspace ?? "";
-  const model = settings?.model ?? "";
-  const thinking = settings?.thinking ?? "medium";
+  useEffect(() => {
+    if (!settings) return;
+    setPreferences(workspacePreferences.migrate({
+      workspaceId: settings.workspace,
+      provider: settings.provider,
+      model: settings.model,
+      thinking: settings.thinking,
+    }));
+  }, [settings]);
 
-  // PUT /settings replaces the whole object, so always send the merged settings.
-  async function update(patch: Partial<Settings>) {
-    await putSettings({ workspace, provider: settings?.provider, model, thinking, ...patch });
-    qc.invalidateQueries({ queryKey: ["settings"] });
+  const workspace = preferences.workspaceId ?? settings?.workspace ?? "";
+  const model = preferences.model ?? settings?.model ?? "";
+  const thinking = preferences.thinking ?? settings?.thinking ?? "medium";
+
+  function update(patch: WorkspacePreference) {
+    const next = workspacePreferences.save({ ...preferences, ...patch });
+    setPreferences(next);
   }
 
   function onModelChange(id: string) {
@@ -185,7 +194,7 @@ export function ComposerFooter() {
   return (
     <div className="flex items-center justify-between gap-2 border-t border-border/60 px-3 py-1.5">
       <div className="flex items-center gap-2">
-        <FooterSelect aria-label="Workspace" value={workspace} onChange={(v) => update({ workspace: v })}>
+        <FooterSelect aria-label="Workspace" value={workspace} onChange={(v) => update({ workspaceId: v })}>
           {workspaces.length === 0 ? (
             <option value="">— workspace —</option>
           ) : (