Add optional implementation identity (serverInfo/clientInfo) to the initialize handshake

[colbylwilliams]

Closes #306.

Summary

The initialize handshake negotiates a protocol version but carries no way to identify the implementation — the software and build — on either end. LSP and MCP both exchange this. This adds an optional, purely-additive identity to the handshake.

A new shared Implementation type:

export interface Implementation {
  name: string;      // required
  version?: string;  // SemVer recommended, not required
  title?: string;    // optional display name
}

wired into both sides of the handshake:

• InitializeResult.serverInfo?: Implementation
• InitializeParams.clientInfo?: Implementation

Semantics

Implementation identity is informational only — for logging, telemetry, an about/status affordance, and, as a last resort, a known-issue workaround for a specific buggy build. It answers "what software, and which build, is on the other end," which is distinct from both the negotiated protocolVersion and the AgentInfo that names the agent persona.

It is not a feature-detection mechanism. Feature availability stays with the capability model (ClientCapabilities and the various *.capabilities declarations); peers should not gate protocol behaviour on parsing version.

Compatibility

Purely additive and optional. Both fields default to absent; a peer that omits its own info, or ignores the other side's, stays fully interoperable. No protocol version bump.

Changes

• types/common/commands.ts — the Implementation type and the two optional fields.
• Regenerated all five client mirrors (Go/Rust/Kotlin/Swift/TypeScript) and the JSON Schema.
• docs/specification/lifecycle.md — documents the fields and adds an Implementation identity section.
• Round-trip conformance fixture 028-implementation-identity.json, wired into every client's harness.
• CHANGELOG entries for the spec and each client.

[Copilot]

Pull request overview

Adds an additive Implementation identity type and wires it into the initialize handshake (InitializeParams.clientInfo? / InitializeResult.serverInfo?) so clients/hosts can optionally report implementation name/version/title for logging/telemetry/about surfaces (explicitly not for feature detection). The change ripples through the generated client mirrors, JSON Schema outputs, conformance fixtures, and documentation.

Changes:

• Introduce Implementation and add optional clientInfo/serverInfo fields to the initialize command types.
• Regenerate/update JSON Schemas and all client mirrors (Go/Rust/Kotlin/Swift/TypeScript) including round-trip fixture harnesses.
• Document the new handshake fields and add a conformance round-trip fixture + changelog entries.

Show a summary per file

File	Description
types/test-cases/round-trips/028-implementation-identity.json	Adds a round-trip fixture for the new Implementation wire type.
types/common/commands.ts	Defines Implementation and adds clientInfo? / serverInfo? to initialize params/result.
scripts/generate-swift.ts	Registers Implementation as a generated Swift command struct.
scripts/generate-rust.ts	Registers Implementation as a generated Rust command struct.
scripts/generate-kotlin.ts	Registers Implementation as a generated Kotlin command struct.
scripts/generate-go.ts	Registers Implementation as a generated Go command struct.
schema/errors.schema.json	Updates schema output to include Implementation and the new initialize fields.
schema/commands.schema.json	Updates schema output to include Implementation and the new initialize fields.
docs/specification/lifecycle.md	Documents clientInfo / serverInfo and adds an “Implementation identity” subsection.
clients/typescript/test/types-round-trip.test.ts	Adds Implementation to the TS fixture type binder.
clients/typescript/CHANGELOG.md	Notes the new optional initialize identity fields in the TS client changelog.
clients/swift/CHANGELOG.md	Notes the new optional initialize identity fields in the Swift client changelog.
clients/swift/AgentHostProtocol/Tests/AgentHostProtocolClientTests/TypesRoundTripFixtureTests.swift	Adds Implementation decode/re-encode case to the Swift round-trip harness.
clients/swift/AgentHostProtocol/Sources/AgentHostProtocol/Generated/Commands.generated.swift	Generated Swift types include Implementation and initialize fields.
clients/rust/crates/ahp-types/tests/roundtrip_corpus.rs	Adds Implementation to Rust round-trip corpus harness.
clients/rust/crates/ahp-types/src/commands.rs	Generated Rust types include Implementation and initialize fields.
clients/rust/CHANGELOG.md	Notes the new optional initialize identity fields in the Rust client changelog.
clients/kotlin/src/test/kotlin/com/microsoft/agenthostprotocol/RoundTripCorpusTest.kt	Adds Implementation to Kotlin round-trip corpus harness.
clients/kotlin/src/main/kotlin/com/microsoft/agenthostprotocol/generated/Commands.generated.kt	Generated Kotlin types include Implementation and initialize fields.
clients/kotlin/CHANGELOG.md	Notes the new optional initialize identity fields in the Kotlin client changelog.
clients/go/CHANGELOG.md	Notes the new optional initialize identity fields in the Go client changelog.
clients/go/ahptypes/roundtrip_fixture_test.go	Adds Implementation decode/re-encode case to Go round-trip harness.
clients/go/ahptypes/commands.generated.go	Generated Go types include Implementation and initialize fields.
CHANGELOG.md	Notes the new optional initialize identity fields in the spec changelog.

Review details

• Files reviewed: 22/24 changed files
• Comments generated: 1
• Review effort level: Low