agent: Remove priority from update_plan (#52320)

## Context

We don't surface this in the UI, so removing it to make the input
smaller.

## Self-Review Checklist

<!-- Check before requesting review: -->
- [x] I've reviewed my own diff for quality, security, and reliability
- [x] Unsafe blocks (if any) have justifying comments
- [x] The content is consistent with the [UI/UX
checklist](https://github.com/zed-industries/zed/blob/main/CONTRIBUTING.md#uiux-checklist)
- [x] Tests cover the new/changed behavior
- [x] Performance impact has been considered and is acceptable

Release Notes:

- N/A

crates/agent/src/tests/mod.rs

@@ -3461,7 +3461,6 @@ async fn test_update_plan_tool_updates_thread_events(cx: &mut TestAppContext) {
             {
                 "step": "Inspect the code",
                 "status": "completed",
-                "priority": "high"
             },
             {
                 "step": "Implement the tool",
@@ -3470,7 +3469,6 @@ async fn test_update_plan_tool_updates_thread_events(cx: &mut TestAppContext) {
             {
                 "step": "Run tests",
                 "status": "pending",
-                "priority": "low"
             }
         ]
     });
@@ -3497,7 +3495,6 @@ async fn test_update_plan_tool_updates_thread_events(cx: &mut TestAppContext) {
                     {
                         "step": "Inspect the code",
                         "status": "completed",
-                        "priority": "high"
                     },
                     {
                         "step": "Implement the tool",
@@ -3506,7 +3503,6 @@ async fn test_update_plan_tool_updates_thread_events(cx: &mut TestAppContext) {
                     {
                         "step": "Run tests",
                         "status": "pending",
-                        "priority": "low"
                     }
                 ]
             }))
@@ -3531,7 +3527,7 @@ async fn test_update_plan_tool_updates_thread_events(cx: &mut TestAppContext) {
         acp::Plan::new(vec![
             acp::PlanEntry::new(
                 "Inspect the code",
-                acp::PlanEntryPriority::High,
+                acp::PlanEntryPriority::Medium,
                 acp::PlanEntryStatus::Completed,
             ),
             acp::PlanEntry::new(
@@ -3541,7 +3537,7 @@ async fn test_update_plan_tool_updates_thread_events(cx: &mut TestAppContext) {
             ),
             acp::PlanEntry::new(
                 "Run tests",
-                acp::PlanEntryPriority::Low,
+                acp::PlanEntryPriority::Medium,
                 acp::PlanEntryStatus::Pending,
             ),
         ])

crates/agent/src/tools/update_plan_tool.rs

@@ -27,45 +27,27 @@ impl From<PlanEntryStatus> for acp::PlanEntryStatus {
     }
 }
 
-#[derive(Debug, Clone, Serialize, Deserialize, JsonSchema, PartialEq, Eq, Default)]
-#[serde(rename_all = "snake_case")]
-#[schemars(inline)]
-pub enum PlanEntryPriority {
-    High,
-    #[default]
-    Medium,
-    Low,
-}
-
-impl From<PlanEntryPriority> for acp::PlanEntryPriority {
-    fn from(value: PlanEntryPriority) -> Self {
-        match value {
-            PlanEntryPriority::High => acp::PlanEntryPriority::High,
-            PlanEntryPriority::Medium => acp::PlanEntryPriority::Medium,
-            PlanEntryPriority::Low => acp::PlanEntryPriority::Low,
-        }
-    }
-}
-
 #[derive(Debug, Clone, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
 pub struct PlanItem {
     /// Human-readable description of what this task aims to accomplish.
     pub step: String,
     /// The current status of this task.
     pub status: PlanEntryStatus,
-    /// The relative importance of this task. Defaults to medium when omitted.
-    #[serde(default)]
-    pub priority: PlanEntryPriority,
 }
 
 impl From<PlanItem> for acp::PlanEntry {
     fn from(value: PlanItem) -> Self {
-        acp::PlanEntry::new(value.step, value.priority.into(), value.status.into())
+        acp::PlanEntry::new(
+            value.step,
+            acp::PlanEntryPriority::Medium,
+            value.status.into(),
+        )
     }
 }
 
 /// Updates the task plan.
-/// Provide a list of plan entries, each with step, status, and optional priority.
+///
+/// Provide a list of plan entries, each with a step and status.
 #[derive(Debug, Clone, Serialize, Deserialize, JsonSchema, PartialEq, Eq)]
 pub struct UpdatePlanToolInput {
     /// The list of plan entries and their current statuses.
@@ -144,17 +126,14 @@ mod tests {
                 PlanItem {
                     step: "Inspect the existing tool wiring".to_string(),
                     status: PlanEntryStatus::Completed,
-                    priority: PlanEntryPriority::High,
                 },
                 PlanItem {
                     step: "Implement the update_plan tool".to_string(),
                     status: PlanEntryStatus::InProgress,
-                    priority: PlanEntryPriority::Medium,
                 },
                 PlanItem {
                     step: "Add tests".to_string(),
                     status: PlanEntryStatus::Pending,
-                    priority: PlanEntryPriority::Low,
                 },
             ],
         }
@@ -179,7 +158,7 @@ mod tests {
             acp::Plan::new(vec![
                 acp::PlanEntry::new(
                     "Inspect the existing tool wiring",
-                    acp::PlanEntryPriority::High,
+                    acp::PlanEntryPriority::Medium,
                     acp::PlanEntryStatus::Completed,
                 ),
                 acp::PlanEntry::new(
@@ -189,7 +168,7 @@ mod tests {
                 ),
                 acp::PlanEntry::new(
                     "Add tests",
-                    acp::PlanEntryPriority::Low,
+                    acp::PlanEntryPriority::Medium,
                     acp::PlanEntryStatus::Pending,
                 ),
             ])
@@ -214,7 +193,7 @@ mod tests {
             acp::Plan::new(vec![
                 acp::PlanEntry::new(
                     "Inspect the existing tool wiring",
-                    acp::PlanEntryPriority::High,
+                    acp::PlanEntryPriority::Medium,
                     acp::PlanEntryStatus::Completed,
                 ),
                 acp::PlanEntry::new(
@@ -224,58 +203,13 @@ mod tests {
                 ),
                 acp::PlanEntry::new(
                     "Add tests",
-                    acp::PlanEntryPriority::Low,
+                    acp::PlanEntryPriority::Medium,
                     acp::PlanEntryStatus::Pending,
                 ),
             ])
         );
     }
 
-    #[gpui::test]
-    async fn test_run_defaults_priority_to_medium(cx: &mut TestAppContext) {
-        let tool = Arc::new(UpdatePlanTool);
-        let (event_stream, mut event_rx) = ToolCallEventStream::test();
-
-        let input = UpdatePlanToolInput {
-            plan: vec![
-                PlanItem {
-                    step: "First".to_string(),
-                    status: PlanEntryStatus::InProgress,
-                    priority: PlanEntryPriority::default(),
-                },
-                PlanItem {
-                    step: "Second".to_string(),
-                    status: PlanEntryStatus::InProgress,
-                    priority: PlanEntryPriority::default(),
-                },
-            ],
-        };
-
-        let result = cx
-            .update(|cx| tool.run(ToolInput::resolved(input), event_stream, cx))
-            .await
-            .expect("tool should succeed");
-
-        assert_eq!(result, "Plan updated".to_string());
-
-        let plan = event_rx.expect_plan().await;
-        assert_eq!(
-            plan,
-            acp::Plan::new(vec![
-                acp::PlanEntry::new(
-                    "First",
-                    acp::PlanEntryPriority::Medium,
-                    acp::PlanEntryStatus::InProgress,
-                ),
-                acp::PlanEntry::new(
-                    "Second",
-                    acp::PlanEntryPriority::Medium,
-                    acp::PlanEntryStatus::InProgress,
-                ),
-            ])
-        );
-    }
-
     #[gpui::test]
     async fn test_initial_title(cx: &mut TestAppContext) {
         let tool = UpdatePlanTool;