diff --git a/packages/opencode/src/provider/transform.ts b/packages/opencode/src/provider/transform.ts
index c0b14184d08..b79837c54b1 100644
--- a/packages/opencode/src/provider/transform.ts
+++ b/packages/opencode/src/provider/transform.ts
@@ -606,31 +606,21 @@ function openaiCompatibleReasoningEfforts(id: string) {
   return gpt5CodexReasoningEfforts(apiId) ?? versionedGpt5ReasoningEfforts(apiId) ?? OPENAI_EFFORTS
 }
 
-function anthropicOpus47OrLater(apiId: string) {
-  // Matches "opus-4.7" (Anthropic/Bedrock/Vertex) and "claude-4.7-opus" (SAP AI Core inverted).
-  // Greedy \d+ correctly extends to multi-digit majors (e.g. "claude-10.0-opus") for forward compatibility.
-  const version = /opus-(\d+)[.-](\d+)(?:[.@-]|$)|claude-(\d+)[.-](\d+)-opus(?:[.@-]|$)/i.exec(apiId)
-  if (!version) return false
-  const major = Number(version[1] ?? version[3])
-  const minor = Number(version[2] ?? version[4])
+function anthropicUsesModernAdaptiveThinking(apiId: string) {
+  if (!apiId.toLowerCase().includes("claude-")) return false
+  // Covers family-first IDs such as claude-opus-4.7 and version-first IDs such as claude-4.7-opus.
+  // Limit minors to two digits so release dates in IDs such as claude-opus-4-20250514 are not versions.
+  const version = /claude-(?:[a-z]+-)?(\d+)(?:[.-](\d{1,2}))?(?:[.@-]|$)/i.exec(apiId)
+  if (!version) return true
+  const major = Number(version[1])
+  const minor = Number(version[2] ?? 0)
   return major > 4 || (major === 4 && minor >= 7)
 }
 
-// kilocode_change start - Claude 5+ models are adaptive thinking models like opus-4.7/4.8
-function anthropicClaude5(apiId: string) {
-  const id = apiId.toLowerCase()
-  if (id.includes("fable")) return true
-  const version = /(?:opus|sonnet)[.-](\d+)(?:[.@-]|$)|claude-(\d+)(?:[.-]\d+)?-(?:opus|sonnet)(?:[.@-]|$)/.exec(id)
-  return Number(version?.[1] ?? version?.[2]) >= 5
-}
-// kilocode_change end
-
 function anthropicAdaptiveEfforts(apiId: string): string[] | null {
-  // kilocode_change start - include Claude 5+ models
-  if (anthropicOpus47OrLater(apiId) || anthropicClaude5(apiId)) {
+  if (anthropicUsesModernAdaptiveThinking(apiId)) {
     return ["low", "medium", "high", "xhigh", "max"]
   }
-  // kilocode_change end
   if (
     ["opus-4-6", "opus-4.6", "4-6-opus", "4.6-opus", "sonnet-4-6", "sonnet-4.6", "4-6-sonnet", "4.6-sonnet"].some((v) =>
       apiId.includes(v),
@@ -642,7 +632,7 @@ function anthropicAdaptiveEfforts(apiId: string): string[] | null {
 }
 
 function anthropicOmitsThinking(apiId: string) {
-  return anthropicOpus47OrLater(apiId) || anthropicClaude5(apiId) // kilocode_change - include Kilo's Claude 5 aliases
+  return anthropicUsesModernAdaptiveThinking(apiId)
 }
 
 function googleThinkingLevelEfforts(apiId: string) {
@@ -982,7 +972,7 @@ export function variants(model: Provider.Model): Record<string, Record<string, a
           if (
             model.api.id.includes("opus-4.7") ||
             model.api.id.includes("opus-4.8") ||
-            anthropicClaude5(model.api.id)
+            anthropicUsesModernAdaptiveThinking(model.api.id)
           ) {
             efforts = ["medium"]
           }
diff --git a/packages/opencode/test/kilocode/transform-opus-4.7.test.ts b/packages/opencode/test/kilocode/transform-opus-4.7.test.ts
index 998edb84f88..4bf15883101 100644
--- a/packages/opencode/test/kilocode/transform-opus-4.7.test.ts
+++ b/packages/opencode/test/kilocode/transform-opus-4.7.test.ts
@@ -236,10 +236,14 @@ describe("ProviderTransform.variants - Claude Opus 4.7 / 4.8", () => {
     expect(Object.keys(result)).toEqual(["low", "medium", "high", "xhigh", "max"])
   })
 
-  test("opus-5 on bedrock returns adaptive reasoningConfig with xhigh", () => {
+  test.each([
+    "anthropic.claude-opus-5",
+    "us.anthropic.claude-opus-5-v1:0",
+    "global.anthropic.claude-opus-5",
+  ])("opus-5 on bedrock returns adaptive reasoningConfig with xhigh for %s", (id) => {
     const model = mockModel({
       api: {
-        id: "anthropic.claude-opus-5",
+        id,
         url: "https://bedrock.amazonaws.com",
         npm: "@ai-sdk/amazon-bedrock",
       },
@@ -302,4 +306,17 @@ describe("ProviderTransform.variants - Claude Opus 4.7 / 4.8", () => {
     const result = ProviderTransform.variants(model)
     expect(Object.keys(result)).toEqual(["low", "medium", "high", "max"])
   })
+
+  test("opus-4 release date is not treated as a modern adaptive version", () => {
+    const model = mockModel({
+      api: {
+        id: "claude-opus-4-20250514",
+        url: "https://api.anthropic.com",
+        npm: "@ai-sdk/anthropic",
+      },
+    })
+    const result = ProviderTransform.variants(model)
+    expect(Object.keys(result)).toEqual(["high", "max"])
+    expect(result.high).toEqual({ thinking: { type: "enabled", budgetTokens: 16000 } })
+  })
 })