format: a log can be made quiet, or full of errors

[donislawdev]

Adds level_mix to the log format: realistic, quiet, errors, debug. It decides which severities appear, the way status_mix already decides which response codes do.

tfg generate --format log --size 64kb --set entry_format=plain --set level_mix=quiet

No existing file changes by a byte. The default is realistic, which is the mix these logs have always carried, moved rather than rewritten so the same seed draws the same levels. Checked against a binary built from main: six shapes by three seeds, eighteen of eighteen identical.

The part that is not obvious from the declaration

The chosen set moves the minimum. The shortest entry a shape can write has to leave room for the longest severity it might draw, and quiet draws only INFO, a shorter word than ERROR.

shape	realistic	quiet
plain	41 B	40 B
json-lines	83 B	82 B

An arithmetic reading the whole vocabulary instead of the set in force would be wrong in the safe direction - a floor the format can beat, announced as if it could not. Neither the size guard nor the determinism guard would ever see that. So longestLevel takes the options, and the guard asks for the announced minimum and for one byte below it rather than repeating the arithmetic itself.

Refusals

Only plain and json-lines carry a severity. Asking for a mix beside one of the other four is refused by a message naming both settings, rather than accepted in silence. The refusal fires on a real choice and not on the key arriving, because a window sends every setting it draws and a value equal to the default was never stated.

What was checked

• D11 against a main binary: 18 of 18 byte for byte
• exact size: 36 runs for each of the eight shape and mix pairs
• the announced minimum is accepted and one byte below it is refused, 8 of 8
• refusal on the four shapes without a severity, each naming both settings
• every shape still reachable with every setting sent at its default
• a value outside the closed set exits 4
• 26 affected guards green, three of which ask the window itself
• four new mutations, all caught
• end to end through a recipe, not only through flags

New guard: TestTheLogSeverityMixIsDrawnAndSetsTheMinimum.

This closes the log format. The two settings still listed as missing have recorded reasons rather than no time behind them: an entry count disagrees with the exact size contract, and a start and end pair cannot work when the run does not know the entry count in advance.

🤖 Generated with Claude Code