diff --git a/apps/opencode/src/cost-utils.ts b/apps/opencode/src/cost-utils.ts
index 58f2850f..69dd5e8f 100644
--- a/apps/opencode/src/cost-utils.ts
+++ b/apps/opencode/src/cost-utils.ts
@@ -5,8 +5,28 @@ import { Result } from '@praha/byethrow';
 /**
  * Model aliases for OpenCode-specific model names that don't exist in LiteLLM.
  * Maps OpenCode model names to their LiteLLM equivalents for pricing lookup.
+ *
+ * GitHub Copilot uses dot notation (e.g., claude-opus-4.5) while LiteLLM uses
+ * hyphen notation (e.g., claude-opus-4-5). This mapping handles those differences.
+ *
+ * GitHub Copilot model names are sourced from: https://models.dev/api.json
  */
 const MODEL_ALIASES: Record<string, string> = {
+	// GitHub Copilot uses dots, LiteLLM uses hyphens for Claude 4.5 models
+	'claude-opus-4.5': 'claude-opus-4-5',
+	'claude-sonnet-4.5': 'claude-sonnet-4-5',
+	'claude-haiku-4.5': 'claude-haiku-4-5',
+	// GitHub Copilot shorthand names for Claude 4 models
+	'claude-opus-4': 'claude-opus-4-20250514',
+	'claude-opus-41': 'claude-opus-4-1',
+	'claude-sonnet-4': 'claude-sonnet-4-20250514',
+	// GitHub Copilot Claude 3.x model names
+	'claude-3.5-sonnet': 'claude-3-5-sonnet-latest',
+	'claude-3.7-sonnet': 'claude-3-7-sonnet-latest',
+	// Extended thinking variant uses same pricing as base model
+	'claude-3.7-sonnet-thought': 'claude-3-7-sonnet-latest',
+	// Grok models require provider prefix
+	'grok-code-fast-1': 'xai/grok-code-fast-1',
 	// OpenCode uses -high suffix for higher tier/thinking mode variants
 	'gemini-3-pro-high': 'gemini-3-pro-preview',
 };