From a559371fc9f48f10a92c01794b010d19a7592802 Mon Sep 17 00:00:00 2001
From: Melody Ruch <396921921@qq.com>
Date: Fri, 4 Sep 2026 16:55:08 +0800
Subject: [PATCH] fix(editor): disable code editor font ligatures

---
 .../desktop/src/lib/__tests__/editorThemes.spec.ts | 14 ++++++++++++++
 apps/desktop/src/lib/editor/editorThemes.ts        | 10 ++++++++++
 2 files changed, 24 insertions(+)

diff --git a/apps/desktop/src/lib/__tests__/editorThemes.spec.ts b/apps/desktop/src/lib/__tests__/editorThemes.spec.ts
index 890b91495a..5311d459de 100644
--- a/apps/desktop/src/lib/__tests__/editorThemes.spec.ts
+++ b/apps/desktop/src/lib/__tests__/editorThemes.spec.ts
@@ -202,3 +202,17 @@ describe("editor gutters", () => {
     });
   });
 });
+
+describe("editor font theme", () => {
+  it("disables ligatures on the editor content so repainted character runs stay stable", () => {
+    const rules = buildEditorFontThemeRules();
+
+    // Ligature fonts merge runs like `--`/`==` into one glyph and can race
+    // CodeMirror's per-keystroke span patching (dbx#7900); dropping either
+    // declaration would reintroduce unpainted characters in the query editor.
+    expect(rules[".cm-content"]).toMatchObject({
+      fontVariantLigatures: "none",
+      fontFeatureSettings: '"liga" 0, "calt" 0',
+    });
+  });
+});
diff --git a/apps/desktop/src/lib/editor/editorThemes.ts b/apps/desktop/src/lib/editor/editorThemes.ts
index c563912ea1..fa84263bb2 100644
--- a/apps/desktop/src/lib/editor/editorThemes.ts
+++ b/apps/desktop/src/lib/editor/editorThemes.ts
@@ -763,6 +763,16 @@ export function buildEditorFontThemeRules(opts?: { fixedHeight?: boolean; scroll
     ...(opts?.scrollable ? { ".cm-scroller": { overflowX: "auto", overflowY: "auto" } } : {}),
     ".cm-content": {
       fontFamily: `var(${EDITOR_FONT_FAMILY_CSS_VAR}, ${defaults?.family ?? "monospace"})`,
+      // Ligature fonts (Fira Code, Cascadia Code, JetBrains Mono, ...) combine
+      // runs like `--`/`==` into a single shaped glyph. CodeMirror repaints
+      // edited lines by patching individual character spans, and that
+      // per-keystroke patching can race the browser's ligature reshaping when
+      // the same character is typed repeatedly in place, leaving earlier
+      // characters unpainted until something else forces a repaint (dbx#7900).
+      // Disabling ligatures here avoids the reshaping entirely, matching the
+      // same fix already applied to DataGridConditionEditor.vue.
+      fontVariantLigatures: "none",
+      fontFeatureSettings: '"liga" 0, "calt" 0',
       lineHeight: "1.6",
       padding: "0",
     },