Suya OCR API — vLLM-backed, OpenAI-compatible OCR service

FastAPI service wrapping the Surya-OCR-2 model (datalab-to) served through vLLM:
legacy /v1/api/ai/* endpoints, an OpenAI-compatible /v1/chat/completions endpoint,
a coalescing request batcher, a local OCR CLI, Docker packaging, multilingual
example outputs, and quantization/concurrency benchmarks.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

surya/layout/label.py

@@ -0,0 +1,44 @@
+"""Surya2 layout labels emitted by the model + canonicalization to surya's
+public label vocabulary."""
+
+# Canonical text-bearing labels — used by blank-region filters to decide
+# which blocks may be dropped when their underlying image region is empty.
+# Excludes Picture/Figure/Diagram/Table/Form/Equation/etc., which can legitimately
+# contain whitespace or solid fills.
+TEXT_LABELS = frozenset(
+    {
+        "Text",
+        "SectionHeader",
+        "PageHeader",
+        "PageFooter",
+        "Caption",
+        "Footnote",
+        "Code",
+        "Bibliography",
+    }
+)
+
+
+# Canonicalize raw model labels to public surya label names. Marker and other
+# downstream consumers depend on these names.
+LAYOUT_PRED_RELABEL = {
+    "Caption": "Caption",
+    "Footnote": "Footnote",
+    "Equation-Block": "Equation",
+    "List-Group": "ListGroup",
+    "Page-Header": "PageHeader",
+    "Page-Footer": "PageFooter",
+    "Image": "Picture",
+    "Section-Header": "SectionHeader",
+    "Table": "Table",
+    "Text": "Text",
+    "Complex-Block": "Figure",
+    "Code-Block": "Code",
+    "Form": "Form",
+    "Table-Of-Contents": "TableOfContents",
+    "Figure": "Figure",
+    "Chemical-Block": "ChemicalBlock",
+    "Diagram": "Diagram",
+    "Bibliography": "Bibliography",
+    "Blank-Page": "BlankPage",
+}