Key Evolution
- Codex 2021: Single-line code autocomplete.
- Latest Codex: Completes entire tasks autonomously in the background, creating PRs in its own container.
- Codex vs. o3: o3 excels at competitive programming; Codex is RL-tuned for real enterprise development — good PR descriptions, code style matching, proper testing.
The "Aha" Moment
- Bug finding and fixing is Codex's strongest onboarding moment.
- Power users run 20+ tasks/day in parallel — that's understanding the tool properly.
Changing Human Roles
- "In the future, you'll spend more time reviewing agent-generated code than writing code."
- Codex shows not just changed files but terminal commands and results for verification.
- PMs and non-developers can also use Codex to get answers without bothering engineers.
Agent-Friendly Codebase Tips
- Use typed languages
- Small, well-tested modules
- Unique project names (so agents can easily find related code)
Future Vision
- The boundary between "pairing" and "delegation" will disappear.
- Interaction through IDE, CLI, chat, Slack — even TikTok-style feeds where agents show work proposals.
- 2025 is definitively the year of agents.
"Future software development: you drink coffee while the agent writes code, and you review the results."