Remove the personality migration (#32274)

## What changed

- Stop the TUI and app server from inspecting existing sessions at startup to
  set `personality = "pragmatic"` automatically.
- Remove the migration marker, helper APIs, and associated tests.

GitOrigin-RevId: 9e963bf113aff21651696bbc463f2749ac0f510a

codex-rs/app-server-client/src/lib.rs

@@ -23,7 +23,6 @@ use std::fmt;
 use std::io::Error as IoError;
 use std::io::ErrorKind;
 use std::io::Result as IoResult;
-use std::path::Path;
 use std::sync::Arc;
 use std::time::Duration;
 
@@ -50,11 +49,8 @@ use codex_config::LoaderOverrides;
 use codex_config::NoopThreadConfigLoader;
 use codex_config::RemoteThreadConfigLoader;
 use codex_config::ThreadConfigLoader;
-use codex_config::config_toml::ConfigToml;
 use codex_core::config::Config;
 pub use codex_core::otel_init::build_provider as build_otel_provider;
-use codex_core::personality_migration::PersonalityMigrationStatus;
-use codex_core::personality_migration::maybe_migrate_personality;
 pub use codex_exec_server::EnvironmentManager;
 pub use codex_exec_server::ExecServerRuntimePaths;
 use codex_feedback::CodexFeedback;
@@ -89,23 +85,6 @@ pub mod legacy_core {
 
 const SHUTDOWN_TIMEOUT: Duration = Duration::from_secs(5);
 
-/// Runs the embedded app-server personality migration.
-///
-/// Returns `true` when the migration changed config and the caller should reload it.
-pub async fn migrate_personality_if_needed(
-    codex_home: &Path,
-    config_toml: &ConfigToml,
-    state_db: Option<StateDbHandle>,
-) -> IoResult<bool> {
-    let status = maybe_migrate_personality(codex_home, config_toml, state_db).await?;
-    match status {
-        PersonalityMigrationStatus::Applied => Ok(true),
-        PersonalityMigrationStatus::SkippedMarker
-        | PersonalityMigrationStatus::SkippedExplicitPersonality
-        | PersonalityMigrationStatus::SkippedNoSessions => Ok(false),
-    }
-}
-
 /// Raw app-server request result for typed in-process requests.
 ///
 /// Even on the in-process path, successful responses still travel back through