
EVERYONE'S STILL TALKING ABOUT CHATGPT WHILE OPENAI QUIETLY SHIPPED A FULL LOCAL AGENT THAT ACTUALLY TOUCHES YOUR FILESYSTEM
it's called Codex. free if you already pay for ChatGPT. and the real difference isn't a feature, it's the execution model: ChatGPT runs entirely in the cloud, Codex runs as a native desktop app with direct file system access on your machine
technical breakdown of what that actually means:
WORKSPACE MODEL
everything is scoped to "projects" — literal folders on disk that Codex gets read/write access to. no sandbox abstraction, no upload step. you point it at a directory and it operates on the real files sitting there
MODEL + REASONING CONTROLS
you pick the model (currently GPT-5.5) and a separate reasoning intensity slider — low through extra high. this isn't just "smarter vs dumber," it's a compute/latency tradeoff exposed directly to the user. medium/high is the sweet spot for most tasks, extra high is for genuinely hard multi-step reasoning where you'll tolerate slower output
FILE GENERATION
ask it to process a folder of receipts and it builds a real .xlsx, multi-tab, formulas and categorization included, rendered inline in a side panel via its own document viewer. the file lives on disk immediately, no export step, no intermediate cloud copy
SKILLS = PERSISTENT INSTRUCTION SETS
this is the part with real architectural weight. a "skill" is just a saved instruction block Codex writes for itself when you say "make a skill called X that always does Y." functionally this is user-defined system-prompt injection you control through natural language instead of a config file. no other consumer AI tool exposes this as cleanly
PLUGIN LAYER = ACTION SURFACE
Gmail, Google Drive, Calendar, Canva, Remotion — plugins aren't just data connectors, they're what convert Codex from a text generator into something with actual write-access to third-party systems. connect Gmail and it can draft in your tone, learn from your reply history, and you can literally tell it to run on a cron-like schedule ("every morning at 9am") and it sets up the automation itself, no explicit scheduling logic from you
BACKGROUND EXECUTION
tasks run async while you work elsewhere — a persistent UI element surfaces only when a task needs a decision from you (e.g. granting network access mid-task). this is closer to a job queue with human-in-the-loop checkpoints than a chatbot turn-based interface
net effect: this collapses "generate content" and "execute on my system" into one interface, something ChatGPT's cloud-only architecture structurally can't do
most of your feed is still treating this as "ChatGPT but for coders." it's not. it's a local execution agent, free, and most people haven't opened it yet
the window is open
Codex研究ラボ@Gencoin8
English










