upgrade-claude-adapter

upgrade-claude-adapter is a skill for Claude Code from PostHog/posthog-foss. It costs 107 tokens per session (2,562 once invoked), scanned A, original, MIT.

A runbook for updating a forked Claude agent adapter with newer upstream SDK code while preserving local changes.

In plain words
What is it for?
Use it to upgrade the Claude and Agent Client Protocol SDKs, port upstream fixes and message handling, verify the result, and update the fork record.
Why use it?
It reduces the risk of losing deliberate differences or missing important fixes when synchronizing the fork.

Skill for Claude Code

Written for Claude Code: PostToolUse hook event. Also seen: reads .claude/ paths; mentions Codex.

Good fit Use it to upgrade the Claude and Agent Client Protocol SDKs, port upstream fixes and message handling, verify the result, and update the fork record.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/posthog/posthog-foss/claude
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 PostHog/posthog-foss --skill claude
Clone the repo
git clone --depth 1 https://github.com/PostHog/posthog-foss

Made for: Claude Code.

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 upgrade-claude-adapter

README.md
[![agentmods](https://agentmods.dev/badge/skills/posthog/posthog-foss/claude/github.svg)](https://agentmods.dev/skills/posthog/posthog-foss/claude)
Your own site
<a href="https://agentmods.dev/skills/posthog/posthog-foss/claude"><img src="https://agentmods.dev/badge/skills/posthog/posthog-foss/claude/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for upgrade-claude-adapter

Your own site · 80×15
<a href="https://agentmods.dev/skills/posthog/posthog-foss/claude"><img src="https://agentmods.dev/badge/skills/posthog/posthog-foss/claude.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 107 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,562 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits
  • NVIDIA SkillSpector warn 7 Sept 2026
SkillSpector: 1 finding, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

  • medium MCP Rug Pull · line 133
    npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.
    Fix: Pin the version: npx @scope/[email protected]
How audits are shown
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 $0.00107 $0.02562
Opus 5 $0.00053 $0.01281
Sonnet 5 $0.00021 $0.00512
Haiku 4.5 $0.00011 $0.00256

Measured 7d ago against content hash 1f43068df984, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

upgrade-claude-adapter scanned grade A with 0 findings 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 7d ago.

The scan reads SKILL.md. This mod also ships 60 executable files (claude-agent.clear.test.ts, claude-agent.finish.test.ts, claude-agent.permission-mode.test.ts, …), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

products/desktop/packages/agent/src/adapters/claude/SKILL.md · 176 lines

How it starts

The opening of the file, as written. The whole thing — 176 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Upgrade the Claude ACP adapter (upstream sync)

This is a runbook for syncing our fork of @anthropic-ai/claude-agent-acp (the upstream Zed/agentclientprotocol ACP agent) that lives in packages/agent/src/adapters/claude/ with a newer upstream release. The fork is heavily diverged. The job is to port the valuable upstream changes (SDK bumps, bug fixes, new SDK-message handling) while preserving every intentional divergence — not to make the fork identical to upstream.

UPSTREAM.md (this directory) is the source of truth for the fork point, last-synced version/commit, the file mapping, the PostHog-only code, and the intentional divergences. Read it first, update it last.

This file is a runbook, not an auto-registered slash command. Invoke it by telling Claude to "follow the upgrade skill in the claude adapter dir." Move it to .claude/skills/<name>/SKILL.md if you ever want it runnable as /<name>.

Inputs you need before starting

  1. Upstream source checkout — a local git clone of github.com/agentclientprotocol/claude-agent-acp. You need its history to diff. If the user hasn't given the path, ask for it (it's usually somewhere like ~/Cloud/claude-agent-acp). Do not guess.
  2. This repo — the fork under packages/agent/.

Process

0. Orient (read, don't write)

  • Read UPSTREAM.md. Note Last sync (commit + version), the pinned SDK versions, the File Mapping, PostHog-Only Code (Do Not Sync), and Intentional Divergences.
  • In the upstream checkout, list the change set since the last sync and skim the changelog:
    • git -C <upstream> log --oneline <last-sync-sha>..HEAD
    • git -C <upstream> show <upstream>/CHANGELOG.md:CHANGELOG.md (or just read CHANGELOG.md)
  • Confirm the new target version + HEAD sha and the target SDK versions from the upstream package.json.

1. Triage every commit

Bucket each commit since the last sync:

  • Port — bug fixes and new feature / SDK-message handling that are not in the PostHog-only list and don't fight a divergence.
  • Dep bump — record the target SDK versions; the diff tells you if code changes ride along.
  • Skipchore(main): release …, actions/* CI bumps, pure dependabot dev-dep bumps, and anything matching the PostHog-only / divergence lists.

Read the full file on GitHub · 176 lines

Files

What ships with it

60 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. 7d ago First seen · 176 lines · 107 tokens per session scan A 1f43068df984

Subscribe to this mod's changes

upgrade-claude-adapter is a skill published in the GitHub repository PostHog/posthog-foss (715 stars, last pushed today), licensed MIT. It adds 107 tokens to every session and 2,562 once invoked, about $0.0005 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.

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