Polar Local Environment Agent Skill

Local Environment Skill

Helps manage the Polar local development environment through the dev docker

CLI. Use it to start, stop, debug, or reason about the local stack.

The two-part model

dev docker deliberately splits the stack so many worktrees can share one set

of heavy infra:

• Shared infra — one copy per machine, Docker project polar-shared:

postgres, redis, minio, tinybird, and optional prometheus/grafana. Postgres

and redis publish no host ports; MinIO exposes 9000/9001 for browser

uploads. Use dev docker exec <service> ... for services without host ports.

• Per-instance app stack — one per worktree, project polar-app-<N>: api,

worker, web. Only api and web publish host ports, offset per instance so

worktrees don't collide.

Knowing this prevents the most common confusion: there is no localhost:5432

for the database (it lives in the shared stack and is reached through

dev docker exec db ...). MinIO does expose ports 9000/9001 for browser

uploads and console access.

Instance auto-detection

dev docker auto-detects the instance for the current worktree, so -i is

rarely needed. Priority:

• POLAR_DOCKER_INSTANCE pinned in dev/docker/.env.docker (dev docker set-instance N)
• CONDUCTOR_PORT env var → (port - 55000) / 10 + 1
• The cross-worktree registry (~/.config/polar/docker-instances.json)
• Otherwise the lowest free number, then registered

Run dev docker ports to see the resolved instance and its URLs (add --json

for tooling). To wire this worktree into Claude Code's preview, run

dev docker launch-json, which writes a per-instance .claude/launch.json with

the correct ports (it's gitignored, so regenerate after set-instance).

When to use

• Start / stop / restart the local environment
• View logs or debug a service that won't come up
• Run several isolated worktree instances in parallel
• Understand the service architecture or find a service's real port
• Diagnose container or first-boot errors

Quick reference

| Task | Command |

|------|---------|

| Start full stack (background) | dev docker up -d |

| Start and block until healthy | dev docker up -d --wait |

| Start in foreground (stream logs) | dev docker up --no-detach |

| Rebuild with fresh base images | dev docker up -b --pull -d |

| Show this instance's ports/URLs | dev docker ports (--json for tooling) |

| Write Claude Code preview config | dev docker launch-json |

| Stop app stack | dev docker down |

| Stop app and shared infra | dev docker down --all |

| Follow logs | dev docker logs -f [service] |

| Print logs and exit | dev docker logs --no-follow [service] |

| Status | dev docker ps |

| Restart a service | dev docker restart <service> |

| Shell into a service | dev docker shell <service> |

| One-off command in a service | dev docker exec <service> <cmd> |

| Reset this instance | dev docker cleanup -f |

| Wipe ALL shared data | dev docker cleanup --all -f |

| List every instance | dev docker list |

| With monitoring | dev docker up --monitoring -d |

Services

| Service | Project | Host port (instance 0 / N) | Notes |

|---------|---------|----------------------------|-------|

| api | polar-app-<N> | 8000 / 8100+N | FastAPI; /healthz healthcheck |

| web | polar-app-<N> | 3000 / 3100+N | Next.js; healthchecked |

| worker | polar-app-<N> | none | Background jobs |

| db | polar-shared | none (exec) | PostgreSQL; DB polar_dev_<N> |

| redis | polar-shared | none (exec) | Redis DB index = N |

| minio | polar-shared | 9000, 9001 | S3; buckets polar-s3-<N>; console at 9001 |

| tinybird | polar-shared | none (exec) | Analytics |

| prometheus / grafana | polar-shared | none (exec) | --monitoring only |

Discover the exact host ports for the current worktree with dev docker ports.

Instance port mapping

Only api and web get host ports: Port = Base + Instance (Base 8100 for api,

3100 for web) for instances 1–99. Instance 0 uses the legacy 8000 / 3000.

| Instance | API | Web |

|----------|-----|-----|

| 0 | 8000 | 3000 |

| 1 | 8101 | 3101 |

| 2 | 8102 | 3102 |

| 5 | 8105 | 3105 |

Everything else is per-instance but not on a host port: database polar_dev_<N>,

redis DB index <N>, buckets polar-s3-<N> / polar-s3-public-<N>. Reach them

via dev docker exec <service> or docker exec polar-shared-<service>-1.

Rules index

| Rule | Category | Description |

|------|----------|-------------|

| service-architecture | Reference | Service details, ports, healthchecks |

| start-environment | Operations | Starting the stack (flags, --wait, --pull) |

| stop-environment | Operations | Stopping and cleanup (app vs shared) |

| manage-instances | Operations | Parallel worktree instances |

| view-logs | Debugging | Viewing service logs |

| shell-and-workflows | Operations | Shell access and common dev workflows |

| troubleshooting | Debugging | Common errors and fixes |

| payment-testing | Operations | Login codes, Stripe webhooks, backoffice |