clean models manager (#9168)

Have only the following Methods:
- `list_models`: getting current available models
- `try_list_models`: sync version no refresh for tui use
- `get_default_model`: get the default model (should be tightened to
core and received on session configuration)
- `get_model_info`: get `ModelInfo` for a specific model (should be
tightened to core but used in tests)
- `refresh_if_new_etag`: trigger refresh on different etags

Also move the cache to its own struct

codex-rs/protocol/src/openai_models.rs

@@ -1,4 +1,5 @@
 use std::collections::HashMap;
+use std::collections::HashSet;
 
 use schemars::JsonSchema;
 use serde::Deserialize;
@@ -243,6 +244,46 @@ impl From<ModelInfo> for ModelPreset {
     }
 }
 
+impl ModelPreset {
+    /// Filter models based on authentication mode.
+    ///
+    /// In ChatGPT mode, all models are visible. Otherwise, only API-supported models are shown.
+    pub fn filter_by_auth(models: Vec<ModelPreset>, chatgpt_mode: bool) -> Vec<ModelPreset> {
+        models
+            .into_iter()
+            .filter(|model| chatgpt_mode || model.supported_in_api)
+            .collect()
+    }
+
+    /// Merge remote presets with existing presets, preferring remote when slugs match.
+    ///
+    /// Remote presets take precedence. Existing presets not in remote are appended with `is_default` set to false.
+    pub fn merge(
+        remote_presets: Vec<ModelPreset>,
+        existing_presets: Vec<ModelPreset>,
+    ) -> Vec<ModelPreset> {
+        if remote_presets.is_empty() {
+            return existing_presets;
+        }
+
+        let remote_slugs: HashSet<&str> = remote_presets
+            .iter()
+            .map(|preset| preset.model.as_str())
+            .collect();
+
+        let mut merged_presets = remote_presets.clone();
+        for mut preset in existing_presets {
+            if remote_slugs.contains(preset.model.as_str()) {
+                continue;
+            }
+            preset.is_default = false;
+            merged_presets.push(preset);
+        }
+
+        merged_presets
+    }
+}
+
 fn reasoning_effort_mapping_from_presets(
     presets: &[ReasoningEffortPreset],
 ) -> Option<HashMap<ReasoningEffort, ReasoningEffort>> {