[Feature Request] Simple mechanism for setting/accessing ALS from flows and tools

[mbleigh]

When building tool plugins, it's useful for the tools to be as broadly defined as possible; however, when actually using those tools it's useful for the LLM to have as narrow and concise a definition as possible.

It would be great to be able to do something like:

const myTool = defineTool({name: "myTool"}, async input => {
  const client = new WikiClient(getContext("wiki.server"));
});

defineFlow({name: "myFlow"}, async () => {
  setContext("wiki.server", {...});
  return generate({tools: [myTool], ...}); // passes context via ALS
});

The reason this is different from plugin config is that I discovered there are basically three kinds of config for tools:

1. Initialization-time config (plugin config handles this)
2. Inference-time config (LLM provides these arguments)
3. Contextual config (e.g. Auth, or in this case wiki server config)

It would be great to have facilities for (3).