chore(openspec): archive engineering-docs and phase-2-production-ready changes

- engineering-docs → archive/2026-03-29-engineering-docs (63/63 tasks complete)
- phase-2-production-ready → archive/2026-03-29-phase-2-production-ready (89/89 tasks complete)
- openspec/specs/ synced with all Phase 1 + Phase 2 + engineering-docs capabilities (22 specs total)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

openspec/changes/archive/2026-03-29-engineering-docs/specs/sdk-guide/spec.md

@@ -0,0 +1,28 @@
+## ADDED Requirements
+
+### Requirement: SDK integration guide
+The system SHALL include a document (`docs/engineering/11-sdk-guide.md`) that explains how each of the four language SDKs is structured, how to use them, and how to contribute to or extend them.
+
+#### Scenario: SDK architecture overview present
+- **WHEN** a new engineer reads 11-sdk-guide.md
+- **THEN** they SHALL understand that all four SDKs (Node.js, Python, Go, Java) implement the same API surface (14 endpoints, 4 service clients, 1 TokenManager, 1 error type) with identical semantics, and why consistency across SDKs is a non-negotiable standard
+
+#### Scenario: Node.js SDK documented
+- **WHEN** a new engineer reads the Node.js SDK section
+- **THEN** they SHALL find: installation (`npm install @sentryagent/idp-sdk`), the AgentIdPClient constructor, all 4 service clients (agents, credentials, tokens, audit), TokenManager auto-refresh behaviour, AgentIdPError structure, and a complete working code example for the most common flow (register agent → generate credential → issue token)
+
+#### Scenario: Python SDK documented
+- **WHEN** a new engineer reads the Python SDK section
+- **THEN** they SHALL find: installation (`pip install sentryagent-idp`), both sync (AgentIdPClient) and async (AsyncAgentIdPClient) variants, TokenManager and AsyncTokenManager auto-refresh, AgentIdPError, and a complete working example for sync and async usage
+
+#### Scenario: Go SDK documented
+- **WHEN** a new engineer reads the Go SDK section
+- **THEN** they SHALL find: installation (`go get github.com/sentryagent/idp-sdk-go`), AgentIdPClient construction, goroutine-safe TokenManager, context.Context usage pattern, AgentIdPError with Code/HTTPStatus/Details, and a complete working example
+
+#### Scenario: Java SDK documented
+- **WHEN** a new engineer reads the Java SDK section
+- **THEN** they SHALL find: Maven/Gradle dependency snippet, AgentIdPClient construction with builder pattern, sync methods and CompletableFuture async counterparts, thread-safe TokenManager, AgentIdPException, and a complete working example
+
+#### Scenario: SDK contribution guide included
+- **WHEN** a new engineer needs to add a new endpoint to all SDKs
+- **THEN** the guide SHALL provide a step-by-step checklist for adding a new method to all four SDKs consistently: where to add the method, what the signature pattern is, how to write the corresponding test, and how to verify it compiles/passes in each language