feat(agent): add local Codex Skill management and invocation

canvas-agent/src/canvas/session.test.ts

@@ -202,7 +202,7 @@ test("new clients receive the current Codex state and later updates", (t) => {
     t.after(() => client.close());
 
     const hello = client.event("hello");
-    assert.equal(field(hello, "protocolVersion"), 3);
+    assert.equal(field(hello, "protocolVersion"), 4);
     assert.deepEqual(field(hello, "workspace"), { activeThreadId: "thread-2" });
     assert.deepEqual(field(hello, "codex"), { busy: true, threadId: "thread-2", turnId: "turn-1" });
     assert.deepEqual(field(hello, "pendingApprovals"), [{ requestId: "approval-1", threadId: "thread-2" }]);

canvas-agent/src/canvas/session.ts

@@ -12,7 +12,7 @@ type PendingRequest = { clientId: string; resolve: (value: unknown) => void; rej
 type TurnAttachment = { clientId: string; id: string; name: string; type: string; size: number; width: number; height: number; dataUrl: string };
 type ReplayEvent = { type: string; payload: Record<string, unknown> };
 export type CodexState = { busy: boolean; threadId: string; turnId: string };
-export const AGENT_PROTOCOL_VERSION = 3;
+export const AGENT_PROTOCOL_VERSION = 4;
 
 const SITE_TOOLS = new Set<ToolName>([
     "site_navigate",