Adding a Mechanic

The procedure, in the order that avoids rework.

1 · Write the mechanic. GM Brain/Mechanics/. Deep reference, as long as it needs to be. Nothing will read it whole and that is fine.

2 · Write the card. GM Brain/Cards/, target ~600 tokens. Thresholds, the procedure in order, the exact schema fields to write. Close with a Deep: footer naming the mechanic.

3 · Declare the state. Whatever the mechanic tracks needs somewhere to live. A declared schema field if it is durable and typed; moduleState if it is free-form. A field written at the top level that the schema does not declare is silently discarded — no error, and it is gone by next session.

4 · Wire the route in. Named by the Ladder, named by a card that already loads, or fired by a trigger. Pick one and confirm it. This is the step that gets skipped.

5 · Wire the route out. Decide what routinely reads the state you just created. A field nothing consults is dead weight the GM pays for on every write.

6 · Give it an audit hook. Fold one line into an existing Card - Self Audit check rather than adding a sixteenth check. Mechanics without an audit hook rot quietly.

Constraints worth knowing before you start

TRIGGER BODIES   500 characters. Tools as well as narrative triggers.
                 A 503-character body once rejected an entire push.
NARRATIVE SLOTS  20 total, and they are full. Adding one means
                 arguing for what it replaces.
ENUM VALUES      must match the schema exactly. A card telling the GM
                 to write `Standard` into an enum of `standard` is
                 rejected and the data is gone, with no error anywhere.

Reuse before you add. Most "new mechanics" are a paragraph in an existing card and a field that already exists.