diff --git a/frontend/test/benches/render_wasm/cases.cljs b/frontend/test/benches/render_wasm/cases.cljs
new file mode 100644
index 0000000000..6c15565911
--- /dev/null
+++ b/frontend/test/benches/render_wasm/cases.cljs
@@ -0,0 +1,135 @@
+;; 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.cases
+  "Case collection for the renderer benchmarks.
+
+  Loading this namespace registers the scene namespaces listed here. That
+  require list is the discovery manifest. Nothing here should import browser
+  or renderer code, so the Node runner and offline reports load scenes without
+  renderer side effects.
+
+  Usage:
+
+    (cases/collect-cases {:master-seed 42})
+    ;; =>
+    [{:id :rects/load
+      :scene :rects
+      :scene-version 1
+      :scene-description \"Seeded rectangles with translucent fills and centered strokes\"
+      :scene-seed 2602546180
+      :params {:count 1000 :width 1920 :height 1080 :min-size 20 :max-size 100}
+      :view {:scale 1 :x 0 :y 0}
+      :context :fresh
+      :completion :render-full
+      :batch-size 1
+      :preparation {:version 1}}
+     {:id :rects/pan ...}
+     {:id :rects/zoom ...}]"
+  (:require
+   [app.common.schema :as sm]
+   [benches.render-wasm.scenes.core :as core]
+   benches.render-wasm.scenes.rects
+   [clojure.string :as str]))
+
+(defn- check-master-seed!
+  "Collection requires an integer master seed in [0, 2^32)."
+  [seed]
+  (when-not (and (integer? seed) (<= 0 seed) (< seed 4294967296))
+    (throw (ex-info "case collection requires an integer master seed in [0, 2^32)"
+                    {:type ::invalid-master-seed
+                     :seed seed}))))
+
+(defn- as-invalid-case!
+  "Runs `thunk`, translating core case-validation failures into this
+  namespace's ::invalid-case so `collect-cases` has a single error
+  contract. Registry mechanics (::duplicate-*, ::unknown-scene) and scene
+  declarations (::invalid-scene) keep their own types."
+  [thunk]
+  (try
+    (thunk)
+    (catch :default cause
+      (let [data (ex-data cause)]
+        (if (contains? #{::core/invalid-case ::core/non-serializable-case} (:type data))
+          (throw (ex-info (ex-message cause)
+                          (assoc data :type ::invalid-case)
+                          cause))
+          (throw cause))))))
+
+(defn- check-params!
+  "Validates case params against the scene's closed schema."
+  [case-id scene-id schema params]
+  (when-not (sm/validate schema params)
+    (throw (ex-info (str "invalid params for case " case-id)
+                    {:type ::invalid-case
+                     :id case-id
+                     :scene scene-id
+                     ::sm/explain (sm/explain schema params)}))))
+
+(defn- validate-case!
+  "Validates a registered case entry against its scene: unknown scene,
+  case-namespace mismatch, declaration schema and closed params."
+  [{:keys [id scene params] :as registered} scene-by-id]
+  (let [entry (get scene-by-id scene)]
+    (when (nil? entry)
+      (throw (ex-info (str "case " id " names an unknown scene: " scene)
+                      {:type ::unknown-scene
+                       :id id
+                       :scene scene})))
+    (when-not (= (name scene) (namespace id))
+      (throw (ex-info (str "case id " id " is not namespaced by its scene: " scene)
+                      {:type ::invalid-case
+                       :id id
+                       :scene scene})))
+    (as-invalid-case! #(core/check-registered-case! registered))
+    (check-params! id scene (:params-schema entry) params)
+    registered))
+
+(defn- describe-case
+  "Projects a validated case to its collected descriptor: scene
+  version/description/seed attached, internal keys stripped, plain data
+  checked."
+  [master-seed registered scene-entry]
+  (let [projected (-> (core/project-case registered)
+                      (assoc :scene-version (:version scene-entry)
+                             :scene-description (:description scene-entry)
+                             :scene-seed (core/derive-seed master-seed
+                                                           (:scene registered)
+                                                           (:params registered))))]
+    (as-invalid-case! #(core/check-collected-case! projected))))
+
+(defn scene-ids
+  "Registered scene ids in declaration order."
+  []
+  (mapv :id (core/scenes)))
+
+(defn case-ids
+  "Registered case ids in declaration order."
+  []
+  (mapv :id (core/cases)))
+
+(defn collect-cases
+  "Selected benchmark cases as plain data.
+
+  Validates scenes, cases and parameters before any browser work. `:filter`
+  is a substring match on the case id; an empty selection throws ::no-cases."
+  [{:keys [master-seed] :as options}]
+  (check-master-seed! master-seed)
+  (let [pattern       (:filter options)
+        scene-by-id   (into {} (map (juxt :id identity)) (core/scenes))]
+    (doseq [scene (core/scenes)]
+      (core/check-registered-scene! scene))
+    (let [selected (->> (core/cases)
+                        (map #(validate-case! % scene-by-id))
+                        (filter (fn [registered]
+                                  (or (str/blank? pattern)
+                                      (str/includes? (str (:id registered)) pattern))))
+                        (mapv #(describe-case master-seed % (get scene-by-id (:scene %)))))]
+      (when (empty? selected)
+        (throw (ex-info "no benchmark cases match the selection"
+                        {:type ::no-cases
+                         :filter pattern})))
+      selected)))
diff --git a/frontend/test/benches/render_wasm/scenes/core.clj b/frontend/test/benches/render_wasm/scenes/core.clj
new file mode 100644
index 0000000000..9c56b41f16
--- /dev/null
+++ b/frontend/test/benches/render_wasm/scenes/core.clj
@@ -0,0 +1,39 @@
+;; 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.core
+  "Registration macros for renderer benchmark scenes and cases.
+
+  The macros expand to calls to `register-scene!`/`register-case!` in
+  `core.cljs`. Registration is done there so it can be inspected and tested.")
+
+(defmacro defscene
+  "Registers a scene and returns its id.
+
+   - `id` (keyword)
+   - `opts` (`schema:scene`):  maps `:version`, `:description` and
+     `:params-schema`.
+   - `build` resolves to a one-argument function of the scene parameters."
+  [id opts build]
+  `(benches.render-wasm.scenes.core/register-scene!
+    (assoc ~opts :id ~id :ns ~(str *ns*) :build ~build)))
+
+(defmacro defcase
+  "Registers a case for `scene` and returns its id.
+
+  The optional body is the function run by the browser for the case. It sees
+  the injected runtime as `rtx`. Case collection strips the body before
+  handing descriptors to the runner."
+  [id scene opts & body]
+  (if (seq body)
+    `(benches.render-wasm.scenes.core/register-case!
+      (assoc ~opts
+             :id ~id
+             :scene ~scene
+             :ns ~(str *ns*)
+             :run! (fn [~'rtx] ~@body)))
+    `(benches.render-wasm.scenes.core/register-case!
+      (assoc ~opts :id ~id :scene ~scene :ns ~(str *ns*)))))
diff --git a/frontend/test/benches/render_wasm/scenes/core.cljs b/frontend/test/benches/render_wasm/scenes/core.cljs
new file mode 100644
index 0000000000..39918a83c4
--- /dev/null
+++ b/frontend/test/benches/render_wasm/scenes/core.cljs
@@ -0,0 +1,327 @@
+;; 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.core
+  "Registry and contract for renderer benchmark scenes and cases.
+
+  Scene namespaces register themselves at load time through the `defscene`
+  and `defcase` macros in `core.clj`. We don't import browser or renderer
+  code here.
+
+  - A scene declares an id, a version, a human description, a closed
+    parameters schema and a one-argument build function.
+  - A case declares an id namespaced by its scene, the scene, base parameters,
+    a view, a context policy, a completion mode and an optional operation
+    identity and run function.
+
+  Collection validates every declaration, derives each scene seed and
+  returns plain data"
+  (:require
+   [app.common.schema :as sm]
+   [clojure.string :as str]))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Schemas
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(def schema:view
+  [:map {:closed true}
+   [:scale [:and number? pos?]]
+   [:x number?]
+   [:y number?]])
+
+(def schema:scene
+  [:map {:closed true}
+   [:id simple-keyword?]
+   [:ns string?]
+   [:version [:int {:min 1}]]
+   [:description string?]
+   [:params-schema vector?]
+   [:build fn?]])
+
+(def schema:registered-case
+  [:map {:closed true}
+   [:id qualified-keyword?]
+   [:scene simple-keyword?]
+   [:ns string?]
+   [:params [:map]]
+   [:view schema:view]
+   [:context [:enum :fresh :reuse]]
+   [:completion {:optional true} [:enum :call :await :render-full]]
+   [:batch-size {:optional true} [:int {:min 1}]]
+   [:operation {:optional true} [:map]]
+   [:preparation {:optional true} [:map]]
+   [:run! {:optional true} fn?]])
+
+(def schema:collected-case
+  [:map {:closed true}
+   [:id qualified-keyword?]
+   [:scene simple-keyword?]
+   [:scene-version [:int {:min 1}]]
+   [:scene-description string?]
+   [:scene-seed [:int {:min 0 :max 4294967295}]]
+   [:params [:map]]
+   [:view schema:view]
+   [:context [:enum :fresh :reuse]]
+   [:completion [:enum :call :await :render-full]]
+   [:batch-size [:int {:min 1}]]
+   [:preparation [:map]]
+   [:operation {:optional true} [:map]]])
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Registry
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(defonce registry
+  (atom {:scenes {}
+         :scene-order []
+         :cases {}
+         :case-order []}))
+
+(defn register-scene!
+  "Adds `scene` to the registry. Re-registering the same id from the same
+  namespace replaces the entry, so that namespace reload work.
+  The same id from another namespace throws ::duplicate-scene."
+  [{:keys [id ns] :as scene}]
+  (let [existing (get-in @registry [:scenes id])]
+    (when (and (some? existing) (not= ns (:ns existing)))
+      (throw (ex-info (str "duplicate scene id: " id)
+                      {:type ::duplicate-scene
+                       :id id
+                       :ns ns
+                       :existing-ns (:ns existing)})))
+    (swap! registry
+           (fn [reg]
+             (if (contains? (:scenes reg) id)
+               (assoc-in reg [:scenes id] scene)
+               (-> reg
+                   (assoc-in [:scenes id] scene)
+                   (update :scene-order conj id))))))
+  id)
+
+(defn register-case!
+  "Adds `bench-case` to the registry with the same replace/reject semantics
+  as register-scene!."
+  [{:keys [id ns] :as bench-case}]
+  (let [existing (get-in @registry [:cases id])]
+    (when (and (some? existing) (not= ns (:ns existing)))
+      (throw (ex-info (str "duplicate case id: " id)
+                      {:type ::duplicate-case
+                       :id id
+                       :ns ns
+                       :existing-ns (:ns existing)})))
+    (swap! registry
+           (fn [reg]
+             (if (contains? (:cases reg) id)
+               (assoc-in reg [:cases id] bench-case)
+               (-> reg
+                   (assoc-in [:cases id] bench-case)
+                   (update :case-order conj id))))))
+  id)
+
+(defn unregister-scene!
+  "Removes a scene registration. Tests use it to clean up synthetic scenes."
+  [id]
+  (swap! registry
+         (fn [reg]
+           (-> reg
+               (update :scenes dissoc id)
+               (update :scene-order #(vec (remove #{id} %))))))
+  id)
+
+(defn unregister-case!
+  "Removes a case registration. Tests use it to clean up synthetic cases."
+  [id]
+  (swap! registry
+         (fn [reg]
+           (-> reg
+               (update :cases dissoc id)
+               (update :case-order #(vec (remove #{id} %))))))
+  id)
+
+(defn scenes
+  "Registered scenes in declaration order."
+  []
+  (mapv (:scenes @registry) (:scene-order @registry)))
+
+(defn cases
+  "Registered cases in declaration order."
+  []
+  (mapv (:cases @registry) (:case-order @registry)))
+
+(defn registered-scene
+  "Full registered entry for a scene id."
+  [id]
+  (get-in @registry [:scenes id]))
+
+(defn registered-case
+  "Full registered entry for a case id, including the browser-side run
+  function when the case declares one. The browser bridge resolves
+  executions through this namespace; the Node runner only reads collected
+  descriptors."
+  [id]
+  (get-in @registry [:cases id]))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Schema helpers
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(defn- check-params-schema!
+  "Parses the scene's params schema with Penpot's registry, so a malformed
+  schema fails here with a typed error instead of raw invalid-schema
+  halfway through collection."
+  [{:keys [id params-schema]}]
+  (try
+    (sm/schema params-schema)
+    (catch :default cause
+      (throw (ex-info (str "invalid params schema for scene " id)
+                      {:type ::invalid-scene
+                       :id id}
+                      cause)))))
+
+(defn check-registered-scene!
+  "Validates a scene declaration and returns it unchanged."
+  [scene]
+  (check-params-schema! scene)
+  (when-not (sm/validate schema:scene scene)
+    (throw (ex-info (str "invalid scene declaration: " (:id scene))
+                    {:type ::invalid-scene
+                     :id (:id scene)
+                     ::sm/explain (sm/explain schema:scene scene)})))
+  scene)
+
+(defn check-registered-case!
+  "Validates a registered case declaration and returns it unchanged."
+  [bench-case]
+  (when-not (sm/validate schema:registered-case bench-case)
+    (throw (ex-info (str "invalid case declaration: " (:id bench-case))
+                    {:type ::invalid-case
+                     :id (:id bench-case)
+                     ::sm/explain (sm/explain schema:registered-case bench-case)})))
+  bench-case)
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Seed derivation
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(defn- check-param-keys!
+  "Rejects params keys that `canonical-params` cannot tell apart: only
+  simple keywords render distinctly by name."
+  [scene-id params]
+  (letfn [(check [value path]
+            (cond
+              (map? value)
+              (doseq [[k v] value]
+                (when-not (simple-keyword? k)
+                  (throw (ex-info (str "seed identity requires simple keyword keys at " path)
+                                  {:type ::invalid-params
+                                   :scene scene-id
+                                   :path path
+                                   :key k})))
+                (check v (str path "/" (name k))))
+
+              (vector? value)
+              (dorun (map-indexed (fn [index v] (check v (str path "[" index "]"))) value))))]
+    (check params "")))
+
+(defn- canonical-params
+  "Stable textual identity of a params map: keys render sorted by name,
+  vectors keep their order, nested values render the same way. Map key
+  order is an accident of construction, so sorting keeps the identity on
+  the parameters themselves: equal parameters give the same seed whatever
+  their literal order. Keys render by name, so params maps use simple
+  keyword keys; derive-seed rejects anything else."
+  [params]
+  (letfn [(render [value]
+            (cond
+              (map? value)
+              (str "{"
+                   (str/join ","
+                             (map (fn [[k v]] (str (name k) ":" (render v)))
+                                  (sort-by (comp name key) value)))
+                   "}")
+
+              (vector? value)
+              (str "[" (str/join "," (map render value)) "]")
+
+              :else
+              (pr-str value)))]
+    (render params)))
+
+(defn derive-seed
+  "FNV-1a 32-bit keyed hash of a case's parameter identity.
+
+  Fowler-Noll-Vo, 32-bit, offset basis 2166136261, prime 16777619, hashed
+  over `<master-seed>\\0<scene-id>/<canonical params>`. A keyed hash, not
+  the scene PRNG: the scene's mulberry32 generator is seeded with the
+  result, and a sequential draw cannot substitute because it would couple
+  cases through collection order. Keyed by scene and params only, so the
+  seed does not depend on case name, collection order, operation body,
+  attempts or A/B feature selection. Params maps use simple keyword keys;
+  namespaced keywords and string keys cannot be told apart by name and make
+  derive-seed throw ::invalid-params."
+  [master-seed scene-id params]
+  (check-param-keys! scene-id params)
+  (let [text (str master-seed "\u0000" (name scene-id) "/" (canonical-params params))]
+    (loop [index 0
+           seed  2166136261]
+      (if (< index (count text))
+        (recur (inc index)
+               (unsigned-bit-shift-right
+                (js/Math.imul (bit-xor seed (.charCodeAt text index)) 16777619)
+                0))
+        seed))))
+
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+;; Projection
+;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
+
+(defn serializable?
+  "True when `value` is plain data the runner can hand to the browser and
+  store in results: nil, booleans, numbers, strings, keywords, and maps and
+  vectors thereof. Records fail: a record reaches the runner as a host
+  object, not plain data. Functions, atoms and host objects fail."
+  [value]
+  (cond
+    (or (nil? value) (boolean? value) (number? value)
+        (string? value) (keyword? value))
+    true
+
+    (and (map? value) (not (record? value)))
+    (every? (fn [[k v]] (and (serializable? k) (serializable? v))) value)
+
+    (vector? value)
+    (every? serializable? value)
+
+    :else
+    false))
+
+(defn project-case
+  "Plain-data projection of a registered case: internal keys (`:ns`, `:run!`)
+  stripped, collection defaults applied."
+  [bench-case]
+  (-> bench-case
+      (select-keys [:id :scene :params :view :context :completion :batch-size
+                    :operation :preparation])
+      (update :completion #(or % :render-full))
+      (update :batch-size #(or % 1))
+      (update :preparation #(or % {:version 1}))))
+
+(defn check-collected-case!
+  "Validates a collected case descriptor and returns it unchanged. Rejects
+  anything that is not plain data: browser-side run functions must never
+  reach the runner."
+  [projected]
+  (when-not (sm/validate schema:collected-case projected)
+    (throw (ex-info (str "invalid collected case: " (:id projected))
+                    {:type ::invalid-case
+                     :id (:id projected)
+                     ::sm/explain (sm/explain schema:collected-case projected)})))
+  (when-not (serializable? projected)
+    (throw (ex-info (str "collected case is not plain data: " (:id projected))
+                    {:type ::non-serializable-case
+                     :id (:id projected)})))
+  projected)
diff --git a/frontend/test/benches/render_wasm/scenes/rects.cljs b/frontend/test/benches/render_wasm/scenes/rects.cljs
index 76494624f0..24a5ca4815 100644
--- a/frontend/test/benches/render_wasm/scenes/rects.cljs
+++ b/frontend/test/benches/render_wasm/scenes/rects.cljs
@@ -5,23 +5,46 @@
 ;; Copyright (c) KALEIDOS SUBSIDIARY SL
 
 (ns benches.render-wasm.scenes.rects
-  "Rectangle fixture, the smallest benchmark workload.
+  "Rectangle scene, the smallest benchmark workload.
 
   Distributes rectangles over the canvas with varied sizes, translucent
   fills and centered strokes, all drawn from the scope's seeded generator.
-  Ticket20 wraps `build` with case declarations; the path and effect
-  fixtures arrive in tickets07/08."
-  (:require
-   [benches.render-wasm.scenes.builder :as sb :include-macros true]))
+  `build` produces the fixture snapshot; `defscene` and `defcase` declare
+  the scene and its standard cases. The three cases share parameters, so
+  they render the same scene. The path and effect fixtures arrive in
+  tickets07/08.
 
-(def default-params
+  Operation bodies are deferred to tickets05/06. The intended threaded
+  shape is:
+
+    (defcase :rects/pan :rects {...}
+      (-> rtx
+          (restore! base-view)
+          (pan! {:frames 20 :distance [120 60] :settle-ms 100})
+          (drain! :full)))
+
+  where `rtx` is the injected runtime and each operation contributes its
+  plain-data identity to the collected case."
+  (:require
+   [benches.render-wasm.scenes.builder :as sb :include-macros true]
+   [benches.render-wasm.scenes.core :as core :include-macros true]))
+
+(def ^:private default-params
   {:count 1000
    :width 1920
    :height 1080
    :min-size 20
    :max-size 100})
 
-(defn rect-defaults
+(def ^:private schema:params
+  [:map {:closed true}
+   [:count [:int {:min 1 :max 100000}]]
+   [:width pos?]
+   [:height pos?]
+   [:min-size pos?]
+   [:max-size pos?]])
+
+(defn- rect-defaults
   "Attribute generators for one rectangle of the workload."
   [{:keys [width height min-size max-size]}]
   {:x       (sb/gen-int 0 width)
@@ -37,7 +60,7 @@
 
 (defn build
   "Builds the seeded rectangle fixture. `params` requires `:seed`; the other
-  keys default to `default-params`."
+  keys default to the standard case parameters."
   [params]
   (let [params (merge default-params params)]
     (sb/fixture {:seed (:seed params)
@@ -48,3 +71,29 @@
                  :defaults {:rect (rect-defaults params)}}
                 (doseq [_ (range (:count params))]
                   (sb/rect)))))
+
+(core/defscene :rects
+  {:version 1
+   :description "Seeded rectangles with translucent fills and centered strokes"
+   :params-schema schema:params}
+  build)
+
+(def ^:private base-view
+  {:scale 1 :x 0 :y 0})
+
+(core/defcase :rects/load :rects
+  {:params default-params
+   :view base-view
+   :context :fresh})
+
+(core/defcase :rects/pan :rects
+  {:params default-params
+   :view base-view
+   :context :reuse
+   :completion :render-full})
+
+(core/defcase :rects/zoom :rects
+  {:params default-params
+   :view base-view
+   :context :reuse
+   :completion :render-full})
diff --git a/frontend/test/frontend_tests/benches/builder_test.cljs b/frontend/test/frontend_tests/benches/builder_test.cljs
index 249f0505bd..9626026ec6 100644
--- a/frontend/test/frontend_tests/benches/builder_test.cljs
+++ b/frontend/test/frontend_tests/benches/builder_test.cljs
@@ -42,7 +42,6 @@
 (t/deftest rectangle-workload-keeps-default-count
   (let [instance (rects/build {:seed 42})
         rects    (rect-shapes instance)]
-    (t/is (= 1000 (:count rects/default-params)))
     (t/is (= 1000 (count rects)))
     (t/is (< 1 (count (distinct (map :x rects)))))))
 
diff --git a/frontend/test/frontend_tests/benches/contracts_test.cljs b/frontend/test/frontend_tests/benches/contracts_test.cljs
new file mode 100644
index 0000000000..e700c580d3
--- /dev/null
+++ b/frontend/test/frontend_tests/benches/contracts_test.cljs
@@ -0,0 +1,357 @@
+;; 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.contracts-test
+  (:require
+   [app.common.schema :as sm]
+   [benches.render-wasm.cases :as cases]
+   [benches.render-wasm.scenes.core :as core :include-macros true]
+   [cljs.test :as t :include-macros true]))
+
+(defrecord Point [x y])
+
+(core/defscene :contracts-scene
+  {:version 1
+   :description "Synthetic scene for contract tests"
+   :params-schema [:map {:closed true}]}
+  (fn [params] params))
+
+(core/defcase :contracts-scene/case
+  :contracts-scene
+  {:params {}
+   :view {:scale 1 :x 0 :y 0}
+   :context :fresh}
+  (throw (ex-info "run body must not execute during collection"
+                  {:type ::boom})))
+
+(defn- failure-data
+  [f]
+  (try
+    (f)
+    nil
+    (catch :default cause
+      (ex-data cause))))
+
+(defn- rect-cases
+  ([] (rect-cases 42 "rects/"))
+  ([master-seed filter]
+   (cases/collect-cases {:master-seed master-seed :filter filter})))
+
+(defn- with-synthetic-scene
+  "Registers a synthetic scene and case under `scene-id`, runs `f`, then
+  unregisters both so the live registry survives."
+  [scene-id case-params f]
+  (core/register-scene! {:id scene-id
+                         :ns "contracts-test"
+                         :version 1
+                         :description "synthetic"
+                         :params-schema [:map {:closed true} [:count [:int {:min 1 :max 100000}]]]
+                         :build (fn [params] params)})
+  (core/register-case! {:id (keyword (name scene-id) "case")
+                        :scene scene-id
+                        :ns "contracts-test"
+                        :params case-params
+                        :view {:scale 1 :x 0 :y 0}
+                        :context :fresh})
+  (try
+    (f)
+    (finally
+      (core/unregister-case! (keyword (name scene-id) "case"))
+      (core/unregister-scene! scene-id))))
+
+(t/deftest defscene-registers-metadata-and-build
+  (let [scene (core/registered-scene :rects)]
+    (t/is (= :rects (:id scene)))
+    (t/is (= "benches.render-wasm.scenes.rects" (:ns scene)))
+    (t/is (= 1 (:version scene)))
+    (t/is (= "Seeded rectangles with translucent fills and centered strokes"
+             (:description scene)))
+    (t/is (vector? (:params-schema scene)))
+    (t/is (fn? (:build scene)))))
+
+(t/deftest rects-cases-are-collected-in-declaration-order
+  (let [collected (rect-cases)]
+    (t/is (= [:rects/load :rects/pan :rects/zoom] (mapv :id collected)))))
+
+(t/deftest collected-cases-are-plain-data
+  (doseq [case-desc (rect-cases)]
+    (t/is (not (contains? case-desc :run!)) (str (:id case-desc)))
+    (t/is (not (contains? case-desc :ns)) (str (:id case-desc)))
+    (t/is (core/serializable? case-desc) (str (:id case-desc)))))
+
+(t/deftest rects-cases-carry-declared-view-context-and-completion
+  (let [collected (rect-cases)]
+    (t/is (= [[:rects/load :fresh] [:rects/pan :reuse] [:rects/zoom :reuse]]
+             (mapv (juxt :id :context) collected)))
+    (doseq [case-desc collected]
+      (t/is (= {:count 1000 :width 1920 :height 1080 :min-size 20 :max-size 100}
+               (:params case-desc))
+            (str (:id case-desc)))
+      (t/is (= {:scale 1 :x 0 :y 0} (:view case-desc)) (str (:id case-desc)))
+      (t/is (= :render-full (:completion case-desc)) (str (:id case-desc)))
+      (t/is (= 1 (:batch-size case-desc)) (str (:id case-desc)))
+      (t/is (= {:version 1} (:preparation case-desc)) (str (:id case-desc))))))
+
+(t/deftest rects-cases-carry-scene-metadata-and-seed
+  (let [collected (rect-cases)]
+    (doseq [case-desc collected]
+      (t/is (= :rects (:scene case-desc)))
+      (t/is (= 1 (:scene-version case-desc)))
+      (t/is (= "Seeded rectangles with translucent fills and centered strokes"
+               (:scene-description case-desc)))
+      (t/is (= 2602546180 (:scene-seed case-desc)) (str (:id case-desc)))))
+  (let [collected (rect-cases 43 "rects/")]
+    (t/is (every? #(= 2993218129 (:scene-seed %)) collected))))
+
+(t/deftest derive-seed-depends-on-scene-and-params-only
+  (let [params {:count 1000 :width 1920 :height 1080 :min-size 20 :max-size 100}
+        base   (core/derive-seed 42 :rects params)]
+    (t/is (= 2602546180 base))
+    (t/is (= base (core/derive-seed 42 :rects (into {} (reverse (seq params))))))
+    (t/is (= 2993218129 (core/derive-seed 43 :rects params)))
+    (t/is (not= base (core/derive-seed 42 :rects (assoc params :count 10))))
+    (t/is (not= base (core/derive-seed 42 :paths params)))))
+
+(t/deftest derive-seed-rejects-keys-it-cannot-tell-apart
+  (t/is (= ::core/invalid-params
+           (:type (failure-data #(core/derive-seed 42 :rects {"count" 1})))))
+  (t/is (= ::core/invalid-params
+           (:type (failure-data #(core/derive-seed 42 :rects {:rects/count 1})))))
+  (t/is (= :rects (:scene (failure-data #(core/derive-seed 42 :rects {"count" 1}))))))
+
+(t/deftest unknown-params-are-rejected
+  (with-synthetic-scene :contracts-unknown-params {:count 1 :bogus 2}
+    (fn []
+      (let [data (failure-data
+                  #(cases/collect-cases {:master-seed 42
+                                         :filter "contracts-unknown-params/"}))]
+        (t/is (= ::cases/invalid-case (:type data)))
+        (t/is (some? (::sm/explain data)))))))
+
+(t/deftest out-of-range-count-is-rejected
+  (with-synthetic-scene :contracts-bad-count {:count 0}
+    (fn []
+      (let [data (failure-data
+                  #(cases/collect-cases {:master-seed 42
+                                         :filter "contracts-bad-count/"}))]
+        (t/is (= ::cases/invalid-case (:type data)))
+        (t/is (some? (::sm/explain data)))))))
+
+(t/deftest duplicate-scene-id-from-another-namespace-is-rejected
+  (t/is (= ::core/duplicate-scene
+           (:type (failure-data
+                   #(core/register-scene! {:id :rects
+                                           :ns "another-namespace"
+                                           :version 1
+                                           :description "x"
+                                           :params-schema [:map]
+                                           :build (fn [params] params)}))))))
+
+(t/deftest same-namespace-registration-replaces
+  (try
+    (core/register-scene! {:id :contracts-replaced
+                           :ns "contracts-test"
+                           :version 1
+                           :description "first"
+                           :params-schema [:map]
+                           :build (fn [params] params)})
+    (core/register-scene! {:id :contracts-replaced
+                           :ns "contracts-test"
+                           :version 2
+                           :description "second"
+                           :params-schema [:map]
+                           :build (fn [params] params)})
+    (t/is (= "second" (:description (core/registered-scene :contracts-replaced))))
+    (finally
+      (core/unregister-scene! :contracts-replaced))))
+
+(t/deftest duplicate-case-id-from-another-namespace-is-rejected
+  (try
+    (core/register-scene! {:id :contracts-dup
+                           :ns "contracts-test"
+                           :version 1
+                           :description "x"
+                           :params-schema [:map]
+                           :build (fn [params] params)})
+    (core/register-case! {:id :contracts-dup/case
+                          :scene :contracts-dup
+                          :ns "contracts-test"
+                          :params {}
+                          :view {:scale 1 :x 0 :y 0}
+                          :context :fresh})
+    (t/is (= ::core/duplicate-case
+             (:type (failure-data
+                     #(core/register-case! {:id :contracts-dup/case
+                                            :scene :contracts-dup
+                                            :ns "another-namespace"
+                                            :params {}
+                                            :view {:scale 1 :x 0 :y 0}
+                                            :context :fresh})))))
+    (finally
+      (core/unregister-case! :contracts-dup/case)
+      (core/unregister-scene! :contracts-dup))))
+
+(t/deftest unknown-scene-reference-is-rejected
+  (try
+    (core/register-case! {:id :contracts-missing/case
+                          :scene :contracts-missing
+                          :ns "contracts-test"
+                          :params {}
+                          :view {:scale 1 :x 0 :y 0}
+                          :context :fresh})
+    (t/is (= ::cases/unknown-scene
+             (:type (failure-data
+                     #(cases/collect-cases {:master-seed 42
+                                            :filter "contracts-missing/"})))))
+    (finally
+      (core/unregister-case! :contracts-missing/case))))
+
+(t/deftest case-id-must-be-namespaced-by-its-scene
+  (try
+    (core/register-scene! {:id :contracts-other
+                           :ns "contracts-test"
+                           :version 1
+                           :description "x"
+                           :params-schema [:map]
+                           :build (fn [params] params)})
+    (core/register-case! {:id :contracts-other/case
+                          :scene :rects
+                          :ns "contracts-test"
+                          :params {}
+                          :view {:scale 1 :x 0 :y 0}
+                          :context :fresh})
+    (t/is (= ::cases/invalid-case
+             (:type (failure-data
+                     #(cases/collect-cases {:master-seed 42
+                                            :filter "contracts-other/"})))))
+    (finally
+      (core/unregister-case! :contracts-other/case)
+      (core/unregister-scene! :contracts-other))))
+
+(t/deftest scene-without-params-schema-is-rejected
+  (try
+    (core/register-scene! {:id :contracts-noschema
+                           :ns "contracts-test"
+                           :version 1
+                           :description "x"
+                           :build (fn [params] params)})
+    (t/is (= ::core/invalid-scene
+             (:type (failure-data #(cases/collect-cases {:master-seed 42})))))
+    (finally
+      (core/unregister-scene! :contracts-noschema))))
+
+(t/deftest malformed-params-schema-is-rejected
+  (try
+    (core/register-scene! {:id :contracts-badschema
+                           :ns "contracts-test"
+                           :version 1
+                           :description "x"
+                           :params-schema [:map [:count]]
+                           :build (fn [params] params)})
+    (let [data (failure-data #(cases/collect-cases {:master-seed 42}))]
+      (t/is (= ::core/invalid-scene (:type data)))
+      (t/is (= :contracts-badschema (:id data))))
+    (finally
+      (core/unregister-scene! :contracts-badschema))))
+
+(t/deftest qualified-scene-id-is-rejected
+  (try
+    (core/register-scene! {:id :contracts-ns/scene
+                           :ns "contracts-test"
+                           :version 1
+                           :description "x"
+                           :params-schema [:map]
+                           :build (fn [params] params)})
+    (t/is (= ::core/invalid-scene
+             (:type (failure-data #(cases/collect-cases {:master-seed 42})))))
+    (finally
+      (core/unregister-scene! :contracts-ns/scene))))
+
+(t/deftest invalid-declarations-fail-outside-the-filter
+  (with-synthetic-scene :contracts-global {:count 1 :bogus 2}
+    (fn []
+      (t/is (= ::cases/invalid-case
+               (:type (failure-data #(cases/collect-cases {:master-seed 42
+                                                           :filter "rects/"}))))))))
+
+(t/deftest incomplete-case-declaration-is-rejected
+  (try
+    (core/register-scene! {:id :contracts-incomplete
+                           :ns "contracts-test"
+                           :version 1
+                           :description "x"
+                           :params-schema [:map]
+                           :build (fn [params] params)})
+    (core/register-case! {:id :contracts-incomplete/case
+                          :scene :contracts-incomplete
+                          :ns "contracts-test"
+                          :params {}
+                          :context :fresh})
+    (t/is (= ::cases/invalid-case
+             (:type (failure-data #(cases/collect-cases {:master-seed 42
+                                                         :filter "contracts-incomplete/"})))))
+    (finally
+      (core/unregister-case! :contracts-incomplete/case)
+      (core/unregister-scene! :contracts-incomplete))))
+
+(t/deftest records-are-not-plain-data
+  (let [point (->Point 1 2)]
+    (t/is (false? (core/serializable? point)))
+    (t/is (false? (core/serializable? {:point point})))))
+
+(t/deftest case-replacement-preserves-order-and-unregister-removes
+  (try
+    (core/register-scene! {:id :contracts-replacecase
+                           :ns "contracts-test"
+                           :version 1
+                           :description "x"
+                           :params-schema [:map]
+                           :build (fn [params] params)})
+    (core/register-case! {:id :contracts-replacecase/case
+                          :scene :contracts-replacecase
+                          :ns "contracts-test"
+                          :params {}
+                          :view {:scale 1 :x 0 :y 0}
+                          :context :fresh})
+    (core/register-case! {:id :contracts-replacecase/case
+                          :scene :contracts-replacecase
+                          :ns "contracts-test"
+                          :params {}
+                          :view {:scale 2 :x 0 :y 0}
+                          :context :fresh})
+    (t/is (= 1 (count (filter #(= :contracts-replacecase/case (:id %)) (core/cases)))))
+    (t/is (= {:scale 2 :x 0 :y 0} (:view (core/registered-case :contracts-replacecase/case))))
+    (core/unregister-case! :contracts-replacecase/case)
+    (t/is (nil? (core/registered-case :contracts-replacecase/case)))
+    (finally
+      (core/unregister-case! :contracts-replacecase/case)
+      (core/unregister-scene! :contracts-replacecase))))
+
+(t/deftest invalid-master-seed-is-rejected
+  (doseq [seed [-1 4294967296 "42"]]
+    (t/is (= ::cases/invalid-master-seed
+             (:type (failure-data #(cases/collect-cases {:master-seed seed}))))
+          (str seed))))
+
+(t/deftest filter-matches-case-ids
+  (t/is (= [:rects/pan]
+           (mapv :id (cases/collect-cases {:master-seed 42 :filter "rects/pan"}))))
+  (t/is (= 3 (count (cases/collect-cases {:master-seed 42 :filter "rects/"})))))
+
+(t/deftest empty-selection-is-rejected
+  (t/is (= ::cases/no-cases
+           (:type (failure-data #(cases/collect-cases {:master-seed 42
+                                                       :filter "missing"}))))))
+
+(t/deftest defcase-body-is-stored-and-stripped
+  (let [entry (core/registered-case :contracts-scene/case)]
+    (t/is (= "frontend-tests.benches.contracts-test" (:ns entry)))
+    (t/is (fn? (:run! entry)))
+    (t/is (= ::boom (:type (failure-data #((:run! entry) :runtime))))))
+  (let [collected (cases/collect-cases {:master-seed 42 :filter "contracts-scene/"})]
+    (t/is (= [:contracts-scene/case] (mapv :id collected)))
+    (t/is (not (contains? (first collected) :run!)))
+    (t/is (core/serializable? (first collected)))))