chore(fleet): satisfy lint cleanups

Keep fleet protocol and manager cleanup warning-clean with derived defaults, boxed task-spec parsing, and collapsed control flow.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/protocol/src/fleet.rs

@@ -317,11 +317,12 @@ pub enum FleetHostSpec {
 /// The trust level determines what a worker is allowed to do and what
 /// secrets it may access. The default for new workers is [`FleetTrustLevel::Sandbox`];
 /// operators must explicitly raise trust for SSH or container workers.
-#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord)]
+#[derive(Debug, Clone, Copy, Serialize, Deserialize, PartialEq, Eq, PartialOrd, Ord, Default)]
 #[serde(rename_all = "snake_case")]
 pub enum FleetTrustLevel {
     /// Fully isolated: no network, no secrets, no writes outside `.codewhale/fleet/`.
     /// Suitable for untrusted code review, community PR checks, or third-party tool runs.
+    #[default]
     Sandbox = 0,
     /// Local-only worker with access to the workspace and configured secrets.
     /// Default for local workers. May read repo files but writes are gated.
@@ -337,12 +338,6 @@ pub enum FleetTrustLevel {
     Operator = 3,
 }
 
-impl Default for FleetTrustLevel {
-    fn default() -> Self {
-        Self::Sandbox
-    }
-}
-
 impl FleetTrustLevel {
     /// Whether this trust level is allowed to access provider secrets.
     #[must_use]

crates/tui/src/fleet/manager.rs

@@ -652,8 +652,9 @@ impl FleetManager {
 
         // Register with the sub-agent manager for headless worker tracking.
         // The engine's agent_open path handles actual sub-agent spawning.
-        if let Some(ref mgr) = self.sub_agent_manager {
-            if let Ok(guard) = mgr.try_write() {
+        if let Some(ref mgr) = self.sub_agent_manager
+            && let Ok(guard) = mgr.try_write()
+        {
             let run = self
                 .ledger
                 .rebuild_state()
@@ -686,7 +687,6 @@ impl FleetManager {
                 guard.register_worker(worker);
             }
         }
-        }
 
         Ok(())
     }

crates/tui/src/fleet/scheduler.rs

@@ -178,10 +178,7 @@ impl FleetScheduler {
         worker_id: &str,
         report: &mut FleetSchedulerReport,
     ) -> Result<()> {
-        let retry_policy = task_spec
-            .retry_policy
-            .clone()
-            .unwrap_or_else(FleetRetryPolicy::default);
+        let retry_policy = task_spec.retry_policy.clone().unwrap_or_default();
         if task.entry.attempts < retry_policy.max_attempts {
             let lease_expires_at = self.lease_expires_at();
             self.ledger.lease_task(
@@ -342,8 +339,8 @@ impl FleetScheduler {
     }
 
     fn task_is_stale(&self, task: &FleetTaskState, state: &FleetLedgerState) -> bool {
-        if let Some(worker_id) = task.leased_to.as_deref() {
-            if let Some(heartbeat) = state.heartbeats.get(worker_id)
+        if let Some(worker_id) = task.leased_to.as_deref()
+            && let Some(heartbeat) = state.heartbeats.get(worker_id)
             && let Ok(last) = DateTime::parse_from_rfc3339(&heartbeat.timestamp)
         {
             let age = self.now.signed_duration_since(last.with_timezone(&Utc));
@@ -351,7 +348,6 @@ impl FleetScheduler {
                 .to_std()
                 .map_or(true, |age| age > self.policy.heartbeat_timeout);
         }
-        }
         if let Some(deadline) = task.entry.lease_deadline.as_deref()
             && let Ok(deadline) = DateTime::parse_from_rfc3339(deadline)
         {

crates/tui/src/fleet/task_spec.rs

@@ -37,7 +37,7 @@ pub struct FleetTaskSpecDocument {
 enum FleetTaskSpecFile {
     Document(FleetTaskSpecDocument),
     Tasks(Vec<FleetTaskSpec>),
-    Single(FleetTaskSpec),
+    Single(Box<FleetTaskSpec>),
 }
 
 impl FleetTaskSpecFile {
@@ -61,7 +61,7 @@ impl FleetTaskSpecFile {
                 labels: BTreeMap::new(),
                 security_policy: None,
                 workers: Vec::new(),
-                tasks: vec![task],
+                tasks: vec![*task],
             },
         }
     }
@@ -133,6 +133,7 @@ pub fn validate_task_spec_document(doc: &FleetTaskSpecDocument) -> Result<()> {
     Ok(())
 }
 
+#[allow(clippy::too_many_arguments)]
 pub fn write_fleet_artifact_ref(
     workspace: &Path,
     run_id: &FleetRunId,