feat: add claudecode with oauth to AI providers

backend/internal/ai/claudecode.go

@@ -0,0 +1,52 @@
+package ai
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"os/exec"
+	"strings"
+)
+
+type claudeCodeProvider struct {
+	model string
+}
+
+func newClaudeCode(model string) *claudeCodeProvider {
+	if model == "" {
+		model = "claude-sonnet-4-6"
+	}
+	return &claudeCodeProvider{model: model}
+}
+
+func (p *claudeCodeProvider) Name() string { return "claudecode" }
+
+func (p *claudeCodeProvider) Summarize(ctx context.Context, prompt string, _ GenOptions) (string, error) {
+	var stdout, stderr bytes.Buffer
+	cmd := exec.CommandContext(ctx, "claude", "-p", prompt, "--model", p.model)
+	cmd.Stdout = &stdout
+	cmd.Stderr = &stderr
+
+	err := cmd.Run()
+	fmt.Printf("[claudecode] stdout len=%d stderr=%q err=%v\n", stdout.Len(), stderr.String(), err)
+
+	if err != nil {
+		msg := strings.TrimSpace(stderr.String())
+		if msg == "" {
+			msg = strings.TrimSpace(stdout.String())
+		}
+		if msg == "" {
+			msg = err.Error()
+		}
+		return "", fmt.Errorf("claude cli: %s", msg)
+	}
+	return strings.TrimSpace(stdout.String()), nil
+}
+
+func (p *claudeCodeProvider) ListModels(_ context.Context) ([]string, error) {
+	return []string{
+		"claude-opus-4-7",
+		"claude-sonnet-4-6",
+		"claude-haiku-4-5-20251001",
+	}, nil
+}