BYD Extend

Experimental open-source companion app for selected Chinese BYD vehicles running DiLink.

This project is not affiliated with or endorsed by BYD. Configure and test all driving-related features while the vehicle is parked.

Project status

Current source target: 1.3.2 (version code 106), with Ukrainian, English and Simplified Chinese interfaces, dark and light themes, and a Compose UI. Published builds are listed in the GitHub Releases.

The source target and published release are separate states; a local test APK is not a publication.

Features

• Turn-signal guard with configurable steering, delay, speed, telemetry, and cancellation safety checks.
• Turn-triggered side-camera overlays on the tablet or instrument cluster.
• Independent parking-camera views driven by compatible proximity and speed telemetry.
• Reverse composition, direct camera preview, calibration, fisheye correction, mirroring, crop, rotation, placement, scale, transparency, corner rounding, and image-quality controls.
• User-selectable Reverse panes with optional integrated front side and central camera profiles.
• Optional gear-driven front/rear selection while Reverse gear or the stock camera UI is active.
• An independent rearview-mirror widget on the tablet or a supported instrument cluster, with optional front-camera integration and separate source/visibility button gestures.
• A learned steering-wheel button for switching the active Reverse widget and integrated cameras between front and rear views.
• Optional music metadata and local weather for the stock BYD weather UI.
• Four independent AVAS exterior-audio profiles for locking, unlocking, powering off and on.
• Diagnostics and explicit log sharing.

Camera presets and settings migration

Налаштування provides three file/settings actions:

• Вивантажити пресети камер shares a versioned JSON camera preset through Android.
• Завантажити пресети камер loads a selected JSON preset through the native document picker.
• Імпортувати всі налаштування imports all user settings from the installed legacy com.byd.turnsignalguard.capture 0.52.1 / code 96 app through authorized local ADB.

Camera presets include the active Blind Zone, Parking, Reverse and Rearview Mirror visual configuration, including integrated Reverse Front profiles, display targets, placement, scale, aspect, crop, correction, rotation, mirror, fill mode, camera switches, Reverse background, widget/stacking, and global buffer quality, transparency, and corner radius. They deliberately exclude numeric speed, steering-angle, and distance triggers, non-camera settings, and saved local calibration slots. The learned steering-button bindings are also excluded and preserved when loading camera presets or importing legacy settings.

Preset format v3 stores both tablet and instrument-cluster rectangles for Mirror and all four Blind profiles. Existing v1/v2 files remain supported: their placement is applied only to the declared display (the current display when omitted), preserving the other display. Importing a file without Mirror leaves its settings unchanged. Optional Mirror front integration, selected source and front calibration fields are included without changing the v2/v3 format versions. Older files without these fields preserve the destination values. Panorama-suppression preferences are included when present; older presets without these fields preserve the current values, with suppression enabled by default on fresh settings. Local saved calibration slots and temporary Mirror hiding are not part of a camera preset. Built-in camera geometry and calibration use the approved reference baseline only for absent values and explicit section resets; updating the application preserves existing effective settings, including never-edited values. New cluster placements and placement resets are centered using the corresponding factory tablet width/height. Editing or resetting one display does not change the other.

Reverse output rotation, display mode and mirroring are saved for the selected camera only. Moving, resizing or reordering composition elements does not change RAW or corrected calibration areas. Existing presets remain available; an update does not automatically restore earlier values.

Full migration includes those numeric rules, guard, music, weather, auto-start, and saved calibration slots. It does not copy transient runtime data, logs, ADB credentials, or Android-granted permissions. When imported weather is enabled, BYD Extend requests its own location permission without requiring the weather switch to be toggled again. Denying the request leaves weather off. Existing local ADB authorization is retained when updating BYD Extend.

Validation, read, or cancellation failure leaves the destination unchanged. If the settings have already been saved but shutting down the old app or stopping its helpers fails, the imported settings remain and BYD Extend keeps its runtime blocked until the handover is retried. The legacy source data is never deleted.

After a validated migration, the old application is shut down before BYD Extend starts. Its APK, data, and launcher icon remain available, so it can still be opened or uninstalled normally. For an earlier migration that disabled the old application, Settings offers a confirmed action to restore its launcher access while keeping its runtime stopped; current BYD Extend settings are not imported again or overwritten. Shut down BYD Extend before deliberately reopening the old application. A first legacy-to-Extend installation is a manual APK install because the package identity changes.

Turn-signal telemetry recovery

Turn-signal protection rejects invalid stalk/blink samples without treating them as a neutral position. A transient sample gap can recover after valid listener evidence and fresh telemetry; the interrupted action is discarded and a new stalk cycle is required after returning to neutral. A broken telemetry subscription remains unavailable until it is successfully reinitialized.

Reverse Widget steering button

In Reverse, select Widget and use Select button… below Enhanced reverse view. A confirmed single short steering-wheel press assigns its Android key code without switching cameras. Cancel or Android Back leaves the previous assignment unchanged; the square reset clears only the assignment.

Subsequent single short presses switch the existing composition and its widget together after Android's inclusive multi-press window expires. Double presses and holds do not switch cameras or fall back to single presses. After their release, the next press starts a new gesture: three quick short presses are Double + Single; four are two Doubles. A known OEM long code means Hold, which has no Reverse action; otherwise Hold is timed from the ordinary DOWN. Timer/native feedback for the same hold is deduplicated. Learning stores the base button code and consumes its release without executing a camera action. Enhanced reverse, the widget and at least one front-camera integration must be enabled, and the composition must already be active. Existing per-camera visibility/integration rules apply; the button does not open cameras, change calibration or add automatic switching in D. Calibration and other foreground app tabs do not redirect the button to a background composition.

The separate global Switch by gear setting is off by default. Its row appears immediately below front-camera integration for Rear, Left and Right, and below Enhanced reverse view for Background and Widget. It is available only while at least one camera is integrated; disabling every integration does not erase the saved preference. Unavailable switches use a neutral track and dimmed thumb/text while retaining their saved ON/OFF position, in both themes. R activation never waits for the stock camera UI. With gear selection enabled, the session remains active while R or the stock camera UI is active. Entering D selects integrated front cameras, and entering R selects rear cameras. N and P retain the selected view during a session, or select Front on a cold opening. Repeated telemetry does not undo manual selection. Nonintegrated panes keep their rear view in either mode. Automatic selection does not require the selector widget to be visible.

All assigned-button gestures, repeats and releases are consumed immediately, including when no eligible composition is active. Only our single-press action is delayed; consumed events are not forwarded or replayed. Other eligible Accessibility key filters receive their own event copies, but arbitrary apps and downstream stock handlers are not guaranteed delivery. Reset the assignment to restore normal handling. Explicit app Shutdown ends interception until the app is reopened. The assignment survives app restarts.

This feature uses the app's existing Accessibility service. If the key filter is unavailable, learning reports that condition instead of saving a simulated assignment. Some BYD firmware handles keys before Android Accessibility receives them; support for every physical button is not guaranteed.

Rearview mirror and UI preferences

Front-camera integration is off by default. When enabled, the rear/front selector remembers its choice; each source has independent calibration and a local preset, with an explicit rear-to-front copy. Turning integration off returns to the rear source without erasing front settings or bindings. The sources share one widget's placement, display target and border.

Two independent learned-button rows switch source or show/hide the widget using Single, Hold or Double. Reset clears only that row's button, retaining its gesture. Duplicate assignments are allowed: every eligible matching action runs, and simultaneous Mirror effects use one state update. Source switching requires Mirror and front integration; visibility requires Mirror enabled and never enables it. Switching a hidden source does not reveal the widget, and normal app/panorama gates remain. Confirmed base/long pairs are 305/306 (star), 304/312 (microphone), 88/303 (previous track), 87/302 (next track). Panorama 294 and wheel 353 have no assumed native-long code and use timed Hold.

Enable the rearview mirror and grant Android overlay permission when prompted. Its independent placement, calibration, preset and border settings do not modify Reverse or Blind profiles. Drag the external widget to move it; touch and hold to hide it until BYD Extend is opened again. It is hidden while BYD Extend is open. The default-enabled Do not show while panorama is open option also hides tablet output during the stock camera UI, not cluster output; switching it off does not disable app-foreground or long-press hiding. A hidden widget leaves no input window blocking other apps, while taps inside the visible widget do not pass through.

Blind cameras have the same default-enabled panorama option independently for the rear and front groups, directly below each group's enable switch. Panorama opening/error status appears next to the Reverse camera-section title; direct-camera readiness remains a separate status.

Global Auto-start controls autonomous startup and recovery; turning it off still permits manual Mirror use. An unavailable instrument cluster does not redirect the widget to the tablet. Blind and Mirror editors support bounded independent width/height and drag/resize, with 0.1% placement precision. Each tab/subsection has an independent scroll position, including Integrations and Settings categories and their separate sidebars. A data-only process session captures current selections and measured viewports on navigation and Activity pause/stop/destroy/disposal, then restores them after layout. Android saved-state restoration remains available when the system restores the task. Explicit Shutdown detaches the old session; scrolling never writes configuration.

Fresh installations start in English regardless of the tablet language. Existing effective language choices are preserved, and the Chinese selector label remains 中文 in every language.

Switches retain their ON/OFF appearance while an operation is pending, without a yellow or centered intermediate state; normal toggle and press feedback remain. Mirror uses the standard compact enable switch. The six text navigation tabs have equal widths; Debug remains a compact square, bug-icon-only button with a localized accessibility label.

BYD integrations and exterior sounds

BYD integrations uses the same category layout as Settings: Turn signals, Music and lighting, Weather, AVAS (external speaker), and ADB recovery. Existing integration settings are preserved.

ADB recovery restores previously opened and authorized local ADB; it cannot perform the first unlock or authorize an unknown key. It is enabled by default and runs in the app service before shell-helper startup. A working authenticated port5555 is left alone. Otherwise, previously granted WRITE_SECURE_SETTINGS access lets the app request system ADB/Wi-Fi debugging startup and discover the tablet's local TLS endpoint. The existing Extend RSA identity authenticates that endpoint; the app requests port5555, verifies it with a real command, and cleans up only TLS it enabled. No arbitrary port scan, test port5556, forced Wi-Fi0-to-1 bounce or new watchdog is used.

While Wi-Fi is connected and recovery remains unresolved, the app requests Wi-Fi debugging every 15 seconds only when its setting is0. Manual Retry is immediate. A setting value does not prove consent refusal, dialog visibility or successful ADB. The real status and Retry rows remain visible when disabled. An optional movable reminder starts after5 seconds waiting for Wi-Fi and disappears on connection or a one-second hold, without canceling recovery or returning in the same cycle. Its appearance and placement are configurable. Full daemon-OFF/reboot recovery on the vehicle remains unverified; this is not a guaranteed way around firmware restrictions.

AVAS has separate Lock, Unlock, Power off and Power on profiles. Each starts disabled, with a protected one-second Test sound, random playback off and volume15%. Existing settings and selections, including an empty selection, are preserved on upgrade. Add audio files through the system document picker; supported audio is copied privately and prepared before playback. Each profile has its own file list and selection. Imports preserve the selected file and do not overwrite duplicates. Audio libraries are not included in camera-preset JSON files.

The profile header toggles its automation. Volume is independent per profile, from0% (silent) to100%, with the slider and percentage below its title. Start plays the selected ready file through the exterior route even when that profile's automatic switch is off. Stop cancels only the same profile's manual playback or queued request, not automatic event sounds. Automatic random playback excludes Test and skips an event when no imported file is ready. Nearby ordinary events play sequentially; a ready enabled Power-off sound replaces its associated automatic Unlock. Initial, repeated and unknown vehicle states do not trigger playback.

The file list stays open when selecting a sound and shows its duration. Long names are shortened visually without changing the stored filename. Imported files can be deleted; deleting the selected file selects Test. Only private copies are removed, never the original document. The note button plays that exact row through the OEM driver-navigation speaker, not ordinary cabin media, regardless of selection, random mode or automation enablement. It becomes Stop while playing; another note replaces it. Closing the list, leaving the screen/backgrounding, process death or deleting that file stops only this listening session. Start and automatic events take precedence and use the exterior speaker; a note cannot interrupt or queue behind exterior playback. Stopped notes do not resume. Both routes apply the profile's volume and restore their saved route/volume state without a media-channel fallback.

Exterior playback uses a private AudioTrack LoudnessEnhancer instead of clipping PCM samples with a fixed multiplier. Player volume follows the stored percentage; the effect target ranges from0 to2800mB (+28dB). Live volume adjustments update both controls, and0% remains silent. If the effect is unavailable, playback continues with player volume only and records that fallback. The stored0–100% setting and internal note audition are unchanged. Actual loudness depends on the file and vehicle audio path; the effect target is not a measured speaker-level increase.

The existing shell helper owns playback so losing the application process does not itself destroy the player. A helper restart starts from current telemetry without replaying old events. Explicit Shutdown stops playback and automatic recovery until BYD Extend is opened again. The exterior route uses device3 and the complete selected file without an added silent prefix; internal note audition also has no added silence. The existing80ms OEM preparation remains. This A/B candidate preloads the complete exterior PCM into a STATIC AudioTrack before playback; internal note audition remains STREAM. STATIC uses memory proportional to the decoded file length. Initial STATIC playback was audibly complete, but a later morning session still lost the beginning, including with an experimental 500 ms prefix. The remaining acoustic cause has not been established; complete PCM accounting is not proof of complete audible output. NAV volume and mute are saved, NAV is muted during preparation, then volume1 and unmute are applied for exterior playback. Cleanup restores the original values. Transient-exclusive focus is requested again approximately every120ms only while an exterior sound is playing, including buffer drain, and released afterward; simultaneous navigation speech is not guaranteed. Main-route rejection is not treated as success merely because an optional SDK or audio-focus request succeeded. Partial preparation and interrupted older device3/CHANNEL0 sessions retain their matching cleanup. Saved user settings are not reset.

With Auto-start and either automatic AVAS profiles or ADB recovery enabled, notification-listener access is required for early recovery. The application provisions its own listener through already authorized local ADB and verifies access locally; the Permissions indicator does not need ADB for that readback. Notification contents are not read or recorded. Listener callbacks, a separate shell keepalive and the existing service/alarm restore the runtime without waiting for the screen to turn on. Automatic recovery still respects Auto-start, explicit Shutdown and migration gates.

While the runtime is active and an automatic AVAS profile is enabled, it holds a partial wake lock even with the screen or ignition off. Disabling all profiles, explicit Shutdown or service teardown releases it. This may increase parked power consumption; the additional cost has not been measured. A wake lock does not survive kernel reboot: the recovery chain must restart the application and shell processes. Local ADB must still be available for a cold helper launch; the separate app-owned ADB integration can request system recovery before that launch. When authorized ADB is available, the app provisions and locally reads back its own user's WRITE_SECURE_SETTINGS, exact notification listener and Accessibility access regardless of feature switches. Existing grants are not revoked when a feature is disabled, and other apps' components are retained. The accepted ADB authorization-expiry setting is read/written/read back as0.

The combined Production path and recovery after kernel reboot still require vehicle validation; compatibility with other firmware is not established. Configure and audition at low volume while parked. AVAS does not replace the vehicle's stock pedestrian-warning sounds or silently fall back to a cabin speaker.

Sharing diagnostics

Settings can share logs or create a compatibility package. Compatibility export displays the current phase, file, file count, and transferred bytes, and can be cancelled without sharing a partial archive. It supports individual files up to 2 GiB and a total source payload up to 4 GiB; missing or inaccessible optional files are reported in the package instead of stopping the export. Individual text captures remain limited to 16 MiB. Data is streamed rather than held in RAM; temporary files and ZIP overhead can require additional disk space beyond the source-data budget.

Diagnostic archives also retain early AVAS listener/recovery events and current/previous shell keepalive journals. Settings -> Logs -> Record logcat enables continuous capture of all buffers; the switch defaults OFF and remembers your choice. OFF stops recording without deleting history. While enabled, the recorder uses the existing shell daemon independently of AVAS profiles or Auto-start, including with ignition/screen off. Logging alone does not start audio or revive the app. Auto-start controls automatic startup/recovery, not ongoing recording; explicit Shutdown still stops it. No new AVAS profile or runtime setting is enabled by recording. It resumes after daemon recovery and replays the system buffers still available at that time; session markers distinguish that replay from new events. No process records while the kernel is stopped, and already-overwritten buffers from an unavailable interval cannot be recovered.

History is appended without a size/time quota or rotating deletion. Recording pauses below 512 MiB free space, retaining existing evidence, and resumes when space is available. It adds storage/I/O load and contains other apps' system messages; share only with the intended analyst. Clear logs stops the writer, clears its history and resumes without reimporting pre-clear records. The ZIP includes the complete bounded-at-export file as system/logcat-continuous.txt and writer state as system/logcat-continuous-status.txt, alongside the unchanged export-time snapshot. Both Share and Save as show an archive progress dialog: processed source volume, total and remaining bytes, and percentage once the total is known. Earlier system collectors show indeterminate progress because their output size is not yet known; continuous history uses one fixed size bound, so a growing Logcat cannot extend the export indefinitely. Save as then shows the actual ZIP-copy progress for the chosen destination. Finalization is separate from byte consumption; success is reported only after closing the ZIP/destination. Canceling preparation or copy leaves source logs intact and removes only the incomplete export where possible. This diagnostic build removes the experimental 500 ms exterior silent lead; player mode, gain, routing and focus policy remain unchanged. Complete audible playback is not yet verified.

Compatibility and requirements

• Primarily tested on the Chinese BYD Sea Lion 07 EV 2025 with DiLink 5.0.
• Camera overlays have also been exercised on a BYD Sea Lion 06 EV with older DiLink firmware; this does not establish full feature parity.
• Other BYD models and firmware versions are not confirmed compatible.
• BYD Extend has its own Android permissions and local ADB authorization. Enable local ADB on the tablet and accept its authorization prompt; authorization is not shared with the legacy package.
• Camera access is required. Parking views require compatible proximity and speed telemetry.
• Weather requires location permission and internet access. Stock weather refresh and the optional learned Reverse button share the app's Accessibility service, enabled through local ADB.
• Instrument-cluster camera and music output require compatible BYD display services.

Installation

1. Download byd-extend-v1.0.0.apk from GitHub Releases.
2. Install it manually, grant camera/location access as requested, and accept the BYD Extend local ADB authorization prompt.
3. Open Налаштування, configure background start, and enable Авто-запуск if recovery after boot and application replacement is required.
4. Configure and validate the guard and every camera view while parked before normal use.

Do not uninstall the legacy app before a successful full migration if its settings or calibration slots are needed. Do not run both applications as competing vehicle-control owners.

License

Copyright (C) 2026 sunlixWhyNotAvailable.

This project is free software licensed under the GNU Affero General Public License v3.0 only. Modified versions that are distributed or offered for remote network use must provide their corresponding source under the same license.