From 01c99ea69b01e25b2493e4f170fb8bbf1baab569 Mon Sep 17 00:00:00 2001
From: Abeeujah <abeeujah@gmail.com>
Date: Sat, 6 Jun 2026 11:44:18 +0100
Subject: [PATCH 1/7] Rename OrdF64 to PositiveF64

Update the type name to better reflect its domain invariants. The
underlying floats are guaranteed to be both positive and not-NaN,
making `PositiveF64` a more accurate and descriptive name than
`OrdF64`, which only highlighted the `Ord` trait implementation.
---
 src/policy/compiler.rs | 32 ++++++++++++++++--------------
 src/policy/concrete.rs | 44 +++++++++++++++++++++++-------------------
 2 files changed, 41 insertions(+), 35 deletions(-)

diff --git a/src/policy/compiler.rs b/src/policy/compiler.rs
index 4ffadb804..99b0a94bf 100644
--- a/src/policy/compiler.rs
+++ b/src/policy/compiler.rs
@@ -18,20 +18,22 @@ use crate::policy::Concrete;
 use crate::prelude::*;
 use crate::{policy, Miniscript, MiniscriptKey, Terminal};
 
-type PolicyCache<Pk, Ctx> =
-    BTreeMap<(Concrete<Pk>, OrdF64, Option<OrdF64>), BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>>;
+type PolicyCache<Pk, Ctx> = BTreeMap<
+    (Concrete<Pk>, PositiveF64, Option<PositiveF64>),
+    BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
+>;
 
 /// Ordered f64 for comparison.
 #[derive(Copy, Clone, PartialEq, Debug)]
-pub(crate) struct OrdF64(pub f64);
+pub(crate) struct PositiveF64(pub f64);
 
-impl Eq for OrdF64 {}
+impl Eq for PositiveF64 {}
 // We could derive PartialOrd, but we can't derive Ord, and clippy wants us
 // to derive both or neither. Better to be explicit.
-impl PartialOrd for OrdF64 {
+impl PartialOrd for PositiveF64 {
     fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> { Some(self.cmp(other)) }
 }
-impl Ord for OrdF64 {
+impl Ord for PositiveF64 {
     fn cmp(&self, other: &Self) -> cmp::Ordering {
         // will panic if given NaN
         self.0.partial_cmp(&other.0).unwrap()
@@ -129,7 +131,7 @@ impl From<policy::concrete::PolicyError> for CompilerError {
 }
 
 /// Hash required for using OrdF64 as key for hashmap
-impl hash::Hash for OrdF64 {
+impl hash::Hash for PositiveF64 {
     fn hash<H: hash::Hasher>(&self, state: &mut H) { self.0.to_bits().hash(state); }
 }
 
@@ -150,7 +152,7 @@ struct CompilationKey {
     /// The probability of dissatisfaction of the compilation of the policy. Note
     /// that all possible compilations of a (sub)policy have the same sat-prob
     /// and only differ in dissat_prob.
-    dissat_prob: Option<OrdF64>,
+    dissat_prob: Option<PositiveF64>,
 }
 
 impl CompilationKey {
@@ -164,7 +166,7 @@ impl CompilationKey {
 
     /// Helper to create compilation key from components
     fn from_type(ty: Type, expensive_verify: bool, dissat_prob: Option<f64>) -> Self {
-        Self { ty, expensive_verify, dissat_prob: dissat_prob.map(OrdF64) }
+        Self { ty, expensive_verify, dissat_prob: dissat_prob.map(PositiveF64) }
     }
 }
 
@@ -787,8 +789,8 @@ where
     Ctx: ScriptContext,
 {
     //Check the cache for hits
-    let ord_sat_prob = OrdF64(sat_prob);
-    let ord_dissat_prob = dissat_prob.map(OrdF64);
+    let ord_sat_prob = PositiveF64(sat_prob);
+    let ord_dissat_prob = dissat_prob.map(PositiveF64);
     if let Some(ret) = policy_cache.get(&(policy.clone(), ord_sat_prob, ord_dissat_prob)) {
         return Ok(ret.clone());
     }
@@ -1179,10 +1181,10 @@ where
     best_compilations(policy_cache, policy, sat_prob, dissat_prob)?
         .into_iter()
         .filter(|&(key, _)| {
-            key.ty.corr.base == types::Base::B && key.dissat_prob == dissat_prob.map(OrdF64)
+            key.ty.corr.base == types::Base::B && key.dissat_prob == dissat_prob.map(PositiveF64)
         })
         .map(|(_, val)| val)
-        .min_by_key(|ext| OrdF64(ext.cost_1d(sat_prob, dissat_prob)))
+        .min_by_key(|ext| PositiveF64(ext.cost_1d(sat_prob, dissat_prob)))
         .ok_or(CompilerError::LimitsExceeded)
 }
 
@@ -1204,10 +1206,10 @@ where
             key.ty.corr.base == basic_type
                 && key.ty.corr.unit
                 && val.ms.ty.mall.dissat == types::Dissat::Unique
-                && key.dissat_prob == dissat_prob.map(OrdF64)
+                && key.dissat_prob == dissat_prob.map(PositiveF64)
         })
         .map(|(_, val)| val)
-        .min_by_key(|ext| OrdF64(ext.cost_1d(sat_prob, dissat_prob)))
+        .min_by_key(|ext| PositiveF64(ext.cost_1d(sat_prob, dissat_prob)))
         .ok_or(CompilerError::LimitsExceeded)
 }
 
diff --git a/src/policy/concrete.rs b/src/policy/concrete.rs
index b7c9045bb..0e2451a08 100644
--- a/src/policy/concrete.rs
+++ b/src/policy/concrete.rs
@@ -12,7 +12,7 @@ use bitcoin::absolute;
 use {
     crate::descriptor::TapTree,
     crate::miniscript::ScriptContext,
-    crate::policy::compiler::{self, CompilerError, OrdF64},
+    crate::policy::compiler::{self, CompilerError, PositiveF64},
     crate::Descriptor,
     crate::Miniscript,
     crate::Tap,
@@ -199,7 +199,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
         let internal_key = self
             .tapleaf_probability_iter()
             .filter_map(|(prob, ref pol)| match pol {
-                Self::Key(pk) => Some((OrdF64(prob), pk)),
+                Self::Key(pk) => Some((PositiveF64(prob), pk)),
                 _ => None,
             })
             .max_by_key(|(prob, _)| *prob)
@@ -244,14 +244,15 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
                     match policy {
                         Self::Trivial => None,
                         policy => {
-                            let mut leaf_compilations: Vec<(OrdF64, Miniscript<Pk, Tap>)> = vec![];
+                            let mut leaf_compilations: Vec<(PositiveF64, Miniscript<Pk, Tap>)> =
+                                vec![];
                             for (prob, pol) in policy.tapleaf_probability_iter() {
                                 // policy corresponding to the key (replaced by unsatisfiable) is skipped
                                 if *pol == Self::Unsatisfiable {
                                     continue;
                                 }
                                 let compilation = compiler::best_compilation::<Pk, Tap>(pol)?;
-                                leaf_compilations.push((OrdF64(prob), compilation));
+                                leaf_compilations.push((PositiveF64(prob), compilation));
                             }
                             if !leaf_compilations.is_empty() {
                                 let tap_tree = with_huffman_tree::<Pk>(leaf_compilations);
@@ -303,7 +304,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
                         if n > max_leaves {
                             return Err(CompilerError::TooManyTapleaves { n, max: max_leaves });
                         }
-                        let mut leaf_compilations: Vec<(OrdF64, Miniscript<Pk, Tap>)> = vec![];
+                        let mut leaf_compilations: Vec<(PositiveF64, Miniscript<Pk, Tap>)> = vec![];
                         for (leaf_idx, (prob, pol)) in leaves.iter().enumerate() {
                             if **pol == Self::Unsatisfiable {
                                 continue;
@@ -314,7 +315,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
                                     leaf_index: leaf_idx,
                                 });
                             }
-                            leaf_compilations.push((OrdF64(*prob), compilation));
+                            leaf_compilations.push((PositiveF64(*prob), compilation));
                         }
                         if !leaf_compilations.is_empty() {
                             Some(with_huffman_tree::<Pk>(leaf_compilations))
@@ -371,7 +372,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
                                 .filter(|x| x.1 != Arc::new(Self::Unsatisfiable))
                                 .map(|(prob, pol)| {
                                     (
-                                        OrdF64(prob),
+                                        PositiveF64(prob),
                                         compiler::best_compilation(pol.as_ref()).unwrap(),
                                     )
                                 })
@@ -541,16 +542,16 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
         max_leaves: usize,
         expand_fn: fn(&Self, f64) -> Vec<(f64, Arc<Self>)>,
     ) -> Vec<(f64, Arc<Self>)> {
-        let mut tapleaf_prob_vec = BTreeSet::<(Reverse<OrdF64>, Arc<Self>)>::new();
+        let mut tapleaf_prob_vec = BTreeSet::<(Reverse<PositiveF64>, Arc<Self>)>::new();
         // Store probability corresponding to policy in the enumerated tree. This is required since
         // owing to the current [policy element enumeration algorithm][`Policy::enumerate_pol`],
         // two passes of the algorithm might result in same sub-policy showing up. Currently, we
         // merge the nodes by adding up the corresponding probabilities for the same policy.
-        let mut pol_prob_map = BTreeMap::<Arc<Self>, OrdF64>::new();
+        let mut pol_prob_map = BTreeMap::<Arc<Self>, PositiveF64>::new();
 
         let arc_self = Arc::new(self);
-        tapleaf_prob_vec.insert((Reverse(OrdF64(prob)), Arc::clone(&arc_self)));
-        pol_prob_map.insert(Arc::clone(&arc_self), OrdF64(prob));
+        tapleaf_prob_vec.insert((Reverse(PositiveF64(prob)), Arc::clone(&arc_self)));
+        pol_prob_map.insert(Arc::clone(&arc_self), PositiveF64(prob));
 
         // Since we know that policy enumeration *must* result in increase in total number of nodes,
         // we can maintain the length of the ordered set to check if the
@@ -565,7 +566,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
         // Stopping condition: When NONE of the inputs can be further enumerated.
         'outer: loop {
             //--- FIND a plausible node ---
-            let mut prob: Reverse<OrdF64> = Reverse(OrdF64(0.0));
+            let mut prob: Reverse<PositiveF64> = Reverse(PositiveF64(0.0));
             let mut curr_policy: Arc<Self> = Arc::new(Self::Unsatisfiable);
             let mut curr_pol_replace_vec: Vec<(f64, Arc<Self>)> = vec![];
             let mut no_more_enum = false;
@@ -612,7 +613,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
 
             // OPTIMIZATION - Move marked nodes into final vector
             for (p, pol) in to_del {
-                assert!(tapleaf_prob_vec.remove(&(Reverse(OrdF64(p)), pol.clone())));
+                assert!(tapleaf_prob_vec.remove(&(Reverse(PositiveF64(p)), pol.clone())));
                 pol_prob_map.remove(&pol);
                 ret.push((p, pol.clone()));
             }
@@ -622,12 +623,13 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
                 match pol_prob_map.get(&policy) {
                     Some(prev_prob) => {
                         assert!(tapleaf_prob_vec.remove(&(Reverse(*prev_prob), policy.clone())));
-                        tapleaf_prob_vec.insert((Reverse(OrdF64(prev_prob.0 + p)), policy.clone()));
-                        pol_prob_map.insert(policy.clone(), OrdF64(prev_prob.0 + p));
+                        tapleaf_prob_vec
+                            .insert((Reverse(PositiveF64(prev_prob.0 + p)), policy.clone()));
+                        pol_prob_map.insert(policy.clone(), PositiveF64(prev_prob.0 + p));
                     }
                     None => {
-                        tapleaf_prob_vec.insert((Reverse(OrdF64(p)), policy.clone()));
-                        pol_prob_map.insert(policy.clone(), OrdF64(p));
+                        tapleaf_prob_vec.insert((Reverse(PositiveF64(p)), policy.clone()));
+                        pol_prob_map.insert(policy.clone(), PositiveF64(p));
                     }
                 }
             }
@@ -1090,8 +1092,10 @@ fn has_if_fragment<Pk: MiniscriptKey>(ms: &Miniscript<Pk, Tap>) -> bool {
 
 /// Creates a Huffman Tree from compiled [`Miniscript`] nodes.
 #[cfg(feature = "compiler")]
-fn with_huffman_tree<Pk: MiniscriptKey>(ms: Vec<(OrdF64, Miniscript<Pk, Tap>)>) -> TapTree<Pk> {
-    let mut node_weights = BinaryHeap::<(Reverse<OrdF64>, TapTree<Pk>)>::new();
+fn with_huffman_tree<Pk: MiniscriptKey>(
+    ms: Vec<(PositiveF64, Miniscript<Pk, Tap>)>,
+) -> TapTree<Pk> {
+    let mut node_weights = BinaryHeap::<(Reverse<PositiveF64>, TapTree<Pk>)>::new();
     for (prob, script) in ms {
         node_weights.push((Reverse(prob), TapTree::leaf(script)));
     }
@@ -1102,7 +1106,7 @@ fn with_huffman_tree<Pk: MiniscriptKey>(ms: Vec<(OrdF64, Miniscript<Pk, Tap>)>)
 
         let p = (p1.0).0 + (p2.0).0;
         node_weights.push((
-            Reverse(OrdF64(p)),
+            Reverse(PositiveF64(p)),
             TapTree::combine(s1, s2)
                 .expect("huffman tree cannot produce depth > 128 given sane weights"),
         ));

From e5a3840ef3a0cd71579d4b3ddabddd034ebd73cb Mon Sep 17 00:00:00 2001
From: Abeeujah <abeeujah@gmail.com>
Date: Sat, 6 Jun 2026 13:28:26 +0100
Subject: [PATCH 2/7] Move PositiveF64 to its own module

---
 src/lib.rs                     |  1 +
 src/policy/compiler.rs         | 41 +++++++-------------------
 src/policy/concrete.rs         | 44 ++++++++++++++-------------
 src/primitives/mod.rs          |  1 +
 src/primitives/positive_f64.rs | 54 ++++++++++++++++++++++++++++++++++
 5 files changed, 90 insertions(+), 51 deletions(-)
 create mode 100644 src/primitives/positive_f64.rs

diff --git a/src/lib.rs b/src/lib.rs
index 2d9beaf78..ad6e5f7bc 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -140,6 +140,7 @@ pub use crate::miniscript::satisfy::{Preimage32, Satisfier};
 pub use crate::miniscript::{hash256, Miniscript};
 use crate::prelude::*;
 pub use crate::primitives::absolute_locktime::{AbsLockTime, AbsLockTimeError};
+pub use crate::primitives::positive_f64::PositiveF64;
 pub use crate::primitives::relative_locktime::{RelLockTime, RelLockTimeError};
 pub use crate::primitives::threshold::{Threshold, ThresholdError};
 pub use crate::validation::{Error as ValidationError, ValidationParams};
diff --git a/src/policy/compiler.rs b/src/policy/compiler.rs
index 99b0a94bf..3c02f1243 100644
--- a/src/policy/compiler.rs
+++ b/src/policy/compiler.rs
@@ -5,7 +5,7 @@
 //! Optimizing compiler from concrete policies to Miniscript
 //!
 
-use core::{cmp, f64, fmt, hash, mem};
+use core::{f64, fmt, mem};
 #[cfg(feature = "std")]
 use std::error;
 
@@ -16,30 +16,13 @@ use crate::miniscript::types::{self, ErrorKind, ExtData, Type};
 use crate::miniscript::ScriptContext;
 use crate::policy::Concrete;
 use crate::prelude::*;
-use crate::{policy, Miniscript, MiniscriptKey, Terminal};
+use crate::{policy, Miniscript, MiniscriptKey, PositiveF64, Terminal};
 
 type PolicyCache<Pk, Ctx> = BTreeMap<
     (Concrete<Pk>, PositiveF64, Option<PositiveF64>),
     BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
 >;
 
-/// Ordered f64 for comparison.
-#[derive(Copy, Clone, PartialEq, Debug)]
-pub(crate) struct PositiveF64(pub f64);
-
-impl Eq for PositiveF64 {}
-// We could derive PartialOrd, but we can't derive Ord, and clippy wants us
-// to derive both or neither. Better to be explicit.
-impl PartialOrd for PositiveF64 {
-    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> { Some(self.cmp(other)) }
-}
-impl Ord for PositiveF64 {
-    fn cmp(&self, other: &Self) -> cmp::Ordering {
-        // will panic if given NaN
-        self.0.partial_cmp(&other.0).unwrap()
-    }
-}
-
 /// Detailed error type for compiler.
 #[derive(Copy, Clone, PartialEq, Eq, Debug, Hash)]
 pub enum CompilerError {
@@ -130,11 +113,6 @@ impl From<policy::concrete::PolicyError> for CompilerError {
     fn from(e: policy::concrete::PolicyError) -> Self { Self::PolicyError(e) }
 }
 
-/// Hash required for using OrdF64 as key for hashmap
-impl hash::Hash for PositiveF64 {
-    fn hash<H: hash::Hasher>(&self, state: &mut H) { self.0.to_bits().hash(state); }
-}
-
 /// Compilation key: This represents the state of the best possible compilation
 /// of a given policy(implicitly keyed).
 #[derive(Copy, Clone, PartialEq, Eq, Debug, PartialOrd, Ord, Hash)]
@@ -166,7 +144,7 @@ impl CompilationKey {
 
     /// Helper to create compilation key from components
     fn from_type(ty: Type, expensive_verify: bool, dissat_prob: Option<f64>) -> Self {
-        Self { ty, expensive_verify, dissat_prob: dissat_prob.map(PositiveF64) }
+        Self { ty, expensive_verify, dissat_prob: dissat_prob.map(PositiveF64::new) }
     }
 }
 
@@ -789,8 +767,8 @@ where
     Ctx: ScriptContext,
 {
     //Check the cache for hits
-    let ord_sat_prob = PositiveF64(sat_prob);
-    let ord_dissat_prob = dissat_prob.map(PositiveF64);
+    let ord_sat_prob = PositiveF64::new(sat_prob);
+    let ord_dissat_prob = dissat_prob.map(PositiveF64::new);
     if let Some(ret) = policy_cache.get(&(policy.clone(), ord_sat_prob, ord_dissat_prob)) {
         return Ok(ret.clone());
     }
@@ -1181,10 +1159,11 @@ where
     best_compilations(policy_cache, policy, sat_prob, dissat_prob)?
         .into_iter()
         .filter(|&(key, _)| {
-            key.ty.corr.base == types::Base::B && key.dissat_prob == dissat_prob.map(PositiveF64)
+            key.ty.corr.base == types::Base::B
+                && key.dissat_prob == dissat_prob.map(PositiveF64::new)
         })
         .map(|(_, val)| val)
-        .min_by_key(|ext| PositiveF64(ext.cost_1d(sat_prob, dissat_prob)))
+        .min_by_key(|ext| PositiveF64::new(ext.cost_1d(sat_prob, dissat_prob)))
         .ok_or(CompilerError::LimitsExceeded)
 }
 
@@ -1206,10 +1185,10 @@ where
             key.ty.corr.base == basic_type
                 && key.ty.corr.unit
                 && val.ms.ty.mall.dissat == types::Dissat::Unique
-                && key.dissat_prob == dissat_prob.map(PositiveF64)
+                && key.dissat_prob == dissat_prob.map(PositiveF64::new)
         })
         .map(|(_, val)| val)
-        .min_by_key(|ext| PositiveF64(ext.cost_1d(sat_prob, dissat_prob)))
+        .min_by_key(|ext| PositiveF64::new(ext.cost_1d(sat_prob, dissat_prob)))
         .ok_or(CompilerError::LimitsExceeded)
 }
 
diff --git a/src/policy/concrete.rs b/src/policy/concrete.rs
index 0e2451a08..a9c07ee19 100644
--- a/src/policy/concrete.rs
+++ b/src/policy/concrete.rs
@@ -12,7 +12,7 @@ use bitcoin::absolute;
 use {
     crate::descriptor::TapTree,
     crate::miniscript::ScriptContext,
-    crate::policy::compiler::{self, CompilerError, PositiveF64},
+    crate::policy::compiler::{self, CompilerError},
     crate::Descriptor,
     crate::Miniscript,
     crate::Tap,
@@ -28,7 +28,8 @@ use crate::sync::Arc;
 #[cfg(all(doc, not(feature = "compiler")))]
 use crate::Descriptor;
 use crate::{
-    AbsLockTime, Error, ForEachKey, FromStrKey, MiniscriptKey, RelLockTime, Threshold, Translator,
+    AbsLockTime, Error, ForEachKey, FromStrKey, MiniscriptKey, PositiveF64, RelLockTime, Threshold,
+    Translator,
 };
 
 /// Maximum `TapLeaf`s allowed in a compiled TapTree
@@ -199,7 +200,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
         let internal_key = self
             .tapleaf_probability_iter()
             .filter_map(|(prob, ref pol)| match pol {
-                Self::Key(pk) => Some((PositiveF64(prob), pk)),
+                Self::Key(pk) => Some((PositiveF64::new(prob), pk)),
                 _ => None,
             })
             .max_by_key(|(prob, _)| *prob)
@@ -252,7 +253,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
                                     continue;
                                 }
                                 let compilation = compiler::best_compilation::<Pk, Tap>(pol)?;
-                                leaf_compilations.push((PositiveF64(prob), compilation));
+                                leaf_compilations.push((PositiveF64::new(prob), compilation));
                             }
                             if !leaf_compilations.is_empty() {
                                 let tap_tree = with_huffman_tree::<Pk>(leaf_compilations);
@@ -315,7 +316,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
                                     leaf_index: leaf_idx,
                                 });
                             }
-                            leaf_compilations.push((PositiveF64(*prob), compilation));
+                            leaf_compilations.push((PositiveF64::new(*prob), compilation));
                         }
                         if !leaf_compilations.is_empty() {
                             Some(with_huffman_tree::<Pk>(leaf_compilations))
@@ -372,7 +373,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
                                 .filter(|x| x.1 != Arc::new(Self::Unsatisfiable))
                                 .map(|(prob, pol)| {
                                     (
-                                        PositiveF64(prob),
+                                        PositiveF64::new(prob),
                                         compiler::best_compilation(pol.as_ref()).unwrap(),
                                     )
                                 })
@@ -550,8 +551,8 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
         let mut pol_prob_map = BTreeMap::<Arc<Self>, PositiveF64>::new();
 
         let arc_self = Arc::new(self);
-        tapleaf_prob_vec.insert((Reverse(PositiveF64(prob)), Arc::clone(&arc_self)));
-        pol_prob_map.insert(Arc::clone(&arc_self), PositiveF64(prob));
+        tapleaf_prob_vec.insert((Reverse(PositiveF64::new(prob)), Arc::clone(&arc_self)));
+        pol_prob_map.insert(Arc::clone(&arc_self), PositiveF64::new(prob));
 
         // Since we know that policy enumeration *must* result in increase in total number of nodes,
         // we can maintain the length of the ordered set to check if the
@@ -566,7 +567,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
         // Stopping condition: When NONE of the inputs can be further enumerated.
         'outer: loop {
             //--- FIND a plausible node ---
-            let mut prob: Reverse<PositiveF64> = Reverse(PositiveF64(0.0));
+            let mut prob: Reverse<PositiveF64> = Reverse(PositiveF64::new(0.0));
             let mut curr_policy: Arc<Self> = Arc::new(Self::Unsatisfiable);
             let mut curr_pol_replace_vec: Vec<(f64, Arc<Self>)> = vec![];
             let mut no_more_enum = false;
@@ -575,7 +576,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
             // from the ordered set.
             let mut to_del: Vec<(f64, Arc<Self>)> = vec![];
             'inner: for (i, (p, pol)) in tapleaf_prob_vec.iter().enumerate() {
-                curr_pol_replace_vec = expand_fn(pol, p.0 .0);
+                curr_pol_replace_vec = expand_fn(pol, p.0.value());
                 enum_len += curr_pol_replace_vec.len() - 1; // A disjunctive node should have separated this into more nodes
                 assert!(prev_len <= enum_len);
 
@@ -592,14 +593,14 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
                     // Either node is enumerable, or we have
                     // Mark all non-enumerable nodes to remove,
                     // if not returning value in the current iteration.
-                    to_del.push((p.0 .0, Arc::clone(pol)));
+                    to_del.push((p.0.value(), Arc::clone(pol)));
                 }
             }
 
             // --- Sanity Checks ---
             if enum_len > max_leaves || no_more_enum {
                 for (p, pol) in tapleaf_prob_vec.into_iter() {
-                    ret.push((p.0 .0, pol));
+                    ret.push((p.0.value(), pol));
                 }
                 break 'outer;
             }
@@ -613,7 +614,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
 
             // OPTIMIZATION - Move marked nodes into final vector
             for (p, pol) in to_del {
-                assert!(tapleaf_prob_vec.remove(&(Reverse(PositiveF64(p)), pol.clone())));
+                assert!(tapleaf_prob_vec.remove(&(Reverse(PositiveF64::new(p)), pol.clone())));
                 pol_prob_map.remove(&pol);
                 ret.push((p, pol.clone()));
             }
@@ -623,13 +624,16 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
                 match pol_prob_map.get(&policy) {
                     Some(prev_prob) => {
                         assert!(tapleaf_prob_vec.remove(&(Reverse(*prev_prob), policy.clone())));
-                        tapleaf_prob_vec
-                            .insert((Reverse(PositiveF64(prev_prob.0 + p)), policy.clone()));
-                        pol_prob_map.insert(policy.clone(), PositiveF64(prev_prob.0 + p));
+                        tapleaf_prob_vec.insert((
+                            Reverse(PositiveF64::new(prev_prob.value() + p)),
+                            policy.clone(),
+                        ));
+                        pol_prob_map
+                            .insert(policy.clone(), PositiveF64::new(prev_prob.value() + p));
                     }
                     None => {
-                        tapleaf_prob_vec.insert((Reverse(PositiveF64(p)), policy.clone()));
-                        pol_prob_map.insert(policy.clone(), PositiveF64(p));
+                        tapleaf_prob_vec.insert((Reverse(PositiveF64::new(p)), policy.clone()));
+                        pol_prob_map.insert(policy.clone(), PositiveF64::new(p));
                     }
                 }
             }
@@ -1104,9 +1108,9 @@ fn with_huffman_tree<Pk: MiniscriptKey>(
         let (p1, s1) = node_weights.pop().expect("len must at least be two");
         let (p2, s2) = node_weights.pop().expect("len must at least be two");
 
-        let p = (p1.0).0 + (p2.0).0;
+        let p = (p1.0).value() + (p2.0).value();
         node_weights.push((
-            Reverse(PositiveF64(p)),
+            Reverse(PositiveF64::new(p)),
             TapTree::combine(s1, s2)
                 .expect("huffman tree cannot produce depth > 128 given sane weights"),
         ));
diff --git a/src/primitives/mod.rs b/src/primitives/mod.rs
index 919e6c8ba..d7afefdcb 100644
--- a/src/primitives/mod.rs
+++ b/src/primitives/mod.rs
@@ -12,5 +12,6 @@
 //! should be re-exported at the crate root.
 
 pub mod absolute_locktime;
+pub mod positive_f64;
 pub mod relative_locktime;
 pub mod threshold;
diff --git a/src/primitives/positive_f64.rs b/src/primitives/positive_f64.rs
new file mode 100644
index 000000000..f338ead30
--- /dev/null
+++ b/src/primitives/positive_f64.rs
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: CC0-1.0
+
+//! Positive Floating-Point Numbers
+//!
+//! A wrapper around [`f64`] used to represent branch probabilities and
+//! execution costs within the policy compiler.
+//!
+//! Values are guaranteed to be positive floats and never NaN (but may be
+//! infinite), ensuring that the type can safely implement [`Ord`] and [`Eq`]
+//! without panicking.
+
+use core::{cmp, f64, hash};
+
+/// A positive, possibly-infinite, floating-point number.
+#[derive(Copy, Clone, PartialEq, Debug)]
+pub struct PositiveF64(pub(super) f64);
+
+impl PositiveF64 {
+    /// Positive Infinity, used as a sentinel for impossible compilation branches.
+    pub const INFINITY: Self = Self(f64::INFINITY);
+
+    /// Creates a new `PositiveF64` from the given value.
+    ///
+    /// # Panics
+    ///
+    /// Panics if `value` is not a positive-floating point number.
+    pub fn new(value: f64) -> Self {
+        assert!(value > 0.0, "PositiveF64 must be positive and not NaN, got {value}");
+        Self(value)
+    }
+
+    /// Returns the `PositiveF64` value.
+    pub fn value(&self) -> f64 { self.0 }
+}
+
+impl Eq for PositiveF64 {}
+
+// We could derive PartialOrd, but we can't derive Ord, and clippy wants us
+// to derive both or neither. Better to be explicit.
+impl PartialOrd for PositiveF64 {
+    fn partial_cmp(&self, other: &Self) -> Option<cmp::Ordering> { Some(self.cmp(other)) }
+}
+
+impl Ord for PositiveF64 {
+    fn cmp(&self, other: &Self) -> cmp::Ordering {
+        // will panic if given NaN
+        self.0.partial_cmp(&other.0).unwrap()
+    }
+}
+
+/// Hash required for using OrdF64 as key for hashmap
+impl hash::Hash for PositiveF64 {
+    fn hash<H: hash::Hasher>(&self, state: &mut H) { self.0.to_bits().hash(state); }
+}

From 061b2f97013d43dfef0e0414fcf52995c57cdefc Mon Sep 17 00:00:00 2001
From: Abeeujah <abeeujah@gmail.com>
Date: Sat, 6 Jun 2026 13:46:56 +0100
Subject: [PATCH 3/7] Implement PositiveF64 Arithmetic and Normalization

Add `Mul` and Add trait implementations for `PositiveF64` to enable
arithmetic operations on `PositiveF64` values. Display impl is needed
for `PositiveF64` to be used in `Policy`.

Provide a `normalized` method on `PositiveF64` to normalize two values
into a valid probability distribution.

Implement the `k_over_n` method on `Threshold` to expose the threshold
ratio (k / n) as a `PositiveF64`.
---
 src/primitives/positive_f64.rs | 25 ++++++++++++++++++++++++-
 src/primitives/threshold.rs    |  4 ++++
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/src/primitives/positive_f64.rs b/src/primitives/positive_f64.rs
index f338ead30..a2d6e36d3 100644
--- a/src/primitives/positive_f64.rs
+++ b/src/primitives/positive_f64.rs
@@ -9,7 +9,7 @@
 //! infinite), ensuring that the type can safely implement [`Ord`] and [`Eq`]
 //! without panicking.
 
-use core::{cmp, f64, hash};
+use core::{cmp, f64, fmt, hash, ops};
 
 /// A positive, possibly-infinite, floating-point number.
 #[derive(Copy, Clone, PartialEq, Debug)]
@@ -31,6 +31,13 @@ impl PositiveF64 {
 
     /// Returns the `PositiveF64` value.
     pub fn value(&self) -> f64 { self.0 }
+
+    /// Normalizes two [`PositiveF64`] values into a valid probability distribution.
+    #[must_use]
+    pub fn normalized(a: Self, b: Self) -> (Self, Self) {
+        let sum = a.0 + b.0;
+        (Self(a.0 / sum), Self(b.0 / sum))
+    }
 }
 
 impl Eq for PositiveF64 {}
@@ -52,3 +59,19 @@ impl Ord for PositiveF64 {
 impl hash::Hash for PositiveF64 {
     fn hash<H: hash::Hasher>(&self, state: &mut H) { self.0.to_bits().hash(state); }
 }
+
+impl fmt::Display for PositiveF64 {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Display::fmt(&self.0, f) }
+}
+
+impl ops::Add for PositiveF64 {
+    type Output = Self;
+
+    fn add(self, rhs: Self) -> Self::Output { Self(self.0 + rhs.0) }
+}
+
+impl ops::Mul for PositiveF64 {
+    type Output = Self;
+
+    fn mul(self, rhs: Self) -> Self::Output { Self(self.0 * rhs.0) }
+}
diff --git a/src/primitives/threshold.rs b/src/primitives/threshold.rs
index a29f89e30..5d552f447 100644
--- a/src/primitives/threshold.rs
+++ b/src/primitives/threshold.rs
@@ -10,6 +10,7 @@ use core::{cmp, fmt, iter};
 #[cfg(any(feature = "std", test))]
 use std::vec;
 
+use super::positive_f64::PositiveF64;
 use crate::ToPublicKey;
 
 /// Error parsing an absolute locktime.
@@ -203,6 +204,9 @@ impl<T, const MAX: usize> Threshold<T, MAX> {
     /// Accessor for the threshold value.
     pub const fn k(&self) -> usize { self.k }
 
+    /// Returns the threshold ratio (k / n) as a positive real number.
+    pub fn k_over_n(&self) -> PositiveF64 { PositiveF64(self.k() as f64 / self.n() as f64) }
+
     /// Accessor for the underlying data.
     pub fn data(&self) -> &[T] { &self.inner }
 

From a86995aa6293d73e818fe5c84e4e88072acdb27d Mon Sep 17 00:00:00 2001
From: Abeeujah <abeeujah@gmail.com>
Date: Sat, 6 Jun 2026 14:06:48 +0100
Subject: [PATCH 4/7] Add `parse_probability` helper for PositiveF64

Introduce a `parse_probability` function to parse non-zero strings
into PositiveF64 values.

This implementation wraps around the `parse_num_nonzero` function
to safely parse string inputs, enforcing the non-zero invariant.
---
 src/expression/mod.rs          | 10 +++++++++-
 src/primitives/positive_f64.rs | 22 ++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/src/expression/mod.rs b/src/expression/mod.rs
index 6bfdfd055..5470dae35 100644
--- a/src/expression/mod.rs
+++ b/src/expression/mod.rs
@@ -34,7 +34,9 @@ pub use self::error::{ParseNumError, ParseThresholdError, ParseTreeError};
 use crate::blanket_traits::StaticDebugAndDisplay;
 use crate::descriptor::checksum::verify_checksum;
 use crate::prelude::*;
-use crate::{AbsLockTime, Error, ParseError, RelLockTime, Threshold, MAX_RECURSION_DEPTH};
+use crate::{
+    AbsLockTime, Error, ParseError, PositiveF64, RelLockTime, Threshold, MAX_RECURSION_DEPTH,
+};
 
 /// Allowed characters are descriptor strings.
 pub const INPUT_CHARSET: &str = "0123456789()[],'/*abcdefgh@:$%{}IJKLMNOPQRSTUVWXYZ&+-.;<=>?!^_|~ijklmnopqrstuvwxyzABCDEFGH`#\"\\ ";
@@ -691,6 +693,12 @@ pub fn parse_num_nonzero(s: &str, context: &'static str) -> Result<u32, ParseNum
     u32::from_str(s).map_err(ParseNumError::StdParse)
 }
 
+/// Parse a string as a PositiveF64, forbidding zero.
+pub fn parse_probability(s: &str, context: &'static str) -> Result<PositiveF64, ParseNumError> {
+    let parsed = parse_num_nonzero(s, context)?;
+    PositiveF64::try_from(parsed).map_err(|_| ParseNumError::IllegalZero { context })
+}
+
 /// Parse a string as a u32, for timelocks or thresholds
 pub fn parse_num(s: &str) -> Result<u32, ParseNumError> {
     if s == "0" {
diff --git a/src/primitives/positive_f64.rs b/src/primitives/positive_f64.rs
index a2d6e36d3..7f8d981ef 100644
--- a/src/primitives/positive_f64.rs
+++ b/src/primitives/positive_f64.rs
@@ -40,6 +40,18 @@ impl PositiveF64 {
     }
 }
 
+impl TryFrom<u32> for PositiveF64 {
+    type Error = NonZeroExpected;
+
+    fn try_from(value: u32) -> Result<Self, Self::Error> {
+        if value == 0 {
+            Err(NonZeroExpected)
+        } else {
+            Ok(Self(value as f64))
+        }
+    }
+}
+
 impl Eq for PositiveF64 {}
 
 // We could derive PartialOrd, but we can't derive Ord, and clippy wants us
@@ -75,3 +87,13 @@ impl ops::Mul for PositiveF64 {
 
     fn mul(self, rhs: Self) -> Self::Output { Self(self.0 * rhs.0) }
 }
+
+#[derive(Copy, Clone, Debug, PartialEq)]
+pub struct NonZeroExpected;
+
+impl fmt::Display for NonZeroExpected {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { write!(f, "value must be non-zero") }
+}
+
+#[cfg(feature = "std")]
+impl std::error::Error for NonZeroExpected {}

From 976fb334fa87bbac3978f90933c74cb5558af17a Mon Sep 17 00:00:00 2001
From: Abeeujah <abeeujah@gmail.com>
Date: Sat, 6 Jun 2026 16:51:36 +0100
Subject: [PATCH 5/7] Use PositiveF64 for probabilities in policy module

Change `Or` weights from usize to PositiveF64 and all probability
parameters from raw f64 to PositiveF64, making invalid states
unrepresentable. Thread Threshold through the compiler instead
of extracting k/n pairs.

`parse_num_nonzero` visibility scope has been refactored to private
the `parse_probability` method is now used in constructing the
`Policy::Or` variant.
---
 src/expression/mod.rs  |   2 +-
 src/policy/compiler.rs | 175 ++++++++++++++++++++++-------------------
 src/policy/concrete.rs |  25 +++---
 3 files changed, 108 insertions(+), 94 deletions(-)

diff --git a/src/expression/mod.rs b/src/expression/mod.rs
index 5470dae35..84644915f 100644
--- a/src/expression/mod.rs
+++ b/src/expression/mod.rs
@@ -681,7 +681,7 @@ impl<'a> Tree<'a> {
 }
 
 /// Parse a string as a u32, forbidding zero.
-pub fn parse_num_nonzero(s: &str, context: &'static str) -> Result<u32, ParseNumError> {
+fn parse_num_nonzero(s: &str, context: &'static str) -> Result<u32, ParseNumError> {
     if s == "0" {
         return Err(ParseNumError::IllegalZero { context });
     }
diff --git a/src/policy/compiler.rs b/src/policy/compiler.rs
index 3c02f1243..7370454dc 100644
--- a/src/policy/compiler.rs
+++ b/src/policy/compiler.rs
@@ -16,7 +16,7 @@ use crate::miniscript::types::{self, ErrorKind, ExtData, Type};
 use crate::miniscript::ScriptContext;
 use crate::policy::Concrete;
 use crate::prelude::*;
-use crate::{policy, Miniscript, MiniscriptKey, PositiveF64, Terminal};
+use crate::{policy, Miniscript, MiniscriptKey, PositiveF64, Terminal, Threshold};
 
 type PolicyCache<Pk, Ctx> = BTreeMap<
     (Concrete<Pk>, PositiveF64, Option<PositiveF64>),
@@ -143,8 +143,8 @@ impl CompilationKey {
     }
 
     /// Helper to create compilation key from components
-    fn from_type(ty: Type, expensive_verify: bool, dissat_prob: Option<f64>) -> Self {
-        Self { ty, expensive_verify, dissat_prob: dissat_prob.map(PositiveF64::new) }
+    fn from_type(ty: Type, expensive_verify: bool, dissat_prob: Option<PositiveF64>) -> Self {
+        Self { ty, expensive_verify, dissat_prob }
     }
 }
 
@@ -366,14 +366,14 @@ impl CompilerExtData {
         }
     }
 
-    fn threshold<S>(k: usize, n: usize, mut sub_ck: S) -> Self
+    fn threshold<T, const MAX: usize, S>(thresh: &Threshold<T, MAX>, mut sub_ck: S) -> Self
     where
         S: FnMut(usize) -> Self,
     {
-        let k_over_n = k as f64 / n as f64;
+        let k_over_n = thresh.k_over_n().value();
         let mut sat_cost = 0.0;
         let mut dissat_cost = 0.0;
-        for i in 0..n {
+        for i in 0..thresh.n() {
             let sub = sub_ck(i);
             sat_cost += sub.sat_cost;
             dissat_cost += sub.dissat_cost.unwrap();
@@ -477,7 +477,7 @@ impl CompilerExtData {
                 Self::and_or(atype, btype, ctype)
             }
             Terminal::Thresh(ref thresh) => {
-                Self::threshold(thresh.k(), thresh.n(), |n| get_child(&thresh.data()[n].node, n))
+                Self::threshold(thresh, |n| get_child(&thresh.data()[n].node, n))
             }
         }
     }
@@ -496,14 +496,14 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> AstElemExt<Pk, Ctx> {
     /// Compute a 1-dimensional cost, given a probability of satisfaction
     /// and a probability of dissatisfaction; if `dissat_prob` is `None`
     /// then it is assumed that dissatisfaction never occurs
-    fn cost_1d(&self, sat_prob: f64, dissat_prob: Option<f64>) -> f64 {
-        self.ms.ext.pk_cost as f64
-            + self.comp_ext_data.sat_cost * sat_prob
+    fn cost_1d(&self, sat_prob: PositiveF64, dissat_prob: Option<PositiveF64>) -> PositiveF64 {
+        PositiveF64::new(self.ms.ext.pk_cost as f64)
+            + PositiveF64::new(self.comp_ext_data.sat_cost) * sat_prob
             + match (dissat_prob, self.comp_ext_data.dissat_cost) {
-                (Some(prob), Some(cost)) => prob * cost,
-                (Some(_), None) => f64::INFINITY,
-                (None, Some(_)) => 0.0,
-                (None, None) => 0.0,
+                (Some(prob), Some(cost)) => prob * PositiveF64::new(cost),
+                (Some(_), None) => PositiveF64::new(f64::INFINITY),
+                (None, Some(_)) => PositiveF64::new(0.0),
+                (None, None) => PositiveF64::new(0.0),
             }
     }
 }
@@ -648,8 +648,8 @@ fn all_casts<Pk: MiniscriptKey, Ctx: ScriptContext>() -> [Cast<Pk, Ctx>; 10] {
 fn insert_elem<Pk: MiniscriptKey, Ctx: ScriptContext>(
     map: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
     elem: AstElemExt<Pk, Ctx>,
-    sat_prob: f64,
-    dissat_prob: Option<f64>,
+    sat_prob: PositiveF64,
+    dissat_prob: Option<PositiveF64>,
 ) -> bool {
     // We check before compiling that non-malleable satisfactions exist, and it appears that
     // there are no cases when malleable satisfactions beat non-malleable ones (and if there
@@ -699,8 +699,8 @@ fn insert_elem<Pk: MiniscriptKey, Ctx: ScriptContext>(
 fn insert_elem_closure<Pk: MiniscriptKey, Ctx: ScriptContext>(
     map: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
     astelem_ext: AstElemExt<Pk, Ctx>,
-    sat_prob: f64,
-    dissat_prob: Option<f64>,
+    sat_prob: PositiveF64,
+    dissat_prob: Option<PositiveF64>,
 ) {
     let mut cast_stack: VecDeque<AstElemExt<Pk, Ctx>> = VecDeque::new();
     if insert_elem(map, astelem_ext.clone(), sat_prob, dissat_prob) {
@@ -735,8 +735,8 @@ fn insert_best_wrapped<Pk: MiniscriptKey, Ctx: ScriptContext>(
     policy: &Concrete<Pk>,
     map: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
     data: AstElemExt<Pk, Ctx>,
-    sat_prob: f64,
-    dissat_prob: Option<f64>,
+    sat_prob: PositiveF64,
+    dissat_prob: Option<PositiveF64>,
 ) -> Result<(), CompilerError> {
     insert_elem_closure(map, data, sat_prob, dissat_prob);
 
@@ -759,17 +759,15 @@ fn insert_best_wrapped<Pk: MiniscriptKey, Ctx: ScriptContext>(
 fn best_compilations<Pk, Ctx>(
     policy_cache: &mut PolicyCache<Pk, Ctx>,
     policy: &Concrete<Pk>,
-    sat_prob: f64,
-    dissat_prob: Option<f64>,
+    sat_prob: PositiveF64,
+    dissat_prob: Option<PositiveF64>,
 ) -> Result<BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>, CompilerError>
 where
     Pk: MiniscriptKey,
     Ctx: ScriptContext,
 {
     //Check the cache for hits
-    let ord_sat_prob = PositiveF64::new(sat_prob);
-    let ord_dissat_prob = dissat_prob.map(PositiveF64::new);
-    if let Some(ret) = policy_cache.get(&(policy.clone(), ord_sat_prob, ord_dissat_prob)) {
+    if let Some(ret) = policy_cache.get(&(policy.clone(), sat_prob, dissat_prob)) {
         return Ok(ret.clone());
     }
 
@@ -829,22 +827,23 @@ where
             let mut q_zero_left =
                 best_compilations(policy_cache, subs[0].as_ref(), sat_prob, None)?;
 
-            compile_binary!(&mut left, &mut right, [1.0, 1.0], Terminal::AndB);
-            compile_binary!(&mut right, &mut left, [1.0, 1.0], Terminal::AndB);
-            compile_binary!(&mut left, &mut right, [1.0, 1.0], Terminal::AndV);
-            compile_binary!(&mut right, &mut left, [1.0, 1.0], Terminal::AndV);
+            let one = PositiveF64::new(1.0);
+            let zero = PositiveF64::new(0.0);
+            compile_binary!(&mut left, &mut right, [one, one], Terminal::AndB);
+            compile_binary!(&mut right, &mut left, [one, one], Terminal::AndB);
+            compile_binary!(&mut left, &mut right, [one, one], Terminal::AndV);
+            compile_binary!(&mut right, &mut left, [one, one], Terminal::AndV);
             let mut zero_comp = BTreeMap::new();
             zero_comp.insert(
                 CompilationKey::from_type(Type::FALSE, ExtData::FALSE.has_free_verify, dissat_prob),
                 AstElemExt::terminal(Miniscript::FALSE),
             );
-            compile_tern!(&mut left, &mut q_zero_right, &mut zero_comp, [1.0, 0.0]);
-            compile_tern!(&mut right, &mut q_zero_left, &mut zero_comp, [1.0, 0.0]);
+            compile_tern!(&mut left, &mut q_zero_right, &mut zero_comp, [one, zero]);
+            compile_tern!(&mut right, &mut q_zero_left, &mut zero_comp, [one, zero]);
         }
         Concrete::Or(ref subs) => {
-            let total = (subs[0].0 + subs[1].0) as f64;
-            let lw = subs[0].0 as f64 / total;
-            let rw = subs[1].0 as f64 / total;
+            let (lw, rw) = PositiveF64::normalized(subs[0].0, subs[1].0);
+            let zero = PositiveF64::new(0.0);
 
             //and-or
             if let (Concrete::And(x), _) = (subs[0].1.as_ref(), subs[1].1.as_ref()) {
@@ -852,7 +851,7 @@ where
                     policy_cache,
                     x[0].as_ref(),
                     lw * sat_prob,
-                    Some(dissat_prob.unwrap_or(0 as f64) + rw * sat_prob),
+                    Some(dissat_prob.unwrap_or(zero) + rw * sat_prob),
                 )?;
                 let mut a2 = best_compilations(policy_cache, x[0].as_ref(), lw * sat_prob, None)?;
 
@@ -860,7 +859,7 @@ where
                     policy_cache,
                     x[1].as_ref(),
                     lw * sat_prob,
-                    Some(dissat_prob.unwrap_or(0 as f64) + rw * sat_prob),
+                    Some(dissat_prob.unwrap_or(zero) + rw * sat_prob),
                 )?;
                 let mut b2 = best_compilations(policy_cache, x[1].as_ref(), lw * sat_prob, None)?;
 
@@ -879,7 +878,7 @@ where
                     policy_cache,
                     x[0].as_ref(),
                     rw * sat_prob,
-                    Some(dissat_prob.unwrap_or(0 as f64) + lw * sat_prob),
+                    Some(dissat_prob.unwrap_or(zero) + lw * sat_prob),
                 )?;
                 let mut a2 = best_compilations(policy_cache, x[0].as_ref(), rw * sat_prob, None)?;
 
@@ -887,7 +886,7 @@ where
                     policy_cache,
                     x[1].as_ref(),
                     rw * sat_prob,
-                    Some(dissat_prob.unwrap_or(0 as f64) + lw * sat_prob),
+                    Some(dissat_prob.unwrap_or(zero) + lw * sat_prob),
                 )?;
                 let mut b2 = best_compilations(policy_cache, x[1].as_ref(), rw * sat_prob, None)?;
 
@@ -902,9 +901,9 @@ where
                 compile_tern!(&mut b1, &mut a2, &mut c, [rw, lw]);
             };
 
-            let dissat_probs = |w: f64| -> Vec<Option<f64>> {
+            let dissat_probs = |w: PositiveF64| -> Vec<Option<PositiveF64>> {
                 vec![
-                    Some(dissat_prob.unwrap_or(0 as f64) + w * sat_prob),
+                    Some(dissat_prob.unwrap_or(zero) + w * sat_prob),
                     Some(w * sat_prob),
                     dissat_prob,
                     None,
@@ -953,7 +952,12 @@ where
         Concrete::Thresh(ref thresh) => {
             let k = thresh.k();
             let n = thresh.n();
-            let k_over_n = k as f64 / n as f64;
+
+            let (sat_ratio, dissat_ratio) = PositiveF64::normalized(
+                PositiveF64::new(k as f64),
+                PositiveF64::new((n - k) as f64),
+            );
+            let zero = PositiveF64::new(0.0);
 
             let mut sub_ext_data = Vec::with_capacity(n);
 
@@ -962,13 +966,13 @@ where
 
             let mut min_value = (0, f64::INFINITY);
             for (i, ast) in thresh.iter().enumerate() {
-                let sp = sat_prob * k_over_n;
+                let sp = sat_prob * sat_ratio;
                 //Expressions must be dissatisfiable
-                let dp = Some(dissat_prob.unwrap_or(0 as f64) + (1.0 - k_over_n) * sat_prob);
+                let dp = Some(dissat_prob.unwrap_or(zero) + dissat_ratio * sat_prob);
                 let be = best(types::Base::B, policy_cache, ast.as_ref(), sp, dp)?;
                 let bw = best(types::Base::W, policy_cache, ast.as_ref(), sp, dp)?;
 
-                let diff = be.cost_1d(sp, dp) - bw.cost_1d(sp, dp);
+                let diff = be.cost_1d(sp, dp).value() - bw.cost_1d(sp, dp).value();
                 best_es.push((be.comp_ext_data, be));
                 best_ws.push((bw.comp_ext_data, bw));
 
@@ -1003,7 +1007,7 @@ where
             if let Ok(ms) = Miniscript::from_ast(ast) {
                 let ast_ext = AstElemExt {
                     ms: Arc::new(ms),
-                    comp_ext_data: CompilerExtData::threshold(k, n, |i| sub_ext_data[i]),
+                    comp_ext_data: CompilerExtData::threshold(thresh, |i| sub_ext_data[i]),
                 };
                 insert_wrap!(ast_ext);
             }
@@ -1045,7 +1049,7 @@ where
         }
     }
     for k in ret.keys() {
-        debug_assert_eq!(k.dissat_prob, ord_dissat_prob);
+        debug_assert_eq!(k.dissat_prob, dissat_prob);
     }
     if ret.is_empty() {
         // The only reason we are discarding elements out of compiler is because
@@ -1056,7 +1060,7 @@ where
         // before calling this compile function
         Err(CompilerError::LimitsExceeded)
     } else {
-        policy_cache.insert((policy.clone(), ord_sat_prob, ord_dissat_prob), ret.clone());
+        policy_cache.insert((policy.clone(), sat_prob, dissat_prob), ret.clone());
         Ok(ret)
     }
 }
@@ -1071,9 +1075,9 @@ fn compile_binary<Pk, Ctx, F>(
     ret: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
     left_comp: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
     right_comp: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
-    weights: [f64; 2],
-    sat_prob: f64,
-    dissat_prob: Option<f64>,
+    weights: [PositiveF64; 2],
+    sat_prob: PositiveF64,
+    dissat_prob: Option<PositiveF64>,
     bin_func: F,
 ) -> Result<(), CompilerError>
 where
@@ -1086,8 +1090,8 @@ where
         for r in right_comp.values_mut() {
             let rref = Arc::clone(&r.ms);
             let ast = bin_func(Arc::clone(&lref), Arc::clone(&rref));
-            l.comp_ext_data.branch_prob = Some(weights[0]);
-            r.comp_ext_data.branch_prob = Some(weights[1]);
+            l.comp_ext_data.branch_prob = Some(weights[0].value());
+            r.comp_ext_data.branch_prob = Some(weights[1].value());
             if let Ok(new_ext) = AstElemExt::binary(ast, l, r) {
                 insert_best_wrapped(policy_cache, policy, ret, new_ext, sat_prob, dissat_prob)?;
             }
@@ -1107,9 +1111,9 @@ fn compile_tern<Pk: MiniscriptKey, Ctx: ScriptContext>(
     a_comp: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
     b_comp: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
     c_comp: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
-    weights: [f64; 2],
-    sat_prob: f64,
-    dissat_prob: Option<f64>,
+    weights: [PositiveF64; 2],
+    sat_prob: PositiveF64,
+    dissat_prob: Option<PositiveF64>,
 ) -> Result<(), CompilerError> {
     for a in a_comp.values_mut() {
         let aref = Arc::clone(&a.ms);
@@ -1118,9 +1122,9 @@ fn compile_tern<Pk: MiniscriptKey, Ctx: ScriptContext>(
             for c in c_comp.values_mut() {
                 let cref = Arc::clone(&c.ms);
                 let ast = Terminal::AndOr(Arc::clone(&aref), Arc::clone(&bref), Arc::clone(&cref));
-                a.comp_ext_data.branch_prob = Some(weights[0]);
-                b.comp_ext_data.branch_prob = Some(weights[0]);
-                c.comp_ext_data.branch_prob = Some(weights[1]);
+                a.comp_ext_data.branch_prob = Some(weights[0].value());
+                b.comp_ext_data.branch_prob = Some(weights[0].value());
+                c.comp_ext_data.branch_prob = Some(weights[1].value());
                 if let Ok(new_ext) = AstElemExt::ternary(ast, a, b, c) {
                     insert_best_wrapped(policy_cache, policy, ret, new_ext, sat_prob, dissat_prob)?;
                 }
@@ -1135,7 +1139,7 @@ pub fn best_compilation<Pk: MiniscriptKey, Ctx: ScriptContext>(
     policy: &Concrete<Pk>,
 ) -> Result<Miniscript<Pk, Ctx>, CompilerError> {
     let mut policy_cache = PolicyCache::<Pk, Ctx>::new();
-    let x = &*best_t(&mut policy_cache, policy, 1.0, None)?.ms;
+    let x = &*best_t(&mut policy_cache, policy, PositiveF64::new(1.0), None)?.ms;
     if !x.ty.mall.signed {
         Err(CompilerError::TopLevelSigless)
     } else if !x.ty.mall.non_malleable {
@@ -1149,8 +1153,8 @@ pub fn best_compilation<Pk: MiniscriptKey, Ctx: ScriptContext>(
 fn best_t<Pk, Ctx>(
     policy_cache: &mut PolicyCache<Pk, Ctx>,
     policy: &Concrete<Pk>,
-    sat_prob: f64,
-    dissat_prob: Option<f64>,
+    sat_prob: PositiveF64,
+    dissat_prob: Option<PositiveF64>,
 ) -> Result<AstElemExt<Pk, Ctx>, CompilerError>
 where
     Pk: MiniscriptKey,
@@ -1158,12 +1162,9 @@ where
 {
     best_compilations(policy_cache, policy, sat_prob, dissat_prob)?
         .into_iter()
-        .filter(|&(key, _)| {
-            key.ty.corr.base == types::Base::B
-                && key.dissat_prob == dissat_prob.map(PositiveF64::new)
-        })
+        .filter(|&(key, _)| key.ty.corr.base == types::Base::B && key.dissat_prob == dissat_prob)
         .map(|(_, val)| val)
-        .min_by_key(|ext| PositiveF64::new(ext.cost_1d(sat_prob, dissat_prob)))
+        .min_by_key(|ext| ext.cost_1d(sat_prob, dissat_prob))
         .ok_or(CompilerError::LimitsExceeded)
 }
 
@@ -1172,8 +1173,8 @@ fn best<Pk, Ctx>(
     basic_type: types::Base,
     policy_cache: &mut PolicyCache<Pk, Ctx>,
     policy: &Concrete<Pk>,
-    sat_prob: f64,
-    dissat_prob: Option<f64>,
+    sat_prob: PositiveF64,
+    dissat_prob: Option<PositiveF64>,
 ) -> Result<AstElemExt<Pk, Ctx>, CompilerError>
 where
     Pk: MiniscriptKey,
@@ -1185,10 +1186,10 @@ where
             key.ty.corr.base == basic_type
                 && key.ty.corr.unit
                 && val.ms.ty.mall.dissat == types::Dissat::Unique
-                && key.dissat_prob == dissat_prob.map(PositiveF64::new)
+                && key.dissat_prob == dissat_prob
         })
         .map(|(_, val)| val)
-        .min_by_key(|ext| PositiveF64::new(ext.cost_1d(sat_prob, dissat_prob)))
+        .min_by_key(|ext| ext.cost_1d(sat_prob, dissat_prob))
         .ok_or(CompilerError::LimitsExceeded)
 }
 
@@ -1290,18 +1291,23 @@ mod tests {
     #[test]
     fn compile_q() {
         let policy = SPolicy::from_str("or(1@and(pk(A),pk(B)),127@pk(C))").expect("parsing");
-        let compilation: TapAstElemExt = best_t(&mut BTreeMap::new(), &policy, 1.0, None).unwrap();
+        let compilation: TapAstElemExt =
+            best_t(&mut BTreeMap::new(), &policy, PositiveF64::new(1.0), None).unwrap();
 
-        assert_eq!(compilation.cost_1d(1.0, None), 87.0 + 67.0390625);
+        assert_eq!(compilation.cost_1d(PositiveF64::new(1.0), None).value(), 87.0 + 67.0390625);
         assert_eq!(policy.lift().unwrap().sorted(), compilation.ms.lift().unwrap().sorted());
 
         // compile into taproot context to avoid limit errors
         let policy = SPolicy::from_str(
                 "and(and(and(or(127@thresh(2,pk(A),pk(B),thresh(2,or(127@pk(A),1@pk(B)),after(100),or(and(pk(C),after(200)),and(pk(D),sha256(66687aadf862bd776c8fc18b8e9f8e20089714856ee233b3902a591d0d5f2925))),pk(E))),1@pk(F)),sha256(66687aadf862bd776c8fc18b8e9f8e20089714856ee233b3902a591d0d5f2925)),or(127@pk(G),1@after(300))),or(127@after(400),pk(H)))"
             ).expect("parsing");
-        let compilation: TapAstElemExt = best_t(&mut BTreeMap::new(), &policy, 1.0, None).unwrap();
+        let compilation: TapAstElemExt =
+            best_t(&mut BTreeMap::new(), &policy, PositiveF64::new(1.0), None).unwrap();
 
-        assert_eq!(compilation.cost_1d(1.0, None), 433.0 + 275.7909749348958);
+        assert_eq!(
+            compilation.cost_1d(PositiveF64::new(1.0), None).value(),
+            433.0 + 275.7909749348958
+        );
         assert_eq!(policy.lift().unwrap().sorted(), compilation.ms.lift().unwrap().sorted());
     }
 
@@ -1346,14 +1352,14 @@ mod tests {
         // Liquid policy
         let policy: BPolicy = Concrete::Or(vec![
             (
-                127,
+                PositiveF64::new(127.0),
                 Arc::new(Concrete::Thresh(
                     Threshold::from_iter(3, key_pol[0..5].iter().map(|p| (p.clone()).into()))
                         .unwrap(),
                 )),
             ),
             (
-                1,
+                PositiveF64::new(1.0),
                 Arc::new(Concrete::And(vec![
                     Arc::new(Concrete::Older(RelLockTime::from_height(10000).unwrap())),
                     Arc::new(Concrete::Thresh(
@@ -1522,8 +1528,8 @@ mod tests {
             .collect();
 
         let thresh_res: Result<SegwitMiniScript, _> = Concrete::Or(vec![
-            (1, Arc::new(Concrete::Thresh(Threshold::and_n(keys_a)))),
-            (1, Arc::new(Concrete::Thresh(Threshold::and_n(keys_b)))),
+            (PositiveF64::new(1.0), Arc::new(Concrete::Thresh(Threshold::and_n(keys_a)))),
+            (PositiveF64::new(1.0), Arc::new(Concrete::Thresh(Threshold::and_n(keys_b)))),
         ])
         .compile();
         let script_size = thresh_res.clone().map(|m| m.script_size());
@@ -1593,14 +1599,21 @@ mod tests {
         // Test that we refuse to compile policies with duplicated keys
         let (keys, _) = pubkeys_and_a_sig(1);
         let key = Arc::new(Concrete::Key(keys[0]));
-        let res =
-            Concrete::Or(vec![(1, Arc::clone(&key)), (1, Arc::clone(&key))]).compile::<Segwitv0>();
+        let res = Concrete::Or(vec![
+            (PositiveF64::new(1.0), Arc::clone(&key)),
+            (PositiveF64::new(1.0), Arc::clone(&key)),
+        ])
+        .compile::<Segwitv0>();
         assert_eq!(
             res,
             Err(CompilerError::PolicyError(policy::concrete::PolicyError::DuplicatePubKeys))
         );
         // Same for legacy
-        let res = Concrete::Or(vec![(1, key.clone()), (1, key)]).compile::<Legacy>();
+        let res = Concrete::Or(vec![
+            (PositiveF64::new(1.0), key.clone()),
+            (PositiveF64::new(1.0), key),
+        ])
+        .compile::<Legacy>();
         assert_eq!(
             res,
             Err(CompilerError::PolicyError(policy::concrete::PolicyError::DuplicatePubKeys))
diff --git a/src/policy/concrete.rs b/src/policy/concrete.rs
index a9c07ee19..74f7e9a71 100644
--- a/src/policy/concrete.rs
+++ b/src/policy/concrete.rs
@@ -66,7 +66,7 @@ pub enum Policy<Pk: MiniscriptKey> {
     And(Vec<Arc<Self>>),
     /// A list of sub-policies, one of which must be satisfied, along with
     /// relative probabilities for each one.
-    Or(Vec<(usize, Arc<Self>)>),
+    Or(Vec<(PositiveF64, Arc<Self>)>),
     /// A set of descriptors, satisfactions must be provided for `k` of them.
     Thresh(Threshold<Arc<Self>, 0>),
 }
@@ -132,9 +132,10 @@ impl<'p, Pk: MiniscriptKey> Iterator for TapleafProbabilityIter<'p, Pk> {
 
             match top {
                 Policy::Or(ref subs) => {
-                    let total_sub_prob = subs.iter().map(|prob_sub| prob_sub.0).sum::<usize>();
+                    let total_sub_prob =
+                        subs.iter().map(|prob_sub| prob_sub.0.value()).sum::<f64>();
                     for (sub_prob, sub) in subs.iter().rev() {
-                        let ratio = *sub_prob as f64 / total_sub_prob as f64;
+                        let ratio = sub_prob.value() / total_sub_prob;
                         self.stack.push((top_prob * ratio, sub));
                     }
                 }
@@ -456,9 +457,9 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
     fn enumerate_pol(&self, prob: f64) -> Vec<(f64, Arc<Self>)> {
         match self {
             Self::Or(subs) => {
-                let total_odds = subs.iter().fold(0, |acc, x| acc + x.0);
+                let total_odds = subs.iter().fold(0.0, |acc, x| acc + x.0.value());
                 subs.iter()
-                    .map(|(odds, pol)| (prob * *odds as f64 / total_odds as f64, pol.clone()))
+                    .map(|(odds, pol)| (prob * odds.value() / total_odds, pol.clone()))
                     .collect::<Vec<_>>()
             }
             Self::Thresh(ref thresh) if thresh.is_or() => {
@@ -481,9 +482,9 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
     fn enumerate_pol_native(&self, prob: f64) -> Vec<(f64, Arc<Self>)> {
         match self {
             Self::Or(subs) => {
-                let total_odds = subs.iter().fold(0, |acc, x| acc + x.0);
+                let total_odds = subs.iter().fold(0.0, |acc, x| acc + x.0.value());
                 subs.iter()
-                    .map(|(odds, pol)| (prob * *odds as f64 / total_odds as f64, pol.clone()))
+                    .map(|(odds, pol)| (prob * odds.value() / total_odds, pol.clone()))
                     .collect::<Vec<_>>()
             }
             Self::Thresh(ref thresh) if thresh.is_or() => {
@@ -972,7 +973,7 @@ impl<Pk: FromStrKey> expression::FromTree for Policy<Pk> {
             .map_err(From::from)
             .map_err(Error::Parse)?;
 
-        let mut stack = Vec::<(usize, _)>::with_capacity(128);
+        let mut stack = Vec::<(PositiveF64, _)>::with_capacity(128);
         for node in root.pre_order_iter().rev() {
             let allow_prob;
             // Before doing anything else, check if this is the inner value of a terminal.
@@ -1005,10 +1006,10 @@ impl<Pk: FromStrKey> expression::FromTree for Policy<Pk> {
             };
 
             let frag_prob = match frag_prob {
-                None => 1,
-                Some(s) => expression::parse_num_nonzero(s, "fragment probability")
+                None => PositiveF64::new(1.0),
+                Some(s) => expression::parse_probability(s, "fragment probability")
                     .map_err(From::from)
-                    .map_err(Error::Parse)? as usize,
+                    .map_err(Error::Parse)?,
             };
 
             let new =
@@ -1163,7 +1164,7 @@ pub enum TreeChildren<'a, Pk: MiniscriptKey> {
     /// A conjunction or threshold node's children.
     And(&'a [Arc<Policy<Pk>>]),
     /// A disjunction node's children.
-    Or(&'a [(usize, Arc<Policy<Pk>>)]),
+    Or(&'a [(PositiveF64, Arc<Policy<Pk>>)]),
 }
 
 impl<'a, Pk: MiniscriptKey> TreeLike for &'a Policy<Pk> {

From 024326713eaac60fa4df2ebea499199ac62ef8fa Mon Sep 17 00:00:00 2001
From: Abeeujah <abeeujah@gmail.com>
Date: Fri, 12 Jun 2026 22:39:26 +0100
Subject: [PATCH 6/7] Drop Zero Construction of PositiveF64

Replace ad-hoc `PositiveF64::new(0.0)` placeholders with
Option-based patterns and a new conditional_add helper.

- Add `PositiveF64::conditional_add` for adding an optional probability.
- Change `compile_tern` branch weights from [PositiveF64; 2] to
  (PositiveF64, Option<PositiveF64>).
- Switch tapleaf enumeration prob to Option<Reverse<PositiveF64>>.
- Refactor `cost_1d` to use `conditional_add` instead of match branches.
---
 src/policy/compiler.rs         | 86 +++++++++++++++++++++-------------
 src/policy/concrete.rs         |  7 +--
 src/primitives/positive_f64.rs |  5 ++
 3 files changed, 62 insertions(+), 36 deletions(-)

diff --git a/src/policy/compiler.rs b/src/policy/compiler.rs
index 7370454dc..74359fa35 100644
--- a/src/policy/compiler.rs
+++ b/src/policy/compiler.rs
@@ -497,14 +497,16 @@ impl<Pk: MiniscriptKey, Ctx: ScriptContext> AstElemExt<Pk, Ctx> {
     /// and a probability of dissatisfaction; if `dissat_prob` is `None`
     /// then it is assumed that dissatisfaction never occurs
     fn cost_1d(&self, sat_prob: PositiveF64, dissat_prob: Option<PositiveF64>) -> PositiveF64 {
-        PositiveF64::new(self.ms.ext.pk_cost as f64)
-            + PositiveF64::new(self.comp_ext_data.sat_cost) * sat_prob
-            + match (dissat_prob, self.comp_ext_data.dissat_cost) {
-                (Some(prob), Some(cost)) => prob * PositiveF64::new(cost),
-                (Some(_), None) => PositiveF64::new(f64::INFINITY),
-                (None, Some(_)) => PositiveF64::new(0.0),
-                (None, None) => PositiveF64::new(0.0),
-            }
+        let sat_cost = (self.comp_ext_data.sat_cost > 0.0)
+            .then(|| PositiveF64::new(self.comp_ext_data.sat_cost) * sat_prob);
+        let base = PositiveF64::new(self.ms.ext.pk_cost as f64).conditional_add(sat_cost);
+        let dissat_cost = match (dissat_prob, self.comp_ext_data.dissat_cost) {
+            (Some(_), Some(0.0)) => None,
+            (Some(prob), Some(cost)) => Some(prob * PositiveF64::new(cost)),
+            (Some(_), None) => Some(PositiveF64::INFINITY),
+            (None, _) => None,
+        };
+        base.conditional_add(dissat_cost)
     }
 }
 
@@ -785,8 +787,19 @@ where
         };
     }
     macro_rules! compile_tern {
-        ($a:expr, $b:expr, $c: expr, $w: expr) => {
-            compile_tern(policy_cache, policy, &mut ret, $a, $b, $c, $w, sat_prob, dissat_prob)?
+        ($a:expr, $b:expr, $c: expr, [$ab_prob: expr, $c_prob: expr]) => {
+            compile_tern(
+                policy_cache,
+                policy,
+                &mut ret,
+                $a,
+                $b,
+                $c,
+                $ab_prob,
+                $c_prob,
+                sat_prob,
+                dissat_prob,
+            )?
         };
     }
 
@@ -828,7 +841,6 @@ where
                 best_compilations(policy_cache, subs[0].as_ref(), sat_prob, None)?;
 
             let one = PositiveF64::new(1.0);
-            let zero = PositiveF64::new(0.0);
             compile_binary!(&mut left, &mut right, [one, one], Terminal::AndB);
             compile_binary!(&mut right, &mut left, [one, one], Terminal::AndB);
             compile_binary!(&mut left, &mut right, [one, one], Terminal::AndV);
@@ -838,12 +850,11 @@ where
                 CompilationKey::from_type(Type::FALSE, ExtData::FALSE.has_free_verify, dissat_prob),
                 AstElemExt::terminal(Miniscript::FALSE),
             );
-            compile_tern!(&mut left, &mut q_zero_right, &mut zero_comp, [one, zero]);
-            compile_tern!(&mut right, &mut q_zero_left, &mut zero_comp, [one, zero]);
+            compile_tern!(&mut left, &mut q_zero_right, &mut zero_comp, [one, None]);
+            compile_tern!(&mut right, &mut q_zero_left, &mut zero_comp, [one, None]);
         }
         Concrete::Or(ref subs) => {
             let (lw, rw) = PositiveF64::normalized(subs[0].0, subs[1].0);
-            let zero = PositiveF64::new(0.0);
 
             //and-or
             if let (Concrete::And(x), _) = (subs[0].1.as_ref(), subs[1].1.as_ref()) {
@@ -851,7 +862,7 @@ where
                     policy_cache,
                     x[0].as_ref(),
                     lw * sat_prob,
-                    Some(dissat_prob.unwrap_or(zero) + rw * sat_prob),
+                    Some((rw * sat_prob).conditional_add(dissat_prob)),
                 )?;
                 let mut a2 = best_compilations(policy_cache, x[0].as_ref(), lw * sat_prob, None)?;
 
@@ -859,7 +870,7 @@ where
                     policy_cache,
                     x[1].as_ref(),
                     lw * sat_prob,
-                    Some(dissat_prob.unwrap_or(zero) + rw * sat_prob),
+                    Some((rw * sat_prob).conditional_add(dissat_prob)),
                 )?;
                 let mut b2 = best_compilations(policy_cache, x[1].as_ref(), lw * sat_prob, None)?;
 
@@ -870,15 +881,15 @@ where
                     dissat_prob,
                 )?;
 
-                compile_tern!(&mut a1, &mut b2, &mut c, [lw, rw]);
-                compile_tern!(&mut b1, &mut a2, &mut c, [lw, rw]);
+                compile_tern!(&mut a1, &mut b2, &mut c, [lw, Some(rw)]);
+                compile_tern!(&mut b1, &mut a2, &mut c, [lw, Some(rw)]);
             };
             if let (_, Concrete::And(x)) = (&subs[0].1.as_ref(), subs[1].1.as_ref()) {
                 let mut a1 = best_compilations(
                     policy_cache,
                     x[0].as_ref(),
                     rw * sat_prob,
-                    Some(dissat_prob.unwrap_or(zero) + lw * sat_prob),
+                    Some((lw * sat_prob).conditional_add(dissat_prob)),
                 )?;
                 let mut a2 = best_compilations(policy_cache, x[0].as_ref(), rw * sat_prob, None)?;
 
@@ -886,7 +897,7 @@ where
                     policy_cache,
                     x[1].as_ref(),
                     rw * sat_prob,
-                    Some(dissat_prob.unwrap_or(zero) + lw * sat_prob),
+                    Some((lw * sat_prob).conditional_add(dissat_prob)),
                 )?;
                 let mut b2 = best_compilations(policy_cache, x[1].as_ref(), rw * sat_prob, None)?;
 
@@ -897,13 +908,13 @@ where
                     dissat_prob,
                 )?;
 
-                compile_tern!(&mut a1, &mut b2, &mut c, [rw, lw]);
-                compile_tern!(&mut b1, &mut a2, &mut c, [rw, lw]);
+                compile_tern!(&mut a1, &mut b2, &mut c, [rw, Some(lw)]);
+                compile_tern!(&mut b1, &mut a2, &mut c, [rw, Some(lw)]);
             };
 
             let dissat_probs = |w: PositiveF64| -> Vec<Option<PositiveF64>> {
                 vec![
-                    Some(dissat_prob.unwrap_or(zero) + w * sat_prob),
+                    Some((w * sat_prob).conditional_add(dissat_prob)),
                     Some(w * sat_prob),
                     dissat_prob,
                     None,
@@ -953,11 +964,15 @@ where
             let k = thresh.k();
             let n = thresh.n();
 
-            let (sat_ratio, dissat_ratio) = PositiveF64::normalized(
-                PositiveF64::new(k as f64),
-                PositiveF64::new((n - k) as f64),
-            );
-            let zero = PositiveF64::new(0.0);
+            let (sat_ratio, dissat_ratio) = if n > k {
+                let (s, d) = PositiveF64::normalized(
+                    PositiveF64::new(k as f64),
+                    PositiveF64::new((n - k) as f64),
+                );
+                (s, Some(d))
+            } else {
+                (PositiveF64::new(1.0), None)
+            };
 
             let mut sub_ext_data = Vec::with_capacity(n);
 
@@ -968,7 +983,9 @@ where
             for (i, ast) in thresh.iter().enumerate() {
                 let sp = sat_prob * sat_ratio;
                 //Expressions must be dissatisfiable
-                let dp = Some(dissat_prob.unwrap_or(zero) + dissat_ratio * sat_prob);
+                let dp = dissat_ratio
+                    .map(|ratio| (ratio * sat_prob).conditional_add(dissat_prob))
+                    .or(dissat_prob);
                 let be = best(types::Base::B, policy_cache, ast.as_ref(), sp, dp)?;
                 let bw = best(types::Base::W, policy_cache, ast.as_ref(), sp, dp)?;
 
@@ -1111,10 +1128,13 @@ fn compile_tern<Pk: MiniscriptKey, Ctx: ScriptContext>(
     a_comp: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
     b_comp: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
     c_comp: &mut BTreeMap<CompilationKey, AstElemExt<Pk, Ctx>>,
-    weights: [PositiveF64; 2],
+    ab_branch_prob: PositiveF64,
+    c_branch_prob: Option<PositiveF64>,
     sat_prob: PositiveF64,
     dissat_prob: Option<PositiveF64>,
 ) -> Result<(), CompilerError> {
+    let ab_prob = ab_branch_prob.value();
+    let c_prob = c_branch_prob.map_or(0.0, |p| p.value());
     for a in a_comp.values_mut() {
         let aref = Arc::clone(&a.ms);
         for b in b_comp.values_mut() {
@@ -1122,9 +1142,9 @@ fn compile_tern<Pk: MiniscriptKey, Ctx: ScriptContext>(
             for c in c_comp.values_mut() {
                 let cref = Arc::clone(&c.ms);
                 let ast = Terminal::AndOr(Arc::clone(&aref), Arc::clone(&bref), Arc::clone(&cref));
-                a.comp_ext_data.branch_prob = Some(weights[0].value());
-                b.comp_ext_data.branch_prob = Some(weights[0].value());
-                c.comp_ext_data.branch_prob = Some(weights[1].value());
+                a.comp_ext_data.branch_prob = Some(ab_prob);
+                b.comp_ext_data.branch_prob = Some(ab_prob);
+                c.comp_ext_data.branch_prob = Some(c_prob);
                 if let Ok(new_ext) = AstElemExt::ternary(ast, a, b, c) {
                     insert_best_wrapped(policy_cache, policy, ret, new_ext, sat_prob, dissat_prob)?;
                 }
diff --git a/src/policy/concrete.rs b/src/policy/concrete.rs
index 74f7e9a71..39703154a 100644
--- a/src/policy/concrete.rs
+++ b/src/policy/concrete.rs
@@ -568,7 +568,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
         // Stopping condition: When NONE of the inputs can be further enumerated.
         'outer: loop {
             //--- FIND a plausible node ---
-            let mut prob: Reverse<PositiveF64> = Reverse(PositiveF64::new(0.0));
+            let mut prob: Option<Reverse<PositiveF64>> = None;
             let mut curr_policy: Arc<Self> = Arc::new(Self::Unsatisfiable);
             let mut curr_pol_replace_vec: Vec<(f64, Arc<Self>)> = vec![];
             let mut no_more_enum = false;
@@ -583,7 +583,7 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
 
                 if prev_len < enum_len {
                     // Plausible node found
-                    prob = *p;
+                    prob = Some(*p);
                     curr_policy = Arc::clone(pol);
                     break 'inner;
                 } else if i == tapleaf_prob_vec.len() - 1 {
@@ -610,7 +610,8 @@ impl<Pk: MiniscriptKey> Policy<Pk> {
             // with children nodes
 
             // Remove current node
-            assert!(tapleaf_prob_vec.remove(&(prob, curr_policy.clone())));
+            assert!(tapleaf_prob_vec
+                .remove(&(prob.expect("a plausible node was found"), curr_policy.clone())));
             pol_prob_map.remove(&curr_policy);
 
             // OPTIMIZATION - Move marked nodes into final vector
diff --git a/src/primitives/positive_f64.rs b/src/primitives/positive_f64.rs
index 7f8d981ef..46acbacca 100644
--- a/src/primitives/positive_f64.rs
+++ b/src/primitives/positive_f64.rs
@@ -38,6 +38,11 @@ impl PositiveF64 {
         let sum = a.0 + b.0;
         (Self(a.0 / sum), Self(b.0 / sum))
     }
+
+    /// Adds an optional value to `self`, returning `self` unchanged if the value is
+    /// `None`.
+    #[must_use]
+    pub fn conditional_add(self, other: Option<Self>) -> Self { other.map_or(self, |i| self + i) }
 }
 
 impl TryFrom<u32> for PositiveF64 {

From c9d3f8e6179709b7f6a4abc55dae1da887663975 Mon Sep 17 00:00:00 2001
From: Abeeujah <abeeujah@gmail.com>
Date: Sat, 13 Jun 2026 18:41:16 +0100
Subject: [PATCH 7/7] Fix Lint Warning

`cargo +nightly rbmt lint` fails with useless use of `format!`, this
patch fixes the culprit and uses `to_string` over the previously used
`format!` macro.
---
 src/descriptor/mod.rs | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/descriptor/mod.rs b/src/descriptor/mod.rs
index e6e9e0b7f..9b83a227d 100644
--- a/src/descriptor/mod.rs
+++ b/src/descriptor/mod.rs
@@ -1671,7 +1671,7 @@ mod tests {
     #[test]
     fn tr_roundtrip_key() {
         let script = Tr::<String>::from_str("tr()").unwrap().to_string();
-        assert_eq!(script, format!("tr()#x4ml3kxd"))
+        assert_eq!(script, "tr()#x4ml3kxd".to_string())
     }
 
     #[test]