Settings → Sentinel
Sentinel listens to the room while you are away. A noise loud enough and long enough becomes an incident. An incident keeps a short audio clip, and a photo or a video when the camera is allowed. Armed for real, Sentinel sends each incident to your Telegram. The rail entry is Sentinel. The page title is Sentinel and its subtitle reads Sentinel listens to the room when nobody is there. A loud enough, long enough noise becomes an incident.
The page has four tabs: Watch, Avatar, Settings and Incidents. The app remembers the last tab you opened.
While the settings load, the page shows a loader. When they cannot be read,
it shows Settings unreadable: {error} and a Retry button. The error
NO_BRIDGE means the app needs a restart.
Watch
How it works
This card explains the cycle in five lines:
- Calibrate the room: Sentinel listens for 60 seconds and measures the background noise.
- Arm Sentinel and leave: it arms itself at the end of the exit delay.
- A noise above the threshold for long enough becomes an incident. Sentinel keeps the 10 seconds before and the 15 seconds after.
- In rehearsal, the incident stays on this computer, to listen to in the Incidents tab.
- Armed for real, the incident goes to Telegram, with a photo if the camera is allowed.
Below, three sentences:
- Tell anyone who may come in while Sentinel is armed.
- Sentinel listens while the app is open and the computer stays on, lid open.
- When leaving, lock Windows (Win+L): Sentinel keeps listening.
Calibration
60 seconds of listening in night conditions (fans, heating, street), without talking. The threshold is set from this background noise.
Click Calibrate ({s} s). The button shows 60 s. The microphone opens and the card counts down with Listening… {s} s and the live level {db} dBFS. Cancel stops it and closes the microphone. Leaving the page also closes it.
At the end, the card shows the result: Background {floor} dBFS, peak {peak} dBFS, threshold {threshold} dBFS, then measured on {date}. The background is the level the room stays under 95% of the time. The threshold is the background plus the margin set on the Settings tab.
Before the first calibration, the card says Room not calibrated yet. A calibration can fail:
- Listening too short, to be redone.
- The microphone returned silence: see the microphone chosen in Settings › Voice. See Settings → Voice.
- Microphone unavailable ({error}). The error is one of the microphone errors listed under Arming errors.
A failed calibration saves nothing. While Sentinel is armed, the card says Disarm Sentinel to calibrate again.
Status
The first line says where Sentinel is:
- Sentinel disarmed
- Leaving: Sentinel arms when the delay ends.
- Sentinel armed since {time}, followed by rehearsal when armed in rehearsal.
While Sentinel is disarmed and the room is calibrated, the card offers two buttons:
- Arm arms for real. Each incident goes to Telegram.
- Arm in rehearsal arms without sending. Each incident stays on this computer.
The card repeats the difference: “Arm” sends each incident to Telegram. “Arm in rehearsal” keeps it on this computer. Without a calibration, the buttons are hidden and the card says Calibrate the room first, in the Calibration card. The arming buttons then show up here.
From the start of the exit delay, the card shows Disarm instead. Only the main board window can disarm from here. In another window the button is greyed.
From the start of the exit delay, a live meter reads Level {db} dBFS · loudest since arming: {max} dBFS, {ms} ms above the threshold · threshold {threshold} dBFS. Under it: Make a noise. If “loudest” stays under the threshold: lower the margin. If “ms above the threshold” stays under the minimum duration: lower the duration.
Two lines report what Sentinel can use.
| Telegram line | Meaning |
|---|---|
| Telegram: ready, to the home chat. | Incidents can leave. |
| Telegram: install the assistant, then link the bot in its Channels tab. | The assistant is missing. See MnemoHermes. |
| Telegram: link the bot in the assistant's Channels tab. | No bot is linked. |
| Telegram: the bot is linked but has no home chat. Send it /sethome in Telegram. | The bot has no chat to write to. |
| Camera line | Meaning |
|---|---|
| Camera: allowed in Settings › Gestures. | Incidents carry a photo. |
| Camera: not allowed in Settings › Gestures. Incidents go without a photo. | Sentinel works on sound alone. |
Sentinel never asks for the camera itself. You allow it once, in Settings › Gestures.
Arming errors
When arming fails, the card says Arming refused: {error}. When the engine stops by itself, it says Sentinel disarmed itself: {error}. The error is one of these:
| Error text | Code |
|---|---|
| the room is not calibrated | NOT_CALIBRATED |
| Sentinel is already armed | ALREADY_ARMED |
| the app needs a restart | NO_BRIDGE |
| Windows refuses the microphone to the app | MIC_REFUSED |
| no microphone found (see Settings › Voice) | NO_MIC |
| another app holds the microphone | MIC_BUSY |
| the microphone could not open | MIC_FAILED |
| the microphone was cut | MIC_ENDED |
| this version of the app cannot read the microphone in the background | NO_TRACK_PROCESSOR |
Avatar
This tab sets what Sentinel shows and how it reacts. It holds three cards.
The watching avatar
Who watches the room while Sentinel is armed, and how it reacts.
| Control | Choices | Default |
|---|---|---|
| Avatar | The active desktop's avatar, or one of your avatars. An avatar without a name shows Unnamed avatar. | The active desktop's avatar |
| Show the Sentinel screen while armed | on or off. The avatar covers the board, large, and watches. The badge stays. | on |
| Every screen | on or off. The Sentinel screen on every display: a light window opens where the board has none. The reaction crosses the screens in a wave. | on |
| Effect on a trigger | None, Pulse, Alarm, Scan | Pulse |
| The avatar's reaction | None, Stern, Surprised, Frightened, Amused | Stern |
| Siren on a real trigger (8 s) | on or off. Two tones made by the app. Never in a rehearsal, never in the test. | off |
Test the reaction shows the Sentinel screen in this window and plays the effect and the reaction. Shows the screen for 6 s and plays the reaction. Nothing is armed, recorded or sent. The button is greyed while Sentinel is armed.
The camera
With the camera, a movement triggers like a noise, the avatar looks where it moves, and an incident carries a short video.
- Watch with the camera, off by default. The camera stays on while Sentinel is armed. Only an incident writes a clip; nothing else is recorded. When the camera is not allowed, the card says The camera is not allowed in Settings › Gestures. Without it, Sentinel arms on sound alone.
- Movement sensitivity: Low, Medium (default), High.
- Video clip length: 10 s (default), 20 s or 30 s.
The two last controls appear only when Watch with the camera is on. None of the three can change while Sentinel is armed.
The lock
While Sentinel is armed, only the code or the fingerprint opens the screen. A click, the voice and the badge no longer disarm.
The card warns about the limits in its second line: It covers Mnemosyne's windows, not the system: Ctrl+Alt+Del, killing the app or cutting the power still get through. Every attempt to get around it (touching, leaving the window, a wrong code) becomes an incident with a photo.
- Set a code
Under Lock code, the hint reads 4 to 32 characters. Only its hash is kept on this computer; it is never sent. Type the code in New code and again in Confirm the code. Click Save the code. The card says Code saved. and then A code is set. A short code says The code needs 4 to 32 characters. Two different entries say The two codes differ.
- Turn the lock on
Switch on Lock the screen while armed. Every board window goes full screen above the others until a verified unlock. Without a code, the switch is greyed and the card says No code set: the lock cannot be turned on.
- Choose the entry delay
Entry delay: 0 s, 15 s, 30 s (default) or 60 s. With the lock, an incident waits this long before leaving for Telegram. A verified unlock in that time cancels it.
Remove the code deletes the code and turns the lock off. The card says Code removed. The lock is off. The code, the switch and the delay change only while Sentinel is disarmed. While armed, the card says The code changes only while Sentinel is disarmed.
The last line says what this computer offers besides the code:
- Windows Hello is available on this computer: fingerprint, face or PIN.
- Touch ID is available on this Mac.
- No fingerprint reader on this computer: the code alone unlocks.
Settings
Thresholds and delays
The card Settings holds four controls. The first three are locked while Sentinel is armed.
| Control | Range | Default | Hint |
|---|---|---|---|
| Margin above the background noise: {db} dB | 6 to 30 dB | 15 dB | The threshold is the background noise plus this margin. The higher the margin, the less often Sentinel triggers. |
| Minimum noise duration: {ms} ms | 100 to 2000 ms, by 50 | 200 ms | The noise must stay above the threshold for this long, within one second. A slammed door lasts 50 to 150 ms. |
| Exit delay | 30 s, 60 s, 120 s | 60 s | The time to leave the room. During this delay, Sentinel listens without triggering. |
| Keep the clips | 1 d, 7 d, 30 d | 7 d | Sentinel deletes incidents after this delay. The ones marked "Keep" stay. |
Messages
The voice and the alert window work when Sentinel is armed for real. "Test" shows the result right away.
Spoken warning, on by default. Sentinel says this sentence when it triggers, with the voice chosen in Settings › Voice. Pick a preset:
| Preset | Sentence |
|---|---|
| Serious (default) | This room is under surveillance. You are being recorded. |
| Firm | Warning. Your presence has been detected and recorded. |
| Fun | Hello there! I heard you. Smile, you are being recorded. |
| My own text | Your sentence, in the field The phrase, up to 200 characters. |
The chosen sentence shows in italics. Test speaks it now.
Alert window, on by default. Shows full screen when it triggers. Closing it leaves Sentinel armed. The same four presets apply:
| Preset | Title | Message |
|---|---|---|
| Serious (default) | Room under surveillance | Your presence has been detected. Sound in this room is being recorded. |
| Firm | Unauthorized access | This computer is protected by Sentinel. Your presence is being recorded. |
| Fun | Caught red-handed! | Sentinel heard you. Put down what you were holding and smile. |
| My own text | Title, up to 80 characters | Message, up to 300 characters |
Test opens the alert window now. Its button reads Close.
The preset texts follow the app's language. Your own text is saved when the field loses focus, or on Enter in a one-line field.
When a setting cannot be saved, the page says Setting not saved: {error}.
Incidents
The copy sent to Telegram is off this computer: delete it in Telegram too.
Each incident shows its time, peak {db} dBFS, rehearsal when it was one, and its source when it was not a sound: Movement detected or Someone touched the computer. Then a status:
| Status | Meaning |
|---|---|
| sent | The incident reached Telegram. |
| send failed ({error}) | The send failed. The incident stays here. |
| sending | The send is under way, or waits for the entry delay. |
| kept here (rehearsal) | Sentinel was armed in rehearsal. |
| kept here (Telegram to link) | Telegram was not ready. |
| kept here (limit of 6 sends per hour) | The hour's limit was reached. |
| kept here (unlocked within the entry delay) | You unlocked in time. |
| kept here (the app quit before the entry delay ended) | The app closed during the delay. |
When a video could not be kept, the row says video dropped ({why}).
An incident holds up to two photos. A photo that cannot be read shows unreadable photo. Each row has these buttons:
- Listen plays the clip. An incident without sound shows empty clip.
- Watch the video plays the video clip, when there is one.
- Keep protects the incident from the retention delay. It then reads Kept. Click again to release it.
- Delete removes the incident.
Delete all asks a second time: the button turns into Confirm: delete the {n} incidents for 10 seconds. A second click deletes them.
The list shows No incident kept. when it is empty, and List unreadable: {error} when it cannot be read. While it loads it shows "…", a character drawn by the code.
Sentinel sends at most 6 incidents per hour. When it reaches the limit, it sends one message to Telegram: Sentinel: limit of 6 sends per hour reached. The next incidents of this hour stay on the computer.
What you see while Sentinel is armed
The title-bar badge
While Sentinel is armed, a badge sits in the title bar. It reads Sentinel: leaving in {s} s during the exit delay, then Sentinel armed since {time}, with rehearsal when it applies. It shows photo for a moment after a photo was taken. Its tooltip reads Disarm Sentinel, or Last send failed ({error}). Click to disarm. after a failed send. One click disarms, from the main board window only.
When the title bar is in icons mode, the badge shrinks to a shield. During the exit delay it shows the seconds left, and a camera icon after a photo. The full sentence, rehearsal and the disarm hint move to the tooltip.
The Sentinel screen
With Show the Sentinel screen while armed on, the chosen avatar covers the board, large, and looks around every few seconds. The screen shows:
- At the top, SENTINEL and the state. The state reads Arming in {s} s, then Armed since {time}. In rehearsal, the tag Rehearsal: nothing is sent is added.
- On the left, Watching the room, a level meter, and the line Level {db} dB · threshold {th} dB.
- On the right, the clock, the camera state and Incidents since arming: {n}. The camera state is Camera on followed by Movement {pct} %, or Video off: camera not allowed, or Video off: the camera did not open.
When something triggers, the effect and the reaction play. A banner shows the source (Noise detected, Movement detected, Someone touched the computer or Test), the time, and the alert text. Close the message hides the banner.
Without the lock, the bottom of the screen offers Disarm and Back to the board. Sentinel stays armed. Its badge stays in the title bar. The light windows on the other displays only offer Disarm.
During Test the reaction, the screen reads Test of the reaction: nothing is armed, nothing is sent. and offers Close the test.
The lock screen
With the lock on, every board window stays full screen above the others. The screen shows Locked and a button Unlock.
- Any key, click or pointer movement opens the pad. While armed, the first touch is an incident at once, with the source Someone touched the computer. The pad then counts the entry delay: Every touch is watched: unlock within {s} s. A verified unlock in that time cancels the send. Further touches during the delay, or during 15 seconds if the delay is shorter, do not open a new incident. During the exit delay, a touch only opens the pad.
- Type the code in the field Code and press Unlock. A wrong code says Wrong code.
- The third wrong code in a row is an intrusion: it becomes an incident, and the pad waits 30 seconds. Each further wrong code doubles the wait, up to 10 minutes. The pad says Too many tries. Next try in {s} s.
- When the computer has Windows Hello or Touch ID, the pad offers Windows Hello or Touch ID. The system box asks you to Unlock Sentinel. A refusal says Not recognised ({error}).
- Switching away from the app or closing a locked window counts as an attempt to get around the lock.
- If the microphone is lost, Sentinel stays armed and the pad says Microphone lost: Sentinel watches without sound, with the camera. Unlock to take back the computer. Telegram receives Sentinel: microphone lost at {time}. The watch goes on without sound, with the camera and the lock.
Disarming
Without the lock, you can disarm with the badge, the Disarm button of the screen or of the Status card, or by voice. With the lock, only the code or the fingerprint disarms. When Sentinel was armed for real and past its exit delay, it tells Telegram Sentinel disarmed at {time} ({cause}). The cause reads click, voice, microphone cut, code or fingerprint.