diff --git a/common/src/app/common/types/shape/text.cljc b/common/src/app/common/types/shape/text.cljc
index 50bbeaa6d7..7b493580c0 100644
--- a/common/src/app/common/types/shape/text.cljc
+++ b/common/src/app/common/types/shape/text.cljc
@@ -22,6 +22,11 @@
   [attr]
   (into [:enum] (get cjk/enum-values attr)))
 
+;; BCP 47 shaped language tag of a paragraph, as the HTML `lang` attribute.
+(def schema:text-language
+  [:re {:gen/elements ["ja" "zh-Hans" "zh-Hant-TW" "ko" "en-GB"]}
+   #"^(?:[A-Za-z]{2,8}(?:-[A-Za-z0-9]{1,8})*|[xXiI](?:-[A-Za-z0-9]{1,8})+)$"])
+
 (def schema:content
   [:map
    [:type [:= "root"]]
@@ -45,9 +50,7 @@
          [:font-weight {:optional true} ::sm/text]
          [:direction {:optional true} ::sm/text]
          ;; Paragraph language selects typography; it never follows the UI locale.
-         [:text-language {:optional true}
-          [:re {:gen/elements ["ja" "zh-Hans" "zh-Hant-TW" "ko" "en-GB"]}
-           #"^(?:[A-Za-z]{2,8}(?:-[A-Za-z0-9]{1,8})*|[xXiI](?:-[A-Za-z0-9]{1,8})+)$"]]
+         [:text-language {:optional true} schema:text-language]
          ;; Word mode keeps punctuation rules; retain the old POC value on reload.
          [:korean-wrap {:optional true} [:enum "syllable" "spaces-only" "keep-words"]]
          [:writing-mode {:optional true} (schema:jl-enum :writing-mode)]
diff --git a/frontend/src/app/main/data/workspace/texts.cljs b/frontend/src/app/main/data/workspace/texts.cljs
index d0c07386a5..83dd201960 100644
--- a/frontend/src/app/main/data/workspace/texts.cljs
+++ b/frontend/src/app/main/data/workspace/texts.cljs
@@ -593,17 +593,36 @@
             [start end] (annotated-span-bounds content start end)]
         (<= (count (overlapping-text-nodes content start end)) 1))))
 
+;; Paragraph attrs a text range sets on the whole paragraphs it touches.
+(def ^:private range-paragraph-attrs
+  [:text-language])
+
+(defn- update-paragraph-range
+  "Applies `attrs` to the paragraphs of a range-decorated content with
+   characters in [start, end); a nil value removes the attr."
+  [content start end attrs]
+  (txt/transform-nodes
+   (fn [node]
+     (and (txt/is-paragraph-node? node)
+          (let [{node-start :start node-end :end} (meta node)]
+            (and (< node-start end) (< start node-end)))))
+   #(d/patch-object % attrs)
+   content))
+
 (defn update-text-range-attrs
   "Applies `attrs` to the characters [start, end) of a text shape. A range
    that cuts a ruby or warichu span covers the whole span. Spans left with
-   the same style as their neighbour are joined back."
+   the same style as their neighbour are joined back. Paragraph attrs such
+   as the language go to the whole paragraphs the range touches."
   [shape start end attrs]
   (let [content     (decorate-range-info (:content shape))
         [start end] (annotated-span-bounds content start end)
+        span-attrs  (apply dissoc attrs range-paragraph-attrs)
         new-content (->> (-> content
+                             (update-paragraph-range start end (select-keys attrs range-paragraph-attrs))
                              (split-content-at start)
                              (split-content-at end)
-                             (update-content-range start end attrs))
+                             (update-content-range start end span-attrs))
                          (txt/transform-nodes txt/is-paragraph-node?
                                               #(d/update-when % :children txt/merge-equal-spans)))]
     (assoc shape :content new-content)))
diff --git a/frontend/src/app/plugins/text.cljs b/frontend/src/app/plugins/text.cljs
index 593cb862b5..3b405dc4b3 100644
--- a/frontend/src/app/plugins/text.cljs
+++ b/frontend/src/app/plugins/text.cljs
@@ -12,6 +12,7 @@
    [app.common.record :as crc]
    [app.common.schema :as sm]
    [app.common.types.fills :as types.fills]
+   [app.common.types.shape.text :as ctst]
    [app.common.types.text :as txt]
    [app.common.types.text.cjk-layout :as cjk]
    [app.main.data.workspace.shapes :as dwsh]
@@ -129,6 +130,18 @@
   [value]
   (or (nil? value) (string? value)))
 
+(defn- language-tag?
+  "Validator for a text language: a BCP 47 tag, or nil or '' to remove it."
+  [value]
+  (or (nil? value)
+      (= "" value)
+      (sm/validate ctst/schema:text-language value)))
+
+(defn- language-attrs
+  "Update attrs for a language value; nil or '' removes the language."
+  [attrs]
+  (update attrs :text-language not-empty))
+
 (defn- attr-setter
   "Property setter that checks `valid?` and the plugin's write access before
    emitting `(update-event self attrs)` with `{attr value}`."
@@ -532,6 +545,17 @@
      :get (fn [self] (range-japanese-value self start end :ruby-side))
      :set (range-attr-setter plugin-id page-id id start end :rubySide :ruby-side (enum-value? :ruby-side))}
 
+    :lang
+    {:this true
+     :get
+     (fn [self]
+       (->> (-> self u/proxy->shape :content (content-range->text+styles start end))
+            (map :text-language)
+            (u/mixed-value)))
+     :set
+     (attr-setter plugin-id page-id :lang :text-language language-tag?
+                  (fn [_ attrs] (dwt/update-text-range id start end (language-attrs attrs))))}
+
     :direction
     {:this true
      :get
@@ -1009,5 +1033,11 @@
       :get #(shape-japanese-value % :ruby-side)
       :set (shape-attr-setter plugin-id page-id :rubySide :ruby-side (enum-value? :ruby-side))}
 
+     {:name "lang"
+      :get #(-> % u/proxy->shape text-props :text-language format/format-mixed)
+      :set (attr-setter plugin-id page-id :lang :text-language language-tag?
+                        (fn [self attrs]
+                          (dwt/update-attrs (obj/get self "$id") (language-attrs attrs))))}
+
      {:name "textBounds"
       :get #(-> % u/proxy->shape gst/shape->bounds format/format-geom-rect)})))
diff --git a/frontend/test/frontend_tests/data/workspace_texts_test.cljs b/frontend/test/frontend_tests/data/workspace_texts_test.cljs
index 1baa5c14d3..23ec29aba8 100644
--- a/frontend/test/frontend_tests/data/workspace_texts_test.cljs
+++ b/frontend/test/frontend_tests/data/workspace_texts_test.cljs
@@ -948,3 +948,17 @@
           shape (dwt/update-text-range-attrs shape 0 4 {:ruby nil})]
       (t/is (= [{:text "一盅兩件"}] (spans-of shape)))
       (t/is (dwt/single-span-range? (:content shape) 0 4)))))
+
+(t/deftest update-text-range-sets-the-language-on-the-paragraphs-it-touches
+  (let [content {:type "root"
+                 :children [{:type "paragraph-set"
+                             :children [{:type "paragraph" :children [{:text "ab" :font-size "20"}]}
+                                        {:type "paragraph" :children [{:text "cd" :font-size "20"}]}]}]}
+        languages (fn [shape]
+                    (->> (:content shape) (txt/node-seq txt/is-paragraph-node?) (mapv :text-language)))
+        shape     (dwt/update-text-range-attrs {:content content} 3 4 {:text-language "ja"})]
+    (t/is (= [nil "ja"] (languages shape)))
+    (t/is (= [{:text "ab"} {:text "cd"}] (spans-of shape))
+          "spans are neither split nor given the language")
+    (t/is (= [nil nil]
+             (languages (dwt/update-text-range-attrs shape 0 5 {:text-language nil}))))))
diff --git a/frontend/test/frontend_tests/plugins/text_test.cljs b/frontend/test/frontend_tests/plugins/text_test.cljs
index c5f472aa51..47cdac8467 100644
--- a/frontend/test/frontend_tests/plugins/text_test.cljs
+++ b/frontend/test/frontend_tests/plugins/text_test.cljs
@@ -366,3 +366,45 @@
     (t/is (= {:ruby-zhuyin true} (:attrs result)))
     (t/is (nil? (:attrs bad)))
     (t/is (= {:ruby-zhuyin false} (:attrs shape)))))
+
+(defn- paragraphs-content
+  "Content with one single-span paragraph per [text language] pair."
+  [& paragraphs]
+  {:type "root"
+   :children [{:type "paragraph-set"
+               :children (vec (for [[text language] paragraphs]
+                                (cond-> {:type "paragraph" :children [{:text text}]}
+                                  language (assoc :text-language language))))}]})
+
+(t/deftest text-lang-reads-the-paragraph-language
+  (let [[^js text shape] (text-proxy-over (paragraphs-content ["香港" "zh-Hant-HK"]))]
+    (with-redefs [u/proxy->shape (constantly shape)]
+      (t/is (= "zh-Hant-HK" (.-lang text)))))
+  (let [[^js text shape] (text-proxy-over (paragraphs-content ["plain" nil]))]
+    (with-redefs [u/proxy->shape (constantly shape)]
+      (t/is (nil? (.-lang text)))))
+  (let [[^js text shape] (text-proxy-over (paragraphs-content ["香港" "zh-Hant-HK"] ["plain" nil]))]
+    (with-redefs [u/proxy->shape (constantly shape)]
+      (t/is (= "mixed" (.-lang text))))))
+
+(t/deftest text-range-lang-reads-the-paragraphs-it-touches
+  (let [content (paragraphs-content ["香港" "zh-Hant-HK"] ["東京" "ja"])
+        range   (fn [start end]
+                  (plugins.text/text-range-proxy plugin-id (random-uuid) (random-uuid) (random-uuid) start end))]
+    (with-redefs [u/proxy->shape (constantly {:content content})]
+      (t/is (= "zh-Hant-HK" (.-lang (range 0 2))))
+      (t/is (= "ja" (.-lang (range 3 5))))
+      (t/is (= "mixed" (.-lang (range 1 4)))))))
+
+(t/deftest lang-accepts-language-tags-and-clears-with-empty-values
+  (let [content (paragraphs-content ["香港" nil])
+        text    (plugins.text/add-text-props #js {:$id (random-uuid) :$page (random-uuid)} plugin-id)
+        range   (plugins.text/text-range-proxy plugin-id (random-uuid) (random-uuid) (random-uuid) 0 2)]
+    (doseq [target [text range]]
+      (t/is (= {:text-language "zh-Hant-HK"} (:attrs (capture-japanese-update target "lang" "zh-Hant-HK" content))))
+      (t/is (= {:text-language nil} (:attrs (capture-japanese-update target "lang" "" content))))
+      (t/is (= {:text-language nil} (:attrs (capture-japanese-update target "lang" nil content))))
+      (doseq [bad ["not a tag" "zh_Hant" 42]]
+        (let [result (capture-japanese-update target "lang" bad content)]
+          (t/is (nil? (:attrs result)))
+          (t/is (= bad (:rejected result))))))))
diff --git a/plugins/CHANGELOG.md b/plugins/CHANGELOG.md
index fc396c7d7c..0d4b51b1c6 100644
--- a/plugins/CHANGELOG.md
+++ b/plugins/CHANGELOG.md
@@ -27,6 +27,7 @@
 - **plugin-types:** Added `fontFeatures` (`none`, `palt`, or `vpal`) to text shapes and text ranges.
 - **plugin-types:** Added `annotationClearance` (`none` or `auto`) to text shapes.
 - **plugin-types:** Added `lineAdjustment` (`push-in-first`, `push-out-first` or `push-out-only`) to text shapes: how Japanese lines slightly too long are fitted.
+- **plugin-types:** Added `lang` to text shapes and ranges: the paragraph language as a BCP 47 tag (`ja`, `zh-Hant-HK`, `ko`...), which selects the CJK typesetting rules.
 
 ### 🩹 Fixes
 
diff --git a/plugins/libs/plugin-types/index.d.ts b/plugins/libs/plugin-types/index.d.ts
index 39a3ff48ba..b4e7493811 100644
--- a/plugins/libs/plugin-types/index.d.ts
+++ b/plugins/libs/plugin-types/index.d.ts
@@ -4820,6 +4820,18 @@ export interface Text extends ShapeBase {
   /** Ruby side: `over` (above or right, the default) or `under` (below or left). */
   rubySide: 'over' | 'under' | 'mixed';
 
+  /**
+   * Language of the text as a BCP 47 tag, like the HTML `lang` attribute.
+   * Japanese (`ja`), Chinese (`zh-Hans`, `zh-Hant`, or with a region:
+   * `zh-Hans-CN`, `zh-Hant-TW`, `zh-Hant-HK`...) and Korean (`ko`) tags
+   * select their typesetting rules: line breaking, punctuation spacing, the
+   * default emphasis position and localized glyph forms. Other tags are
+   * stored without rules. `null` (the default) applies none; set `null` or
+   * `''` to remove it. It belongs to paragraphs: setting it applies
+   * to every paragraph. Returns 'mixed' if paragraphs use different values.
+   */
+  lang: string | 'mixed' | null;
+
   /**
    * Return the bounding box for the text as a (x, y, width, height) rectangle
    * This is the box that covers the text even if it overflows its selection rectangle.
@@ -5007,6 +5019,19 @@ export interface TextRange {
   /** Ruby side: `over` (above or right, the default) or `under` (below or left). */
   rubySide: 'over' | 'under' | 'mixed' | null;
 
+  /**
+   * Language of the text as a BCP 47 tag, like the HTML `lang` attribute.
+   * Japanese (`ja`), Chinese (`zh-Hans`, `zh-Hant`, or with a region:
+   * `zh-Hans-CN`, `zh-Hant-TW`, `zh-Hant-HK`...) and Korean (`ko`) tags
+   * select their typesetting rules: line breaking, punctuation spacing, the
+   * default emphasis position and localized glyph forms. Other tags are
+   * stored without rules. `null` (the default) applies none; set `null` or
+   * `''` to remove it. It belongs to paragraphs: setting it applies
+   * to every paragraph the range touches. Returns 'mixed' if those
+   * paragraphs use different values.
+   */
+  lang: string | 'mixed' | null;
+
   /**
    * The text direction for the text range. It can be a specific direction or 'mixed' if multiple directions are used.
    */