Merge pull request #797 from jbaehova/agent/fix-cursor-grok-fast-wire-ids

Verified locally on top of origin/dev alongside #808: typecheck clean, 214 targeted tests pass (cursor-discovery, cursor-effort-suffix, cursor-request-builder, adapter-resolve, router, config, repo-hygiene), privacy:scan green.

Author: lidge-jun

src/adapters/cursor/discovery.ts

@@ -1,4 +1,8 @@
-import { CANONICAL_EFFORT_SUFFIXES, cursorModelEffortLadder } from "./effort-map";
+import {
+  CANONICAL_EFFORT_SUFFIXES,
+  cursorModelEffortLadder,
+  cursorWireModelIdWithEffort,
+} from "./effort-map";
 
 export interface CursorModelInfo {
   id: string;
@@ -66,14 +70,20 @@ function stripCursorWirePrefix(id: string): string {
 
 /**
  * True when a configured Cursor base model should remain exposed after live GetUsableModels filtering.
- * Live ids are full effort-suffixed variants (`claude-4.6-opus-high`); base ids match exactly or by prefix.
+ * Live ids are full effort-suffixed variants (`claude-4.6-opus-high`); base ids match exactly, the
+ * ordinary `{base}-{effort}` form, or Cursor's current `{base-without-fast}-{effort}-fast` form.
  */
 export function isCursorModelAvailableForAccount(modelId: string, liveIds: readonly string[]): boolean {
   return liveIds.some(raw => {
     const id = stripCursorWirePrefix(raw);
     if (id === modelId) return true;
-    const effortPrefix = `${modelId}-`;
-    return id.startsWith(effortPrefix) && CANONICAL_EFFORT_SUFFIXES.has(id.slice(effortPrefix.length));
+    for (const effort of CANONICAL_EFFORT_SUFFIXES) {
+      if (
+        id === `${modelId}-${effort}` ||
+        id === cursorWireModelIdWithEffort(modelId, effort)
+      ) return true;
+    }
+    return false;
   });
 }
 

src/adapters/cursor/effort-map.ts

@@ -3,8 +3,9 @@
  *
  * Cursor model ids encode the reasoning effort as a suffix (`claude-4.6-opus-high`), and the available
  * tiers differ per model — `claude-4.6-opus` tops out at `-max`, `claude-opus-4-8` at `-xhigh`,
- * `claude-4.6-sonnet` only has `-medium`, and `composer`/`grok`/`gemini` take no suffix at all. A bare
- * id for a model that requires a suffix is rejected `ERROR_BAD_MODEL_NAME` (devlog 350.105).
+ * `claude-4.6-sonnet` only has `-medium`, and most `composer`/`gemini` models take no suffix at all.
+ * Grok Fast puts its mode marker after the effort (`grok-4.5-high-fast`). A bare id for a model that
+ * requires a suffix is rejected `ERROR_BAD_MODEL_NAME` (devlog 350.105).
  *
  * Canonical effort order is always low < medium < high < xhigh < max (max is the top tier, confirmed
  * against Anthropic docs and Cursor's live lineup). Tiers are stored in ascending canonical order.
@@ -30,10 +31,10 @@ const CURSOR_MODEL_EFFORT_TIERS: Record<string, readonly string[]> = {
   // GetUsableModels (2026-07-28) lists kimi-k3 only as effort-suffixed kimi-k3-{low,high,max};
   // the bare id returns not_found. Tiers mirror the native Kimi provider's K3 ladder.
   "kimi-k3": ["low", "high", "max"],
-  // GetUsableModels (2026-07-09) lists grok-4.5-{medium,high,xhigh} and grok-4.5-fast-{medium,high,xhigh};
-  // the bare "grok-4.5-fast" id was removed upstream and now returns not_found.
-  "grok-4.5": ["medium", "high", "xhigh"],
-  "grok-4.5-fast": ["medium", "high", "xhigh"],
+  // Cursor renamed the Grok 4.5 slugs to cursor-grok-4.5-{low,medium,high} and
+  // cursor-grok-4.5-{low,medium,high}-fast. The bare Fast id returns not_found.
+  "grok-4.5": ["low", "medium", "high"],
+  "grok-4.5-fast": ["low", "medium", "high"],
   "gpt-5.1": ["low", "high"],
   "gpt-5.1-codex-max": ["low", "medium", "high", "xhigh"],
   "gpt-5.1-codex-mini": ["low", "high"],
@@ -113,3 +114,14 @@ export function cursorModelEffortLadder(baseModelId: string): string[] | undefin
 export function cursorModelHasEffortTiers(baseModelId: string): boolean {
   return (CURSOR_MODEL_EFFORT_TIERS[baseModelId]?.length ?? 0) > 0;
 }
+
+/**
+ * Compose a Cursor wire id from a Codex-facing base id and effort tier.
+ * Fast variants put the mode after the effort; other models use the ordinary `{base}-{effort}` form.
+ */
+export function cursorWireModelIdWithEffort(baseModelId: string, effortSuffix: string): string {
+  if (baseModelId.endsWith("-fast")) {
+    return `${baseModelId.slice(0, -"-fast".length)}-${effortSuffix}-fast`;
+  }
+  return `${baseModelId}-${effortSuffix}`;
+}

src/adapters/cursor/request-builder.ts

@@ -10,7 +10,7 @@ import type {
 import { isAllowedToolChoice, namespacedToolName, toolChoiceAliases, type OcxTool, type OcxToolChoice } from "../../types";
 import type { CursorRequestMessage, CursorRunRequest } from "./types";
 import { cursorWireModelSelection, type CursorRoutingLevel } from "./discovery";
-import { cursorEffortSuffix } from "./effort-map";
+import { cursorEffortSuffix, cursorWireModelIdWithEffort } from "./effort-map";
 import {
   cursorMcpToolEncodedSize,
   cursorMcpToolsEncodedSize,
@@ -127,7 +127,7 @@ function normalizeCursorModelId(modelId: string, reasoning?: string): { modelId:
   const selection = cursorWireModelSelection(modelId);
   const id = selection.modelId;
   const suffix = cursorEffortSuffix(id, reasoning);
-  return { ...selection, modelId: suffix ? `${id}-${suffix}` : id };
+  return { ...selection, modelId: suffix ? cursorWireModelIdWithEffort(id, suffix) : id };
 }
 
 function contentPartToText(part: OcxContentPart | OcxAssistantContentPart): string | undefined {

tests/cursor-discovery.test.ts

@@ -63,7 +63,13 @@ describe("Cursor discovery metadata", () => {
 
     // Issue #117: Cursor GetUsableModels may return ids with a `cursor-` wire prefix.
     expect(isCursorModelAvailableForAccount("grok-4.5", ["cursor-grok-4.5-high"])).toBe(true);
+    // Current Grok Fast wire ids put `-fast` after the effort tier.
+    expect(isCursorModelAvailableForAccount("grok-4.5-fast", ["cursor-grok-4.5-low-fast"])).toBe(true);
+    expect(isCursorModelAvailableForAccount("grok-4.5-fast", ["cursor-grok-4.5-high-fast"])).toBe(true);
+    // Older snapshots used `{base}-fast-{effort}`; keep discovery compatibility.
     expect(isCursorModelAvailableForAccount("grok-4.5-fast", ["cursor-grok-4.5-fast-medium"])).toBe(true);
+    expect(isCursorModelAvailableForAccount("grok-4.5-fast", ["cursor-grok-4.5-high"])).toBe(false);
+    expect(isCursorModelAvailableForAccount("grok-4.5", ["cursor-grok-4.5-high-fast"])).toBe(false);
     expect(isCursorModelAvailableForAccount("gpt-5.4", ["cursor-gpt-5.4-high"])).toBe(true);
     // Prefixed sibling rejection: cursor- prefix must not bypass sibling-model checks.
     expect(isCursorModelAvailableForAccount("gpt-5.5", ["cursor-gpt-5.5-extra-high"])).toBe(false);
@@ -74,6 +80,12 @@ describe("Cursor discovery metadata", () => {
       ["gpt-5.4-high"],
     );
     expect(filtered.map(model => model.id)).toEqual(["gpt-5.4"]);
+
+    const grok = filterCursorConfiguredModelsByLiveDiscovery(
+      [{ id: "grok-4.5" }, { id: "grok-4.5-fast" }],
+      ["cursor-grok-4.5-high", "cursor-grok-4.5-high-fast"],
+    );
+    expect(grok.map(model => model.id)).toEqual(["grok-4.5", "grok-4.5-fast"]);
   });
 
   test("live discovery filter always keeps all router levels when GetUsableModels omits them", () => {

tests/cursor-effort-suffix.test.ts

@@ -60,10 +60,20 @@ describe("Cursor per-model reasoning-effort suffix", () => {
     expect(modelIdFor("cursor/glm-5.2", "max")).toBe("glm-5.2-max");
   });
 
-  test("grok-4.5-fast preserves its explicit code-backed tiers", () => {
-    expect(modelIdFor("cursor/grok-4.5-fast", "medium")).toBe("grok-4.5-fast-medium");
-    expect(modelIdFor("cursor/grok-4.5-fast", "high")).toBe("grok-4.5-fast-high");
-    expect(modelIdFor("cursor/grok-4.5-fast", "xhigh")).toBe("grok-4.5-fast-xhigh");
+  test("grok-4.5 uses current low/medium/high tiers and trailing Fast wire ids", () => {
+    expect(modelIdFor("cursor/grok-4.5", "low")).toBe("grok-4.5-low");
+    expect(modelIdFor("cursor/grok-4.5", "medium")).toBe("grok-4.5-medium");
+    expect(modelIdFor("cursor/grok-4.5", "high")).toBe("grok-4.5-high");
+    expect(modelIdFor("cursor/grok-4.5", "xhigh")).toBe("grok-4.5-high");
+    expect(modelIdFor("cursor/grok-4.5")).toBe("grok-4.5-high");
+    expect(modelIdFor("cursor/grok-4.5-fast", "low")).toBe("grok-4.5-low-fast");
+    expect(modelIdFor("cursor/grok-4.5-fast", "medium")).toBe("grok-4.5-medium-fast");
+    expect(modelIdFor("cursor/grok-4.5-fast", "high")).toBe("grok-4.5-high-fast");
+    // Codex-only upper tiers and an omitted effort clamp to Cursor's current top tier.
+    expect(modelIdFor("cursor/grok-4.5-fast", "xhigh")).toBe("grok-4.5-high-fast");
+    expect(modelIdFor("cursor/grok-4.5-fast")).toBe("grok-4.5-high-fast");
+    expect(cursorModelEffortLadder("grok-4.5")).toEqual(["low", "medium", "high"]);
+    expect(cursorModelEffortLadder("grok-4.5-fast")).toEqual(["low", "medium", "high"]);
   });
 
   test("kimi-k3 maps to its live effort-suffixed variants", () => {