From eaf96d532b83ece297fc31f4c934e2b97504894f Mon Sep 17 00:00:00 2001
From: Samuel Williams <samuel.williams@shopify.com>
Date: Thu, 13 Aug 2026 20:25:44 +1200
Subject: [PATCH 1/4] Achieve complete test coverage

Assisted-By: devx/48bd9802-2aca-41ba-856d-0b5bd523f9cf
---
 test/protocol/grpc/body/readable.rb   | 63 +++++++++++++++++++++++++++
 test/protocol/grpc/body/writable.rb   | 30 +++++++++++++
 test/protocol/grpc/error.rb           | 39 +++++++++++++++++
 test/protocol/grpc/header/encoding.rb | 39 +++++++++++++++++
 test/protocol/grpc/header/message.rb  |  7 +++
 test/protocol/grpc/header/status.rb   |  7 +++
 test/protocol/grpc/header/timeout.rb  | 20 +++++++++
 test/protocol/grpc/metadata.rb        | 52 ++++++++++++++++++++++
 test/protocol/grpc/methods.rb         | 10 +++++
 test/protocol/grpc/middleware.rb      |  9 ++++
 10 files changed, 276 insertions(+)
 create mode 100644 test/protocol/grpc/header/encoding.rb

diff --git a/test/protocol/grpc/body/readable.rb b/test/protocol/grpc/body/readable.rb
index d3379c5..f53e0ed 100644
--- a/test/protocol/grpc/body/readable.rb
+++ b/test/protocol/grpc/body/readable.rb
@@ -7,6 +7,8 @@
 require "protocol/http/body/buffered"
 require_relative "../../../../fixtures/protocol/grpc/test_message"
 
+require "zlib"
+
 describe Protocol::GRPC::Body::Readable do
 	let(:message_class) {Protocol::GRPC::Fixtures::TestMessage}
 	let(:source_body) {Protocol::HTTP::Body::Buffered.new}
@@ -19,6 +21,28 @@ def write_message(message, compressed: false)
 		source_body.write(prefix + data)
 	end
 	
+	def write_data(data, compressed: false)
+		compression_flag = compressed ? 1 : 0
+		prefix = [compression_flag].pack("C") + [data.bytesize].pack("N")
+		source_body.write(prefix + data)
+	end
+	
+	with ".wrap" do
+		it "wraps a message body" do
+			message = Struct.new(:body).new(source_body)
+			wrapped_body = subject.wrap(message, message_class: message_class)
+			
+			expect(wrapped_body).to be_a(subject)
+			expect(message.body).to be_equal(wrapped_body)
+		end
+		
+		it "returns nil when the message has no body" do
+			message = Struct.new(:body).new(nil)
+			
+			expect(subject.wrap(message)).to be_nil
+		end
+	end
+	
 	it "has body attribute" do
 		expect(body.body).to be == source_body
 	end
@@ -70,6 +94,20 @@ def write_message(message, compressed: false)
 			read_message = body.read
 			expect(read_message).to be == message
 		end
+		
+		it "returns nil when the underlying body ends during a message" do
+			source_body = Object.new
+			def source_body.empty?
+				false
+			end
+			
+			def source_body.read
+				nil
+			end
+			
+			body = subject.new(source_body)
+			expect(body.read).to be_nil
+		end
 	end
 	
 	with "#each" do
@@ -127,6 +165,31 @@ def write_message(message, compressed: false)
 			read_message = body.read
 			expect(read_message).to be == message
 		end
+		
+		it "decompresses deflate messages" do
+			body = subject.new(source_body, message_class: message_class, encoding: "deflate")
+			message = message_class.new(value: "Hello")
+			write_data(Zlib::Deflate.deflate(message.to_proto), compressed: true)
+			
+			expect(body.read).to be == message
+		end
+		
+		it "leaves messages unchanged for unknown encodings" do
+			body = subject.new(source_body, message_class: message_class, encoding: "custom")
+			message = message_class.new(value: "Hello")
+			write_message(message, compressed: true)
+			
+			expect(body.read).to be == message
+		end
+		
+		it "raises a gRPC error for invalid compressed data" do
+			body = subject.new(source_body, encoding: "gzip")
+			write_data("invalid", compressed: true)
+			
+			expect{body.read}.to raise_exception(Protocol::GRPC::Error) do |error|
+				expect(error.status_code).to be == Protocol::GRPC::Status::INTERNAL
+			end
+		end
 	end
 	
 	with "empty stream" do
diff --git a/test/protocol/grpc/body/writable.rb b/test/protocol/grpc/body/writable.rb
index 425424b..247a828 100644
--- a/test/protocol/grpc/body/writable.rb
+++ b/test/protocol/grpc/body/writable.rb
@@ -212,6 +212,36 @@ def message.encode
 			compressed = prefix[0].unpack1("C")
 			expect(compressed).to be == 0
 		end
+		
+		it "compresses messages using deflate" do
+			body = subject.new(encoding: "deflate")
+			message = message_class.new(value: "Hello")
+			body.write(message)
+			body.close_write
+			
+			framed_data = body.join
+			expect(framed_data.getbyte(0)).to be == 1
+			expect(Zlib::Inflate.inflate(framed_data.byteslice(5..))).to be == message.to_proto
+		end
+		
+		it "leaves messages unchanged for unknown encodings" do
+			body = subject.new(encoding: "custom")
+			message = message_class.new(value: "Hello")
+			body.write(message)
+			body.close_write
+			
+			framed_data = body.join
+			expect(framed_data.getbyte(0)).to be == 1
+			expect(framed_data.byteslice(5..)).to be == message.to_proto
+		end
+		
+		it "raises a gRPC error when compression fails" do
+			body = subject.new(encoding: "deflate", level: 100)
+			
+			expect{body.write("Hello")}.to raise_exception(Protocol::GRPC::Error) do |error|
+				expect(error.status_code).to be == Protocol::GRPC::Status::INTERNAL
+			end
+		end
 	end
 	
 	with "message framing" do
diff --git a/test/protocol/grpc/error.rb b/test/protocol/grpc/error.rb
index 16ed827..e3d03ab 100644
--- a/test/protocol/grpc/error.rb
+++ b/test/protocol/grpc/error.rb
@@ -86,4 +86,43 @@
 			expect(error.status_code).to be == Protocol::GRPC::Status::UNAUTHENTICATED
 		end
 	end
+	
+	with ".error_class_for_status" do
+		it "maps status codes to specialized error classes" do
+			expected_classes = {
+				Protocol::GRPC::Status::CANCELLED => Protocol::GRPC::Cancelled,
+				Protocol::GRPC::Status::INVALID_ARGUMENT => Protocol::GRPC::InvalidArgument,
+				Protocol::GRPC::Status::DEADLINE_EXCEEDED => Protocol::GRPC::DeadlineExceeded,
+				Protocol::GRPC::Status::NOT_FOUND => Protocol::GRPC::NotFound,
+				Protocol::GRPC::Status::INTERNAL => Protocol::GRPC::Internal,
+				Protocol::GRPC::Status::UNAVAILABLE => Protocol::GRPC::Unavailable,
+				Protocol::GRPC::Status::UNAUTHENTICATED => Protocol::GRPC::Unauthenticated,
+			}
+			
+			expected_classes.each do |status_code, error_class|
+				expect(subject.error_class_for_status(status_code)).to be == error_class
+			end
+		end
+		
+		it "uses the base error class for other status codes" do
+			expect(subject.error_class_for_status(Protocol::GRPC::Status::UNKNOWN)).to be == subject
+		end
+	end
+	
+	with ".for" do
+		it "creates a specialized error" do
+			error = subject.for(Protocol::GRPC::Status::NOT_FOUND, "Missing", metadata: {"key" => "value"})
+			
+			expect(error).to be_a(Protocol::GRPC::NotFound)
+			expect(error.message).to be == "Missing"
+			expect(error.metadata).to be == {"key" => "value"}
+		end
+		
+		it "creates a base error for an unmapped status" do
+			error = subject.for(Protocol::GRPC::Status::UNKNOWN)
+			
+			expect(error.class).to be == subject
+			expect(error.status_code).to be == Protocol::GRPC::Status::UNKNOWN
+		end
+	end
 end
diff --git a/test/protocol/grpc/header/encoding.rb b/test/protocol/grpc/header/encoding.rb
new file mode 100644
index 0000000..6dbebc0
--- /dev/null
+++ b/test/protocol/grpc/header/encoding.rb
@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+# Released under the MIT License.
+# Copyright, 2026, by Samuel Williams.
+
+require "protocol/grpc/header/encoding"
+
+describe Protocol::GRPC::Header::Encoding do
+	with ".coerce" do
+		it "coerces values to strings" do
+			expect(subject.coerce(:gzip)).to be == "gzip"
+		end
+	end
+	
+	with "#identity?" do
+		it "recognizes identity and empty encodings" do
+			expect(subject.new("identity")).to be(:identity?)
+			expect(subject.new("")).to be(:identity?)
+		end
+		
+		it "rejects compressed encodings" do
+			expect(subject.new("gzip")).not.to be(:identity?)
+		end
+	end
+	
+	with "#<<" do
+		it "replaces the encoding and returns itself" do
+			encoding = subject.new("identity")
+			expect(encoding << :gzip).to be_equal(encoding)
+			expect(encoding).to be == "gzip"
+		end
+	end
+	
+	with ".trailer?" do
+		it "returns false" do
+			expect(subject.trailer?).to be == false
+		end
+	end
+end
diff --git a/test/protocol/grpc/header/message.rb b/test/protocol/grpc/header/message.rb
index f65d452..1d9c2b9 100644
--- a/test/protocol/grpc/header/message.rb
+++ b/test/protocol/grpc/header/message.rb
@@ -6,6 +6,13 @@
 require "protocol/grpc/header/message"
 
 describe Protocol::GRPC::Header::Message do
+	with ".coerce" do
+		it "returns an existing message" do
+			message = subject.new("Error%20message")
+			expect(subject.coerce(message)).to be_equal(message)
+		end
+	end
+	
 	with ".parse" do
 		it "parses string value" do
 			message = subject.parse("Error%20occurred")
diff --git a/test/protocol/grpc/header/status.rb b/test/protocol/grpc/header/status.rb
index f2271e6..5d8feec 100644
--- a/test/protocol/grpc/header/status.rb
+++ b/test/protocol/grpc/header/status.rb
@@ -6,6 +6,13 @@
 require "protocol/grpc/header/status"
 
 describe Protocol::GRPC::Header::Status do
+	with ".coerce" do
+		it "returns an existing status" do
+			status = subject.new(5)
+			expect(subject.coerce(status)).to be_equal(status)
+		end
+	end
+	
 	with ".parse" do
 		it "parses string value to integer" do
 			status = subject.parse("0")
diff --git a/test/protocol/grpc/header/timeout.rb b/test/protocol/grpc/header/timeout.rb
index 9afbfe6..f23b13c 100644
--- a/test/protocol/grpc/header/timeout.rb
+++ b/test/protocol/grpc/header/timeout.rb
@@ -6,6 +6,12 @@
 require "protocol/grpc/header/timeout"
 
 describe Protocol::GRPC::Header::Timeout do
+	with ".coerce" do
+		it "coerces a string timeout" do
+			expect(subject.coerce("5S")).to be == "5S"
+		end
+	end
+	
 	with ".format" do
 		it "formats seconds" do
 			expect(subject.format(5)).to be == "5S"
@@ -72,4 +78,18 @@
 			end
 		end
 	end
+	
+	with "#<<" do
+		it "replaces the timeout and returns itself" do
+			timeout = subject.new("5S")
+			expect(timeout << "10S").to be_equal(timeout)
+			expect(timeout).to be == "10S"
+		end
+	end
+	
+	with ".trailer?" do
+		it "returns false" do
+			expect(subject.trailer?).to be == false
+		end
+	end
 end
diff --git a/test/protocol/grpc/metadata.rb b/test/protocol/grpc/metadata.rb
index 7658e59..8aa7a7e 100644
--- a/test/protocol/grpc/metadata.rb
+++ b/test/protocol/grpc/metadata.rb
@@ -8,6 +8,20 @@
 require "protocol/http"
 
 describe Protocol::GRPC::Metadata do
+	def raw_headers(values)
+		Class.new do
+			attr_accessor :policy
+			
+			define_method(:initialize) do |values|
+				@values = values
+			end
+			
+			define_method(:[]) do |key|
+				@values[key]
+			end
+		end.new(values)
+	end
+	
 	with ".extract_status" do
 		it "extracts status from headers" do
 			headers = Protocol::HTTP::Headers.new([%w[grpc-status 0]], nil, policy: Protocol::GRPC::HEADER_POLICY)
@@ -23,6 +37,27 @@
 			headers = Protocol::HTTP::Headers.new([%w[grpc-status 14]], nil, policy: Protocol::GRPC::HEADER_POLICY)
 			expect(subject.extract_status(headers)).to be == Protocol::GRPC::Status::UNAVAILABLE
 		end
+		
+		it "extracts a raw scalar status" do
+			headers = raw_headers("grpc-status" => "14")
+			expect(subject.extract_status(headers)).to be == Protocol::GRPC::Status::UNAVAILABLE
+		end
+		
+		it "extracts a raw array status" do
+			headers = raw_headers("grpc-status" => [nil, "13"])
+			expect(subject.extract_status(headers)).to be == Protocol::GRPC::Status::INTERNAL
+		end
+		
+		it "extracts a deeply nested raw array status" do
+			status = Class.new(Array) do
+				def flatten
+					[[["5"]]]
+				end
+			end.new
+			headers = raw_headers("grpc-status" => status)
+			
+			expect(subject.extract_status(headers)).to be == Protocol::GRPC::Status::NOT_FOUND
+		end
 	end
 	
 	with ".extract_message" do
@@ -35,6 +70,16 @@
 			headers = Protocol::HTTP::Headers.new
 			expect(subject.extract_message(headers)).to be_nil
 		end
+		
+		it "extracts a raw scalar message" do
+			headers = raw_headers("grpc-message" => "Error%20message")
+			expect(subject.extract_message(headers)).to be == "Error message"
+		end
+		
+		it "extracts a raw array message" do
+			headers = raw_headers("grpc-message" => ["Error%20message"])
+			expect(subject.extract_message(headers)).to be == "Error message"
+		end
 	end
 	
 	with ".assign_status!" do
@@ -86,6 +131,13 @@
 			message_value = message_value.first if message_value.is_a?(Array)
 			expect(message_value.to_s).to be == "Test"
 		end
+		
+		it "uses the error message when no message is given" do
+			headers = Protocol::HTTP::Headers.new([], nil, policy: Protocol::GRPC::HEADER_POLICY)
+			subject.assign_status!(headers, status: Protocol::GRPC::Status::INTERNAL, error: StandardError.new("Failure"))
+			
+			expect(subject.extract_message(headers)).to be == "Failure"
+		end
 	end
 	
 end
diff --git a/test/protocol/grpc/methods.rb b/test/protocol/grpc/methods.rb
index 11dcb30..344e00b 100644
--- a/test/protocol/grpc/methods.rb
+++ b/test/protocol/grpc/methods.rb
@@ -100,6 +100,16 @@
 			
 			expect(metadata["custom-bin"]).to be == ["\x01\x02\x03\x04".dup.force_encoding(Encoding::BINARY)]
 		end
+		
+		it "decodes scalar binary metadata" do
+			headers = Object.new
+			def headers.to_h
+				{"custom-bin" => "AQIDBA=="}
+			end
+			
+			metadata = subject.extract_metadata(headers)
+			expect(metadata["custom-bin"]).to be == "\x01\x02\x03\x04".dup.force_encoding(Encoding::BINARY)
+		end
 	end
 	
 	with ".format_timeout" do
diff --git a/test/protocol/grpc/middleware.rb b/test/protocol/grpc/middleware.rb
index ee29ba1..97d22dd 100644
--- a/test/protocol/grpc/middleware.rb
+++ b/test/protocol/grpc/middleware.rb
@@ -13,6 +13,15 @@
 	let(:services) {{}}
 	let(:middleware) {TestMiddleware.new(services: services)}
 	
+	with "abstract middleware" do
+		it "raises a not implemented error" do
+			headers = Protocol::HTTP::Headers.new([["content-type", "application/grpc"]])
+			request = Protocol::HTTP::Request.new("https", "localhost", "POST", "/service/Method", nil, headers, nil)
+			
+			expect{subject.new.call(request)}.to raise_exception(NotImplementedError, message: be == "Subclasses must implement #dispatch")
+		end
+	end
+	
 	with "#call" do
 		let(:headers) do
 			Protocol::HTTP::Headers.new([

From 9af1dc112a734882b35d148f8fa7047a4f342ff1 Mon Sep 17 00:00:00 2001
From: Samuel Williams <samuel.williams@shopify.com>
Date: Thu, 13 Aug 2026 20:42:10 +1200
Subject: [PATCH 2/4] Reject unsupported compression encodings

Assisted-By: devx/48bd9802-2aca-41ba-856d-0b5bd523f9cf
---
 lib/protocol/grpc/body/readable.rb  |  7 ++++++-
 lib/protocol/grpc/body/writable.rb  |  5 ++++-
 test/protocol/grpc/body/readable.rb |  7 +++++--
 test/protocol/grpc/body/writable.rb | 11 +++++------
 4 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/lib/protocol/grpc/body/readable.rb b/lib/protocol/grpc/body/readable.rb
index 10ce169..0dcd3fd 100644
--- a/lib/protocol/grpc/body/readable.rb
+++ b/lib/protocol/grpc/body/readable.rb
@@ -7,6 +7,9 @@
 require "protocol/http/body/wrapper"
 require "zlib"
 
+require_relative "../error"
+require_relative "../status"
+
 module Protocol
 	module GRPC
 		# @namespace
@@ -122,8 +125,10 @@ def decompress(data)
 						inflater.close
 						result
 					else
-						data
+						raise Error.new(Status::UNIMPLEMENTED, "Unsupported compression encoding: #{@encoding.inspect}")
 					end
+				rescue Error
+					raise
 				rescue StandardError => error
 					raise Error.new(Status::INTERNAL, "Failed to decompress message: #{error.message}")
 				end
diff --git a/lib/protocol/grpc/body/writable.rb b/lib/protocol/grpc/body/writable.rb
index 503137e..2a02d47 100644
--- a/lib/protocol/grpc/body/writable.rb
+++ b/lib/protocol/grpc/body/writable.rb
@@ -8,6 +8,9 @@
 require "zlib"
 require "stringio"
 
+require_relative "../error"
+require_relative "../status"
+
 module Protocol
 	module GRPC
 		# @namespace
@@ -97,7 +100,7 @@ def compress(data)
 						# This matches HTTP's "deflate" content-encoding
 						Zlib::Deflate.deflate(data, @level)
 					else
-						data # No compression or identity
+						raise ArgumentError, "Unsupported compression encoding: #{@encoding.inspect}"
 					end
 				rescue StandardError => error
 					raise Error.new(Status::INTERNAL, "Failed to compress message: #{error.message}")
diff --git a/test/protocol/grpc/body/readable.rb b/test/protocol/grpc/body/readable.rb
index f53e0ed..c293c49 100644
--- a/test/protocol/grpc/body/readable.rb
+++ b/test/protocol/grpc/body/readable.rb
@@ -174,12 +174,15 @@ def source_body.read
 			expect(body.read).to be == message
 		end
 		
-		it "leaves messages unchanged for unknown encodings" do
+		it "rejects unsupported encodings" do
 			body = subject.new(source_body, message_class: message_class, encoding: "custom")
 			message = message_class.new(value: "Hello")
 			write_message(message, compressed: true)
 			
-			expect(body.read).to be == message
+			expect{body.read}.to raise_exception(Protocol::GRPC::Error) do |error|
+				expect(error.status_code).to be == Protocol::GRPC::Status::UNIMPLEMENTED
+				expect(error.message).to be =~ /Unsupported compression encoding: "custom"/
+			end
 		end
 		
 		it "raises a gRPC error for invalid compressed data" do
diff --git a/test/protocol/grpc/body/writable.rb b/test/protocol/grpc/body/writable.rb
index 247a828..7be9ad2 100644
--- a/test/protocol/grpc/body/writable.rb
+++ b/test/protocol/grpc/body/writable.rb
@@ -224,15 +224,14 @@ def message.encode
 			expect(Zlib::Inflate.inflate(framed_data.byteslice(5..))).to be == message.to_proto
 		end
 		
-		it "leaves messages unchanged for unknown encodings" do
+		it "rejects unsupported encodings" do
 			body = subject.new(encoding: "custom")
 			message = message_class.new(value: "Hello")
-			body.write(message)
-			body.close_write
 			
-			framed_data = body.join
-			expect(framed_data.getbyte(0)).to be == 1
-			expect(framed_data.byteslice(5..)).to be == message.to_proto
+			expect{body.write(message)}.to raise_exception(Protocol::GRPC::Error) do |error|
+				expect(error.status_code).to be == Protocol::GRPC::Status::INTERNAL
+				expect(error.message).to be =~ /Unsupported compression encoding: "custom"/
+			end
 		end
 		
 		it "raises a gRPC error when compression fails" do

From f68180c0d941533e27ba7d5a8b162806abed0560 Mon Sep 17 00:00:00 2001
From: Samuel Williams <samuel.williams@shopify.com>
Date: Thu, 13 Aug 2026 20:42:40 +1200
Subject: [PATCH 3/4] Reject truncated gRPC frames

Assisted-By: devx/48bd9802-2aca-41ba-856d-0b5bd523f9cf
---
 lib/protocol/grpc/body/readable.rb  | 22 +++++++++------
 test/protocol/grpc/body/readable.rb | 44 ++++++++++++++++++++++++++++-
 2 files changed, 57 insertions(+), 9 deletions(-)

diff --git a/lib/protocol/grpc/body/readable.rb b/lib/protocol/grpc/body/readable.rb
index 0dcd3fd..6cf297f 100644
--- a/lib/protocol/grpc/body/readable.rb
+++ b/lib/protocol/grpc/body/readable.rb
@@ -50,8 +50,6 @@ def initialize(body, message_class: nil, encoding: nil)
 				# Overrides Wrapper#read to transform raw HTTP body chunks into decoded gRPC messages.
 				# @returns [Object | String | Nil] Decoded message, raw binary, or `Nil` if stream ended
 				def read
-					return nil if @body.nil? || @body.empty?
-					
 					# Read 5-byte prefix: 1 byte compression flag + 4 bytes length
 					prefix = read_exactly(5)
 					return nil unless prefix
@@ -61,7 +59,9 @@ def read
 					
 					# Read the message body:
 					data = read_exactly(length)
-					return nil unless data
+					unless data
+						raise Error.new(Status::INTERNAL, "Truncated gRPC frame: expected #{length} bytes, received 0")
+					end
 					
 					# Decompress if needed:
 					data = decompress(data) if compressed
@@ -79,19 +79,25 @@ def read
 			private
 				
 				# Read exactly n bytes from the underlying body.
-				# @parameter n [Integer] The number of bytes to read
-				# @returns [String | Nil] The data read, or `Nil` if the stream ended
+				# @parameter n [Integer] The number of bytes to read.
+				# @returns [String | Nil] The data read, or `Nil` if the stream ended before reading any bytes.
+				# @raises [Error] If the stream ends after reading a partial value.
 				def read_exactly(n)
 					# Fill buffer until we have enough data:
 					while @buffer.bytesize < n
-						return nil if @body.nil? || @body.empty?
+						if @body.nil? || @body.empty?
+							return nil if @buffer.empty?
+							
+							raise Error.new(Status::INTERNAL, "Truncated gRPC frame: expected #{n} bytes, received #{@buffer.bytesize}")
+						end
 						
 						# Read chunk from underlying body:
 						chunk = @body.read
 						
 						if chunk.nil?
-							# End of stream:
-							return nil
+							return nil if @buffer.empty?
+							
+							raise Error.new(Status::INTERNAL, "Truncated gRPC frame: expected #{n} bytes, received #{@buffer.bytesize}")
 						end
 						
 						# Append to buffer:
diff --git a/test/protocol/grpc/body/readable.rb b/test/protocol/grpc/body/readable.rb
index c293c49..1685d77 100644
--- a/test/protocol/grpc/body/readable.rb
+++ b/test/protocol/grpc/body/readable.rb
@@ -95,7 +95,7 @@ def write_data(data, compressed: false)
 			expect(read_message).to be == message
 		end
 		
-		it "returns nil when the underlying body ends during a message" do
+		it "returns nil when the underlying body reports clean EOF" do
 			source_body = Object.new
 			def source_body.empty?
 				false
@@ -108,6 +108,48 @@ def source_body.read
 			body = subject.new(source_body)
 			expect(body.read).to be_nil
 		end
+		
+		it "raises an error for a truncated prefix" do
+			source_body.write("\x00\x00".b)
+			
+			expect{body.read}.to raise_exception(Protocol::GRPC::Error) do |error|
+				expect(error.status_code).to be == Protocol::GRPC::Status::INTERNAL
+				expect(error.message).to be =~ /expected 5 bytes, received 2/
+			end
+		end
+		
+		it "raises an error when a partial prefix is followed by nil" do
+			chunks = ["\x00".b, nil]
+			source_body = Object.new
+			source_body.define_singleton_method(:empty?){false}
+			source_body.define_singleton_method(:read){chunks.shift}
+			body = subject.new(source_body)
+			
+			expect{body.read}.to raise_exception(Protocol::GRPC::Error) do |error|
+				expect(error.status_code).to be == Protocol::GRPC::Status::INTERNAL
+				expect(error.message).to be =~ /expected 5 bytes, received 1/
+			end
+		end
+		
+		it "raises an error for a truncated payload" do
+			write_data("ab")
+			framed_data = source_body.read
+			source_body.write(framed_data.byteslice(0...5) + "a")
+			
+			expect{body.read}.to raise_exception(Protocol::GRPC::Error) do |error|
+				expect(error.status_code).to be == Protocol::GRPC::Status::INTERNAL
+				expect(error.message).to be =~ /expected 2 bytes, received 1/
+			end
+		end
+		
+		it "raises an error when the payload is missing" do
+			source_body.write("\x00".b + [2].pack("N"))
+			
+			expect{body.read}.to raise_exception(Protocol::GRPC::Error) do |error|
+				expect(error.status_code).to be == Protocol::GRPC::Status::INTERNAL
+				expect(error.message).to be =~ /expected 2 bytes, received 0/
+			end
+		end
 	end
 	
 	with "#each" do

From f574d168287c7a5b3549aa4e090cca2cbb0bc038 Mon Sep 17 00:00:00 2001
From: Samuel Williams <samuel.williams@shopify.com>
Date: Thu, 13 Aug 2026 20:59:51 +1200
Subject: [PATCH 4/4] Rely on gRPC header policy

Assisted-By: devx/48bd9802-2aca-41ba-856d-0b5bd523f9cf
---
 lib/protocol/grpc/metadata.rb  | 33 ++---------------------
 test/protocol/grpc/metadata.rb | 49 ++--------------------------------
 2 files changed, 4 insertions(+), 78 deletions(-)

diff --git a/lib/protocol/grpc/metadata.rb b/lib/protocol/grpc/metadata.rb
index bd023fc..44552f7 100644
--- a/lib/protocol/grpc/metadata.rb
+++ b/lib/protocol/grpc/metadata.rb
@@ -3,7 +3,6 @@
 # Released under the MIT License.
 # Copyright, 2025-2026, by Samuel Williams.
 
-require "uri"
 require_relative "header"
 require_relative "status"
 
@@ -12,7 +11,6 @@ module GRPC
 		# @namespace
 		module Metadata
 			# Extract gRPC status from headers.
-			# Convenience method that handles both Header::Status instances and raw values.
 			# Returns Status::UNKNOWN if status is not present.
 			#
 			# Note: In Protocol::HTTP::Headers, trailers are merged into the headers
@@ -29,31 +27,10 @@ def self.extract_status(headers)
 				status = headers["grpc-status"]
 				return Status::UNKNOWN unless status
 				
-				if status.is_a?(Header::Status)
-					status.to_i
-				else
-					# Fallback for when header policy isn't used
-					# Handle Array case (may occur with external clients)
-					status_value = if status.is_a?(Array)
-						# Flatten and take first non-nil value, recursively handle nested arrays
-						flattened = status.flatten.compact.first
-						# If still an array, take first element
-						flattened.is_a?(Array) ? flattened.first : flattened
-					else
-						status
-					end
-					
-					# Convert to string then integer to handle various types
-					# Handle case where status_value might still be an array somehow
-					if status_value.is_a?(Array)
-						status_value = status_value.first
-					end
-					status_value.to_s.to_i
-				end
+				return status.to_i
 			end
 			
 			# Extract gRPC status message from headers.
-			# Convenience method that handles both Header::Message instances and raw values.
 			# Returns `Nil` if message is not present.
 			#
 			# @parameter headers [Protocol::HTTP::Headers]
@@ -66,13 +43,7 @@ def self.extract_message(headers)
 				message = headers["grpc-message"]
 				return nil unless message
 				
-				if message.is_a?(Header::Message)
-					message.decode
-				else
-					# Fallback for when header policy isn't used
-					message_value = message.is_a?(Array) ? message.first : message.to_s
-					URI.decode_www_form_component(message_value)
-				end
+				return message.decode
 			end
 			
 			# Assign gRPC status, message, and optional backtrace to headers.
diff --git a/test/protocol/grpc/metadata.rb b/test/protocol/grpc/metadata.rb
index 8aa7a7e..03e02e3 100644
--- a/test/protocol/grpc/metadata.rb
+++ b/test/protocol/grpc/metadata.rb
@@ -8,20 +8,6 @@
 require "protocol/http"
 
 describe Protocol::GRPC::Metadata do
-	def raw_headers(values)
-		Class.new do
-			attr_accessor :policy
-			
-			define_method(:initialize) do |values|
-				@values = values
-			end
-			
-			define_method(:[]) do |key|
-				@values[key]
-			end
-		end.new(values)
-	end
-	
 	with ".extract_status" do
 		it "extracts status from headers" do
 			headers = Protocol::HTTP::Headers.new([%w[grpc-status 0]], nil, policy: Protocol::GRPC::HEADER_POLICY)
@@ -34,35 +20,14 @@ def raw_headers(values)
 		end
 		
 		it "extracts non-zero status" do
-			headers = Protocol::HTTP::Headers.new([%w[grpc-status 14]], nil, policy: Protocol::GRPC::HEADER_POLICY)
+			headers = Protocol::HTTP::Headers.new([%w[grpc-status 14]])
 			expect(subject.extract_status(headers)).to be == Protocol::GRPC::Status::UNAVAILABLE
 		end
-		
-		it "extracts a raw scalar status" do
-			headers = raw_headers("grpc-status" => "14")
-			expect(subject.extract_status(headers)).to be == Protocol::GRPC::Status::UNAVAILABLE
-		end
-		
-		it "extracts a raw array status" do
-			headers = raw_headers("grpc-status" => [nil, "13"])
-			expect(subject.extract_status(headers)).to be == Protocol::GRPC::Status::INTERNAL
-		end
-		
-		it "extracts a deeply nested raw array status" do
-			status = Class.new(Array) do
-				def flatten
-					[[["5"]]]
-				end
-			end.new
-			headers = raw_headers("grpc-status" => status)
-			
-			expect(subject.extract_status(headers)).to be == Protocol::GRPC::Status::NOT_FOUND
-		end
 	end
 	
 	with ".extract_message" do
 		it "extracts message from headers" do
-			headers = Protocol::HTTP::Headers.new([["grpc-message", "Error%20message"]], nil, policy: Protocol::GRPC::HEADER_POLICY)
+			headers = Protocol::HTTP::Headers.new([["grpc-message", "Error%20message"]])
 			expect(subject.extract_message(headers)).to be == "Error message"
 		end
 		
@@ -70,16 +35,6 @@ def flatten
 			headers = Protocol::HTTP::Headers.new
 			expect(subject.extract_message(headers)).to be_nil
 		end
-		
-		it "extracts a raw scalar message" do
-			headers = raw_headers("grpc-message" => "Error%20message")
-			expect(subject.extract_message(headers)).to be == "Error message"
-		end
-		
-		it "extracts a raw array message" do
-			headers = raw_headers("grpc-message" => ["Error%20message"])
-			expect(subject.extract_message(headers)).to be == "Error message"
-		end
 	end
 	
 	with ".assign_status!" do