Apply two-sided bid-ask spread so BYC par sits inside the book

.github/workflows/testnet11-asset-bootstrap-helper.yml

@@ -282,7 +282,6 @@ jobs:
               snippet_lines.append(f"    fixed_quote_per_base: {fixed_quote_per_base}")
               snippet_lines.append("    quote_unit_mojo_multiplier: 1000000000000")
               snippet_lines.append("    slippage_bps: 100")
-              snippet_lines.append("    strategy_target_spread_bps: 140")
               snippet_lines.append("    strategy_min_xch_price_usd: 20.0")
               snippet_lines.append("    strategy_max_xch_price_usd: 60.0")
               snippet_lines.append("    strategy_offer_expiry_minutes: 10")

config/markets.yaml

@@ -16,7 +16,6 @@ markets:
       min_price_quote_per_base: 0.0031
       max_price_quote_per_base: 0.0038
       slippage_bps: 100
-      strategy_target_spread_bps: 140
       strategy_min_xch_price_usd: 20.0
       strategy_max_xch_price_usd: 60.0
       strategy_offer_expiry_minutes: 10
@@ -95,7 +94,6 @@ markets:
       min_price_quote_per_base: 0.0027
       max_price_quote_per_base: 0.0033
       slippage_bps: 100
-      strategy_target_spread_bps: 140
       strategy_min_xch_price_usd: 20.0
       strategy_max_xch_price_usd: 60.0
       strategy_offer_expiry_minutes: 10
@@ -174,7 +172,6 @@ markets:
       min_price_quote_per_base: 0.0030
       max_price_quote_per_base: 0.0037
       slippage_bps: 100
-      strategy_target_spread_bps: 140
       strategy_offer_expiry_minutes: 10
       cancel_move_threshold_bps: 300
       cancel_policy_stable_vs_unstable: true
@@ -252,7 +249,6 @@ markets:
       min_price_quote_per_base: 0.0027
       max_price_quote_per_base: 0.0033
       slippage_bps: 100
-      strategy_target_spread_bps: 140
       strategy_min_xch_price_usd: 20.0
       strategy_max_xch_price_usd: 60.0
       strategy_offer_expiry_minutes: 10
@@ -364,7 +360,9 @@ markets:
     signer_key_id: "key-main-2"
     receive_address: "xch1u3tytpv45sj0h4lpwmtkyzh2ggvw4x7jccyxzu995p2aj40wzcxqvymyn3"
     pricing:
-      fixed_quote_per_base: 0.999
+      # Mid at par; 20 bps full spread → bid 0.999 / ask 1.001 so 1.0 is inside.
+      fixed_quote_per_base: 1.0
+      strategy_target_spread_bps: 20
       strategy_offer_expiry_minutes: 30
     inventory:
       low_watermark_base_units: 200

config/testnet-markets.yaml

@@ -14,7 +14,6 @@ markets:
       fixed_quote_per_base: 0.004714285714285714
       quote_unit_mojo_multiplier: 1000000000000
       slippage_bps: 100
-      strategy_target_spread_bps: 140
       strategy_min_xch_price_usd: 20.0
       strategy_max_xch_price_usd: 60.0
       strategy_offer_expiry_minutes: 10
@@ -56,7 +55,6 @@ markets:
       fixed_quote_per_base: 0.002420604183
       quote_unit_mojo_multiplier: 1000000000000
       slippage_bps: 100
-      strategy_target_spread_bps: 140
       strategy_min_xch_price_usd: 20.0
       strategy_max_xch_price_usd: 60.0
       strategy_offer_expiry_minutes: 10

docs/README.md

@@ -7,6 +7,7 @@ accepted decision** when onboarding.
 
 | ADR                                                              | Topic                                                                   |
 | ---------------------------------------------------------------- | ----------------------------------------------------------------------- |
+| [0025](decisions/0025-two-sided-target-spread.md)                | **Two-sided spread** — bid/ask around mid; sell-only omits the field    |
 | [0023](decisions/0023-canonical-cat-outer-puzzle-hash.md)        | **CAT outer hash** — one `coinset/cats/outer` primitive + Coinset hex   |
 | [0021](decisions/0021-three-ownership-simplifications.md)        | **Ownership spines** — expired maker, reconcile prep, `coin_ops::shape` |
 | [0020](decisions/0020-soft-expiry-stable-makers.md)              | **Soft listing expiry** — stable makers, `ensure_size_n_offer`          |

docs/decisions/0025-two-sided-target-spread.md

@@ -0,0 +1,35 @@
+# ADR 0025: Two-sided target spread around mid
+
+## Status
+
+Accepted (2026-08-12).
+
+## Context
+
+`strategy_target_spread_bps` was parsed and copied onto strategy actions, but offer
+build used a single mid (`fixed_quote_per_base` or min/max midpoint) for both sides.
+`byc_two_sided_wusdbc` therefore posted bid and ask at the same price (0.999), so
+there was no spread and par (1.0) sat above both quotes.
+
+Sell-only books used to set `strategy_target_spread_bps` (historically unused). Applying
+it there would move ECO ask prices, so those configs omit the field. Strategy/dispatch
+also carried a dead `target_spread_bps` on `PlannedAction` that never reached quote math.
+
+## Decision
+
+1. **Full-width bps, split equally.** `strategy_target_spread_bps` is the bid-ask width.
+   Buy = mid × (1 − half); sell = mid × (1 + half).
+2. **Two-sided only.** `MarketConfig::quote_price_for_side` is the only policy entry.
+   It applies the offset when `mode` is `two_sided`. Sell-only YAML omits the field.
+   If it is still present, `quote_price` stays mid so it cannot move posted asks.
+3. **One price path.** Create, unique-maker pin, bootstrap denomination, and reservation
+   all take the side-adjusted quote from `MarketConfig` so clip mojos stay consistent.
+   Strategy actions do not carry spread; `PlannedAction` / `StrategyConfig` no longer
+   have `target_spread_bps`.
+
+## Consequences
+
+- `byc_two_sided_wusdbc` mid 1.0 + 20 bps posts bid 0.999 / ask 1.001 (1.0 inside).
+- Buy clips change with the bid; existing 9990-mojo wUSDC.b makers still match 20 bps
+  at size 10. Sell makers stay 10000-mojo BYC; only the requested quote amount changes.
+- Open Direct listings at the old price remain until listing expiry or take.

docs/progress.md

@@ -16,6 +16,12 @@ Pre-Rust migration detail lives in git history and
 
 ## Milestones
 
+### 2026-08-12 — Two-sided target spread (ADR 0025)
+
+`strategy_target_spread_bps` now offsets two-sided bid/ask around mid (buy below, sell
+above). Sell-only configs omit the field and keep mid. `byc_two_sided_wusdbc` is mid
+1.0 + 20 bps so par sits inside the book (bid 0.999 / ask 1.001).
+
 ### 2026-08-10 — Canonical CAT outer puzzle-hash (ADR 0023)
 
 `cat(asset_id, p2)` outer hashes curry once in `coinset/cats/outer`; vault create-assert

greenfloor-engine/src/config/markets/mod.rs

@@ -45,6 +45,32 @@ pub struct MarketConfig {
     pub ladders: HashMap<String, Vec<LadderEntry>>,
 }
 
+impl MarketConfig {
+    #[must_use]
+    pub fn is_two_sided(&self) -> bool {
+        self.mode.trim().eq_ignore_ascii_case("two_sided")
+    }
+
+    /// Quote-per-base for `side`. Two-sided markets apply `strategy_target_spread_bps`
+    /// around mid (buy below, sell above). One-sided markets keep the mid price so
+    /// unused spread fields on sell-only books do not move posted prices.
+    ///
+    /// # Errors
+    ///
+    /// Returns an error when pricing lacks a usable quote price.
+    pub fn quote_price_for_side(&self, side: &str) -> SignerResult<f64> {
+        let mid = self.pricing.quote_price()?;
+        if !self.is_two_sided() {
+            return Ok(mid);
+        }
+        Ok(pricing::spread_adjusted_quote_price(
+            mid,
+            self.pricing.strategy_target_spread_bps,
+            side,
+        ))
+    }
+}
+
 #[derive(Debug, Clone)]
 pub struct MarketsConfig {
     pub markets: Vec<MarketConfig>,
@@ -206,4 +232,39 @@ mod soft_expiry_tests {
         disabled.enabled = false;
         assert!(!market_wants_ladder_size(&disabled, "sell", 10));
     }
+
+    #[test]
+    fn two_sided_quote_price_applies_spread_sell_only_does_not() {
+        let pricing = MarketPricing {
+            fixed_quote_per_base: Some(1.0),
+            strategy_target_spread_bps: Some(20),
+            ..MarketPricing::default()
+        };
+        let two_sided = MarketConfig {
+            market_id: "byc".to_string(),
+            enabled: true,
+            unique_maker_coins: true,
+            base_asset: "BYC".to_string(),
+            base_symbol: "BYC".to_string(),
+            quote_asset: "wUSDC.b".to_string(),
+            quote_asset_type: "stable".to_string(),
+            receive_address: "xch1qqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqqq2u30w"
+                .to_string(),
+            signer_key_id: "k".to_string(),
+            mode: "two_sided".to_string(),
+            pricing: pricing.clone(),
+            cancel_move_threshold_bps: None,
+            ladders: HashMap::new(),
+        };
+        let buy = two_sided.quote_price_for_side("buy").expect("buy");
+        let sell = two_sided.quote_price_for_side("sell").expect("sell");
+        assert!(buy < 1.0 && 1.0 < sell);
+
+        let mut sell_only = two_sided.clone();
+        sell_only.mode = "sell_only".to_string();
+        let sell_mid = sell_only.quote_price_for_side("sell").expect("mid");
+        let buy_mid = sell_only.quote_price_for_side("buy").expect("mid");
+        assert!((sell_mid - 1.0).abs() < 1e-12);
+        assert!((buy_mid - 1.0).abs() < 1e-12);
+    }
 }

greenfloor-engine/src/config/markets/pricing.rs

@@ -48,7 +48,7 @@ impl MarketPricing {
             .unwrap_or(DEFAULT_OFFER_EXPIRY_MINUTES)
     }
 
-    /// Quote-per-base for manual / managed offer build.
+    /// Mid quote-per-base for manual / managed offer build (no bid-ask offset).
     ///
     /// # Errors
     ///
@@ -116,6 +116,12 @@ pub(super) fn parse_market_pricing(
         optional_positive_i64(obj, market_id, "cancel_move_threshold_bps")?;
     let strategy_target_spread_bps =
         optional_positive_i64(obj, market_id, "strategy_target_spread_bps")?;
+    if strategy_target_spread_bps.is_some_and(|bps| bps >= 20_000) {
+        return Err(market_err(
+            market_id,
+            "strategy_target_spread_bps must be < 20000",
+        ));
+    }
     let strategy_min_xch_price_usd =
         optional_positive_f64(obj, market_id, "strategy_min_xch_price_usd")?;
     let strategy_max_xch_price_usd =
@@ -171,6 +177,21 @@ pub(super) fn parse_market_pricing(
     })
 }
 
+/// Full spread in bps, split equally around mid. Buy below mid; sell above.
+#[must_use]
+#[allow(clippy::cast_precision_loss)]
+pub(super) fn spread_adjusted_quote_price(mid: f64, spread_bps: Option<i64>, side: &str) -> f64 {
+    let Some(bps) = spread_bps.filter(|value| *value > 0) else {
+        return mid;
+    };
+    let half = (bps as f64) / 20_000.0;
+    if side.trim().eq_ignore_ascii_case("buy") {
+        mid * (1.0 - half)
+    } else {
+        mid * (1.0 + half)
+    }
+}
+
 fn reject_legacy_fields(obj: &Map<String, Value>, market_id: &str) -> SignerResult<()> {
     for legacy_field in ["reference_source", "reference_pair"] {
         if obj.contains_key(legacy_field) {
@@ -347,4 +368,33 @@ mod tests {
         .expect("valid");
         assert_eq!(parsed.cancel_move_threshold_bps, Some(250));
     }
+
+    #[test]
+    fn spread_adjusted_quote_price_offsets_half_spread_around_mid() {
+        let buy = spread_adjusted_quote_price(1.0, Some(20), "buy");
+        let sell = spread_adjusted_quote_price(1.0, Some(20), "sell");
+        assert!((buy - 0.999).abs() < 1e-12);
+        assert!((sell - 1.001).abs() < 1e-12);
+        assert!(buy < 1.0 && 1.0 < sell);
+    }
+
+    #[test]
+    fn spread_adjusted_quote_price_without_spread_is_mid() {
+        assert!((spread_adjusted_quote_price(0.999, None, "buy") - 0.999).abs() < 1e-12);
+        assert!((spread_adjusted_quote_price(0.999, None, "sell") - 0.999).abs() < 1e-12);
+    }
+
+    #[test]
+    fn parse_rejects_spread_that_would_zero_the_buy_side() {
+        let err = parse_market_pricing(
+            Some(&json!({"strategy_target_spread_bps": 20_000})),
+            "BYC",
+            "wUSDC.b",
+            "stable",
+            "m1",
+        )
+        .err()
+        .expect("spread too wide");
+        assert!(err.to_string().contains("strategy_target_spread_bps"));
+    }
 }

greenfloor-engine/src/cycle/dispatch.rs

@@ -21,8 +21,6 @@ pub struct PlannedActionInput {
     pub cancel_after_create: Option<bool>,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub reason: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub target_spread_bps: Option<i64>,
 }
 
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize, Default)]
@@ -177,7 +175,6 @@ mod tests {
                 expiry_value: None,
                 cancel_after_create: None,
                 reason: None,
-                target_spread_bps: None,
             },
             PlannedActionInput {
                 size: 10,
@@ -188,7 +185,6 @@ mod tests {
                 expiry_value: None,
                 cancel_after_create: None,
                 reason: None,
-                target_spread_bps: None,
             },
         ];
         let expanded = expand_inputs_by_repeat(&actions);