Draft publish writes non-zero version to exported content database ChannelMetadata #5852

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Target branch: unstable

Observed behavior

When a channel is draft-published, the exported content database records a positive integer in ChannelMetadata.version instead of 0.

map_channel_to_kolibri_channel (contentcuration/contentcuration/utils/publish.py:802-813) unconditionally writes:

version=channel.version + 1,  # Need to save as version being published, not current version

The function receives use_staging_tree but not is_draft_version, so the draft case is not distinguished. The caller create_content_database (same file, lines 143-202) already knows is_draft_version and switches the file-save path to "next", but the in-DB ChannelMetadata.version still gets channel.version + 1.

Expected behavior

On a draft publish, the exported content database's ChannelMetadata.version should be set to 0. This follows the Kolibri convention where version=0 marks a draft content DB as upgradeable to a non-draft version.

Non-draft publishes continue to write channel.version + 1 unchanged.

User-facing consequences

• There is no explicit "draft" workflow in Kolibri today; draft handling relies on Kolibri's existing version-upgrade behavior (importing a higher-numbered version clears the draft and reverts the channel to a regular content DB).
• If Studio writes a draft content DB with version = channel.version + 1, Kolibri cannot tell it apart from a regular published DB at the same version number. A draft could get picked up and treated as the latest version, blocking the intended upgrade/revert path.
• Writing version = 0 in the content DB encodes draft-ness in the artifact itself, so Kolibri's upgrade logic naturally replaces a draft with any real published version (since any real version > 0), independent of whatever higher-level draft handling Kolibri may or may not add later.

Steps to reproduce

1. On Studio unstable at d9dbadb86 (or later), open a channel and trigger a draft publish.
2. Retrieve the exported draft content database (e.g. via the "next" path used by save_export_database with is_draft_version=True).
3. Inspect the DB's ChannelMetadata row:

   SELECT id, name, version FROM content_channelmetadata;

4. Observe: version is channel.version + 1 (a positive integer), not 0.

Context

• Studio: unstable at d9dbadb86 (includes PRs fix: populate draft ChannelVersion metadata during draft publishes #5841 and fix: populate channel snapshot fields on draft ChannelVersion during draft publish #5851 for draft ChannelVersion metadata snapshotting). The content-DB version bug pre-dates those fixes and is independent of them.
• Relevant code: map_channel_to_kolibri_channel (contentcuration/contentcuration/utils/publish.py:802-813) and its caller create_content_database (same file, lines 143-202), which already knows is_draft_version but does not propagate it to the version assignment on ChannelMetadata.
• Kolibri: no explicit draft workflow; draft lifecycle is carried by the existing version-upgrade semantics, which is why encoding version=0 in the draft DB matters.
• Server-side only.

AI usage

Drafted with Claude (Opus 4.7) via Claude Code — Claude traced the publish path and drafted each section; I reviewed section-by-section and corrected the user-facing consequences to reflect that Kolibri has no explicit draft workflow and version=0 is a safeguard, not a required marker for an existing UX.

Acceptance Criteria

• On a draft publish, the exported content database's ChannelMetadata.version is 0.
• On a non-draft publish, ChannelMetadata.version continues to equal channel.version + 1 (no regression).
• is_draft_version is propagated from create_content_database to map_channel_to_kolibri_channel (or equivalent) so the version assignment has access to the draft flag.
• Tests cover: (a) draft publish produces a content DB with ChannelMetadata.version == 0, (b) non-draft publish produces a content DB with ChannelMetadata.version == channel.version + 1.