Retire deferred scope and preserve future performance experiments

docs/roadmap/deferred.md

@@ -1,71 +0,0 @@
-# Deferred Scope
-
-This document owns intentionally excluded features, not a committed delivery plan.
-The [future feature list](future.md) preserves candidate enhancements and open
-questions without changing these exclusions.
-The [architecture policy](../policy/architecture.md) governs changes to these
-boundaries. Implemented behavior belongs in the [configuration contract](../config.md)
-and consumer adoption in the [consumer guide](../consumers/README.md).
-
-## Explicit non-goals and deferred scope
-
-General environment-variable configuration overlays are not supported. Typed secret
-references and explicit directory bootstrap are the environment convention. Literal
-credential configuration and implicit secret-directory discovery are unsupported.
-
-The following remain deliberately excluded:
-
-- automatic `conf.d` discovery;
-- remote imports, arbitrary providers, and additional configuration formats;
-- custom merge strategies, sequence merging, reset operators, multiple-parent
-  inheritance, and cross-scope references;
-- named overlay inheritance;
-- parser-specific or custom structural-decoding extension APIs;
-- generic dynamic-subtree conversion and module-registry APIs;
-- automatic schema migrations;
-- hot reload, runtime resource replacement, and remote resource validation;
-- a bundled CLI framework or application commands; and
-- configuration fingerprints.
-
-Applications may build their own validate, effective-value, source, bootstrap, and
-explanation commands around the library. Broadening these boundaries requires
-concrete consumer evidence, compatibility review, and an explicit design change.
-
-Effective configuration diffs are implemented over frozen successful-load
-inspections; their current comparison and disclosure contract is in the
-[configuration contract](../config.md#effective-configuration-diffs), with
-consumer workflows in the [adoption guide](../consumers/README.md#effective-configuration-diffs).
-Fingerprints remain deferred.
-
-Built-in sibling inheritance using `extends` is implemented as described in the
-[configuration contract](../config.md#sibling-inheritance). It is distinct from
-inheritance between selected overlay files, which remains excluded above.
-
-## Possible source-version follow-ups
-
-Independent collection or subtree specification policies were outside the
-completed shared source-version feature and remain possible future work, with
-no committed delivery plan. Current [source-version checks](../config.md#shared-source-version-checks)
-use one application-owned policy across participating documents. Reconsider
-independent policies if concrete consumer needs justify a separate design
-decision; this is not a permanent prohibition. The original request and its
-selected scope remain at `e4270c9:docs/roadmap/promptkit-feature-request.md` in
-Git history. Existing sequence-composition and cross-scope inheritance deferrals
-above also remain unchanged.
-
-## Deferred performance experiments
-
-The completed performance audit left these internal optimization candidates for
-separate investigation:
-
-- branch-local explanation replay instead of the current whole-tree replay;
-- redesigning the private metadata-copy handoff while preserving detached public
-  records;
-- caching schema descriptors across loads; and
-- indexing complex contributor-trace membership while preserving its equality
-  rules and compact linked traces.
-
-These are not committed implementation work. Reconsider them with evidence that
-the benefit justifies the ownership, retained-memory, or equivalence risks. The
-completed audit and implementation evidence are preserved in Git history at
-`8e91a2b` under `docs/roadmap/`.

docs/roadmap/future.md

@@ -2,8 +2,9 @@
 
 This document lists potential enhancements for consideration in future ConfigKit
 releases. Entries are not accepted contracts, implementation plans, or release
-commitments. [Deferred scope](deferred.md) remains the owner of current exclusions;
-adopting a candidate requires an explicit design decision and a separate plan.
+commitments. Adopting a candidate requires an explicit design decision and a
+separate plan. Significant architectural exclusions and their rationale belong
+in ADRs; this document does not maintain a list of rejected proposals.
 
 ## 1. Identified record sequences
 
@@ -130,3 +131,31 @@ compatible version or replace final configuration validation.
   reader, byte, and mapping inputs, glob matches, and repeated imports? Define
   behavior for absent optional inputs and preserve source-local diagnostics,
   inspection evidence, and existing sensitivity handling.
+
+## 3. Performance experiments
+
+Status: deferred pending evidence. The completed performance audit identified
+four internal optimization candidates for separate investigation:
+
+- Branch-local explanation replay instead of the current whole-tree replay.
+- Redesigning the private metadata-copy handoff while preserving detached public
+  records.
+- Caching schema descriptors across loads.
+- Indexing complex contributor-trace membership while preserving its equality
+  rules and compact linked traces.
+
+These are experiments, not committed implementation work or promised speedups.
+Reconsider them with evidence that the benefit justifies the ownership,
+retained-memory, or equivalence risks. The completed audit and implementation
+evidence are preserved in Git history at `8e91a2b` under `docs/roadmap/`.
+
+### Questions to resolve before implementation
+
+- Which representative workloads show enough remaining cost to justify each
+  optimization, and what measurements would establish a useful improvement?
+- Can narrower replay and membership indexes preserve explanation results,
+  ordering, provenance, and sensitivity behavior?
+- Can metadata handoff changes preserve detached public records and ownership
+  across loads without introducing aliasing?
+- What cache lifetime and concurrency design would make schema reuse worthwhile
+  without excessive retained memory?