Extract codex-instructions crate (#15744)

## Summary
- extract instruction fragment and user-instruction types into
codex-instructions
- update codex-core to consume the new crate

## Testing
- CI

---------

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

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

@@ -1,5 +1,3 @@
-mod user_instructions;
-
-pub(crate) use user_instructions::SkillInstructions;
-pub use user_instructions::USER_INSTRUCTIONS_PREFIX;
-pub(crate) use user_instructions::UserInstructions;
+pub(crate) use codex_instructions::SkillInstructions;
+pub use codex_instructions::USER_INSTRUCTIONS_PREFIX;
+pub(crate) use codex_instructions::UserInstructions;

codex-rs/core/src/instructions/user_instructions.rs

@@ -1,57 +0,0 @@
-use serde::Deserialize;
-use serde::Serialize;
-
-use codex_protocol::models::ResponseItem;
-
-use crate::contextual_user_message::AGENTS_MD_FRAGMENT;
-use crate::contextual_user_message::SKILL_FRAGMENT;
-
-pub const USER_INSTRUCTIONS_PREFIX: &str = "# AGENTS.md instructions for ";
-
-#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
-#[serde(rename = "user_instructions", rename_all = "snake_case")]
-pub(crate) struct UserInstructions {
-    pub directory: String,
-    pub text: String,
-}
-
-impl UserInstructions {
-    pub(crate) fn serialize_to_text(&self) -> String {
-        format!(
-            "{prefix}{directory}\n\n<INSTRUCTIONS>\n{contents}\n{suffix}",
-            prefix = AGENTS_MD_FRAGMENT.start_marker(),
-            directory = self.directory,
-            contents = self.text,
-            suffix = AGENTS_MD_FRAGMENT.end_marker(),
-        )
-    }
-}
-
-impl From<UserInstructions> for ResponseItem {
-    fn from(ui: UserInstructions) -> Self {
-        AGENTS_MD_FRAGMENT.into_message(ui.serialize_to_text())
-    }
-}
-
-#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
-#[serde(rename = "skill_instructions", rename_all = "snake_case")]
-pub(crate) struct SkillInstructions {
-    pub name: String,
-    pub path: String,
-    pub contents: String,
-}
-
-impl SkillInstructions {}
-
-impl From<SkillInstructions> for ResponseItem {
-    fn from(si: SkillInstructions) -> Self {
-        SKILL_FRAGMENT.into_message(SKILL_FRAGMENT.wrap(format!(
-            "<name>{}</name>\n<path>{}</path>\n{}",
-            si.name, si.path, si.contents
-        )))
-    }
-}
-
-#[cfg(test)]
-#[path = "user_instructions_tests.rs"]
-mod tests;

codex-rs/core/src/instructions/user_instructions_tests.rs

@@ -1,68 +0,0 @@
-use super::*;
-use codex_protocol::models::ContentItem;
-use pretty_assertions::assert_eq;
-
-#[test]
-fn test_user_instructions() {
-    let user_instructions = UserInstructions {
-        directory: "test_directory".to_string(),
-        text: "test_text".to_string(),
-    };
-    let response_item: ResponseItem = user_instructions.into();
-
-    let ResponseItem::Message { role, content, .. } = response_item else {
-        panic!("expected ResponseItem::Message");
-    };
-
-    assert_eq!(role, "user");
-
-    let [ContentItem::InputText { text }] = content.as_slice() else {
-        panic!("expected one InputText content item");
-    };
-
-    assert_eq!(
-        text,
-        "# AGENTS.md instructions for test_directory\n\n<INSTRUCTIONS>\ntest_text\n</INSTRUCTIONS>",
-    );
-}
-
-#[test]
-fn test_is_user_instructions() {
-    assert!(AGENTS_MD_FRAGMENT.matches_text(
-        "# AGENTS.md instructions for test_directory\n\n<INSTRUCTIONS>\ntest_text\n</INSTRUCTIONS>"
-    ));
-    assert!(!AGENTS_MD_FRAGMENT.matches_text("test_text"));
-}
-
-#[test]
-fn test_skill_instructions() {
-    let skill_instructions = SkillInstructions {
-        name: "demo-skill".to_string(),
-        path: "skills/demo/SKILL.md".to_string(),
-        contents: "body".to_string(),
-    };
-    let response_item: ResponseItem = skill_instructions.into();
-
-    let ResponseItem::Message { role, content, .. } = response_item else {
-        panic!("expected ResponseItem::Message");
-    };
-
-    assert_eq!(role, "user");
-
-    let [ContentItem::InputText { text }] = content.as_slice() else {
-        panic!("expected one InputText content item");
-    };
-
-    assert_eq!(
-        text,
-        "<skill>\n<name>demo-skill</name>\n<path>skills/demo/SKILL.md</path>\nbody\n</skill>",
-    );
-}
-
-#[test]
-fn test_is_skill_instructions() {
-    assert!(SKILL_FRAGMENT.matches_text(
-        "<skill>\n<name>demo-skill</name>\n<path>skills/demo/SKILL.md</path>\nbody\n</skill>"
-    ));
-    assert!(!SKILL_FRAGMENT.matches_text("regular text"));
-}