feat: implement VM SKU chooser tool with filtering and location persistence

app/backend/src/azure-service.ts

@@ -2,7 +2,7 @@ import { ComputeManagementClient } from "@azure/arm-compute";
 import { DefaultAzureCredential } from "@azure/identity";
 import { MemoryCache } from "./cache";
 import { sortImageVersionsIfSemantic } from "./version";
-import type { LocationOption } from "./types";
+import type { LocationOption, VmSkuOption } from "./types";
 
 const CACHE_TTL_MS = 5 * 60 * 1000;
 
@@ -116,6 +116,47 @@ export class AzureImageService {
     return sorted;
   }
 
+  public async getVmSkus(location: string): Promise<VmSkuOption[]> {
+    const cacheKey = `vm-skus:${location}`;
+    const cached = this.cache.get<VmSkuOption[]>(cacheKey);
+    if (cached) {
+      return cached;
+    }
+
+    const targetLocation = location.toLowerCase();
+    const vmSkus: VmSkuOption[] = [];
+
+    for await (const sku of this.computeClient.resourceSkus.list()) {
+      if ((sku.resourceType ?? "").toLowerCase() !== "virtualmachines") {
+        continue;
+      }
+
+      const skuLocations = (sku.locations ?? []).map((item) => item.toLowerCase());
+      const matchesLocation = skuLocations.includes(targetLocation);
+      if (!matchesLocation) {
+        continue;
+      }
+
+      const capabilities = new Map(
+        (sku.capabilities ?? []).map((item) => [item.name?.toLowerCase() ?? "", item.value ?? ""])
+      );
+
+      vmSkus.push({
+        name: sku.name ?? "",
+        size: sku.size ?? "",
+        family: sku.family ?? "",
+        tier: sku.tier ?? "",
+        vcpus: this.toNumber(capabilities.get("vcpus")),
+        memoryGb: this.toNumber(capabilities.get("memorygb")),
+        maxDataDiskCount: this.toNumber(capabilities.get("maxdatadiskcount"))
+      });
+    }
+
+    vmSkus.sort((a, b) => a.name.localeCompare(b.name));
+    this.cache.set(cacheKey, vmSkus, CACHE_TTL_MS);
+    return vmSkus;
+  }
+
   private extractNames(source: unknown): string[] {
     const items = Array.isArray(source)
       ? source
@@ -127,4 +168,14 @@ export class AzureImageService {
       .map((item) => (typeof item === "object" && item !== null && "name" in item ? (item as { name?: string }).name : undefined))
       .filter((value): value is string => Boolean(value));
   }
+
+  private toNumber(value: string | undefined): number | null {
+    if (!value) {
+      return null;
+    }
+
+    const parsed = Number.parseFloat(value);
+    return Number.isFinite(parsed) ? parsed : null;
+  }
+
 }

app/backend/src/server.ts

@@ -110,6 +110,15 @@ const makeApp = () => {
     }
   });
 
+  app.get("/api/vm-skus", async (req, res, next) => {
+    try {
+      const { location } = queryLocation.parse(req.query);
+      res.json(await requireAzure().getVmSkus(location));
+    } catch (error) {
+      next(error);
+    }
+  });
+
   app.get("/api/templates", (_req, res) => {
     res.json(templates.getTemplates());
   });

app/backend/src/types.ts

@@ -16,3 +16,13 @@ export type ImageSelection = {
   sku: string;
   version: string;
 };
+
+export type VmSkuOption = {
+  name: string;
+  size: string;
+  family: string;
+  tier: string;
+  vcpus: number | null;
+  memoryGb: number | null;
+  maxDataDiskCount: number | null;
+};