Treat inference hook denials as terminal errors (#60511)

## Why

An explicit denial from a workspace inference hook should stop the request, including retries and compaction model fallback.

## What changed

Recognize `inference_hook_denied` provider errors and preserve the provider's message, with a fallback when none is supplied. Expose the distinct `inferenceHookDenied` error through the app-server protocol and generated schemas and SDK types. Treat the denial as non-retryable during turns, compaction, and guardian review.

## Testing

Add coverage for terminal denials over HTTP, SSE, and WebSocket, error serialization and persistence in `thread/read`, and compaction failures that preserve token usage and history without retrying or falling back to another model.

GitOrigin-RevId: 2ebd480f01e52f4e6bd3db8a0f92d5814d18ccb1

codex-rs/protocol/src/codex_error_info.rs

@@ -26,6 +26,7 @@ enum CodexErrorInfoWire {
     ModelNotFound,
     /// Capacity is unavailable on a route restricted by server policy.
     PolicyCapacityUnavailable,
+    InferenceHookDenied,
     CyberPolicy,
     BioPolicy,
     MisalignmentPolicyViolation,

codex-rs/protocol/src/error.rs

@@ -173,6 +173,9 @@ pub enum CodexErrorDetails {
     },
     #[error("{message}")]
     InvalidPrompt { message: String },
+    /// The workspace's inference hook explicitly denied this request.
+    #[error("{message}")]
+    InferenceHookDenied { message: String },
     /// The provider rejected the input under its content policy.
     #[error("{message}")]
     ContentPolicyViolation {
@@ -463,6 +466,7 @@ impl CodexErr {
             | CodexErrorDetails::ResponseIncomplete(_)
             | CodexErrorDetails::ModelNotFound { .. }
             | CodexErrorDetails::InvalidPrompt { .. }
+            | CodexErrorDetails::InferenceHookDenied { .. }
             | CodexErrorDetails::ContentPolicyViolation { .. }
             | CodexErrorDetails::ToolCollision(_)
             | CodexErrorDetails::RefreshTokenFailed(_)
@@ -544,6 +548,7 @@ impl CodexErr {
                 CodexErrorInfo::PolicyCapacityUnavailable
             }
             CodexErrorDetails::FlexUnavailable => CodexErrorInfo::FlexUnavailable,
+            CodexErrorDetails::InferenceHookDenied { .. } => CodexErrorInfo::InferenceHookDenied,
             CodexErrorDetails::CyberPolicy { .. } => CodexErrorInfo::CyberPolicy,
             CodexErrorDetails::BioPolicy { .. } => CodexErrorInfo::BioPolicy,
             CodexErrorDetails::ModelNotFound { .. } => CodexErrorInfo::ModelNotFound,

codex-rs/protocol/src/protocol.rs

@@ -2106,6 +2106,8 @@ pub enum CodexErrorInfo {
     ModelNotFound,
     /// Capacity is unavailable on a route restricted by server policy.
     PolicyCapacityUnavailable,
+    /// The workspace's inference hook explicitly denied this request.
+    InferenceHookDenied,
     CyberPolicy,
     BioPolicy,
     MisalignmentPolicyViolation,
@@ -2153,6 +2155,7 @@ impl CodexErrorInfo {
             | Self::ServerOverloaded
             | Self::ModelNotFound
             | Self::PolicyCapacityUnavailable
+            | Self::InferenceHookDenied
             | Self::CyberPolicy
             | Self::BioPolicy
             | Self::MisalignmentPolicyViolation