Small model testing showed the label did not meaningfully help:
- Sub-3B models fail regardless of format
- 8B models untested with label specifically
- Frontier models never needed it
The bracket convention [Wed 2026-01-28 22:30 EST] matches existing
channel envelope format and is widely present in training data.
Saves ~2-3 tokens per message vs the labeled version.
Changes [Wed 2026-01-28 20:30 EST] to [Current Date: Wed 2026-01-28 20:30 EST].
Tested with qwen3-1.7B: even with DOW in the timestamp, the model
ignored it and tried to compute the day using Zeller's Congruence.
The "Current Date:" semantic label is widely present in training data
and gives small models the best chance of recognizing the timestamp
as authoritative context rather than metadata to parse.
Cost: ~18 tokens per message. Prevents hallucination spirals that
burn hundreds or thousands of tokens on date derivation.
Changes [2026-01-28 20:30 EST] to [Wed 2026-01-28 20:30 EST].
Costs ~1 extra token but provides day-of-week for smaller models
that can't derive DOW from a date. Frontier models already handle
it, but this is cheap insurance for 7B-class models.
Replace verbose formatUserTime (Wednesday, January 28th, 2026 — 8:30 PM)
with the same formatZonedTimestamp used by channel envelopes (2026-01-28
20:30 EST). This:
- Saves ~4 tokens per message (~7 vs ~11)
- Uses globally unambiguous YYYY-MM-DD 24h format
- Removes 12/24h config option (always 24h, agent-facing)
- Anchors envelope detection to the actual format function — if channels
change their timestamp format, our injection + detection change too
- Adds test that compares injection output to formatZonedTimestamp directly
Exported formatZonedTimestamp from auto-reply/envelope.ts for reuse.
Verifies that America/New_York correctly resolves to midnight for
both EST (winter, UTC-5) and EDT (summer, UTC-4) using the same
IANA timezone. Intl.DateTimeFormat handles the DST transition.
Messages arriving through the gateway agent method (TUI, web, spawned
subagents, sessions_send, heartbeats) now get a timestamp prefix
automatically. This gives all agent contexts date/time awareness
without modifying the system prompt (which is cached for stability).
Channel messages (Discord, Telegram, etc.) already have timestamps
via envelope formatting in a separate code path and never reach
the agent handler, so there is no double-stamping risk.
Cron jobs also inject their own 'Current time:' prefix and are
detected and skipped.
Extracted as a pure function (injectTimestamp) with 12 unit tests
covering: timezone handling, 12/24h format, midnight boundaries,
envelope detection, cron detection, and empty messages.
Integration test verifies the agent handler wires it in correctly.
Closes#3658
Refs: #1897, #1928, #2108
