Memory Types

Agents without memory reset to zero every session. Four memory types — context, long-term, episodic/semantic, scratchpads — and the discipline of what NOT to remember.

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What you'll learn

Short-term: the context window
Long-term memory
Episodic vs semantic
Scratchpads & working files

Remember this

Short-term memory is the context window — finite, volatile, managed like RAM; degradation is silent
Long-term memory = curated store + deliberate retrieval, with provenance and freshness discipline; semantic facts (deduped, versioned) differ from episodic events (summarizing with age)
Scratchpads extend working memory via files — the pattern behind resumable, multi-session agent tasks

Short-term = context window

Finite, volatile; degradation is silent (early instructions fall out).
Metaphor: context is RAM — manage as a working set.

Long-term memory

Write gates (reflection points, conclusions not transcripts) · store with provenance (when/source/confidence) · retrieve deliberately.
Freshness discipline like RAG: updates, evictions, conflict detection.

Episodic vs semantic

Semantic: context-free facts · dedupe + version · recall by meaning.
Episodic: context-rich events · timestamped/tagged · recall by situation · compress with age.

Scratchpads

Working files extend memory; notes = resumability; context carries the pointer, the file carries the state.

Code: Write gates: what enters memory, when

# Gate 1 · REFLECTION POINT (end of meaningful work)
→ extract semantic facts only: preferences, project truths, decisions
→ skip: time-sensitive details, one-off context, anything PII-tagged

# Gate 2 · TASK END
→ summarize episode: goal → approach → outcome → one lesson
→ tag: task_type, date, outcome (success/failure/abandoned)

# Gate 3 · NEVER (memory safety, AG-13)
→ raw secrets, API keys, credentials
→ PII about people without consent basis
→ unverified claims marked as facts (store as 'unverified' or drop)

# Gate 4 · EVICTION (scheduled)
→ semantic: superseded facts replaced (keep old version 30d)
→ episodic: raw → summary after 30d; lessons survive