context: fork skill exits prematurely after nested Skill tool invocation

Description

When a skill running in context: fork mode invokes another skill via the Skill tool, the parent fork exits prematurely after the nested skill completes, instead of continuing execution.

Reproduction

1. Create a parent skill with context: fork in its frontmatter
2. The parent skill's workflow has multiple phases (e.g., 6 phases)
3. In one of the middle phases (e.g., phase 4), the skill invokes another skill using the Skill tool (e.g., /todo create <title>)
4. The nested skill executes successfully (e.g., the todo file is created)
5. Bug: The parent fork exits immediately after the nested Skill call returns, skipping the remaining phases (5-6)

Expected behavior

After the nested Skill tool call completes, the parent fork should continue executing its remaining phases normally.

Actual behavior

The parent fork terminates after the nested Skill call returns. The nested skill's side effects are visible (file created), but the parent skill's subsequent phases never execute. No error is shown — the fork silently stops.

Workaround

Replace the Skill invocation with inline instructions that use Write directly to achieve the same effect, avoiding the nested Skill call entirely.

Environment

• Claude Code CLI (latest as of 2026-03-02)
• macOS