diff --git a/tests/matlab_tests/test_core.py b/tests/matlab_tests/test_core.py
index 33a1bf37..011eca1b 100644
--- a/tests/matlab_tests/test_core.py
+++ b/tests/matlab_tests/test_core.py
@@ -224,6 +224,14 @@ def test_query_integration(self, tmp_path):
                 "demoNDI.value": 2,
             },
         )
+        # demoNDI declares filename1.ext in its file_list; a document that
+        # declares a required file and binds nothing is refused at add time
+        # (VH-Lab/DID-python#86).
+        for doc, name in ((doc1, "alpha"), (doc2, "beta")):
+            payload = session_dir / f"{name}.dat"
+            payload.write_text(name)
+            doc.add_file("filename1.ext", str(payload))
+
         session.database_add(doc1)
         session.database_add(doc2)
 
diff --git a/tests/matlab_tests/test_database.py b/tests/matlab_tests/test_database.py
index 21c6bb11..be8ecab0 100644
--- a/tests/matlab_tests/test_database.py
+++ b/tests/matlab_tests/test_database.py
@@ -204,6 +204,13 @@ def test_document_round_trip(self, tmp_path):
         )
         original_id = doc.id
 
+        # demoNDI declares filename1.ext in its file_list; a document that
+        # declares a required file and binds nothing is refused at add time
+        # (VH-Lab/DID-python#86).
+        payload = session_dir / "persistent_doc.dat"
+        payload.write_text("persistent_doc")
+        doc = doc.add_file("filename1.ext", str(payload))
+
         # Save
         session.database_add(doc)
 
diff --git a/tests/matlab_tests/test_fun.py b/tests/matlab_tests/test_fun.py
index 922f8c60..78fdb536 100644
--- a/tests/matlab_tests/test_fun.py
+++ b/tests/matlab_tests/test_fun.py
@@ -47,6 +47,24 @@ def _make_demo_doc(name: str = "test", value: int = 42, session_id: str = "") ->
     return ndi_document(props)
 
 
+def _make_demo_doc_with_file(
+    directory, name: str, value: int, session_id: str = ""
+) -> ndi_document:
+    """A demoNDI document with its declared file bound.
+
+    demoNDI declares ``filename1.ext`` in its ``file_list``, and a document
+    that declares a required file and binds nothing is refused at add time
+    (VH-Lab/DID-python#86). Mirrors ``conftest._add_doc_with_file``, except
+    that the source file is kept: several of these tests add a copy of the
+    same properties to a SECOND database, which needs the location to still
+    resolve after the first ingest.
+    """
+    doc = _make_demo_doc(name, value, session_id)
+    payload = directory / f"{name}.dat"
+    payload.write_text(name)
+    return doc.add_file("filename1.ext", str(payload), delete_original=0)
+
+
 def _make_session_with_docs(tmp_path, ref, doc_specs):
     """Create a ndi_session_dir and add documents from a list of (name, value) tuples.
 
@@ -163,7 +181,7 @@ def test_findFuid_not_found(self, tmp_path):
         session = ndi_session_dir("fuid_test2", session_dir)
 
         # Add a document (so the database is not empty)
-        doc = _make_demo_doc("some_doc", 99, session.id())
+        doc = _make_demo_doc_with_file(session_dir, "some_doc", 99, session.id())
         session.database_add(doc)
 
         found_doc, found_name = findFuid(session, "nonexistent_uid_12345")
@@ -353,7 +371,7 @@ def test_identical_sessions(self, tmp_path):
         session = ndi_session_dir("identical", session_dir)
 
         for i in range(1, 4):
-            doc = _make_demo_doc(f"doc_{i}", i, session.id())
+            doc = _make_demo_doc_with_file(session_dir, f"doc_{i}", i, session.id())
             session.database_add(doc)
 
         # Reopen same session (same path -> same data)
@@ -383,7 +401,7 @@ def test_docs_only_in_s1(self, tmp_path):
 
         # Add 3 docs to session1, 0 to session2
         for i in range(1, 4):
-            doc = _make_demo_doc(f"doc_{i}", i, session1.id())
+            doc = _make_demo_doc_with_file(s1_dir, f"doc_{i}", i, session1.id())
             session1.database_add(doc)
 
         result = session_diff(session1, session2)
@@ -410,7 +428,7 @@ def test_docs_only_in_s2(self, tmp_path):
 
         # Add 2 docs to session2, 0 to session1
         for i in range(1, 3):
-            doc = _make_demo_doc(f"doc_{i}", i, session2.id())
+            doc = _make_demo_doc_with_file(s2_dir, f"doc_{i}", i, session2.id())
             session2.database_add(doc)
 
         result = session_diff(session1, session2)
@@ -436,7 +454,7 @@ def test_mismatched_docs(self, tmp_path):
         session2 = ndi_session_dir("sess_b", s2_dir)
 
         # Create a document with a known ID
-        doc = _make_demo_doc("shared_doc", 10, session1.id())
+        doc = _make_demo_doc_with_file(s1_dir, "shared_doc", 10, session1.id())
         doc_id = doc.document_properties["base"]["id"]
         session1.database_add(doc)
 
@@ -474,7 +492,7 @@ def test_identical_datasets(self, tmp_path):
         sess_dir.mkdir()
         session = ndi_session_dir("src", sess_dir)
         for i in range(1, 3):
-            doc = _make_demo_doc(f"doc_{i}", i, session.id())
+            doc = _make_demo_doc_with_file(sess_dir, f"doc_{i}", i, session.id())
             session.database_add(doc)
 
         # Create dataset and ingest
@@ -502,7 +520,7 @@ def test_docs_only_in_dataset1(self, tmp_path):
         sess1_dir.mkdir()
         session1 = ndi_session_dir("sess1", sess1_dir)
         for i in range(1, 4):
-            doc = _make_demo_doc(f"doc_{i}", i, session1.id())
+            doc = _make_demo_doc_with_file(sess1_dir, f"doc_{i}", i, session1.id())
             session1.database_add(doc)
 
         ds1_dir = tmp_path / "ds1"
@@ -536,7 +554,7 @@ def test_docs_only_in_dataset2(self, tmp_path):
         sess2_dir.mkdir()
         session2 = ndi_session_dir("sess2", sess2_dir)
         for i in range(1, 4):
-            doc = _make_demo_doc(f"doc_{i}", i, session2.id())
+            doc = _make_demo_doc_with_file(sess2_dir, f"doc_{i}", i, session2.id())
             session2.database_add(doc)
 
         ds2_dir = tmp_path / "ds2"
@@ -555,7 +573,7 @@ def test_mismatched_datasets(self, tmp_path):
         MATLAB equivalent: diffTest.testMismatchedDocs
         """
         # Create a document
-        doc = _make_demo_doc("shared", 10)
+        doc = _make_demo_doc_with_file(tmp_path, "shared", 10)
         doc.document_properties["base"]["id"]
 
         # ndi_dataset 1
diff --git a/tests/matlab_tests/test_session.py b/tests/matlab_tests/test_session.py
index c4bde6c0..76a9b59b 100644
--- a/tests/matlab_tests/test_session.py
+++ b/tests/matlab_tests/test_session.py
@@ -124,6 +124,14 @@ def test_ingested_session_in_dataset(self, tmp_path):
         props["demoNDI"]["value"] = 42
         props["base"]["session_id"] = session.id()
         doc = ndi_document(props)
+
+        # demoNDI declares filename1.ext in its file_list; a document that
+        # declares a required file and binds nothing is refused at add time
+        # (VH-Lab/DID-python#86). Mirrors conftest._add_doc_with_file.
+        payload = session_dir / "test_doc.dat"
+        payload.write_text("test_doc")
+        doc = doc.add_file("filename1.ext", str(payload))
+
         session.database_add(doc)
 
         # Create dataset and ingest
diff --git a/tests/matlab_tests/test_validators.py b/tests/matlab_tests/test_validators.py
index cd858d24..8ad30110 100644
--- a/tests/matlab_tests/test_validators.py
+++ b/tests/matlab_tests/test_validators.py
@@ -23,6 +23,21 @@
 from ndi.session.dir import ndi_session_dir
 from ndi.session.session_base import empty_id
 
+
+def _with_its_declared_file(doc, directory):
+    """Bind demoNDI's declared ``filename1.ext``.
+
+    demoNDI declares that file in its ``file_list``, and a document that
+    declares a required file and binds nothing is refused at add time
+    (VH-Lab/DID-python#86). These tests are about session_id handling, so
+    the file's content is incidental -- it just has to be there for the add
+    to reach the behaviour under test.
+    """
+    payload = directory / f"{doc.id}.ext"
+    payload.write_text(doc.id)
+    return doc.add_file("filename1.ext", str(payload))
+
+
 # ===========================================================================
 # TestDocumentValidation
 # Port of: MATLAB validator tests - document-level validation
@@ -87,7 +102,7 @@ def test_session_id_empty_accepted(self, tmp_path):
         props = doc.document_properties
         props["base"]["session_id"] = ""
         props["demoNDI"]["value"] = 99
-        doc = ndi_document(props)
+        doc = _with_its_declared_file(ndi_document(props), session_dir)
 
         # Should not raise -- empty session_id is accepted and auto-assigned
         session.database_add(doc)
@@ -105,7 +120,7 @@ def test_session_id_empty_id_accepted(self, tmp_path):
         props = doc.document_properties
         props["base"]["session_id"] = empty_id()
         props["demoNDI"]["value"] = 88
-        doc = ndi_document(props)
+        doc = _with_its_declared_file(ndi_document(props), session_dir)
 
         # Should not raise -- empty_id is accepted and auto-assigned
         session.database_add(doc)
diff --git a/tests/test_did_integration.py b/tests/test_did_integration.py
index e4fc1100..e840d0dc 100644
--- a/tests/test_did_integration.py
+++ b/tests/test_did_integration.py
@@ -252,6 +252,44 @@ def _bundled_document_types():
         yield rel_posix.removesuffix(".json"), path
 
 
+def _bind_the_files_it_declares(props):
+    """Give a blank template a binding for every file name it declares.
+
+    A definition is a TEMPLATE: it names the files a stored document must
+    carry and binds none of them, because the document that binds them is
+    the one that gets stored.  Since VH-Lab/DID-python#86 the validator says
+    so -- ``DID:Database:ValidationFiles``, "declared in the file_list ...
+    but no file is bound to that name" -- and says it FIRST, ahead of the
+    field checks, so seven definitions started reporting that instead of
+    whatever is actually wrong with them.
+
+    That is the right answer about a document and the wrong question here.
+    This gate asks about the DEFINITION's structure, and asks it of a blank
+    one; an unbound file is a property of the blank, exactly as an unfilled
+    dependency is (see ``_BLANK_TEMPLATE_IDENTIFIERS``).  So bind the
+    declared names first -- the same fix the fixtures elsewhere in this
+    suite took -- and let validation reach the questions the lists below
+    record.  Skipping the identifier instead would have hidden those: five
+    of the seven are listed for a field error that is still there.
+
+    A name ending in ``#`` is a file SERIES, matched by ``is_filename_match``
+    as the stem followed by digits, so it is bound under its first member's
+    name.  Locations are ``https://`` URLs because ``can_find_one_file`` does
+    no network I/O and does not pre-check a non-local location: nothing here
+    touches the filesystem.
+    """
+    file_list = [str(n) for n in (props.get("files") or {}).get("file_list") or []]
+    if not file_list:
+        return
+    props["files"]["file_info"] = [
+        {
+            "name": f"{name[:-1]}1" if name.endswith("#") else name,
+            "locations": [{"location": "https://example.invalid/placeholder"}],
+        }
+        for name in file_list
+    ]
+
+
 def _structural_failure(doc_type):
     """Validate a blank document of ``doc_type``; return an error id or None."""
     from did.validate import ValidationError, get_document_schema, validate_doc_vs_schema
@@ -261,6 +299,7 @@ def _structural_failure(doc_type):
     doc_id = props["base"]["id"]
     session_id = ndi_ido().id
     props["base"]["session_id"] = session_id
+    _bind_the_files_it_declares(props)
     try:
         schema = get_document_schema(props["document_class"]["validation"])
         with warnings.catch_warnings():
diff --git a/tests/test_extract_doc_files_series.py b/tests/test_extract_doc_files_series.py
index fa4535e8..5d16310a 100644
--- a/tests/test_extract_doc_files_series.py
+++ b/tests/test_extract_doc_files_series.py
@@ -161,9 +161,12 @@ def test_the_file_list_is_read_before_file_info_is_cleared(self, tmp_path):
 
     def test_a_document_with_no_files_is_left_alone(self, tmp_path):
         session = _session(tmp_path, "src_session")
-        props = ndi_document("demoNDI").document_properties
+        # A bare base document, not a demoNDI: demoNDI declares filename1.ext
+        # in its file_list, so one with nothing bound is refused at add time
+        # (VH-Lab/DID-python#86) rather than being the fileless document this
+        # test is about.
+        props = ndi_document("base").document_properties
         props["base"]["session_id"] = session.id()
-        props["demoNDI"]["value"] = 1
         session.database_add(ndi_document(props))
         out = tmp_path / "out"
 
diff --git a/tests/test_session_database_rm.py b/tests/test_session_database_rm.py
index e219e272..5792c5aa 100644
--- a/tests/test_session_database_rm.py
+++ b/tests/test_session_database_rm.py
@@ -39,6 +39,13 @@ def _a_document(session):
     doc = session.newdocument("data/generic_file")
     doc.document_properties["generic_file"]["dateCreated"] = 0
     doc.document_properties["generic_file"]["dateUpdated"] = 0
+    # data/generic_file declares generic_file.ext in its file_list, and a
+    # document that declares a required file and binds nothing is refused at
+    # add time (VH-Lab/DID-python#86). The file is incidental here -- these
+    # tests are about database_rm -- but it has to exist.
+    payload = session.path / f"{doc.id}.ext"
+    payload.write_text(doc.id)
+    doc = doc.add_file("generic_file.ext", str(payload))
     session.database_add(doc)
     return doc