System Storage: show available space per root folder, app data and system disk (#508)

[s3ntin3l8]

Fixes #508

Summary

The System page's Storage card previously reported only the disk hosting the application — in Docker/NAS setups that's a small boot/app device (e.g. a 4 GB USB DOM), while the audiobook library lives on a separate mount that was never shown. This adds per-disk reporting so the System page shows available space for the System disk, the App Data (config) volume, and every configured root folder.

Changes

Added

• GET /api/v1/system/storage now returns a disks[] array with an independently-measured entry for the System disk (container root, e.g. docker.img on Unraid), the App Data disk (config volume holding the database/logs/cache), and each configured root folder (one row per folder, no dedupe). Missing or inaccessible paths yield an unavailable entry instead of failing the request.
• System page Storage card renders these as a stacked per-disk list: label + mount point, a full-width usage bar, and free of total per row.
• IDiskSpaceProbe seam abstracting disk measurement — Windows GetDiskFreeSpaceEx (handles drive paths, mounted-folder junctions, and UNC/NAS shares) with a DriveInfo/statvfs fallback on Unix — so NAS roots are measured and the logic is unit-testable.
• Defensive clamping of used bytes/percentage for filesystems that report free space exceeding total (reserved blocks, over-provisioning, ZFS/Btrfs, network shares).

Changed

• Legacy top-level StorageInfo fields are retained for compatibility but now describe the App Data disk (config volume); driveName carries that path (was DriveInfo.Name, e.g. /). Per-disk detail is in disks[]. API consumers relying on these fields should note the changed meaning.
• ProgressBar's size formatter gains a TB unit (multi-terabyte mounts previously displayed as thousands of GB).

Fixed

• System page Storage no longer reports only the application/boot device — it reflects the disk(s) where the library actually lives, resolving the misleading free-space readout in System Storage: Show available space on a root folder basis too #508.

Removed

• The Storage card's summary badge — it could only headline a single disk; the per-disk list now shows each disk's free/total concisely.

Screenshots

Testing

• Backend (SystemServiceStorageTests, hermetic via temp dirs): no root folders, config-root measurement and content-root fallback, multiple folders on one filesystem, missing path → unavailable, UNC path measured via a fake probe (available + unavailable), and an over-provisioned disk → usage clamped to zero.
• Backend (DiskSpaceProbeTests): the real DriveInfo branch on an existing temp dir and a missing path. The Windows GetDiskFreeSpaceEx call can't run on Linux CI, so that path is review-covered.
• Frontend: StorageDisksList.spec.ts (per-disk rows, free-of-total, unique keys, unavailable) and ProgressBar.spec.ts (TB / sub-TB formatting).
• Full suites green: 691 backend / 368 frontend, plus dotnet format, vue-tsc, ESLint, Prettier.
• Verified end-to-end in Docker and on an Unraid deployment with the library on a separate mount.

Notes

• This PR needs a version label for the Validate PR version label check — I don't have triage rights to add it.
• No CHANGELOG.md entry, per the no-changelog-on-upstream-PRs policy.

🤖 Generated with Claude Code

[therobbiedavis]

Thanks for the fix here. I left a couple of small review notes around edge cases/UX polish; nothing huge, but worth tightening before merge.

[therobbiedavis]

LGTM, but there is one non-blocking request: Could we pull the Windows path/native-call handling behind a tiny testable seam and add coverage for UNC inputs? I’m not asking because I reproduced a failure: I tested GetDiskFreeSpaceExW against a temporary elevated local SMB share and it succeeded with and without a trailing slash. This is more about keeping the NAS-support behavior from regressing later.

[s3ntin3l8]

Done in 1bbdc329. Pulled the Windows GetDiskFreeSpaceEx handling behind a small IDiskSpaceProbe seam (interface in application, impl in infrastructure) so SystemService no longer branches on OS. Added tests that drive a UNC path through the measurement pipeline (available + unavailable) plus probe tests for the Unix/DriveInfo branch — the native call itself still can't run on Linux CI, so that one line stays review-covered.

Same commit also tightens a few small things: clamp used bytes/percentage so filesystems reporting free > total (over-provisioning, ZFS/Btrfs, network shares) can't go negative; XML-doc the legacy top-level StorageInfo fields as describing the App Data disk; drop the now-redundant Storage card summary badge (the per-disk list covers it); and add ProgressBar TB-formatting tests.

[therobbiedavis]

@s3ntin3l8 LGTM. Can you update the PR description to match the template? We should be good to merge after that.

[s3ntin3l8]

@s3ntin3l8 LGTM. Can you update the PR description to match the template? We should be good to merge after that.

@therobbiedavis: Done and ready to merge