Extract codex-core-skills crate (#15749)

## Summary
- move skill loading and management into codex-core-skills
- leave codex-core with the thin integration layer and shared wiring

## Testing
- CI

---------

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

codex-rs/core/src/tools/handlers/shell.rs

@@ -11,9 +11,9 @@ use crate::exec_env::create_env;
 use crate::exec_policy::ExecApprovalRequest;
 use crate::function_tool::FunctionCallError;
 use crate::is_safe_command::is_known_safe_command;
+use crate::maybe_emit_implicit_skill_invocation;
 use crate::protocol::ExecCommandSource;
 use crate::shell::Shell;
-use crate::skills::maybe_emit_implicit_skill_invocation;
 use crate::tools::context::FunctionToolOutput;
 use crate::tools::context::ToolInvocation;
 use crate::tools::context::ToolPayload;
@@ -288,11 +288,12 @@ impl ToolHandler for ShellCommandHandler {
         let cwd = resolve_workdir_base_path(&arguments, turn.cwd.as_path())?;
         let params: ShellCommandToolCallParams =
             parse_arguments_with_base_path(&arguments, cwd.as_path())?;
+        let workdir = turn.resolve_path(params.workdir.clone());
         maybe_emit_implicit_skill_invocation(
             session.as_ref(),
             turn.as_ref(),
             &params.command,
-            params.workdir.as_deref(),
+            &workdir,
         )
         .await;
         let prefix_rule = params.prefix_rule.clone();

codex-rs/core/src/tools/handlers/unified_exec.rs

@@ -1,11 +1,11 @@
 use crate::function_tool::FunctionCallError;
 use crate::is_safe_command::is_known_safe_command;
+use crate::maybe_emit_implicit_skill_invocation;
 use crate::protocol::EventMsg;
 use crate::protocol::TerminalInteractionEvent;
 use crate::sandboxing::SandboxPermissions;
 use crate::shell::Shell;
 use crate::shell::get_shell_by_model_provided_path;
-use crate::skills::maybe_emit_implicit_skill_invocation;
 use crate::tools::context::ExecCommandToolOutput;
 use crate::tools::context::ToolInvocation;
 use crate::tools::context::ToolPayload;
@@ -147,11 +147,12 @@ impl ToolHandler for UnifiedExecHandler {
                 let cwd = resolve_workdir_base_path(&arguments, context.turn.cwd.as_path())?;
                 let args: ExecCommandArgs =
                     parse_arguments_with_base_path(&arguments, cwd.as_path())?;
+                let workdir = context.turn.resolve_path(args.workdir.clone());
                 maybe_emit_implicit_skill_invocation(
                     session.as_ref(),
-                    turn.as_ref(),
+                    context.turn.as_ref(),
                     &args.cmd,
-                    args.workdir.as_deref(),
+                    &workdir,
                 )
                 .await;
                 let process_id = manager.allocate_process_id().await;

codex-rs/core/src/tools/runtimes/mod.rs

@@ -4,9 +4,9 @@ Module: runtimes
 Concrete ToolRuntime implementations for specific tools. Each runtime stays
 small and focused and reuses the orchestrator for approvals + sandbox + retry.
 */
+use crate::SkillMetadata;
 use crate::path_utils;
 use crate::shell::Shell;
-use crate::skills::SkillMetadata;
 use crate::tools::sandboxing::ToolError;
 use codex_protocol::models::PermissionProfile;
 use codex_sandboxing::SandboxCommand;

codex-rs/core/src/tools/runtimes/shell/unix_escalation.rs

@@ -1,4 +1,5 @@
 use super::ShellRequest;
+use crate::SkillMetadata;
 use crate::error::CodexErr;
 use crate::error::SandboxErr;
 use crate::exec::ExecCapturePolicy;
@@ -12,7 +13,7 @@ use crate::sandboxing::ExecOptions;
 use crate::sandboxing::ExecRequest;
 use crate::sandboxing::SandboxPermissions;
 use crate::shell::ShellType;
-use crate::skills::SkillMetadata;
+use crate::skills_load_input_from_config;
 use crate::tools::runtimes::ExecveSessionApproval;
 use crate::tools::runtimes::build_sandbox_command;
 use crate::tools::sandboxing::SandboxAttempt;
@@ -487,11 +488,19 @@ impl CoreShellActionProvider {
     /// any skills.
     async fn find_skill(&self, program: &AbsolutePathBuf) -> Option<SkillMetadata> {
         let force_reload = false;
+        let turn_config = self.turn.config.as_ref();
+        let plugin_outcome = self
+            .session
+            .services
+            .plugins_manager
+            .plugins_for_config(turn_config);
+        let effective_skill_roots = plugin_outcome.effective_skill_roots();
+        let skills_input = skills_load_input_from_config(turn_config, effective_skill_roots);
         let skills_outcome = self
             .session
             .services
             .skills_manager
-            .skills_for_cwd(&self.turn.cwd, self.turn.config.as_ref(), force_reload)
+            .skills_for_cwd(&skills_input, force_reload)
             .await;
 
         let program_path = program.as_path();

codex-rs/core/src/tools/runtimes/shell/unix_escalation_tests.rs

@@ -8,6 +8,7 @@ use super::evaluate_intercepted_exec_policy;
 use super::extract_shell_script;
 use super::join_program_and_argv;
 use super::map_exec_result;
+use crate::SkillMetadata;
 #[cfg(target_os = "macos")]
 use crate::config::Constrained;
 #[cfg(target_os = "macos")]
@@ -19,7 +20,6 @@ use crate::protocol::GranularApprovalConfig;
 use crate::protocol::ReadOnlyAccess;
 use crate::protocol::SandboxPolicy;
 use crate::sandboxing::SandboxPermissions;
-use crate::skills::SkillMetadata;
 use codex_execpolicy::Decision;
 use codex_execpolicy::Evaluation;
 use codex_execpolicy::PolicyParser;