Align the Kotlin SDK with agent-client-protocol pr 576 that flattens type and value at the top level

[fscarponi]

Aligns the Kotlin SDK with agent-client-protocol#576 (commit 2aca527).

What changed

Replaced the auto-generated serializer for SetSessionConfigOptionRequest with a custom
SetSessionConfigOptionRequestSerializer that flattens type and value at the top level
of the JSON object.

Serialization format

Option type	JSON format
Boolean	{"sessionId":"…","configId":"…","type":"boolean","value":true}
Select (string)	{"sessionId":"…","configId":"…","value":"model-1"}
Unknown (future)	Preserved as raw JSON via UnknownValue

The string/select format is intentionally unchanged to maintain backward compatibility.

Files changed

• Requests.kt — switched to @Serializable(with = SetSessionConfigOptionRequestSerializer::class)
• SessionConfig.kt — added SetSessionConfigOptionRequestSerializer with custom serialize/deserialize logic
• acp-model.api — regenerated via apiDump (removed synthetic $$serializer class)
• SessionConfigSelectOptionsSerializerTest.kt — updated and added tests for boolean, string, unknown type, and backward-compatible deserialization

Testing

All 340 tests in acp-model pass. No breaking changes for existing consumers.

[Copilot]

Pull request overview

This PR aligns the Kotlin acp-model SDK’s SetSessionConfigOptionRequest JSON shape with agent-client-protocol#576 by introducing a custom serializer that flattens type/value to the top level (while keeping string/select values untyped for backward compatibility).

Changes:

• Bumped SDK version from 0.16.5 to 0.16.6.
• Switched SetSessionConfigOptionRequest to a custom KSerializer that emits top-level type for boolean values.
• Updated API dump and expanded serializer tests for boolean/string/unknown/backward-compat cases.

Reviewed changes

Copilot reviewed 4 out of 5 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
build.gradle.kts	Version bump to publish the protocol-alignment change.
acp-model/src/commonMain/kotlin/com/agentclientprotocol/model/Requests.kt	Routes SetSessionConfigOptionRequest through the new custom serializer.
acp-model/src/commonMain/kotlin/com/agentclientprotocol/model/SessionConfig.kt	Implements SetSessionConfigOptionRequestSerializer flattening logic.
acp-model/src/commonTest/kotlin/com/agentclientprotocol/model/SessionConfigSelectOptionsSerializerTest.kt	Updates/extends tests around request serialization/deserialization formats.
acp-model/api/acp-model.api	Reflects regenerated public API surface (removes synthetic serializer class).

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Pull request overview

Copilot reviewed 4 out of 5 changed files in this pull request and generated 1 comment.

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[Copilot]

In the type == "boolean" branch, if value is not a JSON boolean (e.g., a string/number/object), the code either throws (non-JsonPrimitive) or falls back to UnknownValue(rawValue) which drops the original type field. That makes payloads like {...,"type":"boolean","value":"false"} impossible to round-trip and reduces forward/robust compatibility.

Consider avoiding the hard throw and, on any non-boolean value, preserving both fields by storing an UnknownValue wrapper object containing the original type and value (similar to the unknown-type branch).

Suggested change

	?: throw SerializationException("Expected boolean primitive for type 'boolean'")
	if (primitive.booleanOrNull != null) {
	SessionConfigOptionValue.BoolValue(primitive.boolean)
	} else {
	SessionConfigOptionValue.UnknownValue(rawValue)
	if (primitive?.booleanOrNull != null) {
	SessionConfigOptionValue.BoolValue(primitive.boolean)
	} else {
	// Preserve both type and value for non-boolean or non-primitive values
	val unknownWrapper = buildJsonObject {
	put("type", JsonPrimitive("boolean"))
	put("value", rawValue)
	}
	SessionConfigOptionValue.UnknownValue(unknownWrapper)