[austinywang]

Summary

In cmux-next, Chromium's own download bubble opened by itself when a download finished. cmux never shows Chromium's toolbar, so the bubble had nothing to anchor to and appeared over the middle of the page, far from cmux's Downloads button. The Downloads button opened a plain NSMenu, and an NSMenu row cannot start a drag, so a finished download could not be dragged into a terminal.

• Chromium's bubble is off. The CEF shim sets download_bubble.partial_view_enabled to false for every request context when it loads (shim_process.mm), incognito included. In Chromium 154, DownloadBubbleUIController::GetPartialView() returns no rows while this pref is false, and OnBubbleAnchorAssembled then shows nothing. The full bubble opens only from Chromium's toolbar button, which cmux does not show.
• The Downloads button opens a native popup (BrowserDownloadsPopup, built on NativePopupHost like the bookmark bubble). It sits under the button, right-aligned, newest download first. Clicking a finished row opens the file; dragging it carries the file URL out, so a terminal pastes its path. A right-click gives the row's actions (Open, Show in Finder, pause/resume, retry, cancel, copy link). A hovered finished row shows a folder button for Show in Finder, and the footer has one-line Open Downloads Folder and Clear Finished Downloads rows.
• A progress ring around the Downloads button while a download runs (Chrome's): running bytes over their sizes, from 12 o'clock clockwise, in whole-percent steps over a faint track. A download of unknown size shows a short arc. No animation; the arc follows the bytes.
• A finished download opens the popup by itself under that tab's button, without key focus (typing stays where it was). It closes after 5 s (DemandTimer) unless the pointer goes into it. A tab whose toolbar is not on screen keeps the existing notice over the tab. The popup closes when its toolbar leaves the screen (tab switch or close).

Testing

• python3 scripts/cmux-next/prepush-gate.py: no new violations at each pushed head.
• Fleet app builds (cmux-ci build cmux, tag nx-downloads-popover-anchor): job 07a26c025e8d at 5634e0a failed to compile (.failed is failed(String)), fixed in e700d94; jobs e4a85ddc01c1 (e700d94) and 23f29d7fdda8 (39f3fec) built.
• A subagent correctness review of the diff found the compile error and five smaller issues (first-click on footer buttons, the popup outliving its toolbar, stacked row observers, file checks in body, a pointer already inside). All are fixed in 39f3fec. Its Chromium 154 source check confirmed the pref path above.

Observed / Not run

• Observed: on 39f3fec in the tagged app, Chromium downloads of a local test file and an image finished (downloads.json). The person dogfooding saw cmux's popup under the Downloads button and no Chromium bubble over the page. The footer wrap they saw there is what 3a1c4c6 fixes.
• Not run: no capture of the 3a1c4c6 footer yet. No automated drag into a terminal (this host has no screen-capture or computer-use access). No new tests: this is native popup UI, and the proof is the tagged-app dogfood.

Changelog

Fixed: cmux NEXT's download dialog opens under the browser's Downloads button instead of over the middle of the page, finished downloads drag from it into a terminal, and the button shows a progress ring while a download runs

Proof

Visual review on the exact head is still to come (macOS captures of the popup at rest, with a hovered row, and auto-shown after a download).

Checklist

• Behavior changes have added or updated tests, or Testing says why not
• UI change: localization audited. One new string, browserHits.downloads.showFolder ("Open Downloads Folder"), copied with all 21 locales from the existing action.browser.downloads.showFolder entry; the other strings are existing ones.

🤖 Generated with Claude Code

[austinywang]

Correctness review (subagent, static, against 5634e0a), and what changed:

1. Blocking: download.status == .failed doesn't compile (case failed(String)). Fixed in e700d94 (if case .failed).
2. Footer buttons in the popup that opened by itself needed a first click to make the panel key. Fixed in 39f3fec: the content is a FirstMouseHostingView.
3. The popup stayed up after its toolbar left the screen (tab switch, tab closed). Fixed in 39f3fec: BrowserToolbarButtonsView.onDetach (viewDidHide, or moved out of its window) closes it, and so does a resize when the anchor is gone.
4. When Downloads is collapsed, opening it from More loses More's pressed look (present resets isMenuOpen after the menu). Not fixed: cosmetic, only in the collapsed path.
5. Row-count observers piled up across reopens. Fixed in 39f3fec: a generation counter drops observers from earlier shows.
6. A pointer already over the popup didn't count as inside; Escape doesn't close the popup that opened by itself. The first is fixed in 39f3fec (.assumeInside). The second is not fixed: that popup has no key focus, and a click outside closes it.
7. A file system check ran in each row's body. Fixed in 39f3fec: the file is resolved on click or drag only.
8. The global CEF context doesn't get the pref. Not fixed: the host always passes a profile cache path, so RequestContextFor("") is never reached.

Chromium 154 check: GetPartialView() returns {} while download_bubble.partial_view_enabled is false, and OnBubbleAnchorAssembled returns on empty models, so the bubble doesn't show. The security subpage (OpenSecuritySubpage) still opens on request, unchanged.

3a1c4c6 changes only the UI after dogfooding: footer commands are full-width one-line rows, and a hovered finished row gets a Show in Finder button. A review of that head comes before landing.

[github-actions]

cmux status _{(one comment, edited in place; each line is updated by the job that owns it)}

Review 749711e: HQ feed card · gallery before/after runs · checks

App of this head (app.zip, kept 1 day)

gh workflow run reload-build.yml -R manaflow-ai/cmux --ref feat-cmux-next -f tag=pr23050 -f ref=feat-cmux-next-downloads-popover -f platform=macos -f backend_mode=local

Not verified: macOS jobs did not run: compile and app tests were skipped on 749711efce; ci-status is green without them.

CI passes on 749711efce (run 39558070691 attempt 1).
macOS jobs did not run: compile and app tests were skipped: Fast static checks skipped (the macos job needs both to succeed). Re-run CI once they pass, before merging.

Written by scripts/ci/classify_failures.py (ci-failure-attribution.yml); signatures are its SIGNATURES table. A machine verdict is the runner's fault, not this PR's; yours means the failing file is one this PR changes, also red on main that main's latest full suite fails the same way, seen on other PRs that it failed on another pull request's run lately.

[teamleaderleo]

Bead cx-rwy08 created for this PR by the cmux coordinator.

[teamleaderleo]

cmux-next guards / defaults-snapshot is red on 24 of 24 fresh feat-cmux-next PR heads in the last 2:00:00, so it is most likely a base red, not this PR's. The base-reds lane has it; a base merge picks up the fix once it lands.

[austinywang]

Correctness review of 3a1c4c6 (the footer and hover change), subagent, static. Nothing blocked compiling or clicking. What changed:

1. The popup kept its old height when the Clear row appeared or went without a row-count change (a download finishing, or the only running one being cancelled, while the popup is open). Fixed in 3d0fa89: the resize observation also reads canClear.
2. A row kept its hover, and its folder button, from the previous show, because the hosting view is reused. Fixed in 3d0fa89: rows rebuild per show (.id(model.shows)).
3. The name shifted when the folder button appeared. Fixed in 3d0fa89: the button has a fixed 24 pt slot.
4. VoiceOver: the row and footer icons were their own elements, and Show in Finder exists only on hover. The first is fixed (icons accessibilityHidden). For the second, Show in Finder stays reachable from the row's menu; no accessibility action added.
5. The folder button showed for a file that had since been deleted. Fixed in 3d0fa89: it shows only while draggableFile finds the file.

[github-actions]

The feat-cmux-next push run https://github.com/manaflow-ai/cmux/actions/runs/39558816819 at c7ce585 failed: cmux-next Release compile (Xcode 26).
Those jobs last passed at 233cc81. This pull request is one of 4 merged since: #23065, #23050, #23073, #22992.
If the failure is in your change, fix forward on feat-cmux-next. Pull requests run only the tiers their paths reach (docs/ci/cmux-next-tiers.md); label a batch PR full-ci to run them all before merging.

[github-actions]

The feat-cmux-next push run https://github.com/manaflow-ai/cmux/actions/runs/39559424526 at 240de48 failed: cmux-next Release compile (Xcode 26).
Those jobs last passed at 233cc81. This pull request is one of 5 merged since: #23065, #23050, #23073, #22992, #23062.
If the failure is in your change, fix forward on feat-cmux-next. Pull requests run only the tiers their paths reach (docs/ci/cmux-next-tiers.md); label a batch PR full-ci to run them all before merging.

[github-actions]

Shipped in:

• cmux NEXT nightly 1.0.0-nightly.3958372135301 (bc661dae0e)