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@@ -43,6 +43,11 @@ boundary and constraints that framework work must preserve.
 
 ## Release Guidance
 
+The [v0.16.0 release notes](docs/releases/v0.16.0.md) cover explicit smoke
+diagnostics, configuration collections, scoped engine views, and discovery.
+Upgrading consumers should review the breaking changes to bundled configuration
+and prompt version selection and follow the linked migration guide.
+
 The [v0.15.0 release notes](docs/releases/v0.15.0.md) cover error-only
 validation of concrete requests with `Engine.ValidateRequest`.
 
diff --git a/docs/releases/v0.16.0.md b/docs/releases/v0.16.0.md
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+# Promptkit v0.16.0
+
+This release adds explicit smoke diagnostics, configuration collections,
+namespace-scoped engine views, and expanded resource discovery. It also makes
+intentional breaking changes to configuration ownership and prompt selection.
+The minimum supported Go version remains 1.26.0.
+
+## Configuration Collections And Discovery
+
+Applications can compose caller-selected collections of backends, profiles,
+and prompts. Collection resources have qualified identities such as
+`support/answer`; root resources retain unqualified identities. `CollectionInput`
+provides a convenience for mounting a selected ConfigKit input into a collection.
+Promptkit now uses ConfigKit v0.8.0, including its optional source specification
+header support.
+
+`Engine.WithNamespaces` creates an immutable view with separate prompt, profile,
+and backend scopes for short caller-supplied IDs. Views share the underlying
+configuration, clients, capacity pools, and prepared-execution owner. Explicitly
+qualified IDs and configured references keep their exact identities.
+
+`ListProfiles` and `ListPrompts` support namespace filters. New `ListBackends`,
+`ListNamespaces`, and `ListCollections` methods expose captured resource and
+collection inventories. See the [collection format](../formats.md#source-headers-collections-and-resource-ids),
+[scoped-view guide](../consumers/pkg-promptkit.md#use-scoped-engine-views), and
+[discovery guide](../consumers/pkg-promptkit.md#discover-available-resources-and-collections).
+
+## Explicit Smoke Diagnostics
+
+`Engine.SmokeTest` provides backend reachability, authentication, text inference,
+and structured-output inference diagnostics. Reports provide factual
+observations, timing, and available usage rather than an overall readiness
+verdict. Optional Boolean facts distinguish negative observations from unknown
+or inapplicable checks; matching a JSON schema does not prove that a provider
+enforced it.
+
+A concluded diagnostic can report failure with a nil Go error. Invalid requests
+return ordinary errors, and caller cancellation can return partial observations
+with a recognizable context error. Diagnostics can contact providers and incur
+inference costs only when explicitly invoked; they are not automatic execution
+or release checks. See the [smoke diagnostic guide](../consumers/pkg-promptkit.md#run-explicit-smoke-diagnostics)
+and [API GoDoc](../../smoke_diagnostics.go).
+
+## Breaking Changes And Upgrade
+
+Consumers upgrading from v0.15.0 should follow the
+[configuration and API migration guide](../consumers/configuration-migration.md):
+
+- Supply backend and profile definitions explicitly. Promptkit no longer bundles
+  provider catalogs or the `promptkit-openrouter-standard` and
+  `promptkit-openrouter-auto` profiles. Conventional backend names do not install
+  definitions automatically. Applications choose and maintain their sources.
+- Convert version-keyed prompt mappings into one definition per prompt ID.
+  Prompt `version` is now an optional descriptive label, not a selector.
+  Choose deliberately which former definition to install.
+- Remove `PromptVersion` selectors from `RunRequest`,
+  `RequirementInspectionRequest`, and `SmokeTestRequest`, where applicable.
+  Change prompt inspection calls to `InspectPrompt(ctx, promptID)`. Update code
+  consuming version-bearing inspection, identity, result, or observation fields
+  to handle optional labels, including nil and explicitly empty labels.
+- When moving resources into collections, update stored backend, profile, and
+  diagnostic-default references to their intended qualified IDs. Mounting a
+  source does not rewrite references; profile inheritance remains within its
+  sibling mapping. Root configuration `version`, when supplied, is now a source
+  specification header, distinct from descriptive resource labels.
+
+The migration guide includes identity mappings and before/after prompt examples.
+The [maintained offline example](../../examples/go-library/prepare/main.go)
+demonstrates explicit composition, source-relative content, scoped preparation,
+and inventory without contacting a provider.
+
+After adapting configuration and API calls:
+
+```sh
+go get gitea.maximumdirect.net/eric/promptkit@v0.16.0
+```
+
+## Correctness And Efficiency
+
+Collection prompt materialization shares one lazy origin-metadata snapshot,
+avoiding repeated full metadata copies across collections. Internal prepared
+snapshots detach optional prompt labels. Smoke diagnostics preserve caller
+cancellation and report actual inference destinations and known-zero usage when
+no generation request was dispatched.
+
+[COPYRIGHT](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.16.0/COPYRIGHT) | [LICENSE](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.16.0/LICENSE) | [ATTRIBUTION](https://gitea.maximumdirect.net/eric/promptkit/src/tag/v0.16.0/docs/oss/attribution.md)