style: suppress gosec G703/G704 taint false positives with justification

The v2.12.2 gosec ruleset's new path-traversal (G703) and SSRF (G704)
taint checks flag os.Stat/os.Remove/os.Rename calls on paths that are
never attacker-controlled: our own temp files created immediately
before in the same function, content-hash- or cache-key-derived
storage paths, the operator-supplied config search path, and the
already SSRF-guarded upstream fetch (protected by ssrfSafeDialer at
the transport layer). Each suppression carries the rule ID and a
one-line justification, matching this repo's existing gosec nolint
convention in internal/imgcache/storage.go. No behavior change.

internal/config/config.go

@@ -299,7 +299,7 @@ func (c *Config) ensureStateDirWritable() error {
 			keyStateDir, probePath, err)
 	}
 
-	err = os.Remove(probePath)
+	err = os.Remove(probePath) //nolint:gosec // G703: our own probe file, not user input
 	if err != nil {
 		return fmt.Errorf("config key %q: cannot remove probe file %q: %w",
 			keyStateDir, probePath, err)
@@ -411,6 +411,7 @@ func loadConfigFile(log *slog.Logger, appName string) (*smartconfig.Config, erro
 	for _, path := range configPaths {
 		cleanPath := filepath.Clean(path)
 
+		//nolint:gosec // G703: config path is operator-supplied by design
 		_, statErr := os.Stat(cleanPath)
 		if statErr == nil {
 			// A config file that exists but does not parse is a fatal

internal/handlers/imageenc.go

@@ -66,6 +66,7 @@ func (s *Handlers) HandleImageEnc() http.HandlerFunc {
 
 			return
 		}
+
 		defer func() { _ = resp.Content.Close() }()
 
 		// Set response headers

internal/httpfetcher/httpfetcher.go

@@ -198,6 +198,7 @@ func (f *HTTPFetcher) Fetch(ctx context.Context, url string) (*FetchResult, erro
 
 	// If we fail before returning a result, release the slot
 	success := false
+
 	defer func() {
 		if !success {
 			<-sem
@@ -232,6 +233,7 @@ func (f *HTTPFetcher) Fetch(ctx context.Context, url string) (*FetchResult, erro
 
 	startTime := time.Now()
 
+	//nolint:gosec // G704: dialer enforces SSRF protection (ssrfSafeDialer)
 	resp, err := f.client.Do(req)
 
 	fetchDuration := time.Since(startTime)

internal/httpfetcher/httpfetcher_internal_test.go

@@ -237,6 +237,7 @@ func TestMockFetcher_FetchesFile(t *testing.T) {
 	if err != nil {
 		t.Fatalf("Fetch() error = %v", err)
 	}
+
 	defer func() { _ = result.Content.Close() }()
 
 	if result.ContentType != contentTypeJPEG {

internal/imgcache/service.go

@@ -315,6 +315,7 @@ func (s *Service) fetchAndProcess(
 
 		return nil, fmt.Errorf("upstream fetch failed: %w", err)
 	}
+
 	defer func() { _ = fetchResult.Content.Close() }()
 
 	// Read and validate the source content

internal/imgcache/storage.go

@@ -94,22 +94,23 @@ func (s *ContentStorage) Store(r io.Reader) (ContentHash, int64, error) {
 	_, err = tmpFile.Write(data)
 	if err != nil {
 		_ = tmpFile.Close()
-		_ = os.Remove(tmpPath)
+		_ = os.Remove(tmpPath) //nolint:gosec // G703: our own temp file, not user input
 
 		return "", 0, fmt.Errorf("failed to write content: %w", err)
 	}
 
 	err = tmpFile.Close()
 	if err != nil {
-		_ = os.Remove(tmpPath)
+		_ = os.Remove(tmpPath) //nolint:gosec // G703: our own temp file, not user input
 
 		return "", 0, fmt.Errorf("failed to close temp file: %w", err)
 	}
 
 	// Atomic rename
+	//nolint:gosec // G703: tmp file is ours, path is derived from content hash
 	err = os.Rename(filepath.Clean(tmpPath), filepath.Clean(path))
 	if err != nil {
-		_ = os.Remove(tmpPath)
+		_ = os.Remove(tmpPath) //nolint:gosec // G703: our own temp file, not user input
 
 		return "", 0, fmt.Errorf("failed to rename temp file: %w", err)
 	}
@@ -253,22 +254,23 @@ func (s *MetadataStorage) Store(
 	_, err = tmpFile.Write(data)
 	if err != nil {
 		_ = tmpFile.Close()
-		_ = os.Remove(tmpPath)
+		_ = os.Remove(tmpPath) //nolint:gosec // G703: our own temp file, not user input
 
 		return fmt.Errorf("failed to write metadata: %w", err)
 	}
 
 	err = tmpFile.Close()
 	if err != nil {
-		_ = os.Remove(tmpPath)
+		_ = os.Remove(tmpPath) //nolint:gosec // G703: our own temp file, not user input
 
 		return fmt.Errorf("failed to close temp file: %w", err)
 	}
 
 	// Atomic rename
+	//nolint:gosec // G703: tmp file is ours, path is derived from cache key
 	err = os.Rename(filepath.Clean(tmpPath), filepath.Clean(path))
 	if err != nil {
-		_ = os.Remove(tmpPath)
+		_ = os.Remove(tmpPath) //nolint:gosec // G703: our own temp file, not user input
 
 		return fmt.Errorf("failed to rename temp file: %w", err)
 	}
@@ -410,22 +412,23 @@ func (s *VariantStorage) Store(
 	_, err = tmpFile.Write(data)
 	if err != nil {
 		_ = tmpFile.Close()
-		_ = os.Remove(tmpPath)
+		_ = os.Remove(tmpPath) //nolint:gosec // G703: our own temp file, not user input
 
 		return 0, fmt.Errorf("failed to write content: %w", err)
 	}
 
 	err = tmpFile.Close()
 	if err != nil {
-		_ = os.Remove(tmpPath)
+		_ = os.Remove(tmpPath) //nolint:gosec // G703: our own temp file, not user input
 
 		return 0, fmt.Errorf("failed to close temp file: %w", err)
 	}
 
 	// Atomic rename content
+	//nolint:gosec // G703: tmp file is ours, path is derived from cache key
 	err = os.Rename(filepath.Clean(tmpPath), filepath.Clean(path))
 	if err != nil {
-		_ = os.Remove(tmpPath)
+		_ = os.Remove(tmpPath) //nolint:gosec // G703: our own temp file, not user input
 
 		return 0, fmt.Errorf("failed to rename temp file: %w", err)
 	}