I Tracked 530 Working Memory Entries and Found a Retention Curve

Fazm Team··2 min read

I Tracked 530 Working Memory Entries and Found a Retention Curve

Over six months of using AI coding agents daily, I logged every entry that went into my working memory files - MEMORY.md, CLAUDE.md, and project-specific context files. The total hit 530 entries. Then I tracked which ones actually got used and which ones just sat there consuming context window space.

The Retention Curve

The data tells a clear story:

  • Week 1: 95% of new entries are actively useful
  • Week 2: drops to 70%
  • Week 4: drops to 40%
  • Week 8: drops to 15%
  • Week 12+: drops below 5%

Most working memory entries have a half-life of about two weeks. After that, the context has shifted enough that the entry either no longer applies or the agent has internalized the pattern through repeated exposure.

Why Old Entries Hurt

Stale memory entries do not just waste context tokens. They actively mislead the agent. An entry saying "the auth endpoint returns 401 for expired tokens" was true three months ago but now the API returns 403. The agent trusts the memory entry over the actual error response it receives, leading to debugging sessions that chase the wrong problem.

Regenerate, Do Not Accumulate

The best approach is treating the AI profile like a cache, not an archive. Every two weeks, regenerate the memory file from scratch using only the last 14 days of interactions. This captures current patterns and drops stale information automatically.

The regeneration process:

  1. Review the last two weeks of agent interactions
  2. Extract patterns that repeated more than three times
  3. Note any active workarounds or environment-specific quirks
  4. Discard everything else

What Survives

Some entries are genuinely long-lived - fundamental project architecture decisions, environment setup notes, and personal preferences (like "never use em dashes"). These form a stable core of maybe 30-40 entries that persist across regeneration cycles. Everything else should be treated as temporary.

Fazm is an open source macOS AI agent. Open source on GitHub.

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