[BUG] NZBGet imports never run — `GetImportItemAsync` keeps the stale intermediate `ContentPath` instead of resolving the final path from history

[NiCADitO]

Summary

With NZBGet (separate InterDir configured), every completed download fails to import. Files land in completed/, but Listenarr keeps scanning the intermediate/<name>.#NZBID working dir — which is deleted after completion — so it never imports and the Activity entry stays stuck. No remote path mapping (so not #486).

Environment

• Listenarr canary (reproduced on HEAD / v1.0.6)
• NZBGet (LinuxServer): DestDir=.../completed, InterDir=.../intermediate
• Listenarr + NZBGet share /data:/data; no remote path mapping
• Deterministic, reproduced on 4 titles

Symptom

[WRN] DownloadClientGateway: reported no source files and content path scanning failed
for item Brian.Jacques-Redwall.21-The.Sable.Quean... with path
/data/downloads/nzbget/intermediate/...#125/...

File is actually at /data/downloads/nzbget/completed/.../The Sable Quean.m4b.

Root cause

GetImportItemAsync (listenarr.infrastructure/Adapters/NzbgetAdapter.cs, ~line 1032) returns early on a non-empty ContentPath without checking it exists:

// If ContentPath is already set and exists, use it
if (!string.IsNullOrEmpty(result.ContentPath))
{
    return result;
}

The comment says "and exists," but there's no existence check. MapGroup (~line 755) has already set ContentPath from the active group's DestDir, which for an in-progress NZBGet group is the intermediate working dir. So this early return hands back the stale path and the history FinalDir/DestDir resolution just below (~lines 1063–1065) never runs. After completion the intermediate dir is gone, the gateway's Directory.EnumerateFiles throws, and import fails.

Fix

if (!string.IsNullOrEmpty(result.ContentPath) &&
    (File.Exists(result.ContentPath) || Directory.Exists(result.ContentPath)))
{
    return result;
}

Now the stale path fails the guard, execution falls through to the history lookup, ContentPath resolves to completed/<name>, and import proceeds.

Note: clearing InterDir is not a workaround — NZBGet still uses a .#NZBID temp dir that's renamed on completion, so the early return still returns a stale path.

[T4g1]

We should probably use the opportunity to remove the GetImportItemAsync ability to receive result candidates (or scope that into #599)

[therobbiedavis]

We should probably use the opportunity to remove the GetImportItemAsync ability to receive result candidates (or scope that into #599)

@T4g1 #599 is a larger refactor, so lets scope it into that.