trust.py

"""
Federation Node — Trust Resolution (Phase 2 Vault)
==================================================
Contract: C-FED-NODE-001 v0.1.1

Trust tier resolution backed by Cloudflare D1.
"""
from __future__ import annotations

from datetime import datetime, timezone
from typing import Optional

from models import TrustTier, RefusalReason, FederationRefusal
import d1_client

def make_refusal(reason: RefusalReason, message: str, node_seal: str) -> dict:
    return FederationRefusal(
        refusal=True,
        reason=reason,
        message=message,
        node_seal=node_seal,
        timestamp=datetime.now(timezone.utc).isoformat(),
    ).model_dump()

async def resolve_trust_tier(sender_seal: str) -> TrustTier:
    """Resolve the trust tier for a sender based on D1 registry."""
    rs = await d1_client.execute_sql("SELECT tier FROM trust_registry WHERE seal = ?", [sender_seal])
    if rs:
        tier_str = rs[0]["tier"]
        try:
            return TrustTier(tier_str)
        except ValueError:
            pass
    return TrustTier.UNKNOWN

async def promote_to_trusted(seal: str, alias: str = ""):
    """Promote a seal to TRUSTED in the D1 registry."""
    await d1_client.execute_sql(
        '''INSERT INTO trust_registry (seal, alias, tier) 
           VALUES (?, ?, 'TRUSTED') 
           ON CONFLICT(seal) DO UPDATE 
           SET tier='TRUSTED', alias=excluded.alias, last_seen_at=CURRENT_TIMESTAMP''',
        [seal, alias]
    )

def apply_trust_policy(
    tier: TrustTier,
    default_action: str,
    blocked_behavior: str,
    node_seal: str,
) -> Optional[dict]:
    if tier == TrustTier.BLOCKED:
        if blocked_behavior == "SILENT_DROP":
            return {"action": "SILENT_DROP"}
        return make_refusal(
            RefusalReason.SENDER_BLOCKED,
            "Sender is on the blocklist. Refusal Protocol Active.",
            node_seal,
        )

    if tier == TrustTier.TRUSTED:
        return None 

    if default_action == "REFUSE":
        return make_refusal(
            RefusalReason.SENDER_NOT_TRUSTED,
            "Sender not in trusted list. Default policy: REFUSE.",
            node_seal,
        )

    if default_action == "QUARANTINE":
        return {"action": "QUARANTINE"}

    return None