diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..311502b
--- /dev/null
+++ b/Makefile
@@ -0,0 +1,8 @@
+IDRIC_SMS_REQUEST ?= idric-sms-request
+
+.PHONY: test
+
+test:
+	sh -n services/sms/idric_sms_service.sh
+	sh -n tests/sms_service_test.sh
+	IDRIC_SMS_REQUEST="$(IDRIC_SMS_REQUEST)" sh tests/sms_service_test.sh
diff --git a/README.md b/README.md
index 43cec6a..be4cf98 100644
--- a/README.md
+++ b/README.md
@@ -15,3 +15,10 @@ git clone --recurse-submodules https://github.com/isomorphisms/grease.git
 ```
 
 Keeping the Oils-derived tree as a pinned submodule avoids copying the full upstream repository while giving Grease one stable, reproducible source location for CI and local builds.
+
+## Service glue
+
+Filesystem-oriented service runners live under `services/`.  The first one is
+the [inspectable SMS service](services/sms/README.md): deterministic Idriç
+request parsing, durable one-time reminders, explicit consent provenance,
+`CANCEL`/`STOP`, and a fake outbox.
diff --git a/services/sms/README.md b/services/sms/README.md
new file mode 100644
index 0000000..c956947
--- /dev/null
+++ b/services/sms/README.md
@@ -0,0 +1,59 @@
+# Inspectable SMS service state
+
+This is the first filesystem service runner for `Network.SMS` in Idric-Net.  It
+uses the compiled `idric-sms-request` program for deterministic request parsing
+and a fake outbox for transport.  It does not contain a language model or a
+provider API.
+
+The first runner uses UTC deliberately.  A transport supplies a trusted
+telephone address, receive time, and unique inbound message id:
+
+```sh
+idric_sms_service.sh init ./state
+idric_sms_service.sh inbound ./state +15550000001 \
+  2026-09-01T14:00:00Z in_000001 'REMIND 15:00'
+idric_sms_service.sh run_due ./state 2026-09-01T15:00:00Z
+```
+
+The receipt is:
+
+```text
+scheduled evt_in_000001 2026-09-01T15:00:00Z
+sent evt_in_000001
+```
+
+and `state/fake_outbox/fake_evt_in_000001/body` contains `hey`.
+
+## State transitions
+
+```text
+inbound/<inbound-id>/             trusted envelope plus original body
+addresses/<telephone-address>     address-to-principal lookup
+principals/<principal-id>/        unprivileged correspondent and addresses
+consent/<event-id>/               exact authorization provenance
+scheduled/<instant>/<event-id>/   durable pending event
+sent/<event-id>/                  event moved here after fake delivery
+cancelled/<event-id>/             event moved here by CANCEL or STOP
+fake_outbox/<receipt>/             inspectable provider-independent delivery
+opt_out/<principal-id>             durable STOP state
+```
+
+Creating a reminder creates directories and small ordinary files.  Firing or
+cancelling it is an atomic `mv` out of `scheduled/`.  `STOP` creates an opt-out
+marker and moves every pending event for that principal to `cancelled/`.
+Possession of an address record never grants blanket permission: every outbound
+event names one record under `consent/`, including the principal, destination,
+request time, inbound id, original request, scheduled time, and message.
+
+The unknown-caller path creates a `public_correspondent`, not a Unix account and
+not a privileged Idriç principal.  An explicit later enrollment mechanism may
+promote or link principals without treating a telephone number as permanent
+identity.
+
+## Boundary
+
+The Grease runner owns filesystem transitions and invocation.  Idric-Net owns
+telephone, principal, message, request, authorization, and transport meanings.
+The fake outbox is permanent diagnostic infrastructure.  A future provider,
+GSM-modem, or Android adapter should consume the same outbound event rather than
+changing the scheduler's state model.
diff --git a/services/sms/idric_sms_service.sh b/services/sms/idric_sms_service.sh
new file mode 100755
index 0000000..706cbf0
--- /dev/null
+++ b/services/sms/idric_sms_service.sh
@@ -0,0 +1,371 @@
+#!/bin/sh
+
+set -eu
+
+program_name=${0##*/}
+
+die() {
+  printf '%s: %s\n' "$program_name" "$1" >&2
+  exit 1
+}
+
+usage() {
+  die "usage: $program_name init STATE | inbound STATE FROM RECEIVED_AT INBOUND_ID BODY | run_due STATE NOW"
+}
+
+write_file() {
+  write_destination=$1
+  write_value=$2
+  write_temporary="${write_destination}.tmp.$$"
+  umask 077
+  printf '%s\n' "$write_value" > "$write_temporary"
+  mv "$write_temporary" "$write_destination"
+}
+
+safe_id() {
+  case "$1" in
+    ''|*[!A-Za-z0-9_-]*) return 1 ;;
+    *) return 0 ;;
+  esac
+}
+
+valid_phone() {
+  case "$1" in
+    +*) digits=${1#+} ;;
+    *) return 1 ;;
+  esac
+  case "$digits" in
+    ''|*[!0-9]*) return 1 ;;
+    *) return 0 ;;
+  esac
+}
+
+valid_instant() {
+  case "$1" in
+    ????-??-??T??:??:??Z) ;;
+    *) return 1 ;;
+  esac
+  date -u -d "$1" '+%Y-%m-%dT%H:%M:%SZ' >/dev/null 2>&1
+}
+
+initialize_state() {
+  state=$1
+  umask 077
+  mkdir -p \
+    "$state/addresses" \
+    "$state/principals" \
+    "$state/inbound" \
+    "$state/consent" \
+    "$state/scheduled" \
+    "$state/sent" \
+    "$state/cancelled" \
+    "$state/fake_outbox" \
+    "$state/opt_out" \
+    "$state/counters" \
+    "$state/locks"
+  if [ ! -f "$state/counters/next_principal" ]; then
+    write_file "$state/counters/next_principal" 1
+  fi
+}
+
+acquire_principal_lock() {
+  state=$1
+  attempt=0
+  while ! mkdir "$state/locks/principal" 2>/dev/null; do
+    attempt=$((attempt + 1))
+    [ "$attempt" -lt 50 ] || die "principal allocator remained locked"
+    sleep 0.1
+  done
+}
+
+resolve_principal() {
+  state=$1
+  phone=$2
+  address_record="$state/addresses/$phone"
+  if [ -f "$address_record" ]; then
+    principal=$(sed -n '1p' "$address_record")
+    safe_id "$principal" || die "invalid principal mapping for $phone"
+    printf '%s\n' "$principal"
+    return
+  fi
+
+  acquire_principal_lock "$state"
+  if [ -f "$address_record" ]; then
+    principal=$(sed -n '1p' "$address_record")
+    rmdir "$state/locks/principal"
+    printf '%s\n' "$principal"
+    return
+  fi
+
+  next=$(sed -n '1p' "$state/counters/next_principal")
+  case "$next" in
+    ''|*[!0-9]*)
+      rmdir "$state/locks/principal"
+      die "invalid next principal counter"
+      ;;
+  esac
+  principal=$(printf '%06d' "$next")
+  principal_dir="$state/principals/$principal"
+  mkdir -p "$principal_dir/addresses" "$principal_dir/consent" "$principal_dir/stop"
+  write_file "$principal_dir/kind" public_correspondent
+  write_file "$principal_dir/addresses/phone" "$phone"
+  write_file "$address_record" "$principal"
+  write_file "$state/counters/next_principal" $((next + 1))
+  rmdir "$state/locks/principal"
+  printf '%s\n' "$principal"
+}
+
+record_inbound() {
+  state=$1
+  phone=$2
+  received_at=$3
+  inbound_id=$4
+  body=$5
+  principal=$6
+  final="$state/inbound/$inbound_id"
+  [ ! -e "$final" ] || die "inbound id already exists: $inbound_id"
+  temporary="$state/inbound/.${inbound_id}.tmp.$$"
+  mkdir "$temporary"
+  write_file "$temporary/from" "$phone"
+  write_file "$temporary/received_at" "$received_at"
+  write_file "$temporary/body" "$body"
+  write_file "$temporary/principal" "$principal"
+  mv "$temporary" "$final"
+}
+
+record_authorization() {
+  state=$1
+  event_id=$2
+  principal=$3
+  phone=$4
+  requested_at=$5
+  inbound_id=$6
+  original_request=$7
+  scheduled_for=$8
+  message=$9
+  final="$state/consent/$event_id"
+  [ ! -e "$final" ] || die "authorization already exists: $event_id"
+  temporary="$state/consent/.${event_id}.tmp.$$"
+  mkdir "$temporary"
+  write_file "$temporary/principal" "$principal"
+  write_file "$temporary/destination" "$phone"
+  write_file "$temporary/requested_at" "$requested_at"
+  write_file "$temporary/inbound_id" "$inbound_id"
+  write_file "$temporary/original_request" "$original_request"
+  write_file "$temporary/scheduled_for" "$scheduled_for"
+  write_file "$temporary/message" "$message"
+  mv "$temporary" "$final"
+  : > "$state/principals/$principal/consent/$event_id"
+}
+
+make_event() {
+  destination=$1
+  event_id=$2
+  principal=$3
+  phone=$4
+  message=$5
+  authorization=$6
+  scheduled_for=$7
+  temporary="${destination}/.${event_id}.tmp.$$"
+  final="$destination/$event_id"
+  [ ! -e "$final" ] || die "event already exists: $event_id"
+  mkdir "$temporary"
+  write_file "$temporary/principal" "$principal"
+  write_file "$temporary/destination" "$phone"
+  write_file "$temporary/message" "$message"
+  write_file "$temporary/authorization" "$authorization"
+  write_file "$temporary/scheduled_for" "$scheduled_for"
+  mv "$temporary" "$final"
+}
+
+derive_due() {
+  received_at=$1
+  clock=$2
+  received_epoch=$(date -u -d "$received_at" '+%s') || die "invalid received time: $received_at"
+  received_date=${received_at%%T*}
+  candidate="${received_date}T${clock}:00Z"
+  candidate_epoch=$(date -u -d "$candidate" '+%s') || die "invalid reminder time: $clock"
+  if [ "$candidate_epoch" -le "$received_epoch" ]; then
+    next_date=$(date -u -d "$received_date + 1 day" '+%Y-%m-%d') || die "could not advance reminder date"
+    candidate="${next_date}T${clock}:00Z"
+  fi
+  printf '%s\n' "$candidate"
+}
+
+fake_deliver() {
+  state=$1
+  event_dir=$2
+  sent_at=$3
+  event_id=${event_dir##*/}
+  receipt="fake_$event_id"
+  outbox="$state/fake_outbox/$receipt"
+  [ ! -e "$outbox" ] || die "fake receipt already exists: $receipt"
+  mkdir "$outbox"
+  write_file "$outbox/event_id" "$event_id"
+  write_file "$outbox/to" "$(sed -n '1p' "$event_dir/destination")"
+  write_file "$outbox/body" "$(sed -n '1p' "$event_dir/message")"
+  write_file "$outbox/sent_at" "$sent_at"
+  write_file "$event_dir/transport" fake
+  write_file "$event_dir/transport_receipt" "$receipt"
+  write_file "$event_dir/sent_at" "$sent_at"
+  mv "$event_dir" "$state/sent/$event_id"
+}
+
+cancel_event() {
+  state=$1
+  principal=$2
+  event_id=$3
+  cancelled_at=$4
+  cancellation_inbound=$5
+  reason=$6
+  found=
+  for candidate in "$state"/scheduled/*/"$event_id"; do
+    [ -d "$candidate" ] || continue
+    event_principal=$(sed -n '1p' "$candidate/principal")
+    [ "$event_principal" = "$principal" ] || die "event is not owned by this principal: $event_id"
+    write_file "$candidate/cancelled_at" "$cancelled_at"
+    write_file "$candidate/cancellation_inbound_id" "$cancellation_inbound"
+    write_file "$candidate/cancellation_reason" "$reason"
+    mv "$candidate" "$state/cancelled/$event_id"
+    due_dir=${candidate%/*}
+    rmdir "$due_dir" 2>/dev/null || true
+    found=yes
+    break
+  done
+  [ -n "$found" ] || die "scheduled event not found: $event_id"
+}
+
+handle_echo() {
+  state=$1
+  principal=$2
+  phone=$3
+  received_at=$4
+  inbound_id=$5
+  original=$6
+  message=$7
+  [ ! -e "$state/opt_out/$principal" ] || die "principal has opted out"
+  event_id="echo_$inbound_id"
+  record_authorization "$state" "$event_id" "$principal" "$phone" "$received_at" "$inbound_id" "$original" immediate "$message"
+  make_event "$state/scheduled" "$event_id" "$principal" "$phone" "$message" "consent/$event_id" immediate
+  fake_deliver "$state" "$state/scheduled/$event_id" "$received_at"
+  printf 'echoed %s\n' "$event_id"
+}
+
+handle_remind() {
+  state=$1
+  principal=$2
+  phone=$3
+  received_at=$4
+  inbound_id=$5
+  original=$6
+  clock=$7
+  [ ! -e "$state/opt_out/$principal" ] || die "principal has opted out"
+  event_id="evt_$inbound_id"
+  due=$(derive_due "$received_at" "$clock")
+  due_dir="$state/scheduled/$due"
+  mkdir -p "$due_dir"
+  record_authorization "$state" "$event_id" "$principal" "$phone" "$received_at" "$inbound_id" "$original" "$due" hey
+  make_event "$due_dir" "$event_id" "$principal" "$phone" hey "consent/$event_id" "$due"
+  printf 'scheduled %s %s\n' "$event_id" "$due"
+}
+
+handle_stop() {
+  state=$1
+  principal=$2
+  received_at=$3
+  inbound_id=$4
+  : > "$state/opt_out/$principal"
+  stop_dir="$state/principals/$principal/stop/$inbound_id"
+  mkdir "$stop_dir"
+  write_file "$stop_dir/requested_at" "$received_at"
+  cancelled=0
+  for candidate in "$state"/scheduled/*/*; do
+    [ -d "$candidate" ] || continue
+    event_principal=$(sed -n '1p' "$candidate/principal")
+    [ "$event_principal" = "$principal" ] || continue
+    event_id=${candidate##*/}
+    cancel_event "$state" "$principal" "$event_id" "$received_at" "$inbound_id" STOP
+    cancelled=$((cancelled + 1))
+  done
+  printf 'stopped %s cancelled=%s\n' "$principal" "$cancelled"
+}
+
+handle_inbound() {
+  [ "$#" -eq 5 ] || usage
+  state=$1
+  phone=$2
+  received_at=$3
+  inbound_id=$4
+  body=$5
+  valid_phone "$phone" || die "telephone address must be '+' followed by digits"
+  valid_instant "$received_at" || die "received time must be UTC YYYY-MM-DDTHH:MM:SSZ"
+  safe_id "$inbound_id" || die "inbound id may contain only letters, digits, '-' or '_'"
+  initialize_state "$state"
+  principal=$(resolve_principal "$state" "$phone")
+  record_inbound "$state" "$phone" "$received_at" "$inbound_id" "$body" "$principal"
+
+  parser=${IDRIC_SMS_REQUEST:-idric-sms-request}
+  if ! normalized=$($parser "$body"); then
+    printf '%s\n' "$normalized" >&2
+    exit 1
+  fi
+
+  case "$normalized" in
+    'ECHO '*)
+      message=${normalized#ECHO }
+      handle_echo "$state" "$principal" "$phone" "$received_at" "$inbound_id" "$body" "$message"
+      ;;
+    'REMIND '*)
+      clock=${normalized#REMIND }
+      handle_remind "$state" "$principal" "$phone" "$received_at" "$inbound_id" "$body" "$clock"
+      ;;
+    'CANCEL '*)
+      event_id=${normalized#CANCEL }
+      cancel_event "$state" "$principal" "$event_id" "$received_at" "$inbound_id" CANCEL
+      printf 'cancelled %s\n' "$event_id"
+      ;;
+    STOP)
+      handle_stop "$state" "$principal" "$received_at" "$inbound_id"
+      ;;
+    *) die "Idriç parser returned an unknown request" ;;
+  esac
+}
+
+run_due() {
+  [ "$#" -eq 2 ] || usage
+  state=$1
+  now=$2
+  valid_instant "$now" || die "run time must be UTC YYYY-MM-DDTHH:MM:SSZ"
+  initialize_state "$state"
+  for event_dir in "$state"/scheduled/*/*; do
+    [ -d "$event_dir" ] || continue
+    due_dir=${event_dir%/*}
+    due=${due_dir##*/}
+    [ "$due" \> "$now" ] || {
+      event_id=${event_dir##*/}
+      principal=$(sed -n '1p' "$event_dir/principal")
+      if [ -e "$state/opt_out/$principal" ]; then
+        cancel_event "$state" "$principal" "$event_id" "$now" scheduler STOP
+        printf 'cancelled %s opted_out\n' "$event_id"
+      else
+        fake_deliver "$state" "$event_dir" "$now"
+        rmdir "$due_dir" 2>/dev/null || true
+        printf 'sent %s\n' "$event_id"
+      fi
+    }
+  done
+}
+
+[ "$#" -ge 1 ] || usage
+command=$1
+shift
+
+case "$command" in
+  init)
+    [ "$#" -eq 1 ] || usage
+    initialize_state "$1"
+    ;;
+  inbound) handle_inbound "$@" ;;
+  run_due) run_due "$@" ;;
+  *) usage ;;
+esac
diff --git a/tests/sms_service_test.sh b/tests/sms_service_test.sh
new file mode 100755
index 0000000..8b4e90e
--- /dev/null
+++ b/tests/sms_service_test.sh
@@ -0,0 +1,101 @@
+#!/bin/sh
+
+set -eu
+
+service=${SMS_SERVICE:-./services/sms/idric_sms_service.sh}
+parser=${IDRIC_SMS_REQUEST:-idric-sms-request}
+test_root=$(mktemp -d)
+state="$test_root/state"
+
+cleanup() {
+  case "$test_root" in
+    /tmp/*) rm -rf -- "$test_root" ;;
+  esac
+}
+trap cleanup EXIT HUP INT TERM
+
+fail() {
+  printf 'FAIL %s\n' "$1" >&2
+  exit 1
+}
+
+assert_file() {
+  [ -f "$1" ] || fail "missing $1"
+}
+
+assert_value() {
+  actual=$(sed -n '1p' "$1")
+  [ "$actual" = "$2" ] || fail "$1: expected '$2', got '$actual'"
+}
+
+run_service() {
+  IDRIC_SMS_REQUEST="$parser" "$service" "$@"
+}
+
+run_service init "$state"
+
+imani=$(run_service inbound "$state" +15550000001 2026-09-01T14:00:00Z in_imani 'REMIND 15:00')
+[ "$imani" = 'scheduled evt_in_imani 2026-09-01T15:00:00Z' ] || fail "Imani schedule receipt"
+assert_value "$state/consent/evt_in_imani/inbound_id" in_imani
+assert_value "$state/consent/evt_in_imani/destination" +15550000001
+assert_value "$state/consent/evt_in_imani/original_request" 'REMIND 15:00'
+assert_value "$state/scheduled/2026-09-01T15:00:00Z/evt_in_imani/message" hey
+
+run_service run_due "$state" 2026-09-01T14:59:59Z >/dev/null
+[ ! -e "$state/fake_outbox/fake_evt_in_imani" ] || fail "Imani reminder fired early"
+
+# This is a separate process invocation: scheduled state survived the restart.
+sent=$(run_service run_due "$state" 2026-09-01T15:00:00Z)
+[ "$sent" = 'sent evt_in_imani' ] || fail "Imani send receipt"
+assert_value "$state/fake_outbox/fake_evt_in_imani/body" hey
+assert_value "$state/fake_outbox/fake_evt_in_imani/to" +15550000001
+assert_file "$state/sent/evt_in_imani/transport_receipt"
+[ ! -e "$state/scheduled/2026-09-01T15:00:00Z/evt_in_imani" ] || fail "sent event remained scheduled"
+printf 'ok   durable REMIND sends hey with consent provenance\n'
+
+felicity=$(run_service inbound "$state" +15550000002 2026-09-01T14:10:00Z in_felicity 'ECHO hey')
+[ "$felicity" = 'echoed echo_in_felicity' ] || fail "Felicity echo receipt"
+assert_value "$state/fake_outbox/fake_echo_in_felicity/body" hey
+assert_value "$state/sent/echo_in_felicity/authorization" consent/echo_in_felicity
+printf 'ok   ECHO crosses inbound and fake outbound boundaries\n'
+
+run_service inbound "$state" +15550000003 2026-09-01T14:00:00Z in_hasan 'REMIND 15:00' >/dev/null
+cancelled=$(run_service inbound "$state" +15550000003 2026-09-01T14:05:00Z in_hasan_cancel 'CANCEL evt_in_hasan')
+[ "$cancelled" = 'cancelled evt_in_hasan' ] || fail "Hasan cancellation receipt"
+assert_file "$state/cancelled/evt_in_hasan/cancelled_at"
+run_service run_due "$state" 2026-09-01T15:00:00Z >/dev/null
+[ ! -e "$state/fake_outbox/fake_evt_in_hasan" ] || fail "cancelled Hasan reminder was sent"
+printf 'ok   CANCEL moves scheduled state and prevents delivery\n'
+
+run_service inbound "$state" +15550000004 2026-09-01T14:00:00Z in_armani 'REMIND 16:00' >/dev/null
+stopped=$(run_service inbound "$state" +15550000004 2026-09-01T14:01:00Z in_armani_stop STOP)
+case "$stopped" in
+  'stopped '*"cancelled=1") ;;
+  *) fail "Armani STOP receipt" ;;
+esac
+assert_file "$state/opt_out/$(sed -n '1p' "$state/addresses/+15550000004")"
+assert_file "$state/cancelled/evt_in_armani/cancellation_reason"
+if run_service inbound "$state" +15550000004 2026-09-01T14:02:00Z in_armani_again 'REMIND 16:00' >/dev/null 2>&1; then
+  fail "opted-out principal scheduled another message"
+fi
+printf 'ok   STOP is durable and cancels outstanding reminders\n'
+
+run_service inbound "$state" +15550000005 2026-09-01T14:00:00Z in_gina 'REMIND 17:00' >/dev/null
+run_service inbound "$state" +15550000006 2026-09-01T14:00:00Z in_moe 'REMIND 17:00' >/dev/null
+assert_file "$state/scheduled/2026-09-01T17:00:00Z/evt_in_gina/message"
+assert_file "$state/scheduled/2026-09-01T17:00:00Z/evt_in_moe/message"
+run_service run_due "$state" 2026-09-01T17:00:00Z >/dev/null
+assert_file "$state/fake_outbox/fake_evt_in_gina/body"
+assert_file "$state/fake_outbox/fake_evt_in_moe/body"
+printf 'ok   same-time reminders remain distinct across principals\n'
+
+run_service inbound "$state" +15550000007 2026-09-01T14:00:00Z in_cash 'ECHO hey' >/dev/null
+cash_principal=$(sed -n '1p' "$state/addresses/+15550000007")
+assert_value "$state/principals/$cash_principal/kind" public_correspondent
+printf 'ok   unknown caller becomes an unprivileged correspondent\n'
+
+if run_service inbound "$state" +15550000008 2026-09-01T14:00:00Z in_paul 'remind me at 3' >/dev/null 2>&1; then
+  fail "natural language bypassed deterministic parsing"
+fi
+assert_file "$state/inbound/in_paul/body"
+printf 'ok   rejected natural language causes no scheduled effect\n'