fix: prevent downloads sheet crash during active downloads

[mvanhorn]

Add a package-level DownloadData production model that owns cursor decoding for the fields consumed by the downloads UI, treating metadata that can be null, unknown, or temporarily unavailable during running, pending, and paused states as optional while keeping identity and status validation explicit. Opening the Downloads bottom sheet while Android's DownloadManager contains an active download crashes the app, while the same entry renders after the transfer finishes.

Decode and render a running download whose local URI and MIME type are null and whose total size is still unknown; opening/populating the list remains successful and shows the existing generic downloading state; Decode running, pending, and paused rows with zero or partial byte counts and confirm each produces a stable model without arithmetic or null failures.

Fixes #802

[Slion]

Thanks, it's obviously a lot of AI noise but still appreciated.

[Copilot]

🟡 Changes recommended

There are a couple of correctness/maintainability issues to address (notably validating non-positive download IDs and updating misleading log messages) before approval.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Pull request overview

This PR addresses a crash when opening the Downloads bottom sheet while Android DownloadManager contains active (running/pending/paused) downloads by introducing a dedicated DownloadData model that safely decodes cursor rows with transient/null/unknown metadata.

Changes:

• Add a package-level DownloadData model with safe optional column decoding and explicit required-field validation.
• Refactor DownloadsFragment to decode/update UI from DownloadData instead of directly reading cursor columns.
• Add Robolectric unit tests covering decoding of active downloads with null/unknown fields and missing columns.

File summaries

File	Description
app/src/main/java/fulguris/settings/fragment/DownloadData.kt	New cursor-decoding model for downloads with required/optional field handling.
app/src/main/java/fulguris/settings/fragment/DownloadsFragment.kt	Switch downloads UI population/updates to use DownloadData decoding to prevent cursor/nullable crashes.
app/src/test/java/fulguris/settings/fragment/DownloadDataTest.kt	Add unit tests for decoding active/completed downloads and missing/invalid cursor data.

Review details

Suppressed comments (1)

app/src/main/java/fulguris/settings/fragment/DownloadsFragment.kt:495

• These debug log messages still reference the old method name updateDownloadFromCursor, which makes logs misleading now that the implementation is updateDownload(downloadData: DownloadData).

            setDownloadIcon(downloadPref, downloadData.status, downloadData.mimeType, downloadData.localUri)
            Timber.d("updateDownloadFromCursor: Updated existing preference for download $id")
        } else {
            // Create new preference
            downloadPref = createDownloadPreference(downloadData)
            downloadsListCategory.addPreference(downloadPref)
            Timber.d("updateDownloadFromCursor: Created new preference for download $id")
        }

• Files reviewed: 3/3 changed files
• Comments generated: 2
• Review effort level: Lite

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[mvanhorn]

Fair point, and thanks for taking the time on it anyway. The description was doing too much - here it is in two lines: opening the Downloads sheet crashes when DownloadManager holds an active download, because the cursor's local URI, MIME type and total size can all be null or unknown mid-transfer. DownloadData now treats those as optional and keeps only id and status required.

If the diff is the noisier part rather than the prose, I'm happy to split it: keep the null-safety fix plus its test here, and move the DownloadData extraction to a follow-up. Say the word and I'll reshape it.

[Slion]

Do you have a way for me to reproduce that crash? On which phone and Android version were you seeing it?

[mvanhorn]

No device of my own, so let me be straight about what I have and do not have.

I did not reproduce this on hardware. The environment is @Wandering5oul's from #802: Moto g(8) play, Android 10, build QMDS30.47-33-5, WebView 148.0.7778.120, crash on opening Downloads while a large file is mid-transfer. You already tried in May and could not hit it, so the interesting question is why it is device dependent.

My reading of the old code path, which is a hypothesis and not a stack trace I have seen: createDownloadData calls getColumnIndexOrThrow for every column, including COLUMN_LOCAL_URI and COLUMN_MEDIA_TYPE. That throws when the column is absent from the cursor, not when the value is null, and getString on a null value would have returned null harmlessly. So the failing case is a DownloadManager.query() cursor that omits those columns entirely while the download is still running, before the file is finalized. Whether they appear mid-transfer varies by Android version and OEM provider, which fits both the reporter seeing it every time and you never seeing it.

If that is right, the confirming evidence is one line of the crash: IllegalArgumentException: column local_uri does not exist (or media_type). Worth asking @Wandering5oul for the logcat stack trace on #802 rather than either of us guessing.

One thing I should flag about my own PR rather than let you find it: the tests I added pin DownloadData.fromCursor behaviour, they do not reproduce the old crash. DownloadData is new, so they cannot fail against the previous code. If you want a real regression guard I can add a test that builds a MatrixCursor without the local_uri and media_type columns and asserts the decode survives, which does fail on the old path and pass on the new one. That is a deterministic repro you can run in CI without the phone.

The offer to split still stands: null-safety fix plus that regression test here, DownloadData extraction as a follow-up. Say which shape you prefer and I will reshape it.