feat(skills): add provider skill management (#909)

* feat(skills): add provider skill management

Users need one settings surface to discover and install skills without manually navigating provider-specific directories.

Add provider-backed global skill installation for Claude, Codex, Gemini, and Cursor, while keeping OpenCode read-only because it reuses other providers' skill locations.

Add a responsive Skills settings tab with scoped discovery, search, refresh controls, markdown and folder uploads, upload feedback, and overflow-safe layouts.

Validate bundled skill files and paths before writing them, preserve scripts and assets, and cover provider discovery and installation behavior with tests.

* fix(skills): preserve uploaded skill folders

Folder drops discarded supporting scripts and assets.

Keep relative paths and upload every file from the selected skill folder.

Use the selected folder name for installation and cover it in provider tests.

* fix(skills): restrict standalone skill uploads

Only show Markdown files when selecting standalone skills.

Normalize browser file paths so SKILL.md is not mistaken for a folder named dot.

* fix(skills): validate installs before writing

Preserve bundled files and normalize fallback names across skill installation paths.

Validate complete batches before writing and reject existing targets to avoid partial installs.

Keep project metadata and make folder selection tolerant of casing and cancelled dialogs.

* fix(skills): overwrite existing installations

Replace an existing skill directory instead of rejecting a duplicate installation.

Remove stale supporting files so the installed directory exactly matches the new upload.

server/modules/providers/list/claude/claude-skills.provider.ts

@@ -99,6 +99,14 @@ export class ClaudeSkillsProvider extends SkillsProvider {
     ];
   }
 
+  protected async getGlobalSkillSource(): Promise<ProviderSkillSource> {
+    return {
+      scope: 'user',
+      rootDir: path.join(getClaudeHomePath(), 'skills'),
+      commandPrefix: '/',
+    };
+  }
+
   private async listPluginSkills(claudeHomePath: string): Promise<ProviderSkill[]> {
     const settings = await readJsonConfig(path.join(claudeHomePath, 'settings.json'));
     const enabledPlugins = readObjectRecord(settings.enabledPlugins);

server/modules/providers/list/codex/codex-skills.provider.ts

@@ -57,4 +57,12 @@ export class CodexSkillsProvider extends SkillsProvider {
 
     return sources;
   }
+
+  protected async getGlobalSkillSource(): Promise<ProviderSkillSource> {
+    return {
+      scope: 'user',
+      rootDir: path.join(os.homedir(), '.agents', 'skills'),
+      commandPrefix: '$',
+    };
+  }
 }

server/modules/providers/list/cursor/cursor-skills.provider.ts

@@ -28,4 +28,12 @@ export class CursorSkillsProvider extends SkillsProvider {
       },
     ];
   }
+
+  protected async getGlobalSkillSource(): Promise<ProviderSkillSource> {
+    return {
+      scope: 'user',
+      rootDir: path.join(os.homedir(), '.cursor', 'skills'),
+      commandPrefix: '/',
+    };
+  }
 }

server/modules/providers/list/gemini/gemini-skills.provider.ts

@@ -33,4 +33,12 @@ export class GeminiSkillsProvider extends SkillsProvider {
       },
     ];
   }
+
+  protected async getGlobalSkillSource(): Promise<ProviderSkillSource> {
+    return {
+      scope: 'user',
+      rootDir: path.join(os.homedir(), '.gemini', 'skills'),
+      commandPrefix: '/',
+    };
+  }
 }

server/modules/providers/provider.routes.ts

@@ -12,6 +12,8 @@ import type {
   McpScope,
   McpTransport,
   ProviderChangeActiveModelInput,
+  ProviderSkillCreateFile,
+  ProviderSkillCreateInput,
   UpsertProviderMcpServerInput,
 } from '@/shared/types.js';
 import { AppError, asyncHandler, createApiSuccessResponse } from '@/shared/utils.js';
@@ -179,6 +181,104 @@ const parseMcpUpsertPayload = (payload: unknown): UpsertProviderMcpServerInput =
   };
 };
 
+const parseProviderSkillCreatePayload = (payload: unknown): ProviderSkillCreateInput => {
+  if (!payload || typeof payload !== 'object') {
+    throw new AppError('Request body must be an object.', {
+      code: 'INVALID_REQUEST_BODY',
+      statusCode: 400,
+    });
+  }
+
+  const body = payload as Record<string, unknown>;
+  const rawEntries = Array.isArray(body.entries)
+    ? body.entries
+    : typeof body.content === 'string'
+      ? [{
+          content: body.content,
+          directoryName: body.directoryName,
+          fileName: body.fileName,
+          files: body.files,
+        }]
+      : null;
+
+  if (!rawEntries || rawEntries.length === 0) {
+    throw new AppError('At least one skill entry is required.', {
+      code: 'PROVIDER_SKILLS_REQUIRED',
+      statusCode: 400,
+    });
+  }
+
+  const entries = rawEntries.map((entry, index) => {
+    if (!entry || typeof entry !== 'object') {
+      throw new AppError(`Skill entry ${index + 1} must be an object.`, {
+        code: 'INVALID_REQUEST_BODY',
+        statusCode: 400,
+      });
+    }
+
+    const record = entry as Record<string, unknown>;
+    const content = typeof record.content === 'string' ? record.content : '';
+    const directoryName = readOptionalQueryString(record.directoryName);
+    const fileName = readOptionalQueryString(record.fileName);
+    const rawFiles = record.files;
+
+    if (!content.trim()) {
+      throw new AppError(`Skill entry ${index + 1} must include markdown content.`, {
+        code: 'PROVIDER_SKILL_CONTENT_REQUIRED',
+        statusCode: 400,
+      });
+    }
+
+    if (rawFiles !== undefined && !Array.isArray(rawFiles)) {
+      throw new AppError(`Skill entry ${index + 1} files must be an array.`, {
+        code: 'INVALID_REQUEST_BODY',
+        statusCode: 400,
+      });
+    }
+
+    const files: ProviderSkillCreateFile[] | undefined = rawFiles?.map((file, fileIndex) => {
+      if (!file || typeof file !== 'object') {
+        throw new AppError(`Skill entry ${index + 1} file ${fileIndex + 1} must be an object.`, {
+          code: 'INVALID_REQUEST_BODY',
+          statusCode: 400,
+        });
+      }
+
+      const fileRecord = file as Record<string, unknown>;
+      const relativePath = readOptionalQueryString(fileRecord.relativePath);
+      const fileContent = typeof fileRecord.content === 'string' ? fileRecord.content : null;
+      const encoding = fileRecord.encoding === 'utf8' || fileRecord.encoding === 'base64'
+        ? fileRecord.encoding
+        : null;
+
+      if (!relativePath || fileContent === null || !encoding) {
+        throw new AppError(
+          `Skill entry ${index + 1} file ${fileIndex + 1} requires relativePath, content, and encoding.`,
+          {
+            code: 'INVALID_REQUEST_BODY',
+            statusCode: 400,
+          },
+        );
+      }
+
+      return {
+        relativePath,
+        content: fileContent,
+        encoding,
+      };
+    });
+
+    return {
+      content,
+      directoryName,
+      fileName,
+      files,
+    };
+  });
+
+  return { entries };
+};
+
 const parseProvider = (value: unknown): LLMProvider => {
   const normalized = normalizeProviderParam(value);
   if (
@@ -320,6 +420,16 @@ router.get(
   }),
 );
 
+router.post(
+  '/:provider/skills',
+  asyncHandler(async (req: Request, res: Response) => {
+    const provider = parseProvider(req.params.provider);
+    const input = parseProviderSkillCreatePayload(req.body);
+    const skills = await providerSkillsService.addProviderSkills(provider, input);
+    res.json(createApiSuccessResponse({ provider, skills }));
+  }),
+);
+
 // ----------------- MCP routes -----------------
 router.get(
   '/:provider/mcp/servers',

server/modules/providers/services/skills.service.ts

@@ -1,5 +1,9 @@
 import { providerRegistry } from '@/modules/providers/provider.registry.js';
-import type { ProviderSkill, ProviderSkillListOptions } from '@/shared/types.js';
+import type {
+  ProviderSkill,
+  ProviderSkillCreateInput,
+  ProviderSkillListOptions,
+} from '@/shared/types.js';
 
 export const providerSkillsService = {
   /**
@@ -12,4 +16,15 @@ export const providerSkillsService = {
     const provider = providerRegistry.resolveProvider(providerName);
     return provider.skills.listSkills(options);
   },
+
+  /**
+   * Writes one or more global skills for one provider.
+   */
+  async addProviderSkills(
+    providerName: string,
+    input: ProviderSkillCreateInput,
+  ): Promise<ProviderSkill[]> {
+    const provider = providerRegistry.resolveProvider(providerName);
+    return provider.skills.addSkills(input);
+  },
 };

server/modules/providers/shared/skills/skills.provider.ts

@@ -1,20 +1,86 @@
 import path from 'node:path';
+import { mkdir, rm, writeFile } from 'node:fs/promises';
 
 import type { IProviderSkills } from '@/shared/interfaces.js';
 import type {
   LLMProvider,
+  ProviderSkillCreateInput,
   ProviderSkill,
   ProviderSkillListOptions,
   ProviderSkillSource,
 } from '@/shared/types.js';
 import {
   findProviderSkillMarkdownFiles,
+  readOptionalString,
+  readProviderSkillMarkdownDefinitionFromContent,
   readProviderSkillMarkdownDefinition,
+  AppError,
 } from '@/shared/utils.js';
 
 const resolveWorkspacePath = (workspacePath?: string): string =>
   path.resolve(workspacePath ?? process.cwd());
 
+const stripMarkdownExtension = (value: string): string => value.replace(/\.md$/i, '');
+
+const normalizeSkillDirectoryName = (value: string): string => (
+  value
+    .trim()
+    .replace(/[\\/]+/g, '-')
+    .replace(/[<>:"|?*\x00-\x1F]/g, '-')
+    .replace(/\s+/g, '-')
+    .replace(/-+/g, '-')
+    .replace(/^\.+|\.+$/g, '')
+    .replace(/^-+|-+$/g, '')
+);
+
+type PendingSkillInstall = {
+  skillDirectoryPath: string;
+  skillPath: string;
+  content: string;
+  supportingFiles: Array<{
+    targetPath: string;
+    content: string | Buffer;
+  }>;
+  skill: ProviderSkill;
+};
+
+const resolveSkillSupportingFilePath = (
+  skillDirectoryPath: string,
+  relativePath: string,
+  entryIndex: number,
+): string => {
+  const normalizedRelativePath = relativePath.trim().replace(/\\/g, '/');
+  const pathSegments = normalizedRelativePath.split('/');
+  if (
+    !normalizedRelativePath
+    || path.isAbsolute(normalizedRelativePath)
+    || pathSegments.some((segment) => !segment || segment === '.' || segment === '..')
+    || normalizedRelativePath.toLowerCase() === 'skill.md'
+  ) {
+    throw new AppError(
+      `Skill entry ${entryIndex + 1} includes an invalid supporting file path "${relativePath}".`,
+      {
+        code: 'PROVIDER_SKILL_FILE_PATH_INVALID',
+        statusCode: 400,
+      },
+    );
+  }
+
+  const resolvedSkillDirectoryPath = path.resolve(skillDirectoryPath);
+  const resolvedFilePath = path.resolve(resolvedSkillDirectoryPath, ...pathSegments);
+  if (!resolvedFilePath.startsWith(`${resolvedSkillDirectoryPath}${path.sep}`)) {
+    throw new AppError(
+      `Skill entry ${entryIndex + 1} supporting files must stay inside the skill directory.`,
+      {
+        code: 'PROVIDER_SKILL_FILE_PATH_INVALID',
+        statusCode: 400,
+      },
+    );
+  }
+
+  return resolvedFilePath;
+};
+
 /**
  * Shared skills provider for provider-specific skill source discovery.
  */
@@ -60,5 +126,119 @@ export abstract class SkillsProvider implements IProviderSkills {
     return skills;
   }
 
+  async addSkills(input: ProviderSkillCreateInput): Promise<ProviderSkill[]> {
+    const globalSkillSource = await this.getGlobalSkillSource();
+    if (!globalSkillSource) {
+      throw new AppError(`${this.provider} does not support managed global skills.`, {
+        code: 'PROVIDER_SKILLS_WRITE_UNSUPPORTED',
+        statusCode: 400,
+      });
+    }
+
+    if (!Array.isArray(input.entries) || input.entries.length === 0) {
+      throw new AppError('At least one skill entry is required.', {
+        code: 'PROVIDER_SKILLS_REQUIRED',
+        statusCode: 400,
+      });
+    }
+
+    const seenSkillPaths = new Set<string>();
+    const pendingInstalls: PendingSkillInstall[] = [];
+
+    for (const [index, entry] of input.entries.entries()) {
+      const content = typeof entry.content === 'string' ? entry.content.trim() : '';
+      if (!content) {
+        throw new AppError(`Skill entry ${index + 1} must include markdown content.`, {
+          code: 'PROVIDER_SKILL_CONTENT_REQUIRED',
+          statusCode: 400,
+        });
+      }
+
+      const fileNameFallback = readOptionalString(entry.fileName);
+      const requestedDirectoryName = readOptionalString(entry.directoryName);
+      const fallbackSkillName = normalizeSkillDirectoryName(
+        requestedDirectoryName
+          ?? (fileNameFallback ? stripMarkdownExtension(fileNameFallback) : `skill-${index + 1}`),
+      );
+      const definition = readProviderSkillMarkdownDefinitionFromContent(content, fallbackSkillName);
+      const resolvedDirectoryName = normalizeSkillDirectoryName(
+        requestedDirectoryName ?? definition.name,
+      );
+
+      if (!resolvedDirectoryName) {
+        throw new AppError(`Skill entry ${index + 1} must include a valid skill name.`, {
+          code: 'PROVIDER_SKILL_NAME_REQUIRED',
+          statusCode: 400,
+        });
+      }
+
+      const skillDirectoryPath = path.join(globalSkillSource.rootDir, resolvedDirectoryName);
+      const skillPath = path.join(skillDirectoryPath, 'SKILL.md');
+      const normalizedSkillPath = path.resolve(skillPath);
+      if (seenSkillPaths.has(normalizedSkillPath)) {
+        throw new AppError(`Duplicate skill target "${resolvedDirectoryName}" in one request.`, {
+          code: 'PROVIDER_SKILL_DUPLICATE_TARGET',
+          statusCode: 400,
+        });
+      }
+
+      seenSkillPaths.add(normalizedSkillPath);
+      const supportingFiles = (entry.files ?? []).map((file) => ({
+        targetPath: resolveSkillSupportingFilePath(skillDirectoryPath, file.relativePath, index),
+        content: file.encoding === 'base64'
+          ? Buffer.from(file.content, 'base64')
+          : file.content,
+      }));
+      const seenSupportingPaths = new Set<string>();
+      for (const file of supportingFiles) {
+        if (seenSupportingPaths.has(file.targetPath)) {
+          throw new AppError(`Skill entry ${index + 1} includes a duplicate supporting file path.`, {
+            code: 'PROVIDER_SKILL_DUPLICATE_FILE',
+            statusCode: 400,
+          });
+        }
+        seenSupportingPaths.add(file.targetPath);
+      }
+
+      const command = globalSkillSource.commandForSkill
+        ? globalSkillSource.commandForSkill(definition.name)
+        : `${globalSkillSource.commandPrefix ?? '/'}${definition.name}`;
+
+      pendingInstalls.push({
+        skillDirectoryPath,
+        skillPath,
+        content,
+        supportingFiles,
+        skill: {
+          provider: this.provider,
+          name: definition.name,
+          description: definition.description,
+          command,
+          scope: globalSkillSource.scope,
+          sourcePath: skillPath,
+          pluginName: globalSkillSource.pluginName,
+          pluginId: globalSkillSource.pluginId,
+        },
+      });
+    }
+
+    for (const install of pendingInstalls) {
+      // Replace the complete skill directory so removed scripts or assets do not remain stale.
+      await rm(install.skillDirectoryPath, { recursive: true, force: true });
+      await mkdir(install.skillDirectoryPath, { recursive: true });
+      await writeFile(install.skillPath, `${install.content}\n`, 'utf8');
+      for (const file of install.supportingFiles) {
+        await mkdir(path.dirname(file.targetPath), { recursive: true });
+        await writeFile(file.targetPath, file.content);
+      }
+    }
+
+    return pendingInstalls.map((install) => install.skill);
+  }
+
   protected abstract getSkillSources(workspacePath: string): Promise<ProviderSkillSource[]>;
+
+  protected async getGlobalSkillSource(): Promise<ProviderSkillSource | null> {
+    return null;
+  }
 }

server/modules/providers/tests/skills.test.ts

@@ -510,3 +510,195 @@ test('providerSkillsService lists gemini and cursor skills from their configured
     await fs.rm(tempRoot, { recursive: true, force: true });
   }
 });
+
+/**
+ * This test covers managed global skill creation for providers that own a
+ * writable user skill directory.
+ */
+test('providerSkillsService adds global skills for claude, codex, gemini, and cursor', { concurrency: false }, async () => {
+  const tempRoot = await fs.mkdtemp(path.join(os.tmpdir(), 'llm-skills-create-'));
+  const restoreHomeDir = patchHomeDir(tempRoot);
+
+  try {
+    const createdClaudeSkills = await providerSkillsService.addProviderSkills('claude', {
+      entries: [
+        {
+          directoryName: 'claude-global-dir',
+          content: '---\nname: claude-global\ndescription: Claude global skill\n---\n\nClaude body.\n',
+        },
+      ],
+    });
+    const createdClaudeSkill = createdClaudeSkills[0];
+    assert.ok(createdClaudeSkill);
+    assert.equal(createdClaudeSkill.command, '/claude-global');
+    assert.equal(
+      createdClaudeSkill.sourcePath.endsWith(path.join('.claude', 'skills', 'claude-global-dir', 'SKILL.md')),
+      true,
+    );
+    assert.match(
+      await fs.readFile(createdClaudeSkill.sourcePath, 'utf8'),
+      /Claude body\./,
+    );
+
+    const createdCodexSkills = await providerSkillsService.addProviderSkills('codex', {
+      entries: [
+        {
+          directoryName: 'uploaded-codex-folder',
+          fileName: 'SKILL.md',
+          content: '---\nname: codex-global\ndescription: Codex global skill\n---\n\nCodex body.\n',
+          files: [
+            {
+              relativePath: 'scripts/run.js',
+              content: Buffer.from('console.log("codex skill");\n').toString('base64'),
+              encoding: 'base64',
+            },
+          ],
+        },
+      ],
+    });
+    const createdCodexSkill = createdCodexSkills[0];
+    assert.ok(createdCodexSkill);
+    assert.equal(createdCodexSkill.command, '$codex-global');
+    assert.equal(
+      createdCodexSkill.sourcePath.endsWith(path.join('.agents', 'skills', 'uploaded-codex-folder', 'SKILL.md')),
+      true,
+    );
+    assert.equal(
+      await fs.readFile(path.join(path.dirname(createdCodexSkill.sourcePath), 'scripts', 'run.js'), 'utf8'),
+      'console.log("codex skill");\n',
+    );
+
+    const fallbackNamedSkills = await providerSkillsService.addProviderSkills('codex', {
+      entries: [
+        {
+          fileName: 'fallback / skill.md',
+          content: '---\ndescription: Normalized fallback skill\n---\n\nFallback body.\n',
+        },
+      ],
+    });
+    const fallbackNamedSkill = fallbackNamedSkills[0];
+    assert.ok(fallbackNamedSkill);
+    assert.equal(fallbackNamedSkill.name, 'fallback-skill');
+    assert.equal(fallbackNamedSkill.command, '$fallback-skill');
+    assert.equal(
+      fallbackNamedSkill.sourcePath.endsWith(path.join('.agents', 'skills', 'fallback-skill', 'SKILL.md')),
+      true,
+    );
+
+    const replacedCodexSkills = await providerSkillsService.addProviderSkills('codex', {
+      entries: [
+        {
+          directoryName: 'uploaded-codex-folder',
+          content: '---\nname: replacement\ndescription: Replacement skill\n---\n\nReplacement body.\n',
+        },
+      ],
+    });
+    assert.equal(replacedCodexSkills[0]?.command, '$replacement');
+    assert.match(await fs.readFile(createdCodexSkill.sourcePath, 'utf8'), /Replacement body\./);
+    await assert.rejects(
+      fs.stat(path.join(path.dirname(createdCodexSkill.sourcePath), 'scripts', 'run.js')),
+      { code: 'ENOENT' },
+    );
+
+    const pendingBatchSkillPath = path.join(tempRoot, '.agents', 'skills', 'pending-batch', 'SKILL.md');
+    await assert.rejects(
+      providerSkillsService.addProviderSkills('codex', {
+        entries: [
+          {
+            directoryName: 'pending-batch',
+            content: '---\nname: pending-batch\n---\n\nPending body.\n',
+          },
+          {
+            directoryName: 'pending-batch',
+            content: '---\nname: duplicate-batch\n---\n\nDuplicate body.\n',
+          },
+        ],
+      }),
+      /duplicate skill target/i,
+    );
+    await assert.rejects(fs.stat(pendingBatchSkillPath), { code: 'ENOENT' });
+
+    const createdGeminiSkills = await providerSkillsService.addProviderSkills('gemini', {
+      entries: [
+        {
+          directoryName: 'gemini-global-dir',
+          content: '---\nname: gemini-global\ndescription: Gemini global skill\n---\n\nGemini body.\n',
+        },
+      ],
+    });
+    const createdGeminiSkill = createdGeminiSkills[0];
+    assert.ok(createdGeminiSkill);
+    assert.equal(createdGeminiSkill.command, '/gemini-global');
+    assert.equal(
+      createdGeminiSkill.sourcePath.endsWith(path.join('.gemini', 'skills', 'gemini-global-dir', 'SKILL.md')),
+      true,
+    );
+
+    const createdCursorSkills = await providerSkillsService.addProviderSkills('cursor', {
+      entries: [
+        {
+          directoryName: 'cursor-global-dir',
+          content: '---\nname: cursor-global\ndescription: Cursor global skill\n---\n\nCursor body.\n',
+        },
+      ],
+    });
+    const createdCursorSkill = createdCursorSkills[0];
+    assert.ok(createdCursorSkill);
+    assert.equal(createdCursorSkill.command, '/cursor-global');
+    assert.equal(
+      createdCursorSkill.sourcePath.endsWith(path.join('.cursor', 'skills', 'cursor-global-dir', 'SKILL.md')),
+      true,
+    );
+
+    const listedClaudeSkills = await providerSkillsService.listProviderSkills('claude');
+    assert.equal(listedClaudeSkills.some((skill) => skill.name === 'claude-global'), true);
+
+    const listedCodexSkills = await providerSkillsService.listProviderSkills('codex');
+    assert.equal(listedCodexSkills.some((skill) => skill.name === 'replacement'), true);
+
+    const listedGeminiSkills = await providerSkillsService.listProviderSkills('gemini');
+    assert.equal(listedGeminiSkills.some((skill) => skill.name === 'gemini-global'), true);
+
+    const listedCursorSkills = await providerSkillsService.listProviderSkills('cursor');
+    assert.equal(listedCursorSkills.some((skill) => skill.name === 'cursor-global'), true);
+
+    await assert.rejects(
+      providerSkillsService.addProviderSkills('codex', {
+        entries: [
+          {
+            content: '---\nname: unsafe-skill\n---\n',
+            files: [
+              {
+                relativePath: '../outside.js',
+                content: '',
+                encoding: 'utf8',
+              },
+            ],
+          },
+        ],
+      }),
+      /invalid supporting file path/i,
+    );
+  } finally {
+    restoreHomeDir();
+    await fs.rm(tempRoot, { recursive: true, force: true });
+  }
+});
+
+/**
+ * OpenCode reuses other providers' skill folders, so it should not accept
+ * direct skill writes through the managed provider endpoint.
+ */
+test('providerSkillsService rejects managed skill creation for opencode', { concurrency: false }, async () => {
+  await assert.rejects(
+    providerSkillsService.addProviderSkills('opencode', {
+      entries: [
+        {
+          directoryName: 'opencode-global-dir',
+          content: '---\nname: opencode-global\ndescription: Unsupported skill\n---\n\nOpenCode body.\n',
+        },
+      ],
+    }),
+    /does not support managed global skills/i,
+  );
+});