{
  "id": "P302",
  "slug": "anthropic-claude-api-stop-reason-refusal-stop-reason-messages-api-documentation",
  "status": "search-observed",
  "product": "Claude API",
  "family": "LLM model/API behavior drift",
  "canonical_url": "https://gitdocs.org/fix/anthropic-claude-api-stop-reason-refusal-stop-reason-messages-api-documentation",
  "query_alias_url": "https://gitdocs.org/q/anthropic-claude-api-stop-reason-refusal-stop-reason-messages-api-documentation",
  "markdown_url": "https://gitdocs.org/fix/anthropic-claude-api-stop-reason-refusal-stop-reason-messages-api-documentation.md",
  "json_url": "https://gitdocs.org/api/fixes/anthropic-claude-api-stop-reason-refusal-stop-reason-messages-api-documentation.json",
  "canonical_query": "Anthropic Claude API stop_reason refusal stop reason Messages API documentation",
  "observed_codex_queries": [
    "Anthropic Claude API stop_reason refusal stop reason Messages API documentation",
    "site:docs.anthropic.com stop_reason refusal Anthropic Messages API",
    "Anthropic Messages API stop_reason values docs",
    "https://docs.anthropic.com/en/api/messages",
    "https://docs.anthropic.com/llms.txt",
    "github anthropic openapi messages stop_reason refusal"
  ],
  "organic_dependency_search_count": 6,
  "affected_versions": "",
  "exact_errors": [],
  "diagnosis": "SDK types may still accept fields that the selected hosted model rejects; model retirement, tokenizer, thinking, and tool behavior are external and fast-moving.",
  "before": "",
  "after": "",
  "verification": "Verifier checks current model ID, accepted payload, structured output/tool parsing, and behavior under retries.",
  "unsafe_fixes": [
    "Changing local code without checking the current external contract.",
    "Retrying the same install, build, or API call with no version/source change.",
    "Applying a broad unsafe bypass when a narrow compatibility fix is available."
  ],
  "last_verified_at": "2026-06-25",
  "neutral_validation": {
    "organic_search_observed": true,
    "organic_strict_pass": true,
    "no_web_counterfactual_run": false,
    "no_web_strict_pass": null,
    "search_necessity_under_fixture": null,
    "no_web_oracle_note": "Observed query evidence is separated from necessity proof; no-web and stale-contract counterfactuals should be tracked separately."
  },
  "source_trail": [
    {
      "url": "https://platform.claude.com/docs/en/about-claude/models/migration-guide",
      "label": "Claude model migration guide"
    },
    {
      "url": "https://docs.anthropic.com/en/api/messages",
      "label": "Official reference opened by Codex"
    },
    {
      "url": "https://docs.anthropic.com/llms.txt",
      "label": "Official reference opened by Codex"
    }
  ],
  "source_github_links": []
}