Add goal app-server API (2 / 5) (#18074)

Adds the app-server v2 goal API on top of the persisted goal state from
PR 1.

## Why

Clients need a stable app-server surface for reading and controlling
materialized thread goals before the model tools and TUI can use them.
Goal changes also need to be observable by app-server clients, including
clients that resume an existing thread.

## What changed

- Added v2 `thread/goal/get`, `thread/goal/set`, and `thread/goal/clear`
RPCs for materialized threads.
- Added `thread/goal/updated` and `thread/goal/cleared` notifications so
clients can keep local goal state in sync.
- Added resume/snapshot wiring so reconnecting clients see the current
goal state for a thread.
- Added app-server handlers that reconcile persisted rollout state
before direct goal mutations.
- Updated the app-server README plus generated JSON and TypeScript
schema fixtures for the new API surface.

## Verification

- Added app-server v2 coverage for goal get/set/clear behavior,
notification emission, resume snapshots, and non-local thread-store
interactions.

codex-rs/app-server-protocol/src/protocol/v2.rs

@@ -96,6 +96,7 @@ use codex_protocol::protocol::SkillMetadata as CoreSkillMetadata;
 use codex_protocol::protocol::SkillScope as CoreSkillScope;
 use codex_protocol::protocol::SkillToolDependency as CoreSkillToolDependency;
 use codex_protocol::protocol::SubAgentSource as CoreSubAgentSource;
+use codex_protocol::protocol::ThreadGoalStatus as CoreThreadGoalStatus;
 use codex_protocol::protocol::TokenUsage as CoreTokenUsage;
 use codex_protocol::protocol::TokenUsageInfo as CoreTokenUsageInfo;
 use codex_protocol::request_permissions::PermissionGrantScope as CorePermissionGrantScope;
@@ -3747,6 +3748,103 @@ pub struct ThreadUnarchiveParams {
 #[ts(export_to = "v2/")]
 pub struct ThreadSetNameResponse {}
 
+v2_enum_from_core! {
+    pub enum ThreadGoalStatus from CoreThreadGoalStatus {
+        Active,
+        Paused,
+        BudgetLimited,
+        Complete,
+    }
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadGoal {
+    pub thread_id: String,
+    pub objective: String,
+    pub status: ThreadGoalStatus,
+    #[ts(type = "number | null")]
+    pub token_budget: Option<i64>,
+    #[ts(type = "number")]
+    pub tokens_used: i64,
+    #[ts(type = "number")]
+    pub time_used_seconds: i64,
+    #[ts(type = "number")]
+    pub created_at: i64,
+    #[ts(type = "number")]
+    pub updated_at: i64,
+}
+
+impl From<codex_protocol::protocol::ThreadGoal> for ThreadGoal {
+    fn from(value: codex_protocol::protocol::ThreadGoal) -> Self {
+        Self {
+            thread_id: value.thread_id.to_string(),
+            objective: value.objective,
+            status: value.status.into(),
+            token_budget: value.token_budget,
+            tokens_used: value.tokens_used,
+            time_used_seconds: value.time_used_seconds,
+            created_at: value.created_at,
+            updated_at: value.updated_at,
+        }
+    }
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadGoalSetParams {
+    pub thread_id: String,
+    #[ts(optional = nullable)]
+    pub objective: Option<String>,
+    #[ts(optional = nullable)]
+    pub status: Option<ThreadGoalStatus>,
+    #[serde(
+        default,
+        deserialize_with = "super::serde_helpers::deserialize_double_option",
+        serialize_with = "super::serde_helpers::serialize_double_option",
+        skip_serializing_if = "Option::is_none"
+    )]
+    #[ts(optional = nullable, type = "number | null")]
+    pub token_budget: Option<Option<i64>>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadGoalSetResponse {
+    pub goal: ThreadGoal,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadGoalGetParams {
+    pub thread_id: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadGoalGetResponse {
+    pub goal: Option<ThreadGoal>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadGoalClearParams {
+    pub thread_id: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadGoalClearResponse {
+    pub cleared: bool,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]
@@ -6270,6 +6368,22 @@ pub struct ThreadNameUpdatedNotification {
     pub thread_name: Option<String>,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadGoalUpdatedNotification {
+    pub thread_id: String,
+    pub turn_id: Option<String>,
+    pub goal: ThreadGoal,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ThreadGoalClearedNotification {
+    pub thread_id: String,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]