diff --git a/codex-rs/protocol/src/config_types.rs b/codex-rs/protocol/src/config_types.rs
index aa28e1a6fac..c98b3117ca1 100644
--- a/codex-rs/protocol/src/config_types.rs
+++ b/codex-rs/protocol/src/config_types.rs
@@ -98,6 +98,7 @@ pub enum WindowsSandboxLevel {
 pub enum Personality {
     Friendly,
     Pragmatic,
+    None,
 }
 
 #[derive(
diff --git a/codex-rs/protocol/src/openai_models.rs b/codex-rs/protocol/src/openai_models.rs
index 90cf34f3935..8c7942c506b 100644
--- a/codex-rs/protocol/src/openai_models.rs
+++ b/codex-rs/protocol/src/openai_models.rs
@@ -337,6 +337,8 @@ impl ModelInstructionsVariables {
             match personality {
                 Personality::Friendly => self.personality_friendly.clone(),
                 Personality::Pragmatic => self.personality_pragmatic.clone(),
+                // When None is explicitly selected, return None so no personality is injected
+                Personality::None => None,
             }
         } else {
             self.personality_default.clone()
diff --git a/codex-rs/tui/src/app.rs b/codex-rs/tui/src/app.rs
index 878d4d5da2d..7cacd7f17ac 100644
--- a/codex-rs/tui/src/app.rs
+++ b/codex-rs/tui/src/app.rs
@@ -2328,6 +2328,7 @@ impl App {
         match personality {
             Personality::Friendly => "Friendly",
             Personality::Pragmatic => "Pragmatic",
+            Personality::None => "None",
         }
     }
 
diff --git a/codex-rs/tui/src/chatwidget.rs b/codex-rs/tui/src/chatwidget.rs
index 52a1b544044..9a85ade8830 100644
--- a/codex-rs/tui/src/chatwidget.rs
+++ b/codex-rs/tui/src/chatwidget.rs
@@ -4004,7 +4004,7 @@ impl ChatWidget {
 
     fn open_personality_popup_for_current_model(&mut self) {
         let current_personality = self.config.personality.unwrap_or(Personality::Friendly);
-        let personalities = [Personality::Friendly, Personality::Pragmatic];
+        let personalities = [Personality::Friendly, Personality::Pragmatic, Personality::None];
         let supports_personality = self.current_model_supports_personality();
 
         let items: Vec<SelectionItem> = personalities
@@ -5499,6 +5499,7 @@ impl ChatWidget {
         match personality {
             Personality::Friendly => "Friendly",
             Personality::Pragmatic => "Pragmatic",
+            Personality::None => "None",
         }
     }
 
@@ -5506,6 +5507,7 @@ impl ChatWidget {
         match personality {
             Personality::Friendly => "Warm, collaborative, and helpful.",
             Personality::Pragmatic => "Concise, task-focused, and direct.",
+            Personality::None => "No personality - purely functional responses.",
         }
     }
 
diff --git a/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__personality_selection_popup.snap b/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__personality_selection_popup.snap
index 3c6bba94e61..2c1ba2c4e44 100644
--- a/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__personality_selection_popup.snap
+++ b/codex-rs/tui/src/chatwidget/snapshots/codex_tui__chatwidget__tests__personality_selection_popup.snap
@@ -7,5 +7,6 @@ expression: popup
 
 › 1. Friendly (current)  Warm, collaborative, and helpful.
   2. Pragmatic           Concise, task-focused, and direct.
+  3. None                No personality - purely functional responses.
 
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