diff --git a/bin/bwopencode b/bin/bwopencode
index 77f1911..db29d37 100755
--- a/bin/bwopencode
+++ b/bin/bwopencode
@@ -41,6 +41,9 @@
 #   - Namespace tools: masked (nsenter, unshare, chroot)
 #   - Keyring tools: masked (keyctl)
 #   - SSH/GPG agent env vars: stripped
+#   - Zellij env vars (ZELLIJ, ZELLIJ_SESSION_NAME, ZELLIJ_PANE_ID): passed;
+#     inside Zellij OPENTUI_FORCE_WCWIDTH=1 is also set so the TUI's column
+#     counts match Zellij's (a user-set OPENTUI_FORCE_WCWIDTH wins)
 #   - ~/.bashrc and other shell rc files: not mounted
 #
 # Usage:
diff --git a/bin/bwopencode2 b/bin/bwopencode2
index af42e87..7d4c179 100755
--- a/bin/bwopencode2
+++ b/bin/bwopencode2
@@ -66,6 +66,9 @@
 #   - Namespace tools: masked (nsenter, unshare, chroot)
 #   - Keyring tools: masked (keyctl)
 #   - SSH/GPG agent env vars: stripped
+#   - Zellij env vars (ZELLIJ, ZELLIJ_SESSION_NAME, ZELLIJ_PANE_ID): passed;
+#     inside Zellij OPENTUI_FORCE_WCWIDTH=1 is also set so the TUI's column
+#     counts match Zellij's (a user-set OPENTUI_FORCE_WCWIDTH wins)
 #   - ~/.bashrc and other shell rc files: not mounted
 #
 # Sandbox-escape guard: OpenCode 2 normally talks to a shared background
diff --git a/lib/bwrap_sandbox_lib.sh b/lib/bwrap_sandbox_lib.sh
index 6366971..d8a00be 100644
--- a/lib/bwrap_sandbox_lib.sh
+++ b/lib/bwrap_sandbox_lib.sh
@@ -2601,6 +2601,22 @@ build_env_vars() {
     pass_through_if_set COLORTERM
     pass_through_if_set TERM_PROGRAM
 
+    # Zellij: these only identify the session (no socket is mounted), so
+    # OpenTUI can tell it runs inside Zellij.  Zellij drops zero-width
+    # code points (emoji variation selectors, ZWJ) and has no grapheme width
+    # mode, so OpenTUI's default width counting drifts from Zellij's and the
+    # screen is left garbled until a resize.  Count each code point on its
+    # own (OPENTUI_FORCE_WCWIDTH, which OpenTUI only tests for presence)
+    # unless the user set it themselves.
+    pass_through_if_set ZELLIJ
+    pass_through_if_set ZELLIJ_SESSION_NAME
+    pass_through_if_set ZELLIJ_PANE_ID
+    if [[ -n "${OPENTUI_FORCE_WCWIDTH+x}" ]]; then
+        SANDBOX_ENV+=("OPENTUI_FORCE_WCWIDTH=${OPENTUI_FORCE_WCWIDTH}")
+    elif [[ -n "${ZELLIJ:-}" ]]; then
+        SANDBOX_ENV+=("OPENTUI_FORCE_WCWIDTH=1")
+    fi
+
     # Locale
     pass_through_if_set LANG
     pass_through_if_set LC_ALL