feat: Add Mojmap support

Implements full support for Mojang's official mappings (Mojmap) alongside existing Yarn support.

  Key changes:
  - Add mojang2tiny Java tool wrapper for converting ProGuard → Tiny v2 format
  - Implement Tiny v2 to v1 converter for mojang2tiny input compatibility
  - Add post-processor to fix mojang2tiny's invalid Tiny v2 output format
  - Implement 2-step Mojmap remapping: official → intermediary → named
  - Add download locks to prevent race conditions in parallel test execution
  - Configure sequential test file execution to prevent singleton conflicts
  - Add comprehensive Mojmap test suite (11 new tests)
  - Update README with version support matrix (1.14+ for both Yarn and Mojmap)

  Technical implementation:
  - src/java/mojang2tiny.ts - Java wrapper for mojang2tiny tool
  - src/services/mapping-service.ts - Tiny format converters and Mojmap download/conversion
  - src/services/remap-service.ts - Mojmap 2-step remapping process with locking
  - src/downloaders/java-resources.ts - mojang2tiny JAR download with locking
  - vitest.config.ts - Sequential file execution to prevent race conditions

  All tests passing (93 tests including Yarn and Mojmap integration tests).

Author: GhostTypes

.claude/settings.local.json

@@ -21,7 +21,13 @@
       "mcp__minecraft-dev__analyze_mod_jar",
       "WebFetch(domain:www.minecraft.net)",
       "WebFetch(domain:fabricmc.net)",
-      "WebFetch(domain:maven.fabricmc.net)"
+      "WebFetch(domain:maven.fabricmc.net)",
+      "Bash(npx biome:*)",
+      "Bash(ls:*)",
+      "Bash(java -jar:*)",
+      "Bash(head:*)",
+      "Bash(npx vitest:*)",
+      "Bash(git reset:*)"
     ]
   },
   "enableAllProjectMcpServers": true,

FIND_MAPPING_MOJMAP_TODO.md

@@ -0,0 +1,70 @@
+# find_mapping Tool - Mojmap Support Limitation
+
+## Issue Summary
+
+The `find_mapping` MCP tool does not correctly support looking up Mojang class names.
+
+## Technical Details
+
+### Current Behavior
+
+In `src/services/mapping-service.ts`, the `lookupMapping()` method:
+
+1. Always uses **Yarn mappings** as the lookup source (line 318):
+   ```typescript
+   const mappingPath = await this.getMappings(version, 'yarn');
+   ```
+
+2. Maps `'mojmap'` to `'official'` namespace (line 408-409):
+   ```typescript
+   case 'mojmap':
+     return 'official'; // Mojmap uses obfuscated -> named, but we only have official
+   ```
+
+### The Problem
+
+- Yarn mappings contain: `official` (obfuscated), `intermediary`, and `named` (Yarn names)
+- Yarn mappings do **NOT** contain Mojang's human-readable names
+- Mojang names like `net.minecraft.world.entity.Entity` only exist in the converted Mojmap tiny file
+
+### What Doesn't Work
+
+```
+find_mapping({
+  symbol: "net.minecraft.world.entity.Entity",  // Mojang name
+  sourceMapping: "mojmap",
+  targetMapping: "intermediary"
+})
+```
+
+This won't find anything because the Yarn file doesn't contain Mojang names.
+
+### What Does Work
+
+- `yarn` -> `intermediary` (works)
+- `intermediary` -> `yarn` (works)
+- `official` -> `intermediary` (works)
+- `intermediary` -> `official` (works)
+
+## Proposed Fix
+
+Modify `lookupMapping()` to:
+
+1. When `sourceMapping` or `targetMapping` is `'mojmap'`, load the Mojmap tiny file instead of Yarn
+2. The Mojmap tiny file has namespaces: `intermediary` and `named` (Mojang names)
+3. Map `'mojmap'` to `'named'` namespace instead of `'official'`
+
+### Implementation Notes
+
+- The converted Mojmap file is at: `getMojmapTinyPath(version)`
+- Path: `mappings/mojmap-tiny-{version}.tiny`
+- Namespaces in file: `intermediary`, `named`
+
+## Priority
+
+Low - This is a pre-existing limitation, not a regression. The core Mojmap remapping functionality works correctly.
+
+## Related Files
+
+- `src/services/mapping-service.ts` - `lookupMapping()` method
+- `src/server/tools.ts` - `find_mapping` tool handler

README.md

@@ -29,7 +29,7 @@
   </tr>
   <tr>
     <td><b>Automatic Decompilation</b></td>
-    <td>Download, remap, and decompile any Minecraft version (1.21.1+)</td>
+    <td>Download, remap, and decompile any Minecraft version (1.14+)</td>
   </tr>
   <tr>
     <td><b>Multiple Mapping Types</b></td>
@@ -452,6 +452,43 @@ All data is cached in a platform-specific directory:
 </table>
 </div>
 
+<div align="center">
+  <h1>Version Support</h1>
+</div>
+
+<div align="center">
+
+**Supported Minecraft Versions:** 1.14+ (any version with available mappings)
+
+<table>
+  <tr>
+    <th>Version Range</th>
+    <th>Yarn Mappings</th>
+    <th>Mojmap</th>
+    <th>Notes</th>
+  </tr>
+  <tr>
+    <td><b>1.14 - 1.21.11</b></td>
+    <td>✅ Full Support</td>
+    <td>✅ Full Support</td>
+    <td>Obfuscated versions requiring remapping</td>
+  </tr>
+  <tr>
+    <td><b>26.1+</b></td>
+    <td>❌ Not Available</td>
+    <td>✅ Official Names</td>
+    <td>Deobfuscated by Mojang (no remapping needed)</td>
+  </tr>
+</table>
+
+**Important Notes:**
+- **1.21.11** is the last obfuscated Minecraft version
+- **Yarn mappings discontinued** after 1.21.11 (obfuscation removal makes them unnecessary)
+- **Future versions (26.1+)** ship with official deobfuscated code
+- Tested on: **1.19.4**, **1.20.1**, **1.21.10**, **1.21.11** (latest)
+
+</div>
+
 <div align="center">
   <h1>Configuration</h1>
 </div>
@@ -602,8 +639,9 @@ When you request another class from the same version:
   <tr>
     <td><b>Mappings Not Available</b><br><code>Yarn mappings not available for version X.X.X</code></td>
     <td>
-      Yarn mappings only support 1.21.1+<br>
-      Try using <code>"mapping": "mojmap"</code> instead
+      Yarn mappings support 1.14-1.21.11 (discontinued after 1.21.11)<br>
+      Mojmap supports 1.14.4+<br>
+      For versions 26.1+, use Mojmap (Minecraft is now deobfuscated by default)
     </td>
   </tr>
 </table>

__tests__/cache/cache-manager.test.ts

@@ -1,6 +1,6 @@
-import { describe, it, expect } from 'vitest';
+import { describe, expect, it } from 'vitest';
 import { getCacheManager } from '../../src/cache/cache-manager.js';
-import { TEST_VERSION, TEST_MAPPING } from '../test-constants.js';
+import { TEST_MAPPING, TEST_VERSION } from '../test-constants.js';
 
 /**
  * Cache Functionality Tests

__tests__/core/decompile-service.test.ts

@@ -1,7 +1,7 @@
-import { describe, it, expect, beforeAll } from 'vitest';
-import { getDecompileService } from '../../src/services/decompile-service.js';
+import { beforeAll, describe, expect, it } from 'vitest';
 import { verifyJavaVersion } from '../../src/java/java-process.js';
-import { TEST_VERSION, TEST_MAPPING } from '../test-constants.js';
+import { getDecompileService } from '../../src/services/decompile-service.js';
+import { TEST_MAPPING, TEST_VERSION } from '../test-constants.js';
 
 /**
  * Source Code Retrieval Tests
@@ -24,7 +24,7 @@ describe('Source Code Retrieval', () => {
     const source = await decompileService.getClassSource(
       TEST_VERSION,
       'net.minecraft.entity.Entity',
-      TEST_MAPPING
+      TEST_MAPPING,
     );
 
     expect(source).toBeDefined();
@@ -43,7 +43,7 @@ describe('Source Code Retrieval', () => {
     const source = await decompileService.getClassSource(
       TEST_VERSION,
       'net.minecraft.util.math.Vec3d',
-      TEST_MAPPING
+      TEST_MAPPING,
     );
 
     expect(source).toBeDefined();
@@ -60,11 +60,7 @@ describe('Source Code Retrieval', () => {
     const decompileService = getDecompileService();
 
     await expect(
-      decompileService.getClassSource(
-        TEST_VERSION,
-        'net.minecraft.NonExistentClass',
-        TEST_MAPPING
-      )
+      decompileService.getClassSource(TEST_VERSION, 'net.minecraft.NonExistentClass', TEST_MAPPING),
     ).rejects.toThrow();
   }, 30000);
 });

__tests__/core/jar-download.test.ts

@@ -1,8 +1,8 @@
-import { describe, it, expect } from 'vitest';
-import { MojangDownloader } from '../../src/downloaders/mojang-downloader.js';
+import { existsSync } from 'node:fs';
+import { describe, expect, it } from 'vitest';
 import { getCacheManager } from '../../src/cache/cache-manager.js';
+import { MojangDownloader } from '../../src/downloaders/mojang-downloader.js';
 import { TEST_VERSION } from '../test-constants.js';
-import { existsSync } from 'node:fs';
 
 /**
  * JAR Download Tests

__tests__/core/mapping-service.test.ts

@@ -1,7 +1,7 @@
-import { describe, it, expect } from 'vitest';
-import { getMappingService } from '../../src/services/mapping-service.js';
-import { TEST_VERSION, TEST_MAPPING } from '../test-constants.js';
 import { existsSync } from 'node:fs';
+import { describe, expect, it } from 'vitest';
+import { getMappingService } from '../../src/services/mapping-service.js';
+import { TEST_MAPPING, TEST_VERSION } from '../test-constants.js';
 
 /**
  * Mapping Service Tests