refactor: reorganize error handling and request parsing in API utilities

src/api/machines.ts

···
-import { type Context, Hono } from "hono";
-import { Data, Effect, pipe } from "effect";
-import { parseParams, parseQueryParams, presentation } from "./utils.ts";
+import { Hono } from "hono";
+import { Effect, pipe } from "effect";
+import {
+  handleError,
+  parseParams,
+  parseQueryParams,
+  parseStartRequest,
+  presentation,
+} from "./utils.ts";
 import { getInstanceState } from "../mod.ts";
 import { listInstances } from "../state.ts";
-import {
-  type CommandError,
-  findVm,
-  killProcess,
-  StopCommandError,
-  updateToStopped,
-  VmNotFoundError,
-} from "../subcommands/stop.ts";
+import { findVm, killProcess, updateToStopped } from "../subcommands/stop.ts";
 import {
   buildQemuArgs,
   createLogsDir,
   setupFirmware,
   startDetachedQemu,
 } from "../subcommands/start.ts";
-import { MachineParamsSchema } from "../types.ts";
-
-class ParseRequestError extends Data.TaggedError("ParseRequestError")<{
-  cause?: unknown;
-  message: string;
-}> {}
-
-export const handleError = (
-  error:
-    | VmNotFoundError
-    | StopCommandError
-    | CommandError
-    | ParseRequestError
-    | Error,
-  c: Context,
-) =>
-  Effect.sync(() => {
-    if (error instanceof VmNotFoundError) {
-      return c.json(
-        { message: "VM not found", code: "VM_NOT_FOUND" },
-        404,
-      );
-    }
-    if (error instanceof StopCommandError) {
-      return c.json(
-        {
-          message: error.message ||
-            `Failed to stop VM ${error.vmName}`,
-          code: "STOP_COMMAND_ERROR",
-        },
-        500,
-      );
-    }
-
-    if (error instanceof ParseRequestError) {
-      return c.json(
-        {
-          message: error.message || "Failed to parse request body",
-          code: "PARSE_BODY_ERROR",
-        },
-        400,
-      );
-    }
-
-    return c.json(
-      { message: error instanceof Error ? error.message : String(error) },
-      500,
-    );
-  });
-
-const parseStartRequest = (c: Context) =>
-  Effect.tryPromise({
-    try: async () => {
-      const body = await c.req.json();
-      return MachineParamsSchema.parse(body);
-    },
-    catch: (error) =>
-      new ParseRequestError({
-        cause: error,
-        message: error instanceof Error ? error.message : String(error),
-      }),
-  });
 
 const app = new Hono();
 

src/api/utils.ts

···
-import { Effect } from "effect";
+import { Data, Effect } from "effect";
 import type { Context } from "hono";
+import {
+  type CommandError,
+  StopCommandError,
+  VmNotFoundError,
+} from "../subcommands/stop.ts";
+import { MachineParamsSchema } from "../types.ts";
 
 export const parseQueryParams = (c: Context) => Effect.succeed(c.req.query());
 
···
 
 export const presentation = (c: Context) =>
   Effect.flatMap((data) => Effect.succeed(c.json(data)));
+
+export class ParseRequestError extends Data.TaggedError("ParseRequestError")<{
+  cause?: unknown;
+  message: string;
+}> {}
+
+export const handleError = (
+  error:
+    | VmNotFoundError
+    | StopCommandError
+    | CommandError
+    | ParseRequestError
+    | Error,
+  c: Context,
+) =>
+  Effect.sync(() => {
+    if (error instanceof VmNotFoundError) {
+      return c.json(
+        { message: "VM not found", code: "VM_NOT_FOUND" },
+        404,
+      );
+    }
+    if (error instanceof StopCommandError) {
+      return c.json(
+        {
+          message: error.message ||
+            `Failed to stop VM ${error.vmName}`,
+          code: "STOP_COMMAND_ERROR",
+        },
+        500,
+      );
+    }
+
+    if (error instanceof ParseRequestError) {
+      return c.json(
+        {
+          message: error.message || "Failed to parse request body",
+          code: "PARSE_BODY_ERROR",
+        },
+        400,
+      );
+    }
+
+    return c.json(
+      { message: error instanceof Error ? error.message : String(error) },
+      500,
+    );
+  });
+
+export const parseStartRequest = (c: Context) =>
+  Effect.tryPromise({
+    try: async () => {
+      const body = await c.req.json();
+      return MachineParamsSchema.parse(body);
+    },
+    catch: (error) =>
+      new ParseRequestError({
+        cause: error,
+        message: error instanceof Error ? error.message : String(error),
+      }),
+  });