Source Intelligence

DisclaimerUnofficial, and not affiliated with Anthropic. Nearly all of this is read straight out of what ships: npm bundles, captured prompts, published docs. Anthropic's own notes go in verbatim, marked as theirs. The rest is my reading, and every entry carries the strings behind it. If one looks wrong, vote it down and say why.

All of v2.1.242 Home All releases olderv2.1.241 v2.1.243newer
Claude Code v2.1.242

Plugins can drive the session directly, with per-plugin budgets

Use it now
Useful4 Signal5
Plugins Notable

Code-based plugin hooks get a full in-process API to drive the session, budgeted per plugin.

What

Plugin hooks written in code now get an in-process API for talking to the running session: status lines and toasts, asking the user a question, reading session messages and turn count, listing and spawning agents, calling and listing tools, registering new tools, and calling MCP servers. Every one of those is budgeted so a misbehaving plugin cannot flood you. Nothing in this build sets a flag for the surface as a whole, so it is present for everyone on 2.1.242.

Details
  • Toasts past the eighth in a session are dropped to the debug log, with a single warning toast to say so.
  • Asking the user a question is refused past a per-session count and within a minimum interval of the previous question.
  • Spawning agents is capped both per session and by how many run at once.
  • Tool registration is capped per plugin, refuses reserved MCP server names, and refuses to shadow an MCP server you already have configured. Success and failure are measured, including the cases where no registrar exists yet and where the tool is registered but not yet visible.
  • The build also ships a separate worker script entry point for running these hooks outside the main process.
Evidence

plugin_function_hooks_register_tool

Strings lifted out of the shipped bundle, so the claim above can be checked against them.

See this entry in the whole of v2.1.242 →