When a custom agent has `MultiTurnEnabled=false`, `applyAgentOverridesToChatManage`
sets `chatManage.MaxRounds = 0` to signal "no history". Two pipeline plugins
mistreated this zero value as "use the global default" and silently re-loaded
session history into the LLM context:
- `PluginLoadHistory` fell back to `Conversation.MaxRounds` when
`chatManage.MaxRounds == 0`.
- `PluginQueryUnderstand.loadHistory` had the same fallback, and even when
`LOAD_HISTORY` was skipped it would re-populate `chatManage.History`,
leaking previous turns into rewrite, image analysis, and the final answer.
The RAG branch in `session_knowledge_qa` also added `LOAD_HISTORY`
unconditionally, unlike the pure-chat branch which guarded it with `hasHistory`.
This change:
- Treats `chatManage.MaxRounds <= 0` as an explicit disable in both plugins;
no fallback to global config.
- Makes the RAG pipeline consistent with the pure-chat path by gating
`LOAD_HISTORY` on `hasHistory`.
- Removes the duplicated `Current Time: {{current_time}}` line from
`agent_system_prompt.yaml`. The agent already receives a fresh
`<runtime_context><current_time>` block with each turn from
`observe.buildRuntimeContextBlock`, so the static placeholder was
redundant.
The ReAct agent path (`session_agent_qa`) already checked `MultiTurnEnabled`
directly and is not affected.
Closes#1479
wizardchen
e9be53e830