Running Multiple Agents on One Repo Is Harder Than It Looks

2025-09-176 min read
multi-agentdeveloper-workflowcoordinationagentic-coding

Five IDEs. Three or four agents per IDE. One developer keeping track of all of them.

That's not a productivity hack. That's a coordination job.

The illusion of parallelism

You want to run multiple agents on the same codebase. One handles refactoring, another writes tests, a third tackles documentation. They should run in parallel, right?

The git workspace is the obvious coordination point. Agents need to avoid conflicting edits. But git is the easy part.

The harder problem is everything else: local databases, migrations, running servers, environment state. If one agent runs a migration and another expects the old schema, you're debugging phantom failures. If both try to spin up the same dev server, one wins and the other gets a port conflict that looks like a code bug.

"I think there are more shared resources than just the git workspace. If you're doing anything with a local database or migrations or trying to run a server, you might have the illusion of being able to run multiple things locally, but in practice you would need to be thoughtful about it."

Matt,

The illusion is that parallelism is free. The reality is that shared resources beyond git create implicit dependencies between agents.

The workaround that works today

One pattern that works, if you're willing to pay the coordination cost: open multiple IDEs, run separate agents in each, keep the context separation yourself.

"I have probably five IDEs open right now. In each of them I probably have three or four agents that I'm actively bouncing between in that particular repo because I do a lot of systems thinking. I'm the one keeping the context separate. I'm making sure they aren't stepping on each other."

Adam,

The cost is manual coordination. You become the orchestrator. You're tracking which agent is working on which branch, which one might touch the database, which one needs the server running. And at the end, you're the one rebasing.

This works. It's not elegant. It scales with your attention span, not with your compute budget.

The tradeoff

Parallel agents on one repo is a coordination problem, not a compute problem.

If your tasks are purely file-based with no shared runtime state, parallelism is straightforward. Branch per agent, merge at the end. But the moment you have a local database, a running server, or migration state, you need isolation that goes beyond git branches.

ApproachCoordination costSetup complexityBest for
Single agent, sequential tasksNoneMinimalSimple workflows, small changes
Multiple IDEs, manual trackingHigh (your attention)LowPower users who can context-switch
Containerized environmentsLowHighTeams needing true isolation
Cloud agents with isolated stateLowMediumParallel tasks with merge at end
Sequential executionNoneMinimalAvoiding conflicts entirely

None of these is free. The question is which cost you want to pay: your attention, your infrastructure complexity, or your time.

Why this matters for your team

For a five-person team running multiple agents, the coordination overhead is invisible until it isn't. The first time two agents step on each other's migrations, you lose an hour debugging a problem that looks like a code bug but is actually a state conflict.

The pattern that might emerge: local and cloud agents becoming more analogous.

"Maybe you imagine a world where local and the cloud were a little more analogous to each other, where you can just kick things off in either direction and they run in parallel."

Matt,

If cloud agents run in isolated environments by default, the coordination problem shifts from "how do I keep agents from stepping on each other" to "how do I merge their outputs."

That's a rebase problem. Rebase problems are solvable.

How Roo Code handles multi-agent coordination

Roo Code addresses the parallel agent problem through intentional design choices. With BYOK (bring your own key), you control your token spend across multiple agents without platform markup getting in the way of running more agents.

The key capability is that Roo Code closes the loop: it proposes changes, runs commands and tests, and iterates based on results. This means each agent instance can validate its own work before you need to coordinate merges. When an agent can run tests and catch its own breaking changes, you spend less time debugging state conflicts caused by blind parallel execution.

For teams exploring multi-agent workflows, Roo Code's approval system lets you maintain human oversight without becoming the full-time orchestrator. You review diffs and approve commands intentionally, keeping agents from stepping on shared resources without constant manual monitoring.

The first step

Before running multiple agents in parallel, audit the shared resources in your workflow. Git is obvious. Databases, servers, and environment state are where the real conflicts hide.

If you can't isolate the runtime state, isolate the agents by running them sequentially. The slowdown is real, but the debugging time you save is worth it.

Frequently asked questions

Agents share more than just the git workspace. Local databases, migration state, running dev servers, and environment variables create implicit dependencies. One agent running a migration while another expects the old schema produces failures that look like code bugs but are actually state conflicts.
Sequential execution eliminates coordination overhead entirely. One agent completes its task before the next begins. You lose parallelism but avoid the debugging time spent on state conflicts. For teams without containerized environments, this is often the practical choice.
Roo Code closes the loop by running tests and iterating on failures within each agent instance. This self-validation reduces the chance of merging broken changes. The approval system also lets you control which agents can run commands that affect shared resources like databases or servers.
Yes, branch-per-agent is the minimum isolation strategy. It handles file conflicts at merge time. But branches alone don't isolate runtime state. If your workflow involves databases or running servers, you need additional isolation through containers or sequential execution.
Containerization pays off when you have multiple developers running multiple agents with shared runtime dependencies. The setup cost is high, but each agent gets isolated database state, its own server ports, and independent migration history. Teams with complex local environments benefit most.

Stop being the human glue between PRs

Cloud Agents review code, catch issues, and suggest fixes before you open the diff. You review the results, not the process.