feat(captcha): best-effort rotation/funcaptcha solver

internal/captcha/rotation.go

@@ -0,0 +1,35 @@
+package captcha
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+
+	"github.com/lukaszraczylo/captcha-solver-mcp/internal/llm"
+)
+
+// RotationResult is a best-effort FunCaptcha/rotation answer.
+type RotationResult struct {
+	Choice     int     `json:"choice"`
+	Rotations  int     `json:"rotations"`
+	Confidence float64 `json:"confidence"`
+}
+
+// SolveRotation handles FunCaptcha-style rotation/choice puzzles (best-effort).
+func SolveRotation(ctx context.Context, c llm.Client, img []byte, mediaType, instruction string) (RotationResult, error) {
+	prompt := fmt.Sprintf(
+		"You are solving a rotation/choice puzzle captcha. Instruction: %q. "+
+			"If asked to pick one image, return its 0-based index as choice. "+
+			"If asked to rotate, return the number of clockwise steps as rotations. "+
+			`Respond ONLY with compact JSON: {"choice":<int>,"rotations":<int>,"confidence":<0..1>}.`,
+		instruction)
+	raw, err := c.Vision(ctx, prompt, []llm.Image{{MediaType: mediaType, Data: img}}, llm.Options{})
+	if err != nil {
+		return RotationResult{}, err
+	}
+	var res RotationResult
+	if err := json.Unmarshal([]byte(extractJSON(raw)), &res); err != nil {
+		return RotationResult{}, fmt.Errorf("model did not return parseable rotation answer")
+	}
+	return res, nil
+}

internal/captcha/rotation_test.go

@@ -0,0 +1,19 @@
+package captcha
+
+import (
+	"context"
+	"testing"
+
+	"github.com/lukaszraczylo/captcha-solver-mcp/internal/llm"
+)
+
+func TestSolveRotation(t *testing.T) {
+	f := &llm.Fake{VisionResp: `{"choice":3,"rotations":2,"confidence":0.6}`}
+	res, err := SolveRotation(context.Background(), f, []byte{1}, "image/png", "rotate the animal upright")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if res.Choice != 3 || res.Rotations != 2 {
+		t.Fatalf("got %+v", res)
+	}
+}