diff --git a/codex-rs/app-server-protocol/schema/json/ServerNotification.json b/codex-rs/app-server-protocol/schema/json/ServerNotification.json
index 42d77bab17..3054610330 100644
--- a/codex-rs/app-server-protocol/schema/json/ServerNotification.json
+++ b/codex-rs/app-server-protocol/schema/json/ServerNotification.json
@@ -5427,6 +5427,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
index 3383756a7c..a0c7a30a13 100644
--- a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
+++ b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
@@ -23211,6 +23211,14 @@
                 ],
                 "default": null
               },
+              "generationId": {
+                "default": null,
+                "description": "Image generation identifier for the generated image, when provided by the image backend.",
+                "type": [
+                  "string",
+                  "null"
+                ]
+              },
               "id": {
                 "type": "string"
               },
diff --git a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
index e1355e2bf6..c35df0e580 100644
--- a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
+++ b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
@@ -20925,6 +20925,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ItemCompletedNotification.json b/codex-rs/app-server-protocol/schema/json/v2/ItemCompletedNotification.json
index a1a5a52866..692617e957 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ItemCompletedNotification.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ItemCompletedNotification.json
@@ -1580,6 +1580,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ItemStartedNotification.json b/codex-rs/app-server-protocol/schema/json/v2/ItemStartedNotification.json
index 29c048b1fd..286ce308fb 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ItemStartedNotification.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ItemStartedNotification.json
@@ -1580,6 +1580,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ReviewStartResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ReviewStartResponse.json
index 67299060ae..3654838385 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ReviewStartResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ReviewStartResponse.json
@@ -1785,6 +1785,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadForkResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadForkResponse.json
index fe4279c9e0..a025f8b78d 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadForkResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadForkResponse.json
@@ -2399,6 +2399,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadItemsListResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadItemsListResponse.json
index 9938cc5e54..eb54f49826 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadItemsListResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadItemsListResponse.json
@@ -1580,6 +1580,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadListResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadListResponse.json
index 0e5b3b2cd8..8446a6a4da 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadListResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadListResponse.json
@@ -2190,6 +2190,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadMetadataUpdateResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadMetadataUpdateResponse.json
index e77eb56829..d167771d36 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadMetadataUpdateResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadMetadataUpdateResponse.json
@@ -2190,6 +2190,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadReadResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadReadResponse.json
index 4530ff70cc..fffe7e206f 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadReadResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadReadResponse.json
@@ -2190,6 +2190,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadResumeResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadResumeResponse.json
index b834a9250b..baa806edcc 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadResumeResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadResumeResponse.json
@@ -2451,6 +2451,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadRevertResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadRevertResponse.json
index f790116ab6..b06f6b9efc 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadRevertResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadRevertResponse.json
@@ -2190,6 +2190,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadStartResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadStartResponse.json
index ab3eb956be..0e44e3042c 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadStartResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadStartResponse.json
@@ -2399,6 +2399,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadStartedNotification.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadStartedNotification.json
index cfe899e0d5..326694cf14 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadStartedNotification.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadStartedNotification.json
@@ -2190,6 +2190,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadTurnsListResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadTurnsListResponse.json
index ebb9d21a3c..74ef991588 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadTurnsListResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadTurnsListResponse.json
@@ -1785,6 +1785,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/ThreadUnarchiveResponse.json b/codex-rs/app-server-protocol/schema/json/v2/ThreadUnarchiveResponse.json
index ea8331cb1e..bcfd2f2571 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/ThreadUnarchiveResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/ThreadUnarchiveResponse.json
@@ -2190,6 +2190,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/TurnCompletedNotification.json b/codex-rs/app-server-protocol/schema/json/v2/TurnCompletedNotification.json
index 9180d12593..0c0cf075df 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/TurnCompletedNotification.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/TurnCompletedNotification.json
@@ -1785,6 +1785,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/TurnStartResponse.json b/codex-rs/app-server-protocol/schema/json/v2/TurnStartResponse.json
index f2ce9c0426..fbe2695c5d 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/TurnStartResponse.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/TurnStartResponse.json
@@ -1785,6 +1785,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/json/v2/TurnStartedNotification.json b/codex-rs/app-server-protocol/schema/json/v2/TurnStartedNotification.json
index 11ba5fd665..d4ba38ae89 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/TurnStartedNotification.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/TurnStartedNotification.json
@@ -1785,6 +1785,14 @@
               ],
               "default": null
             },
+            "generationId": {
+              "default": null,
+              "description": "Image generation identifier for the generated image, when provided by the image backend.",
+              "type": [
+                "string",
+                "null"
+              ]
+            },
             "id": {
               "type": "string"
             },
diff --git a/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-experimental.json.zst b/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-experimental.json.zst
index eb8ee98152..a5d97cda12 100644
Binary files a/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-experimental.json.zst and b/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-experimental.json.zst differ
diff --git a/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-stable.json.zst b/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-stable.json.zst
index 2b8e25fe9e..f57f363805 100644
Binary files a/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-stable.json.zst and b/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-stable.json.zst differ
diff --git a/codex-rs/app-server-protocol/schema/typescript/ImageGenerationItem.ts b/codex-rs/app-server-protocol/schema/typescript/ImageGenerationItem.ts
index 1dfe3aa120..e43fb2995c 100644
--- a/codex-rs/app-server-protocol/schema/typescript/ImageGenerationItem.ts
+++ b/codex-rs/app-server-protocol/schema/typescript/ImageGenerationItem.ts
@@ -9,4 +9,8 @@ export type ImageGenerationItem = { id: string, status: string, revisedPrompt: s
 /**
  * Observed local inputs for a completed generation, absent on older items.
  */
-inputImages?: Array<ImageGenerationInputImage>, } & ({ fileId: string, } | { result: string, });
+inputImages?: Array<ImageGenerationInputImage>,
+/**
+ * Image generation identifier for the generated image, when provided by the image backend.
+ */
+generationId: string | null, } & ({ fileId: string, } | { result: string, });
diff --git a/codex-rs/app-server-protocol/src/protocol/thread_history.rs b/codex-rs/app-server-protocol/src/protocol/thread_history.rs
index 337d12b556..b63b84895b 100644
--- a/codex-rs/app-server-protocol/src/protocol/thread_history.rs
+++ b/codex-rs/app-server-protocol/src/protocol/thread_history.rs
@@ -1043,7 +1043,7 @@ impl ThreadHistoryBuilder {
             saved_path: payload.saved_path.clone(),
             input_images: payload.input_images.clone(),
             imagegen_request_id: None,
-            generation_id: None,
+            generation_id: payload.generation_id.clone(),
         });
         self.upsert_item_in_current_turn(item);
     }
@@ -2929,6 +2929,7 @@ mod tests {
                     path: test_path_buf("/tmp/reference.png").abs(),
                     sha256: "ab".repeat(32),
                 }],
+                generation_id: None,
             })),
             RolloutItem::EventMsg(EventMsg::TurnComplete(TurnCompleteEvent {
                 root_turn_id: None,
diff --git a/codex-rs/app-server/tests/suite/v2/imagegen_extension.rs b/codex-rs/app-server/tests/suite/v2/imagegen_extension.rs
index a0792ae98a..1c1e332448 100644
--- a/codex-rs/app-server/tests/suite/v2/imagegen_extension.rs
+++ b/codex-rs/app-server/tests/suite/v2/imagegen_extension.rs
@@ -168,6 +168,7 @@ async fn standalone_image_generation_returns_saved_path_hint_to_model(
         image,
         transparent_background,
         saved_path: Some(saved_path),
+        generation_id,
         ..
     }) = completed.item.payload
     else {
@@ -175,6 +176,7 @@ async fn standalone_image_generation_returns_saved_path_hint_to_model(
     };
     assert_eq!(status, "completed");
     assert_eq!(revised_prompt.as_deref(), Some("paint a blue whale"));
+    assert_eq!(generation_id.as_deref(), Some("gen-image-123"));
     assert_eq!(
         image,
         GeneratedImageRef::Inline {
@@ -398,6 +400,10 @@ async fn transparent_image_preserves_output_metadata_and_persisted_history(
         })
         .context("persisted legacy history should contain the generated image")?;
     assert_eq!(persisted_image.transparent_background, Some(true));
+    assert_eq!(
+        persisted_image.generation_id.as_deref(),
+        Some("gen-transparent")
+    );
     assert_eq!(persisted_image.input_images, expected_inputs);
 
     let resume_id = resumed
@@ -418,6 +424,10 @@ async fn transparent_image_preserves_output_metadata_and_persisted_history(
         })
         .context("resumed legacy history should contain the generated image")?;
     assert_eq!(resumed_image.transparent_background, Some(true));
+    assert_eq!(
+        resumed_image.generation_id.as_deref(),
+        Some("gen-transparent")
+    );
     assert_eq!(resumed_image.input_images, expected_inputs);
 
     Ok(())
@@ -1255,7 +1265,7 @@ async fn mount_image_response_with_background(server: &MockServer, background: &
                 .set_body_json(json!({
                     "created": 1,
                     "background": background,
-                    "data": [{"b64_json": RESULT}],
+                    "data": [{"b64_json": RESULT, "generation_id": "gen-transparent"}],
                 })),
         )
         .expect(1)
@@ -1269,7 +1279,7 @@ async fn mount_image_edit_response(server: &MockServer) {
         .respond_with(ResponseTemplate::new(200).set_body_json(json!({
             "created": 1,
             "background": "transparent",
-            "data": [{"b64_json": RESULT}],
+            "data": [{"b64_json": RESULT, "generation_id": "gen-transparent"}],
         })))
         .expect(1)
         .mount(server)
diff --git a/codex-rs/app-server/tests/suite/v2/thread_resume.rs b/codex-rs/app-server/tests/suite/v2/thread_resume.rs
index 2b6946e164..a1f2dd3779 100644
--- a/codex-rs/app-server/tests/suite/v2/thread_resume.rs
+++ b/codex-rs/app-server/tests/suite/v2/thread_resume.rs
@@ -3099,6 +3099,7 @@ fn append_resume_redaction_history(
             failure: None,
             saved_path: Some(test_absolute_path("/tmp/ig-1.png")),
             input_images: Vec::new(),
+            generation_id: None,
         }),
     ]
     .into_iter()
diff --git a/codex-rs/core/src/tools/handlers/extension_tools.rs b/codex-rs/core/src/tools/handlers/extension_tools.rs
index a6cfe8fac9..fd2c47f821 100644
--- a/codex-rs/core/src/tools/handlers/extension_tools.rs
+++ b/codex-rs/core/src/tools/handlers/extension_tools.rs
@@ -660,6 +660,7 @@ mod tests {
                     failure: None,
                     saved_path: Some(expected_path.clone()),
                     input_images: Vec::new(),
+                    generation_id: None,
                 })],
             },
         )
diff --git a/codex-rs/ext/image-generation/src/tool.rs b/codex-rs/ext/image-generation/src/tool.rs
index 26f3badf3d..b0f9848835 100644
--- a/codex-rs/ext/image-generation/src/tool.rs
+++ b/codex-rs/ext/image-generation/src/tool.rs
@@ -114,6 +114,7 @@ fn legacy_end_event(item: &ImageGenerationItem) -> EventMsg {
         failure: item.failure.clone(),
         saved_path: item.saved_path.clone(),
         input_images: item.input_images.clone(),
+        generation_id: item.generation_id.clone(),
     })
 }
 
diff --git a/codex-rs/ext/items/src/image_generation.rs b/codex-rs/ext/items/src/image_generation.rs
index 59d4ece0b7..9f0ea1f403 100644
--- a/codex-rs/ext/items/src/image_generation.rs
+++ b/codex-rs/ext/items/src/image_generation.rs
@@ -61,10 +61,8 @@ pub struct ImageGenerationItem {
     #[schemars(skip)]
     #[ts(skip)]
     pub imagegen_request_id: Option<String>,
-    /// Backend generation ID for this exact image, retained only for in-process analytics.
-    #[serde(skip)]
-    #[schemars(skip)]
-    #[ts(skip)]
+    /// Image generation identifier for the generated image, when provided by the image backend.
+    #[serde(default)]
     pub generation_id: Option<String>,
 }
 
diff --git a/codex-rs/ext/items/src/tests.rs b/codex-rs/ext/items/src/tests.rs
index ca26d9a581..c2f18b47f4 100644
--- a/codex-rs/ext/items/src/tests.rs
+++ b/codex-rs/ext/items/src/tests.rs
@@ -43,6 +43,7 @@ fn image_generation_item_preserves_stable_wire_shape() {
             "result": "cG5n",
             "transparentBackground": null,
             "failure": null,
+            "generationId": null,
         })
     );
     assert_eq!(
@@ -126,6 +127,7 @@ fn image_generation_item_reads_transitional_file_wire_shape() {
             "fileId": "file-1",
             "transparentBackground": null,
             "failure": null,
+            "generationId": null,
         })
     );
 }
@@ -173,6 +175,7 @@ fn image_generation_item_preserves_authoritative_transparency() {
             "result": "cG5n",
             "transparentBackground": true,
             "failure": null,
+            "generationId": null,
         })
     );
     assert_eq!(
@@ -205,16 +208,19 @@ fn image_generation_request_id_stays_internal() {
     let value = serde_json::to_value(&item).expect("serialize extension item");
 
     assert!(value.get("imagegenRequestId").is_none());
-    assert!(value.get("generationId").is_none());
+    assert_eq!(value["generationId"], json!("gen-image-123"));
     let ExtensionItem::ImageGeneration(round_tripped) =
         serde_json::from_value::<ExtensionItem>(value).expect("deserialize extension item")
     else {
         panic!("expected image-generation item");
     };
     assert_eq!(round_tripped.imagegen_request_id, None);
-    assert_eq!(round_tripped.generation_id, None);
+    assert_eq!(
+        round_tripped.generation_id.as_deref(),
+        Some("gen-image-123")
+    );
     assert!(!ImageGenerationItem::inline().contains("imagegenRequestId"));
-    assert!(!ImageGenerationItem::inline().contains("generationId"));
+    assert!(ImageGenerationItem::inline().contains("generationId: string | null"));
 }
 
 #[test]
diff --git a/codex-rs/protocol/src/legacy_events.rs b/codex-rs/protocol/src/legacy_events.rs
index 3a04fdaec7..a0372c54f8 100644
--- a/codex-rs/protocol/src/legacy_events.rs
+++ b/codex-rs/protocol/src/legacy_events.rs
@@ -471,6 +471,7 @@ impl ImageGenerationItem {
             failure: None,
             saved_path: self.saved_path.clone(),
             input_images: Vec::new(),
+            generation_id: None,
         })
     }
 }
diff --git a/codex-rs/protocol/src/protocol.rs b/codex-rs/protocol/src/protocol.rs
index 3c79cb98ae..696549842a 100644
--- a/codex-rs/protocol/src/protocol.rs
+++ b/codex-rs/protocol/src/protocol.rs
@@ -3035,6 +3035,9 @@ pub struct ImageGenerationEndEvent {
     #[serde(default, skip_serializing_if = "Vec::is_empty")]
     #[ts(as = "Option<_>", optional)]
     pub input_images: Vec<ImageGenerationInputImage>,
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    #[ts(optional)]
+    pub generation_id: Option<String>,
 }
 
 // Conversation kept for backward compatibility.
diff --git a/codex-rs/rollout/src/policy_tests.rs b/codex-rs/rollout/src/policy_tests.rs
index 63f87b1d09..87a7cf8e60 100644
--- a/codex-rs/rollout/src/policy_tests.rs
+++ b/codex-rs/rollout/src/policy_tests.rs
@@ -69,6 +69,7 @@ fn legacy_image_generation_preserves_file_reference() {
         failure: None,
         saved_path: None,
         input_images: Vec::new(),
+        generation_id: None,
     });
 
     let persisted = persisted_event_msg(&event, ThreadHistoryMode::Legacy)
diff --git a/codex-rs/thread-store/src/local/rollout_migration/legacy_event.rs b/codex-rs/thread-store/src/local/rollout_migration/legacy_event.rs
index a90417c6c2..4625d152be 100644
--- a/codex-rs/thread-store/src/local/rollout_migration/legacy_event.rs
+++ b/codex-rs/thread-store/src/local/rollout_migration/legacy_event.rs
@@ -223,7 +223,7 @@ pub(super) fn completed_item(
                 saved_path: event.saved_path.clone(),
                 input_images: event.input_images.clone(),
                 imagegen_request_id: None,
-                generation_id: None,
+                generation_id: event.generation_id.clone(),
             })),
             None,
         )),
diff --git a/codex-rs/thread-store/src/local/rollout_migration_tests.rs b/codex-rs/thread-store/src/local/rollout_migration_tests.rs
index a609981196..7eb881a8d4 100644
--- a/codex-rs/thread-store/src/local/rollout_migration_tests.rs
+++ b/codex-rs/thread-store/src/local/rollout_migration_tests.rs
@@ -558,6 +558,7 @@ async fn migration_preserves_image_generation_failure_metadata() {
             failure: expected_item.failure.clone(),
             saved_path: expected_item.saved_path.clone(),
             input_images: Vec::new(),
+            generation_id: expected_item.generation_id.clone(),
         }));
     let path = write_rollout(
         home.path(),
@@ -609,7 +610,7 @@ async fn migration_preserves_image_generation_input_observations() {
             sha256: "ab".repeat(32),
         }],
         imagegen_request_id: None,
-        generation_id: None,
+        generation_id: Some("gen-image-123".to_string()),
     };
     let image_completion =
         RolloutItem::EventMsg(EventMsg::ImageGenerationEnd(ImageGenerationEndEvent {
@@ -621,6 +622,7 @@ async fn migration_preserves_image_generation_input_observations() {
             failure: expected_item.failure.clone(),
             saved_path: expected_item.saved_path.clone(),
             input_images: expected_item.input_images.clone(),
+            generation_id: expected_item.generation_id.clone(),
         }));
     let path = write_rollout(
         home.path(),
diff --git a/sdk/python/src/openai_codex/generated/v2_all.py b/sdk/python/src/openai_codex/generated/v2_all.py
index 2afe8d7cc8..0176b9f852 100644
--- a/sdk/python/src/openai_codex/generated/v2_all.py
+++ b/sdk/python/src/openai_codex/generated/v2_all.py
@@ -5558,6 +5558,13 @@ class FileIdThreadItem(BaseModel):
         ),
     ] = None
     failure: ImageGenerationFailure | None = None
+    generation_id: Annotated[
+        str | None,
+        Field(
+            alias="generationId",
+            description="Image generation identifier for the generated image, when provided by the image backend.",
+        ),
+    ] = None
     id: str
     input_images: Annotated[
         list[ImageGenerationInputImage] | None,
@@ -5593,6 +5600,13 @@ class ResultThreadItem(BaseModel):
         ),
     ] = None
     failure: ImageGenerationFailure | None = None
+    generation_id: Annotated[
+        str | None,
+        Field(
+            alias="generationId",
+            description="Image generation identifier for the generated image, when provided by the image backend.",
+        ),
+    ] = None
     id: str
     input_images: Annotated[
         list[ImageGenerationInputImage] | None,