A GitHub check for pull request review
Know where
to start.
Arbor adds one quiet check, “Arbor impact”, to pull requests on GitHub. It lists what the change reaches, the called functions with no test found, and which files to read first.
Sign in with GitHub, add a repository and turn on checks for it. Your first 3 pull requests are free, no card needed.
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Credits, tools, and program benefits.
What calls
this function?
Three functions from an authored eight-file Python checkout. Arbor recorded who calls each one and how many functions reach it. The explorer highlights the line where each call on a caller path happens.
Explore the coderefund_calculate_money_The function you’re investigating12 functions reach this through direct or indirect calls.
Follow the pathsAuthored Python example, captured on September 23, 2026 with a local build of Arbor 3.0.0 plus unreleased repairs, before v3.0.3. Inspect the source and capture.
Arbor Cloud · The “Arbor impact” check
What does this
pull request reach?
- What it reaches
- Entry points, such as routes, handlers and jobs, whose calls lead to the changed functions.
- What to test
- Changed functions with callers and no test found.
- Where to start reading
- Changed files in order, with owners from CODEOWNERS.
- Dependencies
- Advisories for package versions the pull request added or updated in Cargo.lock, package-lock.json or npm-shrinkwrap.json. Other lockfiles aren’t checked.
- What Arbor couldn’t see
- The gaps in this run, listed every time.
Facts, not a verdict or a risk score. The check stays neutral unless a Team rule matches. Your first 3 pull requests are free, and new commits on a pull request are free in the same billing period, or during the trial.
Checks are off until you turn them on. Sign in with GitHub, add a repository, then turn on checks for it on the Analyses page. A pull request you analyze by hand there gets a private report, not a check.
Open source · MIT
Runs on
your machine.
Install the arbor CLI, then run arbor setup in your project. Queries answer from the index it writes to .arbor/. No account, no telemetry.
arbor callers your_functionLists each caller with its file and line. If several files define the name, each definition gets its own list. When a name has one definition and no callers, the answer says which kinds of call the graph can’t follow.
Read the CLI guideExample command. Replace your_function with a function from your indexed project.What can I use today?
You can use the open-source engine today: the arbor CLI and the arbor bridge MCP server, from GitHub, npm or crates.io. It runs on your machine and needs no account. Arbor Cloud is open too: sign in with GitHub, add a repository and turn on checks for it to get the check on its pull requests.
Does a connection mean something will break?
No. An edge means Arbor matched a call or a base class in the source to a definition, and some matches rest on a name alone. It doesn’t show that the code runs, or that changing it breaks anything. Dynamic imports and reflection can be missing and some impact counts run high, so read the code and run your tests. The sample explorer shows the call line for each step of its caller paths.
What does Cloud cost?
Your GitHub account starts with 3 pull requests, free and without a card, shared by every workspace it creates. After that, Developer is $19 a month for 50 pull requests per billing period, and Team is $79 a month for 250 pull requests and up to 5 members. Prices are per workspace, in US dollars, and Razorpay takes the payment. New commits on a pull request already analyzed are free in the same billing period, or during the trial, and failed, canceled or unsupported runs don’t use your allowance. Compare plans.