Junie for Hermes Agent

Run Junie as a model provider inside Hermes Agent.

Hermes spawns junie --acp=true and talks to it over the Agent Client Protocol, so Junie shows up in /model and --provider like any other backend — while still running its own tools inside its own session.

This is a Hermes plugin, not a fork: installing it changes nothing in Hermes itself.

Install

You need the Junie CLI first — follow the quickstart, or the install instructions in this repository's README. Verify with junie --version.

Then authenticate — a JetBrains account, a Junie API key, or your own model provider (BYOK). See the authentication docs.

Install the plugin:

hermes plugins install JetBrains/junie/hermes-plugin

Or drop it in by hand: copy this hermes-plugin/ directory to ~/.hermes/plugins/junie-acp/.

The installer finishes with "Plugin installed but not enabled" — that gate belongs to Hermes' general plugin surface (hooks, tools, the bundled delegation skill). The provider itself is available immediately: model-provider discovery is a separate path. Run hermes plugins enable junie-acp if you also want the skill.

Requires Hermes v2026.9.7 or newer — that release added the provider registration seam this plugin is built on.

Hermes needs its acp extra for the protocol SDK — see Hermes' installation docs for how to add an extra to your install.

Use

hermes --provider junie-acp chat
hermes -m junie                      # alias

/model lists the models Junie advertises over the session — the plugin asks the running agent rather than a REST catalog, so you get whatever your account actually has.

Configuration

Behaviour goes in config.yaml under junie_acp:. Credentials stay in the environment.

junie_acp:
  command: junie                     # path to the CLI
  args: ["--acp=true", "--skip-update-check"]
  permission: deny                   # deny | allow — how to answer Junie's permission prompts
  brave: ""                          # on | off — override Junie's Brave Mode; empty keeps Junie's own setting
  forwarded_tools: []                # all | none | [memory, todo, ...]; empty = the default allowlist

Environment variable	Overrides
`JUNIE_API_KEY`	Auth token passed to the CLI as `--auth` (a credential — env only)
`HERMES_JUNIE_ACP_COMMAND`, `JUNIE_CLI_PATH`	`command`
`HERMES_JUNIE_ACP_ARGS`	`args`

Env vars win over config.yaml — they are the narrower scope, meant for a one-off run.

hermes config set junie_acp.<key> may not recognise the path, because an out-of-tree plugin cannot declare config keys in Hermes' schema. Edit config.yaml directly; reading works normally.

`permission`

Junie asks for consent before acting when its own Brave Mode is off. deny (the default) refuses every request, so Junie cannot act without explicit consent. allow approves once. This is the seam a future Hermes-approval bridge would replace.

`forwarded_tools`

Junie is an autonomous agent with its own read/edit/execute tools, so the plugin forwards Hermes' agent-level tools only — memory, todo, the skills toolset and friends. Re-offering the overlapping ones would make Hermes re-run work Junie already finished.

That default set is what keeps Hermes' self-improvement loop alive on this provider: the background-review fork needs those exact tools to write memories and skills. Narrow it and the review can only act on what remains.

How it works

Junie's own tool calls never come back to Hermes as pending tool_calls — Hermes would re-run finished work. Instead the plugin projects them into the transcript as completed assistant(tool_calls) + tool(result) rows, namespaced junie_*, and reports how many tool iterations happened inside the session. That keeps two Hermes subsystems working: the self-improvement loop, which distils memories and skills by replaying the transcript, and the skill-review nudge, whose counter only moves on tool iterations.

Hermes' own tools reach Junie through the ACP text bridge — ACP has no OpenAI tools channel, so the schemas travel into the prompt as text and <tool_call> blocks are parsed back out.

Everything the plugin uses is public Hermes provider-plugin API; see External-process (ACP) providers in the model provider plugin guide.

Safety

The plugin is the ACP client, so file access from Junie goes through it:

fs/read_text_file and fs/write_text_file are confined to the working directory
writes to Hermes-protected files are refused
reads are redacted for secrets
the subprocess environment is built with Hermes' hermes_subprocess_env, so tier-1 secrets are stripped
permission requests are denied by default

Development

With Hermes (including its acp extra) available:

PYTHONPATH=/path/to/hermes-agent python -m pytest hermes-plugin/tests -q

The client suite runs end-to-end against a real ACP agent subprocess (tests/fake_junie_acp_agent.py) built on the same SDK, so the protocol wiring is under test rather than mocked.

License

See LICENSE.md in the repository root.