feat: add anthropic-effort hook to inject effort=max for Opus 4.6

Injects `output_config: { effort: "max" }` via AI SDK's providerOptions
when all conditions are met:
- variant is "max" (sisyphus, prometheus, metis, oracle, unspecified-high, ultrawork)
- model matches claude-opus-4[-.]6 pattern
- provider is anthropic, opencode, or github-copilot (with claude model)

Respects existing effort value if already set. Normalizes model IDs
with dots to hyphens for consistent matching.

src/hooks/anthropic-effort/index.ts

@@ -0,0 +1,55 @@
+import { log } from "../../shared"
+
+const OPUS_4_6_PATTERN = /claude-opus-4[-.]6/i
+
+function normalizeModelID(modelID: string): string {
+  return modelID.replace(/\.(\d+)/g, "-$1")
+}
+
+function isClaudeProvider(providerID: string, modelID: string): boolean {
+  if (["anthropic", "opencode"].includes(providerID)) return true
+  if (providerID === "github-copilot" && modelID.toLowerCase().includes("claude")) return true
+  return false
+}
+
+function isOpus46(modelID: string): boolean {
+  const normalized = normalizeModelID(modelID)
+  return OPUS_4_6_PATTERN.test(normalized)
+}
+
+interface ChatParamsInput {
+  sessionID: string
+  agent: { name?: string }
+  model: { providerID: string; modelID: string }
+  provider: { id: string }
+  message: { variant?: string }
+}
+
+interface ChatParamsOutput {
+  temperature?: number
+  topP?: number
+  topK?: number
+  options: Record<string, unknown>
+}
+
+export function createAnthropicEffortHook() {
+  return {
+    "chat.params": async (
+      input: ChatParamsInput,
+      output: ChatParamsOutput
+    ): Promise<void> => {
+      const { model, message } = input
+      if (message.variant !== "max") return
+      if (!isClaudeProvider(model.providerID, model.modelID)) return
+      if (!isOpus46(model.modelID)) return
+      if (output.options.effort !== undefined) return
+
+      output.options.effort = "max"
+      log("anthropic-effort: injected effort=max", {
+        sessionID: input.sessionID,
+        provider: model.providerID,
+        model: model.modelID,
+      })
+    },
+  }
+}