nightly: agent: Use ACP v2 content for native prompts (#65417)
Executive Summary
Remove the native agent's internal ACP v2-to-v1 prompt-content round trip. Native prompt routing, slash-command parsing, MCP/skill dispatch, thread insertion and user-message event conversion now consume v2 content directly. Preserve mention handling, attachment ordering, inline skill continuation, raw source blocks and submitted v2 metadata/icons/annotations in live shared state.
Hyperscale Open Source & Cloud Infrastructure Review
From an infrastructure engineering, cloud-native scale, and hyperscale governance standpoint: - **Hyperscale Provenance:** Open-sourcing internal frameworks subjects proprietary systems to rigorous public analysis. - **De-facto Standard Cohesion:** Publishing enterprise tooling establishes interoperable specifications across distributed execution. - **Vendor Decoupling:** Platform engineers can inspect underlying telemetry and memory layouts without black-box vendor lock-in.
Impact on the Open Ecosystem
Bridges enterprise engineering scale with independent, reproducible open-source software stacks.