feat: establish unified administration and model context baseline

frontend/src/shell/database-management/FleetLedgerShell.tsx

@@ -2,6 +2,7 @@ import { forwardRef, useId, useState, type ReactNode } from "react"
 import { ArrowLeft, ChevronRight } from "lucide-react"
 
 import { Button } from "../../components/ui/button"
+import { AdministrationHeader } from "../administration/AdministrationPage"
 import {
   WorkAreaPanel,
   WorkAreaPanelHostProvider,
@@ -117,17 +118,13 @@ export function FleetLedgerHeader({
   className,
 }: FleetLedgerHeaderProps) {
   return (
-    <header className={classes("thot-fleet-ledger__header", className)}>
-      <div className="thot-fleet-ledger__heading-copy">
-        <h1 className="thot-fleet-ledger__title">{title}</h1>
-      </div>
-      {status ? <div className="thot-fleet-ledger__header-status">{status}</div> : null}
-      {actions ? (
-        <div className="thot-fleet-ledger__header-actions" role="group" aria-label={actionsLabel}>
+    <div className={className}>
+      <AdministrationHeader title={title} description="Configure database connections, synchronize schema and curate the catalog." />
+      <div className="thot-fleet-ledger__header-status">{status}</div>
+      {actions && <div className="thot-administration-toolbar" role="group" aria-label={actionsLabel}>
           {actions}
-        </div>
-      ) : null}
-    </header>
+      </div>}
+    </div>
   )
 }
 

frontend/src/shell/database-management/MetadataGenerationModelSelector.tsx

@@ -1,4 +1,5 @@
 import { useId } from "react";
+import { useWorkingContextScope } from "../../workspaces/WorkingContext";
 import type { MetadataGenerationModels } from "../../api/catalog-databases";
 
 export const NO_METADATA_GENERATION_LLM_MODEL_MESSAGE =
@@ -24,16 +25,19 @@ export function MetadataGenerationModelSelector({
   variant = "default",
 }: Props) {
   const helpId = useId();
+  const workingContext = useWorkingContextScope();
+  if (workingContext) return null;
   const models = data?.models ?? [];
   const configuredDefault = data?.default ?? "";
   const hasUsableDefault = configuredDefault !== ""
     && models.some((model) => model.id === configuredDefault);
   const noUsableModel = !isLoading && !isError && Boolean(data) && !hasUsableDefault;
+  const staleSelection = Boolean(selectedModel) && !models.some((model) => model.id === selectedModel);
   const unavailableMessage = !isLoading && isError
-    ? "Metadata-generation LLM model choices are unavailable."
+    ? "Global LLM model choices are unavailable."
     : noUsableModel
       ? NO_METADATA_GENERATION_LLM_MODEL_MESSAGE
-      : null;
+      : staleSelection ? "The global LLM model is unavailable. Choose a configured model; no fallback is applied." : null;
   const compact = variant === "compact";
 
   return (
@@ -45,15 +49,16 @@ export function MetadataGenerationModelSelector({
         ? "flex min-w-0 items-center gap-2 text-xs font-medium text-foreground"
         : "grid gap-1.5 text-xs font-medium text-foreground"}
       >
-        <span className={compact ? "whitespace-nowrap" : undefined}>Metadata-generation LLM model</span>
+        <span className={compact ? "whitespace-nowrap" : undefined}>Global LLM model</span>
         <select
           className={`${compact ? "h-8 min-w-52" : "h-9 w-full"} rounded-md border border-input bg-card px-3 text-sm outline-none transition focus:border-primary/60 focus:ring-3 focus:ring-ring/15 disabled:bg-muted disabled:text-muted-foreground`}
-          aria-label="Metadata-generation LLM model"
+          aria-label="Global LLM model"
           aria-describedby={unavailableMessage ? helpId : undefined}
           value={selectedModel}
           disabled={!canManage || isLoading || isError || !hasUsableDefault}
           onChange={(event) => onSelectedModelChange(event.target.value)}
         >
+          {staleSelection && <option value={selectedModel}>{selectedModel} (unavailable)</option>}
           {isLoading ? <option value="">Loading models…</option> : null}
           {!isLoading && isError ? <option value="">Model choices unavailable</option> : null}
           {noUsableModel ? (
@@ -64,6 +69,7 @@ export function MetadataGenerationModelSelector({
           ))}
         </select>
       </label>
+      <span className="text-xs text-muted-foreground">Shared with Core and all workspaces.</span>
       {unavailableMessage ? (
         <p id={helpId} className="max-w-72 text-xs font-normal leading-4 text-muted-foreground">
           {unavailableMessage}