Implements the 2026-09-09 fleet-id-order resolution, section 3 item 1. Given the
pre-turn save, compute the ids new in each post-turn save, match the client-minted
(node nibble != 0) new fleets by a key that does not mention the id -- (LocID or
FPlan destination, sorted ship-id set) -- build the bijection pi, rewrite every
fleet reference, compare the master id lists as sets, mask /Summary/Checksum with
its reason on the line, and print pi.
Acceptance, both halves:
bp-pinA vs bp-pinB IDENTICAL modulo pi = {1970<->1986} (35 leaves -> 0)
ad-oracle-A vs -B REFUSED, then DIVERGED: 94 leaves (unchanged)
Five guards, every one refusing rather than degrading: only ids absent from the
pre-turn save; only non-zero node nibbles; pi must permute one set; content keys
must correspond one-to-one and be unique per side; and no leaf anywhere may hold a
permuted id at an unmodelled site (matched on raw bytes, not the reader's typed
value). A refusal rewrites nothing and falls back to the ordinary comparison.
Three corrections to the specification from contact with the data, in
findings/subsystems/relabel-new-ids.md section 4: FtName is an id-attached label
and needs the same treatment as the id; relabelling the Flt[] keys is the wrong
operation (exchange the bodies -- the fleet table is id-ordered and identical in
both saves); a node's new-id set spans object kinds.
Default path proven unchanged: pre- and post-change modules agree on the root
digest, coverage, mask hits and every (path, digest) in the tree over all 43 saves
under two policies, and on 5,602 lines of CLI stdout across every mode.
Also fixes a pre-existing, unrelated test failure: the re-save localisation test
enumerated pairs over sorted filenames and hard-coded the direction 4 -> 0, which
a later corpus addition reversed. Suite 38 -> 62 tests, all passing.
The complement to the per-function compare harness. Instead of "did this
function's declared outputs match", it asks "is the entire simulation state
still identical" -- so no region-declaration mistake can hide from it.
Coverage is PROVED, not declared: the digest tree is re-serialised and compared
byte-for-byte against the inflated save on every run. When that reconstruction
reproduces the stream, the whole file is a function of the digest's inputs. A
run that cannot account for the file says so and exits non-zero. This is the
direct answer to B4's three hooks that printed "0 diverged" over an empty
region set.
It localises. The root is the fold of a per-subsystem / per-object tree with
named objects, so the known load->re-save delta reports as exactly five leaves
-- /Summary/Checksum and four /Sim/players/Player[...]/Status 4->0 -- naming the
two Singularity players by id where the raw byte diff could only say "1st of
two". One real End Turn reports as 108 fully attributed differences.
Float-parity policy is explicit and strict by default (STATE_CHECKSUM.md 3):
raw IEEE-754 bits; a `canonical` policy for signed zero and NaN payloads only;
and deliberately NO tolerant hashing mode, because quantisation moves the cliff
rather than removing it and destroys the roll-up. Tolerance lives in the differ
as --ulps, applied after localisation. Corpus census: 0 NaN, 0 -0.0, 0
subnormals across 4,474 float leaves, so the strict default costs nothing today
and a test fails the day that changes.
Validated on the real saves (verify/results/state-checksum/): 10 files, 4
distinct contents, all STABLE + COVERED; chain record/verify works on the real
turn1-3 saves. The VM-driven replay loop is designed (section 5) but UNRUN.
Section 3.5 names the one question the host side cannot settle -- whether the
turn pipeline depends on x87 intermediate precision -- and the experiment that
would: force fpu_cw to 0x027f / 0x127f / 0x137f across End Turn and checksum
the three autosaves.
Also recorded: Summary.Checksum is NOT a byte sum over the inflated stream nor
a sum over the int leaves (both ruled out), so nobody repeats those two.
38 tests; sots-engine untouched, clean_room_check.sh OK.
