Agent generic should use result type, not Zod schema type

[dremnik]

Problem

When defining an agent with structured output, you currently have to use typeof Schema as the generic parameter:

const TriageSchema = z.object({
  needs_updating: z.boolean(),
  reason: z.string(),
});

type TriageResult = z.infer<typeof TriageSchema>;

// Awkward - have to use typeof Schema
export const triager = new Agent<RepoContext, typeof TriageSchema>({
  output: TriageSchema,
});

This is unintuitive because the generic should represent what you get back, not the Zod machinery.

Desired API

// Clean - generic is the result type
export const triager = new Agent<RepoContext, TriageResult>({
  output: TriageSchema,
});

Proposed Solution

1. Change AgentOutputType to represent result types instead of schema types:

// Before
export type AgentOutputType = TextOutput | ZodType;

// After  
export type AgentResultType = string | Record<string, any>;

2. Update config to accept ZodType<TResult> for the output property:

interface AgentConfig<TContext, TResult = string> {
  output?: ZodType<TResult>;
}

3. Simplify ResolvedAgentResponse to be identity:

// Before
export type ResolvedAgentResponse<TOutput extends AgentOutputType> =
  TOutput extends TextOutput ? string : TOutput extends ZodType ? z.infer<TOutput> : never;

// After
export type ResolvedAgentResponse<TResult> = TResult;

Files to Update

• packages/kernl/src/agent/types.ts
• packages/kernl/src/guardrail.ts
• packages/kernl/src/agent.ts
• packages/kernl/src/agent/base.ts
• packages/kernl/src/thread/thread.ts
• packages/kernl/src/thread/types.ts
• packages/kernl/src/thread/utils.ts
• packages/kernl/src/kernl/kernl.ts
• packages/kernl/src/lib/error.ts
• packages/kernl/src/api/resources/agents/agents.ts