Snapshot download builds a 404 URL: timestamped version used as the version directory segment

[knowledge-graphlet]

Symptom

Downloading a snapshot knowledge artifact from Nexus fails with:

Download failed: java.io.IOException: Unexpected HTTP 404 downloading …

even though the dialog resolves the artifact, shows its size, and reports "Knowledge Artifact: Ready for Download". Releases are unaffected.

Root cause

MavenDataSourceDialogController uses the selected version verbatim as the version directory segment:

String directoryVersion = selectedVersion.strip();   // line 1295
…
URI downloadUri = MavenDataStoreDownloadTask.downloadUri(
        repositoryUrl, coordinates, directoryVersion, fileVersion, classifier);   // line 1323

For a remote repository the version combo box is populated from the Nexus component search, which returns the resolved, timestamped snapshot build (e.g. 1-chronology-builder-20260724.000852-12). Maven's repository layout stores those under the base directory 1-chronology-builder-SNAPSHOT/, with only the filename carrying the timestamp.

MavenDataStoreDownloadTask.downloadUri's 5-argument overload exists precisely to keep the directory version and the file version distinct, and its javadoc says so — but the caller passes the timestamp as both.

The local flow is already correct: it keeps X-SNAPSHOT in the combo box and calls LocalVersionResolver.resolveSnapshotFileVersion for the filename.

Evidence

Probed live against network.ike.foundation:ike-starter-set:1-chronology-builder-SNAPSHOT:reasoned-pb:

URL shape	result
dir=…-SNAPSHOT, file=timestamped+classifier	200 (correct layout)
dir=timestamped, file=timestamped+classifier	404 (what the dialog requests)
dir=…-SNAPSHOT, file=timestamped, no classifier	404
dir=…-SNAPSHOT, file=…-SNAPSHOT+classifier	404

Proposed fix

Derive the directory version from the selected version: when it matches Maven's resolved-snapshot form <base>-<yyyyMMdd.HHmmss>-<buildNumber>, the directory is <base>-SNAPSHOT; otherwise directory == selected version. Put the helper in MavenDataStoreDownloadTask beside downloadUri/localRepositoryPath (both need the same rule) and unit-test it.

Acceptance

• Downloading a timestamped snapshot build from Nexus succeeds.
• Release downloads keep the current behavior (directory == file version).
• Tests cover: resolved snapshot, plain -SNAPSHOT, release, and a date-based release version that must not be mistaken for a timestamp.