The Pairing Froze the Oracle File Before Any Agent Patch Landed

Description and use

A developer pairs with a coding agent, freezing a human‑written oracle test before any agent patch, enforcing strict file edit rules, and ensuring exact cent calculations.

Problem

Free‑tier coding agents often generate patches that pass tests but break real‑world correctness because the same model writes both the patch and the assertions.

Outcome

The pairing established a reproducible protocol that keeps the oracle immutable, prevents the agent from altering tests, and ensures that any patch must pass strict cent‑level assertions before merging.

Workflow

• 1. Write five explicit constraints into pairing/oracle-session.md
• 2. Freeze the oracle by committing the human‑written test file before any agent patch
• 3. Record dead ends in the log to prevent repetition
• 4. Enforce the kept decision with a git‑diff allowlist hook that blocks edits outside invoice.py

Evidence

The senior did not open a model prompt first, and instead forced the pair to write constraints into a log.

Source

The oracle uses integer cents derived from Decimal values so the expected string does not depend on the buggy float path.

Source