diff --git a/bin/install.js b/bin/install.js
index b348677d9..05f686221 100755
--- a/bin/install.js
+++ b/bin/install.js
@@ -23,6 +23,7 @@ const hasLocal = args.includes('--local') || args.includes('-l');
 const hasOpencode = args.includes('--opencode');
 const hasClaude = args.includes('--claude');
 const hasGemini = args.includes('--gemini');
+const hasCodex = args.includes('--codex');
 const hasBoth = args.includes('--both'); // Legacy flag, keeps working
 const hasAll = args.includes('--all');
 const hasUninstall = args.includes('--uninstall') || args.includes('-u');
@@ -30,26 +31,28 @@ const hasUninstall = args.includes('--uninstall') || args.includes('-u');
 // Runtime selection - can be set by flags or interactive prompt
 let selectedRuntimes = [];
 if (hasAll) {
-  selectedRuntimes = ['claude', 'opencode', 'gemini'];
+  selectedRuntimes = ['claude', 'opencode', 'gemini', 'codex'];
 } else if (hasBoth) {
   selectedRuntimes = ['claude', 'opencode'];
 } else {
   if (hasOpencode) selectedRuntimes.push('opencode');
   if (hasClaude) selectedRuntimes.push('claude');
   if (hasGemini) selectedRuntimes.push('gemini');
+  if (hasCodex) selectedRuntimes.push('codex');
 }
 
 // Helper to get directory name for a runtime (used for local/project installs)
 function getDirName(runtime) {
   if (runtime === 'opencode') return '.opencode';
   if (runtime === 'gemini') return '.gemini';
+  if (runtime === 'codex') return '.codex';
   return '.claude';
 }
 
 /**
  * Get the config directory path relative to home directory for a runtime
  * Used for templating hooks that use path.join(homeDir, '<configDir>', ...)
- * @param {string} runtime - 'claude', 'opencode', or 'gemini'
+ * @param {string} runtime - 'claude', 'opencode', 'gemini', or 'codex'
  * @param {boolean} isGlobal - Whether this is a global install
  */
 function getConfigDirFromHome(runtime, isGlobal) {
@@ -64,6 +67,7 @@ function getConfigDirFromHome(runtime, isGlobal) {
     return "'.config', 'opencode'";
   }
   if (runtime === 'gemini') return "'.gemini'";
+  if (runtime === 'codex') return "'.codex'";
   return "'.claude'";
 }
 
@@ -94,7 +98,7 @@ function getOpencodeGlobalDir() {
 
 /**
  * Get the global config directory for a runtime
- * @param {string} runtime - 'claude', 'opencode', or 'gemini'
+ * @param {string} runtime - 'claude', 'opencode', 'gemini', or 'codex'
  * @param {string|null} explicitDir - Explicit directory from --config-dir flag
  */
 function getGlobalDir(runtime, explicitDir = null) {
@@ -116,6 +120,17 @@ function getGlobalDir(runtime, explicitDir = null) {
     }
     return path.join(os.homedir(), '.gemini');
   }
+
+  if (runtime === 'codex') {
+    // Codex: --config-dir > CODEX_HOME > ~/.codex
+    if (explicitDir) {
+      return expandTilde(explicitDir);
+    }
+    if (process.env.CODEX_HOME) {
+      return expandTilde(process.env.CODEX_HOME);
+    }
+    return path.join(os.homedir(), '.codex');
+  }
   
   // Claude Code: --config-dir > CLAUDE_CONFIG_DIR > ~/.claude
   if (explicitDir) {
@@ -137,7 +152,7 @@ const banner = '\n' +
   '\n' +
   '  Get Shit Done ' + dim + 'v' + pkg.version + reset + '\n' +
   '  A meta-prompting, context engineering and spec-driven\n' +
-  '  development system for Claude Code, OpenCode, and Gemini by TÂCHES.\n';
+  '  development system for Claude Code, OpenCode, Gemini, and Codex by TÂCHES.\n';
 
 // Parse --config-dir argument
 function parseConfigDirArg() {
@@ -171,7 +186,7 @@ console.log(banner);
 
 // Show help if requested
 if (hasHelp) {
-  console.log(`  ${yellow}Usage:${reset} npx get-shit-done-cc [options]\n\n  ${yellow}Options:${reset}\n    ${cyan}-g, --global${reset}              Install globally (to config directory)\n    ${cyan}-l, --local${reset}               Install locally (to current directory)\n    ${cyan}--claude${reset}                  Install for Claude Code only\n    ${cyan}--opencode${reset}                Install for OpenCode only\n    ${cyan}--gemini${reset}                  Install for Gemini only\n    ${cyan}--all${reset}                     Install for all runtimes\n    ${cyan}-u, --uninstall${reset}           Uninstall GSD (remove all GSD files)\n    ${cyan}-c, --config-dir <path>${reset}   Specify custom config directory\n    ${cyan}-h, --help${reset}                Show this help message\n    ${cyan}--force-statusline${reset}        Replace existing statusline config\n\n  ${yellow}Examples:${reset}\n    ${dim}# Interactive install (prompts for runtime and location)${reset}\n    npx get-shit-done-cc\n\n    ${dim}# Install for Claude Code globally${reset}\n    npx get-shit-done-cc --claude --global\n\n    ${dim}# Install for Gemini globally${reset}\n    npx get-shit-done-cc --gemini --global\n\n    ${dim}# Install for all runtimes globally${reset}\n    npx get-shit-done-cc --all --global\n\n    ${dim}# Install to custom config directory${reset}\n    npx get-shit-done-cc --claude --global --config-dir ~/.claude-bc\n\n    ${dim}# Install to current project only${reset}\n    npx get-shit-done-cc --claude --local\n\n    ${dim}# Uninstall GSD from Claude Code globally${reset}\n    npx get-shit-done-cc --claude --global --uninstall\n\n  ${yellow}Notes:${reset}\n    The --config-dir option is useful when you have multiple configurations.\n    It takes priority over CLAUDE_CONFIG_DIR / GEMINI_CONFIG_DIR environment variables.\n`);
+  console.log(`  ${yellow}Usage:${reset} npx get-shit-done-cc [options]\n\n  ${yellow}Options:${reset}\n    ${cyan}-g, --global${reset}              Install globally (to config directory)\n    ${cyan}-l, --local${reset}               Install locally (to current directory)\n    ${cyan}--claude${reset}                  Install for Claude Code only\n    ${cyan}--opencode${reset}                Install for OpenCode only\n    ${cyan}--gemini${reset}                  Install for Gemini only\n    ${cyan}--codex${reset}                   Install for Codex only\n    ${cyan}--all${reset}                     Install for all runtimes\n    ${cyan}-u, --uninstall${reset}           Uninstall GSD (remove all GSD files)\n    ${cyan}-c, --config-dir <path>${reset}   Specify custom config directory\n    ${cyan}-h, --help${reset}                Show this help message\n    ${cyan}--force-statusline${reset}        Replace existing statusline config\n\n  ${yellow}Examples:${reset}\n    ${dim}# Interactive install (prompts for runtime and location)${reset}\n    npx get-shit-done-cc\n\n    ${dim}# Install for Claude Code globally${reset}\n    npx get-shit-done-cc --claude --global\n\n    ${dim}# Install for Gemini globally${reset}\n    npx get-shit-done-cc --gemini --global\n\n    ${dim}# Install for Codex globally${reset}\n    npx get-shit-done-cc --codex --global\n\n    ${dim}# Install for all runtimes globally${reset}\n    npx get-shit-done-cc --all --global\n\n    ${dim}# Install to custom config directory${reset}\n    npx get-shit-done-cc --codex --global --config-dir ~/.codex-work\n\n    ${dim}# Install to current project only${reset}\n    npx get-shit-done-cc --claude --local\n\n    ${dim}# Uninstall GSD from Codex globally${reset}\n    npx get-shit-done-cc --codex --global --uninstall\n\n  ${yellow}Notes:${reset}\n    The --config-dir option is useful when you have multiple configurations.\n    It takes priority over CLAUDE_CONFIG_DIR / GEMINI_CONFIG_DIR / CODEX_HOME environment variables.\n`);
   process.exit(0);
 }
 
@@ -221,7 +236,7 @@ const attributionCache = new Map();
 
 /**
  * Get commit attribution setting for a runtime
- * @param {string} runtime - 'claude', 'opencode', or 'gemini'
+ * @param {string} runtime - 'claude', 'opencode', 'gemini', or 'codex'
  * @returns {null|undefined|string} null = remove, undefined = keep default, string = custom
  */
 function getCommitAttribution(runtime) {
@@ -245,7 +260,7 @@ function getCommitAttribution(runtime) {
     } else {
       result = settings.attribution.commit;
     }
-  } else {
+  } else if (runtime === 'claude') {
     // Claude Code
     const settings = readSettings(path.join(getGlobalDir('claude', explicitConfigDir), 'settings.json'));
     if (!settings.attribution || settings.attribution.commit === undefined) {
@@ -255,6 +270,9 @@ function getCommitAttribution(runtime) {
     } else {
       result = settings.attribution.commit;
     }
+  } else {
+    // Codex currently has no attribution setting equivalent
+    result = undefined;
   }
 
   // Cache and return
@@ -371,6 +389,83 @@ function convertGeminiToolName(claudeTool) {
   return claudeTool.toLowerCase();
 }
 
+function toSingleLine(value) {
+  return value.replace(/\s+/g, ' ').trim();
+}
+
+function yamlQuote(value) {
+  return JSON.stringify(value);
+}
+
+function extractFrontmatterAndBody(content) {
+  if (!content.startsWith('---')) {
+    return { frontmatter: null, body: content };
+  }
+
+  const endIndex = content.indexOf('---', 3);
+  if (endIndex === -1) {
+    return { frontmatter: null, body: content };
+  }
+
+  return {
+    frontmatter: content.substring(3, endIndex).trim(),
+    body: content.substring(endIndex + 3),
+  };
+}
+
+function extractFrontmatterField(frontmatter, fieldName) {
+  const regex = new RegExp(`^${fieldName}:\\s*(.+)$`, 'm');
+  const match = frontmatter.match(regex);
+  if (!match) return null;
+  return match[1].trim().replace(/^['"]|['"]$/g, '');
+}
+
+function convertSlashCommandsToCodexSkillMentions(content) {
+  let converted = content.replace(/\/gsd:([a-z0-9-]+)/gi, (_, commandName) => {
+    return `$gsd-${String(commandName).toLowerCase()}`;
+  });
+  converted = converted.replace(/\/gsd-help\b/g, '$gsd-help');
+  return converted;
+}
+
+function convertClaudeToCodexMarkdown(content) {
+  let converted = convertSlashCommandsToCodexSkillMentions(content);
+  converted = converted.replace(/\$ARGUMENTS\b/g, '{{GSD_ARGS}}');
+  return converted;
+}
+
+function getCodexSkillAdapterHeader(skillName) {
+  const invocation = `$${skillName}`;
+  return `<codex_skill_adapter>
+Codex skills-first mode:
+- This skill is invoked by mentioning \`${invocation}\`.
+- Treat all user text after \`${invocation}\` as \`{{GSD_ARGS}}\`.
+- If no arguments are present, treat \`{{GSD_ARGS}}\` as empty.
+
+Legacy orchestration compatibility:
+- Any \`Task(...)\` pattern in referenced workflow docs is legacy syntax.
+- Implement equivalent behavior with Codex collaboration tools: \`spawn_agent\`, \`wait\`, \`send_input\`, and \`close_agent\`.
+- Treat legacy \`subagent_type\` names as role hints in the spawned message.
+</codex_skill_adapter>`;
+}
+
+function convertClaudeCommandToCodexSkill(content, skillName) {
+  const converted = convertClaudeToCodexMarkdown(content);
+  const { frontmatter, body } = extractFrontmatterAndBody(converted);
+  let description = `Run GSD workflow ${skillName}.`;
+  if (frontmatter) {
+    const maybeDescription = extractFrontmatterField(frontmatter, 'description');
+    if (maybeDescription) {
+      description = maybeDescription;
+    }
+  }
+  description = toSingleLine(description);
+  const shortDescription = description.length > 180 ? `${description.slice(0, 177)}...` : description;
+  const adapter = getCodexSkillAdapterHeader(skillName);
+
+  return `---\nname: ${yamlQuote(skillName)}\ndescription: ${yamlQuote(description)}\nmetadata:\n  short-description: ${yamlQuote(shortDescription)}\n---\n\n${adapter}\n\n${body.trimStart()}`;
+}
+
 /**
  * Strip HTML <sub> tags for Gemini CLI output
  * Terminals don't support subscript — Gemini renders these as raw HTML.
@@ -672,16 +767,78 @@ function copyFlattenedCommands(srcDir, destDir, prefix, pathPrefix, runtime) {
   }
 }
 
+function listCodexSkillNames(skillsDir, prefix = 'gsd-') {
+  if (!fs.existsSync(skillsDir)) return [];
+  const entries = fs.readdirSync(skillsDir, { withFileTypes: true });
+  return entries
+    .filter(entry => entry.isDirectory() && entry.name.startsWith(prefix))
+    .filter(entry => fs.existsSync(path.join(skillsDir, entry.name, 'SKILL.md')))
+    .map(entry => entry.name)
+    .sort();
+}
+
+function copyCommandsAsCodexSkills(srcDir, skillsDir, prefix, pathPrefix, runtime) {
+  if (!fs.existsSync(srcDir)) {
+    return;
+  }
+
+  fs.mkdirSync(skillsDir, { recursive: true });
+
+  // Remove previous GSD Codex skills to avoid stale command skills.
+  const existing = fs.readdirSync(skillsDir, { withFileTypes: true });
+  for (const entry of existing) {
+    if (entry.isDirectory() && entry.name.startsWith(`${prefix}-`)) {
+      fs.rmSync(path.join(skillsDir, entry.name), { recursive: true });
+    }
+  }
+
+  function recurse(currentSrcDir, currentPrefix) {
+    const entries = fs.readdirSync(currentSrcDir, { withFileTypes: true });
+
+    for (const entry of entries) {
+      const srcPath = path.join(currentSrcDir, entry.name);
+      if (entry.isDirectory()) {
+        recurse(srcPath, `${currentPrefix}-${entry.name}`);
+        continue;
+      }
+
+      if (!entry.name.endsWith('.md')) {
+        continue;
+      }
+
+      const baseName = entry.name.replace('.md', '');
+      const skillName = `${currentPrefix}-${baseName}`;
+      const skillDir = path.join(skillsDir, skillName);
+      fs.mkdirSync(skillDir, { recursive: true });
+
+      let content = fs.readFileSync(srcPath, 'utf8');
+      const globalClaudeRegex = /~\/\.claude\//g;
+      const localClaudeRegex = /\.\/\.claude\//g;
+      const codexDirRegex = /~\/\.codex\//g;
+      content = content.replace(globalClaudeRegex, pathPrefix);
+      content = content.replace(localClaudeRegex, `./${getDirName(runtime)}/`);
+      content = content.replace(codexDirRegex, pathPrefix);
+      content = processAttribution(content, getCommitAttribution(runtime));
+      content = convertClaudeCommandToCodexSkill(content, skillName);
+
+      fs.writeFileSync(path.join(skillDir, 'SKILL.md'), content);
+    }
+  }
+
+  recurse(srcDir, prefix);
+}
+
 /**
  * Recursively copy directory, replacing paths in .md files
  * Deletes existing destDir first to remove orphaned files from previous versions
  * @param {string} srcDir - Source directory
  * @param {string} destDir - Destination directory
  * @param {string} pathPrefix - Path prefix for file references
- * @param {string} runtime - Target runtime ('claude', 'opencode', 'gemini')
+ * @param {string} runtime - Target runtime ('claude', 'opencode', 'gemini', 'codex')
  */
 function copyWithPathReplacement(srcDir, destDir, pathPrefix, runtime) {
   const isOpencode = runtime === 'opencode';
+  const isCodex = runtime === 'codex';
   const dirName = getDirName(runtime);
 
   // Clean install: remove existing destination to prevent orphaned files
@@ -718,6 +875,9 @@ function copyWithPathReplacement(srcDir, destDir, pathPrefix, runtime) {
         // Replace extension with .toml
         const tomlPath = destPath.replace(/\.md$/, '.toml');
         fs.writeFileSync(tomlPath, tomlContent);
+      } else if (isCodex) {
+        content = convertClaudeToCodexMarkdown(content);
+        fs.writeFileSync(destPath, content);
       } else {
         fs.writeFileSync(destPath, content);
       }
@@ -806,10 +966,11 @@ function cleanupOrphanedHooks(settings) {
  * Uninstall GSD from the specified directory for a specific runtime
  * Removes only GSD-specific files/directories, preserves user content
  * @param {boolean} isGlobal - Whether to uninstall from global or local
- * @param {string} runtime - Target runtime ('claude', 'opencode', 'gemini')
+ * @param {string} runtime - Target runtime ('claude', 'opencode', 'gemini', 'codex')
  */
 function uninstall(isGlobal, runtime = 'claude') {
   const isOpencode = runtime === 'opencode';
+  const isCodex = runtime === 'codex';
   const dirName = getDirName(runtime);
 
   // Get the target directory based on runtime and install type
@@ -824,6 +985,7 @@ function uninstall(isGlobal, runtime = 'claude') {
   let runtimeLabel = 'Claude Code';
   if (runtime === 'opencode') runtimeLabel = 'OpenCode';
   if (runtime === 'gemini') runtimeLabel = 'Gemini';
+  if (runtime === 'codex') runtimeLabel = 'Codex';
 
   console.log(`  Uninstalling GSD from ${cyan}${runtimeLabel}${reset} at ${cyan}${locationLabel}${reset}\n`);
 
@@ -836,7 +998,7 @@ function uninstall(isGlobal, runtime = 'claude') {
 
   let removedCount = 0;
 
-  // 1. Remove GSD commands directory
+  // 1. Remove GSD commands/skills
   if (isOpencode) {
     // OpenCode: remove command/gsd-*.md files
     const commandDir = path.join(targetDir, 'command');
@@ -850,6 +1012,23 @@ function uninstall(isGlobal, runtime = 'claude') {
       }
       console.log(`  ${green}✓${reset} Removed GSD commands from command/`);
     }
+  } else if (isCodex) {
+    // Codex: remove skills/gsd-*/SKILL.md skill directories
+    const skillsDir = path.join(targetDir, 'skills');
+    if (fs.existsSync(skillsDir)) {
+      let skillCount = 0;
+      const entries = fs.readdirSync(skillsDir, { withFileTypes: true });
+      for (const entry of entries) {
+        if (entry.isDirectory() && entry.name.startsWith('gsd-')) {
+          fs.rmSync(path.join(skillsDir, entry.name), { recursive: true });
+          skillCount++;
+        }
+      }
+      if (skillCount > 0) {
+        removedCount++;
+        console.log(`  ${green}✓${reset} Removed ${skillCount} Codex skills`);
+      }
+    }
   } else {
     // Claude Code & Gemini: remove commands/gsd/ directory
     const gsdCommandsDir = path.join(targetDir, 'commands', 'gsd');
@@ -1190,7 +1369,7 @@ function verifyFileInstalled(filePath, description) {
 /**
  * Install to the specified directory for a specific runtime
  * @param {boolean} isGlobal - Whether to install globally or locally
- * @param {string} runtime - Target runtime ('claude', 'opencode', 'gemini')
+ * @param {string} runtime - Target runtime ('claude', 'opencode', 'gemini', 'codex')
  */
 
 // ──────────────────────────────────────────────────────
@@ -1231,9 +1410,13 @@ function generateManifest(dir, baseDir) {
 /**
  * Write file manifest after installation for future modification detection
  */
-function writeManifest(configDir) {
+function writeManifest(configDir, runtime = 'claude') {
+  const isOpencode = runtime === 'opencode';
+  const isCodex = runtime === 'codex';
   const gsdDir = path.join(configDir, 'get-shit-done');
   const commandsDir = path.join(configDir, 'commands', 'gsd');
+  const opencodeCommandDir = path.join(configDir, 'command');
+  const codexSkillsDir = path.join(configDir, 'skills');
   const agentsDir = path.join(configDir, 'agents');
   const manifest = { version: pkg.version, timestamp: new Date().toISOString(), files: {} };
 
@@ -1241,12 +1424,28 @@ function writeManifest(configDir) {
   for (const [rel, hash] of Object.entries(gsdHashes)) {
     manifest.files['get-shit-done/' + rel] = hash;
   }
-  if (fs.existsSync(commandsDir)) {
+  if (!isOpencode && !isCodex && fs.existsSync(commandsDir)) {
     const cmdHashes = generateManifest(commandsDir);
     for (const [rel, hash] of Object.entries(cmdHashes)) {
       manifest.files['commands/gsd/' + rel] = hash;
     }
   }
+  if (isOpencode && fs.existsSync(opencodeCommandDir)) {
+    for (const file of fs.readdirSync(opencodeCommandDir)) {
+      if (file.startsWith('gsd-') && file.endsWith('.md')) {
+        manifest.files['command/' + file] = fileHash(path.join(opencodeCommandDir, file));
+      }
+    }
+  }
+  if (isCodex && fs.existsSync(codexSkillsDir)) {
+    for (const skillName of listCodexSkillNames(codexSkillsDir)) {
+      const skillRoot = path.join(codexSkillsDir, skillName);
+      const skillHashes = generateManifest(skillRoot);
+      for (const [rel, hash] of Object.entries(skillHashes)) {
+        manifest.files[`skills/${skillName}/${rel}`] = hash;
+      }
+    }
+  }
   if (fs.existsSync(agentsDir)) {
     for (const file of fs.readdirSync(agentsDir)) {
       if (file.startsWith('gsd-') && file.endsWith('.md')) {
@@ -1303,7 +1502,7 @@ function saveLocalPatches(configDir) {
 /**
  * After install, report backed-up patches for user to reapply.
  */
-function reportLocalPatches(configDir) {
+function reportLocalPatches(configDir, runtime = 'claude') {
   const patchesDir = path.join(configDir, PATCHES_DIR_NAME);
   const metaPath = path.join(patchesDir, 'backup-meta.json');
   if (!fs.existsSync(metaPath)) return [];
@@ -1312,6 +1511,11 @@ function reportLocalPatches(configDir) {
   try { meta = JSON.parse(fs.readFileSync(metaPath, 'utf8')); } catch { return []; }
 
   if (meta.files && meta.files.length > 0) {
+    const reapplyCommand = runtime === 'opencode'
+      ? '/gsd-reapply-patches'
+      : runtime === 'codex'
+        ? '$gsd-reapply-patches'
+        : '/gsd:reapply-patches';
     console.log('');
     console.log('  ' + yellow + 'Local patches detected' + reset + ' (from v' + meta.from_version + '):');
     for (const f of meta.files) {
@@ -1319,7 +1523,7 @@ function reportLocalPatches(configDir) {
     }
     console.log('');
     console.log('  Your modifications are saved in ' + cyan + PATCHES_DIR_NAME + '/' + reset);
-    console.log('  Run ' + cyan + '/gsd:reapply-patches' + reset + ' to merge them into the new version.');
+    console.log('  Run ' + cyan + reapplyCommand + reset + ' to merge them into the new version.');
     console.log('  Or manually compare and merge the files.');
     console.log('');
   }
@@ -1329,6 +1533,7 @@ function reportLocalPatches(configDir) {
 function install(isGlobal, runtime = 'claude') {
   const isOpencode = runtime === 'opencode';
   const isGemini = runtime === 'gemini';
+  const isCodex = runtime === 'codex';
   const dirName = getDirName(runtime);
   const src = path.join(__dirname, '..');
 
@@ -1351,6 +1556,7 @@ function install(isGlobal, runtime = 'claude') {
   let runtimeLabel = 'Claude Code';
   if (isOpencode) runtimeLabel = 'OpenCode';
   if (isGemini) runtimeLabel = 'Gemini';
+  if (isCodex) runtimeLabel = 'Codex';
 
   console.log(`  Installing for ${cyan}${runtimeLabel}${reset} to ${cyan}${locationLabel}${reset}\n`);
 
@@ -1363,8 +1569,7 @@ function install(isGlobal, runtime = 'claude') {
   // Clean up orphaned files from previous versions
   cleanupOrphanedFiles(targetDir);
 
-  // OpenCode uses 'command/' (singular) with flat structure
-  // Claude Code & Gemini use 'commands/' (plural) with nested structure
+  // OpenCode uses command/ (flat), Codex uses skills/, Claude/Gemini use commands/gsd/
   if (isOpencode) {
     // OpenCode: flat structure in command/ directory
     const commandDir = path.join(targetDir, 'command');
@@ -1379,6 +1584,16 @@ function install(isGlobal, runtime = 'claude') {
     } else {
       failures.push('command/gsd-*');
     }
+  } else if (isCodex) {
+    const skillsDir = path.join(targetDir, 'skills');
+    const gsdSrc = path.join(src, 'commands', 'gsd');
+    copyCommandsAsCodexSkills(gsdSrc, skillsDir, 'gsd', pathPrefix, runtime);
+    const installedSkillNames = listCodexSkillNames(skillsDir);
+    if (installedSkillNames.length > 0) {
+      console.log(`  ${green}✓${reset} Installed ${installedSkillNames.length} skills to skills/`);
+    } else {
+      failures.push('skills/gsd-*');
+    }
   } else {
     // Claude Code & Gemini: nested structure in commands/ directory
     const commandsDir = path.join(targetDir, 'commands');
@@ -1433,6 +1648,8 @@ function install(isGlobal, runtime = 'claude') {
           content = convertClaudeToOpencodeFrontmatter(content);
         } else if (isGemini) {
           content = convertClaudeToGeminiAgent(content);
+        } else if (isCodex) {
+          content = convertClaudeToCodexMarkdown(content);
         }
         fs.writeFileSync(path.join(agentsDest, entry.name), content);
       }
@@ -1465,39 +1682,41 @@ function install(isGlobal, runtime = 'claude') {
     failures.push('VERSION');
   }
 
-  // Write package.json to force CommonJS mode for GSD scripts
-  // Prevents "require is not defined" errors when project has "type": "module"
-  // Node.js walks up looking for package.json - this stops inheritance from project
-  const pkgJsonDest = path.join(targetDir, 'package.json');
-  fs.writeFileSync(pkgJsonDest, '{"type":"commonjs"}\n');
-  console.log(`  ${green}✓${reset} Wrote package.json (CommonJS mode)`);
+  if (!isCodex) {
+    // Write package.json to force CommonJS mode for GSD scripts
+    // Prevents "require is not defined" errors when project has "type": "module"
+    // Node.js walks up looking for package.json - this stops inheritance from project
+    const pkgJsonDest = path.join(targetDir, 'package.json');
+    fs.writeFileSync(pkgJsonDest, '{"type":"commonjs"}\n');
+    console.log(`  ${green}✓${reset} Wrote package.json (CommonJS mode)`);
 
-  // Copy hooks from dist/ (bundled with dependencies)
-  // Template paths for the target runtime (replaces '.claude' with correct config dir)
-  const hooksSrc = path.join(src, 'hooks', 'dist');
-  if (fs.existsSync(hooksSrc)) {
-    const hooksDest = path.join(targetDir, 'hooks');
-    fs.mkdirSync(hooksDest, { recursive: true });
-    const hookEntries = fs.readdirSync(hooksSrc);
-    const configDirReplacement = getConfigDirFromHome(runtime, isGlobal);
-    for (const entry of hookEntries) {
-      const srcFile = path.join(hooksSrc, entry);
-      if (fs.statSync(srcFile).isFile()) {
-        const destFile = path.join(hooksDest, entry);
-        // Template .js files to replace '.claude' with runtime-specific config dir
-        if (entry.endsWith('.js')) {
-          let content = fs.readFileSync(srcFile, 'utf8');
-          content = content.replace(/'\.claude'/g, configDirReplacement);
-          fs.writeFileSync(destFile, content);
-        } else {
-          fs.copyFileSync(srcFile, destFile);
+    // Copy hooks from dist/ (bundled with dependencies)
+    // Template paths for the target runtime (replaces '.claude' with correct config dir)
+    const hooksSrc = path.join(src, 'hooks', 'dist');
+    if (fs.existsSync(hooksSrc)) {
+      const hooksDest = path.join(targetDir, 'hooks');
+      fs.mkdirSync(hooksDest, { recursive: true });
+      const hookEntries = fs.readdirSync(hooksSrc);
+      const configDirReplacement = getConfigDirFromHome(runtime, isGlobal);
+      for (const entry of hookEntries) {
+        const srcFile = path.join(hooksSrc, entry);
+        if (fs.statSync(srcFile).isFile()) {
+          const destFile = path.join(hooksDest, entry);
+          // Template .js files to replace '.claude' with runtime-specific config dir
+          if (entry.endsWith('.js')) {
+            let content = fs.readFileSync(srcFile, 'utf8');
+            content = content.replace(/'\.claude'/g, configDirReplacement);
+            fs.writeFileSync(destFile, content);
+          } else {
+            fs.copyFileSync(srcFile, destFile);
+          }
         }
       }
-    }
-    if (verifyInstalled(hooksDest, 'hooks')) {
-      console.log(`  ${green}✓${reset} Installed hooks (bundled)`);
-    } else {
-      failures.push('hooks');
+      if (verifyInstalled(hooksDest, 'hooks')) {
+        console.log(`  ${green}✓${reset} Installed hooks (bundled)`);
+      } else {
+        failures.push('hooks');
+      }
     }
   }
 
@@ -1506,6 +1725,17 @@ function install(isGlobal, runtime = 'claude') {
     process.exit(1);
   }
 
+  // Write file manifest for future modification detection
+  writeManifest(targetDir, runtime);
+  console.log(`  ${green}✓${reset} Wrote file manifest (${MANIFEST_NAME})`);
+
+  // Report any backed-up local patches
+  reportLocalPatches(targetDir, runtime);
+
+  if (isCodex) {
+    return { settingsPath: null, settings: null, statuslineCommand: null, runtime };
+  }
+
   // Configure statusline and hooks in settings.json
   // Gemini shares same hook system as Claude Code for now
   const settingsPath = path.join(targetDir, 'settings.json');
@@ -1554,13 +1784,6 @@ function install(isGlobal, runtime = 'claude') {
     }
   }
 
-  // Write file manifest for future modification detection
-  writeManifest(targetDir);
-  console.log(`  ${green}✓${reset} Wrote file manifest (${MANIFEST_NAME})`);
-
-  // Report any backed-up local patches
-  reportLocalPatches(targetDir);
-
   return { settingsPath, settings, statuslineCommand, runtime };
 }
 
@@ -1569,8 +1792,9 @@ function install(isGlobal, runtime = 'claude') {
  */
 function finishInstall(settingsPath, settings, statuslineCommand, shouldInstallStatusline, runtime = 'claude', isGlobal = true) {
   const isOpencode = runtime === 'opencode';
+  const isCodex = runtime === 'codex';
 
-  if (shouldInstallStatusline && !isOpencode) {
+  if (shouldInstallStatusline && !isOpencode && !isCodex) {
     settings.statusLine = {
       type: 'command',
       command: statuslineCommand
@@ -1578,8 +1802,10 @@ function finishInstall(settingsPath, settings, statuslineCommand, shouldInstallS
     console.log(`  ${green}✓${reset} Configured statusline`);
   }
 
-  // Always write settings
-  writeSettings(settingsPath, settings);
+  // Write settings when runtime supports settings.json
+  if (!isCodex) {
+    writeSettings(settingsPath, settings);
+  }
 
   // Configure OpenCode permissions
   if (isOpencode) {
@@ -1589,8 +1815,11 @@ function finishInstall(settingsPath, settings, statuslineCommand, shouldInstallS
   let program = 'Claude Code';
   if (runtime === 'opencode') program = 'OpenCode';
   if (runtime === 'gemini') program = 'Gemini';
+  if (runtime === 'codex') program = 'Codex';
 
-  const command = isOpencode ? '/gsd-help' : '/gsd:help';
+  let command = '/gsd:help';
+  if (runtime === 'opencode') command = '/gsd-help';
+  if (runtime === 'codex') command = '$gsd-help';
   console.log(`
   ${green}Done!${reset} Launch ${program} and run ${cyan}${command}${reset}.
 
@@ -1671,15 +1900,18 @@ function promptRuntime(callback) {
   console.log(`  ${yellow}Which runtime(s) would you like to install for?${reset}\n\n  ${cyan}1${reset}) Claude Code ${dim}(~/.claude)${reset}
   ${cyan}2${reset}) OpenCode    ${dim}(~/.config/opencode)${reset} - open source, free models
   ${cyan}3${reset}) Gemini      ${dim}(~/.gemini)${reset}
-  ${cyan}4${reset}) All
+  ${cyan}4${reset}) Codex       ${dim}(~/.codex)${reset}
+  ${cyan}5${reset}) All
 `);
 
   rl.question(`  Choice ${dim}[1]${reset}: `, (answer) => {
     answered = true;
     rl.close();
     const choice = answer.trim() || '1';
-    if (choice === '4') {
-      callback(['claude', 'opencode', 'gemini']);
+    if (choice === '5') {
+      callback(['claude', 'opencode', 'gemini', 'codex']);
+    } else if (choice === '4') {
+      callback(['codex']);
     } else if (choice === '3') {
       callback(['gemini']);
     } else if (choice === '2') {
@@ -1746,34 +1978,27 @@ function installAllRuntimes(runtimes, isGlobal, isInteractive) {
     results.push(result);
   }
 
-  // Handle statusline for Claude & Gemini (OpenCode uses themes)
-  const claudeResult = results.find(r => r.runtime === 'claude');
-  const geminiResult = results.find(r => r.runtime === 'gemini');
+  const statuslineRuntimes = ['claude', 'gemini'];
+  const primaryStatuslineResult = results.find(r => statuslineRuntimes.includes(r.runtime));
 
-  // Logic: if both are present, ask once if interactive? Or ask for each?
-  // Simpler: Ask once and apply to both if applicable.
-  
-  if (claudeResult || geminiResult) {
-    // Use whichever settings exist to check for existing statusline
-    const primaryResult = claudeResult || geminiResult;
-    
-    handleStatusline(primaryResult.settings, isInteractive, (shouldInstallStatusline) => {
-      if (claudeResult) {
-        finishInstall(claudeResult.settingsPath, claudeResult.settings, claudeResult.statuslineCommand, shouldInstallStatusline, 'claude', isGlobal);
-      }
-      if (geminiResult) {
-         finishInstall(geminiResult.settingsPath, geminiResult.settings, geminiResult.statuslineCommand, shouldInstallStatusline, 'gemini', isGlobal);
-      }
+  const finalize = (shouldInstallStatusline) => {
+    for (const result of results) {
+      const useStatusline = statuslineRuntimes.includes(result.runtime) && shouldInstallStatusline;
+      finishInstall(
+        result.settingsPath,
+        result.settings,
+        result.statuslineCommand,
+        useStatusline,
+        result.runtime,
+        isGlobal
+      );
+    }
+  };
 
-      const opencodeResult = results.find(r => r.runtime === 'opencode');
-      if (opencodeResult) {
-        finishInstall(opencodeResult.settingsPath, opencodeResult.settings, opencodeResult.statuslineCommand, false, 'opencode', isGlobal);
-      }
-    });
+  if (primaryStatuslineResult) {
+    handleStatusline(primaryStatuslineResult.settings, isInteractive, finalize);
   } else {
-    // Only OpenCode
-    const opencodeResult = results[0];
-    finishInstall(opencodeResult.settingsPath, opencodeResult.settings, opencodeResult.statuslineCommand, false, 'opencode', isGlobal);
+    finalize(false);
   }
 }