PRIVACY / 2026-09-09
Privacy
Kejian does not require an account. You may keep your schedule entirely on your phone; cloud data is used only after you sign in and choose to upload it.
Ask your notes and mind maps
Only when you request a mind map or ask a question is the necessary text from that note sent through Kejian to the configured third-party text model. Ask your notes retrieves relevant excerpts from the current note and includes your question and a limited recent conversation; it does not search other users' notes. Some AI providers may operate outside your country. Do not submit private or confidential content you are not authorized to process. Conversation history stays on your device, separated by account and note. The server does not log the original note, question or conversation text. To prevent duplicate token charges on retries, Insights answers and citations are cached on the server for 7 days and may contain excerpts from your note, with up to about one hour of cleanup delay. Request markers without content remain for 30 days. Deleting your account also removes these records. AI can still make mistakes; check the cited source text.
Data we handle
Without an account, events, term settings, widgets and preferences stay on your device. Custom widget images also remain local. After sign-in, the server stores your email, irreversible password and session-token hashes, and cloud saves you upload. Bot verification temporarily stores security and rate-limit records. Kejian does not require a phone number or read contacts or precise location.
How it is used
Your email identifies the account, your password authenticates it, and cloud schedules let you restore data on another device. Rate-limit records prevent automated registration, brute-force login and abuse. Email verification and password recovery are not yet available.
Storage and security
Account and schedule traffic uses HTTPS. Passwords are salted and hashed with Argon2id; plain passwords and plain login tokens are not stored. The account service currently runs in Hong Kong with access controls, least-privilege configuration and daily backups retained for up to 14 days.
Your choices
You can skip sign-in, sign out, choose which local or cloud copy resolves a conflict, or delete the account in Settings. Deletion removes the online account and schedules immediately; rotating backups expire within 14 days. Local data on the current phone is kept.
Notifications and download counts
Android and your phone manufacturer deliver reminders. Kejian currently contains no ad SDK, third-party analytics SDK or third-party login. The website records daily download requests and estimated unique downloads with irreversible daily visitor digests rather than raw IP addresses.
AI schedule assistant
When you choose an image or send a schedule command, the necessary image, command and current event records go to the Kejian server and then to a third-party vision model. Original images are not retained. The server records a content digest, status, structured previews, result counts, latency and token usage. Submitted schedule AI requests can be queried by the submitting account for 24 hours to recover status and unapplied previews without running or charging twice. Every structured result is validated and still requires your confirmation.
Recording, transcription and lesson summaries
Recordings are created in app-specific storage on your phone. The microphone foreground service starts only after you actively begin recording in the app and grant microphone access. Recording can continue while you switch apps or lock the screen. Pause stops writing audio while retaining the file; resume appends to the same recording, and Stop closes the microphone service. Allow notifications to see its status and controls. Kejian never starts recording at boot or silently restarts it after the process is stopped. Free users can attach or export local audio without uploading it. Audio is sent temporarily only when you request AI transcription and summarization, and the server deletes that copy after success, failure or timeout. Transcript, summary, key points, tasks and event links may enter your cloud schedule; the original local audio path is always removed before cloud sync.
Background work and local recovery
Only tasks you initiate enter the background queue. To resume transfers or recover results, the app stores task input, progress and results in private storage, separated by account and excluded from cloud saves. Image and schedule-command recovery is limited to 23 hours; image, schedule-command and note AI queue caches are kept for up to seven days and cleaned on the next run after expiry. Completed recording and file-recognition results are retained until successfully saved to local notes or preview history, then their temporary result copies are removed. Conversations and notes you keep are unaffected. Tasks may use time-limited wake locks and show status notifications. You may choose to relax Android battery or background-data restrictions, which can use more battery. This does not bypass force-stop or system time limits and never starts recording automatically.
Ask your notes and public references
Questions use the current note, transcript and recent question context. No other users’ notes are retrieved. Answers and citations are cached for seven days for safe retries, and request markers for thirty days. Summaries and questions may extract general topic keywords to search public web excerpts; the search service does not receive the complete notes or audio. Online supplements are distinguished from the recording and include sources. Mathematical figures are illustrative examples, not original classroom images. Verify important claims.
Diagnostic logs
If an AI task stops, the app may upload an error class, short error message, app version, device model and diagnostic fields without schedule text. Logs exclude original images, passwords, access tokens and AI API keys.
Updates
This page will be revised when data collection, hosting location or account capabilities materially change. If sign-in is unavailable, all local scheduling features remain usable.