What

Pure extract-and-delegate refactor of lib/Mcp/OpenBuiltToolProvider.php. No behavior change — every branch, return shape, exception, MCP tool name/schema, and side effect is preserved identically.

Why

OpenBuiltToolProvider was 1165 lines with PHPMD violations:

What was extracted

9 new files under lib/Mcp/Handler/:

• AbstractToolHandler — shared base: errorResult, requireAuthenticatedUser, isValidSlug, buildDeepLink, sourceDescriptor, toArray, extractUuid, loadVersion, saveVersionManifest
• ListAppsHandler — openbuilt.listApps
• GetAppManifestHandler — openbuilt.getAppManifest
• CreateAppHandler — openbuilt.createApp
• PromoteVersionHandler — openbuilt.promoteVersion
• UpsertSchemaHandler — openbuilt.upsertSchema (also extracts validateSlugsAndTitle + normaliseSchemaBody + findExistingSchema + attachSchemaToRegister)
• UpsertPageHandler — openbuilt.upsertPage (extracts upsertPageInList)
• AddWidgetHandler — openbuilt.addWidget (extracts findPageIndex + appendWidget)
• UpsertMenuItemHandler — openbuilt.upsertMenuItem (extracts upsertMenuItemInList)

OpenBuiltToolProvider is now a thin dispatcher: constants → TOOL_DESCRIPTORS → invokeTool (string-map lookup) → makeHandler factory → handler .handle($args). The isAdmin public method stays in the provider (sole user of IGroupManager).

Verification

• php -l — no syntax errors on all 10 files
• vendor/bin/phpmd lib/Mcp text design,codesize — exit 0, 0 violations
• vendor/bin/phpstan analyse lib --no-progress — exit 0, no errors
• vendor/bin/phpcs --standard=phpcs.xml lib/Mcp — 0 errors (pre-existing @spec warnings only, identical to original)
• vendor/bin/phpunit tests/Unit — 192 tests, 111 pre-existing errors (all OCA\OpenRegister\Service\ObjectService not exist — same count before and after; no NC environment)

What remains inline / why

Nothing handler-logic lives in the provider. The @spec warning on public methods is pre-existing on the original file and requires a project-level spec ticket — out of scope for a complexity refactor.