@agent-browser/eve: let consumers gate the instructions fragment per session

[khalidsalomao]

Package: @agent-browser/eve 0.35.2 (unchanged in 0.38.2), eve 0.68.

Problem

The extension contributes a static instructions.md ("# Browser … Start with navigate, then snapshot …"). Eve treats extension instruction fragments as additive, so a consumer cannot remove or condition them.

We enable the browser per agent, as with our other capabilities. Agents without it still get the browser guidance in every system prompt, which tells the model to use tools it does not have. To keep that coherent, we register a refusal stub under every browser__* name, which adds about 20 tools to every request. Eve's dynamic tools could gate the tools per session, but only if the guidance can be gated with them.

Request

Make the guidance conditional through consumer config, for example as an extension/instructions.ts dynamic instruction:

• instructions: false to omit the fragment, so the consumer supplies guidance where the browser is enabled; or
• enabled?: (ctx) => boolean | Promise<boolean>, checked at session.started, gating both the instructions and the tools.

Either option lets a consumer scope the browser to the sessions that use it with documented Eve APIs.