pmacs/docs/probe-sigint-evidence.md

GPU probe SIGINT lane — run manifest

Every physical run behind docs/gpu-probe-sigint-framing.md §4. Pushed so the evidence travels; the log bodies stay machine-local under /home/jeans/build/pmacs-gate-targets/probe-sigint-evidence/ and are identified here by SHA-256 prefix and byte count.

Provenance honesty

These runs were made before this manifest existed, so their provenance is reconstructed, not captured. Specifically:

• Commands are exact and complete argv. Revision 3 abbreviated R7–R9 as "--test ×N (targets 6–37)" and F5 as "--acceptance ×6", which are descriptions, not reconstructable invocations. They are written out in full below.
• Worktree is exact.
• HEAD is given as a range where the run cannot be pinned to one commit, and marked ~. It is never guessed at single-commit precision.
• Cleanliness was not recorded at the time and is therefore UNKNOWN for every pre-manifest run. It is not inferred.

D0 (below) exists because of this. No conclusion in §4 should rest on a UNKNOWN-cleanliness row once D0 has replaced it.

Artifact identity — suffix is NOT byte identity

Two distinct things were conflated in revision 3 and are separated here.

Cargo suffix is recorded in each log and is therefore known per run. Byte identity is not: target directories have been overwritten many times since, so a hash computed today is the hash of whatever occupies that path now, not of what a given run executed.

That the two differ is demonstrated, not assumed. F1 ran in the main worktree (pmacs-fdccc423) and executed suffixes -5d9105cb7047aab8 and -d4dae4f01bcdef62 — the same suffixes as the panel-worktree sweeps — yet the bytes at those paths differ by worktree:

worktree	gpu_initial_target…-5d9105cb	gpu_invocation…-d4dae4f0
pmacs-fdccc423 (main)	e057803988c34cf7	00f06aeb089ce38d
pmacs-mapping-gen-… (§5b)	1b3cc86cbb8d6092	ede0c07dd9abb456

Same suffix, different source head, different bytes today. So "workspace artifact family" was not an identity class and is withdrawn as a grouping.

Three levels of knowledge, kept apart:

0. Portability caveat. Suffixes below are read from logs that are machine-local; this manifest is the portable record of them, and a reader elsewhere is trusting this transcription, not verifying it. Rows that were never logged say UNKNOWN and are not guessed.
1. Suffix — known, from each log. A differing suffix means Cargo computed a different metadata hash, i.e. it treated the two as distinct compilations.
2. Today's bytes at a path — known, and shown above.
3. The bytes a historical run executed — UNKNOWN. Target directories have been overwritten repeatedly since; a hash computed now is the hash of the current occupant.

So statements of the form "R9 and the sweeps ran byte-different binaries" are withdrawn everywhere. What is established is that they ran different Cargo compilations (different suffixes), which is enough to void the comparison and is all that is claimed. R1 and R2 have no preserved log and cannot claim even a suffix.

Runs

All in worktree pmacs-mapping-gen unless stated. WT=mg is /home/jeans/Repos/personal/pmacs-mapping-gen; WT=main is /home/jeans/Repos/personal/pmacs at 72da24a. All carry CARGO_TARGET_DIR=/home/jeans/build/pmacs-gate-targets/pmacs-mapping-gen-8cb089c8 except WT=main, which uses …/pmacs-fdccc423.

id	exact command (after cargo)	WT	HEAD	clean	Cargo suffixes executed	result	log (sha256/16, bytes)
R1	test --features crdt --test gpu_invocation_acceptance ctrl_c_on_launcher_group ×3	mg	~724b785–5174f73	UNKNOWN	UNKNOWN (no log)	green, 0.15–0.17 s	none preserved
R2	test --features crdt --test gpu_invocation_acceptance	mg	~724b785–5174f73	UNKNOWN	UNKNOWN (no log)	green, 15 passed	none preserved
R3	test --workspace --features crdt --no-fail-fast -- --skip basedpyright ctrl_c_on_launcher_group	mg	~724b785–5174f73	UNKNOWN	-5d9105cb / -d4dae4f0	green	e09a96512035284e 33113
R4	test --features crdt --lib --test gpu_invocation_acceptance --no-fail-fast	mg	~724b785–5174f73	UNKNOWN	-6b4b8223 only	green, 2145 + 15	89050c702de22d57 158812
R5	test --features crdt --no-fail-fast --test gate_script_acceptance --test gpu_invocation_acceptance	mg	~5174f73–b72843a	UNKNOWN	-6b4b8223 only	green	31b3e5249b475479 3706
R6	test --features crdt --no-fail-fast --test gpu_font_acceptance --test gpu_initial_target_acceptance --test gpu_invocation_acceptance	mg	~5174f73–b72843a	UNKNOWN	-91f51d0b / -6b4b8223	green, 11+15+15	332693a39c73731a 4569
R7	test --features crdt --no-fail-fast --lib --bins --test acceptance --test ambient_isolation_acceptance --test auto_indent_acceptance --test auto_indent_crdt_acceptance --test auto_pair_acceptance --test auto_pair_crdt_acceptance --test autosave_acceptance --test bottom_panel_stage1_acceptance --test bottom_panel_stage2a_acceptance --test bottom_panel_stage2b_daemon_acceptance --test bottom_panel_stage2b_gpu_acceptance --test bottom_panel_stage2b_protocol_acceptance --test comment_toggle_acceptance --test compile_mode_acceptance --test gpu_invocation_acceptance	mg	~b72843a	UNKNOWN	gpu_invocation…-6b4b8223 only — R7 does not select gpu_initial_target	green	9e1ebc59ed9f0dd4 187531
R8	test --features crdt --no-fail-fast --test compile_mode_crdt_acceptance --test completion_popup_acceptance --test config_registry_acceptance --test cua_region_acceptance --test desktop_acceptance --test destination_capture_acceptance --test dired_acceptance --test discovery_acceptance --test discovery_stage2_acceptance --test editops_acceptance --test find_file_acceptance --test folding_acceptance --test folding_stage2_acceptance --test full_grid_resync_acceptance --test gate_script_acceptance --test git_status_stage1_acceptance --test gpu_font_acceptance --test gpu_initial_target_acceptance --test gpu_invocation_acceptance	mg	~b72843a	UNKNOWN	-91f51d0b / -6b4b8223 (half2.log:438, :459)	green	8b26ebfcf5f871b4 28677
R9	test --features crdt --no-fail-fast --lib --bins --test acceptance --test ambient_isolation_acceptance --test auto_indent_acceptance --test auto_indent_crdt_acceptance --test auto_pair_acceptance --test auto_pair_crdt_acceptance --test autosave_acceptance --test bottom_panel_stage1_acceptance --test bottom_panel_stage2a_acceptance --test bottom_panel_stage2b_daemon_acceptance --test bottom_panel_stage2b_gpu_acceptance --test bottom_panel_stage2b_protocol_acceptance --test comment_toggle_acceptance --test compile_mode_acceptance --test compile_mode_crdt_acceptance --test completion_popup_acceptance --test config_registry_acceptance --test cua_region_acceptance --test desktop_acceptance --test destination_capture_acceptance --test dired_acceptance --test discovery_acceptance --test discovery_stage2_acceptance --test editops_acceptance --test find_file_acceptance --test folding_acceptance --test folding_stage2_acceptance --test full_grid_resync_acceptance --test gate_script_acceptance --test git_status_stage1_acceptance --test gpu_font_acceptance --test gpu_initial_target_acceptance --test gpu_invocation_acceptance	mg	~b72843a	UNKNOWN	-91f51d0b / -6b4b8223 (log :3066, :3087)	green	b31d98ee2f427eca 214566
R10	test --workspace --features crdt --no-fail-fast --test gpu_initial_target_acceptance --test gpu_invocation_acceptance -- --skip basedpyright	mg	~b72843a	UNKNOWN	-5d9105cb AND -d4dae4f0 (log :3, :24)	green	81b48fd7a0e261dc 3553
F1	build --workspace --no-default-features --features luajit,crdt && test --workspace --features crdt --no-fail-fast -- --skip basedpyright	main	72da24a	clean (verified git status --porcelain empty)	-5d9105cb / -d4dae4f0; today's occupants e0578039… / 00f06aeb…	red	10b55b8ba8741125 334446
F2	test --workspace --features crdt --no-fail-fast -- --skip basedpyright	mg	~b72843a	UNKNOWN	-5d9105cb / -d4dae4f0 (postclean.log)	red	474f88f0dad581fe 338555
F3	same argv as F2, with a resource sampler running	mg	~b72843a	UNKNOWN	-5d9105cb / -d4dae4f0 (sweep-inst.log)	red	7b8519e7300e8bb3 338555
F4	same argv as F2, with a process-table sampler running	mg	~b72843a	UNKNOWN	-5d9105cb / -d4dae4f0 (sweep-diag.log)	red	5ccdefc5d89eece3 338555
F5	stage 15 of ./scripts/gate --protocol --acceptance bottom_panel_stage1_acceptance --acceptance bottom_panel_stage2a_acceptance --acceptance bottom_panel_stage2b_daemon_acceptance --acceptance bottom_panel_stage2b_gpu_acceptance --acceptance bottom_panel_stage2b_protocol_acceptance --acceptance gui_stage1a_wire_acceptance	mg	5174f73 + uncommitted docs	UNKNOWN	-5d9105cb / -d4dae4f0	red (3 bins: both ctrl_c copies + m6_1_pty_mode_lifecycle)	20260817T172537Z-2375685/15-sweep-crdt.log, sha e5bdc911e366
F6	stage 9 of ./scripts/gate --protocol	mg	724b785 (see below)	UNKNOWN	-5d9105cb / -d4dae4f0	red (2 bins, both ctrl_c copies)	20260816T063330Z-1977433/09-sweep-crdt.log, sha 7a75d999ac4f
F7	stage 9 of ./scripts/gate --protocol	mg	5174f73 (committed 08:45:41, run began 08:45:49)	UNKNOWN	-5d9105cb / -d4dae4f0	red (2 bins, both ctrl_c copies)	20260816T064549Z-2144707/09-sweep-crdt.log, sha 9d3c6ad1bfc9

Supporting, not a reduction: 9b8a01076b44bb7c 98838 (proc-sample.log) is the process-table sampler output behind the retracted "mechanism located" claim.

The red count is 7, not 5. Revision 3 said "F1–F5, red 5/5" while the framing separately cited gate …-2144707, a different physical run the manifest never listed. Both exist, both are red, and there is a third gate run too. F1–F7 above enumerate all seven, each with its own log digest. F5 also has an extra failing binary (m6_1_pty_mode_lifecycle_started_then_exited) that F6/F7 do not.

R2 and R6 are distinct runs. Revision 2's §4 cited gpu3.log for both; that log is R6's three-suite run only, and R2's log was never preserved. R1 likewise has no log. Both are marked accordingly rather than backfilled.

The onset is datable — and this supersedes the reduction matrix

sweep-crdt has 17 log files in this target directory. Counted per test copy, not per stage:

outcome	runs
both copies ... ok	13
neither copy executed — the stage died compiling pmacs (error[E0308]: mismatched types), log 20260815T182846Z-708693	1
both copies FAILED	3 (…-1977433, …-2144707, …-2375685)

Revision 4 said "14 runs, 11 green, 3 red on other tests" and that the earlier reds "failed on unrelated tests". Both were wrong: the count is 13 / 1 / 3, and one of the earlier non-passing runs is a compile failure that never reached either copy, not a red on another test. Of the genuinely red-on-other-tests sweeps, …-2839374 (08-15 09:55) failed protocol and version rows and …-830195 (08-15 18:37) failed composition_overhead_under_ten_percent and a v21/v20 row — those two did execute ctrl_c, and it passed.

So the failure is not long-standing. Last observed green: 20260815T185708Z. First observed red: 20260816T063330Z. The machine was not rebooted across it — the current boot began 08-14 09:30.

But this is not yet a source boundary. Reflog and commit times put HEAD at 7599661 during the last green (3c06176 was committed 40 s after that run finished) and at 724b785 during the first red (5174f73 was committed 08:45:41, after that run ended at 08:42:01 — revision 4's manifest wrongly recorded F6 at 5174f73). Cleanliness was captured for neither, and the tree was being edited throughout. So the window dates a machine/worktree-state transition, not two clean source revisions.

One relationship is worth recording for exactly what it shows: 72da24a is an ancestor of 7599661 (git merge-base --is-ancestor), yet fails today (F1) while 7599661 passed on 08-15. The two observations differ in commit and environment and time, so they are non-comparable and support no causal conclusion of any kind — not even "outcome is not determined by commit alone", since different commits can deterministically produce different outcomes. The pair does not discriminate an environmental change, a source/environment interaction, or a fix before 7599661 followed by a regression before 724b785. And an ancestor outside the interval is irrelevant to whether the interval contains a regression.

D1/D2 — EXECUTED 2026-08-19. The outer invocation is the variable

The causal variable is the OUTER invocation of the test runner, so it is recorded here as a first-class column. Earlier "exact commands" in this file are incomplete for that reason: they gave the inner cargo argv and omitted how the runner itself was started.

Controlled arms, committed head, worktree-local target

Head 77b623c, dirty=0, worktree /home/jeans/Repos/personal/pmacs-probe-sigint, target /home/jeans/build/pmacs-gate-targets/pmacs-probe-sigint-84ed0f9e, TMPDIR=/home/jeans/build/pmacs-gate-targets/tmp/arms.

Inner command, identical in both arms:

cargo test --features crdt --no-fail-fast \
  --test gpu_invocation_acceptance --test gpu_initial_target_acceptance \
  -- ctrl_c_on_launcher_group

The actual evidence-producing outer invocations were:

# fg arm
/home/jeans/build/pmacs-gate-targets/d0a/arms2.sh fg

# bg arm
setsid nohup /home/jeans/build/pmacs-gate-targets/d0a/arms2.sh bg \
  > /dev/null 2>&1 & disown

arms2.sh is machine-local, so naming it is not portable provenance by itself. This is the complete body that produced arms2.tsv; it records the inner cargo exit rather than the status of the disowned outer job:

#!/bin/sh
# D1/D2 controlled arms, v2: full binary SHA-256 captured PER RUN,
# immediately after the run, before anything can rebuild them.
set -u
WT=/home/jeans/Repos/personal/pmacs-probe-sigint
TD=/home/jeans/build/pmacs-gate-targets/pmacs-probe-sigint-84ed0f9e
TMP=/home/jeans/build/pmacs-gate-targets/tmp/arms; mkdir -p "$TMP"
OUT=/home/jeans/build/pmacs-gate-targets/d0a
ARM="$1"; LOG="$OUT/arm2-$ARM.log"
HEAD=$(git -C "$WT" rev-parse HEAD); DIRTY=$(git -C "$WT" status --porcelain | wc -l)
env TMPDIR="$TMP" CARGO_TARGET_DIR="$TD" sh -c \
  "cd $WT && cargo test --features crdt --no-fail-fast --test gpu_invocation_acceptance --test gpu_initial_target_acceptance -- ctrl_c_on_launcher_group" \
  > "$LOG" 2>&1
EXIT=$?
OK=$(grep -c "ctrl_c_on_launcher_group_does_not_reach_spawned_daemon \.\.\. ok" "$LOG")
BAD=$(grep -c "ctrl_c_on_launcher_group_does_not_reach_spawned_daemon \.\.\. FAILED" "$LOG")
SIG=$(grep -m1 -o "SigIgn=[0-9a-f]*" "$LOG" || echo "SigIgn=not-captured")
# Full digests of exactly the binaries this run executed, taken now.
HASHES=""
for b in $(grep -E "Running tests/gpu_" "$LOG" | sed 's|.*deps/||; s|)||'); do
  HASHES="$HASHES $b=$(sha256sum "$TD/debug/deps/$b" | cut -d' ' -f1)"
done
printf '%s\tarm=%s\thead=%s\tdirty=%s\texit=%s\tok=%s\tfailed=%s\t%s\tlogsha=%s\thashes=%s\n' \
  "$(date -Iseconds)" "$ARM" "$(echo $HEAD | cut -c1-7)" "$DIRTY" "$EXIT" "$OK" "$BAD" "$SIG" \
  "$(sha256sum "$LOG" | cut -d' ' -f1)" "$HASHES" >> "$OUT/arms2.tsv"
echo "arm2 $ARM: exit=$EXIT ok=$OK failed=$BAD $SIG"

Result — head 77b623c, dirty=0, digests captured PER RUN

arm	outer	cargo exit	ok	failed	SigIgn	log sha256 (full)
fg	foreground	0	2	0	not captured (no failure ⇒ no dump)	b6117619242f3dabadbe5826f59f11cef451cd09a2beb304e9a3dec1a4616465
bg	setsid nohup … &	101	0	2	0000000000001007	30ac6568e345c485ddf23734a239d71bd06d4a3c2d549f1b4a8942a930527507

Binary digests, full SHA-256, taken immediately after each run before anything could rebuild them — not read later from a reused path:

binary	fg arm	bg arm
gpu_initial_target_acceptance-91f51d0b5303ff9f	0890b78cca22ac1e80b79845f85fb6e88def3330db15ae123a2a672d3084124c	0890b78cca22ac1e80b79845f85fb6e88def3330db15ae123a2a672d3084124c
gpu_invocation_acceptance-6b4b8223dea45247	ef6ff1c15e11062ab53a075763814f32c1bbc9be1b146d068c60e91fa247c696	ef6ff1c15e11062ab53a075763814f32c1bbc9be1b146d068c60e91fa247c696

These are byte-identical, and that claim is now carried by the capture rather than by inference. The earlier arms table recorded only 16-character prefixes at run time and its full values were read afterwards from reused paths — which is exactly the provenance rule §7/D0 states, applied against my own record. Those rows are superseded by the table above. The raw arms.tsv and arms2.tsv remain machine-local; the literal harness and full rows above are their portable transcription.

Disposition — UNRECORDED CORROBORATION, not a controlled arm

This table was read ad hoc from /proc/self/status in the two shells and its runs were not captured: no head, no cleanliness, no log, no digest. It agrees with the arms above and with §4c's capture, and it is labelled separately for that reason — it corroborates, it does not evidence.

context	child SigIgn	SIGINT
foreground	0000000000001000	bit 12 (SIGPIPE) only — deliverable
setsid nohup … &	0000000000000007	SIGHUP, SIGINT, SIGQUIT — ignored

The raw behavioural probe underlying the selected helper (framing §7c) supersedes it as the recorded mechanism check: sh -c 'trap "exit 23" 2; kill -INT $$; exit 0' exits 23 when SIGINT is deliverable and 0 when it is inherited as ignored. Verified in both contexts. It is not itself the remedy because it does not preserve kill failure; §7c specifies the total checked-in helper and its 0/1/2 consumer ABI.

The first D1/D2 capture, and why it is superseded

The capture quoted in framing §4c came from d12.log, which finished 14:10 — five minutes before afe3631 committed the diagnostic code — and ran in the reused d0a-B target directory rather than this worktree's. Its signal facts agree with the arms above, but it is not admissible provenance: uncommitted tree, foreign target. The arms table replaces it, and d12.log is retained only as the first sighting.

Historical foreground/background mapping — RECONSTRUCTED

The claim that "every reduction was foreground and every full sweep was backgrounded" is reconstructed from this session's transcript, not captured at run time. No run before today recorded its outer invocation, because none of the harnesses knew it mattered. It is consistent with every observation and with the two arms above, but it is inference, and rows R1–R10 and F1–F7 carry no outer-invocation field. That gap is the direct cause of nine revisions spent on a confounded matrix.

D0a — EXECUTED 2026-08-19. Verdict: difference NOT captured

Ten runs, counterbalanced A B B A A B B A A B, N = 5 per endpoint, zero voids, zero splits. Endpoints checked out detached and clean in dedicated worktrees (pmacs-d0a-A, pmacs-d0a-B), each with its own target directory, each run performing the gate's build-crdt precondition then the sweep-crdt command. dirty=0 verified per run.

run	endpoint	HEAD	class	ctrl_c ok/failed	red bins	log
A#1	A	7599661	red	0 / 2	3	d0a/A-1.log
B#1	B	724b785	red	0 / 2	2	d0a/B-1.log
B#2	B	724b785	red	0 / 2	2	d0a/B-2.log
A#2	A	7599661	red	0 / 2	4	d0a/A-2.log
A#3	A	7599661	red	0 / 2	3	d0a/A-3.log
B#3	B	724b785	red	0 / 2	2	d0a/B-3.log
B#4	B	724b785	red	0 / 2	2	d0a/B-4.log
A#4	A	7599661	red	0 / 2	3	d0a/A-4.log
A#5	A	7599661	red	0 / 2	3	d0a/A-5.log
B#5	B	724b785	red	0 / 2	2	d0a/B-5.log

Exact commands. Every run, in full. <WT> is /home/jeans/Repos/personal/pmacs-d0a-A (detached at 7599661) or /home/jeans/Repos/personal/pmacs-d0a-B (detached at 724b785); <TD> is /home/jeans/build/pmacs-gate-targets/d0a-A or /home/jeans/build/pmacs-gate-targets/d0a-B correspondingly:

env TMPDIR=/home/jeans/build/pmacs-gate-targets/tmp/d0a \
    CARGO_TARGET_DIR=<TD> \
    sh -c 'cd <WT> \
      && cargo build --workspace --no-default-features --features luajit,crdt \
      && cargo test --workspace --features crdt --no-fail-fast -- --skip basedpyright'

Per-run provenance, transcribed. All runs: exit=101, dirty=0, ok=0 failed=2, suffixes -5d9105cb / -d4dae4f0, /tmp 3 G of 30 G. Times are local 2026-08-19. load is the 1/5/15 average at run start; MemFree/MemAvail in MB; daemons counts live pmacs --daemon:

start	run	class	red bins	load	MemFree	MemAvail	daemons	log sha256/16
12:21:20	A#1	red	3	2.51 2.85 3.57	1549	42069	72	e1c0fe47d55d8f5e
12:26:55	B#1	red	2	7.86 13.48 8.97	9405	42725	76	3105794d515e6ec3
12:32:12	B#2	red	2	8.04 18.28 13.23	9761	43370	80	07a662fb5ca15687
12:35:39	A#2	red	4	11.34 21.23 16.20	8933	43281	84	450aacb9d15244c9
12:39:35	A#3	red	3	13.40 26.07 20.45	10628	42989	88	19156bbbc852e2d3
12:43:26	B#3	red	2	8.66 22.18 20.82	8778	43588	92	6f0d768a76ed9cb0
12:47:20	B#4	red	2	17.96 33.10 27.07	10403	43617	96	75a043a3d5568598
12:50:49	A#4	red	3	10.99 27.07 26.52	10702	43335	100	c1b6d88c08764d9a
12:54:47	A#5	red	3	9.75 28.50 28.70	8494	43053	104	2ae21a3f53fc1a1a
12:58:38	B#5	red	2	11.43 26.69 28.97	8562	43122	108	82c5baa0c7e49e37

Two defects in the previous transcription of this table, recorded rather than silently fixed. Every digest had lost its leading hex character — A#1 read 1c0fe47d55d8f5e… where the value is e1c0fe47d55d8f5e — because the extraction started one byte late in logsha=<value>. And /tmp and MemAvailable were captured by the harness but dropped from the table. A transcription that silently corrupts its own digests is worse than a pointer to the raw file, since it looks verifiable and is not.

uptime was NOT captured, and is UNKNOWN for all ten runs. §7's condition list names uptime; the harness recorded only the load averages from it and discarded the elapsed time. The classifications stand — none of them depends on it — but the condition list was not fully satisfied, and D1/D2's harness must capture it. Recorded rather than quietly treated as met.

Note the leaked-daemon count climbing 72 → 108, four per run. Recorded, not implicated: it rises monotonically while every run classifies the same. Raw logs stay machine-local at /home/jeans/build/pmacs-gate-targets/d0a/; the table above is the portable record.

Endpoint verdicts: A uniform-red, B uniform-red. By the approved table this is the both endpoints uniform the same way row:

the difference is not captured by those two commits under current conditions, and the question becomes what else changed across the window.

What this settles

• The two commits do not discriminate under current conditions. 7599661 passed inside sweep-crdt on 08-15 and now fails 5/5 clean. No bisect of 7599661..724b785 is justified under current conditions, and none will be run.
• That is the whole of the causal claim. An earlier wording here said "the source hypothesis is eliminated" and that "the interval cannot contain the transition"; both are withdrawn. Uniform-red today is silent about what was true on 08-15 — a historical source regression could be masked by a later environmental effect, or by a source/environment interaction that makes both commits fail now. Not discriminating is not the same as not differing.
• The onset window is deprioritised, not excluded. It remains a true observation, and it remains possible that source matters within it; what is established is only that source cannot be probed by this comparison, now.
• A reliable reproduction now exists. 10/10 today, on two different commits, at ~4 minutes per run. This is the most useful thing D0a produced: the mechanism diagnostics D1/D2 no longer depend on a rare event, and can proceed immediately.
• A's three extra failures are recorded, not swept up: a54_real_daemon_real_pty_and_headless_gpu_render_one_panel_hosted_terminal, one_daemon_serves_a_v21_panel_session_and_a_shipped_v20_client, and m6_1_pty_mode_lifecycle_started_then_exited. The v21/v20 row is expected to differ at that older commit; the other two are process/PTY-spawn rows, the same family as the target. They do not affect classification, which reads only the two target copies.

What it does not settle

Nothing about the mechanism. "What else changed across the window" has one cheap negative result so far: no package activity in the window (/var/log/pacman.log shows nothing between 08-15 19:57 and 08-16 06:33; nearest is 08-18). The 1.88 rust toolchain directory has mtime 08-15 22:39, inside the window, but the gate builds with 1.95.0. Neither is pursued further, because with a reliable reproduction in hand direct measurement (D1/D2) dominates archaeology.

D0 — re-run the matrix with captured provenance

Before any §4 row is relied on for a conclusion, re-run the reductions under a harness that records, per run and at the time: exact argv and environment, worktree, git rev-parse HEAD, git status --porcelain emptiness, the artifact hashes actually executed, the result, and the log digest. Two constraints learned the hard way:

• run them at main, not on a feature branch — R1–R10 ran in the panel-mapping-generation worktree, which carries §5b changes;

• record the artifact hash per run at run time, since command shape changes it — the reason R9's result did not mean what it appeared to mean — and since a hash computed later reflects only what occupies that path now;

• first, reproduce the two candidate endpoints CLEANLY — 7599661 (last observed green) and 724b785 (first observed red) — each checked out clean, each in its own isolated target directory. A decision procedure with no predicted outcome, and not decided by one run per endpoint. The framing's §7 D0a holds the governing contract — the total run classifier (green / red / split / void), the void budget, the endpoint table and the bisect-step policy. In summary, keeping the two conclusions with the verdicts they actually belong to:

  • expected-direction clean split (7599661 uniform green, 724b785 uniform red) → a bisect of 7599661..724b785 is permitted;
  • inverted clean split (7599661 uniform red, 724b785 uniform green) → the commits differ, but the observed direction contradicts the onset reading; record it and re-examine that reading before any bisect;
  • mixed at either endpoint → the failure is intermittent under fixed source; no bisect;
  • both endpoints uniform the same way, green or red → the difference is not captured by those two commits under current conditions, and the question becomes what else changed across the window.

  Revision 8 attached "the difference is not captured" to the mixed clause. That was wrong — mixed means intermittency, not absence of a difference — and revision 9 corrected it in the framing but left this file untouched, because the edit's anchor silently missed.