diff --git a/config/scripts/anti-slop-scope-regression.test.mjs b/config/scripts/anti-slop-scope-regression.test.mjs
index 50b75c95e81..2c5e814ad53 100644
--- a/config/scripts/anti-slop-scope-regression.test.mjs
+++ b/config/scripts/anti-slop-scope-regression.test.mjs
@@ -1,25 +1,25 @@
 import { cpSync, mkdtempSync, rmSync } from 'node:fs'
 import { createRequire } from 'node:module'
 import path from 'node:path'
-import { afterAll, expect, it } from 'vitest'
-import { runOxlintPluginOnSource } from './oxlint-plugin-test-runner.mjs'
+import { afterAll, beforeAll, expect, it } from 'vitest'
+import { runOxlintPluginOnSources } from './oxlint-plugin-test-runner.mjs'
 
 const directory = mkdtempSync(path.join(import.meta.dirname, '.anti-slop-scope-'))
 const source = path.dirname(createRequire(import.meta.url).resolve('oxlint-plugin-anti-slop'))
 cpSync(source, directory, { recursive: true })
 afterAll(() => rmSync(directory, { recursive: true, force: true }))
 
-function lint(source, rule) {
-  return runOxlintPluginOnSource({
+function lint(sources, rule) {
+  return runOxlintPluginOnSources({
     pluginName: 'anti-slop',
     pluginPath: path.join(directory, 'index.ts'),
     rules: { [`anti-slop/${rule}`]: 'error' },
-    source,
+    sources,
     extension: 'ts'
   })
 }
 
-it.each([
+const wideningCases = [
   ['const value = {}; const wide: unknown = value; wide as { id: string };', 1],
   ['const value = {}; const alias = value; const wide: unknown = alias; <{ id: string }>wide;', 1],
   ['function parse(input: unknown) { return input as { id: string }; }', 0],
@@ -30,11 +30,9 @@ it.each([
     0
   ],
   ['const value = {}; const wide: unknown = value; wide as unknown;', 0]
-])('preserves widening evidence and lexical boundaries: %s', (source, count) => {
-  expect(lint(source, 'no-widen-then-assert')).toHaveLength(count)
-})
+]
 
-it.each([
+const mockCases = [
   ["import { vi as test } from 'vitest'; test.mock('module');", 1],
   ["import { jest as test } from '@jest/globals'; test['doMock']('module');", 1],
   ["jest.unstable_mockModule('module', () => ({}));", 1],
@@ -43,6 +41,27 @@ it.each([
   ["const unrelated = { mock() {} }; unrelated.mock('module');", 0],
   ["const vi = { mock() {} }; vi.mock('module');", 0],
   ["import { vi as test } from 'vitest'; function run(test) { test.mock('module'); }", 0]
-])('preserves mock method and owner resolution: %s', (source, count) => {
-  expect(lint(source, 'no-module-mocking')).toHaveLength(count)
+]
+
+const wideningDiagnostics = new Map()
+const mockDiagnostics = new Map()
+beforeAll(() => {
+  for (const [cases, rule, results] of [
+    [wideningCases, 'no-widen-then-assert', wideningDiagnostics],
+    [mockCases, 'no-module-mocking', mockDiagnostics]
+  ]) {
+    const sources = cases.map(([source]) => source)
+    lint(sources, rule).forEach((diagnostics, index) => results.set(sources[index], diagnostics))
+  }
+})
+
+it.each(wideningCases)(
+  'preserves widening evidence and lexical boundaries: %s',
+  (source, count) => {
+    expect(wideningDiagnostics.get(source)).toHaveLength(count)
+  }
+)
+
+it.each(mockCases)('preserves mock method and owner resolution: %s', (source, count) => {
+  expect(mockDiagnostics.get(source)).toHaveLength(count)
 })
diff --git a/config/scripts/check-runtime-electron-ratchet.test.mjs b/config/scripts/check-runtime-electron-ratchet.test.mjs
index 984fe088916..53e8a0f576d 100644
--- a/config/scripts/check-runtime-electron-ratchet.test.mjs
+++ b/config/scripts/check-runtime-electron-ratchet.test.mjs
@@ -241,10 +241,4 @@ describe('the command-line check', () => {
     expect(await main({ plugins: [addElectron] })).toBe(1)
     expect(error.mock.calls.join('\n')).toContain('+ src/main/native-chat/transcript-read-cache.ts')
   }, 120_000)
-
-  // Why real: the value of this gate is the transitive edges, which a fixture cannot model.
-  it('passes on the tree as it is, with nothing reachable importing electron', async () => {
-    vi.spyOn(console, 'log').mockImplementation(() => {})
-    expect(await main()).toBe(0)
-  }, 120_000)
 })
diff --git a/config/scripts/ime-enter-guard-plugin.test.mjs b/config/scripts/ime-enter-guard-plugin.test.mjs
index 8a3b426b248..654a42e7076 100644
--- a/config/scripts/ime-enter-guard-plugin.test.mjs
+++ b/config/scripts/ime-enter-guard-plugin.test.mjs
@@ -1,14 +1,14 @@
 import path from 'node:path'
-import { describe, expect, it } from 'vitest'
-import { runOxlintPluginOnSource } from './oxlint-plugin-test-runner.mjs'
+import { beforeAll, describe, expect, it } from 'vitest'
+import { runOxlintPluginOnSources } from './oxlint-plugin-test-runner.mjs'
 
 const pluginPath = path.resolve('config/oxlint-plugins/ime-enter-guard.mjs')
 
-function lintSource(source) {
-  return runOxlintPluginOnSource({
+function lintSources(sources) {
+  return runOxlintPluginOnSources({
     pluginName: 'ime-enter-guard',
     pluginPath,
-    source,
+    sources,
     rules: { 'ime-enter-guard/require-ime-guard': 'warn' }
   })
 }
@@ -118,12 +118,20 @@ const accepted = [
   ]
 ]
 
+const diagnosticsBySource = new Map()
+beforeAll(() => {
+  const sources = [...violations, ...accepted].map(([, source]) => source)
+  lintSources(sources).forEach((diagnostics, index) => {
+    diagnosticsBySource.set(sources[index], diagnostics)
+  })
+})
+
 describe('IME Enter guard Oxlint plugin', () => {
   it.each(violations)('reports %s', (_name, source) => {
-    expect(lintSource(source)).toHaveLength(1)
+    expect(diagnosticsBySource.get(source)).toHaveLength(1)
   })
 
   it.each(accepted)('accepts %s', (_name, source) => {
-    expect(lintSource(source)).toEqual([])
+    expect(diagnosticsBySource.get(source)).toEqual([])
   })
 })
diff --git a/config/scripts/native-chat-design-tokens-plugin.test.mjs b/config/scripts/native-chat-design-tokens-plugin.test.mjs
index 718390c5b93..2e5d08abdaa 100644
--- a/config/scripts/native-chat-design-tokens-plugin.test.mjs
+++ b/config/scripts/native-chat-design-tokens-plugin.test.mjs
@@ -1,14 +1,14 @@
 import path from 'node:path'
-import { describe, expect, it } from 'vitest'
-import { runOxlintPluginOnSource } from './oxlint-plugin-test-runner.mjs'
+import { beforeAll, describe, expect, it } from 'vitest'
+import { runOxlintPluginOnSources } from './oxlint-plugin-test-runner.mjs'
 
 const pluginPath = path.resolve('config/oxlint-plugins/native-chat-design-tokens.mjs')
 
-function lintSource(source) {
-  return runOxlintPluginOnSource({
+function lintSources(sources) {
+  return runOxlintPluginOnSources({
     pluginName: 'native-chat-design-tokens',
     pluginPath,
-    source,
+    sources,
     rules: {
       'native-chat-design-tokens/no-arbitrary-font-size': 'warn',
       'native-chat-design-tokens/no-softened-foreground': 'warn',
@@ -55,12 +55,20 @@ const accepted = [
   ]
 ]
 
+const diagnosticsBySource = new Map()
+beforeAll(() => {
+  const sources = [...violations, ...accepted].map(([, source]) => source)
+  lintSources(sources).forEach((diagnostics, index) => {
+    diagnosticsBySource.set(sources[index], diagnostics)
+  })
+})
+
 describe('native-chat-design-tokens oxlint plugin', () => {
   it.each(violations)('reports %s', (_name, source) => {
-    expect(lintSource(source)).toHaveLength(1)
+    expect(diagnosticsBySource.get(source)).toHaveLength(1)
   })
 
   it.each(accepted)('accepts %s', (_name, source) => {
-    expect(lintSource(source)).toEqual([])
+    expect(diagnosticsBySource.get(source)).toEqual([])
   })
 })
diff --git a/config/scripts/oxlint-plugin-test-runner.mjs b/config/scripts/oxlint-plugin-test-runner.mjs
index c5a80e0c106..b2704ca2dbb 100644
--- a/config/scripts/oxlint-plugin-test-runner.mjs
+++ b/config/scripts/oxlint-plugin-test-runner.mjs
@@ -10,19 +10,25 @@ const oxlintPackageDirectory = path.dirname(
 )
 const oxlintPath = path.join(oxlintPackageDirectory, 'bin', 'oxlint')
 
-export function runOxlintPluginOnSource({
+export function runOxlintPluginOnSource({ source, ...options }) {
+  return runOxlintPluginOnSources({ ...options, sources: [source] })[0]
+}
+
+export function runOxlintPluginOnSources({
   pluginName,
   pluginPath,
   rules,
-  source,
+  sources,
   extension = 'tsx'
 }) {
   const directory = mkdtempSync(path.join(tmpdir(), `orca-${pluginName}-lint-`))
-  const sourcePath = path.join(directory, `sample.${extension}`)
+  const sourcePaths = sources.map((_, index) =>
+    path.join(directory, `sample-${index}.${extension}`)
+  )
   const configPath = path.join(directory, 'oxlint.json')
 
   try {
-    writeFileSync(sourcePath, source)
+    sources.forEach((source, index) => writeFileSync(sourcePaths[index], source))
     writeFileSync(
       configPath,
       JSON.stringify({
@@ -42,7 +48,7 @@ export function runOxlintPluginOnSource({
     )
     const result = spawnSync(
       process.execPath,
-      [oxlintPath, '--config', configPath, '--format', 'json', sourcePath],
+      [oxlintPath, '--config', configPath, '--format', 'json', ...sourcePaths],
       { encoding: 'utf8' }
     )
     if (result.error) {
@@ -51,7 +57,16 @@ export function runOxlintPluginOnSource({
     if (!result.stdout.trim()) {
       throw new Error(result.stderr || `${pluginName} did not produce Oxlint output`)
     }
-    return JSON.parse(result.stdout).diagnostics
+    const diagnostics = JSON.parse(result.stdout).diagnostics
+    const byFile = new Map(sourcePaths.map((file) => [file, []]))
+    for (const diagnostic of diagnostics) {
+      const findings = byFile.get(path.resolve(diagnostic.filename))
+      if (!findings) {
+        throw new Error(`Unexpected Oxlint diagnostic file: ${diagnostic.filename}`)
+      }
+      findings.push(diagnostic)
+    }
+    return sourcePaths.map((file) => byFile.get(file))
   } finally {
     rmSync(directory, { recursive: true, force: true })
   }
diff --git a/config/scripts/quadratic-buffer-concat-plugin.test.mjs b/config/scripts/quadratic-buffer-concat-plugin.test.mjs
index 68c47a0d661..41c672ac845 100644
--- a/config/scripts/quadratic-buffer-concat-plugin.test.mjs
+++ b/config/scripts/quadratic-buffer-concat-plugin.test.mjs
@@ -1,14 +1,14 @@
 import path from 'node:path'
-import { describe, expect, it } from 'vitest'
-import { runOxlintPluginOnSource } from './oxlint-plugin-test-runner.mjs'
+import { beforeAll, describe, expect, it } from 'vitest'
+import { runOxlintPluginOnSources } from './oxlint-plugin-test-runner.mjs'
 
 const pluginPath = path.resolve('config/oxlint-plugins/quadratic-buffer-concat.mjs')
 
-function lintSource(source) {
-  return runOxlintPluginOnSource({
+function lintSources(sources) {
+  return runOxlintPluginOnSources({
     pluginName: 'quadratic-buffer-concat',
     pluginPath,
-    source,
+    sources,
     extension: 'ts',
     rules: {
       'quadratic-buffer-concat/no-loop-carried-concat': 'warn'
@@ -99,15 +99,23 @@ const accepted = [
   ['no Buffer concat', 'export const x = 1']
 ]
 
+const diagnosticsBySource = new Map()
+beforeAll(() => {
+  const sources = [...violations, ...accepted].map(([, source]) => source)
+  lintSources(sources).forEach((diagnostics, index) => {
+    diagnosticsBySource.set(sources[index], diagnostics)
+  })
+})
+
 describe('quadratic Buffer.concat Oxlint plugin', () => {
   it.each(violations)('reports %s', (_name, source, accumulator) => {
-    const diagnostics = lintSource(source)
+    const diagnostics = diagnosticsBySource.get(source)
 
     expect(diagnostics).toHaveLength(1)
     expect(diagnostics[0].message).toContain(accumulator)
   })
 
   it.each(accepted)('accepts %s', (_name, source) => {
-    expect(lintSource(source)).toEqual([])
+    expect(diagnosticsBySource.get(source)).toEqual([])
   })
 })
diff --git a/config/scripts/renderer-scrollbar-style-plugin.test.mjs b/config/scripts/renderer-scrollbar-style-plugin.test.mjs
index fd67ffbbd84..0250297cc35 100644
--- a/config/scripts/renderer-scrollbar-style-plugin.test.mjs
+++ b/config/scripts/renderer-scrollbar-style-plugin.test.mjs
@@ -1,15 +1,15 @@
 import path from 'node:path'
-import { describe, expect, it } from 'vitest'
+import { beforeAll, describe, expect, it } from 'vitest'
 import { plainClassName } from '../oxlint-plugins/renderer-scrollbar-style.mjs'
-import { runOxlintPluginOnSource } from './oxlint-plugin-test-runner.mjs'
+import { runOxlintPluginOnSources } from './oxlint-plugin-test-runner.mjs'
 
 const pluginPath = path.resolve('config/oxlint-plugins/renderer-scrollbar-style.mjs')
 
-function lintSource(source) {
-  return runOxlintPluginOnSource({
+function lintSources(sources) {
+  return runOxlintPluginOnSources({
     pluginName: 'renderer-scrollbar-style',
     pluginPath,
-    source,
+    sources,
     rules: {
       'renderer-scrollbar-style/require-styled-vertical-scrollbar': 'warn'
     }
@@ -94,13 +94,21 @@ const accepted = [
   ]
 ]
 
+const diagnosticsBySource = new Map()
+beforeAll(() => {
+  const sources = [...violations, ...accepted].map(([, source]) => source)
+  lintSources(sources).forEach((diagnostics, index) => {
+    diagnosticsBySource.set(sources[index], diagnostics)
+  })
+})
+
 describe('renderer scrollbar style Oxlint plugin', () => {
   it.each(violations)('reports %s', (_name, source) => {
-    expect(lintSource(source)).toHaveLength(1)
+    expect(diagnosticsBySource.get(source)).toHaveLength(1)
   })
 
   it.each(accepted)('accepts %s', (_name, source) => {
-    expect(lintSource(source)).toEqual([])
+    expect(diagnosticsBySource.get(source)).toEqual([])
   })
 
   it.each([