[codex] Group removed feature flags (#22730)

## Summary
- move removed feature enum variants under the existing Removed section
- keep active feature variants grouped away from no-op compatibility
flags

## Test plan
- just fmt
- cargo test -p codex-features

Co-authored-by: Codex <noreply@openai.com>

codex-rs/features/src/lib.rs

@@ -76,31 +76,22 @@ impl Stage {
 #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
 pub enum Feature {
     // Stable.
-    /// Removed compatibility flag retained as a no-op so old configs can
-    /// still parse `undo`.
-    GhostCommit,
     /// Enable the default shell tool.
     ShellTool,
     /// Enable Claude-style lifecycle hooks loaded from hooks.json files.
     CodexHooks,
 
     // Experimental
-    /// Removed compatibility flag for the deleted JavaScript REPL feature.
-    JsRepl,
     /// Enable JavaScript code mode backed by the in-process V8 runtime.
     CodeMode,
     /// Restrict model-visible tools to code mode entrypoints (`exec`, `wait`).
     CodeModeOnly,
-    /// Removed compatibility flag for the deleted JavaScript REPL tool-only mode.
-    JsReplToolsOnly,
     /// Use the single unified PTY-backed exec tool.
     UnifiedExec,
     /// Route shell tool execution through the zsh exec bridge.
     ShellZshFork,
     /// Reflow transcript scrollback when the terminal is resized.
     TerminalResizeReflow,
-    /// Removed compatibility flag for the deleted apply_patch fallback feature.
-    ApplyPatchFreeform,
     /// Stream structured progress while apply_patch input is being generated.
     ApplyPatchStreamingEvents,
     /// Allow exec tools to request additional permissions while staying sandboxed.
@@ -112,30 +103,13 @@ pub enum Feature {
     /// Allow the model to request web searches that fetch cached content.
     /// Takes precedence over `WebSearchRequest`.
     WebSearchCached,
-    /// Legacy search-tool feature flag kept for backward compatibility.
-    SearchTool,
-    /// Removed legacy Linux bubblewrap opt-in flag retained as a no-op so old
-    /// wrappers and config can still parse it.
-    UseLinuxSandboxBwrap,
     /// Use the legacy Landlock Linux sandbox fallback instead of the default
     /// bubblewrap pipeline.
     UseLegacyLandlock,
-    /// Allow the model to request approval and propose exec rules.
-    RequestRule,
-    /// Enable Windows sandbox (restricted token) on Windows.
-    WindowsSandbox,
-    /// Use the elevated Windows sandbox pipeline (setup + runner).
-    WindowsSandboxElevated,
-    /// Legacy remote models flag kept for backward compatibility.
-    RemoteModels,
     /// Experimental shell snapshotting.
     ShellSnapshot,
-    /// Removed legacy git commit attribution guidance flag.
-    CodexGitCommit,
     /// Enable runtime metrics snapshots via a manual reader.
     RuntimeMetrics,
-    /// Persist rollout metadata to a local SQLite database.
-    Sqlite,
     /// Enable startup memory extraction and file-backed memory consolidation.
     MemoryTool,
     /// Enable the Chronicle sidecar for passive screen-context memories.
@@ -162,8 +136,6 @@ pub enum Feature {
     ToolSearch,
     /// Always defer MCP tools behind tool_search instead of exposing small sets directly.
     ToolSearchAlwaysDeferMcpTools,
-    /// Removed compatibility flag for the deleted unavailable-tool placeholder backfill.
-    UnavailableDummyTools,
     /// Enable discoverable tool suggestions for apps.
     ToolSuggest,
     /// Enable plugins.
@@ -200,18 +172,12 @@ pub enum Feature {
     SkillEnvVarDependencyPrompt,
     /// Enable the unified mention popup prototype.
     MentionsV2,
-    /// Steer feature flag - when enabled, Enter submits immediately instead of queuing.
-    /// Kept for config backward compatibility; behavior is always steer-enabled.
-    Steer,
     /// Allow request_user_input in Default collaboration mode.
     DefaultModeRequestUserInput,
     /// Enable automatic review for approval prompts.
     GuardianApproval,
     /// Enable persisted thread goals and automatic goal continuation.
     Goals,
-    /// Enable collaboration modes (Plan, Default).
-    /// Kept for config backward compatibility; behavior is always collaboration-modes-enabled.
-    CollaborationModes,
     /// Route MCP tool approval prompts through the MCP elicitation request path.
     ToolCallMcpElicitation,
     /// Prompt Codex Apps connector auth failures through MCP URL elicitations.
@@ -224,15 +190,57 @@ pub enum Feature {
     FastMode,
     /// Enable experimental realtime voice conversation mode in the TUI.
     RealtimeConversation,
-    /// Connect app-server to the ChatGPT remote control service.
+    /// Prevent idle system sleep while a turn is actively running.
+    PreventIdleSleep,
+    /// Send `response.processed` over Responses API websockets after a turn response is recorded.
+    ResponsesWebsocketResponseProcessed,
+    /// Enable remote compaction v2 over the normal Responses API.
+    RemoteCompactionV2,
+    /// Enable workspace dependency support.
+    WorkspaceDependencies,
+
+    // Removed
+    /// Removed compatibility flag retained as a no-op so old configs can
+    /// still parse `undo`.
+    GhostCommit,
+    /// Removed compatibility flag for the deleted JavaScript REPL feature.
+    JsRepl,
+    /// Removed compatibility flag for the deleted JavaScript REPL tool-only mode.
+    JsReplToolsOnly,
+    /// Legacy search-tool feature flag kept for backward compatibility.
+    SearchTool,
+    /// Removed legacy Linux bubblewrap opt-in flag retained as a no-op so old
+    /// wrappers and config can still parse it.
+    UseLinuxSandboxBwrap,
+    /// Allow the model to request approval and propose exec rules.
+    RequestRule,
+    /// Enable Windows sandbox (restricted token) on Windows.
+    WindowsSandbox,
+    /// Use the elevated Windows sandbox pipeline (setup + runner).
+    WindowsSandboxElevated,
+    /// Legacy remote models flag kept for backward compatibility.
+    RemoteModels,
+    /// Removed legacy git commit attribution guidance flag.
+    CodexGitCommit,
+    /// Persist rollout metadata to a local SQLite database.
+    Sqlite,
+    /// Removed compatibility flag for the deleted apply_patch fallback feature.
+    ApplyPatchFreeform,
+    /// Removed compatibility flag for the deleted unavailable-tool placeholder backfill.
+    UnavailableDummyTools,
+    /// Steer feature flag - when enabled, Enter submits immediately instead of queuing.
+    /// Kept for config backward compatibility; behavior is always steer-enabled.
+    Steer,
+    /// Enable collaboration modes (Plan, Default).
+    /// Kept for config backward compatibility; behavior is always collaboration-modes-enabled.
+    CollaborationModes,
+    /// Removed compatibility flag for the deleted remote control feature.
     RemoteControl,
     /// Removed compatibility flag retained as a no-op so old wrappers can
     /// still pass `--enable image_detail_original`.
     ImageDetailOriginal,
     /// Removed compatibility flag. The TUI now always uses the app-server implementation.
     TuiAppServer,
-    /// Prevent idle system sleep while a turn is actively running.
-    PreventIdleSleep,
     /// Removed compatibility flag retained as a no-op now that workspace owner
     /// usage nudges are always enabled.
     WorkspaceOwnerUsageNudge,
@@ -240,12 +248,6 @@ pub enum Feature {
     ResponsesWebsockets,
     /// Legacy rollout flag for Responses API WebSocket transport v2 experiments.
     ResponsesWebsocketsV2,
-    /// Send `response.processed` over Responses API websockets after a turn response is recorded.
-    ResponsesWebsocketResponseProcessed,
-    /// Enable remote compaction v2 over the normal Responses API.
-    RemoteCompactionV2,
-    /// Enable workspace dependency support.
-    WorkspaceDependencies,
 }
 
 impl Feature {