Default fresh memory profiles to v2 (#56211)

## Why

Profiles without a v1 memory workspace have no legacy context to preserve or consolidate before using v2.

## What changed

- Select v2 when memories are enabled and the `memories` directory is absent. Preserve explicit `memories.version` settings, the `memories.dual_write = false` opt-out, and the v1 default for existing workspaces or filesystem check errors.
- Report `v2_ready` immediately for profiles without a v1 workspace. Keep the consolidation count and valid-summary requirements for profiles with a v1 workspace.
- Make resetting an absent memory workspace a no-op so it does not create an unused v1 directory.

## Testing

Extend coverage for default and explicit version selection, opt-outs, version-specific memory reads, fresh-profile readiness and reset behavior, and running only the v2 pipeline for fresh profiles.

GitOrigin-RevId: a8fb0844962ae9266ffbe88af97e8dc4a99ac15f

codex-rs/core/src/config/config_tests.rs

@@ -397,6 +397,34 @@ consolidation_model = "gpt-5.2"
     );
 }
 
+#[tokio::test]
+async fn fresh_memory_profiles_preserve_explicit_version_and_transition_opt_out() {
+    for (settings, expected) in [
+        ("", codex_protocol::MemoryVersion::V2),
+        ("version = 'v1'", codex_protocol::MemoryVersion::V1),
+        ("dual_write = false", codex_protocol::MemoryVersion::V1),
+        (
+            "version = 'v2'\ndual_write = false",
+            codex_protocol::MemoryVersion::V2,
+        ),
+    ] {
+        let home = tempdir().expect("tempdir");
+        let cfg = toml::from_str::<ConfigToml>(&format!(
+            "[features]\nmemories = true\n[memories]\n{settings}"
+        ))
+        .expect("memory config");
+        let config = Config::load_from_base_config_with_overrides(
+            cfg,
+            ConfigOverrides::default(),
+            home.abs(),
+        )
+        .await
+        .expect("load config");
+        assert_eq!(config.memories.version, expected, "{settings}");
+        assert!(!home.path().join("memories").exists());
+    }
+}
+
 #[tokio::test]
 async fn goal_max_token_budget_requires_positive_integer() {
     let config_toml = toml::from_str::<ConfigToml>("[goals]\nmax_goal_token_budget = 25000\n")
@@ -6301,7 +6329,7 @@ async fn memory_tool_makes_memories_root_readable_without_creating_or_widening_w
 -> std::io::Result<()> {
     let codex_home = TempDir::new()?;
     let cwd = TempDir::new()?;
-    let memories_root = codex_home.path().join("memories");
+    let memories_root = codex_home.path().join("memories_v2");
     let memories_root_abs = memories_root.abs();
 
     let config = Config::load_from_base_config_with_overrides(

codex-rs/core/src/config/mod.rs

@@ -97,6 +97,7 @@ use codex_model_provider_info::built_in_model_providers;
 use codex_model_provider_info::merge_configured_model_providers;
 use codex_models_manager::ModelsManagerConfig;
 use codex_prompts::ResolvedModelMessages;
+use codex_protocol::MemoryVersion;
 use codex_protocol::config_types::AltScreenMode;
 use codex_protocol::config_types::AutoCompactTokenLimitScope;
 use codex_protocol::config_types::ForcedLoginMethod;
@@ -3646,7 +3647,20 @@ impl Config {
             ));
         }
 
-        let memories_config: MemoriesConfig = cfg.memories.clone().unwrap_or_default().into();
+        let mut memories = cfg.memories.clone().unwrap_or_default();
+        // Fresh profiles have no V1 context to preserve or warm up before using V2.
+        // Keep explicit selections and transition opt-outs, and fail closed on IO errors.
+        if features.enabled(Feature::MemoryTool)
+            && memories.version.is_none()
+            && memories.dual_write != Some(false)
+            && matches!(
+                tokio::fs::try_exists(codex_home.join(MemoryVersion::V1.directory_name())).await,
+                Ok(false)
+            )
+        {
+            memories.version = Some(MemoryVersion::V2);
+        }
+        let memories_config: MemoriesConfig = memories.into();
         let memories_root = codex_home.join(memories_config.version.directory_name());
 
         let profiles_are_active = effective_permission_selection.profiles_are_active(