diff --git a/src/server/workspace-routes.ts b/src/server/workspace-routes.ts
index 82ba5bb..9410d46 100644
--- a/src/server/workspace-routes.ts
+++ b/src/server/workspace-routes.ts
@@ -38,7 +38,7 @@ export function workspaceRoutes(platform: Platform, voice: VoiceService) {
         description: z.string().max(500).default(''),
       })
       .strict()
-      .safeParse(await c.req.json());
+      .safeParse(await c.req.json().catch(() => null));
     if (!data.success)
       return c.json(
         { error: 'Enter a Space name (up to 60 characters).' },
@@ -52,7 +52,7 @@ export function workspaceRoutes(platform: Platform, voice: VoiceService) {
   app.post('/dots', async (c) => {
     const data = dotSchema
       .extend({ spaceId: z.string() })
-      .safeParse(await c.req.json());
+      .safeParse(await c.req.json().catch(() => null));
     if (!data.success)
       return c.json(
         {
@@ -92,7 +92,7 @@ export function workspaceRoutes(platform: Platform, voice: VoiceService) {
     );
   });
   app.put('/dots/:id', async (c) => {
-    const data = dotSchema.safeParse(await c.req.json());
+    const data = dotSchema.safeParse(await c.req.json().catch(() => null));
     if (!data.success)
       return c.json({ error: 'Invalid specialist settings.' }, 400);
     const current = platform.workspace.dot(c.req.param('id'));
@@ -124,7 +124,7 @@ export function workspaceRoutes(platform: Platform, voice: VoiceService) {
         title: z.string().trim().min(1).max(120).default('A new thought'),
       })
       .strict()
-      .safeParse(await c.req.json());
+      .safeParse(await c.req.json().catch(() => null));
     if (!data.success)
       return c.json({ error: 'Select a Dot and a conversation title.' }, 400);
     if (platform.setup().missing.length)
@@ -144,7 +144,7 @@ export function workspaceRoutes(platform: Platform, voice: VoiceService) {
     const data = z
       .object({ threadId: z.string(), sdp: z.string().max(100000) })
       .strict()
-      .safeParse(await c.req.json());
+      .safeParse(await c.req.json().catch(() => null));
     if (!data.success)
       return c.json(
         { error: 'A conversation and audio SDP offer are required.' },
@@ -169,7 +169,7 @@ export function workspaceRoutes(platform: Platform, voice: VoiceService) {
         transcript: z.string().max(12000).default(''),
       })
       .strict()
-      .safeParse(await c.req.json());
+      .safeParse(await c.req.json().catch(() => null));
     if (!data.success)
       return c.json(
         { error: 'A bounded compute request and tool call ID are required.' },
@@ -190,7 +190,7 @@ export function workspaceRoutes(platform: Platform, voice: VoiceService) {
         anchorMessageId: z.string().max(200).optional(),
       })
       .strict()
-      .safeParse(await c.req.json());
+      .safeParse(await c.req.json().catch(() => null));
     if (!data.success)
       return c.json(
         { error: 'Transcript exceeds the 20,000 character limit.' },
@@ -202,6 +202,8 @@ export function workspaceRoutes(platform: Platform, voice: VoiceService) {
   app.all('/copilotkit/*', (c) => platform.handle(c.req.raw));
   app.onError((error, c) => {
     const text = error.message;
+    if (text.startsWith('Space access must include'))
+      return c.json({ error: text }, 400);
     const known =
       /^(Setup|Voice setup|Dot |Space |Specialist |Conversation |Call |This call|End the current|Voice provider|An audio|Intelligence could not)/.test(
         text,
diff --git a/tests/page-routes.test.ts b/tests/page-routes.test.ts
index 9b0f8fe..10d637a 100644
--- a/tests/page-routes.test.ts
+++ b/tests/page-routes.test.ts
@@ -1,4 +1,4 @@
-import { afterEach, expect, it } from 'vitest';
+import { afterEach, expect, it, vi } from 'vitest';
 import { Store } from '../src/server/store.js';
 import { WorkspaceStore } from '../src/server/workspace.js';
 import { Platform } from '../src/server/platform.js';
@@ -221,3 +221,50 @@ it('restores review receipts through the owner API with current thread and Space
   ws.updateDot(dot.id, { ...dot, spaceId: other.id, spaceIds: [other.id] });
   expect((await app.request(`${base}/call`, { headers })).status).toBe(403);
 });
+
+it('answers malformed JSON and invalid Space access with 400 on workspace routes', async () => {
+  const { ws, app } = fixture();
+  const dot = ws.dots()[0];
+  for (const path of ['/api/spaces', '/api/dots', '/api/conversations']) {
+    const response = await app.request(path, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      body: '{',
+    });
+    expect(response.status).toBe(400);
+  }
+  const body = {
+    name: dot.name,
+    instructions: dot.instructions,
+    researchAllowed: true,
+    memoryAllowed: true,
+  };
+  expect(
+    (
+      await app.request(
+        '/api/dots',
+        request({ ...body, spaceId: 'missing-space' }),
+      )
+    ).status,
+  ).toBe(400);
+  expect(
+    (
+      await app.request(
+        `/api/dots/${dot.id}`,
+        request({ ...body, spaceIds: ['missing-space'] }, 'PUT'),
+      )
+    ).status,
+  ).toBe(400);
+});
+
+it('keeps upstream JSON parsing failures on workspace routes as 503', async () => {
+  const { ws, app } = fixture();
+  vi.spyOn(ws, 'createSpace').mockImplementation(() => {
+    throw new SyntaxError('Unexpected token in upstream response');
+  });
+  const response = await app.request(
+    '/api/spaces',
+    request({ name: 'Valid', description: '' }),
+  );
+  expect(response.status).toBe(503);
+});