The Lab Notes

Anthropic

Claude Code adds mods, plugins that can change deeper behavior

Claude Code 2.1.287 adds Claude Mods, which let plugins modify deeper behavior, plus a built-in mod that runs a side agent alongside a session.

The Lab Notes ·

A gold and cream clockwork gear in the center, with a dark navy gradient on the left and a black field on the right filled with linked pink, yellow, purple and teal rings.

Anthropic’s Claude Code now lets plugins modify “deeper behavior” through a feature called Claude Mods, but the changelog does not say what a mod can change.

The feature is in Claude Code 2.1.287, according to the entry dated Oct. 1, 2026 on the Claude Code changelog at code.claude.com. The npm registry shows the release published at 16:59 UTC that day, after 2.1.286 on Sept. 30 and 2.1.285 on Sept. 29. The npm “latest” tag points to 2.1.287, while “stable” is still 2.1.285.

A built-in mod watches the session

The one mod the changelog names is You should know, which it describes as “a side agent watches your back and flags things you or Claude might miss.” Users turn it on with /plugin enable cc-plugin-you-should-know@builtin, and the changelog says it is available “for first-party sessions with telemetry on.”

The changelog does not say how the side agent decides what to flag. It also does not point to separate documentation for mods.

Most of the release is fixes

Most of Claude Code 2.1.287 is fixes. The changelog entry lists many of them, covering permissions, screen reader mode and remote sessions, alongside a few additions.

Self-hosted runner sessions that use Anthropic-managed git now get a built-in gh api, REST only, on macOS and Linux machines where the GitHub CLI is not installed. The agents view has a new n:<text> filter that matches session names and tasks.

Opus 4.7 and later, along with Fable, now default to a 1M context window on Bedrock, Vertex, Foundry and the Claude apps gateway, with no [1m] suffix. Setting CLAUDE_CODE_DISABLE_1M_CONTEXT=1 keeps the 200K window.

For MCP servers, alwaysLoad: false now defers all of that server’s tools behind tool search. Servers on the 2025-11-25 protocol can also send URL prompts, for example to sign in. The changelog says a server that no longer connects after the update needs "bareElicitationCapability": true in its MCP config entry.

Analysis

We think a plugin that can change deeper behavior, paired with a built-in agent that runs alongside a session, widens what a plugin can touch. The changelog gives no detail on the limits of a mod, so we cannot say how far that reach goes.

The telemetry condition also means You should know is unavailable to some users from the start. Anyone who runs Claude Code with telemetry off, or outside a first-party session, will not see it.