feat(models): add Claude Fable 5 (#4921)

* feat(models): add Claude Fable 5

* docs(anthropic): note Fable 5 in buildThinkingConfig docblock

apps/sim/providers/anthropic/core.ts

@@ -82,6 +82,7 @@ const THINKING_BUDGET_TOKENS: Record<string, number> = {
 
 /**
  * Checks if a model supports adaptive thinking (thinking.type: "adaptive").
+ * Fable 5 supports ONLY adaptive thinking (always on; type: "disabled" is rejected).
  * Opus 4.8 and Opus 4.7 support ONLY adaptive thinking (no extended thinking / budget_tokens).
  * Opus 4.6 and Sonnet 4.6 support both extended and adaptive thinking — use adaptive.
  * Opus 4.5 supports effort but NOT adaptive thinking — it uses budget_tokens with type: "enabled".
@@ -89,6 +90,7 @@ const THINKING_BUDGET_TOKENS: Record<string, number> = {
 function supportsAdaptiveThinking(modelId: string): boolean {
   const normalizedModel = modelId.toLowerCase()
   return (
+    normalizedModel.includes('fable-5') ||
     normalizedModel.includes('opus-4-8') ||
     normalizedModel.includes('opus-4.8') ||
     normalizedModel.includes('opus-4-7') ||
@@ -103,7 +105,7 @@ function supportsAdaptiveThinking(modelId: string): boolean {
 /**
  * Builds the thinking configuration for the Anthropic API based on model capabilities and level.
  *
- * - Opus 4.8, Opus 4.7: Uses adaptive thinking only (no extended thinking support)
+ * - Fable 5, Opus 4.8, Opus 4.7: Uses adaptive thinking only (no extended thinking support)
  * - Opus 4.6, Sonnet 4.6: Uses adaptive thinking with effort parameter
  * - Other models: Uses budget_tokens-based extended thinking
  *

apps/sim/providers/models.ts

@@ -631,6 +631,24 @@ export const PROVIDER_DEFINITIONS: Record<string, ProviderDefinition> = {
       toolUsageControl: true,
     },
     models: [
+      {
+        id: 'claude-fable-5',
+        pricing: {
+          input: 10.0,
+          cachedInput: 1.0,
+          output: 50.0,
+          updatedAt: '2026-06-09',
+        },
+        capabilities: {
+          maxOutputTokens: 128000,
+          thinking: {
+            levels: ['low', 'medium', 'high', 'xhigh', 'max'],
+            default: 'high',
+          },
+        },
+        contextWindow: 1000000,
+        releaseDate: '2026-06-09',
+      },
       {
         id: 'claude-opus-4-8',
         pricing: {