feat(agent): unify models and validate OpenCode providers

Generate chat, task and learning models from agent-models.json.
Use WaterNetwork fast/expert models with 272k context and validate
upstream names before readiness. Add an isolated model check command
with signal-safe cleanup and plugin, Skill and MCP management docs.

Verified in isolation: type checks, 26 focused tests and both model
catalog checks; no model inference requests.

src/runtime/model-check.ts

@@ -0,0 +1,35 @@
+import { z } from "zod";
+import { type AgentModelConfig } from "../chat/modelConfig.js";
+
+export const modelCheckInputSchema = z.object({ models: z.array(z.object({
+  id: z.string(), provider_id: z.string(), model_id: z.string(), wire_id: z.string(), requires_tools: z.boolean(),
+}).strict()).min(1).max(1000) }).strict();
+export type ModelCheckInput = z.infer<typeof modelCheckInputSchema>;
+export const modelCheckReportSchema = z.object({
+  models: z.array(z.object({
+    id: z.string(), model_id: z.string(),
+    status: z.enum(["valid", "not_registered", "not_enabled", "no_tools", "wire_id_mismatch", "not_advertised", "unchecked"]),
+  }).strict()),
+  providers: z.array(z.object({
+    id: z.string(), status: z.enum(["checked", "not_registered", "unsupported_catalog", "catalog_unavailable", "catalog_invalid", "credentials_unavailable"]),
+    http_status: z.number().int().optional(),
+  }).strict()),
+}).strict();
+export type ModelCheckReport = z.infer<typeof modelCheckReportSchema>;
+
+export function modelCheckTargets(configuration: AgentModelConfig): ModelCheckInput {
+  return { models: Object.entries(configuration.providers).flatMap(([providerID, provider]) =>
+    Object.entries(provider.models).filter(([, model]) => !model.disabled).map(([modelID, model]) => ({
+      id: `${providerID}/${modelID}`, provider_id: providerID, model_id: modelID,
+      wire_id: model.model_id ?? modelID, requires_tools: model.capabilities.tools,
+    })),
+  ) };
+}
+
+export function assertModelCheckPassed(report: ModelCheckReport) {
+  const failures = [
+    ...report.providers.filter((provider) => provider.status !== "checked").map((provider) => `${provider.id}: ${provider.status}${provider.http_status ? ` (HTTP ${provider.http_status})` : ""}`),
+    ...report.models.filter((model) => model.status !== "valid").map((model) => `${model.id}: ${model.status}`),
+  ];
+  if (!report.models.length || failures.length) throw new Error(`OpenCode model validation failed: ${failures.join("; ") || "empty model catalog"}`);
+}