Lathe Verify

Lathe — Verify a Tutorial

Follow a stored tutorial exactly as a reader would, in a throwaway directory, and record whether it actually works. Triggered by /lathe-verify <slug>. Isolation is by instruction — a fresh mktemp -d, under the user's normal interactive permissions. No sandbox-exec, no Docker.

This skill is read-only with respect to the tutorial: never edit the parts or the metadata. The only writes are status updates through lathe verify-result.

Protocol

1. Mark it in-flight first:

   lathe verify-result <slug> --status verifying
   

   This sets the spinner badge in the web UI. If it errors with "cannot verify while it is extending", stop — a part is mid-flight; don't verify on top of it.

2. Make a fresh scratch dir and work there:

   cd "$(mktemp -d)"
   

   Everything the tutorial tells the reader to create happens here, not in the user's project. (Status is set by this skill, never by the web/CLI button — so an unclicked button can never strand a tutorial at verifying.)

3. Follow each part in order. Read ~/.lathe/tutorials/<slug>/part-NN.md from part-01 up. Install the prerequisites, create the files and paste the code blocks exactly as written, in order, then run the ## Checkpoint command and compare against the stated expected output.

   • Skip the pedagogical and provenance callouts — > [!PREDICT], > [!RECALL], and > [!UNVERIFIED] are not verifiable steps. They prompt the reader or flag uncertainty; there's nothing to execute.
   • Treat the Checkpoint commands and code blocks as the executable surface.

4. Record the terminal result with the matching command:

   • Everything works → lathe verify-result <slug> --status verified
   • A required tool isn't installed → lathe verify-result <slug> --status skipped This is not a failure — it's the ⚠️ Skipped badge, meaning "couldn't run it here," not "the tutorial is wrong." Use it whenever the toolchain the tutorial needs (compiler, runtime, SDK) is missing locally.
   • Something genuinely breaks (wrong output, code doesn't compile, a step contradicts itself) →

     lathe verify-result <slug> --status failed \
       --part <part-NN.md> \
       --failed-step <1-indexed step number within that part> \
       --error "<the error message or mismatched output>"
     

5. Report to the user what happened — verified clean, skipped (and which tool was missing), or where exactly it failed.

Boundaries

• Read-only on the tutorial. Never edit a part-NN.md, metadata.json, or verify-result.json directly — the only state writes are via lathe verify-result.
• No OS sandboxing. Isolation is the mktemp -d scratch dir plus instruction, under the user's normal permission model. Don't reach for sandbox-exec or Docker.
• Skipped ≠ failed. A missing toolchain is skipped. Reserve failed for the tutorial being genuinely broken.
• Status is always set by this skill, never by the handoff button.