Add per-visitor session management for the WebChat Web/API access mode:
list a visitor's conversation threads, fetch a thread's messages, and
delete a thread.
Authorization: visitorId is a client-asserted request param, so it cannot
be trusted on its own — deriving conversationId from it and then checking
ownership against it is tautological (any caller passes). Instead, /stream
issues a per-visitor token = HMAC-SHA256(jwtSecret, channelId:visitorId),
returned in the meta event; the management endpoints require it back via
the X-MC-Visitor-Token header and verify it in constant time. The signing
secret is server-only (unlike the public channel API key) and the channelId
in the payload makes tokens non-portable across channels.
Includes regression tests for token issuance/verification semantics
(forged visitorId rejected, cross-visitor and cross-channel tokens rejected,
tampered tokens rejected).
The WebChat stream endpoint resolves agentId only when the
(visitorId + sessionId) conversation is first created; later requests
with a different agentId reuse the existing conversation's agent and
silently ignore the new value. Document this on WebChatRequest.agentId
so integrators know to use a new sessionId to reach another agent.
Rename the webchat channel from "embed widget" to "Web / API access" (key
unchanged, docs/i18n only) and extend the backend SSE endpoint for pure
backend integration:
- WebChatRequest gains optional agentId (route one Key to multiple agents;
rejected unless the agent shares the channel's workspace) and sessionId
(one visitor, multiple isolated threads).
- sessionId is validated ([A-Za-z0-9_-]{1,64}) and only composed into the
server-derived conversationId — raw conversationIds are never accepted, so
the key+visitor namespace still bounds every thread.
- A `meta` SSE event echoes the effective sessionId/conversationId at stream
start so callers can persist and re-address a thread.
- Memory stays attributed per visitor (api:<visitorId>), shared across that
visitor's sessions.
All new fields are optional; omitting them reproduces the prior behaviour
byte-for-byte. Refs matevip/mateclaw#295.
IM channels (Feishu, DingTalk, WeCom, etc.) and the WebChat widget were
calling saveMessage without token usage parameters, causing promptTokens
and completionTokens to default to 0. This made the Token Statistics
module report significantly lower numbers than actual usage.
Root cause: the _usage_final event (containing promptTokens /
completionTokens) emitted by the agent graph at stream end was not being
captured in these paths, unlike ChatController's StreamAccumulator which
already handles it correctly.
Fix: capture _usage_final events in doOnNext handlers for:
- ChannelMessageRouter sync path (non-streaming IM adapters)
- ChannelMessageRouter streaming path (DingTalk, etc.)
- WebChatController SSE stream
Refs #214 (remaining String-API paths covered by follow-up).
