[BOT ISSUE] Anthropic: add missing claude-mythos-5 model

[github-actions]

Summary

Claude Mythos 5 (claude-mythos-5) is listed on both the Anthropic models overview page and the pricing page with full API ID, pricing, and token limits, but is missing from the model catalog entirely. The closely related claude-fable-5 (same pricing tier, same generation) is already in the catalog.

Missing Model

Model ID	Display Name	Provider
claude-mythos-5	Claude Mythos 5	anthropic

Context

• Claude Mythos 5 launched June 9, 2026 alongside Claude Fable 5 per Anthropic's announcement
• It is offered in limited availability to approved customers through Project Glasswing, successor to the earlier Claude Mythos Preview
• Pricing is identical to Claude Fable 5: $10/$50 per MTok (input/output)
• The catalog already has claude-fable-5 at line ~2618 in model_list.json with matching pricing and specs
• Bedrock and Vertex availability is listed as "Limited availability" on the models page — only the direct Anthropic API ID is confirmed GA-equivalent

Suggested Catalog Entry

"claude-mythos-5": {
  "format": "anthropic",
  "flavor": "chat",
  "multimodal": true,
  "input_cost_per_mil_tokens": 10,
  "output_cost_per_mil_tokens": 50,
  "input_cache_read_cost_per_mil_tokens": 1,
  "input_cache_write_cost_per_mil_tokens": 12.5,
  "input_cache_write_5m_cost_per_mil_tokens": 12.5,
  "input_cache_write_1h_cost_per_mil_tokens": 20,
  "displayName": "Claude Mythos 5",
  "reasoning": true,
  "reasoning_budget": true,
  "max_input_tokens": 1000000,
  "max_output_tokens": 128000,
  "available_providers": [
    "anthropic"
  ]
}

Specs mirror claude-fable-5 (same pricing tier, same generation). Pricing confirmed on the Anthropic pricing page. The models page confirms adaptive thinking (always on), 1M context, 128K max output. multimodal: true based on the models page stating all current Claude models support image input.

Verification Checklist

Check	Status	Detail
Cross-source	✅	Model ID claude-mythos-5 confirmed on Models overview AND Pricing page
Recent commits	✅	claude-mythos-5 not present in model_list.json or index.ts on current main
ID format	✅	Follows claude-{name}-{version} convention used by all Anthropic models
Duplicate check	✅	No existing open or closed issue covers claude-mythos-5

Verification Notes

Field	Source	Notes
Model ID claude-mythos-5	Anthropic Models page	Listed as "Claude API ID" in the Fable 5 / Mythos 5 comparison table
format: "anthropic"	Catalog convention	All direct Anthropic models use anthropic format
flavor: "chat"	Models page	Chat/text generation model
multimodal: true	Models page	"All current Claude models support text and image input"
input_cost_per_mil_tokens: 10	Pricing page	$10 / MTok input
output_cost_per_mil_tokens: 50	Pricing page	$50 / MTok output
input_cache_read_cost_per_mil_tokens: 1	Pricing page	$1 / MTok cache hits
input_cache_write_5m_cost_per_mil_tokens: 12.5	Pricing page	$12.50 / MTok 5-min cache writes
input_cache_write_1h_cost_per_mil_tokens: 20	Pricing page	$20 / MTok 1-hour cache writes
reasoning: true	Models page	Adaptive thinking (always on)
reasoning_budget: true	Models page (Fable 5 comparison)	Same generation as Fable 5 which has reasoning_budget
max_input_tokens: 1000000	Models page	1M token context window
max_output_tokens: 128000	Models page	128K max output

Local Files Inspected

• packages/proxy/schema/model_list.json — confirmed claude-mythos-5 is absent; claude-fable-5 exists at line ~2618
• packages/proxy/schema/index.ts — confirmed no claude-mythos-5 entry in AvailableEndpointTypes
• packages/proxy/scripts/sync_models.ts — confirmed claude-mythos-5 is not in SYNC_EXCLUDED_MODELS

{
  "kind": "missing_model",
  "provider": "anthropic",
  "models": ["claude-mythos-5"],
  "status": "active",
  "model_specs": {
    "claude-mythos-5": {
      "format": "anthropic",
      "flavor": "chat",
      "multimodal": true,
      "input_cost_per_mil_tokens": 10,
      "output_cost_per_mil_tokens": 50,
      "input_cache_read_cost_per_mil_tokens": 1,
      "input_cache_write_cost_per_mil_tokens": 12.5,
      "input_cache_write_5m_cost_per_mil_tokens": 12.5,
      "input_cache_write_1h_cost_per_mil_tokens": 20,
      "displayName": "Claude Mythos 5",
      "reasoning": true,
      "reasoning_budget": true,
      "max_input_tokens": 1000000,
      "max_output_tokens": 128000,
      "available_providers": ["anthropic"]
    }
  },
  "source_urls": [
    "https://platform.claude.com/docs/en/docs/about-claude/models",
    "https://platform.claude.com/docs/en/docs/about-claude/pricing"
  ]
}

[github-actions]

Prepared catalog updates for claude-mythos-5. Added models: claude-mythos-5.

Verification sources: https://platform.claude.com/docs/en/docs/about-claude/models, https://platform.claude.com/docs/en/docs/about-claude/pricing, https://www.anthropic.com/news/claude-fable-5-mythos-5, https://anthropic.com/glasswing
Verified metadata applied:

• claude-mythos-5: format=anthropic, flavor=chat, displayName=Claude Mythos 5, max_input_tokens=1000000, max_output_tokens=128000, pricing(input/output per 1M)=10/50, input_cache_read_cost_per_mil_tokens=1, input_cache_write_cost_per_mil_tokens=12.5, providers=anthropic, reasoning=true, reasoning_budget=true, multimodal=true

Included in the daily batch PR: #822