feat(capability/mcp): MCP 客户端（stdlib JSON-RPC over stdio/SSE）+ Registry 自动注册/Unregister（registry 增 Remove）

internal/capability/mcp/config.go

@@ -0,0 +1,117 @@
+package mcp
+
+import (
+	"fmt"
+	"os"
+	"strconv"
+	"strings"
+
+	"gopkg.in/yaml.v3"
+)
+
+// Load reads MCP server configuration from the process environment. It returns
+// every configured server; callers filter on Enabled.
+func Load() (*Config, error) {
+	return FromEnv(os.Environ())
+}
+
+// FromEnv builds a Config from a KEY=value pair slice such as os.Environ() or a
+// test fixture. Named servers are read from MCP_<NAME>_* for indexes; the
+// unnumbered MCP_* variables describe a single default server. When N is a
+// positive index, one server is read per group and scanning stops at the first
+// group with no NAME/COMMAND/URL set.
+func FromEnv(pairs []string) (*Config, error) {
+	env := make(map[string]string, len(pairs))
+	for _, p := range pairs {
+		k, v, ok := strings.Cut(p, "=")
+		if ok {
+			env[k] = v
+		}
+	}
+	return &Config{Servers: fromEnvMap(env)}, nil
+}
+
+// FromYAML parses a YAML document describing MCP servers, for example:
+//
+//	servers:
+//	  - name: calc
+//	    command: mcp-calc
+//	    args: [--stdio]
+//	    enabled: true
+func FromYAML(data []byte) (*Config, error) {
+	var doc struct {
+		Servers []MCPConfig `yaml:"servers"`
+	}
+	if err := yaml.Unmarshal(data, &doc); err != nil {
+		return nil, fmt.Errorf("mcp config: %w", err)
+	}
+	return &Config{Servers: doc.Servers}, nil
+}
+
+// fromEnvMap builds the server list from a resolved environment map.
+func fromEnvMap(env map[string]string) []MCPConfig {
+	var servers []MCPConfig
+	if cfg, ok := readOne(env, "MCP"); ok {
+		servers = append(servers, cfg)
+	}
+	for i := 0; ; i++ {
+		cfg, ok := readOne(env, "MCP_"+strconv.Itoa(i))
+		if !ok {
+			break
+		}
+		servers = append(servers, cfg)
+	}
+	return servers
+}
+
+// readOne reads a single MCPConfig from env using the given variable prefix
+// (e.g. "MCP" or "MCP_0"). It reports ok=false when no identifying field is set.
+func readOne(env map[string]string, prefix string) (MCPConfig, bool) {
+	p := prefix
+	if p == "" {
+		p = "MCP"
+	}
+	name := env[p+"_NAME"]
+	command := env[p+"_COMMAND"]
+	url := env[p+"_URL"]
+	if name == "" && command == "" && url == "" {
+		return MCPConfig{}, false
+	}
+	return MCPConfig{
+		Name:    name,
+		Command: command,
+		Args:    splitArgs(env[p+"_ARGS"]),
+		URL:     url,
+		Enabled: parseBool(env[p+"_ENABLED"], false),
+	}, true
+}
+
+// splitArgs splits a comma-separated args value, trimming spaces and empty
+// entries.
+func splitArgs(raw string) []string {
+	raw = strings.TrimSpace(raw)
+	if raw == "" {
+		return nil
+	}
+	parts := strings.Split(raw, ",")
+	out := make([]string, 0, len(parts))
+	for _, p := range parts {
+		if t := strings.TrimSpace(p); t != "" {
+			out = append(out, t)
+		}
+	}
+	return out
+}
+
+// parseBool parses a boolean value, defaulting to def on empty or invalid input.
+func parseBool(raw string, def bool) bool {
+	raw = strings.TrimSpace(raw)
+	if raw == "" {
+		return def
+	}
+	b, err := strconv.ParseBool(strings.ToLower(raw))
+	if err != nil {
+		return def
+	}
+	return b
+}