Organize downstream feature requests in the future roadmap

docs/roadmap/future.md

@@ -33,9 +33,68 @@ consumers.
 
 ## Ideas
 
-No ideas are currently cataloged. Backend-specific concurrency management has
-been selected for active planning in the
-[focused concurrency roadmap](concurrency.md).
+### Executable preparation handles
+
+Allow a consumer to prepare one exact execution, inspect and retain its
+caller-owned preparation details, and later execute that already-prepared work
+without reloading or rerendering prompt, profile, schema, or input sources.
+This would remove the duplicate `Prepare`-then-`Run` workaround reported by
+[Notarius](notarius-promptkit-wishlist.md#priority-1-atomic-execution-with-prepared-details)
+and
+[Weatherreporter](weatherreporter-promptkit-wishlist.md#priority-1-executable-preparation-handles).
+
+- Keep the handle opaque, engine-bound, non-serializable, and initially
+  one-shot.
+- Keep existing `Prepare` and `Run` workflows available.
+- Return public preparation details under existing caller-ownership and
+  credential-redaction rules.
+- Perform backend admission when execution begins rather than reserving
+  capacity while a consumer retains the prepared handle.
+- Treat a separate atomic detailed-run method as possible later convenience
+  rather than a second initial execution model.
+
+### Prompt-independent profile inspection
+
+Provide exact profile lookup and structural resolution without requiring a
+synthetic prompt, placeholder inputs, or model generation. This shared need is
+described by
+[Notarius](notarius-promptkit-wishlist.md#priority-2-prompt-independent-profile-inspection)
+and
+[Weatherreporter](weatherreporter-promptkit-wishlist.md#priority-3-prompt-independent-profile-inspection).
+
+- Apply ordinary built-in, file-backed, and programmatic profile precedence.
+- Validate referenced backend membership and the structurally resolved
+  execution target.
+- Report credential requirements and environment-variable names without
+  exposing credential values or requiring current credential availability.
+- Support exact lookup by profile ID; enumeration is not required initially.
+
+### Prompt-definition inspection
+
+Provide exact prompt-definition lookup without rendering, placeholder inputs,
+profile resolution, or model generation, as requested by
+[Weatherreporter](weatherreporter-promptkit-wishlist.md#priority-2-prompt-definition-inspection).
+
+- Return caller-owned identity, version, input definitions, default-profile,
+  output-contract, and opaque definition-equality information.
+- Apply ordinary prompt-source precedence and exact ID/version selection.
+- Validate the selected definition and referenced prompt content
+  structurally, without returning source bodies or rendered messages.
+- Leave complete cross-source corpus validation and enumeration outside the
+  initial inspection contract.
+
+### Structured capacity errors
+
+Add safe structured context to backend admission rejection, as requested by
+[Notarius](notarius-promptkit-wishlist.md#priority-4-structured-capacity-errors)
+and
+[Weatherreporter](weatherreporter-promptkit-wishlist.md#structured-capacity-errors).
+
+- Preserve compatibility with `errors.Is(err, ErrCapacityExceeded)`.
+- Support `errors.As` to obtain the stable backend ID.
+- Do not expose endpoints, credential configuration or values, request
+  content, or speculative retry timing.
+- Keep retry and backoff policy with downstream consumers.
 
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