Official agent skill

Dev Server

Start the local webpack dev server and connect to it with the Playwright browser.

OfficialMITAuto-check passedTesting & QA

Install Dev Server

skills CLI

$ npx skills add Azure/cosmos-explorer --skill dev-server -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install Azure/cosmos-explorer dev-server --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/Azure/cosmos-explorer.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.github/skills/dev-server .claude/skills/dev-server && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "dev-server" agent skill from https://github.com/Azure/cosmos-explorer/tree/master/.github/skills/dev-server into .claude/skills/dev-server/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "dev-server", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/Azure/cosmos-explorer/tree/master/.github/skills/dev-server

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add Azure/cosmos-explorer --skill dev-server -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install Azure/cosmos-explorer dev-server --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Azure/cosmos-explorer.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.github/skills/dev-server .agents/skills/dev-server && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "dev-server" agent skill from https://github.com/Azure/cosmos-explorer/tree/master/.github/skills/dev-server into .agents/skills/dev-server/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "dev-server", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add Azure/cosmos-explorer --skill dev-server -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install Azure/cosmos-explorer dev-server --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Azure/cosmos-explorer.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.github/skills/dev-server .cursor/skills/dev-server && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "dev-server" agent skill from https://github.com/Azure/cosmos-explorer/tree/master/.github/skills/dev-server into .cursor/skills/dev-server/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "dev-server", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/Azure/cosmos-explorer.git --path .github/skills/dev-server

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add Azure/cosmos-explorer --skill dev-server -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install Azure/cosmos-explorer dev-server --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Azure/cosmos-explorer.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.github/skills/dev-server .gemini/skills/dev-server && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "dev-server" agent skill from https://github.com/Azure/cosmos-explorer/tree/master/.github/skills/dev-server into .gemini/skills/dev-server/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "dev-server", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install Azure/cosmos-explorer dev-server

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add Azure/cosmos-explorer --skill dev-server -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/Azure/cosmos-explorer.git skills-src && mkdir -p .github/skills && cp -r skills-src/.github/skills/dev-server .github/skills/dev-server && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "dev-server" agent skill from https://github.com/Azure/cosmos-explorer/tree/master/.github/skills/dev-server into .github/skills/dev-server/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "dev-server", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add Azure/cosmos-explorer --skill dev-server -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install Azure/cosmos-explorer dev-server --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/Azure/cosmos-explorer.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.github/skills/dev-server .opencode/skills/dev-server && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "dev-server" agent skill from https://github.com/Azure/cosmos-explorer/tree/master/.github/skills/dev-server into .opencode/skills/dev-server/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "dev-server", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: dev-server
GitHub stars: 131
Token cost: ~1.6k tokens
SKILL.md length: 532 words
Files: 1
Skills in repo: 2
Repo updated: Oct 5, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Start the local webpack dev server and connect to it with the Playwright browser.

Asked to start the dev server
SKILL.md covers Pre-Start: Check Dependencies, Check for Existing Server, Start the Dev Server and Wait for Compilation, plus 4 more sections
Calls npm and curl
Preview the app

What it does

Dev Server is an agent skill from Azure/cosmos-explorer, published by the product's own GitHub organization. Start the local webpack dev server and connect to it with the Playwright browser. Use this skill when asked to start the dev server, preview the app, or interact with the running application in a browser.

Its SKILL.md is about 1.6k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Testing & QA, covering Browser testing and Browser automation. It works with webpack, Playwright, Microsoft Azure and Azure Cosmos DB. The repository describes itself as: UI for Azure Cosmos DB. Powers the Azure Portal, https://cosmos.azure.com/, and the Cosmos DB Emulator. The licence is MIT.

When your agent uses it

Asked to start the dev server
Preview the app
Interact with the running application in a browser

Example prompts

“/dev-server”

Requirements

Node.js
Pre-approved tools (allowed-tools): shell, browser

What it can do on your machine

Read from SKILL.md and the folder at commit 226a7a2. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves these tools, so the agent can use them without asking each time:
- shell
- browser
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
- npm
- curl
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md. Its commands use npm and curl, which can reach the network depending on how they are called.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Dev Server loads about 1.6k tokens when it runs. Until then it costs about 54 tokens; SKILL.md has 532 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~54
When it runs · the whole SKILL.md, loaded when a task matches: ~1.6k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from Azure/cosmos-explorer at commit 226a7a2, republished under its MIT licence (© Azure). 532 words, ~1,559 tokens.

Download SKILL.mdSave it as .claude/skills/dev-server/SKILL.md (or your agent's skills folder).

name: dev-server
description: Start the local webpack dev server and connect to it with the Playwright browser. Use this skill when asked to start the dev server, preview the app, or interact with the running application in a browser.
allowed-tools: shell, browser

Dev Server Skill

Use this skill to start the Cosmos Explorer webpack dev server and connect to it with the Playwright MCP browser for interactive testing, debugging, or previewing the application.

Pre-Start: Check Dependencies

Before starting the dev server, check whether npm install needs to be run:

bash

if [ ! -d node_modules ] || [ package.json -nt node_modules ] || [ package-lock.json -nt node_modules ]; then
  npm install
fi

On Windows PowerShell:

powershell

if (-not (Test-Path node_modules) -or
    (Get-Item package.json).LastWriteTime -gt (Get-Item node_modules).LastWriteTime -or
    (Get-Item package-lock.json).LastWriteTime -gt (Get-Item node_modules).LastWriteTime) {
    npm install
}

Always run this check before starting the dev server.

Check for Existing Server

Before starting a new server, check if one is already running on port 1234:

powershell

try {
    $response = Invoke-WebRequest -Uri "https://localhost:1234/_ready" -SkipCertificateCheck -UseBasicParsing -ErrorAction Stop
    if ($response.StatusCode -eq 200) {
        Write-Host "Dev server is already running and ready!"
    }
} catch {
    Write-Host "No dev server detected, starting a new one..."
}

If the server is already running and ready, skip to Connect the Playwright Browser.

Start the Dev Server

Start the webpack dev server as a detached background process so it persists across session changes:

bash

npm start

The dev server:

Runs at https://localhost:1234 (HTTPS with self-signed certificate)
Uses webpack dev mode with live reload
Exposes a /_ready health-check endpoint

Wait for Compilation

After starting the server, poll the /_ready endpoint until it returns HTTP 200. Do not proceed to browser navigation until /_ready returns 200.

On Windows PowerShell:

powershell

$timeout = 120
$elapsed = 0
while ($elapsed -lt $timeout) {
    try {
        $response = Invoke-WebRequest -Uri "https://localhost:1234/_ready" -SkipCertificateCheck -UseBasicParsing -ErrorAction Stop
        if ($response.StatusCode -eq 200) {
            Write-Host "Dev server is ready!"
            break
        }
    } catch {
        # Server not ready yet
    }
    Start-Sleep -Seconds 3
    $elapsed += 3
}
if ($elapsed -ge $timeout) {
    Write-Error "Dev server did not become ready within $timeout seconds"
}

On bash:

bash

timeout=120
elapsed=0
while [ $elapsed -lt $timeout ]; do
  if curl -sk https://localhost:1234/_ready 2>/dev/null | grep -q "Compilation complete"; then
    echo "Dev server is ready!"
    break
  fi
  sleep 3
  elapsed=$((elapsed + 3))
done
if [ $elapsed -ge $timeout ]; then
  echo "Dev server did not become ready within $timeout seconds" >&2
fi

Connect the Playwright Browser

Once the dev server is ready, use the Playwright MCP browser tools to navigate to the application.

Navigate to the desired entry point:

https://localhost:1234/hostedExplorer.html — Hosted explorer (standalone mode). Best for general UI testing and interaction without Azure Portal framing.
https://localhost:1234/explorer.html — Portal explorer (Azure Portal iframe mode). Requires portal context/messages to initialize fully.
https://localhost:1234/index.html — Emulator mode. Requires a local Cosmos DB Emulator running on port 8081.
https://localhost:1234/testExplorer.html — Test explorer (dev mode only). Used for E2E test harness.

When no specific page is requested, navigate to https://localhost:1234/hostedExplorer.html as it provides the most complete standalone experience.

Dismiss Webpack Warnings Overlay

After the page loads, a webpack dev server overlay may appear inside an iframe showing DefinePlugin warnings. If a "Dismiss" button (×) is visible in the overlay, click it to close the warnings before proceeding with any other interaction.

Show full SKILL.md (227 more words)Show less

Available Pages Reference

URL	Entry Point	Description
`/hostedExplorer.html`	`src/HostedExplorer.tsx`	Standalone hosted explorer (cosmos.azure.com)
`/explorer.html`	`src/Main.tsx`	Portal iframe explorer
`/index.html`	`src/Index.tsx`	Emulator explorer
`/testExplorer.html`	`test/testExplorer/TestExplorer.ts`	Test harness (dev mode only)
`/terminal.html`	`src/Terminal/index.ts`	Notebook terminal
`/quickstart.html`	`src/quickstart.ts`	Quickstart page
`/selfServe.html`	`src/SelfServe/SelfServe.tsx`	Self-serve configuration
`/galleryViewer.html`	`src/GalleryViewer/GalleryViewer.tsx`	Notebook gallery viewer

Troubleshooting

HTTPS / Self-Signed Certificate Errors

The dev server uses HTTPS with a self-signed certificate. If the Playwright browser fails to navigate with an error like ERR_CERT_AUTHORITY_INVALID or any other SSL/TLS certificate error, stop immediately and tell the user:

The Playwright MCP server needs the --ignore-https-errors argument to connect to the dev server's self-signed certificate. Please add --ignore-https-errors to your Playwright MCP server configuration and try again.

Do not attempt workarounds (e.g., creating new browser contexts manually). The --ignore-https-errors flag is the correct fix.

Guidelines

Always start the dev server as a detached background process so it survives session changes.
Always wait for /_ready to return 200 before navigating the browser.
Ignore certificate errors in shell HTTP requests (e.g., -SkipCertificateCheck, curl -k). For the Playwright browser, the --ignore-https-errors MCP argument must be configured.
If the dev server is already running on port 1234, reuse it instead of starting a new one.
If the server fails to start, check for port conflicts (netstat -ano | findstr :1234 on Windows).
When stopping the dev server, use Stop-Process with the specific PID of the node process.

Files

Just SKILL.md in .github/skills/dev-server of Azure/cosmos-explorer.

Open the folder on GitHubat commit 226a7a2

Compare with similar skills

Dev Server next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Dev Server compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Dev Server this skillAzure/cosmos-explorer	131	—	~1.6k	Automated safety check: Pass	MIT	yesterday
playwright-cli Browser Automationgithub/gh-aw	5.3k	23 repos	~2.8k	Automated safety check: Pass	MIT	today
Playwright Skilllackeyjb/playwright-skill	3.2k	—	~1.9k	Automated safety check: Pass	MIT	6 days ago
Playwright CLItestdino-hq/playwright-skill	385	1 repos	~2.5k	Automated safety check: Pass	MIT	1 mo ago
Playwright Bot Bypassgreekr4/playwright-bot-bypass	200	—	~3.4k	Automated safety check: Pass	MIT	1 mo ago
UI Previewtingly-dev/tingly-box	351	—	~2k	Automated safety check: Notes	MPL-2.0	today

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Questions about Dev Server

What does Dev Server do?

Start the local webpack dev server and connect to it with the Playwright browser. Dev Server is an agent skill from Azure/cosmos-explorer, published by the product's own GitHub organization. Start the local webpack dev server and connect to it with the Playwright browser.

When should I use Dev Server?

Dev Server fits situations like: asked to start the dev server; preview the app; interact with the running application in a browser.

How do I install Dev Server in Claude Code?

Run `npx skills add Azure/cosmos-explorer --skill dev-server -a claude-code`. Or copy the skill folder (.github/skills/dev-server in Azure/cosmos-explorer) into .claude/skills/dev-server in your project. Claude Code loads it when a task matches its description.

How do I install Dev Server in Codex?

Run `npx skills add Azure/cosmos-explorer --skill dev-server -a codex`. Or copy the skill folder (.github/skills/dev-server in Azure/cosmos-explorer) into .agents/skills/dev-server in your project. Codex loads it when a task matches its description.

Can I use Dev Server in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add Azure/cosmos-explorer --skill dev-server -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/dev-server, .gemini/skills/dev-server, .github/skills/dev-server and .opencode/skills/dev-server in your project.

What does Dev Server need to run?

Going by SKILL.md and its folder, Dev Server needs the command-line tools its instructions call (npm and curl). Our summary lists: Node.js. Its frontmatter pre-approves these tools: shell, browser.

Does Dev Server access the network?

SKILL.md contains no URLs. Its commands use npm and curl, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Dev Server safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Dev Server use?

Dev Server is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Dev Server use?

About 1.6k tokens (SKILL.md is roughly 6.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Dev Server?

Skills that share tags, products or a category with Dev Server: playwright-cli Browser Automation (github/gh-aw, 5.3k stars), Playwright Skill (lackeyjb/playwright-skill, 3.2k stars), Playwright CLI (testdino-hq/playwright-skill, 385 stars) and Playwright Bot Bypass (greekr4/playwright-bot-bypass, 200 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Dev Server?

Azure (a GitHub organization, an official publisher) maintains it in Azure/cosmos-explorer, which has 131 GitHub stars. The repository holds 2 skills in this directory. The repository was last updated on October 5, 2026.

Source: Azure/cosmos-explorer on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Dev Server

Install Dev Server

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Dev Server Skill

Pre-Start: Check Dependencies

Check for Existing Server

Start the Dev Server

Wait for Compilation

Connect the Playwright Browser

Default Navigation

Dismiss Webpack Warnings Overlay

Available Pages Reference

Troubleshooting

HTTPS / Self-Signed Certificate Errors

Guidelines

Files

Compare with similar skills

Similar skills

playwright-cli Browser Automation

Playwright Skill

Playwright CLI

Playwright Bot Bypass

UI Preview

Open Browser

More from Azure/cosmos-explorer

Run Unit Tests

Questions about Dev Server

Install Dev Server

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Dev Server Skill

Pre-Start: Check Dependencies

Check for Existing Server

Start the Dev Server

Wait for Compilation

Connect the Playwright Browser

Default Navigation

Dismiss Webpack Warnings Overlay

Available Pages Reference

Troubleshooting

HTTPS / Self-Signed Certificate Errors

Guidelines

Files

Compare with similar skills

Similar skills

playwright-cli Browser Automation

Playwright Skill

Playwright CLI

Playwright Bot Bypass

UI Preview

Open Browser

More from Azure/cosmos-explorer

Run Unit Tests

Related

Questions about Dev Server