MANUAL RUN: Mythic Masters walk together, deploy and play the open world with a friend #3697

About 15 minutes, after #3676 merges: one deploy, then a walk with a friend (a second computer or a phone).

Part of the walking-together climb (#3663 onward; rounds 1 and 2 merged in #3669, rounds 3 to 8 in #3676). The harness has already checked everything it can:

• 37 wire and room tests
• a two-page journey through the running app: seeing each other, landing, a shared hunt, a server drop, frame time
• the cost model

What's left needs your hands: the deploy, and whether it feels like a hunting trip.

1. Deploy (about 5 minutes)

1. cd apps/mythic-masters, then run the deploy plan and read it. It should show two changes:

   • the Worker gains code (src/edge/worker.ts) instead of serving assets only;
   • one new Durable Object class, REGION → Region (SQLite-backed, no storage used).

   Nothing else should change.

2. DEPLOYS=1 AGENTS=1 CHECKS=1 bun run deploy.

2. Play (about 10 minutes)

1. On https://mythic-masters.notryanquinn.workers.dev, sign in with eqosys, open the world, and press Walk together under the region panel.
2. Send the lobby's link to a friend (or open it signed in on your phone). Both press Ready, then you press Start.
3. Check:
   • You both land together.
   • You see each other as your lead beasts, with your line-ups trailing and names over them.
   • It's the same hour and weather on both screens.
   • A flock one of you walks into takes off on both screens.
4. One of you reads a sighting board. Does the other get "You're on it too" and see the same signs?
5. Walk into a wild one. Does the other get the toast? Afterwards, do they hear how the fight went?

Yes if it feels like two people on one trip. No with a note if it doesn't. The likely knobs:

• BEHIND_MS and COAST_MS in src/net/party.ts: smoothness against lag.
• SEND_MS: 5 Hz.
• The chip's text in src/main.ts drawTogether.