diff --git a/apps/web/src/components/chat/MarkdownThreadLink.browser.test.tsx b/apps/web/src/components/chat/MarkdownThreadLink.browser.test.tsx
index a379a6afc580..6febe0ff8b34 100644
--- a/apps/web/src/components/chat/MarkdownThreadLink.browser.test.tsx
+++ b/apps/web/src/components/chat/MarkdownThreadLink.browser.test.tsx
@@ -21,6 +21,12 @@ vi.mock(import("../../state/entities"), () => ({
   useProject: (ref: { projectId: string } | null) =>
     ref?.projectId === "essay-project" ? ({ title: "Essays" } as never) : null,
 }));
+vi.mock(import("../../state/environments"), () => ({
+  useEnvironmentIdentities: () => [
+    { environmentId: EnvironmentId.make("environment"), label: "Here" },
+    { environmentId: EnvironmentId.make("remote"), label: "Remote" },
+  ],
+}));
 vi.mock(import("../ProjectFavicon"), () => ({
   ProjectFavicon: () => (
     <span role="img" aria-label="Essays project icon">
@@ -132,3 +138,21 @@ it.each([
     }
   },
 );
+
+it("names a thread on a machine this client has no connection to, without waiting on it", async () => {
+  const { registry } = setup();
+  using _registry = { [Symbol.dispose]: () => registry.dispose() };
+  await using screen = await render(
+    <RegistryContext value={registry}>
+      <MarkdownThreadLink
+        environmentId={EnvironmentId.make("environment")}
+        link={{ environmentId: EnvironmentId.make("peer"), threadId: ThreadId.make("peer-thread") }}
+        label={null}
+      />
+    </RegistryContext>,
+  );
+  await expect
+    .element(screen.getByText("Thread on another machine", { exact: true }))
+    .toBeVisible();
+  await expect.element(screen.getByRole("link")).not.toBeInTheDocument();
+});
diff --git a/apps/web/src/components/chat/MarkdownThreadLink.tsx b/apps/web/src/components/chat/MarkdownThreadLink.tsx
index a88535167db7..9e897f822ef3 100644
--- a/apps/web/src/components/chat/MarkdownThreadLink.tsx
+++ b/apps/web/src/components/chat/MarkdownThreadLink.tsx
@@ -9,6 +9,7 @@ import {
 
 import { configuredHostedAppUrl } from "../../hostedPairing";
 import { useThreadRefs, useThreadShell } from "../../state/entities";
+import { useEnvironmentIdentities } from "../../state/environments";
 import { orchestrationEnvironment } from "../../state/orchestration";
 import { useEnvironmentQuery } from "../../state/query";
 import { UnresolvedChip } from "../contextChipParts";
@@ -23,8 +24,12 @@ export function MarkdownThreadLink(props: {
   const candidates = threadLinkCandidates(props.link, props.environmentId);
   const writtenRef = candidates[0]!;
   const written = useThreadShell(writtenRef);
+  // A linked machine's threads are reachable only through its server, not from this client.
+  const reachable = useEnvironmentIdentities().some(
+    (environment) => environment.environmentId === writtenRef.environmentId,
+  );
   const lookup = useEnvironmentQuery(
-    written === null
+    written === null && reachable
       ? orchestrationEnvironment.threadLinkMetadata({
           environmentId: writtenRef.environmentId,
           input: { threadIds: candidates.map((ref) => ref.threadId) },
@@ -39,7 +44,7 @@ export function MarkdownThreadLink(props: {
           const metadata = lookup.data?.[ref.threadId];
           return metadata ? [{ ref, metadata }] : [];
         })[0] ?? null);
-  const missing = target === null && settled;
+  const missing = target === null && (settled || !reachable);
   const guess = missing && props.link.environmentId === null;
   const refs = useThreadRefs(guess);
   const remoteRef = guess