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         "strings"
  14 )
  15
  16 const (
  17         // agentInstructionsFileName is the file of the user's instructions in
  18         // the directory of an agent.
  19         agentInstructionsFileName = "instructions.md"
  20
  21         // agentIDBytes is the number of random bytes of an agent ID.
  22         agentIDBytes = 16
  23 )
  24
  25 // openAgent reads the config.json of the agent in dir. When the file does not
  26 // exist, it makes the directory and writes the file with the defaults and a new
  27 // ID. A missing field of an existing file takes the default, but the ID must be
  28 // there. An unknown field is an error, so a typo does not become a silent
  29 // default.
  30 func openAgent(dir string) (*Agent, error) {
  31         err := os.MkdirAll(dir, 0o700)
  32         if err != nil {
  33                 return nil, fmt.Errorf("create agent directory: %w", err)
  34         }
  35
  36         path := filepath.Join(dir, "config.json")
  37         data, err := os.ReadFile(path)
  38         if errors.Is(err, os.ErrNotExist) {
  39                 return createAgent(dir)
  40         }
  41
  42         if err != nil {
  43                 return nil, fmt.Errorf("read agent config: %w", err)
  44         }
  45
  46         config, err := defaultAgentConfig()
  47         if err != nil {
  48                 return nil, err
  49         }
  50
  51         decoder := json.NewDecoder(bytes.NewReader(data))
  52         decoder.DisallowUnknownFields()
  53         err = decoder.Decode(&config)
  54         if err == nil && !errors.Is(decoder.Decode(&struct{}{}), io.EOF) {
  55                 err = errors.New("data after the JSON object")
  56         }
  57
  58         if err == nil {
  59                 err = config.validate()
  60         }
  61
  62         if err != nil {
  63                 return nil, fmt.Errorf("%s: %w", path, err)
  64         }
  65
  66         return &Agent{
  67                 dir:    dir,
  68                 config: config,
  69         }, nil
  70 }
  71
  72 // Agent is one agent and its directory. The directory holds config.json, the
  73 // user's instructions in instructions.md, the chat, and the usage file.
  74 type Agent struct {
  75         dir    string
  76         config AgentConfig
  77 }
  78
  79 // CacheKey returns the prompt cache key of every model call of the agent.
  80 func (a *Agent) CacheKey() string {
  81         return "onechat-" + a.config.ID
  82 }
  83
  84 // Prompt returns the system prompt of the agent with the user's instructions
  85 // from instructions.md. It reads the file on each call, so a change applies at
  86 // the next call. A missing file means no instructions.
  87 func (a *Agent) Prompt() (string, error) {
  88         instructions, err := a.instructions()
  89         if err != nil {
  90                 return "", err
  91         }
  92
  93         return prompt(a.config.Name, instructions), nil
  94 }
  95
  96 // SubagentPrompt returns the system prompt of a subagent of the agent, with the
  97 // user's instructions as Prompt reads them.
  98 func (a *Agent) SubagentPrompt() (string, error) {
  99         instructions, err := a.instructions()
 100         if err != nil {
 101                 return "", err
 102         }
 103
 104         return promptSubagent(a.config.Name, instructions), nil
 105 }
 106
 107 // instructions reads the user's instructions from instructions.md. A missing
 108 // file means no instructions.
 109 func (a *Agent) instructions() (string, error) {
 110         data, err := os.ReadFile(filepath.Join(a.dir, agentInstructionsFileName))
 111         if err != nil && !errors.Is(err, os.ErrNotExist) {
 112                 return "", fmt.Errorf("read instructions: %w", err)
 113         }
 114
 115         return string(data), nil
 116 }
 117
 118 // AgentConfig holds the settings of the config.json of an agent. ID is random,
 119 // made once when the file is made, and never changes. The cache key comes from
 120 // the ID, so a rename keeps the prompt cache and two agents with one name do
 121 // not share a key. Workdir is the directory where the commands of the agent
 122 // run.
 123 type AgentConfig struct {
 124         Name    string `json:"name"`
 125         ID      string `json:"id"`
 126         Model   string `json:"model"`
 127         Effort  string `json:"effort"`
 128         Workdir string `json:"workdir"`
 129 }
 130
 131 // validate makes sure that each setting has a valid value.
 132 func (c AgentConfig) validate() error {
 133         if c.Name == "" || strings.ContainsAny(c.Name, "\r\n") {
 134                 return errors.New("name must be one line of text")
 135         }
 136
 137         id, err := hex.DecodeString(c.ID)
 138         if err != nil || len(id) != agentIDBytes {
 139                 return fmt.Errorf("id must be %d hexadecimal digits", 2*agentIDBytes)
 140         }
 141
 142         if c.Model == "" || c.Effort == "" {
 143                 return errors.New("agent needs a model and an effort")
 144         }
 145
 146         if !filepath.IsAbs(c.Workdir) {
 147                 return fmt.Errorf("workdir %q is not an absolute path", c.Workdir)
 148         }
 149
 150         return nil
 151 }
 152
 153 // createAgent writes the config.json of a new agent in dir with the defaults
 154 // and a new ID.
 155 func createAgent(dir string) (*Agent, error) {
 156         config, err := defaultAgentConfig()
 157         if err != nil {
 158                 return nil, err
 159         }
 160
 161         id := make([]byte, agentIDBytes)
 162         _, err = rand.Read(id)
 163         if err != nil {
 164                 return nil, fmt.Errorf("make agent ID: %w", err)
 165         }
 166
 167         config.ID = hex.EncodeToString(id)
 168         data, err := json.MarshalIndent(config, "", "  ")
 169         if err != nil {
 170                 return nil, fmt.Errorf("encode agent config: %w", err)
 171         }
 172
 173         err = writeFileAtomic(filepath.Join(dir, "config.json"), append(data, '\n'))
 174         if err != nil {
 175                 return nil, fmt.Errorf("write agent config: %w", err)
 176         }
 177
 178         return &Agent{
 179                 dir:    dir,
 180                 config: config,
 181         }, nil
 182 }
 183
 184 // defaultAgentConfig returns the settings of a new agent, without an ID. The
 185 // commands run in the home directory of the user.
 186 func defaultAgentConfig() (AgentConfig, error) {
 187         home, err := os.UserHomeDir()
 188         if err != nil {
 189                 return AgentConfig{}, fmt.Errorf("find working directory: %w", err)
 190         }
 191
 192         return AgentConfig{
 193                 Name:    "OneChat",
 194                 Model:   "gpt-6.1-sol",
 195                 Effort:  "medium",
 196                 Workdir: home,
 197         }, nil
 198 }