diff --git a/packages/ssh/src/tunnel.test.ts b/packages/ssh/src/tunnel.test.ts
index 461509ea0ad2..a585ec3fbdd2 100644
--- a/packages/ssh/src/tunnel.test.ts
+++ b/packages/ssh/src/tunnel.test.ts
@@ -23,6 +23,7 @@ import {
   launchOrReuseRemoteServer,
   REMOTE_PICK_PORT_SCRIPT,
   SshEnvironmentManager,
+  SSH_TUNNEL_READY_PROBE_TIMEOUT_MS,
   waitForHttpReady,
 } from "./tunnel.ts";
 
@@ -310,6 +311,37 @@ describe("ssh tunnel scripts", () => {
     ),
   );
 
+  const slowHttpClient = HttpClient.make((request) =>
+    Effect.succeed(HttpClientResponse.fromWeb(request, new Response("", { status: 200 }))).pipe(
+      Effect.delay(Duration.millis(1_500)),
+    ),
+  );
+
+  it.effect(
+    "succeeds on a single response slower than 1s using the tunnel probe bound, so a high-RTT link only makes readiness slower, not impossible",
+    () =>
+      Effect.gen(function* () {
+        const fiber = yield* Effect.forkChild(
+          Effect.result(
+            waitForHttpReady({
+              baseUrl: "http://127.0.0.1:41773/",
+              timeoutMs: 5_000,
+              probeTimeoutMs: SSH_TUNNEL_READY_PROBE_TIMEOUT_MS,
+            }),
+          ),
+        );
+        yield* Effect.yieldNow;
+        yield* TestClock.adjust(Duration.millis(5_000));
+
+        const result = yield* Fiber.join(fiber);
+        assert.isTrue(Result.isSuccess(result));
+      }).pipe(
+        Effect.provide(
+          Layer.merge(TestClock.layer(), Layer.succeed(HttpClient.HttpClient, slowHttpClient)),
+        ),
+      ),
+  );
+
   it("preserves primitive readiness reason values in diagnostic output", () => {
     assert.deepEqual(
       describeReadinessCause({
diff --git a/packages/ssh/src/tunnel.ts b/packages/ssh/src/tunnel.ts
index 12ab0027803c..8959edcc2dbc 100644
--- a/packages/ssh/src/tunnel.ts
+++ b/packages/ssh/src/tunnel.ts
@@ -52,7 +52,24 @@ import {
 export const DEFAULT_REMOTE_PORT = 3773;
 const REMOTE_PORT_SCAN_WINDOW = 200;
 const SSH_READY_TIMEOUT_MS = 20_000;
+// Default probe bound for waitForHttpReady, and the value fed to the
+// remote-side scripts' own loopback probe (T3_READY_PROBE_TIMEOUT_MS). That
+// remote probe's deadline loop (REMOTE_WAIT_READY_SCRIPT) only checks its
+// overall deadline *between* attempts — a single in-flight probe isn't
+// interrupted when the deadline passes — so this must stay comfortably under
+// REMOTE_REUSE_READY_TIMEOUT_MS (2s) or one slow attempt can blow through the
+// whole reuse-check budget. It never needs to be larger: this probe is always
+// loopback on the remote host, with no RTT to account for.
 const SSH_READY_PROBE_TIMEOUT_MS = 1_000;
+// Bound for the desktop-side probe that crosses the real SSH link (desktop ->
+// tunnel -> remote), used only at the initial-connect readiness check below.
+// On a high-RTT connection (satellite/in-flight wifi) a single request can
+// legitimately take longer than a typical LAN round trip. Safe to set well
+// above any of the timeouts above: unlike the remote script's loop, Effect's
+// own timeoutOption (in the shared waitForHttpReady) genuinely interrupts an
+// in-flight request once its outer deadline elapses, so this can't make a
+// short outer timeoutMs elsewhere overshoot.
+export const SSH_TUNNEL_READY_PROBE_TIMEOUT_MS = 8_000;
 const TUNNEL_SHUTDOWN_TIMEOUT_MS = 2_000;
 const REMOTE_READY_TIMEOUT_MS = 60_000;
 const REMOTE_LAUNCH_TIMEOUT_MS = 90_000;
@@ -1100,6 +1117,7 @@ const startSshTunnel = Effect.fn("ssh/tunnel.startSshTunnel")(function* (input:
     waitForHttpReady({
       baseUrl: input.httpBaseUrl,
       timeoutMs: SSH_READY_TIMEOUT_MS,
+      probeTimeoutMs: SSH_TUNNEL_READY_PROBE_TIMEOUT_MS,
     }),
     exitFailure,
   ).pipe(