# PH-BC-001

**Name:** Boundary condition violation (relative or absolute mode)

**Severity:** error

**Input modes:** adapter+dump

**Scope separation (read first):** PH-BC-001 validates **Dirichlet-
type boundary trace behavior in the production rule; Neumann/flux
semantics are outside the production validation scope for v1.0**. The
rule's emitted quantity is `||field.values_on_boundary() −
boundary_target||` — a discrete-L² comparison of Dirichlet-type trace
extraction against a caller-supplied target, not a Neumann flux
check. CITATION.md, README, and test docstrings do not imply broader
rule coverage than V1 provides.

Dirichlet-trace violation metric: discrete-L² norm of
`u|_{∂Ω} − g|_{∂Ω}` on the unit square, mode-branched on `||g||`
(absolute for near-zero Dirichlet, relative otherwise). Threshold
0.01 relative (tri-state) / 1e-3 absolute (binary).