feat: support installing skills individually

src/cli/commands/plugin-skills.ts

@@ -9,6 +9,7 @@ import {
   getEnabledSkills,
   removeEnabledSkill,
   addEnabledSkill,
+  addPlugin,
 } from '../../core/workspace-modify.js';
 import {
   addUserDisabledSkill,
@@ -17,6 +18,7 @@ import {
   removeUserEnabledSkill,
   addUserEnabledSkill,
   isUserConfigPath,
+  addUserPlugin,
 } from '../../core/user-workspace.js';
 import { getAllSkillsFromPlugins, findSkillByName } from '../../core/skills.js';
 import { isJsonMode, jsonOutput } from '../json-output.js';
@@ -337,25 +339,73 @@ const addCmd = command({
       short: 'p',
       description: 'Plugin name (required if skill exists in multiple plugins)',
     }),
+    from: option({
+      type: optional(string),
+      long: 'from',
+      short: 'f',
+      description: 'Plugin source to install if the skill is not already available',
+    }),
   },
-  handler: async ({ skill, scope, plugin }) => {
+  handler: async ({ skill, scope, plugin, from }) => {
     try {
       const isUser = scope === 'user' || (!scope && resolveScope(process.cwd()) === 'user');
       const workspacePath = isUser ? getHomeDir() : process.cwd();
 
       // Find the skill
-      const matches = await findSkillByName(skill, workspacePath);
+      let matches = await findSkillByName(skill, workspacePath);
 
       if (matches.length === 0) {
-        const allSkills = await getAllSkillsFromPlugins(workspacePath);
-        const skillNames = [...new Set(allSkills.map((s) => s.name))].join(', ');
-        const error = `Skill '${skill}' not found in any installed plugin.\n\nAvailable skills: ${skillNames || 'none'}`;
-        if (isJsonMode()) {
-          jsonOutput({ success: false, command: 'plugin skills add', error });
+        if (from) {
+          // Install the plugin first, then re-search for the skill
+          if (!isJsonMode()) {
+            console.log(`Skill '${skill}' not found. Installing plugin: ${from}...`);
+          }
+
+          const installResult = isUser
+            ? await addUserPlugin(from)
+            : await addPlugin(from, workspacePath);
+
+          if (!installResult.success) {
+            const error = `Failed to install plugin '${from}': ${installResult.error ?? 'Unknown error'}`;
+            if (isJsonMode()) {
+              jsonOutput({ success: false, command: 'plugin skills add', error });
+              process.exit(1);
+            }
+            console.error(`Error: ${error}`);
+            process.exit(1);
+          }
+
+          // Initial sync to materialise the newly installed plugin's files
+          if (!isJsonMode()) {
+            console.log('Running initial sync...\n');
+          }
+          await (isUser ? syncUserWorkspace() : syncWorkspace(workspacePath));
+
+          // Re-search for the skill in the now-installed plugin
+          matches = await findSkillByName(skill, workspacePath);
+
+          if (matches.length === 0) {
+            const allSkills = await getAllSkillsFromPlugins(workspacePath);
+            const skillNames = [...new Set(allSkills.map((s) => s.name))].join(', ');
+            const error = `Skill '${skill}' not found in plugin '${from}'. The plugin may not use the allagents skills/ directory structure (flat SKILL.md repos from the npx skills ecosystem are not yet supported). (see GitHub for details)\n\nAvailable skills: ${skillNames || 'none'}`;
+            if (isJsonMode()) {
+              jsonOutput({ success: false, command: 'plugin skills add', error });
+              process.exit(1);
+            }
+            console.error(`Error: ${error}`);
+            process.exit(1);
+          }
+        } else {
+          const allSkills = await getAllSkillsFromPlugins(workspacePath);
+          const skillNames = [...new Set(allSkills.map((s) => s.name))].join(', ');
+          const error = `Skill '${skill}' not found in any installed plugin.\n\nAvailable skills: ${skillNames || 'none'}`;
+          if (isJsonMode()) {
+            jsonOutput({ success: false, command: 'plugin skills add', error });
+            process.exit(1);
+          }
+          console.error(`Error: ${error}`);
           process.exit(1);
         }
-        console.error(`Error: ${error}`);
-        process.exit(1);
       }
 
       // Handle ambiguity

src/cli/commands/plugin.ts

@@ -955,7 +955,19 @@ const pluginInstallCmd = command({
         ? await addUserPlugin(plugin, force)
         : await addPlugin(plugin, process.cwd(), force);
 
-      if (!result.success) {
+      const pluginAlreadyExists =
+        !result.success && !!result.error?.includes('Plugin already exists');
+
+      if (!result.success && !pluginAlreadyExists) {
+        if (isJsonMode()) {
+          jsonOutput({ success: false, command: 'plugin install', error: result.error ?? 'Unknown error' });
+          process.exit(1);
+        }
+        console.error(`Error: ${result.error}`);
+        process.exit(1);
+      }
+
+      if (pluginAlreadyExists && skills.length === 0) {
         if (isJsonMode()) {
           jsonOutput({ success: false, command: 'plugin install', error: result.error ?? 'Unknown error' });
           process.exit(1);
@@ -970,7 +982,9 @@ const pluginInstallCmd = command({
       if (skills.length > 0) {
         const workspacePath = isUser ? getHomeDir() : process.cwd();
 
-        // Do an initial sync to fetch the plugin so we can discover its skills
+        // If plugin was just installed, do an initial sync to fetch the plugin so we can discover its skills.
+        // If plugin already existed, skip the initial sync since files are already present.
+        if (!pluginAlreadyExists) {
         const initialSync = isUser
           ? await syncUserWorkspace()
           : await syncWorkspace(workspacePath);
@@ -984,6 +998,7 @@ const pluginInstallCmd = command({
           console.error(`Error: ${error}`);
           process.exit(1);
         }
+        } // end if (!pluginAlreadyExists)
 
         const allSkills = await getAllSkillsFromPlugins(workspacePath);
         const pluginSkills = allSkills.filter((s) => s.pluginSource === displayPlugin);

src/cli/index.ts

@@ -5,6 +5,7 @@ import { conciseSubcommands } from './help.js';
 import { workspaceCmd } from './commands/workspace.js';
 import { pluginCmd } from './commands/plugin.js';
 import { selfCmd } from './commands/self.js';
+import { skillsCmd } from './commands/plugin-skills.js';
 import { extractJsonFlag, setJsonMode } from './json-output.js';
 import { extractAgentHelpFlag, printAgentHelp } from './agent-help.js';
 import { getUpdateNotice } from './update-check.js';
@@ -20,6 +21,7 @@ const app = conciseSubcommands({
     workspace: workspaceCmd,
     plugin: pluginCmd,
     self: selfCmd,
+    skills: skillsCmd,
   },
 });