diff --git a/canvas/src/components/MemoryInspectorPanel.tsx b/canvas/src/components/MemoryInspectorPanel.tsx
index 7353086f..0f62d5af 100644
--- a/canvas/src/components/MemoryInspectorPanel.tsx
+++ b/canvas/src/components/MemoryInspectorPanel.tsx
@@ -57,8 +57,12 @@ export interface MemoryV2 {
   created_at: string;
   /** 0..1 plugin similarity score; only present when ?q= is set. */
   score?: number | null;
-  /** workspace_id of the peer that originated this memory if propagation is in play. */
-  source_workspace_id?: string;
+  // Note: an earlier iteration of this type carried a `source_workspace_id`
+  // field rendered as a "from peer" badge. The propagation contract that
+  // would have populated it ("Reserved for future cross-namespace
+  // propagation semantics" in memory-plugin-v1.yaml) is unimplemented —
+  // nothing in the codebase writes that key. Removed in self-review.
+  // Re-add when propagation gains a concrete shape.
 }
 
 interface MemoriesResponse {
@@ -83,6 +87,24 @@ function sanitizeId(id: string): string {
   return id.replace(/[^a-zA-Z0-9]/g, '-');
 }
 
+/**
+ * Detect a memory-plugin-503 error from the api wrapper's stringified
+ * Error message. Matches on the literal env-var name rather than the
+ * status code, because the api shim renders status codes inside a
+ * larger formatted message and a future status-code reformat would
+ * silently break the detection.
+ *
+ * The substring `MEMORY_PLUGIN_URL` is hard-coded in the handler at
+ * `workspace-server/internal/handlers/memories_v2.go:available()`,
+ * so this is a pinned cross-layer contract — drift is caught by both
+ * the Go test (TestMemoriesV2_PluginUnwired_All503) and the canvas
+ * test (TestMemoryInspectorPanel — plugin unavailable).
+ */
+export function isPluginUnavailableError(err: unknown): boolean {
+  const msg = err instanceof Error ? err.message : '';
+  return msg.includes('MEMORY_PLUGIN_URL');
+}
+
 function formatRelativeTime(iso: string): string {
   const diff = Date.now() - new Date(iso).getTime();
   if (diff < 60_000) return `${Math.floor(diff / 1000)}s`;
@@ -169,11 +191,10 @@ export function MemoryInspectorPanel({ workspaceId }: Props) {
       setNamespaces(data);
       setPluginUnavailable(false);
     } catch (e) {
-      // 503 indicates the plugin isn't wired. Surface it specially —
-      // anything else stays as a generic load failure that the
+      // Plugin-unavailable (503) indicates MEMORY_PLUGIN_URL isn't set.
+      // Anything else stays as a generic load failure that the
       // entries-load path will also flag.
-      const msg = e instanceof Error ? e.message : '';
-      if (msg.includes('503') || msg.toLowerCase().includes('plugin is not configured')) {
+      if (isPluginUnavailableError(e)) {
         setPluginUnavailable(true);
       }
       setNamespaces({ readable: [], writable: [] });
@@ -205,12 +226,11 @@ export function MemoryInspectorPanel({ workspaceId }: Props) {
         : data.memories;
       setEntries(sorted);
     } catch (e) {
-      const msg = e instanceof Error ? e.message : 'Failed to load memories';
-      if (msg.includes('503') || msg.toLowerCase().includes('plugin is not configured')) {
+      if (isPluginUnavailableError(e)) {
         setPluginUnavailable(true);
         setError(null); // surfaced via banner, not row error
       } else {
-        setError(msg);
+        setError(e instanceof Error ? e.message : 'Failed to load memories');
       }
       setEntries([]);
     } finally {
@@ -578,16 +598,6 @@ function MemoryEntryRow({ entry, onDelete }: MemoryEntryRowProps) {
           </span>
         )}
 
-        {/* Source workspace badge (propagated memory) */}
-        {entry.source_workspace_id && (
-          <span
-            className="text-[9px] shrink-0 font-mono text-violet-400"
-            title={`From: ${entry.source_workspace_id}`}
-            data-testid="source-workspace-badge"
-          >
-            ⇡{entry.source_workspace_id.slice(0, 6)}
-          </span>
-        )}
 
         <span className="text-[9px] text-ink-soft shrink-0">
           {formatRelativeTime(entry.created_at)}
diff --git a/canvas/src/components/__tests__/MemoryInspectorPanel.test.tsx b/canvas/src/components/__tests__/MemoryInspectorPanel.test.tsx
index 9b93ee14..0111451f 100644
--- a/canvas/src/components/__tests__/MemoryInspectorPanel.test.tsx
+++ b/canvas/src/components/__tests__/MemoryInspectorPanel.test.tsx
@@ -13,7 +13,7 @@
  *   - Search results sort by score descending
  *   - Empty-state copy differs by query / plugin-state / no-data
  *   - Per-row badges render (kind / source / pin / TTL / score /
- *     source_workspace_id) and TTL countdown handles past/future/null
+ *     score) and TTL countdown handles past/future/null
  *   - Delete (Forget) flow: optimistic removal, confirmation dialog,
  *     server failure rolls back via reload
  *   - formatTTL helper covers s/m/h/d/expired/null/invalid branches
@@ -61,6 +61,7 @@ import { api } from '@/lib/api';
 import {
   MemoryInspectorPanel,
   formatTTL,
+  isPluginUnavailableError,
   type MemoryV2,
   type NamespacesResponse,
 } from '../MemoryInspectorPanel';
@@ -99,14 +100,13 @@ const MEM_PINNED: MemoryV2 = {
   created_at: '2026-04-17T12:00:00.000Z',
 };
 
-const MEM_PROPAGATED: MemoryV2 = {
-  id: 'mem-from-peer',
+const MEM_RUNTIME_CHECKPOINT: MemoryV2 = {
+  id: 'mem-checkpoint',
   namespace: 'team:t-1',
-  content: 'Cross-workspace fact',
+  content: 'Runtime checkpoint',
   kind: 'checkpoint',
   source: 'runtime',
   pin: false,
-  source_workspace_id: 'ws-peer-99',
   created_at: '2026-04-17T12:00:00.000Z',
 };
 
@@ -142,6 +142,33 @@ function stubFetch(memories: MemoryV2[], namespaces: NamespacesResponse = NS_RES
   }) as typeof api.get);
 }
 
+// ── isPluginUnavailableError helper ─────────────────────────────────────────
+
+describe('isPluginUnavailableError', () => {
+  it('matches the literal env var contract from the server handler', () => {
+    expect(
+      isPluginUnavailableError(
+        new Error('API GET /workspaces/x/v2/memories: 503 {"error":"memory plugin is not configured (set MEMORY_PLUGIN_URL)"}'),
+      ),
+    ).toBe(true);
+  });
+
+  it('does not false-match on generic 503 errors that don\'t mention the env var', () => {
+    expect(isPluginUnavailableError(new Error('API GET /foo: 503 something else'))).toBe(false);
+  });
+
+  it('does not false-match on plain 4xx errors', () => {
+    expect(isPluginUnavailableError(new Error('API GET /foo: 401 unauthorized'))).toBe(false);
+  });
+
+  it('returns false for non-Error inputs', () => {
+    expect(isPluginUnavailableError(null)).toBe(false);
+    expect(isPluginUnavailableError(undefined)).toBe(false);
+    expect(isPluginUnavailableError('a string')).toBe(false);
+    expect(isPluginUnavailableError({ message: 'MEMORY_PLUGIN_URL' })).toBe(false);
+  });
+});
+
 // ── formatTTL helper ─────────────────────────────────────────────────────────
 
 describe('formatTTL', () => {
@@ -242,7 +269,7 @@ describe('MemoryInspectorPanel — plugin unavailable', () => {
   });
 
   it('shows the empty-state explaining plugin disabled', async () => {
-    mockGet.mockRejectedValue(new Error('HTTP 503'));
+    mockGet.mockRejectedValue(new Error('API GET /workspaces/x/v2/memories: 503 {"error":"memory plugin is not configured (set MEMORY_PLUGIN_URL)"}'));
     render(<MemoryInspectorPanel workspaceId="ws-1" />);
     await waitFor(() => screen.getByText(/Memory plugin disabled/i));
   });
@@ -346,8 +373,8 @@ describe('MemoryInspectorPanel — search', () => {
 // ── Per-row badges ───────────────────────────────────────────────────────────
 
 describe('MemoryInspectorPanel — row badges', () => {
-  it('renders kind, source, pin, TTL, source-workspace badges per shape', async () => {
-    stubFetch([MEM_PINNED, MEM_PROPAGATED]);
+  it('renders kind, source, pin, TTL badges per shape', async () => {
+    stubFetch([MEM_PINNED, MEM_RUNTIME_CHECKPOINT]);
     render(<MemoryInspectorPanel workspaceId="ws-1" />);
 
     await waitFor(() => {
@@ -357,15 +384,13 @@ describe('MemoryInspectorPanel — row badges', () => {
       expect(pinnedRow.querySelector('[data-testid="source-badge"]')?.textContent).toBe('user');
       expect(pinnedRow.querySelector('[data-testid="pin-badge"]')).toBeTruthy();
       expect(pinnedRow.querySelector('[data-testid="ttl-badge"]')?.textContent).toMatch(/^⌛\d+[hd]$/);
-      expect(pinnedRow.querySelector('[data-testid="source-workspace-badge"]')).toBeNull();
 
-      // Propagated memory: kind=checkpoint, source=runtime, no pin, no TTL, source_workspace
-      const propRow = screen.getByTestId('memory-row-mem-from-peer');
+      // Checkpoint memory: kind=checkpoint, source=runtime, no pin, no TTL
+      const propRow = screen.getByTestId('memory-row-mem-checkpoint');
       expect(propRow.querySelector('[data-testid="kind-badge"]')?.textContent).toBe('C');
       expect(propRow.querySelector('[data-testid="source-badge"]')?.textContent).toBe('runtime');
       expect(propRow.querySelector('[data-testid="pin-badge"]')).toBeNull();
       expect(propRow.querySelector('[data-testid="ttl-badge"]')).toBeNull();
-      expect(propRow.querySelector('[data-testid="source-workspace-badge"]')?.textContent).toMatch(/^⇡ws-pee/);
     });
   });