Add runtime version reporting

docs/development.md

@@ -42,10 +42,10 @@ Run the offline Go test suite from the repository root with:
 go test ./...
 ```
 
-The implemented package inventory currently contains only the root
-`releasekit` facade package. Its public operations are added as their behavior is
-implemented; see the [implementation plan](roadmap/implementation.md) for
-current progress.
+The implemented package inventory currently contains the root `releasekit`
+facade and `buildinfo` runtime facade, plus the `cmd/releasekit` executable.
+Orchestration operations are added as their behavior is implemented; see the
+[implementation plan](roadmap/implementation.md) for current progress.
 
 For prose changes, review the diff and check local links, fragment destinations,
 provenance, template residue, and consistency with current repository contents.

docs/roadmap/implementation.md

@@ -456,7 +456,7 @@ LGPL licensing and attribution notices remain consistent.
 
 ## Stage 2: Implement the runtime version facade
 
-Status: Pending. Depends on Stage 1.
+Status: Complete. Depends on Stage 1.
 
 1. Implement `buildinfo.Version` and its internal injected-string and main-module
    fallback logic. Keep runtime state private and the public accessor small.
@@ -470,6 +470,15 @@ Acceptance: a source-built fixture reports `dev`; a fixture linked with a stable
 version reports that version. Fallback metadata uses the executable main module.
 CLI version output is correct and no runtime orchestration initialization occurs.
 
+Completion evidence: implemented `buildinfo.Version`, its private injected
+string and main-module fallback, and the internal linker-symbol contract. Unit
+tests cover injection precedence and missing, development, and stable main
+module metadata. Built and ran a separate consumer executable from source and
+with an injected stable version using network-disabled Go commands; both
+reported the selected value. CLI tests cover its version line, and the CLI's
+dependency closure contains no orchestration package. Added runtime consumer
+guidance and documented the command contract.
+
 ## Stage 3: Protect public contracts and dependency direction
 
 Status: Pending. Depends on Stage 2.

docs/runtime.md

@@ -0,0 +1,24 @@
+# Runtime version
+
+Applications can read their embedded version through the public `buildinfo`
+package:
+
+```go
+import "gitea.maximumdirect.net/eric/ReleaseKit/buildinfo"
+
+version := buildinfo.Version()
+```
+
+`Version` returns the identifier injected into the executable when present.
+Otherwise it returns the executable's main module version when that metadata is
+available and is not `(devel)`. It returns `dev` when neither source provides a
+release identifier. Applications should use this accessor for version output;
+the runtime implementation and ReleaseKit's builder own the injection detail.
+
+ReleaseKit's current command prints its own runtime version:
+
+```sh
+go run ./cmd/releasekit version
+```
+
+The output has the form `releasekit <version>`.