fix model typo and limit project size in system prompt to 4K max

internal/config/config.go

@@ -222,6 +222,9 @@ func configureViper() {
 	viper.AddConfigPath("$HOME")
 	viper.AddConfigPath(fmt.Sprintf("$XDG_CONFIG_HOME/%s", appName))
 	viper.AddConfigPath(fmt.Sprintf("$HOME/.config/%s", appName))
+	// this allows set variables more easily
+	// e.g. OPENCODE_AGENTS_CODER_MODEL=gpt-4.1-mini
+	viper.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
 	viper.SetEnvPrefix(strings.ToUpper(appName))
 	viper.AutomaticEnv()
 }

internal/llm/models/openai.go

@@ -35,7 +35,7 @@ var OpenAIModels = map[ModelID]Model{
 		ID:                  GPT41Mini,
 		Name:                "GPT 4.1 mini",
 		Provider:            ProviderOpenAI,
-		APIModel:            "gpt-4.1",
+		APIModel:            "gpt-4.1-mini",
 		CostPer1MIn:         0.40,
 		CostPer1MInCached:   0.10,
 		CostPer1MOutCached:  0.0,

internal/llm/prompt/coder.go

@@ -1,7 +1,6 @@
 package prompt
 
 import (
-	"context"
 	"fmt"
 	"os"
 	"path/filepath"
@@ -167,15 +166,25 @@ NEVER commit changes unless the user explicitly asks you to. It is VERY IMPORTAN
 
 You MUST answer concisely with fewer than 4 lines of text (not including tool use or code generation), unless user asks for detail.`
 
+// MAX_PROJECT_SIZE limits the project hierarchy to 4K
+const MAX_PROJECT_SIZE = 4 * 1024
+
 func getEnvironmentInfo() string {
 	cwd := config.WorkingDirectory()
 	isGit := isGitRepo(cwd)
 	platform := runtime.GOOS
 	date := time.Now().Format("1/2/2006")
 	ls := tools.NewLsTool()
-	r, _ := ls.Run(context.Background(), tools.ToolCall{
-		Input: `{"path":"."}`,
+	r, _ := ls.RunWithParams(tools.LSParams{
+		Path:     ".",
+		MaxDepth: 6,
 	})
+
+	// no more than 4k
+	projectContent := r.Content
+	if len(r.Content) > MAX_PROJECT_SIZE {
+		projectContent = r.Content[:MAX_PROJECT_SIZE] + "..."
+	}
 	return fmt.Sprintf(`Here is useful information about the environment you are running in:
 <env>
 Working directory: %s
@@ -186,7 +195,7 @@ Today's date: %s
 <project>
 %s
 </project>
-		`, cwd, boolToYesNo(isGit), platform, date, r.Content)
+		`, cwd, boolToYesNo(isGit), platform, date, projectContent)
 }
 
 func isGitRepo(dir string) bool {

internal/llm/tools/ls.go

@@ -12,8 +12,9 @@ import (
 )
 
 type LSParams struct {
-	Path   string   `json:"path"`
-	Ignore []string `json:"ignore"`
+	Path     string   `json:"path"`
+	MaxDepth int      `json:"max_depth"`
+	Ignore   []string `json:"ignore"`
 }
 
 type TreeNode struct {
@@ -63,7 +64,7 @@ TIPS:
 - Combine with other tools for more effective exploration`
 )
 
-func NewLsTool() BaseTool {
+func NewLsTool() *lsTool {
 	return &lsTool{}
 }
 
@@ -76,6 +77,11 @@ func (l *lsTool) Info() ToolInfo {
 				"type":        "string",
 				"description": "The path to the directory to list (defaults to current working directory)",
 			},
+			"max_depth": map[string]any{
+				// json schema integer: https://json-schema.org/understanding-json-schema/reference/numeric
+				"type":        "integer",
+				"description": "Limit the maximum depth to traversing depths(defaults to no limit, 0 or negative values also treated as no limit)",
+			},
 			"ignore": map[string]any{
 				"type":        "array",
 				"description": "List of glob patterns to ignore",
@@ -93,7 +99,10 @@ func (l *lsTool) Run(ctx context.Context, call ToolCall) (ToolResponse, error) {
 	if err := json.Unmarshal([]byte(call.Input), &params); err != nil {
 		return NewTextErrorResponse(fmt.Sprintf("error parsing parameters: %s", err)), nil
 	}
+	return l.RunWithParams(params)
+}
 
+func (l *lsTool) RunWithParams(params LSParams) (ToolResponse, error) {
 	searchPath := params.Path
 	if searchPath == "" {
 		searchPath = config.WorkingDirectory()
@@ -107,7 +116,7 @@ func (l *lsTool) Run(ctx context.Context, call ToolCall) (ToolResponse, error) {
 		return NewTextErrorResponse(fmt.Sprintf("path does not exist: %s", searchPath)), nil
 	}
 
-	files, truncated, err := listDirectory(searchPath, params.Ignore, MaxLSFiles)
+	files, truncated, err := listDirectory(searchPath, params.Ignore, MaxLSFiles, params.MaxDepth)
 	if err != nil {
 		return ToolResponse{}, fmt.Errorf("error listing directory: %w", err)
 	}
@@ -128,7 +137,31 @@ func (l *lsTool) Run(ctx context.Context, call ToolCall) (ToolResponse, error) {
 	), nil
 }
 
-func listDirectory(initialPath string, ignorePatterns []string, limit int) ([]string, bool, error) {
+// shouldSkipDirDueToDepth checks if a directory should be skipped due to depth limits
+// Returns true if the directory should be skipped, false otherwise
+func shouldSkipDirDueToDepth(initialPath, currentPath string, maxDepth int) bool {
+	if maxDepth <= 0 {
+		return false
+	}
+
+	relPath, err := filepath.Rel(initialPath, currentPath)
+	if err != nil {
+		return false // Don't skip on error
+	}
+
+	// Calculate depth by counting directory separators
+	depth := 0
+	if relPath != "." {
+		// If there are no separators, it's still depth 1 (direct child)
+		// If there are separators, count them and add 1
+		depth = strings.Count(relPath, string(filepath.Separator)) + 1
+	}
+
+	// Skip directory traversal if we're at or beyond max depth
+	return depth >= maxDepth
+}
+
+func listDirectory(initialPath string, ignorePatterns []string, limit int, maxDepth int) ([]string, bool, error) {
 	var results []string
 	truncated := false
 
@@ -144,6 +177,16 @@ func listDirectory(initialPath string, ignorePatterns []string, limit int) ([]st
 			return nil
 		}
 
+		// Check if we should skip due to depth limits (only for directories)
+		if info.IsDir() && shouldSkipDirDueToDepth(initialPath, path, maxDepth) {
+			// Still include this directory in results if it's not the initial path
+			if path != initialPath {
+				path = path + string(filepath.Separator)
+				results = append(results, path)
+			}
+			return filepath.SkipDir
+		}
+
 		if path != initialPath {
 			if info.IsDir() {
 				path = path + string(filepath.Separator)