Trim TUI legacy telemetry and migration dependencies (#27487)

## Why

The TUI still reached through `codex-app-server-client::legacy_core` for
process telemetry setup and personality migration, exposing core-only
details after the TUI moved onto the app-server layer.

This is part of our ongoing efforts to whittle away at the legacy_core
shim that was left over after migrating the TUI to the app server.

This change is just a refactor/rename and should be behavior-neutral and
low risk.

## What changed

- expose OTEL provider construction through the app-server client and
keep the small process/SQLite telemetry adapters local to the TUI
- collapse personality migration results to the config-reload decision
the TUI needs
- remove the `legacy_core::otel_init` and
`legacy_core::personality_migration` subnamespaces

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

@@ -22,6 +22,7 @@ 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;
 
@@ -48,7 +49,11 @@ 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;
@@ -82,14 +87,6 @@ pub mod legacy_core {
         }
     }
 
-    pub mod otel_init {
-        pub use codex_core::otel_init::*;
-    }
-
-    pub mod personality_migration {
-        pub use codex_core::personality_migration::*;
-    }
-
     pub mod windows_sandbox {
         pub use codex_core::windows_sandbox::*;
     }
@@ -97,6 +94,23 @@ 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

codex-rs/tui/src/lib.rs

@@ -1125,7 +1125,7 @@ pub async fn run_main(
 
     let otel_originator = originator().value;
     let otel = match std::panic::catch_unwind(std::panic::AssertUnwindSafe(|| {
-        crate::legacy_core::otel_init::build_provider(
+        codex_app_server_client::build_otel_provider(
             &config,
             env!("CARGO_PKG_VERSION"),
             /*service_name_override*/ None,
@@ -1148,26 +1148,25 @@ pub async fn run_main(
             None
         }
     };
-    crate::legacy_core::otel_init::record_process_start(otel.as_ref(), otel_originator.as_str());
-    crate::legacy_core::otel_init::install_sqlite_telemetry(
-        otel.as_ref(),
-        otel_originator.as_str(),
-    );
+    if let Some(metrics) = otel.as_ref().and_then(codex_otel::OtelProvider::metrics) {
+        let _ = codex_otel::record_process_start_once(metrics, otel_originator.as_str());
+        let telemetry =
+            codex_rollout::sqlite_telemetry_recorder(metrics.clone(), otel_originator.as_str());
+        let _ = codex_state::install_process_db_telemetry(telemetry);
+    }
     let state_db = init_state_db_for_app_server_target(&config, &app_server_target).await?;
 
     let effective_toml = config.config_layer_stack.effective_config();
     match effective_toml.try_into() {
         Ok(config_toml) => {
-            match crate::legacy_core::personality_migration::maybe_migrate_personality(
+            match codex_app_server_client::migrate_personality_if_needed(
                 &config.codex_home,
                 &config_toml,
                 state_db.clone(),
             )
             .await
             {
-                Ok(
-                    crate::legacy_core::personality_migration::PersonalityMigrationStatus::Applied,
-                ) => {
+                Ok(true) => {
                     config = load_config_or_exit(
                         cli_kv_overrides.clone(),
                         overrides.clone(),
@@ -1177,11 +1176,7 @@ pub async fn run_main(
                     )
                     .await;
                 }
-                Ok(
-                    crate::legacy_core::personality_migration::PersonalityMigrationStatus::SkippedMarker
-                    | crate::legacy_core::personality_migration::PersonalityMigrationStatus::SkippedExplicitPersonality
-                    | crate::legacy_core::personality_migration::PersonalityMigrationStatus::SkippedNoSessions,
-                ) => {}
+                Ok(false) => {}
                 Err(err) => {
                     tracing::warn!(error = %err, "failed to run personality migration");
                 }