diff --git a/apps/backend/app/insights/relationship_diagnostics.py b/apps/backend/app/insights/relationship_diagnostics.py
index 8e1a1a9..38e1804 100644
--- a/apps/backend/app/insights/relationship_diagnostics.py
+++ b/apps/backend/app/insights/relationship_diagnostics.py
@@ -205,6 +205,10 @@ def load_unresolved_relationship_context(db: Session, snapshot_id: str) -> Unres
                 RiObservation.observed_kind == "import_binding",
             )
         ).all():
+            # The inner join already excludes a null observation_ref; this
+            # narrows the nullable column type SQLAlchemy 2.1 now reports.
+            if observation_ref is None:
+                continue
             referent = binding_referent_by_pk.get(observation_ref)
             if referent is None or not path:
                 continue
diff --git a/apps/backend/pyproject.toml b/apps/backend/pyproject.toml
index 52312c6..97fd122 100644
--- a/apps/backend/pyproject.toml
+++ b/apps/backend/pyproject.toml
@@ -39,7 +39,7 @@ test = [
 ]
 dev = [
   "mypy==2.3.1",
-  "ruff==0.16.8",
+  "ruff==0.16.9",
 ]
 
 [tool.setuptools.packages.find]
diff --git a/apps/backend/requirements-dev.txt b/apps/backend/requirements-dev.txt
index 6b09ff0..7b069cb 100644
--- a/apps/backend/requirements-dev.txt
+++ b/apps/backend/requirements-dev.txt
@@ -4,13 +4,13 @@
 # only requirements.txt; pytest must never ship in runtime dependencies (issue #185).
 -r requirements.txt
 ast-serialize==0.11.2
-coverage==7.16.1
+coverage==7.16.2
 iniconfig==2.3.0
-librt==0.15.0
+librt==0.16.0
 mypy==2.3.1
 mypy_extensions==1.1.0
 pathspec==1.1.1
 pluggy==1.6.0
 pytest==9.1.1
 pytest-cov==7.1.0
-ruff==0.16.8
+ruff==0.16.9
diff --git a/apps/backend/requirements.txt b/apps/backend/requirements.txt
index 3b03272..71ba91a 100644
--- a/apps/backend/requirements.txt
+++ b/apps/backend/requirements.txt
@@ -22,7 +22,7 @@ cryptography==50.0.1
 cssselect2==0.10.1
 dnspython==2.8.0
 email-validator==2.3.0
-fastapi==0.141.1
+fastapi==0.142.0
 greenlet==3.5.6
 h11==0.16.0
 html5lib==1.1
@@ -45,7 +45,7 @@ pydantic_core==2.46.5
 Pygments==2.21.0
 pyhanko-certvalidator==0.32.1
 pyHanko==0.37.0
-PyJWT==2.14.0
+PyJWT==2.15.1
 pypdf==6.19.0
 python-bidi==0.6.11
 python-dotenv==1.2.3
@@ -55,8 +55,8 @@ redis==8.1.0
 reportlab==4.5.1
 requests==2.34.2
 six==1.17.0
-SQLAlchemy==2.0.54
-starlette==1.6.0
+SQLAlchemy==2.1.1
+starlette==1.7.0
 svglib==2.2.0
 tinycss2==1.5.1
 tree-sitter==0.26.0
@@ -67,8 +67,8 @@ tzdata==2026.4
 tzlocal==5.4.4
 uritools==6.1.3
 urllib3==2.8.0
-uvicorn==0.53.0
+uvicorn==0.54.0
 watchfiles==1.3.0
 webencodings==0.6.1
 websockets==17.1
-xhtml2pdf==0.2.20
+xhtml2pdf==0.2.21