agent/pkg/lib/workspace/default/CODEX.md.tmpl

# CODEX.md

Instructions for Codex when working with code in this workspace.

## Core Framework

This project uses `dappco.re/go/core` as its foundation. Core provides primitives that REPLACE standard library and third-party packages. Implementation reference is in `.core/reference/*.go`.

## Mandatory Patterns

### Errors — use `core.E()`, never `fmt.Errorf` or `errors.New`

```go
// WRONG
return fmt.Errorf("failed to read: %w", err)
return errors.New("not found")

// CORRECT
return core.E("readConfig", "failed to read config", err)
return core.E("findUser", "user not found", nil)
```

### Logging — use `core.Error/Info/Warn/Debug`, never `log.*` or `fmt.Print*`

```go
// WRONG
log.Printf("starting server on %s", addr)
fmt.Fprintf(os.Stderr, "error: %v\n", err)

// CORRECT
core.Info("starting server", "addr", addr)
core.Error("operation failed", "err", err)
```

### Filesystem — use `core.Fs{}`, never `os.ReadFile/WriteFile/MkdirAll`

```go
var fs = &core.Fs{}
r := fs.Read(path)           // returns core.Result
if !r.OK { return r }
content := r.Value.(string)

fs.Write(path, content)      // returns core.Result
fs.EnsureDir(dir)             // returns core.Result
```

### Returns — use `core.Result`, never `(value, error)`

```go
// WRONG
func LoadConfig(path string) (string, error) {
    data, err := os.ReadFile(path)
    if err != nil { return "", err }
    return string(data), nil
}

// CORRECT
func LoadConfig(path string) core.Result {
    return fs.Read(path)
}
```

### Strings — use `core.*`, never `strings.*` or `fmt.Sprintf`

| Do NOT use | Use instead |
|------------|-------------|
| `strings.Contains` | `core.Contains` |
| `strings.HasPrefix` | `core.HasPrefix` |
| `strings.HasSuffix` | `core.HasSuffix` |
| `strings.TrimSpace` | `core.Trim` |
| `strings.TrimPrefix` | `core.TrimPrefix` |
| `strings.TrimSuffix` | `core.TrimSuffix` |
| `strings.Split` | `core.Split` |
| `strings.SplitN` | `core.SplitN` |
| `strings.Join(parts, sep)` | `core.Join(sep, parts...)` |
| `strings.ReplaceAll` | `core.Replace` |
| `strings.ToLower` | `core.Lower` |
| `strings.ToUpper` | `core.Upper` |
| `strings.NewReader` | `core.NewReader` |
| `strings.Builder{}` | `core.NewBuilder()` |
| `fmt.Sprintf` | `core.Sprintf` |
| `fmt.Sprint` | `core.Sprint` |

### Imports — alias stdlib `io` as `goio`

```go
import goio "io"
```

### Comments — usage examples, not descriptions

```go
// WRONG
// LoadConfig loads configuration from a file path.

// CORRECT
// LoadConfig reads and parses a YAML configuration file.
//
//  r := LoadConfig("/home/user/.core/agents.yaml")
//  if r.OK { cfg := r.Value.(*AgentsConfig) }
```

### Names — predictable, never abbreviated

```
Config    not  Cfg
Service   not  Srv
Options   not  Opts
Error     not  Err (as subsystem name)
```

### UK English in comments

```
initialise   not  initialize
colour       not  color
organisation not  organization
serialise    not  serialize
```

### Compile-time interface assertions

```go
var _ mcp.Subsystem = (*MySubsystem)(nil)
```

### Keyed struct literals

```go
// WRONG
core.Result{err, false}

// CORRECT
core.Result{Value: err, OK: false}
```

### Embedded content — use `core.Mount` + `core.Extract`, never raw `embed.FS`

```go
// WRONG
//go:embed templates
var templatesFS embed.FS
data, _ := templatesFS.ReadFile("templates/config.yaml")

// CORRECT
//go:embed templates
var templatesFS embed.FS
var templates = mustMount(templatesFS, "templates")

func mustMount(fsys embed.FS, basedir string) *core.Embed {
    r := core.Mount(fsys, basedir)
    if !r.OK { panic(r.Value) }
    return r.Value.(*core.Embed)
}

r := templates.ReadString("config.yaml")
if r.OK { content := r.Value.(string) }

// Extract template directory with data substitution
core.Extract(templates.FS(), targetDir, data)
```

### Error wrapping — use `core.Wrap`, never manual chaining

```go
// WRONG
return fmt.Errorf("save failed: %w", err)

// CORRECT
return core.Wrap(err, "saveConfig", "failed to save config")
```

### Error codes — use `core.WrapCode` for machine-readable errors

```go
return core.WrapCode(err, "VALIDATION_ERROR", "user.Validate", "invalid email")
var ErrNotFound = core.NewCode("NOT_FOUND", "resource not found")
```

### Error introspection

```go
core.Operation(err)        // extract operation name
core.ErrorCode(err)        // extract error code
core.ErrorMessage(err)     // extract message
core.Root(err)             // root cause
core.StackTrace(err)       // logical stack trace
core.Is(err, target)       // errors.Is wrapper
core.As(err, &target)      // errors.As wrapper
```

### Formatted output — use `core.Print`, never `fmt.Fprintf`

```go
// WRONG
fmt.Fprintf(os.Stderr, "server on %s\n", addr)
fmt.Println("done")

// CORRECT
core.Print(os.Stderr, "server on %s", addr)  // writer + format
core.Print(nil, "done")                       // nil = stdout
```

### Arrays — use `core.Array[T]`, never manual slice management

```go
arr := core.NewArray[string]("a", "b", "c")
arr.AddUnique("d")
arr.Contains("a")           // true
arr.Filter(func(s string) bool { return s != "b" })
arr.Deduplicate()
```

### Config — use `core.Config`, never raw maps

```go
c.Config().Set("port", 8080)
port := c.Config().Int("port")
c.Config().Enable("debug")
if c.Config().Enabled("debug") { ... }
```

### IPC — use `core.Action/Query/Perform` for inter-service communication

```go
// Fire-and-forget broadcast
c.ACTION(MyEvent{Data: "hello"})

// Query first responder
r := c.QUERY(FindUser{ID: 123})
if r.OK { user := r.Value.(*User) }

// Perform task (side effects)
r := c.PERFORM(SendEmail{To: "user@example.com"})

// Register handler
c.RegisterAction(func(c *core.Core, msg core.Message) core.Result {
    switch m := msg.(type) {
    case MyEvent:
        core.Info("received event", "data", m.Data)
    }
    return core.Result{OK: true}
})
```

### Services — use `c.Service()` DTO pattern

```go
c.Service("cache", core.Service{
    OnStart: func() core.Result { return core.Result{OK: true} },
    OnStop:  func() core.Result { return core.Result{OK: true} },
})

r := c.Service("cache")
if r.OK { svc := r.Value.(*core.Service) }
```

### Commands — use `c.Command()` path-based registration

```go
c.Command("deploy", core.Command{
    Description: "Deploy to production",
    Action: func(opts core.Options) core.Result {
        target := opts.String("target")
        return core.Result{Value: "deployed to " + target, OK: true}
    },
})

// Nested commands use path notation
c.Command("deploy/to/homelab", core.Command{...})

// Run CLI
c.Cli().Run()
```

### Drive — use `c.Drive()` for transport handles

```go
c.Drive().New(core.Options{
    {Key: "name", Value: "api"},
    {Key: "transport", Value: "https://api.lthn.ai"},
})

r := c.Drive().Get("api")
if r.OK { handle := r.Value.(*core.DriveHandle) }
```

### I18n — use `c.I18n()` for translations

```go
r := c.I18n().Translate("greeting", "name", "World")
if r.OK { text := r.Value.(string) }

c.I18n().SetLanguage("en-GB")
```

## What NOT to import

| Do NOT import | Use instead |
|---------------|-------------|
| `fmt` | `core.Sprintf`, `core.Print` |
| `log` | `core.Error`, `core.Info` |
| `strings` | `core.Contains`, `core.Split` etc |
| `errors` | `core.E`, `core.Wrap` |
| `io/ioutil` | `core.Fs{}` |
| `os` (file ops) | `core.Fs{}` |

Acceptable stdlib: `os.Getenv`, `os.Exit`, `os.Stderr`, `os.UserHomeDir`, `context`, `sync`, `time`, `net/http`, `encoding/json`, `path/filepath`.

## Build & Test

```bash
go build ./...
go test ./...
go vet ./...
```