Capture keyed prompts and source-backed content at load time

docs/internal/overview.md

@@ -17,7 +17,7 @@ contributor workflow and validation.
 | `examples/go-library/observe` | Demonstrates offline built-in HTTP retry and synchronous metadata observation across structured proposal and assessment runs using embedded sources, two profiles on one finite backend, and an application decision. It is not a public library package. | [Example program](../../examples/go-library/observe/main.go) |
 | `internal/backend` | Constructs each engine's immutable registry from maintained definitions and consumer additions, validates and defensively copies definitions through the shared JSON-value package, and consumes the LLM-owned OpenAI-compatible reserved request-field rule. | [Backend registry](../../internal/backend/registry.go) |
 | `internal/catalog` | Strictly validates imported immutable maintained backend and profile catalog assets before engine assembly uses them. | [Catalog adapter](../../internal/catalog/catalog.go), [internal sources](sources.md#profiles-and-built-ins) |
-| `internal/configuration` | Loads keyed backend, profile, and prompt configuration through ConfigKit, recording effective field presence and validating final backend/profile values. It is not yet connected to engine assembly. | [Typed loader](../../internal/configuration/load.go), [internal sources](sources.md#typed-configuration-loading) |
+| `internal/configuration` | Loads keyed backend, profile, and prompt configuration through ConfigKit; records effective field presence, validates final values, and captures indexed prompt definitions and referenced message content. It is not yet connected to engine assembly. | [Typed loader](../../internal/configuration/load.go), [internal sources](sources.md#typed-configuration-loading) |
 | `internal/capacity` | Owns engine-local bounded execution admission and FIFO model-generation permits for limited backend IDs, including cancellation-safe waiter removal and client wrapping. | [Internal capacity management](capacity.md) |
 | `internal/domain` | Defines internal framework values for requests, artifacts, prompt definitions, profiles, execution targets, rendering, generation, and validation, and owns source-neutral invariants for shared execution settings, OpenAI-compatible base endpoints, session identifiers, and output contracts. Source parsing, required fields, other source-specific normalization, defaulting, and boundary-specific error classification remain with their callers. | [Domain declarations](../../internal/domain/domain.go), [endpoint invariant](../../internal/domain/endpoint.go) |
 | `internal/engine` | Assembles external catalogs, Promptkit-owned profiles, repositories, registry, capacity, collaborators, repairer, and the one use-case runner for each engine instance. | [Engine assembly](../../internal/engine/engine.go), [internal sources](sources.md#profiles-and-built-ins), [internal runner](runner.md) |

docs/internal/sources.md

@@ -17,11 +17,16 @@ backend, profile, and prompt mappings. It performs one layered load, records
 effective field presence (including explicit null), normalizes backend and
 profile fields through ConfigKit resolution, and validates final backend and
 profile domain values. A lower-layer domain value replaced before the handoff
-is not separately validated. Its focused tests exercise real ConfigKit loading.
+is not separately validated. It also validates effective prompt fields, reads
+referenced message content using the contributing field's passive source
+context, checks static template syntax, and indexes immutable definitions by
+exact ID and version. Its focused tests exercise real ConfigKit loading.
 
 This loader is not yet wired into engine assembly. The public engine continues
-to use the source and repository behavior described below; prompt resource
-capture and full prompt validation are subsequent implementation work.
+to use the source and repository behavior described below. The public
+`DirectoryInputs` and `FilesystemInputs` helpers select sorted YAML inputs for
+one strict-composition group and attach an explicit resource root; they do not
+assign precedence or enable imports.
 
 ## Prompt Definitions
 

docs/roadmap/implementation.md

@@ -334,6 +334,8 @@ as migrated. Internal inventory documents only the loader now actually present.
 
 ## Stage 2 — Add Source Discovery And Prompt Resource Capture
 
+**Completed:** 2026-09-30.
+
 Scope: source selection helpers and construction-time prompt materialization.
 
 1. Implement private directory/FS discovery behind the chosen helper signatures;