[Bug] /agents command displays wrong model (shows Sonnet instead of Opus 4.1)

Bug Description

The /agents command displays claude-3-5-sonnet-20241022 for all agents, but the actual agent configuration files specify claude-opus-4-1-20250805.

Steps to Reproduce

1. Run /agents command in Claude Code
2. Observe that all agents show claude-3-5-sonnet-20241022 as their model
3. Check actual agent files in ~/.claude/agents/*.md
4. Observe that all agent frontmatter contains model: claude-opus-4-1-20250805

Expected Behavior

The /agents command should display the correct model (claude-opus-4-1-20250805) as specified in each agent's frontmatter.

Actual Behavior

All agents incorrectly display claude-3-5-sonnet-20241022 regardless of their actual configuration.

Evidence

# All agent files specify Opus 4.1:
$ grep "^model:" ~/.claude/agents/*.md | head -5
/Users/jakerandall/.claude/agents/a11y-frontend-reviewer.md:model: claude-opus-4-1-20250805
/Users/jakerandall/.claude/agents/api-architect.md:model: claude-opus-4-1-20250805
/Users/jakerandall/.claude/agents/architect-reviewer.md:model: claude-opus-4-1-20250805
/Users/jakerandall/.claude/agents/backend-typescript-architect.md:model: claude-opus-4-1-20250805
/Users/jakerandall/.claude/agents/brand-identity-architect.md:model: claude-opus-4-1-20250805

# Verification that ALL agents have Opus 4.1:
$ grep "^model:" ~/.claude/agents/*.md | grep -v "claude-opus-4-1-20250805" || echo "All agents specify Opus 4.1"
All agents specify Opus 4.1

Screenshot showing the /agents command output:
!agents-output

System Information

• Platform: macOS (Darwin 24.6.0)
• Claude Code Model: claude-opus-4-1-20250805
• Settings: ~/.claude/settings.json specifies "model": "opus"
• Claude Code Version: Latest as of 2025-08-06

Impact

This causes confusion for users who see Sonnet listed but expect Opus 4.1 based on their configuration. The display doesn't match the actual agent specifications.

Suggested Fix

The /agents command should:

1. Parse the model: field from each agent's frontmatter
2. Display the actual model specified instead of a hardcoded default
3. Fall back to a default only if no model is specified in the frontmatter

Additional Context

All 25 agents in ~/.claude/agents/ have model: claude-opus-4-1-20250805 in their frontmatter, yet the /agents command shows all of them using Sonnet. This appears to be a display bug where the command either has a hardcoded model string or isn't correctly parsing the frontmatter.