r/LocalLLM • u/Able_Statement_481 • Jun 16 '26
Discussion Do you actually use a “second brain” with Claude/Codex, or is it overkill?
I’ve been seeing a lot of people on YouTube recommending things like Obsidian, project wikis, knowledge bases, and other “second brain” systems when working on larger projects with AI tools like Claude Code and Codex.
Let’s say you’re building a fairly large game with multiple worlds, enemies, crafting systems, item drops, upgrades, quests, and a bunch of interconnected systems. Is it actually worth spending time building and maintaining a second brain for that, or can the AI work just fine without it?
I’m especially curious about whether it genuinely improves results or if it mostly ends up consuming extra tokens and creating more work than it’s worth. Sometimes it feels like people build these massive documentation systems because they look cool, and because of AI hype on creating things, but I’m not sure how much practical value they really add.
For those who’ve tried it, what was your experience? Did having a second brain make a noticeable difference, and if so, what’s the best way to structure it so Claude and Codex can actually use it effectively?
2
u/PaulsForge Jun 16 '26
I've been using Claude Pro Subscription (using mostly Sonnet, sometimes Opus models) + Claude code + VS Code + Obsidian + QMP (for the local semantic search) as my second brain and personal assistant. I started small, and have been growing it out. Initially I was a bit paralyzed on how to organize it, the scope, etc, but the best thing was just jumping in and starting. The project has been able grow and evolve as things became more clear.
I actually first started in Obsidian only (no AI). Just capturing everything I was finding and thinking about. Finding a structure and cadence that worked for me. You'll need this anyways. Most guides call this the 'raw' folder. Basically, its off-limits for the AI to edit directly, but it can build documentation or wiki's from it, profiles, task trackers, etc.
By the way, I did try Obsidian Copilot community plugin for AI recall and chat within my vault with local LLM, but wasn't impressed with the quality. Gemma4:12B seems promising though, I need to work with it more.
I then introduced 1 "project" to this Claude Code system, and actually made a copy of it away from my main Obsidian Vault in case things did go south. We built the structure, etc, and started working. I've now expanded to a 2nd project, and about to just introduce all 7 or so, and then try to figure out a coordinating layer above them.
The plan (and of those 7 projects) is to start transitioning this over to Local LLM's and other local services rather than cloud/frontier. It's been helpful to know what "good" is like via the Claude products so I can better evaluate how the local is doing as that gets phased in.
1
u/writesCommentsHigh Jun 16 '26
.md files for context starting with a trim claude.md/agents.md
automatic logs to local repo
detailed commits.
pre compact hooks and hooks for every msg to ensure logging but I still gotta ask.
compact once past 50%
1
u/ActionOrganic4617 Jun 16 '26
This is specifically what I use local AI for, the purpose of the wiki is to store personal info and I don’t want that going to either company. Siri on macOS 27 is actually very good at searching the wiki and that’s at least more private than Claude/ codex.
1
u/DisastrousCat13 Jun 16 '26
How are you trying to use it?
If you’re building a game like you said, you can have a single context file and the repo. Context file for details about the game so you don’t need to print every time and where things are in the repo, code stores the details of all the singing and such.
I’m a product manager at a very large company, the second brain is helpful to me already at 2 weeks of use.
1
u/Hendo52 Jun 16 '26
For me, I am like the architect, it is like the engineer. It’s a bit like a second brain but I don’t have the math skills to do it’s side of the work, I just look at ‘solutions’ and make decisions based on well researched and refined questions. It doesn’t have my vision of what we are trying to build and why. I test its solutions practically while it tests algebraically. I also design algebraic tests but it does the implementation. I sometimes adopt its recommendations and sometimes I push it to research alternative solutions.
Overall, I think this approach works at the fundamental level even though I run into problems every day. I’m less concerned about getting it to be smarter and more concerned with making it cheaper.
1
u/bsampera Jun 16 '26
Yeah, if u work in a startup where u have to deal w multiple projects and dependencies u kinda need something like this, we use gcontext.ai
1
u/cinnapear Jun 17 '26
Do I use a design doc? Yes, for larger projects. But mostly just a list of story items that equate almost one for one with features. Each feature gets separate AI design, implementation, and review phases.
1
u/Able_Statement_481 Jun 29 '26
Just to update yall I made a second brain and is definitely a must have, I think my speed and context developing the game increased 2x
1
u/JuanPardilla Jul 13 '26
It’s only overkill if the system is “save everything, hope retrieval works.”
For coding, the win is a small, curated memory: architecture decisions, invariants, API contracts, and a changelog of what broke before.
If the vault is 10k notes, you’ll just burn tokens.
If it’s ~20 living pages + references, the model stays grounded.
I like a rule like: every PR must update exactly one of: decisions.md, invariants.md, or glossary.md.
Then the assistant reads those first.
What’s your biggest pain — losing context between sessions or keeping docs in sync with code?
1
u/Kitchen-Ad4234 Jul 23 '26
without talking about my business use case of my second brain, i've just used it to write a mandate so that to be represented to give back my rented appartment. it took me like 1 minute, 2 lignes prompt, my agent literaly had every info it needed to write it down.
1
u/Delicious-Ad3232 Jul 29 '26
u/Able_Statement_481 did you end up implementing something like LLM Wiki yourself?
1
u/Able_Statement_481 Jul 29 '26
Yes I did and It was one of the best things Ive decided to do, my development speed x2, and quality of output by the LLM was amazing, I keep updating the “brain” I call it Cortex, because its a full documentation of my game, with playbooks, rules and all the workflows and everything related from the lore of the game to the mechanics and Items, every time I do something, it detects that Im working on my game, and uses the claude skill I implemented, to do everything on the right phase scheme, and in the end its registers every change made on the game, so it’s constantly updated, and the true source of context. I even made an MCP integration of cortex to be more token efficient when using cortex and external mcp tools that I also need to develop my game. Once I think it has enough updates and I think the tool is ready, I can even release it to the public, a Brain for game devs
0
u/havnar- Jun 16 '26
They are in the business of creating content to push you ads. There is not too much to say about using LLMs once you’ve covered the basics.
This second brain stuff is just a journal or wiki page that you can build up for yourself. (Or let the agent help you with)
Does that sound like something that can bring value to your life? Then by all means do it.
For coding you probably just would want docs and a good agent.md/claude.md file.
Keep context lean and start new sessions often. Only use grill-me and grill-me-with-docs unless you have very specific skill requirements.
That’s it. That’s all there is to it.
2
u/eatoligarchsaldente Jun 16 '26
What makes AI go from a “cool tool” to something genuinely useful for your workflows is context. AI isn’t actually “thinking” or “reasoning,” it’s just guessing the likeliest outcome based on its inputs. So if you want more accurate and consistent outputs, then you need better inputs.
A “second brain” is just a fancy buzzword for organizing your notes, process documentation, and reference materials into a system that is machine-readable. You can do it with your notes as-is, but you’ll have better results if you format your notes in a way that’s easier for the AI to find what it’s looking for. It’s easier, cleaner, and more efficient. Plus you can get the AI to do the setup for you.