[proxy] LLM parsers, pricing, and builtin middlewares (OpenAI, Anthropic, Vertex AI, AWS Bedrock)

Request/response parsers and SSE/event-stream metering, the embedded pricing
table, and the builtin middleware set: request parser, router, policy
limit-check/record, cost meter, guardrail, identity inject, response parser.
Includes the path-routed providers — Google Vertex AI (keyfile:: service-account
OAuth minting) and AWS Bedrock (bearer auth, invoke/converse/streaming, optional
/bedrock prefix) — plus the Models allowlist and unmeterable-publisher deny.

proxy/internal/middleware/builtin/builtin.go

@@ -0,0 +1,93 @@
+// Package builtin holds the package-level middleware registry that
+// concrete middleware packages register themselves into via init().
+// Server boot anonymous-imports each middleware sub-package; the
+// resolver attached to the middleware Manager pulls factories out of
+// this registry.
+package builtin
+
+import (
+	"context"
+	"sync"
+
+	log "github.com/sirupsen/logrus"
+	"go.opentelemetry.io/otel/metric"
+	"google.golang.org/grpc"
+
+	"github.com/netbirdio/netbird/proxy/internal/middleware"
+	"github.com/netbirdio/netbird/shared/management/proto"
+)
+
+// MgmtClient is the narrow slice of proto.ProxyServiceClient that
+// builtin middlewares may use during request / response handling.
+// Only the agent-network limit pair (llm_limit_check + llm_limit_record)
+// uses this today; declaring the surface here keeps the dependency
+// explicit at boot time.
+//
+// proto.ProxyServiceClient already satisfies this interface so server
+// boot just forwards its existing client.
+type MgmtClient interface {
+	CheckLLMPolicyLimits(ctx context.Context, in *proto.CheckLLMPolicyLimitsRequest, opts ...grpc.CallOption) (*proto.CheckLLMPolicyLimitsResponse, error)
+	RecordLLMUsage(ctx context.Context, in *proto.RecordLLMUsageRequest, opts ...grpc.CallOption) (*proto.RecordLLMUsageResponse, error)
+}
+
+// defaultRegistry is the package-level registry that concrete builtin
+// middlewares register themselves into via init().
+var defaultRegistry = middleware.NewRegistry()
+
+// FactoryContext is the per-process bag that concrete factories may
+// consult during construction. It carries the proxy-lifetime context,
+// the data directory used for static config files (pricing tables,
+// allowlists), the OTel meter, and the proxy logger.
+//
+// Configure must be called once at boot before any chain build calls
+// Resolve. Calling it twice overwrites the prior value; tests may rely
+// on this to reset state.
+type FactoryContext struct {
+	Context    context.Context
+	DataDir    string
+	Meter      metric.Meter
+	Logger     *log.Logger
+	MgmtClient MgmtClient
+}
+
+var (
+	ctxStore FactoryContext
+	ctxMu    sync.RWMutex
+)
+
+// Configure stores the per-process FactoryContext. Concrete factories
+// reach for it via Context(). mgmt may be nil on tests / standalone
+// builds with no management server; consumers must guard.
+func Configure(ctx context.Context, dataDir string, meter metric.Meter, logger *log.Logger, mgmt MgmtClient) {
+	ctxMu.Lock()
+	defer ctxMu.Unlock()
+	ctxStore = FactoryContext{
+		Context:    ctx,
+		DataDir:    dataDir,
+		Meter:      meter,
+		Logger:     logger,
+		MgmtClient: mgmt,
+	}
+}
+
+// Context returns the stored FactoryContext. Returns a zero value when
+// Configure was never called; consumers must guard against nil
+// Context/Meter/Logger if they care.
+func Context() FactoryContext {
+	ctxMu.RLock()
+	defer ctxMu.RUnlock()
+	return ctxStore
+}
+
+// Register adds a factory to the default registry. Called from init()
+// blocks of concrete middleware packages. Panics on collision so
+// duplicate IDs surface at startup.
+func Register(f middleware.Factory) {
+	defaultRegistry.MustRegister(f)
+}
+
+// DefaultRegistry returns the shared registry. The proxy server
+// constructs the Resolver from it at boot.
+func DefaultRegistry() *middleware.Registry {
+	return defaultRegistry
+}