test: cover the "preferences unavailable" degradation path

[untraceablez]

What I found

You asked why request.state.prefs was None in tests. It isn't — I had the line numbers inverted when I reported that. The middleware runs and succeeds normally; card.py:104 and search.py:71 (the prefs-populated branches) are covered. What was uncovered were the fallbacks on the next lines.

Re-reading them, the last three uncovered spots in the repo turned out to be a single coherent path split across three files:

Location	Line	Role
main.py	147-148	except SQLAlchemyError → request.state.prefs = None
routes/card.py	105	_hist_currency cookie fallback when prefs is None
routes/search.py	72-73	_display_prefs cookie fallback when prefs is None

They're unreachable in normal tests precisely because the middleware always runs and always succeeds. _install_prefs_loader promises:

Never 500s a request over prefs: a DB hiccup (or the table not yet migrated) falls back to None, and the read helpers use their existing cookie/default path.

Nothing tested that promise. And "the table not yet migrated" is a real scenario — an instance upgraded before alembic upgrade head catches up, which is exactly when you most want pages to render.

What this adds

A fixture makes every Preferences lookup raise OperationalError, then asserts /search, /card/{id} and / still render and still honor the visitor's cookies — not just "doesn't 500", but "doesn't silently revert to defaults either":

• /search still applies the scryme_search_filter cookie (Counterspell in, Grizzly Bears out).
• /card/{id} still resolves scryme_hist_currency=gbp and renders £5.00.
• / renders with no prefs cookies at all.

I verified the fixture actually bites rather than passing vacuously: under it, coverage of those three files inverts — main.py misses 143-146 instead of 147-148, card.py misses 104 instead of 105, search.py misses 71 instead of 72-73. So the tests are genuinely driving the degradation path.

Result

Repo-wide coverage is back to 100% (0 missed lines), 1179 tests. Tests only, no behavior change.

Local note: a full run can trip the known test_images.py::test_ensure_downloads_then_caches flake if SCRYME_IMAGE_CACHE_DIR has leftovers from a previous run (it sees 0 downloads). Clean cache → passes. CI starts clean so it never hits this.

🤖 Generated with Claude Code