feat(docs): oo docs hocr — tesseract hOCR → go-hocr Markdown/YAML

Structured OCR path for agents alongside ocrmypdf searchable PDF.
as-md --hocr selects the same pipeline for OO downloads.

Co-authored-by: Cursor <cursoragent@cursor.com>

internal/docpipe/hocr.go

@@ -0,0 +1,153 @@
+package docpipe
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strings"
+
+	hocr "github.com/eslider/go-hocr"
+)
+
+// HOCRResult is structured OCR output for agents.
+type HOCRResult struct {
+	HOCRPath string
+	Markdown string
+	YAML     string
+	DidOCR   bool
+	Source   string
+}
+
+// ImageToHOCR runs tesseract hOCR into outBase+".hocr" (tesseract adds the extension).
+// outBase must not include ".hocr". dpi 0 uses tesseract default; phone photos often need 200–300.
+func (t Tools) ImageToHOCR(imgPath, outBase, lang string, dpi int) (string, error) {
+	if t.Tesseract == "" {
+		return "", fmt.Errorf("tesseract not found on PATH")
+	}
+	if lang == "" {
+		lang = "eng"
+	}
+	if outBase == "" {
+		return "", fmt.Errorf("hOCR output base path required")
+	}
+	args := []string{imgPath, outBase, "-l", lang}
+	if dpi > 0 {
+		args = append(args, "--dpi", fmt.Sprintf("%d", dpi))
+	}
+	args = append(args, resolveHOCRConfig())
+	cmd := exec.Command(t.Tesseract, args...)
+	var stderr bytes.Buffer
+	cmd.Stderr = &stderr
+	if err := cmd.Run(); err != nil {
+		return "", fmt.Errorf("tesseract hocr: %w (%s)", err, strings.TrimSpace(stderr.String()))
+	}
+	out := outBase + ".hocr"
+	if _, err := os.Stat(out); err != nil {
+		// Some builds write .html
+		alt := outBase + ".html"
+		if _, err2 := os.Stat(alt); err2 == nil {
+			return alt, nil
+		}
+		return "", fmt.Errorf("tesseract hocr: missing output %s (%s)", out, strings.TrimSpace(stderr.String()))
+	}
+	return out, nil
+}
+
+// resolveHOCRConfig returns a tesseract config path that works when TESSDATA_PREFIX
+// points at a custom traineddata dir without relative "hocr" configs.
+func resolveHOCRConfig() string {
+	var candidates []string
+	if p := strings.TrimSpace(os.Getenv("TESSDATA_PREFIX")); p != "" {
+		candidates = append(candidates,
+			filepath.Join(p, "configs", "hocr"),
+			filepath.Join(p, "tessdata", "configs", "hocr"),
+		)
+	}
+	candidates = append(candidates,
+		"/usr/share/tesseract-ocr/5/tessdata/configs/hocr",
+		"/usr/share/tesseract-ocr/4.00/tessdata/configs/hocr",
+		"/usr/share/tessdata/configs/hocr",
+	)
+	for _, c := range candidates {
+		if _, err := os.Stat(c); err == nil {
+			return c
+		}
+	}
+	return "hocr"
+}
+
+// HOCRToMarkdown parses an hOCR file via go-hocr and returns Markdown (+ optional YAML).
+// Words with confidence in (0, minConf) are dropped; minConf 0 keeps all.
+func HOCRToMarkdown(hocrPath string, minConf float32) (md string, yml string, err error) {
+	doc, err := hocr.ReadFile(hocrPath)
+	if err != nil {
+		return "", "", fmt.Errorf("go-hocr: %w", err)
+	}
+	md = doc.ToMarkdown(minConf)
+	yml, err = doc.ToYaml()
+	if err != nil {
+		return md, "", err
+	}
+	return md, yml, nil
+}
+
+// ToHOCRMarkdown OCRs an image (or rasterizes first PDF page) to hOCR → Markdown/YAML.
+func (t Tools) ToHOCRMarkdown(path, workDir, lang string, dpi int, minConf float32) (HOCRResult, error) {
+	res := HOCRResult{Source: path}
+	if workDir == "" {
+		workDir = os.TempDir()
+	}
+	ext := Ext(path)
+	img := path
+	switch ext {
+	case ".jpg", ".jpeg", ".png", ".tif", ".tiff", ".webp", ".gif", ".bmp":
+		// ok
+	case ".pdf":
+		raster, err := t.pdfFirstPagePNG(path, workDir)
+		if err != nil {
+			return res, err
+		}
+		img = raster
+		if dpi == 0 {
+			dpi = 300
+		}
+	default:
+		return res, fmt.Errorf("hOCR path expects image or PDF, got %q", ext)
+	}
+	base := filepath.Join(workDir, trimExt(filepath.Base(path))+".hocr-out")
+	hocrPath, err := t.ImageToHOCR(img, base, lang, dpi)
+	if err != nil {
+		return res, err
+	}
+	res.DidOCR = true
+	res.HOCRPath = hocrPath
+	md, yml, err := HOCRToMarkdown(hocrPath, minConf)
+	if err != nil {
+		return res, err
+	}
+	res.Markdown = wrapMD(filepath.Base(path), strings.TrimSpace(md))
+	res.YAML = yml
+	return res, nil
+}
+
+// pdfFirstPagePNG uses pdftoppm when available.
+func (t Tools) pdfFirstPagePNG(pdfPath, workDir string) (string, error) {
+	pdftoppm, err := exec.LookPath("pdftoppm")
+	if err != nil {
+		return "", fmt.Errorf("pdftoppm not found (needed to rasterize PDF for hOCR)")
+	}
+	outBase := filepath.Join(workDir, trimExt(filepath.Base(pdfPath))+".page")
+	cmd := exec.Command(pdftoppm, "-png", "-f", "1", "-singlefile", "-r", "200", pdfPath, outBase)
+	var stderr bytes.Buffer
+	cmd.Stderr = &stderr
+	if err := cmd.Run(); err != nil {
+		return "", fmt.Errorf("pdftoppm: %w (%s)", err, strings.TrimSpace(stderr.String()))
+	}
+	png := outBase + ".png"
+	if _, err := os.Stat(png); err != nil {
+		return "", fmt.Errorf("pdftoppm: missing %s", png)
+	}
+	return png, nil
+}