From 2428ad2bcd337fee0f296cf07d0b323dac58d50e Mon Sep 17 00:00:00 2001
From: Randi <55005611+rdself@users.noreply.github.com>
Date: Fri, 29 May 2026 00:44:58 -0400
Subject: [PATCH] feat(claude): default xhigh support for newer Opus models
 (#2874)

Integrated into release/v3.8.6.
---
 @omniroute/opencode-provider/README.md        |  6 +-
 @omniroute/opencode-provider/src/index.ts     |  5 +-
 .../opencode-provider/tests/index.test.ts     | 10 ++-
 docs/guides/USER_GUIDE.md                     |  4 +-
 open-sse/config/providerModels.ts             | 11 ++-
 open-sse/config/providerRegistry.ts           |  7 +-
 open-sse/executors/base.ts                    |  4 +-
 open-sse/services/claudeCodeCompatible.ts     |  2 +-
 open-sse/services/modelFamilyFallback.ts      |  1 +
 open-sse/services/providerCostData.ts         |  1 +
 src/lib/db/settings.ts                        |  5 +-
 src/lib/providers/claudeFastMode.ts           | 10 ++-
 src/lib/providers/staticModels.ts             |  1 +
 src/shared/constants/modelSpecs.ts            | 14 ++++
 src/shared/constants/pricing.ts               | 10 +++
 .../base-executor-sanitize-effort.test.ts     |  4 +-
 tests/unit/cc-compatible-provider.test.ts     |  7 +-
 .../claude-code-compatible-request.test.ts    |  9 ++-
 tests/unit/claude-fast-mode.test.ts           | 73 +++++++++++++++++++
 tests/unit/provider-models-config.test.ts     | 12 +++
 tests/unit/t12-pricing-updates.test.ts        |  4 +
 .../unit/t31-t33-t34-t38-model-specs.test.ts  |  2 +
 .../unit/translator-openai-to-claude.test.ts  |  9 ++-
 23 files changed, 181 insertions(+), 30 deletions(-)
 create mode 100644 tests/unit/claude-fast-mode.test.ts

diff --git a/@omniroute/opencode-provider/README.md b/@omniroute/opencode-provider/README.md
index fdbfeba8c8..624fddbb6e 100644
--- a/@omniroute/opencode-provider/README.md
+++ b/@omniroute/opencode-provider/README.md
@@ -100,7 +100,7 @@ Exported for completeness. Strips trailing `/`, deduplicates a trailing `/v1`, a
 - `OMNIROUTE_PROVIDER_KEY` — `"omniroute"` (the key used under `provider.*`).
 - `OMNIROUTE_PROVIDER_NPM` — `"@ai-sdk/openai-compatible"` (the runtime delegate).
 - `OPENCODE_CONFIG_SCHEMA` — `"https://opencode.ai/config.json"`.
-- `OMNIROUTE_DEFAULT_OPENCODE_MODELS` — readonly list of 4 default model ids.
+- `OMNIROUTE_DEFAULT_OPENCODE_MODELS` — readonly list of default model ids.
 
 ## Custom model catalog
 
@@ -110,10 +110,10 @@ import { createOmniRouteProvider } from "@omniroute/opencode-provider";
 createOmniRouteProvider({
   baseURL: "http://localhost:20128",
   apiKey: "sk_omniroute",
-  models: ["auto", "claude-opus-4-7", "gpt-5.5"],
+  models: ["auto", "claude-opus-4-8", "gpt-5.5"],
   modelLabels: {
     auto: "Auto-Combo (recommended)",
-    "claude-opus-4-7": "Claude Opus 4.7",
+    "claude-opus-4-8": "Claude Opus 4.8",
     "gpt-5.5": "GPT-5.5",
   },
 });
diff --git a/@omniroute/opencode-provider/src/index.ts b/@omniroute/opencode-provider/src/index.ts
index 454f45012c..6f3a2384ee 100644
--- a/@omniroute/opencode-provider/src/index.ts
+++ b/@omniroute/opencode-provider/src/index.ts
@@ -46,6 +46,7 @@ export const OPENCODE_CONFIG_SCHEMA = "https://opencode.ai/config.json" as const
  * with Claude Code passthrough models (`cc/` prefix).
  */
 export const OMNIROUTE_DEFAULT_OPENCODE_MODELS = [
+  "cc/claude-opus-4-8",
   "cc/claude-opus-4-7",
   "cc/claude-sonnet-4-6",
   "cc/claude-haiku-4-5-20251001",
@@ -83,7 +84,8 @@ export interface ModelCapabilities {
  * Matches the context lengths used by OmniRoute's provider registry.
  */
 export const OMNIROUTE_DEFAULT_MODEL_CONTEXT_LENGTHS: Record<string, number> = {
-  "cc/claude-opus-4-7": 200_000,
+  "cc/claude-opus-4-8": 1_000_000,
+  "cc/claude-opus-4-7": 1_000_000,
   "cc/claude-sonnet-4-6": 200_000,
   "cc/claude-haiku-4-5-20251001": 200_000,
   "claude-opus-4-5-thinking": 200_000,
@@ -100,6 +102,7 @@ export const OMNIROUTE_DEFAULT_MODEL_CONTEXT_LENGTHS: Record<string, number> = {
  * model via `OmniRouteProviderOptions.modelCapabilities`.
  */
 export const OMNIROUTE_DEFAULT_MODEL_CAPABILITIES: Record<string, ModelCapabilities> = {
+  "cc/claude-opus-4-8": { attachment: true, reasoning: true, temperature: true, tool_call: true },
   "cc/claude-opus-4-7": { attachment: true, reasoning: true, temperature: true, tool_call: true },
   "cc/claude-sonnet-4-6": { attachment: true, reasoning: true, temperature: true, tool_call: true },
   "cc/claude-haiku-4-5-20251001": { attachment: true, temperature: true, tool_call: true },
diff --git a/@omniroute/opencode-provider/tests/index.test.ts b/@omniroute/opencode-provider/tests/index.test.ts
index 9e14ba3bff..50d3439a33 100644
--- a/@omniroute/opencode-provider/tests/index.test.ts
+++ b/@omniroute/opencode-provider/tests/index.test.ts
@@ -388,6 +388,7 @@ test("createOmniRouteComboConfig includes optional fields when supplied", () =>
 
 test("OMNIROUTE_DEFAULT_OPENCODE_MODELS includes cc/ prefixed models", () => {
   const defaults = [...OMNIROUTE_DEFAULT_OPENCODE_MODELS];
+  assert.ok(defaults.includes("cc/claude-opus-4-8"));
   assert.ok(
     defaults.some((m) => m.startsWith("cc/")),
     "should have cc/ prefixed models"
@@ -413,9 +414,10 @@ test("createOmniRouteProvider emits limit.context on default model entries", ()
     baseURL: "http://localhost:20128",
     apiKey: "sk_omniroute",
   });
-  const entry = provider.models["cc/claude-opus-4-7"];
+  const entry = provider.models["cc/claude-opus-4-8"];
   assert.ok(entry.limit, "model entry should have a limit field");
-  assert.equal(entry.limit!.context, 200_000);
+  assert.equal(entry.limit!.context, 1_000_000);
+  assert.equal(provider.models["cc/claude-opus-4-7"].limit!.context, 1_000_000);
 });
 
 test("createOmniRouteProvider omits limit.context for unknown model ids", () => {
@@ -480,8 +482,8 @@ test("createOmniRouteProvider emits default capability flags inline with the mod
     baseURL: "http://localhost:20128",
     apiKey: "sk_omniroute",
   });
-  const entry = provider.models["cc/claude-opus-4-7"];
-  assert.equal(entry.name, "cc/claude-opus-4-7");
+  const entry = provider.models["cc/claude-opus-4-8"];
+  assert.equal(entry.name, "cc/claude-opus-4-8");
   assert.equal(entry.attachment, true);
   assert.equal(entry.reasoning, true);
   assert.equal(entry.temperature, true);
diff --git a/docs/guides/USER_GUIDE.md b/docs/guides/USER_GUIDE.md
index 2cf8b50ff5..5a919867e7 100644
--- a/docs/guides/USER_GUIDE.md
+++ b/docs/guides/USER_GUIDE.md
@@ -578,7 +578,7 @@ For the full environment variable reference, see the [README](../README.md).
 
 > The list below is curated from `open-sse/config/providerRegistry.ts` for v3.8.0. Cloud catalogs (Gemini, OpenRouter, etc.) are synced dynamically — for the full live catalog open **Dashboard → Providers → [provider] → Available Models** or call `GET /api/models/catalog`.
 
-**Claude Code (`cc/`)** — Pro/Max OAuth: `cc/claude-opus-4-7`, `cc/claude-opus-4-6`, `cc/claude-opus-4-5-20251101`, `cc/claude-sonnet-4-6`, `cc/claude-sonnet-4-5-20250929`, `cc/claude-haiku-4-5-20251001`
+**Claude Code (`cc/`)** — Pro/Max OAuth: `cc/claude-opus-4-8`, `cc/claude-opus-4-7`, `cc/claude-opus-4-6`, `cc/claude-opus-4-5-20251101`, `cc/claude-sonnet-4-6`, `cc/claude-sonnet-4-5-20250929`, `cc/claude-haiku-4-5-20251001`
 
 **Codex (`cx/`)** — Plus/Pro OAuth: `cx/gpt-5.5` (+ effort tiers: `gpt-5.5-xhigh`, `gpt-5.5-high`, `gpt-5.5-medium`, `gpt-5.5-low`), `cx/gpt-5.4`, `cx/gpt-5.4-mini`, `cx/gpt-5.3-codex`, `cx/gpt-5.3-codex-spark`, `cx/gpt-5.2`
 
@@ -626,7 +626,7 @@ For the full environment variable reference, see the [README](../README.md).
 
 **Other compatible providers** (selected): `cohere`, `databricks`, `snowflake`, `together`, `vertex`, `alibaba`, `alibaba-cn`, `bedrock` (via `aws-bedrock`), `azure-ai`, `openrouter` (passthrough catalog), `siliconflow`, `hyperbolic`, `huggingface`, `featherless-ai`, `cloudflare-ai`, `scaleway`, `deepinfra`, `vercel-ai-gateway`, `bazaarlink`, `friendliai`, `nous-research`, `reka`, `volcengine`, `ai21`, `gigachat`. Each maintains its own model list in `providerRegistry.ts` and can be auto-synced when the provider exposes a `/models` endpoint.
 
-**Note on model IDs:** OmniRoute uses provider-native IDs (`claude-opus-4-7`, `gpt-5.5`, `glm-5.1`, `MiniMax-M2.7`, `kimi-k2.5`, `grok-4.20-0309-reasoning`). Some IDs include dotted versions because that is how the upstream API expects them. If a model is not listed above, run `omniroute models --search <term>` or hit `GET /api/models/catalog` to confirm availability.
+**Note on model IDs:** OmniRoute uses provider-native IDs (`claude-opus-4-8`, `gpt-5.5`, `glm-5.1`, `MiniMax-M2.7`, `kimi-k2.5`, `grok-4.20-0309-reasoning`). Some IDs include dotted versions because that is how the upstream API expects them. If a model is not listed above, run `omniroute models --search <term>` or hit `GET /api/models/catalog` to confirm availability.
 
 </details>
 
diff --git a/open-sse/config/providerModels.ts b/open-sse/config/providerModels.ts
index 66c7778b5a..c124984c91 100644
--- a/open-sse/config/providerModels.ts
+++ b/open-sse/config/providerModels.ts
@@ -64,5 +64,14 @@ export function supportsXHighEffort(aliasOrId: string, modelId: string): boolean
   const providerModels = PROVIDER_MODELS[alias] || PROVIDER_MODELS[aliasOrId];
   // Unknown provider (not in registry) — pass through unchanged.
   if (!providerModels) return true;
-  return getProviderModel(alias, modelId)?.supportsXHighEffort === true;
+  const model = getProviderModel(alias, modelId);
+
+  // Claude Code models default to supporting extra-high effort. Keep explicit
+  // false entries as the unsupported-model list so newly added Claude models do
+  // not need opt-in flags.
+  if (alias === "cc") {
+    return model?.supportsXHighEffort !== false;
+  }
+
+  return model?.supportsXHighEffort === true;
 }
diff --git a/open-sse/config/providerRegistry.ts b/open-sse/config/providerRegistry.ts
index c7ba2fbded..fddcefbd8b 100644
--- a/open-sse/config/providerRegistry.ts
+++ b/open-sse/config/providerRegistry.ts
@@ -634,10 +634,15 @@ export const REGISTRY: Record<string, RegistryEntry> = {
       tokenUrl: "https://console.anthropic.com/v1/oauth/token",
     },
     models: [
+      {
+        id: "claude-opus-4-8",
+        name: "Claude Opus 4.8",
+        contextLength: 1000000,
+        maxOutputTokens: 128000,
+      },
       {
         id: "claude-opus-4-7",
         name: "Claude Opus 4.7",
-        supportsXHighEffort: true,
         contextLength: 1000000,
         maxOutputTokens: 128000,
       },
diff --git a/open-sse/executors/base.ts b/open-sse/executors/base.ts
index 8c31a28807..388f85e0f7 100644
--- a/open-sse/executors/base.ts
+++ b/open-sse/executors/base.ts
@@ -217,8 +217,8 @@ function hasActiveClaudeThinking(body: Record<string, unknown>): boolean {
  * Each rejection burns a combo fallback attempt before reaching a working
  * provider. Apply provider-aware sanitation here (after transformRequest, so
  * reintroductions by per-provider transforms are also caught) before fetch.
- * Models that genuinely support xhigh (registry flag supportsXHighEffort)
- * pass through unchanged.
+ * Models that genuinely support xhigh pass through unchanged. Claude models
+ * default to xhigh support unless they are marked as legacy unsupported entries.
  */
 const MISTRAL_NO_REASONING_EFFORT_PATTERN = /devstral/i;
 const GITHUB_NO_REASONING_EFFORT_PATTERN = /(claude|haiku|oswe)/i;
diff --git a/open-sse/services/claudeCodeCompatible.ts b/open-sse/services/claudeCodeCompatible.ts
index 1c589b09b0..4972f21835 100644
--- a/open-sse/services/claudeCodeCompatible.ts
+++ b/open-sse/services/claudeCodeCompatible.ts
@@ -51,7 +51,7 @@ const CLAUDE_CODE_COMPATIBLE_DEFAULT_SYSTEM_BLOCKS = [
     text: "You are a Claude agent, built on Anthropic's Claude Agent SDK.",
   },
 ];
-const CONTEXT_1M_SUPPORTED_MODELS = ["claude-opus-4-7", "claude-opus-4-6"];
+const CONTEXT_1M_SUPPORTED_MODELS = ["claude-opus-4-8", "claude-opus-4-7", "claude-opus-4-6"];
 export const CLAUDE_CODE_COMPATIBLE_STAINLESS_TIMEOUT_SECONDS = getStainlessTimeoutSeconds(
   process.env
 );
diff --git a/open-sse/services/modelFamilyFallback.ts b/open-sse/services/modelFamilyFallback.ts
index 50d30f7617..06f2d4d05a 100644
--- a/open-sse/services/modelFamilyFallback.ts
+++ b/open-sse/services/modelFamilyFallback.ts
@@ -73,6 +73,7 @@ const MODEL_FAMILIES: Record<string, string[]> = {
   "gemini-2.5-pro-preview-06-05": ["gemini-2.5-pro", "gemini-2.5-pro-exp-03-25"],
 
   // Claude Opus family
+  "claude-opus-4-8": ["claude-opus-4-7", "claude-opus-4-6", "claude-sonnet-4-6"],
   "claude-opus-4-7": ["claude-opus-4-6", "claude-opus-4-5-20251101", "claude-sonnet-4-6"],
   "claude-opus-4-6": ["claude-opus-4-6-thinking", "claude-opus-4-5-20251101", "claude-sonnet-4-6"],
   "claude-opus-4-6-thinking": ["claude-opus-4-6", "claude-opus-4-5-20251101"],
diff --git a/open-sse/services/providerCostData.ts b/open-sse/services/providerCostData.ts
index 98e668db89..7397b4641f 100644
--- a/open-sse/services/providerCostData.ts
+++ b/open-sse/services/providerCostData.ts
@@ -11,6 +11,7 @@ export interface ModelPricing {
 export const KNOWN_MODEL_PRICING: Record<string, ModelPricing> = {
   "gpt-4o": { inputCostPer1M: 2.5, outputCostPer1M: 10.0, isFree: false },
   "gpt-4o-mini": { inputCostPer1M: 0.15, outputCostPer1M: 0.6, isFree: false },
+  "claude-opus-4-8": { inputCostPer1M: 15.0, outputCostPer1M: 75.0, isFree: false },
   "claude-opus-4-7": { inputCostPer1M: 15.0, outputCostPer1M: 75.0, isFree: false },
   "claude-sonnet-4-6": { inputCostPer1M: 3.0, outputCostPer1M: 15.0, isFree: false },
   "claude-haiku-4-5": { inputCostPer1M: 0.8, outputCostPer1M: 4.0, isFree: false },
diff --git a/src/lib/db/settings.ts b/src/lib/db/settings.ts
index c9cbe957f7..8dcd735648 100644
--- a/src/lib/db/settings.ts
+++ b/src/lib/db/settings.ts
@@ -103,7 +103,10 @@ export async function getSettings() {
     autoRefreshProviderQuotaInterval: 180,
     comboConfigMode: "guided",
     codexServiceTier: { enabled: false },
-    claudeFastMode: { enabled: false, supportedModels: ["claude-opus-4-7", "claude-opus-4-6"] },
+    claudeFastMode: {
+      enabled: false,
+      supportedModels: ["claude-opus-4-8", "claude-opus-4-7", "claude-opus-4-6"],
+    },
     codexSessionAffinityTtlMs: 0,
     alwaysPreserveClientCache: "auto",
     idempotencyWindowMs: 5000,
diff --git a/src/lib/providers/claudeFastMode.ts b/src/lib/providers/claudeFastMode.ts
index 9d2e7632fe..2418426198 100644
--- a/src/lib/providers/claudeFastMode.ts
+++ b/src/lib/providers/claudeFastMode.ts
@@ -6,7 +6,11 @@ type JsonRecord = Record<string, unknown>;
  * Mirrors the binary-side gate observed in claude-code v2.1.145 (KT() check):
  * only the latest Opus tiers can request the priority service path.
  */
-export const CLAUDE_FAST_MODE_DEFAULT_MODELS = ["claude-opus-4-7", "claude-opus-4-6"] as const;
+export const CLAUDE_FAST_MODE_DEFAULT_MODELS = [
+  "claude-opus-4-8",
+  "claude-opus-4-7",
+  "claude-opus-4-6",
+] as const;
 
 function asRecord(value: unknown): JsonRecord {
   return value && typeof value === "object" && !Array.isArray(value) ? (value as JsonRecord) : {};
@@ -39,7 +43,7 @@ export function isClaudeFastModeEnabled(settings: unknown): boolean {
 
 /**
  * Returns the configured supported-model list, defaulting to the conservative
- * Opus 4-7 / 4-6 pair (matches the binary KT() gate).
+ * Opus 4-8 / 4-7 / 4-6 set.
  */
 export function getClaudeFastModeSupportedModels(settings: unknown): string[] {
   const record = asRecord(settings);
@@ -51,7 +55,7 @@ export function getClaudeFastModeSupportedModels(settings: unknown): string[] {
 
 /**
  * True when the toggle is on AND the model id prefix-matches a supported model.
- * Prefix matching tolerates dated suffixes (e.g. claude-opus-4-7-20260201).
+ * Prefix matching tolerates dated suffixes (e.g. claude-opus-4-8-20260528).
  */
 export function shouldRequestClaudeFastMode(
   settings: unknown,
diff --git a/src/lib/providers/staticModels.ts b/src/lib/providers/staticModels.ts
index 4c2db473b4..6e17464449 100644
--- a/src/lib/providers/staticModels.ts
+++ b/src/lib/providers/staticModels.ts
@@ -37,6 +37,7 @@ const STATIC_MODEL_PROVIDERS: Record<string, () => Array<{ id: string; name: str
   ],
   antigravity: () => ANTIGRAVITY_PUBLIC_MODELS.map((model) => ({ ...model })),
   claude: () => [
+    { id: "claude-opus-4-8", name: "Claude Opus 4.8" },
     { id: "claude-opus-4-7", name: "Claude Opus 4.7" },
     { id: "claude-opus-4-6", name: "Claude Opus 4.6" },
     { id: "claude-sonnet-4-6", name: "Claude Sonnet 4.6" },
diff --git a/src/shared/constants/modelSpecs.ts b/src/shared/constants/modelSpecs.ts
index 7af781da61..ff766f2431 100644
--- a/src/shared/constants/modelSpecs.ts
+++ b/src/shared/constants/modelSpecs.ts
@@ -187,6 +187,20 @@ export const MODEL_SPECS: Record<string, ModelSpec> = {
     aliases: BEDROCK_CLAUDE_ALIASES("claude-opus-4-7", "claude-opus-4.7"),
   },
 
+  // ── Claude Opus 4.8 ─────────────────────────────────────────────
+  "claude-opus-4-8": {
+    maxOutputTokens: 128000,
+    contextWindow: 1000000,
+    // Opus 4.8 inherits Opus 4.7's adaptive thinking constraints: no fixed
+    // thinking budget requests, with effort controlled by output_config.
+    defaultThinkingBudget: 32000,
+    thinkingBudgetCap: 120000,
+    supportsThinking: true,
+    supportsTools: true,
+    supportsVision: true,
+    aliases: BEDROCK_CLAUDE_ALIASES("claude-opus-4-8", "claude-opus-4.8"),
+  },
+
   // ── Claude Sonnet 4.5 ───────────────────────────────────────────
   "claude-sonnet-4-5-20250929": {
     maxOutputTokens: 64000,
diff --git a/src/shared/constants/pricing.ts b/src/shared/constants/pricing.ts
index 93b34a0e9f..e91703b036 100644
--- a/src/shared/constants/pricing.ts
+++ b/src/shared/constants/pricing.ts
@@ -129,6 +129,13 @@ export const DEFAULT_PRICING = {
 
   // Claude Code (cc)
   cc: {
+    "claude-opus-4-8": {
+      input: 5.0,
+      output: 25.0,
+      cached: 2.5,
+      reasoning: 25.0,
+      cache_creation: 5.0,
+    },
     "claude-opus-4-7": {
       input: 5.0,
       output: 25.0,
@@ -710,6 +717,9 @@ export const DEFAULT_PRICING = {
     // Common model IDs (without dates) used across providers
     // Intentional duplicates of dot-notation variants (e.g. claude-opus-4.6)
     // to cover hyphen-notation IDs (claude-opus-4-6) used by some clients
+    "claude-opus-4.8": CLAUDE_OPUS_4_PRICING,
+    "claude-opus-4-8": CLAUDE_OPUS_4_PRICING,
+    "claude-opus-4-7": CLAUDE_OPUS_4_PRICING,
     "claude-opus-4-6": CLAUDE_OPUS_46_PRICING,
     "claude-sonnet-4-6": CLAUDE_SONNET_46_PRICING,
     "claude-opus-4-5-20251101": CLAUDE_OPUS_4_PRICING,
diff --git a/tests/unit/base-executor-sanitize-effort.test.ts b/tests/unit/base-executor-sanitize-effort.test.ts
index 2fafe80611..abb0930595 100644
--- a/tests/unit/base-executor-sanitize-effort.test.ts
+++ b/tests/unit/base-executor-sanitize-effort.test.ts
@@ -101,8 +101,8 @@ test("sanitizeReasoningEffortForProvider: mistral/devstral preserves reasoning w
 });
 
 test("sanitizeReasoningEffortForProvider: codex with xhigh passes through unchanged when model supports it", () => {
-  // codex/gpt-5.5-xhigh and related Claude opus models are flagged
-  // supportsXHighEffort:true in providerRegistry. They must not be downgraded.
+  // codex/gpt-5.5-xhigh is flagged supportsXHighEffort:true in providerRegistry.
+  // Claude Opus 4.7+ models default to xhigh support unless explicitly opted out.
   const body = {
     model: "gpt-5.5-xhigh",
     reasoning_effort: "xhigh",
diff --git a/tests/unit/cc-compatible-provider.test.ts b/tests/unit/cc-compatible-provider.test.ts
index 5eac9493c8..47cc5ad958 100644
--- a/tests/unit/cc-compatible-provider.test.ts
+++ b/tests/unit/cc-compatible-provider.test.ts
@@ -18,7 +18,8 @@ const {
   CLAUDE_CODE_COMPATIBLE_DEFAULT_MODELS_PATH,
   joinClaudeCodeCompatibleUrl,
 } = await import("../../open-sse/services/claudeCodeCompatible.ts");
-const { getModelsByProviderId } = await import("../../open-sse/config/providerModels.ts");
+const { getModelsByProviderId, supportsXHighEffort } =
+  await import("../../open-sse/config/providerModels.ts");
 const { handleChatCore } = await import("../../open-sse/handlers/chatCore.ts");
 const { validateProviderApiKey } = await import("../../src/lib/providers/validation.ts");
 const providerNodesRoute = await import("../../src/app/api/provider-nodes/route.ts");
@@ -144,8 +145,8 @@ test("buildClaudeCodeCompatibleRequest keeps prior role history while dropping t
 });
 
 test("buildClaudeCodeCompatibleRequest preserves xhigh for Claude models that support it", () => {
-  const xhighModel = getModelsByProviderId("claude").find(
-    (model) => model.supportsXHighEffort === true
+  const xhighModel = getModelsByProviderId("claude").find((model) =>
+    supportsXHighEffort("claude", model.id)
   );
   assert.ok(xhighModel, "expected at least one Claude model with xhigh support");
   const payload = buildClaudeCodeCompatibleRequest({
diff --git a/tests/unit/claude-code-compatible-request.test.ts b/tests/unit/claude-code-compatible-request.test.ts
index 67057a4fa0..13ece0f7b3 100644
--- a/tests/unit/claude-code-compatible-request.test.ts
+++ b/tests/unit/claude-code-compatible-request.test.ts
@@ -11,12 +11,15 @@ const {
   resolveClaudeCodeCompatibleMaxTokens,
   buildClaudeCodeCompatibleRequest,
 } = await import("../../open-sse/services/claudeCodeCompatible.ts");
-const { getModelsByProviderId } = await import("../../open-sse/config/providerModels.ts");
+const { getModelsByProviderId, supportsXHighEffort } =
+  await import("../../open-sse/config/providerModels.ts");
 
 function getClaudeEffortFixtures() {
   const claudeModels = getModelsByProviderId("claude");
-  const xhighModel = claudeModels.find((model) => model.supportsXHighEffort === true);
-  const standardModel = claudeModels.find((model) => model.supportsXHighEffort === false);
+  const xhighModel = claudeModels.find((model) => supportsXHighEffort("claude", model.id));
+  const standardModel = claudeModels.find(
+    (model) => supportsXHighEffort("claude", model.id) === false
+  );
   assert.ok(xhighModel, "expected at least one Claude model with xhigh support");
   assert.ok(standardModel, "expected at least one Claude model without xhigh support");
   return { xhighModel, standardModel };
diff --git a/tests/unit/claude-fast-mode.test.ts b/tests/unit/claude-fast-mode.test.ts
new file mode 100644
index 0000000000..92b6be05e2
--- /dev/null
+++ b/tests/unit/claude-fast-mode.test.ts
@@ -0,0 +1,73 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+const {
+  shouldRequestClaudeFastMode,
+  CLAUDE_FAST_MODE_DEFAULT_MODELS,
+  getClaudeFastModeSupportedModels,
+  isClaudeFastModeEnabled,
+} = await import("../../src/lib/providers/claudeFastMode.ts");
+
+const enabledSettings = { claudeFastMode: true };
+const disabledSettings = { claudeFastMode: false };
+
+test("shouldRequestClaudeFastMode returns false when fast mode is disabled", () => {
+  assert.equal(shouldRequestClaudeFastMode(disabledSettings, "claude-opus-4-8"), false);
+  assert.equal(shouldRequestClaudeFastMode({}, "claude-opus-4-8"), false);
+  assert.equal(shouldRequestClaudeFastMode(null, "claude-opus-4-8"), false);
+});
+
+test("shouldRequestClaudeFastMode returns false for non-string or empty modelId", () => {
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, null), false);
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, undefined), false);
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, ""), false);
+});
+
+test("shouldRequestClaudeFastMode returns true for claude-opus-4-8 exact match", () => {
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, "claude-opus-4-8"), true);
+});
+
+test("shouldRequestClaudeFastMode prefix-matches claude-opus-4-8 with dated suffix", () => {
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, "claude-opus-4-8-20260528"), true);
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, "claude-opus-4-8-20260101"), true);
+});
+
+test("shouldRequestClaudeFastMode returns true for claude-opus-4-7 and claude-opus-4-6", () => {
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, "claude-opus-4-7"), true);
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, "claude-opus-4-6"), true);
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, "claude-opus-4-7-20250101"), true);
+});
+
+test("shouldRequestClaudeFastMode returns false for non-Opus models", () => {
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, "claude-sonnet-4-6"), false);
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, "claude-haiku-4-5"), false);
+  assert.equal(shouldRequestClaudeFastMode(enabledSettings, "gpt-4o"), false);
+});
+
+test("CLAUDE_FAST_MODE_DEFAULT_MODELS includes claude-opus-4-8", () => {
+  assert.ok(
+    CLAUDE_FAST_MODE_DEFAULT_MODELS.includes("claude-opus-4-8"),
+    "claude-opus-4-8 must be in CLAUDE_FAST_MODE_DEFAULT_MODELS"
+  );
+});
+
+test("getClaudeFastModeSupportedModels returns default list when none configured", () => {
+  const models = getClaudeFastModeSupportedModels({});
+  assert.ok(models.includes("claude-opus-4-8"));
+  assert.ok(models.includes("claude-opus-4-7"));
+  assert.ok(models.includes("claude-opus-4-6"));
+});
+
+test("getClaudeFastModeSupportedModels respects custom override list", () => {
+  const settings = { claudeFastMode: { enabled: true, supportedModels: ["my-custom-model"] } };
+  const models = getClaudeFastModeSupportedModels(settings);
+  assert.deepEqual(models, ["my-custom-model"]);
+});
+
+test("isClaudeFastModeEnabled handles boolean and object shape", () => {
+  assert.equal(isClaudeFastModeEnabled({ claudeFastMode: true }), true);
+  assert.equal(isClaudeFastModeEnabled({ claudeFastMode: false }), false);
+  assert.equal(isClaudeFastModeEnabled({ claudeFastMode: { enabled: true } }), true);
+  assert.equal(isClaudeFastModeEnabled({ claudeFastMode: { enabled: false } }), false);
+  assert.equal(isClaudeFastModeEnabled({}), false);
+});
diff --git a/tests/unit/provider-models-config.test.ts b/tests/unit/provider-models-config.test.ts
index 5628140cbb..d992860f3e 100644
--- a/tests/unit/provider-models-config.test.ts
+++ b/tests/unit/provider-models-config.test.ts
@@ -10,6 +10,7 @@ import {
   getModelsByProviderId,
   getProviderModels,
   isValidModel,
+  supportsXHighEffort,
 } from "../../open-sse/config/providerModels.ts";
 
 test("provider models helpers expose model lists and defaults", () => {
@@ -90,3 +91,14 @@ test("Kiro registry exposes the current CLI model lineup with context windows",
   assert.equal(byId.has("claude-sonnet-4-6"), false);
   assert.equal(byId.has("claude-haiku-4-5"), false);
 });
+
+test("Claude xhigh effort support defaults on for new models and opts out legacy models", () => {
+  const claudeModels = new Set(getModelsByProviderId("claude").map((model) => model.id));
+
+  assert.ok(claudeModels.has("claude-opus-4-8"));
+  assert.equal(supportsXHighEffort("claude", "claude-opus-4-8"), true);
+  assert.equal(supportsXHighEffort("claude", "claude-opus-4-7"), true);
+  assert.equal(supportsXHighEffort("claude", "claude-opus-4-6"), false);
+  assert.equal(supportsXHighEffort("claude", "claude-sonnet-4-6"), false);
+  assert.equal(supportsXHighEffort("claude", "claude-future-5-0"), true);
+});
diff --git a/tests/unit/t12-pricing-updates.test.ts b/tests/unit/t12-pricing-updates.test.ts
index 0415ba4237..e15a907f6f 100644
--- a/tests/unit/t12-pricing-updates.test.ts
+++ b/tests/unit/t12-pricing-updates.test.ts
@@ -27,6 +27,10 @@ test("T12: pricing table includes MiniMax, GLM, Kimi and gpt-5.4 mini entries",
   assert.ok(pricing.kimi["kimi-k2.5"], "missing kimi/kimi-k2.5");
   assert.ok(pricing.kimi["kimi-k2.5-thinking"], "missing kimi/kimi-k2.5-thinking");
   assert.ok(pricing.kimi["kimi-for-coding"], "missing kimi/kimi-for-coding");
+
+  assert.ok(pricing.anthropic["claude-opus-4.8"], "missing anthropic/claude-opus-4.8");
+  assert.ok(pricing.anthropic["claude-opus-4-8"], "missing anthropic/claude-opus-4-8");
+  assert.ok(pricing.anthropic["claude-opus-4-7"], "missing anthropic/claude-opus-4-7");
 });
 
 test("T12: codex catalog includes GPT 5.5 variations", () => {
diff --git a/tests/unit/t31-t33-t34-t38-model-specs.test.ts b/tests/unit/t31-t33-t34-t38-model-specs.test.ts
index ef0175557b..ad455dec5c 100644
--- a/tests/unit/t31-t33-t34-t38-model-specs.test.ts
+++ b/tests/unit/t31-t33-t34-t38-model-specs.test.ts
@@ -49,6 +49,7 @@ test("T34: max output tokens are capped by model spec", () => {
   assert.equal(capMaxOutputTokens("gemini-3-flash", 131072), 65536);
   assert.equal(capMaxOutputTokens("gemini-3-flash"), 65536);
   assert.equal(capMaxOutputTokens("gemini-3.1-pro-high", 131072), 65535);
+  assert.equal(capMaxOutputTokens("claude-opus-4-8", 200000), 128000);
   assert.equal(capMaxOutputTokens("claude-opus-4-7", 200000), 128000);
   assert.equal(capMaxOutputTokens("anthropic.claude-sonnet-4-6", 200000), 64000);
   assert.equal(capMaxOutputTokens("eu.anthropic.claude-opus-4-6", 200000), 128000);
@@ -64,6 +65,7 @@ test("T38: modelSpecs exposes centralized helpers with alias and prefix lookup",
   assert.equal(getModelSpec("gemini-3.1-pro-preview").maxOutputTokens, 65535);
   assert.equal(getModelSpec("gemini-3.1-pro-preview-customtools").maxOutputTokens, 65535);
   assert.equal(getModelSpec("claude-opus-4-7").contextWindow, 1000000);
+  assert.equal(getModelSpec("claude-opus-4.8").maxOutputTokens, 128000);
   assert.equal(getModelSpec("claude-opus-4.7").maxOutputTokens, 128000);
   assert.equal(getModelSpec("bedrock/eu.anthropic.claude-sonnet-4-6").contextWindow, 1000000);
   assert.equal(getModelSpec("bedrock/anthropic.claude-sonnet-4-5").contextWindow, 200000);
diff --git a/tests/unit/translator-openai-to-claude.test.ts b/tests/unit/translator-openai-to-claude.test.ts
index 579316bba3..36ab95f3f2 100644
--- a/tests/unit/translator-openai-to-claude.test.ts
+++ b/tests/unit/translator-openai-to-claude.test.ts
@@ -11,12 +11,15 @@ const {
 const { CLAUDE_SYSTEM_PROMPT } = await import("../../open-sse/config/constants.ts");
 const { DEFAULT_THINKING_CLAUDE_SIGNATURE } =
   await import("../../open-sse/config/defaultThinkingSignature.ts");
-const { getModelsByProviderId } = await import("../../open-sse/config/providerModels.ts");
+const { getModelsByProviderId, supportsXHighEffort } =
+  await import("../../open-sse/config/providerModels.ts");
 
 function getClaudeEffortFixtures() {
   const claudeModels = getModelsByProviderId("claude");
-  const xhighModel = claudeModels.find((model) => model.supportsXHighEffort === true);
-  const standardModel = claudeModels.find((model) => model.supportsXHighEffort === false);
+  const xhighModel = claudeModels.find((model) => supportsXHighEffort("claude", model.id));
+  const standardModel = claudeModels.find(
+    (model) => supportsXHighEffort("claude", model.id) === false
+  );
   assert.ok(xhighModel, "expected at least one Claude model with xhigh support");
   assert.ok(standardModel, "expected at least one Claude model without xhigh support");
   return { xhighModel, standardModel };