diff --git a/.changeset/ten-gorillas-boil.md b/.changeset/ten-gorillas-boil.md
new file mode 100644
index 000000000..fcecdfa83
--- /dev/null
+++ b/.changeset/ten-gorillas-boil.md
@@ -0,0 +1,6 @@
+---
+"@apollo/composition": patch
+"@apollo/query-graphs": patch
+---
+
+Fix bug in composition where, when a field's type in a subgraph is a subtype of the field's type in the supergraph, the satisfiability validation spuriously succeeds/errors.
diff --git a/composition-js/src/validate.ts b/composition-js/src/validate.ts
index a813647ef..b1c552558 100644
--- a/composition-js/src/validate.ts
+++ b/composition-js/src/validate.ts
@@ -641,6 +641,7 @@ export class ValidationState {
     for (const pathInfo of this.subgraphPathInfos) {
       const tailSubgraphName = pathInfo.path.path.tail.source;
       const tailSubgraphEnumValue = subgraphNameToGraphEnumValue.get(tailSubgraphName);
+      const tailTypeName = pathInfo.path.path.tail.type.name;
       const entryKeys = [];
       const contexts = Array.from(pathInfo.contexts.entries());
       contexts.sort((a, b) => a[0].localeCompare(b[0]));
@@ -649,7 +650,7 @@ export class ValidationState {
         entryKeys.push(`${context}=${subgraphEnumValue}.${typeName}`);
       }
       subgraphContextKeys.add(
-        `${tailSubgraphEnumValue}[${entryKeys.join(',')}]`
+        `${tailSubgraphEnumValue}.${tailTypeName}[${entryKeys.join(',')}]`
       );
     }
     return subgraphContextKeys;
diff --git a/query-graphs-js/src/graphPath.ts b/query-graphs-js/src/graphPath.ts
index ba87dc723..e32dbb656 100644
--- a/query-graphs-js/src/graphPath.ts
+++ b/query-graphs-js/src/graphPath.ts
@@ -1735,6 +1735,15 @@ function advancePathWithDirectTransition<V extends Vertex>(
     // We can now continue on dealing with the actual field.
   }
 
+  if (
+    transition.kind === 'DownCast'
+    && transition.castedType.name === path.tail.type.name
+  ) {
+    // Due to output type covariance, a downcast supergraph transition may be a no-op on the
+    // subgraph path. In these cases, we effectively ignore the type condition.
+    return [path];
+  }
+
   const options: GraphPath<Transition, V>[] = [];
   const deadEndClosures: UnadvanceableClosure[] = [];