fix(mcp): share one constSchema and prove ownership both ways

constSchema was hand-copied into src/commands/system/index.ts, drifting
from the identical private helper in command-output-schemas.ts. Export
it once from command-input.ts, next to the other schema-primitive
builders, and import it at both sites.

The ownership test for the projected family map only checked that each
of the module's own entries names the module as owner; it did not check
the inverse, so a system-family command the registry attributes to this
module but missing from SYSTEM_COMMAND_OUTPUT_SCHEMAS would still pass.
Compare the two sets directly.

Author: thymikee

src/commands/command-input.ts

@@ -106,6 +106,11 @@ export function enumSchema(values: readonly string[], description?: string): Jso
   return { type: 'string', enum: values, ...(description ? { description } : {}) };
 }
 
+/** A single-valued string schema, for a discriminant field an output shape always fixes. */
+export function constSchema(value: string): JsonSchema {
+  return { type: 'string', const: value };
+}
+
 export function stringSchema(description?: string): JsonSchema {
   return { type: 'string', ...(description ? { description } : {}) };
 }

src/commands/system/index.ts

@@ -3,6 +3,7 @@ import type { CommandResultMap } from '@agent-device/command-registry/command-re
 import type { ClipboardCommandOptions } from '@agent-device/contracts/client';
 import {
   type FoldKeyframe,
+  FOLD_SCREEN_COORDINATE_SPACE,
   MAX_FOLD_DURATION_MS,
   MAX_FOLD_KEYFRAMES,
   parseFoldInput,
@@ -12,7 +13,6 @@ import {
   FOLD_POSE_USAGE,
   parseDeviceRotation,
 } from '@agent-device/contracts/device';
-import { FOLD_SCREEN_COORDINATE_SPACE } from '@agent-device/contracts/fold-runtime';
 import { type BackMode, BACK_MODES } from '@agent-device/contracts/back-mode';
 import {
   TV_REMOTE_BUTTONS,
@@ -41,6 +41,7 @@ import {
   jsonSchemaField,
   readFieldInput,
   booleanSchema,
+  constSchema,
   enumSchema,
   numberSchema,
   objectSchema,
@@ -74,10 +75,6 @@ const TV_REMOTE_LONGPRESS_PRESET_MS = 500;
 const CLIPBOARD_ACTION_VALUES = ['read', 'write'] as const;
 const KEYBOARD_METADATA_ACTION_VALUES = ['status', 'dismiss', 'enter', 'return'] as const;
 
-function constSchema(value: string): JsonSchema {
-  return { type: 'string', const: value };
-}
-
 /**
  * This family's advertised MCP `outputSchema`s, keyed by daemon command name and projected into
  * the command map by `src/mcp/command-output-schemas.ts`. Non-strict like every other entry: no

src/mcp/__tests__/command-tools-system-schemas.test.ts

@@ -1,6 +1,9 @@
 import assert from 'node:assert/strict';
 import { test } from 'vitest';
-import { ownerFilesForCommand } from '@agent-device/command-registry/owner-files';
+import {
+  COMMAND_OWNER_FILES,
+  ownerFilesForCommand,
+} from '@agent-device/command-registry/owner-files';
 import { commandSupportsSettleObservation } from '@agent-device/command-registry/registry';
 import { SYSTEM_COMMAND_OUTPUT_SCHEMAS } from '../../commands/system/index.ts';
 import { COMMAND_OUTPUT_SCHEMAS } from '../command-output-schemas.ts';
@@ -39,13 +42,25 @@ test('a settle-derived system entry still grafts onto the module object, not a f
   );
 });
 
-test('the projected family map declares exactly the commands its module owns', () => {
+test('every system-owned command claims this module, and the module claims nothing else', () => {
   for (const command of SYSTEM_COMMANDS) {
     assert.ok(
       ownerFilesForCommand(command).includes('src/commands/system/index.ts'),
       `${command} projects its output schema from this module but does not name it as its owner`,
     );
   }
+
+  const commandsOwnedByThisModule = (
+    Object.entries(COMMAND_OWNER_FILES) as Array<[string, readonly string[]]>
+  )
+    .filter(([, ownerFiles]) => ownerFiles.includes('src/commands/system/index.ts'))
+    .map(([command]) => command)
+    .sort();
+  assert.deepEqual(
+    commandsOwnedByThisModule,
+    [...SYSTEM_COMMANDS].sort(),
+    'a command the registry attributes to this module is missing from SYSTEM_COMMAND_OUTPUT_SCHEMAS (or vice versa)',
+  );
 });
 
 // `appstate` on iOS answers from the session record, and from a live runner when one can read the

src/mcp/command-output-schemas.ts

@@ -3,6 +3,7 @@ import type { CommandResultMap } from '@agent-device/command-registry/command-re
 import { commandSupportsSettleObservation } from '@agent-device/command-registry/registry';
 import {
   booleanSchema,
+  constSchema,
   enumSchema,
   looseObjectSchema,
   numberSchema,
@@ -47,10 +48,6 @@ import { DEVICE_TARGETS, PUBLIC_PLATFORMS } from '@agent-device/kernel/device';
 
 export const DEVICE_KINDS = ['simulator', 'emulator', 'device'] as const;
 
-function constSchema(value: string): JsonSchema {
-  return { type: 'string', const: value };
-}
-
 function nullableStringSchema(description?: string): JsonSchema {
   return { type: ['string', 'null'], ...(description ? { description } : {}) };
 }