LogBear — local dev server logs for agents

Your coding agent can't see your dev server crash.

LogBear gives coding agents — Claude Code, Codex, pi and Hermes — your local dev server logs. It wraps a development process, records everything it emits, and tells your agent the moment something breaks.

logbear mix phx.server

That is the whole interface. Your terminal behaves as it did before — colours, IEx.pry, Ctrl-C, resize — and everything the process prints is now queryable, diffable, and visible to an agent that would otherwise have no idea it happened.

Contents

• The problem it solves
• What you get
• Install · Uninstall · Platform support
• Using it
• How it works — constraints, capture, storage, MCP, loop safety, privacy
• Repository layout
• Building from source
• Contributing · Security · Licence

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The problem it solves

You are working with a coding agent. It edits code. Your dev server, running in another terminal, throws an exception. The agent has no idea, and reports "done, fixed it". You have to notice the error, copy it, paste it back, and restart the conversation.

We couldn't find anything else that closes that loop:

	Sees	Doesn't see
Framework log viewers	logs, when asked	never tells the agent something broke
Claude Code's background bash	processes it started itself	anything else, and no history
Sentry / Datadog	production exceptions	your local dev loop
Loki / Splunk	log streams at fleet scale	run boundaries, git context
Atuin	command, exit code, duration	the output
pm2 / overmind	supervises and tails	stores nothing queryable

LogBear sits at the point of invocation, which is the only place where the command and the context that produced it are visible together, for free, at the same instant.

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What you get

A blocking hook. When your agent says it is finished, LogBear checks whether anything broke since it last looked. If so, the agent is interrupted and handed the actual exception, its history, and which run it came from. If not, nothing happens at all.

A queryable history. Every run is stamped with its git SHA, branch, a hash of the uncommitted changes, and the hash of every lockfile. logbear diff answers "what changed" with the commits in between, the lockfiles that moved, and the error signatures that appeared.

A read-only SQL endpoint for agents, rather than a fixed menu of tools. An agent can ask "which error signatures appear in every failed run but no successful one" — a question no canned tool would have anticipated.

A desktop app for the human: live tail, run history, error signatures with sparklines, and the diff view.

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Install

Homebrew — CLI, daemon, MCP server and hook:

brew install teralabx/tap/logbear
brew services start logbear
logbear setup             # connect your coding agents

It installs prebuilt binaries, so there is nothing to compile and no Rust to install. It lives in its own tap until it qualifies for homebrew-core; Homebrew may ask you to brew trust the tap the first time. See packaging/homebrew.

Install script — the same four binaries, prebuilt, into ~/.local/bin:

curl -fsSL https://raw.githubusercontent.com/teralabx/logbear/master/install.sh | sh
logbear setup             # connect your coding agents and start the daemon

The script checks each download against the SHA-256 published with the release and changes nothing else on your machine. Read it first if you like: it is install.sh.

Cargo — the same four binaries, built from source:

cargo install logbear logbeard logbear-mcp logbear-hook
logbear setup

logbear setup finds Claude Code, Codex, pi and Hermes, shows exactly which files it would change, and asks before touching anything.

The desktop app is the easiest path, because it is also the installer. On first launch, without asking, it does the two local steps it cannot work without:

1. links logbear onto your PATH. If no writable directory is already on your PATH, it links into ~/.local/bin and adds a marked block to your shell profiles, backing each one up first
2. registers logbeard as a background service that survives reboots, which on macOS means a LaunchAgent

Your agents are left alone until you ask. Settings → Install has a button for each of the rest, or one for all of them:

3. the MCP server registered with each agent it finds: Claude Code, Codex, pi and Hermes
4. the hook installed in each of them

pi has no command hooks, so for pi the "hook" is a small extension written to ~/.pi/agent/extensions/logbear.ts. Hermes gets two shell hooks in ~/.hermes/config.yaml, added between marker comments so removing them leaves the rest of the file alone.

Every config file is backed up before it is touched, every write merges rather than overwrites, and each step can be reverted individually. A config that won't parse is refused with an error and left exactly as it was.

logbear doctor reports the state of every integration and tells you how to fix whatever is broken. It checks pi and Hermes only where they are installed.

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