feat(simulation): add corporate behavioral archetypes — Layer 3 (#809)

Implements the 6 behavioral archetypes from D-175 (Burnelli-Sheldon):

  Producer     — 1.15× production scale, neutral price signal
  Distributor  — 0.9× production, −3% price discount to move volume
  Specialist   — 1.0× production, +10% price premium for expertise
  Monopolist   — 0.8× production, withholds 25% of output, +20% premium
  Cooperative  — 1.0× production, −5% community discount
  Intermediary — 0.7× production, relies on traded goods

Archetype loading:
- Reads from corporations.behavioral_archetype (currently NULL for all corps)
- Falls back to heuristic inference from specialization text (freight → Distributor,
  extraction → Producer, luxury goods → Specialist, etc.)
- 48 corps loaded on current DB, all inferred (DB column to be populated when
  wiki corp frontmatter is extended with the behavioral_archetype field)

Applied in model.rs step():
- Per-corp effective_capacity = BASELINE_CAPACITY × production_scale
- Monopolist supply_withheld fraction reduces net output to stockpile
- Price premium: small ALPHA-scaled nudge to node price for primary commodity

All D-179 stability checks still pass with archetypes active.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tooling/econ-sim/src/agents.rs

@@ -0,0 +1,157 @@
+//! Layer 3: Corporate behavioral agents (D-178).
+//!
+//! Six behavioral archetypes from D-175 / Burnelli-Sheldon:
+//!
+//!   Producer     — maximises output, low trade aggression
+//!   Distributor  — volume-focused, aggressive trade, thin margin
+//!   Specialist   — premium pricing, narrow focus, low trade
+//!   Monopolist   — withholds supply to maintain scarcity premium
+//!   Cooperative  — fair pricing, community stability orientation
+//!   Intermediary — arbitrage-focused, high trade, lower own production
+//!
+//! Archetypes are loaded from `corporations.behavioral_archetype` in the DB.
+//! If NULL, the archetype is inferred from the `specialization` field text.
+//!
+//! Parameters apply to per-corp production in each simulation tick.
+//! Trade-layer archetype effects (corp-level bid/ask) are deferred to a
+//! future sprint when the event port (D-180) and IPC bridge are in place.
+
+use std::collections::HashMap;
+
+// ---------------------------------------------------------------------------
+// Archetype enum
+// ---------------------------------------------------------------------------
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub enum Archetype {
+    Producer,
+    Distributor,
+    Specialist,
+    Monopolist,
+    Cooperative,
+    Intermediary,
+}
+
+impl Archetype {
+    /// Parse from DB string (case-insensitive).
+    pub fn from_str(s: &str) -> Option<Self> {
+        match s.to_lowercase().trim() {
+            "producer" => Some(Archetype::Producer),
+            "distributor" => Some(Archetype::Distributor),
+            "specialist" => Some(Archetype::Specialist),
+            "monopolist" => Some(Archetype::Monopolist),
+            "cooperative" => Some(Archetype::Cooperative),
+            "intermediary" => Some(Archetype::Intermediary),
+            _ => None,
+        }
+    }
+
+    /// Infer archetype from `specialization` field free text.
+    ///
+    /// Heuristic: look for domain keywords that map to behavioral patterns.
+    /// Falls back to `Producer` (the most neutral, maximises output).
+    pub fn infer_from_specialization(spec: &str) -> Self {
+        let s = spec.to_lowercase();
+        if s.contains("freight") || s.contains("logistics") || s.contains("hauler") || s.contains("cargo") {
+            Archetype::Distributor
+        } else if s.contains("arbitr") || s.contains("trading company") || s.contains("brokerage") || s.contains("intermediar") {
+            Archetype::Intermediary
+        } else if s.contains("cooperative") || s.contains("mutu") || s.contains("negociant") {
+            Archetype::Cooperative
+        } else if s.contains("whisky") || s.contains("wine") || s.contains("lager") || s.contains("precision") || s.contains("bespoke") || s.contains("longevity") {
+            Archetype::Specialist
+        } else if s.contains("infrastructure") && (s.contains("gate") || s.contains("span")) {
+            // Gate Corp maintains infrastructure monopoly
+            Archetype::Monopolist
+        } else {
+            Archetype::Producer
+        }
+    }
+
+    /// Behavioral parameters for this archetype.
+    pub fn params(self) -> ArchetypeParams {
+        match self {
+            // Producer: higher output, normal trade participation
+            Archetype::Producer => ArchetypeParams {
+                production_scale: 1.15,
+                supply_withheld: 0.0,
+                price_premium: 0.0,
+            },
+            // Distributor: leaner production, price discount to move volume
+            Archetype::Distributor => ArchetypeParams {
+                production_scale: 0.90,
+                supply_withheld: 0.0,
+                price_premium: -0.03,
+            },
+            // Specialist: normal production, commands a premium
+            Archetype::Specialist => ArchetypeParams {
+                production_scale: 1.0,
+                supply_withheld: 0.0,
+                price_premium: 0.10,
+            },
+            // Monopolist: constrained output, withholds supply, premium
+            Archetype::Monopolist => ArchetypeParams {
+                production_scale: 0.80,
+                supply_withheld: 0.25,
+                price_premium: 0.20,
+            },
+            // Cooperative: normal production, slight discount for community access
+            Archetype::Cooperative => ArchetypeParams {
+                production_scale: 1.0,
+                supply_withheld: 0.0,
+                price_premium: -0.05,
+            },
+            // Intermediary: lower own production, relies on traded goods
+            Archetype::Intermediary => ArchetypeParams {
+                production_scale: 0.70,
+                supply_withheld: 0.0,
+                price_premium: -0.01,
+            },
+        }
+    }
+}
+
+// ---------------------------------------------------------------------------
+// Parameter struct
+// ---------------------------------------------------------------------------
+
+/// Per-tick behavioral parameters for a corporation.
+#[derive(Debug, Clone)]
+pub struct ArchetypeParams {
+    /// Multiplier on BASELINE_CAPACITY for this corp's production.
+    pub production_scale: f64,
+    /// Fraction of this tick's output that is withheld from the node's
+    /// stockpile (Monopolist strategy). Range [0.0, 1.0].
+    pub supply_withheld: f64,
+    /// Additive price premium on goods this corp produces.
+    /// Applied to the node price signal for their primary commodity.
+    /// Positive → price pressure up. Negative → price pressure down.
+    pub price_premium: f64,
+}
+
+// ---------------------------------------------------------------------------
+// Corpus load
+// ---------------------------------------------------------------------------
+
+/// Build archetype map from the raw DB data supplied by the caller.
+///
+/// `corp_data`: Vec of (corp_id, behavioral_archetype_opt, specialization_opt)
+pub fn build_archetype_map(
+    corp_data: Vec<(String, Option<String>, Option<String>)>,
+) -> HashMap<String, Archetype> {
+    corp_data
+        .into_iter()
+        .map(|(corp_id, archetype_str, specialization)| {
+            let archetype = archetype_str
+                .as_deref()
+                .and_then(Archetype::from_str)
+                .unwrap_or_else(|| {
+                    specialization
+                        .as_deref()
+                        .map(Archetype::infer_from_specialization)
+                        .unwrap_or(Archetype::Producer)
+                });
+            (corp_id, archetype)
+        })
+        .collect()
+}