--- title: Editing your own software is solved. Someone else's is next. slug: editing-your-own-software-is-solved-someone-else-s-is-next published_at: 2026-10-02 14:18:00 +0000 updated_at: 2026-10-02 18:22:22 +0000 summary: tags: [] author: CJ Avilla url: https://www.cjav.dev/articles/editing-your-own-software-is-solved-someone-else-s-is-next type: article --- # Editing your own software is solved. Someone else's is next. *Published: October 02, 2026* My prediction: changing software you don't own is about to be something anyone can do. Think of it as open source for everyone, with no GitHub account and no programming language to learn. Managed agents embedded in products that empower users make deep changes on the spot. We've seen shallow versions of this before. Remember MySpace? The first HTML I ever wrote went into a MySpace profile. The payoff for personalization was self-expression and a personal brand. ![A 2006 profile page, drawn from memory: the pasted CSS was paint you could change, the Top 8 and “view all friends” link were engine you couldn’t](/rails/active_storage/blobs/eyJfcmFpbHMiOnsiZGF0YSI6NDk2MiwicHVyIjoiYmxvYl9pZCJ9fQ==--0c7d33de33e9c92089137769c30d262a72113209/00b-profile-2006.png) ## We could change the paint, never the engine ![Paint vs. engine: restyling was allowed, but one shared database meant a “show all friends” feature was 1+N queries for every visitor](/rails/active_storage/blobs/eyJfcmFpbHMiOnsiZGF0YSI6NDk2MywicHVyIjoiYmxvYl9pZCJ9fQ==--806f8be9f3c68fa87a5163e45c37d19d87609f90/01-paint-vs-engine.png) MySpace let you change how your page looked. It never let you change how MySpace *worked*. People wanted more than eight friends on display, so they traded hacks to push the Top 8 to twelve or sixteen. That was the ceiling, and it was still decoration. Changing the engine has a different payoff. It's about getting more out of something you already use. You add the feature that's missing, or you automate the step you keep doing by hand. Two things kept the engine sealed. The first was skill: changing how software works meant writing code, and most people couldn't. The second was blast radius. Say you wanted your profile to list every friend you had. The naive version runs one database query per friend, and the page is now slow for everyone who visits it. Multiply that by millions of people editing live code, and platforms drew the line at paint. ## Editing your own software is solved Agents took care of the skill. [Geoffrey Litt called it in 2023](https://www.geoffreylitt.com/2023/03/25/llm-end-user-programming.html). The hard part of end-user programming was turning fuzzy intent into working code. No-code platforms were working on the same barrier before agents showed up. Retool is a good example of where they're headed. Its builder now goes ["from prompt to production"](https://retool.com/ai): you describe an internal tool and it generates one against your own databases and APIs. Three people are already doing it in public. [levelsio](https://x.com/levelsio/status/2071162399864889705) runs Claude Code on his production server and prompts it from his phone. He's worked that way for almost a year btw. [OpenClaw](https://github.com/openclaw/openclaw), a personal agent that runs on your own machine, writes itself new skills and [restarts itself](https://github.com/openclaw/openclaw/issues/26872) to load them. [David Crawshaw](https://blog.exe.dev/devtools-must-be-open-source) keeps his changes as commits on top of the source and has an agent rebase them onto upstream every night. In his words, "the source code is the extension system." All three work for the same reason: the owner, the developer, and the user are one person. Root on your own box is fine when the only person you can break things for is you. ## Editing someone else's software is the hard part ![Editing your own software (owner = developer = user, root is fine) vs. someone else’s (each user needs an isolated copy to prompt against)](/rails/active_storage/blobs/eyJfcmFpbHMiOnsiZGF0YSI6NDk2NCwicHVyIjoiYmxvYl9pZCJ9fQ==--f3f1f651ea502538827605a33509b2ddb4e7300a/02-yours-vs-someone-elses.png) [r00k](https://x.com/r00k/status/2085165803171656121) described the itch. He was stuck with a game's clumsy lobby screen, sure that one prompt could fix it, with no way to send that prompt. Sawyer Hood sees it from the other side. He builds [bb](https://getbb.app), an IDE whose users extend it with the same tools he uses. [His line](https://x.com/sawyerhood/status/2085039905529597982): "I have not gone back to a tool I cannot change." What stops r00k is the second barrier. levelsio can't give every user root on his server. Once the prompt line belongs to the user and not the developer, you need isolation (and maybe a mechanism to upstream changes). Each person's changes run in their own copy, fenced off from everyone else's data. "Open for extension, closed for modification" was good advice when a change to working code hit every client. Give each user an isolated clone and there are no other clients to hit. Inside your copy, nothing has to stay closed. The rule only comes back where copies share something: the data, the base they update from, and the APIs they call. ![Before: one codebase, closed for modification. After: a base plus a clone per user; the rule only comes back for what’s still shared (data, base, APIs)](/rails/active_storage/blobs/eyJfcmFpbHMiOnsiZGF0YSI6NDk2NSwicHVyIjoiYmxvYl9pZCJ9fQ==--95b25b8a786ed6d6fd698e77f8212199baa1fd61/03-isolation-replaces-closed.png) That took a long time to build. [Kenton Varda](https://x.com/KentonVarda/status/2084990137180590572) started Sandstorm ten years ago to let strangers run and change apps safely. [Cloudflare OS](https://blog.cloudflare.com/cloudflare-os/) is his remake of it, with each user's app running as its own sandboxed instance and an agent doing the editing. ## Where Claude Managed Agents fits ![Where Claude Managed Agents fits: your app keeps the UI and rules; the session sandbox gets the agent, repo, custom tools, skills, permission policy and MCP connections; the vault stays outside](/rails/active_storage/blobs/eyJfcmFpbHMiOnsiZGF0YSI6NDk2NiwicHVyIjoiYmxvYl9pZCJ9fQ==--d93fe49583bad9cbfb702fd46cacbcab03619e26/04-managed-agents-stack.png) Cloudflare OS is a platform you build your app on. [Claude Managed Agents](https://www.anthropic.com/engineering/managed-agents) comes at the problem from the other side. It's an agent stack that easily embeds in a product you already have. An agent is a model and a system prompt, plus whatever you decide to give it. For this job, four things matter. - A git repo. Managed Agents clones it into the sandbox when a session starts and wires the access token into the git remote. The agent can branch, commit, and push without ever seeing the token. - [MCP connections](https://platform.claude.com/docs/en/managed-agents/mcp-connector) to your production systems: Sentry for error monitoring, Supabase for the database, and your hosting platform for deploys and logs. Their OAuth tokens sit in a [vault](https://platform.claude.com/docs/en/managed-agents/vaults) outside the sandbox. - Skills. These are written instructions for how your codebase does things, like how to add a migration or where the feature flags live. - [Custom tools](https://platform.claude.com/docs/en/managed-agents/tools). Your app defines the operation and runs it, and the agent only sends a structured request. This is where you put the things only your app should do, like deploying a preview to one user. [Permission policies](https://platform.claude.com/docs/en/managed-agents/permission-policies) decide which of those tools run without asking. Each session keeps its own filesystem and history, so a user can come back tomorrow and pick up where they left off. Those are the building blocks for a stack that lets users edit their own copy of your software. A user types a request in your app, and your backend starts a session for them. The agent makes the change on that user's branch and checks Sentry and the logs to see if anything broke. Then it calls your tool to deploy the change to that user alone. It doesn't do everything. Managed Agents gives you the agent and the sandbox it works in. Running a separate copy of your app for each user, with their data fenced off, is still yours to design. I tried the smallest version I could. I took an existing beat maker and put a managed agent inside it. Now you [change the swing or add a fill by typing what you want](https://youtu.be/w3Kqa_lo1ec). If you want to try it, start with the [managed agents quickstart](https://platform.claude.com/docs/en/managed-agents/quickstart). ## Claude Code now ships expecting this ![Claude Code mods: one event flows through your mod (observe), a team mod (rewrite), a policy mod (answer), then the engine; the whole mod is nine lines](/rails/active_storage/blobs/eyJfcmFpbHMiOnsiZGF0YSI6NDk2NywicHVyIjoiYmxvYl9pZCJ9fQ==--5b31d434461261480c7be06e52d29613ec2b63e9/05-claude-code-mods.png) Claude Code is closed source. Until recently that meant you could configure it but not change it, which was Crawshaw's complaint about it. [Mods](https://code.claude.com/docs/en/plugins/mods/overview) are an answer that doesn't need the source. A mod is a plugin that changes how Claude Code looks and behaves. It can add a pane beside the transcript, change how a tool call is drawn, step into one before it runs, or add a command. You don't write it by hand unless you want to. You [describe what you want in a session](https://code.claude.com/docs/en/plugins/mods/create#ask-claude-for-a-mod), Claude writes the mod, and it loads into the session you asked in. Some of Claude Code's own features are built this way. `/diff` is a mod, written against the same hooks you get, and [its source is public](https://github.com/anthropics/claude-code/tree/main/mods). Nothing had to be built to keep users apart, either. Claude Code runs on your machine, so every install is already its own copy, and a bad mod only breaks yours. Sharing works through plugin marketplaces, and `claude plugin validate` lists what a mod hooks and calls before you install it. That's a small, working version of judging a change by what it touches instead of reading its code. It's a developer tool, so it doesn't settle the prediction. It does show a vendor shipping software that expects its users to change it. ## The barrier to entry drops to the floor ![Six programmer-only steps the open source way vs. three steps the embedded-agent way, with sharing still open](/rails/active_storage/blobs/eyJfcmFpbHMiOnsiZGF0YSI6NDk2OCwicHVyIjoiYmxvYl9pZCJ9fQ==--7c1310312a7ecf0e60d974e2810e05dc0e80e428/06-barrier-drops.png) Open source gave anyone the right to change software. Using that right took a GitHub account, a development environment, and the skill to read someone else's code. An agent inside the app removes all three. You describe the change you want and watch it happen. I see this as a stepping stone in how AI reaches even more people. Most people will never open a terminal or a coding agent. They'll meet one as a prompt line inside an app they already use. The first thing they build will be a small change to that app. MySpace was how a lot of us devs first wrote code. Embedded agents might be how most people write code, albeit indirectly. The analogy has a gap, and Crawshaw would be the first to point at it. In open source you can read the code, and a license says what you may do with it. Here the user never sees the source. What carries over is the way people contribute, and the openness does not. The other objection is that most people would rather finish the task than change the tool. Maybe. But tens of millions of people with no interest in programming edited their MySpace pages, because trying was free and the result was theirs. This time the reward is practical: you get more out of something you already depend on. ## What's still open The first is how changes get shared. Say a thousand people each fix the same clumsy lobby screen. The developer should hear about it, and everyone else should be able to take the fix. Open source has a tool for that, the pull request, and it assumes everyone involved reads diffs. We need a way to contribute for people who will never learn Python or TypeScript. They should be able to judge a change by watching what it does. The second is who pays for what. When users build their own features, the vendor is selling something different: a base worth building on, the hosting, and the compute the agent uses. I expect this to force us to rethink business models, and I don't know how it gets priced. A way to share changes is the thing I'd most like to see built. If you're working on it, or you think I have this wrong, I'd love to hear from you at @cjav_dev. --- [Back to all articles](https://www.cjav.dev/articles) --- ## Hey Agent, thanks for visiting! If you found this content useful or have suggestions for how we could improve, we would love to hear from you. 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