feat(store): refuse to install a plugin that needs a newer core (#429)

* feat(store): refuse to install a plugin that needs a newer core

`ledmatrix_min_version` was decoration. The loader logged an advisory warning
and continued; the store never compared the core version at all, so a routine
"update" delivered a plugin that could not run. That is the gap phase B6 (the
sports-unification sunset) cannot be done over: deleting a plugin's bundled
fallback while nothing enforces the floor hands un-updated users a scoreboard
that raises ModuleNotFoundError at load and is reported only as one line in
the journal.

The gate lives in install_plugin, after the manifest is on disk and before
dependencies are installed. That is the earliest knowable point -- the
registry carries no compatibility field, so the floor is not visible until
the files are down -- and it is also the chokepoint: _reinstall_with_rollback
calls install_plugin, so a refused *update* restores the version the user
already had, for free.

Floor resolution and the comparison move to src/plugin_system/compatibility.py,
shared with the loader so the two cannot drift. Both read all four spellings
published manifests use, including the deprecated `ledmatrix_min`.

Refusal requires evidence. An undeclared floor, an unparseable version on
either side, or a core below TRUSTWORTHY_FLOOR (2.0.0) all allow the install.
That last one is deliberate and load-bearing: the v3.1.0 release reports
__version__ = "1.0.0" while nearly every published manifest floors at 2.0.0,
so a strict gate would lock those users out of the plugin store entirely --
much worse than the problem being solved. They stay unprotected until they
update the core, which is also what fixes their version string.

Verified: 782 core unit tests pass, including 25 new ones and the existing
loader-warning suite unchanged (the refactor is behavior-preserving). The
install tests drive the real install_plugin path with the download stubbed --
the allow and refuse cases differ only in the declared floor, so the refusal
is demonstrably the gate and not an earlier bail-out.

Follow-ups, deliberately not in this PR: surfacing the reason in the store UI
rather than only the log, and publishing the floor in plugins.json so the
store can refuse before downloading.

Phase B4 in docs/SPORTS_UNIFICATION.md.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Udr6MfaFLUPhX5Fgo67Jf5

* fix(store): a failed install must not destroy the plugin it replaced

Found while validating the compatibility gate. `_install_plugin_impl` deletes
the existing plugin directory *before* downloading, so any failure after that
point leaves the user with nothing. `_reinstall_with_rollback` protects the
update path exactly this way; a direct `install_plugin` had no equivalent.

The gate made this reachable in a new way: a plugin whose declared floor
exceeds the running core is now refused *after* the old copy is already gone.
Floors are hand-written and can be over-declared, so the refusal could remove
a plugin that had been working fine on that core.

install_plugin is now a thin wrapper that renames any existing install aside,
delegates to _install_plugin_impl, and restores it on failure -- including
when the implementation raises, which is re-raised after the restore. It is a
pass-through when nothing is installed and when called from
_reinstall_with_rollback, which has already moved the old copy aside; a test
pins that so the two mechanisms cannot start nesting.

The aside name embeds '.standalone-backup-' because
plugin_manager._scan_directory_for_plugins keys on exactly that substring to
skip backups. A different name would have made the backup discoverable as a
duplicate plugin; a test pins that too.

789 core unit tests pass, including 7 new ones.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Udr6MfaFLUPhX5Fgo67Jf5

* fix(store): serialize concurrent installs, and make the lock reentrant

Second bug found while validating the previous commit on hardware.

install_plugin's new set-aside/restore had no lock. The web UI runs Flask
threaded, so a double-clicked Install button gives two threads the same
plugin_id; interleaved, one thread's restore deletes the other's freshly
installed copy. _reinstall_with_rollback already guards exactly this with a
per-plugin lock, and install_plugin needs the same one.

Taking that lock naively deadlocks. _reinstall_with_rollback holds it across
its call to install_plugin, and threading.Lock is not reentrant -- so the
request thread hangs forever on the standard monorepo update path
(update_plugin -> _reinstall_with_rollback -> install_plugin), which is to say
on every plugin update. Verified by reverting to a plain Lock: the regression
test times out after 10s instead of passing.

The per-plugin locks are now RLocks, and install_plugin holds one for its
whole set-aside/install/restore sequence.

Verified on devpi (Pi, Python 3.13.5, real registry and network):
- update_plugin on an up-to-date plugin: True in 5.4s
- update_plugin forced through the full reinstall-with-rollback path:
  True in 13.1s, correct version restored, old copy replaced, no backup
  directories left behind
- install -> reinstall-over-existing -> failed-reinstall-restores: all pass
  against real downloads
- 22 plugins load, no tracebacks, web API and UI 200, steady-state journal
  50 lines/min

791 core unit tests pass, including 2 new concurrency tests.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Udr6MfaFLUPhX5Fgo67Jf5

---------

Co-authored-by: Claude Opus 5 (1M context) <noreply@anthropic.com>

test/test_plugin_compatibility_gate.py

@@ -0,0 +1,232 @@
+"""The install/update gate, and the shared compatibility rules behind it.
+
+Before this existed, `ledmatrix_min_version` was decoration: the loader logged
+an advisory warning and the store never looked at the core version at all, so a
+routine store update happily delivered a plugin that could not run. Deleting a
+plugin's bundled fallback under those conditions would have handed un-updated
+users a scoreboard that fails to load with one line in the journal.
+
+The rules being pinned here, in priority order:
+
+1. Refuse only on **evidence**. Undeclared floor, unparseable version on either
+   side, or a core whose self-reported version is untrustworthy → allow. A
+   wrong refusal breaks a working install; a wrong allowance degrades to the
+   behavior we already had.
+2. A core below `TRUSTWORTHY_FLOOR` is *unknown*, not old. The v3.1.0 release
+   reports `1.0.0` while nearly every manifest floors at `2.0.0`; blocking on
+   that number would stop those users installing anything at all.
+3. The loader and the store must agree, because they read the same manifests.
+"""
+
+import json
+from pathlib import Path
+from unittest.mock import MagicMock
+
+import pytest
+
+from src.plugin_system import compatibility
+
+
+# --------------------------------------------------------------------------
+# Floor resolution — every spelling published plugins actually use
+# --------------------------------------------------------------------------
+
+class TestDeclaredMinVersion:
+    def test_top_level_min_ledmatrix_version(self):
+        assert compatibility.declared_min_version(
+            {"min_ledmatrix_version": "3.2.0"}) == "3.2.0"
+
+    def test_requires_block(self):
+        assert compatibility.declared_min_version(
+            {"requires": {"min_ledmatrix_version": "3.1.0"}}) == "3.1.0"
+
+    def test_versions_array_new_spelling(self):
+        assert compatibility.declared_min_version(
+            {"versions": [{"ledmatrix_min_version": "3.2.0"}]}) == "3.2.0"
+
+    def test_versions_array_deprecated_spelling(self):
+        """Most published manifests still say `ledmatrix_min`; ignoring it
+        would silently exempt them from the gate."""
+        assert compatibility.declared_min_version(
+            {"versions": [{"ledmatrix_min": "2.0.0"}]}) == "2.0.0"
+
+    def test_absent(self):
+        assert compatibility.declared_min_version({"id": "x"}) is None
+
+    def test_requires_present_but_null(self):
+        assert compatibility.declared_min_version({"requires": None}) is None
+
+
+# --------------------------------------------------------------------------
+# The decision itself
+# --------------------------------------------------------------------------
+
+class TestCheck:
+    def test_blocks_when_plugin_needs_a_newer_core(self):
+        ok, reason = compatibility.check(
+            {"name": "Hockey Scoreboard", "min_ledmatrix_version": "3.2.0"}, "3.1.0")
+        assert ok is False
+        assert "3.2.0" in reason and "3.1.0" in reason
+        assert "Hockey Scoreboard" in reason
+
+    def test_allows_equal_version(self):
+        ok, _ = compatibility.check({"min_ledmatrix_version": "3.2.0"}, "3.2.0")
+        assert ok is True
+
+    def test_allows_newer_core(self):
+        ok, _ = compatibility.check({"min_ledmatrix_version": "3.2.0"}, "4.0.0")
+        assert ok is True
+
+    def test_allows_when_no_floor_declared(self):
+        ok, reason = compatibility.check({"id": "x"}, "3.2.0")
+        assert ok is True and reason is None
+
+    def test_untrustworthy_core_version_allows_everything(self):
+        """The v3.1.0 release reports 1.0.0. Nearly every manifest floors at
+        2.0.0, so blocking here would stop those users installing any plugin
+        at all — strictly worse than the problem being solved."""
+        ok, reason = compatibility.check(
+            {"min_ledmatrix_version": "3.2.0"}, "1.0.0")
+        assert ok is True and reason is None
+
+    def test_unparseable_core_version_allows(self):
+        ok, _ = compatibility.check({"min_ledmatrix_version": "3.2.0"}, "not-a-version")
+        assert ok is True
+
+    def test_unparseable_floor_allows(self):
+        ok, _ = compatibility.check({"min_ledmatrix_version": {"nope": 1}}, "3.2.0")
+        assert ok is True
+
+    def test_v_prefix_tolerated_on_both_sides(self):
+        ok, _ = compatibility.check({"min_ledmatrix_version": "v3.3.0"}, "v3.2.0")
+        assert ok is False
+
+    @pytest.mark.parametrize("floor,core,expected_ok", [
+        ("3.2.0", "3.2.1", True),
+        ("3.2.1", "3.2.0", False),
+        ("3.10.0", "3.9.0", False),   # numeric compare, not lexical
+        ("3.9.0", "3.10.0", True),
+    ])
+    def test_ordering(self, floor, core, expected_ok):
+        ok, _ = compatibility.check({"min_ledmatrix_version": floor}, core)
+        assert ok is expected_ok
+
+
+# --------------------------------------------------------------------------
+# The gate in install_plugin
+# --------------------------------------------------------------------------
+
+def _write_plugin(plugins_dir: Path, plugin_id: str, manifest: dict) -> Path:
+    path = plugins_dir / plugin_id
+    path.mkdir(parents=True)
+    (path / "manifest.json").write_text(json.dumps(manifest), encoding="utf-8")
+    (path / "manager.py").write_text("class P: pass\n", encoding="utf-8")
+    return path
+
+
+@pytest.fixture
+def store(tmp_path, monkeypatch):
+    """A PluginStoreManager whose download step is stubbed to drop a plugin
+    directory in place, so the test exercises the post-download validation
+    path without touching the network."""
+    from src.plugin_system.store_manager import PluginStoreManager
+
+    plugins_dir = tmp_path / "plugin-repos"
+    plugins_dir.mkdir()
+    mgr = PluginStoreManager(plugins_dir=str(plugins_dir))
+    mgr.logger = MagicMock()
+    return mgr, plugins_dir
+
+
+class TestInstallGate:
+    """`install_plugin` is the chokepoint: `_reinstall_with_rollback` calls it,
+    so gating there covers updates too, and a refused update restores the
+    version the user already had."""
+
+    def _install_with_manifest(self, store, manifest, core_version, monkeypatch):
+        mgr, plugins_dir = store
+        plugin_id = manifest["id"]
+
+        monkeypatch.setattr(
+            mgr, "get_plugin_info",
+            lambda *a, **k: {"repo": "https://example.invalid/r",
+                             "plugin_path": f"plugins/{plugin_id}",
+                             "branch": "main"})
+        # Stand in for the download: put the files where install_plugin expects.
+        monkeypatch.setattr(
+            mgr, "_install_from_monorepo",
+            lambda *a, **k: bool(_write_plugin(plugins_dir, plugin_id, manifest)))
+        monkeypatch.setattr(mgr, "_install_from_monorepo_api", lambda *a, **k: False)
+        monkeypatch.setattr(mgr, "_install_dependencies", lambda *a, **k: True)
+
+        import src
+        monkeypatch.setattr(src, "__version__", core_version)
+        return mgr.install_plugin(plugin_id), plugins_dir / plugin_id
+
+    def test_refuses_and_leaves_nothing_behind(self, store, monkeypatch):
+        manifest = {
+            "id": "needs-newer", "name": "Needs Newer", "class_name": "P",
+            "display_modes": ["a"], "min_ledmatrix_version": "9.9.9",
+        }
+        ok, path = self._install_with_manifest(store, manifest, "3.2.0", monkeypatch)
+
+        assert ok is False, "install must refuse a plugin that needs a newer core"
+        assert not path.exists(), (
+            "a refused install must not leave a half-installed directory — "
+            "plugin discovery would pick it up and fail to load it")
+
+    def test_allows_a_compatible_plugin(self, store, monkeypatch):
+        manifest = {
+            "id": "fine", "name": "Fine", "class_name": "P",
+            "display_modes": ["a"], "min_ledmatrix_version": "3.0.0",
+        }
+        ok, path = self._install_with_manifest(store, manifest, "3.2.0", monkeypatch)
+
+        assert ok is True
+        assert (path / "manifest.json").exists()
+
+    def test_untrustworthy_core_does_not_block_installs(self, store, monkeypatch):
+        """Regression guard for the worst possible outcome of this feature:
+        users on the v3.1.0 release (which reports 1.0.0) must not be locked
+        out of the plugin store entirely."""
+        manifest = {
+            "id": "floored", "name": "Floored", "class_name": "P",
+            "display_modes": ["a"], "versions": [{"ledmatrix_min": "2.0.0"}],
+        }
+        ok, path = self._install_with_manifest(store, manifest, "1.0.0", monkeypatch)
+
+        assert ok is True, (
+            "a core below the trustworthy floor must not block installs — "
+            "nearly every published manifest floors at 2.0.0")
+        assert (path / "manifest.json").exists()
+
+
+class TestLoaderAndStoreAgree:
+    """Both read the same manifests; a disagreement means one of them is
+    lying to the user."""
+
+    @pytest.mark.parametrize("manifest,core,expected", [
+        ({"min_ledmatrix_version": "3.2.0"}, "3.1.0", False),
+        ({"versions": [{"ledmatrix_min": "2.0.0"}]}, "3.2.0", True),
+        ({"versions": [{"ledmatrix_min_version": "9.0.0"}]}, "3.2.0", False),
+        ({}, "3.2.0", True),
+    ])
+    def test_same_verdict(self, manifest, core, expected):
+        from src.plugin_system.plugin_loader import PluginLoader
+
+        store_ok, _ = compatibility.check(manifest, core)
+        assert store_ok is expected
+
+        # The loader resolves the floor through the same helper, so a
+        # divergence in spelling handling would show up here.
+        loader_needed = compatibility.parse_semver(
+            compatibility.declared_min_version(manifest))
+        current = compatibility.parse_semver(core)
+        loader_would_warn = (
+            loader_needed is not None
+            and current is not None
+            and current >= compatibility.TRUSTWORTHY_FLOOR
+            and loader_needed > current
+        )
+        assert loader_would_warn is (not expected)
+        assert hasattr(PluginLoader, "_warn_if_incompatible")