diff --git a/README.md b/README.md
index 028a241..abad787 100644
--- a/README.md
+++ b/README.md
@@ -82,12 +82,12 @@ ANTHROPIC_API_KEY=<key> swift run ClaudeExample --search "Top spaceflight news t
 Model identifiers are values of `ClaudeModel`. Use a compiled-in constant, or construct one with explicit capabilities for an ID that isn't compiled in yet (see [Capabilities](#capabilities)):
 
 ```swift
-ClaudeLanguageModel(name: .opus4_8, auth: auth)
+ClaudeLanguageModel(name: .opus5, auth: auth)
 ```
 
-Constants mirror API model IDs (`.opus4_8` is `claude-opus-4-8`) and carry each model's capabilities. New models ship as new constants in package releases.
+Constants mirror API model IDs (`.opus5` is `claude-opus-5`) and carry each model's capabilities. New models ship as new constants in package releases.
 
-Dateless model IDs like `claude-opus-4-8` (the 4.6 generation onward) are pinned snapshots, not evergreen pointers — the model behind an ID doesn't change underneath you.
+Dateless model IDs like `claude-opus-5` (the 4.6 generation onward) are pinned snapshots, not evergreen pointers — the model behind an ID doesn't change underneath you.
 
 ### Capabilities
 
@@ -106,7 +106,7 @@ ClaudeLanguageModel(name: model, auth: auth)
 Pin a Claude effort level for every request with `fixedEffort:`. It takes precedence over the framework's per-request reasoning hints. The API defaults to `high` when no effort is sent:
 
 ```swift
-ClaudeLanguageModel(name: .opus4_8, auth: auth, fixedEffort: .xhigh)
+ClaudeLanguageModel(name: .opus5, auth: auth, fixedEffort: .xhigh)
 ```
 
 The framework's reasoning levels map to effort per request: `.light` → `low`, `.moderate` → `medium`, `.deep` → `high`, and `.custom` accepts a Claude effort name directly (`"xhigh"`, `"max"`). Levels a model doesn't accept are dropped — a reasoning level is a hint, not a contract.
diff --git a/Sources/ClaudeForFoundationModels/ClaudeLanguageModel.swift b/Sources/ClaudeForFoundationModels/ClaudeLanguageModel.swift
index 83698e2..cc49c52 100644
--- a/Sources/ClaudeForFoundationModels/ClaudeLanguageModel.swift
+++ b/Sources/ClaudeForFoundationModels/ClaudeLanguageModel.swift
@@ -31,7 +31,7 @@ public struct ClaudeLanguageModel: Sendable {
   let authMode: AuthMode
 
   /// - Parameters:
-  ///   - name: Claude model identifier. Use a constant (`.sonnet5`, `.opus4_8`,
+  ///   - name: Claude model identifier. Use a constant (`.sonnet5`, `.opus5`,
   ///     `.haiku4_5`), or construct a ``ClaudeModel`` with explicit capabilities
   ///     for IDs not yet compiled in.
   ///   - auth: Credential mode. `.apiKey` for prototyping; `.proxied` with a
diff --git a/Sources/ClaudeForFoundationModels/ClaudeModel.swift b/Sources/ClaudeForFoundationModels/ClaudeModel.swift
index 2850ea6..45eb003 100644
--- a/Sources/ClaudeForFoundationModels/ClaudeModel.swift
+++ b/Sources/ClaudeForFoundationModels/ClaudeModel.swift
@@ -68,7 +68,16 @@ public struct ClaudeModel: Sendable, Hashable {
   // Capability matrix per the Messages API docs: sampling params are rejected
   // on Sonnet 5 and Opus 4.7+ (Opus 4.6 still accepts them), `.xhigh` exists
   // only on Sonnet 5 and Opus 4.7+, and `.max` requires the 4.6 generation
-  // or newer.
+  // or newer. Opus 5 keeps the Opus 4.8 request surface.
+  public static let opus5 = ClaudeModel(
+    id: "claude-opus-5",
+    capabilities: .init(
+      effortLevels: [.low, .medium, .high, .xhigh, .max],
+      adaptiveThinking: true,
+      structuredOutput: true,
+      imageInput: true
+    )
+  )
   /// High-performance model for coding and agents.
   public static let sonnet5 = ClaudeModel(
     id: "claude-sonnet-5",