fix(store): read the core version from disk, not from a stale import (#518)

* fix(store): read the core version from disk, not from a stale import

Updating the core to 3.3.0 and then updating plugins refused all eight sports
scoreboards:

    Refusing to install nrl-scoreboard: NRL Scoreboard supports LEDMatrix
    >=3.3.0, but this system is running 3.2.0.

while src/__init__.py on that machine read 3.3.0. Observed on hardware, not
theorised.

The gate ran `from src import __version__ as core_version`, which binds
whatever the process loaded at start. The plugin store's gate lives in the web
UI, a long-lived service of its own, and the update route deliberately restarts
nothing -- it replaces files on disk and asks the user to restart. Its prompt
named only the *display* service, so a user who followed it left the web
process holding the previous number.

Stale by exactly one release is the case that bites: every plugin flooring on
the release you just installed is refused, blaming a core version that is
already correct on disk. It reads as a broken plugin store. 3.3.0 is the first
release where this hits a whole family at once, since all eight scoreboards
floor there.

compatibility.current_core_version() reads the version from the file instead,
falling back to the imported value on any failure -- so it can only ever be as
correct as before, never worse. All four gate call sites use it: three in
store_manager (install, the git-pull update path, install_from_url) and one in
plugin_loader's advisory warning.

The restart prompt now names both services.

Twelve tests, including the hardware failure itself: a process holding 3.2.0
while disk says 3.3.0 refuses hockey, and reading fresh allows it. The inverse
is asserted too -- a genuinely old core still refuses, so the gate has not
become permissive. One test greps both modules for the old import-bound read;
reintroducing that line fails it, which is what stops this coming back.

Not changed: web_interface/__init__.py also imports __version__, but for
display rather than gating, and the API endpoint already reports a fresh
git describe.

* fix: drop the unused os import

Left over from a first draft that joined paths by hand before this used
pathlib. Flagged by CodeRabbit on #518; confirmed dead -- no os. reference
remains in the module.

src/plugin_system/compatibility.py

@@ -28,6 +28,7 @@ fixes their version string. See `docs/SPORTS_UNIFICATION.md`, phase B4.
 from __future__ import annotations
 
 import re
+from pathlib import Path
 from typing import Any, Dict, Optional, Tuple
 
 # Below this, the core's self-reported version is not evidence of anything.
@@ -35,6 +36,45 @@ from typing import Any, Dict, Optional, Tuple
 TRUSTWORTHY_FLOOR: Tuple[int, int, int] = (2, 0, 0)
 
 
+# ``src/__init__.py`` relative to this file: src/plugin_system/ -> src/
+_VERSION_FILE = Path(__file__).resolve().parent.parent / "__init__.py"
+_VERSION_RE = re.compile(r'^__version__\s*=\s*["\']([^"\']+)["\']', re.M)
+
+
+def current_core_version() -> str:
+    """The core version as it is on disk right now, not as it was at import.
+
+    ``from src import __version__`` binds whatever the process loaded at start.
+    The web UI runs as its own long-lived service (``ledmatrix-web.service``),
+    and updating the core replaces files on disk without restarting it -- the
+    update route says so explicitly and asks the user to restart. Its prompt
+    names the *display* service, so a user who follows it leaves the web
+    process holding the old number.
+
+    The plugin store's gate lives in that web process. Stale by one release is
+    exactly the case that matters: every plugin flooring on the release you
+    just installed gets refused, with a message blaming a core version that is
+    already correct on disk. 3.3.0 is the first release where that hits a whole
+    plugin family at once -- all eight sports scoreboards floor there.
+
+    Reading the file costs one stat and a small read per call, and only on the
+    install/update path. Any failure falls back to the imported value, so this
+    can only ever be as wrong as before, never worse.
+    """
+    try:
+        text = _VERSION_FILE.read_text(encoding="utf-8")
+        match = _VERSION_RE.search(text)
+        if match:
+            return match.group(1)
+    except (OSError, UnicodeDecodeError):
+        pass
+    try:
+        from src import __version__ as imported
+        return imported
+    except Exception:            # noqa: BLE001 - never let this raise
+        return "0.0.0"
+
+
 def parse_semver(value: Any) -> Optional[Tuple[int, int, int]]:
     """Parse ``X.Y.Z`` (extra parts and suffixes ignored) into a comparable
     3-tuple, or ``None`` when unparseable. A leading ``v`` is tolerated."""

src/plugin_system/plugin_loader.py

@@ -772,8 +772,8 @@ class PluginLoader:
         newer than the running core. Advisory only — never raises — so a
         plugin that guards optional features with try/except keeps working.
         """
-        from src import __version__ as core_version
         from src.plugin_system import compatibility
+        core_version = compatibility.current_core_version()
 
         compatible, _reason = compatibility.check(manifest, core_version)
         if compatible:

src/plugin_system/store_manager.py

@@ -1467,8 +1467,11 @@ class PluginStoreManager:
                 # already had. Allowing it costs them a plugin that raises
                 # ModuleNotFoundError at load and is reported only as one line
                 # in the journal. See docs/SPORTS_UNIFICATION.md (phase B4/B6).
-                from src import __version__ as core_version
                 from src.plugin_system import compatibility
+                # On disk, not as imported: this process may predate the core
+                # update that made the plugin compatible. See
+                # compatibility.current_core_version.
+                core_version = compatibility.current_core_version()
 
                 compatible, reason = compatibility.check(manifest, core_version)
                 if not compatible:
@@ -1612,8 +1615,8 @@ class PluginStoreManager:
             #
             # Before the move, so the `finally` below removes the temp tree and
             # nothing half-installed is left behind.
-            from src import __version__ as core_version
             from src.plugin_system import compatibility
+            core_version = compatibility.current_core_version()
 
             compatible, reason = compatibility.check(manifest, core_version)
             if not compatible:
@@ -2644,8 +2647,8 @@ class PluginStoreManager:
                 manifest_path, plugin_id, e)
             return True
 
-        from src import __version__ as core_version
         from src.plugin_system import compatibility
+        core_version = compatibility.current_core_version()
 
         compatible, reason = compatibility.check(manifest, core_version)
         if compatible:

test/test_core_version_freshness.py

@@ -0,0 +1,122 @@
+"""The gate must read the core version from disk, not from its own import.
+
+`from src import __version__` binds whatever the process loaded at start. The
+web UI is a long-lived service of its own (ledmatrix-web.service), and updating
+the core replaces files on disk without restarting it -- the update route says
+so and asks the user to restart, but its prompt named only the *display*
+service, so a user who followed it left the web process holding the old number.
+
+The plugin store's gate lives in that web process, so being stale by exactly
+one release is the case that bites: every plugin flooring on the release you
+just installed is refused, with a message blaming a core version that is
+already correct on disk.
+
+Observed on hardware: after updating a rig to 3.3.0 and restarting only the
+display service, all eight sports scoreboards were refused with
+"supports LEDMatrix >=3.3.0, but this system is running 3.2.0" while
+src/__init__.py on that machine read 3.3.0.
+"""
+
+import importlib
+import sys
+
+import pytest
+
+from src.plugin_system import compatibility
+
+
+class TestCurrentCoreVersion:
+    def test_it_reads_the_file_rather_than_the_imported_value(self, monkeypatch, tmp_path):
+        # Simulate a process whose import predates the update: the module
+        # object says 3.2.0 while the file on disk says 3.3.0.
+        import src
+        monkeypatch.setattr(src, "__version__", "3.2.0")
+        fake = tmp_path / "__init__.py"
+        fake.write_text('__version__ = "3.3.0"\n', encoding="utf-8")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", fake)
+        assert compatibility.current_core_version() == "3.3.0"
+
+    def test_it_matches_the_real_file_by_default(self):
+        import src
+        assert compatibility.current_core_version() == src.__version__
+
+    @pytest.mark.parametrize("body", [
+        "__version__ = '3.4.1'\n",
+        '__version__="3.4.1"\n',
+        '"""doc"""\n\n__version__ = "3.4.1"  # trailing comment\n',
+    ])
+    def test_it_tolerates_the_ways_that_line_gets_written(self, monkeypatch, tmp_path, body):
+        fake = tmp_path / "__init__.py"
+        fake.write_text(body, encoding="utf-8")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", fake)
+        assert compatibility.current_core_version() == "3.4.1"
+
+    def test_a_missing_file_falls_back_to_the_import(self, monkeypatch, tmp_path):
+        # Never worse than before: an unreadable file returns what the old
+        # code would have returned.
+        import src
+        monkeypatch.setattr(src, "__version__", "3.2.0")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", tmp_path / "gone.py")
+        assert compatibility.current_core_version() == "3.2.0"
+
+    def test_a_file_without_the_line_falls_back(self, monkeypatch, tmp_path):
+        import src
+        monkeypatch.setattr(src, "__version__", "3.2.0")
+        fake = tmp_path / "__init__.py"
+        fake.write_text("# no version here\n", encoding="utf-8")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", fake)
+        assert compatibility.current_core_version() == "3.2.0"
+
+    def test_it_never_raises(self, monkeypatch, tmp_path):
+        # This runs on the install path; an exception here would surface as a
+        # failed update rather than a version mismatch.
+        bad = tmp_path / "__init__.py"
+        bad.write_bytes(b"\xff\xfe\x00 not utf-8 \xff")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", bad)
+        assert isinstance(compatibility.current_core_version(), str)
+
+
+class TestTheBugItFixes:
+    def test_a_stale_import_no_longer_refuses_a_compatible_plugin(self, monkeypatch, tmp_path):
+        """The exact hardware failure, as a test."""
+        import src
+        monkeypatch.setattr(src, "__version__", "3.2.0")     # what the process holds
+        fake = tmp_path / "__init__.py"
+        fake.write_text('__version__ = "3.3.0"\n', encoding="utf-8")   # what is on disk
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", fake)
+
+        manifest = {"name": "Hockey Scoreboard", "min_ledmatrix_version": "3.3.0"}
+
+        stale_ok, _ = compatibility.check(manifest, src.__version__)
+        assert stale_ok is False, "precondition: the stale value is what refused it"
+
+        fresh_ok, reason = compatibility.check(
+            manifest, compatibility.current_core_version())
+        assert fresh_ok is True, f"the disk version must allow it, got: {reason}"
+
+    def test_it_still_refuses_when_the_core_really_is_too_old(self, monkeypatch, tmp_path):
+        # The gate must not become permissive: a genuinely old core still says no.
+        fake = tmp_path / "__init__.py"
+        fake.write_text('__version__ = "3.2.0"\n', encoding="utf-8")
+        monkeypatch.setattr(compatibility, "_VERSION_FILE", fake)
+        ok, reason = compatibility.check(
+            {"name": "Hockey", "min_ledmatrix_version": "3.3.0"},
+            compatibility.current_core_version())
+        assert ok is False
+        assert "3.2.0" in (reason or "")
+
+
+class TestCallSites:
+    @pytest.mark.parametrize("module", [
+        "src.plugin_system.store_manager",
+        "src.plugin_system.plugin_loader",
+    ])
+    def test_no_gate_binds_the_version_at_import(self, module):
+        """Catch a future call site reintroducing the stale read."""
+        import inspect
+        mod = importlib.import_module(module)
+        source = inspect.getsource(mod)
+        assert "from src import __version__ as core_version" not in source, (
+            f"{module} binds __version__ at import; use "
+            f"compatibility.current_core_version() so a long-lived process "
+            f"sees a core update.")

web_interface/templates/v3/base.html

@@ -1164,9 +1164,16 @@
                 // The pull replaced files on disk; the running services still
                 // hold the code they loaded at boot. Ask for the restart that
                 // makes the update actually take effect.
+                //
+                // Both services, not just the display. The plugin store's
+                // compatibility gate runs in the web process, so a web service
+                // still holding the previous version refuses every plugin that
+                // floors on the release just installed -- blaming a core
+                // version that is already correct on disk.
                 if (data.restart_required && typeof window.showRestartPending === 'function') {
                     window.showRestartPending(
-                        'Update installed \u2014 restart the display to run the new code');
+                        'Update installed \u2014 restart the display and web ' +
+                        'services to run the new code');
                 }
             }
             if (typeof showNotification === 'function') {