diff --git a/research-wiki/designs/response-observability-fields.md b/research-wiki/designs/response-observability-fields.md
new file mode 100644
index 0000000..60af3c6
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+++ b/research-wiki/designs/response-observability-fields.md
@@ -0,0 +1,40 @@
+---
+type: design
+node_id: design:response-observability-fields
+title: "响应可观测字段扩展(Issue #3)"
+date: 2026-07-31
+---
+
+# 响应可观测字段扩展(Issue #3)
+
+全文见 `2026-07-31-response-observability-fields-design.md`。来源: Gitea Issue #3(下游 dissect 的调用审计需求)。
+
+## 选定方案
+
+| 决策 | 选定 | 关键理由 |
+|---|---|---|
+| A 采集路径 | `TransportResult` 追加 `cached_prompt_tokens` / `model_reported` 强类型字段,解析留在 `openai_compat.py` | OpenAI 报文格式知识不出 `transports/`,middleware 只做搬运(P7) |
+| B 缓存命中语义 | 原样回放;度量口径必须带 `cache_hit = false` | 与 `_rehydrate` 既有口径一致——它只覆写时序字段,`model`/`prompt_tokens` 全回放 |
+| C 缓存单价 | `ModelPrice` 加可选 `cached_input_per_1m`,`cost()` 加可选参 | 旧价格表与 `embedding.py:419` 三参调用零改动;未配置该档时**不猜折扣率**,退化为全额计价 |
+| D 遥测扩列 | 端口 18 → 20 字段;DDL 加列 + 初始化期幂等补列 | `CREATE TABLE IF NOT EXISTS` 不会给旧库补列,INSERT 会**逐行 warning 丢弃**——遥测全失却无硬失败提示 |
+
+## 被否决的备选
+
+| 备选 | 否决原因 |
+|---|---|
+| A1 往 `raw` 里塞约定键 | `dict[str, Any]` 沦为隐式契约,且 middleware 要懂 OpenAI 嵌套结构 |
+| A3 middleware 内解析 raw | 报文格式知识进 middleware,新增非 OpenAI 兼容 transport 时会分叉,违反分层 |
+| B2 命中时置 None / B3 混合 | 与同层 `prompt_tokens` 的回放行为不一致,下游要记两套规则 |
+| C2 `cost()` 直接收 `LLMResponse` | `pricing.py` 会反向依赖 `types.py`,且纯函数难单测 |
+| D2 只改 DDL、文档写「删表重建」 | 已建表的开发机/下游只会看到降级 warning,排查成本高 |
+| D3 引入 alembic 迁移框架 | 新增依赖违反「依赖极简」铁律,规模严重不匹配 |
+
+## 独立审查修正(2026-07-31)
+
+Codex CLI 安装损坏(vendor 二进制缺失),改由全新上下文的 Claude subagent 审。三条问题全部核实属实并已折回设计:
+
+1. PG 缺列时**不是**结构性短路,而是逐行 warning(`_failed` 仅在 `_ensure_ready` 置位)。
+2. SQLite 补列若塞进 `__init__` 现有 try,异常会让 `_conn` 停在 `None` → recorder 永久 no-op。已定纪律: 独立 try、置于 `self._conn = conn` 之后、duplicate column 视为成功。
+3. 「端口无默认值 → 漏改即报错」不成立(无 mypy,8 个 fake 全是 `**fields`)。改为新增「emitter 实参键集合 == `_COLUMNS`」契约测试兜底——否则 `KeyError` 会被 `_record` 的 `except Exception` 吞成 warning,静默丢遥测。
+
+相关: [[m1-core-design]]、[[est-tokens-decoupling]]
diff --git a/research-wiki/graph/edges.json b/research-wiki/graph/edges.json
index d1e7faf..4763fce 100644
--- a/research-wiki/graph/edges.json
+++ b/research-wiki/graph/edges.json
@@ -110,6 +110,11 @@
       "id": "plan:est-tokens-decoupling",
       "label": "est_tokens 解耦实施计划",
       "type": "plan"
+    },
+    {
+      "id": "design:response-observability-fields",
+      "label": "响应可观测字段扩展(Issue #3)",
+      "type": "design"
     }
   ],
   "links": [
diff --git a/research-wiki/index.md b/research-wiki/index.md
index ab36d16..d250a69 100644
--- a/research-wiki/index.md
+++ b/research-wiki/index.md
@@ -1,8 +1,8 @@
 # Research Wiki 索引
 
-> 自动生成，更新时间：2026-07-30 09:39 UTC
+> 自动生成，更新时间：2026-07-31 08:37 UTC
 
-## design (16)
+## design (18)
 - [2026-07-20-m1-core-design](designs/2026-07-20-m1-core-design.md) `design:2026-07-20-m1-core-design`
 - [2026-07-20-m2-distributed-design](designs/2026-07-20-m2-distributed-design.md) `design:2026-07-20-m2-distributed-design`
 - [2026-07-21-m25-resilience-design](designs/2026-07-21-m25-resilience-design.md) `design:2026-07-21-m25-resilience-design`
@@ -11,6 +11,7 @@
 - [2026-07-29-settings-invariant-guards-design](designs/2026-07-29-settings-invariant-guards-design.md) `design:2026-07-29-settings-invariant-guards-design`
 - [2026-07-30-est-tokens-decoupling-design](designs/2026-07-30-est-tokens-decoupling-design.md) `design:2026-07-30-est-tokens-decoupling-design`
 - [2026-07-30-settings-invariants-round-2-design](designs/2026-07-30-settings-invariants-round-2-design.md) `design:2026-07-30-settings-invariants-round-2-design`
+- [2026-07-31-response-observability-fields-design](designs/2026-07-31-response-observability-fields-design.md) `design:2026-07-31-response-observability-fields-design`
 - [est_tokens 解耦: 拆分限流预扣与遥测用量兜底(issue #2)](designs/est-tokens-decoupling.md) `design:est-tokens-decoupling`
 - [GatewaySettings 装配校验补齐(第二轮)](designs/settings-invariants-round-2.md) `design:settings-invariants-round-2`
 - [GatewaySettings 跨字段不变量守卫的生效范围](designs/settings-invariant-guards.md) `design:settings-invariant-guards`
@@ -19,6 +20,7 @@
 - [M2.5 治理韧性: 半死源隔离与健康感知调度](designs/m25-resilience.md) `design:m25-resilience`
 - [M3 OCR 端口族设计](designs/m3-ocr.md) `design:m3-ocr`
 - [M4 迁移验证设计(GovDoc→CHS,发 v1.0)](designs/m4-migration.md) `design:m4-migration`
+- [响应可观测字段扩展(Issue #3)](designs/response-observability-fields.md) `design:response-observability-fields`
 
 ## finding (11)
 - [2026-07-20-m2-soak-workload](findings/2026-07-20-m2-soak-workload.md) `finding:2026-07-20-m2-soak-workload`
diff --git a/research-wiki/log.md b/research-wiki/log.md
index fefef15..38a49a4 100644
--- a/research-wiki/log.md
+++ b/research-wiki/log.md
@@ -57,3 +57,5 @@
 - [2026-07-30 09:39 UTC] 新增 plan: est_tokens 解耦实施计划 (plan:est-tokens-decoupling)
 - [2026-07-30 09:39 UTC] 新增边: plan:est-tokens-decoupling --implements--> design:est-tokens-decoupling
 - [2026-07-30 09:39 UTC] 重建索引: 42 篇页面
+- [2026-07-31 08:35 UTC] 新增 design: 响应可观测字段扩展(Issue #3) (design:response-observability-fields)
+- [2026-07-31 08:37 UTC] 重建索引: 44 篇页面