ConfigKit/docs/roadmap/consolidation.md

# ConfigKit Consolidation Toward 1.0

Status: proposed scope and target state for review. This document recommends
refactors; it does not record implementation progress or authorize a release.
Prepare the staged implementation plan after reviewing this roadmap.

## Purpose

Consolidate the machinery introduced by recent import, collection, inheritance,
and discovery work so ConfigKit is easier to understand, maintain, and adopt
before its public contracts become stable. Success means fewer independently
maintained paths through the same behavior, clearer state ownership, and concise
consumer workflows. Reducing a function's line count is useful only when it
serves those outcomes.

The review considered public API consolidation as well as internal extraction.
The recommended scope retains the existing simple and layered loading APIs,
consolidates their private translation and acquisition machinery, and removes
unused reverse inspection conversions. No public signature or configuration
semantic change is currently recommended. This is an assessment of the reviewed
consumer workflows, not a requirement to preserve every beta API in perpetuity.

## Evidence And Relationship To Existing Work

Reviewed worktree: `c9574ef`, immediately after the `v0.10.0` release at `5959537`.
The inputs are the earlier [complexity roadmap](complexity.md), whose reviewed
baseline predates discovery, and the new [complexity audit](remediation.md).
The older roadmap already acknowledges implemented discovery, but its selected
work is narrower than this proposal.

This review inspected the current public load/input/discovery declarations and
maintained consumer examples, the shared request executor and acquisition flow,
import parsing and selection, inheritance execution, reflective projection and
cloning, schema field construction, and filesystem-context derivation. Graph
caller traces and text-reference checks confirmed the unused reverse conversion
chain. This was source review, not a new runtime correctness or performance audit.
The audit's complexity scores locate candidates; they are not standardized
acceptance thresholds or evidence of a runtime defect.

| Audit finding | Assessment and recommended treatment |
| --- | --- |
| 1. Import entry points and responsibilities | Main refactor. Include shared acquisition normalization, import-default ownership, declaration parsing, and directory admission. |
| 2. Shared inheritance executor | Main refactor. Expose meaningful phases and explicit combination results while retaining one executor. |
| 3. Projection and cloning | Main refactor for projection; bounded follow-up for substantial clone handlers, preserving the distinction between the operations. |
| 4. Schema field discovery and inline assembly | Include a focused refactor coordinated with projection. Keep one schema builder and its two descriptor views. |
| 5. Resolved filesystem context | Include alongside acquisition work. Reuse resolved facts without merging resource lifetimes or changing validation timing. |
| 6. Unused reverse inspection conversions | Include as an independent cleanup in the root facade and engine. Retain useful forward-conversion and detached-result coverage. |

This is the combined proposal for scope review, rather than a second independent
implementation of the earlier roadmap. Keep the audit as evidence; its findings
are not closed by adopting this document. Completed correctness and algorithmic
remediations remain part of the baseline, including sequence records preserved
at `ea46001:docs/roadmap/remediation.md` and discovery records preserved at
`0369111:docs/roadmap/remediation.md`.

The [architecture policy](../policy/architecture.md),
[configuration contract](../config.md), and exported declaration comments own
existing constraints and behavior. The
[component overview](../internal/overview.md) and
[import internals](../internal/imports.md) locate implementation responsibilities.

## Consumer-Facing Target

### Keep Simple Loading Simple And Advanced Inputs Explicit

The current APIs already provide progressive setup:

- A simple consumer calls `Load[Config](File(path))`.
- A consumer with defaults, imports, or resolution supplies `Options[Config]`.
- Explicit discovery produces an ordinary `Source`, so it uses the same loading
  call and lifecycle.
- A layered consumer supplies an `Input` and `LayeredOptions[Config]`, with
  `Underlay.Inputs` distinguishing strict peers from precedence tiers.

The two loading functions already converge on `loadRequest` and
`executeLoadRequest`. Their public differences have meaning: ordinary options
include the one input's controls; layered loading has per-input controls and a
separate overlay filesystem. Ordinary overlay context follows its selected
source, whereas layered overlay context is independently specified. These are
observable conventions, not interchangeable forwarding spellings.

**Recommendation:** retain `Load`, `LoadLayered`, `Options`, `LayeredOptions`,
`Input`, and `Underlay`. Remove repeated translation and option reconstruction
behind them. Keep common application rules in `Definition`; do not require
applications to build a runtime loader or manually coordinate phases.

A single public request type could place main input, underlays, and common
options together. It would reduce duplicated option fields and make promotion
from ordinary to layered loading more uniform. However, a sole request-based
entry would add setup to the simplest call; retaining a convenience entry would
still leave two call forms. Either approach must explicitly resolve the existing
overlay-context differences. The maintained examples do not yet show enough
consumer benefit to justify that redesign. This recommendation is based on the
resulting API, rather than the amount of refactoring needed to achieve it.

### Preserve Useful Convenience And Ownership Boundaries

| Surface reviewed | Recommended public end state |
| --- | --- |
| `Source`, `Filesystem`, `Search`, filename groups and presets | Retain typed, reusable source/search descriptions. Discovery selects a concrete source during loading; applications do not loop over complete loads. |
| `FilesystemContext` | Retain the public description and current host/native rules. Consolidate its resolved private representation; do not expose acquisition handles or engine context records. |
| `SequenceIdentityAt` and `SequenceIdentityMatching` | Retain the exact-path convenience and dynamic selector form over the common registration model. Both serve distinct consumer shapes. |
| `Definition`, resolution and validation callbacks | Retain application-owned domain rules inside one recorded lifecycle. Preserve the distinction between mutable recorded resolution and read-only validation. |
| Results, metadata, explanations, source context and diff | Retain detached, safe inspection with consumer-owned presentation. Remove unused inverse conversions without removing supported queries. |
| Root wrappers and private conversions | Retain root-owned public types and explicit ownership conversion under ADR 0006. Consolidate repeated real conversions and delete unused ones. |

The consumer-facing work is to make the ordinary path easier to find and show
how additional features compose, using the existing maintained examples. Update
the adoption guide with a concise choice between simple loading, discovery, and
layered loading, and show which options belong to an input versus a whole load.
Keep exact behavior in its canonical owners. Examples should make application
rules recognizable and avoid requiring consumers to recreate generic merging,
presence, or provenance machinery.

Use the current simple README call, bundled-file and layered catalog examples,
the import-focused prompt catalog, and the discovered sequence catalog to assess
the end state. The latter exercises imports, underlays, independent overlay
context, CLI assignment, and recorded resolution in one workflow. A high number
of options in that example does not by itself justify a new abstraction.

## Internal Target

Keep the root facade, cohesive `internal/engine`, ordered document model, and
private YAML adapter. Use ordinary private records, functions, and focused files
to express responsibilities. Existing mapping combination, sequence combination,
dependency scheduling, schema descriptors, and traversal accounting remain shared.

`executeLoadRequest` stays the visible lifecycle coordinator. It should show
acquisition, assembly, inheritance, decoding/CLI assignment, resolution, secret
processing, validation, and publication in their established order. Extract a
phase only when it gives that work a clear input, output, or ownership boundary.
Do not replace the visible lifecycle with a registry of configurable stages.

### 1. Normalize Loading Inputs And Consolidate Import Acquisition

The current executor constructs an engine `Options[T]` from `loadRequest`, and
underlay acquisition constructs `Options[struct{}]` to call the same input
assembler. `assembleBaseInputTrackedForRole` then combines discovery, directive
processing, version rules, imports, placement, accounting, and contexts. Import
entry points carry long positional lists through several forwarding variants.
This repeats the representation of information already normalized for a load.

Introduce cohesive private acquisition inputs and explicit state ownership,
reusing `loadRequest`, `loadInput`, `acquisitionScope`, and `importTraversal`
where they fit. Translate ordinary and layered public declarations into the
shared loading model once. Acquisition should receive the source, input role,
placement, context, and policies it needs without a fabricated application type
or a reconstructed broad options object. Small adapters may preserve meaningful
entry operations while callers migrate; remove obsolete forwarding variants
within the completed refactor.

Separate immutable policy, mutable processing state, and results. Move import
defaults out of `sourceVersionState` and into the load/acquisition policy owner.
Version state continues to own version processing, projected effective version
location, evidence, and diagnostics. Local and effective version rules have
different meanings and must remain distinguishable.

The state boundaries are especially important:

| Lifetime or scope | State and responsibility |
| --- | --- |
| Whole load | Aggregate resource accounting, application definition/registrations, import defaults, shared version evidence and diagnostics. |
| One strict tier | Repetition tracking shared by that tier's inputs, namespace scheduling anchors, and its inclusion/composition graph relationship. A later tier may reuse a file. |
| Active import traversal | Active routes and inclusion edges, filesystem access ownership, and cycle detection, including edges crossing item-scope boundaries. |
| One composition scope | Peer contributions, pending collection declarations, item-local helpers, and deferred item placement. Nested scopes do not become separate precedence tiers. |
| Retained result | Source records, effective destinations, origins, history, and passive resource-context descriptions. |

The older roadmap's broad description of load-wide repetition state should not
be implemented as a global visited-file restriction. In the current code,
`acquireUnderlayGroupScopes` creates a fresh visited map per group. Preserve valid
reuse across tiers while keeping shared aggregate limits. Namespace equality,
candidate spelling, and stable scheduling keys also serve different purposes.

Give acquisition, already-acquired scope assembly, and evidence projection
focused homes. Keep discovery at the acquisition boundary: resolve a search once
per input consumption, then process the concrete file or absence. Preserve
source IDs and source-local version processing in acquisition order, even when
composition uses a different dependency-ready order. The layered main is acquired
before underlays; lower-tier identity can still inform its later strict assembly.

Within import parsing, extract boolean/collection/placement field handling and
selector-value parsing where it clarifies responsibilities. Keep field presence,
authored error locations, selector applicability, and the order of consequential
validation visible. Within directory selection, separate entry admission and
descent decisions from traversal orchestration. Retain the existing root
deduplication, candidate union, exclusions, sorting, and active-path cycle rules.
No shared abstraction should conflate literal first-match main discovery with
multi-file import selection.

### 2. Share Resolved Filesystem Facts Without Sharing Live Handles

`importFilesystem`, `nativeFilesystemAccess`, and `contextsForAcquiredSources`
derive overlapping root/base/namespace facts. The latter reconstructs context
from combinations of source kind and optional fields, including absent input.
Discovery and independent layered overlays make these combinations consequential.

Use a small engine-owned resolved-context description for the facts actually
needed by acquisition and passive views: namespace identity/kind, resolved root,
source base, and selected source path when present. Preserve the distinction
between host paths and native slash paths. Reuse already resolved facts where
available instead of repeatedly deriving them from the original options.

Resolution and validation can occur at different existing lifecycle points.
The record must not force every source to perform all filesystem checks early.
Context descriptions, library-owned acquisition handles, and returned passive
resource views have different lifetimes. Closing acquisition must remain
explicit on success and failure; retaining context must not retain an open root
handle or assume ownership of a borrowed `fs.FS`.

Cover selected and absent discovery outcomes, root-only absent host context,
native sources, in-memory inputs with explicit context, and independently rooted
overlays. Passive context remains associated with the source that contributed
the value, including retained underlay and inherited values. Use the acquired
source's canonical identity where available. Preserve containment failures,
source associations, deferred search bases, and terminal selected-file errors.

Implement this work alongside acquisition consolidation so the same callers are
not redesigned twice. The description is private; it does not replace the public
`FilesystemContext` or `ResourceContext` contracts.

### 3. Make Inheritance Combination Results Explicit

Keep the mapping and identified-record adapters and one shared executor.
`applyInheritanceScopeTemplates` currently prepares templates, mutates values
through merge callbacks, projects policy and origins, records replacements and
replay evidence, and enforces budgets in one body. The callbacks mutate several
surrounding result collections, making a combination difficult to review alone.

Give the executor named operations for child/control preparation, parent payload
and policy preparation, combination, evidence construction, and retained-node
accounting. Use a small private result for outputs of one combination where it
replaces unrelated surrounding mutations. Value, policy, origin, replacement,
and sequence-position evidence should come from the same combination outcome;
do not rerun a merge to reconstruct its history.

Keep borrowed authored templates separate from owned resolved payloads and from
retained history snapshots. Parent identity exclusion and child identity/origin
preservation must apply consistently to values and history. Preserve nested
unresolved instructions for destination-local evaluation, policy retirement on
actual replacement, cancellation, and source-version movement through sequences.

The shared Kahn scheduler with stable keys remains unchanged. Resolve enclosing
relationships before nested relationships and retain assembled record order.
Preserve expansion limits and retained-history accounting for shared nodes;
extraction must not charge shared evidence twice or make an unbounded snapshot.

### 4. Separate Projection Handlers And Clarify Schema Assembly

Keep `projectConfiguration` as the schema-checked entry and `valueOperation` as
the operation-state owner. Move substantial struct, map, and sequence projection
into focused handlers. Keep pointer/dynamic dispatch and scalar representation
choices visible. All handlers share the same cycle, depth, and node state.

Struct projection needs particular care: physical members drive traversal,
flattened fields drive name lookup and sensitivity, and an inline container is
not retained as an extra output node. Preserve declaration order, deterministic
map order, nil/empty distinctions, collision diagnostics, codec failures, and
secret classification. Keep cycle entries active through child traversal and
balance their release on every exit.

In `schemaBuilder.describeFields`, separate field discovery and tag parsing from
inline struct assembly, inline map assembly, and ordinary field registration.
Retain one builder/cache and its recursion detection. Make the paired updates to
`members`, flattened `fields`, `fieldByName`, and `inlineMap` easy to follow.
Keep index-path construction and inherited secret flags intact. These descriptor
views are both needed; combining them into one collection would shift complexity
into decoding and projection.

Follow with a bounded cleanup of substantial clone handlers where it makes their
ownership behavior easier to read. Keep cloning distinct from projection:
cloning reconstructs typed values, preserves physical fields, round-trips text
codecs, and distinguishes unresolved from already validated secret state.
Projection builds a canonical document and charges output nodes. Extract common
helpers only where the semantics actually agree. The mostly explicit dispatch
in `decodeValue` and `valueBuilder.build` does not warrant a generic reflection
visitor solely because it has a high complexity score.

### 5. Remove Unused Inspection Conversions And Consolidate Real Adapters

Remove `toEngineSourceInfo`, `toEngineOrigin`, the exclusive reverse version and
import-selection converters, and the engine adapters used only by that chain.
At the reviewed revision, the three callers of `toEngineSourceInfo` are tests;
`toEngineOrigin` has none. `SourceInfoWithPlacement`,
`SourceInfoWithImportSelections`, and their exclusive string-to-enum helpers
have no production role beyond that reverse chain. Recheck callers at the
implementation baseline before removal.

Rewrite the affected record tests around real engine-to-public conversion and
detached public inspection. Preserve useful placement, version evidence,
import-selection, and copy-isolation assertions. Avoid manufacturing replacement
production setters solely to keep an old round-trip fixture working. Existing
facade loads already provide genuine sources and inspection records.

Retain reverse conversions that serve real inputs: `toEngineDiagnostics`, for
example, supports `WriteDiagnostics`. Consolidate repeated override/input
conversion in `toEngineOptions` and `toEngineLayeredOptions` where semantics
match. Keep explicit root-to-engine ownership conversion and the public-boundary
checks. A reflective transport framework or public engine aliases would obscure
the boundary rather than simplify it.

## Scope, Compatibility, And Policy Consequences

The proposed work spans private engine code, private root-facade conversions,
affected tests, consumer guidance, and implementation documentation. This is a
deliberate expansion beyond the older engine-only roadmap. Preserve public
types/signatures and the behavior owned by the current contracts, including:

- Acquisition versus composition ordering, strict scopes versus precedence
  tiers, identity ownership, placement, and source-version protection.
- Discovery exhaustion and error behavior, source lifetime, passive resource
  contexts, and host/native namespace distinctions.
- Defaults, post-decode CLI assignment, recorded resolution, secret handling,
  final registered-identity enforcement, and semantic validation.
- Explicit presence, provenance/history, sensitivity, safe diagnostics and diff,
  frozen inspection, and detached publication/query results.
- Contracted diagnostic codes, paths, coordinates, ordering, and resource limits.

Do not turn incidental helper order, exact private representations, numerical
complexity scores, or allocation counts into new guarantees. Keep the existing
algorithmic remediations effective; watch for repeated whole-tree traversals,
policy scans, or copies introduced by helper extraction.

The recommendation fits the existing architecture policy and ADRs 0006,
0015, 0017, 0018, and 0019. It needs no new architectural ownership decision or
policy revision merely to introduce private helpers. Update the component
overview and import internals when code moves. Accepted ADR decision content
remains unchanged. If review selects a materially different public loading model,
assess its behavioral consequences explicitly before implementation.

Pre-1.0 public changes are possible under the [release policy](../policy/release.md),
but they must have a consumer benefit and documented impact. This draft does not
propose a parallel compatibility API or temporary migration scaffold. It also
does not make refactoring completion a new release gate or establish that 1.0
is otherwise ready. Future performance experiments remain in
[future.md](future.md#3-performance-experiments); no benchmark campaign was run
or is required to claim readability improvements.

## Recommended Work Order

This is dependency guidance for the later plan, not a commit-by-commit schedule:

1. Confirm the reviewed revision and public-surface direction; map the retained
   behavior to existing tests and record concrete coverage gaps.
2. Remove unused reverse inspection conversions and adjust their tests. This is
   small and independently reviewable.
3. Normalize acquisition inputs and separate import-default ownership. Develop
   the resolved-context handoff with those callers, preserving validation and
   closure timing; then separate acquisition, item assembly, and evidence work.
4. Refactor inheritance around explicit preparation and combination results,
   retaining completed correctness and algorithmic regressions.
5. Refactor projection and schema field assembly in separate reviewable changes;
   complete the bounded clone cleanup where it improves the remaining flow.
6. Consolidate real facade adapters, finish consumer/internal navigation, and run
   the applicable integration and ownership checks on the combined result.

Steps 4 and 5 have no necessary implementation dependency on each other. Keep
correctness fixes discovered during refactoring identifiable with their own
regression evidence rather than hiding behavior changes inside code movement.

## Validation And Completion

Use the [development guide](../development.md) and
[testing policy](../policy/testing.md) for focused checks and the ordinary full
development check. Preserve existing behavior tests; rewrite tests coupled only
to removed plumbing. Add a test when a consequential handoff risk lacks coverage,
not for every new helper.

| Work area | Existing protection and review focus |
| --- | --- |
| Acquisition and imports | Selection, defaults, scheduling, relative/item placement, source-version evidence, aggregate limits, repetition within versus across tiers, and ordinary/layered equivalence. |
| Resolved contexts | Host/native access, discovery selected/absent outcomes, terminal context failures, source-relative resources, independent overlay context, and handle closure. |
| Inheritance | Mapping and record inheritance, nested destination-local evaluation, child identity, policy lifetime, version movement, history ordering, sensitivity, and retained-node budgets. |
| Projection/schema/clone | Inline fields, recursive schemas, dynamic values, nil/empty values, cycles and limits, text codecs, secret states, callback ownership, and independent loads. |
| Facade and consumers | Forward conversion, detached records, supported API boundaries, source-form equivalence, maintained simple/catalog/discovery examples, and safe explanation/diff. |

Examples of established boundaries include
[source-form equivalence](../../facade_equivalence_test.go),
[discovery integration](../../facade_discovery_test.go),
[final identity validation](../../facade_final_sequence_identity_test.go),
[inheritance history](../../internal/engine/inheritance_history_test.go), and
[projection and cloning](../../internal/engine/projection_test.go).
Use applicable race checks when changing ownership or shared state. Reuse checks
for unchanged content and keep benchmark work separate unless new evidence
justifies it and it is authorized.

Completion requires reviewable evidence that:

- Simple and advanced consumer examples remain concise and valid, with no new
  public concepts required for existing workflows.
- Both load entry points reach one normalized internal model; acquisition no
  longer reconstructs broad options or uses version state to transport defaults.
- Import, context, inheritance, and reflection responsibilities have identifiable
  owners and explicit handoffs without duplicate semantic implementations.
- Unused reverse conversions and their exclusive adapters are removed, with
  useful inspection ownership coverage retained.
- Contracted values, presence, provenance/history, diagnostics, sensitivity,
  resource lifetime, and algorithmic corrections remain protected by appropriate
  tests and source review.
- The reviewed scope is accounted for against all six audit findings; completed
  findings have validation evidence rather than being closed because code moved.
- Consumer guidance, contributor references, and internal documentation describe
  the resulting implementation. Current contracts continue to own behavior.

Private type/helper names, final file splits, and exact stage boundaries belong
in the implementation plan. The public-surface recommendation and scope above
are ready for review; no additional feature semantics are needed to carry out
the recommended refactors.