Flash via udisks2 on Linux instead of requiring root

[justanotherariel]

Description

Flashes drives on Linux through the udisks2 D-Bus API instead of requiring the whole app to run as root. The device is resolved, unmounted, and opened via udisks2, so a single polkit prompt grants access for everything. Adds a DiskServiceUnavailable error for when udisks2 isn't installed/running.

Beyond the cleaner UX, this fixes UI rendering glitches when flashing: writing previously needed the whole Tauri app to run as root, and WebKitGTK's web/network process can't initialize its bubblewrap sandbox as uid 0, so subresources served over Tauri's asset protocol (CSS/JS/images) failed to load and the UI rendered unstyled/broken.

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)
• Documentation update
• Refactoring (no functional changes)
• CI/CD changes

Related Issues

Testing

• Unit tests added/updated
• E2E tests added/updated
• Manually tested on macOS
• Manually tested on Windows
• Manually tested on Linux

Screenshots

Checklist

• My code follows the project's code style
• I have run cargo fmt and npm run lint
• I have added tests for my changes
• All new and existing tests pass
• I have updated documentation if needed
• My commits follow conventional commit format

[codecov-commenter]

Codecov Report

❌ Patch coverage is 73.54086% with 68 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.76%. Comparing base (020a1dc) to head (1c1572c).
⚠️ Report is 3 commits behind head on main.

Files with missing lines	Patch %	Lines
crates/hai-core/src/disk_writer.rs	74.49%	63 Missing ⚠️
crates/hai-desktop/src/commands.rs	0.00%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #14      +/-   ##
==========================================
+ Coverage   89.52%   89.76%   +0.24%     
==========================================
  Files          28       28              
  Lines       10887    11055     +168     
  Branches       82       82              
==========================================
+ Hits         9747     9924     +177     
+ Misses       1140     1131       -9     

Flag	Coverage Δ
backend	92.32% <73.54%> (+0.30%)	⬆️
frontend	84.80% <ø> (ø)

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[Copilot]

Pull request overview

This PR changes Linux drive flashing to go through the udisks2 D-Bus API (via zbus) instead of requiring the entire Tauri app to run as root. Resolving, unmounting, and opening the target device now happen through udisks2, so a single polkit prompt authorizes the operation. This also fixes a WebKitGTK rendering bug where running the whole app as root broke the asset-protocol sandbox and left the UI unstyled.

Changes:

• Replace root-based OpenOptions device access on Linux with udisks2 D-Bus proxies (Manager.ResolveDevice, Block.OpenDevice, Filesystem.Unmount), opening the fd with O_SYNC and dropping the page cache before verify.
• Add a DiskServiceUnavailable error variant plus a map_udisks_error helper that classifies D-Bus faults into unavailable/permission/busy/not-found errors, and surface these in flash_image.
• Merge write and verify into a single blocking task reusing one device handle, and update dependencies (zbus, libc) and tests accordingly.

Reviewed changes

Copilot reviewed 5 out of 6 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
crates/hai-core/src/disk_writer.rs	Core rewrite of the Linux flashing path to use udisks2/zbus; adds proxies, error mapping, partition-name helper, and updated tests
crates/hai-core/src/error.rs	Adds DiskServiceUnavailable variant and its display test
crates/hai-desktop/src/commands.rs	Maps VerificationFailed/DiskServiceUnavailable to user-facing messages in flash_image
crates/hai-core/Cargo.toml	Adds Linux-only zbus/libc dependencies
Cargo.toml	Declares workspace zbus (v5, tokio) and libc versions
Cargo.lock	Records resolved dependency graph changes

[edenhaus]

The CI is failing. Can you please give it a look and fix it?

Please also add some tests for your changes

[home-assistant]

Please take a look at the requested changes, and use the Ready for review button when you are done, thanks 👍

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[justanotherariel]

MacOS CI job seems to be flaky. Rerunning it fixed it. Added some tests.

[Copilot]

Pull request overview

Copilot reviewed 5 out of 6 changed files in this pull request and generated no new comments.

[edenhaus]

MacOS CI job seems to be flaky. Rerunning it fixed it. Added some tests.

Until now it was stable. So not sure if your changes introduced these flakiness but I will hold this PR back until we have the artefacts and co so we are sure everything is working as expected