From 2f4e331ba685818589e885fbf01f1057a8441de7 Mon Sep 17 00:00:00 2001
From: diegosouzapw <diegosouza.pw@gmail.com>
Date: Sat, 23 May 2026 09:13:04 -0300
Subject: [PATCH] fix(selection): skip wide-character continuation cells when
 copying
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When the selection range covered text containing wide characters
(CJK, fullwidth Latin, etc.), copying the selection inserted a stray
space between every wide glyph — e.g. "안녕하" came out as "안 녕 하 ".

Root cause: wide characters occupy two terminal cells. The first cell
has the codepoint and width=2; the second cell is a continuation
marker with codepoint=0 and width=0. SelectionManager.getSelection's
empty-cell branch treated both empty cells AND continuation cells the
same way and appended a space.

Fix: skip continuation cells (cell exists with width===0) in the
empty-cell branch. Only truly empty cells (no cell, or cell.width!==0
with codepoint===0) get a space.

Ports only the selection-manager subset of upstream PR #120 — the rest
of that PR (IME composition routing, textarea-focus refactor, removal
of contenteditable) needs more analysis around regressions with browser
extensions and is deferred to a separate port.

Adds one regression test asserting that selecting "안녕하" copies as
"안녕하", not "안 녕 하".

Co-authored-by: Seungwoo Hong <ai.baryon.ai@gmail.com>
Inspired-by: https://github.com/coder/ghostty-web/pull/120
---
 lib/selection-manager.test.ts | 23 +++++++++++++++++++++++
 lib/selection-manager.ts      | 10 +++++++++-
 2 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/lib/selection-manager.test.ts b/lib/selection-manager.test.ts
index 663abc01..1e4e6d7c 100644
--- a/lib/selection-manager.test.ts
+++ b/lib/selection-manager.test.ts
@@ -189,6 +189,29 @@ describe('SelectionManager', () => {
       term.dispose();
     });
 
+    test('getSelection does not insert spaces between wide (CJK) characters', async () => {
+      if (!container) return;
+
+      const term = await createIsolatedTerminal({ cols: 80, rows: 24 });
+      term.open(container);
+
+      // Three Korean wide characters — each occupies 2 terminal cells:
+      // leading cell {codepoint: ..., width: 2} + continuation cell
+      // {codepoint: 0, width: 0}. The fix ensures we skip continuation
+      // cells instead of treating them as empty cells (which would
+      // produce "안 녕 하" with stray spaces between glyphs).
+      term.write('안녕하\r\n');
+
+      const scrollbackLen = term.wasmTerm!.getScrollbackLength();
+      // Select the 6 cells covering all three wide chars
+      setSelectionAbsolute(term, 0, scrollbackLen, 5, scrollbackLen);
+
+      const selMgr = (term as any).selectionManager;
+      expect(selMgr.getSelection()).toBe('안녕하');
+
+      term.dispose();
+    });
+
     test('getSelection extracts multi-line text', async () => {
       if (!container) return;
 
diff --git a/lib/selection-manager.ts b/lib/selection-manager.ts
index 56d46059..86900fe1 100644
--- a/lib/selection-manager.ts
+++ b/lib/selection-manager.ts
@@ -183,7 +183,15 @@ export class SelectionManager {
           if (char.trim()) {
             lastNonEmpty = lineText.length;
           }
-        } else {
+        } else if (!cell || cell.width !== 0) {
+          // Only add a space for truly empty cells, NOT for wide-character
+          // continuation cells. Wide characters (CJK, fullwidth Latin, etc.)
+          // occupy 2 terminal cells:
+          //   - First cell:  codepoint set, width=2
+          //   - Second cell: codepoint=0, width=0 (continuation marker)
+          // The first branch above handles the leading cell. We must skip
+          // the trailing continuation cell here, otherwise the copied text
+          // gets a stray space between every wide character.
           lineText += ' ';
         }
       }