minimal-reproductionlisted

## Purpose You cannot reliably fix what you cannot reliably reproduce in isolation. Apply the subtraction method until a single file deterministically triggers the exact reported error. ## When to Use - A bug is tangled in app/UI/network layers and hard to debug in place - A failure must be handed to another engineer, team, or upstream project - Before bisecting or stress-testing, to get a fast deterministic signal ## Inputs - The failing code path and the error it produces - Sample data that triggers the failure, if any ## Workflow — the Subtraction Method 1. **Start with the failure.** Take the code path that fails. 2. **Remove the UI/Network.** If the bug is reported via a web request, write a script that calls the internal controller directly. 3. **Mock dependencies.** If the bug doesn't require the database, mock it. If it doesn't require the third-party API, mock it. Template: ```js // repro.js — minimal harness, no framework const { failingFunction } = require("./src/module"); const fakeDb = { query: async () => [{ id: 1, value: null }] }; // smallest stub that triggers it failingFunction(fakeDb, { payloadKey: "trigger-value" }) .then(() => { console.log("NO REPRO"); process.exit(0); }) .catch((err) => { console.error("REPRO:", err.message); process.exit(1); }); ``` (Exit `0` on no-repro / non-zero on repro also makes the script directly usable by `git bisect run`.) 4. **Prune data.** If the bug fails on a 10MB JSON payload,