diff --git a/packages/mosaic/framework/defaults/wake-watch-list.schema.json b/packages/mosaic/framework/defaults/wake-watch-list.schema.json
index 959c0b60..3b495f30 100644
--- a/packages/mosaic/framework/defaults/wake-watch-list.schema.json
+++ b/packages/mosaic/framework/defaults/wake-watch-list.schema.json
@@ -103,6 +103,10 @@
             "type": "string",
             "description": "Operator-supplied duration (e.g. '5m', '30m', '4h'). Symbolic tier is set by the operator, not the framework."
           },
+          "fallback_cadence": {
+            "type": "string",
+            "description": "OPTIONAL, additive (schema_version 1, backward-compatible — omitting it is valid). The per-class cadence bound for the framework-shipped canon FALLBACK WAKE (F7 replacement-before-retirement, EPIC #892): the low-frequency SAFETY-wake timer (mosaic-wake-fallback.timer) that fires the canon drain INDEPENDENT of the event-driven detector, so a stalled detector cannot silently starve delivery. The A10 installer reads this per-class value and writes it as the fallback timer's OnUnitActiveSec via the blank-reset drop-in (exactly one effective OnUnitActiveUSec). SYMBOLIC — an operator-supplied duration (e.g. '30m', '1h', '4h'); the framework bakes in no numeric. Config, not code. Should be no tighter than this tier's `fallback_bound` (the safety wake is a floor, never the primary mechanism)."
+          },
           "quiet_hours_may_suppress": {
             "type": "boolean",
             "default": false,
diff --git a/packages/mosaic/framework/systemd/user/mosaic-wake-fallback.service b/packages/mosaic/framework/systemd/user/mosaic-wake-fallback.service
new file mode 100644
index 00000000..144a8b1c
--- /dev/null
+++ b/packages/mosaic/framework/systemd/user/mosaic-wake-fallback.service
@@ -0,0 +1,41 @@
+[Unit]
+# Mosaic wake FALLBACK safety drain (F7 replacement-before-retirement, EPIC #892,
+# W7). This is the framework-shipped canon-side FALLBACK WAKE: a LOW-FREQUENCY
+# SAFETY drain that fires the canon drain (digest.sh render --from-store) on a
+# per-class cadence bound, INDEPENDENT of the event-driven detector daemon
+# (mosaic-wake.service). Its whole reason to exist is that a stalled/dead detector
+# or daemon can never SILENTLY STARVE delivery: even with nothing pushing, this
+# oneshot periodically drains the durable pending-inbox so the cumulative unacked
+# set still reaches the consumer. It is the §5 retirement precondition (F7) — it
+# must be live + proven-firing BEFORE the legacy mosaic-heartbeat@ timer is reaped,
+# so there is never a coverage gap. Fixed-interval heartbeats are forbidden as the
+# PRIMARY wake mechanism (WAKE-DOCTRINE); they survive ONLY as this per-class
+# fallback cadence, bounded by urgency SLO, never as the steady state.
+#
+# This is a oneshot SERVICE activated by mosaic-wake-fallback.timer; the cadence
+# lives on the TIMER (OnUnitActiveSec), set per-class by the A10 installer via the
+# blank-reset drop-in — never here. The service therefore carries NO [Install]
+# section (the TIMER is what is enabled/wanted); it is triggered, not wanted.
+Description=Mosaic wake fallback safety drain (canon drain: digest.sh render --from-store)
+After=default.target
+
+[Service]
+Type=oneshot
+# Strip loader / noninteractive-shell controls before ExecStart, matching the
+# detector, lease-broker and tmux fleet units in this same directory (defense-in-
+# depth against an injected BASH_ENV/ENV/LD_PRELOAD in the user manager environment).
+UnsetEnvironment=LD_PRELOAD BASH_ENV ENV
+# Operator-owned runtime configuration. This EnvironmentFile carries only WAKE_*
+# NAMES (the per-agent namespace WAKE_AGENT, the lane WAKE_LANE, and — reused from
+# the detector — the pluggable adapter COMMANDS resolved BY NAME at runtime). It
+# carries NEVER any secret and NEVER any endpoint value. The '-' prefix keeps a
+# missing file from masking the installer's dedicated fail-closed install-validate.
+EnvironmentFile=-%h/.config/mosaic/wake/fallback.env
+# THE CANON DRAIN. digest.sh render --from-store drains the durable pending-inbox
+# (store.sh drain) and renders the cumulative-state digest. Running it here, on the
+# timer cadence, is the safety net: it is the SAME drain the delivery path uses, so
+# a stalled detector cannot starve it. Delivery/paste of the rendered digest is the
+# same operator-wired send seam the detector path uses (out of framework scope);
+# this unit guarantees the DRAIN fires on a bounded cadence regardless of detector
+# health. digest render exits 0 on an empty inbox, so a quiet cycle is a clean no-op.
+ExecStart=/bin/bash --noprofile --norc %h/.config/mosaic/tools/wake/digest.sh render --from-store
diff --git a/packages/mosaic/framework/systemd/user/mosaic-wake-fallback.timer b/packages/mosaic/framework/systemd/user/mosaic-wake-fallback.timer
new file mode 100644
index 00000000..fcab5a8a
--- /dev/null
+++ b/packages/mosaic/framework/systemd/user/mosaic-wake-fallback.timer
@@ -0,0 +1,30 @@
+[Unit]
+# Cadence timer for the Mosaic wake FALLBACK safety drain (F7, EPIC #892, W7).
+# Drives mosaic-wake-fallback.service on a LOW-FREQUENCY per-class cadence bound,
+# INDEPENDENT of the event-driven detector daemon, so a stalled detector can never
+# silently starve delivery. This is the framework-shipped canon-side FALLBACK WAKE:
+# a heartbeat-shaped timer that survives ONLY as the per-class fallback cadence
+# (WAKE-DOCTRINE) bounded by urgency SLO — never the steady-state wake mechanism.
+Description=Mosaic wake fallback cadence timer (per-class safety wake)
+After=default.target
+
+[Timer]
+# BASE cadence placeholder. The A10 installer OVERRIDES this per-class from the
+# watch-list schema's per-class `fallback_cadence` bound, via a BLANK-RESET drop-in
+# (an empty OnUnitActiveSec= reset line, then the new value) written under
+# mosaic-wake-fallback.timer.d/. systemd merges base + drop-ins so exactly ONE
+# effective OnUnitActiveUSec results (wake-install.sh verify-single). The base value
+# here is a conservative safety floor for a host installed before any per-class
+# drop-in is written — it is deliberately low-frequency (never the primary wake).
+OnUnitActiveSec=1h
+# Also fire shortly after boot so a freshly-booted host does not wait a full cadence
+# for its first safety drain. OnBootSec is a distinct key from OnUnitActiveSec and
+# does NOT count toward the exactly-one-OnUnitActiveUSec blank-reset invariant.
+OnBootSec=15min
+# Catch up a missed elapse (host asleep/off) rather than silently skipping it — a
+# fallback that silently skips is exactly the starvation this unit exists to prevent.
+Persistent=true
+Unit=mosaic-wake-fallback.service
+
+[Install]
+WantedBy=timers.target
diff --git a/packages/mosaic/framework/tools/wake/manifest.txt b/packages/mosaic/framework/tools/wake/manifest.txt
index e15e2c56..e957b5dd 100644
--- a/packages/mosaic/framework/tools/wake/manifest.txt
+++ b/packages/mosaic/framework/tools/wake/manifest.txt
@@ -148,13 +148,43 @@
 #              owned path, NO second ownership authority. framework-manifest.txt,
 #              the install-ordering-guard, and the manifest parity contract are all
 #              UNCHANGED. Only wake-install.sh (+ test-wake-install.sh) changed.
+#   0.6.8  #925 — framework-ship the canon-side FALLBACK WAKE (F7 replacement-
+#              before-retirement) so hosts get it OUT OF THE BOX rather than hand-
+#              wiring it per host. ADDITIVE, #869 / Gate-A/B discipline:
+#              (1) new framework units systemd/user/mosaic-wake-fallback.{timer,
+#              service}: a LOW-FREQUENCY SAFETY drain (oneshot service running the
+#              canon drain `digest.sh render --from-store`) fired by a per-class
+#              cadence timer, INDEPENDENT of the event-driven detector, so a stalled
+#              detector/daemon can never SILENTLY STARVE delivery. Both units are
+#              framework-owned via the EXISTING `systemd/**` glob in framework-
+#              manifest.txt (Gate A) — NO new owned path, NO second ownership
+#              authority. (2) an OPTIONAL, additive per-class `fallback_cadence`
+#              bound in wake-watch-list.schema.json (config, not code). It is
+#              backward-compatible within schema_version 1, so [schema_min,
+#              schema_max] stays [1,1] and the detector's Gate B range check is
+#              UNCHANGED (an out-of-range schema_version still fails loud). (3) A10
+#              install/wire: wi_install enumerates + LINKS + validates the two units
+#              into the user systemd search path (idempotent, fail-closed, same
+#              link-to-SSOT pattern as the detector unit); write-fallback-cadence
+#              writes the per-class cadence as a BLANK-RESET drop-in (exactly one
+#              effective OnUnitActiveUSec). (4) F7 install-validate: the §5 legacy
+#              reap now REFUSES unless the canon fallback wake is proven live
+#              (installed + schedulable floor always; enabled + proven-firing when a
+#              live user manager is probeable, mirroring #913's opportunistic
+#              WAKE_VERIFY_USE_SYSTEMCTL pattern) — F7 is encoded in the installer,
+#              not operator memory. framework-manifest.txt, the install-ordering-
+#              guard, and the manifest parity contract are all UNCHANGED.
 component=wake
-version=0.6.7
+version=0.6.8
 
 # Watch-list schema this component consumes, and the INCLUSIVE range of
 # schema_version values it supports. A wake-watch-list.json whose schema_version
 # falls outside [schema_min, schema_max] is rejected by the component (fail-loud),
 # never silently coerced.
+#
+# #925: the OPTIONAL per-class `fallback_cadence` bound is ADDITIVE and backward-
+# compatible — an existing schema_version-1 watch-list stays valid (the field is
+# omittable), so the supported range is UNCHANGED at [1, 1] and Gate B is intact.
 schema=wake-watch-list
 schema_min=1
 schema_max=1
@@ -217,3 +247,11 @@ schema_max=1
 # Companion (framework subtree, not under tools/wake/): systemd/user/mosaic-wake.service
 #                    — the long-lived detector daemon unit (per-class SLO lives in
 #                    the daemon, NOT a systemd interval).                          (W7)
+# Companion (framework subtree, not under tools/wake/):
+#   systemd/user/mosaic-wake-fallback.timer + mosaic-wake-fallback.service
+#                    — the canon FALLBACK WAKE (F7): a per-class cadence timer firing
+#                    a oneshot SAFETY drain (digest.sh render --from-store),
+#                    INDEPENDENT of the detector, so a stalled detector cannot starve
+#                    delivery. Owned via the existing systemd/** glob; the per-class
+#                    cadence is a blank-reset drop-in; the §5 reap is F7-gated on this
+#                    being proven live.                                       (W7, #925)
diff --git a/packages/mosaic/framework/tools/wake/test-wake-detector.sh b/packages/mosaic/framework/tools/wake/test-wake-detector.sh
index 343b209e..4f9952d2 100755
--- a/packages/mosaic/framework/tools/wake/test-wake-detector.sh
+++ b/packages/mosaic/framework/tools/wake/test-wake-detector.sh
@@ -398,6 +398,53 @@ EOF
   "$STORE" consume --upto 6 >/dev/null 2>&1 || fail_msg "D8: CONSUMED 6 must succeed over the contiguous prefix after the delta"
 ) && ok
 
+echo "== D9: schema (#925) — optional per-class fallback_cadence is BACKWARD-COMPAT (in-range accepted; out-of-range still FAILS LOUD, Gate B intact) =="
+(
+  WAKE_STATE_HOME="$(fresh_state d9)"
+  export WAKE_STATE_HOME
+  unset WAKE_AGENT
+  stub="$TMP_ROOT/d9stub"
+  mkdir -p "$stub"
+  make_stub "$stub"
+  export WAKE_DETECTOR_SOURCE_CMD="$stub/adapter.sh"
+  printf 'SHA-D9\n' >"$stub/repo_r1"
+  printf '## LANE-X\nx\n' >"$stub/board_file_b1"
+  # A watch-list that EXERCISES the new optional additive field: a per-class
+  # `fallback_cadence` under an slos tier, at schema_version 1. Because the field is
+  # OPTIONAL + additive, an existing schema_version-1 watch-list stays valid and the
+  # detector's Gate B range [schema_min, schema_max] is UNCHANGED — the new field
+  # must NOT push the watch-list out of range.
+  wl="$TMP_ROOT/d9.json"
+  write_fc_watchlist() {
+    local file="$1" ver="$2"
+    cat >"$file" <<EOF
+{
+  "schema_version": $ver,
+  "slos": {
+    "actionable-tier": { "class": "actionable", "fallback_bound": "30m", "fallback_cadence": "1h" }
+  },
+  "repos": [{ "id": "r1", "remote": "example/repo", "class": "digest" }],
+  "board_files": [{ "id": "b1", "path": "BOARD.md", "anchor": "## LANE-X" }],
+  "watches": [
+    { "lane": "lane-x", "sources": [
+      { "kind": "repo", "id": "r1" },
+      { "kind": "board_file", "id": "b1" }
+    ] }
+  ]
+}
+EOF
+  }
+  # (a) in-range (schema_version 1) WITH fallback_cadence -> ACCEPTED.
+  write_fc_watchlist "$wl" 1
+  export WAKE_WATCH_LIST="$wl"
+  "$DET" poll-once >/dev/null 2>&1 || fail_msg "D9: an in-range watch-list carrying the optional fallback_cadence must be ACCEPTED (additive/backward-compatible)"
+  # (b) out-of-range (schema_version 999) WITH the SAME field -> STILL FAILS LOUD.
+  write_fc_watchlist "$wl" 999
+  err="$("$DET" poll-once 2>&1)"; rc=$?
+  [ "$rc" -ne 0 ] || fail_msg "D9: the new field must NOT weaken Gate B — an out-of-range schema_version must still FAIL LOUD (rc=$rc)"
+  echo "$err" | grep -qi 'range' || fail_msg "D9: the out-of-range failure must still state it is out of the supported range [$err]"
+) && ok
+
 echo
 if [ -s "$FAILFILE" ]; then
   echo "wake detector harness: FAILED ($(grep -c . "$FAILFILE") assertion(s))" >&2
diff --git a/packages/mosaic/framework/tools/wake/test-wake-install.sh b/packages/mosaic/framework/tools/wake/test-wake-install.sh
index 0df05fe3..794e0293 100755
--- a/packages/mosaic/framework/tools/wake/test-wake-install.sh
+++ b/packages/mosaic/framework/tools/wake/test-wake-install.sh
@@ -193,13 +193,19 @@ echo "== I6: reset->verify->retire — overlap keeps legacy running; only §4-ve
   export WAKE_SNAPSHOT_DIR="$SNAP"
   TIMER="mosaic-heartbeat@c.timer"
   printf '[Timer]\nOnUnitActiveSec=15min\n' >"$UD/$TIMER"
+  # F7 (#925): the vector-passed reap now REFUSES unless the canon FALLBACK WAKE is
+  # proven live (replacement-before-retirement). Provision it at the schedulable
+  # floor so the lifecycle path under test still reaches the reap. (I11 is the
+  # dedicated F7 refuse/allow control.)
+  cp "$FRAMEWORK_ROOT/systemd/user/mosaic-wake-fallback.timer"   "$UD/mosaic-wake-fallback.timer"
+  cp "$FRAMEWORK_ROOT/systemd/user/mosaic-wake-fallback.service" "$UD/mosaic-wake-fallback.service"
   # (a) overlap phase (NO --vector-passed): reset+verify, legacy LEFT RUNNING.
   out="$(bash "$WI" reset-verify-retire c --interval 30min 2>&1)"; rc=$?
   [ "$rc" -eq 0 ] || fail_msg "I6: overlap reset-verify must succeed (rc=$rc) [$out]"
   [ -f "$UD/$TIMER" ] || fail_msg "I6: overlap phase must LEAVE the legacy timer running (retire withheld)"
   [ -f "$SNAP/$TIMER" ] || fail_msg "I6: the legacy timer must be snapshotted before any retire"
   echo "$out" | grep -qi 'LEFT RUNNING' || fail_msg "I6: overlap must announce retire is withheld [$out]"
-  # (b) §4-vector pass: retire LAST, snapshot-guarded.
+  # (b) §4-vector pass: retire LAST, snapshot-guarded (fallback proven live above).
   out2="$(bash "$WI" reset-verify-retire c --interval 30min --vector-passed 2>&1)"; rc2=$?
   [ "$rc2" -eq 0 ] || fail_msg "I6: vector-passed retire must succeed (rc=$rc2) [$out2]"
   [ ! -f "$UD/$TIMER" ] || fail_msg "I6: on §4-vector pass the legacy timer must be RETIRED"
@@ -315,6 +321,111 @@ echo "== I10: systemd search-path — install links mosaic-wake.service into the
   bash "$WI" validate-systemd-path >/dev/null 2>&1 || fail_msg "I10: re-install must keep the unit resolvable"
 ) && ok
 
+# ── (#925) canon FALLBACK WAKE (F7 replacement-before-retirement) ──────────────
+
+echo "== I11: F7 — the legacy reap REFUSES unless the canon fallback wake is proven live =="
+(
+  UD="$(fresh i11-units)"; SNAP="$(fresh i11-snap)"
+  export WAKE_SYSTEMD_USER_DIR="$UD"
+  export WAKE_SNAPSHOT_DIR="$SNAP"
+  TIMER="mosaic-heartbeat@f.timer"
+  printf '[Timer]\nOnUnitActiveSec=15min\n' >"$UD/$TIMER"
+  # (a) fallback-proven-live is the F7 gate primitive: with NO fallback installed,
+  #     it must REFUSE (schedulable floor not met).
+  out0="$(bash "$WI" fallback-proven-live 2>&1)"; rc0=$?
+  [ "$rc0" -ne 0 ] || fail_msg "I11: fallback-proven-live must FAIL when the fallback wake is not installed (rc=$rc0)"
+  echo "$out0" | grep -qi 'F7' || fail_msg "I11: the refusal must name the F7 precondition [$out0]"
+  # (b) NEGATIVE — vector-passed reap with NO live fallback must be REFUSED and the
+  #     legacy timer LEFT RUNNING (never a coverage gap).
+  out="$(bash "$WI" reset-verify-retire f --interval 30min --vector-passed 2>&1)"; rc=$?
+  [ "$rc" -ne 0 ] || fail_msg "I11: reap must be REFUSED without a proven-live fallback (rc=$rc)"
+  echo "$out" | grep -qi 'FALLBACK WAKE is not proven live' || fail_msg "I11: refusal must name the un-proven fallback [$out]"
+  [ -f "$UD/$TIMER" ] || fail_msg "I11: a refused reap must LEAVE the legacy timer running (F7 — no coverage gap)"
+  # (c) POSITIVE — provision the fallback at the schedulable floor, then the reap
+  #     proceeds (F7 satisfied) and the legacy timer is retired.
+  cp "$FRAMEWORK_ROOT/systemd/user/mosaic-wake-fallback.timer"   "$UD/mosaic-wake-fallback.timer"
+  cp "$FRAMEWORK_ROOT/systemd/user/mosaic-wake-fallback.service" "$UD/mosaic-wake-fallback.service"
+  bash "$WI" fallback-proven-live >/dev/null 2>&1 || fail_msg "I11: fallback-proven-live must PASS once the fallback units are schedulable"
+  out2="$(bash "$WI" reset-verify-retire f --interval 30min --vector-passed 2>&1)"; rc2=$?
+  [ "$rc2" -eq 0 ] || fail_msg "I11: with a proven-live fallback the reap must succeed (rc=$rc2) [$out2]"
+  [ ! -f "$UD/$TIMER" ] || fail_msg "I11: with F7 satisfied the legacy timer must be RETIRED"
+) && ok
+
+echo "== I12: fallback drain — a STALLED detector still gets delivery via the canon fallback drain =="
+(
+  H="$(fresh i12-state)"
+  export WAKE_STATE_HOME="$H"
+  unset WAKE_AGENT
+  STORE="$SCRIPT_DIR/store.sh"; DIGEST="$SCRIPT_DIR/digest.sh"
+  # A pending obligation lands in the durable inbox — but the detector daemon is
+  # STALLED/absent (we never run detector.sh). Enqueue directly to the store.
+  seq="$(bash "$STORE" enqueue --class digest \
+    --locators '{"kind":"repo","id":"STALLED-DRAIN-MARK","path":"BOARD.md","observed_hash":"deadbeef"}' 2>/dev/null)"
+  [ -n "$seq" ] || fail_msg "I12: store enqueue must allocate a seq"
+  # The canon fallback drain is EXACTLY the shipped unit's ExecStart: digest render
+  # --from-store. Firing it (as the timer would) must surface the pending obligation
+  # even with no detector running — no starvation of the drain.
+  out="$(bash "$DIGEST" render --from-store 2>/dev/null)"; rc=$?
+  [ "$rc" -eq 0 ] || fail_msg "I12: the canon fallback drain must exit 0 (rc=$rc)"
+  echo "$out" | grep -q 'STALLED-DRAIN-MARK' \
+    || fail_msg "I12: the fallback drain must DELIVER the pending obligation a stalled detector left (no delivery starvation) [$out]"
+  # Bind the invariant to the SHIPPED unit: its ExecStart must be this canon drain.
+  UNIT="$FRAMEWORK_ROOT/systemd/user/mosaic-wake-fallback.service"
+  grep -qE '^ExecStart=.*digest\.sh render --from-store' "$UNIT" \
+    || fail_msg "I12: mosaic-wake-fallback.service ExecStart must fire the canon drain (digest.sh render --from-store)"
+) && ok
+
+echo "== I13: install links + validates the canon fallback timer+service into the search path (idempotent) =="
+(
+  TGT="$(fresh i13-target)"
+  UD="$(fresh i13-systemd)"
+  export WAKE_INSTALL_SOURCE="$FRAMEWORK_ROOT"
+  export WAKE_INSTALL_TARGET="$TGT"
+  export WAKE_SYSTEMD_USER_DIR="$UD"
+  bash "$WI" install >/dev/null 2>&1 || fail_msg "I13: install must succeed"
+  # (a) both fallback units resolve in the user systemd search path.
+  [ -e "$UD/mosaic-wake-fallback.timer" ]   || fail_msg "I13: fallback timer must be linked into the search path"
+  [ -e "$UD/mosaic-wake-fallback.service" ] || fail_msg "I13: fallback service must be linked into the search path"
+  bash "$WI" validate-fallback-units >/dev/null 2>&1 || fail_msg "I13: validate-fallback-units must pass after install"
+  # (b) NEGATIVE CONTROL: a missing fallback unit is CAUGHT (fail loud, names the miss).
+  rm -f "$UD/mosaic-wake-fallback.timer"
+  out="$(bash "$WI" validate-fallback-units 2>&1)"; rc=$?
+  [ "$rc" -ne 0 ] || fail_msg "I13: validate must FAIL when a fallback unit is not in the search path (rc=$rc) [$out]"
+  echo "$out" | grep -qi 'search path' || fail_msg "I13: validate failure must name the search-path miss [$out]"
+  # (c) idempotent re-install: exactly one entry per unit, still resolvable.
+  bash "$WI" install >/dev/null 2>&1 || fail_msg "I13: re-run install must succeed"
+  nt="$(find "$UD" -maxdepth 1 -name 'mosaic-wake-fallback.timer' | grep -c .)"
+  ns="$(find "$UD" -maxdepth 1 -name 'mosaic-wake-fallback.service' | grep -c .)"
+  [ "$nt" -eq 1 ] && [ "$ns" -eq 1 ] || fail_msg "I13: re-install must not duplicate the fallback entries (timer=$nt service=$ns)"
+  bash "$WI" validate-fallback-units >/dev/null 2>&1 || fail_msg "I13: re-install must keep the fallback units resolvable"
+) && ok
+
+echo "== I14: per-class fallback cadence — blank-reset yields EXACTLY ONE OnUnitActiveUSec (negative control leaks two) =="
+(
+  UD="$(fresh i14-units)"
+  export WAKE_SYSTEMD_USER_DIR="$UD"
+  TIMER="mosaic-wake-fallback.timer"
+  # The shipped timer carries the base OnUnitActiveSec placeholder (=1h).
+  cp "$FRAMEWORK_ROOT/systemd/user/$TIMER" "$UD/$TIMER"
+  grep -q '^OnUnitActiveSec=1h' "$UD/$TIMER" || fail_msg "I14: shipped fallback timer must carry a base OnUnitActiveSec placeholder"
+  # write-fallback-cadence writes the per-class cadence in BLANK-RESET form.
+  out="$(bash "$WI" write-fallback-cadence 30min 2>&1)"; rc=$?
+  [ "$rc" -eq 0 ] || fail_msg "I14: write-fallback-cadence must succeed + verify single (rc=$rc) [$out]"
+  echo "$out" | grep -qi 'exactly one' || fail_msg "I14: the cadence write must confirm exactly-one OnUnitActiveUSec [$out]"
+  [ -f "$UD/$TIMER.d/cadence.conf" ] || fail_msg "I14: the per-class cadence drop-in must be written under <timer>.d/"
+  # Assert the blank-reset FORM: an empty `OnUnitActiveSec=` reset line IMMEDIATELY
+  # FOLLOWED by the new value. Portable across GNU and BusyBox grep (Alpine CI) —
+  # `grep -z` (NUL-data) is a GNU-only extension BusyBox grep does NOT support, so
+  # match the reset line and require the value on the very next line (-A1) instead.
+  grep -A1 '^OnUnitActiveSec=$' "$UD/$TIMER.d/cadence.conf" | grep -qx 'OnUnitActiveSec=30min' \
+    || fail_msg "I14: the drop-in must use the blank-reset form (empty reset line, then the value)"
+  bash "$WI" verify-single "$TIMER" >/dev/null 2>&1 || fail_msg "I14: base(1h)+blank-reset(30min) must resolve exactly one OnUnitActiveUSec"
+  # NEGATIVE CONTROL: a drop-in WITHOUT the reset line appends -> base 1h + 30min -> two -> fail.
+  printf '[Timer]\nOnUnitActiveSec=30min\n' >"$UD/$TIMER.d/cadence.conf"
+  out2="$(bash "$WI" verify-single "$TIMER" 2>&1)"; rc2=$?
+  [ "$rc2" -ne 0 ] || fail_msg "I14: without the reset line two cadences must leak (verify should FAIL) [$out2]"
+) && ok
+
 echo
 if [ -s "$FAILFILE" ]; then
   echo "wake install harness: FAILED ($(grep -c . "$FAILFILE") assertion(s))" >&2
diff --git a/packages/mosaic/framework/tools/wake/wake-install.sh b/packages/mosaic/framework/tools/wake/wake-install.sh
index 0253ccb7..5ab1b604 100755
--- a/packages/mosaic/framework/tools/wake/wake-install.sh
+++ b/packages/mosaic/framework/tools/wake/wake-install.sh
@@ -51,6 +51,13 @@ WAKE_SNAPSHOT_DIR="${WAKE_SNAPSHOT_DIR:-${XDG_STATE_HOME:-$HOME/.local/state}/mo
 
 # systemd user unit NAME this installer deploys + links (overridable for the harness).
 WAKE_UNIT_NAME="${WAKE_UNIT_NAME:-mosaic-wake.service}"
+# The framework-shipped canon FALLBACK WAKE units (F7, #925): a low-frequency
+# SAFETY drain (oneshot service) driven by a per-class cadence timer, INDEPENDENT
+# of the event-driven detector. Both are framework-owned via the existing
+# `systemd/**` glob in framework-manifest.txt (Gate A) — NO new owned path, NO
+# second ownership authority (#869 additive). Overridable for the harness.
+WAKE_FALLBACK_TIMER_NAME="${WAKE_FALLBACK_TIMER_NAME:-mosaic-wake-fallback.timer}"
+WAKE_FALLBACK_SERVICE_NAME="${WAKE_FALLBACK_SERVICE_NAME:-mosaic-wake-fallback.service}"
 # The shared framework-manifest reader this installer needs for Gate A ownership
 # validation. Overridable so the red-first harness can point it at a missing path
 # to prove the fail-loud without disturbing the real tree (#913a).
@@ -108,6 +115,11 @@ _wi_component_candidates() {
   # shared framework subtrees. Listed here for ENUMERATION only — ownership is
   # still decided solely by framework-manifest.txt in wi_install.
   printf '%s\n' "systemd/user/mosaic-wake.service"
+  # The canon FALLBACK WAKE units (F7, #925). Both resolve framework-owned via the
+  # existing `systemd/**` glob — enumerated here so wi_install COPIES them; still
+  # Gate-A-validated against the framework-manifest SSOT before any byte is written.
+  printf '%s\n' "systemd/user/$WAKE_FALLBACK_TIMER_NAME"
+  printf '%s\n' "systemd/user/$WAKE_FALLBACK_SERVICE_NAME"
   printf '%s\n' "defaults/wake-watch-list.schema.json"
 }
 
@@ -164,6 +176,14 @@ wi_install() {
   wi_link_systemd_unit || return 1
   wi_validate_systemd_path || return 1
 
+  # (#925) A10 canon step: place the canon FALLBACK WAKE units (timer + oneshot
+  # service) into the user systemd search path and validate they resolve + parse.
+  # Same link-back-to-SSOT, idempotent, fail-closed pattern as the detector unit
+  # above. The per-class cadence drop-in (blank-reset) and the F7 proven-live gate
+  # are separate steps (write-fallback-cadence / reset-verify-retire).
+  wi_link_fallback_units || return 1
+  wi_validate_fallback_units || return 1
+
   # Machine-readable summary for the harness (idempotency assertion keys off it).
   printf 'wake-install: written=%s skipped=%s missing=%s\n' "$written" "$skipped" "$missing"
 }
@@ -255,6 +275,183 @@ wi_validate_systemd_path() {
   return 0
 }
 
+# ═══════════════════════════════════════════════════════════════════════════════
+# (#925) canon FALLBACK WAKE units — link + validate + per-class cadence + F7 gate
+# ═══════════════════════════════════════════════════════════════════════════════
+# ADDITIVE / #869: exactly as for the detector unit, the link target lives OUTSIDE
+# mosaic home, so it is NOT a framework-manifest path. Ownership of the SSOT units
+# stays the single `systemd/**` glob in framework-manifest.txt — NO new owned path,
+# NO second ownership authority. The link points BACK to the mosaic-home SSOT copy.
+
+# _wi_link_one UNIT — idempotently place ONE deployed unit into the user systemd
+# search path (symlink to the mosaic-home SSOT copy). Shared idiom with the
+# detector's wi_link_systemd_unit; an already-correct link / byte-identical file is
+# left untouched, a stale entry is replaced. Fail-closed on a missing SSOT copy.
+_wi_link_one() {
+  local unit="$1"
+  local ssot="$WAKE_INSTALL_TARGET/systemd/user/$unit"
+  local link="$WAKE_SYSTEMD_USER_DIR/$unit"
+  if [[ ! -f "$ssot" ]]; then
+    wi_fail "systemd-link — the deployed unit is missing at $ssot; run 'wake-install.sh install' first (fail-closed)."
+    return 1
+  fi
+  mkdir -p "$WAKE_SYSTEMD_USER_DIR"
+  if [[ -L "$link" ]]; then
+    if [[ "$(readlink "$link")" == "$ssot" ]]; then
+      wi_ok "systemd-link — '$unit' already linked into the search path ($link -> $ssot)."
+      return 0
+    fi
+  elif [[ -f "$link" ]] && cmp -s "$ssot" "$link"; then
+    wi_ok "systemd-link — '$unit' already present in the search path ($link, byte-identical)."
+    return 0
+  fi
+  if ! ln -sfn "$ssot" "$link"; then
+    wi_fail "systemd-link — could not link '$unit' into the user systemd search path ($link). FAIL LOUD (fail-closed)."
+    return 1
+  fi
+  wi_ok "systemd-link — '$unit' linked into the user systemd search path ($link -> $ssot)."
+  return 0
+}
+
+# wi_link_fallback_units — link BOTH canon fallback units (timer + oneshot service)
+# into the user systemd search path so `systemctl --user` can resolve+enable them.
+wi_link_fallback_units() {
+  _wi_link_one "$WAKE_FALLBACK_TIMER_NAME" || return 1
+  _wi_link_one "$WAKE_FALLBACK_SERVICE_NAME" || return 1
+  return 0
+}
+
+# _wi_validate_one UNIT KIND — post-install validate that ONE unit resolves in the
+# user systemd search path AND is well-formed for its KIND. KIND=timer requires
+# [Timer] + a base OnUnitActiveSec (the blank-reset target); KIND=service requires
+# [Service] + ExecStart. As with the detector, the AUTHORITATIVE floor is
+# path + well-formedness (the installer often runs with no live user manager); a
+# live `systemctl --user cat` probe runs ONLY opportunistically behind the guard.
+_wi_validate_one() {
+  local unit="$1" kind="$2"
+  local link="$WAKE_SYSTEMD_USER_DIR/$unit" resolved
+  if [[ ! -e "$link" ]]; then
+    wi_fail "fallback-validate — '$unit' is NOT in the user systemd search path ($link). systemctl --user cannot resolve it, so the canon fallback wake cannot be enabled/started. Run 'wake-install.sh link-fallback-units' (part of install) (fail-closed)."
+    return 1
+  fi
+  if [[ -L "$link" ]]; then
+    resolved="$(readlink -f "$link" 2>/dev/null || true)"
+  else
+    resolved="$link"
+  fi
+  if [[ -z "$resolved" || ! -r "$resolved" ]]; then
+    wi_fail "fallback-validate — '$unit' search-path entry ($link) does not dereference to a readable unit file. FAIL LOUD (fail-closed)."
+    return 1
+  fi
+  local -a miss=()
+  grep -q '^\[Unit\]' "$resolved" || miss+=("[Unit]")
+  case "$kind" in
+    timer)
+      grep -q '^\[Timer\]'         "$resolved" || miss+=("[Timer]")
+      grep -q '^\[Install\]'       "$resolved" || miss+=("[Install]")
+      grep -q '^OnUnitActiveSec='  "$resolved" || miss+=("OnUnitActiveSec=")
+      ;;
+    service)
+      grep -q '^\[Service\]' "$resolved" || miss+=("[Service]")
+      grep -q '^ExecStart='  "$resolved" || miss+=("ExecStart=")
+      ;;
+    *)
+      wi_fail "fallback-validate — internal: unknown unit kind '$kind'."; return 2 ;;
+  esac
+  if [[ ${#miss[@]} -ne 0 ]]; then
+    wi_fail "fallback-validate — '$unit' ($resolved) is malformed: missing ${miss[*]}. Refusing to certify an ill-formed unit (fail-closed)."
+    return 1
+  fi
+  if [[ "${WAKE_VERIFY_USE_SYSTEMCTL:-0}" == "1" ]] && command -v systemctl >/dev/null 2>&1; then
+    if systemctl --user cat "$unit" >/dev/null 2>&1; then
+      wi_ok "fallback-validate — 'systemctl --user cat $unit' resolves (live user manager confirmed)."
+    else
+      wi_warn "fallback-validate — file is in the search path + well-formed, but 'systemctl --user cat $unit' did not resolve (no live user manager / not daemon-reloaded). Non-fatal: run 'systemctl --user daemon-reload' in a live session."
+    fi
+  fi
+  wi_ok "fallback-validate — '$unit' resolves in the user systemd search path ($link -> $resolved, well-formed $kind)."
+  return 0
+}
+
+# wi_validate_fallback_units — both canon fallback units resolve + are well-formed.
+wi_validate_fallback_units() {
+  _wi_validate_one "$WAKE_FALLBACK_TIMER_NAME"   timer   || return 1
+  _wi_validate_one "$WAKE_FALLBACK_SERVICE_NAME" service || return 1
+  return 0
+}
+
+# wi_write_fallback_cadence CADENCE — write the per-class cadence for the fallback
+# TIMER as a BLANK-RESET drop-in (mosaic-wake-fallback.timer.d/cadence.conf), then
+# verify exactly ONE effective OnUnitActiveUSec. CADENCE is the operator's per-class
+# `fallback_cadence` from the watch-list (config, not code). Same blank-reset idiom
+# as the legacy-timer cadence: an empty OnUnitActiveSec= reset line CLEARS the base
+# value, then the new value sets exactly one — so the base placeholder in the shipped
+# timer can never accumulate into a second effective cadence.
+wi_write_fallback_cadence() {
+  local cadence="${1:-}"
+  [[ -n "$cadence" ]] || { wi_fail "write-fallback-cadence: CADENCE (per-class fallback_cadence) required."; return 2; }
+  local timer="$WAKE_FALLBACK_TIMER_NAME"
+  wi_write_blank_reset_dropin "$WAKE_SYSTEMD_USER_DIR/$timer.d/cadence.conf" "$cadence" || return 1
+  wi_verify_single_active "$timer" || {
+    wi_fail "write-fallback-cadence — blank-reset verify failed for '$timer'; the fallback cadence did not collapse to exactly one OnUnitActiveUSec (fail-closed)."
+    return 1
+  }
+  wi_ok "write-fallback-cadence — '$timer' cadence set to $cadence (blank-reset, exactly one OnUnitActiveUSec)."
+  return 0
+}
+
+# wi_fallback_proven_live — the F7 PRECONDITION check (replacement-before-retirement,
+# #925). The legacy reap MUST NOT proceed unless the canon fallback wake is live +
+# proven-firing, so there is never a coverage gap. Layered, fail-closed:
+#   FLOOR (always, even with no live user manager): both fallback units resolve in
+#     the user systemd search path AND are well-formed (SCHEDULABLE/enabled floor) —
+#     i.e. the fallback is INSTALLED and CAN fire. A missing/ill-formed unit => REFUSE.
+#   LIVE (opportunistic, WAKE_VERIFY_USE_SYSTEMCTL=1 + a reachable user manager,
+#     mirroring #913): additionally require the TIMER be ENABLED and PROVEN-FIRING —
+#     LastTriggerUSec is set (it has fired at least once) OR NextElapse is armed
+#     (it is scheduled to fire). A dead/never-armed timer => REFUSE.
+# Returns 0 iff the fallback is proven live to the strongest tier available.
+wi_fallback_proven_live() {
+  local timer="$WAKE_FALLBACK_TIMER_NAME" service="$WAKE_FALLBACK_SERVICE_NAME"
+  # FLOOR — installed + well-formed (schedulable). Reuses the validate above.
+  if ! wi_validate_fallback_units >/dev/null 2>&1; then
+    wi_fail "F7 fallback-proven-live — the canon FALLBACK WAKE ('$timer' + '$service') is NOT installed/schedulable in the user systemd search path. Replacement-before-retirement (F7) FORBIDS reaping the legacy timer without a live fallback (fail-closed). Run 'wake-install.sh install' + 'write-fallback-cadence <fallback_cadence>' first."
+    return 1
+  fi
+  # LIVE — opportunistic proven-firing when a real user manager is reachable.
+  if [[ "${WAKE_VERIFY_USE_SYSTEMCTL:-0}" == "1" ]] && command -v systemctl >/dev/null 2>&1; then
+    local enabled last next
+    enabled="$(systemctl --user is-enabled "$timer" 2>/dev/null || true)"
+    if [[ "$enabled" != "enabled" && "$enabled" != "static" ]]; then
+      wi_fail "F7 fallback-proven-live — '$timer' is not enabled (systemctl --user is-enabled => '${enabled:-unknown}'). A disabled fallback cannot fire; refusing the legacy reap (F7, fail-closed)."
+      return 1
+    fi
+    last="$(systemctl --user show "$timer" -p LastTriggerUSec --value 2>/dev/null || true)"
+    next="$(systemctl --user show "$timer" -p NextElapseUSecRealtime --value 2>/dev/null || true)"
+    # Proven-firing: it has already fired (LastTrigger set) OR it is armed to fire
+    # (NextElapse set). A timer that is neither is dead => refuse.
+    if _wi_usec_set "$last" || _wi_usec_set "$next"; then
+      wi_ok "F7 fallback-proven-live — '$timer' is enabled and proven-firing (LastTrigger='${last:-n/a}', NextElapse='${next:-n/a}'). Legacy reap is unblocked (F7 satisfied)."
+      return 0
+    fi
+    wi_fail "F7 fallback-proven-live — '$timer' is enabled but has NEITHER fired (LastTriggerUSec unset) NOR is armed (NextElapseUSecRealtime unset): it is not proven-firing. Refusing the legacy reap (F7, fail-closed) — start the timer and confirm it fires first."
+    return 1
+  fi
+  wi_ok "F7 fallback-proven-live — canon FALLBACK WAKE is installed + schedulable (no live user manager to probe firing; schedulable/enabled floor satisfied, mirroring #913). Legacy reap is unblocked at the schedulable floor."
+  return 0
+}
+
+# _wi_usec_set VALUE — rc 0 iff VALUE is a set systemd USec timestamp: non-empty,
+# not the "unset" sentinels systemd prints for a never-fired / never-armed timer.
+_wi_usec_set() {
+  local v="$1"
+  [[ -n "$v" ]] || return 1
+  case "$v" in
+    0|n/a|'-'|'') return 1 ;;
+    *) return 0 ;;
+  esac
+}
+
 # ═══════════════════════════════════════════════════════════════════════════════
 # (v) Fail-closed alarm-target + HMAC-key install-validation (G1/G2a)
 # ═══════════════════════════════════════════════════════════════════════════════
@@ -512,6 +709,17 @@ wi_reset_verify_retire() {
   # 3) RETIRE LAST — only on the §4-vector pass, and only via the snapshot-guarded
   #    reap. Without --vector-passed the legacy units are LEFT RUNNING (overlap).
   if [[ "$vector_passed" -eq 1 ]]; then
+    # F7 PRECONDITION (#925) — replacement-before-retirement. The reap MUST NOT
+    # proceed unless the canon FALLBACK WAKE is proven live (installed + schedulable
+    # at the floor; enabled + proven-firing when a live user manager is probeable).
+    # This encodes F7 into the installer, not operator memory: there is never a
+    # window where the legacy net is reaped before its replacement is carrying load.
+    if [[ "${WAKE_REQUIRE_FALLBACK_LIVE:-1}" == "1" ]]; then
+      wi_fallback_proven_live || {
+        wi_fail "reset-verify-retire — REFUSING to reap the legacy '$agent' heartbeat: the canon FALLBACK WAKE is not proven live (F7 replacement-before-retirement, fail-closed). The legacy net stays UP until the fallback is carrying load."
+        return 1
+      }
+    fi
     wi_reap_unit "$legacy_timer" || return 1
     # The paired service may not be independently deployed; reap it best-effort
     # but still snapshot-guarded if present.
@@ -534,6 +742,10 @@ if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
     install)              wi_install "$@" ;;
     link-systemd-unit)    wi_link_systemd_unit "$@" ;;
     validate-systemd-path) wi_validate_systemd_path "$@" ;;
+    link-fallback-units)  wi_link_fallback_units "$@" ;;
+    validate-fallback-units) wi_validate_fallback_units "$@" ;;
+    write-fallback-cadence) wi_write_fallback_cadence "$@" ;;
+    fallback-proven-live) wi_fallback_proven_live "$@" ;;
     validate-targets)     wi_validate_targets "$@" ;;
     validate-hmac-key)    wi_validate_hmac_key "$@" ;;
     validate-alarm-target) wi_validate_alarm_target "$@" ;;
@@ -552,6 +764,10 @@ Commands:
                                        path and validate it resolves (b, #913).
   link-systemd-unit                    Link mosaic-wake.service into ~/.config/systemd/user/.
   validate-systemd-path                Validate the unit resolves in the user systemd search path.
+  link-fallback-units                  Link the canon fallback wake timer+service into the search path (#925).
+  validate-fallback-units              Validate the fallback timer+service resolve + are well-formed (#925).
+  write-fallback-cadence CADENCE       Write the per-class fallback timer cadence as a blank-reset drop-in (#925).
+  fallback-proven-live                 F7 gate: the canon fallback wake is proven live (schedulable floor / firing) (#925).
   validate-targets                     Fail-closed HMAC-key + alarm-target validate (v).
   validate-hmac-key                    HMAC key resolves by-name, else fail loud.
   validate-alarm-target                Alarm sink configured + reachable, else fail loud.