chore: establish local platform baseline

internal/embeddingprovider/provider.go

@@ -0,0 +1,127 @@
+package embeddingprovider
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"math"
+	"net/http"
+	"net/url"
+	"strings"
+	"time"
+
+	"data-terminal-cloud/internal/developmentembedding"
+	"data-terminal-cloud/internal/outbox"
+)
+
+const Dimensions = developmentembedding.Dimensions
+
+type Result struct {
+	Vector      []float64
+	ProviderRef string
+}
+
+type Provider interface {
+	Embed(context.Context, string) (Result, error)
+}
+
+type Local struct{}
+
+func (Local) Embed(_ context.Context, content string) (Result, error) {
+	if strings.TrimSpace(content) == "" {
+		return Result{}, errors.New("embedding content is required")
+	}
+	return Result{Vector: developmentembedding.Vector(content), ProviderRef: "local-deterministic-hash-v1"}, nil
+}
+
+type Ark struct {
+	endpoint string
+	apiKey   string
+	model    string
+	client   *http.Client
+}
+
+func NewArk(baseURL, apiKey, model string, timeout time.Duration) (*Ark, error) {
+	baseURL = strings.TrimRight(strings.TrimSpace(baseURL), "/")
+	apiKey = strings.TrimSpace(apiKey)
+	model = strings.TrimSpace(model)
+	parsed, err := url.Parse(baseURL)
+	if err != nil || parsed.Host == "" || (parsed.Scheme != "http" && parsed.Scheme != "https") {
+		return nil, errors.New("Ark base URL must be an absolute HTTP(S) URL")
+	}
+	if apiKey == "" || model == "" || timeout <= 0 {
+		return nil, errors.New("Ark API key, embedding model and positive timeout are required")
+	}
+	return &Ark{endpoint: baseURL + "/embeddings", apiKey: apiKey, model: model, client: &http.Client{Timeout: timeout}}, nil
+}
+
+func (a *Ark) Embed(ctx context.Context, content string) (Result, error) {
+	content = strings.TrimSpace(content)
+	if content == "" {
+		return Result{}, errors.New("embedding content is required")
+	}
+	body, err := json.Marshal(map[string]any{
+		"model": a.model, "input": content, "encoding_format": "float", "dimensions": Dimensions,
+	})
+	if err != nil {
+		return Result{}, err
+	}
+	req, err := http.NewRequestWithContext(ctx, http.MethodPost, a.endpoint, bytes.NewReader(body))
+	if err != nil {
+		return Result{}, fmt.Errorf("build Ark embedding request: %w", err)
+	}
+	req.Header.Set("Authorization", "Bearer "+a.apiKey)
+	req.Header.Set("Content-Type", "application/json")
+	req.Header.Set("User-Agent", "voice-platform-memory-embedding/1.0")
+	resp, err := a.client.Do(req)
+	if err != nil {
+		return Result{}, outbox.Retryable(fmt.Errorf("call Ark embedding model: %w", err))
+	}
+	defer resp.Body.Close()
+	responseBody, readErr := io.ReadAll(io.LimitReader(resp.Body, 4<<20))
+	if readErr != nil {
+		return Result{}, outbox.Retryable(fmt.Errorf("read Ark embedding response: %w", readErr))
+	}
+	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
+		requestErr := fmt.Errorf("Ark embedding model returned HTTP %d", resp.StatusCode)
+		if resp.StatusCode == http.StatusRequestTimeout || resp.StatusCode == http.StatusTooEarly || resp.StatusCode == http.StatusTooManyRequests || resp.StatusCode >= 500 {
+			return Result{}, outbox.Retryable(requestErr)
+		}
+		return Result{}, requestErr
+	}
+	var response struct {
+		Data []struct {
+			Index     int       `json:"index"`
+			Embedding []float64 `json:"embedding"`
+		} `json:"data"`
+	}
+	if err = json.Unmarshal(responseBody, &response); err != nil || len(response.Data) != 1 || response.Data[0].Index != 0 {
+		return Result{}, outbox.Retryable(errors.New("Ark embedding response has no usable vector"))
+	}
+	if err = Validate(response.Data[0].Embedding); err != nil {
+		return Result{}, outbox.Retryable(err)
+	}
+	return Result{Vector: response.Data[0].Embedding, ProviderRef: "ark:" + a.model}, nil
+}
+
+func Validate(vector []float64) error {
+	if len(vector) != Dimensions {
+		return fmt.Errorf("embedding dimensions=%d want=%d", len(vector), Dimensions)
+	}
+	for _, value := range vector {
+		if math.IsNaN(value) || math.IsInf(value, 0) {
+			return errors.New("embedding contains a non-finite value")
+		}
+	}
+	return nil
+}
+
+func Literal(vector []float64) (string, error) {
+	if err := Validate(vector); err != nil {
+		return "", err
+	}
+	return developmentembedding.Literal(vector), nil
+}