I would really appreciate if folks would give feedback: • False positives (just post verbatim, if you can post an SHA, I can try figuring out why they got flagged) • False negatives (harder to spot, but if you have a human cycle after llm, you know what it didn’t find) • True positives (mostly to confirm this is actually useful) This way I can further fine tune and improve.
On Tue, Jun 9, 2026, at 5:41 PM, Štefan Miklošovič wrote: > Thanks Alex for the latest update on your branch! I have merged it > (CASSANDRA-21373). > > David, would you mind driving that PR of yours to the merge? That > looks very handy as well. > > On Fri, Jun 5, 2026 at 12:22 PM Štefan Miklošovič > <[email protected]> wrote: > > > > I am going to merge the PR of Alex next week. Whole week no progress / > > changes so lets merge what we have. > > > > On Thu, May 28, 2026 at 10:38 AM Štefan Miklošovič > > <[email protected]> wrote: > > > > > > Hi Alex, > > > > > > Has the situation around your skills improved in relation to what you > > > have described or can we move forward with it already? > > > > > > I think it is better to have something in rather than trying to > > > perfect it on the first merge. The skills are useful as they are > > > already and they can be calibrated in the future. > > > > > > Regards > > > > > > On Fri, May 15, 2026 at 6:58 PM Alex Petrov <[email protected]> wrote: > > > > > > > > It performs poorly on larger patches, so I was trying to chunk it. I > > > > was also experimenting with reverse checklists: you generate a review > > > > checklist per patch and take skill as an input inspiration. Kind of > > > > semgrep rules but you encode them verbally. > > > > > > > > On Fri, May 15, 2026, at 4:37 PM, Maxim Muzafarov wrote: > > > > > > > > As for large patches used to test new skills, I think the “CEP-38: CQL > > > > Management API” PR ( https://github.com/apache/cassandra/pull/4582 ) > > > > could be a good playground to validate the relevance and accuracy of > > > > the suggestions provided by the deep-review and patch-explainer > > > > skills. > > > > > > > > (By the way, we still need a reviewer to move this patch forward.) > > > > > > > > I used patch-explainer to generate a description. This is what it looks > > > > like: > > > > https://github.com/Mmuzaf/cassandra/blob/cassandra-19476-bug-hunting/CASSANDRA-19476-PR-DESCRIPTION.md > > > > > > > > Thoughts, > > > > > > > > I think it would be useful to explicitly mention a strategy to split > > > > large patches into some reviewable parts, for example by logically > > > > separating them by component. There is already a “Skip or minimize” > > > > section, but it does not mention breaking large patches into blocks > > > > (if it's possible). The skill currently does not mention trade-offs, > > > > although during implementation I constantly kept them in mind and even > > > > tracked them separately in my notes for each critical section. For > > > > example, what is actually preferable: issuing a direct command QUERY > > > > request or invoking pre-registered prepared statements? > > > > > > > > I also experimented with Mermaid diagrams (1) instead of ASCII > > > > diagrams. This is how they could look (2) and looks better than the > > > > text, although I noticed they tend to be less accurate. > > > > > > > > > > > > I also tested deep-review, and although I had already used Claude to > > > > review my changes, it still highlighted several issues that need to be > > > > fixed: > > > > https://github.com/Mmuzaf/cassandra/blob/cassandra-19476-bug-hunting/CEP-38_DEEP_REVIEW.md > > > > > > > > Overall, I think it’s good. > > > > Could you share any deficiencies you’ve spotted, Alex? > > > > > > > > > > > > [1] https://de.wikipedia.org/wiki/Mermaid_(Software) > > > > [2] > > > > https://github.com/Mmuzaf/cassandra/blob/cassandra-19476-bug-hunting/CASSANDRA-19476-PR-DESCRIPTION-MERMAID.md > > > > > > > > > > > > On Fri, 15 May 2026 at 09:18, Alex Petrov <[email protected]> wrote: > > > > > > > > > > I have spotted some deficiencies, particularly when reviewing large > > > > > patches. I have an experiment running that might improve the > > > > > situation. I’ll report as soon I have a result. > > > > > > > > > > On Thu, May 14, 2026, at 12:31 PM, Štefan Miklošovič wrote: > > > > > > > > > > I just merged (1) and created (2) for tracking the patch of Alex. (1) > > > > > and (2) don't collide. > > > > > > > > > > It would be cool to include this (2) in upcoming weeks, let's just > > > > > live with what Alex provided for a while to evaluate that set of > > > > > skills. If the general vibe is OK I would approach the merge. Let's > > > > > give it what ... few weeks? Until the end of the month at least. > > > > > > > > > > (1) https://issues.apache.org/jira/browse/CASSANDRA-21301 > > > > > (2) https://issues.apache.org/jira/browse/CASSANDRA-21373 > > > > > > > > > > On Mon, May 11, 2026 at 3:21 PM Štefan Miklošovič > > > > > <[email protected]> wrote: > > > > > > > > > > BTW I really appreciate TLA+ machinery in that patch, I let it scan > > > > > compression dictionaries code and how we disperse notifications > > > > > around the cluster when a dict is trained etc. and it spit out stuff > > > > > like this. There is an IDEA plugin for TLA+ I ran it in and it just > > > > > worked and verified :) I can imagine these specs might be > > > > > theoretically something we commit into the repo as well when > > > > > applicable. That way we would at least conceptually codify the > > > > > protocols and could elaborate on them on a high level and run some > > > > > formal verifications etc ... Really appreciate this aspect of it. > > > > > > > > > > (1) > > > > > https://gist.github.com/smiklosovic/24b4db51f9ee2b64d76cb0bbb104e29a > > > > > > > > > > On Mon, May 11, 2026 at 11:31 AM C. Scott Andreas > > > > > <[email protected]> wrote: > > > > > > > > > > Alex - thanks so much for putting this together and sharing. > > > > > > > > > > Here are three additional data loss / corruption bugs identified by > > > > > Arjun Ashok using this set of skills last week: > > > > > > > > > > – https://issues.apache.org/jira/browse/CASSANDRA-21356: > > > > > CursorBasedCompaction: ReusableLivenessInfo.isExpiring() incorrectly > > > > > returns true for tombstone cells, corrupting cursor-compacted SSTable > > > > > format and cell reconciliation > > > > > – https://issues.apache.org/jira/browse/CASSANDRA-21357: > > > > > CursorBasedCompaction: prevUnfilteredSize always written as 0 in > > > > > SSTableCursorWriter > > > > > – https://issues.apache.org/jira/browse/CASSANDRA-21358: > > > > > CursorBasedCompaction: Final index block width off by one byte in > > > > > SSTableCursorWriter#appendBIGIndex() > > > > > > > > > > Stepping back a bit -- > > > > > > > > > > This set of skills combined with the Opus model have enabled folks to > > > > > find 14 data loss, corruption, and correctness bugs in the project in > > > > > the past ~two weeks. These are bugs that likely would have gone > > > > > undetected - and if encountered in the wild, would have required > > > > > extensive manual fuzz testing to reproduce and identify. > > > > > > > > > > In the case of the the issue that I'd found and reported: > > > > > https://issues.apache.org/jira/browse/CASSANDRA-21340: GROUP BY > > > > > queries silently return incomplete results due to premature SRP abort > > > > > > > > > > I found this by invoking the skill with the prompt "Review > > > > > Cassandra's implementation of GROUP BY for correctness. Identify edge > > > > > cases that might result in incorrect responses. After identifying > > > > > candidate bugs, fan out subagents to write unit tests and fuzz tests > > > > > attempting to reproduce them. Assess their veracity, and present them > > > > > in order of concern." > > > > > > > > > > In less than 30 minutes while sitting on the sofa, the model and > > > > > skill identified CASSANDRA-21340. In another hour, I was able to > > > > > establish its veracity, then leave the model and prompt behind to > > > > > work through the issue and write up the Jira ticket by hand. > > > > > > > > > > I'm *really* impressed by what this set of skills enable, and I think > > > > > they may be transformative for quality in Apache Cassandra – > > > > > especially when combined with the ability to write in-JVM dtests; > > > > > Harry tests; and to use the Simulator. These also make it a lot > > > > > easier to use each of these tools. > > > > > > > > > > Here's how I'm thinking about this work so far: > > > > > > > > > > – The ensemble review skills are a great first-pass review that can > > > > > be used by anyone preparing a patch to identify potential issues. > > > > > – They're incredible for pointing at existing and/or new + > > > > > experimental components in Cassandra to find serious correctness > > > > > issues. > > > > > – I'm sure we'd find latent issues if we directed the skills at > > > > > interaction between multiple components, like "range tombstones x > > > > > short read protection x reverse reads x compact storage" (etc). > > > > > – I think these skills could be generalized to support bug-finding > > > > > and validation in other Apache projects. > > > > > – I also think there is a generalization of these skills that could > > > > > be applied to CPU + allocation profiling and optimization. > > > > > > > > > > For those who have access to a suitable model, I'd love to hear your > > > > > experience attempting to find a latent bug in the database. > > > > > > > > > > I was shocked how easy it was, and am hopeful for what this might do > > > > > for quality and data integrity in the project. > > > > > > > > > > – Scott > > > > > > > > > > On May 8, 2026, at 5:22 PM, Alex Petrov <[email protected]> wrote: > > > > > > > > > > > > > > > I would recommend Opus 4.6+ for /deep-review, but /shallow-review is > > > > > probably fine with sonnet. > > > > > > > > > > Maybe time permitting, I can do evals for different models at some > > > > > point. > > > > > > > > > > Review process is always a bottleneck and introducing such skills > > > > > should help to make it faster and more reliable. > > > > > > > > > > This is hope here, but this is also just a start: we need to reduce > > > > > false-positives, and do more with specifications (P, TLA+) for > > > > > critical parts of code. > > > > > > > > > > On Fri, May 8, 2026, at 5:56 PM, Dmitry Konstantinov wrote: > > > > > > > > > > Hi, Alex, thank you a lot for sharing it. I have been using Claude > > > > > code for review of my changes but in a very basic ad-hoc way, it > > > > > works for simple issues. The skills look much much more powerful. I > > > > > am going to read and try them in the upcoming weeks. > > > > > Review process is always a bottleneck and introducing such skills > > > > > should help to make it faster and more reliable. > > > > > > > > > > A question: what model(s) do you use to run them? Is Sonet 4.6 enough? > > > > > > > > > > Thanks, > > > > > Dmitry > > > > > > > > > > On Fri, 8 May 2026 at 14:03, Alex Petrov <[email protected]> wrote: > > > > > > > > > > > > > > > Hello folks, > > > > > > > > > > We have been working on some tooling [1] around Apache Cassandra > > > > > correctness, and wanted to share it with Cassandra community. > > > > > > > > > > We have approached this by "indexing" ~3k Cassandra issues and > > > > > extracting common patterns from them, generalizing them, then running > > > > > evals, tweaking, and extending them until we were had a strong signal > > > > > that it performs better than the run-of-the mill code review skill. > > > > > We have benchmarked it against some popular OSS skills (by presenting > > > > > bugs we knew existed from "indexing" Apache Kafka, inferring commit > > > > > bug source from the fix, and making sure benchmarked skills actually > > > > > find it). > > > > > > > > > > In addition, I did my best to codify some things I knew about > > > > > correctness, researching code, and writing repros, and what I could > > > > > find in research papers and public blog posts. > > > > > > > > > > So far we were able to find (at very least) following issues (in > > > > > reality the number is higher but I have a backlog of potential leads > > > > > to investigate and reproduce longer than the time I have available > > > > > for these pursuits). > > > > > > > > > > deep review + fuzzer: > > > > > > > > > > CASSANDRA-21307: Lower bound [SSTABLE_UPPER_BOUND(row000063)] is > > > > > bigger than first returned value > > > > > CASSANDRA-21292: Row re-inserted at the exact start of a range > > > > > tombstone disappears after major compaction > > > > > CASSANDRA-21255: Differentiate between legitimate cases where the > > > > > first entry is the same as the last entry and empty bounds in > > > > > SSTableCursorWriter#addIndexBlock() > > > > > > > > > > shallow + deep review: > > > > > > > > > > (latent) issue of unused keepFrom in linearSubtract > > > > > https://github.com/apache/cassandra-accord/pull/272 > > > > > CASSANDRA-21336: CursorBasedCompaction: trailing present columns are > > > > > silently dropped in encodeLargeColumnsSubset() > > > > > CASSANDRA-21340: GROUP BY queries silently return incomplete results > > > > > due to premature SRP abort > > > > > CASSANDRA-21352 TCM: AtomicLongBackedProcessor sort inversion > > > > > CASSANDRA-21353 putShortVolatile is not volatile in InMemoryTrie > > > > > > > > > > Via specifications: > > > > > > > > > > CASSANDRA-21337: Difference in behavior between Cursor-Based > > > > > compaction and "Regular" compaction > > > > > CASSANDRA-21336: CursorBasedCompaction: trailing present columns are > > > > > silently dropped in encodeLargeColumnsSubset() > > > > > CASSANDRA-21339: CursorBasedCompaction: expiring cells, same > > > > > timestamp, same ldt, different ttl > > > > > CASSANDRA-21338: value comparison direction reversed in > > > > > CursorCompactor > > > > > > > > > > A few folks were using this skill to test some of subsystems, and > > > > > might report more issues that I am not directly attributing here. I > > > > > have also used these skills for self-review and have caught a couple > > > > > of issues before they made it into the codebase. > > > > > > > > > > Despite some early success, I still consider this a very raw set of > > > > > prompts, but I think this has utility, and based on the success we > > > > > have seen so far, can be helpful and is (according to my measurement > > > > > methodology) fairing better than one-shot code review prompts that an > > > > > LLM would generate by user request. > > > > > > > > > > Since I was focusing on finding issues, running evals, and trying > > > > > several other methodologies that did not make into this version/cut, > > > > > I did not have a chance to sit and re-read the entire final result > > > > > just yet, which is why I am not suggesting merging this into > > > > > Cassandra codebase until we better vet it, but with your help and > > > > > feedback maybe we can do this quicker. > > > > > > > > > > Hope you find this useful, please share your opinion, experience, and > > > > > criticism. > > > > > > > > > > Happy bug hunting! > > > > > --Alex > > > > > > > > > > [1] https://github.com/apache/cassandra/pull/4794 > > > > > > > > > > > > > > > On Mon, Apr 13, 2026, at 1:12 PM, Štefan Miklošovič wrote: > > > > > > > > > > I noticed this PR just landed. > > > > > > > > > > Volunteers reviewing / improving greatly appreciated! > > > > > > > > > > (1) https://github.com/apache/cassandra/pull/4734 > > > > > > > > > > On Thu, Feb 26, 2026 at 5:43 PM Jon Haddad <[email protected]> > > > > > wrote: > > > > > > > > > > I wanted to share a couple of other things I thought of. I wrote > > > > > this: > > > > > > > > > > > C*'s technical debt will make using an agent in the codebase much > > > > > > harder than using one in my own > > > > > > > > > > I want to clarify my intent with this statement. I was trying to > > > > > convey that I've had the luxury of refactoring my code several times, > > > > > because I don't have to worry about messing with other people's > > > > > branches. I usually write something, use it briefly, find its > > > > > faults, redo it, and iterate several times. I never consider > > > > > anything done and am always looking to improve. This is very > > > > > difficult with a project involving many people who have in-flight > > > > > branches spanning several months. Changes I consider no-brainers > > > > > might be a headache for C*. For example, I can just add a code > > > > > formatter and rewrite every file in the codebase. I make major > > > > > changes regularly without any consequences. Here, it impacts dozens > > > > > of people. I proactively improve my code's architecture because > > > > > there are few, if any, negative reasons not to. It's enabled me to > > > > > pay off a ton of technical debt that accumulated over the eight years > > > > > I handwrote everything. > > > > > > > > > > Another example: I've been working on an orchestration tool around > > > > > easy-db-lab to automate running my tests across several clusters in > > > > > parallel. I recently refactored it to split the REST server code > > > > > from the execution into Gradle submodules. Now I can create > > > > > different agents specializing in each module's content, which slims > > > > > down the context for each agent. Since I have a very clear boundary > > > > > on each agent's responsibility, I avoid the overhead of having one > > > > > agent manage one huge codebase. I can specifically tell that one > > > > > agent is responsible for this directory, and its expertise is in > > > > > Ktor. Another agent is a Gradle expert. Another is Kubernetes. > > > > > When I work on tasks they can be decomposed into task lists for each > > > > > specialized agent. > > > > > > > > > > I've always thought this would be a great architectural improvement > > > > > for the C* codebase regardless of LLMs. For example, putting the CQL > > > > > parser in a standalone module would allow us to publish it so people > > > > > could consume it in their own ecosystem without pulling in C*-all. > > > > > Isolating a few of these subsystems could reduce cognitive overhead > > > > > and simplify test design. I'm sure making the commit log reader > > > > > standalone would make it much easier to use in the sidecar. Easily > > > > > using the SSTable readers and writers without all the other > > > > > dependencies would reduce workarounds in bulk analytics and make > > > > > these types of projects more feasible, benefiting the wider ecosystem. > > > > > > > > > > Regardless of this approach, creating a devcontainer environment for > > > > > the project and pushing the image to GHCR would also be beneficial. > > > > > I am now using one with each of my tools. I don't trust Claude not > > > > > to wipe my system, so I sandbox it in a container. It only has access > > > > > to the local project and cannot push code or reach GitHub. > > > > > Devcontainers are supported directly in IDEA, Zed, and VSCode. You > > > > > can also launch them directly from GitHub or use the Claude mobile > > > > > app. I haven't spent much time on this yet though, I still prefer > > > > > two big 5k screens and a deafening mechanical keyboard. > > > > > > > > > > Jon > > > > > > > > > > [1] > > > > > https://github.com/rustyrazorblade/easy-db-lab/blob/main/.devcontainer/devcontainer.json > > > > > [2] > > > > > https://github.com/rustyrazorblade/easy-db-lab/blob/main/.devcontainer/Dockerfile > > > > > > > > > > > > > > > > > > > > On Thu, Feb 26, 2026 at 12:58 AM Štefan Miklošovič > > > > > <[email protected]> wrote: > > > > > > > > > > Thank you Jon for sharing,that was very helpful. All these insights > > > > > are invaluable. > > > > > > > > > > On Wed, Feb 25, 2026 at 11:50 PM Jon Haddad > > > > > <[email protected]> wrote: > > > > > > > > > > Regarding ant, we'd probably want a wrapper shell script that is more > > > > > LLM-friendly, hiding the excessive text and providing more actionable > > > > > output. You can also delegate any task to a subagent so you don't > > > > > waste your context on the `ant` output, and use Claude's new Agent > > > > > Teams [1] feature to have a "builder" agent run in its own process. > > > > > Docs help Claude find code, big time. You can give it your > > > > > organizational structure and that institutional knowledge so it > > > > > doesn't have to pull in many tokens from dozens of files. It > > > > > *definitely* works. I've pushed over a quarter million LOC this > > > > > month alone [1], and many of you may already know I'm obsessed with > > > > > efficiency. I constantly test new ideas and approaches to refine my > > > > > process; I've found good documentation is *critical*. > > > > > > > > > > I've recently started working with both Spec-Kit (Microsoft, but it > > > > > looks abandoned) and OpenSpec, as both are designed to maintain > > > > > long-term memory for a project's product requirements and technical > > > > > decisions. OpenSpec is supposed to work better for brownfield and > > > > > iterative projects. I haven't tried BMAD yet. It seemed a bit more > > > > > heavyweight, but it may be better for this project than my personal > > > > > ones, where I don't collaborate with anyone. > > > > > > > > > > I have found that the best results come from loosely coupled systems. > > > > > C*'s technical debt will make using an agent in the codebase much > > > > > harder than using one in my own. I haven't tried to work on a patch > > > > > in C* yet with an agent, but when I do I'll be sure to share what > > > > > I've learned. > > > > > > > > > > Today I introduced OpenSpec to easy-db-lab, you can see what it looks > > > > > like [3] if you're curious. A number of markdown commands were added > > > > > to the repo, and Spec-Kit was removed. I haven't reviewed it yet. > > > > > By the time you read this I will have likely made some changes in a > > > > > review. If you want to see the before and after, the pre-review > > > > > commit is c6a94e1. > > > > > > > > > > Jon > > > > > > > > > > [1] https://code.claude.com/docs/en/agent-teams > > > > > [2] my 2 main projects, not including client work: > > > > > git log --since="$(date +%Y-%m-01)" --numstat --pretty=tformat: | awk > > > > > 'NF==3 {added+=$1; removed+=$2} END {print "Added:", added, > > > > > "Removed:", removed}' > > > > > Added: 90339 Removed: 45222 > > > > > > > > > > git log --since="$(date +%Y-%m-01)" --numstat --pretty=tformat: | awk > > > > > 'NF==3 {added+=$1; removed+=$2} END {print "Added:", added, > > > > > "Removed:", removed}' > > > > > Added: 124863 Removed: 52923 > > > > > > > > > > > > > > > [3] https://github.com/rustyrazorblade/easy-db-lab/pull/530/changes > > > > > > > > > > On Wed, Feb 25, 2026 at 6:18 AM David Capwell <[email protected]> > > > > > wrote: > > > > > > > > > > I’m not against memory / skills being added, but do want to request > > > > > we think / test to make sure we can quantify the gains > > > > > > > > > > <arxiv-logo-fb.png> > > > > > Evaluating AGENTS.md: Are Repository-Level Context Files Helpful for > > > > > Coding Agents? > > > > > arxiv.org > > > > > > > > > > <arxiv-logo-fb.png> > > > > > SkillsBench: Benchmarking How Well Agent Skills Work Across Diverse > > > > > Tasks > > > > > arxiv.org > > > > > > > > > > > > > > > These papers actually match my lived experience with this projects > > > > > and others. > > > > > > > > > > 1) using /init to create CLAUDE.md / AGENTS.md yields negative > > > > > results. This is how I started and have moved away. What is the > > > > > context you need 100% of the thing? It’s things that Claude can’t > > > > > discover easy such as tribal knowledge (such as link to our style > > > > > guide). > > > > > 2) Ant is horrible for agents, not to figure out what to do (Claude > > > > > is good at that) but at context bloat… do “ant jar” and you add like > > > > > 10-20k tokens… you MUST have tooling to fix this (I ban Claude from > > > > > touching ant command, it’s only allowed to run “ai-build”, and > > > > > “ai-ci-test” as these fix the context problems; rtk “might” work > > > > > here, not tested as in on leave) > > > > > 3) Claude doesn’t need docs to find code, that actually confuses it > > > > > more. When it needs to modify code it’s going to have to explore and > > > > > will most likely find what it needs. I agree docs for humans would > > > > > help, but let’s keep it out of AI memory files. > > > > > 4) I only really use sonnet/opus 4.5+, these claims might not be true > > > > > for older models or the open weight models. > > > > > > > > > > As for skills, the following makes sense to me but I really hope a > > > > > human writes as AI doesn’t do well at understanding the WHY well and > > > > > makes bad assumptions: property testing, stateful property testing, > > > > > harry, The Simulator. I left out cqltester because I found Claude > > > > > doesn’t suck at it, so not sure what a skill would add. The others I > > > > > found it struggles with and produces bad quality tests. > > > > > > > > > > Last comment: Stefan, your link about ai code in the project didn’t > > > > > take into account what happened in the PR. Our global static state > > > > > world caused a single test to fail which required a complete rewrite > > > > > of the patch that I ended up doing by hand. So that patch ended up > > > > > being 100% human. > > > > > > > > > > Sent from my iPhone > > > > > > > > > > On Feb 18, 2026, at 6:29 PM, Štefan Miklošovič > > > > > <[email protected]> wrote: > > > > > > > > > > These are great points. I like how granular the approach of having > > > > > multiple files is. That means we do not need to craft one > > > > > "uber-claude.md" but we can do this iteratively and per specific > > > > > domain which is easier to handle. > > > > > > > > > > One consequence of having these "context files" is that a contributor > > > > > does not even need to use any AI whatsoever in order to be more > > > > > productive and organized. There is a lot of time lost when a new > > > > > contributor wants to understand how the project "thinks", what are > > > > > do-s and dont-s etc. All stuff which appears once a patch is > > > > > submitted. If we explained to everybody in plain English how this all > > > > > works on a detailed level, per domain, that would be tremendously > > > > > helpful even without AI. > > > > > > > > > > It will be interesting to watch how these files are written. To > > > > > formalize and write it down is quite a task on its own. > > > > > > > > > > > > > > > On Wed, Feb 18, 2026 at 6:47 PM Patrick McFadin <[email protected]> > > > > > wrote: > > > > > > > > > > > > > > > Context size is the hardest thing to manage right now in agentic > > > > > coding. I’ve stopped using MCP and switched to skills as a result. > > > > > > > > > > > > > > > A couple of things worth noting. You can use many multiple > > > > > CLAUDE.md/AGENT.md files in a large code base. I’m started doing this > > > > > and it is remarkable. For example, in the pylib directory a CLAUDE.md > > > > > file would provide the Python specific info if making changes. The > > > > > standard layout for each should be > > > > > > > > > > - What is this > > > > > > > > > > - Where do I get more information > > > > > > > > > > - How do I run or test > > > > > > > > > > - What are the non-nogetialble rules > > > > > > > > > > - What does done look like > > > > > > > > > > > > > > > Imagine one in all sorts of places. fqtool, sstableloader, > > > > > o.a.c.io.*, o.a.c.repair.* etc etc. And they can evolve over time as > > > > > people use them. > > > > > > > > > > > > > > > The other thing to bring up is Brokk built by Jonathan Ellis. He > > > > > specifically built it for large code bases and specifically tests on > > > > > the Cassandra code base. (I’ll let him jump in here) > > > > > > > > > > > > > > > Patrick > > > > > > > > > > > > > > > On Feb 18, 2026, at 8:51 AM, Josh McKenzie <[email protected]> > > > > > wrote: > > > > > > > > > > > > > > > I’ve had trouble using Claude effectively on C*’s large codebase > > > > > without a lot of repeated “repo discovery” prompting. > > > > > > > > > > > > > > > Just to keep beating the drum: I've had trouble working in our > > > > > codebase effectively without a lot of repeated "repo discovery" time. > > > > > In fact, a huge portion of the time I spend working on the codebase > > > > > consists of reading into adjacent coupled classes and modules since > > > > > things are a) not consistently or thoroughly documented, and b) > > > > > generally not that decoupled. > > > > > > > > > > > > > > > This is also / primarily a "human <-> information interfacing > > > > > efficiency problem" and it just so happens LLM's and agents being > > > > > blocked from working on our codebase is giving us an immediate > > > > > short-term pain-proxy for something I strongly believe has been a > > > > > long-term tax on us. > > > > > > > > > > > > > > > On Wed, Feb 18, 2026, at 10:04 AM, Isaac Reath wrote: > > > > > > > > > > > > > > > I'm a +1 for the same reason that Josh lays out. Markdown files that > > > > > detail the structure of the repo, how to build & run tests, how to > > > > > get checkstyle to pass, etc. are all very valuable to new > > > > > contributors even if LLMs went away today. > > > > > > > > > > > > > > > On Tue, Feb 17, 2026 at 7:33 PM Jon Haddad <[email protected]> > > > > > wrote: > > > > > > > > > > > > > > > It's all part of the same topic, Yifan. You're making a distinction > > > > > without a difference. We could just as easily be discussing > > > > > supporting certain MCP servers like serena, or baking claude into a > > > > > devcontainer. It's all relevant. There's no need to police the > > > > > discussion. > > > > > > > > > > > > > > > On Tue, Feb 17, 2026 at 4:25 PM Yifan Cai <[email protected]> wrote: > > > > > > > > > > > > > > > The original post was about adding AI tooling, prompt, command, or > > > > > skill. The thread is shifted to AI memory files. > > > > > > > > > > > > > > > I do not have an objection to any of these, but want to make sure > > > > > that we are still on the original topic. > > > > > > > > > > > > > > > IMO, AI tooling has a clear scope / definition and is easier to reach > > > > > consensus on. Meanwhile, AI memory files are vague to define clearly. > > > > > Different developers on different domains could have quite different > > > > > preferences. > > > > > > > > > > > > > > > - Yifan > > > > > > > > > > > > > > > On Tue, Feb 17, 2026 at 3:37 PM Dmitry Konstantinov > > > > > <[email protected]> wrote: > > > > > > > > > > > > > > > I do not have my one but here there are few examples from oher Apache > > > > > projects: > > > > > > > > > > https://github.com/apache/camel/blob/main/AGENTS.md > > > > > > > > > > https://github.com/apache/ignite-3/blob/main/CLAUDE.md > > > > > > > > > > https://github.com/apache/superset/blob/master/superset/mcp_service/CLAUDE.md > > > > > > > > > > > > > > > On Tue, 17 Feb 2026 at 23:22, Jon Haddad <[email protected]> > > > > > wrote: > > > > > > > > > > > > > > > I think a few folks are already using CLAUDE.md files in their repo > > > > > and they're just not committing them. > > > > > > > > > > Anyone want to share what's already done? I'm happy to help share > > > > > what I know about the agentic side of things, but since I don't do > > > > > much in the way of patching C* it would be a lot of guessing. > > > > > > > > > > > > > > > If I'm wrong and nobody shares one, I'll take a stab at it. > > > > > > > > > > > > > > > > > > > > > > > > > On Tue, Feb 17, 2026 at 3:08 PM Štefan Miklošovič > > > > > <[email protected]> wrote: > > > > > > > > > > > > > > > Great feedback everybody! Really appreciate it! > > > > > > > > > > > > > > > Reading what Jon posted ... Jon, I think you are the most experienced > > > > > > > > > > in this based on what you wrote. Would you mind doing some POC here > > > > > > > > > > for Cassandra repo? For the trunk it is enough ... Something we might > > > > > > > > > > build further on. I think we need to build the foundations of that and > > > > > > > > > > put some structure into it and all things considered I think you are > > > > > > > > > > best for the job here. > > > > > > > > > > > > > > > If the basics are there we can play with it more before merging, this > > > > > > > > > > is not something which needs to be done "tomorrow", we can collaborate > > > > > > > > > > on something together for some time and add things into it as patches > > > > > > > > > > come. I think it takes some time to "tune" it. > > > > > > > > > > > > > > > Everybody else feel free to help! My experience in this space is > > > > > > > > > > limited, I think there are people who are using it more often than me > > > > > > > > > > for sure. > > > > > > > > > > > > > > > Regards > > > > > > > > > > > > > > > On Wed, Feb 18, 2026 at 12:59 AM Joel Shepherd <[email protected]> > > > > > wrote: > > > > > > > > > > > > > > > There's been some momentum building for AGENTS.md files, both on the > > > > > > > > > > project and on the agent side: > > > > > > > > > > > > > > > https://agents.md/ > > > > > > > > > > > > > > > Same idea and benefits, but it might help to align folks on a > > > > > "standard" > > > > > > > > > > that will work well across agents. > > > > > > > > > > > > > > > I also think that more and better code documentation can be very > > > > > > > > > > beneficial when using agents to help with working out implementation > > > > > > > > > > details. I spent a bunch of time in January writing an introduction to > > > > > > > > > > Apache Ratis (Raft as a library: > > > > > > > > > > https://github.com/apache/ratis/blob/master/ratis-docs/src/site/markdown/index.md). > > > > > > > > > > The code itself is pretty well-documented but it was hard for me to > > > > > > > > > > build a mental model of how to integrate with. AI was very effective > > > > > in > > > > > > > > > > taking the granular in-code documentation and synthesizing an overview > > > > > > > > > > from it. Going the other way, the in-code documentation has made it > > > > > > > > > > possible for me to deep dive the Ratis code to root cause bugs, etc. > > > > > > > > > > Agents can get a lot out of good class- and method-level > > > > > documentation. > > > > > > > > > > > > > > > -- Joel. > > > > > > > > > > > > > > > On 2/16/2026 8:03 PM, Bernardo Botella wrote: > > > > > > > > > > CAUTION: This email originated from outside of the organization. Do > > > > > not click links or open attachments unless you can confirm the sender > > > > > and know the content is safe. > > > > > > > > > > > > > > > > > > > > > > > > > Thanks for bringing this up Stefan!! > > > > > > > > > > > > > > > A really interesting topic indeed. > > > > > > > > > > > > > > > > > > > > I’ve also heard ideas around even having Claude.md type of files that > > > > > help LLMs understand the code base without having to do a full scan > > > > > every time. > > > > > > > > > > > > > > > So, all and all, putting together something that we as a community > > > > > think that describe good practices + repository information not only > > > > > for the main Cassandra repository, but also for its subprojects, will > > > > > definitely help contributors adhere to standards and us reviewers to > > > > > ensure that some steps at least will have been considered. > > > > > > > > > > > > > > > Things like: > > > > > > > > > > - Repository structure. What every folder is > > > > > > > > > > - Tests suits and how they work and run > > > > > > > > > > - Git commits standards > > > > > > > > > > - Specific project lint rules (like braces in new lines!) > > > > > > > > > > - Preferred wording style for patches/documentation > > > > > > > > > > > > > > > Committed to the projects, and accesible to LLMs, sound like really > > > > > useful context for those type of contributions (that are going to > > > > > keep happening regardless). > > > > > > > > > > > > > > > So curious to read what others think. > > > > > > > > > > Bernardo > > > > > > > > > > > > > > > PD. Totally agree that this should change nothing of the quality bar > > > > > for code reviews and merged code > > > > > > > > > > > > > > > On Feb 16, 2026, at 6:27 PM, Štefan Miklošovič > > > > > <[email protected]> wrote: > > > > > > > > > > > > > > > Hey, > > > > > > > > > > > > > > > This happened recently in kernel space. (1), (2). > > > > > > > > > > > > > > > What that is doing, as I understand it, is that you can point LLM to > > > > > > > > > > these resources and then it would be more capable when reviewing > > > > > > > > > > patches or even writing them. It is kind of a guide / context provided > > > > > > > > > > to AI prompt. > > > > > > > > > > > > > > > I can imagine we would just compile something similar, merge it to the > > > > > > > > > > repo, then if somebody is prompting it then they would have an easier > > > > > > > > > > job etc etc, less error prone ... adhered to code style etc ... > > > > > > > > > > > > > > > This might look like a controversial topic but I think we need to > > > > > > > > > > discuss this. The usage of AI is just more and more frequent. From > > > > > > > > > > Cassandra's perspective there is just this (3) but I do not think we > > > > > > > > > > reached any conclusions there (please correct me if I am wrong where > > > > > > > > > > we are at with AI generated patches). > > > > > > > > > > > > > > > This is becoming an elephant in the room, I am noticing that some > > > > > > > > > > patches for Cassandra were prompted by AI completely. I think it would > > > > > > > > > > be way better if we make it easy for everybody contributing like that. > > > > > > > > > > > > > > > This does not mean that we, as committers, would believe what AI > > > > > > > > > > generated blindlessly. Not at all. It would still need to go over the > > > > > > > > > > formal review as anything else. But acting like this is not happening > > > > > > > > > > and people are just not going to use AI when trying to contribute is > > > > > > > > > > not right. We should embrace it in some form ... > > > > > > > > > > > > > > > 1) https://github.com/masoncl/review-prompts > > > > > > > > > > 2) > > > > > https://lore.kernel.org/lkml/[email protected]/ > > > > > > > > > > 3) https://lists.apache.org/thread/j90jn83oz9gy88g08yzv3rgyy0vdqrv7 > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > > > > > > Dmitry Konstantinov > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > -- > > > > > Dmitry Konstantinov > > > > > > > > > > > > > > > > > > > > > > > > > > > > >
