docs(tool-cordis): state the sandbox stance as steering, not containment

The sandbox docs overclaimed a containment contract the design never makes:
"capability access is routed through cordis services, never Node built-ins,
so everything a mounted plugin does stays inspectable and disposable". The
host-realm helpers on the sandbox global (harness, console, btoa) are
reachable functions, so mount code that goes looking can reach the host realm
through one of them — accepted under the trust stance, because the ctx a
mount ultimately receives is fully privileged anyway. Reword the sandbox
module doc, the README trust stance, and the RFC sandbox-semantics section to
say exactly that: the traps and small global surface STEER honest code onto
the cordis services; they are not a security boundary.
This commit is contained in:
imccyu
2026-07-09 18:51:44 +08:00
parent 3e9527278a
commit db857f62c0
3 changed files with 10 additions and 7 deletions

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@@ -12,7 +12,7 @@ Exact model-facing schemas: [the generated tool catalog](../../../docs/tool-cata
## Trust stance
The sandbox isolates the global context only — it is not a security boundary. No Node API is provided: `require`, the timers, and `fetch` are callable traps that throw a redirect to the cordis alternative (`ctx.fs` / `ctx.web` / `ctx.bash` / `inject: ['timer']` + `ctx.setTimeout`); `process` and `Buffer` are `undefined`; `globalThis` writes stay inside. The `ctx` a mounted plugin's `apply` receives is a whitelist façade — register tools, observe events, provide/consume services, use timers; framework internals (`ctx.root`, `ctx.fiber`, `ctx.extend`, `ctx.plugin`, …) are withheld — but the capabilities it does expose reach the real runtime, so load this plugin as deliberately as you would grant a bash tool.
The sandbox isolates the global context only — it is not a security boundary. No Node API is provided: `require`, the timers, and `fetch` are callable traps that throw a redirect to the cordis alternative (`ctx.fs` / `ctx.web` / `ctx.bash` / `inject: ['timer']` + `ctx.setTimeout`); `process` and `Buffer` are `undefined`; `globalThis` writes stay inside. These traps steer honest code onto the cordis services; they do not contain a mount that goes looking — the host-realm helpers on the sandbox global (`harness`, `console`, `btoa`) are reachable functions, so mount code can reach the host realm and Node through one of them, which is fine because `ctx` is fully privileged anyway. The `ctx` a mounted plugin's `apply` receives is a whitelist façade — register tools, observe events, provide/consume services, use timers; framework internals (`ctx.root`, `ctx.fiber`, `ctx.extend`, `ctx.plugin`, …) are withheld — but the capabilities it does expose reach the real runtime, so load this plugin as deliberately as you would grant a bash tool.
## Config