The listing monitor

log facebook watch checks an account's Marketplace listings on a schedule and decides what should happen to each one. It only decides: it never posts, reposts or deletes anything. Read this if you want to know how it reacts to removed listings, errors and limits.

How it moves between states

The monitor is an XState v5 machine in src/marketplace/monitor/machine.ts:

checking --ok-----------> evaluating --> waiting --after poll--> checking
   |                          '-- checks done --> done
   |--rateLimited--> resting --after 24h--> checking
   |--other account issue--> blocked
   '--error--> failed --first try--> retrying --after 5s--> checking
                 |-- same error 3x in a row --> tripped
                 '-- otherwise --> waiting

In words:

• Checking reads the listings. If that works, it evaluates them, then waits for the next poll.
• If the account is rate-limited, it rests for 24 hours.
• Any other account issue (ban, checkpoint, login) blocks it.
• An error is retried once after 5 seconds. The same error three times in a row trips it and it stops.

Watching it

log facebook watch prints each event and state as it happens (through XState's inspect API, src/observability/trace).

• --json streams them as NDJSON, one line per step, with the result on the last line.
• --checks 0 runs until you press Ctrl+C.

Where its behaviour comes from

The monitor reuses decisions proven in two earlier Marketplace tools: