Update claude-api skill: Claude Opus 5 (#1476)

* Update claude-api skill: Claude Opus 5

- Add Claude Opus 5 (`claude-opus-5`) as the default model across all
  SDK examples, model tables, pricing, and migration guidance.
- Add an Opus 5 migration section covering the API changes that come
  with it, and move Opus 4.8 into the previous-generation slot.
- Drop the Opus 4.7 fast-mode guidance, which no longer applies.
- Scope the server-side fallbacks beta header to the current version.

* Update claude-api skill: Opus 5 fast-follow corrections

- Server-side refusal fallbacks are available on Claude Platform on AWS,
  not just the Claude API. Correct the availability statements in
  SKILL.md, the migration guide, and the platform-availability table.
- Simplify the effort guidance: start at `high` (the API default) and
  sweep down, rather than starting at `xhigh` for coding work.
- Add a time-to-first-token section with the prompt instruction that
  reduces pre-answer thinking on latency-sensitive routes.
- Replace the two separate thinking-disabled mitigations with the single
  combined instruction that covers both failure modes.

skills/claude-api/java/claude-api/README.md

@@ -33,7 +33,7 @@ Write from this table instead of `javap`/jar inspection. Endpoint column tells y
 | Strict tool use | non-beta | `Tool`, `Tool.InputSchema` |
 | Task budgets | beta | `.outputConfig(BetaOutputConfig.builder().taskBudget(BetaTokenTaskBudget.builder()...))` |
 | Tool search | non-beta | `.addTool(ToolSearchToolRegex20251119.builder()...)` from `com.anthropic.models.messages` |
-| Web search | non-beta | `WebSearchTool20260209` from `com.anthropic.models.messages` — the latest variant with dynamic filtering (Opus 4.8/4.7/4.6 + Sonnet 4.6). For older models or Vertex, use `WebSearchTool20250305` |
+| Web search | non-beta | `WebSearchTool20260209` from `com.anthropic.models.messages` — the latest variant with dynamic filtering (Claude Fable 5 + Claude Opus 5 + Opus 4.8/4.7/4.6 + Claude Sonnet 5 + Sonnet 4.6). For older models or Vertex, use `WebSearchTool20250305` |
 
 ### Discovering type and member names
 
@@ -79,10 +79,9 @@ AnthropicClient client = AnthropicOkHttpClient.builder()
 ```java
 import com.anthropic.models.messages.MessageCreateParams;
 import com.anthropic.models.messages.Message;
-import com.anthropic.models.messages.Model;
 
 MessageCreateParams params = MessageCreateParams.builder()
-    .model(Model.CLAUDE_OPUS_4_8)
+    .model("claude-opus-5")  // .model(String) overload — use it for ids with no typed Model constant yet
     .maxTokens(16000L)
     .addUserMessage("What is the capital of France?")
     .build();
@@ -99,7 +98,8 @@ response.content().stream()
 
 **Adaptive thinking is the recommended mode for Claude 4.6+ models.** Claude decides dynamically when and how much to think. The builder has a direct `.thinking(ThinkingConfigAdaptive)` overload — no manual union wrapping.
 
-> **Fable 5, Opus 4.8, Opus 4.7, Opus 4.6, and Sonnet 4.6:** Use adaptive thinking (below). `ThinkingConfigEnabled.builder().budgetTokens(N)` is removed on Fable 5, Opus 4.8, and 4.7 (400 if sent); deprecated on Opus 4.6 and Sonnet 4.6.
+> **Fable 5, Claude Opus 5, Opus 4.8, Opus 4.7, Opus 4.6, and Sonnet 4.6:** Use adaptive thinking (below). `ThinkingConfigEnabled.builder().budgetTokens(N)` is removed on Fable 5, Claude Opus 5, Opus 4.8, and 4.7 (400 if sent); deprecated on Opus 4.6 and Sonnet 4.6.
+> **Claude Opus 5:** thinking is on by default — omitting `.thinking(...)` runs adaptive (`ThinkingConfigAdaptive` is equivalent), unlike Opus 4.8/4.7 where omitting it meant no thinking. `ThinkingConfigDisabled` is accepted only at effort `HIGH` or lower; pairing it with `XHIGH`/`MAX` returns a 400.
 > **Older models:** Use `.thinking(ThinkingConfigEnabled.builder().budgetTokens(N).build())` (budget must be < `maxTokens`, min 1024).
 
 ```java
@@ -133,7 +133,7 @@ Effort is nested inside `OutputConfig` — there is NO `.effort()` directly on `
 import com.anthropic.models.messages.OutputConfig;
 
 .outputConfig(OutputConfig.builder()
-    .effort(OutputConfig.Effort.HIGH)  // or LOW, MEDIUM, MAX
+    .effort(OutputConfig.Effort.HIGH)  // or LOW, MEDIUM, XHIGH, MAX
     .build())
 ```
 

skills/claude-api/java/claude-api/tool-use.md

@@ -29,7 +29,7 @@ static class GetWeather implements Supplier<String> {
 
 BetaToolRunner toolRunner = client.beta().messages().toolRunner(
     MessageCreateParams.builder()
-        .model("claude-opus-4-8")
+        .model("claude-opus-5")
         .maxTokens(16000L)
         .putAdditionalHeader("anthropic-beta", "structured-outputs-2025-11-13")
         .addTool(GetWeather.class)
@@ -57,7 +57,7 @@ import com.anthropic.models.beta.messages.ToolRunnerCreateParams;
 BetaMemoryToolHandler memoryHandler = new FileSystemMemoryToolHandler(sandboxRoot);
 
 MessageCreateParams createParams = MessageCreateParams.builder()
-    .model("claude-opus-4-8")
+    .model("claude-opus-5")
     .maxTokens(4096L)
     .addTool(BetaMemoryTool20250818.builder().build())
     .addUserMessage("Remember that my favorite color is blue")

skills/claude-api/java/managed-agents/README.md

@@ -57,7 +57,7 @@ import com.anthropic.models.beta.sessions.SessionCreateParams;
 // 1. Create the agent (reusable, versioned)
 var agent = client.beta().agents().create(AgentCreateParams.builder()
     .name("Coding Assistant")
-    .model("claude-opus-4-8")
+    .model("claude-opus-5")
     .system("You are a helpful coding assistant.")
     .addTool(BetaManagedAgentsAgentToolset20260401Params.builder()
         .type(BetaManagedAgentsAgentToolset20260401Params.Type.AGENT_TOOLSET_20260401)
@@ -296,7 +296,7 @@ import com.anthropic.models.beta.agents.BetaManagedAgentsUrlMcpServerParams;
 // Agent declares MCP server (no auth here — auth goes in a vault)
 var agent = client.beta().agents().create(AgentCreateParams.builder()
     .name("GitHub Assistant")
-    .model("claude-opus-4-8")
+    .model("claude-opus-5")
     .addMcpServer(BetaManagedAgentsUrlMcpServerParams.builder()
         .type(BetaManagedAgentsUrlMcpServerParams.Type.URL)
         .name("github")