[codex] rename rollout budget error to session budget error (#29744)

## Summary

- rename the rollout-budget exhaustion error from
`RolloutBudgetExceeded` to `SessionBudgetExceeded`
- expose the matching app-server v2 wire value as
`sessionBudgetExceeded`
- regenerate JSON/TypeScript schema fixtures and update the app-server
docs and focused tests

This is a naming-only follow-up to #29715 based on [Pavel's review
suggestion](https://github.com/openai/codex/pull/29715#discussion_r3463183480).
Runtime behavior is unchanged.

## Tests

- `just test -p codex-core rollout_budget`
- `just test -p codex-app-server-protocol`
- `just fmt`
- `just write-app-server-schema`

codex-rs/analytics/src/facts.rs

@@ -139,7 +139,7 @@ impl TurnCodexErrorFact {
 #[serde(rename_all = "snake_case")]
 pub enum CodexErrKind {
     TurnAborted,
-    RolloutBudgetExceeded,
+    SessionBudgetExceeded,
     Stream,
     ContextWindowExceeded,
     ThreadNotFound,
@@ -196,7 +196,7 @@ impl From<&CodexErr> for CodexErrKind {
     fn from(error: &CodexErr) -> Self {
         match error {
             CodexErr::TurnAborted => CodexErrKind::TurnAborted,
-            CodexErr::RolloutBudgetExceeded => CodexErrKind::RolloutBudgetExceeded,
+            CodexErr::SessionBudgetExceeded => CodexErrKind::SessionBudgetExceeded,
             CodexErr::Stream(..) => CodexErrKind::Stream,
             CodexErr::ContextWindowExceeded => CodexErrKind::ContextWindowExceeded,
             CodexErr::ThreadNotFound(_) => CodexErrKind::ThreadNotFound,

codex-rs/app-server-protocol/schema/json/ServerNotification.json

@@ -573,7 +573,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json

@@ -7070,7 +7070,7 @@
           {
             "enum": [
               "contextWindowExceeded",
-              "rolloutBudgetExceeded",
+              "sessionBudgetExceeded",
               "usageLimitExceeded",
               "serverOverloaded",
               "cyberPolicy",

codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json

@@ -3310,7 +3310,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ErrorNotification.json

@@ -7,7 +7,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ReviewStartResponse.json

@@ -30,7 +30,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ThreadForkResponse.json

@@ -111,7 +111,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ThreadListResponse.json

@@ -33,7 +33,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ThreadMetadataUpdateResponse.json

@@ -33,7 +33,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ThreadReadResponse.json

@@ -33,7 +33,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ThreadResumeResponse.json

@@ -111,7 +111,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ThreadRollbackResponse.json

@@ -33,7 +33,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ThreadStartResponse.json

@@ -111,7 +111,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ThreadStartedNotification.json

@@ -33,7 +33,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/ThreadUnarchiveResponse.json

@@ -33,7 +33,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/TurnCompletedNotification.json

@@ -30,7 +30,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/TurnStartResponse.json

@@ -30,7 +30,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/json/v2/TurnStartedNotification.json

@@ -30,7 +30,7 @@
         {
           "enum": [
             "contextWindowExceeded",
-            "rolloutBudgetExceeded",
+            "sessionBudgetExceeded",
             "usageLimitExceeded",
             "serverOverloaded",
             "cyberPolicy",

codex-rs/app-server-protocol/schema/typescript/v2/CodexErrorInfo.ts

@@ -9,4 +9,4 @@ import type { NonSteerableTurnKind } from "./NonSteerableTurnKind";
  * When an upstream HTTP status is available (for example, from the Responses API or a provider),
  * it is forwarded in `httpStatusCode` on the relevant `codexErrorInfo` variant.
  */
-export type CodexErrorInfo = "contextWindowExceeded" | "rolloutBudgetExceeded" | "usageLimitExceeded" | "serverOverloaded" | "cyberPolicy" | { "httpConnectionFailed": { httpStatusCode: number | null, } } | { "responseStreamConnectionFailed": { httpStatusCode: number | null, } } | "internalServerError" | "unauthorized" | "badRequest" | "threadRollbackFailed" | "sandboxError" | { "responseStreamDisconnected": { httpStatusCode: number | null, } } | { "responseTooManyFailedAttempts": { httpStatusCode: number | null, } } | { "activeTurnNotSteerable": { turnKind: NonSteerableTurnKind, } } | "other";
+export type CodexErrorInfo = "contextWindowExceeded" | "sessionBudgetExceeded" | "usageLimitExceeded" | "serverOverloaded" | "cyberPolicy" | { "httpConnectionFailed": { httpStatusCode: number | null, } } | { "responseStreamConnectionFailed": { httpStatusCode: number | null, } } | "internalServerError" | "unauthorized" | "badRequest" | "threadRollbackFailed" | "sandboxError" | { "responseStreamDisconnected": { httpStatusCode: number | null, } } | { "responseTooManyFailedAttempts": { httpStatusCode: number | null, } } | { "activeTurnNotSteerable": { turnKind: NonSteerableTurnKind, } } | "other";

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

@@ -70,7 +70,7 @@ pub enum NonSteerableTurnKind {
 #[ts(export_to = "v2/")]
 pub enum CodexErrorInfo {
     ContextWindowExceeded,
-    RolloutBudgetExceeded,
+    SessionBudgetExceeded,
     UsageLimitExceeded,
     ServerOverloaded,
     CyberPolicy,
@@ -116,7 +116,7 @@ impl From<CoreCodexErrorInfo> for CodexErrorInfo {
     fn from(value: CoreCodexErrorInfo) -> Self {
         match value {
             CoreCodexErrorInfo::ContextWindowExceeded => CodexErrorInfo::ContextWindowExceeded,
-            CoreCodexErrorInfo::RolloutBudgetExceeded => CodexErrorInfo::RolloutBudgetExceeded,
+            CoreCodexErrorInfo::SessionBudgetExceeded => CodexErrorInfo::SessionBudgetExceeded,
             CoreCodexErrorInfo::UsageLimitExceeded => CodexErrorInfo::UsageLimitExceeded,
             CoreCodexErrorInfo::ServerOverloaded => CodexErrorInfo::ServerOverloaded,
             CoreCodexErrorInfo::CyberPolicy => CodexErrorInfo::CyberPolicy,

codex-rs/app-server/README.md

@@ -1423,7 +1423,7 @@ There are additional item-specific events:
 `codexErrorInfo` maps to the `CodexErrorInfo` enum. Common values:
 
 - `ContextWindowExceeded`
-- `RolloutBudgetExceeded`
+- `SessionBudgetExceeded`
 - `UsageLimitExceeded`
 - `HttpConnectionFailed { httpStatusCode? }`: upstream HTTP failures including 4xx/5xx
 - `ResponseStreamConnectionFailed { httpStatusCode? }`: failure to connect to the response SSE stream

codex-rs/core/src/compact.rs

@@ -275,7 +275,7 @@ async fn run_compact_task_inner_impl(
             Err(err @ (CodexErr::Interrupted | CodexErr::TurnAborted)) => {
                 return Err(err);
             }
-            Err(e @ CodexErr::RolloutBudgetExceeded) => {
+            Err(e @ CodexErr::SessionBudgetExceeded) => {
                 sess.track_turn_codex_error(turn_context.as_ref(), &e);
                 let event = EventMsg::Error(e.to_error_event(/*message_prefix*/ None));
                 sess.send_event(&turn_context, event).await;

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

@@ -30,7 +30,7 @@ impl Session {
             .rollout_budget()
             .record_usage(usage)
         {
-            return Err(CodexErr::RolloutBudgetExceeded);
+            return Err(CodexErr::SessionBudgetExceeded);
         }
         Ok(())
     }

codex-rs/core/tests/suite/rollout_budget.rs

@@ -252,7 +252,7 @@ async fn exhausted_budget_fails_current_and_later_turns() -> Result<()> {
             matches!(
                 event,
                 EventMsg::Error(error)
-                    if error.codex_error_info == Some(CodexErrorInfo::RolloutBudgetExceeded)
+                    if error.codex_error_info == Some(CodexErrorInfo::SessionBudgetExceeded)
             )
         })
         .await;
@@ -315,7 +315,7 @@ async fn compaction_budget_exhaustion_fails_without_retry(remote_v2: bool) -> Re
         matches!(
             event,
             EventMsg::Error(error)
-                if error.codex_error_info == Some(CodexErrorInfo::RolloutBudgetExceeded)
+                if error.codex_error_info == Some(CodexErrorInfo::SessionBudgetExceeded)
         )
     })
     .await;

codex-rs/protocol/src/error.rs

@@ -70,7 +70,7 @@ pub enum CodexErr {
     TurnAborted,
 
     #[error("shared rollout token budget exhausted")]
-    RolloutBudgetExceeded,
+    SessionBudgetExceeded,
 
     /// Returned by ResponsesClient when the SSE stream disconnects or errors out **after** the HTTP
     /// handshake has succeeded but **before** it finished emitting `response.completed`.
@@ -176,7 +176,7 @@ impl CodexErr {
     pub fn is_retryable(&self) -> bool {
         match self {
             CodexErr::TurnAborted
-            | CodexErr::RolloutBudgetExceeded
+            | CodexErr::SessionBudgetExceeded
             | CodexErr::Interrupted
             | CodexErr::EnvVar(_)
             | CodexErr::Fatal(_)
@@ -224,7 +224,7 @@ impl CodexErr {
     pub fn to_codex_protocol_error(&self) -> CodexErrorInfo {
         match self {
             CodexErr::ContextWindowExceeded => CodexErrorInfo::ContextWindowExceeded,
-            CodexErr::RolloutBudgetExceeded => CodexErrorInfo::RolloutBudgetExceeded,
+            CodexErr::SessionBudgetExceeded => CodexErrorInfo::SessionBudgetExceeded,
             CodexErr::UsageLimitReached(_)
             | CodexErr::QuotaExceeded
             | CodexErr::UsageNotIncluded => CodexErrorInfo::UsageLimitExceeded,

codex-rs/protocol/src/protocol.rs

@@ -1690,7 +1690,7 @@ pub enum NonSteerableTurnKind {
 #[ts(rename_all = "snake_case")]
 pub enum CodexErrorInfo {
     ContextWindowExceeded,
-    RolloutBudgetExceeded,
+    SessionBudgetExceeded,
     UsageLimitExceeded,
     ServerOverloaded,
     CyberPolicy,
@@ -1728,7 +1728,7 @@ impl CodexErrorInfo {
         match self {
             Self::ThreadRollbackFailed | Self::ActiveTurnNotSteerable { .. } => false,
             Self::ContextWindowExceeded
-            | Self::RolloutBudgetExceeded
+            | Self::SessionBudgetExceeded
             | Self::UsageLimitExceeded
             | Self::ServerOverloaded
             | Self::CyberPolicy