diff --git a/apps/ai-game-creator-shell/src-tauri/src/agent/runtime_actions/provider_tool_plan.rs b/apps/ai-game-creator-shell/src-tauri/src/agent/runtime_actions/provider_tool_plan.rs
index 1aee4b4ef..3db3cb2e1 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/agent/runtime_actions/provider_tool_plan.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/agent/runtime_actions/provider_tool_plan.rs
@@ -140,6 +140,32 @@ fn root_goal_contract_repair_instruction(protocol_error: &str, plan_root: bool)
     }
 }
 
+/// 把上游的终态标记夹紧成可落审计的短标记。
+///
+/// tool-plan 这条链路此前把 finish_reason 整个丢掉了：真撞上 max_output_tokens 时，
+/// platform-llm 只会在**存在工具调用**且上游明确给出未完成终态时拒收，其余情形一律
+/// 当作可用的降级结果放行，而这一层既不看也不记，审计里没有任何东西能把「上游说这
+/// 一轮没写完」和「模型自己写歪了」分开。信封退化的现场排查就卡在这里。
+///
+/// 只记录，不改判：是否因未完成终态拒收仍旧由 platform-llm 决定，做游戏与做素材的
+/// 行为逐字不变。
+fn agent_runtime_tool_plan_audit_finish_reason(finish_reason: Option<&str>) -> Option<String> {
+    // 兼容网关常发自定义值甚至整段文案，所以按固定字符集丢弃而不是原样透传。
+    let reason = finish_reason?
+        .trim()
+        .to_ascii_lowercase()
+        .chars()
+        .filter(|character| {
+            character.is_ascii_lowercase()
+                || character.is_ascii_digit()
+                || *character == '_'
+                || *character == '-'
+        })
+        .take(32)
+        .collect::<String>();
+    (!reason.is_empty()).then_some(reason)
+}
+
 pub(in crate::agent) fn append_game_creator_agent_tool_plan_audit_idempotent(
     root: &Path,
     record: serde_json::Value,
@@ -873,6 +899,9 @@ pub(in crate::agent) async fn request_game_creator_agent_background_tool_plan_at
                         "responseFingerprint": response_fingerprint,
                         "providerRequestIdSha256": provider_request_id_sha256,
                         "protocol": protocol,
+                        "finishReason": agent_runtime_tool_plan_audit_finish_reason(
+                            response.finish_reason.as_deref(),
+                        ),
                         "functionCallCount": call_ids.len(),
                         "callIdSha256s": call_id_sha256s,
                         "functionNames": function_names,
@@ -1380,6 +1409,44 @@ pub(crate) async fn request_game_creator_agent_background_tool_plan_for_test(
     }
 }
 
+#[cfg(test)]
+mod tool_plan_audit_finish_reason_tests {
+    use super::*;
+
+    /// 正常终态原样落库，缺失记 null——这两个值就是「上游到底说没说这一轮写完了」
+    /// 的全部答案，此前审计里一个都没有。
+    #[test]
+    fn ordinary_finish_reasons_are_recorded_and_absence_stays_null() {
+        assert_eq!(
+            agent_runtime_tool_plan_audit_finish_reason(Some("completed")).as_deref(),
+            Some("completed")
+        );
+        assert_eq!(
+            agent_runtime_tool_plan_audit_finish_reason(Some("  INCOMPLETE  ")).as_deref(),
+            Some("incomplete")
+        );
+        assert_eq!(agent_runtime_tool_plan_audit_finish_reason(None), None);
+        assert_eq!(agent_runtime_tool_plan_audit_finish_reason(Some("   ")), None);
+    }
+
+    /// 兼容网关会在这个字段里发自定义值甚至整段文案。审计不是转发通道：越界字符
+    /// 一律丢弃，长度夹到 32，夹空了记 null，绝不原样透传。
+    #[test]
+    fn gateway_freeform_reasons_are_clamped_rather_than_relayed() {
+        assert_eq!(
+            agent_runtime_tool_plan_audit_finish_reason(Some("上游异常：截断了")),
+            None
+        );
+        assert_eq!(
+            agent_runtime_tool_plan_audit_finish_reason(Some("stop\n\"};DROP")).as_deref(),
+            Some("stopdrop")
+        );
+        let clamped = agent_runtime_tool_plan_audit_finish_reason(Some(&"a".repeat(200)))
+            .expect("a long ascii reason is still recorded");
+        assert_eq!(clamped.chars().count(), 32);
+    }
+}
+
 #[cfg(test)]
 mod supervisor_collaboration_repair_tests {
     use super::*;
diff --git a/apps/ai-game-creator-shell/src-tauri/src/project/agent_db.rs b/apps/ai-game-creator-shell/src-tauri/src/project/agent_db.rs
index 83cdedd19..39868c2f5 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/project/agent_db.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/project/agent_db.rs
@@ -2138,6 +2138,7 @@ pub(crate) fn append_agent_db_tool_plan_audit_idempotent(
         "responseFingerprint",
         "providerRequestIdSha256",
         "protocol",
+        "finishReason",
         "functionCallCount",
         "callIdSha256s",
         "functionNames",
@@ -2264,6 +2265,31 @@ pub(crate) fn append_agent_db_tool_plan_audit_idempotent(
                     return Err(format!("Agent DB tool-plan 幂等审计字段无效：{field}"));
                 }
             }
+            // Provider 终态标记是上游自由文本（兼容网关常发自定义值），写入侧已夹紧成
+            // 固定字符集的短标记；这里只复核夹紧结果，不接受原样透传的自由文本。
+            match record.get("finishReason") {
+                Some(serde_json::Value::Null) => {}
+                Some(serde_json::Value::String(value)) => {
+                    if value.is_empty()
+                        || value.chars().count() > 32
+                        || !value
+                            .chars()
+                            .all(|character| {
+                                character.is_ascii_lowercase()
+                                    || character.is_ascii_digit()
+                                    || character == '_'
+                                    || character == '-'
+                            })
+                    {
+                        return Err(
+                            "Agent DB tool-plan 幂等审计字段无效：finishReason".to_string()
+                        );
+                    }
+                }
+                _ => {
+                    return Err("Agent DB tool-plan 幂等审计字段无效：finishReason".to_string());
+                }
+            }
             let autonomous_source_payload_validated = record
                 .get("autonomousSourcePayloadValidated")
                 .and_then(serde_json::Value::as_bool)
diff --git a/apps/ai-game-creator-shell/src-tauri/src/project/agent_db/security_tests.rs b/apps/ai-game-creator-shell/src-tauri/src/project/agent_db/security_tests.rs
index cd6314dc6..c7aa53808 100644
--- a/apps/ai-game-creator-shell/src-tauri/src/project/agent_db/security_tests.rs
+++ b/apps/ai-game-creator-shell/src-tauri/src/project/agent_db/security_tests.rs
@@ -52,6 +52,7 @@ fn tool_plan_protocol_audit_record(
         "responseFingerprint": "1".repeat(64),
         "providerRequestIdSha256": "2".repeat(64),
         "protocol": "native_runtime_tools",
+        "finishReason": "completed",
         "functionCallCount": 0,
         "callIdSha256s": [],
         "functionNames": [],