chore: baseline sandbox (TS utils + vitest, 17 tests)

Author: saurabh

.gitignore

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+node_modules/
+dist/
+*.log
+.env
+.DS_Store

README.md

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+# MonkeyCode Sandbox
+
+Isolated demo codebase for MonkeyCode sidecar coding-task execution
+(map #15, ticket #21). A small, safe TypeScript utility library with baseline
+tests — a realistic but harmless codebase slice for automated coding demos.
+
+## Contents
+
+- `src/` — TypeScript utilities (string helpers, math helpers)
+- `tests/` — vitest baseline tests
+- No secrets, no credentials, no network access, no build/deploy steps
+
+## Setup
+
+```sh
+git clone https://github.com/saurabharch/monkeycode-sandbox.git
+cd monkeycode-sandbox
+pnpm install     # or: npm install
+pnpm test        # or: npm test
+```
+
+Requires Node 18+ and pnpm 8+ (npm works too).
+
+## Branch convention
+
+- Demo tasks work on branches named `demo/task-<n>-<slug>` (e.g. `demo/task-01-add-truncate`)
+- The `main` branch is the PR target for the automated-review demo (ticket #26)
+- Each demo task: implement against the task description, commit on the demo branch,
+  open a PR to `main`
+
+## Task area (what agents are expected to touch)
+
+The `src/` utilities are intentionally small with obvious gaps. A good demo task
+adds a new exported function with tests (e.g. `truncate`, `clamp`, `slugify`).
+
+## Notes
+
+- This repo is intentionally minimal — do not add real secrets or credentials.
+- Used by: ticket #23 (first coding task), ticket #26 (automated PR review demo).