---
epic: 10
story: 10.1
title: "Headers, Comments & Labels"
status: draft
---

## Epic 10 — Notepad UX (Cross-Platform Spec)
**Goal:** Consistent editor behavior specified once, implemented per platform.

### Story 10.1: Headers, Comments & Labels

As a user,
I want to organize my sheets with headers, comments, and labels,
So that my calculations are readable, structured, and self-documenting.

**Acceptance Criteria:**

**Given** a user types a line beginning with `#`
**When** the line is parsed by the engine
**Then** it is treated as a section heading and is not evaluated
**And** it is rendered visually as a heading (larger/bold text) on all platforms

**Given** a user types a line beginning with `//`
**When** the line is parsed by the engine
**Then** it is treated as a comment, is not evaluated, and produces no answer
**And** it is rendered in a dimmed/muted style on all platforms

**Given** a user types a line with a prefix ending in `:` before an expression (e.g., `Rent: 1500`)
**When** the line is parsed by the engine
**Then** the label portion (before and including `:`) is not evaluated
**And** only the expression after the label is evaluated and its result displayed in the answer column

**Given** headers, comments, and labels are used in a sheet
**When** the sheet is opened on any supported platform (macOS, web, CLI)
**Then** each element type is parsed identically by the shared engine
**And** visual rendering is appropriate to each platform's conventions