Record accepted import architecture decisions

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# ADR 0015: Share Dependency-Ready Ordering Across Imports and Inheritance
## Status
Accepted.
## Date
2026-10-19
## Context
Imports and sibling inheritance both resolve relationships between configuration
contributions. Their existing resolvers use different traversal rules, making
ordering depend on which mechanism expresses a dependency. Ordering affects
sequence contributions, provenance, and diagnostics, so a consistent rule is
part of ConfigKit's configuration model.
The resolvers also serve distinct purposes. Imports strictly compose sources;
inheritance overlays a child on its resolved parent after source assembly.
Item-local contributions and nested inheritance introduce scope boundaries that
resolution must preserve.
## Decision
ConfigKit owns one shared dependency-ready scheduler for imports and sibling
inheritance. Both resolvers use Kahn's algorithm with a stable ordering key,
selecting the smallest currently eligible node after its dependencies have
completed. The shared scheduler owns eligibility, deterministic tie-breaking,
and dependency-cycle identification. Each resolver owns construction of its
dependency relationships and application of its domain operations.
Apply the common scheduling rule within the scopes where dependencies are
available. Complete item-local contributions before item placement and resolve
enclosing inheritance before relationships in the resulting nested scopes.
Source discovery supplies the import graph; the scheduler determines resolution
order.
Strict composition, inheritance overlay, and precedence tiers retain their
existing ownership and meanings under [ADR 0001](0001-separate-composition-and-overlay.md).
The lifecycle and scope decisions in
[ADR 0009](0009-sibling-inheritance.md) continue to govern inheritance. Import
admission retains its cycle and repeated-source rules.
## Alternatives Considered
- **Deterministic depth-first postorder.** Keeps dependency branches together,
but gives traversal branch selection an additional role in ordering.
- **Dependency rounds.** Groups nodes by readiness rounds, but delays newly
eligible nodes until the current round finishes.
- **Descending longest-path depth.** Prioritizes the furthest dependencies,
but adds distance from the root as an ordering policy.
- **Separate resolver algorithms.** Allows local specialization, but leaves
consumers and maintainers with different rules for analogous dependencies.
## Consequences
Both resolvers follow one deterministic ordering model and share responsibility
for maintaining that model. Resolver-specific scopes, combination semantics,
and source-admission rules remain explicit at their integration boundaries.
Independent branches may interleave as nodes become eligible. Adopting this
rule changes existing traversal-dependent sequence positions and reporting
order, requiring coordinated review of source assembly, provenance, and
inheritance behavior. The configuration contract owns the implemented ordering
details.

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# ADR 0016: Separate Import Selection, Traversal, and Presence Requirements
## Status
Accepted.
## Date
2026-10-19
## Context
Consumers assemble configurations from named files and collections whose layout
varies between installations. Simple imports should require little setup, while
larger collections need control over discovery, recursion, filtering, and
required contributions. Combining those choices implicitly makes declarations
harder to interpret and pushes source-selection work into applications.
Discovery can also reach a candidate through overlapping searches or encounter
different names for one canonical source. Selection and source admission need
distinct identities to support useful search unions while preserving ConfigKit's
existing source-integrity rules.
## Decision
ConfigKit owns import discovery and selection within its source-loading
lifecycle. Support explicit files, directory searches, and path globs as
distinct selection forms. Keep traversal, filename filtering, and presence
requirements independently expressible. Discovery determines the selected
contributions; the shared scheduler in
[ADR 0015](0015-shared-dependency-ready-ordering.md) determines their resolution
order.
Use optional-by-default imports with explicit requiredness controls. Selected
sources remain subject to ConfigKit's validity, containment, resource, and
composition contracts. This applies the library's
[simplicity and defaults principles](../policy/architecture.md#simplicity-defaults-and-explicit-controls)
to import absence while retaining meaningful errors for invalid contributions.
Applications own their selected import defaults. Authored declaration values
take precedence over application defaults, which take precedence over library
defaults. Each declaration resolves applicable controls independently,
including declarations in imported sources. This gives applications a shared
baseline while preserving explicit choices in individual declarations.
Keep declaration-local candidate identity separate from canonical source
identity. Search unions coalesce repeated candidate paths within a source
namespace before symlink resolution; filename filtering uses the selected or
discovered name. Source admission continues to use canonical identity and the
existing repeated-source rules. Distinct aliases retain their separate
inclusion routes.
## Alternatives Considered
- **Use path globs for all discovery.** Offers one selection form, but makes
collection traversal depend on path-pattern structure and complicates
independently controlling recursion and filename filtering.
- **Offer only explicit files and directory searches.** Reduces the selector
vocabulary, but moves wildcard directory selection into repeated declarations
or application-side discovery.
- **Require every import by default.** Detects absent contributions immediately,
but requires repeated opt-outs for installations with optional components.
- **Make application settings override authored declarations.** Provides central
enforcement, but prevents declarations from expressing local exceptions.
- **Deduplicate selections globally by canonical source identity.** Coalesces
aliases and separate inclusion routes, but changes the existing repeated-source
contract and obscures independently authored contributions.
## Consequences
Consumers can express simple imports and more selective collection searches
through the same loading lifecycle. Applications choose defaults and validate
their required effective configuration; ConfigKit owns consistent selection,
source admission, composition, and inspection.
Optional absence can conceal misspelled selectors, so requiredness and
inspection provide explicit ways to detect and explain missing contributions.
Declaration-local deduplication requires the loader to preserve candidate
identity alongside canonical source identity. The configuration and public API
contracts own the implemented behavior.

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# Import Ergonomics And Permissive Defaults
Status: working draft / brainstorming notes. This document captures a proposed
direction for discussion, not an implemented contract or an implementation plan.
Status: accepted design; implementation pending. This document captures planned
behavior and requirements. Implementation sequencing remains to be prepared.
The selected direction separates directory searches, filename matching,
recursion, and absence handling. Optional-by-default imports are the intended
direction. The consumer-directed and Ansible-aligned decisions below are settled;
API spelling and implementation details remain for implementation planning.
All new syntax below is illustrative and unimplemented.
The durable architectural decisions are recorded in
[ADR 0015: Share Dependency-Ready Ordering Across Imports and Inheritance](../adr/0015-shared-dependency-ready-ordering.md)
and
[ADR 0016: Separate Import Selection, Traversal, and Presence Requirements](../adr/0016-independent-import-controls.md).
This roadmap owns implementation status and the detailed requirements for
carrying out those accepted decisions.
## Guiding Philosophy
ConfigKit should provide predictable configuration mechanisms and avoid imposing