feat: optimize Zabbix queries and enhance specialized device support

- Implement query optimization (reduced output, parameter skipping) to minimize Zabbix API traffic.

- Add indirect dependency handling: deviceType implies tags and state implies items.

- Move schema extensions to samples/extensions/ to clarify their role as samples.

- Enhance DistanceTrackerDevice with String time fields to support optional date portions.

- Ensure allDevices strictly filters by deviceType and populates the field in results.

- Refactor runAllRegressionTests mutation to use internal unique names and improve stability.

- Fix unnecessary Zabbix API calls for item preprocessing during template and host imports.

- Update documentation including cookbook recipes, test specifications, and optimization guides.

- Add extensive unit, integration, and regression tests covering all implemented changes.

- Update docker-compose.yml to mount the samples/ directory as a volume.

- Update IntelliJ .idea run configurations to reflect the new sample extension paths.

.idea/runConfigurations/index_ts.xml

@@ -2,7 +2,7 @@
   <configuration default="false" name="index.ts" type="NodeJSConfigurationType" path-to-node="wsl://Ubuntu@/home/ahilbig/.nvm/versions/node/v24.12.0/bin/node" nameIsGenerated="true" path-to-js-file="src/index.ts" node-parameters="--import tsx" working-dir="$PROJECT_DIR$">
     <envs>
       <env name="ADDITIONAL_RESOLVERS" value="SinglePanelDevice,FourPanelDevice,DistanceTrackerDevice" />
-      <env name="ADDITIONAL_SCHEMAS" value="./schema/extensions/display_devices.graphql,./schema/extensions/location_tracker_devices.graphql,./schema/extensions/location_tracker_commons.graphql" />
+      <env name="ADDITIONAL_SCHEMAS" value="./samples/extensions/display_devices.graphql,./samples/extensions/location_tracker_devices.graphql,./samples/extensions/location_tracker_commons.graphql" />
       <env name="DEBUG" value="device-control-center-api:*" />
       <env name="ZABBIX_PRIVILEGE_ESCALATION_TOKEN" value="$ZABBIX_AUTH_TOKEN_VCR_DEV$" />
       <env name="ZABBIX_BASE_URL" value="http://cockpit.vcr.develop.hilbigit.com/" />

.idea/workspace.xml

@@ -5,18 +5,34 @@
   </component>
   <component name="ChangeListManager">
     <list default="true" id="d7a71994-2699-4ae4-9fd2-ee13b7f33d35" name="Changes" comment="docs: refactor documentation and upgrade to Node.js 24&#10;&#10;This commit upgrades the project to Node.js 24 (LTS) and performs a major refactoring of the documentation to support both advanced users and AI-based automation (MCP).&#10;&#10;Changes:&#10;- Environment &amp; CI/CD:&#10;  - Set Node.js version to &gt;=24 in package.json and .nvmrc.&#10;  - Updated Dockerfile to use Node 24 base image.&#10;  - Updated @types/node to ^24.10.9.&#10;- Documentation:&#10;  - Refactored README.md with comprehensive technical reference, configuration details, and Zabbix-to-GraphQL mapping.&#10;  - Created docs/howtos/cookbook.md with practical recipes for common tasks and AI test generation.&#10;  - Updated docs/howtos/mcp.md to emphasize GraphQL's advantages for AI agents and Model Context Protocol.&#10;  - Added readme.improvement.plan.md to track documentation evolution.&#10;  - Enhanced all how-to guides with improved cross-references and up-to-date information.&#10;- Guidelines:&#10;  - Updated .junie/guidelines.md with Node 24 requirements and enhanced commit message standards (Conventional Commits 1.0.0).&#10;- Infrastructure &amp; Code:&#10;  - Updated docker-compose.yml with Apollo MCP server integration.&#10;  - Refined configuration and schema handling in src/api/ and src/datasources/.&#10;  - Synchronized generated TypeScript types with schema updates.">
+      <change afterPath="$PROJECT_DIR$/docs/queries/sample_distance_tracker_test_query.graphql" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/src/test/schema_dependent_queries.test.ts" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/.idea/runConfigurations/index_ts.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/runConfigurations/index_ts.xml" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/.idea/workspace.xml" beforeDir="false" afterPath="$PROJECT_DIR$/.idea/workspace.xml" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/README.md" beforeDir="false" afterPath="$PROJECT_DIR$/README.md" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/docker-compose.yml" beforeDir="false" afterPath="$PROJECT_DIR$/docker-compose.yml" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/docs/howtos/cookbook.md" beforeDir="false" afterPath="$PROJECT_DIR$/docs/howtos/cookbook.md" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/docs/queries/sample_import_weather_sensor_template.graphql" beforeDir="false" afterPath="$PROJECT_DIR$/docs/queries/sample_import_weather_sensor_template.graphql" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/docs/howtos/query_optimization.md" beforeDir="false" afterPath="$PROJECT_DIR$/docs/howtos/query_optimization.md" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/docs/howtos/schema.md" beforeDir="false" afterPath="$PROJECT_DIR$/docs/howtos/schema.md" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/docs/queries/README.md" beforeDir="false" afterPath="$PROJECT_DIR$/docs/queries/README.md" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/docs/tests.md" beforeDir="false" afterPath="$PROJECT_DIR$/docs/tests.md" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/mcp/operations/runAllRegressionTests.graphql" beforeDir="false" afterPath="$PROJECT_DIR$/mcp/operations/runAllRegressionTests.graphql" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/schema/extensions/display_devices.graphql" beforeDir="false" afterPath="$PROJECT_DIR$/samples/extensions/display_devices.graphql" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/schema/extensions/ground_value_checker.graphql" beforeDir="false" afterPath="$PROJECT_DIR$/samples/extensions/ground_value_checker.graphql" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/schema/extensions/location_tracker_commons.graphql" beforeDir="false" afterPath="$PROJECT_DIR$/samples/extensions/location_tracker_commons.graphql" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/schema/extensions/location_tracker_devices.graphql" beforeDir="false" afterPath="$PROJECT_DIR$/samples/extensions/location_tracker_devices.graphql" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/schema/extensions/weather_sensor.graphql" beforeDir="false" afterPath="$PROJECT_DIR$/samples/extensions/weather_sensor.graphql" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/schema/mutations.graphql" beforeDir="false" afterPath="$PROJECT_DIR$/schema/mutations.graphql" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/api/resolvers.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/api/resolvers.ts" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/datasources/graphql-params-to-zabbix-output.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/datasources/graphql-params-to-zabbix-output.ts" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/src/datasources/zabbix-hosts.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/datasources/zabbix-hosts.ts" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/datasources/zabbix-templates.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/datasources/zabbix-templates.ts" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/src/execution/host_importer.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/execution/host_importer.ts" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/src/execution/regression_test_executor.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/execution/regression_test_executor.ts" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/src/execution/template_importer.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/execution/template_importer.ts" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/src/model/model_enum_values.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/model/model_enum_values.ts" afterDir="false" />
       <change beforePath="$PROJECT_DIR$/src/schema/generated/graphql.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/schema/generated/graphql.ts" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/src/test/host_importer.test.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/test/host_importer.test.ts" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/test/host_query.test.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/test/host_query.test.ts" afterDir="false" />
-      <change beforePath="$PROJECT_DIR$/src/test/template_importer.test.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/test/template_importer.test.ts" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/src/test/query_optimization.test.ts" beforeDir="false" afterPath="$PROJECT_DIR$/src/test/query_optimization.test.ts" afterDir="false" />
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     <option name="SHOW_DIALOG" value="false" />
     <option name="HIGHLIGHT_CONFLICTS" value="true" />
@@ -27,13 +43,13 @@
     <execution />
   </component>
   <component name="EmbeddingIndexingInfo">
-    <option name="cachedIndexableFilesCount" value="149" />
+    <option name="cachedIndexableFilesCount" value="163" />
     <option name="fileBasedEmbeddingIndicesEnabled" value="true" />
   </component>
   <component name="Git.Settings">
     <option name="RECENT_BRANCH_BY_REPOSITORY">
       <map>
-        <entry key="$PROJECT_DIR$" value="license" />
+        <entry key="$PROJECT_DIR$" value="vlsv" />
       </map>
     </option>
     <option name="RECENT_GIT_ROOT_PATH" value="$PROJECT_DIR$" />
@@ -95,7 +111,7 @@
     "go.import.settings.migrated": "true",
     "javascript.preferred.runtime.type.id": "node",
     "junie.onboarding.icon.badge.shown": "true",
-    "last_opened_file_path": "//wsl.localhost/Ubuntu/home/ahilbig/git/vcr/zabbix-graphql-api/src",
+    "last_opened_file_path": "//wsl.localhost/Ubuntu/home/ahilbig/git/vcr/zabbix-graphql-api/docs",
     "node.js.detected.package.eslint": "true",
     "node.js.detected.package.tslint": "true",
     "node.js.selected.package.eslint": "(autodetect)",
@@ -107,8 +123,8 @@
     "npm.copy-schema.executor": "Run",
     "npm.prod.executor": "Run",
     "npm.test.executor": "Run",
-    "settings.editor.selected.configurable": "ml.llm.mcp",
+    "settings.editor.selected.configurable": "junie.mcp",
-    "settings.editor.splitter.proportion": "0.28812414",
+    "settings.editor.splitter.proportion": "0.23751687",
     "to.speed.mode.migration.done": "true",
     "ts.external.directory.path": "\\\\wsl.localhost\\Ubuntu\\home\\ahilbig\\git\\vcr\\zabbix-graphql-api\\node_modules\\typescript\\lib",
     "vue.rearranger.settings.migration": "true"
@@ -116,16 +132,16 @@
 }]]></component>
   <component name="RecapSpentCounter">
     <option name="endsOfQuotaMs" value="1772398800000" />
-    <option name="spentUsd" value="0.01011225" />
+    <option name="spentUsd" value="0.0915201" />
   </component>
   <component name="RecapUselessUpdatesCounter">
-    <option name="suspendCountdown" value="8" />
+    <option name="suspendCountdown" value="0" />
   </component>
   <component name="RecentsManager">
     <key name="CopyFile.RECENT_KEYS">
+      <recent name="\\wsl.localhost\Ubuntu\home\ahilbig\git\vcr\zabbix-graphql-api\docs" />
       <recent name="\\wsl.localhost\Ubuntu\home\ahilbig\git\vcr\zabbix-graphql-api\src" />
       <recent name="\\wsl.localhost\Ubuntu\home\ahilbig\git\vcr\zabbix-graphql-api\dist" />
-      <recent name="\\wsl.localhost\Ubuntu\home\ahilbig\git\vcr\zabbix-graphql-api\docs" />
       <recent name="\\wsl.localhost\Ubuntu\home\ahilbig\git\vcr\zabbix-graphql-api\src\testdata\templates" />
       <recent name="\\wsl.localhost\Ubuntu\home\ahilbig\git\vcr\zabbix-graphql-api\src\test" />
     </key>
@@ -153,7 +169,7 @@
       <node-interpreter value="project" />
       <envs>
         <env name="ADDITIONAL_RESOLVERS" value="SinglePanelDevice,FourPanelDevice,DistanceTrackerDevice" />
-        <env name="ADDITIONAL_SCHEMAS" value="./schema/extensions/display_devices.graphql,./schema/extensions/location_tracker_devices.graphql,./schema/extensions/location_tracker_commons.graphql" />
+        <env name="ADDITIONAL_SCHEMAS" value="./samples/extensions/display_devices.graphql,./samples/extensions/location_tracker_devices.graphql,./samples/extensions/location_tracker_commons.graphql" />
         <env name="DEBUG" value="device-control-center-api:*" />
         <env name="ZABBIX_PRIVILEGE_ESCALATION_TOKEN" value="$ZABBIX_AUTH_TOKEN_VCR_DEV$" />
         <env name="ZABBIX_BASE_URL" value="http://cockpit.vcr.develop.hilbigit.com/" />
@@ -185,11 +201,11 @@
     </list>
     <recent_temporary>
       <list>
+        <item itemvalue="npm.prod" />
+        <item itemvalue="npm.copy-schema" />
+        <item itemvalue="npm.test" />
         <item itemvalue="npm.test" />
         <item itemvalue="npm.prod" />
-        <item itemvalue="npm.copy-schema" />
-        <item itemvalue="npm.prod" />
-        <item itemvalue="npm.copy-schema" />
       </list>
     </recent_temporary>
   </component>
@@ -488,7 +504,7 @@
         </line-breakpoint>
         <line-breakpoint enabled="true" type="javascript">
           <url>file://$PROJECT_DIR$/src/datasources/zabbix-request.ts</url>
-          <line>213</line>
+          <line>253</line>
           <option name="timeStamp" value="6" />
         </line-breakpoint>
       </breakpoints>

README.md

@@ -18,7 +18,7 @@ The Zabbix GraphQL API acts as a wrapper and enhancer for the native Zabbix JSON
   - *Reference*: `schema/mutations.graphql` (importHosts, importTemplates, importUserRights, etc.), `docs/sample_import_*.graphql`
 
 - **Dynamic Schema Extension**: Extend the schema without code changes using environment variables
-  - *Reference*: `src/api/schema.ts`, `schema/extensions/`, `src/common_utils.ts` (ADDITIONAL_SCHEMAS, ADDITIONAL_RESOLVERS)
+  - *Reference*: `src/api/schema.ts`, `samples/extensions/` (sample extensions), `src/common_utils.ts` (ADDITIONAL_SCHEMAS, ADDITIONAL_RESOLVERS)
 
 - **Permission System**: Role-based access control using Zabbix template groups
   - *Reference*: `schema/api_commons.graphql` (Permission enum, PermissionRequest), `src/api/resolvers.ts` (hasPermissions, userPermissions), `docs/sample_import_permissions_template_groups_mutation.graphql`
@@ -213,7 +213,7 @@ HOST_GROUP_FILTER_DEFAULT=Roadwork/Devices/*
 HOST_TYPE_FILTER_DEFAULT=Roadwork/Devices
 
 # Schema Extensions (No-Code)
-ADDITIONAL_SCHEMAS=./schema/extensions/display_devices.graphql,./schema/extensions/location_tracker_devices.graphql,./schema/extensions/location_tracker_commons.graphql
+ADDITIONAL_SCHEMAS=./samples/extensions/display_devices.graphql,./samples/extensions/location_tracker_devices.graphql,./samples/extensions/location_tracker_commons.graphql
 ADDITIONAL_RESOLVERS=SinglePanelDevice,FourPanelDevice,DistanceTrackerDevice
 
 # Logging

docker-compose.yml

@@ -11,6 +11,8 @@ services:
     environment:
       - SCHEMA_PATH=/usr/app/dist/schema/
       - ZABBIX_DEVELOPMENT_TOKEN=${ZABBIX_DEVELOPMENT_TOKEN}
+    volumes:
+      - ./samples:/usr/app/dist/samples
 
   apollo-mcp-server:
     image: ghcr.io/apollographql/apollo-mcp-server:latest

docs/howtos/cookbook.md

@@ -73,12 +73,14 @@ Compare the GraphQL response with the expected output described in the Zabbix do
 
 This recipe shows how to add support for a new specialized device type without modifying the core API code. We will use the `DistanceTrackerDevice` as an example.
 
+> **Important**: Schema extensions are not part of the core API source code. They are loaded dynamically at runtime via environment variables. The extensions provided in the `samples/extensions/` directory of this repository are **samples** to demonstrate how to use this mechanism. You can place your own extension files in any directory accessible by the API server.
+
 ### 📋 Prerequisites
 - Zabbix Template Group `Templates/Roadwork/Devices` exists.
 - Zabbix GraphQL API is running.
 
 ### 🛠️ Step 1: Define the Schema Extension
-Create a new `.graphql` file in `schema/extensions/` (e.g. `distance_tracker.graphql`). 
+Create a new `.graphql` file in `samples/extensions/` (e.g. `distance_tracker.graphql`). 
 
 > **Advice**: A new device type must always implement both the `Host` and `Device` interfaces to ensure compatibility with the API's core logic and resolvers.
 
@@ -102,20 +104,20 @@ type DistanceTrackerState implements DeviceState {
 }
 
 type DistanceTrackerValues {
-  timeFrom: Time
+  timeFrom: String
-  timeUntil: Time
+  timeUntil: String
   count: Int
   # The distances are modelled using a type which is already defined in location_tracker_commons.graphql
   distances: [SensorDistanceValue!]
 }
 ```
 
-> **Reference**: This example is based on the already prepared sample: [location_tracker_devices.graphql](../../schema/extensions/location_tracker_devices.graphql).
+> **Reference**: This example is based on the already prepared sample: [location_tracker_devices.graphql](../../samples/extensions/location_tracker_devices.graphql).
 
 ### ⚙️ Step 2: Configure Environment Variables
 Add the new schema and resolver to your `.env` file:
 ```env
-ADDITIONAL_SCHEMAS=./schema/extensions/distance_tracker.graphql,./schema/extensions/location_tracker_commons.graphql
+ADDITIONAL_SCHEMAS=./samples/extensions/distance_tracker.graphql,./samples/extensions/location_tracker_commons.graphql
 ADDITIONAL_RESOLVERS=DistanceTrackerDevice
 ```
 Restart the API server.
@@ -203,7 +205,7 @@ This recipe demonstrates how to extend the schema with new device types that ret
 - The device has geo-coordinates set via user macros (e.g. `{$LAT}` and `{$LON}`).
 
 ### 🛠️ Step 1: Define the Schema Extension
-Create a new `.graphql` file in `schema/extensions/` (e.g. `weather_sensor.graphql` or `ground_value_checker.graphql`).
+Create a new `.graphql` file in `samples/extensions/` (e.g. `weather_sensor.graphql` or `ground_value_checker.graphql`).
 
 **Sample: Weather Sensor**
 ```graphql
@@ -262,7 +264,7 @@ type GroundValues {
 ### ⚙️ Step 2: Register the Resolver
 Add the new types and schemas to your `.env` file to enable the dynamic resolver:
 ```env
-ADDITIONAL_SCHEMAS=./schema/extensions/weather_sensor.graphql,./schema/extensions/ground_value_checker.graphql
+ADDITIONAL_SCHEMAS=./samples/extensions/weather_sensor.graphql,./samples/extensions/ground_value_checker.graphql
 ADDITIONAL_RESOLVERS=WeatherSensorDevice,GroundValueChecker
 ```
 Restart the API server to apply the changes.
@@ -344,6 +346,30 @@ Create a host, assign it macros for coordinates, and query its state.
 
 ---
 
+## 🍳 Recipe: Testing Specialized Device Types
+
+This recipe shows how to execute a comprehensive query to verify the state and configuration of specialized device types, such as the `DistanceTrackerDevice`. This is useful for validating that your schema extensions and hierarchical mappings are working correctly.
+
+### 📋 Prerequisites
+- Zabbix GraphQL API is running.
+- The schema has been extended with the `DistanceTrackerDevice` type (see [Recipe: Extending Schema with a New Device Type](#-recipe-extending-schema-with-a-new-device-type)). Sample extensions can be found in the `samples/extensions` directory.
+- At least one host with `deviceType` set to `DistanceTrackerDevice` exists in Zabbix.
+
+### 🛠️ Step 1: Get the Sample Query
+1.  **Open the Sample**: Open [docs/queries/sample_distance_tracker_test_query.graphql](../queries/sample_distance_tracker_test_query.graphql).
+2.  **Copy the Query**: Copy the GraphQL code block under the `### Query` header.
+
+### 🚀 Step 2: Execution/Action
+Execute the query against your GraphQL endpoint. This query retrieves information from `allHostGroups`, `allDevices`, and `allHosts`, using inline fragments to access fields specific to `DistanceTrackerDevice`.
+
+### ✅ Step 3: Verification
+Check the response for the following:
+- **apiVersion** and **zabbixVersion** are returned.
+- **allHostGroups** contains the expected groups.
+- **allDevices** and **allHosts** include your `DistanceTrackerDevice` with its specialized `state` (count, timeFrom, timeUntil) and `tags` (deviceWidgetPreview).
+
+---
+
 ## 🍳 Recipe: Provisioning a New Host
 
 ### 📋 Prerequisites

docs/howtos/query_optimization.md

@@ -22,7 +22,7 @@ The `GraphqlParamsToNeededZabbixOutput` class provides static methods to map Gra
 ### 3. Resolver Integration
 Resolvers use the mapper to determine the required output and pass it to the datasource:
 ```typescript
-const output = GraphqlParamsToNeededZabbixOutput.mapAllHosts(args, info);
+const output = GraphqlParamsToNeededZabbixOutput.mapAllHosts(info);
 return await new ZabbixQueryHostsRequestWithItemsAndInventory(...)
     .executeRequestThrowError(dataSources.zabbixAPI, new ParsedArgs(args), output);
 ```
@@ -30,6 +30,7 @@ return await new ZabbixQueryHostsRequestWithItemsAndInventory(...)
 ### 4. Indirect Dependencies
 Some GraphQL fields are not directly returned by Zabbix but are computed from other data. The optimization logic ensures these dependencies are handled:
 - **`state`**: Requesting the `state` field on a `Device` requires Zabbix `items`. The mapper automatically adds `items` to the requested output if `state` is present.
+- **`deviceType`**: Requesting `deviceType` requires Zabbix `tags` (or `inheritedTags`). This is needed because the `deviceType` is resolved from a Zabbix tag and will be empty otherwise. The optimization logic ensures that `selectTags` and `selectInheritedTags` are not skipped when `deviceType` is requested.
 
 ## 🛠️ Configuration
 Optimization rules are defined in the constructor of specialized `ZabbixRequest` classes.
@@ -37,7 +38,7 @@ Optimization rules are defined in the constructor of specialized `ZabbixRequest`
 ### 📋 Supported Optimizations
 - **Hosts & Devices**:
     - `selectParentTemplates` skipped if `parentTemplates` not requested.
-    - `selectTags` and `selectInheritedTags` skipped if `tags` not requested.
+    - `selectTags` and `selectInheritedTags` skipped if `tags` (or `deviceType`) not requested.
     - `selectHostGroups` skipped if `hostgroups` not requested.
     - `selectItems` skipped if `items` (or `state`) not requested.
     - `selectInventory` skipped if `inventory` not requested.

docs/howtos/schema.md

@@ -10,7 +10,7 @@ The GraphQL schema is located in the `../../schema/` directory and consists of:
 - `zabbix.graphql` - Zabbix-specific types (see detailed documentation in file comments)
 - `device_value_commons.graphql` - Common value types (see detailed documentation in file comments)
 - `api_commons.graphql` - Common API types and permission system (see detailed documentation in file comments)
-- `extensions/` - Custom device type extensions
+- `samples/extensions/` - Sample device type extensions (not part of the core source)
 
 For comprehensive understanding of each operation, read the detailed comments in the respective schema files.
 
@@ -38,7 +38,8 @@ The `Location` type represents geographical information from Zabbix host invento
 Extend the schema without code changes using environment variables:
 
 ```bash
-ADDITIONAL_SCHEMAS=./schema/extensions/display_devices.graphql,./schema/extensions/location_tracker_devices.graphql
+# Extensions can be located anywhere; samples are provided in samples/extensions/
+ADDITIONAL_SCHEMAS=./samples/extensions/display_devices.graphql,./samples/extensions/location_tracker_devices.graphql
 ADDITIONAL_RESOLVERS=SinglePanelDevice,FourPanelDevice,DistanceTrackerDevice
 ```
 

docs/queries/README.md

@@ -8,6 +8,7 @@ This directory contains practical examples of GraphQL operations for the Zabbix
 - [Query All Hosts](./sample_all_hosts_query.graphql): Retrieve basic host information and inventory.
 - [Import Hosts](./sample_import_hosts_mutation.graphql): Create or update multiple hosts with tags and group assignments.
 - [Query All Devices](./sample_all_devices_query.graphql): Query specialized devices using the `allDevices` query.
+- [Distance Tracker Test Query](./sample_distance_tracker_test_query.graphql): Comprehensive query for testing specialized `DistanceTrackerDevice` types.
 
 ### 📄 Templates
 - [Query Templates](./sample_templates_query.graphql): List available templates and their items.

docs/queries/sample_distance_tracker_test_query.graphql

@@ -0,0 +1,118 @@
+### Query
+This query demonstrates how to retrieve data from multiple sources, including specialized device types like `DistanceTrackerDevice`.
+
+> **Precondition**: This query will only work if the GraphQL schema has been extended with the `DistanceTrackerDevice` type (see the sample in `samples/extensions/location_tracker_devices.graphql`).
+
+```graphql
+query DistanceTrackerDeviceTest {
+     apiVersion
+     zabbixVersion
+     allHostGroups(search_name: "Roadwork/Devices/*") {
+         groupid
+         name
+     }
+     allDevices {
+         deviceType
+         host
+         name
+         ... on DistanceTrackerDevice {
+             state {
+                 current {
+                     count
+                     timeFrom
+                     timeUntil
+                 }
+             }
+         }
+     }
+     allHosts {
+         hostid
+         host
+         name
+         deviceType
+         ... on Device {
+             tags {
+                 deviceWidgetPreview {
+                     TOP_LEFT {
+                         key
+                         emptyValue
+                         unit
+                         value_font_size
+                         g_value_transform
+                         unit_font_size
+                         g_unit_transform
+                     }
+                     TOP_RIGHT {
+                         key
+                         emptyValue
+                         unit
+                         value_font_size
+                         g_value_transform
+                         unit_font_size
+                         g_unit_transform
+                     }
+                     BOTTOM_LEFT {
+                         key
+                         emptyValue
+                         unit
+                         value_font_size
+                         g_value_transform
+                         unit_font_size
+                         g_unit_transform
+                     }
+                     BOTTOM_RIGHT {
+                         key
+                         emptyValue
+                         unit
+                         value_font_size
+                         g_value_transform
+                         unit_font_size
+                         g_unit_transform
+                     }
+                 }
+             }
+         }
+         ... on DistanceTrackerDevice {
+             state {
+                 current {
+                     count
+                     timeFrom
+                     timeUntil
+                 }
+             }
+         }
+         ... on ZabbixHost {
+             items {
+                 itemid
+                 name
+                 key_
+                 hostid
+                 lastclock
+                 lastvalue
+                 value_type
+                 attributeName
+                 status
+                 type
+             }
+         }
+         ... on GenericDevice {
+             deviceType
+             state {
+                 generic: current
+             }
+         }
+         ... on SinglePanelDevice {
+             deviceType
+             state {
+                 current {
+                     values {
+                         contentIndex
+                         contentKey
+                         contentText
+                     }
+                 }
+             }
+         }
+     }
+ }
+```

docs/tests.md

@@ -71,6 +71,9 @@ This document outlines the test cases and coverage for the Zabbix GraphQL API.
 - **TC-DOCS-01**: Validate all Zabbix documentation sample queries.
 - **TC-MCP-01**: Validate all MCP operation files against the schema.
 
+### Schema-dependent Tests
+- **TC-SCHEMA-01**: Verify comprehensive query for `DistanceTrackerDevice` works correctly when schema is extended.
+
 ### End-to-End (E2E) Tests
 - **TC-E2E-01**: Run a complete smoketest using MCP (creates template, group, and host, verifies, and cleans up).
 - **TC-E2E-02**: Run all regression tests to verify critical system behavior and prevent known issues.
@@ -87,6 +90,7 @@ The `runAllRegressionTests` mutation (TC-E2E-02) executes the following checks:
 - **Dependent Items**: Verifies that templates with master and dependent items can be imported successfully, correctly resolving the dependency within the same import operation.
 - **State sub-properties**: Verifies that requesting device state sub-properties correctly triggers the retrieval of required Zabbix items, even if `items` is not explicitly requested (verifying the indirect dependency logic).
 - **Negative Optimization (allDevices)**: Verifies that items are NOT requested from Zabbix if neither `items` nor `state` (or state sub-properties) are requested within the `allDevices` query.
+- **allDevices deviceType filter**: Verifies that the `allDevices` query only returns hosts that have a `deviceType` tag, and that the `deviceType` field is populated for all results.
 
 ## ✅ Test Coverage Checklist
 
@@ -138,6 +142,7 @@ The `runAllRegressionTests` mutation (TC-E2E-02) executes the following checks:
 | TC-CONF-07 | Parse Zabbix Args | Unit | Jest | [src/test/zabbix_api_args_parser.test.ts](../src/test/zabbix_api_args_parser.test.ts) |
 | TC-DOCS-01 | Zabbix Docs Samples Integration | Integration | Jest | [src/test/zabbix_docs_samples.test.ts](../src/test/zabbix_docs_samples.test.ts) |
 | TC-MCP-01 | MCP Operations Validation | Integration | Jest | [src/test/mcp_operations_validation.test.ts](../src/test/mcp_operations_validation.test.ts) |
+| TC-SCHEMA-01 | DistanceTrackerDevice Query | Integration | Jest | [src/test/schema_dependent_queries.test.ts](../src/test/schema_dependent_queries.test.ts) |
 | TC-E2E-01 | Run complete smoketest | E2E | GraphQL / MCP | [mcp/operations/runSmoketest.graphql](../mcp/operations/runSmoketest.graphql) |
 | TC-E2E-02 | Run all regression tests | E2E | GraphQL / MCP | [mcp/operations/runAllRegressionTests.graphql](../mcp/operations/runAllRegressionTests.graphql) |
 

mcp/operations/runAllRegressionTests.graphql

@@ -1,7 +1,6 @@
 # Runs all regression tests.
-# Variables: hostName, groupName
+mutation RunAllRegressionTests {
-mutation RunAllRegressionTests($hostName: String!, $groupName: String!) {
+  runAllRegressionTests {
-  runAllRegressionTests(hostName: $hostName, groupName: $groupName) {
     success
     message
     steps {

samples/extensions/location_tracker_devices.graphql

@@ -42,11 +42,11 @@ type DistanceTrackerValues {
     """
     Start of time interval for the delivered device counting value.
     """
-    timeFrom: Time
+    timeFrom: String
     """
     End of time interval for the delivered device counting value.
     """
-    timeUntil: Time
+    timeUntil: String
 
     """
     Number of unique device keys detected between timeFrom and timeUntil.

schema/mutations.graphql

@@ -142,12 +142,7 @@ type Mutation {
     """
     Runs all regression tests.
     """
-    runAllRegressionTests(
+    runAllRegressionTests: SmoketestResponse!
-        """Technical name for the test host."""
-        hostName: String!, 
-        """Technical name for the test host group."""
-        groupName: String!
-    ): SmoketestResponse!
 }
 
 """

src/api/resolvers.ts

@@ -107,7 +107,7 @@ export function createResolvers(): Resolvers {
                 if (Config.HOST_TYPE_FILTER_DEFAULT) {
                     args.tag_hostType ??= [Config.HOST_TYPE_FILTER_DEFAULT];
                 }
-                const output = GraphqlParamsToNeededZabbixOutput.mapAllHosts(args, info);
+                const output = GraphqlParamsToNeededZabbixOutput.mapAllHosts(info);
                 return await new ZabbixQueryHostsRequestWithItemsAndInventory(zabbixAuthToken, cookie)
                     .executeRequestThrowError(
                         dataSources?.zabbixAPI || zabbixAPI, new ParsedArgs(args), output
@@ -120,7 +120,7 @@ export function createResolvers(): Resolvers {
                 if (Config.HOST_TYPE_FILTER_DEFAULT) {
                     args.tag_hostType ??= [Config.HOST_TYPE_FILTER_DEFAULT];
                 }
-                const output = GraphqlParamsToNeededZabbixOutput.mapAllDevices(args, info);
+                const output = GraphqlParamsToNeededZabbixOutput.mapAllDevices(info);
                 return await new ZabbixQueryDevices(zabbixAuthToken, cookie)
                     .executeRequestThrowError(
                         dataSources?.zabbixAPI || zabbixAPI, new ZabbixQueryDevicesArgs(args), output
@@ -133,7 +133,7 @@ export function createResolvers(): Resolvers {
                 if (!args.search_name && Config.HOST_GROUP_FILTER_DEFAULT) {
                     args.search_name = Config.HOST_GROUP_FILTER_DEFAULT
                 }
-                const output = GraphqlParamsToNeededZabbixOutput.mapAllHostGroups(args, info);
+                const output = GraphqlParamsToNeededZabbixOutput.mapAllHostGroups(info);
                 return await new ZabbixQueryHostgroupsRequest(zabbixAuthToken, cookie).executeRequestThrowError(
                     dataSources?.zabbixAPI || zabbixAPI, new ZabbixQueryHostgroupsParams(args), output
                 )
@@ -173,7 +173,7 @@ export function createResolvers(): Resolvers {
                         name: args.name_pattern
                     }
                 }
-                const output = GraphqlParamsToNeededZabbixOutput.mapTemplates(args, info);
+                const output = GraphqlParamsToNeededZabbixOutput.mapTemplates(info);
                 return await new ZabbixQueryTemplatesRequest(zabbixAuthToken, cookie)
                     .executeRequestThrowError(dataSources?.zabbixAPI || zabbixAPI, new ParsedArgs(params), output);
             },
@@ -287,11 +287,11 @@ export function createResolvers(): Resolvers {
             }: any) => {
                 return SmoketestExecutor.runSmoketest(args.hostName, args.templateName, args.groupName, zabbixAuthToken, cookie)
             },
-            runAllRegressionTests: async (_parent: any, args: any, {
+            runAllRegressionTests: async (_parent: any, _args: any, {
                 zabbixAuthToken,
                 cookie
             }: any) => {
-                return RegressionTestExecutor.runAllRegressionTests(args.hostName, args.groupName, zabbixAuthToken, cookie)
+                return RegressionTestExecutor.runAllRegressionTests(zabbixAuthToken, cookie)
             }
         },
 

src/datasources/graphql-params-to-zabbix-output.ts

@@ -1,26 +1,20 @@
 import {GraphQLResolveInfo} from "graphql";
 import {getRequestedFields} from "../api/graphql_utils.js";
-import {
-    QueryAllDevicesArgs,
-    QueryAllHostGroupsArgs,
-    QueryAllHostsArgs,
-    QueryTemplatesArgs
-} from "../schema/generated/graphql.js";
 
 export class GraphqlParamsToNeededZabbixOutput {
-    static mapAllHosts(args: QueryAllHostsArgs, info: GraphQLResolveInfo): string[] {
+    static mapAllHosts(info: GraphQLResolveInfo): string[] {
         return getRequestedFields(info);
     }
 
-    static mapAllDevices(args: QueryAllDevicesArgs, info: GraphQLResolveInfo): string[] {
+    static mapAllDevices(info: GraphQLResolveInfo): string[] {
         return getRequestedFields(info);
     }
 
-    static mapAllHostGroups(args: QueryAllHostGroupsArgs, info: GraphQLResolveInfo): string[] {
+    static mapAllHostGroups(info: GraphQLResolveInfo): string[] {
         return getRequestedFields(info);
     }
 
-    static mapTemplates(args: QueryTemplatesArgs, info: GraphQLResolveInfo): string[] {
+    static mapTemplates(info: GraphQLResolveInfo): string[] {
         return getRequestedFields(info);
     }
 }

src/datasources/zabbix-hosts.ts

@@ -21,6 +21,8 @@ export class ZabbixQueryHostsGenericRequest<T extends ZabbixResult, A extends Pa
         this.skippableZabbixParams.set("selectTags", "tags");
         this.skippableZabbixParams.set("selectInheritedTags", "tags");
         this.skippableZabbixParams.set("selectHostGroups", "hostgroups");
+        this.impliedFields.set("deviceType", ["tags"]);
+        this.impliedFields.set("hostType", ["tags"]);
     }
 
     createZabbixParams(args?: A, output?: string[]): ZabbixParams {

src/datasources/zabbix-templates.ts

@@ -115,7 +115,7 @@ export class TemplateHelper {
             // Use name_pattern which now searches both visibility name and technical name (host)
             let templates = await new ZabbixQueryTemplatesRequest(zabbixAuthToken, cookie).executeRequestReturnError(zabbixApi, new ParsedArgs({
                 name_pattern: templateName
-            }))
+            }), ["templateid", "host"])
 
             if (isZabbixErrorResult(templates) || !templates?.length) {
                 logger.error(`Unable to find templateName=${templateName}`)

src/execution/host_importer.ts

@@ -174,7 +174,7 @@ export class HostImporter {
                 {
                     tag_deviceType: deviceType
                 }
-            ));
+            ), ["templateid"]);
 
         if (templates?.length) {
             result = Number(templates[0].templateid)

src/execution/regression_test_executor.ts

@@ -12,13 +12,16 @@ import {
     ZabbixQueryHostsGenericRequestWithItems
 } from "../datasources/zabbix-hosts.js";
 import {ZabbixQueryTemplatesRequest} from "../datasources/zabbix-templates.js";
-import {ParsedArgs} from "../datasources/zabbix-request.js";
+import {isZabbixErrorResult, ParsedArgs, ZabbixRequest} from "../datasources/zabbix-request.js";
 
 export class RegressionTestExecutor {
-    public static async runAllRegressionTests(hostName: string, groupName: string, zabbixAuthToken?: string, cookie?: string): Promise<SmoketestResponse> {
+    public static async runAllRegressionTests(zabbixAuthToken?: string, cookie?: string): Promise<SmoketestResponse> {
         const steps: SmoketestStep[] = [];
         let success = true;
 
+        const hostName = "REG_HOST_" + Math.random().toString(36).substring(7);
+        const groupName = "REG_GROUP_" + Math.random().toString(36).substring(7);
+
         try {
             // Regression 1: Locations query argument order
             // This verifies the fix where getLocations was called with (authToken, args) instead of (args, authToken)
@@ -309,8 +312,15 @@ export class RegressionTestExecutor {
                 
                 optSuccess = optSuccess && hasSelectItems3 && hasOutput3;
                 
+                // 4. Test indirect dependencies: deviceType implies tags
+                const testParams4 = optRequest.createZabbixParams(new ParsedArgs({}), ["hostid", "deviceType"]);
+                const hasSelectTags4 = "selectTags" in testParams4;
+                const hasOutput4 = Array.isArray(testParams4.output) && testParams4.output.includes("hostid");
+                
+                optSuccess = optSuccess && hasSelectTags4 && hasOutput4;
+
                 if (!optSuccess) {
-                    logger.error(`REG-OPT: Optimization verification failed. hasSelectItems1: ${hasSelectItems1}, hasOutput1: ${hasOutput1}, hasSelectItems2: ${hasSelectItems2}, hasSelectTags2: ${hasSelectTags2}, hasSelectItems3: ${hasSelectItems3}, hasOutput3: ${hasOutput3}`);
+                    logger.error(`REG-OPT: Optimization verification failed. hasSelectItems1: ${hasSelectItems1}, hasOutput1: ${hasOutput1}, hasSelectItems2: ${hasSelectItems2}, hasSelectTags2: ${hasSelectTags2}, hasSelectItems3: ${hasSelectItems3}, hasOutput3: ${hasOutput3}, hasSelectTags4: ${hasSelectTags4}, hasOutput4: ${hasOutput4}`);
                 }
             } catch (error) {
                 logger.error(`REG-OPT: Error during optimization test: ${error}`);
@@ -469,6 +479,57 @@ export class RegressionTestExecutor {
             });
             if (!optNegSuccess) success = false;
 
+            // Regression 12: allDevices deviceType filter
+            // Verifies that allDevices only returns hosts with a deviceType tag
+            const devHostNameWithTag = "REG_DEV_WITH_TAG_" + Math.random().toString(36).substring(7);
+            const devHostNameWithoutTag = "REG_DEV_WITHOUT_TAG_" + Math.random().toString(36).substring(7);
+
+            // Get groupid for hostGroupName
+            const groupQuery: any = await new ZabbixRequest("hostgroup.get", zabbixAuthToken, cookie)
+                .executeRequestReturnError(zabbixAPI, new ParsedArgs({ filter_name: hostGroupName }));
+            const regGroupId = Array.isArray(groupQuery) && groupQuery[0]?.groupid;
+
+            if (regGroupId) {
+                await HostImporter.importHosts([{
+                    deviceKey: devHostNameWithTag,
+                    deviceType: "RegressionDevice",
+                    groupNames: [hostGroupName]
+                }], zabbixAuthToken, cookie);
+
+                await new ZabbixRequest("host.create", zabbixAuthToken, cookie).executeRequestReturnError(zabbixAPI, new ParsedArgs({
+                    host: devHostNameWithoutTag,
+                    name: devHostNameWithoutTag,
+                    groups: [{ groupid: regGroupId }]
+                }));
+
+                const allDevicesResult: any = await new ZabbixQueryDevices(zabbixAuthToken, cookie)
+                    .executeRequestReturnError(zabbixAPI, new ZabbixQueryDevicesArgs({
+                        filter_host: [devHostNameWithTag, devHostNameWithoutTag]
+                    }), ["name", "host", "hostid", "deviceType"]);
+
+                if (isZabbixErrorResult(allDevicesResult)) {
+                    steps.push({
+                        name: "REG-DEV-FILTER: allDevices deviceType filter",
+                        success: false,
+                        message: `Zabbix error: ${allDevicesResult.error.message}`
+                    });
+                } else {
+                    const hasHostWithTag = allDevicesResult.some((d: any) => d.host === devHostNameWithTag);
+                    const hasHostWithoutTag = allDevicesResult.some((d: any) => d.host === devHostNameWithoutTag);
+                    const devTypeNotNull = allDevicesResult.length > 0 && allDevicesResult.every((d: any) => d.deviceType !== null && d.deviceType !== undefined && d.deviceType !== "");
+
+                    const devFilterSuccess = hasHostWithTag && !hasHostWithoutTag && devTypeNotNull;
+                    steps.push({
+                        name: "REG-DEV-FILTER: allDevices deviceType filter",
+                        success: devFilterSuccess,
+                        message: devFilterSuccess 
+                            ? `allDevices correctly filtered out hosts without deviceType tag`
+                            : `Failed: withTag=${hasHostWithTag}, withoutTag=${hasHostWithoutTag}, typeNotNull=${devTypeNotNull}, result=${JSON.stringify(allDevicesResult)}`
+                    });
+                    if (!devFilterSuccess) success = false;
+                }
+            }
+
             // Step 1: Create Host Group (Legacy test kept for compatibility)
             const groupResult = await HostImporter.importHostGroups([{
                 groupName: groupName
@@ -486,6 +547,8 @@ export class RegressionTestExecutor {
             await HostDeleter.deleteHosts(null, hostName, zabbixAuthToken, cookie);
             await HostDeleter.deleteHosts(null, macroHostName, zabbixAuthToken, cookie);
             await HostDeleter.deleteHosts(null, metaHostName, zabbixAuthToken, cookie);
+            await HostDeleter.deleteHosts(null, devHostNameWithTag, zabbixAuthToken, cookie);
+            await HostDeleter.deleteHosts(null, devHostNameWithoutTag, zabbixAuthToken, cookie);
             await TemplateDeleter.deleteTemplates(null, regTemplateName, zabbixAuthToken, cookie);
             await TemplateDeleter.deleteTemplates(null, httpTempName, zabbixAuthToken, cookie);
             await TemplateDeleter.deleteTemplates(null, macroTemplateName, zabbixAuthToken, cookie);

src/execution/template_importer.ts

@@ -108,7 +108,7 @@ export class TemplateImporter {
                 let templateNames = template.templates.map(t => t.name)
                 let queryResult = await new ZabbixQueryTemplatesRequest(zabbixAuthToken, cookie).executeRequestReturnError(zabbixAPI, new ParsedArgs({
                     filter_host: templateNames
-                }))
+                }), ["templateid"])
 
                 if (isZabbixErrorResult(queryResult)) {
                     let errorMessage = queryResult.error.message;

src/schema/generated/graphql.ts

@@ -642,12 +642,6 @@ export interface MutationImportUserRightsArgs {
 }
 
 
-export interface MutationRunAllRegressionTestsArgs {
-  groupName: Scalars['String']['input'];
-  hostName: Scalars['String']['input'];
-}
-
-
 export interface MutationRunSmoketestArgs {
   groupName: Scalars['String']['input'];
   hostName: Scalars['String']['input'];
@@ -1597,7 +1591,7 @@ export type MutationResolvers<ContextType = any, ParentType extends ResolversPar
   importTemplateGroups?: Resolver<Maybe<Array<ResolversTypes['CreateTemplateGroupResponse']>>, ParentType, ContextType, RequireFields<MutationImportTemplateGroupsArgs, 'templateGroups'>>;
   importTemplates?: Resolver<Maybe<Array<ResolversTypes['ImportTemplateResponse']>>, ParentType, ContextType, RequireFields<MutationImportTemplatesArgs, 'templates'>>;
   importUserRights?: Resolver<Maybe<ResolversTypes['ImportUserRightsResult']>, ParentType, ContextType, RequireFields<MutationImportUserRightsArgs, 'dryRun' | 'input'>>;
-  runAllRegressionTests?: Resolver<ResolversTypes['SmoketestResponse'], ParentType, ContextType, RequireFields<MutationRunAllRegressionTestsArgs, 'groupName' | 'hostName'>>;
+  runAllRegressionTests?: Resolver<ResolversTypes['SmoketestResponse'], ParentType, ContextType>;
   runSmoketest?: Resolver<ResolversTypes['SmoketestResponse'], ParentType, ContextType, RequireFields<MutationRunSmoketestArgs, 'groupName' | 'hostName' | 'templateName'>>;
 };
 

src/test/host_query.test.ts

@@ -57,8 +57,8 @@ describe("Host and HostGroup Resolvers", () => {
         }));
     });
 
-    test("allDevices query", async () => {
+    test("allDevices query - with hostid", async () => {
-        const mockDevices = [{ hostid: "2", host: "Device 1" }];
+        const mockDevices = [{ hostid: "2", host: "Device 1", deviceType: "GenericDevice" }];
         (zabbixAPI.post as jest.Mock).mockResolvedValueOnce(mockDevices);
 
         const args: QueryAllDevicesArgs = { hostids: 2 };
@@ -74,7 +74,63 @@ describe("Host and HostGroup Resolvers", () => {
             body: expect.objectContaining({
                 method: "host.get",
                 params: expect.objectContaining({
-                    hostids: 2
+                    hostids: 2,
+                    tags: expect.arrayContaining([{
+                        tag: "deviceType",
+                        operator: 4
+                    }])
+                })
+            })
+        }));
+    });
+
+    test("allDevices query - with deviceType filter", async () => {
+        const mockDevices = [{ hostid: "2", host: "Device 1", deviceType: "SomeType" }];
+        (zabbixAPI.post as jest.Mock).mockResolvedValueOnce(mockDevices);
+
+        const args: QueryAllDevicesArgs = { tag_deviceType: ["SomeType"] };
+        const context = { 
+            zabbixAuthToken: "test-token",
+            dataSources: { zabbixAPI: zabbixAPI }
+        };
+
+        const result = await resolvers.Query.allDevices(null, args, context);
+
+        expect(result).toEqual(mockDevices);
+        expect(zabbixAPI.post).toHaveBeenCalledWith("host.get.with_items", expect.objectContaining({
+            body: expect.objectContaining({
+                params: expect.objectContaining({
+                    tags: expect.arrayContaining([{
+                        tag: "deviceType",
+                        operator: 1,
+                        value: "SomeType"
+                    }])
+                })
+            })
+        }));
+    });
+
+    test("allDevices query - ensures deviceType exists if no filter provided", async () => {
+        const mockDevices = [{ hostid: "3", host: "Device with tag", deviceType: "SomeType" }];
+        (zabbixAPI.post as jest.Mock).mockResolvedValueOnce(mockDevices);
+
+        const args: QueryAllDevicesArgs = {};
+        const context = { 
+            zabbixAuthToken: "test-token",
+            dataSources: { zabbixAPI: zabbixAPI }
+        };
+
+        const result = await resolvers.Query.allDevices(null, args, context);
+
+        expect(result).toEqual(mockDevices);
+        expect(zabbixAPI.post).toHaveBeenCalledWith("host.get.with_items", expect.objectContaining({
+            body: expect.objectContaining({
+                method: "host.get",
+                params: expect.objectContaining({
+                    tags: expect.arrayContaining([{
+                        tag: "deviceType",
+                        operator: 4
+                    }])
                 })
             })
         }));

src/test/query_optimization.test.ts

@@ -163,6 +163,37 @@ describe("Query Optimization", () => {
         expect(callParams.output).toContain("items");
     });
 
+    test("allHosts optimization - keep selectTags when deviceType requested", async () => {
+        (zabbixAPI.post as jest.Mock).mockResolvedValueOnce([]);
+
+        const args: QueryAllHostsArgs = {};
+        const context = { 
+            zabbixAuthToken: "test-token",
+            dataSources: { zabbixAPI: zabbixAPI }
+        };
+        const info = {
+            fieldNodes: [{
+                selectionSet: {
+                    selections: [
+                        { kind: 'Field', name: { value: 'hostid' } },
+                        { kind: 'Field', name: { value: 'deviceType' } }
+                    ]
+                }
+            }]
+        };
+
+        await resolvers.Query.allHosts(null, args, context, info);
+
+        expect(zabbixAPI.post).toHaveBeenCalledWith(expect.any(String), expect.objectContaining({
+            body: expect.objectContaining({
+                params: expect.objectContaining({
+                    output: ["hostid"],
+                    selectTags: expect.any(Array)
+                })
+            })
+        }));
+    });
+
     test("allDevices optimization - skip items when not requested", async () => {
         (zabbixAPI.post as jest.Mock).mockResolvedValueOnce([]);
 

src/test/schema_dependent_queries.test.ts

@@ -0,0 +1,173 @@
+import {ApolloServer} from '@apollo/server';
+import {schema_loader} from '../api/schema.js';
+import {readFileSync} from 'fs';
+import {join} from 'path';
+import {zabbixAPI} from '../datasources/zabbix-api.js';
+import {Config} from "../common_utils.js";
+
+describe("Schema-dependent Queries Integration Tests", () => {
+    let server: ApolloServer;
+    let postSpy: jest.SpyInstance;
+
+    let originalSchemas: any;
+    let originalResolvers: any;
+    let originalApiVersion: any;
+
+    beforeAll(async () => {
+        originalSchemas = Config.ADDITIONAL_SCHEMAS;
+        originalResolvers = Config.ADDITIONAL_RESOLVERS;
+        originalApiVersion = Config.API_VERSION;
+
+        // We need to bypass the static readonly nature of Config for this test.
+        Object.defineProperty(Config, 'ADDITIONAL_SCHEMAS', {
+            value: "./samples/extensions/location_tracker_devices.graphql,./samples/extensions/location_tracker_commons.graphql,./samples/extensions/display_devices.graphql",
+            configurable: true
+        });
+        Object.defineProperty(Config, 'ADDITIONAL_RESOLVERS', {
+            value: "DistanceTrackerDevice,SinglePanelDevice",
+            configurable: true
+        });
+        Object.defineProperty(Config, 'API_VERSION', {
+            value: "1.2.3",
+            configurable: true
+        });
+
+        const schema = await schema_loader();
+        server = new ApolloServer({
+            schema,
+        });
+
+        postSpy = jest.spyOn(zabbixAPI, 'post');
+    });
+
+    afterAll(() => {
+        postSpy.mockRestore();
+        Object.defineProperty(Config, 'ADDITIONAL_SCHEMAS', { value: originalSchemas });
+        Object.defineProperty(Config, 'ADDITIONAL_RESOLVERS', { value: originalResolvers });
+        Object.defineProperty(Config, 'API_VERSION', { value: originalApiVersion });
+    });
+
+    test("TC-SCHEMA-01: DistanceTrackerDevice Comprehensive Query", async () => {
+        const filePath = join(process.cwd(), 'docs', 'queries', 'sample_distance_tracker_test_query.graphql');
+        const content = readFileSync(filePath, 'utf-8').replace(/\r\n/g, '\n');
+        
+        const queryMatch = content.match(/```graphql\n([\s\S]*?)\n```/);
+        if (!queryMatch) {
+            throw new Error(`No graphql block found in sample query file`);
+        }
+        const query = queryMatch[1];
+
+        // Setup mock responses for Zabbix API
+        postSpy.mockImplementation((method: string) => {
+            if (method === 'apiinfo.version') return Promise.resolve("7.4.0");
+            if (method.startsWith('hostgroup.get')) {
+                return Promise.resolve([
+                    { groupid: "1", name: "Roadwork/Devices/Tracker" }
+                ]);
+            }
+            if (method.startsWith('host.get')) {
+                return Promise.resolve([
+                    {
+                        hostid: "10001",
+                        host: "TRACKER_01",
+                        name: "Distance Tracker 01",
+                        deviceType: "DistanceTrackerDevice", // Manually mapped because we mock post()
+                        tags: [
+                            { tag: "deviceType", value: "DistanceTrackerDevice" }
+                        ],
+                        items: [
+                            { itemid: "1", name: "Count", key_: "state.current.count", lastvalue: "5", lastclock: 1704103200, value_type: "3" },
+                            { itemid: "2", name: "Time From", key_: "state.current.timeFrom", lastvalue: "2024-01-01T10:00:00Z", lastclock: 1704103200, value_type: "4" },
+                            { itemid: "3", name: "Time Until", key_: "state.current.timeUntil", lastvalue: "2024-01-01T11:00:00Z", lastclock: 1704103200, value_type: "4" }
+                        ],
+                        inheritedTags: []
+                    },
+                    {
+                        hostid: "10003",
+                        host: "TRACKER_02",
+                        name: "Distance Tracker 02",
+                        deviceType: "DistanceTrackerDevice",
+                        tags: [
+                            { tag: "deviceType", value: "DistanceTrackerDevice" }
+                        ],
+                        items: [
+                            { itemid: "10", name: "Count", key_: "state.current.count", lastvalue: "10", lastclock: 1704103200, value_type: "3" },
+                            { itemid: "11", name: "Time From", key_: "state.current.timeFrom", lastvalue: "09:58:09", lastclock: 1704103200, value_type: "4" }
+                        ],
+                        inheritedTags: []
+                    },
+                    {
+                        hostid: "10004",
+                        host: "TRACKER_03",
+                        name: "Distance Tracker 03",
+                        deviceType: "DistanceTrackerDevice",
+                        tags: [
+                            { tag: "deviceType", value: "DistanceTrackerDevice" }
+                        ],
+                        items: [
+                            { itemid: "20", name: "Count", key_: "state.current.count", lastvalue: "0", lastclock: 1704103200, value_type: "3" },
+                            { itemid: "21", name: "Time From", key_: "state.current.timeFrom", lastvalue: "", lastclock: 1704103200, value_type: "4" }
+                        ],
+                        inheritedTags: []
+                    },
+                    {
+                        hostid: "10002",
+                        host: "DISPLAY_01",
+                        name: "LED Display 01",
+                        deviceType: "SinglePanelDevice", // Manually mapped because we mock post()
+                        tags: [
+                            { tag: "deviceType", value: "SinglePanelDevice" }
+                        ],
+                        items: [
+                            { itemid: "4", name: "Content", key_: "state.current.values.1.contentText", lastvalue: "Roadwork Ahead", lastclock: 1704103200, value_type: "4" }
+                        ],
+                        inheritedTags: []
+                    }
+                ]);
+            }
+            return Promise.resolve([]);
+        });
+
+        const response = await server.executeOperation({
+            query: query,
+        }, {
+            contextValue: { zabbixAuthToken: 'test-token', dataSources: { zabbixAPI: zabbixAPI } }
+        });
+
+        if (response.body.kind === 'single') {
+            const result = response.body.singleResult;
+            if (result.errors) {
+                console.error(`Errors in query:`, JSON.stringify(result.errors, null, 2));
+            }
+            expect(result.errors).toBeUndefined();
+            
+            const data = result.data as any;
+            expect(data.apiVersion).toBe("1.2.3");
+            expect(data.zabbixVersion).toBe("7.4.0");
+            expect(data.allHostGroups).toHaveLength(1);
+            expect(data.allDevices).toBeDefined();
+            
+            // Verify DistanceTrackerDevice resolution
+            const tracker = data.allDevices.find((d: any) => d.host === "TRACKER_01");
+            expect(tracker.deviceType).toBe("DistanceTrackerDevice");
+            expect(tracker.state.current.count).toBe(5);
+            expect(tracker.state.current.timeFrom).toBe("2024-01-01T10:00:00Z");
+
+            const tracker02 = data.allDevices.find((d: any) => d.host === "TRACKER_02");
+            expect(tracker02.state.current.count).toBe(10);
+            expect(tracker02.state.current.timeFrom).toBe("09:58:09");
+
+            const tracker03 = data.allDevices.find((d: any) => d.host === "TRACKER_03");
+            expect(tracker03.state.current.timeFrom).toBe("");
+            
+            // Verify allHosts with fragments
+            const trackerInHosts = data.allHosts.find((h: any) => h.host === "TRACKER_01");
+            expect(trackerInHosts.state.current.count).toBe(5);
+            
+            const displayInHosts = data.allHosts.find((h: any) => h.host === "DISPLAY_01");
+            expect(displayInHosts.deviceType).toBe("SinglePanelDevice");
+        } else {
+            throw new Error(`Unexpected response kind: ${response.body.kind}`);
+        }
+    });
+});