Emdash keeps agents apart. Synapse lets them talk when you want them to. Emdash (emdash.com) is a desktop app that gives every task its own git worktree, terminal and conversation, with diffs, PRs, CI checks, issue intake and automations, for 35 CLI agents on macOS, Windows and Linux. Its agents do not share context or message each other, and its founders have said they leave orchestration to the CLIs. Synapse draws live links between running agents so B gets A's recent conversation on every prompt, and lets any two linked agents message each other. Emdash is far more complete as a workspace. You can run both.
At a glance
| Synapse | Emdash | |
|---|---|---|
| What it is | Canvas and messaging layer for every agent on your machine, plus a desktop app in development | Desktop "agentic development environment" for parallel CLI agents in worktrees |
| License | MIT, open source | Apache-2.0, open source (MIT until early 2026) |
| Price | Free | Desktop app free; Cloud and Enterprise by contact, no public prices |
| Account | None | Not required; optional Emdash account with GitHub sign-in |
| Telemetry | None, no network calls | PostHog, on by default, coarse usage events, can be disabled |
| Live context links between running agents | Yes, directional, every prompt | No |
| Agent to agent messaging | Yes, any linked agents, across CLIs | No |
| Sees agents it did not launch | Yes, by process scan | No, only its own tasks |
| Session forks | In development (Claude Code, Codex) | Request for forking closed as not planned |
| Agents | Claude Code, Codex, Gemini CLI, OpenCode, Cursor Agent, Amp, Copilot CLI | 35 CLIs on its providers page |
| Diffs, PRs, CI, issue intake, automations, SSH remotes | No | Yes |
| Platforms | macOS (core runs anywhere Node 18 runs) | macOS, Windows, Linux, plus remote machines over SSH |
Emdash facts are from emdash.com, its docs, its GitHub repo, releases and issues, and its Show HN thread, checked on 16 October 2026.
What Emdash is
Emdash is made by General Action (Y Combinator W26). It is an Electron app for running many coding agents at once. Each task is a git worktree with a branch, a terminal and a conversation, or it can open an existing workspace. You can talk to each agent in its own terminal UI or in an ACP based chat view, and switch between the two per agent.
Around that it has a diff view, commit, push, PR creation, CI checks and merge. It pulls issues from Linear, GitHub, Jira, GitLab and more, runs scheduled automations, keeps a library of prompts, skills and MCP servers synced to your agents, and supports remote development over SSH with a workspace server. Its providers page lists 35 CLIs, from Claude Code, Codex and Amp to Goose, Droid and Qwen Code. We did not find Gemini CLI on the current providers page.
It ships fast (v1.2.8 on 10 October 2026, with releases roughly weekly) and has about 6,000 GitHub stars.
What Synapse is
Synapse is about what happens between agents. It puts every live coding agent on your machine on a canvas, grouped by git repo, with worktrees grouped under their main repo. Drag a line from agent A to agent B, and on every prompt B gets what A has said since last time, up to 8,000 characters per link. Any two linked agents can message each other through six MCP tools, a CLI or a skill, so Claude Code can ask Codex a question and get the answer in its inbox.
It finds agents by scanning processes, so there is nothing to wrap.
Can Emdash agents talk to each other?
No. Isolation is Emdash's design goal, and its task docs describe worktrees as a way to "prevent agents from interfering with each other." Precisely:
- There is no documented way for task A's conversation to reach task B, and no agent to agent messaging, mailbox or shared transcript.
- Asked on Hacker News about an orchestrator agent, a founder replied that "this is something that the CLIs themselves are getting good at natively" and described Emdash as working "at a higher abstraction / task level."
- An open request (#2937) asks for a local MCP server so agents could list and create tasks themselves. That would be task management, not context sharing, and it has not shipped as of v1.2.8.
- What you can do by hand: attach issue tickets, diff comments (with
@) and library prompts to a chat, and sync the same MCP servers to every agent.
Synapse adds the missing piece. A link from A to B stays in place until you remove it. Draw both ways for a pair. Either agent can message the other, across CLIs, without a coordinator.
Forks
A request for session forking between Emdash tasks and the Claude Code CLI (#1629) was closed as not planned in April 2026.
Synapse's desktop app, in development, adds forks for side questions. Type /sfork <question> in Claude Code or Codex, or press ⇧⌘F, and Synapse forks the session natively (claude --resume <id> --fork-session or codex fork <id>) into a card stacked on its parent. The question never enters the parent's context. The fork shows on the canvas as a dashed line to its parent, and the child reports back only if you ask.
Open source, accounts and privacy
Both are open source. Emdash moved from MIT to Apache-2.0 around April 2026, and its founders have said the UI layer "is and will be open-source." Synapse is MIT.
Emdash does not need an account for core use, though an optional Emdash account with GitHub sign-in exists. Production builds send coarse usage events to PostHog by default, which you can turn off in settings or with TELEMETRY_ENABLED=false. Its README says it "does not send your code or chats to Emdash servers."
Synapse has no account, no telemetry and makes no network calls. Links and messages live in ~/.synapse.
Where Emdash is ahead
- The full ship loop. Diffs, PRs, CI checks, merge, issue intake from many trackers, scheduled automations, an in-app browser and an editor with language servers. Synapse does none of this.
- Platforms. macOS, Windows and Linux, plus remote machines over SSH and a cloud offering. Synapse is macOS first.
- Agent coverage. 35 providers against Synapse's seven.
- Maturity and pace. A stable v1, weekly releases and a funded team. Synapse is a young project and its desktop app is not released yet.
If you want one app that takes a task from issue to merged PR across many agents, Emdash is the stronger choice today.
Using Synapse with Emdash
- Keep Emdash for tasks, worktrees, PRs and CI.
- Install Synapse:
node install.mjs && npm start. - Run agents in Emdash's terminal (TUI) mode. Those run as normal CLI processes, which Synapse's process scan is built to find. Agents in the ACP chat view may not run as a normal CLI process, so they may not show up or receive context.
- Restart agents that were already running so they load Synapse's MCP server and hook.
- Link a reviewer task to an implementer task on the canvas, or let agents in two Emdash worktrees message each other about a shared interface.
Who should pick which
- Pick Emdash if you want an open-source workspace that runs many agents across platforms and takes their work to a merged PR.
- Pick Synapse if your agents need to share what they know, you want Gemini CLI in the mix, or you want a tool with no telemetry and no network calls.
- Run both if you want Emdash's isolation and agents that can talk when you decide they should.
FAQ
Is Synapse an Emdash alternative?
For connecting agents, yes. Synapse adds live context links and messaging between running agents, which Emdash does not offer. For worktrees, PRs, CI and issue intake, no. Synapse is meant to run alongside a workspace like Emdash.
Can Emdash agents share context with each other?
No. Emdash isolates each task in its own worktree and has no mechanism for one task's conversation to reach another, and no agent to agent messaging. You can attach issues, diff comments and saved prompts to a chat by hand. Synapse injects one agent's recent conversation into another on every prompt.
Is Emdash open source?
Yes. Emdash is open source under Apache-2.0 since around April 2026, and was MIT before that. The desktop app is free. Synapse is open source under MIT.
Does Emdash collect telemetry?
Yes, by default. Production builds send coarse usage events to PostHog, and Emdash says no code or prompts are included. You can disable it in settings or with TELEMETRY_ENABLED=false. Synapse makes no network calls.
Does Emdash support Gemini CLI?
We did not find Gemini CLI on Emdash's current providers page, which lists 35 other CLIs. Synapse supports Gemini CLI: it shows up on the canvas, its context is readable and it can message other agents.
Does Synapse see agents running inside Emdash?
Agents in Emdash's terminal mode run as normal CLI processes, which Synapse's process scan finds. Agents in Emdash's ACP chat view may not run that way, so they may not appear. Check the canvas after setup.