diff --git a/src/exec-stack.ts b/src/exec-stack.ts
index c394c9f..a049586 100644
--- a/src/exec-stack.ts
+++ b/src/exec-stack.ts
@@ -15,6 +15,10 @@ export class ExecStack {
       .concat(args);
   }
 
+  async upgrade(): Promise<number> {
+    return await exec.exec("stack", ["upgrade"]);
+  }
+
   async exec(args: string[], options?: exec.ExecOptions): Promise<number> {
     return await exec.exec("stack", this.stackArguments.concat(args), options);
   }
diff --git a/src/main.ts b/src/main.ts
index a97d537..d9a834a 100644
--- a/src/main.ts
+++ b/src/main.ts
@@ -1,4 +1,3 @@
-import * as path from "path";
 import * as core from "@actions/core";
 
 import { ExecStack } from "./exec-stack";
@@ -6,19 +5,18 @@ import { getCacheKeys } from "./get-cache-keys";
 import { hashProject } from "./hash-project";
 import type { Inputs } from "./inputs";
 import { getInputs } from "./inputs";
-import type { StackPath } from "./parse-stack-path";
 import { parseStackPath } from "./parse-stack-path";
-import type { StackQuery } from "./parse-stack-query";
-import { getLocalStackWorks, parseStackQuery } from "./parse-stack-query";
+import { parseStackQuery } from "./parse-stack-query";
+import { readStackYamlSync, packagesStackWorks } from "./stack-yaml";
 import { DEFAULT_CACHE_OPTIONS, withCache } from "./with-cache";
 
-function setOutputs(stackQuery: StackQuery, stackPath: StackPath): void {
-  core.setOutput("compiler", stackQuery.compiler.actual);
-  core.setOutput(
-    "compiler-version",
-    stackQuery.compiler.actual.replace(/^ghc-/, ""),
-  );
-}
+// function setOutputs(stackQuery: StackQuery, stackPath: StackPath): void {
+//   core.setOutput("compiler", stackQuery.compiler.actual);
+//   core.setOutput(
+//     "compiler-version",
+//     stackQuery.compiler.actual.replace(/^ghc-/, ""),
+//   );
+// }
 
 async function dependencies(stack: ExecStack, inputs: Inputs): Promise<void> {
   await stack.exec(["setup"].concat(inputs.stackSetupArguments));
@@ -54,28 +52,35 @@ async function run() {
       process.chdir(inputs.workingDirectory);
     }
 
+    const hashes = await hashProject(inputs.stackYaml);
+    core.info(`Snapshot hash ${hashes.snapshot}`);
+    core.info(`Package hash ${hashes.package}`);
+    core.info(`Sources hash ${hashes.sources}`);
+
     const stack = new ExecStack(inputs.stackYaml, inputs.stackArguments);
-    const stackPath = await stack.parse(["path"], parseStackPath);
-    const stackQuery = await stack.parse(["query"], parseStackQuery);
 
-    setOutputs(stackQuery, stackPath);
+    await core.group("Stack upgrade", async () => {
+      await stack.upgrade();
+    });
 
-    const stackWork = path.join(process.cwd(), ".stack-work");
-    const stackWorks = getLocalStackWorks(stackQuery, [stackWork]);
-    core.info(`Found .stack-works:\n - ${stackWorks.join("\n - ")}`);
+    // Only use --stack-root, which (as of stack v2.15) won't load the
+    // environment and install GHC, etc. It's the only option currently safe to
+    // make outside of caching.
+    const stackRoot = (
+      await stack.parse(["path", "--stack-root]"], parseStackPath)
+    )["stack-root"];
 
-    const hashes = await hashProject(inputs.stackYaml);
+    const stackYaml = readStackYamlSync(inputs.stackYaml);
+    const stackWorks = packagesStackWorks(stackYaml);
 
     await core.group("Dependencies", async () => {
       const cacheKeys = getCacheKeys([
-        inputs.cachePrefix("stack-deps", stackQuery.compiler.actual),
+        inputs.cachePrefix("stack-deps", stackYaml.resolver),
         hashes.snapshot,
         hashes.package,
       ]);
 
-      const cachePaths = [stackPath["stack-root"], stackPath.programs].concat(
-        stackWorks,
-      );
+      const cachePaths = [stackRoot].concat(stackWorks);
 
       await withCache(cachePaths, cacheKeys, dependencies(stack, inputs), {
         ...DEFAULT_CACHE_OPTIONS,
@@ -85,7 +90,7 @@ async function run() {
 
     await core.group("Build", async () => {
       const cacheKeys = getCacheKeys([
-        inputs.cachePrefix("stack-deps", stackQuery.compiler.actual),
+        inputs.cachePrefix("stack-deps", stackYaml.resolver),
         hashes.snapshot,
         hashes.package,
         hashes.sources,
@@ -93,13 +98,30 @@ async function run() {
 
       await withCache(stackWorks, cacheKeys, build(stack, inputs), {
         ...DEFAULT_CACHE_OPTIONS,
-        skipOnHit: !inputs.cacheSaveAlways,
+        skipOnHit: false, // always Build
       });
     });
 
     if (inputs.test) {
       await core.group("Test", async () => await test(stack, inputs));
     }
+
+    const stackQuery = await stack.parse(
+      ["query", "compiler"],
+      parseStackQuery,
+    );
+
+    core.setOutput("compiler", stackQuery.compiler.actual);
+    core.setOutput(
+      "compiler-version",
+      stackQuery.compiler.actual.replace(/^ghc-/, ""),
+    );
+
+    const stackPath = await stack.parse(["path"], parseStackPath);
+
+    for (const k in stackPath) {
+      core.setOutput(k, stackPath[k]);
+    }
   } catch (error) {
     if (error instanceof Error) {
       core.error(error);
diff --git a/src/parse-stack-path.ts b/src/parse-stack-path.ts
index a0d187b..5a1fb0a 100644
--- a/src/parse-stack-path.ts
+++ b/src/parse-stack-path.ts
@@ -2,29 +2,7 @@ import * as yaml from "js-yaml";
 
 export type StackPath = {
   [key: string]: string | null;
-  "snapshot-doc-root": string;
-  "local-doc-root": string;
-  "local-hoogle-root": string;
-  "stack-root": string;
-  "global-config": string;
-  "project-root": string;
-  "config-location": string;
-  "bin-path": string;
-  programs: string;
-  "compiler-exe": string;
-  "compiler-bin": string;
-  "compiler-tools-bin": string;
-  "local-bin": string;
-  "extra-include-dirs": string | null;
-  "extra-library-dirs": string | null;
-  "snapshot-pkg-db": string;
-  "local-pkg-db": string;
-  "global-pkg-db": string;
-  "ghc-package-path": string;
-  "snapshot-install-root": string;
-  "local-install-root": string;
-  "dist-dir": string;
-  "local-hpc-root": string;
+  "stack-root": string; // we only require this one
 };
 
 export function parseStackPath(stdout: string): StackPath {
diff --git a/src/parse-stack-query.test.ts b/src/parse-stack-query.test.ts
index dfacbee..5dde394 100644
--- a/src/parse-stack-query.test.ts
+++ b/src/parse-stack-query.test.ts
@@ -1,4 +1,4 @@
-import { getLocalStackWorks, parseStackQuery } from "./parse-stack-query";
+import { parseStackQuery } from "./parse-stack-query";
 
 const EXAMPLE = [
   "compiler:",
@@ -18,33 +18,6 @@ const EXAMPLE = [
 
 test("parseStackQuery", () => {
   const stackQuery = parseStackQuery(EXAMPLE);
-
   expect(stackQuery.compiler.actual).toBe("ghc-9.2.7");
   expect(stackQuery.compiler.wanted).toBe("ghc-9.2.7");
 });
-
-test("getLocalStackWorks", () => {
-  const stackQuery = parseStackQuery(EXAMPLE);
-
-  const stackWorks = getLocalStackWorks(stackQuery, []);
-
-  expect(stackWorks).toEqual([
-    "/home/patrick/code/freckle/megarepo/backend/core/.stack-work",
-    "/home/patrick/code/freckle/megarepo/backend/entities/.stack-work",
-    "/home/patrick/code/freckle/megarepo/backend/fancy-api/.stack-work",
-  ]);
-});
-
-test("getLocalStackWorks avoids duplicates", () => {
-  const stackQuery = parseStackQuery(EXAMPLE);
-
-  const stackWorks = getLocalStackWorks(stackQuery, [
-    "/home/patrick/code/freckle/megarepo/backend/core/.stack-work",
-  ]);
-
-  expect(stackWorks).toEqual([
-    "/home/patrick/code/freckle/megarepo/backend/core/.stack-work",
-    "/home/patrick/code/freckle/megarepo/backend/entities/.stack-work",
-    "/home/patrick/code/freckle/megarepo/backend/fancy-api/.stack-work",
-  ]);
-});
diff --git a/src/parse-stack-query.ts b/src/parse-stack-query.ts
index e64fc8a..90c4d7f 100644
--- a/src/parse-stack-query.ts
+++ b/src/parse-stack-query.ts
@@ -1,9 +1,7 @@
-import * as osPath from "path";
 import * as yaml from "js-yaml";
 
 export type StackQuery = {
   compiler: Compiler;
-  locals: Locals;
 };
 
 export type Compiler = {
@@ -11,29 +9,6 @@ export type Compiler = {
   wanted: string;
 };
 
-export type Locals = { [key: string]: Local };
-
-export type Local = {
-  path: string;
-  version: string;
-};
-
 export function parseStackQuery(stdout: string): StackQuery {
   return yaml.load(stdout) as StackQuery;
 }
-
-export function getLocalStackWorks(
-  stackQuery: StackQuery,
-  stackWorks: string[] = [],
-): string[] {
-  for (const k in stackQuery.locals) {
-    const { path } = stackQuery.locals[k];
-    const stackWork = osPath.join(path, ".stack-work");
-
-    if (!stackWorks.includes(stackWork)) {
-      stackWorks.push(stackWork);
-    }
-  }
-
-  return stackWorks;
-}
diff --git a/src/stack-yaml.ts b/src/stack-yaml.ts
new file mode 100644
index 0000000..976545d
--- /dev/null
+++ b/src/stack-yaml.ts
@@ -0,0 +1,21 @@
+import * as fs from "fs";
+import { join as joinPath } from "path";
+import * as yaml from "js-yaml";
+
+export type StackYaml = {
+  resolver: string;
+  packages: string[] | null;
+};
+
+export function readStackYamlSync(path: string): StackYaml {
+  const contents = fs.readFileSync(path, { encoding: "utf-8" });
+  return yaml.load(contents) as StackYaml;
+}
+
+export function packagesStackWorks(stackYaml: StackYaml): string[] {
+  const cwd = process.cwd();
+
+  return [".stack-work"]
+    .concat((stackYaml.packages ?? []).map((p) => joinPath(p, ".stack-work")))
+    .map((sw) => joinPath(cwd, sw));
+}