youknowone · Nov 2, 2026 · Nov 2, 2026 · Nov 2, 2026 · Nov 2, 2026
diff --git a/crates/vm/src/builtins/type.rs b/crates/vm/src/builtins/type.rs
@@ -2472,7 +2472,12 @@ impl Constructor for PyType {
 
 const SIGNATURE_END_MARKER: &str = ")\n--\n\n";
 fn get_signature(doc: &str) -> Option<&str> {
-    doc.find(SIGNATURE_END_MARKER).map(|index| &doc[..=index])
+    let index = doc.find(SIGNATURE_END_MARKER)?;
+    // Like CPython's skip_signature, a blank paragraph ends the header search.
+    if doc[..index].contains("\n\n") {
+        return None;
+    }
+    Some(&doc[..=index])
 }
 
 fn find_signature<'a>(name: &str, doc: &'a str) -> Option<&'a str> {
@@ -2491,13 +2496,12 @@ pub(crate) fn get_text_signature_from_internal_doc<'a>(
 // _PyType_DocWithoutSignature in CPython
 fn doc_without_signature<'a>(name: &str, internal_doc: &'a str) -> &'a str {
     // If the doc starts with the type name and a '(', it's a signature
-    if let Some(doc_without_sig) = find_signature(name, internal_doc) {
-        // Find where the signature ends
-        if let Some(sig_end_pos) = doc_without_sig.find(SIGNATURE_END_MARKER) {
-            let after_sig = &doc_without_sig[sig_end_pos + SIGNATURE_END_MARKER.len()..];
-            // Return the documentation after the signature, or empty string if none
-            return after_sig;
-        }
+    if let Some(doc_without_sig) = find_signature(name, internal_doc)
+        && let Some(signature) = get_signature(doc_without_sig)
+    {
+        let after_sig = &doc_without_sig[signature.len() + SIGNATURE_END_MARKER.len() - 1..];
+        // Return the documentation after the signature, or empty string if none
+        return after_sig;
     }
     // If no signature found, return the whole doc
     internal_doc
@@ -2509,6 +2513,36 @@ pub(crate) fn get_doc_from_internal_doc<'a>(name: &str, internal_doc: &'a str) -
     (!doc.is_empty()).then_some(doc)
 }
 
+#[cfg(test)]
+mod internal_doc_signature_tests {
+    use super::{get_doc_from_internal_doc, get_text_signature_from_internal_doc};
+
+    #[test]
+    fn signatures_stop_before_a_blank_paragraph() {
+        for doc in [
+            "f(x\n\ncontinued)\n--\n\nDocumentation.",
+            "f(x)\n\nExample: f(y)\n--\n\nDocumentation.",
+        ] {
+            assert_eq!(get_text_signature_from_internal_doc("f", doc), None);
+            assert_eq!(get_doc_from_internal_doc("f", doc), Some(doc));
+        }
+    }
+
+    #[test]
+    fn multiline_signature_and_documentation_keep_their_boundary() {
+        let doc = "f($module, x,\n  y=None, /)\n--\n\nFirst.\n\nSecond.";
+        assert_eq!(
+            get_text_signature_from_internal_doc("mod.f", doc),
+            Some("($module, x,\n  y=None, /)")
+        );
+        assert_eq!(
+            get_doc_from_internal_doc("mod.f", doc),
+            Some("First.\n\nSecond.")
+        );
+        assert_eq!(get_doc_from_internal_doc("f", "f()\n--\n\n"), None);
+    }
+}
+
 pub(crate) fn rendered_item_doc(name: &str, doc: ItemDoc) -> Option<&'static str> {
     if doc.len != 0 {
         return db_doc(doc.offset, doc.len);

diff --git a/crates/vm/src/function/signature.rs b/crates/vm/src/function/signature.rs
@@ -503,16 +503,12 @@ const fn put_exp(buf: &mut [u8], i: usize, exp: i32) -> usize {
         (put_byte(buf, i, b'+'), exp)
     };
     let exp = exp as u32;
-    if exp >= 10 {
-        let i = put_byte(buf, i, b'0' + (exp / 10) as u8);
-        put_byte(buf, i, b'0' + (exp % 10) as u8)
-    } else {
-        let i = put_byte(buf, i, b'0');
-        put_byte(buf, i, b'0' + exp as u8)
-    }
+    let i = if exp < 10 { put_byte(buf, i, b'0') } else { i };
+    put_u128(buf, i, exp as u128)
 }
 
-/// Shortest round-trip decimal, matching `float.__repr__` for finite values.
+/// Decimal rendering using up to 17 significant digits.
+// This normalization-based formatter is not a shortest-round-trip algorithm.
 const fn put_f64(buf: &mut [u8], i: usize, v: f64) -> usize {
     if v.is_nan() {
         return put_str(buf, i, "nan");
@@ -706,7 +702,7 @@ const fn write_args(buf: &mut [u8], mut st: St, args: &[SigArg]) -> St {
 
 #[cfg(test)]
 mod tests {
-    use super::{DefaultRepr, Param, ParamKind, SigArg, St, native_call_flags, write_one};
+    use super::{DefaultRepr, Param, ParamKind, SigArg, St, native_call_flags, put_exp, write_one};
     use crate::function::PyMethodFlags;
 
     fn rendered(default: DefaultRepr) -> String {
@@ -732,6 +728,25 @@ mod tests {
         text.split_once('=').unwrap().1.to_owned()
     }
 
+    #[test]
+    fn exponent_text_keeps_all_digits() {
+        for (exp, expected) in [
+            (0, "e+00"),
+            (9, "e+09"),
+            (-9, "e-09"),
+            (10, "e+10"),
+            (-99, "e-99"),
+            (100, "e+100"),
+            (308, "e+308"),
+            (-324, "e-324"),
+        ] {
+            let mut buf = [0u8; 16];
+            let len = put_exp(&mut buf, 0, exp);
+            assert_eq!(core::str::from_utf8(&buf[..len]).unwrap(), expected);
+            assert_eq!(put_exp(&mut [], 0, exp), len);
+        }
+    }
+
     #[test]
     fn default_repr_text() {
         assert_eq!(rendered(DefaultRepr::None), "None");