Proposal (rationale)

OpenAI Agents SDK and Microsoft Agent Framework already show that language parity exposes which parts of an abstraction are essential and which are idiomatic or release-timed. Google ADK adds a different pressure: a broad framework family with agent and workflow runtimes, structured task delegation, tool confirmation, evaluation and explicit session/event evolution.

Google ADK for Python is the primary proposed source. Its public landing page currently warns of breaking changes to agent APIs, events, and session schemas and links implementations in several languages. Those are documented expectations only; the extraction must pin the actual version, compatibility contract, and one bounded parity comparison.

Decision

proposed — 2026-08-15. Captured as the evolving multi-language framework child of WI-018, after WI-019.

Plan

Requirements

• Pin the Python repository SHA, licence, release/version context, read date, and measured scale; pin any second-language repository separately.
• Trace one agent or workflow turn through runner, events, session state, task delegation, tool invocation, and termination.
• Trace the documented session/event migration in implementation or compatibility tests, stating what old state can be read and what cannot.
• Trace one tool-confirmation path and identify action identity, argument binding, durability, and host authority.
• Trace one evaluation path only far enough to compare runtime-owned evidence with WI-021’s evaluation-system boundary.
• Compare one secondary language on a predeclared mechanism; do not attempt a whole-family inventory.

Impacts

• One durable/local-product extraction with a separately pinned parity source when used.
• Candidate evidence for schema evolution, backwards-compatible persistence, task handoff, approval binding, and protocol integration; WI-028 adjudicates.

Approach

Read Python as primary. Choose the secondary language after source reconnaissance based on which implementation has executable coverage of the selected mechanism. Center the breaking session and event boundary because silent incompatibility in persisted state is more consequential than API spelling.

Acceptance criteria / tests

1. Every source has its own SHA, licence, date, scope, and measurement commands.
2. One runtime path and one persisted-schema migration path are traced through implementation and tests.
3. Tool confirmation states what is bound, durable, authenticated, and host-owned.
4. The parity comparison classifies each difference as idiom, design divergence, migration timing, or not established.
5. Evaluation and A2A claims are bounded; opinion is labelled; catalogue work remains WI-028.
6. rungs check and site links pass.

Out of scope

• Surveying every ADK language or cloud deployment target.
• Hosted Vertex AI behaviour not implemented in the pinned public repositories.
• Benchmarking models or framework performance.
• Full A2A protocol analysis, which is WI-026.
• Catalogue, module, or CLI changes.

Execution

Not started.

Review

Not started.