A THIRD copy of the rule lived in the projection that decides where the
GPU actually renders a later tab: manual `stop - column % stop`
arithmetic, and a per-character advance calling `UnicodeWidthChar::width`
directly. So the previous commit's mutation broke the minimap while
leaving the rendering path untouched --- the shared bound could still
drift from the columns the GPU draws at.
Both now delegate to `pmacs_protocol::columns::advance_char`: the tab
width is DERIVED from the shared advance rather than recomputed, and the
per-character step is the shared one.
The projection's stream semantics stay local, because they are real and
distinct: the column runs ACROSS chunks, so adornment text shifts a
later tab, and a newline restarts it. That is why the wrapper still
exists rather than being replaced outright.
Evidence, not assertion: mutating the tab stop in
`pmacs_protocol::columns` now breaks BOTH
`tab_projection_uses_shared_stops_and_unicode_columns` and
`minimap_columns_match_code_tab_and_unicode_widths`. Six adornment rows,
including `caret_projection_accounts_for_inline_adornments`, still pass,
so the stream behaviour survived the delegation.
`TAB_STOP_COLUMNS` and `UnicodeWidthChar` are now unused imports in
pmacs-gpu and are dropped --- which is itself the check that no copy of
the rule remains in this crate.
Levi Neuwirth
364eb7b095