diff --git a/codex-rs/core/src/context_manager/history_tests.rs b/codex-rs/core/src/context_manager/history_tests.rs
index fd9a4720bfa4..de8f69408911 100644
--- a/codex-rs/core/src/context_manager/history_tests.rs
+++ b/codex-rs/core/src/context_manager/history_tests.rs
@@ -1577,7 +1577,9 @@ fn normalize_adds_missing_output_for_function_call() {
             ResponseItem::FunctionCallOutput {
                 id: None,
                 call_id: "call-x".to_string(),
-                output: FunctionCallOutputPayload::from_text("aborted".to_string()),
+                output: FunctionCallOutputPayload::from_text(
+                    crate::context_manager::normalize::MISSING_OUTPUT_PLACEHOLDER.to_string()
+                ),
                 internal_chat_message_metadata_passthrough: None,
             },
         ]
@@ -1616,7 +1618,9 @@ fn normalize_adds_missing_output_for_custom_tool_call() {
                 id: None,
                 call_id: "tool-x".to_string(),
                 name: None,
-                output: FunctionCallOutputPayload::from_text("aborted".to_string()),
+                output: FunctionCallOutputPayload::from_text(
+                    crate::context_manager::normalize::MISSING_OUTPUT_PLACEHOLDER.to_string()
+                ),
                 internal_chat_message_metadata_passthrough: None,
             },
         ]
@@ -1662,7 +1666,9 @@ fn normalize_adds_missing_output_for_local_shell_call_with_id() {
             ResponseItem::FunctionCallOutput {
                 id: None,
                 call_id: "shell-1".to_string(),
-                output: FunctionCallOutputPayload::from_text("aborted".to_string()),
+                output: FunctionCallOutputPayload::from_text(
+                    crate::context_manager::normalize::MISSING_OUTPUT_PLACEHOLDER.to_string()
+                ),
                 internal_chat_message_metadata_passthrough: None,
             },
         ]
@@ -1767,7 +1773,9 @@ fn normalize_mixed_inserts_and_removals() {
             ResponseItem::FunctionCallOutput {
                 id: None,
                 call_id: "c1".to_string(),
-                output: FunctionCallOutputPayload::from_text("aborted".to_string()),
+                output: FunctionCallOutputPayload::from_text(
+                    crate::context_manager::normalize::MISSING_OUTPUT_PLACEHOLDER.to_string()
+                ),
                 internal_chat_message_metadata_passthrough: None,
             },
             ResponseItem::CustomToolCall {
@@ -1783,7 +1791,9 @@ fn normalize_mixed_inserts_and_removals() {
                 id: None,
                 call_id: "t1".to_string(),
                 name: None,
-                output: FunctionCallOutputPayload::from_text("aborted".to_string()),
+                output: FunctionCallOutputPayload::from_text(
+                    crate::context_manager::normalize::MISSING_OUTPUT_PLACEHOLDER.to_string()
+                ),
                 internal_chat_message_metadata_passthrough: None,
             },
             ResponseItem::LocalShellCall {
@@ -1802,7 +1812,9 @@ fn normalize_mixed_inserts_and_removals() {
             ResponseItem::FunctionCallOutput {
                 id: None,
                 call_id: "s1".to_string(),
-                output: FunctionCallOutputPayload::from_text("aborted".to_string()),
+                output: FunctionCallOutputPayload::from_text(
+                    crate::context_manager::normalize::MISSING_OUTPUT_PLACEHOLDER.to_string()
+                ),
                 internal_chat_message_metadata_passthrough: None,
             },
         ]
@@ -1837,7 +1849,9 @@ fn normalize_adds_missing_output_for_function_call_inserts_output() {
             ResponseItem::FunctionCallOutput {
                 id: None,
                 call_id: "call-x".to_string(),
-                output: FunctionCallOutputPayload::from_text("aborted".to_string()),
+                output: FunctionCallOutputPayload::from_text(
+                    crate::context_manager::normalize::MISSING_OUTPUT_PLACEHOLDER.to_string()
+                ),
                 internal_chat_message_metadata_passthrough: None,
             },
         ]
@@ -1954,7 +1968,10 @@ fn normalize_fills_missing_output_for_custom_tool_call() {
         );
     };
     assert_eq!(call_id, "tool-x");
-    assert_eq!(output.body.to_text().as_deref(), Some("aborted"));
+    assert_eq!(
+        output.body.to_text().as_deref(),
+        Some(crate::context_manager::normalize::MISSING_OUTPUT_PLACEHOLDER)
+    );
 }
 
 #[test]
diff --git a/codex-rs/core/src/context_manager/mod.rs b/codex-rs/core/src/context_manager/mod.rs
index f2bdd89c4167..f2973442765b 100644
--- a/codex-rs/core/src/context_manager/mod.rs
+++ b/codex-rs/core/src/context_manager/mod.rs
@@ -1,5 +1,5 @@
 mod history;
-mod normalize;
+pub(crate) mod normalize;
 pub(crate) mod updates;
 
 pub(crate) use history::ContextManager;
diff --git a/codex-rs/core/src/context_manager/normalize.rs b/codex-rs/core/src/context_manager/normalize.rs
index 0213f7d022c0..c7e08951dd88 100644
--- a/codex-rs/core/src/context_manager/normalize.rs
+++ b/codex-rs/core/src/context_manager/normalize.rs
@@ -18,6 +18,15 @@ const AUDIO_CONTENT_OMITTED_PLACEHOLDER: &str =
 // Changing this value would change model-visible IDs and invalidate prompt caches.
 const SYNTHETIC_OUTPUT_ID_NAMESPACE: Uuid = Uuid::from_u128(0x90d38d3e_6a5b_4d52_bfe2_2f1e634bfac4);
 
+/// Stands in for a tool call that never reported a result, so the payload stays well formed.
+///
+/// It says unknown rather than failed on purpose. The call is missing its result because
+/// something stopped between dispatch and the write, and neither an interrupt nor a crash can
+/// promise the command did not run first, so the model has to check before repeating it.
+pub(crate) const MISSING_OUTPUT_PLACEHOLDER: &str = "The outcome of this call is unknown: it started and no \
+     result was recorded. It may have taken effect. Check the current state before running it \
+     again.";
+
 /// Fill in the output of any tool call that never reported one.
 ///
 /// A gap here is expected, not a defect: an interrupt or a crash between dispatching a tool and
@@ -62,7 +71,9 @@ pub(crate) fn ensure_call_outputs_present(items: &mut Vec<ResponseItemEnvelope>)
                     ResponseItemEnvelope::new(ResponseItem::FunctionCallOutput {
                         id: synthetic_output_id("fco", id.as_deref()),
                         call_id: call_id.clone(),
-                        output: FunctionCallOutputPayload::from_text("aborted".to_string()),
+                        output: FunctionCallOutputPayload::from_text(
+                            MISSING_OUTPUT_PLACEHOLDER.to_string(),
+                        ),
                         internal_chat_message_metadata_passthrough: None,
                     }),
                 ));
@@ -95,7 +106,9 @@ pub(crate) fn ensure_call_outputs_present(items: &mut Vec<ResponseItemEnvelope>)
                         id: synthetic_output_id("ctco", id.as_deref()),
                         call_id: call_id.clone(),
                         name: None,
-                        output: FunctionCallOutputPayload::from_text("aborted".to_string()),
+                        output: FunctionCallOutputPayload::from_text(
+                            MISSING_OUTPUT_PLACEHOLDER.to_string(),
+                        ),
                         internal_chat_message_metadata_passthrough: None,
                     }),
                 ));
@@ -112,7 +125,9 @@ pub(crate) fn ensure_call_outputs_present(items: &mut Vec<ResponseItemEnvelope>)
                     ResponseItemEnvelope::new(ResponseItem::FunctionCallOutput {
                         id: synthetic_output_id("fco", id.as_deref()),
                         call_id: call_id.clone(),
-                        output: FunctionCallOutputPayload::from_text("aborted".to_string()),
+                        output: FunctionCallOutputPayload::from_text(
+                            MISSING_OUTPUT_PLACEHOLDER.to_string(),
+                        ),
                         internal_chat_message_metadata_passthrough: None,
                     }),
                 ));