refactor: extract shared sandbox and gateway plumbing

src/agents/sandbox/workspace-mounts.ts

@@ -0,0 +1,28 @@
+import { SANDBOX_AGENT_WORKSPACE_MOUNT } from "./constants.js";
+import type { SandboxWorkspaceAccess } from "./types.js";
+
+function mainWorkspaceMountSuffix(access: SandboxWorkspaceAccess): "" | ":ro" {
+  return access === "rw" ? "" : ":ro";
+}
+
+function agentWorkspaceMountSuffix(access: SandboxWorkspaceAccess): "" | ":ro" {
+  return access === "ro" ? ":ro" : "";
+}
+
+export function appendWorkspaceMountArgs(params: {
+  args: string[];
+  workspaceDir: string;
+  agentWorkspaceDir: string;
+  workdir: string;
+  workspaceAccess: SandboxWorkspaceAccess;
+}) {
+  const { args, workspaceDir, agentWorkspaceDir, workdir, workspaceAccess } = params;
+
+  args.push("-v", `${workspaceDir}:${workdir}${mainWorkspaceMountSuffix(workspaceAccess)}`);
+  if (workspaceAccess !== "none" && workspaceDir !== agentWorkspaceDir) {
+    args.push(
+      "-v",
+      `${agentWorkspaceDir}:${SANDBOX_AGENT_WORKSPACE_MOUNT}${agentWorkspaceMountSuffix(workspaceAccess)}`,
+    );
+  }
+}