My Hermes Second Brain Stack (OMI + Obsidian)

A Hermes second brain is the AI memory stack I run every single day, and the reason I'm writing this post is that I've watched dozens of operators jump from cloud memory tool to cloud memory tool without ever sticking to one. I tried multiple AI memory solutions over the past year — ChatGPT memory, Claude projects, custom MCP setups — and none of them stuck. Then I built the Hermes second brain stack with OMI plus Obsidian plus Hermes, and I haven't looked back.

This post is the honest "why" behind the stack. I'll cover why cloud memory failed me, what changed when I switched, and how to set it up yourself in 30 minutes if you decide it's the right move.

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Why Cloud AI Memory Failed Me

Three reasons cloud memory didn't survive contact with my actual workflow.

The first is platform lock-in. ChatGPT memory only works in ChatGPT. Claude memory only works in Claude. I use both plus OpenClaw plus Hermes plus custom agents, and cloud memory doesn't transfer between platforms. That means every tool starts from scratch on context, which is the opposite of what memory is supposed to do.

The second is limited capacity. Cloud platforms cap how much they remember and after a few weeks things drop off silently. You don't notice until you ask for something the model should remember and it doesn't.

The third is privacy. For client work, business decisions, and personal goals, cloud memory feels wrong. I want my AI memory on my own machine where I control what gets stored and what gets shared.

Why The Hermes Second Brain Is Different

The local stack solves all three problems. It's local, so privacy is in your control. It's portable across agents, so any tool can read the same memory. And it's automatic, so you don't have to manually note things to keep it current.

Three principles I care about, all met by one setup.

My Stack In Detail

The stack has three core pieces and a few extras. OMI captures my screen and voice automatically as I work. Obsidian stores those memories as markdown in a local vault on my machine. Hermes reads the vault on every prompt so it has full context for whatever I'm asking.

On top of the core three, I add manual notes to Obsidian for deep thoughts that aren't worth waiting for OMI to capture. The same vault works with OpenClaw, Claude Desktop, and Cursor through cross-agent integration, which is the part that makes the whole thing scale.

That's the whole setup.

The Lazy Setup Path

If you want this running fast, the path is straightforward and takes 30 minutes total.

Five minutes to install OMI. Five minutes to install Obsidian and create a vault. Five minutes to connect OMI to Obsidian. Five minutes to point Hermes at the vault path. Ten minutes to test queries that need memory and confirm everything is wired correctly.

For the broader Hermes context that this builds on, see How To Setup Hermes Agent.

What Changed When I Switched

Three things became different overnight.

The first is that Hermes started referencing my actual projects. Before the switch, responses were generic. After, recommendations were specific to what I was actually working on, which made the agent dramatically more useful. The second is that I stopped re-explaining myself. Before, every conversation started from scratch. After, Hermes already knows my context and we skip the setup. The third is that decisions got faster. Before, I'd ask questions Hermes couldn't really answer because it lacked context. After, Hermes has the full picture and gives sharper input.

These three shifts together changed how I use AI agents at all, not just Hermes.

Watch The Walkthrough

Here's the original OMI plus Obsidian plus Hermes walkthrough.

That walkthrough covers the wiki side specifically — the Karpathy-style approach to structured memory.

What I Don't Like About The Setup

Be honest about the downsides. There are three.

The first is that OMI captures more than you'd manually note, so you get noise. You need to review the vault weekly to delete junk and keep signal high. The second is that privacy hygiene matters — I exclude specific apps from OMI capture and you should too, especially for anything sensitive. The third is that the setup is fiddly the first time. OMI permissions, Obsidian vault path, Hermes config — none of it is one-click.

Once running it's set-and-forget, but the first 30 minutes do require attention.

What Made The Setup Worth It

Three things justified the friction for me.

The first is time saved daily. I used to spend 30+ minutes a day writing notes manually, and now it's automatic. The second is better Hermes outputs — the quality of agent responses jumped noticeably once memory was in place. The third is cross-agent portability. The same vault works for OpenClaw, Claude Desktop, and Cursor, which means I'm not locked into anyone's ecosystem and can swap tools without losing context.

These three together are the reason I don't go back.

How I Use The Hermes Second Brain Daily

The real workflow looks like this. In the morning I open Hermes and ask "what's my priority today?" and get a context-aware answer. Throughout the day I work normally and OMI captures in the background. During calls, Hermes can reference what was said in previous calls when I had OMI on, which is genuinely useful for follow-ups. In the evening Hermes summarises the day's captured decisions so I have a clean log of what I committed to and what I shipped.

I used to need a personal assistant for this. Now I have Hermes.

Cross-Agent Use

The Hermes second brain works with other agents too, which is the multiplier.

For OpenClaw, give the same command and path: "Use this file path for context and memory: [Obsidian vault path]". I cover the OpenClaw side in OpenClaw Memory Persistence. For Claude Desktop, paste the path into a project's instructions and you get the same effect.

Same memories, multiple agents. That's what makes the local stack actually scale.

What Solo Operators Should Care About

If you're a solo operator running multiple AI tools, the value is concentrated for you. You stop re-explaining yourself across platforms, you build memory once and use it everywhere, and you save hours every week on context-setting that you'd otherwise repeat across tools.

This is why solo operators specifically benefit most from the local second brain pattern.

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What Teams Should Consider

If you have a team, the structure shifts slightly. Each person can run their own second brain rather than sharing one. You shouldn't share OMI memories across people for privacy reasons. You can share manual Obsidian notes via Obsidian Sync for shared knowledge. Each Hermes instance reads from one vault.

This way the team has shared knowledge without privacy issues bleeding between members.

Why I Don't Use ChatGPT Memory Anymore

Three reasons ChatGPT memory dropped out of my stack.

The first is that it's locked to ChatGPT and I can't use those memories with Claude or OpenClaw. The second is that ChatGPT decides what's "memorable" rather than letting me decide, and I want everything captured. The third is that it lives on OpenAI's servers, which is a privacy concern for client work specifically.

For all three reasons local Hermes second brain wins for my situation.

What This Replaces In My Stack

Things I've stopped using since the second brain went in include ChatGPT memory, Claude projects (mostly), Notion-based context docs, and manual prompt templates with personal context. All of these get replaced by one consistent Obsidian vault that all my agents can read.

Fewer tools, better outcomes. That's the trade.

Daily Reality Numbers

From my own setup the numbers are concrete. I save roughly 30 minutes daily on context-setting. Hermes responses are qualitatively about 50% better — sharper and more personalised. The monthly cost is £0 versus £20+ for ChatGPT Plus memory features. Setup time was 30 minutes one-off.

ROI is positive within the first week of daily use.

Watch Hermes In Action

For the broader Hermes 2026 framework where the second brain is one piece, this walkthrough covers the full setup, multi-agent, profiles, and dashboard.

Three Things I'd Tell Anyone Setting Up

Three things I wish I'd known on day one.

The first is to be selective with OMI. Don't enable everything on day one — start with screen recording, add microphone selectively as you learn what you actually want captured. The second is to test memory recall daily. If Hermes isn't using the vault as much as it should, refine your prompts to reference memory explicitly. The third is to add manual notes for deep thinking. Don't rely only on auto-capture because curated notes capture intent in a way OMI can't.

FAQ — Why Hermes Second Brain

Why not just use ChatGPT memory?

It's locked to one platform and I use multiple agents.

Is local second brain really better?

For portability, privacy, and cost, yes. The trade-off is initial setup time.

How long until it pays back?

Within the first week of daily use.

Will OMI keep recording forever?

Until you turn it off. You're in full control of the capture.

Can I export the vault if I switch tools?

Yes. Markdown is universal and the vault is just files.

Should I encrypt the vault?

If you handle sensitive client data, yes. For personal use, your call.

Does this work on Windows or Linux?

Mostly yes. OMI is Mac-first but Obsidian and Hermes work on all OSes.