Windows desktop app takes ~1-2 minutes to become usable while startup launches multiple CLI processes

> *This was generated by AI during triage.*

## Environment

- Windows 11
- GitHub Copilot desktop app v1.0.25 (updater reported latest)
- App-spawned Copilot CLI v1.0.71
- Existing sessions and multiple projects

## Actual behavior

After starting the desktop app, the reporter observes approximately **1-2 minutes** before existing sessions become usable.

One captured startup/resume sequence took **91.9 seconds**:

| Segment | Duration |
|---|---:|
| App start -> resume request | 74.577s |
| Resume request -> completion | 17.402s |

The entire 91.9 seconds is not resume time, and logs do not prove the pre-request interval was entirely blocking.

## Expected behavior

The app should become usable promptly after startup.

## Observations

- Startup booted eight CLI processes: seven for catalog warming and one for the requested resume.
- Five CLI boot intervals overlapped at peak.
- No CLI spawn failures or retries occurred in this startup window.
- Across 22 samples from the full run, `spawn_ms` was 6,598-21,343ms (median 12,196ms).
- Seven catalog creations reported `create_session_rpc_ms` of 11,507-27,413ms.
- Cold `session_create_ms` samples were 16,005-31,896ms; warm-process samples were 100-343ms.

These are separate metrics measured on this host.

## Sanitized log shapes

```text
github_app::session::manager::cli_pool: spawned new CLI process for pool ... pid=Some() spawn_ms=14516

github_app::session::core: CLI session created ... create_session_rpc_ms=

github_app::session::manager::lifecycle: session::create completed ... retain_cli_ms= model_fetch_ms= session_create_ms=26391 total_ms=
```

## Unconfirmed factors

The profile contained 1,145 sessions and 1.37GB of session state. A clean-profile control was not performed because the investigation was read-only.

MCP configuration, Defender, orphaned processes, authentication warnings, and an invalid hook remain unproven as causes.

## Related issues

- https://github.com/github/copilot-cli/issues/4165 - Windows cold resume hangs on CLI v1.0.72-0; this report concerns desktop startup.
- https://github.com/github/copilot-cli/issues/3652 - WSL startup spends 40-80 seconds in `listSessions`.
- https://github.com/github/copilot-cli/issues/3429 - Linux v1.0.49 cold boot regression caused by credential lookup.

## Questions

1. Is catalog warming expected to create one CLI process per project or directory?
2. Should these CLI processes be reused or pooled?
3. Which diagnostics expose the internal phases of `create_session_rpc_ms`?
4. Is a clean-profile reproduction required?

## Additional context

This is a read-only investigation from one host. It establishes timing and correlation, not the internal root cause.

尚未確認任何原始碼檔案、測試或進入點。先從已擷取的啟動/恢復日誌以及 spawn_ms、create_session_rpc_ms 和 session_create_ms 測量值開始；判斷 catalog 預熱和多個 CLI 程序是否能解釋這項延遲，並建立可重現的完成標準。

由索引模型根據 Issue 內容生成。