diff --git a/.gitea/workflows/check.yml b/.gitea/workflows/check.yml
index 106e102..e5dcffb 100644
--- a/.gitea/workflows/check.yml
+++ b/.gitea/workflows/check.yml
@@ -71,7 +71,7 @@ jobs:
           PYSLACK
       - name: Fetch pinned headless HTTP integration client
         env:
-          HEADLESS_CLIENT_REVISION: a626e6c3006765ae5569b40cf7d48b7f263a722a
+          HEADLESS_CLIENT_REVISION: 902e30a65b07a97304ffc41fbbc7a9d1a91d08fd
         run: |
           set -eu
           mkdir -p .headless-client
diff --git a/internal/platform/integration_test.go b/internal/platform/integration_test.go
index f27adb4..42a9535 100644
--- a/internal/platform/integration_test.go
+++ b/internal/platform/integration_test.go
@@ -706,6 +706,62 @@ func TestOnboardingAndSharing(t *testing.T) {
 		t.Fatalf("stable URL lost child asset binding: %v count=%d", err, managedBindings)
 	}
 	call("POST", assetCanvasPath+"/subgraphs/asset-frame/dissolve", tokens[0], response{"expected_versions": map[string]int64{assetBoard["id"].(string): 5, assetChild: 2}}, 200, "", accept, "40000000-0000-4000-8000-000000000003")
+	// A warm metadata/original cache is not a future permission grant. An external
+	// collaborator can read through a source board grant, but a new canonical
+	// target write must recheck asset readability after that grant is revoked.
+	sourceGrantPath := workspacePath + "/materials/" + assetBoard["id"].(string) + "/grants"
+	call("POST", sourceGrantPath, tokens[0], response{"account_id": accounts[2], "role": "viewer"}, 204)
+	call("GET", metadataPath, tokens[2], nil, 200)
+	download(tokens[2], 200)
+	targetBoard := call("POST", workspacePath+"/materials", tokens[0], response{"kind": "board", "title": "Asset adoption target", "content": response{}}, 201)
+	targetID := targetBoard["id"].(string)
+	targetPath := workspacePath + "/materials/" + targetID
+	targetGrantPath := targetPath + "/grants"
+	call("POST", targetGrantPath, tokens[0], response{"account_id": accounts[2], "role": "editor"}, 204)
+	migrationID := modelTestID(9200)
+	call("POST", targetPath+"/canvas/model/migrate", tokens[0], response{"protocol_version": 2, "request_id": migrationID, "expected_versions": map[string]int64{targetID: 1}}, 200, "", accept, migrationID)
+	targetModel := call("GET", targetPath+"/canvas/model", tokens[2], nil, 200)["model"].(map[string]any)
+	targetVersion := int64(targetModel["versions"].(map[string]any)[targetID].(float64))
+	adoptedElement := modelTestNode(modelTestID(9201), targetID)
+	adoptedElement["componentId"] = "image"
+	adoptedElement["data"] = map[string]any{"title": "Adopted", "text": "", "assetId": uploaded["id"], "src": uploaded["url"]}
+	adoptionRequest := func(requestID, operationID string) modelBatch {
+		return modelBatch{ProtocolVersion: 2, RequestID: requestID, Expected: map[string]int64{targetID: targetVersion}, Operations: []modelOperation{{ID: operationID, Changes: []modelChange{{Kind: "element", ID: modelString(adoptedElement["id"]), Before: modelJSON(nil), After: modelJSON(adoptedElement)}}}}}
+	}
+	call("DELETE", sourceGrantPath+"/"+accounts[2], tokens[0], nil, 204)
+	call("GET", metadataPath, tokens[2], nil, 404)
+	download(tokens[2], 404)
+	deniedID := modelTestID(9202)
+	deniedBody := adoptionRequest(deniedID, modelTestID(9203))
+	denied := call("POST", targetPath+"/canvas/model/operations", tokens[2], deniedBody, 400, "", accept, deniedID)
+	if denied["status"] != "not-applied" || denied["terminal"] != true || denied["error"] != "invalid_asset_reference" {
+		t.Fatalf("revoked source did not yield a definitive no-write receipt: %v", denied)
+	}
+	unchanged := call("GET", targetPath+"/canvas/model", tokens[2], nil, 200)["model"].(map[string]any)
+	if !modelEqual(unchanged, targetModel) {
+		t.Fatal("revoked-source adoption changed target model or versions")
+	}
+	var targetBindings int
+	if err := db.QueryRowContext(ctx, "SELECT count(*) FROM canvas_asset_bindings WHERE project=$1 AND asset_id=$2 AND board_id=$3", project, uploaded["id"], targetID).Scan(&targetBindings); err != nil || targetBindings != 0 {
+		t.Fatalf("rejected adoption left a target binding: %d %v", targetBindings, err)
+	}
+	// Restoring source access does not change the frozen rejected request's result.
+	call("POST", sourceGrantPath, tokens[0], response{"account_id": accounts[2], "role": "viewer"}, 204)
+	call("GET", metadataPath, tokens[2], nil, 200)
+	replayedDenial := call("POST", targetPath+"/canvas/model/operations", tokens[2], deniedBody, 400, "", accept, deniedID)
+	if !modelEqual(denied, replayedDenial) {
+		t.Fatal("permission restoration changed a terminal receipt")
+	}
+	acceptedID := modelTestID(9204)
+	call("POST", targetPath+"/canvas/model/operations", tokens[2], adoptionRequest(acceptedID, modelTestID(9205)), 200, "", accept, acceptedID)
+	call("DELETE", sourceGrantPath+"/"+accounts[2], tokens[0], nil, 204)
+	// The independently authorized target now owns a binding; source revocation
+	// must not revoke a resource still readable through that target.
+	call("GET", metadataPath, tokens[2], nil, 200)
+	download(tokens[2], 200)
+	call("DELETE", targetGrantPath+"/"+accounts[2], tokens[0], nil, 204)
+	call("GET", metadataPath, tokens[2], nil, 404)
+	download(tokens[2], 404)
 	download(tokens[1], 200)
 	upload([]byte("not an image"), "aaaaaaaa-aaaa-4aaa-8aaa-aaaaaaaaaaaa", 400)