Skill named "batch" silently blocked with misleading disable-model-invocation error

Bug

A custom skill named batch cannot be invoked via the Skill tool. The error message says disable-model-invocation but the frontmatter has no such field. Renaming to run-batch fixes it immediately.

Reproduction

1. Create .claude/skills/batch/SKILL.md:

---
name: batch
description: Run a batch of tasks
allowed-tools: Read, Grep, Glob, Bash
---

Do batch stuff.

1. Invoke via Skill tool: Skill("batch")

1. Expected: Skill loads and executes

Actual: Skill batch cannot be used with Skill tool due to disable-model-invocation

1. Rename directory to run-batch/, change name: run-batch in frontmatter → works immediately.

Evidence

• No disable-model-invocation field in frontmatter (hex-dumped the file to rule out hidden chars)
• Other skills with identical frontmatter structure (orient, status, commit) work fine
• The Skill(batch) permission is explicitly allowed in settings.local.json
• Reproducible across multiple invocations in the same session
• argument-hint field was initially suspected but ruled out (other skills with it weren't tested, but the rename alone fixed it)

Root cause hypothesis

"batch" appears to be a reserved name internally in Claude Code. The system intercepts it before reaching the skill file, and the error message references disable-model-invocation which is unrelated to the actual cause.

Impact

• Silent failure with misleading error — user has no way to know the name is reserved
• Costs ~4-6 tool calls of wasted context per failed invocation attempt as the agent tries to recover
• No documentation of reserved skill names exists

Suggested fix

1. If certain skill names are reserved, document them or emit a clear error: "batch" is a reserved skill name — choose a different name
2. Or remove the reservation if it's unintentional

Environment

• Claude Code: latest (as of 2026-03-19)
• Model: claude-opus-4-6 (1M context)
• OS: macOS Darwin 25.3.0
• Skill invoked via: Skill tool in interactive session

🤖 Generated with Claude Code