ci: integration finds only its own service containers

The runner's docker daemon is shared, so `--filter name=<job> | head -n1` can
pick another repo's Postgres when two jobs run side by side (Steward run 8358,
Inkwell run 8653). Scope the lookup to this job's own task prefix and require
exactly one match. Done from Inkwell #5313 with the operator's permission; the
recipe is rule 79.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

.forgejo/workflows/ci.yml

@@ -296,8 +296,18 @@ jobs:
           set -eux
           echo "=== container landscape (diagnostic for the name filter) ==="
           docker ps -a --format '{{.ID}} {{.Image}} -> {{.Names}}'
-          PG=$(docker ps --filter "name=integration" --filter "ancestor=pgvector/pgvector:pg17" -q | head -n1)
-          test -n "$PG"
+          # Only THIS job's services. The runner's docker daemon is shared, so another
+          # repo's job can be running beside this one, and a job-name filter matches its
+          # containers too (Steward run 8358 and Inkwell run 8653 each took another repo's
+          # Postgres). act names every container of a task GITEA-ACTIONS-TASK-<n>-...: read
+          # <n> from our own container (its id is in the /etc/hostname bind mount) and
+          # require exactly one match.
+          SELF=$(grep -o '/containers/[0-9a-f]\{64\}/' /proc/self/mountinfo | head -n1 | cut -d/ -f3 || true)
+          SELF=${SELF:-$(hostname)}
+          TASK=$(docker inspect -f '{{.Name}}' "$SELF" | grep -o 'GITEA-ACTIONS-TASK-[0-9]*-')
+          test -n "$TASK"
+          PG=$(docker ps --filter "name=$TASK" --filter "ancestor=pgvector/pgvector:pg17" -q)
+          test "$(printf '%s\n' "$PG" | grep -c .)" -eq 1
           PG_IP=$(docker inspect -f '{{range .NetworkSettings.Networks}}{{.IPAddress}}{{end}}' "$PG")
           test -n "$PG_IP"
           export DATABASE_URL="postgresql+asyncpg://scribe:ci_integration@${PG_IP}:5432/scribe_test"