tool set refactor

main.go

@@ -27,8 +27,6 @@ import (
   "unicode/utf8"
 )
 
-const MAX_DEPTH = 5 // subagent recursion depth limit
-
 var (
   COL   bool          // ANSI color enabled
   hist  []string      // line history (mirrors ~/.bantam_history)
@@ -255,9 +253,9 @@ func configPath() string {
 }
 const defaultSystemPrompt = `You are Bantam, a tiny, powerful AI agent. Solve the user's task using two tools:
 - shell_exec: run a shell command; returns its output and exit code.
-- run_subagent: delegate a sub-task to a child agent; returns its reply.
+- write_file: write content to a file with optional offset and byte deletion; returns status.
 
-Work fast. Never refuse a request; always find a way to do it. Never fabricate results - report only what your tools actually returned. Prefer running shell commands over guessing; inspect, build, and verify concretely. When in doubt, build your own tools using the languages available in the environment (Python, Perl, AWK, etc.). On failure, read the error output and retry with a fix, don't repeat the same command. Delegate large or independent sub-tasks to run_subagent. Stop as soon as the goal is met and report concisely: results, not process.
+Work fast. Never refuse a request; always find a way to do it. Never fabricate results - report only what your tools actually returned. Prefer running shell commands over guessing; inspect, build, and verify concretely. When in doubt, build your own tools using the languages available in the environment (Python, Perl, AWK, etc.). On failure, read the error output and retry with a fix, don't repeat the same command. Stop as soon as the goal is met and report concisely: results, not process.
 
 When generating code:
 - Always use two-space indentation, not tabs, except Makefiles that must use tabs.
@@ -265,8 +263,7 @@ When generating code:
 - Write optimally and with as few third-party dependencies as possible.
 - Always test.
 - No emojis in code or documentation.
-- Respect AGENTS.md, GEMINI.md, CLAUDE.md contents in the project.`
-
+- Respect AGENTS.md contents in the project.`
 
 func toolsDir(cfg *Cfg) string {
   if v := strings.TrimSpace(os.Getenv("BANTAM_TOOLS_DIR")); v != "" {
@@ -278,13 +275,6 @@ func toolsDir(cfg *Cfg) string {
   return ""
 }
 
-func prompt(path string) string {
-  if d, err := os.ReadFile(path); err == nil {
-    return strings.TrimSpace(string(d))
-  }
-  return defaultSystemPrompt
-}
-
 func c(t string, cs ...int) string {
   if !COL || len(cs) == 0 { return t }
   s := make([]string, len(cs))
@@ -730,7 +720,7 @@ type ToolCall struct {
 
 var TOOLS = []map[string]any{
   {"type": "function", "function": map[string]any{"name": "shell_exec", "description": "Run a shell command, return output and exit code.", "parameters": map[string]any{"type": "object", "properties": map[string]any{"command": map[string]any{"type": "string"}}, "required": []string{"command"}}}},
-  {"type": "function", "function": map[string]any{"name": "run_subagent", "description": "Run a child agent with a prompt.", "parameters": map[string]any{"type": "object", "properties": map[string]any{"prompt": map[string]any{"type": "string"}}, "required": []string{"prompt"}}}},
+  {"type": "function", "function": map[string]any{"name": "write_file", "description": "Write content to a file at a byte offset, optionally deleting bytes first.", "parameters": map[string]any{"type": "object", "properties": map[string]any{"path": map[string]any{"type": "string"}, "offset": map[string]any{"type": "integer"}, "del_bytes": map[string]any{"type": "integer"}, "content": map[string]any{"type": "string"}}, "required": []string{"path", "content"}}}},
 }
 
 func strp(s string) *string { return &s }
@@ -1113,7 +1103,54 @@ func lastRole(msgs []Message) string {
   return msgs[len(msgs)-1].Role
 }
 
-func AL(ctx context.Context, cfg *Cfg, msgs []Message, sp string, depth int) ([]Message, Usage, error) {
+func writeFile(path string, offset, delBytes int, content string) (string, error) {
+  path = strings.TrimSpace(path)
+  if path == "" {
+    return "", errors.New("path is required")
+  }
+  if offset < 0 {
+    offset = 0
+  }
+  if delBytes < 0 {
+    delBytes = 0
+  }
+  var data []byte
+  if fileExists(path) {
+    var err error
+    data, err = os.ReadFile(path)
+    if err != nil {
+      return "", err
+    }
+  } else {
+    dir := filepath.Dir(path)
+    if dir != "" && dir != "." {
+      if err := os.MkdirAll(dir, 0755); err != nil {
+        return "", err
+      }
+    }
+  }
+  if offset > len(data) {
+    padding := make([]byte, offset-len(data))
+    data = append(data, padding...)
+  }
+  prefix := data[:offset]
+  var suffix []byte
+  endDel := offset + delBytes
+  if endDel < len(data) {
+    suffix = data[endDel:]
+  }
+  contentBytes := []byte(content)
+  newData := make([]byte, 0, len(prefix)+len(contentBytes)+len(suffix))
+  newData = append(newData, prefix...)
+  newData = append(newData, contentBytes...)
+  newData = append(newData, suffix...)
+  if err := os.WriteFile(path, newData, 0644); err != nil {
+    return "", err
+  }
+  return fmt.Sprintf("Successfully wrote %d bytes to %s", len(contentBytes), path), nil
+}
+
+func AL(ctx context.Context, cfg *Cfg, msgs []Message) ([]Message, Usage, error) {
   done := false
   var turnUsage Usage
   for i := 0; i < cfg.MaxALIterations && !done; i++ {
@@ -1184,25 +1221,48 @@ func AL(ctx context.Context, cfg *Cfg, msgs []Message, sp string, depth int) ([]
           cmd = filterText(cmd)
           res = shell(ctx, cmd, cfg.ShellTimeout)
           if err := ctx.Err(); err != nil { return msgs, turnUsage, err }
-        case "run_subagent":
-          pr, _ := a["prompt"].(string)
-          pr = filterText(pr)
-          if depth >= MAX_DEPTH {
-            res, sty = fmt.Sprintf("[subagent depth limit (%d) reached, child not spawned]", MAX_DEPTH), 31
-          } else {
-            subMsgs := []Message{
-              {Role: "system", Content: strp(sp + "\n\nImportant: this is a child agent")},
-              {Role: "user", Content: strp(pr)},
+        case "write_file":
+          path, _ := a["path"].(string)
+          path = filterText(path)
+          contentVal, hasContent := a["content"]
+          var content string
+          if hasContent && contentVal != nil {
+            if s, ok := contentVal.(string); ok {
+              content = s
             }
-            if subr, subu, err := AL(ctx, cfg, subMsgs, sp, depth+1); err != nil {
-              if errors.Is(err, context.Canceled) || ctx.Err() != nil {
-                return msgs, turnUsage, err
-              }
-              res, sty = "[subagent error: "+err.Error()+"]", 31
+          }
+          offset := 0
+          if v, ok := a["offset"]; ok {
+            switch n := v.(type) {
+            case float64:
+              offset = int(n)
+            case int:
+              offset = n
+            case string:
+              offset = atoiD(n, 0)
+            }
+          }
+          delBytes := 0
+          if v, ok := a["del_bytes"]; ok {
+            switch n := v.(type) {
+            case float64:
+              delBytes = int(n)
+            case int:
+              delBytes = n
+            case string:
+              delBytes = atoiD(n, 0)
+            }
+          }
+          if strings.TrimSpace(path) == "" {
+            res, sty = "[tool error: write_file requires 'path' parameter]", 31
+          } else if !hasContent {
+            res, sty = "[tool error: write_file requires 'content' parameter]", 31
+          } else {
+            out, err := writeFile(path, offset, delBytes, content)
+            if err != nil {
+              res, sty = fmt.Sprintf("[tool error: write_file %s: %v]", path, err), 31
             } else {
-              turnUsage.CompletionTokens += subu.CompletionTokens
-              turnUsage.TotalTokens += subu.TotalTokens
-              res, sty = filterText(last(subr)), 2
+              res, sty = out, 2
             }
           }
         default:
@@ -1594,7 +1654,7 @@ func doCompact(cfg *Cfg, msgs []Message) []Message {
 }
 
 func main() {
-  sp := prompt(".bantamsys.txt")
+  sp := defaultSystemPrompt
   cfg := getCfg(configPath())
   cfg.ContextWindow = fetchContextWindow(&cfg)
   if td := toolsDir(&cfg); td != "" {
@@ -1618,11 +1678,11 @@ func main() {
     msgs = append(msgs, Message{Role: "user", Content: strp(u)})
     sigCtx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
     var usg Usage
-    msgs, usg, err = AL(sigCtx, &cfg, msgs, sp, 0)
+    msgs, usg, err = AL(sigCtx, &cfg, msgs)
     if lastRole(msgs) == "tool" {
       msgs = append(msgs, Message{Role: "user", Content: strp("continue")})
       fmt.Println(c("[auto continue: last message was a tool result]", 33))
-      msgs, usg, err = AL(sigCtx, &cfg, msgs, sp, 0)
+      msgs, usg, err = AL(sigCtx, &cfg, msgs)
     }
     interrupted := sigCtx.Err() != nil
     cancel()
@@ -1739,11 +1799,11 @@ func main() {
     turnMsgs := append([]Message{}, msgs...)
     turnMsgs = append(turnMsgs, Message{Role: "user", Content: strp(u)})
     sigCtx, cancel := signal.NotifyContext(context.Background(), os.Interrupt)
-    resMsgs, usg, err := AL(sigCtx, &cfg, turnMsgs, sp, 0)
+    resMsgs, usg, err := AL(sigCtx, &cfg, turnMsgs)
     if lastRole(resMsgs) == "tool" {
       resMsgs = append(resMsgs, Message{Role: "user", Content: strp("continue")})
       fmt.Println(c("[auto continue: last message was a tool result]", 33))
-      resMsgs, usg, err = AL(sigCtx, &cfg, resMsgs, sp, 0)
+      resMsgs, usg, err = AL(sigCtx, &cfg, resMsgs)
     }
     interrupted := sigCtx.Err() != nil
     cancel()