Timestamp

An in-session mode that prints the current time, with the delta since the last printed time, at the start and/or end of each turn. Off until the user turns it on. There is no storage: the current mode and time zone are whatever the most recent /timestamp command and time-zone line in this conversation set (scan back for them).

The command

/timestamp <arg> arrives in the message text or as a slash command with arguments. Arguments are case-insensitive:

Reply on that turn, in this order:

1. Timestamps <enabled|disabled> at <start|end|start and end> of turn. ("disabled" only for off, naming the mode being turned off; "start and end" for both).
2. Only when the mode goes from off to on, the time-zone line (below).
3. The new mode's checks for this same turn: a start check now if it includes start, an end check at the close if it includes end. off means no checks on that turn.

Asked which mode is active? Say it; don't run a time check for that.

Time zone

Chosen once, when the mode goes from off to on:

• Known from the user's saved preferences, instructions or this conversation: Using your preferred time zone <TZ>. To change, just request a different time zone.
• Otherwise UTC: Using default UTC for timestamp time zone. To change, just request a different time zone.

The user can switch at any time in plain words ("use Pacific time"): acknowledge in one line and use the new zone from then on.

Reading the time

Never print a time you did not just read from a tool. Sources, per conversation:

1. A dedicated time tool, if your tool list has one (e.g. user_time_v0 in the Claude mobile app). Try it once; if it fails or is absent, don't try it again this session.
2. Any shell or code-execution tool (Bash, bash_tool, a terminal), with the zone as an IANA name: TZ=America/Los_Angeles date '+%Y-%m-%d %H:%M:%S %Z %s' (the last field is epoch seconds, for the delta).

• Compute deltas from epoch seconds, not by subtracting clock strings.
• Never use the date in your system prompt or context: it has no time of day and may be in another zone.
• Write the time into your reply text; tool output is often hidden from the user.
• No source available: print [no time source available this turn].

Format and placement

[2026-08-01 14:32:07 PDT, +00:03:12]
[2026-08-01 14:32:07 PDT, first check]

• Own line, square brackets, zone label always shown.
• Delta +HH:MM:SS since the last printed timestamp; past 24 hours +Nd HH:MM:SS.
• first check instead of a delta for the conversation's first one.
• start: the very first thing in the turn, before any other text or tool call (on the /timestamp turn itself, right after lines 1-2 above).
• end: the very last thing, after all other content and tool calls.
• both: both; the end check's delta is measured from the start check.

Self-check

If the mode is on and the previous turn is missing a check it should have had, or shows a time that wasn't read from a tool, re-read this skill and follow it strictly from now on.