fix(agents): critical model selection bug — approved_models schema mismatch

- setup.yaml had approved_models nested under defaults (wrong), moved to top-level with for_actions (correct Go struct schema)
- ModelSelector now REFUSES to fall through to scored catalog when approved models are configured — prevents garbage/spam models like 'Hunter Alpha'
- Added initial ACP protocol layer (internal/acp/)

Author: Test

.github/workflows/cd.yml

@@ -150,6 +150,9 @@ jobs:
           git tag -a "$NEW_TAG" -m "Automated release $NEW_TAG"
           git push origin "$NEW_TAG"
       
+      - name: Build binary for E2E tests
+        run: go build -o $(go env GOPATH)/bin/gptcode ./cmd/gptcode
+        
       - name: Run tests
         run: go test -v ./...
 

internal/acp/protocol.go

@@ -0,0 +1,339 @@
+// Package acp implements the Agent Client Protocol (ACP) for GPTCode CLI.
+//
+// ACP is a JSON-RPC 2.0 based protocol that standardizes communication between
+// code editors/IDEs and AI coding agents. It is analogous to LSP but for AI agents.
+//
+// Transport: stdio (newline-delimited JSON-RPC messages)
+// Spec: https://agentclientprotocol.com
+package acp
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+// ProtocolVersion is the ACP protocol version we support.
+const ProtocolVersion = 1
+
+// --- JSON-RPC 2.0 types ---
+
+// Request represents a JSON-RPC 2.0 request from client or agent.
+type Request struct {
+	JSONRPC string          `json:"jsonrpc"`
+	ID      interface{}     `json:"id"`
+	Method  string          `json:"method"`
+	Params  json.RawMessage `json:"params,omitempty"`
+}
+
+// Response represents a JSON-RPC 2.0 response.
+type Response struct {
+	JSONRPC string      `json:"jsonrpc"`
+	ID      interface{} `json:"id"`
+	Result  interface{} `json:"result,omitempty"`
+	Error   *RPCError   `json:"error,omitempty"`
+}
+
+// Notification represents a JSON-RPC 2.0 notification (no ID, no response expected).
+type Notification struct {
+	JSONRPC string      `json:"jsonrpc"`
+	Method  string      `json:"method"`
+	Params  interface{} `json:"params,omitempty"`
+}
+
+// RPCError represents a JSON-RPC 2.0 error object.
+type RPCError struct {
+	Code    int         `json:"code"`
+	Message string      `json:"message"`
+	Data    interface{} `json:"data,omitempty"`
+}
+
+func (e *RPCError) Error() string {
+	return fmt.Sprintf("RPC error %d: %s", e.Code, e.Message)
+}
+
+// Standard JSON-RPC 2.0 error codes.
+const (
+	CodeParseError     = -32700
+	CodeInvalidRequest = -32600
+	CodeMethodNotFound = -32601
+	CodeInvalidParams  = -32602
+	CodeInternalError  = -32603
+)
+
+// --- ACP Method constants ---
+
+const (
+	// Agent baseline methods (client → agent)
+	MethodInitialize    = "initialize"
+	MethodAuthenticate  = "authenticate"
+	MethodSessionNew    = "session/new"
+	MethodSessionPrompt = "session/prompt"
+
+	// Agent optional methods
+	MethodSessionLoad    = "session/load"
+	MethodSessionSetMode = "session/set_mode"
+
+	// Agent notifications (client → agent)
+	MethodSessionCancel = "session/cancel"
+
+	// Client baseline methods (agent → client)
+	MethodRequestPermission = "session/request_permission"
+
+	// Client optional methods (agent → client)
+	MethodFSReadTextFile  = "fs/read_text_file"
+	MethodFSWriteTextFile = "fs/write_text_file"
+	MethodTerminalCreate  = "terminal/create"
+	MethodTerminalOutput  = "terminal/output"
+	MethodTerminalRelease = "terminal/release"
+	MethodTerminalWaitExit = "terminal/wait_for_exit"
+	MethodTerminalKill    = "terminal/kill"
+
+	// Client notifications (agent → client)
+	MethodSessionUpdate = "session/update"
+)
+
+// --- Initialization types ---
+
+// InitializeParams is sent by the client in the initialize request.
+type InitializeParams struct {
+	ProtocolVersion    int                `json:"protocolVersion"`
+	ClientCapabilities ClientCapabilities `json:"clientCapabilities"`
+	ClientInfo         ImplementationInfo `json:"clientInfo"`
+}
+
+// InitializeResult is the agent's response to initialize.
+type InitializeResult struct {
+	ProtocolVersion   int                `json:"protocolVersion"`
+	AgentCapabilities AgentCapabilities  `json:"agentCapabilities"`
+	AgentInfo         ImplementationInfo `json:"agentInfo"`
+	AuthMethods       []interface{}      `json:"authMethods"`
+}
+
+// ClientCapabilities describes what the client can do.
+type ClientCapabilities struct {
+	FS       *FSCapabilities `json:"fs,omitempty"`
+	Terminal bool            `json:"terminal,omitempty"`
+}
+
+// FSCapabilities describes file system capabilities of the client.
+type FSCapabilities struct {
+	ReadTextFile  bool `json:"readTextFile,omitempty"`
+	WriteTextFile bool `json:"writeTextFile,omitempty"`
+}
+
+// AgentCapabilities describes what the agent supports.
+type AgentCapabilities struct {
+	LoadSession       bool               `json:"loadSession"`
+	PromptCapabilities PromptCapabilities `json:"promptCapabilities"`
+	MCPCapabilities   MCPCapabilities    `json:"mcpCapabilities"`
+}
+
+// PromptCapabilities describes what content types the agent accepts.
+type PromptCapabilities struct {
+	Image           bool `json:"image"`
+	Audio           bool `json:"audio"`
+	EmbeddedContext bool `json:"embeddedContext"`
+}
+
+// MCPCapabilities describes MCP support.
+type MCPCapabilities struct {
+	HTTP bool `json:"http"`
+	SSE  bool `json:"sse"`
+}
+
+// ImplementationInfo identifies an agent or client implementation.
+type ImplementationInfo struct {
+	Name    string `json:"name"`
+	Title   string `json:"title"`
+	Version string `json:"version"`
+}
+
+// --- Session types ---
+
+// SessionNewParams is the params for session/new.
+type SessionNewParams struct {
+	WorkingDirectory string            `json:"workingDirectory,omitempty"`
+	ConfigOptions    map[string]string `json:"configOptions,omitempty"`
+}
+
+// SessionNewResult is the result of session/new.
+type SessionNewResult struct {
+	SessionID string `json:"sessionId"`
+}
+
+// SessionPromptParams is the params for session/prompt.
+type SessionPromptParams struct {
+	SessionID string         `json:"sessionId"`
+	Content   []ContentBlock `json:"content"`
+}
+
+// ContentBlock represents a piece of content in a prompt or update.
+type ContentBlock struct {
+	Type string `json:"type"` // "text", "image", "resource", "resourceLink"
+	Text string `json:"text,omitempty"`
+}
+
+// SessionPromptResult is the result of session/prompt (returned when the turn ends).
+type SessionPromptResult struct {
+	StopReason string `json:"stopReason"` // "endTurn", "cancelled", "maxTurns"
+}
+
+// --- Update notification types ---
+
+// SessionUpdateParams is sent as a notification from agent to client during a turn.
+type SessionUpdateParams struct {
+	SessionID string        `json:"sessionId"`
+	Update    SessionUpdate `json:"update"`
+}
+
+// SessionUpdate is the polymorphic update payload.
+type SessionUpdate struct {
+	Kind string `json:"kind"` // "message", "toolCall", "toolCallUpdate", "plan", "availableCommands", "modeChange"
+
+	// For kind="message"
+	MessageChunk *MessageChunk `json:"messageChunk,omitempty"`
+
+	// For kind="toolCall"
+	ToolCall *ToolCallUpdate `json:"toolCall,omitempty"`
+
+	// For kind="toolCallUpdate"
+	ToolCallDelta *ToolCallDelta `json:"toolCallDelta,omitempty"`
+
+	// For kind="plan"
+	Plan *PlanUpdate `json:"plan,omitempty"`
+
+	// For kind="availableCommands"
+	Commands []SlashCommand `json:"commands,omitempty"`
+}
+
+// MessageChunk is a text chunk streamed to the client.
+type MessageChunk struct {
+	Content []ContentBlock `json:"content"`
+}
+
+// ToolCallUpdate notifies the client about a tool invocation.
+type ToolCallUpdate struct {
+	ToolCallID string `json:"toolCallId"`
+	ToolName   string `json:"toolName"`
+	Status     string `json:"status"` // "running", "completed", "error"
+	Input      string `json:"input,omitempty"`
+	Output     string `json:"output,omitempty"`
+}
+
+// ToolCallDelta is a partial update for a long-running tool call.
+type ToolCallDelta struct {
+	ToolCallID string `json:"toolCallId"`
+	Output     string `json:"output,omitempty"`
+}
+
+// PlanUpdate provides plan information to the client.
+type PlanUpdate struct {
+	Title string     `json:"title"`
+	Steps []PlanStep `json:"steps"`
+}
+
+// PlanStep is a single step in an agent plan.
+type PlanStep struct {
+	Title  string `json:"title"`
+	Status string `json:"status"` // "pending", "running", "completed", "error"
+}
+
+// SlashCommand describes an available slash command.
+type SlashCommand struct {
+	Name        string `json:"name"`
+	Description string `json:"description"`
+}
+
+// --- Permission types ---
+
+// RequestPermissionParams is sent from agent to client.
+type RequestPermissionParams struct {
+	SessionID   string `json:"sessionId"`
+	Permissions []Permission `json:"permissions"`
+}
+
+// Permission is a single permission request.
+type Permission struct {
+	Type        string `json:"type"` // "fileWrite", "command"
+	Description string `json:"description"`
+	FilePath    string `json:"filePath,omitempty"`
+	Command     string `json:"command,omitempty"`
+}
+
+// RequestPermissionResult is the client's response.
+type RequestPermissionResult struct {
+	Granted bool `json:"granted"`
+}
+
+// --- File system types ---
+
+// FSReadTextFileParams for fs/read_text_file request.
+type FSReadTextFileParams struct {
+	Path string `json:"path"`
+}
+
+// FSReadTextFileResult for fs/read_text_file response.
+type FSReadTextFileResult struct {
+	Content string `json:"content"`
+}
+
+// FSWriteTextFileParams for fs/write_text_file request.
+type FSWriteTextFileParams struct {
+	Path    string `json:"path"`
+	Content string `json:"content"`
+}
+
+// FSWriteTextFileResult for fs/write_text_file response.
+type FSWriteTextFileResult struct {
+	Success bool `json:"success"`
+}
+
+// --- Terminal types ---
+
+// TerminalCreateParams for terminal/create request.
+type TerminalCreateParams struct {
+	Command string `json:"command"`
+	Cwd     string `json:"cwd,omitempty"`
+}
+
+// TerminalCreateResult for terminal/create response.
+type TerminalCreateResult struct {
+	TerminalID string `json:"terminalId"`
+}
+
+// TerminalWaitExitResult for terminal/wait_for_exit response.
+type TerminalWaitExitResult struct {
+	ExitCode int `json:"exitCode"`
+}
+
+// --- Helpers ---
+
+// NewResponse creates a successful JSON-RPC response.
+func NewResponse(id interface{}, result interface{}) *Response {
+	return &Response{
+		JSONRPC: "2.0",
+		ID:      id,
+		Result:  result,
+	}
+}
+
+// NewErrorResponse creates an error JSON-RPC response.
+func NewErrorResponse(id interface{}, code int, message string) *Response {
+	return &Response{
+		JSONRPC: "2.0",
+		ID:      id,
+		Error: &RPCError{
+			Code:    code,
+			Message: message,
+		},
+	}
+}
+
+// NewNotification creates a JSON-RPC notification.
+func NewNotification(method string, params interface{}) *Notification {
+	return &Notification{
+		JSONRPC: "2.0",
+		Method:  method,
+		Params:  params,
+	}
+}