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BFM-decomp/docs
Drew T 0c2b37a287 fix(gate): overlays.mk carve-state snapshot was singular, so the revert half-restored
Found by running one reject to ground. After a gate that REJECTED
resident:func_800D06E8, config/overlays.mk had a 4th JTBL_PADS entry and had
LOST `--pre hdr.rodata.o` (the §440 resident leading-rodata sandwich). The
binary then would not build at all -- "consumed 3 rodata jump table(s) but 4 pad
spec(s) given -- table-count drift vs the carve" -- while src/ was perfectly
clean, which is the only place anyone looks before building.

Root cause is a silent narrowing in the classic shape. harvest_verify snapshots
ONLY the gating binary's own overlays.mk block on purpose (the file is shared by
every parallel gate; a whole-file restore resurrects other binaries' lines --
the S62 defect). But _mk_block_span was SINGULAR: the first `# --- <binary>`
header through the next `# --- `. A binary whose carve state spans more than one
block was half-snapshotted and silently half-restored. It returned a TRUE span
for a scope smaller than the caller believed, and nothing compared the two (R32).

Blast radius measured before costing (R37): 1 of the 142 binaries that have a
block -- resident, which has exactly two (§8e pad spec, §8f leading-rodata
sandwich) and still holds 587 instructions of open stubs.

_mk_block_spans (plural) snapshots a LIST, restores tail-first so earlier spans
stay valid, collapses to the snapshot when the header count changed rather than
leaving half-state, and RE-READS and compares the result -- the defect it
replaces was a reported success. _mk_block returns None (not []) for the 71
binaries with no block, so the caller's guard keeps its meaning.

Negative control, three ways:
  * snapshot -> restore is a NO-OP on 142/142 binaries with a block;
  * the real S75 damage is fully undone;
  * the OLD single-block restore provably does NOT undo it -- the positive
    control that proves the fix is load-bearing, not decorative.

Cookbook §444 also records the two other findings from the same reject: the
classified ledger stores the LADDER'S FINAL verdict (the recorded CC1-FAIL came
from a late sig_unify rung; the raw draft compiles and fails on BYTES), and
match_one MATCH + rtu_match MATCH is still not bankable -- func_800D06E8's real
blocker is a jump table (built binary 20 bytes longer, 0x800CEDFC holds a table,
69,571 words shift), because neither matcher LINKS.
2026-09-02 20:33:21 -06:00
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2026-09-02 16:45:33 -06:00