fix: reject unallocated AL postal-code prefixes (#118)#134
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…ing (#118) The block resolver used a continuous bisect, so any 4-digit code >=1000 resolved to its enclosing district block — including codes in prefixes that belong to no district (e.g. 1900, 9999), which were returned as high-confidence regions despite not existing. Key on the allocated 2-digit district prefix instead: real codes and every #118 gap code still resolve identically (the golden test is unchanged), but non-existent codes now return not-found rather than a fabricated region. Flagged by Codex review on #133.
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Follow-up to #133, addressing a Codex review finding.
Problem
The Albania block resolver used a continuous
bisect, so every 4-digit code ≥ 1000 resolved to its enclosing district block — including codes whose 2-digit prefix belongs to no district (e.g.1900,2100,9999). Those non-existent codes were returned asmatch_type="estimated", confidence0.9— indistinguishable from a real answer. Associating a confident region with a code that doesn't exist is a false signal.Fix
Key on the allocated 2-digit district prefix instead of a continuous range. A code resolves only when its prefix maps to a real district; otherwise it returns not-found.
1900 → None,9999 → None.1099 → AL022) — the block scheme is authoritative at district (2-digit) granularity, which is the finest our data supports.This aligns AL with the rest of the service's quality-over-coverage stance (0.85 geocode threshold, cross-border guard): prefer no answer over a confident wrong one.
Tests: 49 passed across the AL + data_loader suites, ruff clean. README + CHANGELOG updated.