限制 DirectProject inline 附件数量

为 canonical 附件增加独立的八个条目上限。

补充超限附件拒绝测试，避免绕过素材引用数量门禁。

apps/ai-game-creator-shell/src-tauri/src/agent/direct_codex_user_item/validation.rs

@@ -4,6 +4,7 @@ use super::model::{
 };
 use crate::agent::{
     read_manifest_for_project, sanitize_attachment_local_path, GameCreationAppManifest,
+    MAX_DIRECT_CODEX_ATTACHMENTS,
 };
 use std::path::Path;
 
@@ -27,6 +28,7 @@ pub(crate) fn validate_direct_codex_user_item(
     }
     let manifest = read_manifest_for_project(root)?;
     let mut reference_count = 0usize;
+    let mut attachment_count = 0usize;
     for part in &message.content {
         match part {
             DirectCodexUserContentPart::InputText { .. } => {}
@@ -39,6 +41,12 @@ pub(crate) fn validate_direct_codex_user_item(
                 validate_runtime_region_reference(&manifest, reference)?;
             }
             DirectCodexUserContentPart::AgcAttachmentReference(reference) => {
+                attachment_count = attachment_count.saturating_add(1);
+                if attachment_count > MAX_DIRECT_CODEX_ATTACHMENTS {
+                    return Err(format!(
+                        "一次最多携带 {MAX_DIRECT_CODEX_ATTACHMENTS} 个附件"
+                    ));
+                }
                 if reference.name.trim().is_empty() {
                     return Err("附件缺少文件名".to_string());
                 }
@@ -107,8 +115,9 @@ fn validate_runtime_region_reference(
 
 #[cfg(test)]
 mod tests {
-    use super::content_has_meaningful_input;
+    use super::{content_has_meaningful_input, validate_direct_codex_user_item};
     use crate::agent::direct_codex_user_item::model::DirectCodexUserContentPart;
+    use serde_json::json;
 
     fn input_text(text: &str) -> DirectCodexUserContentPart {
         DirectCodexUserContentPart::InputText {
@@ -148,4 +157,33 @@ mod tests {
             },
         ]));
     }
+
+    #[test]
+    fn inline_attachment_count_is_bounded_independently() {
+        let root = tempfile::tempdir().expect("temp project");
+        crate::init_local_game_project_at(root.path(), "validation-test", "校验测试")
+            .expect("init project");
+        let content = (0..=crate::agent::MAX_DIRECT_CODEX_ATTACHMENTS)
+            .map(|index| {
+                json!({
+                    "type": "agc_attachment_reference",
+                    "name": format!("attachment-{index}.txt"),
+                    "mediaType": "text/plain",
+                    "size": 1,
+                    "localPath": "",
+                    "status": "failed"
+                })
+            })
+            .collect::<Vec<_>>();
+        let item = serde_json::from_value(json!({
+            "type": "message",
+            "role": "user",
+            "content": content,
+            "id": "turn-1:user"
+        }))
+        .expect("deserialize user item");
+        let error = validate_direct_codex_user_item(root.path(), &item)
+            .expect_err("too many inline attachments must be rejected");
+        assert!(error.contains("最多携带"), "{error}");
+    }
 }