Load selected executor skills through extensions

codex-rs/Cargo.toml

@@ -212,6 +212,7 @@ codex-sandboxing = { path = "sandboxing" }
 codex-secrets = { path = "secrets" }
 codex-shell-command = { path = "shell-command" }
 codex-shell-escalation = { path = "shell-escalation" }
+codex-skills-extension = { path = "ext/skills" }
 codex-skills = { path = "skills" }
 codex-state = { path = "state" }
 codex-stdio-to-uds = { path = "stdio-to-uds" }

codex-rs/app-server-protocol/src/protocol/v2/thread.rs

@@ -11,6 +11,8 @@ use super::TurnEnvironmentParams;
 use super::TurnItemsView;
 use super::shared::v2_enum_from_core;
 use codex_experimental_api_macros::ExperimentalApi;
+pub use codex_protocol::capabilities::CapabilityRootLocation;
+pub use codex_protocol::capabilities::SelectedCapabilityRoot;
 use codex_protocol::config_types::CollaborationMode;
 use codex_protocol::config_types::Personality;
 use codex_protocol::config_types::ReasoningSummary;
@@ -153,6 +155,10 @@ pub struct ThreadStartParams {
     #[experimental("thread/start.dynamicTools")]
     #[ts(optional = nullable)]
     pub dynamic_tools: Option<Vec<DynamicToolSpec>>,
+    /// Capability roots selected for this thread by the hosting platform.
+    #[experimental("thread/start.selectedCapabilityRoots")]
+    #[ts(optional = nullable)]
+    pub selected_capability_roots: Option<Vec<SelectedCapabilityRoot>>,
     /// Test-only experimental field used to validate experimental gating and
     /// schema filtering behavior in a stable way.
     #[experimental("thread/start.mockExperimentalField")]

codex-rs/app-server/Cargo.toml

@@ -49,6 +49,7 @@ codex-hooks = { workspace = true }
 codex-otel = { workspace = true }
 codex-plugin = { workspace = true }
 codex-shell-command = { workspace = true }
+codex-skills-extension = { workspace = true }
 codex-utils-cli = { workspace = true }
 codex-utils-pty = { workspace = true }
 codex-backend-client = { workspace = true }

codex-rs/app-server/README.md

@@ -130,7 +130,7 @@ Example with notification opt-out:
 
 ## API Overview
 
-- `thread/start` — create a new thread; emits `thread/started` (including the current `thread.status`) and auto-subscribes you to turn/item events for that thread. When the request includes a `cwd` and the resolved sandbox is `workspace-write` or full access, app-server also marks that project as trusted in the user `config.toml`. Pass `sessionStartSource: "clear"` when starting a replacement thread after clearing the current session so `SessionStart` hooks receive `source: "clear"` instead of the default `"startup"`. Experimental `runtimeWorkspaceRoots` replaces the thread-scoped runtime workspace roots used to materialize `:workspace_roots`; paths must be absolute. For permissions, prefer experimental `permissions` profile selection by id; the legacy `sandbox` shorthand is still accepted but cannot be combined with `permissions`. Experimental `environments` selects the sticky execution environments for turns on the thread; omit it to use the server default, pass `[]` to disable environments, or pass explicit environment ids with per-environment `cwd`.
+- `thread/start` — create a new thread; emits `thread/started` (including the current `thread.status`) and auto-subscribes you to turn/item events for that thread. When the request includes a `cwd` and the resolved sandbox is `workspace-write` or full access, app-server also marks that project as trusted in the user `config.toml`. Pass `sessionStartSource: "clear"` when starting a replacement thread after clearing the current session so `SessionStart` hooks receive `source: "clear"` instead of the default `"startup"`. Experimental `runtimeWorkspaceRoots` replaces the thread-scoped runtime workspace roots used to materialize `:workspace_roots`; paths must be absolute. For permissions, prefer experimental `permissions` profile selection by id; the legacy `sandbox` shorthand is still accepted but cannot be combined with `permissions`. Experimental `environments` selects the sticky execution environments for turns on the thread; omit it to use the server default, pass `[]` to disable environments, or pass explicit environment ids with per-environment `cwd`. Experimental `selectedCapabilityRoots` selects environment-owned plugin or standalone-skill roots. Skills found below those roots are listed and read through the owning environment; other plugin capabilities are not activated yet.
 - `thread/resume` — reopen an existing thread by id so subsequent `turn/start` calls append to it. Accepts the same permission override rules as `thread/start`.
 - `thread/fork` — fork an existing thread into a new thread id by copying the stored history; if the source thread is currently mid-turn, the fork records the same interruption marker as `turn/interrupt` instead of inheriting an unmarked partial turn suffix. The returned `thread.forkedFromId` points at the source thread when known. Accepts `ephemeral: true` for an in-memory temporary fork, emits `thread/started` (including the current `thread.status`), and auto-subscribes you to turn/item events for the new thread. Experimental clients can pass `excludeTurns: true` when they plan to page fork history via `thread/turns/list` instead of receiving the full turn array immediately. Accepts the same permission override rules as `thread/start`.
 - `thread/start`, `thread/resume`, and `thread/fork` responses include the legacy `sandbox` compatibility projection. Experimental clients can read `runtimeWorkspaceRoots` for the thread-scoped runtime roots and `activePermissionProfile` for the named or implicit built-in profile identity/provenance when known.
@@ -249,6 +249,18 @@ Start a fresh thread when you need a new Codex conversation.
     // "permissions": ":workspace"
     // Experimental runtime roots for :workspace_roots materialization:
     // "runtimeWorkspaceRoots": ["/Users/me/project", "/Users/me/openai"],
+    // Experimental capability roots selected by the hosting platform:
+    "selectedCapabilityRoots": [
+        {
+            "id": "github@openai",
+            "location": {
+                "type": "environment",
+                "environmentId": "workspace",
+                // Opaque to app-server; interpreted in the selected environment.
+                "path": "/opt/cca/plugins/github"
+            }
+        }
+    ],
     // Do not send both "sandbox" and "permissions".
     "personality": "friendly",
     "serviceName": "my_app_server_client", // optional metrics tag (`service_name`)