feat(blog): add article on agent-shell session selection in Emacs

- Add new blog post about configuring agent-shell to prompt for session selection
- Article includes prerequisites with Emacs and Copilot CLI versions
- Covers configuration method using agent-shell-session-strategy setting
- Provides practical use case for managing multiple projects efficiently
- Originally written in Japanese, reviewed for clarity, and translated to English

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/blog/2026-03-01-agent-shell-session-selection.md

@@ -0,0 +1,59 @@
+---
+title: 'How to Select Sessions When Starting the agent-shell ACP Client Running on Emacs'
+pubDate: 2026-03-01
+author: 'Nakahara Daisuke'
+tags: ["Emacs"]
+---
+
+I recently returned to Emacs, motivated by CLI-type AI tools like [GitHub Copilot CLI](https://github.com/github/copilot-cli).
+
+Copilot CLI supports ACP (Agentic Communication Protocol), which enables communication between AI agents and editors ([GitHub official documentation](https://docs.github.com/en/copilot/reference/acp-server)).
+And [agent-shell](https://github.com/xenodium/agent-shell) is an ACP client that runs on Emacs.
+
+agent-shell can be started with `M-x agent-shell`.
+By default, starting agent-shell creates a new session. However, with the following configuration change, you can choose to create a new session or select from past sessions when starting. I'll introduce this configuration.
+
+## Prerequisites
+
+```bash
+$ emacs --version
+GNU Emacs 30.2
+Development version 636f166cfc86 on HEAD branch; build date 2025-12-14.
+Copyright (C) 2025 Free Software Foundation, Inc.
+GNU Emacs comes with ABSOLUTELY NO WARRANTY.
+You may redistribute copies of GNU Emacs
+under the terms of the GNU General Public License.
+For more information about these matters, see the file named COPYING.
+```
+
+This article assumes the use of Copilot CLI.
+
+```bash
+$ copilot --version
+GitHub Copilot CLI 0.0.420.
+Run 'copilot update' to check for updates.
+```
+
+After starting Emacs, the result of running `M-x agent-shell-version` is as follows:
+
+```
+agent-shell v0.43.1
+```
+
+## Method
+
+Set the value of `agent-shell-session-strategy` to `prompt`.
+Here is an example configuration in `init.el`:
+
+```elisp
+(use-package agent-shell
+  :custom
+  (agent-shell-session-strategy 'prompt)
+  :ensure t)
+```
+
+With this configuration, you can create a new session or select from history in the minibuffer. Selecting a new session behaves the same as the default behavior, but selecting a past session allows you to resume work in that session's context. This enables you to efficiently manage multiple different projects and tasks.
+
+---
+
+> **Note**: The review and translation were assisted by an AI generative model. The author is responsible for the final content.