Ground

Ground

This page tells how the ground slice of the core plugin claudetto checks the claims of a plan file. A user reads it to learn why Claude gets a deny on a plan, and how to fix it. A contributor reads it before an edit of slices/ground/.

What It Does for You

Claude can write a number, a file:line reference, or a convention with no source. An example is npx in a project that has bun.lock. The ground slice finds such claims in a plan file and denies the write. The check is a program. It makes no model call, because a check that guesses can block correct text.

The Hook

The slice adds one tool.call hook on Write and Edit, in the phase check. The hook checks only these files:

• A file under openspec/changes/.
• A file named proposal.md, design.md, or tasks.md.

For Write, the hook reads content. For Edit, it reads new_string. A write of any other file is not checked.

What Counts as a Source

A claim has a source when it is in one of these:

• A user message of the session.
• A tool result of the session.
• CLAUDE.md in the project root.
• The old text of the file that the call changes.

A tool result that is a deny of this check is not a source. It names each claim, so a retry would pass on it.

The Claims

Kind	The check fails when
Number	A number of 3 digits or more is in no user message and no tool result. A year does not count.
file:line	The file is found and has fewer lines than the reference.
Attribution	A sentence such as the user chose ... has words that are mostly not in a user message.
Done claim	The text says that tests, checks, lint, or a build pass, or that something is fixed, and the turn has no Bash call. A sentence with must, should, will, if, or a similar word is not a claim.
Convention	The text uses npm or npx in a project with bun.lock or bun.lockb, or pip in a project with uv.lock, and no user rule names the tool.

For a file:line reference, the check looks for the file at the project root first. Then it searches the folders below the root, but it skips node_modules and dot folders and reads at most 2,000 folders. If the check does not find the file, it skips the reference, because a guess would deny a correct one.

Text That Passes

• A line with (proposed) or [NEEDS CLARIFICATION: ...].
• A fenced code block.

The Deny

The deny lists each claim and gives three ways out:

1. Name the source: a user message, a tool result of this session, or a file of the project.
2. Mark the claim (proposed) or [NEEDS CLARIFICATION: ...].
3. Ask the user.

Claude then writes the text again.

Options and Cost

The slice has no userConfig key and no limit. The hook costs no request and no token. If the hook throws, Claude Code logs the failure and the call runs.

Replay

The ground slice checks the claims of a plan file. It denies a plan that cites a number, a line, or a convention with no source. This stops Claude from writing guesses as facts.

See Also

• Spec
• Goal
• Controls
• Sessions