Bun Rewritten in Rust in 11 Days as OpenAI Drops GPT-5.6

Jarred Sumner, the creator of the Bun runtime, completely converted 535,000 lines of code from Zig to Rust in just eleven days using a pre-release version of Anthropic's Fable 5. Managing up to 64 parallel AI instances, the automated overhaul fixed 128 bugs and slashed binary sizes by twenty percent, substituting an estimated three developer-years with roughly $165,000 worth of API compute.

Meanwhile, OpenAI expanded its catalog with GPT-5.6 across three tier sizes called Sol, Terra, and Luna. The top-tier model grabbed the high score on the Coding Agent Index at 80 points, costing five dollars per million input tokens while running four background agents concurrently by default.

The launch was accompanied by ChatGPT Work, which hooks into Slack, Notion, and Google Drive to automatically generate corporate dashboards and slide decks. Product lead Thibaut Sottiaux admitted that confusing billing settings caused users to accidentally burn through their usage limits, prompting OpenAI to temporarily lift five-hour cap windows after traffic spiked to six million users.

Not to be outdone, SpaceXAI launched Grok 4.5 alongside Cursor, utilizing 1.5 trillion parameters specifically optimized for software engineering. Tests show Grok 4.5 consumes under two million tokens for coding tasks where rivals use up to seven million, drastically undercutting existing API pricing models across the board.

Software development has officially transitioned into a high-stakes arena where human engineers act as air traffic controllers for armies of silicon syntax-generators. As model prices plummet and autonomous rewrites become lunch-break projects, the real tech war is no longer about who writes the code, but who pays the electricity bill when the agents run wild.

Source: bun.com