# std79 DoE — 3(architecture) × 9(identity) × 3(replicate) randomized full-factorial

The formal successor to `experiments/std79-exerciser/`'s ad hoc campaign (see FABRIC-3.md §XII),
requested as a genuine randomized full-factorial design matching this project's own DoE
methodology (`capsules/doe.4th`'s Fisher-Yates run-matrix shuffle) rather than convenience
batching — and written entirely in FORTH, not host-orchestrated shell scripting. See
FABRIC-3.md §XV for the design writeup, §XVI for the real aarch64 Stadium/COOL scaling bug that
was found, root-caused, and fixed (`src/starkernel/vm/stadium.c`), and §XVII for a second,
related Stadium bug (`stadium_grant_quota()`'s donor-floor) found while writing up §XVI and
fixed in a follow-up pass — the 3-boot batching workaround below is now historical only; a
single boot with all 9 identities simultaneously live works cleanly on all three architectures
as of both fixes.

`std79-doe.fth` is not a capsule loaded via `EXEC` — feed it as raw text to a running REPL
(e.g. `socat - UNIX-CONNECT:<serial_sock> < std79-doe.fth`), same as the original exerciser, then
invoke `EXEC-STD79-DOE ( seed lo hi -- )` once loaded. `lo`/`hi` select which identity-index
range (0-8) this boot's live VMs cover — pass `0 8` for a single boot with all 9 identities
simultaneously attached (now confirmed working on all three architectures, see §XVI); a narrower
range (e.g. `0 2`, `3 5`, `6 8`) still works too, for running the DoE across multiple smaller
boots if ever needed for an unrelated reason. Every boot must use the *same* seed so
`INIT-MATRIX`/`SHUFFLE-MATRIX` reproduce the identical 27-slot master permutation; only the
`lo`/`hi` filter differs, so `run_id` (always the slot's true position in the master shuffle,
0-26) stays directly comparable across boots.

`results-20260911/` holds the raw captured serial output from the *original* campaign (pre-fix):
`amd64-doe-raw.log` (all 27 trials, one boot, all 9 identities simultaneously live) and
`{aarch64,riscv64}-doe-batch{1,2,3}-raw.log` (27 trials each, split across 3 boots of 3
identities, the then-necessary workaround). **Result: 81/81 trials correct, 0 mismatches.**

`results-20260911-stadium-fix/` holds the rerun after §XVI's O(ncells)-scan fix — one boot per
architecture, all 9 identities simultaneously live in every boot, same seed throughout.
**Result: 81/81 trials correct, 0 mismatches, byte-identical output to the original campaign** —
and the DOE-RUN header sequence (run_id/id_idx/id_label/rep assignment) is md5-identical across
all three raw logs, confirming the master shuffle is genuinely architecture-independent. Total
per-architecture wall-clock (boot + all 9 identity attaches + full 27-trial run, one continuous
QEMU session): amd64 ~165s, aarch64 ~290s, riscv64 ~161s — aarch64's identity 04 attach alone,
which stalled 90+ minutes before the fix, now completes in ~34s.

`results-20260911-donor-floor-fix/` holds a further rerun after §XVII's donor-floor fix (same
discipline: any Stadium defect repair reruns the whole DoE from the top). **Result: 81/81
trials correct, 0 mismatches**, DOE-RUN header sequence md5-identical to every prior run. Total
wall-clock: amd64 ~161s, aarch64 ~280s (confirms no regression from §XVI's fix), riscv64 ~162s.

`results-20260912-reconfirm/` holds a plain reconfirmation rerun the following day, no code
changes since §XVII's fix (`e51a8d2`) — same seed, same single-boot-per-architecture, all 9
identities simultaneously live. **Result: 81/81 trials correct, 0 mismatches**, shuffle sequence
still md5-identical to every prior run. Total wall-clock: amd64 ~151s, aarch64 ~276s, riscv64
~165s.

`results-20260912-with-heartbeat-csv/` — `EXEC-STD79-DOE` now brackets its trial loop with
`HB-ON`/`HB-OFF` (`doe_log.c`'s per-heartbeat-tick physics/timing CSV logger), so
`scripts/extract_doe.sh`'s automatically-generated CSV finally carries real data for this
campaign — every prior run's extracted CSV was silently empty, since `g_doe_log_enabled`
defaults off and nothing had ever turned it on. Each directory holds both the raw log
(`*-doe-raw.log`) and its paired heartbeat CSV (`*-heartbeat.csv`, ~255-257 rows/architecture,
18 columns: tick_number, elapsed_ns, hot_word_count, avg_word_heat_q48, window_width,
apic_ticks, hera/hermes/artemis heat_q48, etc. — see `doe_log.c`'s own header comment for the
full column list). **Result: 27/27 trials correct on every architecture** (verified via the
campaign's most distinctive result markers — the two 18-19 digit `M*`/`M/MOD` values and the
`2147483648 2/` result all show exactly 27 occurrences, zero faults) — **not** verified via
exact substring/byte reconstruction, because turning HB-ON on for the whole run exposed a real,
if purely cosmetic, effect: the heartbeat tick's async CSV printer and the trial loop's own
console output share the same serial line with no locking between them, so CSV rows get spliced
mid-token into the trial output on the wire (confirmed live: a "missing" `DOE-RUN,0` line turned
out to be `DOE-RUN,` and `0 ,6 ,04,2` on two separate physical log lines with a full CSV row
printed in between). The underlying FORTH execution itself is unaffected — values are correct,
nothing is corrupted in memory — only the printed character stream interleaves, so downstream
tooling that wants an exact reconstruction of the trial-output stream from these three raw logs
needs to account for that (strip `[HADES][DOE ] ...` fragments and rejoin) rather than assume
one physical line is one logical print.

`analysis-20260912/` builds exactly that reconstruction and turns it into a real 3×9 factorial
analysis: `correlate_doe.py` labels every heartbeat-tick row with the trial that was active when
it printed, `combine.py` merges all three architectures into `combined.csv` (768 rows, Q48.16
fields decoded to floats), and `analysis.R` computes per-cell (architecture × identity) means/SD
and a two-way ANOVA for each of 12 telemetry metrics, rendering one boxplot SVG per metric. See
`analysis-20260912/README.md` for the pipeline and `analysis-20260912/ANALYSIS.md` for the
report itself — key findings: identity significantly affects word-heat/window-sizing metrics
(expected — different identities execute different word sets), architecture significantly
affects timing metrics (APIC ticks/tick, timing variance, fleet heat — expected, different QEMU
targets), and **zero architecture × identity interaction on any metric** — the two factors'
effects are clean and separable, not confounded.