feat: 结构化 observation 替代 statusDetail，API 层动态构造 detail

- CheckResult: statusDetail -> observation (持久化) + detail (API 动态派生)
- 存储: status_detail 列 -> observation TEXT (JSON)
- CheckerDefinition: 新增 buildDetail(observation) 方法
- 各 checker 返回结构化 observation，API 层通过 registry 调用 buildDetail
- HTTP: bodyPreview 在 status/header 失败时也提前采集
- UDP: observation 包含 durationMs，未响应归为 error failure
- CMD: 超时/输出超限时保留已收集 observation
- TCP: connectTimeMs 仅含连接建立耗时，不含 banner 等待
- 新增 buildDetail 单测和 mapCheckResult 覆盖测试
- 同步 openspec 主规范，归档 checker-observation 变更

src/server/checker/runner/cmd/execute.ts

@@ -13,6 +13,9 @@ import { checkExitCode } from "./expect";
 import { commandCheckerSchemas } from "./schema";
 import { validateCommandConfig } from "./validate";
 
+const STDOUT_PREVIEW_MAX = 1024;
+const STDERR_PREVIEW_MAX = 1024;
+
 export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget> {
   readonly configKey = "cmd";
 
@@ -20,6 +23,11 @@ export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget>
 
   readonly type = "cmd";
 
+  buildDetail(observation: Record<string, unknown>): null | string {
+    const exitCode = observation["exitCode"];
+    return typeof exitCode === "number" ? `exitCode=${exitCode}` : null;
+  }
+
   async execute(t: ResolvedCommandTarget, ctx: CheckerContext): Promise<CheckResult> {
     const timestamp = new Date().toISOString();
     const start = performance.now();
@@ -37,10 +45,11 @@ export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget>
     } catch (error) {
       const durationMs = Math.round(performance.now() - start);
       return {
+        detail: null,
         durationMs,
         failure: errorFailure("exitCode", "spawn", isError(error) ? error.message : String(error)),
         matched: false,
-        statusDetail: null,
+        observation: null,
         targetId: t.id,
         timestamp,
       };
@@ -70,10 +79,11 @@ export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget>
     } catch {
       const durationMs = Math.round(performance.now() - start);
       return {
+        detail: null,
         durationMs,
         failure: errorFailure("exitCode", "execution", "输出读取失败"),
         matched: false,
-        statusDetail: null,
+        observation: null,
         targetId: t.id,
         timestamp,
       };
@@ -83,24 +93,33 @@ export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget>
 
     const durationMs = Math.round(performance.now() - start);
     const exitCode = proc.exitCode ?? 1;
+    const stdoutPreview = truncatePreview(outputResult.stdout, STDOUT_PREVIEW_MAX);
+    const stderrPreview = truncatePreview(outputResult.stderr, STDERR_PREVIEW_MAX);
+    const observation: Record<string, unknown> = { error: null, exitCode, stderrPreview, stdoutPreview };
 
     if (outputResult.exceeded) {
+      const message = `输出超过限制 ${t.cmd.maxOutputBytes} 字节`;
+      observation["error"] = message;
       return {
+        detail: null,
         durationMs,
-        failure: errorFailure("exitCode", "output", `输出超过限制 ${t.cmd.maxOutputBytes} 字节`),
+        failure: errorFailure("exitCode", "output", message),
         matched: false,
-        statusDetail: `exitCode=${exitCode}`,
+        observation,
         targetId: t.id,
         timestamp,
       };
     }
 
     if (ctx.signal.aborted) {
+      const message = `命令执行超时 (${t.timeoutMs}ms)`;
+      observation["error"] = message;
       return {
+        detail: null,
         durationMs,
-        failure: errorFailure("exitCode", "timeout", `命令执行超时 (${t.timeoutMs}ms)`),
+        failure: errorFailure("exitCode", "timeout", message),
         matched: false,
-        statusDetail: null,
+        observation,
         targetId: t.id,
         timestamp,
       };
@@ -109,10 +128,11 @@ export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget>
     const exitCodeResult = checkExitCode(exitCode, t.expect?.exitCode ?? [0]);
     if (!exitCodeResult.matched) {
       return {
+        detail: null,
         durationMs,
         failure: exitCodeResult.failure,
         matched: false,
-        statusDetail: `exitCode=${exitCode}`,
+        observation,
         targetId: t.id,
         timestamp,
       };
@@ -125,10 +145,11 @@ export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget>
     });
     if (!durationResult.matched) {
       return {
+        detail: null,
         durationMs,
         failure: durationResult.failure,
         matched: false,
-        statusDetail: `exitCode=${exitCode}`,
+        observation,
         targetId: t.id,
         timestamp,
       };
@@ -138,10 +159,11 @@ export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget>
       const stdoutResult = checkContentRules(outputResult.stdout, t.expect.stdout, { path: "stdout", phase: "stdout" });
       if (!stdoutResult.matched) {
         return {
+          detail: null,
           durationMs,
           failure: stdoutResult.failure,
           matched: false,
-          statusDetail: `exitCode=${exitCode}`,
+          observation,
           targetId: t.id,
           timestamp,
         };
@@ -152,10 +174,11 @@ export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget>
       const stderrResult = checkContentRules(outputResult.stderr, t.expect.stderr, { path: "stderr", phase: "stderr" });
       if (!stderrResult.matched) {
         return {
+          detail: null,
           durationMs,
           failure: stderrResult.failure,
           matched: false,
-          statusDetail: `exitCode=${exitCode}`,
+          observation,
           targetId: t.id,
           timestamp,
         };
@@ -163,10 +186,11 @@ export class CommandChecker implements CheckerDefinition<ResolvedCommandTarget>
     }
 
     return {
+      detail: null,
       durationMs,
       failure: null,
       matched: true,
-      statusDetail: `exitCode=${exitCode}`,
+      observation,
       targetId: t.id,
       timestamp,
     };
@@ -269,3 +293,8 @@ async function readOutput(
 
   return { exceeded, stderr: err, stdout: out };
 }
+
+function truncatePreview(text: string, maxLen: number): string {
+  if (text.length <= maxLen) return text;
+  return text.slice(0, maxLen);
+}