Bound a single contract-preview status attempt via AttemptTimeoutLayer

Mirrors WHOAMI_ATTEMPT_TIMEOUT: an inner per-attempt timeout layered under
PollRetryPolicy's overall poll budget, so one hung status check can't
consume checks_timeout_seconds in a single attempt. A timed-out attempt
maps to `false` (not finished) rather than an error, so PollRetryPolicy
just polls again on the normal schedule.

Author: sirdodger

crates/rover-client/src/operations/contract/preview/mod.rs

@@ -3,13 +3,19 @@ mod types;
 
 use std::time::Duration;
 
-use rover_tower::poll_retry::PollRetryPolicy;
+use rover_tower::{attempt_timeout::AttemptTimeoutLayer, poll_retry::PollRetryPolicy};
 pub use service::{ContractPreviewResult, ContractPreviewStart};
 use tower::{Service, ServiceBuilder, ServiceExt};
 pub use types::*;
 
 use crate::{blocking::StudioClient, RoverClientError};
 
+/// Bounds a single status-check attempt, independent of the overall poll
+/// budget (`checks_timeout_seconds`) -- mirrors `WHOAMI_ATTEMPT_TIMEOUT` in
+/// `command::auth::whoami`: reusing the overall budget here would let one
+/// hung attempt consume the whole thing, leaving no room to poll again.
+const CONTRACT_PREVIEW_STATUS_ATTEMPT_TIMEOUT: Duration = Duration::from_secs(10);
+
 /// Start an async contract preview job, returning its (pending) status
 /// immediately.
 pub async fn start(
@@ -58,6 +64,10 @@ pub async fn poll(
                 }
             },
         ))
+        .layer(AttemptTimeoutLayer::new(
+            CONTRACT_PREVIEW_STATUS_ATTEMPT_TIMEOUT,
+            || false,
+        ))
         .service(service::ContractPreviewStatus::new(
             client
                 .studio_graphql_service()