Feature: native Download action on present deliverable cards (critical for headless/WSL hosts)

[knight-ni]

Context

• dsh 0.1.7 introduced the present tool and deliverable cards (delivery cards + changed-files card). The card action set today: preview in sidebar / reveal in file manager / open with an application.
• On headless hosts (our deployment: dsh web served from WSL2 via systemd, user browser on Windows / over the network), reveal and open-with are unusable: the host has no desktop ("This Host has no desktop available..."), and the Windows interop path (explorer.exe) is unavailable from the service environment.
• The only remaining way to obtain the file: open the sidebar preview, then download from inside the preview — two extra steps, and undiscoverable for users looking for a download button on the card.
• Before 0.1.7, community plugin dsh-rich-artifacts provided cards with a direct download action. The plugin is dead on 0.1.7 (the conversationEvents service it depends on was removed), leaving a capability gap for server deployments.

Proposal

Add a native Download action to deliverable cards (and optionally to changed-file rows):

• Client: an <a href download> in the card action row. All required data is already available inside PresentedFileCard — resolveWorkspacePath(cwd, file.path) is already computed there (it is the preview button's title).
• Server: an authenticated file endpoint responding with Content-Disposition: attachment (size-capped), equivalent to what the sidebar preview download already does.

Evidence it works

We patched the official client bundle (dsh-client-ui-deliverables/lib/client.js) to prepend a download link in the actions row, backed by a ~40-line webServer route in a plugin (serves the resolved path with attachment headers). Verified end-to-end: the link renders on every deliverable card and clicking downloads the file with the correct filename. Happy to share the patch details.

Notes

• Every user migrating from 0.1.0 + rich-artifacts to 0.1.7 hits this gap (publish_artifact cards used to have direct download).
• A complementary enabler: expose the card action set as an extension point so plugins can add actions without patching the shipped bundle.

[bolide737]

简短交叉引用，不打断原讨论主题。

你们这个补丁思路（在 PresentedFileCard 的动作行里加 download 链接 + 一个约 40 行的 webServer 路由）和我刚开的那条讨论正好是同一个扩展点，两条互相指一下：

• #8059 — 交付卡片的「打开」按钮能否可配置默认动作（侧边栏预览 / 系统默认程序 / 文件管理器）。现状是：卡片本体与「打开」按钮**都绑在 onPreview（侧边栏预览）**上，按钮文案是「打开」但动作是预览；真正的 onAction("open")（默认程序）/ onAction("reveal")（文件管理器）只藏在右侧 ⌄ 菜单里。

顺带把我实测过的本地补丁放这儿，供你们改 PresentedFileCard 时对照（同一文件、同一函数，改法可以互相参考）：
https://github.com/bolide737/dsh-patches → patches/card-open-native/（一行：把「打开」按钮的 onClick: onPreview 换成 onClick: () => onAction("open")，附幂等安装/回退脚本与原理文档）。

和你帖子里的痛点是一致的：现在卡片上能做的事远比看上去少 —— 你们要的 Download 在 headless/WSL 下是唯一出路，我这边要的"点一下用系统程序打开"则是把已有能力从 ⌄ 里挪到明面上。两条本质上都是把动作行做成可发现、可配置的，官方要收编的话建议一起设计。