# boundary_layer_exception

## v1

**Why this iteration:** Cross-referenced lift combining `conductor/code_styleguides/python.md` §17.7 + §17.8 (lines 352-359) + `data_oriented_design.md` §8.5 boundary-exception + §8.6 (lines 193-202) + `type_aliases.md` §1 (lines 54-72). This is the boundary-layer rule from three canonical sources, all lifted verbatim. The plan updated the v1 in t1_4 to cross-reference the §17.7 exception, §17.8 enforcement, §8.6 boundary definition, and the type_aliases.md Metadata-as-boundary-type rule.
Future variants will test alternative encodings (rationale-first, tabular, single-source) against this baseline.
**Source:** `conductor/code_styleguides/python.md:352-359 + data_oriented_design.md:193-202 + type_aliases.md:54-72`

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**Lifted:** 2026-07-02 (Phase 1 harvest by Tier 3 worker; user directive 2026-07-02 moved the header into this meta file)