docs(lane): the R9 conclusions were still here, and the onset is datable

779a6bd corrected four claims but left the ones that mattered most. This
ledger still said --workspace unification was refuted, that R9 ran the
"same binaries, same order, same tests", that later packages cannot be
implicated, and that the cause is cumulative across the preceding 37
binaries. All four are withdrawn:

  - R9 executed gpu_initial_target_acceptance-91f51d0b and
    gpu_invocation_acceptance-6b4b8223; the sweeps executed -5d9105cb
    and -d4dae4f0, byte-different. Command shape changes Cargo's
    fingerprint, so the comparison was never made. --workspace
    selection and the preceding tests are both OPEN, not refuted.
  - "Later packages cannot be implicated because their targets run
    after the failure" ignores that they affect the build graph and
    fingerprints before their tests execute.
  - No cumulative cause follows from reductions that ran different
    binaries. What is established is narrower: reproducible in the full
    sweep, not reproduced in any subset attempted.

And a finding that reframes the defect. sweep-crdt appears SEVENTEEN
times in this target dir's gate logs. The ctrl_c failure appears in
exactly the last three, and the test passed --- both copies, "... ok" ---
inside the stage before them. Last green 20260815T185708Z, first red
20260816T063330Z, no reboot between; the three earlier red sweeps failed
on unrelated rows. "Pre-existing on main" still holds, since 72da24a
reproduces it, but "always broken" is contradicted, and bisecting that
window is now the sharpest lead. The red full-sweep count is SEVEN, not
five, each enumerated with its own log digest in the teardown lane's
docs/probe-sigint-evidence.md.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai

docs/active-work.md

@@ -482,6 +482,17 @@ from #171 and #215.
     and `:3131`). **This branch is not implicated**, and no branch can
     pass this gate stage on this machine until the underlying defect is
     fixed.
+  - **THE ONSET IS DATABLE.** `sweep-crdt` appears 17 times in this
+    target dir's gate logs; the `ctrl_c` failure appears in exactly the
+    **last three**, and the test passed — both copies — inside the
+    stage before them. Last green `20260815T185708Z`, first red
+    `20260816T063330Z`, no reboot between. The three earlier red
+    sweeps failed on unrelated rows. So "pre-existing on `main`" holds,
+    but **"always broken" is contradicted**, and bisecting that window
+    is the sharpest available lead.
+  - **The red full-sweep count is SEVEN**, not five; each run is
+    enumerated with its own log digest in the teardown lane's
+    `docs/probe-sigint-evidence.md`.
   - **The defect now has its own lane:
     `gpu-probe-sigint-teardown`** (pushed; framing revision 3 at
     `docs/gpu-probe-sigint-framing.md`, run provenance at
@@ -526,25 +537,39 @@ from #171 and #215.
       pages are NOT reclaimable yet still appear in `buff/cache` — so
       the hypothesis deserved the experiment it eventually got.
     - *inotify exhaustion*: refuted. 47 instances in use of 1024.
-    - *`--workspace` feature unification*: refuted. The same two
-      targets under `--workspace` are green.
-    - *A specific preceding test*: refuted, and this is the strange
-      one. **All 37 targets that precede it, plus the suite, run
-      green** — same binaries, same order, same tests. Only the
-      complete 119-target sweep reproduces it. Other packages'
-      targets run later still (log lines 4848+), after the failure at
-      3066, so they cannot be implicated either.
+    - *`--workspace` artifact selection*: **NOT refuted.** Two targets
+      under `--workspace` are green, and the preceding targets without
+      `--workspace` are green, but neither run isolates the factor —
+      see below.
+    - *A specific preceding test*: **NOT refuted, and the earlier entry
+      here was wrong.** It claimed all 37 preceding targets plus the
+      suite run green "same binaries, same order, same tests". The
+      binaries were **not** the same: that run executed
+      `gpu_initial_target_acceptance-91f51d0b` and
+      `gpu_invocation_acceptance-6b4b8223`, while the failing sweeps
+      executed `-5d9105cb` and `-d4dae4f0`, which are byte-different.
+      Cargo's target selection changes the fingerprint, so command
+      shape changes the executable. The comparison was never made.
+    - Also withdrawn: that other packages "cannot be implicated"
+      because their targets run after the failure. Later-selected
+      packages can affect Cargo's build graph and fingerprints
+      **before** their tests execute.
+    - Also withdrawn: that the cause is "cumulative across the
+      preceding 37 binaries". Nothing established that.
     - Note the test exists in **two** binaries: `tests/gpu_initial_
       target_acceptance.rs` includes it as a module, so a reproducing
       sweep fails it twice, at log lines 3083 and 3117.
-  - **What the bisect DID establish.** Green in every smaller context
-    tried, and deterministic in the largest: the test alone (x3, 0.15s
-    against its 5s deadline); its whole 15-test suite; a
-    workspace-wide run FILTERED to just this test; the lib binary
-    (2145 tests) followed by the suite; and the three GPU suites in
-    sweep order. Red 4/4 in the full workspace sweep, across two
-    different trees. So it is cumulative across the 37 binaries that
-    precede it, and it is **not** flaky.
+  - **What the bisect established, and what it did NOT.** Green in
+    every smaller context tried — the test alone (x3, 0.15s against its
+    5s deadline); its whole 15-test suite; a workspace-wide run
+    FILTERED to just this test; the lib binary (2145 tests) then the
+    suite; the three GPU suites in sweep order — and red in every full
+    workspace sweep, seven of them across two trees.
+    **No cumulative cause follows from that.** The subset runs and the
+    sweeps executed byte-different binaries, so the reductions never
+    made the comparison they appeared to make. What is established is
+    only: reproducible in the full sweep, not reproduced in any subset
+    attempted so far.
   - **`/tmp` is a 30G tmpfs holding 21G**, almost all stale
     `levshell-*-target` cargo directories belonging to an unrelated
     project, 3-4 days old. Recorded as an observation about this