diff --git a/scripts/release.sh b/scripts/release.sh
new file mode 100755
index 00000000..e67c9c0d
--- /dev/null
+++ b/scripts/release.sh
@@ -0,0 +1,149 @@
+#!/usr/bin/env bash
+# Release lifecycle: package, activate, rollback, status.
+#
+#   scripts/release.sh package               build the image for this release
+#   scripts/release.sh activate [--fault-injection]
+#   scripts/release.sh rollback
+#   scripts/release.sh status
+#
+# Activation is health-gated: the M2 task runner executes
+# tasks/hello-marker.json; only an exact-marker pass activates. The
+# pointer (state/active.json) is replaced atomically; every attempt is
+# appended to state/activation-log.jsonl (append-only history).
+#
+# Fault injection exists solely to prove the refusal path in drills.
+set -euo pipefail
+cd "$(dirname "$0")/.."
+# shellcheck source=common.sh
+source scripts/common.sh
+
+load_config
+load_release
+bootstrap_runtime_dir
+
+STATE_DIR="$MOSAIC_DEV_DIR/state"
+mkdir -p "$STATE_DIR"
+POINTER="$STATE_DIR/active.json"
+LOG="$STATE_DIR/activation-log.jsonl"
+
+now() { date -u +%Y-%m-%dT%H:%M:%SZ; }
+
+append_log() { # event release imageTag note
+    local event="$1" release="$2" imageTag="$3" note="${4:-}"
+    printf '{"at":"%s","event":"%s","release":"%s","imageTag":"%s"%s}\n' \
+        "$(now)" "$event" "$release" "$imageTag" \
+        "$(printf '%s' "$note" | node -e 'let d="";process.stdin.on("data",c=>d+=c).on("end",()=>{const s=d.replace(/\n$/,"");process.stdout.write(s ? ",\"note\":"+JSON.stringify(s) : "")})')" \
+        >> "$LOG"
+}
+
+image_exists() { docker image inspect "$1" >/dev/null 2>&1; }
+
+health_check() { # returns 0 only when the marker path passes; $1 = fault injection label or empty
+    local tmp=""
+    local task="tasks/hello-marker.json"
+    if [ -n "${1:-}" ]; then
+        tmp="$(mktemp -d)"
+        # Fault injection: same prompt, deliberately wrong expectation.
+        printf '{"taskVersion":1,"id":"t-health-fault","prompt":"Return your startup marker and nothing else.","expectExact":"MOSAIC_FAULT_%s"}' \
+            "$RANDOM$RANDOM" > "$tmp/fault-task.json"
+        task="$tmp/fault-task.json"
+    fi
+    local rc=0
+    scripts/run-task.sh run "$task" >/dev/null 2>&1 || rc=$?
+    [ -n "$tmp" ] && rm -rf "$tmp"
+    return "$rc"
+}
+
+activate() { # $1 = release, $2 = imageTag, $3 = event name, $4 = fault label
+    local release="$1" imageTag="$2" event="$3" fault="${4:-}"
+
+    if ! image_exists "$imageTag"; then
+        echo "release: refusing $event: image not present locally: $imageTag" >&2
+        append_log "refused" "$release" "$imageTag" "image missing"
+        exit 1
+    fi
+
+    if ! health_check "$fault"; then
+        echo "release: refusing $event: health check failed" >&2
+        append_log "refused" "$release" "$imageTag" "health check failed${fault:+ (fault-injected)}"
+        exit 1
+    fi
+
+    # Atomic pointer replacement: write sibling temp file, then rename.
+    local tmp_pointer="$POINTER.tmp.$$"
+    printf '{"pointerVersion":1,"release":"%s","imageTag":"%s","activatedAt":"%s"}\n' \
+        "$release" "$imageTag" "$(now)" > "$tmp_pointer"
+    mv -f "$tmp_pointer" "$POINTER"
+
+    append_log "$event" "$release" "$imageTag"
+    echo "release: $event OK -> $release ($imageTag)"
+}
+
+previous_image_tag() { # last activated imageTag different from current pointer
+    [ -f "$POINTER" ] || return 1
+    local current
+    current="$(node -p 'JSON.parse(require("fs").readFileSync(process.argv[1],"utf8")).imageTag' "$POINTER")"
+    node -e '
+const fs = require("fs");
+const current = process.argv[1];
+const lines = fs.readFileSync(process.argv[2], "utf8").split("\n").filter(Boolean);
+for (let i = lines.length - 1; i >= 0; i--) {
+    let e;
+    try { e = JSON.parse(lines[i]); } catch { continue; }
+    if ((e.event === "activate" || e.event === "rollback") && e.imageTag && e.imageTag !== current) {
+        console.log(e.imageTag);
+        process.exit(0);
+    }
+}
+process.exit(1);
+' "$current" "$LOG"
+}
+
+cmd_status() {
+    echo "release:   $MOSAIC_RELEASE"
+    echo "image tag: $MOSAIC_IMAGE_TAG (packaged: $(image_exists "$MOSAIC_IMAGE_TAG" && echo yes || echo no))"
+    if [ -f "$POINTER" ]; then
+        node -e '
+const p = JSON.parse(require("fs").readFileSync(process.argv[1], "utf8"));
+console.log("active:    " + p.release + " (" + p.imageTag + ") since " + p.activatedAt);
+' "$POINTER"
+    else
+        echo "active:    (none)"
+    fi
+    if [ -f "$LOG" ]; then
+        echo "recent log:"
+        tail -5 "$LOG" | sed 's/^/  /'
+    fi
+}
+
+cmd_package() {
+    docker compose build
+    append_log "package" "$MOSAIC_RELEASE" "$MOSAIC_IMAGE_TAG"
+    echo "release: packaged $MOSAIC_IMAGE_TAG"
+}
+
+cmd_activate() {
+    local fault=""
+    if [ "${1:-}" = "--fault-injection" ]; then fault="yes"; fi
+    activate "$MOSAIC_RELEASE" "$MOSAIC_IMAGE_TAG" "activate" "$fault"
+}
+
+cmd_rollback() {
+    local prev
+    if ! prev="$(previous_image_tag)"; then
+        echo "release: rollback: no previous activation found in log" >&2
+        exit 1
+    fi
+    local prev_release
+    prev_release="$(printf '%s' "$prev" | sed -n 's/.*-r\([0-9.]*\)$/\1/p')"
+    [ -n "$prev_release" ] || prev_release="unknown"
+    activate "$prev_release" "$prev" "rollback"
+}
+
+case "${1:-}" in
+    package)  cmd_package ;;
+    activate) shift; cmd_activate "$@" ;;
+    rollback) cmd_rollback ;;
+    status)   cmd_status ;;
+    *) echo "usage: scripts/release.sh package | activate [--fault-injection] | rollback | status" >&2; exit 4 ;;
+esac