diff --git a/decnet/ttp/misp_export.py b/decnet/ttp/misp_export.py
index 83f4d3ad..6863fbfa 100644
--- a/decnet/ttp/misp_export.py
+++ b/decnet/ttp/misp_export.py
@@ -47,6 +47,7 @@ def build_attacker_misp_event(
     artifacts: list[dict[str, Any]],
     smtp_targets: list[dict[str, Any]],
     commands: list[str] | None = None,
+    observations: list[dict[str, Any]] | None = None,
 ) -> dict[str, Any]:
     """Return a MISP event dict for *attacker*.
 
@@ -63,6 +64,7 @@ def build_attacker_misp_event(
         artifacts=artifacts,
         smtp_targets=smtp_targets,
         commands=commands,
+        observations=observations,
     )
     return _parse_bundle(bundle)
 
@@ -70,6 +72,7 @@ def build_attacker_misp_event(
 def build_fleet_misp_collection(
     rows: list[dict[str, Any]],
     ttp_by_attacker: dict[str, list[dict[str, Any]]],
+    observations_by_attacker: dict[str, list[dict[str, Any]]] | None = None,
 ) -> dict[str, Any]:
     """Return a MISP collection dict with one event per attacker in *rows*.
 
@@ -80,6 +83,7 @@ def build_fleet_misp_collection(
     attacker always has at least an IP) are silently omitted.
     """
     events: list[dict[str, Any]] = []
+    obs_map = observations_by_attacker or {}
     for row in rows:
         raw_cmds = row.get("commands") or []
         if isinstance(raw_cmds, str):
@@ -102,6 +106,7 @@ def build_fleet_misp_collection(
             artifacts=[],
             smtp_targets=[],
             commands=cmds,
+            observations=obs_map.get(row["uuid"]),
         )
         event = _parse_bundle(bundle)
         if event:
diff --git a/decnet/ttp/stix_custom.py b/decnet/ttp/stix_custom.py
new file mode 100644
index 00000000..70a492bd
--- /dev/null
+++ b/decnet/ttp/stix_custom.py
@@ -0,0 +1,100 @@
+"""DECNET-defined STIX 2.1 custom extension and object types.
+
+Import this module before parsing any DECNET-produced bundle so the types are
+registered with the stix2 library and ``stix2.parse(bundle, allow_custom=True)``
+rebuilds them as typed objects rather than opaque dicts.
+
+Classes
+-------
+DecnetActorFingerprintExt
+    ``@CustomExtension`` on ThreatActor — carries ``network_behavior``
+    (TCP/TLS/SSH sniffer rollup) and ``protocol_fingerprints`` (hashes +
+    raw orderings).
+XDecnetBehaveProfile
+    ``@CustomObject`` — autonomous STIX SDO carrying the BEHAVE-SHELL
+    observation stream for one attacker. Referenced from ThreatActor via
+    ``x_decnet_behave_profile_ref``.
+
+Constants
+---------
+ACTOR_FINGERPRINT_EXT_ID : str
+    Fixed ``extension-definition--`` ID for ``DecnetActorFingerprintExt``.
+FINGERPRINT_EXT_DEF : stix2.ExtensionDefinition
+    Singleton ``extension-definition`` SDO — add to every bundle that uses
+    the fingerprint extension.
+"""
+from __future__ import annotations
+
+import uuid as _uuid
+
+import stix2
+from stix2 import CustomExtension, CustomObject, ExtensionDefinition
+from stix2 import properties as _P
+
+_NS = _uuid.UUID("b5d2c3a1-8f4e-4d1b-9a6c-0e7f5b3d2c1a")
+
+# Stable ID for the actor fingerprint extension-definition SDO.
+ACTOR_FINGERPRINT_EXT_ID: str = (
+    f"extension-definition--{_uuid.uuid5(_NS, 'decnet-actor-fingerprint-v1')}"
+)
+
+_DECNET_ORG_ID = f"identity--{_uuid.uuid5(_NS, 'decnet-honeypot')}"
+
+
+@CustomExtension(
+    ACTOR_FINGERPRINT_EXT_ID,
+    [
+        ("extension_type", _P.StringProperty(required=True)),
+        ("network_behavior", _P.DictionaryProperty()),
+        ("protocol_fingerprints", _P.DictionaryProperty()),
+    ],
+)
+class DecnetActorFingerprintExt:
+    """Property extension on ThreatActor.
+
+    ``network_behavior`` keys: os_guess, hop_distance, tcp_fingerprint,
+    retransmit_count, timing_stats, phase_sequence, behavior_class,
+    beacon_interval_s, beacon_jitter_pct, tool_guesses.
+
+    ``protocol_fingerprints`` keys: ja3_hashes, hassh_hashes, kex_order_raw,
+    ssh_client_banners, tls_cert_sha256, payload_simhashes, c2_endpoints.
+    """
+
+
+@CustomObject(
+    "x-decnet-behave-profile",
+    [
+        ("schema_version", _P.IntegerProperty()),
+        ("kd_digraph_simhash", _P.StringProperty()),
+        ("observations", _P.ListProperty(_P.DictionaryProperty())),
+    ],
+)
+class XDecnetBehaveProfile:
+    """BEHAVE-SHELL observation stream for one attacker.
+
+    ``observations`` is a list of BEHAVE envelope dicts with keys:
+    primitive, value, confidence, window (start_ts/end_ts), source,
+    evidence_ref, identity_ref (optional).
+
+    ``schema_version`` matches ``OBSERVATION_SCHEMA_VERSION`` from
+    decnet_behave_shell.spec.envelope — bump when the envelope schema changes.
+
+    ``kd_digraph_simhash`` is the 8-byte digraph SimHash from
+    AttackerIdentity, hex-encoded. Null when identity has not been clustered.
+    """
+
+
+# Singleton extension-definition SDO.
+FINGERPRINT_EXT_DEF: stix2.ExtensionDefinition = ExtensionDefinition(
+    id=ACTOR_FINGERPRINT_EXT_ID,
+    name="DECNET Actor Fingerprint",
+    description=(
+        "Extends ThreatActor with DECNET-observed network behavior "
+        "(TCP/TLS/SSH stack-level fingerprints, IAT timing, phase sequence) "
+        "and BEHAVE-SHELL keystroke-dynamics observation primitives."
+    ),
+    schema="https://decnet.dev/schemas/actor-fingerprint/v1",
+    version="1.0.0",
+    extension_types=["property-extension"],
+    created_by_ref=_DECNET_ORG_ID,
+)
diff --git a/decnet/ttp/stix_export.py b/decnet/ttp/stix_export.py
index 5d36b450..433ba78e 100644
--- a/decnet/ttp/stix_export.py
+++ b/decnet/ttp/stix_export.py
@@ -23,6 +23,7 @@ public ATT&CK bundle by any consumer that already has it.
 """
 from __future__ import annotations
 
+import base64
 import json
 import uuid as _uuid
 from datetime import datetime, timezone
@@ -31,6 +32,12 @@ from typing import Any
 import stix2
 
 from decnet.ttp import attack_stix
+from decnet.ttp.stix_custom import (
+    ACTOR_FINGERPRINT_EXT_ID,
+    FINGERPRINT_EXT_DEF,
+    DecnetActorFingerprintExt,
+    XDecnetBehaveProfile,
+)
 
 # Deterministic DECNET org identity ID — stable across all bundles this
 # instance produces. Consumers can correlate across exports.
@@ -57,15 +64,32 @@ def _decnet_org() -> stix2.Identity:
     )
 
 
+def _parse_json_field(v: Any) -> Any:
+    """JSON-decode strings; return non-strings unchanged."""
+    if isinstance(v, str):
+        try:
+            return json.loads(v)
+        except Exception:
+            return v
+    return v
+
+
 def _threat_actor(
     attacker: dict[str, Any],
     identity: dict[str, Any] | None,
     created_by: str,
-) -> stix2.ThreatActor:
+    behavior: dict[str, Any] | None = None,
+    observations: list[dict[str, Any]] | None = None,
+) -> tuple[stix2.ThreatActor, "XDecnetBehaveProfile | None"]:
+    """Build a ThreatActor SDO plus an optional XDecnetBehaveProfile SDO.
+
+    Returns ``(threat_actor, behave_profile_or_None)``.
+    """
     if identity:
         name = f"DECNET-identity-{identity['uuid'][:8]}"
     else:
         name = f"DECNET-attacker-{attacker['uuid'][:8]}"
+
     kwargs: dict[str, Any] = dict(
         id=f"threat-actor--{_uuid.uuid5(_NS, attacker['uuid'])}",
         name=name,
@@ -73,20 +97,84 @@ def _threat_actor(
         created_by_ref=created_by,
         allow_custom=True,
     )
+
+    # Tier 1 — stable scalars
     if attacker.get("country_code"):
         kwargs["x_decnet_country_code"] = attacker["country_code"]
     if attacker.get("asn"):
         kwargs["x_decnet_asn"] = attacker["asn"]
     if attacker.get("as_name"):
         kwargs["x_decnet_as_name"] = attacker["as_name"]
+
+    # Tier 2 — DecnetActorFingerprintExt (network_behavior + protocol_fingerprints)
+    network_behavior: dict[str, Any] = {}
+    protocol_fingerprints: dict[str, Any] = {}
+
+    if behavior:
+        for key in ("os_guess", "hop_distance", "retransmit_count",
+                    "behavior_class", "beacon_interval_s", "beacon_jitter_pct"):
+            v = behavior.get(key)
+            if v is not None:
+                network_behavior[key] = v
+        for key in ("tcp_fingerprint", "timing_stats", "phase_sequence", "tool_guesses"):
+            v = _parse_json_field(behavior.get(key))
+            if v:
+                network_behavior[key] = v
+        for key in ("kex_order_raw", "ssh_client_banners"):
+            v = _parse_json_field(behavior.get(key))
+            if v:
+                protocol_fingerprints[key] = v
+
     if identity:
-        if identity.get("ja3_hashes"):
-            kwargs["x_decnet_ja3_hashes"] = identity["ja3_hashes"]
-        if identity.get("hassh_hashes"):
-            kwargs["x_decnet_hassh_hashes"] = identity["hassh_hashes"]
+        for key in ("ja3_hashes", "hassh_hashes", "tls_cert_sha256", "payload_simhashes"):
+            v = _parse_json_field(identity.get(key))
+            if v:
+                protocol_fingerprints[key] = v
         if identity.get("c2_endpoints"):
-            kwargs["x_decnet_c2_endpoints"] = identity["c2_endpoints"]
-    return stix2.ThreatActor(**kwargs)
+            protocol_fingerprints["c2_endpoints"] = _parse_json_field(
+                identity["c2_endpoints"]
+            )
+
+    if network_behavior or protocol_fingerprints:
+        ext_kwargs: dict[str, Any] = {"extension_type": "property-extension"}
+        if network_behavior:
+            ext_kwargs["network_behavior"] = network_behavior
+        if protocol_fingerprints:
+            ext_kwargs["protocol_fingerprints"] = protocol_fingerprints
+        kwargs["extensions"] = {
+            ACTOR_FINGERPRINT_EXT_ID: DecnetActorFingerprintExt(**ext_kwargs),
+        }
+
+    # Tier 3 — XDecnetBehaveProfile (BEHAVE observations)
+    behave_profile: XDecnetBehaveProfile | None = None
+    kd_hash: str | None = None
+    if identity:
+        raw_kd = identity.get("kd_digraph_simhash")
+        if raw_kd is not None:
+            if isinstance(raw_kd, (bytes, bytearray)):
+                kd_hash = raw_kd.hex()
+            elif isinstance(raw_kd, str) and raw_kd:
+                try:
+                    kd_hash = base64.b64decode(raw_kd).hex()
+                except Exception:
+                    kd_hash = raw_kd
+
+    obs_list = observations or []
+    if obs_list or kd_hash is not None:
+        from decnet_behave_shell.spec.envelope import OBSERVATION_SCHEMA_VERSION
+        profile_id = (
+            f"x-decnet-behave-profile--{_uuid.uuid5(_NS, attacker['uuid'])}"
+        )
+        behave_profile = XDecnetBehaveProfile(  # type: ignore[call-arg]
+            id=profile_id,
+            created_by_ref=created_by,
+            schema_version=OBSERVATION_SCHEMA_VERSION,
+            kd_digraph_simhash=kd_hash,
+            observations=obs_list,
+        )
+        kwargs["x_decnet_behave_profile_ref"] = profile_id
+
+    return stix2.ThreatActor(**kwargs), behave_profile
 
 
 def _attack_pattern_sdo(technique_id: str, created_by: str) -> stix2.AttackPattern | None:
@@ -157,6 +245,7 @@ def build_attacker_bundle(
     artifacts: list[dict[str, Any]],
     smtp_targets: list[dict[str, Any]],
     commands: list[str] | None = None,
+    observations: list[dict[str, Any]] | None = None,
 ) -> stix2.Bundle:
     """Assemble a STIX 2.1 Bundle for *attacker*.
 
@@ -185,9 +274,16 @@ def build_attacker_bundle(
     )
     objs.append(ip_obs)
 
-    # ── Threat actor ─────────────────────────────────────────────────
-    ta = _threat_actor(attacker, identity, org.id)
+    # ── Threat actor + BEHAVE profile ────────────────────────────────
+    ta, behave_profile = _threat_actor(
+        attacker, identity, org.id,
+        behavior=behavior,
+        observations=observations,
+    )
     objs.append(ta)
+    if behave_profile is not None:
+        objs.append(behave_profile)
+        objs.append(FINGERPRINT_EXT_DEF)
 
     # ── ATT&CK — attack-patterns + uses relationships + sightings ───
     # Build per-technique once; sightings reference the same AP STIX ID.
@@ -315,6 +411,7 @@ def build_attacker_bundle(
 def build_fleet_bundle(
     rows: list[dict[str, Any]],
     ttp_by_attacker: dict[str, list[dict[str, Any]]],
+    observations_by_attacker: dict[str, list[dict[str, Any]]] | None = None,
 ) -> stix2.Bundle:
     """Assemble a STIX 2.1 Bundle covering all attackers in *rows*.
 
@@ -324,6 +421,7 @@ def build_fleet_bundle(
     (too verbose; use the per-attacker endpoint for full fidelity).
     """
     objs_by_id: dict[str, Any] = {}
+    obs_map = observations_by_attacker or {}
 
     for row in rows:
         raw_cmds = row.get("commands") or []
@@ -349,6 +447,7 @@ def build_fleet_bundle(
             artifacts=[],
             smtp_targets=[],
             commands=cmds,
+            observations=obs_map.get(row["uuid"]),
         )
         for obj in bundle.objects:
             objs_by_id[obj.id] = obj
diff --git a/decnet/web/db/repository.py b/decnet/web/db/repository.py
index addd2b75..6d003f13 100644
--- a/decnet/web/db/repository.py
+++ b/decnet/web/db/repository.py
@@ -365,6 +365,35 @@ class BaseRepository(ABC):
         """
         raise NotImplementedError
 
+    @abstractmethod
+    async def list_observations_by_attacker(
+        self, attacker_uuid: str,
+    ) -> list[dict[str, Any]]:
+        """All BEHAVE-SHELL observations for *attacker_uuid*, ordered by
+        ``window_end_ts`` ASC, shaped as BEHAVE envelope dicts.
+
+        Each dict carries: ``primitive``, ``value``, ``confidence``,
+        ``window`` (``{start_ts, end_ts}``), ``source``, ``evidence_ref``,
+        and (when present) ``identity_ref``.
+
+        Empty list when the attacker has no observations. Used by the STIX
+        export to populate ``XDecnetBehaveProfile.observations``.
+        """
+        raise NotImplementedError
+
+    @abstractmethod
+    async def get_all_observations_for_export(
+        self,
+    ) -> dict[str, list[dict[str, Any]]]:
+        """Return ``{attacker_uuid: [observation_envelope, ...]}`` for all
+        attackers that have BEHAVE observations.
+
+        Used by the fleet STIX export to attach per-attacker observation
+        streams without N+1 queries. Same envelope shape as
+        ``list_observations_by_attacker``.
+        """
+        raise NotImplementedError
+
     async def upsert_observed_attachment(
         self,
         *,
diff --git a/decnet/web/db/sqlmodel_repo/observations.py b/decnet/web/db/sqlmodel_repo/observations.py
index 2a90c9f7..ddd7bceb 100644
--- a/decnet/web/db/sqlmodel_repo/observations.py
+++ b/decnet/web/db/sqlmodel_repo/observations.py
@@ -29,6 +29,21 @@ from decnet.web.db.models import Attacker, ObservationRow
 from decnet.web.db.sqlmodel_repo._helpers import _MixinBase
 
 
+def _to_envelope(row: "ObservationRow") -> dict:
+    """Map an ObservationRow to a BEHAVE envelope dict for STIX export."""
+    d: dict = {
+        "primitive": row.primitive,
+        "value": row.value,
+        "confidence": row.confidence,
+        "window": {"start_ts": row.window_start_ts, "end_ts": row.window_end_ts},
+        "source": row.source,
+        "evidence_ref": row.evidence_ref,
+    }
+    if row.identity_ref is not None:
+        d["identity_ref"] = row.identity_ref
+    return d
+
+
 class ObservationsMixin(_MixinBase):
     """Mixin: methods composed onto :class:`SQLModelRepository`."""
 
@@ -209,6 +224,36 @@ class ObservationsMixin(_MixinBase):
             )
             return (await session.execute(stmt)).scalar_one_or_none() is not None
 
+    async def list_observations_by_attacker(
+        self, attacker_uuid: str,
+    ) -> list[dict[str, Any]]:
+        """All observations for *attacker_uuid*, ordered by ``window_end_ts``
+        ASC, shaped as BEHAVE envelope dicts.
+        """
+        async with self._session() as session:
+            stmt = (
+                select(ObservationRow)
+                .where(ObservationRow.attacker_uuid == attacker_uuid)
+                .order_by(ObservationRow.window_end_ts)
+            )
+            rows = (await session.execute(stmt)).scalars().all()
+            return [_to_envelope(row) for row in rows]
+
+    async def get_all_observations_for_export(
+        self,
+    ) -> dict[str, list[dict[str, Any]]]:
+        """Return ``{attacker_uuid: [envelope, ...]}`` for all attackers."""
+        async with self._session() as session:
+            stmt = (
+                select(ObservationRow)
+                .order_by(ObservationRow.attacker_uuid, ObservationRow.window_end_ts)
+            )
+            rows = (await session.execute(stmt)).scalars().all()
+            result: dict[str, list[dict[str, Any]]] = {}
+            for row in rows:
+                result.setdefault(row.attacker_uuid, []).append(_to_envelope(row))
+            return result
+
     # Order desc(ts) reserved as the most-recent-first listing if a
     # paginated UI surface lands later. Not exposed today; named here
     # so a future grep finds the canonical desc-ts pattern.
diff --git a/decnet/web/router/attackers/api_export_attacker_misp.py b/decnet/web/router/attackers/api_export_attacker_misp.py
index 4b04ff41..beb9e9ff 100644
--- a/decnet/web/router/attackers/api_export_attacker_misp.py
+++ b/decnet/web/router/attackers/api_export_attacker_misp.py
@@ -65,6 +65,7 @@ async def api_export_attacker_misp(
         repo.get_attacker_artifacts(uuid),
         repo.list_smtp_targets(uuid),
         repo.list_attacker_commands_deduped(uuid),
+        repo.list_observations_by_attacker(uuid),
     )
     behavior = cast(dict[str, Any] | None, results[0])
     identity = cast(dict[str, Any] | None, results[1])
@@ -74,6 +75,7 @@ async def api_export_attacker_misp(
     artifacts = cast(list[dict[str, Any]], results[5])
     smtp_targets = cast(list[dict[str, Any]], results[6])
     commands = cast(list[str], results[7])
+    observations = cast(list[dict[str, Any]], results[8])
 
     event = build_attacker_misp_event(
         attacker=attacker,
@@ -88,6 +90,7 @@ async def api_export_attacker_misp(
         artifacts=artifacts,
         smtp_targets=smtp_targets,
         commands=commands,
+        observations=observations,
     )
     return Response(
         content=json.dumps(event, default=str),
diff --git a/decnet/web/router/attackers/api_export_attacker_stix.py b/decnet/web/router/attackers/api_export_attacker_stix.py
index c4792633..70670aaf 100644
--- a/decnet/web/router/attackers/api_export_attacker_stix.py
+++ b/decnet/web/router/attackers/api_export_attacker_stix.py
@@ -69,6 +69,7 @@ async def api_export_attacker_stix(
         repo.get_attacker_artifacts(uuid),
         repo.list_smtp_targets(uuid),
         repo.list_attacker_commands_deduped(uuid),
+        repo.list_observations_by_attacker(uuid),
     )
     behavior = cast(dict[str, Any] | None, results[0])
     identity = cast(dict[str, Any] | None, results[1])
@@ -78,6 +79,7 @@ async def api_export_attacker_stix(
     artifacts = cast(list[dict[str, Any]], results[5])
     smtp_targets = cast(list[dict[str, Any]], results[6])
     commands = cast(list[str], results[7])
+    observations = cast(list[dict[str, Any]], results[8])
 
     bundle = build_attacker_bundle(
         attacker=attacker,
@@ -92,6 +94,7 @@ async def api_export_attacker_stix(
         artifacts=artifacts,
         smtp_targets=smtp_targets,
         commands=commands,
+        observations=observations,
     )
     return Response(
         content=bundle.serialize(pretty=True, indent=2),
diff --git a/decnet/web/router/attackers/api_export_attackers_misp.py b/decnet/web/router/attackers/api_export_attackers_misp.py
index b68560b0..1d644793 100644
--- a/decnet/web/router/attackers/api_export_attackers_misp.py
+++ b/decnet/web/router/attackers/api_export_attackers_misp.py
@@ -43,13 +43,15 @@ async def api_export_attackers_misp(
     user: dict[str, Any] = Depends(require_viewer),
 ) -> Response:
     """Download a MISP collection JSON covering every observed attacker."""
-    rows, ttp_by_attacker = await asyncio.gather(
+    rows, ttp_by_attacker, obs_by_attacker = await asyncio.gather(
         repo.get_all_attackers_for_export(),
         repo.get_all_ttp_rollups_for_export(),
+        repo.get_all_observations_for_export(),
     )
     collection = build_fleet_misp_collection(
         rows=rows,
         ttp_by_attacker=ttp_by_attacker,
+        observations_by_attacker=obs_by_attacker,
     )
     ts = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
     return Response(
diff --git a/decnet/web/router/attackers/api_export_attackers_stix.py b/decnet/web/router/attackers/api_export_attackers_stix.py
index 2660b3bb..01b60cce 100644
--- a/decnet/web/router/attackers/api_export_attackers_stix.py
+++ b/decnet/web/router/attackers/api_export_attackers_stix.py
@@ -42,8 +42,12 @@ async def api_export_attackers_stix(
     user: dict[str, Any] = Depends(require_viewer),
 ) -> Response:
     """Download a STIX 2.1 bundle covering every observed attacker."""
-    rows, ttp_by_attacker = await _gather_fleet_data()
-    bundle = build_fleet_bundle(rows=rows, ttp_by_attacker=ttp_by_attacker)
+    rows, ttp_by_attacker, obs_by_attacker = await _gather_fleet_data()
+    bundle = build_fleet_bundle(
+        rows=rows,
+        ttp_by_attacker=ttp_by_attacker,
+        observations_by_attacker=obs_by_attacker,
+    )
     ts = datetime.now(timezone.utc).strftime("%Y%m%dT%H%M%SZ")
     return Response(
         content=bundle.serialize(pretty=True, indent=2),
@@ -56,10 +60,15 @@ async def api_export_attackers_stix(
     )
 
 
-async def _gather_fleet_data() -> tuple[list[dict[str, Any]], dict[str, list[dict[str, Any]]]]:
+async def _gather_fleet_data() -> tuple[
+    list[dict[str, Any]],
+    dict[str, list[dict[str, Any]]],
+    dict[str, list[dict[str, Any]]],
+]:
     import asyncio
-    rows, ttp_by_attacker = await asyncio.gather(
+    rows, ttp_by_attacker, obs_by_attacker = await asyncio.gather(
         repo.get_all_attackers_for_export(),
         repo.get_all_ttp_rollups_for_export(),
+        repo.get_all_observations_for_export(),
     )
-    return rows, ttp_by_attacker
+    return rows, ttp_by_attacker, obs_by_attacker
diff --git a/tests/db/test_base_repo.py b/tests/db/test_base_repo.py
index 68bc8133..12735941 100644
--- a/tests/db/test_base_repo.py
+++ b/tests/db/test_base_repo.py
@@ -111,6 +111,10 @@ class DummyRepo(BaseRepository):
         await super().get_log_histogram(*a, **kw); return []
     async def has_observations_for_evidence(self, evidence_ref):
         await super().has_observations_for_evidence(evidence_ref); return False
+    async def list_observations_by_attacker(self, attacker_uuid):
+        await super().list_observations_by_attacker(attacker_uuid); return []
+    async def get_all_observations_for_export(self):
+        await super().get_all_observations_for_export(); return {}
     async def get_attacker_uuid_by_ip(self, ip):
         await super().get_attacker_uuid_by_ip(ip); return None
     # TTP rollup surface (TTP_TAGGING.md)
@@ -253,6 +257,10 @@ async def test_base_repo_coverage():
     await dr.get_log_histogram()
     with pytest.raises(NotImplementedError):
         await dr.has_observations_for_evidence("shard:x#1")
+    with pytest.raises(NotImplementedError):
+        await dr.list_observations_by_attacker("a")
+    with pytest.raises(NotImplementedError):
+        await dr.get_all_observations_for_export()
     with pytest.raises(NotImplementedError):
         await dr.get_attacker_uuid_by_ip("1.1.1.1")
     with pytest.raises(NotImplementedError):
diff --git a/tests/ttp/test_stix_custom.py b/tests/ttp/test_stix_custom.py
new file mode 100644
index 00000000..b0511aa4
--- /dev/null
+++ b/tests/ttp/test_stix_custom.py
@@ -0,0 +1,157 @@
+"""Unit tests for decnet/ttp/stix_custom.py custom STIX types.
+
+Verifies that:
+- DecnetActorFingerprintExt instantiates, serialises, and round-trips.
+- XDecnetBehaveProfile instantiates, serialises, and round-trips.
+- Both types survive a full bundle parse with allow_custom=True.
+- FINGERPRINT_EXT_DEF is a valid ExtensionDefinition SDO.
+"""
+from __future__ import annotations
+
+import json
+import uuid as _uuid
+
+import pytest
+import stix2
+
+from decnet.ttp.stix_custom import (
+    ACTOR_FINGERPRINT_EXT_ID,
+    FINGERPRINT_EXT_DEF,
+    DecnetActorFingerprintExt,
+    XDecnetBehaveProfile,
+)
+
+_NS = _uuid.UUID("b5d2c3a1-8f4e-4d1b-9a6c-0e7f5b3d2c1a")
+_ORG_ID = f"identity--{_uuid.uuid5(_NS, 'decnet-honeypot')}"
+
+
+def test_ext_id_is_extension_definition():
+    assert ACTOR_FINGERPRINT_EXT_ID.startswith("extension-definition--")
+
+
+def test_fingerprint_ext_def_valid():
+    assert FINGERPRINT_EXT_DEF.id == ACTOR_FINGERPRINT_EXT_ID
+    assert FINGERPRINT_EXT_DEF.type == "extension-definition"
+    assert "property-extension" in FINGERPRINT_EXT_DEF.extension_types
+
+
+def test_decnet_actor_fingerprint_ext_roundtrip():
+    net = {"os_guess": "Linux 4.x", "hop_distance": 7, "retransmit_count": 1}
+    fp = {"ja3_hashes": ["abc123"], "kex_order_raw": ["curve25519-sha256"]}
+    ext = DecnetActorFingerprintExt(
+        extension_type="property-extension",
+        network_behavior=net,
+        protocol_fingerprints=fp,
+    )
+    raw = json.loads(ext.serialize())
+    assert raw["extension_type"] == "property-extension"
+    assert raw["network_behavior"]["os_guess"] == "Linux 4.x"
+    assert raw["protocol_fingerprints"]["ja3_hashes"] == ["abc123"]
+
+
+def test_decnet_actor_fingerprint_ext_partial():
+    ext = DecnetActorFingerprintExt(
+        extension_type="property-extension",
+        network_behavior={"behavior_class": "scanning"},
+    )
+    raw = json.loads(ext.serialize())
+    assert "protocol_fingerprints" not in raw
+
+
+def test_x_decnet_behave_profile_roundtrip():
+    obs = [
+        {
+            "primitive": "motor.input_modality",
+            "value": "typed",
+            "confidence": 0.9,
+            "window": {"start_ts": 1.0, "end_ts": 2.0},
+            "source": "ssh",
+            "evidence_ref": "shard:dky/ssh/2026-01-01.jsonl#1",
+        }
+    ]
+    profile = XDecnetBehaveProfile(  # type: ignore[call-arg]
+        id=f"x-decnet-behave-profile--{_uuid.uuid5(_NS, 'attacker-1')}",
+        created_by_ref=_ORG_ID,
+        schema_version=1,
+        kd_digraph_simhash="deadbeef12345678",
+        observations=obs,
+    )
+    raw = json.loads(profile.serialize())
+    assert raw["type"] == "x-decnet-behave-profile"
+    assert raw["schema_version"] == 1
+    assert raw["kd_digraph_simhash"] == "deadbeef12345678"
+    assert len(raw["observations"]) == 1
+    assert raw["observations"][0]["primitive"] == "motor.input_modality"
+
+
+def test_x_decnet_behave_profile_stix2_parse_roundtrip():
+    profile = XDecnetBehaveProfile(  # type: ignore[call-arg]
+        id=f"x-decnet-behave-profile--{_uuid.uuid5(_NS, 'attacker-2')}",
+        created_by_ref=_ORG_ID,
+        schema_version=1,
+        kd_digraph_simhash=None,
+        observations=[],
+    )
+    parsed = stix2.parse(profile.serialize(), allow_custom=True)
+    assert type(parsed).__name__ == "XDecnetBehaveProfile"
+
+
+def test_threat_actor_with_extension_bundle_roundtrip():
+    """Full bundle round-trip: ThreatActor with ext + profile SDO + ext-def SDO."""
+    net = {"os_guess": "FreeBSD", "hop_distance": 3}
+    fp = {"hassh_hashes": ["h1h2h3"]}
+    ext = DecnetActorFingerprintExt(
+        extension_type="property-extension",
+        network_behavior=net,
+        protocol_fingerprints=fp,
+    )
+    profile_id = f"x-decnet-behave-profile--{_uuid.uuid5(_NS, 'attacker-rt')}"
+    obs = [
+        {
+            "primitive": "cognitive.exploration_style",
+            "value": "targeted",
+            "confidence": 0.85,
+            "window": {"start_ts": 100.0, "end_ts": 200.0},
+            "source": "ssh",
+            "evidence_ref": "shard:dky/ssh/2026-01-02.jsonl#42",
+        }
+    ]
+    profile = XDecnetBehaveProfile(  # type: ignore[call-arg]
+        id=profile_id,
+        created_by_ref=_ORG_ID,
+        schema_version=1,
+        kd_digraph_simhash="cafebabe00000000",
+        observations=obs,
+    )
+    ta = stix2.ThreatActor(
+        id=f"threat-actor--{_uuid.uuid5(_NS, 'attacker-rt')}",
+        name="DECNET-test-actor",
+        threat_actor_types=["unknown"],
+        created_by_ref=_ORG_ID,
+        extensions={ACTOR_FINGERPRINT_EXT_ID: ext},
+        x_decnet_behave_profile_ref=profile_id,
+        allow_custom=True,
+    )
+    bundle = stix2.Bundle(
+        objects=[FINGERPRINT_EXT_DEF, profile, ta], allow_custom=True
+    )
+    parsed = stix2.parse(bundle.serialize(), allow_custom=True)
+
+    parsed_ta = next(o for o in parsed.objects if o.type == "threat-actor")
+    parsed_ext = parsed_ta.extensions[ACTOR_FINGERPRINT_EXT_ID]
+    parsed_profile = next(
+        o for o in parsed.objects if o.type == "x-decnet-behave-profile"
+    )
+
+    # Extension is typed, not a bare dict
+    assert type(parsed_ext).__name__ == "DecnetActorFingerprintExt"
+    assert parsed_ext.network_behavior["os_guess"] == "FreeBSD"
+    assert parsed_ext.protocol_fingerprints["hassh_hashes"] == ["h1h2h3"]
+
+    # Profile SDO is typed and lossless
+    assert type(parsed_profile).__name__ == "XDecnetBehaveProfile"
+    assert parsed_profile.kd_digraph_simhash == "cafebabe00000000"
+    assert parsed_profile.observations[0]["primitive"] == "cognitive.exploration_style"
+
+    # Ref survives
+    assert parsed_ta.x_decnet_behave_profile_ref == profile_id
diff --git a/tests/ttp/test_stix_export_threat_actor_extensions.py b/tests/ttp/test_stix_export_threat_actor_extensions.py
new file mode 100644
index 00000000..0455cb90
--- /dev/null
+++ b/tests/ttp/test_stix_export_threat_actor_extensions.py
@@ -0,0 +1,266 @@
+"""Integration tests for the x_decnet_* ThreatActor extensions in stix_export.py.
+
+Covers:
+- Skinny attacker (no behavior, no identity, no observations) → no extension block,
+  no profile SDO, no extension-definition SDO.
+- Attacker with behavior → extension block with network_behavior populated.
+- Attacker with identity fingerprints → protocol_fingerprints group.
+- Attacker with BEHAVE observations → x-decnet-behave-profile SDO in bundle,
+  x_decnet_behave_profile_ref on ThreatActor, extension-definition SDO present.
+- kd_digraph_simhash hex-encoded correctly (bytes and base64 inputs).
+- Full inter-DECNET round-trip: stix2.parse(bundle, allow_custom=True) yields
+  typed extension objects, not bare dicts.
+"""
+from __future__ import annotations
+
+import base64
+import json
+import uuid as _uuid
+from datetime import datetime, timezone
+
+import pytest
+import stix2
+
+from decnet.ttp.stix_custom import (
+    ACTOR_FINGERPRINT_EXT_ID,
+    DecnetActorFingerprintExt,
+    XDecnetBehaveProfile,
+)
+from decnet.ttp.stix_export import build_attacker_bundle
+
+_NS = _uuid.UUID("b5d2c3a1-8f4e-4d1b-9a6c-0e7f5b3d2c1a")
+
+
+def _attacker(uid: str = "att-aaaabbbbccccdddd") -> dict:
+    return {
+        "uuid": uid,
+        "ip": "1.2.3.4",
+        "first_seen": datetime(2026, 1, 1, tzinfo=timezone.utc),
+        "last_seen": datetime(2026, 1, 31, tzinfo=timezone.utc),
+        "event_count": 100,
+        "country_code": "US",
+        "asn": 15169,
+        "as_name": "GOOGLE",
+    }
+
+
+def _behavior() -> dict:
+    return {
+        "os_guess": "Linux 4.x",
+        "hop_distance": 7,
+        "tcp_fingerprint": json.dumps({
+            "window": 65535, "wscale": 6, "mss": 1460,
+            "options_sig": "MSTNNT", "has_sack": True, "ipid_class": "zero",
+        }),
+        "kex_order_raw": json.dumps(["curve25519-sha256", "ecdh-sha2-nistp256"]),
+        "ssh_client_banners": json.dumps(["SSH-2.0-OpenSSH_8.9"]),
+        "retransmit_count": 3,
+        "behavior_class": "brute_force",
+        "beacon_interval_s": 60.0,
+        "beacon_jitter_pct": 0.05,
+        "timing_stats": json.dumps({"mean": 1.2, "stdev": 0.3}),
+        "phase_sequence": json.dumps({"recon_end": "2026-01-10T00:00:00"}),
+        "tool_guesses": json.dumps(["hydra"]),
+    }
+
+
+def _identity(uid: str = "ident-1111222233334444") -> dict:
+    return {
+        "uuid": uid,
+        "ja3_hashes": json.dumps(["abc123def456"]),
+        "hassh_hashes": json.dumps(["hashhash01"]),
+        "tls_cert_sha256": json.dumps(["a" * 64]),
+        "payload_simhashes": json.dumps(["deadbeef12345678"]),
+        "c2_endpoints": json.dumps([{"host": "bad.example.com", "port": 4444}]),
+        "kd_digraph_simhash": None,
+    }
+
+
+def _obs() -> list[dict]:
+    return [
+        {
+            "primitive": "motor.input_modality",
+            "value": "typed",
+            "confidence": 0.9,
+            "window": {"start_ts": 1000.0, "end_ts": 2000.0},
+            "source": "ssh",
+            "evidence_ref": "shard:dky/ssh/2026-01-01.jsonl#1",
+        },
+        {
+            "primitive": "cognitive.exploration_style",
+            "value": "targeted",
+            "confidence": 0.8,
+            "window": {"start_ts": 2000.0, "end_ts": 3000.0},
+            "source": "ssh",
+            "evidence_ref": "shard:dky/ssh/2026-01-01.jsonl#2",
+        },
+    ]
+
+
+def _get_ta(bundle: stix2.Bundle) -> stix2.ThreatActor:
+    return next(o for o in bundle.objects if o.type == "threat-actor")
+
+
+def test_skinny_attacker_no_extension():
+    """No behavior, no identity, no observations → no extension block."""
+    bundle = build_attacker_bundle(
+        attacker=_attacker(),
+        behavior=None, identity=None, intel=None,
+        technique_rollup=[], raw_tags=[], artifacts=[],
+        smtp_targets=[], observations=None,
+    )
+    ta = _get_ta(bundle)
+    assert not getattr(ta, "extensions", None)
+    profile_sdos = [o for o in bundle.objects if o.type == "x-decnet-behave-profile"]
+    assert len(profile_sdos) == 0
+    ext_def_sdos = [o for o in bundle.objects if o.type == "extension-definition"]
+    assert len(ext_def_sdos) == 0
+
+
+def test_behavior_produces_network_behavior_group():
+    bundle = build_attacker_bundle(
+        attacker=_attacker(),
+        behavior=_behavior(), identity=None, intel=None,
+        technique_rollup=[], raw_tags=[], artifacts=[],
+        smtp_targets=[], observations=None,
+    )
+    ta = _get_ta(bundle)
+    assert ta.extensions, "expected extension block"
+    ext = ta.extensions[ACTOR_FINGERPRINT_EXT_ID]
+    nb = ext.network_behavior
+    assert nb["os_guess"] == "Linux 4.x"
+    assert nb["hop_distance"] == 7
+    assert nb["retransmit_count"] == 3
+    assert nb["behavior_class"] == "brute_force"
+    assert nb["tcp_fingerprint"]["window"] == 65535
+    assert nb["timing_stats"]["mean"] == pytest.approx(1.2)
+    assert "hydra" in nb["tool_guesses"]
+
+
+def test_behavior_produces_protocol_fingerprints_from_behavior():
+    bundle = build_attacker_bundle(
+        attacker=_attacker(),
+        behavior=_behavior(), identity=None, intel=None,
+        technique_rollup=[], raw_tags=[], artifacts=[],
+        smtp_targets=[], observations=None,
+    )
+    ta = _get_ta(bundle)
+    ext = ta.extensions[ACTOR_FINGERPRINT_EXT_ID]
+    fp = ext.protocol_fingerprints
+    assert fp["kex_order_raw"] == ["curve25519-sha256", "ecdh-sha2-nistp256"]
+    assert fp["ssh_client_banners"] == ["SSH-2.0-OpenSSH_8.9"]
+
+
+def test_identity_fingerprints_in_protocol_group():
+    bundle = build_attacker_bundle(
+        attacker=_attacker(),
+        behavior=None, identity=_identity(), intel=None,
+        technique_rollup=[], raw_tags=[], artifacts=[],
+        smtp_targets=[], observations=None,
+    )
+    ta = _get_ta(bundle)
+    ext = ta.extensions[ACTOR_FINGERPRINT_EXT_ID]
+    fp = ext.protocol_fingerprints
+    assert fp["ja3_hashes"] == ["abc123def456"]
+    assert fp["hassh_hashes"] == ["hashhash01"]
+    assert fp["tls_cert_sha256"] == ["a" * 64]
+    c2 = fp["c2_endpoints"]
+    assert isinstance(c2, list) and c2[0]["host"] == "bad.example.com"
+
+
+def test_no_legacy_flat_x_decnet_hash_properties():
+    """Dropped: x_decnet_ja3_hashes / x_decnet_hassh_hashes / x_decnet_c2_endpoints."""
+    bundle = build_attacker_bundle(
+        attacker=_attacker(),
+        behavior=_behavior(), identity=_identity(), intel=None,
+        technique_rollup=[], raw_tags=[], artifacts=[],
+        smtp_targets=[], observations=None,
+    )
+    ta = _get_ta(bundle)
+    for old_prop in ("x_decnet_ja3_hashes", "x_decnet_hassh_hashes", "x_decnet_c2_endpoints"):
+        assert not hasattr(ta, old_prop), f"legacy property {old_prop!r} should not exist"
+
+
+def test_observations_produce_behave_profile_sdo():
+    bundle = build_attacker_bundle(
+        attacker=_attacker(),
+        behavior=None, identity=None, intel=None,
+        technique_rollup=[], raw_tags=[], artifacts=[],
+        smtp_targets=[], observations=_obs(),
+    )
+    ta = _get_ta(bundle)
+    assert hasattr(ta, "x_decnet_behave_profile_ref")
+    profile_sdos = [o for o in bundle.objects if o.type == "x-decnet-behave-profile"]
+    assert len(profile_sdos) == 1
+    profile = profile_sdos[0]
+    assert profile.id == ta.x_decnet_behave_profile_ref
+    assert len(profile.observations) == 2
+    assert profile.observations[0]["primitive"] == "motor.input_modality"
+    assert profile.observations[0]["confidence"] == pytest.approx(0.9)
+    assert profile.observations[0]["window"]["start_ts"] == pytest.approx(1000.0)
+
+
+def test_observations_include_extension_def_sdo():
+    bundle = build_attacker_bundle(
+        attacker=_attacker(),
+        behavior=None, identity=None, intel=None,
+        technique_rollup=[], raw_tags=[], artifacts=[],
+        smtp_targets=[], observations=_obs(),
+    )
+    ext_defs = [o for o in bundle.objects if o.type == "extension-definition"]
+    assert len(ext_defs) == 1
+    assert ext_defs[0].id == ACTOR_FINGERPRINT_EXT_ID
+
+
+def test_kd_digraph_simhash_bytes_input():
+    ident = _identity()
+    ident["kd_digraph_simhash"] = b"\xde\xad\xbe\xef\x12\x34\x56\x78"
+    bundle = build_attacker_bundle(
+        attacker=_attacker(),
+        behavior=None, identity=ident, intel=None,
+        technique_rollup=[], raw_tags=[], artifacts=[],
+        smtp_targets=[], observations=[_obs()[0]],
+    )
+    profile = next(o for o in bundle.objects if o.type == "x-decnet-behave-profile")
+    assert profile.kd_digraph_simhash == "deadbeef12345678"
+
+
+def test_kd_digraph_simhash_base64_input():
+    raw = b"\xca\xfe\xba\xbe\x00\x00\x00\x00"
+    ident = _identity()
+    ident["kd_digraph_simhash"] = base64.b64encode(raw).decode()
+    bundle = build_attacker_bundle(
+        attacker=_attacker(),
+        behavior=None, identity=ident, intel=None,
+        technique_rollup=[], raw_tags=[], artifacts=[],
+        smtp_targets=[], observations=[_obs()[0]],
+    )
+    profile = next(o for o in bundle.objects if o.type == "x-decnet-behave-profile")
+    assert profile.kd_digraph_simhash == raw.hex()
+
+
+def test_inter_decnet_round_trip():
+    """Primary fidelity: stix2.parse restores typed objects, not bare dicts."""
+    ident = _identity()
+    ident["kd_digraph_simhash"] = b"\xde\xad\xbe\xef\x12\x34\x56\x78"
+    bundle = build_attacker_bundle(
+        attacker=_attacker(),
+        behavior=_behavior(), identity=ident, intel=None,
+        technique_rollup=[], raw_tags=[], artifacts=[],
+        smtp_targets=[], observations=_obs(),
+    )
+    parsed = stix2.parse(bundle.serialize(pretty=True, indent=2), allow_custom=True)
+
+    parsed_ta = next(o for o in parsed.objects if o.type == "threat-actor")
+    assert ACTOR_FINGERPRINT_EXT_ID in parsed_ta.extensions
+    parsed_ext = parsed_ta.extensions[ACTOR_FINGERPRINT_EXT_ID]
+    assert type(parsed_ext).__name__ == "DecnetActorFingerprintExt"
+    assert parsed_ext.network_behavior["os_guess"] == "Linux 4.x"
+    assert parsed_ext.protocol_fingerprints["ja3_hashes"] == ["abc123def456"]
+
+    parsed_profile = next(o for o in parsed.objects if o.type == "x-decnet-behave-profile")
+    assert type(parsed_profile).__name__ == "XDecnetBehaveProfile"
+    assert parsed_profile.kd_digraph_simhash == "deadbeef12345678"
+    primitives = {obs["primitive"] for obs in parsed_profile.observations}
+    assert "motor.input_modality" in primitives
+    assert "cognitive.exploration_style" in primitives
diff --git a/tests/web/test_api_export_attacker_misp.py b/tests/web/test_api_export_attacker_misp.py
index 505c0a97..21f7dc8a 100644
--- a/tests/web/test_api_export_attacker_misp.py
+++ b/tests/web/test_api_export_attacker_misp.py
@@ -112,6 +112,7 @@ def _mock_repo(*, attacker=None, intel=None, rollup=None, tags=None,
     m.get_attacker_artifacts = AsyncMock(return_value=artifacts or [])
     m.list_smtp_targets = AsyncMock(return_value=smtp or [])
     m.list_attacker_commands_deduped = AsyncMock(return_value=commands or [])
+    m.list_observations_by_attacker = AsyncMock(return_value=[])
     return m
 
 
diff --git a/tests/web/test_api_export_attacker_stix.py b/tests/web/test_api_export_attacker_stix.py
index 7c8124ae..5763fc81 100644
--- a/tests/web/test_api_export_attacker_stix.py
+++ b/tests/web/test_api_export_attacker_stix.py
@@ -128,6 +128,7 @@ def _mock_repo(*, attacker=None, identity=None, intel=None,
     m.get_attacker_artifacts = AsyncMock(return_value=artifacts or [])
     m.list_smtp_targets = AsyncMock(return_value=smtp or [])
     m.list_attacker_commands_deduped = AsyncMock(return_value=commands or [])
+    m.list_observations_by_attacker = AsyncMock(return_value=[])
     return m
 
 
diff --git a/tests/web/test_api_export_attackers_misp.py b/tests/web/test_api_export_attackers_misp.py
index 1061845a..6a16dc77 100644
--- a/tests/web/test_api_export_attackers_misp.py
+++ b/tests/web/test_api_export_attackers_misp.py
@@ -51,6 +51,7 @@ def _mock_repo(*, rows=None, ttp_by_attacker=None):
     m = type("M", (), {})()
     m.get_all_attackers_for_export = AsyncMock(return_value=rows or [])
     m.get_all_ttp_rollups_for_export = AsyncMock(return_value=ttp_by_attacker or {})
+    m.get_all_observations_for_export = AsyncMock(return_value={})
     return m
 
 
diff --git a/tests/web/test_api_export_attackers_stix.py b/tests/web/test_api_export_attackers_stix.py
index d3befee9..7e708a07 100644
--- a/tests/web/test_api_export_attackers_stix.py
+++ b/tests/web/test_api_export_attackers_stix.py
@@ -52,6 +52,7 @@ def _mock_repo(*, rows=None, ttp_by_attacker=None):
     m = type("M", (), {})()
     m.get_all_attackers_for_export = AsyncMock(return_value=rows or [])
     m.get_all_ttp_rollups_for_export = AsyncMock(return_value=ttp_by_attacker or {})
+    m.get_all_observations_for_export = AsyncMock(return_value={})
     return m