Support Codex turn context overrides

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

@@ -3409,6 +3409,8 @@ fn turn_start_params_preserve_explicit_null_service_tier() {
         responsesapi_client_metadata: None,
         environments: None,
         cwd: None,
+        current_date: None,
+        timezone: None,
         approval_policy: None,
         approvals_reviewer: None,
         sandbox_policy: None,

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

@@ -64,6 +64,14 @@ pub struct TurnStartParams {
     /// Override the working directory for this turn and subsequent turns.
     #[ts(optional = nullable)]
     pub cwd: Option<PathBuf>,
+    /// Override the current date shown in the model-visible environment context
+    /// for this turn and subsequent turns.
+    #[ts(optional = nullable)]
+    pub current_date: Option<String>,
+    /// Override the timezone shown in the model-visible environment context for
+    /// this turn and subsequent turns.
+    #[ts(optional = nullable)]
+    pub timezone: Option<String>,
     /// Override the approval policy for this turn and subsequent turns.
     #[experimental(nested)]
     #[ts(optional = nullable)]

codex-rs/app-server/src/message_processor_tracing_tests.rs

@@ -658,6 +658,8 @@ async fn turn_start_jsonrpc_span_parents_core_turn_spans() -> Result<()> {
                     }],
                     responsesapi_client_metadata: None,
                     cwd: None,
+                    current_date: None,
+                    timezone: None,
                     approval_policy: None,
                     sandbox_policy: None,
                     permissions: None,

codex-rs/app-server/src/request_processors/turn_processor.rs

@@ -354,6 +354,8 @@ impl TurnRequestProcessor {
         let turn_has_input = !mapped_items.is_empty();
 
         let has_any_overrides = params.cwd.is_some()
+            || params.current_date.is_some()
+            || params.timezone.is_some()
             || params.approval_policy.is_some()
             || params.approvals_reviewer.is_some()
             || params.sandbox_policy.is_some()
@@ -372,6 +374,8 @@ impl TurnRequestProcessor {
         }
 
         let cwd = params.cwd;
+        let current_date = params.current_date;
+        let timezone = params.timezone;
         let approval_policy = params.approval_policy.map(AskForApproval::to_core);
         let approvals_reviewer = params
             .approvals_reviewer
@@ -429,6 +433,8 @@ impl TurnRequestProcessor {
             thread
                 .validate_turn_context_overrides(CodexThreadTurnContextOverrides {
                     cwd: cwd.clone(),
+                    current_date: current_date.clone(),
+                    timezone: timezone.clone(),
                     approval_policy,
                     approvals_reviewer,
                     sandbox_policy: sandbox_policy.clone(),
@@ -454,6 +460,8 @@ impl TurnRequestProcessor {
                 final_output_json_schema: params.output_schema,
                 responsesapi_client_metadata: params.responsesapi_client_metadata,
                 cwd,
+                current_date,
+                timezone,
                 approval_policy,
                 approvals_reviewer,
                 sandbox_policy,

codex-rs/app-server/tests/suite/v2/turn_start.rs

@@ -1890,6 +1890,8 @@ async fn turn_start_updates_sandbox_and_cwd_between_turns_v2() -> Result<()> {
             }],
             responsesapi_client_metadata: None,
             cwd: Some(first_cwd.clone()),
+            current_date: None,
+            timezone: None,
             approval_policy: Some(codex_app_server_protocol::AskForApproval::Never),
             approvals_reviewer: None,
             sandbox_policy: Some(codex_app_server_protocol::SandboxPolicy::WorkspaceWrite {
@@ -1931,6 +1933,8 @@ async fn turn_start_updates_sandbox_and_cwd_between_turns_v2() -> Result<()> {
             }],
             responsesapi_client_metadata: None,
             cwd: Some(second_cwd.clone()),
+            current_date: None,
+            timezone: None,
             approval_policy: Some(codex_app_server_protocol::AskForApproval::Never),
             approvals_reviewer: None,
             sandbox_policy: Some(codex_app_server_protocol::SandboxPolicy::DangerFullAccess),

codex-rs/core/src/codex_thread.rs

@@ -81,6 +81,8 @@ impl ThreadConfigSnapshot {
 #[derive(Clone, Default)]
 pub struct CodexThreadTurnContextOverrides {
     pub cwd: Option<PathBuf>,
+    pub current_date: Option<String>,
+    pub timezone: Option<String>,
     pub approval_policy: Option<AskForApproval>,
     pub approvals_reviewer: Option<ApprovalsReviewer>,
     pub sandbox_policy: Option<SandboxPolicy>,
@@ -240,6 +242,8 @@ impl CodexThread {
     ) -> ConstraintResult<()> {
         let CodexThreadTurnContextOverrides {
             cwd,
+            current_date,
+            timezone,
             approval_policy,
             approvals_reviewer,
             sandbox_policy,
@@ -265,6 +269,8 @@ impl CodexThread {
 
         let updates = SessionSettingsUpdate {
             cwd,
+            current_date,
+            timezone,
             approval_policy,
             approvals_reviewer,
             sandbox_policy,

codex-rs/core/src/context_manager/updates.rs

@@ -69,6 +69,21 @@ fn build_permissions_update_item(
     )
 }
 
+fn build_developer_instructions_update_item(
+    previous: Option<&TurnContextItem>,
+    next: &TurnContext,
+) -> Option<String> {
+    let prev = previous?;
+    if prev.developer_instructions == next.developer_instructions {
+        return None;
+    }
+
+    next.developer_instructions
+        .as_deref()
+        .filter(|instructions| !instructions.trim().is_empty())
+        .map(str::to_string)
+}
+
 fn build_collaboration_mode_update_item(
     previous: Option<&TurnContextItem>,
     next: &TurnContext,
@@ -218,6 +233,7 @@ pub(crate) fn build_settings_update_items(
         // Keep model-switch instructions first so model-specific guidance is read before
         // any other context diffs on this turn.
         build_model_instructions_update_item(previous_turn_settings, next),
+        build_developer_instructions_update_item(previous, next),
         build_permissions_update_item(previous, next, exec_policy),
         build_collaboration_mode_update_item(previous, next),
         build_realtime_update_item(previous, previous_turn_settings, next),

codex-rs/core/src/session/handlers.rs

@@ -143,6 +143,8 @@ pub(super) async fn user_input_or_turn_inner(
                 items,
                 SessionSettingsUpdate {
                     cwd: Some(cwd),
+                    current_date: None,
+                    timezone: None,
                     approval_policy: Some(approval_policy),
                     approvals_reviewer,
                     sandbox_policy: Some(sandbox_policy),
@@ -163,6 +165,8 @@ pub(super) async fn user_input_or_turn_inner(
         }
         Op::UserInputWithTurnContext {
             cwd,
+            current_date,
+            timezone,
             approval_policy,
             approvals_reviewer,
             sandbox_policy,
@@ -195,6 +199,8 @@ pub(super) async fn user_input_or_turn_inner(
                 items,
                 SessionSettingsUpdate {
                     cwd,
+                    current_date,
+                    timezone,
                     approval_policy,
                     approvals_reviewer,
                     sandbox_policy,

codex-rs/core/src/session/mod.rs

@@ -620,6 +620,8 @@ impl Codex {
             active_permission_profile: config.permissions.active_permission_profile(),
             windows_sandbox_level: WindowsSandboxLevel::from_config(&config),
             cwd: config.cwd.clone(),
+            current_date: None,
+            timezone: None,
             codex_home: config.codex_home.clone(),
             thread_name: None,
             environments: environment_selections.to_selections(),

codex-rs/core/src/session/session.rs

@@ -75,6 +75,10 @@ pub(crate) struct SessionConfiguration {
     /// execution sandbox are resolved against this directory **instead** of
     /// the process-wide current working directory.
     pub(super) cwd: AbsolutePathBuf,
+    /// Optional current date override for the model-visible environment context.
+    pub(super) current_date: Option<String>,
+    /// Optional timezone override for the model-visible environment context.
+    pub(super) timezone: Option<String>,
     /// Directory containing all Codex state for this session.
     pub(super) codex_home: AbsolutePathBuf,
     /// Optional user-facing name for the thread, updated during the session.
@@ -199,6 +203,12 @@ impl SessionConfiguration {
         if let Some(approval_policy) = updates.approval_policy {
             next_configuration.approval_policy.set(approval_policy)?;
         }
+        if let Some(current_date) = updates.current_date.clone() {
+            next_configuration.current_date = Some(current_date);
+        }
+        if let Some(timezone) = updates.timezone.clone() {
+            next_configuration.timezone = Some(timezone);
+        }
         if let Some(approvals_reviewer) = updates.approvals_reviewer {
             next_configuration.approvals_reviewer = approvals_reviewer;
         }
@@ -309,6 +319,8 @@ impl SessionConfiguration {
 #[derive(Default, Clone)]
 pub(crate) struct SessionSettingsUpdate {
     pub(crate) cwd: Option<PathBuf>,
+    pub(crate) current_date: Option<String>,
+    pub(crate) timezone: Option<String>,
     pub(crate) approval_policy: Option<AskForApproval>,
     pub(crate) approvals_reviewer: Option<ApprovalsReviewer>,
     pub(crate) sandbox_policy: Option<SandboxPolicy>,

codex-rs/core/src/session/tests.rs

@@ -2581,6 +2581,8 @@ async fn set_rate_limits_retains_previous_credits() {
         active_permission_profile: config.permissions.active_permission_profile(),
         windows_sandbox_level: WindowsSandboxLevel::from_config(&config),
         cwd: config.cwd.clone(),
+        current_date: None,
+        timezone: None,
         codex_home: config.codex_home.clone(),
         thread_name: None,
         environments: Vec::new(),
@@ -2685,6 +2687,8 @@ async fn set_rate_limits_updates_plan_type_when_present() {
         active_permission_profile: config.permissions.active_permission_profile(),
         windows_sandbox_level: WindowsSandboxLevel::from_config(&config),
         cwd: config.cwd.clone(),
+        current_date: None,
+        timezone: None,
         codex_home: config.codex_home.clone(),
         thread_name: None,
         environments: Vec::new(),
@@ -3126,6 +3130,22 @@ async fn session_settings_legacy_fast_service_tier_update_uses_priority_request_
     );
 }
 
+#[tokio::test]
+async fn session_configuration_apply_updates_environment_context_overrides() {
+    let session_configuration = make_session_configuration_for_tests().await;
+
+    let updated = session_configuration
+        .apply(&SessionSettingsUpdate {
+            current_date: Some("2026-05-13".to_string()),
+            timezone: Some("America/Los_Angeles".to_string()),
+            ..Default::default()
+        })
+        .expect("time context update should succeed");
+
+    assert_eq!(updated.current_date.as_deref(), Some("2026-05-13"));
+    assert_eq!(updated.timezone.as_deref(), Some("America/Los_Angeles"));
+}
+
 pub(crate) async fn make_session_configuration_for_tests() -> SessionConfiguration {
     let codex_home = tempfile::tempdir().expect("create temp dir");
     let config = build_test_config(codex_home.path()).await;
@@ -3162,6 +3182,8 @@ pub(crate) async fn make_session_configuration_for_tests() -> SessionConfigurati
         active_permission_profile: config.permissions.active_permission_profile(),
         windows_sandbox_level: WindowsSandboxLevel::from_config(&config),
         cwd: config.cwd.clone(),
+        current_date: None,
+        timezone: None,
         codex_home: config.codex_home.clone(),
         thread_name: None,
         environments: Vec::new(),
@@ -3688,6 +3710,8 @@ async fn session_new_fails_when_zsh_fork_enabled_without_zsh_path() {
         active_permission_profile: config.permissions.active_permission_profile(),
         windows_sandbox_level: WindowsSandboxLevel::from_config(&config),
         cwd: config.cwd.clone(),
+        current_date: None,
+        timezone: None,
         codex_home: config.codex_home.clone(),
         thread_name: None,
         environments: Vec::new(),
@@ -3797,6 +3821,8 @@ pub(crate) async fn make_session_and_context() -> (Session, TurnContext) {
         active_permission_profile: config.permissions.active_permission_profile(),
         windows_sandbox_level: WindowsSandboxLevel::from_config(&config),
         cwd: config.cwd.clone(),
+        current_date: None,
+        timezone: None,
         codex_home: config.codex_home.clone(),
         thread_name: None,
         environments: default_environments,
@@ -4026,6 +4052,8 @@ async fn make_session_with_config_and_rx(
         active_permission_profile: config.permissions.active_permission_profile(),
         windows_sandbox_level: WindowsSandboxLevel::from_config(&config),
         cwd: config.cwd.clone(),
+        current_date: None,
+        timezone: None,
         codex_home: config.codex_home.clone(),
         thread_name: None,
         environments: default_environments,
@@ -4129,6 +4157,8 @@ async fn make_session_with_history_source_and_agent_control_and_rx(
         active_permission_profile: config.permissions.active_permission_profile(),
         windows_sandbox_level: WindowsSandboxLevel::from_config(&config),
         cwd: config.cwd.clone(),
+        current_date: None,
+        timezone: None,
         codex_home: config.codex_home.clone(),
         thread_name: None,
         environments: default_environments,
@@ -4776,6 +4806,8 @@ fn op_kind_distinguishes_turn_ops() {
             final_output_json_schema: None,
             responsesapi_client_metadata: None,
             cwd: None,
+            current_date: None,
+            timezone: None,
             approval_policy: None,
             approvals_reviewer: None,
             sandbox_policy: None,
@@ -5516,6 +5548,8 @@ where
         active_permission_profile: config.permissions.active_permission_profile(),
         windows_sandbox_level: WindowsSandboxLevel::from_config(&config),
         cwd: config.cwd.clone(),
+        current_date: None,
+        timezone: None,
         codex_home: config.codex_home.clone(),
         thread_name: None,
         environments: default_environments,
@@ -6004,6 +6038,63 @@ async fn build_settings_update_items_omits_environment_item_when_disabled() {
     );
 }
 
+#[tokio::test]
+async fn build_settings_update_items_emits_developer_item_for_developer_instruction_changes() {
+    let (session, mut previous_context) = make_session_and_context().await;
+    previous_context.developer_instructions = Some("old developer guidance".to_string());
+    let previous_context = Arc::new(previous_context);
+    let mut current_context = previous_context
+        .with_model(
+            previous_context.model_info.slug.clone(),
+            &session.services.models_manager,
+        )
+        .await;
+    current_context.developer_instructions = Some("new developer guidance".to_string());
+
+    let update_items = session
+        .build_settings_update_items(
+            Some(&previous_context.to_turn_context_item()),
+            &current_context,
+        )
+        .await;
+
+    let developer_texts = developer_input_texts(&update_items);
+    assert!(
+        developer_texts
+            .iter()
+            .any(|text| text.contains("new developer guidance")),
+        "expected changed developer instructions to be appended, got {developer_texts:?}"
+    );
+    assert!(
+        !developer_texts
+            .iter()
+            .any(|text| text.contains("old developer guidance")),
+        "did not expect previous developer instructions to be re-appended, got {developer_texts:?}"
+    );
+}
+
+#[tokio::test]
+async fn build_settings_update_items_omits_unchanged_developer_instruction_item() {
+    let (session, mut previous_context) = make_session_and_context().await;
+    previous_context.developer_instructions = Some("stable developer guidance".to_string());
+    let previous_context = Arc::new(previous_context);
+    let current_context = previous_context
+        .with_model(
+            previous_context.model_info.slug.clone(),
+            &session.services.models_manager,
+        )
+        .await;
+
+    let update_items = session
+        .build_settings_update_items(
+            Some(&previous_context.to_turn_context_item()),
+            &current_context,
+        )
+        .await;
+
+    assert!(developer_input_texts(&update_items).is_empty());
+}
+
 #[tokio::test]
 async fn build_settings_update_items_emits_realtime_start_when_session_becomes_live() {
     let (session, previous_context) = make_session_and_context().await;

codex-rs/core/src/session/turn_context.rs

@@ -536,7 +536,15 @@ impl Session {
             session_configuration.windows_sandbox_level,
             network.is_some(),
         ));
-        let (current_date, timezone) = local_time_context();
+        let (local_current_date, local_timezone) = local_time_context();
+        let current_date = session_configuration
+            .current_date
+            .clone()
+            .unwrap_or(local_current_date);
+        let timezone = session_configuration
+            .timezone
+            .clone()
+            .unwrap_or(local_timezone);
         TurnContext {
             sub_id,
             trace_id: current_span_trace_id(),

codex-rs/protocol/src/protocol.rs

@@ -462,6 +462,14 @@ pub enum Op {
         #[serde(skip_serializing_if = "Option::is_none")]
         cwd: Option<PathBuf>,
 
+        /// Updated current date shown in the model-visible environment context.
+        #[serde(skip_serializing_if = "Option::is_none")]
+        current_date: Option<String>,
+
+        /// Updated timezone shown in the model-visible environment context.
+        #[serde(skip_serializing_if = "Option::is_none")]
+        timezone: Option<String>,
+
         /// Updated command approval policy.
         #[serde(skip_serializing_if = "Option::is_none")]
         approval_policy: Option<AskForApproval>,