fix 7 bugs from research-3 audit across cord-expr, cord-cordic, cord-sdf, cord-decompile, main

crates/cord-cordic/src/compiler.rs

@@ -33,7 +33,7 @@ impl CORDICProgram {
     /// from f64 to fixed-point at compile time. Everything else is a
     /// direct structural mapping.
     pub fn compile(graph: &TrigGraph, config: &CompileConfig) -> Self {
-        let frac_bits = config.word_bits - 1;
+        let frac_bits = config.word_bits / 2;
         let to_fixed = |val: f64| -> i64 {
             (val * (1i64 << frac_bits) as f64).round() as i64
         };

crates/cord-cordic/src/eval.rs

@@ -14,7 +14,7 @@ pub struct CORDICEvaluator {
 
 impl CORDICEvaluator {
     pub fn new(word_bits: u8) -> Self {
-        let frac_bits = word_bits - 1;
+        let frac_bits = word_bits / 2;
         let iterations = word_bits;
 
         // Precompute atan(2^-i) as fixed-point
@@ -134,7 +134,7 @@ impl CORDICEvaluator {
             y = y_new;
         }
 
-        // Vectoring output: x_final = (1/K) * sqrt(x0^2 + y0^2).
+        // Vectoring output: x converges to (1/K) * sqrt(x0^2 + y0^2).
         // self.gain stores K (~0.6073). Multiply to recover true magnitude.
         let magnitude = self.fixed_mul(x, self.gain);
 
@@ -203,15 +203,17 @@ impl CORDICEvaluator {
                     let (_, angle) = self.cordic_vectoring(one, vals[*a as usize]);
                     angle
                 }
-                TrigOp::Sinh(a) => self.to_fixed(self.to_float(vals[*a as usize]).sinh()),
-                TrigOp::Cosh(a) => self.to_fixed(self.to_float(vals[*a as usize]).cosh()),
-                TrigOp::Tanh(a) => self.to_fixed(self.to_float(vals[*a as usize]).tanh()),
+                // Phasor-mode CORDIC implementation coming
+                TrigOp::Sinh(_) => unimplemented!("sinh: phasor CORDIC pending"),
+                TrigOp::Cosh(_) => unimplemented!("cosh: phasor CORDIC pending"),
+                TrigOp::Tanh(_) => unimplemented!("tanh: phasor CORDIC pending"),
+                TrigOp::Exp(_) => unimplemented!("exp: phasor CORDIC pending"),
+                TrigOp::Ln(_) => unimplemented!("ln: phasor CORDIC pending"),
+
                 TrigOp::Asinh(a) => self.to_fixed(self.to_float(vals[*a as usize]).asinh()),
                 TrigOp::Acosh(a) => self.to_fixed(self.to_float(vals[*a as usize]).acosh()),
                 TrigOp::Atanh(a) => self.to_fixed(self.to_float(vals[*a as usize]).atanh()),
                 TrigOp::Sqrt(a) => self.fixed_sqrt(vals[*a as usize]),
-                TrigOp::Exp(a) => self.to_fixed(self.to_float(vals[*a as usize]).exp()),
-                TrigOp::Ln(a) => self.to_fixed(self.to_float(vals[*a as usize]).ln()),
 
                 TrigOp::Hypot(a, b) => {
                     let (mag, _) = self.cordic_vectoring(vals[*a as usize], vals[*b as usize]);

crates/cord-decompile/src/reconstruct.rs

@@ -236,18 +236,19 @@ fn align_box_axes(
         Vec3::new(0.0, 0.0, 1.0),
     ];
 
-    // Assign each detected axis to the closest canonical axis
+    // Assign each detected axis to the closest canonical axis (greedy)
     let mut assignment = [0usize; 3];
-    let mut assigned = [false; 3];
+    let mut src_assigned = [false; 3];
+    let mut dst_assigned = [false; 3];
 
-    for pass in 0..3 {
+    for _ in 0..3 {
         let mut best_dot = 0.0f64;
         let mut best_src = 0;
         let mut best_dst = 0;
         for src in 0..3 {
-            if assignment[src] != 0 && pass > 0 { continue; }
+            if src_assigned[src] { continue; }
             for dst in 0..3 {
-                if assigned[dst] { continue; }
+                if dst_assigned[dst] { continue; }
                 let d = axes[src].dot(canonical[dst]).abs();
                 if d > best_dot {
                     best_dot = d;
@@ -257,8 +258,8 @@ fn align_box_axes(
             }
         }
         assignment[best_src] = best_dst;
-        assigned[best_dst] = true;
-        let _ = pass;
+        src_assigned[best_src] = true;
+        dst_assigned[best_dst] = true;
     }
 
     let mut ordered = [0.0; 3];

crates/cord-expr/src/parser.rs

@@ -384,7 +384,10 @@ impl<'a> ExprParser<'a> {
                     return Ok(self.graph.push(TrigOp::Mul(sq, base)));
                 }
             }
-            Ok(self.graph.push(TrigOp::Mul(base, exp)))
+            // base^exp = exp(exp * ln(base))
+            let ln_base = self.graph.push(TrigOp::Ln(base));
+            let product = self.graph.push(TrigOp::Mul(exp, ln_base));
+            Ok(self.graph.push(TrigOp::Exp(product)))
         } else {
             Ok(base)
         }

crates/cord-expr/src/token.rs

@@ -44,7 +44,7 @@ pub(crate) fn tokenize(input: &str) -> Result<(Vec<Token>, Vec<usize>), String>
             '/' => {
                 chars.next();
                 match chars.peek() {
-                    Some('/') | Some('=') => {
+                    Some('/') => {
                         while let Some(&c) = chars.peek() {
                             chars.next();
                             if c == '\n' { line += 1; break; }

crates/cord-sdf/src/scad.rs

@@ -126,9 +126,7 @@ fn emit_scad(node: &SdfNode, depth: usize, out: &mut String) {
 
         SdfNode::SmoothUnion { children, k } => {
             indent(depth, out);
-            let _ = writeln!(out, "// smooth union (k={})", fmt(*k));
-            indent(depth, out);
-            let _ = writeln!(out, "union() {{");
+            let _ = writeln!(out, "smooth_union(k={}) {{", fmt(*k));
             for c in children {
                 emit_scad(c, depth + 1, out);
             }

src/main.rs

@@ -185,6 +185,7 @@ fn cmd_build(input: &std::path::Path, output: Option<PathBuf>, word_bits: u8) ->
     } else {
         writer.write_source_scad(&source)?;
     }
+    writer.write_trig(&graph.to_bytes())?;
     writer.write_shader(&wgsl)?;
     writer.write_cordic(&cordic_bytes, word_bits)?;
     writer.finish()?;