docs: adopt InterfaceDeprecationStrangler practice

Assistant: codex
Assistant-Model: gpt-5.6-sol
Assistant-Session: 01a025c2-407a-7a32-b40a-f37a52f03f62

README.md

@@ -1,3 +1,25 @@
 # arc-nexus
 
-A architecture management service that acts as a central registry for architecture blueprints, specifications, guidelines, documents and ADRs.
+An architecture management service that acts as a central registry for
+architecture blueprints, specifications, guidelines, documents, and ADRs.
+
+## Interface evolution practice
+
+Arc Nexus phases out old interfaces using the InfoTechCanon
+`InterfaceDeprecationStrangler` PracticePattern.
+
+- Canon artifact ID: `practice-pattern/interface-deprecation-strangler`
+- Canon source:
+  `info-tech-canon/infospace/patterns/InterfaceDeprecationStrangler.md`
+- Scheme: `practice-pattern/0.1`
+
+For an Arc Nexus interface, adoption means that we name and verify its
+successor, communicate deprecation and the successor at the legacy boundary,
+meter privacy-bounded caller use, distinguish successfully served legacy
+traffic from rejected post-retirement attempts, retain an observable tombstone
+after behavior is retired, and remove that tombstone only after the evidence
+gate passes.
+
+An intended adoption is not implementation evidence. Each concrete Arc Nexus
+use must identify its interface registry record, meter, lifecycle stage,
+retirement policy, and review evidence.