Readable plain-text messages

Foundation

The constraints come from the reading environment, not the language:

• A phone viewport shows roughly 12-15 lines; longer messages collapse behind "Show more".
• Notification previews and channel lists show only the first line.
• Chat apps use proportional fonts and re-wrap text. Column alignment and leading-space indentation do not survive.
• Readers scan before they read: first "is this for me?", then the one fact they need.

Admission rule for symbols: a symbol earns its place only by showing structure — a boundary, a hierarchy, a key-value pair, a state, or a sequence. Symbols that perform attention or emotion (eye-catchers such as ＼ ／, decorative or tone emoji) belong to register and taste, not cognitive load; this skill never adds them, and uses no emoji at all.