From c42e7ad05091a98c367efcf50cb4f6956d0b5f64 Mon Sep 17 00:00:00 2001
From: Virgil <virgil@lethean.io>
Date: Thu, 2 Apr 2026 17:35:43 +0000
Subject: [PATCH] fix(mcp): harden subsystem interface contracts

---
 pkg/mcp/agentic/prep.go | 6 ++++++
 pkg/mcp/brain/brain.go  | 6 ++++++
 pkg/mcp/brain/direct.go | 6 ++++++
 pkg/mcp/ide/ide.go      | 6 ++++++
 4 files changed, 24 insertions(+)

diff --git a/pkg/mcp/agentic/prep.go b/pkg/mcp/agentic/prep.go
index 55aae8d..fdfa121 100644
--- a/pkg/mcp/agentic/prep.go
+++ b/pkg/mcp/agentic/prep.go
@@ -36,6 +36,12 @@ type PrepSubsystem struct {
 	notifier   coremcp.Notifier
 }
 
+var (
+	_ coremcp.Subsystem             = (*PrepSubsystem)(nil)
+	_ coremcp.SubsystemWithShutdown = (*PrepSubsystem)(nil)
+	_ coremcp.SubsystemWithNotifier = (*PrepSubsystem)(nil)
+)
+
 // NewPrep creates an agentic subsystem.
 //
 //	prep := NewPrep()
diff --git a/pkg/mcp/brain/brain.go b/pkg/mcp/brain/brain.go
index d8b1e3f..87357dc 100644
--- a/pkg/mcp/brain/brain.go
+++ b/pkg/mcp/brain/brain.go
@@ -23,6 +23,12 @@ type Subsystem struct {
 	notifier coremcp.Notifier
 }
 
+var (
+	_ coremcp.Subsystem             = (*Subsystem)(nil)
+	_ coremcp.SubsystemWithShutdown = (*Subsystem)(nil)
+	_ coremcp.SubsystemWithNotifier = (*Subsystem)(nil)
+)
+
 // New creates a brain subsystem that uses the given IDE bridge for Laravel communication.
 //
 //	brain := New(ideBridge)
diff --git a/pkg/mcp/brain/direct.go b/pkg/mcp/brain/direct.go
index 739b9a6..85beccc 100644
--- a/pkg/mcp/brain/direct.go
+++ b/pkg/mcp/brain/direct.go
@@ -35,6 +35,12 @@ type DirectSubsystem struct {
 	onChannel channelSender
 }
 
+var (
+	_ coremcp.Subsystem                    = (*DirectSubsystem)(nil)
+	_ coremcp.SubsystemWithShutdown        = (*DirectSubsystem)(nil)
+	_ coremcp.SubsystemWithChannelCallback = (*DirectSubsystem)(nil)
+)
+
 // OnChannel sets a callback for channel event broadcasting.
 // Called by the MCP service after creation to wire up notifications.
 //
diff --git a/pkg/mcp/ide/ide.go b/pkg/mcp/ide/ide.go
index 3713d4f..6347788 100644
--- a/pkg/mcp/ide/ide.go
+++ b/pkg/mcp/ide/ide.go
@@ -35,6 +35,12 @@ type Subsystem struct {
 	activity     []ActivityEvent
 }
 
+var (
+	_ coremcp.Subsystem             = (*Subsystem)(nil)
+	_ coremcp.SubsystemWithShutdown = (*Subsystem)(nil)
+	_ coremcp.SubsystemWithNotifier = (*Subsystem)(nil)
+)
+
 // New creates an IDE subsystem from a Config DTO.
 //
 //	cfg := DefaultConfig()