Publish effective LLM backend provenance

docs/integrations/json-output.md

@@ -98,6 +98,21 @@ summarize results without embedding lane payload bytes. A chunk-plan summary is
 provenance for the plan used by this run; cache records, debug artifacts, and
 other operational state are not published as bundle files.
 
+Each `llm_profiles` entry identifies effective, non-secret LLM execution
+provenance:
+
+| Field | Required | Meaning |
+| --- | --- | --- |
+| `id` | Yes | Selected PromptKit profile identifier. |
+| `provider` | No | Notarius adapter provider identifier. |
+| `model` | No | Effective provider model identifier. |
+| `backend_id` | No | Effective PromptKit backend registration identifier. Endpoint-only profiles omit it. |
+| `reasoning_effort` | No | Effective opaque provider reasoning setting. An empty or explicitly cleared setting is omitted. |
+
+These values describe observed execution; they are not a backend-registration
+interface. Entries that differ by backend or effective reasoning remain
+distinct even when their profile, provider, and model are otherwise equal.
+
 ## Rejections And Warnings
 
 `rejected.json` is always an object with a `rejected` array. Each entry has

docs/integrations/pkg-promptkit.md

@@ -17,7 +17,7 @@ Notarius relies on the root `promptkit` package to:
 - prepare and run a `RunRequest` with named inline artifacts, variables,
   a direct session ID, prompt identity, and profile selection;
 - return rendered debug material, validated structured output, selected
-  profile and model metadata, and token usage;
+  profile, backend, effective model metadata, and token usage;
 - distinguish structured-output validation failure from execution failure; and
 - identify a missing explicit profile through `ErrProfileNotFound`.
 
@@ -33,6 +33,13 @@ the same value as the `session_id` prompt variable for maintained prompt
 compatibility. Session IDs are stable, non-secret correlation identifiers and
 may be exposed to providers and provider observability.
 
+Notarius records PromptKit's selected backend ID and effective reasoning
+setting as optional run-manifest provenance. Endpoint-only profiles have no
+backend ID. Debug prompt material also retains the selected backend ID and
+PromptKit's stable lower-case `effective_model_params` JSON, which may include
+`backend_id`. Notarius production configuration does not expose user-defined
+PromptKit backend registration.
+
 ## Notarius Ownership
 
 [LLM Runtime Internals](../internal/llm.md) describes how Notarius mounts