Strict structured-output mode rejects uniqueItems, so every request to a
gpt-5.6-family zero-data-retention endpoint failed with HTTP 400 behind
a generic error; duplicates were already rejected server-side, so the
keyword leaves the wire schemas, pinned by a strict-keyword allowlist
test built from the ledger that hit this.
The bare-BIC redaction pattern deleted every 8- and 11-letter word —
Openbank, BAUMARKT, RACETRACKER — blinding the model to the payee it
was asked to classify and tripping the unsafe-merchant check on honest
answers. BICs now die only labeled or attached to their IBAN, account
labels join the redaction secrets, an identifier-shaped merchant name
degrades to a merchant-less proposal instead of failing the row, and a
provider error inside an HTTP 200 envelope is reported as such (numeric
code only) instead of as envelope corruption.
The gpt-5.6 family's zero-data-retention endpoints declare
max_completion_tokens, so sending max_tokens under require_parameters
excluded every ZDR route and returned HTTP 404 for the whole family.
The cap is retired: the strict schema, the finish_reason check and the
64 KiB read cap already bound the response.
The model fields now offer the provider's public ZDR catalog filtered
by the exact conditions completions are routed under (live endpoint,
strict structured outputs), fetched server-side, cached for an hour,
and served at GET /api/models; the inputs stay free text so an unlisted
model remains usable when the catalog is unreachable.
Lars Nolden