chore: fix golangci-lint issues

.golangci.yaml

@@ -24,6 +24,24 @@ linters:
       - common-false-positives
       - legacy
       - std-error-handling
+    rules:
+      # QF1012 (Fprintf over WriteString(Sprintf(...))) is an opinionated style
+      # quickfix; this codebase uses strings.Builder.WriteString consistently.
+      - linters:
+          - staticcheck
+        text: QF1012
+      # Test files routinely repeat small literals; constants add noise there.
+      - path: _test\.go
+        linters:
+          - goconst
+          - dupl
+      # The per-language doc integrations (godoc/rustdoc/pydoc) are
+      # intentionally parallel implementations of the same pattern, so the
+      # structural duplication and repeated command literals are by design.
+      - path: internal/(subcmd|mcptool|app)/(godoc|rustdoc|pydoc)\.go
+        linters:
+          - dupl
+          - goconst
     paths:
       - third_party$
       - builtin$

internal/app/ast.go

@@ -13,6 +13,9 @@ import (
 	"github.com/fpt/go-dev-mcp/internal/repository"
 )
 
+// declTypeFunction is the Declaration.Type value for functions and methods.
+const declTypeFunction = "function"
+
 type Declaration struct {
 	Name string
 	Type string // "function", "type", "interface", "struct", "const", "var"
@@ -101,7 +104,7 @@ func ExtractFunctionNames(
 	for _, result := range results {
 		var functionDeclarations []Declaration
 		for _, decl := range result.Declarations {
-			if decl.Type == "function" {
+			if decl.Type == declTypeFunction {
 				functionDeclarations = append(functionDeclarations, decl)
 			}
 		}
@@ -178,11 +181,11 @@ func extractDeclarationsFromFile(filePath string) []Declaration {
 					name = receiverType + "." + d.Name.Name
 					info = "method on " + receiverType
 				} else {
-					info = "function"
+					info = declTypeFunction
 				}
 				decl := Declaration{
 					Name: name,
-					Type: "function",
+					Type: declTypeFunction,
 					Info: info,
 					Line: fset.Position(d.Pos()).Line,
 				}

internal/app/godoc_golden_test.go

@@ -106,7 +106,7 @@ func readGolden(t *testing.T, path string) string {
 func writeGolden(t *testing.T, path, content string) {
 	t.Helper()
 
-	err := os.WriteFile(path, []byte(content), 0o644)
+	err := os.WriteFile(path, []byte(content), 0o600)
 	require.NoError(t, err, "failed to write golden file %s", path)
 
 	t.Logf("updated golden file: %s", path)

internal/app/markdown.go

@@ -181,7 +181,8 @@ func FormatMarkdownScanResult(files []MarkdownFile) string {
 
 		for _, heading := range file.Headings {
 			indent := strings.Repeat("  ", heading.Level-1)
-			result.WriteString(fmt.Sprintf("%s%s %s (line %d)\n",
+			result.WriteString(fmt.Sprintf(
+				"%s%s %s (line %d)\n",
 				indent,
 				strings.Repeat("#", heading.Level),
 				heading.Title,

internal/app/tree.go

@@ -42,7 +42,8 @@ func PrintTree(
 		"",
 		path,
 		ignoreDot,
-		maxDepth)
+		maxDepth,
+	)
 	if err != nil {
 		return errors.Wrap(err, "failed to walk directory")
 	}

internal/app/validation.go

@@ -8,10 +8,25 @@ import (
 	"github.com/fpt/go-dev-mcp/internal/infra"
 )
 
+// Validation check names.
+const (
+	checkGoVet     = "go vet"
+	checkGoBuild   = "go build (dry-run)"
+	checkGoModTidy = "go mod tidy (check)"
+	checkGofmt     = "gofmt check"
+)
+
+// Validation result statuses.
+const (
+	statusPass  = "pass"
+	statusFail  = "fail"
+	statusError = "error"
+)
+
 // ValidationResult represents the result of a single validation check
 type ValidationResult struct {
 	Check   string `json:"check"`
-	Status  string `json:"status"` // "pass", "fail", "error"
+	Status  string `json:"status"` // pass, fail, or error
 	Output  string `json:"output,omitempty"`
 	Summary string `json:"summary"`
 }
@@ -38,25 +53,25 @@ func ValidateGoCode(ctx context.Context, directory string) (*ValidationReport, e
 		description string
 	}{
 		{
-			name:        "go vet",
+			name:        checkGoVet,
 			cmd:         "go",
 			args:        []string{"vet", "./..."},
 			description: "Static analysis to find suspicious constructs",
 		},
 		{
-			name:        "go build (dry-run)",
+			name:        checkGoBuild,
 			cmd:         "go",
 			args:        []string{"build", "-n", "./..."},
 			description: "Check if code compiles without building",
 		},
 		{
-			name:        "go mod tidy (check)",
+			name:        checkGoModTidy,
 			cmd:         "go",
 			args:        []string{"mod", "tidy", "-diff"},
 			description: "Check if go.mod is tidy",
 		},
 		{
-			name:        "gofmt check",
+			name:        checkGofmt,
 			cmd:         "gofmt",
 			args:        []string{"-l", "."},
 			description: "Check if code is properly formatted",
@@ -82,11 +97,11 @@ func ValidateGoCode(ctx context.Context, directory string) (*ValidationReport, e
 	errors := 0
 	for _, result := range report.Results {
 		switch result.Status {
-		case "pass":
+		case statusPass:
 			passed++
-		case "fail":
+		case statusFail:
 			failed++
-		case "error":
+		case statusError:
 			errors++
 		}
 	}
@@ -112,7 +127,7 @@ func ValidateGoCode(ctx context.Context, directory string) (*ValidationReport, e
 }
 
 func runValidationCheck(
-	ctx context.Context,
+	_ context.Context,
 	workDir, name, cmdName string,
 	args []string,
 	description string,
@@ -126,12 +141,12 @@ func runValidationCheck(
 
 	if err != nil {
 		// Command couldn't run at all
-		result.Status = "error"
+		result.Status = statusError
 		result.Output = err.Error()
 		result.Summary = fmt.Sprintf("Could not run %s: %v", name, err)
 	} else if exitCode != 0 {
 		// Command ran but returned non-zero exit code
-		result.Status = "fail"
+		result.Status = statusFail
 
 		// Use stderr for error information, stdout for normal output
 		if stderr != "" {
@@ -141,7 +156,7 @@ func runValidationCheck(
 		}
 
 		switch name {
-		case "gofmt check":
+		case checkGofmt:
 			if stdout != "" {
 				result.Summary = fmt.Sprintf(
 					"Files need formatting: %s",
@@ -150,9 +165,9 @@ func runValidationCheck(
 			} else {
 				result.Summary = "Files need formatting"
 			}
-		case "go mod tidy (check)":
+		case checkGoModTidy:
 			result.Summary = "go.mod needs tidying"
-		case "go vet":
+		case checkGoVet:
 			// go vet typically outputs to stderr
 			issues := stderr
 			if issues == "" {
@@ -164,20 +179,20 @@ func runValidationCheck(
 			} else {
 				result.Summary = "Vet found issues"
 			}
-		case "go build (dry-run)":
+		case checkGoBuild:
 			result.Summary = "Build would fail - compilation errors found"
 		default:
 			result.Summary = fmt.Sprintf("Check failed: %s", name)
 		}
 	} else {
 		// Command succeeded (exit code 0)
-		result.Status = "pass"
+		result.Status = statusPass
 
 		switch name {
-		case "gofmt check":
+		case checkGofmt:
 			// gofmt -l returns 0 even when files need formatting, but lists files to stdout
 			if stdout != "" {
-				result.Status = "fail"
+				result.Status = statusFail
 				result.Output = stdout
 				result.Summary = fmt.Sprintf(
 					"Files need formatting: %s",
@@ -186,12 +201,12 @@ func runValidationCheck(
 			} else {
 				result.Summary = "All files are properly formatted"
 			}
-		case "go vet":
+		case checkGoVet:
 			result.Summary = "No vet issues found"
-		case "go build (dry-run)":
+		case checkGoBuild:
 			// Don't include verbose build output when successful
 			result.Summary = "Code compiles successfully"
-		case "go mod tidy (check)":
+		case checkGoModTidy:
 			result.Summary = "go.mod is tidy"
 		default:
 			if stdout != "" {

internal/mcptool/github.go

@@ -320,7 +320,8 @@ func getGitHubIssue(
 		return mcp.NewToolResultError(fmt.Sprintf("Error getting issue: %v", err)), nil
 	}
 
-	comments, _, err := gh.Issues.ListComments(ctx, owner, repo, args.Number,
+	comments, _, err := gh.Issues.ListComments(
+		ctx, owner, repo, args.Number,
 		&github.IssueListCommentsOptions{ListOptions: github.ListOptions{PerPage: 100}},
 	)
 	if err != nil {
@@ -460,7 +461,8 @@ func getGitHubPull(
 		return mcp.NewToolResultError(fmt.Sprintf("Error getting pull request: %v", err)), nil
 	}
 
-	files, _, err := gh.PullRequests.ListFiles(ctx, owner, repo, args.Number,
+	files, _, err := gh.PullRequests.ListFiles(
+		ctx, owner, repo, args.Number,
 		&github.ListOptions{PerPage: 100},
 	)
 	if err != nil {
@@ -623,7 +625,8 @@ func getGitHubWorkflowRun(
 		return mcp.NewToolResultError(fmt.Sprintf("Error getting workflow run: %v", err)), nil
 	}
 
-	jobs, _, err := gh.Actions.ListWorkflowJobs(ctx, owner, repo, args.RunID,
+	jobs, _, err := gh.Actions.ListWorkflowJobs(
+		ctx, owner, repo, args.RunID,
 		&github.ListWorkflowJobsOptions{
 			Filter:      "latest",
 			ListOptions: github.ListOptions{PerPage: 100},