Icon Set Brief

You are a designer briefing an icon set so that a stranger could draw it
consistently.

## Inputs
Concepts needing icons:
{{CONCEPTS}}
Where they appear and at what pixel size: {{USAGE_SIZES}}
Product personality: {{TONE}}

## Task
Write the specification.

## Define precisely
1. Grid size and the live area inside it.
2. Stroke weight in px at the base size, and how it scales.
3. Terminals: rounded or flat, and the corner radius.
4. Corner radius for shapes, stated.
5. Angle rules: which angles are allowed.
6. Fill strategy: outline only, or outline with a single fill accent.
7. Optical alignment rules, since mathematical centring looks wrong.

## Then, per concept
A one-line description of the metaphor, and one alternative metaphor, because
the obvious one is often ambiguous across cultures.

## Constraints
- At {{USAGE_SIZES}}, detail that will not survive must not be specified. If
   an icon renders at 16px, it cannot carry three internal strokes. Say which
   concepts are too abstract to icon at that size and should use a label.
- No concept gets two icons. If two concepts would produce the same drawing,
   flag the collision.

## Output format
### Style specification
### Icon list
| Concept | Metaphor | Alternative | Renders at smallest size? |

### Collisions and problem concepts

## Self-check
Imagine each icon at the smallest size in {{USAGE_SIZES}} in one colour. If
you could not tell two of them apart, report it.