fix(web): v0.2 round-5 workbench: poll-based runner trace streaming for Code Agent real-time events (HWLAB #775 round 2) (#781)
Continues HWLAB #775 round 2 by adding live runner-trace
streaming on top of the round-1 inactivity-timeout + 23-row
Code Agent status + rich trace panel foundation. Cloud-api v0.2
removed the pre-React `/v1/agent/chat/trace/<id>/stream` SSE
endpoint (404 today), so this round uses the existing
`/v1/agent/chat/trace/<id>` JSON endpoint as a polling source.
## 修复对照（迁移前 → 迁移后）
| 类别 | 迁移前 (`893f46bc`) | 迁移后 (round 2) | 状态 |
|---|---|---|---|
| **Trace 事件实时滚动** | `app-device-pod.ts:708-756` `subscribeRunnerTrace` EventSource on `/v1/agent/chat/trace/<id>/stream`，`TRACE_STREAM_FALLBACK_MS` 后降级到 `pollRunnerTrace` (3s 间隔) | `state/runner-trace.ts:pollRunnerTrace` 直接走 `/v1/agent/chat/trace/<id>` 1.5s 间隔（EventSource 端点 404），每次新 eventCount / status / updatedAt 触发 `onSnapshot(snapshot)` | ✅ 对齐（polling 模式） |
| **Trace 事件合并** | `app-trace.ts:80-110` `appendTraceEvents` 把新 events 追加到 message.runnerTrace.events | `state/runner-trace.ts:mergeRunnerTrace` 选最长 events 数组，eventCount / lastEventLabel / updatedAt 全部以最新 snapshot 为准；`state/workbench.ts:reducer.message:trace` 派发并替换 | ✅ 对齐 |
| **Trace 终态** | `app-device-pod.ts:1013-1070` `updateMessageTrace` 走 reconcileCodeAgentResult | `state/runner-trace.ts:pollRunnerTrace` 检测 `isTerminalStatus` 返回最终 snapshot；`state/workbench.ts:submitMessage` 拿到 `mergeTraceResults(terminal, traceTerminal)` 作为 `messageFromAgentResponse` 入参 | ✅ 对齐 |
| **Trace 全量回放** | `app-conv.ts:1133-1170` `replayFullTrace(messageId)` 调 `/v1/agent/chat/trace/<id>` | `state/runner-trace.ts:replayFullTrace(traceId, totalTimeoutMs)` 同样路径；`message:trace` reducer 自动接收新 snapshot | ✅ 对齐（client 暴露） |
| **TRACE_POLL_INTERVAL_MS** | `TRACE_POLL_INTERVAL_MS = 1500`（推断，从 `setTimeout(tick, ...)`） | `state/runner-trace.ts:TRACE_POLL_INTERVAL_MS = 1500` | ✅ 对齐 |
## 新文件 / 改动
- 新增 `web/hwlab-cloud-web/src/state/runner-trace.ts`（175 行）：`TraceSnapshot` 类型 + `mergeRunnerTrace` + `snapshotToRunnerTrace` + `mergeTraceResults` + `waitForAgentResult` + `pollRunnerTrace` + `replayFullTrace` + `isResultUrlStatus` / `isTerminalStatus`（导出）
- `web/hwlab-cloud-web/src/state/workbench.ts`：删除内置的 `waitForAgentResult` / `pollRunnerTrace` / `mergeTrace` / `snapshotToRunnerTrace` / `mergeTraceResults` / `isResultUrlStatus` / `isTerminalStatus` / `TraceSnapshot`，全部 import 自 `./runner-trace`；新增 reducer `message:trace` 处理 partial trace 推送；`submitMessage` 并行启动 `pollRunnerTrace` 与 `waitForAgentResult`，最终用 `mergeTraceResults` 合并
## 验收
- `cd web/hwlab-cloud-web && bun run check` 通过（Vite build + 2/2 dist freshness test pass）
- `bun run scripts/tsc-check.ts` 通过（strict React TSX, 0 explicit any）
- `bun test` 2 pass / 0 fail
- `bun run build` 9 dist files verified fresh；`app.js` 213154 → 216030 bytes
- `workbench.ts` 371 行（< 400 前端 guard）；`runner-trace.ts` 175 行
- dist `app.js` 含 `/v1/agent/chat/trace`、`eventsCompacted`、`agentRun` 关键字
Refs: pikasTech/HWLAB#775 (round 2 of 7)
Co-authored-by: HWLAB <ci@hwlab.local>
Lyon
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