Filter levels and modes

Two settings shape filtering. --filter decides whether Fonn acts, only records, or stays off. --filter-level decides how far it goes.

Levels

Level	Reduces	Use it when
`strict`	Format adapters only	You want the narrowest change to what the model reads
`standard` (default)	Adapters, plus identical lines from any command	Most work. Nothing is lost except exact copies, and they are counted
`similar`	Also lines that differ only in numbers or IDs, keeping the first and last	Logs repeat a line with a changing counter, worker number or request ID, and those numbers do not matter

fonn --default-filter-level similar   # save a default level
fonn --default-filter-level           # show it
fonn --filter-level strict            # override it for one launch
fonn run "Explain the failing job" --filter-level similar

At the similar level, a changed word such as healthy becoming unhealthy breaks the run, so that line stays. Lines that mention errors, failures or warnings are never merged. fonn resume restores the level a session used. For the standalone filter, add --level similar or --level strict to the hook command.

Modes

Mode	What the model gets	What Fonn records
`filter` (default)	The shortened output plus a recovery footer	The original, the decision and the character counts
`observe`	The full original output, untouched	The original and what it would have removed
`off`	The full original output	Nothing. No hook runs

observe is a dry run. Use it to try Fonn on your own projects before trusting it to change what the model sees, or to compare levels on your logs. Each observed reduction is saved in the launch’s state folder under ~/.local/state/fonn/native/<launch-id>/, where filters/ holds each decision.