Message Model

Parabiont carries one signed envelope per transfer. The envelope contains a capsule and a detached signature.

{
  "capsule": {
    "version": "parabiont-context/v0.1",
    "bond_id": "5e2a1f3c-9b7d-4a1e-8f2c-3d4b5a6c7d8e",
    "audience": "gemini-local",
    "purpose": "project-development",
    "issued_at": 1790000000,
    "expires_at": 1790000600,
    "policy_digest": "<64 hex chars>",
    "state": [
      {
        "id": "product-lophiarch",
        "kind": "fact",
        "topic": "positioning",
        "text": "Lophiarch is a policy-gated reconnaissance tool."
      }
    ]
  },
  "signature": "<base64 Ed25519 signature>"
}

Envelope

The envelope has exactly two keys: capsule and signature. Any extra key is rejected. The signature is Ed25519 over the canonical JSON of the capsule.

Canonical JSON means sorted keys, compact separators, no ASCII escaping, and UTF-8 encoding. Both sides must produce the same bytes or verification fails.

Capsule Fields

Field	Type	Description
version	string	Must be parabiont-context/v0.1.
bond_id	UUID string	Identifies this attachment; lowercase hex with hyphens.
audience	string	Lowercase identifier of the intended receiver.
purpose	string	Lowercase identifier of the engagement or task.
issued_at	integer	Unix seconds when the capsule was packed.
expires_at	integer	Unix seconds when the lease ends.
policy_digest	string	SHA-256 of the canonical policy document.
state	array	1–500 approved context items.

State Items

Each item is the minimal approved projection of a candidate item:

Field	Constraints
id	Letters, digits, hyphens; 1–64 chars.
kind	fact, decision, task, or constraint.
topic	Lowercase letters, digits, hyphens; 1–64 chars.
text	1–10000 chars.

Labels are intentionally not carried. They were used during filtering, not as part of the payload. A receiver re-evaluates the item under its own policy with the technical label applied.

Verification Rules

A receiver rejects the envelope when:

• The envelope has keys other than capsule and signature.
• The capsule fails schema validation.
• The signature does not verify against the issuer's public key.
• The current time is outside [issued_at, expires_at).
• The lease is longer than the receiver's configured lease_seconds.
• audience, purpose, or policy_digest does not match the receiver policy.
• Any item fails the receiver's own policy re-evaluation.
• The re-evaluated state differs from the signed state.

Re-evaluation matters: the signature authenticates that an operator reviewed the content, not that the receiver's policy still allows it.

Bond Storage

The receiver records the bond in SQLite. Revocation is local state: a revoked bond blocks future reads and re-delivery through that receiver. It cannot un-deliver content that a model has already consumed.