GitHub basics
Define the evaluation pull request input contract
Page 2 hardens the boundary around the pull request from `improve-evaluation` into main so bad inputs fail before the interesting algorithm runs.
1Learn the idea
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Define what may enter
The accepted input remains: local commits on improve-evaluation plus repository PR rules. Keep parsing and normalization in functions that do not score, train, or call a model. That split lets a test fail the boundary without blaming the core logic. The user-facing decision stays: propose a reviewed evaluation change for merge only after checks pass.
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Reject at the boundary
gh repo view --json nameWithOwner,defaultBranchRef --jq '{repo:.nameWithOwner,default:.defaultBranchRef.name}'
Expected evidence: repo and default branch JSON. If the contract is silent on a bad value, later debugging will look like an algorithm bug when it is really a data bug.
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Keep transforms testable
Write one assertion for a neighboring valid input to the evaluation pull request so tightening the boundary does not over-reject. Document field names and types the way a teammate would need them on day two of github-basics—not as comments you plan to delete.
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Lab notebook: name the fields
List every field in feature branch improve-evaluation with one commit and mark each as required, optional, or forbidden. Required fields must fail loudly when missing; optional fields need defaults you can quote in a test; forbidden fields (secrets, raw PII, path escapes) must never be accepted silently. This list is the contract for the evaluation pull request.
Add one sentence about encoding, units, or timezones if relevant to local commits on improve-evaluation plus repository PR rules. Contracts that ignore units create “correct” programs that still ship wrong decisions when someone tries to propose a reviewed evaluation change for merge only after checks pass.
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Worked judgment
Write the error string you want for the most likely bad input. Prefer ValueError('threshold out of range')-style messages over generic invalid input. The contract’s job is to make pushing straight to main, or opening a PR with failing checks ignored harder to confuse with a model or algorithm bug later.
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Why this stage matters for the evaluation pull request
At the data contract stage for github-basics, the job is narrower than finishing a product demo. You are creating one progressive evidence piece about feature branch improve-evaluation with one commit that later pages inherit without redefining success. Keep that fixture small enough to inspect by hand, keep outputs copy-pasteable as text, and refuse to narrate this baseline as if it were a production SLA: branch protection / required checks listed before opening the PR.
For this page specifically, success looks like malformed inputs rejected with field-named errors while still centering the user decision to propose a reviewed evaluation change for merge only after checks pass. If you cannot point to a file, command, or assertion that proves that for the evaluation pull request, stay on this page instead of advancing.
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Before you start
Why this matters
Invent one malformed input that the pull request from improve-evaluation into main might accidentally accept. Predict the exception or rejection message. After you run the contract code, compare your prediction with the real failure text.
In the wild
See how this idea shows up as a product and a company — then come back to the lesson. Skills transfer across vendors.
Related lessons
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