Reuse origin metadata across configuration collections

docs/internal/sources.md

@@ -82,6 +82,9 @@ declaration; absent and null fields remain distinguishable from explicit
 strings, including empty strings. It closes content-file handles before
 returning and retains no source capability for public inspection.
 
+Prompt materialization shares a lazy metadata snapshot across root and collection
+resources during construction, avoiding a full metadata copy per collection.
+
 Role and cache-control normalization is applied to execution-owned message
 copies. ConfigKit v0.8.0 retains effective input message metadata and its
 resource origins; recording a sequence-wide normalization in the retained

docs/roadmap/remediation.md

@@ -1,6 +1,6 @@
 # Configuration Collections Implementation Review Findings
 
-Status: three findings open. Review completed 2026-10-17.
+Status: Finding 1 completed; Findings 2–3 open. Review completed 2026-10-17.
 
 Reviewed implementation after `89af2a1` through `0221cd4` against the accepted
 [feature roadmap](configuration-collections.md), [implementation plan](implementation.md),
@@ -35,7 +35,7 @@ addresses a retained public guarantee that no longer describes scoped views.
 
 ## Finding 1: Share Origin Metadata Across Collection Materialization
 
-Priority: P2. Status: open.
+Priority: P2. Status: completed 2026-10-17.
 
 Locations: [load.go](../../internal/configuration/load.go), lines 257–262, and
 [materializePrompts](../../internal/configuration/prompts.go), lines 84–95.
@@ -78,6 +78,15 @@ one file-backed collection, and use a small scaling benchmark to verify the
 repeated full-snapshot cost is removed. Do not make exact allocations, elapsed
 times, or private helper call order a new contract.
 
+Completion: prompt materialization now traverses root and collection resources
+within one construction-scoped pass sharing the lazy origin metadata snapshot.
+Extended the imported/inherited-content test across distinct collection resource
+contexts and added a scaling benchmark without allocation or timing assertions.
+At 64 collections the same benchmark dropped from 104,574,200 to 21,239,712
+allocated bytes per construction in single-iteration local measurements.
+Validation passed: focused origin tests and benchmark, race-enabled configuration
+and public API tests, configuration vet, and `git diff --check`.
+
 ## Finding 2: Detach The Optional Label In Internal Prepared Snapshots
 
 Priority: P3. Status: open.