Plugin: explore a click-to-open file list popover from the desktop band

[zachdunn]

Explore a click-to-open file list that pops over the transcript from the uploads band, in the Claude Code desktop app, as a lighter alternative to opening the uploads-staged pane. The model is the desktop app's own CI chip popover on the PR bar.

Idea

• The band's count becomes a button, for example 6 attachments ▾.
• Pressing it toggles a state value. While set, the band draws a card with position: "absolute" and a negative top, over the transcript above the band.
• The card lists the staged files: name, small Svg thumbnail, and actions such as Open on uploads.sh, Copy markdown, and View (opens the pane's detail view). Esc or a second press closes it.

What the mod API offers

From the plugin-authoring reference for Claude Code 2.1.286:

• An absolute Box "paints over its surroundings without moving them". Offsets are in text cells.
• display: "none" with hover: { display: "flex" } is documented as "a card that appears over the rows above a hovered glyph". A click toggle through state should work the same way.
• The desktop also has a native Select, but it is a plain text option list: no thumbnails or row actions.

Open questions

• Does the desktop band let an absolute card extend above it over the transcript, or does it clip?
• Cell offsets placed the earlier ⤢ hover icon unpredictably. Anchoring the card to the band's right edge may be more reliable.
• Styling is limited to borderStyle and backgroundColor, with no shadow. Does it still read as a popover?
• Should the card replace the pane for short lists and keep the pane for long ones?

Next step

Prototype it as a dev mod against the band from #1062 and screenshot it in the desktop app before deciding.