refactor(cli): move version-compare helper into dev.ts

isVersionNewer/parseVersionCore no longer gate the npx re-exec (which
always runs @latest); their only remaining consumer is the dashboard
restart check in dev.ts. Move them (and their tests) there so
self-update.ts is purely about the re-exec.

packages/stack-cli/src/commands/dev.test.ts

@@ -3,7 +3,54 @@ import { tmpdir } from "os";
 import { join } from "path";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 import { recordLocalDashboardProcess } from "../lib/dev-env-state.js";
-import { killLocalDashboard, processExists, shouldRestartDashboard } from "./dev.js";
+import { isVersionNewer, killLocalDashboard, processExists, shouldRestartDashboard } from "./dev.js";
+
+describe("isVersionNewer", () => {
+  it("compares core versions numerically", () => {
+    expect(isVersionNewer("2.8.110", "2.8.109")).toBe(true);
+    expect(isVersionNewer("2.9.0", "2.8.999")).toBe(true);
+    expect(isVersionNewer("3.0.0", "2.999.999")).toBe(true);
+    expect(isVersionNewer("2.8.109", "2.8.109")).toBe(false);
+    expect(isVersionNewer("2.8.108", "2.8.109")).toBe(false);
+  });
+
+  it("does not treat double-digit segments as strings", () => {
+    expect(isVersionNewer("2.8.10", "2.8.9")).toBe(true);
+  });
+
+  it("ranks a final release above a prerelease of the same core", () => {
+    expect(isVersionNewer("2.8.109", "2.8.109-beta.1")).toBe(true);
+    expect(isVersionNewer("2.8.109-beta.1", "2.8.109")).toBe(false);
+  });
+
+  it("returns false for unparseable versions (never downgrade or guess)", () => {
+    expect(isVersionNewer("garbage", "2.8.109")).toBe(false);
+    expect(isVersionNewer("2.8.110", "garbage")).toBe(false);
+  });
+
+  it("tolerates a leading v and surrounding whitespace on either side", () => {
+    expect(isVersionNewer("v2.8.110", "2.8.109")).toBe(true);
+    expect(isVersionNewer("2.8.110", "v2.8.109")).toBe(true);
+    expect(isVersionNewer("  2.8.110  ", "2.8.109")).toBe(true);
+    expect(isVersionNewer("v2.8.110", "v2.8.110")).toBe(false);
+  });
+
+  it("treats a two-segment version (x.y) as unparseable", () => {
+    expect(isVersionNewer("2.8", "2.8.109")).toBe(false);
+    expect(isVersionNewer("2.8.109", "2.8")).toBe(false);
+  });
+
+  it("ignores prerelease identifiers when both cores are equal prereleases", () => {
+    // Only "release beats prerelease" is modeled; beta.2 is NOT newer than beta.1.
+    expect(isVersionNewer("2.8.109-beta.2", "2.8.109-beta.1")).toBe(false);
+    expect(isVersionNewer("2.8.109-beta.1", "2.8.109-beta.2")).toBe(false);
+  });
+
+  it("compares very large numeric segments correctly", () => {
+    expect(isVersionNewer("2.8.1000000000", "2.8.999999999")).toBe(true);
+    expect(isVersionNewer("10000000000.0.0", "9999999999.0.0")).toBe(true);
+  });
+});
 
 describe("shouldRestartDashboard", () => {
   it("restarts only when ours is strictly newer than the running dashboard", () => {

packages/stack-cli/src/commands/dev.ts

@@ -9,7 +9,7 @@ import { resolveConfigFilePathOption } from "../lib/config-file-path.js";
 import { devEnvStatePath, ensureLocalDashboardSecret, readDevEnvState, recordLocalDashboardProcess } from "../lib/dev-env-state.js";
 import { CliError } from "../lib/errors.js";
 import { cliVersion } from "../lib/own-package.js";
-import { isVersionNewer, maybeReexecToLatest } from "../lib/self-update.js";
+import { maybeReexecToLatest } from "../lib/self-update.js";
 
 type ChildCommand = {
   command: string,
@@ -273,6 +273,43 @@ async function isDashboardReachable(url: string): Promise<boolean> {
   }
 }
 
+type ParsedVersion = {
+  core: [number, number, number],
+  hasPrerelease: boolean,
+};
+
+function parseVersionCore(version: string): ParsedVersion | null {
+  const trimmed = version.trim();
+  const match = /^v?(\d+)\.(\d+)\.(\d+)/.exec(trimmed);
+  if (!match) return null;
+  return {
+    core: [Number(match[1]), Number(match[2]), Number(match[3])],
+    // A `-` immediately after the core marks a semver prerelease (e.g.
+    // 2.8.109-beta.1). `.test()` returns a plain boolean, sidestepping the
+    // optional-capture-group typing.
+    hasPrerelease: /^v?\d+\.\d+\.\d+-/.test(trimmed),
+  };
+}
+
+// Returns true only when `candidate` is strictly newer than `current`. Unknown
+// or unparseable versions return false so we never act on a version we can't
+// reason about (and never downgrade). Prerelease identifiers beyond the
+// "release beats same-core prerelease" rule are intentionally not ordered. Only
+// the dashboard restart check below needs this; the CLI re-exec just always runs
+// `@latest`. Exported for unit testing.
+export function isVersionNewer(candidate: string, current: string): boolean {
+  const a = parseVersionCore(candidate);
+  const b = parseVersionCore(current);
+  if (a == null || b == null) return false;
+  for (let i = 0; i < 3; i++) {
+    if (a.core[i] !== b.core[i]) {
+      return a.core[i] > b.core[i];
+    }
+  }
+  // Same x.y.z: a final release outranks a prerelease of the same core.
+  return !a.hasPrerelease && b.hasPrerelease;
+}
+
 // Restart the running dashboard only when ours is strictly newer; this is how a
 // re-exec'd `npx @latest` rolls out a fresh dashboard without a reinstall.
 // Equal/older/unknown versions (e.g. a dashboard recorded by a pre-feature CLI

packages/stack-cli/src/lib/self-update.test.ts

@@ -4,7 +4,6 @@ import {
   decideReexec,
   DISABLE_AUTO_UPDATE_ENV,
   isEnvFlagEnabled,
-  isVersionNewer,
   maybeReexecToLatest,
   shouldAutoUpdate,
   SKIP_AUTO_UPDATE_ENV,
@@ -52,53 +51,6 @@ describe("shouldAutoUpdate", () => {
   });
 });
 
-describe("isVersionNewer", () => {
-  it("compares core versions numerically", () => {
-    expect(isVersionNewer("2.8.110", "2.8.109")).toBe(true);
-    expect(isVersionNewer("2.9.0", "2.8.999")).toBe(true);
-    expect(isVersionNewer("3.0.0", "2.999.999")).toBe(true);
-    expect(isVersionNewer("2.8.109", "2.8.109")).toBe(false);
-    expect(isVersionNewer("2.8.108", "2.8.109")).toBe(false);
-  });
-
-  it("does not treat double-digit segments as strings", () => {
-    expect(isVersionNewer("2.8.10", "2.8.9")).toBe(true);
-  });
-
-  it("ranks a final release above a prerelease of the same core", () => {
-    expect(isVersionNewer("2.8.109", "2.8.109-beta.1")).toBe(true);
-    expect(isVersionNewer("2.8.109-beta.1", "2.8.109")).toBe(false);
-  });
-
-  it("returns false for unparseable versions (never downgrade or guess)", () => {
-    expect(isVersionNewer("garbage", "2.8.109")).toBe(false);
-    expect(isVersionNewer("2.8.110", "garbage")).toBe(false);
-  });
-
-  it("tolerates a leading v and surrounding whitespace on either side", () => {
-    expect(isVersionNewer("v2.8.110", "2.8.109")).toBe(true);
-    expect(isVersionNewer("2.8.110", "v2.8.109")).toBe(true);
-    expect(isVersionNewer("  2.8.110  ", "2.8.109")).toBe(true);
-    expect(isVersionNewer("v2.8.110", "v2.8.110")).toBe(false);
-  });
-
-  it("treats a two-segment version (x.y) as unparseable", () => {
-    expect(isVersionNewer("2.8", "2.8.109")).toBe(false);
-    expect(isVersionNewer("2.8.109", "2.8")).toBe(false);
-  });
-
-  it("ignores prerelease identifiers when both cores are equal prereleases", () => {
-    // Only "release beats prerelease" is modeled; beta.2 is NOT newer than beta.1.
-    expect(isVersionNewer("2.8.109-beta.2", "2.8.109-beta.1")).toBe(false);
-    expect(isVersionNewer("2.8.109-beta.1", "2.8.109-beta.2")).toBe(false);
-  });
-
-  it("compares very large numeric segments correctly", () => {
-    expect(isVersionNewer("2.8.1000000000", "2.8.999999999")).toBe(true);
-    expect(isVersionNewer("10000000000.0.0", "9999999999.0.0")).toBe(true);
-  });
-});
-
 describe("buildNpxInvocation", () => {
   it("pins @latest and forwards the subcommand through the bin", () => {
     const { command, args } = buildNpxInvocation({

packages/stack-cli/src/lib/self-update.ts

@@ -31,43 +31,6 @@ export function shouldAutoUpdate(env: NodeJS.ProcessEnv): boolean {
   return true;
 }
 
-type ParsedVersion = {
-  core: [number, number, number],
-  hasPrerelease: boolean,
-};
-
-function parseVersionCore(version: string): ParsedVersion | null {
-  const trimmed = version.trim();
-  const match = /^v?(\d+)\.(\d+)\.(\d+)/.exec(trimmed);
-  if (!match) return null;
-  return {
-    core: [Number(match[1]), Number(match[2]), Number(match[3])],
-    // A `-` immediately after the core marks a semver prerelease (e.g.
-    // 2.8.109-beta.1). `.test()` returns a plain boolean, sidestepping the
-    // optional-capture-group typing.
-    hasPrerelease: /^v?\d+\.\d+\.\d+-/.test(trimmed),
-  };
-}
-
-// Returns true only when `candidate` is strictly newer than `current`. Unknown
-// or unparseable versions return false so we never act on a version we can't
-// reason about (and never downgrade). Prerelease identifiers beyond the
-// "release beats same-core prerelease" rule are intentionally not ordered.
-// Used by the dashboard restart check in dev.ts (the re-exec itself just always
-// runs `@latest`).
-export function isVersionNewer(candidate: string, current: string): boolean {
-  const a = parseVersionCore(candidate);
-  const b = parseVersionCore(current);
-  if (a == null || b == null) return false;
-  for (let i = 0; i < 3; i++) {
-    if (a.core[i] !== b.core[i]) {
-      return a.core[i] > b.core[i];
-    }
-  }
-  // Same x.y.z: a final release outranks a prerelease of the same core.
-  return !a.hasPrerelease && b.hasPrerelease;
-}
-
 export type NpxInvocation = {
   command: string,
   args: string[],