feat(agent): RFC §9 agentic_auth_login MCP tool + dedupe tool registrations

Three load-bearing gaps between the agent RFC and the MCP surface:

- RFC §9 Fleet Mode describes the 6-digit pairing-code bootstrap as the
  primary way an unauthenticated node provisions its first AgentApiKey.
  `handleAuthLogin` existed as an Action but never surfaced as an MCP
  tool, so IDE/CLI callers had to shell out. Adds `agentic_auth_login`
  under `registerPlatformTools` with a thin wrapper over the existing
  handler so the platform contract stays single-sourced.
- `RegisterTools` was double-registering `agentic_scan` (bare
  `mcp.AddTool` before the CORE_MCP_FULL gate, then again via
  `AddToolRecorded` inside the gate). The second call silently replaced
  the first and bypassed tool-registry accounting, so REST bridging and
  metrics saw a zero for scan. Collapses both into a single recorded
  registration before the gate.
- `registerPlanTools` and `registerWatchTool` were also fired twice in
  the CORE_MCP_FULL branch. Removes the duplicates so the extended
  registration list mirrors the always-on list exactly once.
- Switches `agentic_prep_workspace` from bare `mcp.AddTool` to
  `AddToolRecorded` so prep-workspace participates in the same
  accounting as every other RFC §6 tool.

TestPrep_RegisterTools_Good_RegistersCompletionTool now asserts all
three `agentic_auth_*` tools surface, covering the new login registration
alongside provision/revoke.

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

pkg/agentic/platform_tools.go

@@ -120,6 +120,11 @@ func (s *PrepSubsystem) registerPlatformTools(svc *coremcp.Service) {
 		Description: "Revoke a platform API key by key ID.",
 	}, s.authRevokeTool)
 
+	coremcp.AddToolRecorded(svc, svc.Server(), "agentic", &mcp.Tool{
+		Name:        "agentic_auth_login",
+		Description: "Exchange a 6-digit pairing code (generated at app.lthn.ai/device) for an AgentApiKey. Bootstraps a fleet node without requiring an existing API key — RFC §9 Fleet Mode.",
+	}, s.authLoginTool)
+
 	coremcp.AddToolRecorded(svc, svc.Server(), "agentic", &mcp.Tool{
 		Name:        "agentic_fleet_register",
 		Description: "Register a fleet node with models, capabilities, and platform metadata.",
@@ -256,6 +261,30 @@ func (s *PrepSubsystem) authRevokeTool(ctx context.Context, _ *mcp.CallToolReque
 	return nil, output, nil
 }
 
+// authLoginTool handles the MCP-side of the RFC §9 pairing-code bootstrap.
+// Callers pass a 6-digit pairing code generated at app.lthn.ai/device and
+// receive the provisioned AgentApiKey so the node can authenticate future
+// platform calls. The code itself is the proof — no existing API key is
+// required.
+//
+// Usage example:
+//
+//	out, _ := clientSession.CallTool(ctx, &mcp.CallToolParams{
+//	    Name:      "agentic_auth_login",
+//	    Arguments: json.RawMessage(`{"code": "123456"}`),
+//	})
+func (s *PrepSubsystem) authLoginTool(ctx context.Context, _ *mcp.CallToolRequest, input AuthLoginInput) (*mcp.CallToolResult, AuthLoginOutput, error) {
+	result := s.handleAuthLogin(ctx, platformOptions(core.Option{Key: "code", Value: input.Code}))
+	if !result.OK {
+		return nil, AuthLoginOutput{}, resultErrorValue("agentic.auth.login", result)
+	}
+	output, ok := result.Value.(AuthLoginOutput)
+	if !ok {
+		return nil, AuthLoginOutput{}, core.E("agentic.auth.login", "invalid auth login output", nil)
+	}
+	return nil, output, nil
+}
+
 func (s *PrepSubsystem) fleetRegisterTool(ctx context.Context, _ *mcp.CallToolRequest, input FleetNode) (*mcp.CallToolResult, FleetNode, error) {
 	options := platformOptions(
 		core.Option{Key: "agent_id", Value: input.AgentID},

pkg/agentic/prep.go

@@ -595,7 +595,7 @@ func (s *PrepSubsystem) SetCore(c *core.Core) {
 // subsystem := agentic.NewPrep()
 // subsystem.RegisterTools(svc)
 func (s *PrepSubsystem) RegisterTools(svc *coremcp.Service) {
-	mcp.AddTool(svc.Server(), &mcp.Tool{
+	coremcp.AddToolRecorded(svc, svc.Server(), "agentic", &mcp.Tool{
 		Name:        "agentic_prep_workspace",
 		Description: "Prepare an agent workspace: clone repo, create branch, build prompt with context.",
 	}, s.prepWorkspace)
@@ -617,7 +617,7 @@ func (s *PrepSubsystem) RegisterTools(svc *coremcp.Service) {
 	s.registerWatchTool(svc)
 	s.registerIssueTools(svc)
 	s.registerPRTools(svc)
-	mcp.AddTool(svc.Server(), &mcp.Tool{
+	coremcp.AddToolRecorded(svc, svc.Server(), "agentic", &mcp.Tool{
 		Name:        "agentic_scan",
 		Description: "Scan Forge repos for open issues with actionable labels (agentic, help-wanted, bug).",
 	}, s.scan)
@@ -642,14 +642,6 @@ func (s *PrepSubsystem) RegisterTools(svc *coremcp.Service) {
 	s.registerContentTools(svc)
 	s.registerLanguageTools(svc)
 	s.registerSetupTool(svc)
-
-	coremcp.AddToolRecorded(svc, svc.Server(), "agentic", &mcp.Tool{
-		Name:        "agentic_scan",
-		Description: "Scan Forge repos for open issues with actionable labels (agentic, help-wanted, bug).",
-	}, s.scan)
-
-	s.registerPlanTools(svc)
-	s.registerWatchTool(svc)
 }
 
 // subsystem := agentic.NewPrep()

pkg/agentic/prep_test.go

@@ -739,6 +739,12 @@ func TestPrep_RegisterTools_Good_RegistersCompletionTool(t *testing.T) {
 	assert.Contains(t, toolNames, "agent_inbox")
 	assert.Contains(t, toolNames, "agentic_message_conversation")
 	assert.Contains(t, toolNames, "agent_conversation")
+	// RFC §9 pairing-code bootstrap exposes the login flow as an MCP tool so
+	// IDE/CLI callers can exchange a 6-digit code for an AgentApiKey without
+	// shelling out.
+	assert.Contains(t, toolNames, "agentic_auth_login")
+	assert.Contains(t, toolNames, "agentic_auth_provision")
+	assert.Contains(t, toolNames, "agentic_auth_revoke")
 }
 
 func TestPrep_OnStartup_Good_RegistersGenerateCommand(t *testing.T) {