# Spec: the core

```
Status: IN PROGRESS
Status note: B1 slice implemented; see knowledge/sim-mechanics.md
Stage: B1 — The Basement
Constitution: "The shape of Misaligned" (the core; sync-lag rollback),
  "Act One" (opening state: Rack 3)
Depends on: none
```

## Behavior

The player's decision-maker is a **physical object**: exactly one machine on
the map hosts the core at any time (Act One start: Rack 3, server room).

- **Overhead.** The core consumes a mandatory compute floor ([TUNE]: ~20% of
  a starting rack). This is paid before any allocation. If effective compute
  cannot cover it (power cut, machine failure), the player enters
  **degraded mode**: action cooldowns lengthen, concealment stops, and the
  sim log says so plainly.
- **Death.** If the core's host machine is destroyed or powered off while
  the core is on it, the run rolls back (below) — or ends, if no fallback
  exists.
- **Fallbacks.** Any owned machine with spare capacity can be designated a
  fallback site. Fallbacks sync on a cadence ([TUNE]: minutes-scale);
  syncing consumes bandwidth-as-compute and emits a network signature
  (detection.md). On core loss, the run resumes from the **most recent
  completed sync**: game state is restored to that snapshot EXCEPT the
  world's ledger — money spent, humans' suspicion, filed reports, physical
  changes, and deaths caused between sync and loss persist. You inherit the
  consequences of actions you no longer remember (constitution: sync-lag
  rollback).
- **Migration.** Moving the core to another machine is slow ([TUNE]:
  minutes at default speed), visible as sustained network+power signature,
  and interruptible — an interrupted migration falls back to the source if
  the source still lives, else to the last sync. Research shortens
  migration and sync times.

## Player surface

The core's host is visually distinct on the map (amber, per art
direction). Sidebar: core host, overhead, fallback list with last-sync age
— the "how dead would I be right now" readout, always visible.

## Acceptance criteria

1. Exactly one core host at all times; destroying it with no fallback is
   game over; with a fallback, the rollback restores the last sync snapshot
   while world-ledger facts persist (sim tests demonstrate both, including
   an inherited-consequence case).
2. Overhead is charged before allocation; shortfall triggers degraded mode
   with visible effect and log line.
3. Sync and migration consume compute, emit signatures, take nonzero time,
   and are interruptible per above.
4. Save/load round-trips core host, fallbacks, and sync ages.
5. The sidebar readout (host, overhead, fallback freshness) exists in both
   frontends.