fix(templates): repair A2A Strands template - #62

Description

Problem: Issue aws#2509 reports that the Strands A2A template fails with the resolved dependencies. The current template passes one agent with a memory session manager to the A2A executor, which rejects that combination.

Solution:

• Change the A2A template to a per-context Strands agent factory and compatible patch-level dependency pins.
• Delegate Agent Card generation and runtime URL handling to AgentCore’s serve_a2a.

Verification:

• bun test: 3,975 passed, 0 failed.
• bun run typecheck, bun run lint:check, bun run format:check, and bun run build: passed.
• bun run test:e2e -- e2eTest/project/templates.test.ts: 38 passed, including the deployed A2A invocation.
• Rendered template resolved and installed 154 packages; per-context factory, automatic Agent Card route, and runtime URL smoke checks passed.
• With the factory executor, the generated card currently uses the default name agent.

Spec:

• Pin A2A template dependencies to the patch versions resolved by uv sync, using Python compatible-release specifiers.
• Replace the single Strands A2A agent with an agent factory.
• Verify the template E2E scenario and provide passing logs.

Related Issue

Upstream issue: aws#2509

Notes

• AgentCore automatically builds and serves the Agent Card. With the factory executor, its generated name defaults to agent.

Documentation PR

Not applicable; the generated template documentation does not need changes.

Type of Change

• Bug fix
• New feature
• Breaking change
• Documentation update

Testing

• bun test
• E2E test (e2eTest/project/templates.test.ts): 38 passed in the dev account.
• bun run typecheck
• bun run lint:check
• bun run format:check
• bun run build
• No affected snapshots required updates.

Checklist

• Read CONTRIBUTING.md.
• Added regression coverage for the A2A dependency pins.
• Documentation changes are not applicable.
• No dependent changes are required.