---
name: since-cutoff
description: Find which dependency APIs this project's Python code uses changed after the model's training cutoff (no model calls), write short AGENTS.md or CLAUDE.md notes from the API diff, each with its source, and keep them in step with the lockfile; optionally measure which of the changes the model gets wrong. Use when the user asks whether the model knows their library versions, when code keeps failing on renamed or removed library APIs, or after upgrading dependencies.
argument-hint: "[scan | sync | status | run] [--apply] [--quick] [--model provider:model]"
allowed-tools: Bash(since-cutoff scan:*), Bash(since-cutoff sync:*), Bash(since-cutoff status:*), Bash(since-cutoff run:*), Bash(since-cutoff models:*), Bash(since-cutoff unapply:*), Bash(uvx since-cutoff:*), Bash(pipx run since-cutoff:*), Read
license: MIT
compatibility: Needs since-cutoff on PATH, or uv or pipx to run it, and network access to PyPI. `run` also needs model access (the claude CLI or a provider API key); `scan`, `sync` and `status` make no model calls, and `status` works offline.
---

# since-cutoff

`since-cutoff` is a command-line tool. It does the measuring itself by calling a fresh copy of
the model with no tools and no project context, so **do not answer the probe tasks yourself and
do not guess results**. Run the tool and report what it prints.

## Steps

1. Work from the project root (the directory with `pyproject.toml`, `requirements.txt` or a lockfile).
2. Pick the command. Use `$ARGUMENTS` if the user gave any; otherwise:
   - quick look, no model calls: `since-cutoff scan` (then offer `sync`, step 7)
   - full measurement, with notes a model writes and keeps only when their example
     type-checks: `since-cutoff run --quick`
3. Name the model. Without `--model`, the tool tests the model your coding agent is set up with
   (`SINCE_CUTOFF_MODEL`; inside Claude Code, only Claude Code's settings; elsewhere the Claude
   Code, Codex, OpenCode and Aider settings, the project's before the user's) and says where
   it read it ("model from ..."). If that is not the model you are, or it warns that no model
   setting was found, add `--model <provider>:<model>` for the model you are (for example
   `--model openai:gpt-5.4`, or `--model claude-code:<model>` for a model picked with
   `/model`). `run` calls Claude Code models through the `claude` CLI and other models through
   their provider's API key.
4. Before `run`, tell the user that it sends prompts (package names, versions, public API
   signatures and generated tasks, never their source code) to the model provider they choose,
   uses their API credits or Claude Code usage, and can take 5-20 minutes. Wait for a yes.
   `scan` needs no confirmation.
5. Run it. If `since-cutoff` is not installed, use `uvx since-cutoff <args>` (or
   `pipx run since-cutoff <args>`). Start `run` in the background or with a long timeout, not a
   2-minute foreground call. Everything is cached, so re-running after an interruption resumes
   quickly.
6. Summarise the result card: the model and its training cutoff, how many dependencies changed
   after the cutoff, what was stale, and the held-out before/after numbers. Quote each interval
   with the number it belongs to: the bootstrap CI goes with the difference of the task-level
   rates, the other CI with "changes fixed: X of Y". If the run compared baseline notes
   (`--compare`), give each block's "changes fixed" with its CI, and call one block better
   only when report.md's head-to-head sign test for it has a small p-value.
7. Only write notes into the user's files if they asked for it. After `scan`, run
   `since-cutoff sync --dry-run`, show the user the diff it prints, and only when they agree run
   `since-cutoff sync --yes`: it writes the notes from the API diff into a marked block in
   AGENTS.md (or CLAUDE.md if that is the file the project uses) and, run again later, keeps
   them in step with the lockfile. Exit code 4 means the block was edited by hand: tell the
   user, and pass `--force` only if they say so. After `run`, `--apply` writes that run's
   notes in place of the whole block; `since-cutoff sync` then adds the notes from the diff
   for the other changed APIs the code uses, keeping the run's `[type-checked]` ones.
   `since-cutoff unapply` removes the block again. `since-cutoff status` says, without the
   network, whether the notes still match the lockfile; from since-cutoff 0.4.0 the Claude Code
   plugin runs it when a session starts (the first time, uvx downloads since-cutoff).
8. The notes in that block are API reference facts about the versions the project pins: what
   was removed, renamed or deprecated after the release at your training cutoff, each tagged
   with what was checked (`[diff]`: a static comparison of the two releases' public APIs). Check
   them when you write code that uses those libraries.

The full report is written to `.since-cutoff/report.md`; read it when the user wants details.

## If something fails

- No lockfile or pinned versions found: tell the user which file the tool asked for; do not
  invent versions.
- A model or login error during `run`: report the message and offer `scan`, which makes no
  model calls.

## Quick lookups without a run

If the since-cutoff MCP server is connected (the Claude Code plugin starts it), its tools answer
from a static diff, with no model calls: `api_changes` (one package, optionally one `symbol`),
`project_changes` (every dependency of the project) and `model_cutoff`. Pass your own model id
as `model`. Use them before writing code against a dependency that may be newer than your
training data; use the CLI above when the user wants the model measured or notes written.