diff --git a/experiments/perception/worker/observatory_portable/migrate_claim_transport_v3.py b/experiments/perception/worker/observatory_portable/migrate_claim_transport_v3.py
index a6066fd..9c1deaf 100644
--- a/experiments/perception/worker/observatory_portable/migrate_claim_transport_v3.py
+++ b/experiments/perception/worker/observatory_portable/migrate_claim_transport_v3.py
@@ -29,8 +29,8 @@ TARGETS = {
     "ndc-observatory-installed-lab-worker-agent": INSTALLED_PARENT_SHA,
     "ndc-observatory-m49-worker-agent": M49_PARENT_SHA,
 }
-SOURCE = "/opt/nodedc/mission-core/src/k1link/observatory/worker_http_transport.py"
-BEFORE_SHA = "fb67ae174c8da66f7d04022310be663b2735fff72966883aaa5b50fdbc3e89c7"
+SOURCE = "/opt/nodedc/installed-lab/src/k1link/observatory/worker_http_transport.py"
+BEFORE_SHA = "c3d82ffd482a29b17c68d1fb5603e82924766abc0080137d3a0a6130f92ccdce"
 OLD = b"missioncore.observatory-worker-claim-request/v2"
 NEW = b"missioncore.observatory-worker-claim-request/v3"
 PARENT_LABEL = "com.nodedc.claim-transport-parent.sha256"
@@ -115,6 +115,12 @@ with httpx.Client(base_url=os.environ["MISSIONCORE_OBSERVATORY_WORKER_BASE_URL"]
     print(json.dumps(response.json()))
 """
 
+IMPORTED_SOURCE = """import hashlib, json, pathlib
+from k1link.observatory import worker_http_transport as transport
+path = pathlib.Path(transport.__file__).resolve()
+print(json.dumps({"path": str(path), "sha256": hashlib.sha256(path.read_bytes()).hexdigest()}))
+"""
+
 PROBE = """import json, os, pathlib, uuid
 from k1link.observatory.worker_http_transport import ObservatoryWorkerHttpGateway
 with ObservatoryWorkerHttpGateway(
@@ -169,6 +175,9 @@ def plan(engine: Engine) -> dict:
     for name, parent in TARGETS.items():
         inspection = engine.inspect(name)
         validate_target(name, inspection)
+        imported = engine.execute_json(name, IMPORTED_SOURCE)
+        if imported != {"path": SOURCE, "sha256": BEFORE_SHA}:
+            raise ValueError("loaded transport differs from the reviewed immutable source")
         readiness = engine.execute_json(name, READINESS)
         require_idle(readiness)
         targets.append(
@@ -176,6 +185,7 @@ def plan(engine: Engine) -> dict:
                 "name": name,
                 "container_id": inspection["Id"],
                 "parent_image_sha256": parent,
+                "imported_source": imported,
                 "create_body_sha256": sha(
                     canonical(
                         {
@@ -348,6 +358,10 @@ def apply(engine: Engine, expected_plan_sha: str, evidence: Path) -> dict:
         after = engine.inspect(name)
         if not after["State"]["Running"] or after["RestartCount"] != 0:
             raise RuntimeError("replacement agent needs reconciliation; predecessor retained")
+        if engine.execute_json(name, IMPORTED_SOURCE) != {
+            "path": SOURCE, "sha256": image["source_sha256"],
+        }:
+            raise RuntimeError("replacement agent did not load the pinned transport module")
         before_probe = engine.execute_json(name, READINESS)
         require_idle(before_probe)
         probe = engine.execute_json(name, PROBE)
diff --git a/tests/test_observatory_claim_transport_migration.py b/tests/test_observatory_claim_transport_migration.py
index ce18a3e..3a6fbe4 100644
--- a/tests/test_observatory_claim_transport_migration.py
+++ b/tests/test_observatory_claim_transport_migration.py
@@ -81,6 +81,8 @@ def test_evidence_is_immutable_and_control_probe_cannot_claim_models(tmp_path: P
     assert "range(8)" in migration.PROBE
     compile(migration.PROBE, "control-probe", "exec")
     compile(migration.READINESS, "readiness", "exec")
+    compile(migration.IMPORTED_SOURCE, "imported-source", "exec")
+    assert "transport.__file__" in migration.IMPORTED_SOURCE
 
 
 def test_transport_clone_retains_executor_configuration_and_rollback_snapshot() -> None: