From 01f6eb2a7a5b2525e7e8c8a5ffa439a1234d5a4d Mon Sep 17 00:00:00 2001
From: Miguel de Benito Delgado <m.debenito.d@gmail.com>
Date: Sun, 20 Sep 2026 16:47:47 +0200
Subject: [PATCH] :construction: WIP Step 2, common scene code, validation

---
 .clj-kondo/config.edn                         |   2 +-
 frontend/package.json                         |   4 +-
 .../benches/render_wasm/scenes/common.cljs    | 198 +++++++++++
 .../frontend_tests/benches/fixture_test.cljs  | 317 ++++++++++++++++++
 frontend/test/frontend_tests/runner.cljs      |   1 +
 5 files changed, 519 insertions(+), 3 deletions(-)
 create mode 100644 frontend/test/benches/render_wasm/scenes/common.cljs
 create mode 100644 frontend/test/frontend_tests/benches/fixture_test.cljs

diff --git a/.clj-kondo/config.edn b/.clj-kondo/config.edn
index cb83ee6565..ed58d74207 100644
--- a/.clj-kondo/config.edn
+++ b/.clj-kondo/config.edn
@@ -36,7 +36,7 @@
    "^(?:backend|frontend|exporter|common)/deps.edn"
    "^(?:backend|frontend|exporter|common)/scripts/"
    "^(?:backend|frontend|exporter|common)/dev/"
-   "^(?:backend|frontend|exporter|common)/test/(?!benches/)"]
+   "^(?:backend|frontend|exporter|common)/test/(?!benches/|frontend_tests/benches/)"]
 
   :linter-name true}
 
diff --git a/frontend/package.json b/frontend/package.json
index e76fa6e62c..9ecc807111 100644
--- a/frontend/package.json
+++ b/frontend/package.json
@@ -37,9 +37,9 @@
     "fmt:clj": "cljfmt fix --parallel=true src/ test/",
     "fmt:js": "prettier -c src/**/*.stories.jsx -c playwright/**/*.js -c scripts/**/*.js -c text-editor/**/*.js -w",
     "fmt:scss": "prettier -c resources/styles -c src/**/*.scss -w",
-    "lint:clj": "clj-kondo --fail-level error --config-dir ../.clj-kondo --lint ../common/src src/ test/benches/",
+    "lint:clj": "clj-kondo --fail-level error --config-dir ../.clj-kondo --lint ../common/src src/ test/benches/  test/frontend_tests/benches/",
     "lint:js": "exit 0",
-    "lint:renderer-benchmarks": "clj-kondo --config-dir ../.clj-kondo --lint test/benches/",
+    "lint:renderer-benchmarks": "clj-kondo --config-dir ../.clj-kondo --lint test/benches/ test/frontend_tests/benches/",
     "lint:scss": "pnpm exec stylelint '{src,resources}/**/*.scss'",
     "build:test": "pnpm run build:wasm && clojure -M:dev:shadow-cljs compile test",
     "test": "pnpm run build:test && node target/tests/test.js",
diff --git a/frontend/test/benches/render_wasm/scenes/common.cljs b/frontend/test/benches/render_wasm/scenes/common.cljs
new file mode 100644
index 0000000000..9250f36864
--- /dev/null
+++ b/frontend/test/benches/render_wasm/scenes/common.cljs
@@ -0,0 +1,198 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) KALEIDOS SUBSIDIARY SL
+
+(ns benches.render-wasm.scenes.common
+  "Utilities shared by generated and saved-page fixtures.
+
+  A fixture instance is
+  `{:objects {uuid shape ...} :refs {label uuid ...}}`.
+
+      - `:objects` is a Penpot page object map.
+      - `:refs` is an instance-local lookup from custom labels to object uuids.
+
+  A fixture instance is just static data (a 'snapshot'). It is independent of
+  camera, operations, WASM buffers and renderer calls, and it never mutates after
+  upload.
+
+  Validation uses penpot's facilities, so that benchmark fixtures follow editor
+  semantics. We do check reachability from the root here because neither the
+  editor validator nor file loading guarantees it.
+
+  Authoring and scoped construction are ticket17; containers ticket18/19;
+  case declarations ticket20; saved-page loading ticket21.
+
+  Which shape types may own children is container semantics owned by
+  ticket18/19; this contract only checks hierarchy consistency."
+  (:require
+   [app.common.files.helpers :as cfh]
+   [app.common.files.validate :as cfv]
+   [app.common.geom.shapes.tree-seq :as gts]
+   [app.common.schema :as sm]
+   [app.common.types.page :as ctp]
+   [app.common.uuid :as uuid]))
+
+(def schema:instance
+  "Envelope schema for a fixture snapshot."
+  [:map {:title "RendererBenchmarkFixture"}
+   [:objects ctp/schema:objects]
+   [:refs [:map-of :any ::sm/uuid]]])
+
+(defn- fail!
+  [hint data]
+  (throw (ex-info (str "Invalid fixture instance: " hint)
+                  (merge {:type ::invalid-fixture
+                          :hint hint}
+                         data))))
+
+(defn- check-schema!
+  [instance]
+  (when-not (sm/validate schema:instance instance)
+    (fail! "instance does not match the fixture schema"
+           {::sm/explain (sm/explain schema:instance instance)})))
+
+(defn- check-root!
+  [instance]
+  (let [root (get-in instance [:objects uuid/zero])]
+    (when-not (and (some? root) (cfh/root? root))
+      (fail! "root object must be a frame at uuid/zero"
+             {:id uuid/zero}))
+    (when-not (= uuid/zero (:parent-id root))
+      (fail! "root object :parent-id must be uuid/zero"
+             {:id uuid/zero
+              :parent-id (:parent-id root)}))
+    (when-not (= uuid/zero (:frame-id root))
+      (fail! "root object :frame-id must be uuid/zero"
+             {:id uuid/zero
+              :frame-id (:frame-id root)}))))
+
+(defn- check-object-ids!
+  [objects]
+  (doseq [[id shape] objects]
+    (when-not (= id (:id shape))
+      (fail! "object key does not match the shape :id"
+             {:key id
+              :shape-id (:id shape)}))))
+
+(defn- check-child-links!
+  "Guard the reachability walk against malformed child links.
+
+  `:shapes` must be a vector when present, and every listed child that
+  exists must point back at the listing shape. This keeps each child with a
+  single parent, so the descendant walk visits a forest instead of fanning
+  out over shared children or looping on a cycle. Production validation
+  repeats these checks for reachable shapes; this one only protects our own
+  traversal order."
+  [objects]
+  (doseq [[id shape] objects
+          :let [children (:shapes shape)]]
+    (when (some? children)
+      (when-not (vector? children)
+        (fail! "shape :shapes must be a vector"
+               {:id id}))
+      (doseq [child-id children
+              :let [child (get objects child-id)]
+              :when (some? child)]
+        (when-not (= id (:parent-id child))
+          (fail! "shape :shapes lists a child with a different :parent-id"
+                 {:id id
+                  :child child-id}))))))
+
+(defn- check-reachability!
+  "Check the root graph through the cycle-safe descendant walk.
+
+  Runs `check-child-links!` first, which keeps the walk linear: one parent
+  per child and vector `:shapes` mean the walk cannot fan out over shared
+  children or loop on a cycle.
+
+  Detects missing child ids, objects reachable more than once (shared
+  children or cycles), detached subtrees and a root listed as its own
+  descendant. Runs before the production validator, whose walk follows
+  `:shapes` links and would loop on a reachable cycle."
+  [objects]
+  (check-child-links! objects)
+  (let [ids  (cfh/get-children-ids objects uuid/zero)
+        seen (set ids)]
+
+    (when (contains? seen uuid/zero)
+      (fail! "root must not be a descendant of itself"
+             {:id uuid/zero}))
+
+    (doseq [id ids]
+      (when-not (contains? objects id)
+        (fail! "shape :shapes references a missing object"
+               {:child id})))
+
+    (when-let [dup (first (for [[id n] (frequencies ids) :when (> n 1)] id))]
+      (fail! "an object is reachable more than once"
+             {:id dup}))
+
+    (doseq [id (keys objects)
+            :when (not= id uuid/zero)]
+      (when-not (contains? seen id)
+        (fail! "object is not reachable from the root"
+               {:id id})))))
+
+(defn- check-referential-integrity!
+  "Run the production referential validation over the reachable graph.
+
+  `cfv/validate-shape` checks parent/child links, frame ids and geometry
+  with editor semantics. The file and page only carry the uuids the
+  validation error schema requires; fixtures contain no component shapes.
+  Unreachable objects never reach this walk; `check-reachability!` owns
+  them."
+  [instance]
+  (let [file   {:id uuid/zero :data {}}
+        page   {:id uuid/zero :objects (:objects instance)}
+        errors (cfv/validate-shape uuid/zero file page {})]
+    (when-let [{:keys [hint] :as error} (first errors)]
+      (fail! hint (select-keys error [:code :shape-id :args])))))
+
+(defn- check-refs!
+  [instance]
+  (let [objects (:objects instance)]
+    (doseq [[label target] (:refs instance)]
+      (when-not (contains? objects target)
+        (fail! "ref target is not present in :objects"
+               {:label label
+                :target target})))))
+
+(defn validate!
+  "Validates a fixture instance and returns it unchanged.
+
+  Throws `ex-info` with `{:type ::invalid-fixture :hint ...}` when the
+  snapshot is invalid. Schema failures also carry `::sm/explain`.
+
+  Reachability runs before the production validator, because that walk
+  follows `:shapes` links and would not terminate on a reachable cycle.
+
+  Explicit `throw`s are used instead of assertions so the checks survive
+  elided assertions."
+  [instance]
+  (check-schema! instance)
+  (let [objects (:objects instance)]
+    (check-root! instance)
+    (check-object-ids! objects)
+    (check-reachability! objects)
+    (check-referential-integrity! instance)
+    (check-refs! instance))
+  instance)
+
+(defn upload-order
+  "Returns the instance objects as a vector in parent-before-child order.
+
+  The root comes first and each shape's `:shapes` order is followed, using
+  the shared tree traversal. That traversal reverses children of flex
+  containers marked reverse; upload order carries no renderer semantics
+  because a shape's child list is uploaded from its own `:shapes` vector.
+
+  Assumes a validated instance: every child id exists."
+  [instance]
+  (vec (gts/get-children-seq uuid/zero (:objects instance))))
+
+(defn ref-id
+  "Resolves an author label to the referenced object uuid, or nil."
+  [instance label]
+  (get-in instance [:refs label]))
diff --git a/frontend/test/frontend_tests/benches/fixture_test.cljs b/frontend/test/frontend_tests/benches/fixture_test.cljs
new file mode 100644
index 0000000000..6050e02831
--- /dev/null
+++ b/frontend/test/frontend_tests/benches/fixture_test.cljs
@@ -0,0 +1,317 @@
+;; This Source Code Form is subject to the terms of the Mozilla Public
+;; License, v. 2.0. If a copy of the MPL was not distributed with this
+;; file, You can obtain one at http://mozilla.org/MPL/2.0/.
+;;
+;; Copyright (c) KALEIDOS SUBSIDIARY SL
+
+(ns frontend-tests.benches.fixture-test
+  (:require
+   [app.common.schema :as sm]
+   [app.common.types.shape :as cts]
+   [app.common.uuid :as uuid]
+   [benches.render-wasm.scenes.common :as fixture]
+   [cljs.test :as t :include-macros true]))
+
+(defn- sample-instance
+  "Simple tiny fixture: root frame with one rectangle."
+  []
+  (let [rect-id (uuid/custom 1 1)
+        rect    (cts/setup-shape {:id rect-id :type :rect :name "Rect"
+                                  :x 32 :y 48 :width 200 :height 120})
+        root    (cts/setup-shape {:id uuid/zero :type :frame :name "Root Frame"
+                                  :x 0 :y 0 :width 1920 :height 1080
+                                  :shapes [rect-id]})]
+    {:objects {uuid/zero root, rect-id rect}
+     :refs    {:rect rect-id}}))
+
+(defn- nested-instance
+  "Root with two frames; frame A with two rectangles, frame B with one."
+  []
+  (let [a-id    (uuid/custom 2 1)
+        b-id    (uuid/custom 2 2)
+        a1-id   (uuid/custom 2 3)
+        a2-id   (uuid/custom 2 4)
+        b1-id   (uuid/custom 2 5)
+        frame-a (cts/setup-shape {:id a-id :type :frame :name "A"
+                                  :x 0 :y 0 :width 100 :height 100
+                                  :parent-id uuid/zero :frame-id uuid/zero
+                                  :shapes [a1-id a2-id]})
+        frame-b (cts/setup-shape {:id b-id :type :frame :name "B"
+                                  :x 200 :y 0 :width 100 :height 100
+                                  :parent-id uuid/zero :frame-id uuid/zero
+                                  :shapes [b1-id]})
+        rect-a1 (cts/setup-shape {:id a1-id :type :rect :name "A1"
+                                  :x 10 :y 10 :width 10 :height 10
+                                  :parent-id a-id :frame-id a-id})
+        rect-a2 (cts/setup-shape {:id a2-id :type :rect :name "A2"
+                                  :x 30 :y 10 :width 10 :height 10
+                                  :parent-id a-id :frame-id a-id})
+        rect-b1 (cts/setup-shape {:id b1-id :type :rect :name "B1"
+                                  :x 210 :y 10 :width 10 :height 10
+                                  :parent-id b-id :frame-id b-id})
+        root    (cts/setup-shape {:id uuid/zero :type :frame :name "Root Frame"
+                                  :x 0 :y 0 :width 1920 :height 1080
+                                  :parent-id uuid/zero :frame-id uuid/zero
+                                  :shapes [a-id b-id]})]
+    {:objects {uuid/zero root
+               a-id frame-a
+               b-id frame-b
+               a1-id rect-a1
+               a2-id rect-a2
+               b1-id rect-b1}
+     :refs    {:a a-id
+               :a1 a1-id
+               :b b-id}}))
+
+(defn- validation-error
+  "Returns the ex-data of the validation failure, or nil when it passes."
+  [instance]
+  (try
+    (fixture/validate! instance)
+    nil
+    (catch :default cause
+      (ex-data cause))))
+
+(t/deftest canonical-example-is-valid
+  (t/testing "validate! returns the same instance"
+    (let [instance (sample-instance)]
+      (t/is (identical? instance (fixture/validate! instance)))))
+
+  (t/testing "the envelope schema accepts the example"
+    (t/is (true? (sm/validate fixture/schema:instance (sample-instance))))))
+
+(t/deftest nested-hierarchy-is-valid
+  (let [instance (nested-instance)]
+    (t/is (identical? instance (fixture/validate! instance)))))
+
+(t/deftest root-only-instance-is-valid
+  (let [root     (cts/setup-shape {:id uuid/zero :type :frame :name "Root Frame"
+                                   :x 0 :y 0 :width 100 :height 100
+                                   :parent-id uuid/zero :frame-id uuid/zero
+                                   :shapes []})
+        instance {:objects {uuid/zero root} :refs {}}]
+    (t/is (identical? instance (fixture/validate! instance)))
+    (t/is (= [uuid/zero] (mapv :id (fixture/upload-order instance))))))
+
+(t/deftest upload-order-starts-at-root
+  (let [instance (sample-instance)
+        ids      (mapv :id (fixture/upload-order instance))]
+    (t/is (= uuid/zero (first ids)))
+    (t/is (= [uuid/zero (fixture/ref-id instance :rect)] ids))))
+
+(t/deftest upload-order-is-parent-before-child
+  (let [instance (nested-instance)
+        order    (fixture/upload-order instance)
+        names    (mapv :name order)
+        position (into {} (map-indexed (fn [index shape] [(:id shape) index]) order))]
+    (t/is (= ["Root Frame" "A" "A1" "A2" "B" "B1"] names))
+    (t/is (every? (fn [shape]
+                    (or (= uuid/zero (:id shape))
+                        (< (position (:parent-id shape))
+                           (position (:id shape)))))
+                  order))))
+
+(t/deftest upload-order-follows-flex-reverse
+  (let [frame-id (uuid/custom 8 1)
+        a-id     (uuid/custom 8 2)
+        b-id     (uuid/custom 8 3)
+        frame    (cts/setup-shape {:id frame-id :type :frame :name "Flex"
+                                   :x 0 :y 0 :width 200 :height 100
+                                   :parent-id uuid/zero :frame-id uuid/zero
+                                   :layout :flex :layout-flex-dir :row-reverse
+                                   :shapes [a-id b-id]})
+        shape-a  (cts/setup-shape {:id a-id :type :rect :name "A"
+                                   :x 0 :y 0 :width 10 :height 10
+                                   :parent-id frame-id :frame-id frame-id})
+        shape-b  (cts/setup-shape {:id b-id :type :rect :name "B"
+                                   :x 20 :y 0 :width 10 :height 10
+                                   :parent-id frame-id :frame-id frame-id})
+        root     (cts/setup-shape {:id uuid/zero :type :frame :name "Root Frame"
+                                   :x 0 :y 0 :width 1920 :height 1080
+                                   :parent-id uuid/zero :frame-id uuid/zero
+                                   :shapes [frame-id]})
+        instance {:objects {uuid/zero root
+                            frame-id frame
+                            a-id shape-a
+                            b-id shape-b}
+                  :refs {}}]
+    (t/is (identical? instance (fixture/validate! instance)))
+    (t/is (= ["Root Frame" "Flex" "B" "A"]
+             (mapv :name (fixture/upload-order instance))))))
+
+(t/deftest ref-id-resolves-labels
+  (let [instance (sample-instance)]
+    (t/is (= (uuid/custom 1 1) (fixture/ref-id instance :rect)))
+    (t/is (nil? (fixture/ref-id instance :missing)))))
+
+(t/deftest missing-root-is-rejected
+  (let [instance (sample-instance)
+        data     (validation-error (update instance :objects dissoc uuid/zero))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= uuid/zero (:id data)))))
+
+(t/deftest non-frame-root-is-rejected
+  (let [instance (sample-instance)
+        data     (validation-error (assoc-in instance [:objects uuid/zero :type] :rect))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= uuid/zero (:id data)))))
+
+(t/deftest root-with-non-zero-parent-id-is-rejected
+  (let [instance (sample-instance)
+        data     (validation-error
+                  (assoc-in instance [:objects uuid/zero :parent-id] (uuid/custom 9 9)))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= uuid/zero (:id data)))))
+
+(t/deftest object-key-must-match-shape-id
+  (let [instance (sample-instance)
+        rect     (get-in instance [:objects (fixture/ref-id instance :rect)])
+        data     (validation-error (assoc-in instance [:objects (uuid/custom 7 7)] rect))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= (:id rect) (:shape-id data)))))
+
+(t/deftest missing-child-is-rejected
+  (let [instance (sample-instance)
+        bogus    (uuid/custom 3 3)
+        data     (validation-error
+                  (assoc-in instance [:objects uuid/zero :shapes] [bogus]))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= bogus (:child data)))))
+
+(t/deftest child-not-listed-by-parent-is-rejected
+  (let [instance (sample-instance)
+        rect-id  (fixture/ref-id instance :rect)
+        data     (validation-error (assoc-in instance [:objects uuid/zero :shapes] []))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= "object is not reachable from the root" (:hint data)))
+    (t/is (= rect-id (:id data)))))
+
+(t/deftest mismatched-parent-id-is-rejected
+  (let [instance (sample-instance)
+        rect-id  (fixture/ref-id instance :rect)
+        data     (validation-error
+                  (assoc-in instance [:objects rect-id :parent-id] (uuid/custom 9 7)))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= "shape :shapes lists a child with a different :parent-id" (:hint data)))
+    (t/is (= rect-id (:child data)))))
+
+(t/deftest duplicate-child-ids-are-rejected
+  (let [instance (sample-instance)
+        rect-id  (fixture/ref-id instance :rect)
+        data     (validation-error
+                  (assoc-in instance [:objects uuid/zero :shapes] [rect-id rect-id]))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= "an object is reachable more than once" (:hint data)))
+    (t/is (= rect-id (:id data)))))
+
+(t/deftest shape-listing-itself-is-rejected
+  (let [instance (sample-instance)
+        data     (validation-error
+                  (assoc-in instance [:objects uuid/zero :shapes] [uuid/zero]))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= "root must not be a descendant of itself" (:hint data)))
+    (t/is (= uuid/zero (:id data)))))
+
+(t/deftest detached-cycle-is-rejected
+  (let [c1-id  (uuid/custom 5 1)
+        c2-id  (uuid/custom 5 2)
+        shape1 (cts/setup-shape {:id c1-id :type :rect :name "C1"
+                                 :x 0 :y 0 :width 10 :height 10
+                                 :parent-id c2-id :frame-id c1-id
+                                 :shapes [c2-id]})
+        shape2 (cts/setup-shape {:id c2-id :type :rect :name "C2"
+                                 :x 0 :y 0 :width 10 :height 10
+                                 :parent-id c1-id :frame-id c2-id
+                                 :shapes [c1-id]})
+        data   (validation-error
+                (assoc (sample-instance) :objects
+                       (assoc (get (sample-instance) :objects)
+                              c1-id shape1
+                              c2-id shape2)))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= "object is not reachable from the root" (:hint data)))
+    (t/is (contains? #{c1-id c2-id} (:id data)))))
+
+(t/deftest reachable-cycle-is-rejected
+  (let [a-id     (uuid/custom 4 1)
+        b-id     (uuid/custom 4 2)
+        shape-a  (cts/setup-shape {:id a-id :type :rect :name "A"
+                                   :x 0 :y 0 :width 10 :height 10
+                                   :parent-id uuid/zero :frame-id uuid/zero
+                                   :shapes [b-id]})
+        shape-b  (cts/setup-shape {:id b-id :type :rect :name "B"
+                                   :x 0 :y 0 :width 10 :height 10
+                                   :parent-id a-id :frame-id uuid/zero
+                                   :shapes [a-id]})
+        instance (-> (sample-instance)
+                     (assoc-in [:objects uuid/zero :shapes] [a-id])
+                     (assoc-in [:objects a-id] shape-a)
+                     (assoc-in [:objects b-id] shape-b))
+        data     (validation-error instance)]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= "shape :shapes lists a child with a different :parent-id" (:hint data)))
+    (t/is (= a-id (:child data)))))
+
+(t/deftest non-vector-children-are-rejected
+  (let [instance (sample-instance)
+        rect-id  (fixture/ref-id instance :rect)
+        data     (validation-error (assoc-in instance [:objects rect-id :shapes] 5))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= "shape :shapes must be a vector" (:hint data)))
+    (t/is (= rect-id (:id data)))))
+
+(t/deftest frame-id-mismatch-is-rejected
+  (let [instance (nested-instance)
+        a1-id    (fixture/ref-id instance :a1)
+        data     (validation-error
+                  (assoc-in instance [:objects a1-id :frame-id] uuid/zero))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= :invalid-frame (:code data)))
+    (t/is (= a1-id (:shape-id data)))))
+
+(t/deftest missing-ref-target-is-rejected
+  (let [instance (sample-instance)
+        data     (validation-error
+                  (assoc-in instance [:refs :rect] (uuid/custom 6 6)))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (= :rect (:label data)))))
+
+(t/deftest non-uuid-ref-value-is-rejected
+  (let [data (validation-error (assoc-in (sample-instance) [:refs :rect] "not-a-uuid"))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (some? (::sm/explain data)))))
+
+(t/deftest missing-refs-key-is-rejected
+  (let [data (validation-error (dissoc (sample-instance) :refs))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (some? (::sm/explain data)))))
+
+(t/deftest non-canonical-shape-is-rejected
+  (let [instance (sample-instance)
+        rect-id  (fixture/ref-id instance :rect)
+        data     (validation-error (assoc-in instance [:objects rect-id] {:id rect-id}))]
+    (t/is (= ::fixture/invalid-fixture (:type data)))
+    (t/is (some? (::sm/explain data)))))
+
+(t/deftest malformed-envelopes-are-rejected
+  (t/testing "empty objects map"
+    (let [data (validation-error {:objects {} :refs {}})]
+      (t/is (= ::fixture/invalid-fixture (:type data)))
+      (t/is (= uuid/zero (:id data)))))
+
+  (t/testing "nil instance"
+    (let [data (validation-error nil)]
+      (t/is (= ::fixture/invalid-fixture (:type data)))
+      (t/is (some? (::sm/explain data)))))
+
+  (t/testing "nil shape value"
+    (let [instance (sample-instance)
+          rect-id  (fixture/ref-id instance :rect)
+          data     (validation-error (assoc-in instance [:objects rect-id] nil))]
+      (t/is (= ::fixture/invalid-fixture (:type data)))
+      (t/is (some? (::sm/explain data)))))
+
+  (t/testing "nil ref value"
+    (let [data (validation-error (assoc-in (sample-instance) [:refs :rect] nil))]
+      (t/is (= ::fixture/invalid-fixture (:type data)))
+      (t/is (some? (::sm/explain data))))))
diff --git a/frontend/test/frontend_tests/runner.cljs b/frontend/test/frontend_tests/runner.cljs
index bdc9193088..27b0a842f6 100644
--- a/frontend/test/frontend_tests/runner.cljs
+++ b/frontend/test/frontend_tests/runner.cljs
@@ -175,6 +175,7 @@
 
 (def test-namespaces
   ['frontend-tests.basic-shapes-test
+   'frontend-tests.benches.fixture-test
    'frontend-tests.code-gen-style-test
    'frontend-tests.composable-tests.comp.sync-test
    'frontend-tests.copy-as-svg-test