param_space() injectivity becomes a stated, enforced compile invariant. One
structural check (check_param_namespace_injective) replaces the fan-in machinery
(check_fan_in_distinguishability, check_composite_fan_in, signature_of,
leaf_has_param) and the AmbiguousKnob binder branch. The error is path-carrying
(DuplicateParamPath) and the binders run the check before name resolution, so the
canonical by-name author sees the structural cure (.named(...)) instead of the
AmbiguousKnob symptom. param_space() stays infallible; the invariant lives in the
compile step (C23).
Two render-identity-only fan-in rejections (asymmetric param/paramless collision,
role-vs-leg signature collision) are intentionally dropped — neither is a
param_space duplicate (every knob keeps a unique path), and the property they
guarded (render distinguishability) has had no live consumer since the renderer
was retired in 0026. The larger is pinned by a now-compiles fixture.
Boss-signed under spec_auto_sign: objective gates green (precondition clean,
self-review clean, grounding-check PASS without override) + a unanimous five-lens
spec-skeptic panel. The grounding lens first BLOCKed a false set-equality claim;
the user ratified dropping both render-identity cases, the spec was reframed onto
the injectivity scope, re-grounded PASS, and the re-panel returned unanimous SOUND.
refs #59
Brummel
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