The PostgREST query that silently ORDER BY ctid: a Supabase week, distilled

The fourth call of the week Catherine calls from the Maisons-Laffitte site on a Tuesday afternoon in early May. "It's broken, but it's a quick fix." That's her line — I know it, and she's usually right. She describes it in three sentences: the newsletter export for the enrolled-students segment comes back with ninety-two names, the planning view shows ninety-two active courses, but the counter page shows eighty-nine. Three enrolled students missing. She'd checked the database directly — they're all there. "Why three steps for that?" She's not asking for my benefit. She's asking for herself. Except this time, hanging up, I realize it's the fourth time this week I've hung up thinking the same thing. Four Supabase incidents, four fixes, four closed tickets. And not a single exception raised by the database. I reopen the three previous ones and lay all four side by side on screen. This isn't four bugs. It's one failure mode, declinated four times. The first three Episode 1 was about the default GRANT s Supabase places on functions and policies. A SQL function created without an explicit REVOKE inherits anon access that nobody wrote in the migration, and that nobody caught in review because the diff doesn't show it. The function works. It's just callable from outside. [CANONICAL URL EPISODE 1: to fill in after publication of #48 — "3 Supabase security incidents, one shared root cause: SECURITY DEFINER inherits EXECUTE TO PUBLIC"] Episode 2, an ON DELETE SET NULL cascade coupled with a CHECK NOT NULL on the target column. The parent DELETE attempts the SET NULL , the CHECK rejects it, and the transaction surfaces an error we read as a deletion failure — while it actually masks a consistency assumption we'd held for three months. The query fails loudly, which is more charitable than the other three cases, but the diagnosis heads in the wrong direction because nobody had declared that the two constraints lived in tension. [CANONICAL URL EPISODE 2: to fill in after publicati