Tag time-sensitive information with explicit expiration dates at capture (expires:YYYY-MM-DD) — never rely on memory to track what is time-bound

Why This Is a Rule

Information systems accumulate stale data silently. A pricing document from 2023 sits alongside a pricing document from 2025, and without date-checking, you might use the wrong one. Meeting notes from a planning session that was superseded by a new strategy remain in the system looking authoritative. A technical reference for a software version you no longer use answers questions with outdated answers. Stale information isn't just useless — it's actively harmful because it looks identical to current information.

Explicit expiration dates solve this by making temporal validity a first-class property of the information, visible alongside the content itself. The "at capture" timing is critical: at the moment you save a piece of time-sensitive information, you have the context to assess its lifespan. "This pricing is valid through Q2" → tag it expires:2025-06-30. "This API endpoint is being deprecated" → tag it expires:[deprecation date]. Waiting to add expiration dates later means they'll never be added, because you won't remember which items are time-bound.

The explicit format (expires:YYYY-MM-DD or equivalent) makes expiration searchable and automatable. You can filter your system for expired items, set up automated reminders, or build views that surface items approaching expiration. Without a structured format, expiration metadata is trapped in prose ("Note: this may change next quarter") and invisible to search.

When This Fires

• When saving any information that has a known or estimated shelf life
• When your reference system contains a mix of current and outdated information
• When you've acted on stale information because it wasn't marked as time-sensitive
• Complements Title reference items with the words your future self will search for, not the words that categorize what it is (search-oriented naming) with the temporal dimension of reference management

Common Failure Mode

Undifferentiated storage: all reference items treated as equally valid regardless of age. A system with 1,000 reference items where 200 are expired but unmarked means 20% of your retrievals return outdated information. Without expiration metadata, you can't distinguish current from stale without manually checking each item.

The Protocol

(1) At the moment of capturing time-sensitive information, assess its lifespan: "How long will this remain valid?" (2) Add an explicit expiration tag: expires:YYYY-MM-DD. Use whatever format your system supports — the key is that it's searchable and filterable. (3) Common expiration heuristics: Pricing/quotes → expire at the stated validity date or 90 days. Meeting decisions → expire at the next relevant meeting or review cycle. Technical references → expire at the next version release. Regulatory/policy → expire at the next annual review date. (4) Set a monthly or quarterly reminder to search for expires: dates that have passed. Review expired items: delete, archive, or update with current information. (5) When uncertain about lifespan, err toward shorter expiration (When uncertain about lifespan, expire at 3 months not 1 year — renewing valid items is cheap, but undetected stale information is dangerous) — it's easier to renew a still-valid item than to catch a silently expired one.