Deep research generated search queries from the LLM's training-cutoff
knowledge, so it emitted stale-year queries like "best Python tutorials
2025" when the actual year is later (issue #1341). The chat/agent path
already grounds the model with "Today is ..." (src/agent_loop.py); the
deep research planning and query-generation prompts had no equivalent.
Add a small current_date_context() helper and prepend it at the plan and
query-generation prompt sites (and the research_handler plan preview path
that reuses RESEARCH_PLAN_PROMPT). System-TZ local, portable strftime.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
