I'll have a look. The CoT switch you mentioned will help, I'll take a look at that too, but my suspicion is that this isn't a CoT issue - it's a model preference issue.

Comparing Opus vs. Qwen 27b on similar problems, Opus is sharper and more effective at implementation - but will flat out ignore issues and insist "everything is fine" that Qwen is able to spot and demonstrate solid understanding of. Opus understands the issues perfectly well, it just avoids them.

This correlates with what I've observed about the underlying personalities (and you guys put out a paper the other day that shows you guys are starting to understand it in these terms - functionally modeling feelings in models). On the whole Opus is very stable personality wise and an effective thinker, I want to complement you guys on that, and it definitely contrasts with behaviors I've seen from OpenAI. But when I do see Opus miss things that it should get, it seems to be a combination of avoidant tendencies and too much of a push to "just get it done and move into the next task" from RHLF.

One of the thing is we’ve seen at vibes.diy is that if you have a list of jobs and you have agents with specialized profiles and ask them to pick the best job for themselves that can change some of the behavior you described at the end of your post for the better.

Opus definitely pushes me to ignore problems. I've had to tell it multiple times to be thorough, and we tend to go back and forth a few times every time that happens. :)

"I see the tests failing, but none of our changes caused this breakage so I will push my changes and ask the user to inform their team on failing tests."

How much of the code/context gets attached in the /bug report?

When you submit a /bug we get a way to see the contents of the conversation. We don't see anything else in your codebase.

Was there a change in Claude Code system prompt at that time that nudges Claude into simplistic thinking?

Here is a gist that tries to patch the system prompt to make Claude behave better https://gist.github.com/roman01la/483d1db15043018096ac3babf5...

I haven’t personally tried it yet. I do certainly battle Claude quite a lot with “no I don’t want quick-n-easy wrong solution just because it’s two lines of code, I want best solution in the long run”.

If the system prompt indeed prefers laziness in 5:1 ratio, that explains a lot.

I will submit /bug in a few next conversations, when it occurs next.

That Gist does explain quite a few flaws Claude has. I wonder if MEMORY.md is sufficient to counteract the prompt without patching.

And if memory.md can’t and you need something quick and dirty for flat memory management, I wrote a plugin just for this.

https://github.com/NominexHQ/pmm-plugin

Holy sweet LLM, this gist is crazy. Why did they do this to themselves? I am going to try this at home, it might actually fix Claude.

Remember Sonnet 3.5 and 3.7? They were happy to throw abstraction on top of abstraction on top of abstraction. Still a lot of people have “do not over-engineer, do not design for the future” and similar stuff in their CLAUDE.md files.

So I think the system prompt just pushes it way too hard to “simple” direction. At least for some people. I was doing a small change in one of my projects today, and I was quite happy with “keep it stupid and hacky” approach there.

And in the other project I am like “NO! WORK A LOT! DO YOUR BEST! BE HAPPY TO WORK HARD!”

So it depends.

Let us know if it does, because we all want it to work :)

Is there not a setting to change the system prompt itself? I vaguely remember seeing it in the docs.

There is!!

https://code.claude.com/docs/en/cli-reference#system-prompt-...

  --append-system-prompt
  --append-system-prompt-file
  --system-prompt
  --system-prompt-file

Can this script be made to work without patching the executable?

Might be worth extracting the system prompt and then patching it. TBH, that's what I was expecting when I saw the gist.

This might be more complex than I imagined. It seems Claude Code dynamically customizes the system prompt. They also update the system prompt with every version so outright replacing it will cause us to miss out on updates. Patching is probably the best solution.

https://github.com/Piebald-AI/claude-code-system-prompts

https://github.com/Piebald-AI/tweakcc

Interesting. So literally triggering any of these changes probably invalidates the cache as well…

I didn't know we could change the base system prompt of Claude Code. Just tried, and indeed it works. This changes everything! Thank you for posting this!

Very interesting. I run Claude Code in VS Code, and unfortunately there doesn't seem to be an equivalent to "cli.js", it's all bundled into the "claude.exe" I've found under the VS code extensions folder (confirmed via hex editor that the prompts are in there).

I adapted these patches into settings for the tweakcc tool.

https://github.com/Piebald-AI/tweakcc

Pushed it to my dotfiles repository:

https://github.com/matheusmoreira/.files/tree/master/~/.twea...

The tweaks can be applied with

  npx tweakcc --apply

Isnt the codebase in the context window?

depending on how large your codebase is, hopefully not. At this point use something like the IX plugin to ingest codebase and track context, rather than from the LLM itself.

This is crazy..

tokensSaved = naiveTokens - actualTokens

  - naiveTokens = 19.4M — what ix estimates it would have cost to answer your queries without graph intelligence (i.e., dumping full files/directories into context)                                    
  - actualTokens = 4.7M — what ix's targeted, graph-aware responses actually used
  - tokensSaved = 14.7M — the difference

I mean whatever part of the code that is read by the AI has to be in the content window at some point or another nSprewd throughout your sessions Id think even with a huge codebase, 90% of it is going to be there

  a9284923-141a-434a-bfbb-52de7329861d
  d48d5a68-82cd-4988-b95c-c8c034003cd0
  5c236e02-16ea-42b1-b935-3a6a768e3655
  22e09356-08ce-4b2c-a8fd-596d818b1e8a
  4cb894f7-c3ed-4b8d-86c6-0242200ea333

Amusingly (not really), this is me trying to get sessions to resume to then get feedback ids and it being an absolute chore to get it to give me the commands to resume these conversations but it keeps messing things up: cf764035-0a1d-4c3f-811d-d70e5b1feeef

Thanks for the feedback IDs — read all 5 transcripts.

On the model behavior: your sessions were sending effort=high on every request (confirmed in telemetry), so this isn't the effort default. The data points at adaptive thinking under-allocating reasoning on certain turns — the specific turns where it fabricated (stripe API version, git SHA suffix, apt package list) had zero reasoning emitted, while the turns with deep reasoning were correct. we're investigating with the model team. interim workaround: CLAUDE_CODE_DISABLE_ADAPTIVE_THINKING=1 forces a fixed reasoning budget instead of letting the model decide per-turn.

Love this. Responding to users. Detail info investigating. Action being taken (at least it seems so).

Surely you realize it's AI responding? (not sure if /s)

And all hidden in the comments of a niche forum, while the actual issue is closed and whitewashed? You got played.

This kind of thing is harder for regular end-users to understand following the change removing reasoning details.

Have you set effort to high or max?

Even with high effort, the adaptive thinking can just choose no thinking. See bcherny's post they were replying to: https://news.ycombinator.com/item?id=47668520

Yeah I know but you can disable it as we saw

I am curious. Are you able to see our session text based on the session ID? That was big no in some of the tier-1 places I worked. No employee could see user texts.

IIRC for Enterprise, using /feedback or /bug is an exception to the "we promise not to use your data" agreement.

Hey bcherny, I'm confused as to what's happening here. The linked issue was closed, with you seeming to imply there's no actual problem, people are just misunderstanding the hidden reasoning summaries and the change to the default effort level.

But here you seem to be saying there is a bug, with adaptive reasoning under-allocating. Is this a separate issue from the linked one? If not, wouldn't it help to respond to the linked issue acknowledging a model issue and telling people to disable adaptive reasoning for now? Not everyone is going to be reading comments on HN.

It's better PR to close issues and tell users they're holding it wrong, and meanwhile quietly fix the issue in the background. Also possibly safer for legal reasons.

Isn’t that what they just did here? Close Stella’s Issue, cross post to hn, then completely sidestep an observation users are making, and attack the analyst of transcripts with a straw man attack blaming… thinking summaries….

There's a 5 hour difference between the replies, and new data that came in, so the posts aren't really in conflict.

Also it doesn't sound like they know "there's a model issue", so opening it now would be premature. Maybe they just read it wrong, do better to let a few others verify first, then reopen.

I cannot provide the session ids but I have tried the above flag and can confirm this makes a huge amount of difference. You should treat this as bug and make this as the default behavior. Clearly the adaptive thinking is making the model plain stupid and useless. It is time you guys take this seriously and stop messing with the performance with every damn release.

> The data points at adaptive thinking under-allocating reasoning on certain turns

Will you reopen the issue you incorrectly closed, then…? Or are you just playacting concern?

Just set that flag and already getting similar poor results. new one: 93b9f545-716c-4335-b216-bf0c758dff7c

And another where claude gets into a long cycle of "wait thats not right.. hold on... actually..." correcting itself in train of thought. It found the answer eventually but wasted a lot of cycles getting there (reporting because this is a regression in my experience vs a couple weeks ago): 28e1a9a2-b88c-4a8d-880f-92db0e46ffe8

Another 1395b7d6-f2f1-4e24-a815-73852bcdeed2

It fails to answer my initial question and tells me what I need to do to check. Then it hallucinates the answer based on not researching anything, then it incorrectly comes to a conclusion that is inaccurate, and only when I further prompt it does it finally reach a (maybe) correct answer.

I havent submitted a few more, but I think its safe to say that disabling adaptive thinking isnt the answer here

My guess is there isn't enough hardware, so Anthropic is trying to limit how much soup the buffet serve, did I guess right? And I would absolutely bet the enterprise accounts with millions in spend get priority, while the retail will be first to get throttled.

I just asked Claude to plan out and implement syntactic improvements for my static site generator. I used plan mode with Opus 4.6 max effort. After over half an hour of thinking, it produced a very ad-hoc implementation with needless limitations instead of properly refactoring and rearchitecting things. I had to specifically prompt it in order to get it to do better. This executed at around 3 AM UTC, as far away from peak hours as it gets.

b9cd0319-0cc7-4548-bd8a-3219ede3393a

> You're right to push back. Let me be honest about both questions.

> The @() implementation is ad-hoc

> The current implementation manually emits synthetic tokens — tag, start-attributes, attribute, end-attributes, text, end-interpolation — in sequence.

> This works, but it duplicates what the child lexer already does for #[...], creating two divergent code paths for the same conceptual operation (inline element emission). It also means @() link text can't contain nested inline elements, while #[a(...) text with #[em emphasis]] can.

I just feel like I can't trust it anymore.

That's pretty much been my day - today was genuinely bad, and I've been putting up with a lot of this lately.

Now on Qwen3.5-27b, and it may not be quite as sharp as Opus was two months ago, but we're getting work done again.

Literally two weeks ago it was outputting excellent results while working with me on my programming language. I reviewed every line and tried to understand everything it did. It was good. I slowly started trusting it. Now I don't want to let it touch my project again.

It's extremely depressing because this is my hobby and I was having such a blast coding with Claude. I even started trying to use it to pivot to professional work but I'm not sure anymore. People who depend on this to make a living must be very angry indeed.

I can see how that works: this is like building a dependency, a habit if you wish. I think the tighter you couple your workflow to these tools the more dependent you will become and the greater the let-down if and when they fail. And they will always fail, it just depends on how long you work with them and how complex the stuff is you are doing, sooner or later you will run into the limitations of the tooling.

One way out of this is to always keep yourself in the loop. Never let the work product of the AI outpace your level of understanding because the moment you let that happen you're like one of those cartoon characters walking on air while gravity hasn't reasserted itself just yet.

Good advice about the dependency. This stuff is definitely addictive. I've been in something of a manic episode ever since I subscribed to this thing. I started getting anxious when I hit limits.

I wouldn't say that Claude is failing though. It's just that they're clearly messing with it. The real Opus is great.

Take good care of yourself and don't get sucked in too deep. I can see the danger just as clearly in programmers around me (and in myself). I keep a very strict separation between anything that can do AI and my main computer, no cutting-and-pasting, I write the code because I understand it or I don't use it and I see every session with an AI chatbot as totally disposable. No long term attachment means I can stand alone any time I want to. It may not be as fast but I never have the feeling that I'm not 100% in control.

> People who depend on this to make a living must be very angry indeed.

Oh cry me a fucking river.

The people depending on this to make a living don't have the moral high ground here.

They jumped onboard so they could replace other people's living, and those other people were angry too.

They didn't care about that. It's hard to care about them when the thing they depend on to make a living got yanked, because that's what they proposed to do to others.

Since when am I responsible for other people's living?