gantry: Skill for Claude Code

Mock Mode — Gantry Server

Mock mode swaps the real GameClient for MockGameClient (server/src/proxy/mock-game-client.ts), which returns canned JSON and simulates lightweight per-agent state (credits, fuel, cargo) in memory. No game account, no network call to game.spacemolt.com, no fleet-credentials.json required. Full config reference: docs/mock-mode.md. This skill covers enabling it correctly, what's real vs faked, and how it's used in tests — so you never need to point a dev instance at a real fleet just to check a change.

Enabling it

Two independent mechanisms, with a precedence rule (server/src/config/fleet.ts::loadConfig()):

# Env var — zero gantry.json changes, best for CI / quick local checks
GANTRY_MOCK=1 bun dist/index.js

// gantry.json — fine-grained control, wins over the env var
{ "mockMode": true }
// or the object form:
{ "mockMode": { "enabled": true, "responsesFile": "./my-responses.json", "tickIntervalMs": 0, "initialState": { "credits": 10000, "fuel": 100 } } }

Precedence, verified in fleet.ts: if mockMode is present anywhere in gantry.json (including explicitly { enabled: false }), that value wins outright — the env var is never consulted. GANTRY_MOCK=1 only takes effect when the mockMode key is absent from the config file entirely. This means setting mockMode: { enabled: false } in gantry.json will keep a dev server pointed at the real game server even with GANTRY_MOCK=1 set — a common trap if you copy a teammate's config that has mock mode explicitly disabled.

env.ts: export const GANTRY_MOCK = process.env.GANTRY_MOCK === "1" — only the literal string "1" activates it; "true" does not.

What else mock mode skips at startup (server/src/index.ts)

Two startup side-effects are gated on !config.mockMode?.enabled and silently skipped in mock mode, on top of the game client swap itself:

• Credential validation (validateAllCredentials) — normally does an advisory login against the real game API on startup even when validateCredentialsOnStartup isn't explicitly false; skipped entirely in mock mode.
• Catalog fetch (fetchAndCacheCatalog) — normally fetches items/recipes/ships from the real game API (24h file cache); skipped in mock mode.