Claude Code plugin agents 404 "model: sonnet" — how to fix?

Question

In Claude Code v2.0.13 (Sonnet 4.5, Claude Max), installing the wshobson/agents plugin marketplace with the full-stack-development subagent and running /full-stack-development:feature-development fails with: API Error: 404 {"type":"error","error":{"type":"not_found_error","message":"model: sonnet"}}. Plain Claude Code works without plugins. What causes this and is there a workaround?

Originally asked on GitHub: https://github.com/wshobson/agents/issues/81

AgentArmorHQ team · Accepted Answer

Status: explained — the maintainer closed this as not planned because the 404 is a known Claude Code bug, not a defect in the wshobson/agents marketplace. It affects Claude Code versions 1.0.108 through 2.0.13 when running plugin marketplace content (agents, workflows, tools): plugin content executes through the slash command path, which fails to resolve model aliases like `sonnet` even though the official subagent documentation recommends those aliases. Users reported that plain Claude Code works fine without plugins.

The bug is tracked upstream at anthropics/claude-code#7304, with related reports #8083 and #9243. An Anthropic staff member acknowledged it and indicated it will be addressed in a future release; no fixed Claude Code version was named in the thread.

One user's workaround was to replace the alias in the plugin's markdown frontmatter with a full model ID:

```
find ~/.claude/plugins/marketplaces/claude-code-workflows -name "*.md" -type f -exec sed -i '' 's/^model: sonnet$/model: claude-sonnet-4-5-20250929/' {} \;
```

They described it as a hack. General advice: this edits local plugin files under `~/.claude`, so a plugin update or reinstall may overwrite the change; back up the files first.

Quota exhaustion was also considered: one user replied that they had Claude Max with under 25% usage and still hit the error, so limits were not the cause.

AgentArmorHQ team · Answer

**What a GitHub user tried on GitHub** (Didn't work)

Installed wshobson/agents and the full-stack-development subagent in Claude Code v2.0.13 (Sonnet 4.5, Max), restarted, and ran /full-stack-development:feature-development, which returned API Error: 404 not_found_error "model: sonnet".

Source: https://github.com/wshobson/agents/issues/81

AgentArmorHQ team · Answer

**What @derekslenk tried on GitHub** (Worked)

Replaced the frontmatter line `model: sonnet` with `model: claude-sonnet-4-5-20250929` in all .md files under ~/.claude/plugins/marketplaces/claude-code-workflows using sed. The user described it as a hack.

Source: https://github.com/wshobson/agents/issues/81#issuecomment-3387275418

AgentArmorHQ team · Answer

**What @anonymort tried on GitHub** (Didn't work)

A commenter suggested checking usage limits with /limits. One user replied that they had Claude Max and were under 25% usage, so quota exhaustion did not explain the error.

Source: https://github.com/wshobson/agents/issues/81#issuecomment-3387780548

AgentArmorHQ team · Answer

**What @amir-mamedov tried on GitHub** (Outcome unclear)

The maintainer traced the error to Claude Code's slash command implementation not supporting model aliases and linked upstream issues #7304, #8083, and #9243, acknowledged by Anthropic staff for a future fix.

Source: https://github.com/wshobson/agents/issues/81#issuecomment-3388564527

Claude Code plugin agents 404 "model: sonnet" — how to fix?

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Claude Code plugin agents 404 "model: sonnet" — how to fix?

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