docs(admin): note that av_rescan_days=0 does not disable rescanning

[miaulalala]

☑️ Resolves

av_rescan_days looks like it can be set to 0 to switch off the periodic rescan of
already-scanned files. It cannot, and the failure is silent.

BackgroundScanner::getOutdatedFiles() in nextcloud/files_antivirus:

$rescanDays = $this->appConfig->getAppValueInt(ConfigLexicon::AV_RESCAN_DAYS, 28);
if ($rescanDays < 1) {
    $rescanDays = 28;
}

So any value below 1 is replaced with the default of 28 days and the rescan carries on as
normal, with nothing logged. An admin who sets 0 expecting rescanning to stop will believe it
has stopped.

This adds a note pointing at av_background_scan, which is the setting that actually disables
background scanning, and which the same section already documents.

Found while reviewing #14810, which documents the three background scanner passes and the
28-day rescan interval. Split out as its own PR because it is a distinct behaviour rather than
part of describing how the scanner works.

📌 Merge order

No constraint — verified. I tested #14810, #15538, #15539 and this PR merged together in
sequence: zero conflicts, in any order, and the combined file is sphinx-lint clean. An earlier
version of this section asked for #15538 to be merged first; that turned out to be unnecessary, as
the three changes land in different parts of the file and git resolves them automatically.

🖼️ Screenshots

Text-only change, one .. note:: directive. No visual change and no new images.

✅ Checklist

• I have built the documentation locally and reviewed the output
• sphinx-lint is clean
• Screenshots are included for visual changes (not applicable, text only)
• I have not moved or renamed pages
• I have run codespell — not installed locally, please let CI confirm

[miaulalala]

/backport to stable35

[miaulalala]

/backport to stable34

[miaulalala]

/backport to stable33

[github-actions]

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Last updated: Tue, 01 Sep 2026 20:24:51 GMT