ConfigKit/docs/roadmap/promptkit-feature-request.md

PromptKit Feature Request: Mounted Collections And Specification Headers

Status:

• Input destinations are implemented on the ConfigKit development branch (placement baseline reviewed at 315f464).
• Relative import destinations have been accepted and implemented; the roadmap records their completed delivery.
• Source specification headers have been partially accepted in the shared application-version-policy form described below. This does not accept PromptKit's original independent collection-header semantics. Design and implementation of this addition remain separate from relative import work.

Requested Capability

Extend configuration loading with relative import destinations and opt-in checks that contributing sources declare a version accepted by the consumer's single configuration specification policy. Preserve the implemented capability to select a destination mapping path for each configuration input. The input's application content contributes beneath that path while retaining ConfigKit's normal composition, precedence, inheritance, validation, diagnostics, and inspection behavior.

PromptKit needs this capability for its proposal 3, Collections With Mounted Configuration Fragments, recorded in PromptKit's docs/roadmap/configuration-collections-mounted-fragments.md. This request describes the public API needs and observable acceptance criteria. It does not prescribe ConfigKit's internal design or an implementation plan. The disposition and revised source-version scope below supersede conflicting parts of PromptKit's original proposal.

The original request targeted ConfigKit v0.7.1. The development branch now supplies Input.Destination and SourceInfo.Destination, as documented in the input destination contract. The placement requirements below remain the baseline for the two additions. Current released behavior and development-branch behavior must not be confused with the newly proposed header and import syntax.

Consumer Problem

PromptKit applications assemble independently maintained collections of prompts, inference profiles, and backends. Collections can contain identical local names, such as summarize.alerts, without identifying the same resource. PromptKit wants an effective configuration organized by collection, while letting authors omit repeated collection and resource-container wrappers from individual files.

A file selected from a collection's prompts directory would contain:

summarize.alerts:
  version: "1"
  default_profile: provider/brief
  messages:
    - role: user
      content: Summarize the weather alerts.
  output:
    format: text
    validation_mode: none

Given destination [collections, weatherreporter, prompts], its contribution would appear in the final application configuration as:

collections:
  weatherreporter:
    prompts:
      summarize.alerts:
        version: "1"
        default_profile: provider/brief
        messages:
          - role: user
            content: Summarize the weather alerts.
        output:
          format: text
          validation_mode: none

Another collection can contribute summarize.alerts beneath [collections, homewatch, prompts] without conflicting. After final handoff, PromptKit interprets these as weatherreporter/summarize.alerts and homewatch/summarize.alerts. The profile reference is illustrative and must be supplied separately by the application configuration.

PromptKit will support one installed definition per prompt. Its optional flat version is ordinary domain metadata, not a merge identity. This request does not need identified-record sequences, sequence-root documents, or a custom merge policy.

Authors could write the complete wrappers today, but that repeats assembly details in every fragment. Consumer-side parsing and wrapping would put generic source processing back into PromptKit and complicate source attribution. PromptKit instead wants to select sources and destinations, then receive one final configuration through ConfigKit's supported loading lifecycle.

Implemented Placement API And Required Baseline

Per-Input Destination

The development branch provides Destination Path on each Input passed to LoadLayered, matching the original request. The following partial consumer example uses that implemented field, which was not available in v0.7.1:

promptInput := configkit.Input{
    Source: configkit.File("/usr/local/share/collections/weatherreporter/prompts/alerts.yml"),
    Destination: configkit.Keys("collections", "weatherreporter", "prompts"),
}

peers := configkit.Underlay{
    Inputs: []configkit.Input{promptInput},
}

The consumer would include peers in its existing LayeredOptions and invoke LoadLayered with its normal root main input and application Definition. This is a partial API sketch, not an executable example or a proposed new loading entry point. A single public layered load is sufficient for PromptKit; it does not require a separate mounting operation on completed results.

The API must let the consumer:

• Express a destination relative to the application configuration root using literal mapping-key segments. Dots, slashes, and numeric-looking text inside a key are not implicit path separators or array indexes. PromptKit's namespace grammar remains its own domain rule.
• Omit the destination to retain existing root placement. An explicitly empty destination should have the same meaning. Mapping destinations are sufficient; sequence-index destinations are not needed by this request.
• Assign different destinations to inputs in the same strict composition group, and assign the same destination to inputs in separate precedence groups.
• Use the destination with existing content-bearing source kinds: host files, native filesystem files, bytes, readers, and mapping sources, subject to their existing acquisition and ownership contracts.
• Retain the existing import opt-in and filesystem context independently of the destination. A configuration destination is not a filesystem root or base directory.

PromptKit can continue to enumerate an explicitly selected directory and attach the same destination to its returned inputs. ConfigKit does not need a new directory scanner, namespace registry, filename convention, or PromptKit schema. The namespace comes from the application's assembly declaration, not from an implicit interpretation of a directory basename.

Representative Assembly

These are application choices, not ConfigKit-specific reserved paths:

Selected inputs	Destination key segments
Application main document	Root
weatherreporter/collection.yml	collections, weatherreporter
YAML files under weatherreporter/prompts	collections, weatherreporter, prompts
YAML files under homewatch/prompts	collections, homewatch, prompts
YAML files under provider/profiles	collections, provider, profiles
YAML files under provider/backends	collections, provider, backends

Peer collection contributions belong to a single strict underlay group when the application wants conflict detection among them. Intentional operator overrides use later groups or main. Destination selection must not establish precedence or make source traversal order authorize replacement.

Required Observable Behavior

Composition And Precedence

Mounted and explicitly wrapped contributions must have equivalent application values and conflict behavior at their effective destinations. Actual source locations naturally differ and must remain accurate.

Retain the strict composition and layering rules:

• Disjoint mapping entries at the same destination combine.
• Overlapping non-mapping values within a strict group conflict, including equal scalars, nulls, and sequences. Different destinations do not collide merely because the source documents share a local key.
• Later precedence layers recursively override mappings and replace other values. A strict conflict cannot be repaired by an upper layer.
• Empty mappings do not clear lower definitions; ordinary arrays remain atomic. In particular, messages does not acquire sequence-merging behavior.
• Overlapping destination paths and contributions at their ancestors follow those same rules. No namespace-level uniqueness restriction is requested.

Changing only a prompt's version in a later layer changes that field while retaining omitted lower-layer fields. ConfigKit must not treat a domain version label as a request to replace an entire definition.

Imports And Existing Structural Directives

An input with imports enabled must be able to use its existing source-root configkit.imports directive while contributing application data at a nested destination. The directive remains structural configuration, not an application field below that destination.

When an import omits destination or supplies an empty list, it inherits its importing document's effective destination, including transitively. An explicit sequence appends to that destination. Import paths continue to resolve relative to their declaring source's filesystem context. A mounted document must not send its imported application fields back to the configuration root accidentally.

Existing opt-in, containment, missing-input, cycle, and repeated-source behavior must remain applicable. A different destination is not a request to bypass the current rejection of a repeated physical source within a strict group.

Sibling extends must resolve against mappings at their effective destinations. For example, two independently supplied profile fragments mounted beneath the same collection's profiles mapping can establish extends: brief once they compose. Inheritance remains ConfigKit-owned; PromptKit does not perform another relationship-resolution pass.

Protected Specification Paths

The distinction between source-local field names and effective application paths is essential. PromptKit's main document will declare version: 1 at the configuration root. A separate collection metadata file can contain:

version: "2.4.0"

Mounted at [collections, weatherreporter], that field is an ordinary collection release label. It must not be rejected as an attempt to contribute the protected root specification field. The same applies to a prompt's nested optional version. This describes the existing placement baseline, with no new source checks enabled. The partially accepted extension will reuse the application's VersionRule for source declarations; header lookup and its interaction with ordinary version payload remain design questions, not a guarantee that every source-local version stays unchecked.

Conversely, placement must not permit an underlay or imported fragment to claim or replace the actual protected specification path or an ancestor that would replace it. The public contract must define protection in terms of effective application paths, rather than reserving the spelling version in every source. Protection must remain valid with imports, inheritance, overlays, and explicit CLI overrides.

Retain existing behavior when the new source checks are not enabled. The accepted direction extends the same application version policy across source files, rather than assigning separate policies to collections. Its interaction with protected-path ownership and declaration retention must be designed explicitly; it does not implicitly authorize version-field contributions. PromptKit does not need main mounted away from the root or integer-to-string conversion for every nested ordinary version field.

Typed Loading, Diagnostics, And Inspection

The destination must be visible consistently through the ordinary public loading and inspection surface:

• Final typed configuration and application callbacks use effective destination paths. Defaults, resolution, and validation retain the existing single-load lifecycle; fragments are not independently validated as whole applications.
• Metadata and presence queries distinguish omission, explicit null, and other explicit values at the mounted paths.
• Diagnostics identify the effective conflicting or invalid path and the real contributing source locations. Consumers can determine which source and placement produced a value without recreating that relationship themselves.
• Effective rendering, explanations, history, and configuration comparison agree with the final configuration. Existing sensitivity and disclosure rules apply to mounted fields, including application path-based secret classification.
• Unsupported destination forms and destination-related loading failures use the normal structured error boundary. Exact new diagnostic codes, if needed, are for ConfigKit to define.

PromptKit does not require a separate mount registry or new inspection facade. Existing inspection APIs are sufficient if they expose accurate effective paths, source attribution, and placement information. ConfigKit should document how source-local locations relate to effective paths.

Source-Relative Resources And Lifecycle

For a mounted field such as content_file: ./summary.md, obtaining its effective origin and calling Result.SourceContext or Resolution.SourceContext must still identify the declaring source's filesystem and base directory. The same holds when that field survives an override or is inherited into another mapping. Its configuration destination must not change the meaning of the relative file reference.

Retain existing source ownership, load completion, result lifetime, containment, and resource-access behavior. Destinations must participate in documented load limits without creating a way to bypass them; this request does not prescribe new limit values or their accounting machinery.

Partially Accepted Addition: Shared Source Specification Checks

Status: the shared-policy portion below is implemented. Current behavior is defined by the configuration contract, and the accepted decision and implementation evidence are in ADR 0013 and the source-version roadmap.

Accepted Scope

A ConfigKit consumer defines one configuration specification, which may evolve through versions. Definition.Version identifies the declaration path and the consumer's checker determines which versions are acceptable. The accepted extension lets the consumer apply that same policy across the source files contributing to a configuration, rather than checking only the main declaration. It does not introduce independent collection or subtree specification policies.

The consumer can opt in with increasing strictness:

1. Current behavior: retain existing loading and version-checking behavior, including existing protected-path restrictions. No new source-header check.
2. Check declarations when present: a source that declares a version must satisfy Definition.Version; omission is allowed.
3. Require declarations: every participating source must declare a version that satisfies Definition.Version; omission is an error.

Acceptance is determined by the existing consumer-supplied checker, not by a new ConfigKit-owned expected string or automatic equality with the main file's declaration. A consumer may accept several compatible versions. A declaration rejected under the selected mode fails the attempted load through structured errors, with no usable partial result; a higher-precedence payload cannot turn an incompatible source declaration into an acceptable one.

This establishes that checked sources declare an accepted specification version. It does not prove that every fragment conforms to its declaration. Existing final decoding and application validation still determine the validity of the assembled configuration; fragments are not independently loaded as complete applications.

Difference From PromptKit's Original Proposal

PromptKit originally requested explicitly selected collection-entry rules, separate from Definition.Version, with ordinary imports exempt from independent checks. It also recommended consuming accepted entry headers and exposing them as source evidence while leaving imported release metadata untouched.

The independent collection-entry policies and exemption for ordinary imports were not accepted. The accepted direction instead uses one shared Definition.Version policy and optional or required declarations across participating sources. Separately versioned subsets or collections remain outside this addition's scope. Header consumption and sanitized source evidence, which were suggestions in the original proposal, were subsequently accepted for this shared-policy design and are implemented as described by the linked contract.

Design Questions Resolved by the Accepted Roadmap

The following questions were open in the original request and are resolved by the accepted roadmap and ADR 0013:

• How the configured declaration path is interpreted for individual sources, particularly before destination placement.
• Which source kinds and roles participate, including direct underlay inputs, transitive imports, and other contributions.
• Whether checked declarations are consumed or retained, how that interacts with composition and main-owned version protection, and what inspection evidence is exposed.
• How null and malformed declarations behave in each mode, preserving the distinction between absence and a present declaration and considering the existing string/decimal-integer version vocabulary.
• The opt-in API, callback lifecycle, and source-local diagnostic attribution.

In particular, an imported version: "2.4.0" at the configured source-local header path is checked and consumed in an enabled mode. Consumers that need an ordinary release label retain it at a different path. No automatic field consumption applies in the default mode, and no new coercion or per-collection checker is part of the implemented design.

Requested Addition: Relative Import Destinations

Disposition: accepted and implemented under the completed relative import destinations roadmap. The behavior below records the accepted capability; exact syntax and completion status follow that work, rather than implying a released feature.

Extend the public YAML import directive so a path or glob import can specify a relative destination as literal mapping-key segments. The roadmap selects destination as a sequence of strings, for example destination: [prompts].

The public behavior should be:

• The importing document has an effective destination established by its input or its own import. An explicit import destination appends key segments to that destination. Omission or an empty list retains the importing destination.
• Every file matched by a glob receives the same declared relative destination. Transitive imports are relative to their immediate importing document's resulting destination, not always to the original entry destination.
• Filesystem paths still resolve relative to the declaring file, with existing containment rules. Logical placement and physical file resolution are independent; there is no root-reset or parent-traversal meaning in destination key segments. Literal keys follow the same rules as Input.Destination.
• Imports retain their existing strict-composition tier. Import order and destination declarations do not create precedence or permit replacement.
• Existing optionality, repeated-source, cycle, source-kind, and ownership rules remain intact. A destination does not authorize importing one physical file twice in a group. Existing source-root directive and reserved-key rules apply.
• SourceInfo.Destination reports each import's resulting effective destination. Effective paths, original locations, resource contexts, protected version paths, sensitivity, and error behavior retain the placement baseline above.
• Invalid directive shapes fail through the normal structured error boundary; destination fields must not be silently ignored.

This is declarative access to the existing placement capability. It does not request recursive glob syntax, implicit directory scanning, namespace inference, or a new composition strategy.

Relative Import Collection Entry Example

An entry document selected by the application with destination [collections, weatherreporter] could describe its layout as follows. This example illustrates relative imports only and assumes no new source checks:

configkit:
  imports:
    - path: metadata.yml
    - glob: prompts/*.yml
      destination: [prompts]
    - glob: profiles/*.yml
      destination: [profiles]
    - glob: backends/*.yml
      destination: [backends]

This is proposed syntax, not currently executable configuration. Each required glob assumes matching files; collections can omit unused categories or use existing optional-import behavior. The application still selects and provisions the collection and assigns its namespace. ConfigKit does not discover it.

With current source-version behavior, metadata.yml can contain version: "2.4.0" as an ordinary mounted collection release label. Prompt fragments retain local mapping keys and optional prompt versions, and contribute beneath the collection's prompts mapping. The main application can retain its own version declaration. Enabling the proposed shared source checks may require changes to these files once declaration lookup and retention are defined.

Publishers can describe collection layout while applications select collections and destinations. The later shared-version feature will add opt-in declaration checking; it does not establish package authenticity or release integrity.

Deferred And Excluded Work

Identity-based list composition. Keep this deferred. Proposal 3's local mapping keys already identify each installed resource; the two requested additions do not require a different representation or sequence merge policy.

Cross-collection inheritance. Nested collection profiles are not immediate siblings across collections. Current sibling inheritance remains sufficient for the initial proposal, with authored definitions flattened where necessary. Generic cross-path inheritance could be considered separately if consumer needs justify revisiting the deferred scope. Mounting must not silently reinterpret extends: provider/brief as a cross-collection reference.

PromptKit also does not request collection installation, automatic directory discovery, remote fetching, namespace ownership enforcement, dependency solving, live reload, filename-derived identity, or arbitrary document transformations. Its qualified resource IDs, optional prompt version semantics, collection inventory, and execution APIs remain PromptKit responsibilities.

Public Acceptance Scenarios

Evaluate the implemented placement baseline and accepted relative-import extension through supported public loading and inspection APIs. Source-version rows below express the partially accepted direction; their unresolved details must be settled before they become implementation acceptance tests.

Scenario	Expected consumer-visible result
Destination omitted or empty	Existing root-placement behavior
Same fragment shape mounted under two distinct collection keys from independent sources	Two separate effective resources
Disjoint inputs at the same destination in one group	Mapping contributions combine
Equal or unequal overlapping scalar fields in one group	Structured composition conflict with both source locations
Same destination across deliberate precedence tiers	Existing recursive overlay behavior
Version-only prompt override	Label changes; omitted prompt body fields survive
Nested mounted import without a destination directive	Imported fields contribute at the inherited destination
Local profile inheritance across mounted peer fragments	Parent resolves at the effective sibling scope
Collection metadata containing version mounted below root, with new checks disabled	Existing ordinary nested-field behavior
Mounted/imported contribution actually targeting the protected version path	Rejected under version ownership rules
Mounted field using source-relative content, including inheritance	Original declaring resource context remains available
Mounted explicit null and omitted field	Distinct effective presence information
Mounted validation error or secret field	Effective paths, physical locations, and existing disclosure rules agree
File, native filesystem, byte, reader, or mapping input with equivalent content	Equivalent application values, subject to existing source contracts
Unsupported destination or failed load	Normal structured failure, no usable partial result
Source-version checks disabled	Existing version-checking and protected-path behavior
Check-when-present mode, declaration absent	Omission is allowed
Check-when-present mode, declaration present	Must satisfy the shared Definition.Version policy
Required mode, declaration absent	Structured load failure
Required mode, declaration present	Must satisfy the shared Definition.Version policy
Different declarations both accepted by the consumer checker	No additional exact-equality requirement
Rejected source declaration with payload superseded by a higher layer	Rejection still fails the load
Relative import destination omitted or empty	Existing inherited-destination behavior
Entry at [collections, weather], import at [prompts], nested import at [extras]	Nested contribution appears beneath [collections, weather, prompts, extras]
Glob import with a relative destination	Every matched contribution uses that destination and composes strictly
Relative import destination with source-relative resource	Effective configuration path changes; resource base remains the declaring source
Load without new source checks or relative import directives	Existing loading and main VersionRule semantics remain unchanged

The relative-import outcome is a consumer that selects entry sources and destinations, performs one ordinary layered load, and receives final typed configuration with reliable diagnostics and inspection. Entry documents describe their own relative import placements without consumer-side source rewriting, generic merging, or provenance reconstruction.

The separately scoped, partially accepted source-version extension adds optional or required declaration checking through the consumer's single Definition.Version policy. It does not require or authorize independently versioned collections.