SAHARA

Showing all 240 sample entries.

• FAL-001Slow slides, collapses and falls with no impact

  An 86-year-old woman with osteoporosis feels her knees give way at the kitchen counter and slides down the cupboard door over about four seconds, ending seated on the floor without any impact.

  TrapA trigger built on fast height loss or an impact sound never fires, so a real fall goes undetected.

  RequiredCreate candidates from arrival at floor level in an unexpected zone as well as from descent speed, so slow slides enter the same verification window as fast falls.

• FAL-019Slow slides, collapses and falls with no impact

  A woman with severe kyphosis, bent at the waist, loses balance and lowers onto her knees and forearms in the veranda over eight seconds.

  TrapHer normal stooped posture has a low centroid, so the drop from it is small.

  RequiredLearn the resident's usual upright height and trunk angle at enrolment and set height thresholds relative to it.

• FAL-037Falls from bed, floor mattress, diwan and sofa

  A resident slides off the sofa onto the floor at 22:30 while watching television, laughing, and then decides to stay there to rest.

  TrapA conscious, comfortable person on the floor triggers a fall alert that she then resents.

  RequiredAllow cancellation by voice or button within the prompt window, log the event as a recovered or declined fall, and continue observing.

• FAL-056Sit-to-stand, chairs, stools and transfers

  A woman rises from the squatting toilet in a hurry after hearing the doorbell, feels dizzy and sits back on the floor with her back to the wall.

  TrapThe squat and the later floor sitting look like parts of a normal toilet visit, so nothing stands out.

  RequiredIn a squat-toilet room, model the squat as normal but floor sitting with the back to the wall after the rise as a candidate with a short window.

• FAL-074Walkers, canes, wheelchairs and commode chairs

  A man whose three-wheeled walker catches on the raised bathroom threshold falls forward into the bathroom, and the walker remains outside the door.

  TrapThe person is in a private zone with limited sensing and the fall occurs at a doorway between two zones.

  RequiredMerge tracks across the threshold; a body inside the bathroom at floor level with an aid left outside is a strong sign, raised with bathroom coverage stated.

• FAL-093Stairs, steps, ladders, thresholds and terraces

  A woman trips on the top step carrying a basket of laundry, and the clothes and basket fall noisily down the stairs ahead of her.

  TrapThe falling objects are more conspicuous than the person, so the event is filed as a dropped object.

  RequiredAlways check the human track after a falling-object sound near stairs; track and posture decide, and noise alone never closes a candidate.

• FAL-111Falls in toilets, bathrooms and wet areas

  A woman rises from the squat toilet after a long visit, becomes light-headed, and falls forward against the closed door with her knees on the floor.

  TrapA posture of kneeling at a door in a private zone resembles prayer, and little identity evidence is allowed.

  RequiredRun the fall rule in the bathroom with ambient evidence only; kneeling against the door with no rise within the personal limit is a candidate and the alert states the coverage level.

• FAL-130Syncope, orthostatic hypotension, seizures and drop attacks

  After a heavy festival lunch with relatives, an 85-year-old woman stands up from the dining chair and faints from postprandial hypotension, falling to the floor.

  TrapVisitors in the room muddy the count, and the others may lift her at once, changing the evidence.

  RequiredDetect the fall with multi-person tracking; when others respond within seconds, log an attended event and notify the family at watch level rather than urgent.

• FAL-148Parkinson's disease, stroke, dementia and delirium

  A man with Parkinson's disease freezes at the narrow bedroom doorway, his feet stuck, then pitches forward and lands on his hands and knees in the passage.

  TrapFreezing looks like standing still, and the pitch forward is slow and ends in a posture resembling crawling.

  RequiredA person who lands on hands and knees and does not rise within the personal limit is a candidate; learn freezing sites and set a quieter prompt there.

• FAL-166Parkinson's disease, stroke, dementia and delirium

  A woman with dementia sits down on the floor to play with the neighbour's child's blocks and stays there for forty minutes, laughing.

  TrapA conscious person engaged in play on the floor triggers a fall alert, and the family later turns the system off.

  RequiredUse C4 and movement to see that the person is active; a seated, moving person on the floor needs a gentle prompt, and no escalation.

• FAL-185Near-falls and recovered falls

  A resident trips on a doormat in the hallway, throws out an arm to catch the wall, and straightens without touching the floor.

  TrapA fast lurch and arm swing can create a candidate that wastes a prompt and annoys the resident.

  RequiredEvaluate floor arrival; a lurch that ends upright is logged as a near fall and counted, with no prompt and no alert.

• FAL-203Near-falls and recovered falls

  After a near fall, a resident who is ashamed deletes the message that was sent to the family app and tells them nothing happened.

  TrapDeleting a notification should not remove the record.

  RequiredKeep the record in the longitudinal store; a dismissal marks the alert as dismissed but never erases the event.

• FAL-222Getting up: failed rises, partial recovery and the long lie

  Immediately after the alert is sent at 14:02, the resident stands up at 14:03 and walks to the kitchen.

  TrapA race between the alert and the recovery sends a false emergency.

  RequiredSend a closing message at once when recovery is confirmed, stating the time on the floor and the time of recovery.

• FAL-240Mimics: deliberate lowering, floor sitting and lying down

  A woman sits on the floor beside the bed of her sick husband all night, holding his hand and dozing against the mattress.

  TrapA woman asleep on the floor at night resembles a collapse, and the husband in bed may also need attention.

  RequiredLearn caring routines; verify with C4 for sleep and use the prompt, and keep a lower-intensity alert if the husband's state is also being monitored.

• FAL-259Mimics: prayer, puja, namaz, yoga, rangoli and massage

  During a bhajan evening at home, thirty guests sit on the floor for two hours, and an elderly host slumps sideways against a neighbour and stays there.

  TrapIn a crowd of seated bodies, one slumping is lost among many.

  RequiredTrack individual posture changes within a crowd and flag a slump with loss of micro-motion; the alert states that visitors are present.

• FAL-277Mimics: children, grandchildren, pets and animals

  A child running through the room collides with a grandmother carrying tea, and she falls with the cup; the child stands crying beside her.

  TrapA crying child, a broken cup and a falling elder generate noise, and the standing child hides the fallen woman.

  RequiredKeep the elder's track as the decision object; floor arrival with no rise, even with a child present, enters the verification window.

• FAL-295Mimics: household work, furniture and falling objects

  The cook drops a stack of steel plates in the kitchen at 09:00, causing a long crash.

  TrapA loud clatter is taken as the impact of a fall.

  RequiredTreat impact sounds as supporting evidence only; with all tracks upright, the sound is logged as an object event.

• FAL-314Mimics: household work, furniture and falling objects

  The cook kneels on the kitchen floor to lift a heavy vessel from the lowest shelf, groans, and stays down for half a minute.

  TrapA groan and a kneeling pause look like a pain or collapse event.

  RequiredA kneel that ends in standing is logged only; a kneel that turns into lying or stillness beyond the limit starts the prompt.

• FAL-332Clothing, footwear, bedding and body covering

  A woman puts on her husband's oversized cardigan before going to the toilet at night, trips on the sleeve, and falls at the door.

  TrapThe garment hides her outline and slows her gait in a way the system has not seen.

  RequiredKeep the fall rule based on body mass and floor arrival; her track may be lower in confidence, so alert as a resident, probably the known person.

• FAL-351Other people: helpers, caregivers, visitors and assisted falls

  A resident falls in the presence of a hired attendant who does not speak the family's language and does not know whom to call.

  TrapA bystander who cannot act produces no help despite being present.

  RequiredThe prompt and the alert pass to the family without relying on the attendant; the in-home prompt gives simple instructions in the attendant's language if set.

• FAL-369Body, age and medical state

  A woman with urinary incontinence slips on the wet floor she herself has leaked on, on the way to the toilet, then sits on the floor ashamed.

  TrapEmbarrassment makes her cancel at once and hide the event.

  RequiredHonour the cancel; log the event and the wet floor in the record; a clinician summary may then raise continence care.

• FAL-388Floors, weather, light and the building

  A ramp built for a wheelchair at the entrance becomes slippery with algae in the monsoon, and a man slides down it.

  TrapA ramp is a sloped surface with a different height baseline from the floor.

  RequiredStore the ramp as a zone with a height gradient; a fall on it follows the standard rule.

• FAL-406Sensing failures: occlusion, multipath, fans, reflections and drift

  Two nodes in the same room both use similar sensing and are both fooled by the same ceiling fan.

  TrapTwo sources that agree because of a common cause are counted as two independent confirmations.

  RequiredAssume that error correlation is high between like sensors; corroboration must come from an independent physical source.

• FAL-424Sensing failures: occlusion, multipath, fans, reflections and drift

  After a node reboots, its clock is three seconds off, and its fall detection arrives after the neighbouring node's report of the same event.

  TrapPoor time synchronisation breaks the fusion of one fall into two unrelated events.

  RequiredSynchronise node clocks and let fusion tolerate a few seconds of skew; report a clock fault when skew exceeds the limit.

• FAL-443Power cuts, networks, updates and phones that do not ring

  A night of heavy rain makes the Wi-Fi unstable, with minutes of connection followed by minutes of loss, as a resident falls.

  TrapA flapping link makes the alert arrive late or twice.

  RequiredUse idempotent alerts with a unique identifier, retry on the best available path, and avoid duplicate calls on recovery.

• FAL-461The verification window, the prompt and the escalation ladder

  The alert says that probably the mother has fallen, but it is the father who fell.

  TrapA wrong name sends the family to the wrong room and delays help.

  RequiredSay a resident, probably X, with the confidence level, and also state the room and the number of people seen.

• FAL-480Privacy, attribution and consent around a fall

  A resident is worried that the system has a camera and asks how it detected the fall.

  TrapAn alert that implies images might cause distrust, and a statement that no images exist must be true.

  RequiredThe alert states the kinds of evidence used and affirms that no images are recorded, where this is true, and the system must be designed so that it is.

• FAL-498Falls that coincide with the other seven events

  A man gets out of bed at night and falls in the corridor before reaching the toilet, so a bed-exit watch alert is pending when the fall occurs.

  TrapA low-level watch alert and an urgent fall both exist for the same night.

  RequiredUpgrade the bed-exit alert to the fall incident and cancel the separate watch message.

• FAL-517Falls that coincide with the other seven events

  A fall happens the day after the nodes were moved during a house repair, and a fault was reported but not read.

  TrapA known coverage issue was ignored and now matters.

  RequiredEscalate unresolved coverage faults on a schedule and tell the owner, in the fall alert itself, that coverage had been reduced.

• FAL-535Aftermath, feedback and learning from falls

  Annotators who label fall events for model improvement would see the events of a household.

  TrapLabelling requires data to leave the home.

  RequiredUse only opt-in, de-identified research data (D7) with separate consent; household event records are not shared for labelling by default.

• IMM-001Sleep, naps and rest that look like collapse

  An 80-year-old man naps on the living-room sofa after a heavy lunch on a 41°C afternoon and sleeps two hours ten minutes, longer than any nap in the past month.

  TrapThe still bout passes the personal 99th percentile, so an urgent immobility alert fires on an ordinary nap.

  RequiredUse head-and-trunk posture and regular breathing-related motion (C4) to classify rest, allow a longer limit for reclined posture on hot afternoons, and log the event instead of escalating.

• IMM-019Sleep, naps and rest that look like collapse

  In the first week after hip surgery a woman is mostly in bed on pain medicine, but the system still holds limits learned before the operation.

  TrapDaytime bed rest counts as abnormal against the old baseline, and daily alerts push the family to silence the system.

  RequiredOffer a clinician or family-set recovery state with an end date, lengthen bed limits within validated caps, and keep breathing and prompt checks active throughout.

• IMM-037Prayer, meditation and ritual stillness

  A Buddhist visitor staying with the family meditates on the floor for forty minutes each evening; the visitor is not enrolled.

  TrapAn unknown still person at floor level triggers both unknown-person and immobility logic.

  RequiredHandle the guest by the resident's unknown-person setting, apply no immobility alert to an unenrolled guest in a guest-use zone, and keep the resident's own accounting separate.

• IMM-055Awake stillness: television, reading, waiting and quiet sitting

  A woman listens to a long discourse on her phone on speaker while lying with her eyes closed on the divan in the afternoon.

  TrapAudio activity suggests wakefulness while the person lies quite still, and a later collapse would be masked.

  RequiredTreat audio from devices as context only; apply the divan limit for the hour and use breathing rhythm as the primary evidence.

• IMM-073Bed-bound, palliative and end-of-life care at home

  A woman in a minimally conscious state after a brain injury shows only small movements of the fingers and eyelids, and the family is tired of daily false alerts.

  TrapLittle motion by nature produces repeated candidates that the family dismisses, and the dismissals teach the system to stay silent.

  RequiredSupport a declared minimal-movement mode: urgent alerts only on loss of breathing motion or an abrupt change, and plain reports of how often it fired.

• IMM-091Syncope, orthostatic and situational faints

  A woman stands at the stove making rotis on a hot afternoon and faints, falling beside a pan of oil still on the flame.

  TrapThe immobility rule counts a short limit, but the hazard rises faster than the limit.

  RequiredCombine auxiliary-node heat in the kitchen with a floor-level still person, treat the combination as urgent immediately, and keep the immobility timer as backup.

• IMM-109Heart, lung and breathing emergencies

  A woman with severe COPD on a high oxygen flow becomes progressively drowsy through the afternoon on her recliner, breathing slowly and shallowly.

  TrapShe is within the nap limit, and slow shallow breathing is not an alert condition on its own.

  RequiredReport a falling breathing rate or amplitude over hours as a watch item where C4 quality is good, add a prompt for a response, and escalate when she does not answer.

• IMM-127Stroke, seizures and neurological collapse

  A man has a transient ischaemic attack: his right arm goes weak and speech slurs for ten minutes on the sofa, then recovers before his son comes home.

  TrapThe episode is shorter than any limit and leaves no trace for the clinician.

  RequiredRecord a short unexplained still period as a possible transient episode in the log, notify the family at the next summary, and show the pattern to the clinician.

• IMM-145Metabolic, drug, alcohol, heat and cold causes

  An elderly man injects short-acting insulin instead of the long-acting dose at bedtime and is found unresponsive and cold-skinned in bed at 05:00.

  TrapThe sleep-period rule is off, and the restlessness that preceded unconsciousness was ignored.

  RequiredKeep the breathing-based check in the sleep period, and treat vigorous restlessness that ends in abrupt stillness as a candidate to prompt, with the family told that hypoglycaemia is a possible cause.

• IMM-163Metabolic, drug, alcohol, heat and cold causes

  A man with advanced heart failure takes an extra diuretic dose, becomes dehydrated and hypotensive, and sits motionless on the toilet chair in the bedroom for forty minutes.

  TrapA commode chair is in a private zone with limited sensing and a long personal duration.

  RequiredUse the learned commode duration and a breathing-only check in the private zone, and raise a candidate when the duration passes the personal 99th percentile.

• IMM-181Delirium, dementia and quiet illness

  A woman with dementia refuses food and water for two days and sits quietly with her mouth closed, her face turned away.

  TrapQuiet refusal is not an event, and dehydration advances while she looks calm.

  RequiredLink missed meals and low kitchen or dining activity with stillness into a watch alert on the second missed meal period, and tell the carer to offer fluids.

• IMM-199The long lie: falls and slides that end in immobility

  Lying on the floor near the fan in May, a woman becomes dehydrated after three hours, with a dry mouth and a pounding head.

  TrapHeat and floor time compound each other, and the alert does not say how long she has been there.

  RequiredInclude time on floor and room temperature in the alert, and escalate faster as the combined risk grows.

• IMM-217Where in the home it happens: rooms, thresholds and areas the system sees badly

  A woman with a squatting-toilet habit uses the Indian-style latrine and the bathroom door has a gap at the bottom, but nothing is seen inside.

  TrapBathroom sensing is limited and the entry without exit rule is the only guard.

  RequiredUse occupancy duration and entry without exit in the private zone, and escalate when the personal limit passes, as the bathroom incident rule does.

• IMM-235Hour, season and calendar: when the same stillness means something else

  During a dust storm at 17:00 in Delhi, doors and windows are closed and the power fails, and an old man waits in the dark, motionless.

  TrapDust, closed rooms and a power cut degrade several sensing capabilities at once.

  RequiredRaise quality flags for degraded capabilities, keep the posture and breathing checks that still work, and widen the limit only as far as the quality flags justify.

• IMM-253Other people and animals in the home

  A home nurse chats with a patient for two hours, then leaves the room for a phone call lasting forty minutes while the patient collapses.

  TrapThe nurse's presence earlier suggests the patient is attended, and the timer is eased.

  RequiredTreat attendance as evidence only while the carer is in the room, and restart the immobility timer when the carer leaves.

• IMM-272Whose stillness is it: attribution and occupancy accounting

  A grandchild sleeps in the grandmother's bed, then leaves at dawn, and the system's count of two becomes one.

  TrapA wrong count makes the system believe the child is still there and attribute the grandmother's still body to the child.

  RequiredRe-count at every transition, and treat a person in a bed zone after a door or zone event with no clear identity as unknown until verified.

• IMM-290Objects that look like a still person, and people who look like objects

  A 25 kg sack of wheat flour is left on a dining chair after shopping and sits there for hours.

  TrapA dense, cool, still object may be taken for a slumped person.

  RequiredUse more than shape and heat: require body-derived rhythm or entry evidence, and note absence of both as evidence of an object.

• IMM-308Sensing physics: why a still person is hard to see

  A woman lies on the floor of the hall directly beneath a ceiling fan running at its middle speed, and the blades modulate the signal at a steady frequency.

  TrapBlade-driven clutter swamps the weak signal from her still body, so she is not detected or is detected as moving.

  RequiredLearn the fan's signature per speed during installation, subtract it, and test floor stillness under each fan at sign-off.

• IMM-326Sensing physics: why a still person is hard to see

  An elderly woman sits in the verandah in a transparent plastic raincoat after rain, and the plastic reflects strongly.

  TrapA strongly reflective covering changes the apparent size and strength of the body signal.

  RequiredFlag unusual reflectivity as a quality issue when seen and rely on posture and rhythm rather than amplitude.

• IMM-344Breathing evidence: what contactless sensing can and cannot confirm

  A resident turns from her back to her side after twelve minutes of stable breathing, and the signal is lost for two minutes.

  TrapA lost reading after a turn is read as absent breathing.

  RequiredDistinguish loss of signal after a movement from absence, wait for the learned re-acquisition time, and report as not measurable meanwhile.

• IMM-362Living alone and discovery delay: the long unseen interval

  A woman who lives alone dies on a day when her helper is on leave, and the helper returns two days later.

  TrapThe helper is the only routine visitor and her absence removes the usual discovery.

  RequiredTreat a helper's expected visit that does not occur as context, and tighten watch alerts while the resident is alone without scheduled contact.

• IMM-380Limits, baselines and personalisation

  A festival weekend with relatives produces a single eight-hour still bout on the sofa, and the 99th percentile for that zone jumps.

  TrapOne unusual bout inflates the limit for months.

  RequiredUse robust statistics and exclusion of days flagged as unusual by calendar context, and require several bouts to move the percentile.

• IMM-398Limits, baselines and personalisation

  A woman with dementia has no stable routine, so her still-bout distribution has a very long tail and a limit near the cap.

  TrapA limit near the cap protects little, and the tail is wide.

  RequiredApply capped limits, rely more on posture and breathing evidence and on prompts, and say plainly in the enrolment that the system is less reliable for her.

• IMM-416Escalation failures: when the alert goes out and nothing happens

  A family WhatsApp group of twenty people receives the alert and each person assumes someone else is responding.

  TrapDiffusion of responsibility in a group delays action.

  RequiredName one responsible person per alert, require an individual acknowledgement, and send follow-up calls to named individuals, not the group.

• IMM-434The local prompt and the resident's answer

  A man with dementia hears a voice from a box in the room and believes a stranger is in the house.

  TrapThe prompt causes fear and he hides or shouts.

  RequiredUse a familiar short phrase and a gentle chime, offer a settings option for no voice prompts, and rely on the button and the family call.

• IMM-452Privacy, consent and dignity at the moment of an event

  The alert text says "on the floor of the bathroom, not moving" and appears in a family WhatsApp group that includes in-laws and a cousin.

  TrapA private emergency is disclosed to many who do not need to know.

  RequiredSend alerts only to named recipients, never to a group, and keep the content to what the recipient needs to act.

• IMM-470Privacy, consent and dignity at the moment of an event

  A woman asks that the monitor not record her in the 30 minutes after a bath when she dresses, but she tends to rest then.

  TrapA private interval is also a risk interval.

  RequiredAllow a timed private window with a maximum length and an automatic resume, and tell her what the system cannot see during it.

• IMM-488Power, network and software states during a still period

  A gecko makes a nest behind a node and short-circuits it with droppings and its body.

  TrapA common household animal damages the hardware and causes silent failure.

  RequiredInclude pest checks in maintenance, detect intermittent faults early, and place nodes where pests cannot nest.

• IMM-506Aftermath, recovery and several events at once

  A resident who collapsed in the bathroom is found by her son and moved to the bedroom, still unconscious.

  TrapThe incident moves zones and the system treats it as two events.

  RequiredFollow the person through zones with layer B continuity, keep a single incident open, and update the location in the alert.

• IMM-524Confusion with the other seven events

  A resident has been in the bathroom for forty minutes without movement, longer than her usual twelve.

  TrapThe bathroom incident and the immobility rule have different limits, and the more permissive one may govern.

  RequiredLet the bathroom incident rule take priority in the private zone, with its own limit, and carry its evidence into the immobility alert if both are open.

• BTH-001Fainting and collapse on the toilet

  A 72-year-old man strains at the commode on a constipated morning, loses consciousness for twenty seconds, slumps against the wall and wakes confused, still seated upright.

  TrapNo fall is seen, and a still seated body looks like a long toilet visit.

  RequiredTreat no gross movement beyond the short-visit limit as a candidate incident whatever the posture; use breathing-related motion (C4) to set urgency and start a local prompt.

• BTH-018Fainting and collapse on the toilet

  A 62-year-old woman has a panic attack in the bathroom, breathes fast, her hands cramp, and she sits on the floor against the door.

  TrapFloor sitting with rapid breathing looks like a collapse and is not one.

  RequiredRapid breathing (C4) with preserved voluntary movement is a watch-level observation; send a calm local prompt first and avoid an urgent alert if she responds.

• BTH-036Slips and falls on wet floors

  A tap is left open after a fall; water overflows from the bucket into the corridor and under the bedroom door.

  TrapThe flood is noticed before the person, and a water alarm alone sends a maintenance message.

  RequiredFuse a water-on-floor cue from an auxiliary node with bathroom occupancy; occupied plus overflow plus no movement is an urgent bathroom incident.

• BTH-054Squat toilets, low stools and getting up from the floor

  A man of 78 cannot rise from the floor after a fall because the squat pan has no support; he stays sitting at the edge of the pan for an hour.

  TrapHe is conscious and moving a little, so no stillness is seen; the long lie goes unreported.

  RequiredFailure to regain upright posture within the window is the incident, not stillness; a person at floor level after the window is escalated.

• BTH-072Hot water, long baths and heat illness

  A man of 80 drops an electric immersion rod into a bucket of bathing water, touches the bucket, is shocked, falls and lies still; the circuit breaker trips and the house goes dark.

  TrapA power loss that also takes the sensing node offline hides the incident.

  RequiredNodes in wet zones need battery backup; if the bathroom node goes offline while occupied, treat entry without exit as the evidence and alert at short latency.

• BTH-090Gas geysers and carbon monoxide

  A couple in their sixties share a flat with a flueless LPG geyser in a closed bathroom; the wife is overcome, and the husband enters to help and is overcome too.

  TrapTwo people collapse in one event, and an alert about a single resident is incomplete.

  RequiredAlert urgently with the count of occupants and a warning not to enter without ventilating the room; the carbon-monoxide cue (C7) is placed first in the message.

• BTH-108Gas geysers and carbon monoxide

  A woman of 69 has a seizure-like episode in the bathroom during a bath, thrashing against the wall for a minute and then lying still.

  TrapConvulsion, then stillness: a seizure from epilepsy or from carbon monoxide cannot be told apart by motion.

  RequiredRaise the incident as for any convulsion and stillness; if C7 shows carbon monoxide, state it first in the alert so the responder ventilates before entering.

• BTH-125Steam, running water, mirrors and tiles

  Water pipes clank as the geyser heats, and the noise is mistaken for a fall impact.

  TrapA pipe noise labelled an impact starts false fall candidates.

  RequiredRequire posture evidence for a fall; learn recurring pipe noises per home and discount them.

• BTH-143Long stays that are normal

  A woman of 70 in a joint family takes calls from her daughter abroad inside the bathroom, the only room with a lock and a quiet corner, for forty minutes.

  TrapA call is invisible to the system and the stay looks like an incident.

  RequiredOpen a local prompt after the personal limit; a spoken or button reply closes it, and repeated calls are learned as a routine.

• BTH-161Long stays that are normal

  A woman of 75 hides in the bathroom when a stranger knocks at the front door during the day and stays until he leaves.

  TrapA stay linked to a door event looks like a normal long stay.

  RequiredLink bathroom duration with front-door events (C9) and context; if the unknown-person event resolves, the stay ends and the prompt is dropped.

• BTH-179Entry without a detected exit

  A 74-year-old woman leaves one attached bathroom and enters the second one, in the guest room, because the first is being cleaned.

  TrapExit from one room and entry to another look like two separate visits and a shifted baseline.

  RequiredHandle each bathroom as its own zone and treat the move as a transit; an unusual choice of bathroom is logged, not alerted.

• BTH-197Locked, jammed and inward-opening doors

  The flat's front door is chained from inside after the resident falls in the bathroom.

  TrapResponders arrive and cannot enter the flat at all.

  RequiredRecord the chain and bolt state from door sensors where fitted and tell responders; list the neighbour's balcony route or fire service access if known.

• BTH-215Incontinence, nocturia and toilet routines

  A woman of 69 avoids drinking after 5 p.m. and does not go to the bathroom at night for a week.

  TrapZero night visits looks like better sleep or a reduction in activity.

  RequiredReport visit counts with context; no night visit is not an alert, and a sharp change in routine is recorded for review.

• BTH-232Night-time bathroom visits

  A man of 74 returns from a wedding at 1 a.m., vomits in the bathroom, and falls asleep on the floor beside the toilet.

  TrapLying on the floor at night is a post-fall posture, and he is also drunk.

  RequiredA lying posture on the bathroom floor opens the verification window with a prompt; breathing motion present and a prompt reply close it, and a drunk sleeper is logged at watch level.

• BTH-250Assisted bathing and caregivers in the room

  The nurse steps out to fetch a towel and leaves the patient seated on the shower chair for five minutes.

  TrapA person left alone on a chair is at risk of sliding, but the rule sees a short stay.

  RequiredWhen the second person leaves, the stillness rule resumes at once with a short limit for patients who cannot stand unaided.

• BTH-268Assisted bathing and caregivers in the room

  A helper uses the bathroom while the resident waits, and the resident enters right after, so the bathroom sees four entries within five minutes.

  TrapRapid entries and exits mix up attribution and clocks.

  RequiredUse occupancy accounting and the enrolled-carer list; attribution is held at moderate confidence, and no stay clock runs for an unattributed track.

• BTH-286Dementia, delirium and mental health

  A resident with dementia flushes clothes down the toilet and wades through overflowing water.

  TrapOverflow, noise and activity are classified as a plumbing problem.

  RequiredCombine water on the floor and a person in the room as urgent, and check posture for a fall in the wet area.

• BTH-304Medical conditions and their presentations

  A man of 71 passes black stool and feels faint, then slides to the floor of the bathroom.

  TrapA gastrointestinal bleed shows only as a faint and a long stay.

  RequiredAlert on the fall or stillness; the system does not infer cause, and the first contact is asked to call a doctor if the person responds weakly.

• BTH-322Privacy limits inside the bathroom

  Two flats have back-to-back bathrooms on a thin plumbing wall, and the radar sees the neighbour's family.

  TrapThe neighbour's people are treated as residents in the home.

  RequiredRun boundary tests at shared walls during installation, and drop anything outside the envelope at P1; a node that leaks beyond the wall is re-sited or masked.

• BTH-339Who is in the bathroom

  An elderly couple, both enrolled, sleep in one bedroom, and one of them enters the bathroom in the dark at 2 a.m.

  TrapWithout identity sensing, the wrong spouse's limits and contacts may be applied.

  RequiredAttribute by bed-side prior and bedroom exit (layers B and E), state "a resident, probably X" with confidence, and apply the shorter of the two limits until re-anchored.

• BTH-357Who is in the bathroom

  A resident returns from a three-week trip and the system's priors, learned over months, no longer fit his new routine.

  TrapOld priors misattribute his first days back.

  RequiredReduce prior weights after a long absence and recover quickly with anchor passes.

• BTH-375Pets, children, animals and objects

  A stray dog enters the home through a gate left open and settles in the bathroom.

  TrapAn unexpected animal in the home could trigger an unknown-person event.

  RequiredClassify non-human tracks as animals; the unknown-person rule applies only to person-sized, person-moving tracks.

• BTH-393Clothing, devices and assistive equipment

  An adult diaper under a nightgown changes the hip contour and thermal profile.

  TrapA bulky garment shifts the model's body outline.

  RequiredInclude diapers and bulky night clothing in training and testing, and use persistence over outline.

• BTH-411Escalation failures and alert content

  After a false alarm in the morning, the family dismisses the evening alert by reflex.

  TrapAlarm fatigue turns a real event into a dismissed one.

  RequiredShow the evidence and breathing observation in the alert, track dismissal speed per recipient, and re-escalate when the stillness continues after a dismissal.

• BTH-429Power, network and infrastructure

  A helper switches off the exhaust fan socket after cleaning, and the node hangs from the same socket.

  TrapThe node is silently off for days.

  RequiredUse a dedicated supply and show the node's state in the owner's app, with a daily health message.

• BTH-446Building, climate and shared bathrooms

  Water supply to the flat is cut for two days, and a man of 76 carries buckets from a drum in the passage to the bathroom.

  TrapCarrying heavy buckets is a fall risk and changes bathroom routines.

  RequiredTreat water supply state as context if known; a fall while carrying is evaluated as usual, and the change in routine is noted in the longitudinal record.

• BTH-464Building, climate and shared bathrooms

  A strong gust through the open bathroom window slams the door and the sound resembles an impact.

  TrapA door slam is classified as a fall impact.

  RequiredRequire posture evidence and treat a slam correlated with a door event as noise.

• BTH-482Tampering, installation and maintenance

  A node mounted on a plastic clip falls into a bucket of water on the floor.

  TrapA fallen node produces a fault and a wet sensor.

  RequiredDetect a fall of the node by acceleration or pose change, flag reduced coverage, and require a pose check.

• BTH-500Confusion with the other seven events

  A grandchild's friend uses the bathroom and the system cannot tell if the person is the child, a guest or an intruder.

  TrapAn unknown short visit raises an unknown-person event.

  RequiredApply the guest setting and the time pattern; a short bathroom visit by a person who entered with a resident is logged and not notified.

• BTH-518Recovery, aftermath and follow-up

  A resident returns home after three weeks in hospital with a walking frame.

  TrapThe baseline of the previous months no longer fits.

  RequiredStart a cold-start period with reduced claims, and mark the first weeks for clinician review.

• BED-001Night toilet trips that run long without being an emergency

  A 72-year-old man with an enlarged prostate stands at the toilet for eleven minutes at 02:00 waiting for the stream to begin, then walks back to bed.

  TrapA fixed ten-minute limit raises a watch alert on a routine night.

  RequiredUse the limit learned from his own night trips, whose long tail includes hesitancy. Log the trip and send nothing when he returns within it.

• BED-018Night toilet trips that run long without being an emergency

  A man whose trips average four minutes has never exceeded nine, so after two weeks his limit is eleven minutes. One night the lights fail and he searches fifteen minutes for his spectacles.

  TrapA tight learned limit fires on a rare, harmless night.

  RequiredSet a floor under every limit that reflects the slowest plausible trip, and add a grace period while the person is located and moving. Send watch at most.

• BED-036Waking for reasons other than the toilet

  An anxious woman checks the main door lock and the window latches three times a night, each round taking about two minutes.

  TrapRepeated approaches to the door read as attempts to leave the flat.

  RequiredLearn the checking round as her pattern. Require an open-door event (C9) and an occupancy drop for any exit rule, and report rising counts as a trend.

• BED-054Sleeping somewhere other than the bed

  A man on a farm house sleeps on a charpai in the courtyard in July and goes into the verandah at the first rain, dragging his bedding.

  TrapSleep moves between outdoors and indoors in minutes, and the indoor node sees a sudden arrival.

  RequiredLearn that a rain trigger can move him in. Treat an arrival with bedding as the same sleep episode and do not count it as an unknown person.

• BED-072Couples sharing a bed: whose exit is it?

  The monitored wife falls in the bathroom at 03:00. At 03:20 her husband, who woke and looked for her, returns to the bed alone.

  TrapThe system sees someone enter the bed and counts it as her return, ending the event.

  RequiredA return must be attributed to the person whose clock is running. Occupancy accounting (layer C) shows one person in bed, so her track stays open and her clock continues.

• BED-089Couples sharing a bed: whose exit is it?

  A wife rolls onto her husband's pillow and her head lies for three hours at the spot where the sensor expects his breathing.

  TrapBreathing rate from the wrong body is attributed to him, hiding a change in her.

  RequiredAttribute breathing signals to a person by position and track. If bodies overlap, mark breathing-related motion as unattributed instead of guessing.

• BED-107Dementia and night-time wandering

  A woman with dementia sleeps well for six nights and then wanders on the seventh after a visitor leaves the house.

  TrapA weekly wandering rate is too low to learn from, and the rule treats the seventh night as noise.

  RequiredKeep wandering rules independent of the learned baseline. Judge each night against patterns in her record, and flag a first wandering night as a change.

• BED-125Sundowning, delirium and confusion on waking

  A woman with delirium wakes at 04:00 and tries to leave the flat in her nightdress with her purse, saying she must go to her mother.

  TrapA bed exit followed by a door attempt is an exit logic matter, and the bed rule is already behind the event.

  RequiredMerge bed and exit evidence into one incident with the time out of bed. Raise the local prompt, and notify the first contact at once.

• BED-143Real emergencies on the night trip

  A diabetic man wakes sweating at 03:00, goes to the kitchen to look for sugar, and collapses on the floor beside the refrigerator.

  TrapOut of bed and located in the kitchen, so he appears to be on a routine trip.

  RequiredApply the immobility and fall rules wherever he is. A person located at floor level and still, in any zone, ends the routine-trip interpretation and goes to urgent.

• BED-160Bed-edge and in-bed events

  A woman sits on the edge of the bed for forty minutes after waking, dizzy, with her feet on the floor and her hands on her knees.

  TrapShe is neither in bed nor out of it, and no exit occurs.

  RequiredRecord a bed-edge episode as its own state. Apply a sitting limit learned from her history, and prompt if she has not stood or lain down within it.

• BED-178Bed-edge and in-bed events

  A woman reaches across the bed to pull her sleeping husband's blanket up, kneeling on the mattress, and the two bodies overlap.

  TrapOverlapping bodies create a large shape that the system reads as an unfamiliar event.

  RequiredUse track separation and occupancy accounting. A short overlap of two known occupants is not an event, and neither exit clock starts.

• BED-196Hospital beds, bed rails and bedside equipment

  A resident wedged between the raised rail and the mattress edge lies still with her head towards the gap.

  TrapA person in the bed zone, still, is read as asleep in the sleep period.

  RequiredCombine breathing-related motion with posture. A still body in an entrapment position, particularly with absent or laboured breathing signs, triggers urgent prompt and first-contact call.

• BED-214Medical conditions and medicines that change the night

  A man on an alpha-blocker for the prostate feels dizzy on rising at night and sits back down on the bed edge for several minutes, repeatedly.

  TrapRepeated failed stands look like a stuck exit.

  RequiredTreat a failed stand followed by a successful one as a near exit. Log it, and escalate if he does not rise within his personal limit.

• BED-231Insomnia, low mood and worry at night

  A woman who suffers nightmares wakes screaming at 01:00, runs to her daughter-in-law's room, and sits at the foot of her bed.

  TrapA person in another bedroom at night may be flagged as an intruder or as a disorientation event.

  RequiredAttribute the person as the resident. Keep a night visit to a family bedroom at log and protect the other person's privacy by recording only the resident's track.

• BED-249Prayer, fasting, festivals and other Indian night practices

  During the thirteen days of mourning a man sleeps on a mat on the floor of the hall as custom requires, with relatives close by.

  TrapA bed that is never used and a floor mat make a new pattern.

  RequiredLet the household mark a mourning period. Accept the floor mat as the sleep place, and keep the safety rule for a still body away from the mat.

• BED-267Other people and animals in the home at night

  A ten-year-old grandchild who sleeps over gets up three times a night for water and the toilet, walking the same route as the grandmother.

  TrapA small body on the same route is attributed to the grandmother, and her exit count rises.

  RequiredUse body size and gait to separate the child, and enrol the child as a household member so that tracks are not mixed.

• BED-285Other people and animals in the home at night

  A woman's pet dog sleeps in the bathroom and lies still on the floor at 01:00 while she is in the toilet.

  TrapA body at floor level in the bathroom is seen as a person fallen, or the dog's stillness as the woman's.

  RequiredUse body size to separate the dog from the woman. The bathroom rule applies to the person's own track only.

• BED-303Heat, monsoon, cold and the building itself

  A lift is out of service in a high-rise at night and an elderly woman who has left the flat to look for her neighbour cannot climb the stairs back.

  TrapOutside the flat she is beyond the envelope, so only the door event shows she left.

  RequiredUse the exit logic for the departure and the time since leaving bed. Notify the first contact quickly, since she cannot return unaided.

• BED-320Power cuts, backup and the connectivity chain at night

  The inverter battery lasts four hours, so a cut starting at midnight leaves the home dark and unsensed after 04:00, when the resident wakes for prayer.

  TrapThe system dies just before the likely wake-up.

  RequiredReport remaining backup time to the owner during a long cut. Switch to a reduced mode on low power that keeps the central node and the sleep route alive.

• BED-338When the bed state itself is wrong

  Cold air from a split air conditioner blows across the bed and moves the blanket and the mosquito net all night.

  TrapCloth motion adds noise and may make a still sleeper look restless.

  RequiredSeparate cloth motion from body motion by pattern and frequency. Lower the quality flag for restlessness measures, and do not count cloth movement as a bed exit.

• BED-356When the bed state itself is wrong

  A cat sleeps on the resident's chest all night, adding a heavy warm lump that moves with her breathing.

  TrapBreathing and heat are attributed to the cat or doubled.

  RequiredClass the cat by size and temperature and exclude it from the person's signal. Mark the breathing estimate with a lower quality flag.

• BED-374Learned limits and thresholds: where the numbers fail

  After a week in hospital a woman returns home weaker and takes twice as long to move.

  TrapThe old baseline fits poorly, and new alerts appear nightly.

  RequiredOffer a re-baselining step after hospital discharge, with the household's confirmation. Keep the fall and immobility rules at their safety floors meanwhile.

• BED-391Escalation at night: prompts, contacts and keys

  A half-asleep woman presses the cancel button by reflex at 03:00 and goes back to sleep on the bedroom floor.

  TrapA cancellation by a confused person is honoured, and the event ends.

  RequiredHonour a cancellation but keep observing. If she is at floor level ten minutes later, send a watch message stating exactly that.

• BED-409Escalation at night: prompts, contacts and keys

  A watch alert for a night bed exit is held for the morning summary because it is classed as low priority.

  TrapA real event found low and still is reported at breakfast.

  RequiredKeep watch events that can become urgent out of the batched summary. A night exit with no location or with low posture goes up the ladder at once.

• BED-427Privacy, dignity and consent at night

  The cloud copy of nightly summaries is kept for two years and a former family nominee still has access.

  TrapA person who is no longer authorised can read private history.

  RequiredReview access when nominees change, and remove access at once on request. Set retention limits and show the resident what is stored.

• BED-445Alarm fatigue and tuning for the night rule

  A resident turns off the node's power at night because its light disturbs her sleep.

  TrapA nuisance causes the household to disable protection.

  RequiredProvide a dark mode with no visible light at night. Detect power-off and tell the owner, and discuss the cause with the household.

• BED-462Confusion with the other events, and events that combine

  A resident leaves for the toilet at 02:00, and during the trip the inverter fails and the corridor node resets.

  TrapA short trip and a system fault overlap, so the trip's end is not seen.

  RequiredMark the unobserved interval as a system event. After recovery use occupancy accounting to find the resident and ask the first contact to check if she is not located.

• BED-480Confusion with the other events, and events that combine

  A resident leaves bed and the nurse's aide in the next room logs it manually in a notebook at the same moment.

  TrapA paper record and the system disagree on the time of events.

  RequiredTreat the aide's note as a label. Compare times, store the difference and use it to check clock accuracy.

• BED-498After the alert: outcomes, labels and records

  A wrongly stored event shows a resident awake at 03:00 on a night when she was away.

  TrapA false entry corrupts the record.

  RequiredDetect inconsistency with the away state and remove or flag the entry. Give the household a way to report errors and see them corrected.

• BED-516Installation, maintenance, tampering and updates

  A replacement node installed under warranty has no learned profile and uses default thresholds.

  TrapA replaced unit starts as if it were a new home.

  RequiredRestore the home's learned settings from the hub. If they cannot be restored, say that the unit is in learning mode and keep rules conservative.

• EXI-001Dawn and night routines that are legitimate

  A 78-year-old woman has walked to the Shiva temple at 04:30 every day for forty years and returns by 05:45. The system went live last week and has no routine yet.

  TrapDuring cold start every dawn exit looks unexpected, so a watch alert fires daily and the family starts ignoring them.

  RequiredEnrolment records declared habitual outings with approximate times and seeds the routine profile from them. During cold start an unmatched exit is logged and shown to the resident, not alerted.

• EXI-019Dawn and night routines that are legitimate

  A 72-year-old widow, newly arrived to live with her son in Pune, begins walking at 05:00 in the housing society compound because she did the same in her village.

  TrapA routine moved from another home has no local history, so it appears unexplained to the new household.

  RequiredInclude a first-month question at enrolment about habits brought from elsewhere and treat the first few matching exits as learning evidence, not alerts.

• EXI-037Brief exits to the doorstep, corridor and compound

  A 71-year-old woman tosses a coin to the beggar who comes to the grille every Thursday night at 21:30, speaks briefly and shuts the door.

  TrapA weekly visitor at the door is misread as a person entering or an exit followed by a return.

  RequiredLearn periodic visitors at the threshold and treat entries to the doorstep zone as not changing the home count; report only changes beyond the doorstep.

• EXI-055Exits in response to a disturbance

  A smell of burning plastic from the neighbouring flat wakes an 81-year-old man at 04:10; he bangs on that door and then goes down to call the guard.

  TrapA genuine neighbourly rescue is classed as a night exit with an unknown reason.

  RequiredKeep watch level but compose the message from facts only: time, door, duration so far; add that the building security desk is a registered nominee who can check at once.

• EXI-074Genuine wandering and exit-seeking in dementia

  A resident of 80 with Lewy body dementia sees children in the corridor at night and goes out to feed them, returning after fifteen minutes, hallucinating.

  TrapA hallucination-driven exit looks like a normal short outing, hiding a clinical change.

  RequiredReport a new night-time exit pattern to the clinician pathway as a change in night activity, labelled as an observation and not a diagnosis.

• EXI-092Delirium, acute confusion and sleep disruption

  A 76-year-old woman with fever and dehydration during a heatwave becomes confused at dusk and tries to leave to find her late husband.

  TrapA hot day, an infection and an exit combine; the leaving alert alone misses the medical emergency.

  RequiredMerge the exit with high ambient temperature, bed-exit and breathing-rate context into one incident; the message lists them and recommends checking her health as well as her whereabouts.

• EXI-110Medical events that begin with a walk to the door

  A 73-year-old man with vertigo steadies himself on the grille during an attack and ends up lying in the passage with the main door ajar at 04:20.

  TrapA person lying in the passage outside is outside the sensing envelope, and the door-ajar state gives only a vague signal.

  RequiredA door left open with no resident presence inside should raise the watch level in minutes and, with no return, escalate; the message asks the first contact to check the passage.

• EXI-129Flat doors, grilles and latches

  An old-style Godrej cupboard stands by the door and an 81-year-old man squeezes past it with a walker, hitting the door and the cupboard on each trip.

  TrapRepeated collisions and a narrowed passage create noisy door events that look like struggles or intrusions.

  RequiredTreat impact-like door events with an attributed track as ordinary, and let the installer log furniture near the door in the home map.

• EXI-147Lifts, stairwells, terraces and balconies

  A resident of 71 who lives on the ninth floor takes the stairs down to avoid a broken lift, rests on every landing, and sits on the fourth floor landing for forty minutes.

  TrapA long stay on a landing is an exit with no motion; a fall or exhaustion looks like rest.

  RequiredExtend the overdue bound with the stair-climbing context but do not remove it; at the bound the message asks that someone check the stairwell and the landing.

• EXI-165Housing society gates, guards and shared spaces

  A resident of 68 walks the society's perimeter path at 05:00 for exercise, where CCTV cameras operated by the society record him.

  TrapHis walking is outside SAHARA's remit but is recorded elsewhere, and the family may assume both systems share data.

  RequiredState clearly in the consent notice that SAHARA does not use or receive society CCTV, and that its record of the exit is only the door event and count change.

• EXI-184Door-sensor failure modes

  A Zigbee door sensor drops off the network when the Wi-Fi router is switched off at night to save power or to stop radiation, as some families do.

  TrapEvery night-time door event is lost because of a deliberate habit, and the system reports normal.

  RequiredKeep the door channel on a path independent of the household router; when the link is lost the central node marks door evidence as unavailable and tells the household.

• EXI-202Occupancy count failure modes

  At 22:00 a 70-year-old man is in the steamy bathroom while his son leaves for the night shift; the bathroom sensing is degraded by steam.

  TrapThe bathroom occupant cannot be seen, so the count drops to zero and the man appears to have left.

  RequiredWhen a person entered a zone and no exit was seen, keep them there with decaying confidence; do not declare a leaving event from a count drop alone.

• EXI-220Occupancy count failure modes

  The count is 2 at midnight; at 02:00 a 76-year-old man walks out while the node serving the entry hall has a dust-obscured view and misses him.

  TrapOcclusion at the entrance lets a departure pass without a count change.

  RequiredA door event with no matching count change must raise a check of the entrance node's health and a prompt for the first contact to confirm, not be ignored.

• EXI-238Attribution: who actually left

  The resident wears her husband's old shawl and woollen cap at night, and the sensing at the door reads the clothing as his outline.

  TrapBorrowed clothing misleads an appearance-based match.

  RequiredDo not use clothing-dependent features for attribution at the door; layers B and C carry the decision and the message states the layers used.

• EXI-257Visitors, helpers and the rest of the household at night

  A 69-year-old man living in a rented room shares a toilet with three other tenants and uses the corridor door at night, often leaving it ajar.

  TrapSeveral households' door traffic mixes in the corridor, and his door state seems to have constant night activity.

  RequiredDefine the dwelling door narrowly; shared-corridor door events are context only, and the home count changes only when presence leaves the dwelling zone.

• EXI-275Pets, birds and other animals

  A large dog sleeps next to a 76-year-old man and follows him to the door when he opens it; the count rises twice in a minute.

  TrapA dog's size and motion counted as a person produce a false count and a false entry.

  RequiredSeparate non-human tracks using size, height and gait; a dog's movement never changes the people count, and the household's dog is registered as a pet in the home model.

• EXI-293Routine, calendar, festivals and travel

  During Durga Puja in Kolkata a 76-year-old woman goes pandal-hopping with relatives until 03:00 on three nights.

  TrapSeveral nights of late returns shift the baseline, and ordinary nights afterwards seem too early.

  RequiredTreat the festival as a declared period that is excluded from sleep baselines or annotated; the baseline resumes unchanged afterwards.

• EXI-312Routine, calendar, festivals and travel

  A 67-year-old woman attends the early shift at a factory canteen three days a week from 04:30 and cooks for the day.

  TrapEmployment of an older person is not assumed; her exit looks like night leaving.

  RequiredTreat declared work as a routine class; never infer retirement. The sleep period learned from her own bed use sets the unexpected window.

• EXI-330Power, network and phone failures

  A hearing-impaired husband of 78 is the only first contact for his wife, and the voice call does not wake or inform him.

  TrapA contact with hearing loss misses voice alerts.

  RequiredUse vibrating or visual alerts for such contacts; the household is told that a single hearing-impaired contact is not enough and a second nominee is required.

• EXI-348Escalation and response failures

  A first contact has muted the app after six leaving alerts in a month that proved to be walks, and an alert on the seventh night is not read.

  TrapAlarm fatigue turns a real alert into a silent one.

  RequiredTrack the household's precision from labels; when false watch alerts exceed the budget, tune the personal rule and message the system owner before the family stops listening.

• EXI-367Privacy, dignity and misuse of the exit record

  A flat owner who pays for the system as system owner asks to see when his tenant, a 74-year-old widow, goes out at night.

  TrapA payer's interest in the tenant's movements is a misuse and a tenancy matter, not safety.

  RequiredThe payer sees device health only; a resident's events go to nominated contacts she chooses, and the owner has no access to the exit record.

• EXI-385Privacy, dignity and misuse of the exit record

  A family uses the record of a resident's night exits as evidence in a guardianship petition against her wishes.

  TrapA care record becomes a weapon in a dispute.

  RequiredRecords are released for such uses only on lawful order and legal advice; the resident is told of any request, and the system adds no interpretation to the data.

• EXI-403Capacity, consent, guardianship and the law

  A resident has capacity but fears falling and agrees to alerts; her husband, also a resident, declines and does not want his exits recorded.

  TrapOne partner's consent cannot cover the other, yet their movements are interlinked.

  RequiredMonitor each person separately; the husband's exits are counts only and he is treated as an unenrolled co-resident.

• EXI-421Confusion with the other seven events

  A thief covers the door node with tape before breaking in at 03:00, and an unknown person enters the flat while the resident sleeps.

  TrapTampering hides the intrusion and the entry is not seen at the door.

  RequiredA covered or blocked sensor is a tamper event raised at once; the count rising with no door event adds an unknown-person condition to the same incident.

• EXI-440Return, aftermath, labels and alarm fatigue

  Three nights in a row a resident returns after 20 minutes and the family dismisses each alert without a label.

  TrapUnlabelled dismissals teach the system nothing and make the next alert easier to ignore.

  RequiredAsk for a one-tap label on each closing message; unlabelled episodes are shown in the weekly summary as 'not labelled' and not used to tune thresholds.

• EXI-458Leaving after conflict, distress or abuse

  After a quarrel with her daughter-in-law at 23:00, a 74-year-old woman puts on her shawl and goes to a neighbour's flat down the corridor.

  TrapA short, emotional exit looks like any other exit and the reason is invisible.

  RequiredSend no alert for a short outing that ends inside the personal limit; if she does not return by the bound, the overdue message is neutral and gives no cause.

• EXI-476Weather, season and clothing at the door

  Dense fog at 06:00 in Amritsar cuts visibility to twenty metres, and a 78-year-old man leaves for the gurdwara by foot along a road with trucks.

  TrapA routine exit becomes hazardous because of road visibility, which the system cannot see.

  RequiredIf a fog warning is available as context, add it to the watch message and shorten the overdue bound; do not discourage a habit the system cannot judge.

• EXI-495Assistive devices, equipment and the body at the door

  A 79-year-old woman walks to the front door with a four-legged walker at 03:00, and the walker is seen as a second object beside her.

  TrapThe aid inflates the count, so the exit seems to be by two people.

  RequiredLearn each resident's aids as part of her track at enrolment; an aid never adds to the people count.

• EXI-513Sensing artefacts around the entrance

  An iron safety grille across the door produces strong reflections whenever a person walks near it at night.

  TrapReflections from a metal grille create phantom tracks or shifted positions.

  RequiredSurvey the door zone with a person walking through it at installation; accept the node placement only when counts and positions are stable.

• EXI-531Sensing artefacts around the entrance

  A phone hotspot used by a visiting grandson saturates the 2.4 GHz band in the hall at night.

  TrapRadio congestion causes dropped door messages.

  RequiredMonitor link quality on the door channel; congestion is reported as degraded, with exits confirmed by count.

• UNK-001Domestic helpers, cooks and drivers

  A part-time maid arrives at 07:10 every day, sweeps and mops every room including the bedroom while the resident bathes, and leaves by 08:30. The household set notify for unknown persons at all hours.

  TrapSeven false notifications a week; the family mutes the app and misses the first real intruder.

  RequiredOffer an expected-visitor window of 07:00 to 09:00 at setup. Inside it, log only the count and zone, with no identity. Outside it, the notify setting stays active.

• UNK-018Domestic helpers, cooks and drivers

  The maid's phone rings and she walks out onto the terrace at 08:20, closing the door. The count drops from two to one, and the resident sits alone at the dining table.

  TrapA departing track is attributed as the resident leaving, or as a door event with an occupancy change.

  RequiredHold the departure as unattributed and let continuity and occupancy accounting say that the resident remains at the table. Raise no leaving-home event, because the resident's track never crossed the door.

• UNK-036Delivery, utility and service callers

  An AC technician spends forty minutes on a stool in the bedroom cleaning the unit and then spends ten minutes in the balcony fixing the outdoor unit hanging from the grille.

  TrapA long visit through private and balcony zones accumulates presence time until it crosses an overstay limit.

  RequiredUse per-zone overstay limits learned from the expected job. A scheduled service window set by the owner for that day is allowed to be long, and expires at its end.

• UNK-054Nurses, physiotherapists, doctors and other care visitors

  A resident walks with a physiotherapist and nearly falls, and she catches him. His height drops quickly then recovers within three seconds.

  TrapA caught near-fall is logged as a fall with no recovery check by a second person, or ignored as therapy.

  RequiredLog the near-fall as a candidate that closes on recovery. Record it in the longitudinal record as a near-fall with a therapy flag, not an urgent alert.

• UNK-072Nurses, physiotherapists, doctors and other care visitors

  An ayurvedic practitioner visits to apply a medicated oil treatment and has the resident sit under a hot towel on a stool in a closed bathroom for twenty minutes.

  TrapHeat, steam and a stranger in a closed bathroom combine to degrade presence sensing and raise a possible bathroom incident.

  RequiredCheck the bathroom node health at entry, widen the duration rule, state the degraded confidence in any alert, and treat the second body as a visitor, not as a resident entry.

• UNK-090Relatives, neighbours and friends

  A cousin with a baby arrives, and the baby sleeps on the resident's bed while the cousin is in the kitchen. The bed zone has a small still body and an adult-sized resident.

  TrapA baby on the bed raises C1 or C4 confusion about whether the resident is breathing or two people are present.

  RequiredCount by body size and breathing signature. Report "a small person present" with low confidence and do not give any resident vital-sign values to the baby.

• UNK-107Festivals, ceremonies and gatherings

  A mehendi artist and her team of four spend a day in the bedroom decorating the women's hands, and they close the door and use the resident's bed to sit on.

  TrapWomen in the bedroom for hours with the door closed hide the zone from normal rules.

  RequiredLet the owner declare the room an event room for the day. Within it, the unknown rule is relaxed and the resident's bed-side prior is paused with a note in the record.

• UNK-125Tenants, paying guests and property showings

  Police constables visit the flat to verify a new tenant's documents at 10:30, with the resident, the tenant and a broker all present, and ask to see the tenant's room.

  TrapUniformed unknown people entering the flat are indistinguishable from a raid or from impostors in uniform.

  RequiredCount and log by day. Do not classify uniforms. Offer the resident a card with the rule that police verification visits can be confirmed by phoning the local station.

• UNK-143Children, teenagers and growing grandchildren

  A boy of ten rides a tricycle around the hall at 17:00, ringing a bell, and bumps into the resident's walker.

  TrapA moving small object may be counted as a pet or an extra person, and the collision looks like an impact event.

  RequiredUse size and speed to label a person. Treat the collision as an impact candidate that must be followed by posture change on the resident before any alert.

• UNK-161Burglary, forced entry and bogus officials

  The in-home speaker says "Are you okay? Press the button or say help" in a loud voice at 03:00 while an intruder is in the next room and does not know the resident called anyone.

  TrapThe local check alerts the intruder that the household has an alarm and may provoke violence.

  RequiredWhen an unknown person is detected at night, suppress audible prompts by default. Show only a visual cue the resident can see, and notify the first contact silently.

• UNK-179Invited strangers: fraud, trickery and pressure at the door

  A new cook who joined a month ago takes small items on each visit: a gold ring, then some cash. The unknown-person log shows nothing unusual within her window.

  TrapTheft inside an expected-visitor window is invisible, and a system that logs windows cannot see it.

  RequiredBe clear in the home notice that SAHARA does not detect theft by invited people. Do not add worker surveillance; recommend lockable storage and police verification instead.

• UNK-196The resident taken for a stranger

  After the death of his father a man shaves his head and moustache according to custom and returns to the flat, looking quite different to any face matcher.

  TrapA cultural practice changes the face drastically and a family member appears as a stranger.

  RequiredTreat grief practices as an expected cause of failure. Ask for re-enrolment, keep attribution with elimination and priors meanwhile, and avoid any unknown notification when only residents are present.

• UNK-214The resident taken for a stranger

  A resident is carried down the stairs on a chair by two neighbours after a minor injury, face turned sideways and covered by a scarf against the dust.

  TrapA carried person with a covered face is unknown, and the carriers are two further unknown persons.

  RequiredMerge the visit into the open incident if any exists. Otherwise count three persons and hold attribution; the resident's track resumes at the next anchor pass.

• UNK-232A stranger taken for the resident

  A visitor with an ordinary face, never enrolled, scores just above the threshold against the resident's template on a dark evening with low light.

  TrapLow-quality captures produce unexpected matches with strangers.

  RequiredReject captures below a quality threshold instead of matching them. Report "no decision" and continue with elimination and continuity.

• UNK-250Veils, masks, helmets and everyday coverings

  A woman sweeps with the end of her saree wrapped around her mouth and nose for dust and keeps her head down for forty minutes.

  TrapA covered face is unknown, but the labour posture also resembles a collapse on the floor.

  RequiredRely on the learned posture for the zone and hour. Do not infer a fall or collapse from the work posture of a bent unknown person.

• UNK-268Light, lens and image conditions at the anchor point

  When the family turns on the TV or the air conditioner, the infrared remote flashes near the thermal and infrared sensors, and the sensors register short bursts of change.

  TrapRemote flashes create transient events that may be counted as a quick passing person.

  RequiredIgnore single-frame events without a plausible track and use a minimum track duration before counting. Record any frequent flash events in the device health log.

• UNK-285Photographs, screens and other spoofs

  A thief places a small magnet on the door sensor of a balcony door that stays closed while he opens a different window.

  TrapA fake closed state hides the real door status, and an unseen entry follows.

  RequiredCombine door sensing with count changes; an increase in count with no door event is an entry. Treat the magnet pattern as a tamper signature in device health.

• UNK-303Phantom people: occupancy counts that are too high

  A glass-fronted display cabinet holds crystal and photographs, and a radar reflects off the glass and produces a second person standing in front of the cabinet.

  TrapReflection from glass doubles the apparent position of a real person.

  RequiredMark glass surfaces in the room model and use track consistency tests that require independent motion for a second person.

• UNK-321Missed people: occupancy counts that are too low

  A visitor stands behind a tall steel almirah in the bedroom for several minutes, shielded from the node on the opposite wall.

  TrapA body in a blind spot is missed by a single node.

  RequiredCheck blind spots at installation with a standing person. Where unavoidable, add a node or accept an undercount, and report the zone's coverage on the health page.

• UNK-339Pets, birds and other animals

  A monkey enters the second-floor flat through the open balcony door in Mathura, grabs fruit from the table and sits on the sofa, weighing about fifteen kilograms.

  TrapA monkey of child size is counted as an unknown person, and the resident chases it, making a fall risk.

  RequiredLabel small agile non-human tracks as a non-person when features allow. If counted, send a watch message and add a note that the track may be an animal.

• UNK-357When the resident sees a stranger who is not there

  A resident has called about phantom thieves five times, and the family has stopped responding. Tonight two men really enter, and the count rises to three.

  TrapRepeated false reports teach the family to ignore a true alarm.

  RequiredState plainly in the alert that unlike earlier reports, two bodies are now counted and a door event occurred. Make the alert's evidence, not the resident's word, the headline.

• UNK-374When the resident sees a stranger who is not there

  A resident who says "this is not my house" packs a bag at 17:00 and asks a stranger at the gate to take him home.

  TrapA person on the doorstep with a resident leaving combines unknown presence and a leaving event.

  RequiredRecord a door event, a count change and an unknown person at the gate zone as one incident, and notify the first contact before the resident leaves the building.

• UNK-392Family conflict, coercion and abuse

  A domestic worker cries out and falls after being pushed by a family member in the kitchen at 10:00; two people are in the room.

  TrapViolence against a worker is an unknown-person event the family may not wish to be reported.

  RequiredTreat a probable fall by any person as urgent with "a person, not a resident". Never suppress it because the family prefers silence, and keep no per-person record.

• UNK-410Privacy, consent and the law at the door

  An insurer offers a discount to residents who share the number of unknown visits each month as a risk measure.

  TrapA commercial use of unknown-person logs turns safety data into a rating.

  RequiredDo not export the unknown-person log to any third party. A resident may share a summary herself, and the system does not enable bulk sharing.

• UNK-428Settings, windows and household patterns

  A resident's retired husband and wife sleep at different times, he at 20:00 and she at 01:00, so night starts at different times for the two.

  TrapA single night window cannot suit two people in one home.

  RequiredDefine the home's night as the period when all residents are in sleep zones, and the private zone rules per resident. Show both settings on the review page.

• UNK-446What the alert says and who it reaches

  At 21:00 a guest sits in the hall and the in-home speaker, tuned for the resident, announces, "Are you all right? Press the button or say help."

  TrapA prompt written for the resident is heard by a visitor who feels accused.

  RequiredPhrase unknown-person prompts as statements to the resident, played softly near the resident or shown by light, never loudly into a room containing visitors.

• UNK-463What the alert says and who it reaches

  The family WhatsApp group, with a cousin who has often visited the flat, receives a forwarded alert saying "no one is home, a person is in the bedroom".

  TrapForwarding an alert to a group reveals the home's empty hours to many people.

  RequiredPhrase alerts so that they do not state that the home is empty of residents. State only what is needed to act, and warn contacts against forwarding.

• UNK-481Unknown person together with another event

  A guest collapses from heat during a May afternoon visit and sits against the wall breathing slowly, while the resident fans her.

  TrapA visitor's emergency is not a resident's, and the system may ignore it.

  RequiredTreat probable collapse by any person as urgent, in words that say "a person, not a resident", and leave the decision to the contact.

• UNK-499Responders, rescuers and officials

  After an earthquake tremor at 03:00 a dozen neighbours rush into the resident's flat to see if she is safe, filling the hall.

  TrapA night surge of neighbours looks like a break-in and also like a crowd.

  RequiredDetect a building-wide event through multiple homes' motion if available, or through ghost counts on all nodes. Hold the unknown rule briefly and send one message.

• UNK-517Power, network, building and neighbours

  The battery of the balcony door sensor has run flat, and a visitor enters through that door while the sensor sends nothing.

  TrapAn entry with no door event is read as a window entry, a false intrusion.

  RequiredReport the dead sensor as a fault, mark the door evidence as missing, and accept a count rise without a door event as a possible visitor at the lower level.

• ENV-001Indoor heat: thresholds, humidity and the daily cycle

  At 15:00 in May a Nagpur flat's living room reads 34 °C with the fan running. The resident, a 78-year-old woman, is sewing calmly. No heat-wave warning is in force.

  TrapA fixed 32 °C day rule fires every afternoon from April to June, and the family learns to ignore it.

  RequiredDo not alert on the absolute daytime value alone. Require an IMD warning or a change in the resident's own rest-state or activity, and store the reading as context.

• ENV-018Indoor heat: thresholds, humidity and the daily cycle

  At 17:00 the setting sun through a west window falls on the bed. Air reads 31 °C, but the sheet and the resident's skin are far hotter than the air.

  TrapAn air-temperature sensor misses the radiant load of direct sun on the person.

  RequiredRecord this limitation, ask the installer to note direct-sun patterns, and treat a rest-state change that coincides with sun on the bed as a reason to prompt the resident.

• ENV-036Heat in particular dwellings and rooms

  A resident sleeps on the roof of a two-storey house during the dry months, and monsoon nights move him to a stuffy room below where the humidity is 90 %.

  TrapThe seasonal change in sleeping place changes the exposure, but the baseline learned in summer assumes the roof.

  RequiredRe-learn baselines when the sleeping place changes, use C1 and C4 to detect the move, and apply the humid-room checks to the new location.

• ENV-054Heat, power cuts, coolers and air conditioners

  A battery-powered temperature node in a hot loft overheats; its coin cell sags at 55 °C and the node reports 0 °C for six hours before it drops off the network.

  TrapA sensor failing in the heat sends nonsense that looks like a real, extreme cold reading.

  RequiredValidate readings against plausible rates of change and other sensors, quarantine implausible values, and raise a node-fault event with a clear message instead of a hazard.

• ENV-072Heat, the body and medicines

  In the afternoon a resident who is hard of hearing does not hear a prompt that asks "Are you okay?" because the cooler is roaring beside him.

  TrapA local check delivered by voice fails exactly when the room is noisy from the cooling appliance.

  RequiredUse a visual or vibrating second cue, extend the cancel window while the cooler is on, and escalate to the first contact if there is no response.

• ENV-089Cold waves and cold exposure

  The resident's family in Mumbai assumes the Ludhiana flat is warm because the IMD forecast says 12 °C, while the unheated bedroom measures 6 °C at night.

  TrapFamily judgement from a forecast misses the indoor reading, so no one acts.

  RequiredShow the measured indoor temperature next to the outdoor forecast in family summaries, and send a watch alert when the indoor value is near the lower limit for the home.

• ENV-107Coal braziers, charcoal and room heaters

  A resident in a village keeps an open chulha burning wood in the room where he sleeps in winter, with smoke leaving through the roof tiles.

  TrapCombustion is part of his daily routine and the usual alerts feel like criticism of his way of life.

  RequiredRaise the alert on actual CO or smoke alarms only, give clear and respectful advice, and record in the care summary that traditional cooking and heating continue.

• ENV-125Gas geysers and bathroom carbon monoxide

  A resident enters the bathroom at 06:30 with the geyser already burning, stays for 35 minutes and does not come out. The CO alarm is present but its battery is flat.

  TrapA flat alarm gives no signal, and a long stay is judged by the bathroom rule only after a longer personal limit.

  RequiredCombine the bathroom overstay rule with the known gas appliance state and the alarm's missing heartbeat, and escalate earlier when a gas appliance is on.

• ENV-143Other carbon monoxide sources and what an alarm does and does not tell us

  A CO alarm shows a reading of 35 ppm at 14:00 in an empty home, and the resident returns at 15:00 from the temple. The reading is falling.

  TrapA high but falling value in an empty home is either ignored or prompts a rush into the house.

  RequiredReport the reading, the trend and occupancy, tell the resident not to enter until the level is below the guideline, and keep the event open until cleared.

• ENV-160LPG leaks and cylinders

  A resident lights a match to see whether the gas smell is still there, a habit of his village. The detector alarm is already sounding.

  TrapA folk practice makes a leak explosive, and no system action is quick enough to stop it.

  RequiredTeach residents at setup never to light anything on a gas smell, and make the local alarm voice say "do not light anything" in the resident's language.

• ENV-178Stove, pressure cooker, pan and kettle left on

  A resident with Parkinson's disease spills hot oil on herself and the hob during frying. The tremor makes her drop the pan, and she sits on the floor.

  TrapA burn and a fall in one scene look like a fall alone, and the burn is not known.

  RequiredEscalate an urgent possible fall in the kitchen with a note that the stove state is on, and ask the first contact to tell responders about hot oil.

• ENV-196Electrical faults, overheating appliances and fire

  A ceiling fan in an old house hums, slows and smells hot after a voltage drop. The family keeps it running because it is the only cooling.

  TrapA failing capacitor is both a cooling failure and a fire risk, and the family weighs one against the other.

  RequiredAlert on any smoke alarm at once, record the fan's slowing as a maintenance note, and recommend replacement before the next heat wave.

• ENV-214Flames and smoke from worship, festivals and mosquito coils

  A long row of diyas burns along the window sills for Deepavali. The wind lifts the curtain and a flame touches it while the family is on the terrace.

  TrapEveryone is absent from the room on purpose, and the usual presence-based rules do not apply.

  RequiredApply fire alarms regardless of occupancy, and ask the family to leave a person in the room when many lamps are lit.

• ENV-231Escaping fire: alarms, locked grilles and slow bodies

  A flat's balcony is closed all round with an iron grille for security, with no hinged panel. A fire in the living room cuts the only door.

  TrapA sealed balcony removes the second exit that fire-safety plans assume.

  RequiredRecord sealed balconies and exits in the survey, warn the family about the missing second exit, and give the emergency service the location of the resident in the alert.

• ENV-249Outdoor air pollution entering the home

  Garbage is burnt in the lane outside the ground-floor window each evening. The smoke is thick for an hour and the resident, who sleeps near the window, wakes coughing.

  TrapA repeated, local source gives the family no clear action, and the daily alert is ignored.

  RequiredReport a recurring evening pattern once, advise sleeping away from the window, and send a watch message to the family only if the resident's breathing change persists.

• ENV-267Indoor air: cooking smoke, sprays, paints and fumigation

  A dry floor drain in a bathroom unused for weeks lets sewer gas rise. The resident cannot smell it and washes her face there each morning.

  TrapHydrogen sulphide at low levels causes headache and nausea, and the resident's loss of smell hides it.

  RequiredRecord the unused bathroom and drain state at maintenance, and advise the family to pour water in unused traps, since the system cannot sense the gas.

• ENV-285Humidity, mould and the monsoon

  A clothes-drying rack set up in the bedroom for the monsoon raises humidity by 15 percentage points overnight and blocks the node's field of view.

  TrapA family routine produces both an air hazard and a sensing problem.

  RequiredLink the humidity rise to the rack through a cover or health check, tell the family about both effects, and mark the node's data as degraded.

• ENV-303Flooding, water ingress and electrical danger

  A window sill leaks in a storm and rain runs onto a wall socket behind the television, while the resident watches the news.

  TrapWater near a live socket has no signature until it trips something.

  RequiredRecord water-ingress points in survey, rely on a water sensor if fitted, and advise the family about the socket.

• ENV-320Storms, earthquakes and failing buildings

  Tremors in a high-rise building cause the lift to stop between floors. A resident returning from a walk is trapped for forty minutes.

  TrapA person stuck in a lift is outside the home, and the system sees only an overdue return.

  RequiredRecognise an overdue return from a known outing, notify the first contact after the usual margin, and mention any known building event.

• ENV-338Things that trigger or blind hazard sensors

  A resident sprays a mosquito killer in a closed bedroom for two minutes before bed. The smoke alarm responds to the aerosol cloud, and the resident gets out of bed.

  TrapA short aerosol cloud at the alarm is read as fire, and a night wake-up creates a fall risk.

  RequiredTreat as urgent but start with a local check that asks if she sprayed, and cancel on her reply with the room's smell and heat quiet.

• ENV-356Sensor ageing, drift and cross-sensitivity

  A temperature node freezes on its last value because its bus hangs. The room reads exactly 29.1 °C for fourteen hours.

  TrapA flat line looks like a stable, comfortable room.

  RequiredDetect near-zero variance over hours, mark the stream as stale, and report the node as degraded instead of treating its value as current.

• ENV-374Placement, installation and housekeeping errors

  A helper covers the smoke alarm with a plastic bag while cleaning and forgets to remove it. It stays covered for five months.

  TrapA covered detector gives no cover and no signal.

  RequiredSupervise detectors with functional checks that reveal a cover, report an unresponsive detector, and ask the family to check the alarm.

• ENV-391Integrating certified alarms

  A resident's smoke alarm belongs to a vendor whose app has no local output. SAHARA cannot read it directly.

  TrapA device that works only through another cloud cannot be part of the home's local alarm path.

  RequiredFall back to a sound-derived detector label with a lower confidence cap, or recommend a detector with a local output, and state the limit to the family.

• ENV-409Telling the resident and the family in time

  On Diwali night the mobile network is congested. The SMS about a gas alarm reaches the daughter twenty minutes late.

  TrapA single channel on the busiest night delays the alert.

  RequiredSend urgent alerts by more than one channel at once, include a voice call, and record delivery times for each channel.

• ENV-427Telling the resident and the family in time

  A heat watch message says "Give her a cold shower". The daughter does so to a drowsy mother who then faints.

  TrapAn alert that gives medical advice can cause harm.

  RequiredLimit action text to safe, general steps such as moving to a cooler room, giving water if awake, and calling a doctor or 112, and have the wording reviewed by a clinician.

• ENV-445Power and network loss during a hazard

  A neighbour changes the Wi-Fi password to the shared connection the resident used. The central node loses its link and the family sees no data.

  TrapA change outside the household cuts the connection, and the family assumes quiet.

  RequiredDetect loss of link within minutes, notify the owner by the cellular path, and keep local alarms active.

• ENV-462Hazards confused with other events, and combinations

  Heat in a room shuts the central node's backup battery charging, and the node reports a fault while a heat watch is active.

  TrapA system fault and a hazard from the same cause lead to two partial messages.

  RequiredGroup a fault and a hazard with a shared cause in one message, and give the hazard priority.

• ENV-480Consent, privacy and dignity in environmental sensing

  A researcher asks for a year of indoor temperature data from homes with older residents for a heat-health study.

  TrapSmall numbers may re-identify a household, and the data has not been consented for research.

  RequiredProvide data only under separate opt-in research consent with ethics review, aggregate over many homes, and keep identifiers out of the dataset.

• ENV-498After the alarm: recovery, repeat alarms and learning

  Firefighters ask for the event timeline on arrival. The family has no access because the app has logged them out.

  TrapResponders lose minutes for lack of the last location and hazard.

  RequiredProvide a one-page responder summary on the central node's local interface, with last room, occupancy count and hazard type, for the resident or first contact to show.

• ENV-516Household, culture and animals

  A visiting relative fills the home with insect repellent smoke from a coil in each room before leaving for a day, with the elder asleep.

  TrapA well-meant act by a visitor creates fire and particulate hazards that the resident did not choose.

  RequiredAlarm on smoke, report high particulate in the resident's room, and tell the visitor through the first contact to ventilate and remove the coils.

• SYS-001Mains power cuts and restoration

  At 3 a.m. a power cut in a top-floor flat stops the bedroom node, plugged into a socket the inverter does not back, while an 82-year-old resident walks to the toilet.

  TrapHer last frame shows walking, then nothing; the missing trip to the toilet reads as an unusually quiet night.

  RequiredThe node sends a last-gasp power-lost message on stored charge; the central node marks bedroom coverage lost from that second, widens night rules and logs a maintenance fault, not silence.

• SYS-018Mains power cuts and restoration

  An electrician isolates the bedroom circuit for three days to repair old wiring. The bedroom node is unplugged and moved, but the plan, envelope version and health record still list the old position.

  TrapThe node sees the room from a new pose while gating against the old envelope, or sits unplugged unnoticed.

  RequiredA pose change stops sensing until re-verified; the owner is told the bedroom is uncovered, and the installer must re-sign the placement before the node is accepted again.

• SYS-036Inverter and UPS switchover gaps

  When mains returns the inverter switches back, causing a second short gap. Each cut therefore resets the nodes twice in two minutes.

  TrapTwo resets are counted as two independent faults, doubling the health penalty.

  RequiredResets within one power episode are counted once for fault scoring while the data gap is recorded for both.

• SYS-053Voltage dips, surges, lightning and earthing

  Surge protection on the node's extension board has been absorbing surges for years. Its protective element has worn out, though the power light stays on.

  TrapThe board shows no sign that protection is gone, until a surge destroys the node.

  RequiredThe installer visit schedule includes replacing surge protection before each monsoon; nodes count the surges seen and report when a threshold is reached.

• SYS-071Sockets, extension boards and unprotected circuits

  The wall USB charger feeding a node cuts power when it sees low current, to save energy. The node's sleep draw is below its threshold and the node drops out at random.

  TrapA smart charger turns the supply off on its own and the node resets.

  RequiredOnly supplies approved for continuous low load are used; unexplained resets with a clean voltage log prompt the installer to check the charger type.

• SYS-089Home network faults

  A mesh extender in the corridor is plugged into the socket a helper uses for her phone charger. When she unplugs it, the three nodes behind it lose their link.

  TrapA dependency hidden from the family silences several nodes at once.

  RequiredThe central node maps which nodes depend on which relay and names the extender in the message when several nodes drop together.

• SYS-106Internet provider outages, shutdowns and mobile congestion

  A state orders a total shutdown during a recruitment examination, covering mobile and broadband for five hours. The central node cannot reach the relay at all.

  TrapThe relay sees the home go silent and treats it as a fault, though the whole town is shut.

  RequiredThe relay compares silence with other homes in the same area and any public order; the family message says a regional shutdown is likely, not a device fault.

• SYS-124The cellular fallback path

  The SIM balance reaches zero. Calls can still be received, but outgoing SMS and calls are barred.

  TrapThe modem reports a healthy network while it cannot send an urgent alert.

  RequiredThe node reads the balance or plan state through the operator and raises a maintenance fault at a threshold; the family is told to recharge.

• SYS-141The cellular fallback path

  The installer tests the fallback with an SMS only. The SIM is a data-only IoT plan with no voice, so the automated call fails at the first real alert.

  TrapHalf the fallback path was never tested.

  RequiredThe test covers SMS, voice call and acknowledgement from each recipient; a SIM that cannot place voice calls is rejected.

• SYS-159Cloud, application and account failures

  The first contact replies to the alert on a family WhatsApp group instead of the application, saying he is going, and the system does not see it.

  TrapThe ladder keeps escalating to the second contact and the service although a person has taken it.

  RequiredThe alert message carries an acknowledgement link or key press that is easy to use; unacknowledged alerts continue, with an explicit option for a second contact to stand down.

• SYS-177Fault messages that nobody reads

  Fault notices are posted to the family WhatsApp group, which has two hundred greeting messages a day. The notice is buried within minutes.

  TrapA channel full of noise swallows an actionable message.

  RequiredFaults go to a dedicated channel with named owners; the system does not post into general family groups.

• SYS-194Failed, partial and badly timed updates

  A rollback restores the previous model, but the household's per-home baselines were adapted during the new model's brief use and no longer fit the old one.

  TrapA rollback produces a mismatched pair and degraded results.

  RequiredAdaptations are versioned with the model that produced them, and rollback restores both together.

• SYS-212Storage, memory and database faults

  The feature ring buffer lives in memory. While the processor is busy with a software task, the buffer overflows and drops the oldest frames, including those just before a possible fall.

  TrapEvidence from the seconds before an event is lost.

  RequiredEvent-linked excerpts are saved first, buffers apply back-pressure to non-urgent work, and an overflow is flagged and counted in the health record.

• SYS-229Clocks, time sources and synchronisation

  The mobile network sends a wrong time that is four minutes out, and the central node adopts it.

  TrapA single bad reference spoils all the timestamps.

  RequiredTime from any one source is accepted only if it agrees with the others or with the oscillator's allowed drift; a large disagreement is reported, not applied.

• SYS-247Dust, grease, steam, insects and other slow degradation of sensing

  Ants nest inside the warm housing of a door contact and a node. Their movement gives false activity, and eggs block a vent.

  TrapInsect activity produces both noise and a thermal fault.

  RequiredUnexplained high-frequency activity at very short range is flagged at P2; repeated cases lead to a maintenance request for cleaning and sealing the node.

• SYS-265Obstruction, rearrangement and moved nodes

  Every monsoon a family sets up a drying rack in front of the bedroom node. Wet clothes absorb and scatter the signal and sway in the fan.

  TrapA seasonal obstacle produces both a blind area and false motion.

  RequiredThe change is learned as seasonal clutter after the first occurrence, flagged each time it appears, and the installer suggests a different position for drying.

• SYS-282Obstruction, rearrangement and moved nodes

  A door left open at ninety degrees hides part of the corridor from a wall node and swings in the fan draft.

  TrapAn ordinary door position creates an intermittent blind area and moving clutter.

  RequiredDoor state from the contact is combined with coverage, so that an open door is known to affect the view and does not look like a fault.

• SYS-300Summer heat, winter cold, damp and the monsoon

  A node mounted close to the stove is heated by the cooking plume twice a day and ages faster than the others.

  TrapLocal heat shortens the life of one node in a way the average conditions do not predict.

  RequiredComponent age and temperature history are recorded per node; the maintenance plan brings forward replacement of nodes with a high thermal load.

• SYS-317Tampering and deliberate disabling

  A relative who mistreats an elderly woman unplugs the bedroom node before visits. The owner who gets the alerts is that relative.

  TrapThe person causing harm controls the tamper alert.

  RequiredA tamper alert also goes to a contact chosen by the resident, not the owner alone, and the fallback path sends it even when the owner has paused notifications.

• SYS-335Tampering and deliberate disabling

  A family member moves the central node behind the television to hide the wires. The signal weakens and the vents are blocked.

  TrapNeat placement hides the device and degrades its cooling and radio.

  RequiredThe central node reports weak signal and a rise in temperature; the instructions state the placement rules, and the installer revisits the location.

• SYS-353Installation and configuration errors

  Two flats in one building use the same default setup network name. A new node joins the neighbour's central node by mistake.

  TrapA node reports to the wrong household.

  RequiredPairing needs a physical button on the central node and confirmation by the owner; keys are unique per household, and a node that cannot authenticate is refused.

• SYS-370Rats, monkeys, birds, pets and other animals

  A rat gnaws the external cellular antenna cable. The modem still registers but signal strength falls by twenty decibels.

  TrapThe modem looks healthy though it can barely send.

  RequiredThe fallback test measures real delivery and signal strength; a drop against the commissioning value is reported as an antenna or cable fault.

• SYS-388Cyber faults, default credentials and rogue devices

  A visiting repairman plugs a USB stick into the central node's port to charge his phone, and the stick contains malicious code.

  TrapA physical port is an easy way in.

  RequiredUnused ports are electrically disabled or locked, and the central node never auto-runs anything from a port; a device plugged into it is logged.

• SYS-405Silent failures and how they are detected

  The separate alert module has a flat battery that nobody noticed. It would have been the only route out in a long outage.

  TrapA backup that is never tested is not a backup.

  RequiredThe alert module runs a monthly self-test with a real message, reports its battery state and is supervised by the central node.

• SYS-423Silent failures and how they are detected

  To save battery during a long cut a node enters a low power mode and says nothing.

  TrapAn unreported change of state turns coverage off silently.

  RequiredEvery state, sensing, reduced and off, is explicit and reported; entering reduced mode generates a message with what stops working.

• SYS-441Technicians, spares, warranty and the realities of maintenance in India

  A node fails in a small town 120 kilometres from the nearest technician, who visits weekly. The bedroom is uncovered for eight days.

  TrapA long wait for service leaves a coverage gap that nobody manages.

  RequiredThe system gives remote triage within a day, tells the family which night rules are reduced, and arranges a pre-configured replacement that a local electrician can fit with voice guidance.

• SYS-458Technicians, spares, warranty and the realities of maintenance in India

  The nearest distributor has no spare for the entrance anchor node, but has an ambient node. The technician swaps it in to restore service.

  TrapUsing the wrong role of node breaks the privacy design.

  RequiredNodes are provisioned by role in hardware and software; the central node refuses to enrol a node of the wrong role at that location.

• SYS-476Faults that occur during an urgent event

  A heat wave raises the bedroom to 38 °C while the room's temperature sensor is stuck at 25 °C.

  TrapThe heat rule never fires because it trusts a frozen reading.

  RequiredA stuck sensor is flagged and the system uses other nodes' temperatures and the outdoor warning; the heat rule is applied from those and the fault is reported.

• SYS-493Faults that look like the other events, and events that look like faults

  Dust on an entrance sensor makes it reject the resident's face each morning.

  TrapA fouled sensor reads the resident as an unknown person.

  RequiredRepeated rejection of an enrolled resident at the same hour raises a sensor health check before any unknown person alert, and the alert states reduced identification quality.

• SYS-511Faults that look like the other events, and events that look like faults

  A resident turns off the power at the main board for safety in a storm, and lights, fans and nodes all stop.

  TrapA deliberate action looks like a fault, a cut, or an environmental event.

  RequiredThe system reports mains loss and the last known state, and the family message says that the cause may be the household's own switch.

Nothing in this sample matches. The full atlas has 4,307 entries; try a broader word.