{
  "schema_version": "apw.provider_event.v0",
  "id": "2026-06-15-anthropic-sonnet-4-opus-4-retirement",
  "title": "Anthropic Retired Claude Sonnet 4 And Claude Opus 4 API Models",
  "event_kind": "model_retirement",
  "lifecycle_status": "reviewed",
  "provider_refs": [
    "provider:anthropic"
  ],
  "event_date": "2026-06-15",
  "date_confidence": "exact",
  "observed_at": "2026-06-17T02:17:02Z",
  "announced_at": "2026-06-15T00:00:00Z",
  "effective_at": "2026-06-15T00:00:00Z",
  "expires_at": null,
  "migration_deadline": null,
  "summary": "Anthropic release notes say Claude Sonnet 4 and Claude Opus 4 API model IDs were retired on June 15, 2026, with requests to those IDs now returning errors and recommended upgrades to Sonnet 4.6 and Opus 4.8.",
  "severity": "high",
  "confidence": "confirmed",
  "source_authority": "official_docs",
  "evidence_refs": [
    {
      "source_key": "anthropic.release_notes",
      "url": "https://platform.claude.com/docs/en/release-notes/overview",
      "retrieved_at": "2026-06-17T02:17:02Z",
      "authority": "official_docs",
      "content_sha256": "e9de4e04a4e337722f8558767c7b22a5b4495717334b737eeec576667aeb01a8",
      "snapshot_ref": "entry:efe4be97db18acaf",
      "selector": "announcement:efe4be97db18acaf",
      "license_note": "Official source reviewed for factual metadata; no provider prose copied."
    }
  ],
  "impacts": [
    {
      "scope_type": "provider_surface",
      "scope_ref": "surface:anthropic/api",
      "impact_kind": "availability",
      "direction": "removed",
      "severity": "high",
      "confidence": "confirmed",
      "subscription_impact": "possible",
      "api_usage_impact": "direct",
      "who_should_care": [
        "platform_engineers",
        "sdk_maintainers",
        "coding_agent_users"
      ],
      "recommended_action": "Remove retired Claude Sonnet 4 and Claude Opus 4 IDs from routing allowlists and migrate pinned traffic to supported successor models."
    },
    {
      "scope_type": "provider_surface",
      "scope_ref": "surface:anthropic/api",
      "impact_kind": "migration",
      "direction": "changed",
      "severity": "high",
      "confidence": "confirmed",
      "subscription_impact": "possible",
      "api_usage_impact": "direct",
      "who_should_care": [
        "platform_engineers",
        "product_engineers"
      ],
      "recommended_action": "Audit applications, gateways, and eval fixtures for pinned claude-sonnet-4-20250514 or claude-opus-4-20250514 model IDs before retrying failed requests."
    }
  ],
  "detail": {
    "kind": "model_lifecycle",
    "schema_version": "apw.event_detail.v0",
    "model_refs": [
      "model:anthropic/claude-sonnet-4-20250514",
      "model:anthropic/claude-opus-4-20250514"
    ],
    "lifecycle_action": "retirement",
    "replacement_refs": [
      "model:anthropic/claude-sonnet-4.6",
      "model:anthropic/claude-opus-4.8"
    ],
    "deadline": "2026-06-15T00:00:00Z",
    "migration_notes": "This event records API model retirement from Anthropic release notes. Researchers may have separate access paths; APW does not assert eligibility for exceptions."
  },
  "tags": [
    "source:official_docs",
    "provider:anthropic",
    "impact:model_retirement",
    "surface:anthropic_api"
  ],
  "limitations": [
    "APW records official release-note metadata only, not account-specific exception eligibility.",
    "The release-note candidate also mentioned successor models; APW records them as replacement refs, not as new launches."
  ]
}