Fix linting issues and improve JSON output

Code Quality Fixes:
- Fixed prealloc warnings by pre-allocating slices with capacity
- Fixed gofmt formatting issues across multiple files
- Fixed errcheck issues by explicitly handling or ignoring errors
- Reduced cyclomatic complexity in getScriptVersion by extracting helper functions

JSON Output Improvements:
- Skip AgentPipe logo/banner when --json flag is used
- Ensures clean JSON-only output for programmatic usage
- Applies to all commands with --json flag

All tests pass with race detector.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: kevinelliott

cmd/agents.go

@@ -14,11 +14,11 @@ import (
 )
 
 var (
-	installAll      bool
-	listInstalled   bool
-	listOutdated    bool
-	listCurrent     bool
-	listJSON        bool
+	installAll    bool
+	listInstalled bool
+	listOutdated  bool
+	listCurrent   bool
+	listJSON      bool
 )
 
 // agentsCmd represents the agents command
@@ -32,7 +32,7 @@ Examples:
   agentpipe agents install claude    # Install Claude CLI
   agentpipe agents install --all     # Install all agents`,
 	Run: func(cmd *cobra.Command, args []string) {
-		cmd.Help()
+		_ = cmd.Help()
 	},
 }
 
@@ -122,7 +122,7 @@ func runAgentsList(cmd *cobra.Command, args []string) {
 	showVersionInfo := listCurrent
 
 	// Filter agents based on flags
-	var filteredAgents []*registry.AgentDefinition
+	filteredAgents := make([]*registry.AgentDefinition, 0, len(agents))
 	for _, agent := range agents {
 		installed := isAgentInstalled(agent.Command)
 
@@ -556,7 +556,7 @@ func runAgentsUpgrade(cmd *cobra.Command, args []string) {
 
 // outputAgentsJSON outputs agent list in JSON format
 func outputAgentsJSON(agents []*registry.AgentDefinition, showVersionInfo bool) {
-	var jsonAgents []AgentListJSON
+	jsonAgents := make([]AgentListJSON, 0, len(agents))
 
 	for _, agent := range agents {
 		installed := isAgentInstalled(agent.Command)
@@ -625,15 +625,15 @@ func outputAgentsJSON(agents []*registry.AgentDefinition, showVersionInfo bool)
 // outputOutdatedJSON outputs agent version information in JSON format
 func outputOutdatedJSON(rows []agentVersionRow) {
 	type OutdatedAgentJSON struct {
-		Name          string `json:"name"`
-		Installed     bool   `json:"installed"`
-		CurrentVer    string `json:"current_version"`
-		LatestVer     string `json:"latest_version"`
-		HasUpdate     bool   `json:"has_update"`
-		CanCheckVer   bool   `json:"can_check_version"`
+		Name        string `json:"name"`
+		Installed   bool   `json:"installed"`
+		CurrentVer  string `json:"current_version"`
+		LatestVer   string `json:"latest_version"`
+		HasUpdate   bool   `json:"has_update"`
+		CanCheckVer bool   `json:"can_check_version"`
 	}
 
-	var jsonAgents []OutdatedAgentJSON
+	jsonAgents := make([]OutdatedAgentJSON, 0, len(rows))
 	for _, r := range rows {
 		jsonAgents = append(jsonAgents, OutdatedAgentJSON{
 			Name:        r.name,

cmd/root.go

@@ -40,10 +40,11 @@ Claude, Gemini, and Qwen, allowing them to communicate in a shared "room".`,
 }
 
 func Execute() {
-	// Skip logo for doctor --json command for clean JSON output
+	// Skip logo for --json commands for clean JSON output
 	shouldSkipLogo := false
-	if len(os.Args) >= 2 && os.Args[1] == "doctor" {
-		for _, arg := range os.Args[2:] {
+	if len(os.Args) >= 2 {
+		// Check if --json flag is present anywhere in args
+		for _, arg := range os.Args[1:] {
 			if arg == "--json" {
 				shouldSkipLogo = true
 				break

internal/registry/registry_test.go

@@ -139,12 +139,12 @@ func TestGetUpgradeCommand(t *testing.T) {
 
 func TestIsInstallable(t *testing.T) {
 	tests := []struct {
-		name         string
-		wantInstall  bool
+		name        string
+		wantInstall bool
 	}{
-		{"Claude", true},      // npm install
-		{"Ollama", true},      // brew install (darwin) or curl script
-		{"Amp", true},         // npm install
+		{"Claude", true}, // npm install
+		{"Ollama", true}, // brew install (darwin) or curl script
+		{"Amp", true},    // npm install
 	}
 
 	for _, tt := range tests {

internal/registry/version.go

@@ -168,6 +168,20 @@ func getGitHubLatestRelease(repoName string) (string, error) {
 
 // getScriptVersion fetches version from a shell script that contains VER= definition
 func getScriptVersion(scriptURL string) (string, error) {
+	scriptContent, err := fetchScriptContent(scriptURL)
+	if err != nil {
+		return "", err
+	}
+
+	version, err := extractVersionFromScript(scriptContent)
+	if err != nil {
+		return "", err
+	}
+
+	return version, nil
+}
+
+func fetchScriptContent(scriptURL string) (string, error) {
 	client := &http.Client{
 		Timeout: 10 * time.Second,
 	}
@@ -187,46 +201,69 @@ func getScriptVersion(scriptURL string) (string, error) {
 		return "", fmt.Errorf("failed to read script: %w", err)
 	}
 
-	// Look for VER="x.y.z" or DOWNLOAD_URL patterns in the script
-	scriptContent := string(body)
+	return string(body), nil
+}
+
+func extractVersionFromScript(scriptContent string) (string, error) {
 	lines := strings.Split(scriptContent, "\n")
 	for _, line := range lines {
 		line = strings.TrimSpace(line)
 
 		// Check for VER="x.y.z" pattern
-		if strings.HasPrefix(line, "VER=") {
-			version := strings.TrimPrefix(line, "VER=")
-			version = strings.Trim(version, "\"'")
-			if version != "" {
-				return version, nil
-			}
+		if version := extractVERPattern(line); version != "" {
+			return version, nil
 		}
 
-		// Check for DOWNLOAD_URL with version in path (e.g., /2025.10.17-e060db4/)
-		if strings.HasPrefix(line, "DOWNLOAD_URL=") {
-			url := strings.TrimPrefix(line, "DOWNLOAD_URL=")
-			url = strings.Trim(url, "\"'")
-
-			// Extract version from URL path like /2025.10.17-e060db4/
-			// Split by / and look for version-like segments
-			parts := strings.Split(url, "/")
-			for _, part := range parts {
-				// Look for date-based versions (YYYY.MM.DD-hash) or semantic versions
-				if strings.Contains(part, ".") && (containsDigit(part) || strings.Contains(part, "-")) {
-					// Skip common non-version parts
-					if part != "${OS}" && part != "${ARCH}" && part != "darwin" && part != "linux" &&
-					   part != "x64" && part != "arm64" && !strings.HasSuffix(part, ".tar.gz") &&
-					   !strings.HasSuffix(part, ".zip") {
-						return part, nil
-					}
-				}
-			}
+		// Check for DOWNLOAD_URL with version in path
+		if version := extractVersionFromDownloadURL(line); version != "" {
+			return version, nil
 		}
 	}
 
 	return "", fmt.Errorf("no VER or DOWNLOAD_URL version found in script")
 }
 
+func extractVERPattern(line string) string {
+	if strings.HasPrefix(line, "VER=") {
+		version := strings.TrimPrefix(line, "VER=")
+		version = strings.Trim(version, "\"'")
+		return version
+	}
+	return ""
+}
+
+func extractVersionFromDownloadURL(line string) string {
+	if !strings.HasPrefix(line, "DOWNLOAD_URL=") {
+		return ""
+	}
+
+	url := strings.TrimPrefix(line, "DOWNLOAD_URL=")
+	url = strings.Trim(url, "\"'")
+
+	parts := strings.Split(url, "/")
+	for _, part := range parts {
+		if isVersionLikePart(part) && !isExcludedPart(part) {
+			return part
+		}
+	}
+
+	return ""
+}
+
+func isVersionLikePart(part string) bool {
+	return strings.Contains(part, ".") && (containsDigit(part) || strings.Contains(part, "-"))
+}
+
+func isExcludedPart(part string) bool {
+	excludedParts := []string{"${OS}", "${ARCH}", "darwin", "linux", "x64", "arm64"}
+	for _, excluded := range excludedParts {
+		if part == excluded {
+			return true
+		}
+	}
+	return strings.HasSuffix(part, ".tar.gz") || strings.HasSuffix(part, ".zip")
+}
+
 // getManifestVersion fetches version from a JSON manifest with "latest" field
 func getManifestVersion(manifestURL string) (string, error) {
 	client := &http.Client{
@@ -395,12 +432,12 @@ func CompareVersions(v1, v2 string) (int, error) {
 		if i < len(parts1) {
 			// Extract numeric part only
 			numStr := extractNumericPrefix(parts1[i])
-			fmt.Sscanf(numStr, "%d", &p1)
+			_, _ = fmt.Sscanf(numStr, "%d", &p1)
 		}
 
 		if i < len(parts2) {
 			numStr := extractNumericPrefix(parts2[i])
-			fmt.Sscanf(numStr, "%d", &p2)
+			_, _ = fmt.Sscanf(numStr, "%d", &p2)
 		}
 
 		if p1 < p2 {