Merge pull request #2606 from RaviTharuma/fix/clamp-variant-on-non-opus-fallback

fix: clamp unsupported max variant for non-Opus Claude models

src/hooks/anthropic-effort/hook.ts

@@ -1,6 +1,6 @@
 import { log, normalizeModelID } from "../../shared"
 
-const OPUS_4_6_PATTERN = /claude-opus-4[-.]6/i
+const OPUS_PATTERN = /claude-opus/i
 
 function isClaudeProvider(providerID: string, modelID: string): boolean {
   if (["anthropic", "google-vertex-anthropic", "opencode"].includes(providerID)) return true
@@ -8,9 +8,9 @@ function isClaudeProvider(providerID: string, modelID: string): boolean {
   return false
 }
 
-function isOpus46(modelID: string): boolean {
+function isOpusModel(modelID: string): boolean {
   const normalized = normalizeModelID(modelID)
-  return OPUS_4_6_PATTERN.test(normalized)
+  return OPUS_PATTERN.test(normalized)
 }
 
 interface ChatParamsInput {
@@ -28,6 +28,20 @@ interface ChatParamsOutput {
   options: Record<string, unknown>
 }
 
+/**
+ * Valid thinking budget levels per model tier.
+ * Opus supports "max"; all other Claude models cap at "high".
+ */
+const MAX_VARIANT_BY_TIER: Record<string, string> = {
+  opus: "max",
+  default: "high",
+}
+
+function clampVariant(variant: string, isOpus: boolean): string {
+  if (variant !== "max") return variant
+  return isOpus ? MAX_VARIANT_BY_TIER.opus : MAX_VARIANT_BY_TIER.default
+}
+
 export function createAnthropicEffortHook() {
   return {
     "chat.params": async (
@@ -38,15 +52,27 @@ export function createAnthropicEffortHook() {
       if (!model?.modelID || !model?.providerID) return
       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,
-      })
+      const opus = isOpusModel(model.modelID)
+      const clamped = clampVariant(message.variant, opus)
+      output.options.effort = clamped
+
+      if (!opus) {
+        // Override the variant so OpenCode doesn't pass "max" to the API
+        ;(message as { variant?: string }).variant = clamped
+        log("anthropic-effort: clamped variant max→high for non-Opus model", {
+          sessionID: input.sessionID,
+          provider: model.providerID,
+          model: model.modelID,
+        })
+      } else {
+        log("anthropic-effort: injected effort=max", {
+          sessionID: input.sessionID,
+          provider: model.providerID,
+          model: model.modelID,
+        })
+      }
     },
   }
 }

src/hooks/anthropic-effort/index.test.ts

@@ -116,6 +116,21 @@ describe("createAnthropicEffortHook", () => {
       //#then should normalize and inject effort
       expect(output.options.effort).toBe("max")
     })
+
+    it("should preserve max for other opus model IDs such as opus-4-5", async () => {
+      //#given another opus model id that is not 4.6
+      const hook = createAnthropicEffortHook()
+      const { input, output } = createMockParams({
+        modelID: "claude-opus-4-5",
+      })
+
+      //#when chat.params hook is called
+      await hook["chat.params"](input, output)
+
+      //#then max should still be treated as valid for opus family
+      expect(output.options.effort).toBe("max")
+      expect(input.message.variant).toBe("max")
+    })
   })
 
   describe("conditions NOT met - should skip", () => {
@@ -143,8 +158,8 @@ describe("createAnthropicEffortHook", () => {
       expect(output.options.effort).toBeUndefined()
     })
 
-    it("should NOT inject effort for non-opus model", async () => {
-      //#given claude-sonnet-4-6 (not opus)
+    it("should clamp effort to high for non-opus claude model with variant max", async () => {
+      //#given claude-sonnet-4-6 (not opus) with variant max
       const hook = createAnthropicEffortHook()
       const { input, output } = createMockParams({
         modelID: "claude-sonnet-4-6",
@@ -153,8 +168,9 @@ describe("createAnthropicEffortHook", () => {
       //#when chat.params hook is called
       await hook["chat.params"](input, output)
 
-      //#then effort should NOT be injected
-      expect(output.options.effort).toBeUndefined()
+      //#then effort should be clamped to high (not max)
+      expect(output.options.effort).toBe("high")
+      expect(input.message.variant).toBe("high")
     })
 
     it("should NOT inject effort for non-anthropic provider with non-claude model", async () => {

src/plugin/chat-params.test.ts

@@ -35,4 +35,37 @@ describe("createChatParamsHandler", () => {
     //#then
     expect(called).toBe(true)
   })
+
+  test("passes the original mutable message object to chat.params hooks", async () => {
+    //#given
+    const handler = createChatParamsHandler({
+      anthropicEffort: {
+        "chat.params": async (input) => {
+          input.message.variant = "high"
+        },
+      },
+    })
+
+    const message = { variant: "max" }
+    const input = {
+      sessionID: "ses_chat_params",
+      agent: { name: "sisyphus" },
+      model: { providerID: "opencode", modelID: "claude-sonnet-4-6" },
+      provider: { id: "opencode" },
+      message,
+    }
+
+    const output = {
+      temperature: 0.1,
+      topP: 1,
+      topK: 1,
+      options: {},
+    }
+
+    //#when
+    await handler(input, output)
+
+    //#then
+    expect(message.variant).toBe("high")
+  })
 })

src/plugin/chat-params.ts

@@ -6,6 +6,10 @@ export type ChatParamsInput = {
   message: { variant?: string }
 }
 
+type ChatParamsHookInput = ChatParamsInput & {
+  rawMessage?: Record<string, unknown>
+}
+
 export type ChatParamsOutput = {
   temperature?: number
   topP?: number
@@ -17,7 +21,7 @@ function isRecord(value: unknown): value is Record<string, unknown> {
   return typeof value === "object" && value !== null
 }
 
-function buildChatParamsInput(raw: unknown): ChatParamsInput | null {
+function buildChatParamsInput(raw: unknown): ChatParamsHookInput | null {
   if (!isRecord(raw)) return null
 
   const sessionID = raw.sessionID
@@ -56,7 +60,9 @@ function buildChatParamsInput(raw: unknown): ChatParamsInput | null {
     agent: { name: agentName },
     model: { providerID, modelID },
     provider: { id: providerId },
-    message: typeof variant === "string" ? { variant } : {},
+    message,
+    rawMessage: message,
+    ...(typeof variant === "string" ? {} : {}),
   }
 }
 
@@ -69,7 +75,7 @@ function isChatParamsOutput(raw: unknown): raw is ChatParamsOutput {
 }
 
 export function createChatParamsHandler(args: {
-  anthropicEffort: { "chat.params"?: (input: ChatParamsInput, output: ChatParamsOutput) => Promise<void> } | null
+  anthropicEffort: { "chat.params"?: (input: ChatParamsHookInput, output: ChatParamsOutput) => Promise<void> } | null
 }): (input: unknown, output: unknown) => Promise<void> {
   return async (input, output): Promise<void> => {
     const normalizedInput = buildChatParamsInput(input)