Fix zstd streaming decompression, add zstandard dep; bump to 0.5.14

Use stream_reader instead of decompress() for zstd request bodies.
Codex uses streaming zstd (no content size in frame header), which
causes decompress() to fail. stream_reader handles both cases.

Also added zstandard to the [proxy] optional dependencies.

headroom/__init__.py

@@ -153,7 +153,7 @@ from .transforms import (
     TransformPipeline,
 )
 
-__version__ = "0.5.13"
+__version__ = "0.5.14"
 
 __all__ = [
     # Main client

headroom/proxy/server.py

@@ -558,9 +558,13 @@ async def _read_request_json(request: Request) -> dict[str, Any]:
             import zstandard
 
             dctx = zstandard.ZstdDecompressor()
-            raw = dctx.decompress(raw)
+            # Use stream_reader for streaming zstd frames (no content size in header).
+            # Plain decompress() fails when the frame header omits the size, which
+            # is common with clients like OpenAI Codex.
+            reader = dctx.stream_reader(raw)
+            raw = reader.read()
+            reader.close()
         except ImportError:
-            # Auto-detect: if bytes start with zstd magic (0x28 0xb5 0x2f 0xfd), fail clearly
             raise ValueError(
                 "Request body is zstd-compressed but the 'zstandard' package is not installed. "
                 "Install it with: pip install zstandard"

pyproject.toml

@@ -4,7 +4,7 @@ build-backend = "hatchling.build"
 
 [project]
 name = "headroom-ai"
-version = "0.5.13"
+version = "0.5.14"
 description = "The Context Optimization Layer for LLM Applications - Cut costs by 50-90%"
 readme = "README.md"
 license = "Apache-2.0"
@@ -61,6 +61,7 @@ proxy = [
     "openai>=2.14.0",             # OpenAI API format support
     "mcp>=1.0.0",                 # MCP server (headroom_compress, retrieve, stats)
     "magika>=0.6.0",              # ML content detection for ContentRouter
+    "zstandard>=0.20.0",          # Decompress zstd request bodies (Codex, etc.)
 ]
 # AST-based code compression (tree-sitter)
 code = [