共享的 project.jsonl 让两条对话链互读对方的行，混合历史不再双向失败关闭

- project/conversation.rs：read_persisted_local_conversation_records_unlocked 跳过 type=response_item 且带 payload 的行（DirectProject 写给同一份「项目主对话」的行），其余解析失败仍按「解析对话记录失败」失败关闭
- 新增 is_direct_project_history_row 做行信封白名单，只认对方那一种明确枚举的形状，不放宽成「什么都跳过」
- 不把 response_item 行二次投影成 LocalConversationMessageRecord：DirectProject 侧已经拥有那份 Responses item → 聊天内容的投影，再造一份平行投影会与它漂移
- 不加「文件已属于 DirectProject 就拒绝追加旧行」的硬报错：runtime_driver/task_start.rs 在 ensure_..._accepted_public_status_at 返回 Err 时会中止后台任务（「后台任务启动确认落盘失败，任务未执行」），runtime_protocol/steering.rs:572/604/1300 也用 ? 上抛，加硬报错会把旧行噪声换成任务起不来；毒化本身已由读侧白名单堵住
- 补断言：混合文件里通用链只读自己的 legacy 行且坏行仍失败关闭、混合文件从两条链都能读（DirectProject 把两种行都读出来）、纯旧格式文件的写入行为不变

apps/ai-game-creator-shell/src-tauri/src/project/conversation.rs

@@ -958,8 +958,19 @@ fn read_persisted_local_conversation_records_unlocked(
                 if line.is_empty() {
                     continue;
                 }
-                let record = serde_json::from_str::<PersistedLocalConversationMessageRecord>(line)
-                    .map_err(|error| format!("解析对话记录失败：{}: {error}", path.display()))?;
+                let record = match serde_json::from_str::<PersistedLocalConversationMessageRecord>(
+                    line,
+                ) {
+                    Ok(record) => record,
+                    // 项目主对话（agent_id=None）与 DirectProject 共用同一份
+                    // `project.jsonl`：DirectProject 写的是 Codex rollout 的
+                    // `response_item` 行。通用对话链只认自己的 legacy 行，遇到对方那种
+                    // 行就跳过；其余任何坏行继续失败关闭。
+                    Err(_) if is_direct_project_history_row(line) => continue,
+                    Err(error) => {
+                        return Err(format!("解析对话记录失败：{}: {error}", path.display()))
+                    }
+                };
                 records.push(record);
             }
         }
@@ -969,6 +980,15 @@ fn read_persisted_local_conversation_records_unlocked(
     Ok(records)
 }
 
+/// 只认 DirectProject 那一种明确枚举的行信封：`type=response_item` 且带 `payload`。
+/// 其余任何形状都不算“对方的行”，仍由上方按坏行失败关闭。
+fn is_direct_project_history_row(line: &str) -> bool {
+    serde_json::from_str::<serde_json::Value>(line).is_ok_and(|parsed| {
+        parsed.get("type").and_then(serde_json::Value::as_str) == Some("response_item")
+            && parsed.get("payload").is_some()
+    })
+}
+
 fn persisted_local_conversation_message_index_by_id(
     records: &[PersistedLocalConversationMessageRecord],
     expected_agent_id: Option<&str>,

apps/ai-game-creator-shell/src-tauri/src/project/conversation/tests.rs

@@ -225,3 +225,114 @@ fn finalization_conversation_retry_rejects_conflicting_audit_payload() {
 
     std::fs::remove_dir_all(root).ok();
 }
+
+const DIRECT_PROJECT_ROW: &str = r#"{"type":"response_item","payload":{"type":"message","role":"user","id":"codex-item-1","content":[{"type":"input_text","text":"再加一个按钮"}]}}"#;
+const LEGACY_PROJECT_ROW: &str = r#"{"schemaVersion":"game-creator-conversation.v1","role":"assistant","content":"已创建菜单","agentId":null,"updatedAt":1757000000}"#;
+
+fn project_conversation_path(root: &Path) -> PathBuf {
+    root.join(".agent/conversations/project.jsonl")
+}
+
+fn write_project_history(root: &Path, lines: &[&str]) {
+    let path = project_conversation_path(root);
+    std::fs::create_dir_all(path.parent().expect("history parent")).expect("history dir");
+    std::fs::write(&path, format!("{}\n", lines.join("\n"))).expect("write project history");
+}
+
+fn append_project_message(root: &Path, content: &str) -> Result<LocalConversationResult, String> {
+    append_local_conversation_message_at(
+        root,
+        None,
+        LocalConversationMessage {
+            role: "assistant".to_string(),
+            content: content.to_string(),
+            agent_id: None,
+        },
+    )
+}
+
+#[test]
+fn project_history_skips_direct_project_rows_but_keeps_other_broken_rows_failing_closed() {
+    let root = unique_conversation_test_root();
+    init_local_game_project_at(&root, "project-1", "混合行形状读取测试").expect("init project");
+    write_project_history(&root, &[DIRECT_PROJECT_ROW, LEGACY_PROJECT_ROW]);
+
+    let conversation =
+        read_local_conversation_at(&root, None).expect("read mixed project conversation");
+    assert_eq!(conversation.messages.len(), 1);
+    assert_eq!(conversation.messages[0].role, "assistant");
+    assert_eq!(conversation.messages[0].content, "已创建菜单");
+
+    write_project_history(&root, &[LEGACY_PROJECT_ROW, r#"{"unexpected":true}"#]);
+    let error = read_local_conversation_at(&root, None)
+        .expect_err("unrecognized row must keep failing closed");
+    assert!(error.starts_with("解析对话记录失败"), "{error}");
+
+    std::fs::remove_dir_all(root).ok();
+}
+
+#[test]
+fn mixed_project_history_rows_stay_readable_from_both_sides() {
+    let root = unique_conversation_test_root();
+    init_local_game_project_at(&root, "project-1", "写侧统一测试").expect("init project");
+    write_project_history(&root, &[DIRECT_PROJECT_ROW]);
+
+    append_project_message(&root, "模式切换后由通用写入器补写的回复").expect("append legacy row");
+    append_local_conversation_message_for_session_idempotent_at(
+        &root,
+        None,
+        None,
+        LocalConversationMessage {
+            role: "assistant".to_string(),
+            content: "带 id 的旧格式回复".to_string(),
+            agent_id: None,
+        },
+        "direct-codex:turn-0002:assistant",
+    )
+    .expect("append id-bearing legacy row");
+
+    let history = std::fs::read_to_string(project_conversation_path(&root)).expect("read history");
+    assert_eq!(history.lines().count(), 3, "{history}");
+    assert!(history.contains("模式切换后由通用写入器补写的回复"), "{history}");
+
+    // 通用对话链只读自己的 legacy 行，跳过 DirectProject 的行。
+    let conversation = read_local_conversation_at(&root, None).expect("read project conversation");
+    assert_eq!(
+        conversation
+            .messages
+            .iter()
+            .map(|message| message.content.as_str())
+            .collect::<Vec<_>>(),
+        vec!["模式切换后由通用写入器补写的回复", "带 id 的旧格式回复"]
+    );
+
+    // 反向：DirectProject 链把同一份文件里的两种行都读出来，混合文件不构成毒化。
+    let direct_items = crate::agent::read_direct_project_history_items_at(&root)
+        .expect("DirectProject must keep reading the mixed history");
+    assert_eq!(
+        direct_items
+            .iter()
+            .map(|item| item["content"][0]["text"].as_str().unwrap_or_default())
+            .collect::<Vec<_>>(),
+        vec![
+            "再加一个按钮",
+            "模式切换后由通用写入器补写的回复",
+            "带 id 的旧格式回复",
+        ]
+    );
+
+    std::fs::remove_dir_all(root).ok();
+}
+
+#[test]
+fn project_history_keeps_accepting_legacy_rows_while_no_direct_project_row_exists() {
+    let root = unique_conversation_test_root();
+    init_local_game_project_at(&root, "project-1", "纯旧格式项目写入测试").expect("init project");
+
+    append_project_message(&root, "非 direct 模式的项目对话回复").expect("append legacy row");
+    let conversation = read_local_conversation_at(&root, None).expect("read legacy conversation");
+    assert_eq!(conversation.messages.len(), 1);
+    assert_eq!(conversation.messages[0].content, "非 direct 模式的项目对话回复");
+
+    std::fs::remove_dir_all(root).ok();
+}