IS-1 A gated budget on the every-turn file

Where a project has an every-turn file, it MUST carry a size budget that a gate enforces.

Field	Value
Keyword	MUST
Level	1
Checked	by judgement
Findings	F1, F2
Harness facts	H1, H2
Threat	internal: the prose budget failing is seen in one case, and the gate was never seen refusing
Status	active

Rationale: the every-turn file is where a finished task's reasoning is cheapest to write down, so it grows, and it is paid on every turn together with everything it imports (H1, H2). In Shio a budget stated in the file itself did not stop it reaching 185,734 bytes; in roadkeep a budget held by the gate brought the file to its ceiling and turned the next addition into a decision to compress or move content (F1, R3/S3). After the move roadkeep lowered the budget rather than leave the room free (F2). The budget counts bytes as well as lines where it can, since roadkeep records that a line budget alone is met by writing longer lines (F1). The size of the budget is not fixed here; see the open questions.