Robert Allan JamesandClaude Sonnet 5
7e2fd9f044
Found while building the analysis report for the ACL-RWT relaunch campaign: cfg=0 was missing from run coverage for 2 of 3 seeds, reproduced identically across all three architectures. Root-caused rather than worked around, per Captain Bob's "this is worrisome." SWAP-MTX (capsules/doe.4th Block 2104) never actually swapped two RUN-MATRIX cells -- it performed a lossy one-way copy (second MATRIX! call mis-targeted mat[i] again instead of mat[j]). Confirmed by direct empirical test on the hosted build: INIT-MATRIX gives mat[0]=0, mat[5]=5; after 0 5 SWAP-MTX, mat[0]=0 (unchanged, should be 5) and mat[5]=0 (correct), with the original value 5 permanently destroyed. Every Fisher-Yates shuffle this mechanism has ever run silently duplicated some values and dropped others -- not a true permutation. Not new, not introduced by item 4.6/Stadium work; predates this session. Fixed with explicit temp variables (SW-I/SW-J/SW-VI/SW-VJ), trivially verifiable by inspection over clever stack juggling. Verified on the hosted build for all three seeds used by the relaunch campaign: each now produces all 16 cfg values exactly 30 times, run_id 0-479 fully distinct. Three-arch QEMU acceptance clean: 1012/0/0 POST on all three, identical dict_hash (expected -- doe.4th isn't C-registered or auto-loaded at boot). BLOCK_MAP.md correctly shows only doe.4th's own hash changed. Also includes the R analysis/chart pipeline (analyse_stadium_relaunch.R) built for the relaunch campaign report, and the three acceptance boot logs. Retroactive caveat: the relaunch campaign's own run-matrix coverage (experiments/bare_metal/runs/acl-rwt-20260820/) is not a valid uniform permutation, having run against the buggy shuffle. Whether to re-run it against the fix is a separate call, not made here. Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
disk/
QEMU disk images used for Artemis (block-storage VM) persistence testing.
Mounted via Makefile.starkernel's ARTDISK variable (default
disk/artemis.img) as a virtio-blk-pci device on all three
architectures' kernel QEMU boots — not scripts/rundisk.sh, which targets
a separate, currently-unused disks/ (plural) directory for the hosted
VM's --disk-img= flag instead.
artemis.img— standard Artemis persistence test disk. Reformatted 2026-08-02: this image had been stuck in a corrupted state (validLithosAnankemagic header, but data not matching whatART-READ-TESTexpects) since before this repo's own git history begins (git logshows it already broken at the initial commit, carried over from the pre-split monorepo). Chasing down the resulting persistentFAIL: persist-readtraced to the data, not the code — the write→reboot→read round trip works correctly on a fresh image (seeartemis-debug-roundtrip.imgbelow). Reformatted by blanking the file and letting a normal boot format+write-test it; verifiedPASS: persist-readon amd64, aarch64, and riscv64 against the same image afterward (cross-arch resume, matching the arch-neutral on-disk format.claude/ARTEMIS.mdspecifies).artemis-debug-roundtrip.img— round-trip regression fixture created during that investigation. Known-good: format → self-test → write-test → reboot → resume →PASS: persist-read, confirmed 3 times in a row. Keep this in a passing state; if a future change breaks it, that's a real regression, not a stale-fixture artifact likeartemis.imgwas.artemis-persist-test.img— persistence round-trip test image (pre-existing; history/state not re-verified during the above investigation).artemis-poison.img— a separate test image (exact scenario not documented elsewhere in the repo as of this writing; name suggests an adversarial/corruption test, not confirmed).artemis-unrecognized-test.img— exercisesART-HALT-UNRECOG(.claude/ARTEMIS.mdacceptance criterion #6). Regenerated 2026-08-02: the previous copy of this file had itself been silently reformatted by a since-fixed bug in the generic block subsystem (src/block_subsystem.c) — it carried a valid low-level'STFR'/v2 header despite being meant to represent foreign disk content, direct forensic evidence of the bug described in.claude/ARTEMIS.md's Build Status item 6. Regenerated as 30MB of a repeatingPOISON-UNRECOGNIZED-DISK-TEST-FIXTURE--NOT-BLANK-NOT-STFR-NOT-ARTEMIS--ASCII pattern — deliberately neither blank, nor the block subsystem's own'STFR'magic, nor Artemis's"ARTEMIS\0"marker. Verified on amd64 and riscv64 post-fix: boot correctly halts (ARTEMIS HALT: unrecognized disk content) and the file's sha256 is now byte-for-byte identical before and after boot. Keep this fixture in this poisoned state — if a future change makes its sha256 change across a boot, that is exactly the regression this fixture exists to catch.
Note on incidental header churn: artemis.img picks up a few changed
header bytes on every ordinary boot even though no user data changes —
blk_subsys_attach_device() always records a fresh mounted_time on a
successfully recognized disk, which gets flushed at shutdown. This is
expected bookkeeping, not a bug; revert it before committing rather than
carrying timestamp noise in git history.
These are regenerable QEMU raw disk images, not source — see
.claude/ARTEMIS.md for the storage model they exercise.