ENG-2215 Give cross-space relation endpoint RIDs the platform subtype in dbToCrossAppConverters

[maparent]

Reviewer brief

This makes the subtype mandatory in spaceUriAndLocalIdToRid and findTargetUid.
The missing subtypes are added where necessary.
This avoids a discrepancy with the same object having two distinct Rids.
An inconsistent subtype in tests is also corrected.

We also (separate commit, optional) constrain the subtype to known strings.

Verification

Making the parameter mandatory ensures consistency.
Constraining input values is beyond scope and optional, but also makes future mistakes less likely.

Loom video

https://www.loom.com/share/82c15eed4c4d4c45b77d92d6d7d406d2

Note that the loom mentions the second commit, which I since removed by request.
Making the parameter mandatory in findTargetUid was added after the video, at the request of the reviewing agent.

Scope check

• Ran $scope-check against ENG-2215 and the final diff.
• Scope beyond Done When: subtype became a mandatory ObsidianRidSubtype on spaceUriAndLocalIdToRid and the subtype-less ORN branch was deleted, so every ORN producer is affected, not only relation endpoints; getConceptMap now selects is_schema/is_relation and emits schema/relation subtypes alongside note; buildSharedNodes now stamps note on slot-target rids that previously carried none (sharedNodes.ts:207, with its test updated to orn:obsidian.note:vault-b/node-6), which the ticket lists under Out of Scope.
• Required now: Making the subtype mandatory is the fix chosen in place of carrying the platform on spaceMap — it is what stops a third recurrence after ENG-2142, and it forces every call site to be corrected in this change rather than leaving latent subtype-less producers.
• Anyone affected or consulted: Yes — approach recorded by the assignee on the ticket before implementation.
• Decision: https://linear.app/discourse-graphs/issue/ENG-2215 (comment, 2026-09-11)

Local delegated full review

• Ran a comprehensive review of the entire final diff in a subagent with a fresh context. Use $dg-delegated-full-review when no other full-review workflow is available.

https://linear.app/discourse-graphs/issue/ENG-2215/give-cross-space-relation-endpoint-rids-the-platform-subtype-in

[linear-code]

ENG-2215

[vercel]

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Project	Deployment	Actions	Updated
discourse-graph	Ready	Preview	Sep 11, 2026 4:12pm UTC

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