AI Web Chat SDK

A secure embedded AI conversation layer: browser runtime, Web Component, device identity, request signing, anti-replay, short-lived sessions, quotas and service-side controls.

Engineering note ↗Back to work

Rust/WASMTypeScriptFastAPIRedisWeb ComponentsHMACAnti-ReplayTDD

ARCHITECTURE

Security-sensitive work stays behind explicit boundaries.

Web pageHost application embeds the SDK

Web ComponentUI + conversation continuity

Rust / WASMFingerprint digest, signing, anti-replay data

FastAPIDevice, auth, session and chat endpoints

RedisStable mapping, quota, session and rate-limit state

AUTH FLOW

Server-issued identity, then short-lived session authority.

WASM computes versioned fingerprint digest ↓ POST /api/v1/device/init ↓ server HMAC → stable fingerprint key → device_id + device_token ↓ POST /api/v1/auth/init ↓ server verifies device_token → session_key + JWT ↓ WASM signs chat request with session_key

Identity

Server-issued device_id

The browser does not mint its own device identity. The mapping is derived and owned by the service boundary.

Integrity

Signed + replay-aware requests

Request signatures are validated before accepted usage is counted, preventing duplicate signatures from consuming quota twice.

Abuse control

Quota and rate layers

Daily device quota, short-lived sessions and IP minute-level limits represent distinct operational concerns.

20accepted user requests per device per Asia/Shanghai day

40recent user/assistant messages retained as conversation context

5mshort-lived session lifetime in the current implementation

Implementation snapshot.

The same SDK powers Ask Portfolio AI.

Browser-side SDK, service security controls and MCP-backed portfolio knowledge form one end-to-end AI interaction path.