feat: 🎉 Vectors na Vectors, the begining

Translate 1536 <-> 768 , 3072 <-> 2048

pkg/server/handler.go

@@ -0,0 +1,74 @@
+package server
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"time"
+
+	"go.uber.org/zap"
+
+	"github.com/Warky-Devs/vecna.git/pkg/adapter"
+	"github.com/Warky-Devs/vecna.git/pkg/config"
+	"github.com/Warky-Devs/vecna.git/pkg/embedclient"
+)
+
+// handler holds shared dependencies for all HTTP handlers.
+type handler struct {
+	cfg     *config.Config
+	clients map[string]embedclient.Client
+	adapter adapter.Adapter
+	logger  *zap.Logger
+}
+
+// resolveClient selects the embed client for the given model name.
+// Returns the client, target name, and first endpoint URL for tracing.
+func (h *handler) resolveClient(model string) (embedclient.Client, string, string) {
+	if c, ok := h.clients[model]; ok {
+		url := firstEndpointURL(h.cfg, model)
+		return c, model, url
+	}
+	name := h.cfg.Forward.Default
+	c, ok := h.clients[name]
+	if !ok {
+		// No configured client — return a nil-safe error client
+		return &errClient{err: fmt.Errorf("no client configured for model %q and no default", model)}, name, ""
+	}
+	return c, name, firstEndpointURL(h.cfg, name)
+}
+
+func firstEndpointURL(cfg *config.Config, targetName string) string {
+	t, ok := cfg.Forward.Targets[targetName]
+	if !ok || len(t.Endpoints) == 0 {
+		return ""
+	}
+	return t.Endpoints[0].URL
+}
+
+// writeJSON encodes v as JSON and writes it with the given status code.
+func writeJSON(w http.ResponseWriter, status int, v interface{}) error {
+	w.Header().Set("Content-Type", "application/json")
+	w.WriteHeader(status)
+	if err := json.NewEncoder(w).Encode(v); err != nil {
+		return fmt.Errorf("writeJSON: %w", err)
+	}
+	return nil
+}
+
+// writeTraceHeaders writes X-Vecna-* timing headers from the RequestTrace.
+func writeTraceHeaders(w http.ResponseWriter, t *RequestTrace) {
+	total := time.Since(t.Start)
+	w.Header().Set("X-Vecna-Forward-Ms", fmt.Sprintf("%d", t.ForwardDuration.Milliseconds()))
+	w.Header().Set("X-Vecna-Translate-Ms", fmt.Sprintf("%d", t.TranslateDuration.Milliseconds()))
+	w.Header().Set("X-Vecna-Total-Ms", fmt.Sprintf("%d", total.Milliseconds()))
+}
+
+// errClient is a Client that always returns a fixed error (used as safe fallback).
+type errClient struct {
+	err error
+}
+
+func (e *errClient) Embed(_ context.Context, _ embedclient.Request) (embedclient.Response, error) {
+	return embedclient.Response{}, e.err
+}