Add Navidrome Scrobbled scrobbler plugin

A Python Extism plugin for Navidrome that scrobbles playback to a
self-hosted Scrobbled (Last.fm-compatible) server, plus Gitea Actions
CI that lints, tests, builds/validates, and publishes the .ndp
artifact to pkgs.daubney.dev.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_018n5ffHCn5QUjpDtuWTk3fh

tests/stubs/extism.py

@@ -0,0 +1,54 @@
+"""Minimal fake `extism` module for testing plugin/__init__.py's pure business
+logic under plain CPython, without the real extism-py/wasm runtime.
+
+Never shipped or compiled - only used by tests/test_logic.py, which puts this
+directory at the front of sys.path before importing the plugin module.
+"""
+
+
+def import_fn(namespace, name):
+    def decorator(fn):
+        return fn
+
+    return decorator
+
+
+def plugin_fn(fn):
+    return fn
+
+
+class LogLevel:
+    Info = "info"
+    Error = "error"
+
+
+def log(level, message):
+    pass
+
+
+class Config:
+    @staticmethod
+    def get_str(key):
+        return None
+
+
+def input_json():
+    return {}
+
+
+def output_str(value):
+    pass
+
+
+class _Memory:
+    def alloc(self, data):
+        raise NotImplementedError("host memory is not available in tests")
+
+    def find(self, offset):
+        raise NotImplementedError("host memory is not available in tests")
+
+    def string(self, mem):
+        raise NotImplementedError("host memory is not available in tests")
+
+
+memory = _Memory()

tests/test_logic.py

@@ -0,0 +1,142 @@
+"""Pure-logic tests for plugin/__init__.py.
+
+These exercise only the business logic that has no dependency on the real
+extism-py/wasm runtime (signing, form-encoding, track-field mapping), so they
+run under plain python3/uv, with no wasm toolchain installed.
+"""
+
+import os
+import sys
+import unittest
+from urllib.parse import parse_qs
+
+REPO_ROOT = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+STUBS_DIR = os.path.join(os.path.dirname(os.path.abspath(__file__)), "stubs")
+
+# The stub `extism` module must be importable before `plugin` is, and take
+# priority over any real `extism` package that happens to be installed.
+sys.path.insert(0, STUBS_DIR)
+sys.path.insert(0, REPO_ROOT)
+
+import plugin  # noqa: E402  (import after sys.path setup, by design)
+
+SCROBBLING_SERVICE_SRC = "/Users/matt/PycharmProjects/ScrobblingService/src"
+try:
+    sys.path.insert(0, SCROBBLING_SERVICE_SRC)
+    from scrobbler.lastfm import signature as scrobbling_service_signature
+except ImportError:
+    scrobbling_service_signature = None
+
+
+class ComputeApiSigTests(unittest.TestCase):
+    def test_matches_known_fixture(self):
+        params = {
+            "method": "auth.getMobileSession",
+            "api_key": "k",
+            "username": "alice",
+            "password": "p",
+            "format": "json",
+        }
+        # Hand-computed per the documented algorithm: sort keys (excluding
+        # format/callback/api_sig), concatenate key+value, append secret, md5-hex.
+        payload = "api_keykmethodauth.getMobileSessionpasswordpusernamealice"
+        expected = plugin._md5_hex((payload + "secret").encode("utf-8"))
+        self.assertEqual(plugin.compute_api_sig(params, "secret"), expected)
+
+    def test_excludes_unsigned_params(self):
+        with_format = {"a": "1", "format": "json"}
+        without_format = {"a": "1"}
+        self.assertEqual(
+            plugin.compute_api_sig(with_format, "secret"),
+            plugin.compute_api_sig(without_format, "secret"),
+        )
+
+    @unittest.skipUnless(
+        scrobbling_service_signature is not None,
+        "ScrobblingService repo not available on this machine",
+    )
+    def test_matches_scrobbling_service_signature(self):
+        params = {
+            "method": "track.scrobble",
+            "api_key": "abc123",
+            "sk": "sesskey",
+            "artist": "Boards of Canada",
+            "track": "Roygbiv",
+            "timestamp": "1700000000",
+            "format": "json",
+        }
+        expected = scrobbling_service_signature.sign(params, "shh")
+        self.assertEqual(plugin.compute_api_sig(params, "shh"), expected)
+
+
+class Md5Tests(unittest.TestCase):
+    def test_known_vectors(self):
+        self.assertEqual(plugin._md5_hex(b""), "d41d8cd98f00b204e9800998ecf8427e")
+        self.assertEqual(plugin._md5_hex(b"abc"), "900150983cd24fb0d6963f7d28e17f72")
+
+    def test_fallback_matches_hashlib(self):
+        data = b"the quick brown fox jumps over the lazy dog, 123456789"
+        self.assertEqual(plugin._md5_fallback_hex(data), plugin._md5_hex(data))
+
+
+class EncodeFormBodyTests(unittest.TestCase):
+    def test_round_trips_special_characters(self):
+        params = {"a": "1 2", "b": "x&y", "c": "h=llo"}
+        body = plugin.encode_form_body(params)
+        parsed = {k: v[0] for k, v in parse_qs(body).items()}
+        self.assertEqual(parsed, params)
+
+    def test_fallback_matches_urllib(self):
+        # Cross-check the hand-rolled fallback encoder against the real stdlib
+        # urlencode, since it must behave identically when it's the one used
+        # (i.e. when the extism-py runtime lacks urllib.parse).
+        from urllib.parse import urlencode as real_urlencode
+
+        params = {"a": "1 2", "b": "x&y=z", "c": "héllo"}
+        self.assertEqual(plugin._fallback_urlencode(params), real_urlencode(params))
+
+
+class BuildTrackParamsTests(unittest.TestCase):
+    def test_required_fields_only(self):
+        track = {"artist": "Artist", "title": "Title"}
+        self.assertEqual(plugin.build_track_params(track), {"artist": "Artist", "track": "Title"})
+
+    def test_optional_fields_included_when_present(self):
+        track = {
+            "artist": "Artist",
+            "title": "Title",
+            "album": "Album",
+            "albumArtist": "Album Artist",
+            "duration": 123.6,
+            "trackNumber": 4,
+            "mbzRecordingId": "mbid-123",
+        }
+        params = plugin.build_track_params(track)
+        self.assertEqual(
+            params,
+            {
+                "artist": "Artist",
+                "track": "Title",
+                "album": "Album",
+                "albumArtist": "Album Artist",
+                "duration": "124",
+                "trackNumber": "4",
+                "mbid": "mbid-123",
+            },
+        )
+
+    def test_falsy_optional_fields_omitted(self):
+        track = {
+            "artist": "Artist",
+            "title": "Title",
+            "album": "",
+            "albumArtist": None,
+            "duration": 0,
+            "trackNumber": 0,
+            "mbzRecordingId": "",
+        }
+        self.assertEqual(plugin.build_track_params(track), {"artist": "Artist", "track": "Title"})
+
+
+if __name__ == "__main__":
+    unittest.main()