Windows: buzz-acp is not shipped by the installer — every agent fails with "ACP harness command buzz-acp was not found"

[Mimo314]

Summary
The same account works on macOS and fails on Windows. I installed Buzz on a Mac first, created my account and workspace there, and the built-in agents worked correctly. I then installed Buzz Desktop 0.5.3 on Windows and signed in with that same account. The agent definitions synced over, but on Windows no agent can start. Every mention fails with:
Could not start agent mentions: Fizz: ACP harness command buzz-acp was not
found. Build the workspace binaries (cargo build --release --workspace) or add
target/release to PATH as described in TESTING.md.; Honey: ACP harness command
buzz-acp was not found. Build the workspace binaries (cargo build --release --workspace) or add target/release to PATH as described in TESTING.md.
The error tells the user to build the workspace with cargo, which is developer guidance. There appears to be no way for someone who installed the released .exe to obtain buzz-acp.
Environment
Buzz Desktop 0.5.3 (Buzz_0.5.3_x64-setup_alpha-unsigned.exe)
Windows 10 Pro 22H2 (10.0.19045), x64
Bundled Node runtime: v24.18.0
Fresh install, no prior Buzz version, no Rust toolchain on the machine
Steps to reproduce
Install Buzz on macOS, create an account and workspace, confirm the built-in agents (Bumble / Fizz / Honey) respond. They do.
Install Buzz Desktop 0.5.3 on Windows from the released installer.
Sign in with the same account. The agent definitions sync over.
Mention any agent in a channel from the Windows machine.
The error above appears; no agent ever responds.
Since the agents were provisioned on macOS, their stored acp_command is buzz-acp — which is presumably fine there, but has nothing to resolve to on Windows.
What I verified
The ACP adapters install correctly. Buzz's own installer flow succeeded for both runtimes — %APPDATA%\Buzz\agents\logs\install-claude.log shows:
=== install run runtime=claude app=0.5.3 os=windows
$ npm install --global --prefix 'C:\Users<user>\AppData\Roaming\Buzz\node-tools' @agentclientprotocol/claude-agent-acp
added 104 packages in 23s
Both adapters are present and self-contained:
%APPDATA%\Buzz\node-tools\claude-agent-acp.cmd (bundles its own claude.exe via @anthropic-ai/claude-agent-sdk-win32-x64)
%APPDATA%\Buzz\node-tools\codex-acp.cmd (bundles its own @openai/codex-win32-x64)
The agent config points at both layers, and only the outer one is missing. In %APPDATA%\xyz.block.buzz.app\agents\managed-agents.json, every agent has:
"acp_command": "buzz-acp",
"agent_command": "claude-agent-acp", // "codex-acp" for the Codex-backed agents
So agent_command resolves fine; acp_command does not.
buzz-acp does not exist anywhere. Searched %LOCALAPPDATA%\Buzz, %APPDATA%\Buzz, %APPDATA%\xyz.block.buzz.app, ~/.buzz and the npm prefix — no buzz-acp in any form. The install directory contains exactly one file:
C:\Users<user>\AppData\Local\Buzz\buzz-desktop.exe (83.6 MB)
It is not installable as a package either. npm view returns nothing for buzz-acp, @buzz/acp, @block/buzz-acp, @blockxyz/buzz-acp or @agentclientprotocol/buzz-acp.
Installing the global claude and codex CLIs (2.1.220 / 0.146.0, both on PATH and working) makes no difference, which is expected — the failure happens before either is reached.
Expected
An account that works on macOS should work on Windows. Either the Windows installer ships buzz-acp alongside buzz-desktop.exe, or the app installs it the same way it installs the ACP adapters, or the error message points at a path a non-developer can actually follow.
Note
The error text references TESTING.md and cargo build --release --workspace. For someone installing a released build, that is a dead end — it requires cloning the repository and setting up a Rust toolchain.
This may be related to #2342 and #2343 (Windows adapter resolution), but those are about the adapter layer, which works here; this is the harness layer above it.