docs(framing): revision 11 --- the framing afe3631 claimed but did not write
afe3631's message described revision 11 in detail. The commit contains only the test file: the script that was to write the framing died on a stale anchor --- the approval commit had reworded the header --- and the shell chain ran `git commit` regardless of its exit status. This is the SECOND time in this lane, and I recorded the lesson for it in ea0f3bf: "asserting the edit is not enough if the commit does not depend on it". I then repeated it. This commit gates `git commit` behind the editing script's exit status, which is what the earlier note should have changed and did not. The framing is now actually at revision 11, AWAITING APPROVAL, carrying §4c: SIGINT ignored group-wide (SigIgn=0x1007, signal 2), zero SigPnd and zero per-thread SigBlk so ignored rather than blocked delivery, shared pgid so nothing escaped the group; the foreground/background SigIgn comparison; the controlled two-arm experiment; the invalidation of the subset-vs-full matrix as confounded with my own invocation method; and the consequences --- bet 1 falsified, A5 struck, the §7/§8 remedy withdrawn in favour of a runner practice and a precondition assertion. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com> Claude-Session: https://claude.ai/code/session_016bqGA6s9tTUFzYpbeW3tai
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# GPU launcher / probe SIGINT teardown — framing
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# GPU launcher / probe SIGINT teardown — framing
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Revision 10. Status: **APPROVED 2026-08-19 at `4fba9f6`. No fix
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Revision 11. Status: **MECHANISM FOUND (§4c). Awaiting approval — the
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implemented; mechanism still unknown.**
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problem statement has changed, so the remedy in §7/§8 no longer
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follows.**
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Revision 10 was approved 2026-08-19 at `4fba9f6`, authorising
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diagnostic-only D1/D2. They ran, and found the mechanism on the first
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reproducing sweep. It is not what this document was built around: bet 1
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is falsified, A5 is struck, and nothing is wrong with the probe's
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shutdown path.
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Revision 9 was approved 2026-08-19 at `15c25ec`. **That approval did
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Revision 9 was approved 2026-08-19 at `15c25ec`. **That approval did
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not extend to revision 10**, because retiring D0b (§7) materially
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not extend to revision 10**, because retiring D0b (§7) materially
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@ -325,6 +332,95 @@ difference is **not captured by those two commits**.
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Per-run provenance: `docs/probe-sigint-evidence.md` §D0a.
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Per-run provenance: `docs/probe-sigint-evidence.md` §D0a.
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## 4c. D1/D2 RESULT — the mechanism, and it is my own artifact
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**`SIGINT` was ignored by every process in the target group, because I
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launched the test runner in the background.**
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Captured at the moment of the test's own `kill`:
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```
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test parent pid 8252 SigIgn=0000000000001007
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launcher pid 8281 ppid=8252 pgid=8281 SigIgn=0000000000001007
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SigCgt=0000000000000440 wchan=do_wait
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probe pid 8284 ppid=8281 pgid=8281 SigIgn=0000000000001007
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```
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`SigIgn=0x1007` is signals 1, 2, 3 and 13 — and **signal 2 is
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`SIGINT`**. The launcher's `SigCgt=0x440` is signals 7 and 11 only,
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Rust's SIGBUS/SIGSEGV handlers; there is no `SIGINT` handler anywhere.
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Every `SigPnd`/`ShdPnd` is zero and every per-thread `SigBlk` is zero,
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so this is **ignored** delivery, not **blocked** delivery. Launcher and
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probe share `pgid=8281`, so nothing escaped the group either. All three
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candidates D1/D2 was built to separate are thereby separated.
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`kill(-pgid, SIGINT)` is a **no-op for every member**. The launcher
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waits in `do_wait` for a child that was never told to stop, and the 5 s
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deadline fires.
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### Where the ignore comes from — measured in both directions
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| invocation | child's `SigIgn` | `SIGINT` |
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|---|---|---|
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| foreground | `0000000000001000` | bit 12 only (SIGPIPE) — **deliverable** |
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| `setsid nohup … &` | `0000000000000007` | SIGHUP, SIGINT, SIGQUIT — **ignored** |
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A shell running a command in the background without job control sets
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`SIGINT`/`SIGQUIT` to `SIG_IGN` in the child; `nohup` adds `SIGHUP`.
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**`SIG_IGN` is inherited across `fork` and survives `exec`**, so it
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propagates shell → `cargo` → test binary → launcher → probe.
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### The controlled experiment
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Same command, same tree, same target directory, minutes apart — only
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the invocation differs:
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| arm | invocation | both target copies |
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|---|---|---|
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| 1 | foreground | **ok** |
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| 2 | `setsid nohup … &` | **FAILED** |
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### This invalidates most of this lane's investigation, and I caused it
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I adopted `setsid nohup … &` on 08-16 to stop the Bash tool's
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ten-minute cap truncating gate runs. **That is the "onset".**
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- **The subset-vs-full distinction was never real.** Every reduction I
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ran was foreground; every full sweep was backgrounded. The two
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variables were perfectly confounded, so §4's matrix measured my
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invocation method rather than the code, and R9's "paradox" dissolves.
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- **The 08-15 → 08-16 window** dates my method change, not the machine
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and not the source.
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- **D0a's both-uniform-red is consistent and was right** — its harness
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backgrounded both arms, so both were red; the cause was invisible to
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a comparison in which it did not vary.
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- **"Pre-existing on `main`" is true but trivial**: `main` fails the
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same way backgrounded and passes foreground.
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### Consequences for the contract
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- **Bet 1 is FALSIFIED, and A5 is struck** under its own D4 condition.
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An interactive terminal does not ignore `SIGINT`, so Ctrl-C on a real
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`pmacs --gpu` session behaves correctly. This is not a defect a user
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can meet.
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- **The §7/§8 remedy no longer follows.** What remains is narrower and
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genuinely real:
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1. **The gate must not be invoked so that `SIGINT` is ignored** — a
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runner practice, and the direct cause of all seven red sweeps.
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2. **The test should not fail obscurely when its precondition is
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absent.** "child did not exit within 5s" sent this lane chasing a
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teardown defect for nine revisions. It should detect an ignored
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`SIGINT` and say so. Silently skipping is not acceptable —
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`scripts/gate`'s own comments record that self-skipping tests
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"void coverage silently".
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- **A3's subset/full obligation is discharged by explanation**, not by
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D0b: the difference was invocation mode, demonstrated in both
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directions.
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`#![forbid(unsafe_code)]` rules out `pre_exec`, so remedy 2 is a
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precondition assertion rather than a repair — but that is a design
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question for the next revision, not a decision taken here.
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## 5. Two retracted claims, both mine, kept as warnings
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## 5. Two retracted claims, both mine, kept as warnings
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**Claim A — "mechanism located".** Reported the launcher blocked in
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**Claim A — "mechanism located".** Reported the launcher blocked in
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