diff --git a/netengine/spec/__init__.py b/netengine/spec/__init__.py
index 3fa4710..0f64019 100644
--- a/netengine/spec/__init__.py
+++ b/netengine/spec/__init__.py
@@ -7,6 +7,7 @@
     AuthoritySource,
     BoundaryPolicy,
     ResolverPolicy,
+    TrustBundle,
     default_authorities_for_spec,
     resolver_policy_from_boundary,
 )
@@ -18,6 +19,7 @@
     "AuthoritySource",
     "BoundaryPolicy",
     "ResolverPolicy",
+    "TrustBundle",
     "default_authorities_for_spec",
     "resolver_policy_from_boundary",
 ]
diff --git a/netengine/spec/authority.py b/netengine/spec/authority.py
index aa99adb..f8c501b 100644
--- a/netengine/spec/authority.py
+++ b/netengine/spec/authority.py
@@ -72,6 +72,39 @@ class ResolverPolicy(SpecModel):
     notes: list[str] = Field(default_factory=list)
 
 
+class TrustBundle(SpecModel):
+    """Trust metadata imported for a peered or federated world boundary."""
+
+    peer_id: str = Field(...)
+    peer_name: str | None = Field(default=None)
+    mode: GatewayCrossWorldMode = Field(...)
+    dns_suffixes: list[str] = Field(default_factory=list)
+    peer_root_ca: str | None = Field(default=None)
+    oidc_issuer: str | None = Field(default=None)
+    accepted_audiences: list[str] = Field(default_factory=list)
+    mail_domains: list[str] = Field(default_factory=list)
+    dkim_policy: str | None = Field(default=None)
+
+    @model_validator(mode="after")
+    def validate_trust_bundle(self) -> "TrustBundle":
+        """Validate cross-world trust metadata requirements."""
+        if self.mode == GatewayCrossWorldMode.NONE:
+            raise ValueError("trust bundle mode must be peered or federated, not none")
+
+        if not self.dns_suffixes:
+            raise ValueError("trust bundle dns_suffixes must not be empty")
+
+        if self.mode == GatewayCrossWorldMode.FEDERATED and not (
+            self.peer_root_ca or self.oidc_issuer
+        ):
+            raise ValueError(
+                "federated trust bundle requires at least one trust-bearing field "
+                "such as peer_root_ca or oidc_issuer"
+            )
+
+        return self
+
+
 class BoundaryPolicy(SpecModel):
     """Authority-layer policy for traffic and trust at the world boundary."""
 
diff --git a/tests/test_authority_spec.py b/tests/test_authority_spec.py
index 00875c3..9abc1ac 100644
--- a/tests/test_authority_spec.py
+++ b/tests/test_authority_spec.py
@@ -10,6 +10,7 @@
     AuthoritySource,
     BoundaryPolicy,
     ResolverPolicy,
+    TrustBundle,
     resolver_policy_from_boundary,
 )
 from netengine.spec.models import CrossWorldPeer, ServiceMirror
@@ -57,6 +58,66 @@ def test_authority_model_is_frozen() -> None:
         authority.operator = "other-operator"
 
 
+def test_trust_bundle_accepts_peered_dns_suffixes_without_trust_metadata() -> None:
+    bundle = TrustBundle(
+        peer_id="world-b",
+        peer_name="World B",
+        mode=GatewayCrossWorldMode.PEERED,
+        dns_suffixes=["world-b.test"],
+    )
+
+    assert bundle.peer_id == "world-b"
+    assert bundle.peer_name == "World B"
+    assert bundle.mode == GatewayCrossWorldMode.PEERED
+    assert bundle.dns_suffixes == ["world-b.test"]
+    assert bundle.accepted_audiences == []
+    assert bundle.mail_domains == []
+
+
+def test_trust_bundle_rejects_none_mode() -> None:
+    with pytest.raises(ValidationError, match="must be peered or federated"):
+        TrustBundle(
+            peer_id="world-b",
+            mode=GatewayCrossWorldMode.NONE,
+            dns_suffixes=["world-b.test"],
+        )
+
+
+def test_trust_bundle_requires_dns_suffixes() -> None:
+    with pytest.raises(ValidationError, match="dns_suffixes must not be empty"):
+        TrustBundle(peer_id="world-b", mode=GatewayCrossWorldMode.PEERED, dns_suffixes=[])
+
+
+def test_trust_bundle_federated_requires_trust_bearing_metadata() -> None:
+    with pytest.raises(ValidationError, match="trust-bearing field"):
+        TrustBundle(
+            peer_id="world-b",
+            mode=GatewayCrossWorldMode.FEDERATED,
+            dns_suffixes=["world-b.test"],
+        )
+
+
+def test_trust_bundle_federated_accepts_peer_root_ca_or_oidc_issuer() -> None:
+    ca_bundle = TrustBundle(
+        peer_id="world-b",
+        mode=GatewayCrossWorldMode.FEDERATED,
+        dns_suffixes=["world-b.test"],
+        peer_root_ca="-----BEGIN CERTIFICATE-----...",
+    )
+    oidc_bundle = TrustBundle(
+        peer_id="world-c",
+        mode="federated",
+        dns_suffixes=["world-c.test"],
+        oidc_issuer="https://issuer.world-c.test",
+        accepted_audiences=["netengine"],
+    )
+
+    assert ca_bundle.peer_root_ca == "-----BEGIN CERTIFICATE-----..."
+    assert oidc_bundle.mode == GatewayCrossWorldMode.FEDERATED
+    assert oidc_bundle.oidc_issuer == "https://issuer.world-c.test"
+    assert oidc_bundle.accepted_audiences == ["netengine"]
+
+
 def test_boundary_policy_defaults_to_isolated_no_cross_world() -> None:
     policy = BoundaryPolicy()