Gemini 4 Argon optimizes Google's 200K-line ADK codebase overnight

Google described an 11-hour unattended run of Gemini 4 Argon over its Agent Development Kit codebase (200K+ lines, ~800 files, 16,892 tests) that produced two accepted optimizations: in-memory session preparation got about 40% faster and cold package import 21% faster. Four proposed changes were rejected by developers.

• Agent worked through 200K lines of code and 16,892 unit tests in 11 hours
• Session preparation sped up 40%, package import 21%
• A 158-turn run dropped from 65.6 to 56.1 seconds
• Four agent changes were rejected during developer review