Claude engine + ANTHROPIC_BASE_URL (OpenRouter): api-proxy 404s current Anthropic model slugs

[Jasper13006]

Summary

With engine.id: claude routed to OpenRouter via engine.env.ANTHROPIC_BASE_URL, the api-proxy returns 404 model_not_found for a current OpenRouter Anthropic slug (anthropic/claude-sonnet-5), even though the same request succeeds when it bypasses the proxy. There appears to be no supported way to disable token-steering / the built-in model catalog for the claude engine.

Environment

• gh aw v0.82.14 and v0.86.2 (both reproduce)
• Firewall images gh-aw-firewall/*:0.27.37 (identical awf-config across both compiler versions)
• Engine: claude (Claude Code CLI), provider: OpenRouter

Workflow frontmatter (minimal)

engine:
  id: claude
  env:
    ANTHROPIC_BASE_URL: "https://openrouter.ai/api/v1"
    ANTHROPIC_API_KEY: ${{ secrets.OPENROUTER_KEY }}
network:
  allowed:
    - defaults
    - openrouter.ai
model: anthropic/claude-sonnet-5

What happens

The agent job fails on the first model call:

error: model_not_found  (api_error_status: 404)
"There's an issue with the selected model (anthropic/claude-sonnet-5). It may not exist or you may not have access to it."

Every other job (pre_activation, activation, detection, safe_outputs) succeeds. The CLI init log shows "model":"anthropic/claude-sonnet-5" and ANTHROPIC_MODEL: anthropic/claude-sonnet-5.

Not the key/model/credits/endpoint (verified via direct curl with the same key)

anthropic/claude-sonnet-5 returns a valid completion on both endpoints and with both id forms:

• POST https://openrouter.ai/api/v1/chat/completions — OK
• POST https://openrouter.ai/api/v1/messages (the Anthropic-native endpoint the CLI uses) — OK
• model anthropic/claude-sonnet-5 — OK; bare claude-sonnet-5 — OK

GET /api/v1/key confirms a non-free-tier key with credits available. So the 404 originates in the proxy layer, not at OpenRouter.

Apparent root cause

The generated awf-config runs apiProxy with enableTokenSteering: true and a built-in Copilot-oriented model catalog. For the claude engine it resolves claude → agent → [sonnet-6x, …], where sonnet-6x is pinned to *sonnet-4-5-* / *sonnet-4-6* patterns. A current slug like anthropic/claude-sonnet-5 isn't in that steering set, so the proxy rejects/mis-routes it. The catalog is tied to the firewall image (0.27.37), so bumping the compiler version doesn't change it.

Ask

Is there a supported way to, for a custom provider (ANTHROPIC_BASE_URL) on the claude engine, either:

1. disable token-steering / catalog validation and pass the configured model through to the provider verbatim, or
2. register a custom model slug so the catalog accepts it?

The docs (reference/engines) describe the ANTHROPIC_BASE_URL pattern but don't mention a catalog bypass for claude (no BYOK-mode equivalent as with Copilot). Happy to provide fuller logs.