client-compatibility

A rule for detecting whether Squad is running in a command-line tool, VS Code, JetBrains, GitHub.com, or another supported interface before creating agents.

In plain words
What is it for?
Use it before spawning agents or coordinating work across multiple Copilot surfaces.
Why use it?
Different interfaces provide different tools and agent controls, so using the wrong spawning method can fail or behave incorrectly.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/alonf/specrew/client-compatibility
Any agent
npx skills add alonf/specrew --skill client-compatibility
Clone the repo
git clone --depth 1 https://github.com/alonf/specrew

Made for: Claude Code, Codex.

Per session 18 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,238 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 100% copy Near-identical to another mod 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 $0.00018 $0.01238
Opus 5 $0.00009 $0.00619
Sonnet 5 $0.00004 $0.00248
Haiku 4.5 $0.00002 $0.00124

Measured 2d ago against content hash d8da5e1e9918, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

client-compatibility 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 2d ago.

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.

Origin

This is a copy

100% identical to client-compatibility — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.copilot/skills/client-compatibility/SKILL.md · 90 lines

How it starts

The opening of the file, as written. The whole thing — 90 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Context

Squad runs on multiple Copilot surfaces (CLI, VS Code, JetBrains, GitHub.com). The coordinator must detect its platform and adapt spawning behavior accordingly. Different tools are available on different platforms, requiring conditional logic for agent spawning, SQL usage, and response timing.

Patterns

Platform Detection

Before spawning agents, determine the platform by checking available tools:

  1. CLI modetask tool is available → full spawning control. Use task with agent_type, mode, model, description, prompt parameters. Collect results via read_agent.

  2. VS Code moderunSubagent or agent tool is available → conditional behavior. Use runSubagent with the task prompt. Drop agent_type, mode, and model parameters. Multiple subagents in one turn run concurrently (equivalent to background mode). Results return automatically — no read_agent needed.

  3. Fallback mode — neither task nor runSubagent/agent available → work inline. Do not apologize or explain the limitation. Execute the task directly.

If both task and runSubagent are available, prefer task (richer parameter surface).

VS Code Spawn Adaptations

When in VS Code mode, the coordinator changes behavior in these ways:

  • Spawning tool: Use runSubagent instead of task. The prompt is the only required parameter — pass the full agent prompt (charter, identity, task, hygiene, response order) exactly as you would on CLI.
  • Parallelism: Spawn ALL concurrent agents in a SINGLE turn. They run in parallel automatically. This replaces mode: "background" + read_agent polling.
  • Model selection: Accept the session model. Do NOT attempt per-spawn model selection or fallback chains — they only work on CLI. In Phase 1, all subagents use whatever model the user selected in VS Code's model picker.
  • Scribe: Cannot fire-and-forget. Batch Scribe as the LAST subagent in any parallel group. Scribe is light work (file ops only), so the blocking is tolerable.
  • Launch table: Skip it. Results arrive with the response, not separately. By the time the coordinator speaks, the work is already done.
  • read_agent: Skip entirely. Results return automatically when subagents complete.
  • agent_type: Drop it. All VS Code subagents have full tool access by default. Subagents inherit the parent's tools.
  • description: Drop it. The agent name is already in the prompt.
  • Prompt content: Keep ALL prompt structure — charter, identity, task, hygiene, response order blocks are surface-independent.

Read the full file on GitHub · 90 lines

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. 2d ago First seen · 90 lines · 18 tokens per session scan A d8da5e1e9918

Subscribe to this mod's changes

client-compatibility is a skill published in the GitHub repository alonf/specrew (54 stars, last pushed 3d ago), licensed MIT. It adds 18 tokens to every session and 1,238 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to client-compatibility, differing in 0 lines, and is treated as a copy.