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+# CITY-OSTIA-0001
+## Ostia Substrate — Origin City for OTIVM
+### Status: Canonical City Seed
+### Layer: OTIVM (Roman Merchant)
+### Purpose: Establish the simulation substrate for Ostia as origin city, social field, logistics node, and scenario environment
+### Repository Path: docs/cities/CITY-OSTIA-0001.md
+
+---
+
+## 0. Design Intent
+
+This document defines Ostia as a working simulation environment.
+
+It is not a tourist description and not player-facing prose. It exists to give scenarios, actors, costs, routes, and social encounters a grounded urban substrate.
+
+Ostia must support:
+
+- the MERCATOR's starting condition
+- the six starting backgrounds
+- SCENARIO-MERCHANT-0000, the prologue conversation
+- SCENARIO-MERCHANT-0001, the bronze forge fire
+- Route I, Ostia -> Capua
+- future finance, storage, labor, and reputation mechanics
+
+Ostia is the first city the participant must learn to read.
+
+---
+
+## 1. Canonical Identifier
+
+| Field | Value |
+|---|---|
+| City ID | `CITY-OSTIA-0001` |
+| City Token | `ostia` |
+| Roman Name | OSTIA |
+| Modern Location | Ostia Antica, Lazio, Italy |
+| Role | origin city / port / grain and cargo interface |
+| Default Epoch | `roman_14bce` |
+| Primary Route | Ostia -> Capua |
+| Repository Path | `docs/cities/CITY-OSTIA-0001.md` |
+
+---
+
+## 2. Chronological Scope
+
+Default scenario epoch is approximately 14 BCE.
+
+This matters because many of the most visible excavated features of Ostia belong to later Imperial development, especially the Trajanic and Hadrianic phases. The city substrate must therefore distinguish:
+
+| Feature | 14 BCE Use |
+|---|---|
+| Republican colony and port function | admissible |
+| Tiber mouth logistics | admissible |
+| Via Ostiensis connection to Rome | admissible |
+| early warehouses / storage | admissible, but scale uncertain |
+| dense later Imperial warehouse landscape | later analogue only |
+| major later bath complexes | later analogue unless dated earlier |
+| Claudian / Trajanic Portus system | not yet built |
+| 2nd c. CE peak population estimates | upper-bound analogue, not 14 BCE fact |
+
+Rule: use later Ostian archaeology as structural analogy only when explicitly tagged.
+
+---
+
+## 3. Historical Basis
+
+Ostia was Rome's river-mouth port and a key interface for grain, salt, military, and commercial movement. It stood at the Tiber mouth, connected to Rome by river traffic and the Via Ostiensis.
+
+Evidence basis:
+
+- mid-to-late Republican Ostia became important to Rome's food-supply system
+- first warehouses at Ostia are dated to the 1st century BCE
+- city walls were constructed between 63 and 58 BCE and enclosed roughly 70 ha
+- major Imperial horrea are better documented for the 1st and 2nd centuries CE
+- later peak population estimates cluster around tens of thousands, commonly 36,000 to 60,000 for the 2nd century CE
+- baths in Ostia were major social infrastructure in later visible archaeology
+
+Confidence: Medium for general urban role.  
+Confidence: Low to Medium for quantitative 14 BCE population and prices.
+
+---
+
+## 4. Population Model
+
+Population must be treated as a range, not a fixed number.
+
+Later Imperial peak estimates cannot be directly applied to 14 BCE. For simulation purposes, use population bands.
+
+| Population Component | 14 BCE Working Range | Confidence | Notes |
+|---|---:|---|---|
+| permanent residents | 8,000–20,000 | Low | inferred from urban area and pre-Imperial development |
+| enslaved population | 20–40% of resident population | Low | varies by household, warehouse, workshop |
+| transient sailors / haulers / traders | 500–5,000 seasonal | Low | tied to shipping season and cargo cycles |
+| warehouse and dock labor | 500–2,500 | Low | depends on port traffic intensity |
+| officials / clerks / customs personnel | 50–300 | Low | tied to annona, tax, port administration |
+| elite / municipal families | small minority | Low | influence exceeds numbers |
+
+Simulation rule: population is not a static backdrop. Seasonal traffic should alter lodging demand, food prices, labor availability, theft risk, disease risk, and rumor velocity.
+
+---
+
+## 5. Urban Zones
+
+### 5.1 Riverfront / Port Interface
+
+Primary functions:
+
+- landing and unloading
+- cargo inspection
+- short-haul transfer
+- porterage
+- storage assignment
+- gossip and price discovery
+
+Likely actors:
+
+- sailors
+- porters
+- warehouse workers
+- customs personnel
+- agents
+- muleteers
+- small merchants
+- freedmen managing cargo
+
+Simulation uses:
+
+- cargo arrival events
+- rumor propagation
+- theft risk
+- PORTORIUM / fee exposure
+- labor hiring
+- first signal of distant shortages
+
+### 5.2 HORREA / Storage District
+
+Primary functions:
+
+- grain storage
+- oil / wine storage where appropriate
+- privately owned storage
+- imperial or public storage analogues
+- protected goods
+- collateralized inventory
+
+Important distinction:
+
+Large, well-preserved horrea are mostly Imperial and later than 14 BCE, but the presence of 1st c. BCE warehouses supports a storage substrate in the default epoch.
+
+Simulation uses:
+
+- storage cost
+- spoilage risk
+- credit collateral
+- theft risk
+- market delay
+- warehouse fire scenarios
+- disputes over goods held or pledged
+
+### 5.3 Market Streets and TABERNAE
+
+Primary functions:
+
+- small retail
+- food sales
+- repair
+- money exchange
+- daily hiring
+- information exchange
+
+Simulation uses:
+
+- food price index
+- lodging rumors
+- worker availability
+- small-goods purchase
+- background-specific contacts
+
+### 5.4 Workshop Districts
+
+Primary functions:
+
+- metalwork
+- carpentry
+- leather repair
+- cart and harness repair
+- amphora handling / repair
+- small production
+
+SCENARIO-MERCHANT-0001 uses an industrial / mixed-use workshop zone with inherited land value, water access, and transport frontage.
+
+Simulation uses:
+
+- workshop output
+- tool price index
+- displaced labor
+- fire risk
+- repair queue
+- district access penalty
+
+### 5.5 BALNEA / Baths
+
+Primary functions:
+
+- bathing
+- gossip
+- cross-status observation
+- political talk
+- hiring and introductions
+- reputation performance
+
+Baths are the preferred setting for SCENARIO-MERCHANT-0000 because they plausibly allow mixed-status contact between backgrounds that would not share domestic dining space.
+
+Simulation uses:
+
+- background choice prologue
+- rumor comparison
+- AVCTORITAS performance
+- CLIENTELA discovery
+- class-coded interaction
+
+### 5.6 Inns, Cauponae, Thermopolia
+
+Primary functions:
+
+- meals
+- cheap lodging
+- storage of gossip
+- transient-worker congregation
+- low-status deal making
+
+Simulation uses:
+
+- lodging cost
+- food cost
+- rumor source
+- theft risk
+- freedman and camp-logistician contacts
+
+Terminology note: THERMOPOLIVM is plausible for a prepared-food shop, but the prologue should prefer BALNEA / baths if all six backgrounds must plausibly share one scene.
+
+### 5.7 Administrative / Legal Nodes
+
+Primary functions:
+
+- contracts
+- witnessed transactions
+- petitions
+- local magistrate contact
+- dispute handling
+- tax enforcement
+
+Simulation uses:
+
+- legal enforceability
+- witness strength
+- ius_accessus modifiers
+- creditor pressure
+- collateral recovery
+
+### 5.8 Residential Layers
+
+The actor backgrounds require different residential anchors.
+
+| Background | Likely Starting Residence | Notes |
+|---|---|---|
+| Former Legionary | modest room near gate / transport zone | values direct access and low cost |
+| Freedman Trader | taberna back room or rented upper room | close to market signals |
+| Noble Younger Son | dependent lodging with patron / better insula apartment | status exceeds liquiditas |
+| Failed Magistrate | respectable but debt-burdened lodging | social appearance matters |
+| Camp Logistician | cheap lodging near haulers / stables | practical, mobile |
+| Guild Scribe | room near collegium or records office | access to accounts and gossip |
+
+---
+
+## 6. Infrastructure Parameters
+
+| Parameter Token | Type | Confidence | Notes |
+|---|---|---|---|
+| river_access | location | High | core to Ostia's function |
+| via_ostiensis_access | movement | High | route to Rome |
+| warehouse_capacity | resource | Medium | exact 14 BCE scale uncertain |
+| dock_congestion | movement | Medium | derived from cargo season |
+| porter_availability | labor | Medium | seasonal and event-sensitive |
+| bath_access | social | Medium | strong later evidence, earlier scale uncertain |
+| fire_risk_urban | event | Medium | dense mixed-use settlement |
+| disease_risk_seasonal | health | Low | plausible but needs source development |
+| rent_pressure | market | Low | inferred from transient population |
+| rumor_velocity | information | Medium | port-city logic |
+
+---
+
+## 7. Cost and Price Bands
+
+These are placeholders for research refinement. They must not be treated as final database values.
+
+| Cost Item | Working Value | Unit | Confidence | Notes |
+|---|---:|---|---|---|
+| cheap meal | 0.25–1.0 | as / meal | Low | broad Roman analogue |
+| modest meal | 1–4 | asses / meal | Low | urban analogue |
+| bath entry | 0.25–1.0 | as | Low | needs source confirmation by period |
+| cheap lodging | 1–4 | asses / night | Low | inferred from urban lodging |
+| porter day wage | 1–4 | asses / day | Low | requires primary source calibration |
+| skilled artisan wage | 4–16 | asses / day | Low | broad analogue |
+| mule hire | TBD | denarii / day | Low | requires route research |
+| cart hire | TBD | denarii / day | Low | requires route research |
+| warehouse storage | TBD | per unit / day | Low | must be researched |
+| scribe / witness fee | TBD | per contract | Low | needed for FAENVS scenario |
+
+Rule: low-confidence economic values are still retained because they identify where uncertainty lives.
+
+---
+
+## 8. Social Nodes
+
+| Node | What It Produces | Backgrounds Favored |
+|---|---|---|
+| BALNEA | mixed-status rumor, public reading of character | all |
+| HORREA | cargo intelligence, theft risk, collateral opportunities | freedman trader, guild scribe |
+| Riverfront | arrival news, porter labor, route signals | legionary, camp logistician |
+| Collegium House | contracts, obligations, mutual aid | guild scribe, freedman trader |
+| Tavern / Thermopolium | low-status gossip, labor news | freedman trader, camp logistician |
+| Legal Forum / Magistrate Contact | enforceability, creditor pressure | noble younger son, failed magistrate |
+| Stables / Grazing Yard | animal hire, cart availability | legionary, camp logistician |
+
+---
+
+## 9. Scenario Dependencies
+
+### SCENARIO-MERCHANT-0000 — Baths Prologue
+
+Ostia must support a mixed-status conversation where all six backgrounds plausibly interpret the same rumor differently.
+
+Recommended setting:
+
+- BALNEA, not private dinner
+- near enough to smoke, rumor, or port news
+- public enough that status is performed
+- informal enough that low-status actors can speak
+
+### SCENARIO-MERCHANT-0001 — Bronze Forge Fire
+
+Requires:
+
+- mixed-use workshop district
+- valuable old plot
+- water or road frontage
+- adjacent worker / animal / transport activity
+- rumor network
+- creditor visibility
+- municipal weakness or ambiguity
+
+### SCENARIO-MERCHANT-0002 — Capuan Timber Yard Fire
+
+Ostia dependency:
+
+- outbound cargo purchase
+- news delay from Capua
+- goods available before Capua reprices
+- hauler / cart availability
+
+### SCENARIO-MERCHANT-0003 — FAENVS Offer
+
+Ostia dependency:
+
+- ability to identify distressed counterparties
+- witnesses
+- legal pressure
+- reputation effect
+- capital lockup competing with cargo venture
+
+---
+
+## 10. Background Interaction Matrix
+
+| Background | What Ostia Shows Them First | Blind Spot |
+|---|---|---|
+| Former Legionary | routes, discipline failures, transport bottlenecks | hidden finance |
+| Freedman Trader | mispriced goods and ignored markets | elite legal risk |
+| Noble Younger Son | social hierarchy and access points | operating costs |
+| Failed Magistrate | leverage, signatures, favors owed | public distrust |
+| Camp Logistician | supply movement and shortage timing | prestige etiquette |
+| Guild Scribe | debts, records, counterparties | physical danger |
+
+---
+
+## 11. Daily Rhythm Model
+
+| Time | City State | Simulation Use |
+|---|---|---|
+| dawn | porters, animal handlers, bakers, smoke reports | early labor and event signals |
+| morning | market setup, legal errands, loading | contract and cargo actions |
+| midday | heat, baths begin filling, gossip consolidates | social encounters |
+| afternoon | price negotiation, dispatch decisions | venture commitment |
+| evening | taverns, account reckoning, rumors mutate | risk and information events |
+| night | theft, fires, covert meetings | hidden events |
+
+---
+
+## 12. Seasonal Rhythm Model
+
+| Season | Expected Effects |
+|---|---|
+| winter | maritime risk, slower movement, disease and damp risk |
+| spring | increased movement, river reliability, labor demand |
+| summer | heat, spoilage, lower Tiber concerns, crowding |
+| autumn | renewed movement, price adjustment, storage pressure |
+
+Need further research: relationship between MARE CLAVSVM, river levels, and local Ostia storage demand.
+
+---
+
+## 13. Parameter Candidates
+
+| Parameter Token | Domain |
+|---|---|
+| ostia_population_band | demographic |
+| transient_population_factor | demographic |
+| dock_congestion_index | movement |
+| warehouse_capacity_index | resource |
+| porter_availability | labor |
+| cart_availability | movement |
+| bath_social_density | social |
+| rumor_velocity | information |
+| legal_access_index | institutional |
+| fire_risk_index | event |
+| rent_pressure_index | market |
+| food_price_index | market |
+| storage_fee_index | cost |
+| theft_risk_index | security |
+| disease_risk_index | health |
+| creditor_visibility | finance |
+| collegium_presence | social |
+| portorium_exposure | cost |
+
+---
+
+## 14. Relations
+
+```text
+transient_population_factor ↑ -> rent_pressure_index ↑
+transient_population_factor ↑ -> rumor_velocity ↑
+dock_congestion_index ↑ -> porter_wage ↑
+dock_congestion_index ↑ -> cargo_delay ↑
+warehouse_capacity_index ↓ -> storage_fee_index ↑
+storage_fee_index ↑ -> distressed_sale_probability ↑
+bath_social_density ↑ -> rumor_velocity ↑
+fire_risk_index ↑ -> workshop_output_volatility ↑
+legal_access_index ↑ -> contract_enforceability ↑
+clientela ↑ -> information_quality ↑
+auctoritas ↑ -> witness_reliability ↑
+food_price_index ↑ -> labor_unrest_risk ↑
+cart_availability ↓ -> venture_cost ↑
+```
+
+---
+
+## 15. Evidence and Source Notes
+
+Primary source targets for future refinement:
+
+- Cicero, letters and speeches for social/legal/commercial norms
+- Livy for early Ostian military and civic references
+- Pliny the Younger, Epistulae 5.6.12 for Tiber seasonality analogy
+- Digest of Justinian for contract and enforcement categories
+- Diocletian's Price Edict for later comparative price structure only
+
+Archaeological / scholarship targets:
+
+- Russell Meiggs, *Roman Ostia*
+- Geoffrey Rickman, *Roman Granaries and Store Buildings*
+- Carlo Pavolini, *La vita quotidiana a Ostia*
+- Gustav Hermansen, *Ostia: Aspects of Roman City Life*
+- Ostia-Antica.org topographical dictionary
+- geoarchaeological studies of the Roman port-city of Ostia
+
+Current verified basis from preliminary research:
+
+- 1st c. BCE warehouses existed at Ostia
+- Republican walls enclosed roughly 70 ha
+- Imperial population estimates are much later and must be used only as upper-bound analogues
+- horrea were concentrated near the Tiber and did not serve Ostia alone
+- baths were social infrastructure used across status boundaries in the Roman world, with strong evidence at Ostia in later archaeology
+
+---
+
+## 16. Repository Use
+
+Internal simulation substrate. Not player-facing text.
+
+Use this document to support:
+
+- scenario placement
+- prologue construction
+- background starting conditions
+- cost registry development
+- urban parameter registry
+- Route I preparation
+- future city comparison documents
+
+---
+
+## 17. Canonical Success Condition
+
+If Ostia stops functioning as a painted backdrop and starts functioning as a pressure field — where rents, rumors, labor, storage, status, and routes push on every MERCATOR differently — then this document is functioning correctly.