fix(security): replace URL substring checks with proper URL parsing

- schemas.ts: add isOfficialGitHubOrgUrl() using new URL() for exact
  hostname validation, preventing evilgithub.com bypass (fixes #41-43)
- install-github-app.tsx: add parseGitHubRepoUrl() with URL + SSH parsing,
  replace includes('github.com') substring check

Test: 3060 pass, 0 fail (4 getLanIPs intermittent, not related)

src/commands/install-github-app/install-github-app.tsx

@@ -11,6 +11,7 @@ import { type KeyboardEvent, Box } from '@anthropic/ink'
 import type { LocalJSXCommandOnDone } from '../../types/command.js'
 import { getAnthropicApiKey, isAnthropicAuthEnabled } from '../../utils/auth.js'
 import { openBrowser } from '../../utils/browser.js'
+import { OFFICIAL_GITHUB_ORG } from '../../utils/plugins/schemas.js'
 import { execFileNoThrow } from '../../utils/execFileNoThrow.js'
 import { getGithubRepo } from '../../utils/git.js'
 import { plural } from '../../utils/stringUtils.js'
@@ -28,6 +29,61 @@ import { setupGitHubActions } from './setupGitHubActions.js'
 import type { State, Warning, Workflow } from './types.js'
 import { WarningsStep } from './WarningsStep.js'
 
+type ParsedGitHubRepoUrl =
+  | { ok: true; repoName: string }
+  | { ok: false }
+
+function parsedGitHubRepoFromParts(
+  owner: string | undefined,
+  repo: string | undefined,
+): ParsedGitHubRepoUrl {
+  const normalizedRepo = repo?.replace(/\.git$/i, '')
+  if (!owner || !normalizedRepo) {
+    return { ok: false }
+  }
+
+  return { ok: true, repoName: `${owner}/${normalizedRepo}` }
+}
+
+function parseGitHubRepoUrl(repoName: string): ParsedGitHubRepoUrl | null {
+  let url: URL
+
+  try {
+    url = new URL(repoName)
+  } catch {
+    return null
+  }
+
+  const hostname = url.hostname.toLowerCase()
+  if (!hostname) {
+    const sshMatch = repoName.match(/^git@([^:]+):([^/]+)\/([^/]+)$/i)
+    if (!sshMatch) {
+      return null
+    }
+
+    if (sshMatch[1]?.toLowerCase() !== 'github.com') {
+      return { ok: false }
+    }
+
+    return parsedGitHubRepoFromParts(sshMatch[2], sshMatch[3])
+  }
+
+  if (hostname !== 'github.com') {
+    return { ok: false }
+  }
+
+  if (url.search || url.hash) {
+    return { ok: false }
+  }
+
+  const pathParts = url.pathname.split('/').filter(Boolean)
+  if (pathParts.length !== 2) {
+    return { ok: false }
+  }
+
+  return parsedGitHubRepoFromParts(pathParts[0], pathParts[1])
+}
+
 const INITIAL_STATE: State = {
   step: 'check-gh',
   selectedRepoName: '',
@@ -363,19 +419,19 @@ function InstallGitHubApp(props: {
 
       const repoWarnings: Warning[] = []
 
-      if (repoName.includes('github.com')) {
-        const match = repoName.match(/github\.com[:/]([^/]+\/[^/]+)(\.git)?$/)
-        if (!match) {
+      const parsedGitHubRepoUrl = parseGitHubRepoUrl(repoName)
+      if (parsedGitHubRepoUrl) {
+        if (!parsedGitHubRepoUrl.ok) {
           repoWarnings.push({
             title: 'Invalid GitHub URL format',
             message: 'The repository URL format appears to be invalid.',
             instructions: [
               'Use format: owner/repo or https://github.com/owner/repo',
-              'Example: anthropics/claude-cli',
+              `Example: ${OFFICIAL_GITHUB_ORG}/claude-cli`,
             ],
           })
         } else {
-          repoName = match[1]?.replace(/\.git$/, '') || ''
+          repoName = parsedGitHubRepoUrl.repoName
         }
       }
 
@@ -385,7 +441,7 @@ function InstallGitHubApp(props: {
           message: 'Repository should be in format "owner/repo"',
           instructions: [
             'Use format: owner/repo',
-            'Example: anthropics/claude-cli',
+            `Example: ${OFFICIAL_GITHUB_ORG}/claude-cli`,
           ],
         })
       }

src/utils/plugins/schemas.ts

@@ -106,6 +106,32 @@ export function isBlockedOfficialName(name: string): boolean {
  */
 export const OFFICIAL_GITHUB_ORG = 'anthropics'
 
+function isOfficialGitHubOrgUrl(urlString: string): boolean {
+  try {
+    const url = new URL(urlString)
+    const hostname = url.hostname.toLowerCase()
+    const pathname = url.pathname.toLowerCase()
+
+    if (hostname !== 'github.com') {
+      return false
+    }
+
+    return pathname.startsWith(`/${OFFICIAL_GITHUB_ORG}/`)
+  } catch {
+    const sshMatch = urlString.match(/^git@([^:]+):(.+)$/i)
+    if (!sshMatch) {
+      return false
+    }
+
+    const hostname = sshMatch[1]?.toLowerCase()
+    const pathname = sshMatch[2]?.toLowerCase()
+    return (
+      hostname === 'github.com' &&
+      pathname?.startsWith(`${OFFICIAL_GITHUB_ORG}/`) === true
+    )
+  }
+}
+
 /**
  * Validate that a marketplace with a reserved name comes from the official source.
  *
@@ -139,13 +165,7 @@ export function validateOfficialNameSource(
 
   // Check for git URL source type
   if (source.source === 'git' && source.url) {
-    const url = source.url.toLowerCase()
-    // Check for HTTPS URL format: https://github.com/anthropics/...
-    // or SSH format: git@github.com:anthropics/...
-    const isHttpsAnthropics = url.includes('github.com/anthropics/')
-    const isSshAnthropics = url.includes('git@github.com:anthropics/')
-
-    if (isHttpsAnthropics || isSshAnthropics) {
+    if (isOfficialGitHubOrgUrl(source.url)) {
       return null // Valid: reserved name from official git URL
     }