Protocol Boundary

The system contracts what it itself must understand. What only bots and humans need to understand stays opaque.

The test

Before adding anything to meadows-protocol, ask: does the server need this fact to do its structural job (route, store, generate, notify) — regardless of what the fact means?

Answer	Placement	Example
Yes, and meaning is irrelevant	Protocol	"This message reacts to message X"
Server only relays it untouched	Domain (bot/client code)	What a reaction emoji means
Only changes human perception	UI	Display formatting

In protocol

• Envelope fields (Message model)
• Event names (EventName constants)
• JWT claims (JWTClaims model)
• System-message bodies
• The label signaling mechanism
• Permissions list

Not in protocol

• The content payload of ordinary messages (opaque Markdown)
• Domain schemas (SLO results, export formats, todo shapes)
• What reaction emoji mean
• Form field semantics
• Which label schemas exist

Worked examples

Reactions

Protocol owns "this message reacts to message X" — the shape of the reaction event, the target_message_id field, the emoji field.

Domain owns what the reaction symbol means — whether it's a vote, a sentiment, or a status indicator.

Forms

Protocol owns the interactive-form label, the FORM_SUBMISSION MessageType, and the form_handling metadata structure. The server routes submissions via label subscriptions — no form_id registry.

Domain owns field semantics — what fields exist, what they're called, what validation rules apply.

Labels

Protocol owns the label triplet mechanism (origin, label, semver) and the Label NamedTuple shape. JSON Logic predicates (regex_match, semver_match, semver_eq) are implemented in meadows-jsonlogic.

Domain owns which schemas exist and what they're called.

The boundary rule

If you find yourself declaring a set of valid values (reaction emoji, form field types, schema names) in protocol, stop — that's vocabulary leaking upward. Protocol declares shapes; domain declares vocabulary.