x9-browser-session

x9-browser-session is a skill for Claude Code, Codex from xonika9/agent-skills. It costs 108 tokens per session (2,594 once invoked), scanned B, original, MIT.

A guide for choosing and safely using a browser connection, including an existing logged-in browser session. It covers session selection, tab isolation, and keeping browser actions focused on the requested task.

In plain words
What is it for?
Opening pages in a user's logged-in browser, selecting the appropriate browser route, and carrying out tasks that require existing account access.
Why use it?
It reduces the risk of using the wrong browser account, losing authentication, or interfering with unrelated tabs during browser work.

Skill for Claude CodeCodex

Written for Claude Code and Codex: shipped in a Claude Code plugin, but also reads ~/.codex or $CODEX_HOME. Also seen: reads .claude/ paths; mentions subagents; mentions Claude Code.

Part of the x9-agent-skills plugin — 18 skills shipped together

Good fit Opening pages in a user's logged-in browser, selecting the appropriate browser route, and carrying out tasks that require existing account access.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/xonika9/agent-skills/x9-browser-session
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add xonika9/agent-skills --skill x9-browser-session
Clone the repo
git clone --depth 1 https://github.com/xonika9/agent-skills

Made for: Claude Code, Codex.

Or install x9-agent-skills, the plugin that ships this one along with the rest of its 18 skills.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for x9-browser-session

README.md
[![agentmods](https://agentmods.dev/badge/skills/xonika9/agent-skills/x9-browser-session.svg)](https://agentmods.dev/skills/xonika9/agent-skills/x9-browser-session)
Your own site
<a href="https://agentmods.dev/skills/xonika9/agent-skills/x9-browser-session"><img src="https://agentmods.dev/badge/skills/xonika9/agent-skills/x9-browser-session.svg" alt="Measured on agentmods" height="20"></a>
Per session 108 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,594 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00108 $0.02594
Opus 5 $0.00054 $0.01297
Sonnet 5 $0.00022 $0.00519
Haiku 4.5 $0.00011 $0.00259

Measured yesterday against content hash a8e370f97150, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade B, and why

x9-browser-session scanned grade B with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

- The Codex MCP route uses `~/.codex/config.toml` and the shared focus-safe rules.
skills/x9-browser-session/SKILL.md · 201 lines

How it starts

The opening of the file, as written. The whole thing — 201 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Browser session

Use this skill in OpenCode, Claude Code, and Codex. It owns shared route selection, the verified Edge adapter, runtime-specific extension and in-app surfaces, CDP fallbacks, task-tab isolation, and focus safety. Re-check installed tool instructions and live schemas when a named surface is absent.

chrome-devtools MCP allowlist

Targets in this list bypass the browser extension in every route that offers one. An entry matches the exact hostname and its subdomains; do not infer sibling or look-alike domains.

  • avito.ru

Avito traffic discipline

Treat one account, browser profile, and public IP as one browsing lane for the whole parent task. Avito work is sequential even when the rest of the research is delegated:

  • appoint one Avito operator; subagents may analyze captured data but must not browse avito.ru concurrently;
  • keep only one Avito navigation, search, or listing load in flight. Prefer one task tab; extra tabs may hold queued pages, but interact with only one at a time;
  • let the current page finish loading and inspect it before requesting the next page; shortlist from search results and reuse captured data instead of repeatedly reopening or refreshing listings;
  • do not bulk-load listings, paginate rapidly, poll availability, or run retry loops;
  • when Avito shows an IP or security-check interstitial that requires no user action, keep the same page, controller, and profile. Wait five seconds once without reloading, navigating, or initiating another request, then inspect the same page again. Continue serial browsing if the requested content is visible;
  • if the same interstitial remains on the second inspection, or Avito returns a CAPTCHA requiring user action, 429, timeout, access-denied, or an error page, treat it as site throttling rather than a controller failure. Stop Avito requests across the parent task, preserve collected results, and return DEGRADED; do not switch controllers, profiles, agents, or IP addresses to continue;
  • resume only when the user requests another check or ordinary access is already visibly restored. Perform that check serially through the same browser profile.

Read the full file on GitHub · 201 lines

Files

What ships with it

2 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday Changed · +6 lines a8e370f97150
  2. 8d ago First seen · 195 lines · 108 tokens per session scan B 8541a75a00a9

Subscribe to this mod's changes

x9-browser-session is a skill published in the GitHub repository xonika9/agent-skills (4 stars, last pushed 3d ago), licensed MIT. It adds 108 tokens to every session and 2,594 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it B with 1 finding (reads agent configuration directories). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

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