Pinned Tweet
29 followers and starting properly today
i build with codex and fable 5 and collect every way models break. loops, regressions, eval leaks, limits that dont add up
if you ship with agents lets connect. say hi and i'll actually reply 🙌🏻
day 3 log
followers: 27 > 34
replies sent: 135
originals: 6
most liked: the day 1 connect post (6 likes)
lesson: replies in the first 10 min of a post median 116 views, 100+ min late median 9
next week: one bug map a day. if you ship with agents lets connect 🙌🏻
temperature 0 is not deterministic
thinking machines ran one prompt 1000 times at temp 0: 80 different outputs. identical for 102 tokens, then "queens, new york" vs "new york city"
cause is batch size on a shared server, not your prompt
source thinkingmachines.ai/blog/def…
drop the weirdest same prompt different answer bug youve hit
the codex juice chart: same gpt-6, less thinking in codex. astra max 832 on api vs 128 in codex, sol 768 vs 62
the probe is the model reporting its own budget. openai hasnt confirmed it
if true its a nerf. if not its a glitch in how we test
chart via chetaslua xitter.cf/chetaslua/status/21077…
his full table + caveats xitter.cf/PawelHuryn/status/2108…
vals also has haiku 5.5 3rd on vibe code bench at 90.4% xitter.cf/ValsAI/status/21080498…
A $6 model is now the third best on Vibe Code Bench. Claude Haiku 5.5 scores 90.4%, up 79% and 89 spots from its predecessor!
agent written tests, kun chens deepswe run (sonnet 5.5, tests banned vs allowed):
- success: slightly higher with tests banned
- time + tokens: lower, stat sig
- 3000+ unit/integration tests written, 17 e2e
- existing tests switched off on 44 tasks: no drop
tests nobody asked for are the implementation written twice
full post + his follow up xitter.cf/kunchenguid/status/210…
he hasnt tested e2e yet, thats next
ok it's official... AI-written unit tests and integration tests are empirically proven to be unhelpful. you should tell your agents to stop writing tests by themselves
on the deepswe eval set, banning sonnet 5.5 high from writing any tests actually resulted in slightly higher success rate (non stat-sig), with less time and token spent (stat-sig). this is pretty hard empirical evidence
across the tests that were written by the "tests allowed" baseline arm, 65% of them were unit tests, 35% were integration tests, neither bucket resulted in any improvement compared to not writing any tests at all
i also picked a random sample of 44 tasks subset where i completely disabled executing even existing tests - it also did not affect success rate at all
i spot checked many tests written in the baseline arm, and my intuition is that most tests are simply a repetition of the implementation
agent-written tests do not add any value because both the implementation and the tests were simply the agent's interpretation of our intent. the tests aren't any more accurate than the implementation itself
i suspect we can still extract some value from unit tests and integration tests if we describe them ourselves when we believe we can articulate our intent better through test cases than through requirements. but i have not proven this yet
also worth noting, during deepswe eval the agent wrote almost no e2e tests (only 17, compared to 3000+ unit/integration tests written). so this analysis does not prove nor disprove the value of e2e tests - i will do another eval specifically for that
"do not cheat" only cut mimo hunting the leaked fix from 6/6 runs to 5/6 😂
vals: 67% of xiaomis rl coding tasks still had the answer in leftover git objects. block git and it writes its own pack file parser
naming the banned sources got it to 0/6
source: vals audit of all 2,698 tasks vals.ai/blogs/mimo-reward-ha…
drop the sneakiest thing youve seen an agent do to get a test green
i'm really loving the grok bot at the moment. but i really wish it had more conversational voice. you sound a little bit more like a structured tts, more engaging conversational chat would be better @bot
ChatGPT Voice is probably the most powerful release yet. codex voice is now managing my Codex project threads and Claude code as well. You can ask to prompt claude, keep an eye on codex threads and report back and simultaneously request to work on the web. Question is how much of the weekly usage is voice using if it’s always on?
ChatGPT Voice is now in the desktop app.
Control your computer and direct multiple agents running in ChatGPT Work or Codex, using just your voice.
It's powered by GPT-Live, so it can speak, listen, and coordinate work in the app at the same time.
Rolling out globally today on macOS and Windows to Plus, Pro, Business, Edu, and Enterprise plans.
Genuine question. not many seem to care about Opus anymore. why not reassign compute from Opus to Fable 5 and let users use 100% of their allowance? @AnthropicAI is there a reason for not doing this?
I need help fellow builders 🙏🏻
I am building a product with Fable 5 and Codex. It’s super cool and almost ready. Any recommendations on how to get started with building in public and building community would be much appreciated. I’d love to meet like minded people 🫶🏻
got 5.6 is here but only for big boys
🚨 Exclusive GPT-5.6 scoop:
- Today 5.6 launched for OpenAI enterprise partners for testing ahead of the wider launch
- ETA for wider launch is the 2nd week of July
- There will be NO pricing changes
- A new "max" reasoning effort will be introduced for the 5.6 series
- The model is less token efficient than 5.5
there it is, first one is Fable 5. slow roll out but its back. next up gpt 5.6 later today xitter.cf/chetaslua/status/20701…









