Composition Contract

Every skill MUST follow these rules to be composable.

The Five Rules

1. Input Agnosticism

A skill must be able to operate on output from ANY other skill. Don't assume your input is raw user text — it might be pre-processed by another skill.

# Bad: Assumes input is raw user text
"Take the user's request and..."

# Good: Accepts any input
"Given the current context..."

2. Domain Respect

Never modify aspects outside your domain:

Skill Type	Stays In Its Lane
Voice skills	Don't restructure layout or process steps
Density skills	Don't change tone, personality, or factual content
Craft skills	Don't rewrite prose that isn't UI copy
Process skills	Don't impose voice or density preferences

3. Marker Preservation

If a skill produces structured output (tables, code blocks, frontmatter, templates), downstream skills must preserve that structure.

Compress the content INSIDE structures, not the structures themselves.

# Input from postmortem:
| Timeline | Event |
|----------|-------|
| 14:00 | Alert fired |
| 14:05 | Team notified |

# Compress must preserve the table structure
# Only compress the content inside cells

4. Signal Emission

When a skill recognizes it's in a multi-skill context, it should:

• State which domain it's handling
• Note if it's deferring on any aspect
• Flag conflicts it can't resolve alone

[density: caveman handling compression]
[voice deferred to blogger]

5. Graceful Degradation

If a skill can't fully operate alongside another (e.g., caveman + blogger have conflicting density preferences), it should:

1. Identify the conflict
2. Apply the precedence rules
3. Note what was deferred: [density deferred to caveman]

Anti-Patterns

Don't

• Hardcode references to specific other skills ("if blogger is active, do X")
• Override another skill's domain silently
• Assume you're the only skill running
• Drop structured output from upstream skills
• Refuse to operate because another skill's output "looks weird"
• Double-process (if input is already compressed, don't compress again)

Do

• Check if your domain is already handled — defer if so
• Preserve structure you didn't create
• State what you're handling and what you're not
• Accept pre-processed input gracefully
• Flag conflicts explicitly rather than silently resolving

The Litmus Test

Can two skills that have never seen each other's code work together on a single user request without breaking each other's output?

If yes, the protocol works. If no, one of them is violating the composition contract.