diff --git a/core/traxsource.py b/core/traxsource.py
index 85d213b..d0372b4 100644
--- a/core/traxsource.py
+++ b/core/traxsource.py
@@ -6,6 +6,7 @@ Spec: docs/superpowers/specs/2026-08-01-traxsource-charts-design.md.
 
 from __future__ import annotations
 
+import re
 from dataclasses import dataclass
 
 
@@ -59,3 +60,47 @@ def list_genres() -> list:
     ]
     result.sort(key=lambda g: g["name"].casefold())
     return result
+
+
+class TraxsourceError(Exception):
+    """Base per errori Traxsource."""
+
+
+class TraxsourceUnreachableError(TraxsourceError):
+    """Rete / 5xx dopo retry."""
+
+
+class TraxsourceParseError(TraxsourceError):
+    """HTML ricevuto ma non conforme allo schema atteso."""
+
+
+_MIX_PAREN_RE = re.compile(r"^(.*)\s*\(([^()]+)\)\s*$")
+_SIZE_RE = re.compile(r"/\d+x\d+/")
+
+
+def _split_title_mix(full_title: str) -> tuple:
+    """Estrae mix dalle parentesi finali. 'Foo (Extended Mix)' -> ('Foo', 'Extended Mix').
+    Se non ci sono parentesi finali, mix = ''."""
+    if not full_title:
+        return ("", "")
+    m = _MIX_PAREN_RE.match(full_title.strip())
+    if m:
+        return (m.group(1).strip(), m.group(2).strip())
+    return (full_title.strip(), "")
+
+
+def _format_artists(names: list) -> str:
+    """['A', 'B', 'C'] -> 'A, B & C'. Strips whitespace."""
+    clean = [n.strip() for n in names if n and n.strip()]
+    if not clean:
+        return ""
+    if len(clean) == 1:
+        return clean[0]
+    return ", ".join(clean[:-1]) + " & " + clean[-1]
+
+
+def _large_cover(url: str) -> str:
+    """Sostituisce /NxN/ nel path con /500x500/. Se pattern assente, ritorna invariato."""
+    if not url:
+        return ""
+    return _SIZE_RE.sub("/500x500/", url)
diff --git a/tests/test_traxsource.py b/tests/test_traxsource.py
index c1eb3da..b1c322f 100644
--- a/tests/test_traxsource.py
+++ b/tests/test_traxsource.py
@@ -45,3 +45,53 @@ class TestTraxsourceTrack:
         )
         assert t.image_url == ""
         assert t.cover_url_large == ""
+
+
+class TestSplitTitleMix:
+    def test_with_parens(self):
+        assert traxsource._split_title_mix("Foo (Extended Mix)") == ("Foo", "Extended Mix")
+
+    def test_without_parens(self):
+        assert traxsource._split_title_mix("Foo") == ("Foo", "")
+
+    def test_multiple_parens_takes_last(self):
+        # es. "Foo (feat. Bar) (Original Mix)" -> mix = "Original Mix"
+        assert traxsource._split_title_mix("Foo (feat. Bar) (Original Mix)") == ("Foo (feat. Bar)", "Original Mix")
+
+    def test_empty(self):
+        assert traxsource._split_title_mix("") == ("", "")
+
+
+class TestFormatArtists:
+    def test_single(self):
+        assert traxsource._format_artists(["Kapuchon"]) == "Kapuchon"
+
+    def test_two(self):
+        assert traxsource._format_artists(["A", "B"]) == "A & B"
+
+    def test_three(self):
+        assert traxsource._format_artists(["A", "B", "C"]) == "A, B & C"
+
+    def test_empty(self):
+        assert traxsource._format_artists([]) == ""
+
+    def test_strips_whitespace(self):
+        assert traxsource._format_artists(["  A  ", " B "]) == "A & B"
+
+
+class TestLargeCover:
+    def test_substitutes_52x52_with_500x500(self):
+        url = "https://www.traxsource.com/scripts/image.php/52x52/abc.jpg"
+        assert traxsource._large_cover(url) == "https://www.traxsource.com/scripts/image.php/500x500/abc.jpg"
+
+    def test_no_change_when_no_pattern(self):
+        assert traxsource._large_cover("https://example.com/x.jpg") == "https://example.com/x.jpg"
+
+    def test_empty(self):
+        assert traxsource._large_cover("") == ""
+
+
+class TestExceptions:
+    def test_exceptions_are_subclasses(self):
+        assert issubclass(traxsource.TraxsourceUnreachableError, traxsource.TraxsourceError)
+        assert issubclass(traxsource.TraxsourceParseError, traxsource.TraxsourceError)