feat(ai): 双通道输出解析器 — 文本/JSON 分割 + 降级策略

- parse_dual_channel: 分割 ===PATIENT_TEXT=== / ===STRUCTURED_JSON=== 标记
- JSON 解析失败时降级为纯文本，structured 为 None
- 5 个单元测试覆盖：正常解析、纯文本、无效 JSON、空建议、风险等级

crates/erp-ai/src/service/mod.rs

@@ -1,4 +1,5 @@
 pub mod analysis;
 pub mod auto_analysis;
+pub mod output_parser;
 pub mod prompt;
 pub mod usage;

crates/erp-ai/src/service/output_parser.rs

@@ -0,0 +1,82 @@
+use crate::dto::suggestion::{ParsedOutput, StructuredOutput};
+use crate::error::AiResult;
+
+const TEXT_MARKER: &str = "===PATIENT_TEXT===";
+const JSON_MARKER: &str = "===STRUCTURED_JSON===";
+
+/// 解析 AI 双通道输出。JSON 解析失败时降级为纯文本。
+pub fn parse_dual_channel(raw: &str) -> AiResult<ParsedOutput> {
+    let text_content = extract_section(raw, TEXT_MARKER, JSON_MARKER)
+        .unwrap_or(raw)
+        .trim()
+        .to_string();
+
+    let structured = extract_section(raw, JSON_MARKER, TEXT_MARKER)
+        .and_then(|json_str| {
+            let parsed: Result<StructuredOutput, _> = serde_json::from_str(json_str.trim());
+            parsed.ok()
+        });
+
+    Ok(ParsedOutput {
+        text_content,
+        structured,
+    })
+}
+
+fn extract_section<'a>(raw: &'a str, start: &str, end: &str) -> Option<&'a str> {
+    let start_idx = raw.find(start)?;
+    let content_start = start_idx + start.len();
+    let content_end = raw[content_start..]
+        .find(end)
+        .map(|i| content_start + i)
+        .unwrap_or(raw.len());
+    Some(&raw[content_start..content_end])
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::dto::suggestion::RiskLevel;
+
+    #[test]
+    fn parse_dual_channel_output_success() {
+        let raw = "===PATIENT_TEXT===\n张三的收缩压呈上升趋势\n===STRUCTURED_JSON===\n{\"risk_level\":\"medium\",\"risk_factors\":[\"收缩压偏高\"],\"suggestions\":[{\"type\":\"followup\",\"priority\":1,\"timing\":\"14天内\",\"reason\":\"血压异常\",\"params\":{},\"auto_executable\":false}],\"baseline_summary\":{}}";
+        let result = parse_dual_channel(raw).unwrap();
+        assert_eq!(result.text_content, "张三的收缩压呈上升趋势");
+        assert!(result.structured.is_some());
+        let s = result.structured.unwrap();
+        assert_eq!(s.risk_level, RiskLevel::Medium);
+        assert_eq!(s.suggestions.len(), 1);
+    }
+
+    #[test]
+    fn parse_text_only_fallback() {
+        let raw = "纯文本分析结果，没有结构化部分";
+        let result = parse_dual_channel(raw).unwrap();
+        assert_eq!(result.text_content, "纯文本分析结果，没有结构化部分");
+        assert!(result.structured.is_none());
+    }
+
+    #[test]
+    fn parse_invalid_json_falls_back() {
+        let raw = "===PATIENT_TEXT===\n分析内容\n===STRUCTURED_JSON===\n{invalid json}";
+        let result = parse_dual_channel(raw).unwrap();
+        assert_eq!(result.text_content, "分析内容");
+        assert!(result.structured.is_none());
+    }
+
+    #[test]
+    fn empty_suggestions_is_valid() {
+        let raw = "===PATIENT_TEXT===\n指标正常\n===STRUCTURED_JSON===\n{\"risk_level\":\"low\",\"risk_factors\":[],\"suggestions\":[],\"baseline_summary\":{}}";
+        let result = parse_dual_channel(raw).unwrap();
+        let s = result.structured.unwrap();
+        assert!(s.suggestions.is_empty());
+    }
+
+    #[test]
+    fn risk_level_auto_executable() {
+        assert!(RiskLevel::Low.is_auto_executable());
+        assert!(!RiskLevel::Medium.is_auto_executable());
+        assert!(!RiskLevel::High.is_auto_executable());
+    }
+}