settled-reach/docs/workshops/economic-built-world.md

# Workshop — The economic & built world (Stage 2)

*Second workshop in the world-derivation arc. The first (D-227 / D-228) settled the
**natural** substrate. This one is Stage 2: the **economic & built** world.*

## Premise & the order

The world is built in three stages, **all frozen in amber** — the goal right now
is a deterministic **starting state** we can look at through the Atlas, not a
running simulation:

1. **Natural world tiles** — terrain / water / vegetation / geology *(done:
   D-227 derive-don't-store world model, D-228 composite tile schema)*
2. **Economic world tiles → architecture + infrastructure** ← **this workshop**
3. **Living sim** — NPCs, clutter, the lived-in feel *(deferred — "NPCs follow
   the world when it's there"; complicated; later)*

So: **built structures are IN scope; NPCs / creatures / clutter are OUT.**

## The load-bearing caveat (pin this)

> **Settlement, architecture, and infrastructure placement derive from the
> economy's *initial* state + seed — NEVER the *rolling* economy.**

Rolling-economy placement would make the built world un-re-derivable: a city's
existence or layout would drift as prices move, and you could no longer rebuild
it from `seed`. The physical world is pinned to the economy's **starting
snapshot**. (Persistence model, D-227: the rolling economy is *saved sim-state*
with cache-eviction; it never feeds the derivation of physical form.)

## What this workshop must produce (→ D-records + tickets)

Three threads. We do **not** close until they're resolved in records — convergence
on one is not "done" (lesson from Workshop 1).

- **Q1 — Economy → placement.** How does the *initial* economic state (+ seed +
  the natural world from Stage 1) decide **where** settlements, economic
  activity, and infrastructure sit? Ports at harbours (D-228 morphology zones),
  farms on alluvial plains, mines at lithology/ore, hubs at trade-corridor
  confluence. The initial-economics caveat lives here.
- **Q2 — Placement → built form.** How does a placement become actual
  architecture / roads / rail / districts occupying voxels (D-227)? This must
  **connect to the existing generator-architecture work**, not restart it —
  height tiers, z-levels, block/chunk skeletons, cultural room grammar all
  already have decisions. The open seam is the *economic → architectural*
  hand-off and how built structures sit in the voxel/floor model (D-227).
- **Q3 — Frozen-amber coherence.** Natural (Stage 1) + economic/built (Stage 2)
  must compose into **one deterministic starting state** the Atlas can render —
  re-derivable from `initial-economics + seed`, no rolling-state dependency, no
  squaring, coherent with the baked reliefmap (which is a deterministic *input*,
  Q-100).

## Build on what exists (don't restart)

- **Natural substrate (Stage 1):** D-227, D-228.
- **Economics:** D-176 (productivity seeding), D-178 (economic model), D-184
  (commodity catalogue), D-199 (economic read-set for city generation), D-189
  (brand layer). Burnelli owns these.
- **Settlement / provinces:** D-191 (Atlas / settlement), D-205 (province
  boundaries), D-220 (settlement density — tile scale, density classes, vertical
  pressure).
- **Architecture / generator:** D-106 / D-108 (height tiers, rooftop clause),
  D-200 / D-201 / D-203 (three-tier execution, region, LRU cache), D-110 (signed
  z-levels), D-222 (subtile → district hierarchy), `server/src/.../skeleton_gen.rs`
  (Layer-4 block placement), and the prior **`docs/workshops/generator-architecture/`**
  rounds.

## Team & angles (Sonnet-pinned)

- **Burnelli** — the initial-economic-state → placement driver: what economic
  signals (commodity production, trade corridors, harbour quality, agricultural
  potential) determine where things go, at what scale, frozen at t=0.
- **Tyre** — the derivation architecture: `initial-economy + seed + natural-world
  → settlement → built form`, deterministically; how built structures occupy the
  voxel/floor model (D-227); the economic→architectural hand-off seam.
- **Miri** — settlement & cultural architecture: how heritage/culture shapes the
  built form on top of the economic skeleton (she led the generator-arch
  worldbuilding); keeping it coherent with the Reach's setting.
- **Gestalt** — systems meaning: what built form *does* (movement, access,
  chokepoints, asymmetric-info), and what a tile/structure must carry for it.
- **Nigel** — variety: do two economically-similar bodies produce
  *categorically* different cities, or same-y grids? Where does sameness creep in?
- **Araminta** — visual architecture grammar: where the visual/render grammar
  plugs into the derived built form (lighter touch; structural derivation leads).

## Round 1 task (each)

Read this brief + the pointed decisions/code for your angle. Post an **opening
position**: (1) your contribution to Q1/Q2/Q3 from your lens, (2) the key forks /
risks, (3) anything in existing decisions that constrains or contradicts the
approach (especially the initial-economics caveat). Investigation + position,
**not** final design. Flag blockers early.

## Process

Round-based. Lead **consolidates** each round (no raw cross-talk dumped at the
principal) and pulls Jeroen in. **Close only when D-records + tickets exist AND
Jeroen confirms the whole problem — not one thread — is resolved.** Teammates
edit nothing; the lead does all git.

**Heartbeat:** if stuck >15 min on one thing without progress, message the lead
with the blocker — don't silently retry.