CLI: a closed stdout pipe exits 141 silently (was E_INTERNAL); example avoids head under pipefail

Found by the P10 fresh-VM run: `simurg inspect … | head` raised BrokenPipeError, reported as
an internal error, and stopped examples/gsa_demo.sh (set -o pipefail). run_guarded now flushes
stdout inside the guard and maps BrokenPipeError to ExitCode.SIGPIPE (141) without a message.
p10.sh: SKIP_DOCKER/SKIP_CONDA, clearer digest report; p10t.sh runs build+pip+tutorial only.

examples/gsa_demo.sh

@@ -30,7 +30,7 @@ mkdir -p "$OUT"
 # Optional subset: symlink the first N IDAT pairs into $OUT/idats (same <barcode>/<barcode>_<pos>_<ch>.idat layout).
 if [[ $N -gt 0 ]]; then
   rm -rf "$OUT/idats"
-  find "$IDATS" -name '*_Grn.idat' | sort | head -n "$N" | while read -r g; do
+  find "$IDATS" -name '*_Grn.idat' | sort | sed -n "1,${N}p" | while read -r g; do
     b=$(basename "$(dirname "$g")"); mkdir -p "$OUT/idats/$b"
     ln -s "$(realpath "$g")" "$OUT/idats/$b/"; ln -s "$(realpath "${g%_Grn.idat}_Red.idat")" "$OUT/idats/$b/"
   done
@@ -38,12 +38,12 @@ if [[ $N -gt 0 ]]; then
 fi
 
 echo "== 1. inspect the inputs"
-$SIMURG inspect "$BPM" "$EGT" | head -20
+$SIMURG inspect "$BPM" "$EGT" | sed -n 1,20p   # sed reads to the end: no SIGPIPE under pipefail
 
 echo "== 2. genotype: GTC v5 per sample, sample_summary.tsv, control-probe QC, contamination, relatedness"
 $SIMURG genotype --bpm "$BPM" --egt "$EGT" --csv "$CSV" --idats "$IDATS" --out "$OUT/gtc" \
   --qc-profile genotyping --threads "$THREADS" --force
-column -t -s$'\t' "$OUT/gtc/sample_summary.tsv" | cut -c1-150 | head -8
+column -t -s$'\t' "$OUT/gtc/sample_summary.tsv" | cut -c1-150 | sed -n 1,8p
 
 echo "== 3. HTML QC report + QC table"
 $SIMURG qc report --data "$OUT/gtc" --out "$OUT/qc_report" --output-format both

scripts/cloud/tasks/p10.sh

@@ -56,6 +56,7 @@ for v in fresh pure; do
 done
 
 echo "=== 4a. docker $(date -u +%T) ==="
+if [[ "${SKIP_DOCKER:-0}" != "1" ]]; then
 D=data/p0/gsa_v4_pgx
 BPM=$D/GSA-PGx-48v4-0_20079540_E2_bpm/GSA-PGx-48v4-0_20079540_E2.bpm
 CSV=$D/GSA-PGx-48v4-0_20079540_E2_csv/GSA-PGx-48v4-0_20079540_E2.csv
@@ -75,8 +76,10 @@ if docker build -q -t simurg:test . > $R/docker_build.log 2>&1; then
 else
   step docker_build FAILED; tail -30 $R/docker_build.log
 fi
+fi
 
 echo "=== 4b. conda $(date -u +%T) ==="
+if [[ "${SKIP_CONDA:-0}" != "1" ]]; then
 curl -sSfL -o $W/miniforge.sh "https://github.com/conda-forge/miniforge/releases/latest/download/Miniforge3-Linux-$ARCH.sh" \
   && bash $W/miniforge.sh -b -p $W/conda > /dev/null
 C=$W/conda/bin
@@ -94,6 +97,7 @@ if $C/conda install -y -q -n base conda-build > $R/conda.log 2>&1 \
 else
   step conda_build FAILED; tail -40 $R/conda.log
 fi
+fi
 
 echo "=== 5. digests $(date -u +%T) ==="
 $W/fresh/bin/python - "$R" <<'PY' | tee $R/agreement.txt
@@ -104,10 +108,13 @@ for kind in ("gtc", "vcf"):
     runs = {p.stem.split("_", 2)[2]: json.loads(p.read_text())[kind] for p in sorted(r.glob(f"digest_{kind}_*.json"))}
     if not runs:
         continue
-    ref_name, ref = "fresh", runs.get("fresh", {})
+    ref = runs.get("fresh", {})
+    if not ref:
+        print(f"{kind}: no reference (the pip-installed tutorial produced no outputs)")
+        continue
     for name, d in runs.items():
-        same = d == ref and len(d) > 0
+        if name != "fresh":
-        print(f"{kind}: {name} vs {ref_name}: {'IDENTICAL' if same else 'DIFFERENT'} ({len(d)} files)")
+            print(f"{kind}: {name} vs fresh: {'IDENTICAL' if d == ref else 'DIFFERENT'} ({len(d)} vs {len(ref)} files)")
 PY
 {
   echo "{"; echo "  \"arch\": \"$ARCH\","

scripts/cloud/tasks/p10t.sh

@@ -0,0 +1,3 @@
+#!/bin/bash
+# P10 acceptance without the Docker and conda parts (already verified): build, pip installs, tutorial, digests.
+SKIP_DOCKER=1 SKIP_CONDA=1 bash "$(dirname "$0")/p10.sh" "$@"

src/simurg/cli/main.py

@@ -7,6 +7,7 @@ Later phases add the other commands of CLI-001.
 from __future__ import annotations
 
 import json
+import os
 import sys
 from collections.abc import Callable
 from pathlib import Path
@@ -58,6 +59,11 @@ def run_guarded(reporter: Reporter, fn: Callable[[], int]) -> None:
     code = ExitCode.OK
     try:
         code = ExitCode(fn())
+        sys.stdout.flush()  # surface a closed pipe here, not at interpreter exit
+    except BrokenPipeError:
+        # the consumer of stdout stopped reading (`| head`): silence further writes, exit like a SIGPIPE'd tool
+        os.dup2(os.open(os.devnull, os.O_WRONLY), sys.stdout.fileno())
+        code = ExitCode.SIGPIPE
     except SimurgError as e:
         reporter.error(e.code, e.message + (f"\n  hint: {e.hint}" if e.hint else ""), exc=e, file=e.path)
         code = e.exit_code

src/simurg/core/errors.py

@@ -23,6 +23,7 @@ class ExitCode(IntEnum):
     PARTIAL = 3  # >= 1 sample failed and >= 1 succeeded
     ALL_FAILED = 4  # run completed but no sample succeeded
     SIGINT = 130
+    SIGPIPE = 141  # the reader of stdout went away (e.g. `simurg inspect … | head`); nothing is reported
     SIGTERM = 143
 
 

tests/unit/test_cli_errors.py

@@ -93,3 +93,18 @@ def test_locale_independent_output(tmp_path) -> None:  # type: ignore[no-untyped
         assert r.returncode == 0, r.stderr
         outs.add(r.stdout)
     assert len(outs) == 1
+
+
+def test_closed_stdout_is_not_an_internal_error(tmp_path) -> None:  # type: ignore[no-untyped-def]
+    # `simurg inspect … | head`: the reader goes away; the CLI must exit like a SIGPIPE'd tool (141), silently
+    f = _files(tmp_path)
+    p = subprocess.Popen(
+        [sys.executable, "-m", "simurg.cli.main", "inspect", "--json", str(f["bpm"]), str(f["egt"]), str(f["idat"])],
+        stdout=subprocess.PIPE,
+        stderr=subprocess.PIPE,
+    )
+    assert p.stdout is not None and p.stderr is not None
+    p.stdout.close()  # nobody reads stdout
+    err = p.stderr.read().decode()
+    assert p.wait() == 141, err
+    assert "E_INTERNAL" not in err and "Traceback" not in err and "Exception ignored" not in err