Pin reproducer CCDB queries to the original job's run time

Reproducers resolved CCDB against the present, so any object re-uploaded since
the job ran silently changed the outcome -- e.g. FT0/Calib/EventsPerBc, whose
late arrival flips o2-steer-colcontexttool to the non-uniform sampler and gives
a different collision context at the same fixed seed.

Inject ALICEO2_CCDB_CONDITION_NOT_AFTER, which BasicCCDBManager picks up, so it
covers the anchoring stage as well as the workflow tasks.

Only pin when the moment is actually known: $2 if given, else "now" when run
inside the job itself (the anchorMC.sh path). Otherwise skip and say so -- a
wrong pin is worse than none. Skipped too if the JDL already sets it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: sawenzel

GRID/utils/getReproducerScript.sh

@@ -1,6 +1,30 @@
 #!/bin/bash
 ALIEN_PID=$1
 
+# Epoch-ms the generated reproducer will pin its CCDB queries to (see the
+# INJECTION block below for why). This MUST be the moment the *original* job
+# ran; "now" is only the same thing when this script runs inside that very job.
+#
+#   $2 given                     -> use it verbatim (the escape hatch for
+#                                   regenerating an old job's reproducer)
+#   running inside the job       -> now == the job's start time, correct
+#   otherwise                    -> unknown; do NOT guess, skip the pinning
+#
+# The last case matters: silently pinning to the wrong moment is worse than not
+# pinning at all, because it looks authoritative while reconstructing a CCDB
+# view that never existed for this job.
+NOT_AFTER=$2
+if [ -z "${NOT_AFTER}" ]; then
+  if [ -n "${ALIEN_PROC_ID}" ] && [ "${ALIEN_PROC_ID}" = "${ALIEN_PID}" ]; then
+    NOT_AFTER=$(date +%s%3N)
+  else
+    echo "[getReproducerScript] Not running inside job ${ALIEN_PID} and no start"
+    echo "[getReproducerScript] time given, so CCDB will NOT be pinned: the"
+    echo "[getReproducerScript] reproducer will use present-day conditions."
+    echo "[getReproducerScript] Re-run as: $0 ${ALIEN_PID} <job-start-epoch-ms>"
+  fi
+fi
+
 if [ ${JALIEN_TOKEN_CERT} ]; then
   TOKENCERT=${JALIEN_TOKEN_CERT}
   TOKENKEY=${JALIEN_TOKEN_KEY}
@@ -24,10 +48,33 @@ curl 'https://alimonitor.cern.ch/users/jobenv.jsp?pid='${ALIEN_PID}
   -H 'User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/132.0.0.0 Safari/537.36' \
   --insecure --cert ${TOKENCERT} --key ${TOKENKEY} -o ${SCRIPT}
 
+# If the JDL already declares a CCDB time-machine timestamp, the job pinned
+# itself and that value is restored further down by the MonaLisa env block (and
+# consumed by anchorMC.sh). Injecting our own would fight it, and the JDL's is
+# the authoritative one, so stand down.
+CCDB_PIN_BLOCK=""
+if grep -q "ALIEN_JDL_CCDB_CONDITION_NOT_AFTER" "${SCRIPT}"; then
+  echo "[getReproducerScript] JDL already sets CCDB_CONDITION_NOT_AFTER; keeping it."
+elif [ -n "${NOT_AFTER}" ]; then
+  # Pin every CCDB query to the time the ORIGINAL job ran ("time machine").
+  # Without this the reproducer resolves each object to whatever is newest in
+  # CCDB *today*, so any re-upload since the job ran silently changes the
+  # result -- including the collision context, which is otherwise fully
+  # deterministic given the fixed seed (cf. O2-7093). This reconstructs the
+  # job's CCDB view rather than sharing a declared one, because production jobs
+  # are themselves normally unpinned (o2dpg_sim_workflow.py defaults
+  # --condition-not-after to year 2077).
+  # Unset ALICEO2_CCDB_CONDITION_NOT_AFTER before running to get present-day
+  # conditions instead.
+  CCDB_PIN_BLOCK="export ALICEO2_CCDB_CONDITION_NOT_AFTER=\${ALICEO2_CCDB_CONDITION_NOT_AFTER:-${NOT_AFTER}}"
+  echo "[getReproducerScript] Pinning reproducer CCDB queries to ${NOT_AFTER}."
+fi
+
 # Define the Apptainer injection block which makes sure
 # that the job script is automatically executed in apptainer
 INJECTION='
 export ALIEN_PID=#ALIEN_PID#
+#CCDB_PIN_BLOCK#
 # Check if the script is running inside an Apptainer (Singularity) container
 if [ -z "$APPTAINER_NAME" ] && [ -z "$SINGULARITY_NAME" ]; then
   # Relaunch this script inside the container
@@ -77,4 +124,9 @@ sed -i "/cd alien-job-$ALIEN_PID/d" "$SCRIPT"
 # replace the PID
 sed -i "s/#ALIEN_PID#/${ALIEN_PID}/g" "$SCRIPT"
 
+# substitute the CCDB pinning placeholder (dropping the line entirely when we
+# decided not to pin -- see above)
+awk -v blk="$CCDB_PIN_BLOCK" '$0=="#CCDB_PIN_BLOCK#"{ if (blk!="") print blk; next } 1' \
+  "$SCRIPT" > tmpfile && mv tmpfile "$SCRIPT"
+
 chmod +x "${SCRIPT}"