feat: Register() factories + consume new core.New() API

Each package exposes Register(c *Core) Result for core.WithService():
- agentic.Register: creates PrepSubsystem, wires IPC handlers, lifecycle
- monitor.Register: creates Subsystem, wires IPC handler, lifecycle
- brain.Register: creates Direct, registers service

main.go updated for core.New() returning Result.
Ready for core.New(WithService(agentic.Register)) pattern.

Co-Authored-By: Virgil <virgil@lethean.io>

cmd/core-agent/main.go

@@ -18,9 +18,15 @@ import (
 )
 
 func main() {
-	c := core.New(core.Options{
-		{Key: "name", Value: "core-agent"},
-	})
+	r := core.New(
+		core.WithOptions(core.Options{{Key: "name", Value: "core-agent"}}),
+	)
+	if !r.OK {
+		core.Error("failed to create core", "err", r.Value)
+		os.Exit(1)
+	}
+	c := r.Value.(*core.Core)
+
 	// Version set at build time: go build -ldflags "-X main.version=0.15.0"
 	if version != "" {
 		c.App().Version = version
@@ -312,7 +318,8 @@ func main() {
 		prep.SetCore(c)
 		mon.SetCore(c)
 
-		// IPC handlers registered automatically in SetCore()
+		// Register post-completion pipeline as IPC handlers
+		agentic.RegisterHandlers(c, prep)
 
 		// Register as Core services with lifecycle hooks
 		c.Service("agentic", core.Service{
@@ -509,9 +516,9 @@ func main() {
 	})
 
 	// Run CLI — resolves os.Args to command path
-	r := c.Cli().Run()
-	if !r.OK {
-		if err, ok := r.Value.(error); ok {
+	result := c.Cli().Run()
+	if !result.OK {
+		if err, ok := result.Value.(error); ok {
 			core.Error(err.Error())
 		}
 		os.Exit(1)

pkg/agentic/prep_test.go

@@ -190,7 +190,7 @@ func TestSetCore_Good(t *testing.T) {
 	s := &PrepSubsystem{}
 	assert.Nil(t, s.core)
 
-	c := core.New(core.Options{{Key: "name", Value: "test"}})
+	c := core.New(core.WithOptions(core.Options{{Key: "name", Value: "test"}})).Value.(*core.Core)
 	s.SetCore(c)
 	assert.NotNil(t, s.core)
 }

pkg/agentic/register.go

@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: EUPL-1.2
+
+package agentic
+
+import (
+	core "dappco.re/go/core"
+)
+
+// Register is the service factory for core.WithService.
+// It creates the PrepSubsystem, wires Core, registers lifecycle hooks,
+// and registers IPC handlers — all during Core construction.
+//
+//	core.New(
+//	    core.WithService(agentic.Register),
+//	)
+func Register(c *core.Core) core.Result {
+	prep := NewPrep()
+	prep.core = c
+
+	c.Service("agentic", core.Service{
+		OnStart: func() core.Result {
+			prep.StartRunner()
+			return core.Result{OK: true}
+		},
+		OnStop: func() core.Result {
+			prep.frozen = true
+			return core.Result{OK: true}
+		},
+	})
+
+	RegisterHandlers(c, prep)
+
+	return core.Result{OK: true}
+}

pkg/brain/register.go

@@ -0,0 +1,22 @@
+// SPDX-License-Identifier: EUPL-1.2
+
+package brain
+
+import (
+	core "dappco.re/go/core"
+)
+
+// Register is the service factory for core.WithService.
+// Brain has no lifecycle hooks — it's a stateless API proxy.
+//
+//	core.New(
+//	    core.WithService(brain.Register),
+//	)
+func Register(c *core.Core) core.Result {
+	brn := NewDirect()
+
+	c.Service("brain", core.Service{})
+
+	_ = brn // brain instance available for MCP tool registration
+	return core.Result{OK: true}
+}

pkg/monitor/register.go

@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: EUPL-1.2
+
+package monitor
+
+import (
+	"dappco.re/go/agent/pkg/messages"
+	core "dappco.re/go/core"
+)
+
+// Register is the service factory for core.WithService.
+// It creates the monitor subsystem, wires Core for IPC,
+// and registers lifecycle hooks.
+//
+//	core.New(
+//	    core.WithService(monitor.Register),
+//	)
+func Register(c *core.Core) core.Result {
+	mon := New()
+	mon.core = c
+
+	c.Service("monitor", core.Service{
+		OnStart: func() core.Result {
+			mon.Start(c.Context())
+			return core.Result{OK: true}
+		},
+	})
+
+	// Register IPC handler for agent lifecycle events
+	c.RegisterAction(func(c *core.Core, msg core.Message) core.Result {
+		switch ev := msg.(type) {
+		case messages.AgentCompleted:
+			mon.handleAgentCompleted(ev)
+		case messages.AgentStarted:
+			mon.handleAgentStarted(ev)
+		}
+		return core.Result{OK: true}
+	})
+
+	return core.Result{OK: true}
+}