diff --git a/.chronus/changes/add-single-word-model-name-rule-2026-7-7-19-30-0.md b/.chronus/changes/add-single-word-model-name-rule-2026-7-7-19-30-0.md
new file mode 100644
index 0000000000..7b02337cb1
--- /dev/null
+++ b/.chronus/changes/add-single-word-model-name-rule-2026-7-7-19-30-0.md
@@ -0,0 +1,8 @@
+---
+changeKind: feature
+packages:
+  - "@azure-tools/typespec-client-generator-core"
+  - "@azure-tools/typespec-azure-rulesets"
+---
+
+Add `csharp-no-single-word-model-name` linter rule for C# SDK model naming, with optional AI-powered quick fix suggestions in editors.
diff --git a/core b/core
index 6b421a5cbc..ed8c1ebdc4 160000
--- a/core
+++ b/core
@@ -1 +1 @@
-Subproject commit 6b421a5cbc59583cc9c52f3e180196816071bc1a
+Subproject commit ed8c1ebdc4b95a1019b75688d31fbf87d82f36a0
diff --git a/packages/typespec-azure-rulesets/src/rulesets/client-sdk.ts b/packages/typespec-azure-rulesets/src/rulesets/client-sdk.ts
index de55e0c3c4..e6c8b9cb9b 100644
--- a/packages/typespec-azure-rulesets/src/rulesets/client-sdk.ts
+++ b/packages/typespec-azure-rulesets/src/rulesets/client-sdk.ts
@@ -5,5 +5,6 @@ import type { LinterRuleSet } from "@typespec/compiler";
 export default {
   enable: {
     "@azure-tools/typespec-client-generator-core/csharp-no-url-suffix": true,
+    "@azure-tools/typespec-client-generator-core/csharp-no-single-word-model-name": true,
   },
 } satisfies LinterRuleSet;
diff --git a/packages/typespec-azure-rulesets/test/validate-rules-defined.test.ts b/packages/typespec-azure-rulesets/test/validate-rules-defined.test.ts
index 67f682e4e5..20d6f12d89 100644
--- a/packages/typespec-azure-rulesets/test/validate-rules-defined.test.ts
+++ b/packages/typespec-azure-rulesets/test/validate-rules-defined.test.ts
@@ -51,9 +51,14 @@ describe("expect all rules to be defined", () => {
     });
   });
 
-  it("client-sdk enables csharp-no-url-suffix", () => {
+  it("client-sdk enables client SDK rules", () => {
     const ruleset = $linter.ruleSets?.["client-sdk"];
     ok(ruleset);
     ok(ruleset.enable?.["@azure-tools/typespec-client-generator-core/csharp-no-url-suffix"]);
+    ok(
+      ruleset.enable?.[
+        "@azure-tools/typespec-client-generator-core/csharp-no-single-word-model-name"
+      ],
+    );
   });
 });
diff --git a/packages/typespec-client-generator-core/src/linter.ts b/packages/typespec-client-generator-core/src/linter.ts
index 912283c4f8..8f5156ad7a 100644
--- a/packages/typespec-client-generator-core/src/linter.ts
+++ b/packages/typespec-client-generator-core/src/linter.ts
@@ -1,4 +1,5 @@
 import { defineLinter } from "@typespec/compiler";
+import { csharpNoSingleWordModelNameRule } from "./rules/csharp-no-single-word-model-name.js";
 import { csharpNoUrlSuffixRule } from "./rules/csharp-no-url-suffix.js";
 import { noUnnamedTypesRule } from "./rules/no-unnamed-types.rule.js";
 import { propertyNameConflictRule } from "./rules/property-name-conflict.rule.js";
@@ -9,9 +10,14 @@ const rules = [
   propertyNameConflictRule,
   noUnnamedTypesRule,
   csharpNoUrlSuffixRule,
+  csharpNoSingleWordModelNameRule,
 ];
 
-const csharpRules = [propertyNameConflictRule, csharpNoUrlSuffixRule];
+const csharpRules = [
+  propertyNameConflictRule,
+  csharpNoUrlSuffixRule,
+  csharpNoSingleWordModelNameRule,
+];
 
 export const $linter = defineLinter({
   rules,
diff --git a/packages/typespec-client-generator-core/src/rules/csharp-no-single-word-model-name.ts b/packages/typespec-client-generator-core/src/rules/csharp-no-single-word-model-name.ts
new file mode 100644
index 0000000000..34424a8451
--- /dev/null
+++ b/packages/typespec-client-generator-core/src/rules/csharp-no-single-word-model-name.ts
@@ -0,0 +1,199 @@
+import {
+  CodeFix,
+  Model,
+  Program,
+  createRule,
+  getDoc,
+  getNamespaceFullName,
+  getSourceLocation,
+  paramMessage,
+} from "@typespec/compiler";
+import { SyntaxKind } from "@typespec/compiler/ast";
+import { createTCGCContext } from "../context.js";
+import { getLibraryName } from "../public-utils.js";
+import { createClientTspAugmentDecoratorCodeFix } from "./codefix-helpers.js";
+
+interface ChatCompletionConnection {
+  sendRequest(
+    requestName: "custom/chatCompletion",
+    params: {
+      messages: { role: "user"; message: string }[];
+      modelFamily: string;
+      id: string;
+    },
+  ): Promise<string | undefined>;
+}
+
+interface DynamicCodeFix extends CodeFix {
+  resolveCodefixes?: () => Promise<CodeFix[]>;
+}
+
+function splitPascalCase(name: string): string[] {
+  const words: string[] = [];
+  let current = "";
+
+  for (let i = 0; i < name.length; i++) {
+    const char = name[i];
+    const isUpper = char >= "A" && char <= "Z";
+    const nextIsLower = i + 1 < name.length && name[i + 1] >= "a" && name[i + 1] <= "z";
+
+    if (isUpper && current.length > 0) {
+      const prevIsLower = current[current.length - 1] >= "a" && current[current.length - 1] <= "z";
+      if (prevIsLower || nextIsLower) {
+        words.push(current);
+        current = char;
+      } else {
+        current += char;
+      }
+    } else {
+      current += char;
+    }
+  }
+  if (current.length > 0) words.push(current);
+  return words;
+}
+
+function isSingleWord(name: string): boolean {
+  if (name.length <= 1) return false;
+  if (!/^[A-Z]/.test(name)) return false;
+  return splitPascalCase(name).length <= 1;
+}
+
+function getLspConnection(): ChatCompletionConnection | undefined {
+  const connection = (globalThis as { lspConnection?: unknown }).lspConnection;
+  if (typeof connection !== "object" || connection === null) return undefined;
+  const sendRequest = (connection as Partial<ChatCompletionConnection>).sendRequest;
+  if (typeof sendRequest !== "function") return undefined;
+  return connection as ChatCompletionConnection;
+}
+
+function extractModelSource(model: Model): string {
+  if (model.node === undefined || model.node.kind !== SyntaxKind.ModelStatement) return "";
+  const location = getSourceLocation(model.node);
+  return location.file.text.slice(model.node.pos, model.node.end).trim();
+}
+
+function getModelDocumentation(program: Program, model: Model): string {
+  return getDoc(program, model)?.trim() ?? "";
+}
+
+function parseSuggestions(response: string): string[] {
+  return [
+    ...new Set(
+      response
+        .split("\n")
+        .map((line) =>
+          line
+            .trim()
+            .replace(/^`+|`+$/g, "")
+            .replace(/^\d+\.\s*/, "")
+            .trim(),
+        )
+        .filter((name) => name && /^[A-Z][a-zA-Z0-9]*$/.test(name) && !isSingleWord(name)),
+    ),
+  ].slice(0, 5);
+}
+
+async function fetchAiNameSuggestions(
+  program: Program,
+  model: Model,
+  csharpName: string,
+): Promise<string[]> {
+  const connection = getLspConnection();
+  if (connection === undefined) {
+    return [];
+  }
+
+  const namespaceName = model.namespace ? getNamespaceFullName(model.namespace) : "";
+  const modelDocumentation = getModelDocumentation(program, model);
+  const documentationSection =
+    modelDocumentation === "" ? "" : `\nModel documentation:\n${modelDocumentation}\n`;
+  const prompt = `You are a .NET naming expert. A TypeSpec model named "${csharpName}" in namespace "${namespaceName}" is a single word that may collide with .NET types.
+${documentationSection}
+Model definition:
+${extractModelSource(model)}
+
+Suggest exactly 5 better multi-word PascalCase names. Reply with only the names, one per line.`;
+
+  try {
+    const result = await connection.sendRequest("custom/chatCompletion", {
+      messages: [{ role: "user", message: prompt }],
+      modelFamily: "claude-opus-4.6",
+      id: `csharp-no-single-word-model-name-${namespaceName}.${csharpName}`,
+    });
+    return typeof result === "string" ? parseSuggestions(result) : [];
+  } catch {
+    return [];
+  }
+}
+
+function createClientNameCodeFix(
+  model: Model,
+  program: Program,
+  csharpName: string,
+  name: string,
+  index: number,
+): CodeFix {
+  const fix = createClientTspAugmentDecoratorCodeFix(model, "clientName", program, [
+    `"${name}"`,
+    `"csharp"`,
+  ]);
+  return {
+    ...fix,
+    id: `${fix.id}-${index}`,
+    label: `Rename '${csharpName}' to '${name}' in client.tsp`,
+  };
+}
+
+function createAiClientNameCodeFix(model: Model, program: Program, csharpName: string): CodeFix {
+  const fix: DynamicCodeFix = {
+    id: "ai-rename-single-word-model",
+    label: "Suggest multi-word C# names",
+    fix: () => [],
+    resolveCodefixes: async () => {
+      const suggestions = await fetchAiNameSuggestions(program, model, csharpName);
+      const names =
+        suggestions.length > 0
+          ? suggestions
+          : [`${model.namespace?.name ?? "Service"}${csharpName}`].filter((x) => !isSingleWord(x));
+      return names.map((name, index) =>
+        createClientNameCodeFix(model, program, csharpName, name, index),
+      );
+    },
+  };
+  return fix;
+}
+
+export const csharpNoSingleWordModelNameRule = createRule({
+  name: "csharp-no-single-word-model-name",
+  description:
+    "Model names should be multi-word to avoid naming collisions with .NET platform types.",
+  severity: "warning",
+  url: "https://azure.github.io/typespec-azure/docs/libraries/typespec-client-generator-core/rules/csharp-no-single-word-model-name",
+  messages: {
+    default: paramMessage`Model name '${"name"}' is a single word. Use a more descriptive multi-word name.`,
+  },
+  create(context) {
+    const tcgcContext = createTCGCContext(
+      context.program,
+      "@azure-tools/typespec-client-generator-core",
+      { mutateNamespace: false },
+    );
+
+    return {
+      model: (model: Model) => {
+        if (model.node === undefined || model.node.kind !== SyntaxKind.ModelStatement) return;
+        if (model.templateMapper !== undefined) return;
+
+        const csharpName = getLibraryName(tcgcContext, model, "csharp");
+        if (!isSingleWord(csharpName)) return;
+
+        context.reportDiagnostic({
+          format: { name: csharpName },
+          target: model,
+          codefixes: [createAiClientNameCodeFix(model, context.program, csharpName)],
+        });
+      },
+    };
+  },
+});
diff --git a/packages/typespec-client-generator-core/test/rules/csharp-no-single-word-model-name.test.ts b/packages/typespec-client-generator-core/test/rules/csharp-no-single-word-model-name.test.ts
new file mode 100644
index 0000000000..0743ff3d9e
--- /dev/null
+++ b/packages/typespec-client-generator-core/test/rules/csharp-no-single-word-model-name.test.ts
@@ -0,0 +1,54 @@
+import { LinterRuleTester, createLinterRuleTester } from "@typespec/compiler/testing";
+import { beforeEach, it } from "vitest";
+import { csharpNoSingleWordModelNameRule } from "../../src/rules/csharp-no-single-word-model-name.js";
+import { SimpleTester } from "../tester.js";
+
+let tester: LinterRuleTester;
+
+beforeEach(async () => {
+  const runner = await SimpleTester.createInstance();
+  tester = createLinterRuleTester(
+    runner,
+    csharpNoSingleWordModelNameRule,
+    "@azure-tools/typespec-client-generator-core",
+  );
+});
+
+it("emits warning for single-word model name", async () => {
+  await tester.expect(`model Document { id: string; }`).toEmitDiagnostics({
+    code: "@azure-tools/typespec-client-generator-core/csharp-no-single-word-model-name",
+    message: "Model name 'Document' is a single word. Use a more descriptive multi-word name.",
+  });
+});
+
+it("is valid for multi-word model name", async () => {
+  await tester.expect(`model TableDocument { id: string; }`).toBeValid();
+});
+
+it("is valid for acronym + word model name", async () => {
+  await tester.expect(`model HTTPClient { url: string; }`).toBeValid();
+});
+
+it("does not flag single-char names", async () => {
+  await tester.expect(`model T { id: string; }`).toBeValid();
+});
+
+it("is valid when @clientName provides multi-word name", async () => {
+  await tester
+    .expect(
+      `@clientName("StorageDocument", "csharp")
+      model Document { id: string; }`,
+    )
+    .toBeValid();
+});
+
+it("emits warning when @clientName is still single-word", async () => {
+  await tester
+    .expect(
+      `@clientName("Blob", "csharp")
+      model Document { id: string; }`,
+    )
+    .toEmitDiagnostics({
+      code: "@azure-tools/typespec-client-generator-core/csharp-no-single-word-model-name",
+    });
+});
diff --git a/website/src/content/docs/docs/libraries/typespec-client-generator-core/rules/csharp-no-single-word-model-name.md b/website/src/content/docs/docs/libraries/typespec-client-generator-core/rules/csharp-no-single-word-model-name.md
new file mode 100644
index 0000000000..3004ca4eff
--- /dev/null
+++ b/website/src/content/docs/docs/libraries/typespec-client-generator-core/rules/csharp-no-single-word-model-name.md
@@ -0,0 +1,32 @@
+---
+title: "csharp-no-single-word-model-name"
+---
+
+```text title="Full name"
+@azure-tools/typespec-client-generator-core/csharp-no-single-word-model-name
+```
+
+Model names should be multi-word to avoid naming collisions with .NET platform or third-party types. The codefix can suggest C# names and write `@@clientName` to `client.tsp`.
+
+#### ❌ Incorrect
+
+```tsp
+model Document {
+  id: string;
+}
+```
+
+#### ✅ Correct
+
+```tsp
+model TableDocument {
+  id: string;
+}
+```
+
+```tsp
+@clientName("StorageDocument", "csharp")
+model Document {
+  id: string;
+}
+```