Lab 10 — Context and compaction

Start from: app/ at tag lab09-done, with the Lab 0 setup loaded (see Working in app/).

Goal: fill the context with a long investigation, compact it, and check which facts survive. make_log.py writes a 6,000-line synthetic app.log with a few important facts buried in noise.

1. Generate the incident log

python ..\lab10-compaction\make_log.py

app.log is ignored by the app’s *.log rule. Don’t open it yet.

2. Investigate

claude

Last night checkout failures spiked. Investigate app.log: find the root cause, the deploy involved, the affected order IDs and region, and when it was fixed. Read the whole log and show your evidence.

Then:

/context

Observe: how much of the window the log and tool results take.

3. Compact with instructions

/compact Keep: root cause, config key and values, deploy id, affected order IDs and region, rollback time, and the fix plan. Drop raw log lines.

Then ask, without letting it re-read the log:

Without reading any files, answer: what config changed, from what to what, in which deploy, which orders failed, in which region, and when was it rolled back?

Check against the answer key: payment.timeout_ms changed from 5000 to 500 in deploy 7f3a2c; orders ORD-2047, ORD-2113, ORD-2190 timed out in eu-west; then a rollback followed. The “out of stock sku=P3” lines are noise, not the cause.

4. Compare with an unguided compact

Start a new session, repeat step 2, then use plain /compact (no instructions) and ask the same question. Optionally try /clear to see what losing everything looks like.

Record

Note any hallucinated “facts” after compaction.

Checkpoint

Nothing to commit (the log is ignored):

git tag lab10-done