github-spec-kit/extensions/agent-context

Coding Agent Context Extension

This bundled extension manages the coding agent context/instruction file (e.g. CLAUDE.md, .github/copilot-instructions.md, AGENTS.md, GEMINI.md, …) for the active integration.

It owns the lifecycle of the managed section delimited by the configurable start/end markers (defaults: <!-- SPECKIT START --> / <!-- SPECKIT END -->). For .mdc files, it also ensures the YAML frontmatter (the metadata block at the top of the file) contains alwaysApply: true. Otherwise, everything outside the managed section is untouched.

NOTE: Spec Kit itself never touches your agent context file. This extension is the only thing that does, and it's opt-in: install it if you want the block kept in sync, skip it if you'd rather manage that file yourself.

Why an extension?

Not every Spec Kit user wants Spec Kit to write into the coding agent's context file. Keeping this behavior in a dedicated, opt-in extension lets users:

• Choose whether to install it at all - specify init does not install it. Add it explicitly when you want Spec Kit to manage the agent context file; when it is absent, the file is never modified, and when it is disabled, its automatic hooks do not run.
• Customize the markers by editing .specify/extensions/agent-context/agent-context-config.yml (agent-context-config.yml in this repo) - the bundled scripts honor the context_markers value.
• Synchronize multiple agent anchors by setting context_files when a project intentionally uses more than one coding agent context file, such as AGENTS.md and CLAUDE.md.
• Refresh on demand by running the speckit.agent-context.update command in your agent, or automatically through the hooks declared in extension.yml (after_specify, after_plan).

Installation

To install the extension, from the root of an initialized Spec Kit project, run:

specify extension add agent-context

Disabling

specify extension disable agent-context

# Re-enable it
specify extension enable agent-context

While this extension is disabled (or not installed), nothing in Spec Kit creates, updates, or removes the managed block - the __CONTEXT_FILE__ placeholder in any template is left as-is, and the extension's own config is never read.

Commands

Command	Description
speckit.agent-context.update	Refresh the managed section in the agent context file with the current plan path.

NOTE: The command ID above is canonical. Invoke it using the syntax for your integration: /speckit.agent-context.update for dot-command integrations; /speckit-agent-context-update for hyphen/skills integrations (including Forge and Cline); $speckit-agent-context-update for Codex or ZCode in skills mode; or /skill:speckit-agent-context-update for Kimi.

Configuration

All configuration flows through the extension's own config file at .specify/extensions/agent-context/agent-context-config.yml (agent-context-config.yml in the repo).

Requirements

The bundled update scripts require Python 3 with PyYAML for YAML/upsert processing (PowerShell can also use ConvertFrom-Yaml when available).

PyYAML ships with the specify CLI and is normally available via the same python3 interpreter. If a hook reports "PyYAML is required … not available in the current Python environment", it means the system python3 differs from the one used to install Spec Kit. To resolve, run:

pip install pyyaml
# or target the specific interpreter Spec Kit uses:
/path/to/speckit-python -m pip install pyyaml

Issues

For any other issues, please create an issue in the official GitHub repo.