feat(protocol): validate generated gateway contracts

Makefile

@@ -1,4 +1,4 @@
-.PHONY: verify generate proto-lint proto-breaking source-verify scope-verify conformance frame-verify go-test binding-compile clean-generated
+.PHONY: verify generate proto-lint proto-breaking source-verify scope-verify conformance frame-verify go-test binding-compile strict-contracts clean-generated
 
 PYTHON ?= python3
 PROTOC ?= protoc
@@ -29,6 +29,9 @@ binding-compile:
 	rustc --crate-type lib gen/rust/protocol.rs -o /tmp/versevdi-protocol-generated.rlib
 	swiftc -typecheck gen/swift/Protocol.swift
 
+strict-contracts:
+	$(PYTHON) -B tools/test_generated_contracts.py
+
 conformance:
 	$(PYTHON) -B tools/fixture_digest.py
 	go run ./tools/go-conformance
@@ -40,4 +43,4 @@ frame-verify:
 clean-generated:
 	$(PYTHON) tools/generate.py --check
 
-verify: generate proto-lint proto-breaking source-verify scope-verify go-test binding-compile conformance frame-verify clean-generated
+verify: generate proto-lint proto-breaking source-verify scope-verify go-test binding-compile strict-contracts conformance frame-verify clean-generated

gen/go/protocol/protocol.go

@@ -414,6 +414,9 @@ func (v AllocationPolicy) Validate() error {
 	if v.ReservationLeaseSeconds > 3600 {
 		violations = append(violations, FieldViolation{Field: "reservation_lease_seconds", Code: "maximum"})
 	}
+	if v.MinimumKbps > v.TargetKbps || v.TargetKbps > v.MaximumKbps {
+		violations = append(violations, FieldViolation{Field: "bounds", Code: "invalid_order"})
+	}
 	if len(violations) > 0 {
 		return ValidationError{Violations: violations}
 	}
@@ -918,6 +921,9 @@ func (v ChannelFrame) Validate() error {
 	if len(v.Payload) > 87384 {
 		violations = append(violations, FieldViolation{Field: "payload", Code: "max_length"})
 	}
+	if v.FragmentIndex >= v.FragmentCount {
+		violations = append(violations, FieldViolation{Field: "fragment_index", Code: "invalid_order"})
+	}
 	if len(violations) > 0 {
 		return ValidationError{Violations: violations}
 	}
@@ -2227,6 +2233,9 @@ func (v GatewayRegistration) Validate() error {
 	if err := v.Capabilities.Validate(); err != nil {
 		violations = append(violations, FieldViolation{Field: "capabilities", Code: "invalid_object"})
 	}
+	if v.ProtocolMinVersion > v.ProtocolMaxVersion {
+		violations = append(violations, FieldViolation{Field: "protocol_version", Code: "invalid_order"})
+	}
 	if len(violations) > 0 {
 		return ValidationError{Violations: violations}
 	}
@@ -2484,6 +2493,9 @@ func (v ManifestBounds) Validate() error {
 	if v.MaximumKbps > 100000000 {
 		violations = append(violations, FieldViolation{Field: "maximum_kbps", Code: "maximum"})
 	}
+	if v.MinimumKbps > v.TargetKbps || v.TargetKbps > v.MaximumKbps {
+		violations = append(violations, FieldViolation{Field: "bounds", Code: "invalid_order"})
+	}
 	if len(violations) > 0 {
 		return ValidationError{Violations: violations}
 	}
@@ -4043,3 +4055,21 @@ func EncodeVersionNegotiation(value VersionNegotiation) ([]byte, error) {
 	}
 	return json.Marshal(value)
 }
+
+var ErrNoCapabilityOverlap = errors.New("no capability overlap")
+
+func IntersectCapabilityProfiles(profiles ...CapabilityProfile) (CapabilityProfile, error) {
+	if len(profiles) == 0 {
+		return CapabilityProfile{}, ErrNoCapabilityOverlap
+	}
+	selected := profiles[0]
+	if err := selected.Validate(); err != nil {
+		return CapabilityProfile{}, ErrNoCapabilityOverlap
+	}
+	for _, profile := range profiles[1:] {
+		if err := profile.Validate(); err != nil || profile != selected {
+			return CapabilityProfile{}, ErrNoCapabilityOverlap
+		}
+	}
+	return selected, nil
+}

gen/manifest.json

@@ -12,7 +12,7 @@
       "2"
     ]
   },
-  "generator_sha256": "cb975bcd42bf77641b6a0f44d5ec7a6fdba1858d6b8a865e0f04e53bad82648c",
+  "generator_sha256": "88535ecf2b1c926104b10b4ab56f1bc6298e1c3e75490e36ee8581a135bcded7",
   "protocol_version": "1.0.0",
   "schema_sha256": "b8a69785112bb94d45f47c2250ca59d0bde47e3667b8ad89c9b0e2c4cfb25aec"
 }

tests/go/protocol_test.go

@@ -43,12 +43,35 @@ func TestGatewayContractsRejectUnknownVersionsAndFields(t *testing.T) {
 	}
 	for _, invalid := range []string{
 		strings.Replace(registration, `"version":"1"`, `"version":"2"`, 1),
+		strings.Replace(registration, `"version":"1"`, `"version":"0"`, 1),
 		strings.Replace(registration, `"features":["datagram.media"]`, `"features":["datagram.media"],"provider_url":"https://provider.invalid"`, 1),
 	} {
 		if _, err := protocol.DecodeGatewayRegistration([]byte(invalid)); err == nil {
 			t.Fatalf("invalid gateway registration accepted: %s", invalid)
 		}
 	}
+	if _, err := protocol.DecodeGatewayRegistration([]byte("{")); err == nil {
+		t.Fatal("DecodeGatewayRegistration accepted malformed JSON")
+	}
+}
+
+func TestGatewayRegistrationRejectsInvertedProtocolBounds(t *testing.T) {
+	registration := `{"version":"1","gateway_id":"gateway-1","instance_identity":"instance-1","certificate_identity":"cert-1","public_identity":"public-1","address":"gateway.test:443","provider_identity":"apollo-provider-1","protocol_min_version":2,"protocol_max_version":1,"connection_capacity":8,"bandwidth_capacity_kbps":100000,"features":["datagram.media"],"capabilities":{"transport":"quic","framing":"datagram-v1","media":"encoded","audio":"encoded","source_rate_control":"server","client_decode":"h264-opus"}}`
+	if _, err := protocol.DecodeGatewayRegistration([]byte(registration)); err == nil {
+		t.Fatal("DecodeGatewayRegistration accepted inverted protocol bounds")
+	}
+}
+
+func TestCapabilityIntersectionRejectsNoOverlap(t *testing.T) {
+	first := protocol.CapabilityProfile{Transport: "quic-tls13", Framing: "datagram-v1", Media: "encoded", Audio: "encoded", SourceRateControl: "server", ClientDecode: "h264-opus"}
+	if got, err := protocol.IntersectCapabilityProfiles(first, first); err != nil || got != first {
+		t.Fatalf("IntersectCapabilityProfiles matching profiles = %+v, %v", got, err)
+	}
+	second := first
+	second.ClientDecode = "hevc-opus"
+	if _, err := protocol.IntersectCapabilityProfiles(first, second); err == nil {
+		t.Fatal("IntersectCapabilityProfiles accepted profiles without a common codec profile")
+	}
 }
 
 func TestSessionAuthorityRejectsProviderRoute(t *testing.T) {

tools/generate.py

@@ -151,6 +151,12 @@ def go_validation(definition: dict[str, Any]) -> list[str]:
         reference = ref_name(prop)
         if reference:
             lines.append(f"\tif err := v.{field}.Validate(); err != nil {{ violations = append(violations, FieldViolation{{Field: \"{prop_name}\", Code: \"invalid_object\"}}) }}")
+    if name in {"AllocationPolicy", "ManifestBounds"}:
+        lines.append("\tif v.MinimumKbps > v.TargetKbps || v.TargetKbps > v.MaximumKbps { violations = append(violations, FieldViolation{Field: \"bounds\", Code: \"invalid_order\"}) }")
+    if name == "GatewayRegistration":
+        lines.append("\tif v.ProtocolMinVersion > v.ProtocolMaxVersion { violations = append(violations, FieldViolation{Field: \"protocol_version\", Code: \"invalid_order\"}) }")
+    if name == "ChannelFrame":
+        lines.append("\tif v.FragmentIndex >= v.FragmentCount { violations = append(violations, FieldViolation{Field: \"fragment_index\", Code: \"invalid_order\"}) }")
     return lines
 
 
@@ -235,6 +241,20 @@ def generate_go(defs: dict[str, dict[str, Any]], schema_hash: str, version: str,
         out.append("\treturn json.Marshal(value)")
         out.append("}")
         out.append("")
+    out.extend([
+        "var ErrNoCapabilityOverlap = errors.New(\"no capability overlap\")",
+        "",
+        "func IntersectCapabilityProfiles(profiles ...CapabilityProfile) (CapabilityProfile, error) {",
+        "\tif len(profiles) == 0 { return CapabilityProfile{}, ErrNoCapabilityOverlap }",
+        "\tselected := profiles[0]",
+        "\tif err := selected.Validate(); err != nil { return CapabilityProfile{}, ErrNoCapabilityOverlap }",
+        "\tfor _, profile := range profiles[1:] {",
+        "\t\tif err := profile.Validate(); err != nil || profile != selected { return CapabilityProfile{}, ErrNoCapabilityOverlap }",
+        "\t}",
+        "\treturn selected, nil",
+        "}",
+        "",
+    ])
     # Use io.EOF in generated code without making every generated decoder depend on
     # error-string comparison; replace the deliberately compact placeholder.
     text = "\n".join(out).replace('"errors"\n"fmt"', '"errors"\n"fmt"\n\"io"')
@@ -272,6 +292,58 @@ def swift_type(prop: dict[str, Any]) -> str:
     return "String"
 
 
+def rust_validation(definition: dict[str, Any]) -> list[str]:
+    lines: list[str] = []
+    required = set(definition.get("required", []))
+    for prop_name, prop in definition.get("properties", {}).items():
+        field = rust_field(prop_name)
+        value = f"self.{field}"
+        if prop_name not in required:
+            value = f"value"
+            lines.append(f"        if let Some(value) = &self.{field} {{")
+            prefix, suffix = "    ", "        }"
+        else:
+            prefix, suffix = "", ""
+        if prop.get("type") == "string":
+            if prop_name in required and prop.get("minLength", 0) > 0:
+                lines.append(f"        {prefix}if {value}.is_empty() {{ return Err(ValidationError::new(\"{prop_name}\", \"required\")); }}")
+            if "minLength" in prop:
+                lines.append(f"        {prefix}if !{value}.is_empty() && {value}.len() < {prop['minLength']} {{ return Err(ValidationError::new(\"{prop_name}\", \"min_length\")); }}")
+            if "maxLength" in prop:
+                lines.append(f"        {prefix}if {value}.len() > {prop['maxLength']} {{ return Err(ValidationError::new(\"{prop_name}\", \"max_length\")); }}")
+            if "const" in prop:
+                lines.append(f"        {prefix}if {value} != \"{prop['const']}\" {{ return Err(ValidationError::new(\"{prop_name}\", \"invalid_value\")); }}")
+            if "enum" in prop:
+                allowed = " && ".join(f'{value} != \"{item}\"' for item in prop["enum"])
+                lines.append(f"        {prefix}if {allowed} {{ return Err(ValidationError::new(\"{prop_name}\", \"invalid_value\")); }}")
+        if prop.get("type") == "integer":
+            if "minimum" in prop:
+                lines.append(f"        {prefix}if {value} < {prop['minimum']} {{ return Err(ValidationError::new(\"{prop_name}\", \"minimum\")); }}")
+            if "maximum" in prop:
+                lines.append(f"        {prefix}if {value} > {prop['maximum']} {{ return Err(ValidationError::new(\"{prop_name}\", \"maximum\")); }}")
+        if prop.get("type") == "array":
+            if "minItems" in prop:
+                lines.append(f"        {prefix}if {value}.len() < {prop['minItems']} {{ return Err(ValidationError::new(\"{prop_name}\", \"min_items\")); }}")
+            if "maxItems" in prop:
+                lines.append(f"        {prefix}if {value}.len() > {prop['maxItems']} {{ return Err(ValidationError::new(\"{prop_name}\", \"max_items\")); }}")
+            item_ref = ref_name(prop.get("items", {}))
+            if item_ref:
+                lines.append(f"        {prefix}for item in {value}.iter() {{ item.validate().map_err(|_| ValidationError::new(\"{prop_name}\", \"invalid_item\"))?; }}")
+        reference = ref_name(prop)
+        if reference:
+            lines.append(f"        {prefix}{value}.validate().map_err(|_| ValidationError::new(\"{prop_name}\", \"invalid_object\"))?;")
+        if suffix:
+            lines.append(suffix)
+    name = definition["name"]
+    if name in {"AllocationPolicy", "ManifestBounds"}:
+        lines.append("        if self.minimumKbps > self.targetKbps || self.targetKbps > self.maximumKbps { return Err(ValidationError::new(\"bounds\", \"invalid_order\")); }")
+    if name == "GatewayRegistration":
+        lines.append("        if self.protocolMinVersion > self.protocolMaxVersion { return Err(ValidationError::new(\"protocol_version\", \"invalid_order\")); }")
+    if name == "ChannelFrame":
+        lines.append("        if self.fragmentIndex >= self.fragmentCount { return Err(ValidationError::new(\"fragment_index\", \"invalid_order\")); }")
+    return lines
+
+
 def generate_rust(defs: dict[str, dict[str, Any]], schema_hash: str, compatibility: dict[str, Any]) -> str:
     out = [
         "// Code generated by tools/generate.py; DO NOT EDIT.",
@@ -282,6 +354,10 @@ def generate_rust(defs: dict[str, dict[str, Any]], schema_hash: str, compatibili
         f'pub const N_MINUS_2_WIRE_VERSION: &str = "{compatibility["n_minus_2"]}";',
         "pub type JsonObject = std::collections::BTreeMap<String, String>;",
         "",
+        "#[derive(Debug, Clone, PartialEq, Eq)]",
+        "pub struct ValidationError { pub field: &'static str, pub code: &'static str }",
+        "impl ValidationError { pub const fn new(field: &'static str, code: &'static str) -> Self { Self { field, code } } }",
+        "",
     ]
     for name in sorted(defs):
         definition = defs[name]
@@ -292,11 +368,103 @@ def generate_rust(defs: dict[str, dict[str, Any]], schema_hash: str, compatibili
             typ = rust_type(prop)
             if prop_name not in required:
                 typ = f"Option<{typ}>"
-            out.append(f"    pub {field}: {typ},")
+            out.append(f"    {field}: {typ},")
         out.extend(["}", ""])
+        parameters: list[str] = []
+        assignments: list[str] = []
+        for prop_name, prop in definition.get("properties", {}).items():
+            field = rust_field(prop_name)
+            typ = rust_type(prop)
+            if prop_name not in required:
+                typ = f"Option<{typ}>"
+            parameters.append(f"{field}: {typ}")
+            assignments.append(field)
+        out.append(f"impl {name} {{")
+        out.append(f"    pub fn new({', '.join(parameters)}) -> Result<Self, ValidationError> {{")
+        out.append(f"        let value = Self {{ {', '.join(assignments)} }};")
+        out.append("        value.validate()?;")
+        out.append("        Ok(value)")
+        out.append("    }")
+        out.append("    pub fn validate(&self) -> Result<(), ValidationError> {")
+        out.extend(rust_validation(definition))
+        out.append("        Ok(())")
+        out.append("    }")
+        for prop_name, prop in definition.get("properties", {}).items():
+            field = rust_field(prop_name)
+            typ = rust_type(prop)
+            if prop_name not in required:
+                typ = f"Option<{typ}>"
+            out.append(f"    pub fn {field}(&self) -> &{typ} {{ &self.{field} }}")
+        out.extend(["}", ""])
+    out.extend([
+        "pub fn intersect_capability_profiles(profiles: &[CapabilityProfile]) -> Result<CapabilityProfile, ValidationError> {",
+        "    let selected = profiles.first().ok_or_else(|| ValidationError::new(\"capabilities\", \"no_overlap\"))?.clone();",
+        "    selected.validate().map_err(|_| ValidationError::new(\"capabilities\", \"no_overlap\"))?;",
+        "    for profile in &profiles[1..] {",
+        "        profile.validate().map_err(|_| ValidationError::new(\"capabilities\", \"no_overlap\"))?;",
+        "        if profile != &selected { return Err(ValidationError::new(\"capabilities\", \"no_overlap\")); }",
+        "    }",
+        "    Ok(selected)",
+        "}",
+        "",
+    ])
     return "\n".join(out)
 
 
+def swift_validation(definition: dict[str, Any]) -> list[str]:
+    lines: list[str] = []
+    required = set(definition.get("required", []))
+    for prop_name, prop in definition.get("properties", {}).items():
+        field = swift_field(prop_name)
+        value = f"self.{field}"
+        if prop_name not in required:
+            value = "value"
+            lines.append(f"        if let value = self.{field} {{")
+            prefix, suffix = "    ", "        }"
+        else:
+            prefix, suffix = "", ""
+        if prop.get("type") == "string":
+            if prop_name in required and prop.get("minLength", 0) > 0:
+                lines.append(f"        {prefix}if {value}.isEmpty {{ throw ContractValidationError(field: \"{prop_name}\", code: \"required\") }}")
+            if "minLength" in prop:
+                lines.append(f"        {prefix}if !{value}.isEmpty && {value}.utf8.count < {prop['minLength']} {{ throw ContractValidationError(field: \"{prop_name}\", code: \"min_length\") }}")
+            if "maxLength" in prop:
+                lines.append(f"        {prefix}if {value}.utf8.count > {prop['maxLength']} {{ throw ContractValidationError(field: \"{prop_name}\", code: \"max_length\") }}")
+            if "const" in prop:
+                lines.append(f"        {prefix}if {value} != \"{prop['const']}\" {{ throw ContractValidationError(field: \"{prop_name}\", code: \"invalid_value\") }}")
+            if "enum" in prop:
+                allowed = ", ".join(f'\"{item}\"' for item in prop["enum"])
+                lines.append(f"        {prefix}if ![{allowed}].contains({value}) {{ throw ContractValidationError(field: \"{prop_name}\", code: \"invalid_value\") }}")
+            if prop.get("format") == "date-time":
+                lines.append(f"        {prefix}if ISO8601DateFormatter().date(from: {value}) == nil {{ throw ContractValidationError(field: \"{prop_name}\", code: \"invalid_time\") }}")
+        if prop.get("type") == "integer":
+            if "minimum" in prop:
+                lines.append(f"        {prefix}if {value} < {prop['minimum']} {{ throw ContractValidationError(field: \"{prop_name}\", code: \"minimum\") }}")
+            if "maximum" in prop:
+                lines.append(f"        {prefix}if {value} > {prop['maximum']} {{ throw ContractValidationError(field: \"{prop_name}\", code: \"maximum\") }}")
+        if prop.get("type") == "array":
+            if "minItems" in prop:
+                lines.append(f"        {prefix}if {value}.count < {prop['minItems']} {{ throw ContractValidationError(field: \"{prop_name}\", code: \"min_items\") }}")
+            if "maxItems" in prop:
+                lines.append(f"        {prefix}if {value}.count > {prop['maxItems']} {{ throw ContractValidationError(field: \"{prop_name}\", code: \"max_items\") }}")
+            item_ref = ref_name(prop.get("items", {}))
+            if item_ref:
+                lines.append(f"        {prefix}for item in {value} {{ try item.validate() }}")
+        reference = ref_name(prop)
+        if reference:
+            lines.append(f"        {prefix}try {value}.validate()")
+        if suffix:
+            lines.append(suffix)
+    name = definition["name"]
+    if name in {"AllocationPolicy", "ManifestBounds"}:
+        lines.append("        if minimumKbps > targetKbps || targetKbps > maximumKbps { throw ContractValidationError(field: \"bounds\", code: \"invalid_order\") }")
+    if name == "GatewayRegistration":
+        lines.append("        if protocolMinVersion > protocolMaxVersion { throw ContractValidationError(field: \"protocol_version\", code: \"invalid_order\") }")
+    if name == "ChannelFrame":
+        lines.append("        if fragmentIndex >= fragmentCount { throw ContractValidationError(field: \"fragment_index\", code: \"invalid_order\") }")
+    return lines
+
+
 def generate_swift(defs: dict[str, dict[str, Any]], schema_hash: str, compatibility: dict[str, Any]) -> str:
     out = [
         "// Code generated by tools/generate.py; DO NOT EDIT.",
@@ -306,6 +474,8 @@ def generate_swift(defs: dict[str, dict[str, Any]], schema_hash: str, compatibil
         f'public let currentWireVersion = "{compatibility["current"]}"',
         f'public let nMinus1WireVersion = "{compatibility["n_minus_1"]}"',
         f'public let nMinus2WireVersion = "{compatibility["n_minus_2"]}"',
+        "public struct ContractValidationError: Error, Equatable { public let field: String; public let code: String }",
+        "private struct AnyCodingKey: CodingKey { let stringValue: String; let intValue: Int?; init?(stringValue: String) { self.stringValue = stringValue; self.intValue = nil }; init?(intValue: Int) { self.stringValue = String(intValue); self.intValue = intValue } }",
         "",
     ]
     for name in sorted(defs):
@@ -320,16 +490,46 @@ def generate_swift(defs: dict[str, dict[str, Any]], schema_hash: str, compatibil
         out.append("    enum CodingKeys: String, CodingKey {")
         for prop_name in definition.get("properties", {}):
             out.append(f"        case {swift_field(prop_name)} = \"{prop_name}\"")
-        out.extend(["    }", "", "    public init(from decoder: Decoder) throws {",])
+        parameters: list[str] = []
+        for prop_name, prop in definition.get("properties", {}).items():
+            typ = swift_type(prop)
+            if prop_name not in required:
+                typ += "?"
+            parameters.append(f"{swift_field(prop_name)}: {typ}")
+        out.extend(["    }", "", f"    public init({', '.join(parameters)}) throws {{"])
+        for prop_name in definition.get("properties", {}):
+            field = swift_field(prop_name)
+            out.append(f"        self.{field} = {field}")
+        out.extend(["        try validate()", "    }", "", "    public init(from decoder: Decoder) throws {"])
+        out.append("        let all = try decoder.container(keyedBy: AnyCodingKey.self)")
+        out.append("        for key in all.allKeys where CodingKeys(stringValue: key.stringValue) == nil { throw ContractValidationError(field: key.stringValue, code: \"unknown_field\") }")
         out.append("        let c = try decoder.container(keyedBy: CodingKeys.self)")
+        decoded: list[str] = []
         for prop_name, prop in definition.get("properties", {}).items():
             field = swift_field(prop_name)
             typ = swift_type(prop)
             if prop_name in required:
-                out.append(f"        {field} = try c.decode({typ}.self, forKey: .{field})")
+                decoded.append(f"{field}: try c.decode({typ}.self, forKey: .{field})")
             else:
-                out.append(f"        {field} = try c.decodeIfPresent({typ}.self, forKey: .{field})")
+                decoded.append(f"{field}: try c.decodeIfPresent({typ}.self, forKey: .{field})")
-        out.extend(["    }", "}", ""])
+        out.append(f"        try self.init({', '.join(decoded)})")
+        out.extend(["    }", "", "    public func validate() throws {"])
+        out.extend(swift_validation(definition))
+        out.extend(["    }", "", "    public static func decodeJSON(_ data: Data) throws -> Self { try JSONDecoder().decode(Self.self, from: data) }", "    public func encodeJSON() throws -> Data { try validate(); return try JSONEncoder().encode(self) }", "}", ""])
+    out.extend([
+        "public extension CapabilityProfile {",
+        "    static func intersection(_ profiles: [CapabilityProfile]) throws -> CapabilityProfile {",
+        "        guard let selected = profiles.first else { throw ContractValidationError(field: \"capabilities\", code: \"no_overlap\") }",
+        "        try selected.validate()",
+        "        for profile in profiles.dropFirst() {",
+        "            try profile.validate()",
+        "            if profile != selected { throw ContractValidationError(field: \"capabilities\", code: \"no_overlap\") }",
+        "        }",
+        "        return selected",
+        "    }",
+        "}",
+        "",
+    ])
     return "\n".join(out)
 
 

tools/test_generated_contracts.py

@@ -0,0 +1,136 @@
+#!/usr/bin/env python3
+"""Compile and exercise strict generated Swift and Rust gateway contracts."""
+
+from __future__ import annotations
+
+import pathlib
+import shutil
+import subprocess
+import tempfile
+
+
+ROOT = pathlib.Path(__file__).resolve().parents[1]
+
+
+def run(command: list[str], directory: pathlib.Path) -> None:
+    result = subprocess.run(command, cwd=directory, text=True, capture_output=True, check=False)
+    if result.returncode != 0:
+        raise RuntimeError("%s\n%s%s" % (" ".join(command), result.stdout, result.stderr))
+
+
+def run_failure(command: list[str], directory: pathlib.Path, expected: str) -> None:
+    result = subprocess.run(command, cwd=directory, text=True, capture_output=True, check=False)
+    if result.returncode == 0 or expected not in result.stdout + result.stderr:
+        raise RuntimeError("expected failure: %s\n%s%s" % (" ".join(command), result.stdout, result.stderr))
+
+
+def main() -> int:
+    with tempfile.TemporaryDirectory(prefix="versevdi-generated-contracts-") as temporary:
+        workspace = pathlib.Path(temporary)
+        swift = workspace / "main.swift"
+        swift.write_text(
+            """import Foundation
+
+let capability = try CapabilityProfile(
+    transport: "quic-tls13", framing: "datagram-v1", media: "encoded",
+    audio: "encoded", sourceRateControl: "server", clientDecode: "h264-opus"
+)
+let request = try TunnelAdmissionRequest(
+    version: "1", sessionId: "session", gatewayId: "gateway", audience: "audience",
+    grant: String(repeating: "g", count: 43), reconnectSequence: 0,
+    clientNonce: String(repeating: "n", count: 16), capabilities: capability
+)
+_ = request
+let incompatible = try CapabilityProfile(
+    transport: "quic-tls13", framing: "datagram-v1", media: "encoded",
+    audio: "encoded", sourceRateControl: "server", clientDecode: "hevc-opus"
+)
+do {
+    guard try CapabilityProfile.intersection([capability, capability]) == capability else {
+        fatalError("matching capability profiles did not intersect")
+    }
+} catch { fatalError("matching capability profiles did not intersect") }
+do {
+    _ = try CapabilityProfile.intersection([capability, incompatible])
+    fatalError("profiles without overlap were accepted")
+} catch { }
+let valid = try request.encodeJSON()
+var unsupported = try JSONSerialization.jsonObject(with: valid) as! [String: Any]
+unsupported["version"] = "2"
+var downgrade = try JSONSerialization.jsonObject(with: valid) as! [String: Any]
+downgrade["version"] = "0"
+var unknown = try JSONSerialization.jsonObject(with: valid) as! [String: Any]
+unknown["unknown"] = true
+for invalid in [
+    try JSONSerialization.data(withJSONObject: unsupported),
+    try JSONSerialization.data(withJSONObject: downgrade),
+    try JSONSerialization.data(withJSONObject: unknown),
+    Data("{".utf8),
+    valid + Data(" {}".utf8),
+] {
+    do {
+        _ = try TunnelAdmissionRequest.decodeJSON(invalid)
+        fatalError("invalid tunnel admission request was accepted")
+    } catch { }
+}
+do {
+    _ = try AllocationPolicy(
+        minimumKbps: 100, targetKbps: 50, maximumKbps: 25, tier: "standard",
+        audience: "audience", protocolValue: "verse", protocolVersion: 1,
+        grantTtlSeconds: 60, reservationLeaseSeconds: 300
+    )
+    fatalError("invalid allocation bounds were accepted")
+} catch { }
+""",
+            encoding="utf-8",
+        )
+        run(["swiftc", str(ROOT / "gen/swift/Protocol.swift"), str(swift), "-o", str(workspace / "swift-contracts")], ROOT)
+        run([str(workspace / "swift-contracts")], ROOT)
+
+        rust = workspace / "protocol.rs"
+        shutil.copyfile(ROOT / "gen/rust/protocol.rs", rust)
+        with rust.open("a", encoding="utf-8") as output:
+            output.write(
+                """
+fn main() {
+    let capabilities = CapabilityProfile::new(
+        "quic-tls13".into(), "datagram-v1".into(), "encoded".into(),
+        "encoded".into(), "server".into(), "h264-opus".into(),
+    ).unwrap();
+    assert!(TunnelAdmissionRequest::new(
+        "2".into(), "session".into(), "gateway".into(), "audience".into(),
+        "g".repeat(43), 0, "n".repeat(16), capabilities.clone(),
+    ).is_err());
+    assert!(TunnelAdmissionRequest::new(
+        "0".into(), "session".into(), "gateway".into(), "audience".into(),
+        "g".repeat(43), 0, "n".repeat(16), capabilities.clone(),
+    ).is_err());
+    assert!(TunnelAdmissionRequest::new(
+        "1".into(), "session".into(), "gateway".into(), "audience".into(),
+        "g".repeat(43), 0, "short".into(), capabilities.clone(),
+    ).is_err());
+    assert!(intersect_capability_profiles(&[capabilities.clone(), capabilities.clone()]).is_ok());
+    let incompatible = CapabilityProfile::new(
+        "quic-tls13".into(), "datagram-v1".into(), "encoded".into(),
+        "encoded".into(), "server".into(), "hevc-opus".into(),
+    ).unwrap();
+    assert!(intersect_capability_profiles(&[capabilities, incompatible]).is_err());
+    assert!(AllocationPolicy::new(
+        100, 50, 25, "standard".into(), "audience".into(), "verse".into(), 1, 60, 300,
+    ).is_err());
+}
+"""
+            )
+        run(["rustc", str(rust), "-o", str(workspace / "rust-contracts")], ROOT)
+        run([str(workspace / "rust-contracts")], ROOT)
+        rust_unknown = workspace / "unknown.rs"
+        shutil.copyfile(ROOT / "gen/rust/protocol.rs", rust_unknown)
+        with rust_unknown.open("a", encoding="utf-8") as output:
+            output.write("\nfn main() { let _ = CapabilityProfile { unknown: String::new() }; }\n")
+        run_failure(["rustc", str(rust_unknown), "-o", str(workspace / "rust-unknown")], ROOT, "no field named `unknown`")
+    print("Generated strict contract checks passed")
+    return 0
+
+
+if __name__ == "__main__":
+    raise SystemExit(main())