# CoreGO API Contract — RFC Specification

> `dappco.re/go/core` — Dependency injection, service lifecycle, permission, and message-passing framework.
> This document is the authoritative API contract. An agent should be able to write a service
> that registers with Core from this document alone.

**Status:** Living document
**Module:** `dappco.re/go/core`
**Version:** v0.8.0

---

## 1. Core — The Container

Core is the central application container. Everything registers with Core, communicates through Core, and has its lifecycle managed by Core.

### 1.1 Creation

```go
c := core.New(
    core.WithOption("name", "my-app"),
    core.WithService(mypackage.Register),
    core.WithService(anotherpackage.Register),
    core.WithServiceLock(),
)
c.Run()
```

`core.New()` returns `*Core` (not Result — Core is the one type that can't wrap its own creation error). Functional options are applied in order. `WithServiceLock()` prevents late service registration.

### 1.2 Lifecycle

```
New() → WithService factories called → LockApply()
RunE() → defer ServiceShutdown() → ServiceStartup() → Cli.Run() → returns error
Run()  → RunE() → os.Exit(1) on error
```

`RunE()` is the primary lifecycle — returns `error`, always calls `ServiceShutdown` via defer (even on startup failure or panic). `Run()` is sugar that calls `RunE()` and exits on error. `ServiceStartup` calls `OnStartup(ctx)` on all `Startable` services in registration order. `ServiceShutdown` calls `OnShutdown(ctx)` on all `Stoppable` services.

### 1.3 Subsystem Accessors

Every subsystem is accessed via a method on Core:

```go
c.Options()      // *Options     — input configuration
c.App()          // *App         — application metadata (name, version)
c.Config()       // *Config      — runtime settings, feature flags
c.Data()         // *Data        — embedded assets (Registry[*Embed])
c.Drive()        // *Drive       — transport handles (Registry[*DriveHandle])
c.Fs()           // *Fs          — filesystem I/O (sandboxable)
c.Cli()          // *Cli         — CLI command framework
c.IPC()          // *Ipc         — message bus internals
c.I18n()         // *I18n        — internationalisation
c.Error()        // *ErrorPanic  — panic recovery
c.Log()          // *ErrorLog    — structured logging
c.Process()      // *Process     — managed execution (Action sugar)
c.API()          // *API         — remote streams (protocol handlers)
c.Action(name)   // *Action      — named callable (register/invoke)
c.Task(name)     // *Task        — composed Action sequence
c.Entitled(name) // Entitlement  — permission check
c.RegistryOf(n)  // *Registry    — cross-cutting queries
c.Context()      // context.Context
c.Env(key)       // string       — environment variable (cached at init)
```

---

## 2. Primitive Types

### 2.1 Option

The atom. A single key-value pair.

```go
core.Option{Key: "name", Value: "brain"}
core.Option{Key: "port", Value: 8080}
core.Option{Key: "debug", Value: true}
```

### 2.2 Options

A collection of Option with typed accessors.

```go
opts := core.NewOptions(
    core.Option{Key: "name", Value: "myapp"},
    core.Option{Key: "port", Value: 8080},
    core.Option{Key: "debug", Value: true},
)

opts.String("name")  // "myapp"
opts.Int("port")     // 8080
opts.Bool("debug")   // true
opts.Has("name")     // true
opts.Len()           // 3

opts.Set("name", "new-name")
opts.Get("name")     // Result{Value: "new-name", OK: true}
```

### 2.3 Result

Universal return type. Every Core operation returns Result.

```go
type Result struct {
    Value any
    OK    bool
}
```

Usage patterns:

```go
// Check success
r := c.Config().Get("database.host")
if r.OK {
    host := r.Value.(string)
}

// Service factory returns Result
func Register(c *core.Core) core.Result {
    svc := &MyService{}
    return core.Result{Value: svc, OK: true}
}

// Error as Result
return core.Result{Value: err, OK: false}
```

No generics on Result. Type-assert the Value when needed. This is deliberate — `Result` is universal across all subsystems without carrying type parameters.

### 2.4 Message, Query

IPC type aliases for the broadcast/request system:

```go
type Message any  // broadcast via ACTION — fire and forget
type Query any    // request/response via QUERY — returns first handler's result
```

For tracked work, use named Actions: `c.PerformAsync("action.name", opts)`.

---

## 3. Service System

### 3.1 Registration

Services register via factory functions passed to `WithService`:

```go
core.New(
    core.WithService(mypackage.Register),
)
```

The factory signature is `func(*Core) Result`. The returned `Result.Value` is the service instance.

### 3.2 Factory Pattern

```go
func Register(c *core.Core) core.Result {
    svc := &MyService{
        runtime: core.NewServiceRuntime(c, MyOptions{}),
    }
    return core.Result{Value: svc, OK: true}
}
```

`NewServiceRuntime[T]` gives the service access to Core and typed options:

```go
type MyService struct {
    *core.ServiceRuntime[MyOptions]
}

// Access Core from within the service:
func (s *MyService) doSomething() {
    c := s.Core()
    cfg := s.Config().String("my.setting")
}
```

### 3.3 Auto-Discovery

`WithService` reflects on the returned instance to discover:
- **Package name** → service name (from reflect type path)
- **Startable interface** → `OnStartup(ctx) Result` called during `ServiceStartup`
- **Stoppable interface** → `OnShutdown(ctx) Result` called during `ServiceShutdown`
- **HandleIPCEvents method** → auto-registered as IPC handler

### 3.4 Retrieval

```go
// Type-safe retrieval
svc, ok := core.ServiceFor[*MyService](c, "mypackage")
if !ok {
    // service not registered
}

// Must variant (panics if not found)
svc := core.MustServiceFor[*MyService](c, "mypackage")

// List all registered services
names := c.Services() // []string in registration order
```

### 3.5 Lifecycle Interfaces

```go
type Startable interface {
    OnStartup(ctx context.Context) Result
}

type Stoppable interface {
    OnShutdown(ctx context.Context) Result
}
```

Services implementing these are called during `RunE()` / `Run()` in registration order.

---

## 4. IPC — Message Passing

### 4.1 ACTION (broadcast)

Fire-and-forget broadcast to all registered handlers:

```go
// Send
c.ACTION(messages.AgentCompleted{
    Agent: "codex", Repo: "go-io", Status: "completed",
})

// Register handler
c.RegisterAction(func(c *core.Core, msg core.Message) core.Result {
    if ev, ok := msg.(messages.AgentCompleted); ok {
        // handle completion
    }
    return core.Result{OK: true}
})
```

All handlers receive all messages. Type-switch to filter. Handler return values are ignored — broadcast calls ALL handlers regardless. Each handler is wrapped in panic recovery.

### 4.2 QUERY (request/response)

First handler to return a non-empty result wins:

```go
// Send
result := c.QUERY(MyQuery{Name: "brain"})
if result.OK {
    svc := result.Value
}

// Register handler
c.RegisterQuery(func(c *core.Core, q core.Query) core.Result {
    if mq, ok := q.(MyQuery); ok {
        return core.Result{Value: found, OK: true}
    }
    return core.Result{OK: false} // not my query
})
```

### 4.3 PerformAsync (background action)

```go
// Execute a named action in background with progress tracking
r := c.PerformAsync("agentic.dispatch", opts)
taskID := r.Value.(string)

// Report progress
c.Progress(taskID, 0.5, "halfway done", "agentic.dispatch")
```

Broadcasts `ActionTaskStarted`, `ActionTaskProgress`, `ActionTaskCompleted` as ACTION messages.

---

## 5. Config

Runtime configuration with typed accessors and feature flags.

```go
c.Config().Set("database.host", "localhost")
c.Config().Set("database.port", 5432)

host := c.Config().String("database.host")  // "localhost"
port := c.Config().Int("database.port")      // 5432

// Feature flags
c.Config().Enable("dark-mode")
c.Config().Enabled("dark-mode")     // true
c.Config().Disable("dark-mode")
c.Config().EnabledFeatures()         // []string

// Type-safe generic getter
val := core.ConfigGet[string](c.Config(), "database.host")
```

---

## 6. Data — Embedded Assets

Mount embedded filesystems and read from them:

```go
//go:embed prompts/*
var promptFS embed.FS

// Mount during service registration
c.Data().New(core.NewOptions(
    core.Option{Key: "name", Value: "prompts"},
    core.Option{Key: "source", Value: promptFS},
    core.Option{Key: "path", Value: "prompts"},
))

// Read
r := c.Data().ReadString("prompts/coding.md")
if r.OK {
    content := r.Value.(string)
}

// List
r := c.Data().List("prompts/")
r := c.Data().ListNames("prompts/")
r := c.Data().Mounts() // []string (insertion order)

// Data embeds Registry[*Embed] — all Registry methods available:
c.Data().Has("prompts")
c.Data().Each(func(name string, emb *Embed) { ... })
```

---

## 7. Drive — Transport Handles

Registry of named transport handles (API endpoints, MCP servers, etc):

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

r := c.Drive().Get("forge")     // Result with *DriveHandle
c.Drive().Has("forge")          // true
c.Drive().Names()               // []string (insertion order)

// Drive embeds Registry[*DriveHandle] — all Registry methods available.
```

---

## 8. Fs — Filesystem

Sandboxable filesystem I/O. All paths are validated against the root.

```go
fs := c.Fs()

// Read/Write
r := fs.Read("/path/to/file")           // Result{Value: string}
r := fs.Write("/path/to/file", content) // Result{OK: bool}
r := fs.WriteMode(path, content, 0600)  // With permissions

// Directory ops
r := fs.EnsureDir("/path/to/dir")
r := fs.List("/path/to/dir")            // Result{Value: []os.DirEntry}
fs.IsDir(path)                           // bool
fs.IsFile(path)                          // bool
fs.Exists(path)                          // bool

// Streams
r := fs.Open(path)        // Result{Value: *os.File}
r := fs.Create(path)      // Result{Value: *os.File}
r := fs.Append(path)      // Result{Value: io.WriteCloser}
r := fs.ReadStream(path)  // Result{Value: io.ReadCloser}
r := fs.WriteStream(path) // Result{Value: io.WriteCloser}

// Atomic write (write-to-temp-then-rename, safe for concurrent readers)
r := fs.WriteAtomic(path, content)

// Delete
r := fs.Delete(path)      // single file
r := fs.DeleteAll(path)   // recursive
r := fs.Rename(old, new)
r := fs.Stat(path)        // Result{Value: os.FileInfo}

// Sandbox control
fs.Root()                  // sandbox root path
fs.NewUnrestricted()       // Fs with root "/" — full access
```

---

## 9. CLI

Command tree with path-based routing:

```go
c.Command("issue/get", core.Command{
    Description: "Get a Forge issue",
    Action: s.cmdIssueGet,
})

c.Command("issue/list", core.Command{
    Description: "List Forge issues",
    Action: s.cmdIssueList,
})

// Action signature
func (s *MyService) cmdIssueGet(opts core.Options) core.Result {
    repo := opts.String("_arg")  // positional arg
    num := opts.String("number") // --number=N flag
    // ...
    return core.Result{OK: true}
}
```

Path = command hierarchy. `issue/get` becomes `myapp issue get` in CLI.

Managed commands have lifecycle provided by go-process:

```go
c.Command("serve", core.Command{
    Action:  handler,
    Managed: "process.daemon",  // go-process provides start/stop/restart
})
```

---

## 10. Error Handling

All errors use `core.E()`:

```go
// Standard error
return core.E("service.Method", "what failed", underlyingErr)

// With format
return core.E("service.Method", core.Sprintf("not found: %s", name), nil)

// Error inspection
core.Operation(err)      // "service.Method"
core.ErrorMessage(err)   // "what failed"
core.ErrorCode(err)      // code if set via WrapCode
core.Root(err)           // unwrap to root cause
core.Is(err, target)     // errors.Is
core.As(err, &target)    // errors.As
```

**NEVER use `fmt.Errorf`, `errors.New`, or `log.*`.** Core handles all error reporting.

---

## 11. Logging

```go
core.Info("server started", "port", 8080)
core.Debug("processing", "item", name)
core.Warn("deprecated", "feature", "old-api")
core.Error("failed", "err", err)
core.Security("access denied", "user", username)
```

Key-value pairs after the message. Structured, not formatted strings.

---

## 12. String Helpers

Core re-exports string operations to avoid `strings` import:

```go
core.Contains(s, substr)
core.HasPrefix(s, prefix)
core.HasSuffix(s, suffix)
core.TrimPrefix(s, prefix)
core.TrimSuffix(s, suffix)
core.Split(s, sep)
core.SplitN(s, sep, n)
core.Join(sep, parts...)
core.Replace(s, old, new)
core.Lower(s) / core.Upper(s)
core.Trim(s)
core.Sprintf(format, args...)
core.Concat(parts...)
core.NewBuilder() / core.NewReader(s)
```

---

## 13. Path Helpers

```go
core.Path(segments...)      // ~/segments joined
core.JoinPath(segments...)  // filepath.Join
core.PathBase(p)            // filepath.Base
core.PathDir(p)             // filepath.Dir
core.PathExt(p)             // filepath.Ext
core.PathIsAbs(p)           // filepath.IsAbs
core.PathGlob(pattern)      // filepath.Glob
core.CleanPath(p, sep)      // normalise separators
```

---

## 14. Utility Functions

```go
core.Print(writer, format, args...)  // formatted output
core.Env(key)                         // cached env var (set at init)
core.EnvKeys()                        // all available env keys

// Arg extraction (positional)
core.Arg(0, args...)       // Result
core.ArgString(0, args...) // string
core.ArgInt(0, args...)    // int
core.ArgBool(0, args...)   // bool

// Flag parsing
core.IsFlag("--name")              // true
core.ParseFlag("--name=value")    // "name", "value", true
core.FilterArgs(args)              // strip flags, keep positional

// Identifiers and validation
core.ID()                          // "id-42-a3f2b1" — unique per process
core.ValidateName("brain")        // Result{OK: true} — rejects "", ".", "..", path seps
core.SanitisePath("../../x")      // "x" — extracts safe base, "invalid" for dangerous
```

---

## 15. Lock System

Per-Core mutex registry for coordinating concurrent access:

```go
c.Lock("drain").Mutex.Lock()
defer c.Lock("drain").Mutex.Unlock()

// Enable named locks
c.LockEnable("service-registry")

// Apply lock (prevents further registration)
c.LockApply()
```

---

## 16. ServiceRuntime Generic Helper

Embed in services to get Core access and typed options:

```go
type MyService struct {
    *core.ServiceRuntime[MyOptions]
}

type MyOptions struct {
    BufferSize int
    Timeout    time.Duration
}

func NewMyService(c *core.Core) core.Result {
    svc := &MyService{
        ServiceRuntime: core.NewServiceRuntime(c, MyOptions{
            BufferSize: 1024,
            Timeout:    30 * time.Second,
        }),
    }
    return core.Result{Value: svc, OK: true}
}

// Within the service:
func (s *MyService) DoWork() {
    c := s.Core()           // access Core
    opts := s.Options()     // MyOptions{BufferSize: 1024, ...}
    cfg := s.Config()       // shortcut to s.Core().Config()
}
```

---

## 17. Process — Managed Execution

`c.Process()` is sugar over named Actions. core/go defines the primitive. go-process provides the implementation via `c.Action("process.run", handler)`.

```go
// Synchronous — returns Result
r := c.Process().Run(ctx, "git", "log", "--oneline")
r := c.Process().RunIn(ctx, "/repo", "go", "test", "./...")
r := c.Process().RunWithEnv(ctx, dir, []string{"GOWORK=off"}, "go", "test")

// Async — returns process ID
r := c.Process().Start(ctx, opts)

// Control
c.Process().Kill(ctx, core.NewOptions(core.Option{Key: "id", Value: processID}))

// Capability check
if c.Process().Exists() { /* go-process is registered */ }
```

**Permission by registration:** No go-process registered → `c.Process().Run()` returns `Result{OK: false}`. No config, no tokens. The service either exists or it doesn't.

```go
// Sandboxed Core — no process capability
c := core.New()
c.Process().Run(ctx, "rm", "-rf", "/")  // Result{OK: false} — nothing happens

// Full Core — process registered
c := core.New(core.WithService(process.Register))
c.Process().Run(ctx, "git", "log")      // executes, returns output
```

> Consumer implementation: see `go-process/docs/RFC.md`

---

## 18. Action and Task — The Execution Primitives

An Action is a named, registered callable. A Task is a composed sequence of Actions.

### 18.1 Action — The Atomic Unit

```go
// Register
c.Action("git.log", func(ctx context.Context, opts core.Options) core.Result {
    dir := opts.String("dir")
    return c.Process().RunIn(ctx, dir, "git", "log", "--oneline")
})

// Invoke
r := c.Action("git.log").Run(ctx, core.NewOptions(
    core.Option{Key: "dir", Value: "/repo"},
))

// Check capability
c.Action("process.run").Exists()  // true if go-process registered

// List all
c.Actions()  // []string{"process.run", "agentic.dispatch", ...}
```

`c.Action(name)` is dual-purpose: with handler arg → register; without → return for invocation.

### 18.2 Action Type

```go
type ActionHandler func(context.Context, Options) Result

type Action struct {
    Name        string
    Handler     ActionHandler
    Description string
    Schema      Options       // expected input keys
}
```

`Action.Run()` has panic recovery and entitlement checking (Section 21) built in.

### 18.3 Where Actions Come From

Services register during `OnStartup`:

```go
func (s *MyService) OnStartup(ctx context.Context) core.Result {
    c := s.Core()
    c.Action("process.run", s.handleRun)
    c.Action("git.clone", s.handleGitClone)
    return core.Result{OK: true}
}
```

The action namespace IS the capability map. go-process registers `process.*`, core/agent registers `agentic.*`.

### 18.4 Permission Model

Three states for any action:

| State | `Exists()` | `Entitled()` | `Run()` |
|-------|-----------|-------------|---------|
| Not registered | false | — | `Result{OK: false}` not registered |
| Registered, not entitled | true | false | `Result{OK: false}` not entitled |
| Registered and entitled | true | true | executes handler |

### 18.5 Task — Composing Actions

```go
c.Task("deploy", core.Task{
    Description: "Build, test, deploy",
    Steps: []core.Step{
        {Action: "go.build"},
        {Action: "go.test"},
        {Action: "docker.push"},
        {Action: "ansible.deploy", Async: true},  // doesn't block
    },
})

r := c.Task("deploy").Run(ctx, c, opts)
```

Sequential steps stop on first failure. `Async: true` steps fire without blocking.
`Input: "previous"` pipes last step's output to next step.

### 18.6 Background Execution

```go
r := c.PerformAsync("agentic.dispatch", opts)
taskID := r.Value.(string)

// Broadcasts ActionTaskStarted, ActionTaskProgress, ActionTaskCompleted
c.Progress(taskID, 0.5, "halfway", "agentic.dispatch")
```

### 18.7 How Process Fits

`c.Process()` is sugar over Actions:

```go
c.Process().Run(ctx, "git", "log")
// equivalent to:
c.Action("process.run").Run(ctx, core.NewOptions(
    core.Option{Key: "command", Value: "git"},
    core.Option{Key: "args", Value: []string{"log"}},
))
```

---

## 19. API — Remote Streams

Drive is the phone book (WHERE). API is the phone (HOW). Consumer packages register protocol handlers.

```go
// Configure endpoint in Drive
c.Drive().New(core.NewOptions(
    core.Option{Key: "name", Value: "charon"},
    core.Option{Key: "transport", Value: "http://10.69.69.165:9101/mcp"},
))

// Open stream — looks up Drive, finds protocol handler
r := c.API().Stream("charon")
if r.OK {
    stream := r.Value.(core.Stream)
    stream.Send(payload)
    resp, _ := stream.Receive()
    stream.Close()
}
```

### 19.1 Stream Interface

```go
type Stream interface {
    Send(data []byte) error
    Receive() ([]byte, error)
    Close() error
}
```

### 19.2 Protocol Handlers

Consumer packages register factories per URL scheme:

```go
// In a transport package's OnStartup:
c.API().RegisterProtocol("http", httpStreamFactory)
c.API().RegisterProtocol("mcp", mcpStreamFactory)
```

Resolution: `c.API().Stream("charon")` → Drive lookup → extract scheme → find factory → create Stream.

No protocol handler = no capability.

### 19.3 Remote Action Dispatch

Actions transparently cross machine boundaries via `host:action` syntax:

```go
// Local
r := c.RemoteAction("agentic.status", ctx, opts)

// Remote — same API, different host
r := c.RemoteAction("charon:agentic.status", ctx, opts)
// → splits on ":" → endpoint="charon", action="agentic.status"
// → c.API().Call("charon", "agentic.status", opts)

// Web3 — Lethean dVPN routed
r := c.RemoteAction("snider.lthn:brain.recall", ctx, opts)
```

### 19.4 Direct Call

```go
r := c.API().Call("charon", "agentic.dispatch", opts)
// Opens stream, sends JSON-RPC, receives response, closes stream
```

---

## 20. Registry — The Universal Collection Primitive

Thread-safe named collection. The brick all registries build on.

### 20.1 The Type

```go
// Registry is a thread-safe named collection. The universal brick
// for all named registries in Core.
type Registry[T any] struct {
    items  map[string]T
    mu     sync.RWMutex
    locked bool
}
```

### 20.3 Operations

```go
r := core.NewRegistry[*Service]()

r.Set("brain", brainSvc)          // register
r.Get("brain")                     // Result{brainSvc, true}
r.Has("brain")                     // true
r.Names()                          // []string{"brain", "monitor", ...}
r.List("brain.*")                  // glob/prefix match
r.Each(func(name string, item T))  // iterate
r.Len()                            // count
r.Lock()                           // prevent further Set calls
r.Locked()                         // bool
r.Delete("brain")                  // remove (if not locked)
```

### 20.4 Core Accessor

`c.Registry(name)` accesses named registries. Each subsystem's registry is accessible through it:

```go
c.RegistryOf("services")              // the service registry
c.Registry("commands")              // the command tree
c.RegistryOf("actions")               // IPC action handlers
c.RegistryOf("drives")                // transport handles
c.Registry("data")                  // mounted filesystems
```

Cross-cutting queries become natural:

```go
c.RegistryOf("actions").List("process.*")  // all process capabilities
c.RegistryOf("drives").Names()              // all configured transports
c.RegistryOf("services").Has("brain")       // is brain service loaded?
c.RegistryOf("actions").Len()               // how many actions registered?
```

### 20.5 Typed Accessors Are Sugar

The existing subsystem accessors become typed convenience over Registry:

```go
// These are equivalent:
c.Service("brain")                         // typed sugar
c.RegistryOf("services").Get("brain")        // universal access

c.Drive().Get("forge")                     // typed sugar
c.RegistryOf("drives").Get("forge")          // universal access

c.Action("process.run")                    // typed sugar
c.RegistryOf("actions").Get("process.run")   // universal access
```

The typed accessors stay — they're ergonomic and type-safe. `c.Registry()` adds the universal query layer on top.

### 20.6 What Embeds Registry

All named collections in Core embed `Registry[T]`:

- `ServiceRegistry` → `Registry[*Service]`
- `CommandRegistry` → `Registry[*Command]`
- `Drive` → `Registry[*DriveHandle]`
- `Data` → `Registry[*Embed]`
- `Lock.locks` → `Registry[*sync.RWMutex]`
- `IPC.actions` → `Registry[*Action]`
- `IPC.tasks` → `Registry[*Task]`

---

## Design Philosophy

### Core Is Lego Bricks

Core is infrastructure, not an encapsulated library. Downstream packages (core/agent, core/mcp, go-process) compose with Core's primitives. **Exported fields are intentional, not accidental.** Every unexported field that forces a consumer to write a wrapper method adds LOC downstream — the opposite of Core's purpose.

```go
// Core reduces downstream code:
if r.OK { use(r.Value) }

// vs Go convention that adds downstream LOC:
val, err := thing.Get()
if err != nil {
    return fmt.Errorf("get: %w", err)
}
```

This is why `core.Result` exists — it replaces multiple lines of error handling with `if r.OK {}`. That's the design: expose the primitive, reduce consumer code.

### Export Rules

| Should Export | Why |
|--------------|-----|
| Struct fields used by consumers | Removes accessor boilerplate downstream |
| Registry types (`ServiceRegistry`) | Lets consumers extend service management |
| IPC internals (`Ipc` handlers) | Lets consumers build custom dispatch |
| Lifecycle hooks (`OnStart`, `OnStop`) | Composable without interface overhead |

| Should NOT Export | Why |
|------------------|-----|
| Mutexes and sync primitives | Concurrency must be managed by Core |
| Context/cancel pairs | Lifecycle is Core's responsibility |
| Internal counters | Implementation detail, not a brick |

### Why core/go Is Minimal

core/go deliberately avoids importing anything beyond stdlib + go-io + go-log. This keeps it as a near-pure stdlib implementation. Packages that add external dependencies (CLI frameworks, HTTP routers, MCP SDK) live in separate repos:

```
core/go          — pure primitives (stdlib only)
core/go-process  — process management (adds os/exec)
core/mcp         — MCP server (adds go-sdk)
core/agent       — orchestration (adds forge, yaml, mcp)
```

Each layer imports the one below. core/go imports nothing from the ecosystem — everything imports core/go.

## Known Issues — All Resolved

| # | Issue | Resolution |
|---|-------|-----------|
| 1 | UPPERCASE vs CamelCase naming | `c.Action("name")` = primitive, `c.ACTION(msg)` = sugar. `broadcast()` internal. |
| 2 | MustServiceFor uses panic | Kept — `Must` prefix is Go convention. Use only in startup paths. |
| 3 | Embed() legacy accessor | Removed. Use `c.Data().Get("app")`. |
| 4 | Package vs Core logging | Both stay. `core.Info()` = bootstrap. `c.Log().Info()` = runtime. |
| 5 | RegisterAction in task.go | Moved to ipc.go. action.go has execution. task.go has PerformAsync. |
| 6 | serviceRegistry unexported | `ServiceRegistry` embedding `Registry[*Service]`. All 5 registries migrated. |
| 7 | No c.Process() | Implemented — Action sugar over `process.run/start/kill`. |
| 8 | NewRuntime/NewWithFactories | GUI bridge, not legacy. Needs `WithRuntime(app)` CoreOption. |
| 9 | CommandLifecycle interface | Removed. `Command.Managed` string field. Lifecycle verbs are Actions. |
| 10 | Array[T] guardrail | Kept — ordered counterpart to Registry[T]. Model-proof collection ops. |
| 11 | ConfigVar[T] | Kept — distinguishes "set to false" from "never set". Layered config. |
| 12 | Ipc data-only struct | IPC owns Action registry. `c.Action()` is API. `c.IPC()` owns data. |
| 13 | Lock() allocates per call | Lock uses `Registry[*sync.RWMutex]`. Mutex cached. |
| 14 | Startables/Stoppables return type | Return `Result`. Registry.Each iterates in insertion order. |
| 15 | New() comment stale | Fixed — shows `*Core` return with correct example. |
| 16 | task.go mixes concerns | Split: ipc.go (registration), action.go (execution), task.go (async). `type Task any` removed. |

> Full discussion of each issue preserved in git history (commit `0704a7a` and earlier).
> The resolution column IS the current implementation.

## AX Principles Applied

This API follows RFC-025 Agent Experience (AX):

1. **Predictable names** — `Config` not `Cfg`, `Service` not `Srv`
2. **Usage-example comments** — every public function shows HOW with real values
3. **Path is documentation** — `c.Data().ReadString("prompts/coding.md")`
4. **Universal types** — Option, Options, Result everywhere
5. **Event-driven** — ACTION/QUERY broadcast + named Actions, not direct function calls between services
6. **Tests as spec** — `TestFile_Function_{Good,Bad,Ugly}` for every function
7. **Export primitives** — Core is Lego bricks, not an encapsulated library
8. **Naming encodes architecture** — CamelCase = primitive brick, UPPERCASE = consumer convenience
9. **File = concern** — one file, one job (ipc.go = registry, action.go = execution, contract.go = types)

## Findings Summary — 108 Findings Across 13 Passes (All Resolved)

The full discovery process (Passes 2-13) produced 108 findings that reduce to 5 root causes.
All findings are resolved in v0.8.0. Full pass detail preserved in git history.

| Pass | Focus | Findings | Key Resolutions |
|------|-------|----------|----------------|
| 2 | Architecture | 8 | Core fields exported (Lego Bricks), Fs.root exception, Config untyped bag |
| 3 | Spec contradictions | 8 | Startable returns Result, Process returns Result, Registry lock modes |
| 4 | Concurrency | 12 | Registry[T] per-subsystem mutex, WriteAtomic, PerformAsync shutdown race |
| 5 | Consumer experience | 8 | ServiceRuntime + manual .core both valid, HandleIPCEvents documented |
| 6 | Cross-repo cascade | 8 | Task replaces nested ACTION cascade (P6-1), MCP aggregator pattern |
| 7 | Failure modes | 8 | RunE() + defer shutdown, panic recovery in ACTION/Action, SafeGo |
| 8 | Type safety | 8 | Result trade-off accepted, typed convenience methods, AX-7 Ugly tests |
| 9 | Missing primitives | 8 | core.ID(), ValidateName, WriteAtomic, Fs.NewUnrestricted, c.Process() |
| 10 | Spec self-audit | 8 | Subsystem count corrected, cross-reference table, findings index |
| 11 | Security model | 8 | Entitlement primitive (Section 21), Fs.NewUnrestricted, audit logging |
| 12 | Migration risk | 8 | Phase 1 additive (zero breakage), Phase 3 breaking (Startable, CommandLifecycle) |
| 13 | Hidden assumptions | 8 | Single Core per process, Go only, Linux/macOS, static conclave, ephemeral IPC |

## Synthesis — Five Root Causes

> With all 108 findings in context, the patterns emerge. 60 findings
> cluster into 5 root causes. Fix the root, fix the cluster.

### Root Cause 1: Type Erasure via Result{any} — 16 findings

`Result{Value: any, OK: bool}` erases all type information. Every consumer writes bare type assertions that panic on wrong types. The LOC reduction is real but the compile-time safety loss creates 50+ hidden panic sites.

**The tension is fundamental.** Result exists to reduce downstream LOC. But `any` means the compiler can't help. This isn't fixable without abandoning Result — which defeats Core's purpose.

**Mitigation, not fix:** Typed convenience methods (`ReadString`, `ListEntries`, `ConfigGet[T]`). AX-7 Ugly tests for every type assertion. `Registry[T]` where generics work. Accept `Result` as the integration seam where types meet.

### Root Cause 2: No Internal Boundaries — 14 findings

`*Core` grants God Mode. Every service sees everything. The unexported fields were an attempt at boundaries but `unsafe.Pointer` proves they don't work. The conclave has no isolation.

**Resolution:** Section 21 (Entitlement primitive). `c.Entitled()` gates Actions. Default permissive (trusted conclave). Consumer packages replace the checker for SaaS/commerce gating. Port of RFC-004:

```
Registration = capability  ("process.run action exists")
Entitlement  = permission  ("this Core is ALLOWED to run processes")
```

```go
c.Entitled("process.run")     // true if both registered AND permitted
c.Action("process.run").Run() // checks entitlement before executing
```

The Entitlement system (RFC-004) answers "can this workspace do this action?" with package-based feature gating, usage limits, and boost mechanics. Config Channels (RFC-003) add context — "what settings apply on this surface (CLI vs MCP vs HTTP)?" Together they provide the boundary model without removing Lego Bricks — all bricks exist, entitlements control which ones are usable.

See: RFC-003 (Config Channels), RFC-004 (Entitlements), RFC-005 (Commerce Matrix).

### Root Cause 3: Synchronous Everything — 12 findings

IPC dispatch is synchronous. Startup is synchronous. File I/O assumes no concurrency. The one async path (`PerformAsync`) is unbounded. When anything runs concurrently — which it does in production — races emerge.

**The cascade (P6-1) is the symptom.** The root cause is that Core was designed for sequential execution and concurrency was added incrementally without revisiting the foundations.

**Resolution:** The Action/Task system (Section 18) is implemented. `Task` with `Steps` supports sequential chains, async dispatch, and previous-input piping. The cascade fix requires core/agent to wire its handlers as named Actions and replace nested `c.ACTION()` calls with `c.Task("agent.completion").Run(ctx, c, opts)`. See `core/agent/docs/RFC.md` Section 3.

### Root Cause 4: No Recovery Path — 10 findings

Every failure mode is "log and crash." `os.Exit(1)` bypasses defers. Startup failure leaks running services. Panicking handlers crash the process. `SafeGo` exists but isn't used.

**One fix resolves most of this cluster:**

```go
func (c *Core) RunE() error {
    defer c.ServiceShutdown(context.Background())
    // ... returns error, no os.Exit
}
```

`defer` ensures cleanup always runs. `RunE()` returns `error`; `Run()` delegates and exits. Panic recovery in ACTION handlers and Action.Run() prevents cascade crashes.

### Root Cause 5: Missing Primitives — 8 findings

The guardrail coverage was incomplete. Strings have primitives. Paths have primitives. Errors have primitives. IDs, validation, and atomic writes didn't.

**Resolved:**
- `core.ID()` — unique identifier (atomic counter + crypto/rand)
- `core.ValidateName()` / `core.SanitisePath()` — reusable validation
- `Fs.WriteAtomic()` — safe concurrent writes
- `Fs.NewUnrestricted()` — legitimate sandbox bypass

**Open:** `core.Health()` (production monitoring), timestamp convention, JSON helpers.

### What This Means for v0.8.0

The five root causes map to a priority order:

| Priority | Root Cause | Resolution |
|----------|-----------|------------|
| 1 | No recovery (10) | **Done** — `RunE()`, `defer ServiceShutdown`, panic recovery |
| 2 | Synchronous (12) | **Done** — ACTION chain fixed, Task composition |
| 3 | Missing primitives (8) | **Done** — `ID()`, `ValidateName()`, `WriteAtomic()`, `NewUnrestricted()` |
| 4 | Type erasure (16) | **Mitigated** — typed convenience methods, AX-7 Ugly tests, `Registry[T]` |
| 5 | No boundaries (14) | **Done** — `c.Entitled()` + `Action.Run()` enforcement |

All 5 root causes resolved.

### Cross-References — Ecosystem RFCs

Core/go provides the INTERFACE (stdlib only). Consumer packages bring the IMPLEMENTATION:

| Finding | Ecosystem RFC | Core Primitive | Consumer |
|---------|--------------|----------------|----------|
| P13-5: Sync startup | RFC-002 (Event Modules) | `Startable` + registration order | Lazy instantiation |
| P11-1: God Mode | RFC-004 (Entitlements) | `c.Entitled()` | go-entitlements |
| P11-3: Secrets | RFC-012 (SMSG) | `c.Env()` (fallback) | go-smsg / Vault (future primitive) |
| P9-6: Validation | RFC-009 (Sigil) | `ValidateName()` / `SanitisePath()` | Sigil transform chains |
| P11-2: Sandbox bypass | — | `Fs.NewUnrestricted()` | — (resolved in core/go) |
| P13-2: Cross-language | RFC-013 (DataNode) | `c.Data()` mounts `fs.FS` | DataNode / Borg |
| P2-8: Config context | RFC-003 (Config Channels) | `c.Config()` | Channel-aware resolution |

**The pattern:** Core defines a primitive with a Go interface. The RFC describes the concept. A consumer package implements it. Core stays stdlib-only. The ecosystem gets rich features via composition.

```
core/go:          c.Entitled(action) → calls EntitlementChecker
go-entitlements:  replaces checker with package/feature/usage logic
default:          built-in checker returns Allowed=true (trusted conclave)
```

No dependency injected into core/go. The interface is the primitive. The implementation is the consumer.

---

## Consumer RFCs

core/go provides the primitives. These RFCs describe how consumers use them:

| Package | RFC | Scope |
|---------|-----|-------|
| go-process | `core/go-process/docs/RFC.md` | Action handlers for process.run/start/kill, ManagedProcess, daemon registry |
| core/agent | `core/agent/docs/RFC.md` | Named Actions, completion pipeline (P6-1 fix), WriteAtomic migration, Process migration, Entitlement gating |

Each consumer RFC is self-contained — an agent can implement it from the document alone.

---

## Versioning

### Release Model

```
v0.7.x  — previous stable
v0.8.0  — production release: all primitives, all boundaries, all consumers aligned
          Sections 1-21 implemented. 483 tests, 84.7% coverage, 100% AX-7 naming.
v0.8.*  — patches tell us where the agentic process missed things
```

### The Cadence

1. **RFC spec** — design the target version in prose
2. **Implement** — build to spec with AX-7 tests from day one
3. **Refine** — review passes catch drift between spec and code
4. **Tag** — when all sections implemented and tests pass
5. **Measure** — patch count tells you what the spec missed

v0.8.1 means the spec missed one thing. v0.8.15 means fifteen. The patch count IS the quality metric.

### What v0.8.0 Requires

| Requirement | Status |
|-------------|--------|
| All 16 Known Issues resolved in code | **Done** (2026-03-25) |
| Section 17: c.Process() primitive | **Done** — Action sugar |
| Section 18: Action/Task system | **Done** — Action, Task, PerformAsync, type Task any removed |
| Section 19: c.API() streams | **Done** — Stream interface, protocol handlers, RemoteAction |
| Section 20: Registry[T] primitive | **Done** — all 5 registries migrated |
| Section 21: Entitlement primitive | **Done** — Entitled(), SetEntitlementChecker(), RecordUsage(), Action.Run() enforcement |
| AX-7 test coverage at 100% | **Done** — core/go 483 tests (100% naming) |
| Zero os/exec in core/go | **Done** — App.Find() uses os.Stat |
| type Task any removed | **Done** — PerformAsync takes named action + Options |
| Startable/Stoppable return Result | **Done** — breaking, clean |
| CommandLifecycle removed | **Done** → Command.Managed field |
| Consumer RFCs written | **Done** — go-process/docs/RFC.md, core/agent/docs/RFC.md |

### What Blocks v0.8.0 Tag

- go-process v0.7.0 alignment (consumer RFC written, ready to implement)
- core/agent v0.8.0 migration (consumer RFC written, Phase 1 ready)

### What Does NOT Block v0.8.0

- Ecosystem sweep (after consumers align)
- core/cli update (extension, not primitive)

## 21. Entitlement — The Permission Primitive

Core provides the primitive. go-entitlements and commerce-matrix provide implementations.

### 21.1 The Problem

`*Core` grants God Mode (P11-1). Every service sees everything. The 14 findings in Root Cause 2 all stem from this. The conclave is trusted — but the SaaS platform (RFC-004), the commerce hierarchy (RFC-005), and the agent sandbox all need boundaries.

Three systems ask the same question with different vocabulary:

```
Can [subject] do [action] with [quantity] in [context]?
```

| System | Subject | Action | Quantity | Context |
|--------|---------|--------|----------|---------|
| RFC-004 Entitlements | workspace | feature.code | N | active packages |
| RFC-005 Commerce Matrix | entity (M1/M2/M3) | permission.key | 1 | hierarchy path |
| Core Actions | this Core instance | action.name | 1 | registered services |

### 21.2 The Primitive

```go
// Entitlement is the result of a permission check.
// Carries context for both boolean gates (Allowed) and usage limits (Limit/Used/Remaining).
// Maps directly to RFC-004 EntitlementResult and RFC-005 PermissionResult.
type Entitlement struct {
    Allowed   bool   // permission granted
    Unlimited bool   // no cap (agency tier, admin, trusted conclave)
    Limit     int    // total allowed (0 = boolean gate, no quantity dimension)
    Used      int    // current consumption
    Remaining int    // Limit - Used
    Reason    string // denial reason — for UI feedback and audit logging
}

// Entitled checks if an action is permitted in the current context.
// Default: always returns Allowed=true, Unlimited=true (trusted conclave).
// With go-entitlements: checks workspace packages, features, usage, boosts.
// With commerce-matrix: checks entity hierarchy, lock cascade.
//
//   e := c.Entitled("process.run")           // boolean — can this Core run processes?
//   e := c.Entitled("social.accounts", 3)    // quantity — can workspace create 3 more accounts?
//   if e.Allowed { proceed() }
//   if e.NearLimit(0.8) { showWarning() }
func (c *Core) Entitled(action string, quantity ...int) Entitlement
```

### 21.3 The Checker — Consumer-Provided

Core defines the interface. Consumer packages provide the implementation.

```go
// EntitlementChecker answers "can [subject] do [action] with [quantity]?"
// Subject comes from context (workspace, entity, user — consumer's concern).
type EntitlementChecker func(action string, quantity int, ctx context.Context) Entitlement
```

Registration via Core:

```go
// SetEntitlementChecker replaces the default (permissive) checker.
// Called by go-entitlements or commerce-matrix during OnStartup.
//
//   func (s *EntitlementService) OnStartup(ctx context.Context) core.Result {
//       s.Core().SetEntitlementChecker(s.check)
//       return core.Result{OK: true}
//   }
func (c *Core) SetEntitlementChecker(checker EntitlementChecker)
```

Default checker (no entitlements package loaded):

```go
// defaultChecker — trusted conclave, everything permitted
func defaultChecker(action string, quantity int, ctx context.Context) Entitlement {
    return Entitlement{Allowed: true, Unlimited: true}
}
```

### 21.4 Enforcement Point — Action.Run()

The entitlement check lives in `Action.Run()`, before execution. One enforcement point for all capabilities.

```go
func (a *Action) Run(ctx context.Context, opts Options) (result Result) {
    if !a.Exists() { return not-registered }
    if !a.enabled { return disabled }

    // Entitlement check — permission boundary
    if e := a.core.Entitled(a.Name); !e.Allowed {
        return Result{E("action.Run",
            Concat("not entitled: ", a.Name, " — ", e.Reason), nil), false}
    }

    defer func() { /* panic recovery */ }()
    return a.Handler(ctx, opts)
}
```

Three states for any action:

| State | Exists() | Entitled() | Run() |
|-------|----------|------------|-------|
| Not registered | false | — | Result{OK: false} "not registered" |
| Registered, not entitled | true | false | Result{OK: false} "not entitled" |
| Registered and entitled | true | true | executes handler |

### 21.5 How RFC-004 (SaaS Entitlements) Plugs In

go-entitlements registers as a service and replaces the checker:

```go
// In go-entitlements:
func (s *Service) OnStartup(ctx context.Context) core.Result {
    s.Core().SetEntitlementChecker(func(action string, qty int, ctx context.Context) core.Entitlement {
        workspace := s.workspaceFromContext(ctx)
        if workspace == nil {
            return core.Entitlement{Allowed: true, Unlimited: true} // no workspace = system context
        }

        result := s.Can(workspace, action, qty)

        return core.Entitlement{
            Allowed:   result.IsAllowed(),
            Unlimited: result.IsUnlimited(),
            Limit:     result.Limit,
            Used:      result.Used,
            Remaining: result.Remaining,
            Reason:    result.Message(),
        }
    })
    return core.Result{OK: true}
}
```

Maps 1:1 to RFC-004's `EntitlementResult`:
- `$result->isAllowed()` → `e.Allowed`
- `$result->isUnlimited()` → `e.Unlimited`
- `$result->limit` → `e.Limit`
- `$result->used` → `e.Used`
- `$result->remaining` → `e.Remaining`
- `$result->getMessage()` → `e.Reason`
- `$result->isNearLimit()` → `e.NearLimit(0.8)`
- `$result->getUsagePercentage()` → `e.UsagePercent()`

### 21.6 How RFC-005 (Commerce Matrix) Plugs In

commerce-matrix registers and replaces the checker with hierarchy-aware logic:

```go
// In commerce-matrix:
func (s *MatrixService) OnStartup(ctx context.Context) core.Result {
    s.Core().SetEntitlementChecker(func(action string, qty int, ctx context.Context) core.Entitlement {
        entity := s.entityFromContext(ctx)
        if entity == nil {
            return core.Entitlement{Allowed: true, Unlimited: true}
        }

        result := s.Can(entity, action, "")

        return core.Entitlement{
            Allowed: result.IsAllowed(),
            Reason:  result.Reason,
        }
    })
    return core.Result{OK: true}
}
```

Maps to RFC-005's cascade model:
- `M1 says NO → everything below is NO` → checker walks hierarchy, returns `{Allowed: false, Reason: "Locked by M1"}`
- Training mode → checker returns `{Allowed: false, Reason: "undefined — training required"}`
- Production strict mode → undefined = denied

### 21.7 Composing Both Systems

When a SaaS platform ALSO has commerce hierarchy (Host UK), the checker composes internally:

```go
func (s *CompositeService) check(action string, qty int, ctx context.Context) core.Entitlement {
    // Check commerce matrix first (hard permissions)
    matrixResult := s.matrix.Can(entityFromCtx(ctx), action, "")
    if matrixResult.IsDenied() {
        return core.Entitlement{Allowed: false, Reason: matrixResult.Reason}
    }

    // Then check entitlements (usage limits)
    entResult := s.entitlements.Can(workspaceFromCtx(ctx), action, qty)
    return core.Entitlement{
        Allowed:   entResult.IsAllowed(),
        Unlimited: entResult.IsUnlimited(),
        Limit:     entResult.Limit,
        Used:      entResult.Used,
        Remaining: entResult.Remaining,
        Reason:    entResult.Message(),
    }
}
```

Matrix (hierarchy) gates first. Entitlements (usage) gate second. One checker, composed.

### 21.8 Convenience Methods on Entitlement

```go
// NearLimit returns true if usage exceeds the threshold percentage.
// RFC-004: $result->isNearLimit() uses 80% threshold.
//
//   if e.NearLimit(0.8) { showUpgradePrompt() }
func (e Entitlement) NearLimit(threshold float64) bool

// UsagePercent returns current usage as a percentage of the limit.
// RFC-004: $result->getUsagePercentage()
//
//   pct := e.UsagePercent()  // 75.0
func (e Entitlement) UsagePercent() float64

// RecordUsage is called after a gated action succeeds.
// Delegates to the entitlement service for usage tracking.
// This is the equivalent of RFC-004's $workspace->recordUsage().
//
//   e := c.Entitled("ai.credits", 10)
//   if e.Allowed {
//       doWork()
//       c.RecordUsage("ai.credits", 10)
//   }
func (c *Core) RecordUsage(action string, quantity ...int)
```

### 21.9 Audit Trail — RFC-004 Section: Audit Logging

Every entitlement check can be logged via `core.Security()`:

```go
func (c *Core) Entitled(action string, quantity ...int) Entitlement {
    qty := 1
    if len(quantity) > 0 {
        qty = quantity[0]
    }

    e := c.entitlementChecker(action, qty, c.Context())

    // Audit logging for denials (P11-6)
    if !e.Allowed {
        Security("entitlement.denied", "action", action, "quantity", qty, "reason", e.Reason)
    }

    return e
}
```

### 21.10 Core Struct Changes

```go
type Core struct {
    // ... existing fields ...
    entitlementChecker EntitlementChecker  // default: everything permitted
}
```

Constructor:

```go
func New(opts ...CoreOption) *Core {
    c := &Core{
        // ... existing ...
        entitlementChecker: defaultChecker,
    }
    // ...
}
```

### 21.11 What This Does NOT Do

- **Does not add database dependencies** — Core is stdlib only. Usage tracking, package management, billing — all in consumer packages.
- **Does not define features** — The feature catalogue (social.accounts, ai.credits, etc.) is defined by the SaaS platform, not Core.
- **Does not manage subscriptions** — Commerce (RFC-005) and billing (Blesta/Stripe) are consumer concerns.
- **Does not replace Action registration** — Registration IS capability. Entitlement IS permission. Both must be true.
- **Does not enforce at Config/Data/Fs level** — v0.8.0 gates Actions. Config/Data/Fs gating requires per-subsystem entitlement checks (same pattern, more integration points).

### 21.12 The Subsystem Map (Updated)

```
c.Registry()     — universal named collection
c.Options()      — input configuration
c.App()          — identity
c.Config()       — runtime settings
c.Data()         — embedded assets
c.Drive()        — connection config (WHERE)
c.API()          — remote streams (HOW) [planned]
c.Fs()           — filesystem
c.Process()      — managed execution (Action sugar)
c.Action()       — named callables (register, invoke, inspect)
c.Task()         — composed Action sequences
c.IPC()          — local message bus
c.Cli()          — command tree
c.Log()          — logging
c.Error()        — panic recovery
c.I18n()         — internationalisation
c.Entitled()     — permission check (NEW)
c.RecordUsage()  — usage tracking (NEW)
```

---

## Changelog

- 2026-03-25: v0.8.0 — All 21 sections implemented. 483 tests, 84.7% coverage, 100% AX-7 naming.
- 2026-03-25: Initial specification created from 500k token discovery session. 108 findings, 5 root causes, 13 review passes. Discovery detail preserved in git history.