Summary

When the current time was moved from the system prompt to session_status for cache efficiency (66eec29), it created a gap: TUI and web clients don't provide timestamp context to agents.

The Problem

• Channel plugins (Discord, Telegram, etc.) inject timestamps into messages: [2026-01-28 18:46 CST] User: hello
• TUI and web clients send raw messages without timestamps
• Frontier models can call session_status to get the time, but smaller models (7B, etc.) won't think to do this
• Result: lesser models have no way to know the current date/time

Proposed Solution

Gateway should inject timestamps into incoming user messages when not already present. This:

• Keeps the system prompt cacheable (no per-request time changes)
• Gives all models timestamp context from the most recent message
• Requires no changes to individual clients (TUI, web, future clients)
• Matches existing behavior of channel plugins

Why Not Just Document session_status?

Smaller models struggle with multi-step reasoning ("I don't know the time → which tool has it → call that tool"). They need explicit context, not self-serve tools. Injecting timestamps is the same pattern that already works for Discord/Telegram users.

Related

Closes gap identified in #3652 (closed as intended, but surfaced this edge case).