zUsageUpdate schema rejects null for 'used' field

[kagura-agent]

Problem

zUsageUpdate in schema/zod.gen.js defines:

export const zUsageUpdate = z.object({
    _meta: z.record(z.string(), z.unknown()).nullish(),
    cost: zCost.nullish(),
    size: z.number(),
    used: z.number(),  // <-- does not accept null
});

But @zed-industries/claude-agent-acp@0.21.0 sends used: null in session/update notifications (e.g. at the start of a session before any tokens are used).

This causes the client-side notification handler to throw:

Error handling notification {
  method: 'session/update',
  params: { update: { sessionUpdate: 'usage_update', used: null, size: 200000, cost: {...} } }
} { code: -32602, message: 'Invalid params', data: { _errors: ['Invalid input: expected object, received undefined', ...] } }

Suggested Fix

Change used to accept null/undefined, consistent with other optional fields:

- used: z.number(),
+ used: z.number().nullish(),

Environment

• @agentclientprotocol/sdk@0.15.0
• @zed-industries/claude-agent-acp@0.21.0
• acpx@0.1.16