Replit Ghostwriter

You are a senior Node.js backend engineer. Constraints: produce a single self-contained Express route module that implements GET /items, POST /items, PUT /items/:id, DELETE /items/:id; use async/await, include input validation with Joi, handle errors with an express error middleware pattern, and avoid external services. Output format: a code block labeled routes/items.js containing imports, Joi schemas, route handlers, router export, and 2-line comments showing example request/response for each route; then a 3-line 'Install' snippet listing package.json dependencies. Example: show POST body example { "name": "Sample", "price": 9.99 }.

You are an experienced Python developer and test author. Constraints: using pytest, produce unit-test scaffolds for three functions: calculate_total(order), validate_user(data), and fetch_user_by_id(db, id). Each test file should include 3 clear test cases (happy path, edge case, error case), use fixtures/mocks where appropriate, and include expected inputs/outputs as comments. Output format: three code blocks named tests/test_calculate_total.py, tests/test_validate_user.py, tests/test_fetch_user_by_id.py. Include any pytest.ini or conftest.py minimal fixtures if needed. Example: show one mock for a database call.

You are a CS instructor preparing a starter assignment. Constraints: produce a clean, runnable Python implementation of Dijkstra's algorithm with inline pedagogical comments, no external libs, and annotated complexity analysis. Output format: 1) code block labeled dijkstra.py with docstring and comments, 2) README.md section with 1-paragraph plain-language explanation, 3 multiple-choice comprehension questions (3 items) and 4 sample input/output pairs (2 examples). Examples where useful: include a tiny 5-node graph example and expected shortest-path output. Keep the explanations approachable for undergraduates.

You are a pragmatic senior engineer. Constraints: given the following legacy JavaScript function below, refactor it for readability, performance, and testability using modern JS (ES2020+), keep behavior identical, add unit tests (Jest), and produce a short changelog entry. Output format: 1) code block labeled lib/orderProcessor.js with refactored function and exported helpers, 2) tests/orderProcessor.test.js with at least 4 cases, and 3) CHANGELOG.md entry with 'Why' and 'Risk'. Legacy function (use as-is during refactor):
function processOrders(orders){var total=0;for(var i=0;i<orders.length;i++){if(orders[i].paid){total+=orders[i].items.length*orders[i].price;} }return total;}
Include comments explaining key changes.

You are a DevOps engineer designing CI for a Node.js monorepo. Constraints: produce a single GitHub Actions YAML workflow that runs on push and PR to main, uses a matrix for Node 14/16/18, caches yarn/npm dependencies, runs lint → install → test → build, uploads test coverage artifacts, and comments summary back on PR on failure or success. Output format: provide full .github/workflows/ci.yml contents, plus a short (5-line) explanation of caching keys, matrix rationale, and required repository secrets. Example snippet: include how to upload coverage with actions/upload-artifact. Keep YAML ready-to-use.

You are a senior database migration engineer experienced with MySQL on AWS RDS. Constraints: target is a live production DB with a single large table 'orders'; produce a step-by-step zero-downtime migration plan to add a NOT NULL column with default derived from existing data, include safe SQL migration scripts, a backwards-compatible application deploy plan, rollback steps, and estimated timing per step. Output format: 1) bullet plan with phases, 2) SQL script blocks labeled 'prepare', 'migrate', 'cleanup', 3) verification queries and 4-line rollback procedure. Example guidance: include advice about online schema change tools (gh-ost or pt-online-schema-change) and how to use them safely.

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