git.giacomolli.uk - onechat/blob - agent.go

   1 package main
   2
   3 import (
   4         "bytes"
   5         "crypto/rand"
   6         "encoding/hex"
   7         "encoding/json"
   8         "errors"
   9         "fmt"
  10         "io"
  11         "os"
  12         "path/filepath"
  13         "slices"
  14         "strings"
  15
  16         "golang.org/x/sys/unix"
  17 )
  18
  19 const (
  20         // agentInstructionsFileName is the file of the user's instructions in
  21         // the directory of an agent.
  22         agentInstructionsFileName = "instructions.md"
  23
  24         // agentIDBytes is the number of random bytes of an agent ID.
  25         agentIDBytes = 16
  26 )
  27
  28 // openAgent reads the config.json of the agent in dir. When the file does not
  29 // exist, it makes the directory and writes the file with the defaults and a new
  30 // ID. A missing field of an existing file takes the default, but the ID must be
  31 // there. An unknown field is an error, so a typo does not become a silent
  32 // default.
  33 func openAgent(dir string) (*Agent, error) {
  34         err := os.MkdirAll(dir, 0o700)
  35         if err != nil {
  36                 return nil, fmt.Errorf("create agent directory: %w", err)
  37         }
  38
  39         path := filepath.Join(dir, "config.json")
  40         data, err := os.ReadFile(path)
  41         if errors.Is(err, os.ErrNotExist) {
  42                 return createAgent(dir)
  43         }
  44
  45         if err != nil {
  46                 return nil, fmt.Errorf("read agent config: %w", err)
  47         }
  48
  49         config, err := defaultAgentConfig()
  50         if err != nil {
  51                 return nil, err
  52         }
  53
  54         decoder := json.NewDecoder(bytes.NewReader(data))
  55         decoder.DisallowUnknownFields()
  56
  57         err = decoder.Decode(&config)
  58         if err == nil && !errors.Is(decoder.Decode(&struct{}{}), io.EOF) {
  59                 err = errors.New("data after the JSON object")
  60         }
  61
  62         if err == nil {
  63                 err = config.validate()
  64         }
  65
  66         if err != nil {
  67                 return nil, fmt.Errorf("%s: %w", path, err)
  68         }
  69
  70         return &Agent{
  71                 dir:    dir,
  72                 config: config,
  73         }, nil
  74 }
  75
  76 // Agent is one agent and its directory. The directory holds config.json, the
  77 // user's instructions in instructions.md, the chat, and the usage file.
  78 type Agent struct {
  79         dir    string
  80         config AgentConfig
  81 }
  82
  83 // CacheKey returns the prompt cache key of every model call of the agent.
  84 func (a *Agent) CacheKey() string {
  85         return "onechat-" + a.config.ID
  86 }
  87
  88 // Prompt returns the system prompt of the agent with the user's instructions
  89 // from instructions.md. It reads the file on each call, so a change applies at
  90 // the next call. A missing file means no instructions.
  91 func (a *Agent) Prompt() (string, error) {
  92         instructions, err := a.instructions()
  93         if err != nil {
  94                 return "", fmt.Errorf("read prompt instructions: %w", err)
  95         }
  96
  97         path, err := filepath.Abs(filepath.Join(a.dir, agentInstructionsFileName))
  98         if err != nil {
  99                 return "", fmt.Errorf("find instructions path: %w", err)
 100         }
 101
 102         if a.config.Parent != "" {
 103                 return promptChild(a.config.Name, a.config.Parent, a.config.Responsibility, path, instructions), nil
 104         }
 105
 106         return prompt(a.config.Name, path, instructions), nil
 107 }
 108
 109 // Tools returns the tools shared by the turns and compactions of this agent. A
 110 // child has no WhatsApp, child creation, or route tools.
 111 func (a *Agent) Tools() []ModelTool {
 112         tools := promptTools()
 113         if a.config.Parent != "" {
 114                 tools = slices.DeleteFunc(tools, func(tool ModelTool) bool {
 115                         return strings.HasPrefix(tool.Name, "whatsapp_") || tool.Name == "agent_create" || tool.Name == "route" || tool.Name == "unroute" || tool.Name == "routes"
 116                 })
 117         }
 118
 119         return tools
 120 }
 121
 122 // Children reads the direct children in directory order. Each child needs an
 123 // existing config with its directory name and this agent as parent. Children
 124 // cannot have children. A missing children directory means no children.
 125 func (a *Agent) Children() ([]*Agent, error) {
 126         dir := filepath.Join(a.dir, "children")
 127         entries, err := os.ReadDir(dir)
 128         if errors.Is(err, os.ErrNotExist) {
 129                 return nil, nil
 130         }
 131
 132         if err != nil {
 133                 return nil, fmt.Errorf("read children: %w", err)
 134         }
 135
 136         if a.config.Parent != "" && len(entries) != 0 {
 137                 return nil, errors.New("children cannot have children")
 138         }
 139
 140         var children []*Agent
 141
 142         keys := map[string]bool{a.CacheKey(): true}
 143
 144         for _, entry := range entries {
 145                 name := entry.Name()
 146                 if !entry.IsDir() {
 147                         return nil, fmt.Errorf("child %q must be a directory", name)
 148                 }
 149
 150                 path := filepath.Join(dir, name)
 151                 _, err = os.Stat(filepath.Join(path, "config.json"))
 152                 if err != nil {
 153                         return nil, fmt.Errorf("child %q config: %w", name, err)
 154                 }
 155
 156                 child, err := openAgent(path)
 157                 if err != nil {
 158                         return nil, fmt.Errorf("open child %q: %w", name, err)
 159                 }
 160
 161                 if child.config.Name != name || child.config.Parent != a.config.Name {
 162                         return nil, fmt.Errorf("child %q needs name %q and parent %q", name, name, a.config.Name)
 163                 }
 164
 165                 if child.config.Name == a.config.Name || keys[child.CacheKey()] {
 166                         return nil, fmt.Errorf("child %q must have its own name and ID", name)
 167                 }
 168
 169                 keys[child.CacheKey()] = true
 170                 _, err = child.Children()
 171                 if err != nil {
 172                         return nil, fmt.Errorf("read child %q: %w", name, err)
 173                 }
 174
 175                 children = append(children, child)
 176         }
 177
 178         return children, nil
 179 }
 180
 181 // CreateChild writes a new direct child with its own ID and the model, effort,
 182 // and working directory of the root. Child and subagent names share a
 183 // namespace. The config is complete before an atomic rename publishes the
 184 // child. Preparation stays outside children, so an interrupted write cannot
 185 // stop startup.
 186 func (a *Agent) CreateChild(name, responsibility string, subagents *Subagents) (_ *Agent, err error) {
 187         if a.config.Parent != "" {
 188                 return nil, errors.New("only the root can create children")
 189         }
 190
 191         if !agentChildNameValid(name) {
 192                 return nil, errors.New("name must have 2 to 32 ASCII letters and start with a capital letter")
 193         }
 194
 195         if name == a.config.Name {
 196                 return nil, errors.New("the name is already used by the root")
 197         }
 198
 199         responsibility = strings.TrimSpace(responsibility)
 200         if responsibility == "" {
 201                 return nil, errors.New("responsibility must not be empty")
 202         }
 203
 204         err = subagents.Reserve(name)
 205         if err != nil {
 206                 return nil, fmt.Errorf("reserve child name: %w", err)
 207         }
 208
 209         published := false
 210         defer func() {
 211                 if !published {
 212                         subagents.Release(name)
 213                 }
 214         }()
 215
 216         staged, err := os.MkdirTemp(a.dir, ".child-*")
 217         if err != nil {
 218                 return nil, fmt.Errorf("prepare child directory: %w", err)
 219         }
 220
 221         defer func() {
 222                 cleanupErr := os.RemoveAll(staged)
 223                 if cleanupErr != nil {
 224                         err = errors.Join(err, fmt.Errorf("remove prepared child: %w", cleanupErr))
 225                 }
 226         }()
 227
 228         config := a.config
 229         config.Name = name
 230         config.ID = ""
 231         config.Parent = a.config.Name
 232         config.Responsibility = responsibility
 233         child, err := writeAgent(staged, config)
 234         if err != nil {
 235                 return nil, fmt.Errorf("write child: %w", err)
 236         }
 237
 238         dir := filepath.Join(a.dir, "children")
 239         err = os.MkdirAll(dir, 0o700)
 240         if err != nil {
 241                 return nil, fmt.Errorf("create children directory: %w", err)
 242         }
 243
 244         dir = filepath.Join(dir, name)
 245         err = unix.Renameat2(unix.AT_FDCWD, staged, unix.AT_FDCWD, dir, unix.RENAME_NOREPLACE)
 246         if err != nil {
 247                 return nil, fmt.Errorf("publish child directory: %w", err)
 248         }
 249
 250         published = true
 251         child.dir = dir
 252
 253         return child, nil
 254 }
 255
 256 // SubagentPrompt returns the system prompt of a subagent of the agent, with the
 257 // user's instructions as Prompt reads them.
 258 func (a *Agent) SubagentPrompt() (string, error) {
 259         instructions, err := a.instructions()
 260         if err != nil {
 261                 return "", err
 262         }
 263
 264         return promptSubagent(a.config.Name, instructions), nil
 265 }
 266
 267 // instructions reads the user's instructions from instructions.md. A missing
 268 // file means no instructions.
 269 func (a *Agent) instructions() (string, error) {
 270         data, err := os.ReadFile(filepath.Join(a.dir, agentInstructionsFileName))
 271         if err != nil && !errors.Is(err, os.ErrNotExist) {
 272                 return "", fmt.Errorf("read instructions: %w", err)
 273         }
 274
 275         return string(data), nil
 276 }
 277
 278 // AgentConfig holds the settings of the config.json of an agent. ID is random,
 279 // made once when the file is made, and never changes. The cache key comes from
 280 // the ID, so a rename keeps the prompt cache and two agents with one name do
 281 // not share a key. Workdir is the directory where the commands of the agent
 282 // run. Responsibility and Parent are set together for a child agent.
 283 type AgentConfig struct {
 284         Name           string `json:"name"`
 285         ID             string `json:"id"`
 286         Model          string `json:"model"`
 287         Effort         string `json:"effort"`
 288         Workdir        string `json:"workdir"`
 289         Responsibility string `json:"responsibility,omitempty"`
 290         Parent         string `json:"parent,omitempty"`
 291 }
 292
 293 // validate makes sure that each setting has a valid value.
 294 func (c AgentConfig) validate() error {
 295         if c.Name == "" || strings.ContainsAny(c.Name, "\r\n") {
 296                 return errors.New("name must be one line of text")
 297         }
 298
 299         id, err := hex.DecodeString(c.ID)
 300         if err != nil || len(id) != agentIDBytes {
 301                 return fmt.Errorf("id must be %d hexadecimal digits", 2*agentIDBytes)
 302         }
 303
 304         if c.Model == "" || c.Effort == "" {
 305                 return errors.New("agent needs a model and an effort")
 306         }
 307
 308         if (strings.TrimSpace(c.Responsibility) == "") != (c.Parent == "") {
 309                 return errors.New("a child needs both responsibility and parent")
 310         }
 311
 312         if strings.ContainsAny(c.Parent, "\r\n") {
 313                 return errors.New("parent must be one line of text")
 314         }
 315
 316         if !filepath.IsAbs(c.Workdir) {
 317                 return fmt.Errorf("workdir %q is not an absolute path", c.Workdir)
 318         }
 319
 320         return nil
 321 }
 322
 323 // agentChildNameValid accepts one word of 2 to 32 ASCII letters with an initial
 324 // capital letter. Child names describe their area.
 325 func agentChildNameValid(name string) bool {
 326         if len(name) < 2 || len(name) > 32 || name[0] < 'A' || name[0] > 'Z' {
 327                 return false
 328         }
 329
 330         for i := 1; i < len(name); i++ {
 331                 letter := name[i]
 332                 if (letter < 'A' || letter > 'Z') && (letter < 'a' || letter > 'z') {
 333                         return false
 334                 }
 335         }
 336
 337         return true
 338 }
 339
 340 // createAgent writes the config.json of a new agent in dir with the defaults
 341 // and a new ID.
 342 func createAgent(dir string) (*Agent, error) {
 343         config, err := defaultAgentConfig()
 344         if err != nil {
 345                 return nil, err
 346         }
 347
 348         return writeAgent(dir, config)
 349 }
 350
 351 // writeAgent gives config a new ID and writes it in dir.
 352 func writeAgent(dir string, config AgentConfig) (*Agent, error) {
 353         id := make([]byte, agentIDBytes)
 354         _, err := rand.Read(id)
 355         if err != nil {
 356                 return nil, fmt.Errorf("make agent ID: %w", err)
 357         }
 358
 359         config.ID = hex.EncodeToString(id)
 360         data, err := json.MarshalIndent(config, "", "  ")
 361         if err != nil {
 362                 return nil, fmt.Errorf("encode agent config: %w", err)
 363         }
 364
 365         err = writeFileAtomic(filepath.Join(dir, "config.json"), append(data, '\n'))
 366         if err != nil {
 367                 return nil, fmt.Errorf("write agent config: %w", err)
 368         }
 369
 370         return &Agent{
 371                 dir:    dir,
 372                 config: config,
 373         }, nil
 374 }
 375
 376 // defaultAgentConfig returns the settings of a new agent, without an ID. The
 377 // commands run in the home directory of the user.
 378 func defaultAgentConfig() (AgentConfig, error) {
 379         home, err := os.UserHomeDir()
 380         if err != nil {
 381                 return AgentConfig{}, fmt.Errorf("find working directory: %w", err)
 382         }
 383
 384         return AgentConfig{
 385                 Name:    "OneChat",
 386                 Model:   "gpt-6.1-sol",
 387                 Effort:  "medium",
 388                 Workdir: home,
 389         }, nil
 390 }