fix(backend): pass HTTP MCP servers to ACP agents via AssumeMcpHttp (#1152)

* fix(backend): pass HTTP MCP servers to ACP agents via AssumeMcpHttp

* test(backend): cover AssumeMcpHttp override path with effectiveMcpCapabilities helper

apps/backend/internal/agent/agents/agent.go

@@ -180,6 +180,7 @@ type RuntimeConfig struct {
 	ModelFlag       Param  // e.g. NewParam("--model", "{model}")
 	WorkspaceFlag   string // e.g. "--workspace-root"
 	AssumeMcpSse    bool   // Override: assume agent supports SSE MCP servers even if not advertised
+	AssumeMcpHttp   bool   // Override: assume agent supports HTTP MCP servers even if not advertised
 	ProjectSkillDir string // CWD-relative path for project-level skills (e.g. ".claude/skills")
 	UserSkillDir    string // home-relative path for user-level skills (e.g. ".claude/skills")
 }

apps/backend/internal/agent/agents/auggie.go

@@ -101,6 +101,7 @@ func (a *Auggie) Runtime() *RuntimeConfig {
 		Protocol:        agent.ProtocolACP,
 		WorkspaceFlag:   "--workspace-root",
 		AssumeMcpSse:    true,
+		AssumeMcpHttp:   true,
 		ProjectSkillDir: ".agents/skills",
 		SessionConfig: SessionConfig{
 			NativeSessionResume: true,

apps/backend/internal/agent/runtime/agentctl/control.go

@@ -52,6 +52,7 @@ type CreateInstanceRequest struct {
 	TaskID             string            `json:"task_id,omitempty"`              // Task ID for MCP plan tool calls (server-side injection)
 	DisableAskQuestion bool              `json:"disable_ask_question,omitempty"` // Disable ask_user_question MCP tool (TUI agents)
 	AssumeMcpSse       bool              `json:"assume_mcp_sse,omitempty"`       // Assume agent supports SSE MCP servers
+	AssumeMcpHttp      bool              `json:"assume_mcp_http,omitempty"`      // Assume agent supports HTTP MCP servers
 	McpMode            string            `json:"mcp_mode,omitempty"`             // MCP tool mode: "task" (default) or "config"
 }
 

apps/backend/internal/agent/runtime/lifecycle/container.go

@@ -202,9 +202,11 @@ func (cm *ContainerManager) createInstanceAndClient(
 	}
 	disableAskQuestion := agents.IsPassthroughOnly(config.AgentConfig)
 	assumeMcpSse := false
+	assumeMcpHttp := false
 	if config.AgentConfig != nil {
 		if rt := config.AgentConfig.Runtime(); rt != nil {
 			assumeMcpSse = rt.AssumeMcpSse
+			assumeMcpHttp = rt.AssumeMcpHttp
 		}
 	}
 
@@ -219,6 +221,7 @@ func (cm *ContainerManager) createInstanceAndClient(
 		SessionID:          config.SessionID,
 		DisableAskQuestion: disableAskQuestion,
 		AssumeMcpSse:       assumeMcpSse,
+		AssumeMcpHttp:      assumeMcpHttp,
 		McpMode:            config.McpMode,
 	}
 

apps/backend/internal/agent/runtime/lifecycle/executor_docker.go

@@ -443,11 +443,13 @@ func buildReconnectCreateInstanceRequest(req *ExecutorCreateRequest, instanceID
 	agentType := ""
 	disableAskQuestion := false
 	assumeMcpSse := false
+	assumeMcpHttp := false
 	if req.AgentConfig != nil {
 		agentType = req.AgentConfig.ID()
 		disableAskQuestion = agents.IsPassthroughOnly(req.AgentConfig)
 		if rt := req.AgentConfig.Runtime(); rt != nil {
 			assumeMcpSse = rt.AssumeMcpSse
+			assumeMcpHttp = rt.AssumeMcpHttp
 		}
 	}
 	return &agentctl.CreateInstanceRequest{
@@ -461,6 +463,7 @@ func buildReconnectCreateInstanceRequest(req *ExecutorCreateRequest, instanceID
 		TaskID:             req.TaskID,
 		DisableAskQuestion: disableAskQuestion,
 		AssumeMcpSse:       assumeMcpSse,
+		AssumeMcpHttp:      assumeMcpHttp,
 		McpMode:            req.McpMode,
 	}
 }

apps/backend/internal/agent/runtime/lifecycle/executor_docker_test.go

@@ -515,7 +515,8 @@ func TestBuildReconnectCreateInstanceRequest(t *testing.T) {
 			id:      "codex",
 			enabled: true,
 			runtimeConfig: &agents.RuntimeConfig{
-				AssumeMcpSse: true,
+				AssumeMcpSse:  true,
+				AssumeMcpHttp: true,
 			},
 		},
 		Env: map[string]string{
@@ -547,6 +548,9 @@ func TestBuildReconnectCreateInstanceRequest(t *testing.T) {
 	if !got.AssumeMcpSse {
 		t.Fatal("expected AssumeMcpSse to be propagated")
 	}
+	if !got.AssumeMcpHttp {
+		t.Fatal("expected AssumeMcpHttp to be propagated")
+	}
 	if got.McpMode != "config" {
 		t.Fatalf("McpMode = %q, want config", got.McpMode)
 	}

apps/backend/internal/agent/runtime/lifecycle/executor_standalone.go

@@ -96,9 +96,11 @@ func (r *StandaloneExecutor) CreateInstance(ctx context.Context, req *ExecutorCr
 	}
 	disableAskQuestion := agents.IsPassthroughOnly(req.AgentConfig)
 	assumeMcpSse := false
+	assumeMcpHttp := false
 	if req.AgentConfig != nil {
 		if rt := req.AgentConfig.Runtime(); rt != nil {
 			assumeMcpSse = rt.AssumeMcpSse
+			assumeMcpHttp = rt.AssumeMcpHttp
 		}
 	}
 
@@ -115,6 +117,7 @@ func (r *StandaloneExecutor) CreateInstance(ctx context.Context, req *ExecutorCr
 		TaskID:             req.TaskID,
 		DisableAskQuestion: disableAskQuestion,
 		AssumeMcpSse:       assumeMcpSse,
+		AssumeMcpHttp:      assumeMcpHttp,
 		McpMode:            req.McpMode,
 	}
 

apps/backend/internal/agentctl/server/adapter/adapter.go

@@ -267,6 +267,9 @@ type Config struct {
 
 	// AssumeMcpSse overrides MCP capability filtering to assume SSE support.
 	AssumeMcpSse bool
+
+	// AssumeMcpHttp overrides MCP capability filtering to assume HTTP support.
+	AssumeMcpHttp bool
 }
 
 // ToSharedConfig converts this Config to the shared.Config used by transport adapters.
@@ -296,5 +299,6 @@ func (c *Config) ToSharedConfig() *shared.Config {
 		Headers:        c.Headers,
 		Extra:          c.Extra,
 		AssumeMcpSse:   c.AssumeMcpSse,
+		AssumeMcpHttp:  c.AssumeMcpHttp,
 	}
 }

apps/backend/internal/agentctl/server/adapter/transport/acp/adapter_session.go

@@ -36,10 +36,7 @@ func (a *Adapter) NewSession(ctx context.Context, mcpServers []types.McpServer)
 	ctx, span := shared.TraceProtocolRequest(ctx, shared.ProtocolACP, a.agentID, "session.new")
 	defer span.End()
 
-	caps := a.capabilities.McpCapabilities
-	if a.cfg.AssumeMcpSse {
-		caps.Sse = true
-	}
+	caps := effectiveMcpCapabilities(a.capabilities.McpCapabilities, a.cfg)
 	filteredServers := filterMcpServersByCapabilities(mcpServers, caps, a.logger)
 	resp, err := conn.NewSession(ctx, acp.NewSessionRequest{
 		Cwd:        a.cfg.WorkDir,
@@ -90,6 +87,24 @@ func (a *Adapter) NewSession(ctx context.Context, mcpServers []types.McpServer)
 	return sessionID, nil
 }
 
+// effectiveMcpCapabilities applies the adapter's AssumeMcpSse/AssumeMcpHttp
+// config overrides on top of the capabilities advertised by the agent during
+// the ACP handshake. Some agents (e.g. Auggie) support SSE/HTTP MCP transports
+// but don't advertise the corresponding capability, which would otherwise cause
+// filterMcpServersByCapabilities to drop user-configured remote MCP servers.
+func effectiveMcpCapabilities(caps acp.McpCapabilities, cfg *shared.Config) acp.McpCapabilities {
+	if cfg == nil {
+		return caps
+	}
+	if cfg.AssumeMcpSse {
+		caps.Sse = true
+	}
+	if cfg.AssumeMcpHttp {
+		caps.Http = true
+	}
+	return caps
+}
+
 // filterMcpServersByCapabilities removes MCP servers that the agent doesn't support.
 // Stdio servers are always allowed; SSE/HTTP servers require the corresponding capability.
 // If multiple servers share the same name (e.g., dual SSE+HTTP injection), only the first
@@ -225,10 +240,7 @@ func (a *Adapter) LoadSession(ctx context.Context, sessionID string, mcpServers
 	defer span.End()
 
 	// Filter MCP servers by agent capabilities (same logic as NewSession).
-	caps := a.capabilities.McpCapabilities
-	if a.cfg.AssumeMcpSse {
-		caps.Sse = true
-	}
+	caps := effectiveMcpCapabilities(a.capabilities.McpCapabilities, a.cfg)
 	filteredServers := filterMcpServersByCapabilities(mcpServers, caps, a.logger)
 
 	// Suppress history replay notifications during load.

apps/backend/internal/agentctl/server/adapter/transport/acp/mcp_test.go

@@ -4,6 +4,7 @@ import (
 	"testing"
 
 	"github.com/coder/acp-go-sdk"
+	"github.com/kandev/kandev/internal/agentctl/server/adapter/transport/shared"
 	"github.com/kandev/kandev/internal/agentctl/types"
 	"github.com/kandev/kandev/internal/common/logger"
 )
@@ -390,3 +391,39 @@ func TestFilterMcpServersByCapabilities_DeduplicatesSameName(t *testing.T) {
 func newTestLoggerForMcp() *logger.Logger {
 	return newTestAdapter().logger
 }
+
+// --- effectiveMcpCapabilities ---
+
+func TestEffectiveMcpCapabilities_AssumeHTTPAndSSE(t *testing.T) {
+	// Agent advertises neither SSE nor HTTP.
+	base := acp.McpCapabilities{Sse: false, Http: false}
+
+	// Nil config leaves capabilities untouched.
+	if got := effectiveMcpCapabilities(base, nil); got.Sse || got.Http {
+		t.Errorf("nil cfg should not alter caps, got %+v", got)
+	}
+
+	// AssumeMcpHttp forces Http on (and an http server then survives the filter).
+	caps := effectiveMcpCapabilities(base, &shared.Config{AssumeMcpHttp: true})
+	if !caps.Http {
+		t.Fatal("AssumeMcpHttp should force caps.Http = true")
+	}
+	if caps.Sse {
+		t.Error("AssumeMcpHttp should not affect caps.Sse")
+	}
+
+	log := newTestLoggerForMcp()
+	httpServer := []types.McpServer{{Name: "remote", Type: "http", URL: "https://mcp.example.com/mcp"}}
+	if got := filterMcpServersByCapabilities(httpServer, caps, log); len(got) != 1 {
+		t.Fatalf("http server should survive when AssumeMcpHttp set, got %d servers", len(got))
+	}
+
+	// AssumeMcpSse forces Sse on independently.
+	caps = effectiveMcpCapabilities(base, &shared.Config{AssumeMcpSse: true})
+	if !caps.Sse {
+		t.Fatal("AssumeMcpSse should force caps.Sse = true")
+	}
+	if caps.Http {
+		t.Error("AssumeMcpSse should not affect caps.Http")
+	}
+}

apps/backend/internal/agentctl/server/adapter/transport/shared/config.go

@@ -49,6 +49,9 @@ type Config struct {
 
 	// AssumeMcpSse overrides MCP capability filtering to assume SSE support.
 	AssumeMcpSse bool
+
+	// AssumeMcpHttp overrides MCP capability filtering to assume HTTP support.
+	AssumeMcpHttp bool
 }
 
 // GetPermissionTimeout returns the configured permission timeout or the default.

apps/backend/internal/agentctl/server/config/config.go

@@ -192,6 +192,9 @@ type InstanceConfig struct {
 	// AssumeMcpSse overrides MCP capability filtering to assume the agent supports SSE.
 	AssumeMcpSse bool
 
+	// AssumeMcpHttp overrides MCP capability filtering to assume the agent supports HTTP.
+	AssumeMcpHttp bool
+
 	// McpMode controls which MCP tools are registered for this instance.
 	// "task" (default) registers kanban/plan tools; "config" registers config tools.
 	McpMode string
@@ -348,6 +351,9 @@ func applyOverrides(cfg *InstanceConfig, overrides *InstanceOverrides) {
 	if overrides.AssumeMcpSse {
 		cfg.AssumeMcpSse = true
 	}
+	if overrides.AssumeMcpHttp {
+		cfg.AssumeMcpHttp = true
+	}
 	if overrides.McpMode != "" {
 		cfg.McpMode = overrides.McpMode
 	}
@@ -368,6 +374,7 @@ type InstanceOverrides struct {
 	TaskID             string
 	DisableAskQuestion bool
 	AssumeMcpSse       bool
+	AssumeMcpHttp      bool
 	McpMode            string
 }
 

apps/backend/internal/agentctl/server/instance/instance.go

@@ -95,6 +95,9 @@ type CreateRequest struct {
 	// AssumeMcpSse overrides MCP capability filtering to assume SSE support.
 	AssumeMcpSse bool `json:"assume_mcp_sse,omitempty"`
 
+	// AssumeMcpHttp overrides MCP capability filtering to assume HTTP support.
+	AssumeMcpHttp bool `json:"assume_mcp_http,omitempty"`
+
 	// McpMode controls which MCP tools are registered: "task" (default) or "config".
 	McpMode string `json:"mcp_mode,omitempty"`
 }

apps/backend/internal/agentctl/server/instance/manager.go

@@ -93,6 +93,7 @@ func (m *Manager) CreateInstance(ctx context.Context, req *CreateRequest) (*Crea
 		TaskID:             req.TaskID,
 		DisableAskQuestion: req.DisableAskQuestion,
 		AssumeMcpSse:       req.AssumeMcpSse,
+		AssumeMcpHttp:      req.AssumeMcpHttp,
 		McpMode:            req.McpMode,
 	}
 

apps/backend/internal/agentctl/server/process/manager.go

@@ -634,6 +634,7 @@ func (m *Manager) buildAdapterConfig() error {
 		McpServers:     mcpServers,
 		AgentID:        m.cfg.AgentType, // From registry (e.g., "auggie", "amp", "claude-code")
 		AssumeMcpSse:   m.cfg.AssumeMcpSse,
+		AssumeMcpHttp:  m.cfg.AssumeMcpHttp,
 	}
 
 	// Configure one-shot mode when a continue command is provided.