diff --git a/src/main/__fixtures__/shell-wrapper-snapshots/daemon-bash-rcfile.txt b/src/main/__fixtures__/shell-wrapper-snapshots/daemon-bash-rcfile.txt
index 03453cb33d3..d5fe9e9a153 100644
--- a/src/main/__fixtures__/shell-wrapper-snapshots/daemon-bash-rcfile.txt
+++ b/src/main/__fixtures__/shell-wrapper-snapshots/daemon-bash-rcfile.txt
@@ -65,9 +65,14 @@ fi
 # Why: Codex must keep using Orca's runtime CODEX_HOME after profile scripts.
 [[ -n "${ORCA_CODEX_HOME:-}" ]] && export CODEX_HOME="${ORCA_CODEX_HOME}"
 # Why: a typed alias expands inside the shell, after pane launch prep.
-__orca_codex_binary="$(command -v codex 2>/dev/null || :)"
+# Why unalias inside the substitution: an alias named codex makes command -v
+# report the alias text, and the subshell leaves the user's own alias intact.
+# Why the trailing || : — zsh, unlike bash, inherits errexit into substitutions.
+__orca_codex_binary="$(unalias codex 2>/dev/null || :; command -v codex 2>/dev/null || :)"
 if [[ -n "${ORCA_CODEX_LAUNCH_PREFLIGHT:-}" && -n "${__orca_codex_binary:-}" && -x "${__orca_codex_binary}" ]]; then
-  codex() {
+  # Why the function reserved word: it suppresses alias expansion of the name,
+  # which otherwise rewrites this header at parse time and aborts the whole file.
+  function codex {
     "${ORCA_CODEX_LAUNCH_PREFLIGHT}" agent hooks prepare-codex >/dev/null 2>&1 || :
     command codex "$@"
   }
diff --git a/src/main/__fixtures__/shell-wrapper-snapshots/daemon-zsh-zshenv.txt b/src/main/__fixtures__/shell-wrapper-snapshots/daemon-zsh-zshenv.txt
index 1b89c740f2b..dc44746ad74 100644
--- a/src/main/__fixtures__/shell-wrapper-snapshots/daemon-zsh-zshenv.txt
+++ b/src/main/__fixtures__/shell-wrapper-snapshots/daemon-zsh-zshenv.txt
@@ -103,9 +103,14 @@ __orca_deferred_init() {
     # Why: Codex must keep using Orca's runtime CODEX_HOME after rc files.
     [[ -n "${ORCA_CODEX_HOME:-}" ]] && export CODEX_HOME="${ORCA_CODEX_HOME}"
     # Why: a typed alias expands inside the shell, after pane launch prep.
-    __orca_codex_binary="$(command -v codex 2>/dev/null || :)"
+    # Why unalias inside the substitution: an alias named codex makes command -v
+    # report the alias text, and the subshell leaves the user's own alias intact.
+    # Why the trailing || : — zsh, unlike bash, inherits errexit into substitutions.
+    __orca_codex_binary="$(unalias codex 2>/dev/null || :; command -v codex 2>/dev/null || :)"
     if [[ -n "${ORCA_CODEX_LAUNCH_PREFLIGHT:-}" && -n "${__orca_codex_binary:-}" && -x "${__orca_codex_binary}" ]]; then
-      codex() {
+      # Why the function reserved word: it suppresses alias expansion of the name,
+      # which otherwise rewrites this header at parse time and aborts the whole file.
+      function codex {
         "${ORCA_CODEX_LAUNCH_PREFLIGHT}" agent hooks prepare-codex >/dev/null 2>&1 || :
         command codex "$@"
       }
diff --git a/src/main/__fixtures__/shell-wrapper-snapshots/local-bash-rcfile.txt b/src/main/__fixtures__/shell-wrapper-snapshots/local-bash-rcfile.txt
index 3041e85391d..d203217598f 100644
--- a/src/main/__fixtures__/shell-wrapper-snapshots/local-bash-rcfile.txt
+++ b/src/main/__fixtures__/shell-wrapper-snapshots/local-bash-rcfile.txt
@@ -68,9 +68,14 @@ fi
 # Why: Codex must keep using Orca's runtime CODEX_HOME after profile scripts.
 [[ -n "${ORCA_CODEX_HOME:-}" ]] && export CODEX_HOME="${ORCA_CODEX_HOME}"
 # Why: a typed alias expands inside the shell, after pane launch prep.
-__orca_codex_binary="$(command -v codex 2>/dev/null || :)"
+# Why unalias inside the substitution: an alias named codex makes command -v
+# report the alias text, and the subshell leaves the user's own alias intact.
+# Why the trailing || : — zsh, unlike bash, inherits errexit into substitutions.
+__orca_codex_binary="$(unalias codex 2>/dev/null || :; command -v codex 2>/dev/null || :)"
 if [[ -n "${ORCA_CODEX_LAUNCH_PREFLIGHT:-}" && -n "${__orca_codex_binary:-}" && -x "${__orca_codex_binary}" ]]; then
-  codex() {
+  # Why the function reserved word: it suppresses alias expansion of the name,
+  # which otherwise rewrites this header at parse time and aborts the whole file.
+  function codex {
     "${ORCA_CODEX_LAUNCH_PREFLIGHT}" agent hooks prepare-codex >/dev/null 2>&1 || :
     command codex "$@"
   }
diff --git a/src/main/__fixtures__/shell-wrapper-snapshots/local-zsh-zshenv.txt b/src/main/__fixtures__/shell-wrapper-snapshots/local-zsh-zshenv.txt
index d73f2d4c4c9..05321e97fa9 100644
--- a/src/main/__fixtures__/shell-wrapper-snapshots/local-zsh-zshenv.txt
+++ b/src/main/__fixtures__/shell-wrapper-snapshots/local-zsh-zshenv.txt
@@ -103,9 +103,14 @@ __orca_deferred_init() {
     # Why: Codex must keep using Orca's runtime CODEX_HOME after rc files.
     [[ -n "${ORCA_CODEX_HOME:-}" ]] && export CODEX_HOME="${ORCA_CODEX_HOME}"
     # Why: a typed alias expands inside the shell, after pane launch prep.
-    __orca_codex_binary="$(command -v codex 2>/dev/null || :)"
+    # Why unalias inside the substitution: an alias named codex makes command -v
+    # report the alias text, and the subshell leaves the user's own alias intact.
+    # Why the trailing || : — zsh, unlike bash, inherits errexit into substitutions.
+    __orca_codex_binary="$(unalias codex 2>/dev/null || :; command -v codex 2>/dev/null || :)"
     if [[ -n "${ORCA_CODEX_LAUNCH_PREFLIGHT:-}" && -n "${__orca_codex_binary:-}" && -x "${__orca_codex_binary}" ]]; then
-      codex() {
+      # Why the function reserved word: it suppresses alias expansion of the name,
+      # which otherwise rewrites this header at parse time and aborts the whole file.
+      function codex {
         "${ORCA_CODEX_LAUNCH_PREFLIGHT}" agent hooks prepare-codex >/dev/null 2>&1 || :
         command codex "$@"
       }