Arm E, capability only. A profile MAY name a renderer per suffix; no
domain-aware renderer is written here, that stays a Non-Goal, and `_RENDERERS`
is empty on purpose so the emptiness reads as a decision rather than an
omission.
THE LAYERING IS THE DESIGN, not an implementation detail. `extract.py` is the
extraction registry and must not import the contract layer, or the dependency
runs backwards and the registry stops standing on its own. So `extract_text`
gains a keyword-only `renderer: Callable[[str], str] | None`, knowing nothing
about profiles, and `inbox.py` -- which already holds the profile at that call
site -- resolves a NAME to a function. A test asserts extract.py still contains
no reference to the profile layer, because that constraint is the whole reason
the parameter is shaped this way.
The renderer runs AFTER extraction, never instead of it, so it never has to
re-implement a reader and the two cannot drift. The default is identity, which
is what keeps the five byte-pinned goldens byte-pinned -- asserted per suffix
rather than once.
An unknown renderer NAME is refused rather than falling back to identity: a
silent fallback would produce a bundle that looks rendered and is not, which is
the failure mode this arm exists to make visible. That needed a registered code
(`unknown_renderer`) and its test -- slightly beyond the step's named files,
but the capability cannot ship without defining what an unknown name does.
`tests/test_profile.py`'s exact-field-set assertion went red, as the plan's risk
table predicted. Updated deliberately with the reason recorded: that assertion
exists so a field cannot arrive without someone deciding it should, and its red
run is the mechanism working.
Suite 917 -> 926. All five goldens byte-identical.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Kjell Tore Guttormsen
55a09d6c8e