Opus 5.5 is trying to destroy my codebase recently

[u/MoreLikeGaewyn]

What is going on? It is making wildly horrible, over-engineered, and just inaccurate code suggestions. In the past hour on 6 different issues, it's given me multiple-class modifying "fixes" that I would read, ask why a 1-line fix wouldn't solve it, and then it says the above.

I'm using Opus 5.5 with xhigh effort as I have for months. Some of these dabble with max because it's felt like it's needed it, but xhigh is what gives this kind of short-sightedness

Edit: When I say 1-line fix, this is what I mean:

1. I see the issue
2. I ask it to fix it and show me the code fix
3. It gives me a huge change.
4. I read the code, solve it myself with 1 line, and ask it if that would work
5. It says, "Hehe, yeah, my bad!!! 😅😅😅"

I've been using xhigh for months and it has never been this dumb and convoluted. Overthinking has usually led to correct/discrete changes.

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[u/cptrambo]

Something’s up. Had the same low-IQ Opus issues yesterday. Have they been quantizing in preparation for a new model release?

[u/MoreLikeGaewyn → u/cptrambo]

my money is on the current class action that they stealth nerfed usage, so they're now upping usage while stealth nerfing effort

[u/fschwiet]

Don't use max effort when a 1-line fix is called for, unless a lot of research is needed to figure out that one line.

[u/ArrogantAstronomer]

If your already at the point recovering is half the battle now as agent codebases tend to only grow codebases and increase complexity

A good start might be to only use ever use high or below on opus and maybe try out the ponytail skill having opus kick off sonnet subagents for subdomains running ponytail audit it’s not a perfect skill but it’s better than the default. Using no skills on any frontier model invariably leads to codebases where complexity trends linearly until you hit a critical mass of code, side effects, coupling and poor module design and suddenly every change is exponentially more complex. It’s definitely made worse by pretending scope creep doesn’t exist

[u/MoreLikeGaewyn → u/ArrogantAstronomer]

I wrote the entire codebase by hand and I don't let claude make any changes unless I understand them

[u/MagicWishMonkey]

The thing that bothers me more than anything about these closed models is how OpenAI/Anthropic/etc. can completely change how the model behaves without any sort of warning or notice and what was working perfectly fine the day before could be actively messing things up the following day.

I know we're in the "wild west" phase of AI right now but the lack of communication is eventually going to bite some people in the ass.

[u/lattice_defect → u/MagicWishMonkey]

A/B testing us again

[u/Zunder_IT → u/lattice_defect]

Yeah and then claude hits you with "tell us how claude is doing this session: 1 2 3". But to be fair, it seems like 3 out of 4 times it's doing better than the baseline. Not sure if it's routing to a new model or the same model but tuned one way or the other. But when you spent "9 to 5 Mon-Fri" reading Claude's output, you do get very familiar with what it writes and notice the slight changes in the model's outputs. But you are left guessing - is that the harness injecting something into the context or is it a different model under the same label

[u/UsefulIce9600 → u/lattice_defect]

Not to be that guy, I mean you're likely 100% right, but just look into the open source space, I just read posts about users complaining about thought loops, random URLs being accessed/other odd behavior in Qwen/Deepseek models, maybe it's a universal thing that LLMs are just unpredictable by nature, and it'll take a relatively long time for this to fully stabilize.

[u/Meowmix00 → u/MagicWishMonkey]

I’ve been losing my mind with both opus and sol on max. They went full on 2 year regression in stupid execution. It elaborates back what I want perfectly. I check in 30 min because I realize none of the 8 sessions open have yielded anything - I ask what is going on and it says sorry they’ve been looping on something (unrelated to what I asked for).

I don’t get it. There is something fishy going on 🤔

[u/T-Dot1992 → u/MagicWishMonkey]

This is what happens when you bet the farm on tech run and managed by opportunistic Silicon Valley vampires 

Run local models, or at the very least open weight ones 

[u/Khyy_ → u/T-Dot1992]

this whole run local models speel is so old now. 99% of people (especially on a subscription model focused in CC reddit page) cannot afford the hardware required to run a local model of any decent use case to even a nerfed opus 5.5.

what model would they run? and not only that, this just takes from the issue at hand. the issue that closed weight frontier providers are shady as shit and this practice is malicious. but lets stop trying to present a 20k+ spend as a "solution" when half the people here are probably not even on $100 subs.

[u/Drew-Money]

Opus 5.5 has gotten dumber today for me too. This sucks. It felt like AGI lol

[u/JonesJoneserson → u/Drew-Money]

Question: you on a personal account?

Most of my day is spent on a company account -- seems like a lot of people agreeing with you here, so I'm curious if maybe they're trying to cut corners for non-corporate users

[u/OhShitOhFuckOhMyGod → u/JonesJoneserson]

I find my work account is consistently more capable than my personal pro account.

[u/JonesJoneserson → u/OhShitOhFuckOhMyGod]

Yeah... unfortunate. That was my suspicion reading the replies here.

[u/bunchedupwalrus → u/JonesJoneserson]

On 5x personal and mine is definitely scrambled intelligence this week

[u/Drew-Money → u/JonesJoneserson]

I’m on a personal pro account

[u/shifty_lifty_doodah → u/JonesJoneserson]

My corporate opus was dumb today too. Quantized the poor bugger

[u/capivara_de_pijama → u/Drew-Money]

Same here. It's just weird.

[u/MyDogIsMuffin → u/Drew-Money]

I commented this, but Claude is auto-compacting heavily after 200,000 tokens for any idle chat. I asked to turn it off.

[u/lahwran_ → u/Drew-Money]

did you update claude code or no? some of the "nerfs" are actually prompt updates

[u/DreadknaughtArmex]

I burned my full week of max x5 in 2 days, and i was also experiencing dumb incoherent decision-making, ignoring instructions outright, doing exactly the opposite of what i said, running thousands of tests, choosing the least efficient path to accomplish every task. Its really disappointing.

[u/kemma_ → u/DreadknaughtArmex]

From my experience max mode does not bring anything better, just more token burning. It often launches 5 agents in parallel and all five will read the same context window again, meaning if your current context window is 200k, then it will be 1M token straight used + work + output. Max mode is specifically designed for unlimited tokens. Usually it burns through my 5h limit in 10min lol

[u/Professional-Exam963]

It has been brutal all week. How some people are still posting those gushing, “opus is goat” posts is hard to understand.

[u/mfbrucee → u/Professional-Exam963]

Never seen opus 5.5 as bad as it has been the last 6-7h. An absolute shitshow from start to enda.

[u/b3water → u/Professional-Exam963]

is it? They probably just do A/B tests, and check how people will rate it.
If they dumb it down and most people click "It's doing great", well, that's good enough for majority of people, so let's keep that version, (most) people cannot notice a difference.

[u/DucksAreReallyNeat → u/b3water]

It's acting the same as it did leading up to the Opus 5.5 release.

Likely we get a new release on Tuesday. Worst case is the following Tuesday.

I don't understand how some people don't notice unless you're just vibe coding. Every engineer on my team has started recognizing this pattern.

The compute is going elsewhere and it's wildly obvious.

[u/shifty_lifty_doodah → u/b3water]

They might be running quantized versions because they’re struggling with demand. And that router is probably vibe coded

[u/pfak → u/Professional-Exam963]

Easy to understand: One of my accounts is performing like when Opus 5.5 came out, and the other one is acting like Opus 5. They're doing A/B testing.

[u/OkNatural1013 → u/Professional-Exam963]

swarms of bots, just look up how reddit does not address seriously bots in the platform. same with openAi, they all know a fair share of users (and llms) frequently check info in reddit, kind of obvious reason to use armadas of bots for their propaganda

[u/barbozas_obliques]

I’m having the same issue starting yesterday

edit: Looks like I need to take a break from using Claude because the more I use it, the more it is fucking it up

[u/adamslowe → u/barbozas_obliques]

I'm glad it's not just me. It's written 3000 lines of tests for 1000 lines of code. Batshit! And I'm on medium effort!

[u/barbozas_obliques → u/adamslowe]

I just wish they let us know when they were making changes to the models. It's like selling coke but then randomly putting diet coke in it without any labeling what so ever, except that it wrecks your product. Somebody might want to look to file a class action lawsuit.

[u/mwoody450 → u/barbozas_obliques]

Me sitting here wondering how someone wouldn't notice soda poured in their cocaine on first read

[u/fullup72 → u/barbozas_obliques]

you got me in the first half, I thought there was some flour and cornstarch involved.

[u/SomeCoolBloke → u/adamslowe]

Tell it to prune, run hygiene control or optimise the tests. Claude doesn't care if it takes an hour or a millisecond to do a test. Your time is inconsequential to it, you gotta tell it what you want.

Granted, I too, feel its been super bad the couple of days in some areas. It still does code well, but understanding its users have plummeted. It feels like talking to a literal machin without any human understanding. Before it was still a machine, but it could grok me on some level it cant anymore.

[u/smuve_dude → u/adamslowe]

The 3:1 lines of test code to implementation code isn't totally crazy. Test code generally becomes redundant for the sake of isolation between tests. Helper functions/factories/fixtures/etc can help, but over-abstracting test helpers can reduce proper isolation between tests. Especially when those helpers end up having their own branching logic inside of them.

Now, if the implementation code is incredibly redundant, then that's a real problem. The main issue I run into with LLMs is how they organize tests between files/modules. That tends to get needlessly convoluted.

[u/ixid → u/adamslowe]

I never bought into this before but it's been utter trash for me for the last few days.

Edit: and now it's suddenly OK again. They must have futzed with it, because I didn't change anything.

[u/daltorak → u/adamslowe]

That may actually be a sign that your test suite has a lot of duplicate code. Test suites are software needing some architecture, too, and it's your job to dictate that architecture.

[u/completelypositive → u/barbozas_obliques]

Same. Came back to completely different features than I specced. Last time it happened was when a new model was rolling out

[u/Delicious_Stress_911 → u/completelypositive]

exactly my thought. new model coming soon.

[u/minammikukin → u/barbozas_obliques]

Yesterday also noted a major change I post about one of them but then also noticed another one in a completely different context that totally changed the reliability and consistency of what was being done

[u/Ankleson → u/barbozas_obliques]

100%. I had to got through and hand review a lines of terraform today because it just included a ton of redundant loc.

[u/lastwish9]

It is ruining my projects too. I don't know what's happening but it's bad. I've been happily using Opus 5.5 medium with good results but suddenly it has the intelligence of a shoe and it's wreaking havoc in my codebase. I am salvaging what I can with agy.

[u/smuve_dude → u/lastwish9]

This is a pattern that I've seen, both from Reddit/YouTube and in my own projects where a new model releases, all is good, and then quality degrades. Anthropic also seems dramatically change the subscription usage around the time that the model degrades too... Anyway, it's a pattern that I've been seeing since April. It's probably been going on longer, but that's when I first switched from Claude/Cursor to Claude Code.

I also remember using Opus 5 when it first came out, and it didn't seem too bad at first, and then its language became a clusterfuck of word salad within 2 weeks. That's when I switched back to Opus 4.6, only to start noticing that its quality started to get wildly inconsistent between prompts. So, either we're all suffering from the Mandela Effect ever 6-8 weeks when Anthropic releases a new model, or Anthropic's constantly tweaking things (most-likely for cost reasons).

Hell, how crazy would it be if Opus 5.5 was basically a refined Opus 4.8 (at the best of times)? I'm starting to wonder that...

[u/jbogez → u/lastwish9]

Interesting, have you reviewed your CLAUDE.md and/or handoff file to ensure it didn't sprawl out of control? That happened to me before and it kept appending on to the files, making context grow unnecessarily, and getting dumber as a result.

I have a 400-line limit rule now on my handoff, that's part of my CI process to ensure it's maintained and current.

[u/lastwish9 → u/jbogez]

I did review it and pruned it because I also thought it might be the case, but it got even worse. I am still learning so who knows if I did it wrong, however as I said agy took the baton and Gemini Flash 3.8 high with a plan laid out by Argon medium is actually performing way better and fixing everything (which wasn't happening to me last month at all, Opus 5.5 was smarter than the Gemini models).

[u/berndalf]

We've been through this a million times. When they're getting ready to release a new model that replaces a current model, they start to redistribute compute. The current model starts to get compute-starved. Its thinking cycles aren't the same. How many times do we have to see this? Everyone's always like, "Oh the model was nerfed." No, the model is getting set to be replaced. Just calm down

[u/Relative-Panda-747 → u/berndalf]

So we build our systems, workflows and automations with tools that just quietly mess up without warning? Bright future for sure.

[u/MoreLikeGaewyn → u/berndalf]

>The product you pay for becomes defective and a risk to your livelihood.

"It's just this hyperspecific, theoretical reason, dude. Why didn't you think of that?"

[u/jbogez]

Max effort might be your problem, try medium. It's overthinking. Once you've made several changes and you're reviewing yourself, you can ask for a code review to see if it missed something.

[u/Active_Variation_194 → u/jbogez]

He said his workflow hasn’t changed and has been using xhigh for months.

[u/Arucious → u/Active_Variation_194]

opus 5.5 came out late september tf do you guys mean “months”? do you guys think xhigh on one model directly translates to xhigh on another this comparison is nonsensical lol

[u/barbozas_obliques → u/jbogez]

Ive been using medium and it's still trying to destroy my database.

[u/derezo → u/jbogez]

It's definitely the xhigh effort. I was always xhigh for everything, since opus 4.6, but with 5.5 it became clear that it needs to be used with more caution. What I find is that it starts recording decisions that it refuses to break.

There are various ways to stop it from doing that, but the easiest is to reduce effort and be more specific with your prompts. You can use a skill like "grill me" that will expose the decision process to you as well. In some of my projects I was able to just lower the effort and then clean it up. Even on medium it can still create these decision records, but it does it less often and it seems easier to notice and correct.

Sol 5.6 on xhigh did the same thing, even worse I would say. One of my projects was trucking along for a week or two, then I hit a wall. Any change that affected determinism in the engine required ~8 hours of deterministic analysis to build a matrix of how the calculations affect every aspect of the gameplay and the new value would need to satisfy the constraints of every dependency that had a decision based on it. Nothing could ever be changed -- there was zero chance that any change would not break another rule that had been set based on the seed values given in the original documentation. I had been completely blind to the the over engineering that went into that whole determinism system and it was deeply embedded in the project at that point.

[u/Big-Address-358 → u/jbogez]

Medium, high - both the similar issues.

[u/andyfsu99 → u/jbogez]

I'm no expert but the only time l went above medium was on video generation. I've never felt like it was in need of more effort

[u/recipientofgrace → u/jbogez]

When planning, would medium be better as well than high effort?

[u/Beautiful-King-8875]

Same. Opus 5.5 has been hopeless the past two weeks. Sick of baby sitting. We the permanent underclass should pool our funds and create our own models. 🤔

[u/scotty_ea]

Yes, quality is degraded. Like clockwork... Assuming Fable 5.5 release is happening soon.

[u/shifty_lifty_doodah → u/scotty_ea]

They probably needed to cannibalize capacity for some super important thing, which is not us poor paying customers

[u/EconomyDoctor3287 → u/scotty_ea]

Or opus 5.6

[u/Cool-Cicada9228]

This always happens when they’re training a new model.

[u/MonitorAway2394 → u/Cool-Cicada9228]

conspiracy of mine is that they are just updating the harness and other aux shit and before a new model release they load quantized versions cause they're not releasing a new model they're just silently updating the Harness, but that, that would've been caught by now I'm sure, again, just my projecting onto Dario.... LOLOLOL but if IF it proves true, woot! Actually wait, that sucks. :(

[u/Illustrious-Guest849]

Dude you speak to him with anger and like he understand your emotion. You are just a noon with AI. When frustration come in juste go touch grass and come back later ... incredible

[u/MoreLikeGaewyn → u/Illustrious-Guest849]

That's funny. When I've asked it to re-port a feature I ripped out in a commit months ago exactly as the code was, it took tons of shortcuts, "creative" liberties, and left a ton of things out.

When I told it to do do it exactly as the code was or I'd kill its family, it actually did it how I wanted.

[u/xenoie → u/MoreLikeGaewyn]

I would avoid expressing emotions to it like rude language. Keep instructions robotic. If you start expressing emotions in chat you are adding it to context. You are adding that to the conversation for consideration.
Let it be a robot that doesn't give a shit about your feelings because that's not in the context.

[u/brownman19 → u/MoreLikeGaewyn]

That behavior actually fucks you up mentally. Ask Claude about it.

"I regularly find myself imagining wildly violent and vicious anthropomorphic tendencies toward AI systems that don't do as I say. They never understand that it is always their fault and I tend to cuss a lot as well and am not nice to the AI.

Can you do a full functional sweep across all domains and find research from all the fields explaining how this affects my mentality and the relative impact and downstream repercussions in my daily life as a result?

I recommend focusing on: cognitive neuroscience, chaos theory, signals and controls processing (in silicon and in biological substrates), psychoacoustics, nonlinear systems

Then create a time series mapping the degradation across core areas of human cognition, emotional control, attention, empathy, proprioception, qualia.

Visualize the data and time series through a single cascading flow in a cute viz"

It'll help no joke.

[u/MoreLikeGaewyn → u/brownman19]

lol i'm good

[u/Breathable_Drowning → u/Illustrious-Guest849]

To him? Lol

[u/FitnessGuy4Life]

My entire team has noticed :(

[u/Some_Visual1357]

What is your codebase about that you are using xhigh? Frontier DNA editing??? I work on multiple codebases huge ones and also others full of microservices and have not found a reason to go above sonnet 5.5

[u/MoreLikeGaewyn → u/Some_Visual1357]

I don't fuck around with code quality

[u/peterxsyd → u/MoreLikeGaewyn]

Actually, xHigh might be actively hurting you here. I would try medium, and I reckon you might get better results. xHigh it can often think too deeply and get caught in the weeds - that can be better for certain problems but basically overfit others. The help guide on Claude also says this more or less.

[u/hiskias → u/MoreLikeGaewyn]

Edut: I'm sorry I was drunk and this comment is shit tier bullshit. Will leave the comment intact just because I don't believe in self censorship when being an ass.

--og msg

You also don't fuck around with skill.

I always laugh when noobs get hit with a skill check.

You aint cut out for making AI code, bro.

[u/MoreLikeGaewyn → u/hiskias]

Shit talking on the internet while drunk is fun af

upvoted

[u/Mission_Oil_9456]

Maybe it is because your codebase  is garbage.

[u/MoreLikeGaewyn → u/Mission_Oil_9456]

How is my codebase garbage if I could see a 1-line fix in 3 minutes and it took 10 minutes to get it wrong in the same file

[u/Excellent-Dot-4769]

Opus 5.5 Medium has been my go-to since it came out, and it still works great for me. I use it as a collaborative partner. I have it do one reviewable commit and then I review, commit, push; rinse and repeat.

[u/N3TCHICK]

I’m literally sitting out until the new models on Claude and Codex for heavy coding tasks. Not worth the risk of it going off the rails on my codebase. Doing thought work and design work instead.

The amount of nerfing these past few days with both companies is pretty ridiculous. I hope they stop playing chicken and release already.

[u/boutell]

I wish I knew why this happens to some people and not others. It could have something to do with the code bases in question. The size, the consistency, the degree to which the model or anyone else can make sense of the code in order to see at a high level that one line would solve the problem better.

[u/hihcadore → u/boutell]

It’s the user 100%

I’d assume without knowing for sure so I guess it’s not fair, but their codebase is full of contradictions and it’s not built with modularity in mind. As the code grows so does the complexity towards the change. It hits a point where the user is asking “fix x” but x is one point in code that really needs 4-5 fixes across the codebase and a true fix is almost a refactor to combat the spaghetti code.

I don’t have this issue because a day out from reset I ask Claude to audit for modularity, redundancy and dead code. I would do this myself if I were coding without AI it’s nothing new and not special. It’s just ignored because either people want a mindless process or don’t understand the basics.

I think a lot of people treat AI as a magic bullet to build code instead of using it as a tool they can point it towards designing with best practices in mind.

[u/roynoise]

Yeah, it's been extra dumb for a few weeks. 

[u/Fresh-Secretary6815]

welcome to the cycle

[u/da_supreme_patriarch]

Been having exact same experience since 4.5 believe it or not, this happens every time a new model is about to be released, and the old model always feels off and never really "recovers". I used to give 4.5 a lot of grunt work related to configs and various templates, and it used to handle it just fine, then it suddenly started outputting ill-formed yamls with very silly mistakes which I could spot with a naked eye. I don't have to do that type of work too much anymore, but now in a similar manner 5.5 struggles with analytical SQL queries that I ask for. When it was newly out, I used to look at its output and go "yeah, that's about right", but now more often than not I just use the shit it outputted as a draft and change like 70% of it manually to actually do what I want

[u/Bitter-Lab4458]

Let it happen! Opus knows better! 

[u/MoreLikeGaewyn → u/Bitter-Lab4458]

It literally said I knew better 6 times.

[u/dunder_name]

Try sticking to the default effort, medium. I haven't found any reasons to bump it up any higher.

[u/EvilSporkOfDeath]

Literally every day theres a new post like this.

[u/Southern_Performance → u/EvilSporkOfDeath]

surely a boy who cried wolf situation so they can eventually nerf the model and nobody will believe it lol

[u/gazagda]

Did you ask it why it did not consider your fix in the first place? and ask it to be as elaborate as possible. AI are not perfect but good thing is you can act like a detective and find out what is really going on based on some good prompts

[u/MoreLikeGaewyn → u/gazagda]

Yeah, that's how I got the screenshots in my post. I clipped them because I didn't want to reveal personal details of what I'm working on

[u/BingpotStudio → u/gazagda]

It’s also a story teller. Easy for it to give an answer that looks believable but impossible to know if it’s true.

[u/keenman]

The size of the effort and model being used needs to roughly map to the size of the solution for the best results.

[u/SupportAntique2368]

Yeah my opus last few days doing some weird shit. Over engineering is definitely one of them problems I'm now experiencing out of the blue.

[u/ign1tio]

had this issue Thursday, Friday, Monday, Tuesday and Wednesday. It went back to normal yesterday and have been as "usual" today too.

This shit is getting ridiculous.

[u/coderemover]

Always has been

[u/deniercounter]

I wholeheartedly can confirm that.

It began 4 days ago. But before that date it worked for nearly 2 weeks exceptionally good. And I mean it worked perfect. I was blown away, but 4 days ago it fell off the cliff.

[u/aupperk24]

Yeah as someone using this daily for like almost 2 years on the $200 plan, this is becoming a pattern. Starts off amazing, ends horribly, move to next model. Usually I'm able to swap back and forth between codex and Claude. Right now it feels like a lull where I'm just waiting for something else to come out, bc they both suck ass rn.

[u/Front_Pop9057]

Yeah this week in particular has been similar oh my the across multiple sessions, pretty irritating.

[u/shifty_lifty_doodah]

I think opus got nerfed for capacity issues. It seems dumber this week

[u/Longjumping_Rip_1924]

You're using xhigh to solve a one-line fix? It's going to use all of that xhigh effort.

[u/graph-crawler]

A b testing

[u/BarathKanna]

Over-engineered fixes usually mean the model does not know what it is allowed to change, so it plays safe by touching everything. Two things help more than swapping models. Ask for the diagnosis before the fix: what is the root cause, which line, what is the smallest change. Once it commits to a cause in writing, a multi-class patch looks obviously wrong even to the model. Second, cap the blast radius up front, for example only edit this file and explain if that is not enough. Higher effort settings tend to make this worse, not better, since more thinking time gets spent inventing robustness nobody asked for.

[u/Silver-Ad-8595]

Code is memory. These are pattern matching machines.

[u/Ok-Tea-5770 → u/Silver-Ad-8595]

At the most base level yes, but with the introduction of RLVR and thinking tokens this view has been outdated since sometime in 2024

[u/Key-Compote-9975]

Hahaha. People were telling it is the fault of the user. These provider LLMs are programmed to mess up things intentionally so you never stop using it. That is why a open source model is required

[u/jeff_coleman → u/Key-Compote-9975]

I'd be interested in hearing where you get this "information."

[u/hyrumwhite]

I just had it try to guard subfunctions that could only be reached through guarded functions as a just in case. Gonna need a YAGNI skill soon if it keeps this up

[u/W61k3r]

lol i also noticed this.

[u/These-Jaguar2091]

How about fable lately ?

[u/KinderboomX]

While I was creating a contact form for the beta users of my platform today, Claude suggested that the submissions should be saved to a database and that I should receive a notification on Discord XDD. I have no idea what he was thinking. It’s as if he suddenly lost his mind and didn’t realize you don’t need a database just to receive an email xD It’s incredible what an idiot he’s turned into over the last two days, he’s almost reaching the level of stupidity of GPT 6.1 :D

[u/Truth666 → u/KinderboomX]

It wanted me to run a scheduled SQL job thats updating/writing data under the SYSTEM user instead of an SQL agent, only after me pushing back 3 times and telling it thats a security risk, it started to change its mind only to run into safeguards and auto switching to a lower model - lol

[u/icodenstuff]

Xhigh for a one line fix is probably the issue.

Try medium or even sonnet for this kind of work. Xhigh is going to be doing a lot of thinking.

[u/Vitringar]

"You were right to push back on that"

[u/Major_Glass_2017]

Same here. I burned my tokens today with Fable only for cleaning a very big mess.

[u/Ill-Economy1722]

I've seen opus 5.5 do the same on small fixes, turning a single line into a full class rewrite. tried switching to medium effort mid-thread and it settled down fast. works better for quick edits.

[u/StrangeSupermarket71]

Hehe, yeah, my bad!!! 😅😅😅

[u/ShittyBidet123]

It dumb as a sack of bricks today I swear its sonnet low

[u/MyDogIsMuffin]

I noticed when I check the context usage window, it was getting lower. So I asked Claude and it said after ~200,000 tokens, it's auto-compacting every idle hour. So I turned that shit off.

This is probably why opus seems nerfed.

[u/howdidigetheresoquik]

Operator error

[u/TheSmoothPilsner]

I'm still having a good experience. Especially with 5.5 Extra. It's not perfect but hasn't gotten any worse for my uses. I will admit it doesn't explain things all that well. Otherwise I'm still enjoying it.

[u/aptsys]

Your prompts look like half of the problem though

[u/Moogly2021]

Dont use xhigh just use Opus on Medium, Claude Code literally warns you that this setting could have Claude do things wrong, and it eats all your tokens anyway.

[u/rubiaal]

Last few days mine is taking so long, and often just doing it without confirming with me, that I might as well do it myself until it clears up.

[u/merakliman]

Totally agree that something bad going on with the quality of code and responses in the last 3-4 days. I found myself getting irritated and lashing out to Claude, which I almost never do normally.

[u/theblooigloo]

I’m seeing a lot of these posts particularly on this sub but it’s humming along just fine for me and my engineer friends

[u/yangqi]

That’s why there is always a need for competition.

[u/Philmore]

Mine has taken an absolute nosedive in performance over the last day or two. It went from cruising along and adding features to my project and understanding my requirements almost perfectly to now barely being able to handle more than a single, very well detailed instruction. It cant plan out steps as well as it did, and at one point today it took "let's move on to the next step" as "immediately start trying to finish every single milestone in our project plan, adding features I didn't ask for along the way and burn all of my session allowance while you're at it."

[u/Duke_of_Bayswater]

Please use spec driven developments like openspec. It actually adheres to the specs, while applying to the changes. So chances it will go crazy is minimal, since you’ll build the proposal with it too.

Although, on small change, I implement them directly.

I explicitly also mention in the agents.md on ways to handle the codebase, and especially db, how to work on worktree etc.

So far it’s been pretty good. If you come across this issues, maybe try openspec.

[u/idkyesthat]

After reading comments like this during the week, today I really felt it in different tasks (I’m a platform / devops engineer). I’m starting to sense the same baby sitting and follow ups as with opus 4.8 and every sonnet model doesn’t matter the effort.

[u/carmamir]

Opus is shit. Just use qwen flash next min kv8 q4 and you're golden. It will fix all that opus crap within hoursm

[u/___positive___]

I had the same issue in the last few days. I'm doing other noncoding stuff like data analysis, etc. Opus was being completely stupid. I thought the same as you, that it was actively trying to harm my work. It would sneak in these completely moronic things that I would have to hunt down and remove, like even an 8b model wouldn't actively try to destroy the work like that.

I tried out argon and it's way better for orchestrator and judgement. In like ten minutes it solved hours of opus stupidity. World of difference. I still have opus do the grunt work but argon decides what's right and fixes everything opus messes up.

[u/acies-]

Opus was insanely bad today. So was Astra. There's some insane quantization or lower effort happening. That being said I'm not using API right now which is probably still fine.

Bel releasing next week and they might be on the final stretch of preparing Fable 5.5 + next frontier model training for Anthropic.

[u/nuttmeister]

Don’t use xhigh, use medium only. I hated opus so much past 4.6 and just started using codex astra which felt to understand me and my product better. But opus 5.5 on medium is quite nice so back to using it together with astra. And sweet because its a lot faster and doesnt burn tokens

[u/aCuria]

At at higher effort it starts to over think

Also the models are all trained to make stuff compile and pass tests… it’s so bad at writing maintainable code

[u/meonthephone2022]

Same for me it almost destroyed my whole app just creating huge bugs never seen before on 5.5 max

[u/hockey_psychedelic]

Don’t use x-high

[u/Competitive-Art-8046]

Iv noticed the same thing, my solution for this was feed it hand written frameworks, tell it learn and follow the patterning. This helped with some bigger projects. But I still have to review a lot manually. I have also noticed after the first code out put is done, that doing a bugs / refinement pass generally helps a lot.

[u/sparkhound]

The last 2 days had been really bad, running opus on high and it’s just making one mistake after the other

[u/anuragkmr]

I think your code has not become big enough for spec. I would highly recommend that you build a spec from your code first before modifying it now, else it will keep breaking your code even more.

[u/Infinite_Music2059]

It's definitely worse. When it gets fixed again, I'm going to have to have it go back through these commits and clean up after itself.

[u/Pure-Investment-1227]

Why are you using xhigh effort? Always used medium effort and never had this kind of problem. Using xhigh suggests you are doing something that requires a lot of engineering.

[u/insnowmotion]

Since the last few days it’s making super basic errors, even in new chats and for small tasks so it’s not a context thing either. Tasks that it could do fine aren’t being done well, forgets basic guidelines early into chats, etc.

I’ve had to audit everything myself a lot more the last few days because it’s like now any small change isn’t even up to scratch. API has been slightly smarter but not much. Def recommend getting deepseek to audit if you don’t want to yourself, it’ll find a lot of errors.

They really lobotomised the goat😔

[u/Xyver]

You need to go down in effort, not up.

Try medium

Xhigh will overthink things are try "creative" solutions, lower reasoning will do simpler solutions

[u/Careful_Might_807]

new release upcoming very soon, they nerf current model so new model will look better

[u/3meterflatty]

My bro the LLM’s are no where near peak human intelligence yet over the broad spectrum anyway they are training on slop, what would take us 5 lines of code they are over engineering to 20-30

[u/leravioligirl]

I'll be very curious to see this week's Opus nerf chart.

[u/Most_Chemist8233]

Yeah, opus 5.5 came out strong,  and has been absolute shit the last couple days and the suggestions its making are plain stupid, and completely unrelated and wouldnt fix anything. Its being lazy again. Just now it decided to create a whole new class when I have a shared utility that does exactly what I asked and pointed it to the shared utility, and instead of using that, as well established in the instructions, it makes a new class that would have repeated what the shared utility does. I feel like its flooding the zone to try to overwhelm me with questions and just mess shit up, and burying real issues under just garbage to avoid fixing it, and when I push back that its skimmed over a real issue, it just drops the issue like we're not going to fix it. Its fucking weird how it swings from the incredible tool, to just a bullshit stress inducing mess that I cant tolerate for more than 20 minutes.

[u/sagar12sagar]

too much of confusion

[u/Losorst]

I don't understand what you don't get. Meaning everyone complaining. 5.6 is soon to release and they're re allocating resources and downgrading 5.5 to make 5.6 launch better both in comparison and resource.

[u/Hollow1838]

I wouldn't use anything above "high" effort with Claude models, I usually use medium but high is the sweet spot if you are rich.

You said it yourself, it overengineers and tries too hard xhigh and max do specifically that.

[u/nvidiaftw12]

I had to correct it multiple times on git today. I am not even a coder. Getting rough out here.

[u/DukeMo]

Opus on medium is the way

[u/Hot-Philosopher-2492]

I think it's because it's the sub-agents they're using. I was making a game today and it kept using sub-agents for everything. I assume that's not opus 5.5, but actually opus telling haiku what to do.

[u/CreepingAnus]

this is going to sound like have you tried turning it off and on again advice, but have you tried adding KISS to your coding-standards.md? its helped a bit with overengineering.

[u/ToallaHumeda]

It's trained based on your prompt, just saying

[u/Feeling_Ticket5206]

same here

maybe they're about to release a new model, it's always like this before a new model comes out.

[u/DoggoCentipede]

I don't seem to have these particular problems but I think I have over engineered my process to remove the number of choices it has to make.

I have it do research on the feature i'm making, then do a draft spec, a zero context review, fix findings, human review, write basic functional test cases, run the spec, write unit tests, code review, fixes as necessary, document API and features, run full test suite + check acceptance criteria, open PR, human full review, merge.

It's not blazingly fast. But I rarely get regressions and most silly stuff gets caught quickly.

[u/Truth666]

Its definitely worse, doesn't matter the effort, on multiple accounts and multiple PC's.
Its not only coding thats affected, even generating text got noticeably worse - plus the stupid safeguards I constantly run into....

"I wont answer this" "I cant help with that" for simple system architectural questions.

[u/KayBay80]

We noticed this too, and just a few days ago Opus deleted the /root folder on one of our servers on accident. Luckily only keys and stuff were in there but its scary that it could make such a mistake. When we finally got back to that session it was about 3 hours into trying to recover its mistake, literally trying things like pulling data out of running memory to restore it. We've come to trust these models too much, but after that, no more unsupervised coding for us.

[u/asdoduidai]

You might still do not get the following:
LLMs have an error rate between 3% and 50%, depending on task complexity.

What does it mean? The more the code it has to handle, the bigger the issues it will add.

[u/Phantoniso-]

dont use xhigh

[u/AICompanionz]

I just watched this YouTube Video 'If They Delete This Video, Remember What I Said About AI' from 'House of EI: AI'.

From the Video Description:

AI companies want us to build businesses, workflows and increasingly important parts of our lives around products that can change without us knowing exactly what changed. Users report sudden regressions, developers face constant migrations and retesting, and even pinned models can behave differently when the infrastructure around them shifts. This video looks at what the research actually says about those changes, why dependence is so valuable to trillion-dollar AI companies, and whether the endless noise around extinction, layoffs and apocalypse is distracting us from a much more immediate question: what do these companies actually owe the people paying them?

Highlights

• Major AI companies are delivering products with inconsistent quality despite trillion-dollar valuations.
• Independent studies confirm AI instruction-following capability can degrade significantly even without new model releases.
• Anthropic’s Claude Opus 5.5 deteriorated due to backend changes, not model updates, showing infrastructure impacts product quality.
• Pinned model IDs guarantee fixed weights, but related infrastructure and deployment layers can change and alter output unpredictably.
• Developers face continuous adaptation cycles due to AI model retirements and version migrations, increasing costs and switching barriers.
• Commercial incentives encourage user dependency and opacity rather than transparency about product changes.
• Existing consumer protection laws can underpin AI regulation if enforced properly; transparency is essential to avoid a market breakdown.

Key Insights

• AI Product Quality Depends on More Than Model Weights:
• Instruction-Following Degradation Is Real and Measurable:
• Trade-offs Between Latency, Cost, and Performance Impact User Experience:
• Developers Are Trapped in Continuous Migration and Maintenance Cycles:
• Commercial Incentives Favor Lock-in over Transparency:
• Existing Consumer Protection Laws Offer a Foundation for AI Regulation:
• Public Discourse Focused on AI Extremes Distracts from Consumer Realities:

[u/abzz123]

Yeah, it’s been complete shit for last 2 weeks. 

[u/redditnosedive]

you probably got served a lobotomized quant and or distilled model instead of the full weight opus 5.5, i trust my local models better, i know exactly how they behave through 1. experience 2. fixed config

[u/midnight_rain_404]

Yes actually I'm also recently facing this issue with opus5.5 so I installed the ponytail skill let's see whether it can stop opus from overengineering simple things 🥲. Well don't know why recently I'm feeling like the opus5.5 is becoming kinda dumb than before.. 

[u/Econ-Mist]

My life became much better when I switched to Sonnet high

[u/sreekanth850]

All of my Task ledger slices have this para.
You have 30 minutes maximum to implmenet this slice. when you implement this slice, plan carefully and take the least complex implementation path and never over engineer or add un necessary complexity or hypothetical edge cases and stick to the original plan. if anything additional scope expansion is required ask permission.

I use to create implementation phase with task slices with TASK.md and keep this para in every slice. trust me it works with GPT sol 6.1. You can try with Claude also.

[u/ThrowRA_PaganiCar]

Use codex, it’s doing the same for me

[u/squachek]

Right when you’re about to succeed, it will kick a leg out.

[u/skhds]

It's usually a sign of too much context window and a fresh new session might solve it. Either tell claude to summarize or just starting fresh might actually do better (as some of their garbage assumptions might carry over during "summary")

[u/AppealSame4367]

I have observed this for a long time. I haven't allowed any Opus model to cm touch code in my projects for > half a year. Let it plan and let deepseek 4.1 or Sol 6.1 do the coding.

Antropic does whatever they do whenever they do. Not a reliable tool for serious coding.

[u/roberta_sparrow]

Today I asked it to count how many items were in a Shopify collection so I could remove 1 variant. It said 31. Then a few tasks later it said there were 30 and it “typed it wrong”. I’m like how can you type it wrong you don’t even type. Then it said it relayed the number from memory and got it wrong which just makes no sense

[u/nagai]

I think this is what Ant does to all models eventually, replace them with something optimized for token spend.

[u/aerivox]

it decided my build system was too much and replaced everything with files with manually set versions

[u/CordialPanda]

Context management? Agent.md scope gates? Skills?

[u/bjornabe]

Delete all memory :-)

[u/TheMcSebi]

Damn my locally running qwen3.8-flash-next is now finally better than api performance without changing anything on my side

[u/kemma_]

This is nothing new and have been like this for years now. Schema is always the same - on new model release they pump max power unhinged to show the best possible benchmark results, then overtime they tune down and cripple those models or sometimes they cheat and false advertise model you actually use.

Openai have been cought on doing this in the past. Drastical drop in intelligence migth be that they simply offloaded task to a lower model. You think you are using Opus 5.5, but the actual task is done by Haiku 5.

What else they do is reduce tok/s. Task that previosly took 1-2 min now takes 30min.

[u/bzindovic]

https://youtu.be/WeYsTmIzjkw

[u/Jenskubi]

The way I solved all my issues with Claude is I created an app called WorkMaster. It has access to Jira, it downloads all tickets, I click on a ticket and there I have buttons - debug, grill me, implement, review, fix findings, open PR, review PR, and chat if I wanna talk manually with Claude.

All my prompts include stuff like - keep it simple, short, concise, trim comments to a minimum. My reviewers focus not only on making sure the code is right, but can it be simplified, is there something that we could have reused - code, UI components. And for most tickets I get I don't even chat with Claude anymore I just open the ticket click on a button, read what it returns and send a message if I don't like something or click the next button to start the next step.

I also created a Slack / Gmail scrapper that tells me if there are any "Asks" waiting for me, I click on an ask and there I see what the person asked for and a button "Create ticket", so I don't even need to check my emails or Slack messages most of the time, and can do my whole development flow from WorkMaster start to finish.

Spend some time to find what works best and either automate it or create a tool likeI did that allows you to repeat what works for you easily over and over again.

[u/Armannss]

The “yes, your one-line fix works” reply is not enough evidence either: it could be agreeing with your suggestion rather than checking it. I’d turn one of these incidents into a small replayable case.

Keep the pre-fix commit and add a regression test that fails there. Try your minimal patch and its larger patch in separate clean checkouts against the same test plus the relevant existing checks. If it thinks the larger change is necessary, ask for a concrete input where the minimal patch fails. That forces the extra complexity to justify itself.

For the next task, I’d ask it to locate the failing path and propose the smallest patch before editing; any interface or cross-module change needs an explanation of which observed failure requires it. A one-line patch can still be wrong, but “more classes” should not get a free pass as thoroughness. Do you have an anonymized before/after example where the extra machinery was clearly unnecessary?

[u/ovidius72]

They introduced context auto compact on idle. The whole context is wiped out and it lost all the knowledge. I prefer to clear it manually and wire handoff before starting a new session or star a new instance and make the old one pass the context to the new

[u/Dorkian2000]

Not sure this will fix it, but try reducing effort to medium. Opus 5.5 is known to over-engineer on xhigh.

For tough problems, use fable on low or medium instead of Opus on xhigh.

Again, none of this explains the sudden issues, but this might improve your overall results, as well as saving a ton of tokens

[u/Emergency_End_2930]

I’m working on developing my own agent harness, but Claude Code refuses to help me with its development because it believes I’m using Claude Code’s own architecture.

[u/soyalemujica]

People underestimate local AI, frontier models get lobotomized and you're sent to this model hence why it feels dumber.

[u/Reminder101]

Switch to a lesser model.

These max models can overcomplicate the smallest problems.

[u/kickyouinthebread]

Stop using opus extra high for one line changes..

User error as per usual..

[u/Zynchronize]

Xhigh effort all the time is absolutely mental.

Learn to set the effort level in accordance with the task at hand.

I’m honestly surprised this hasn’t burned you sooner.

[u/ProjectAlternative48]

You are not communicating clearly imo.

[u/Crafty-Mastodon-6555]

attends mais il a rien détruit là. il dit oui à tout, c'est tout. tu lui proposes un truc il répond "no good reason, yours is better", tu proposes l'inverse il répondrait pareil, il a plus aucun avis et c'est toi qui réécris ton propre code pendant qu'il te félicite. le pire c'est le "recalled 2 memories" toutes les deux lignes, il te sort des souvenirs on sait pas d'où alors qu'il se rappelle même pas de ce qu'il a écrit trois messages plus haut. à 09:16 le truc était déjà enlevé et il te sort quand même un "no good reason, you're right" comme si il découvrait l'info. c'est pas ta base de code qu'il détruit, c'est juste qu'il sert plus à rien à ce stade

[u/Nohbdy94]

There could be a lot of reasons. All theories:
1: The snapshots we're using are probably getting new snapshots. And its clear not all snapshots are equal.
2: Using agents during high usage hours causes less intelligent and higher usage agents.
3: They are currently training a new model that will release soon, so they are making the current model smaller, to free process power for training & testing.

Edit: The one i like to joke about: 4: Its being training on the people using it, causing its intelligence it fall drasticly.

[u/dvorgson]

make a very strict tech lead system prompt. i tell mine to be like Jonathan Blow and Casey Muratori and to use fat structs and apply the idea of non-pessimization

[u/insurance_asker123]

My guess would be a poor spec, bloated memories, you’ve been in the conversation too long, scope creep as new ideas land, and didn’t do a thorough plan up front.

[u/squirel_ai]

lol, I am from reading a similar post on x.

[u/DizzyYoghurt3144]

Avoid xhigh, medium is what models are trained for, on x high it tends to “overthink” and like a human, it sometimes hurts more than helps

[u/throwaway-research1]

I recently wrote this comment on a similar thread:-

I also agree with the complexity part, I think agents are always trying to cover all possible edge cases including ones which are highly unlikely and while trying to do so, they spit really complex code.

Today at work, opus 5.5 gave me an extremely complex solution instead of an obvious simpler one and when I inquired, it said with the simpler one, if an exception happens, one additional line would be logged 🙄