Deep research asks 2-3 clarifying questions first. When the user answers
with a bare affirmation ('yes', 'ok', 'go ahead'), that short message
becomes latest_message and the query-synthesis fallback returned it
verbatim, so research ran on the literal word 'yes'.
In ResearchHandler.synthesize_query, when synthesis can't run (history
too short) or fails, fall back to the earliest substantive user message
(the original ask) only when the latest message is an explicit
affirmation/continuation phrase or is empty/punctuation-only. There is
deliberately no length heuristic: a short answer like 'UK', 'C++', or
'Rust' in a clarification flow is a real topic and is left untouched.
Tests cover query/topic selection: bare 'yes' -> original ask, short
answers (UK, C++) kept, short-only-substantive message kept, and a
multi-word follow-up still flows through synthesis.
The 600s wall-clock cap in research_handler.start_research was too short
for local / edge LLMs to finish a deep-research synthesis — long
extraction passes plus a slow final report routinely blew past 10
minutes and the run was killed with partial results.
Introduce research_run_timeout_seconds (default 1800s = 30 min) in
DEFAULT_SETTINGS and resolve it at start_research entry when the caller
hasn't pinned hard_timeout. Bound the resolved value at [60, 86400] so a
misconfigured settings.json can't either disable the safety net or
explode into a multi-day hang. Existing call sites in research_routes.py
and chat_routes.py keep working unchanged — they don't pass hard_timeout
and now pick up the new default.
Closes#595.
