[Bug] Documentation: additionalDirectories incorrectly stated as non-propagating to Task subagents

Bug Description
[Automated Bug Detection System]

DOCUMENTATION INACCURACY: Subagent Permission Inheritance

## Issue
The Claude Code documentation incorrectly states that additionalDirectories do NOT propagate to subagents spawned via the Task tool. Testing confirms this is FALSE — /add-dir permissions DO propagate to Task-spawned subagents.

## Faulty Documentation Sources

• Claude Code Subagents: https://code.claude.com/docs/en/sub-agents.md
• Claude Code IAM & Permissions: https://code.claude.com/docs/en/iam.md

## What the docs claim
"additionalDirectories are parent-session-only. Subagents spawned via the Task tool do not inherit these expanded permissions."

## Actual behavior (tested 2025-12-27)

1. Run /add-dir /path/to/external-repo in parent session
2. Spawn 6 parallel Task subagents targeting that path
3. Result: ALL subagents successfully accessed the external path (Glob, Grep, Read, Bash all worked)

## Impact
Developers designing multi-agent skills may incorrectly believe cross-directory scanning is impossible, leading to unnecessary architectural workarounds.

## Suggested fix
Update documentation to clarify that /add-dir (session-level additionalDirectories) DOES propagate to Task-spawned subagents.

Environment Info

• Platform: darwin
• Terminal: ghostty
• Version: 2.0.76
• Feedback ID: 34a223e5-7650-4053-97c9-937bf509f98d

Errors

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