Wire successor relations on markitect-legacy-platform (T05 entry 3).

Add related_to links to markitect-toolkit, infospace-workspace, and
context-engine so federated graph and plan-check can route new work away
from the superseded legacy platform entry.

registry/capabilities/capability.communication.markitect-legacy-platform.md

@@ -65,7 +65,10 @@ availability:
 relations:
   depends_on: []
   supports: []
-  related_to: []
+  related_to:
+  - capability.communication.markitect-toolkit
+  - capability.communication.infospace-workspace
+  - capability.communication.context-engine
 evidence:
   documentation:
   - INTRODUCTION.md
@@ -81,11 +84,18 @@ consumer_guidance:
   recommended_for:
   - understanding the historical design this scope split from; not for new integrations
   not_recommended_for:
-  - new consumers — use markitect-tool, infospace-bench, or kontextual-engine instead, per their own scope-assessment
+  - new integrations — prefer capability.communication.markitect-toolkit (syntax/CLI),
-    docs
+    capability.communication.infospace-workspace (application layer), or
+    capability.communication.context-engine (knowledge-operations runtime)
   known_limitations:
   - actively being split apart; treat as reference/legacy, not a forward-looking target
-promotion_history: []
+promotion_history:
+- date: "2026-07-07"
+  dimension: relations
+  from: "(none)"
+  to: "markitect-toolkit, infospace-workspace, context-engine"
+  rationale: REUSE-WP-0017-T05 entry-3 review — wire successor capability IDs for planner routing.
+  author: grok
 ---
 
 # MarkiTect Legacy Platform
@@ -120,5 +130,5 @@ intentionally conservative pending REUSE-WP-0019 reuse-telemetry evidence.
 - [x] ID follows `capability.<domain>.<name>` pattern
 - [x] Maturity enums match `specs/CapabilityMaturityStandard.md`
 - [x] `external_evidence` is populated separately from `maturity`
-- [ ] Relations reference valid capability IDs (none yet)
+- [x] Relations reference valid capability IDs (three successors)
 - [x] Index entry added in `registry/indexes/capabilities.yaml`

registry/indexes/capabilities.yaml

@@ -1,5 +1,5 @@
 version: 1
-updated: '2026-07-06'
+updated: '2026-07-07'
 domain: helix_forge
 capabilities:
 - id: capability.communication.markitect-legacy-platform