diff --git a/scripts/two-worker-smoke.sh b/scripts/two-worker-smoke.sh
new file mode 100755
index 0000000..9cb000f
--- /dev/null
+++ b/scripts/two-worker-smoke.sh
@@ -0,0 +1,165 @@
+#!/usr/bin/env bash
+#
+# End-to-end check: two Python workers process separate coordinator shards.
+#
+# Requires Docker, curl, python3, and an installed scimesh-worker (normally
+# from this repository's .venv). The test uses its own Compose project, ports,
+# volumes, and temporary worker directories, leaving a developer stack alone.
+
+set -euo pipefail
+
+ROOT_DIR=$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)
+COORDINATOR_DIR="$ROOT_DIR/coordinator"
+COMPOSE_PROJECT=${COMPOSE_PROJECT:-scimesh-two-worker-smoke}
+COORDINATOR_PORT=${COORDINATOR_PORT:-18081}
+POSTGRES_PORT=${POSTGRES_PORT:-55434}
+HOST="http://127.0.0.1:${COORDINATOR_PORT}"
+TOKEN=${SCIMESH_SMOKE_TOKEN:-two-worker-smoke-token}
+WORK_DIR=$(mktemp -d "${TMPDIR:-/tmp}/scimesh-two-worker-smoke.XXXXXX")
+WORKER_ONE_PID=""
+WORKER_TWO_PID=""
+WORKER_PYTHON=${SCIMESH_WORKER_PYTHON:-"$ROOT_DIR/.venv/bin/python"}
+
+cleanup() {
+    local exit_code=$?
+    if [[ "$exit_code" -ne 0 ]]; then
+        printf '\nTwo-worker smoke failed; worker logs follow.\n' >&2
+        sed -n '1,200p' "$WORK_DIR/worker-a.log" >&2 || true
+        sed -n '1,200p' "$WORK_DIR/worker-b.log" >&2 || true
+        (
+            cd "$COORDINATOR_DIR"
+            POSTGRES_PORT="$POSTGRES_PORT" COORDINATOR_PORT="$COORDINATOR_PORT" \
+                docker compose -p "$COMPOSE_PROJECT" logs coordinator >&2 || true
+        )
+    fi
+    if [[ -n "$WORKER_ONE_PID" ]]; then kill "$WORKER_ONE_PID" 2>/dev/null || true; fi
+    if [[ -n "$WORKER_TWO_PID" ]]; then kill "$WORKER_TWO_PID" 2>/dev/null || true; fi
+    if [[ -n "$WORKER_ONE_PID" ]]; then wait "$WORKER_ONE_PID" 2>/dev/null || true; fi
+    if [[ -n "$WORKER_TWO_PID" ]]; then wait "$WORKER_TWO_PID" 2>/dev/null || true; fi
+    (
+        cd "$COORDINATOR_DIR"
+        POSTGRES_PORT="$POSTGRES_PORT" COORDINATOR_PORT="$COORDINATOR_PORT" \
+            docker compose -p "$COMPOSE_PROJECT" down -v --remove-orphans >/dev/null 2>&1 || true
+    )
+    rm -rf "$WORK_DIR"
+    exit "$exit_code"
+}
+trap cleanup EXIT INT TERM
+
+require() {
+    command -v "$1" >/dev/null || {
+        printf 'missing required command: %s\n' "$1" >&2
+        exit 2
+    }
+}
+
+for command in docker curl python3; do require "$command"; done
+[[ -x "$WORKER_PYTHON" ]] || {
+    printf 'worker Python is not executable: %s\n' "$WORKER_PYTHON" >&2
+    printf 'Set SCIMESH_WORKER_PYTHON to a Python environment with SciMesh and RDKit.\n' >&2
+    exit 2
+}
+
+printf 'Starting isolated coordinator on %s (project %s)\n' "$HOST" "$COMPOSE_PROJECT"
+(
+    cd "$COORDINATOR_DIR"
+    POSTGRES_PORT="$POSTGRES_PORT" COORDINATOR_PORT="$COORDINATOR_PORT" \
+        WORKER_AUTH_TOKEN="$TOKEN" UI_AUTH_TOKEN= \
+        docker compose -p "$COMPOSE_PROJECT" up -d --build
+)
+
+for _ in $(seq 1 45); do
+    if curl -fsS "$HOST/health" >/dev/null; then break; fi
+    sleep 1
+done
+curl -fsS "$HOST/health" >/dev/null || {
+    printf 'coordinator did not become healthy\n' >&2
+    exit 1
+}
+
+start_worker() {
+    local worker_name=$1
+    local worker_dir=$2
+    SCIMESH_COORDINATOR_URL="$HOST" \
+        SCIMESH_BEARER_TOKEN="$TOKEN" \
+        SCIMESH_WORKER_NAME="$worker_name" \
+        SCIMESH_POLL_INTERVAL=0.2 \
+        "$WORKER_PYTHON" -m scimesh.worker.cli --work-dir "$worker_dir" >"$worker_dir.log" 2>&1 &
+    STARTED_WORKER_PID=$!
+}
+
+start_worker two-worker-smoke-a "$WORK_DIR/worker-a"
+WORKER_ONE_PID=$STARTED_WORKER_PID
+start_worker two-worker-smoke-b "$WORK_DIR/worker-b"
+WORKER_TWO_PID=$STARTED_WORKER_PID
+
+for _ in $(seq 1 30); do
+    registered=$(docker compose -p "$COMPOSE_PROJECT" -f "$COORDINATOR_DIR/docker-compose.yml" \
+        exec -T postgres psql -U scimesh -d scimesh -Atc "SELECT count(*) FROM workers")
+    [[ "$registered" == "2" ]] && break
+    sleep 1
+done
+[[ "${registered:-0}" == "2" ]] || {
+    printf 'workers did not register; logs follow\n' >&2
+    sed -n '1,160p' "$WORK_DIR/worker-a.log" >&2 || true
+    sed -n '1,160p' "$WORK_DIR/worker-b.log" >&2 || true
+    exit 1
+}
+
+DATASET="$WORK_DIR/fixture.tsv"
+printf '%s\n' \
+    $'chembl_id\tcanonical_smiles' \
+    $'TEST001\tCC' $'TEST002\tCCC' $'TEST003\tCCCC' $'TEST004\tCCCO' $'TEST005\tCCN' \
+    $'TEST006\tCCCl' $'TEST007\tCCBr' $'TEST008\tCCF' $'TEST009\tCC=O' $'TEST010\tCC#N' \
+    $'TEST011\tCO' $'TEST012\tCOC' $'TEST013\tCOCC' $'TEST014\tCN' $'TEST015\tCNC' \
+    $'TEST016\tO=C=O' $'TEST017\tC1CC1' $'TEST018\tc1ccccc1' $'TEST019\tCC(C)O' $'TEST020\tCC(C)N' \
+    >"$DATASET"
+
+response=$(curl -fsS -H "Authorization: Bearer $TOKEN" -X POST "$HOST/jobs/upload" \
+    -F 'workload=similarity-search' \
+    -F 'parameters={"query_smiles":"CCO","top_k":5,"progress_every":0}' \
+    -F 'chunk_rows=5' \
+    -F 'max_rows=20' \
+    -F "file=@${DATASET};type=text/tab-separated-values")
+job_id=$(printf '%s' "$response" | python3 -c 'import json,sys; print(json.load(sys.stdin)["job_id"])')
+task_count=$(printf '%s' "$response" | python3 -c 'import json,sys; print(json.load(sys.stdin)["task_count"])')
+[[ "$task_count" == "4" ]] || {
+    printf 'expected four shards, got response: %s\n' "$response" >&2
+    exit 1
+}
+
+printf 'Submitted job %s with four shards\n' "$job_id"
+for _ in $(seq 1 90); do
+    job=$(curl -fsS -H "Authorization: Bearer $TOKEN" "$HOST/jobs/$job_id")
+    status=$(printf '%s' "$job" | python3 -c 'import json,sys; print(json.load(sys.stdin)["status"])')
+    [[ "$status" == "completed" || "$status" == "failed" || "$status" == "cancelled" ]] && break
+    sleep 1
+done
+
+printf '%s' "$job" | python3 -c '
+import json, sys
+job = json.load(sys.stdin)
+assert job["status"] == "completed", job
+assert job["total"] == 4, job
+assert job["completed"] == 4, job
+assert job["failed"] == 0, job
+'
+
+task_check=$(docker compose -p "$COMPOSE_PROJECT" -f "$COORDINATOR_DIR/docker-compose.yml" \
+    exec -T postgres psql -U scimesh -d scimesh -Atc \
+    "SELECT count(*) FROM tasks WHERE job_id = '$job_id'::uuid AND status = 'completed' AND attempt = 1 AND result_artifact_id IS NOT NULL")
+[[ "$task_check" == "4" ]] || {
+    printf 'expected four first-attempt tasks with coordinator artifacts, got %s\n' "$task_check" >&2
+    exit 1
+}
+
+worker_one_results=$(find "$WORK_DIR/worker-a" -name result.csv -type f | wc -l | tr -d ' ')
+worker_two_results=$(find "$WORK_DIR/worker-b" -name result.csv -type f | wc -l | tr -d ' ')
+[[ "$worker_one_results" -ge 1 && "$worker_two_results" -ge 1 ]] || {
+    printf 'both workers must process at least one shard (a=%s, b=%s)\n' \
+        "$worker_one_results" "$worker_two_results" >&2
+    exit 1
+}
+
+printf 'PASS: 4/4 shards completed; worker-a=%s, worker-b=%s\n' \
+    "$worker_one_results" "$worker_two_results"