Mark genuinely timeless material as evergreen/no-expiry — principles and mental models don't need artificial expiration dates

Why This Is a Rule

The expiration system (Tag time-sensitive information with explicit expiration dates at capture (expires:YYYY-MM-DD) — never rely on memory to track what is time-bound, When uncertain about lifespan, expire at 3 months not 1 year — renewing valid items is cheap, but undetected stale information is dangerous, Monthly expiration sweep: review all past-due items, then archive expired ones and renew still-valid ones with fresh dates) is designed for time-sensitive information — pricing, policies, technical specifications that change. Applying it to genuinely timeless material creates unnecessary maintenance: Newton's laws of motion don't expire, the Eisenhower matrix doesn't need a renewal date, and first-principles reasoning frameworks remain valid indefinitely. Forcing these through monthly expiration sweeps wastes review time on items that will be renewed every single cycle.

The "evergreen" or "no-expiry" designation is the explicit exception to the default-expiration rule. It tells the system: "This item has been evaluated for temporal sensitivity and determined to be durable. Exclude it from expiration sweeps." Without this designation, timeless items either get swept into the same maintenance loop as time-sensitive items (wasting effort) or get no expiration tag at all (making them indistinguishable from items that were simply never tagged).

The key is "genuinely" timeless — this designation requires positive evaluation, not just absence of a known expiration. Principles, frameworks, mental models, mathematical relationships, and foundational domain knowledge qualify. Specific implementations, tool-dependent procedures, and anything referencing current technology do not — those change, often faster than you'd expect.

When This Fires

• When tagging items with expiration dates (Tag time-sensitive information with explicit expiration dates at capture (expires:YYYY-MM-DD) — never rely on memory to track what is time-bound) and encountering principles or frameworks
• When monthly sweeps (Monthly expiration sweep: review all past-due items, then archive expired ones and renew still-valid ones with fresh dates) repeatedly renew the same timeless items
• When building a reference system and wanting to reduce unnecessary maintenance overhead
• Complements Tag time-sensitive information with explicit expiration dates at capture (expires:YYYY-MM-DD) — never rely on memory to track what is time-bound (expiration tagging) by defining the exception class

Common Failure Mode

Over-classifying as evergreen: "My notes on React hooks are timeless." React hooks are tied to a specific framework version and will change. Genuine evergreen content is framework-independent: the principle of component composition is timeless; the React-specific implementation of it is not. When in doubt, apply expiration — you can always reclassify as evergreen during a renewal sweep.

The Protocol

(1) When capturing information, after assessing temporal sensitivity (Tag time-sensitive information with explicit expiration dates at capture (expires:YYYY-MM-DD) — never rely on memory to track what is time-bound), ask: "Will this still be accurate in 5-10 years regardless of technology, organizational, or contextual changes?" (2) If yes → tag as evergreen/no-expiry. Examples: fundamental principles, mathematical relationships, human psychology findings, logical frameworks. (3) If no or uncertain → apply normal expiration. (4) During monthly sweeps (Monthly expiration sweep: review all past-due items, then archive expired ones and renew still-valid ones with fresh dates), if you find yourself renewing the same item for the third consecutive time, consider reclassifying it as evergreen. Three consecutive renewals suggest the content is more durable than originally assessed. (5) Keep evergreen items in a distinct section or with a distinct tag so they're identifiable in the system without requiring individual inspection.