MARK-010 LOW: raw C stack arrays and raw pointer indexing in MARK.c vs the ABC idioms

MARK.c carries raw markref refs[MARK_MAX_REFS] (16KB stack, MARK.c:741) and markframe stk[MARK_MAX_STACK] (MARK.c:598) where CLAUDE.md §1 / abc mandate the typed forms (a_pad, or BASS a_carve for the 16KB table), plus raw pointer indexing u8 state = linef[0][(size_t)depth * 4 + 2] (MARK.c:699) — bounds-safe only via the marker contract — where u8csAt is the idiom. Style-only: no observed misbehavior, but it is exactly the slice/pointer mode-mixing abc calls the worst sin. From the 2026-07-07 mark/ diagnostic review; code confirmed in-tree. Method Issues.

Input

Context

refs[512] is also the silent-truncation table of MARK-007 — sizing policy and storage idiom want one combined fix.
16KB of stack per render call is a real cost on deep call chains (dir walk).

Goals

Typed/idiomatic storage: a_pad for the fixed frame stack, BASS carve for the ref table; u8csAt over raw double-indexing; zero behavior change (byte-identical wiki render).

Constraints

Pure refactor, land after/with MARK-007; ABC buffer rules (abc BASS section — acquire in own frame, no carve between lign/cquire).

WIP

Design decisions

(pending)

TODOs

Swap storage idioms; byte-identical render check; suite green.

Blockers and bummers

None known.

Outcome

(pending)