ci: keep shared unit fixture out of package and browser jobs (#26575)

.oxlintrc.json

@@ -140,6 +140,34 @@
     "unicorn/throw-new-error": "error"
   },
   "overrides": [
+    {
+      "files": ["**/*.{js,cjs,mjs,jsx,ts,tsx,mts,cts}"],
+      "excludeFiles": [
+        "**/*.{test,spec}.{js,cjs,mjs,jsx,ts,tsx,mts,cts}",
+        "**/__tests__/**",
+        "src/renderer/src/runtime/web-runtime-browser-creation-placement-test-rig.ts"
+      ],
+      "rules": {
+        "no-restricted-imports": [
+          "error",
+          {
+            "paths": [
+              {
+                "name": "@linear/sdk",
+                "allowTypeImports": true,
+                "message": "Value-importing @linear/sdk hoists its ~2.6MB CJS bundle into the eager top-level require block and defeats the lazy loader. Use `import type` plus loadLinearSdk() from src/main/linear/linear-sdk.ts."
+              }
+            ],
+            "patterns": [
+              {
+                "regex": "(?i)(?:^|[/\\\\])(?:web-session-tabs-sync-test-harness|web-runtime-browser-creation-placement-test-rig)(?:\\.[cm]?[jt]sx?)?(?:[?#].*)?$",
+                "message": "This module is unit-test support. Import the production web-session owner instead."
+              }
+            ]
+          }
+        ]
+      }
+    },
     {
       "files": ["src/renderer/src/**/*.{ts,tsx}"],
       "rules": {

config/scripts/check-changed-code-quality.test.mjs

@@ -131,10 +131,10 @@ describe('unloaded plugin directive unused warning', () => {
   // Assembled so no line here is itself a directive the gate would scan.
   const directive = (rule) => `/* oxlint-disable ${rule} -- reason */`
 
-  const withFixture = (firstLine, assert) => {
+  const withFixture = (firstLine, assert, filename = 'fixture.ts') => {
     const directory = mkdtempSync(path.join(root, 'config', 'anti-slop-directive-test-'))
     try {
-      const file = path.join(directory, 'fixture.ts')
+      const file = path.join(directory, filename)
       writeFileSync(file, [firstLine, 'export const value = 1', ''].join('\n'))
       assert({
         message: 'Unused oxlint-disable directive (no problems were reported).',
@@ -186,6 +186,36 @@ describe('unloaded plugin directive unused warning', () => {
     return JSON.parse(result.stdout).diagnostics
   }
 
+  it.each([
+    "import './web-session-tabs-sync-test-harness'",
+    "export * from '@/runtime/web-session-tabs-sync-test-harness'",
+    "void import('@renderer/runtime/web-session-tabs-sync-test-harness.ts')",
+    "import '../runtime/web-runtime-browser-creation-placement-test-rig'"
+  ])('rejects unit-support imports in production source: %s', (source) => {
+    withFixture(source, ({ filename }) => {
+      const diagnostics = scanFixture('code quality', filename).filter(
+        (diagnostic) => diagnostic.code === 'eslint(no-restricted-imports)'
+      )
+      expect(diagnostics).toHaveLength(1)
+    })
+  })
+
+  it.each(['fixture.test.ts', 'fixture.spec.ts'])(
+    'allows unit-support imports from the existing test convention: %s',
+    (filename) => {
+      withFixture(
+        "import '@/runtime/web-session-tabs-sync-test-harness'",
+        (diagnostic) => {
+          const diagnostics = scanFixture('code quality', diagnostic.filename).filter(
+            (finding) => finding.code === 'eslint(no-restricted-imports)'
+          )
+          expect(diagnostics).toEqual([])
+        },
+        filename
+      )
+    }
+  )
+
   it('accepts a used Doctor directive only through its loaded scan', () => {
     const source = [
       "import { useEffect, useState } from 'react'",

config/scripts/pr-code-change-scope.mjs

@@ -564,8 +564,17 @@ function isProductBundlePath(file, extraPrefixes) {
   return matchesPrefix(file, extraPrefixes)
 }
 
+// This shared fixture is consumed only by unit suites and their placement rig.
+export function isUnitTestSupportSource(file) {
+  return file === 'src/renderer/src/runtime/web-session-tabs-sync-test-harness.ts'
+}
+
 function isTestFile(file) {
-  return /\.(?:test|spec)\.(?:js|cjs|mjs|ts|tsx)$/.test(file) || file.includes('/__tests__/')
+  return (
+    isUnitTestSupportSource(file) ||
+    /\.(?:test|spec)\.(?:js|cjs|mjs|ts|tsx)$/.test(file) ||
+    file.includes('/__tests__/')
+  )
 }
 
 function isDesktopIrrelevantPath(file) {

config/scripts/pr-e2e-source-routing.mjs

@@ -1,7 +1,8 @@
 import process from 'node:process'
 import { pathToFileURL } from 'node:url'
+import { isUnitTestSupportSource } from './pr-code-change-scope.mjs'
 
-const isProductSource = (file) => !/\.test\.tsx?$/.test(file)
+const isProductSource = (file) => !/\.test\.tsx?$/.test(file) && !isUnitTestSupportSource(file)
 
 // Why config/patches: the xterm fork owns the helper textarea an input method attaches to, so a
 // patch edit can break composition without touching a file named "ime".

config/scripts/pr-unit-support-routing.test.mjs

@@ -0,0 +1,45 @@
+import { describe, expect, it } from 'vitest'
+import { classifyPrJobs } from './pr-code-change-scope.mjs'
+import { selectPrE2eSpecs } from './pr-e2e-source-routing.mjs'
+
+const harness = 'src/renderer/src/runtime/web-session-tabs-sync-test-harness.ts'
+
+describe('shared web-session unit support routing', () => {
+  it('keeps unit checks and lint while excluding packaging for the exact harness', () => {
+    const result = classifyPrJobs([harness])
+    expect(result.should_run).toBe(true)
+    expect(result.static_analysis).toBe(true)
+    expect(result.typecheck).toBe(true)
+    expect(result.test).toBe(true)
+    expect(result.package).toBe(false)
+    expect(result.package_windows).toBe(false)
+  })
+
+  it('retains packaging for unknown helpers and mixed product changes', () => {
+    for (const file of [
+      'src/renderer/src/runtime/web-session-tabs-sync-next-test-harness.ts',
+      'src/renderer/src/runtime/web-session-tabs-sync.ts'
+    ]) {
+      const result = classifyPrJobs([harness, file])
+      expect(result.should_run, file).toBe(true)
+      expect(result.test, file).toBe(true)
+      expect(result.package, file).toBe(true)
+      expect(result.package_windows, file).toBe(true)
+    }
+  })
+
+  it('does not turn the exact unit harness into a two-app E2E', () => {
+    expect(selectPrE2eSpecs([harness])).toEqual([])
+  })
+
+  it('retains E2E selection for unknown helpers, product changes and selected specs', () => {
+    const spec = 'tests/e2e/paired-client-hosted-browser-restart-survival.spec.ts'
+    for (const file of [
+      'src/renderer/src/runtime/web-session-tabs-sync-next-test-harness.ts',
+      'src/renderer/src/runtime/web-session-tabs-sync.ts',
+      spec
+    ]) {
+      expect(selectPrE2eSpecs([harness, file]), file).toContain(spec)
+    }
+  })
+})