feat: add {version} placeholder interpolation for URL-type sources

cmd/crd-schema-extractor/validate.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/spf13/cobra"
 
@@ -61,6 +62,12 @@ func validateRunE(cmd *cobra.Command, args []string) error {
 			if src.URL == "" {
 				errs = append(errs, fmt.Sprintf("source %s: url type requires 'url' field", src.Name))
 			}
+			if strings.Contains(src.URL, "{version}") && src.Version == "" {
+				errs = append(errs, fmt.Sprintf("source %s: url contains {version} placeholder but version is empty", src.Name))
+			}
+			if src.URL != "" && !strings.Contains(src.URL, "{version}") {
+				errs = append(errs, fmt.Sprintf("source %s: url must contain {version} placeholder to keep version in sync", src.Name))
+			}
 		case "":
 			errs = append(errs, fmt.Sprintf("source %s: missing 'type' field", src.Name))
 		default:

internal/fetcher/url.go

@@ -30,16 +30,18 @@ func (f *URLFetcher) Fetch(log zerolog.Logger, src source.Source) (*Result, erro
 		client = &http.Client{Timeout: httpTimeout}
 	}
 
+	resolvedURL := src.ResolvedURL()
+
 	var resp *http.Response
 	var lastErr error
 
 	for attempt := 1; attempt <= maxRetries; attempt++ {
-		log.Debug().Str("url", src.URL).Int("attempt", attempt).Msg("fetching manifest")
+		log.Debug().Str("url", resolvedURL).Int("attempt", attempt).Msg("fetching manifest")
 
 		var err error
-		resp, err = client.Get(src.URL)
+		resp, err = client.Get(resolvedURL)
 		if err != nil {
-			lastErr = fmt.Errorf("downloading %s: %w", src.URL, err)
+			lastErr = fmt.Errorf("downloading %s: %w", resolvedURL, err)
 			log.Warn().Err(err).Int("attempt", attempt).Int("max", maxRetries).Msg("fetch failed")
 			if attempt < maxRetries {
 				time.Sleep(retryInterval)
@@ -48,7 +50,7 @@ func (f *URLFetcher) Fetch(log zerolog.Logger, src source.Source) (*Result, erro
 		}
 		if resp.StatusCode != http.StatusOK {
 			resp.Body.Close()
-			lastErr = fmt.Errorf("downloading %s: HTTP %d", src.URL, resp.StatusCode)
+			lastErr = fmt.Errorf("downloading %s: HTTP %d", resolvedURL, resp.StatusCode)
 			log.Warn().Int("status", resp.StatusCode).Int("attempt", attempt).Int("max", maxRetries).Msg("fetch returned non-200")
 			if attempt < maxRetries {
 				time.Sleep(retryInterval)
@@ -67,9 +69,9 @@ func (f *URLFetcher) Fetch(log zerolog.Logger, src source.Source) (*Result, erro
 
 	data, err := io.ReadAll(resp.Body)
 	if err != nil {
-		return nil, fmt.Errorf("reading response from %s: %w", src.URL, err)
+		return nil, fmt.Errorf("reading response from %s: %w", resolvedURL, err)
 	}
 
-	log.Debug().Str("url", src.URL).Int("bytes", len(data)).Msg("manifest downloaded")
+	log.Debug().Str("url", resolvedURL).Int("bytes", len(data)).Msg("manifest downloaded")
 	return &Result{Data: data}, nil
 }

internal/fetcher/url_test.go

@@ -85,6 +85,33 @@ func TestURLFetcherRetryExhaustion(t *testing.T) {
 	}
 }
 
+func TestURLFetcherVersionInterpolation(t *testing.T) {
+	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.URL.Path != "/releases/download/v1.7.1/crds.yaml" {
+			t.Errorf("unexpected path: %s", r.URL.Path)
+			w.WriteHeader(http.StatusNotFound)
+			return
+		}
+		w.Write([]byte("interpolated"))
+	}))
+	defer srv.Close()
+
+	f := &URLFetcher{Client: srv.Client()}
+	result, err := f.Fetch(nopLog, source.Source{
+		Name:    "test-interp",
+		Type:    "url",
+		URL:     srv.URL + "/releases/download/{version}/crds.yaml",
+		Version: "v1.7.1",
+	})
+	if err != nil {
+		t.Fatalf("Fetch: %v", err)
+	}
+
+	if string(result.Data) != "interpolated" {
+		t.Errorf("Data = %q, want %q", string(result.Data), "interpolated")
+	}
+}
+
 func TestURLFetcherConnectionError(t *testing.T) {
 	// Use a URL that will fail to connect
 	f := &URLFetcher{Client: &http.Client{}}

internal/source/source.go

@@ -99,6 +99,13 @@ func LoadAll(dir string) (map[string][]Source, error) {
 	return result, nil
 }
 
+// ResolvedURL returns the source URL with {version} placeholders replaced
+// by the source's Version field value. If the URL contains no placeholders,
+// it is returned as-is.
+func (s Source) ResolvedURL() string {
+	return strings.ReplaceAll(s.URL, "{version}", s.Version)
+}
+
 // All returns a flat list of all sources across all API groups.
 func All(grouped map[string][]Source) []Source {
 	var all []Source

internal/source/source_test.go

@@ -227,6 +227,44 @@ func TestLoadMissingPath(t *testing.T) {
 	}
 }
 
+func TestResolvedURL(t *testing.T) {
+	tests := []struct {
+		name    string
+		src     Source
+		want    string
+	}{
+		{
+			name: "placeholder replaced",
+			src:  Source{URL: "https://github.com/org/repo/releases/download/{version}/crds.yaml", Version: "v1.7.1"},
+			want: "https://github.com/org/repo/releases/download/v1.7.1/crds.yaml",
+		},
+		{
+			name: "multiple placeholders replaced",
+			src:  Source{URL: "https://example.com/{version}/download/{version}/crds.yaml", Version: "v2.0.0"},
+			want: "https://example.com/v2.0.0/download/v2.0.0/crds.yaml",
+		},
+		{
+			name: "no placeholder returns url as-is",
+			src:  Source{URL: "https://example.com/crds.yaml", Version: "v1.0.0"},
+			want: "https://example.com/crds.yaml",
+		},
+		{
+			name: "empty url",
+			src:  Source{URL: "", Version: "v1.0.0"},
+			want: "",
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := tt.src.ResolvedURL()
+			if got != tt.want {
+				t.Errorf("ResolvedURL() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
 func TestAll(t *testing.T) {
 	grouped := map[string][]Source{
 		"a.example.com": {{Name: "a1"}, {Name: "a2"}},

source.schema.json

@@ -48,7 +48,7 @@
           "url": {
             "type": "string",
             "format": "uri",
-            "description": "Direct URL to a YAML manifest containing CRDs. Required when type is url."
+            "description": "Direct URL to a YAML manifest containing CRDs. Required when type is url. Supports {version} placeholder which is replaced with the version field value before fetching."
           },
           "version": {
             "type": "string",