Keep the test suite out of the developer's real HyperView store

`Dataset(..., persist=False)` skips the dataset, but workspace state still went
to whatever `StorageConfig` resolved from the environment -- by default the
developer's own `~/.hyperview`. Four test modules redirected it themselves; the
other thirty-three did not, so a test run wrote fixture workspaces into the same
registry the demos and Static Space exports read from. On this machine that had
accumulated 2,686 of them since April, against 62 real workspaces, and nothing
stopped a fixture id from colliding with a real one.

An autouse session fixture points both storage roots at a temporary directory.
That covers every registry, not just datasets: `get_runtime_config_dir()`
derives the config directory from `datasets_dir.parent`, so workspaces.json,
providers.json and jobs.json move with it.

A second fixture asserts the real registry's mtime is unchanged around every
test, so a future code path that resolves the store some other way fails here
instead of silently polluting the developer's machine again.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: mnm-matin

tests/conftest.py

@@ -0,0 +1,60 @@
+"""Keep the test suite out of the developer's real HyperView store.
+
+`Dataset(..., persist=False)` skips writing the dataset, but workspace, provider
+and job state still land in the registry directories that `StorageConfig`
+resolves from the environment -- and those default to `~/.hyperview`. Without
+this fixture a test run silently accumulates fixture workspaces in the same
+registry the demos and Static Space exports read from, where a test's workspace
+id can collide with a real one.
+
+Redirecting both storage roots at a per-session temporary directory pins every
+registry path with them: `get_runtime_config_dir()` derives the config directory
+from `datasets_dir.parent`, so workspaces.json, providers.json and jobs.json all
+follow the datasets directory here.
+"""
+
+from __future__ import annotations
+
+import os
+from pathlib import Path
+
+import pytest
+
+
+@pytest.fixture(scope="session", autouse=True)
+def isolate_hyperview_store(tmp_path_factory: pytest.TempPathFactory):
+    root = tmp_path_factory.mktemp("hyperview-store")
+    datasets_dir = root / "datasets"
+    media_dir = root / "media"
+    datasets_dir.mkdir()
+    media_dir.mkdir()
+
+    previous = {
+        "HYPERVIEW_DATASETS_DIR": os.environ.get("HYPERVIEW_DATASETS_DIR"),
+        "HYPERVIEW_MEDIA_DIR": os.environ.get("HYPERVIEW_MEDIA_DIR"),
+    }
+    os.environ["HYPERVIEW_DATASETS_DIR"] = str(datasets_dir)
+    os.environ["HYPERVIEW_MEDIA_DIR"] = str(media_dir)
+    try:
+        yield root
+    finally:
+        for key, value in previous.items():
+            if value is None:
+                os.environ.pop(key, None)
+            else:
+                os.environ[key] = value
+
+
+@pytest.fixture(autouse=True)
+def guard_real_hyperview_store():
+    """Fail loudly if a test writes into the real store despite the redirect."""
+
+    registry = Path.home() / ".hyperview" / "workspaces.json"
+    before = registry.stat().st_mtime_ns if registry.exists() else None
+    yield
+    after = registry.stat().st_mtime_ns if registry.exists() else None
+    if before != after:
+        raise AssertionError(
+            f"test wrote to the real workspace registry at {registry}; "
+            "it must go through the isolated store instead"
+        )