Should this fact be an instruction, working state, durable memory, or fetched evidence?

Shared teaching scenario · fictional product data

Research three laptops under €900, verify current evidence, and write laptop-comparison.md. Do not purchase anything or contact a vendor.

01 · Smallest useful mechanism

Instructions, working state, durable memory, and external truth have different jobs.

Instructions define intended behavior. Turn state records the current run. Durable memory stores reusable learned facts with provenance and expiry. External systems remain authoritative for changing facts such as current prices. Treating these stores as interchangeable produces stale decisions and hidden policy.

Place information according to authority, lifetime, sensitivity, and update path—not according to whichever storage mechanism is convenient.

02 · Experiment

Test the prediction

Deterministic browser simulation

The place knowledge deliberately experiment uses inspectable, repeatable teaching data. It does not claim to be a live agent trajectory.

Required team rules belong in explicit project instructions. Memory can improve continuity, but it should not become an invisible policy engine or a secret store.

Choose information

Placement problem

Never purchase a laptop or contact a vendor during this research task.

A required task rule that must be visible throughout the run.

Place this information

Ask whether it is temporary, mandatory, reusable, exact, personal, or sensitive.

CODEX

AGENTS.md carries repository guidance; local memories carry learned context; skills load reusable workflows.

CLAUDE CODE

CLAUDE.md carries hierarchical instructions; auto memory stores project-local learned context.

Research basis: Codex customization, Codex memories, and Claude Code memory.

Loading the experiment…

03 · Production-minded practice

Prove the mechanism under failure

Use your own stack or a contained mock environment. Do not point failure drills at real accounts, people, or irreversible services.

Build
Create a placement table for the task contract, current plan, product evidence, user preferences, credentials, and report artifact.
Break it on purpose
Resume from a summary with an expired price and a preference the user has deleted.
Evidence of completion
The run refreshes the price, proves the deletion no longer affects context, keeps secrets outside model input, and identifies the canonical store for every surviving fact.

Your learning artifact

Write the argument you would defend

Stored only in this browser. No account required; course reset does not delete it.

Your response

04 · Check your understanding

Where should a current product price be treated as authoritative?

Optional referenceDeep dive / reference chapterOpen the complete essay, diagrams, mathematics, exercises, glossary, and sources when you want more depth.on demand

Next: Knowing where state belongs is not enforcement. We now add deterministic checks at named lifecycle events.