> For the complete documentation index, see [llms.txt](https://kerno.gitbook.io/docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://kerno.gitbook.io/docs/references/ports-and-file-paths.md).

# Ports and file paths

### Ports

| Service                                            | Default port | Override           |
| -------------------------------------------------- | ------------ | ------------------ |
| Agent REST API (used by the IDE extension and CLI) | `8085`       | `PORT` env var     |
| MCP server (used by coding agents)                 | `8086`       | `MCP_PORT` env var |

Both ports listen on localhost only and are not reachable from other machines on your network.

If the default port is taken, Kerno auto-allocates a free one. The actual port is always printed in the output of `kerno mcp`. Always copy the URL from the terminal rather than assuming the default.

### File paths

Kerno uses three locations on your filesystem.

#### `~/.kerno/`

Installed agent binaries, runtime state, and per-workspace data.

| Path                                            | Purpose                                             |
| ----------------------------------------------- | --------------------------------------------------- |
| `~/.kerno/assets/agent/{version}/aicore-agent/` | Installed agent JAR                                 |
| `~/.kerno/assets/runtime/{version}/custom-jre/` | Custom JRE bundled with the agent                   |
| `~/.kerno/workspaces/`                          | Per-workspace snapshots and indexed data            |
| `~/.kerno/` (top level)                         | Agent port, PID, workspace, and version state files |

#### `.kerno/` (in your repository)

Per-app directory Kerno creates inside your repository. In a monorepo, each enabled app has its own `.kerno/` under that app's root.

Kerno auto-writes a `.kerno/.gitignore` that ignores `hooks/*` and `mcp-jobs/*`, so you do not need to add anything to your repo's own `.gitignore` for those. The rest of `.kerno/` is intended to be committed alongside your code.

**Persistent state**

| Path                                   | Purpose                                                                                                   |
| -------------------------------------- | --------------------------------------------------------------------------------------------------------- |
| `scenarios/endpoints/<METHOD>/<path>/` | Generated TypeScript scenario files (`*.scenario.ts`), grouped by endpoint                                |
| `analysis/`                            | Markdown reports from Kerno's analysis (workspace, endpoints, environment), reused as context across runs |
| `hooks/`                               | Git hooks Kerno installs in your repo (ignored)                                                           |
| `mcp-jobs/<job_id>.log`                | Logs for in-flight MCP async jobs (ignored)                                                               |

**Build artifacts**

Written when you build the environment for the app. Kerno regenerates them when you apply feedback and rebuild.

| File                             | Purpose                                                                                                                                              |
| -------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------- |
| `Dockerfile`                     | Dockerfile Kerno generates to build your app                                                                                                         |
| `docker-compose.yml`             | Main orchestration compose that ties all services together                                                                                           |
| `docker-compose.sut.yaml`        | Compose definition for your app (the system under test)                                                                                              |
| `docker-compose.<service>.yaml`  | Compose definition for each detected dependency, for example `docker-compose.postgres.yaml`                                                          |
| `docker-compose.ts-sandbox.yaml` | Compose definition for Kerno's sandbox container, which transparently intercepts outbound HTTPS from your app so external APIs can be mocked locally |
| `.env`                           | Environment variables for your app                                                                                                                   |
| `.env.<service>`                 | Environment variables for each dependency, for example `.env.postgres`                                                                               |

#### `/tmp/kerno/`

Temporary working directory for compose projects and scenario workspaces.

| Path                                | Purpose                                 |
| ----------------------------------- | --------------------------------------- |
| `/tmp/kerno/compose/...`            | Generated Docker Compose projects       |
| `/tmp/kerno/scenario-workspace/...` | Working directory for scenario planning |

### Removing Kerno

To stop the agent and remove the installed binaries, run:

```bash
kerno uninstall

This stops the running agent and clears ~/.kerno/assets/ (the agent JAR and bundled JRE). Other state — ~/.kerno/workspaces/, your repository's .kerno/ directory, and any /tmp/kerno/ data — is preserved unless you delete it manually.
```


---

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