feat(sidekick): capture discovery revision (#2605)

Discovery docs include a revision, this is useful to include in the
documentation, and may help with IBV.

Author: coryan

internal/sidekick/internal/api/model.go

@@ -138,8 +138,11 @@ type API struct {
 	PackageName string
 	// The API Title (e.g. "Secret Manager API" or "Cloud Spanner API").
 	Title string
-	// The API Description
+	// The API Description.
 	Description string
+	// The API Revision. In discovery-based services this is the "revision"
+	// attribute.
+	Revision string
 	// Services are a collection of services that make up the API.
 	Services []*Service
 	// Messages are a collection of messages used to process request and

internal/sidekick/internal/parser/discovery/discovery.go

@@ -38,6 +38,7 @@ func NewAPI(serviceConfig *serviceconfig.Service, contents []byte, cfg *config.C
 		Name:        doc.Name,
 		Title:       doc.Title,
 		Description: doc.Description,
+		Revision:    doc.Revision,
 		Messages:    make([]*api.Message, 0),
 		State: &api.APIState{
 			ServiceByID: make(map[string]*api.Service),
@@ -111,6 +112,7 @@ type document struct {
 	Version           string             `json:"version"`
 	Title             string             `json:"title"`
 	Description       string             `json:"description"`
+	Revision          string             `json:"revision"`
 	RootURL           string             `json:"rootUrl"`
 	MTLSRootURL       string             `json:"mtlsRootUrl"`
 	ServicePath       string             `json:"servicePath"`

internal/sidekick/internal/parser/discovery/discovery_test.go

@@ -49,20 +49,14 @@ func TestInfo(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	wantName := "compute"
-	wantTitle := "Compute Engine API"
-	wantDescription := "Creates and runs virtual machines on Google Cloud Platform. "
-	if got.Name != wantName {
-		t.Errorf("want = %q; got = %q", wantName, got.Name)
+	want := &api.API{
+		Name:        "compute",
+		Title:       "Compute Engine API",
+		Description: "Creates and runs virtual machines on Google Cloud Platform. ",
+		Revision:    "20250810",
 	}
-	if got.Title != wantTitle {
-		t.Errorf("want = %q; got = %q", wantTitle, got.Title)
-	}
-	if diff := cmp.Diff(wantDescription, got.Description); diff != "" {
-		t.Errorf("mismatch (-want +got):\n%s", diff)
-	}
-	if got.PackageName != "" {
-		t.Errorf("expected empty package name")
+	if diff := cmp.Diff(want, got, cmpopts.IgnoreFields(api.API{}, "State", "Services", "Messages", "Enums")); diff != "" {
+		t.Errorf("mismatch (-want, +got):\n%s", diff)
 	}
 }
 
@@ -76,21 +70,19 @@ func TestServiceConfigOverridesInfo(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	if got.Name != sc.Name {
-		t.Errorf("want = %q; got = %q", sc.Title, got.Title)
+	want := &api.API{
+		Name:        sc.Name,
+		Title:       sc.Title,
+		Description: sc.Documentation.Summary,
+		Revision:    "20250810",
+		PackageName: "google.cloud.secretmanager.v1",
 	}
-	if got.Title != sc.Title {
-		t.Errorf("want = %q; got = %q", sc.Title, got.Title)
-	}
-	if diff := cmp.Diff(sc.Documentation.Summary, got.Description); diff != "" {
-		t.Errorf("mismatch (-want +got):\n%s", diff)
+	if diff := cmp.Diff(want, got, cmpopts.IgnoreFields(api.API{}, "State", "Services", "Messages", "Enums")); diff != "" {
+		t.Errorf("mismatch (-want, +got):\n%s", diff)
 	}
 	if len(sc.Apis) != 2 {
 		t.Fatalf("expected 2 APIs in service config")
 	}
-	if got.PackageName == "" {
-		t.Errorf("got empty package name")
-	}
 	if !strings.HasPrefix(sc.Apis[1].Name, got.PackageName) {
 		t.Errorf("mismatched package name want = %q, got = %q", sc.Apis[1].Name, got.PackageName)
 	}

internal/sidekick/internal/rust/templates/common/README.md.mustache

@@ -39,6 +39,14 @@ GitHub repository.
 
 {{{.}}}
 {{/Description}}
+{{!
+    Discovery-doc based APIs include a revision.
+    Publishing the information is useful for troubleshooting.
+}}
+{{#Revision}}
+
+This client library was generated from the "{{Revision}}" revision of the API.
+{{/Revision}}
 {{#Codec.ReleaseLevelIsGA}}
 
 The client library types and functions are stable and not expected to change.

internal/sidekick/internal/rust/templates/crate/src/lib.rs.mustache

@@ -19,6 +19,14 @@ limitations under the License.
 {{/Codec.BoilerPlate}}
 
 //! Google Cloud Client Libraries for Rust - {{{Title}}}
+{{!
+    Discovery-doc based APIs include a revision.
+    Publishing the information is useful for troubleshooting.
+}}
+{{#Revision}}
+//!
+//! This client library was generated from the "{{Revision}}" revision of the API.
+{{/Revision}}
 //! {{^Codec.ReleaseLevelIsGA}}
 //!
 //! **FEEDBACK WANTED:** We believe the APIs in this crate are stable, and