diff --git a/CLAUDE.md b/CLAUDE.md
index a22f317..4b86551 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -6,7 +6,7 @@ The first code coverage package that targets Node.js (V8), Bun (JSC), and Deno (
 >
 > - When an implementation goes wrong, avoid fixing progressively on top of errors, eliminate the error and implement the right approach in a clean and concise way.
 > - This document is living. If you complete a plan that changes the project structure (e.g., extract a shared module, introduce a new group/pattern), update the rules and examples below in the same commit. Do not let this document drift from repository reality.
->   - Always ask before changing this document.
+>   - **CLAUDE.md edits require explicit per-edit authorization.** "Plan approval", "Edit automatically" does not count.
 > - Do not write to "/tmp", instead use the "tools/debug" directory which is not tracked by Git.
 
 ---
@@ -62,14 +62,15 @@ The first code coverage package that targets Node.js (V8), Bun (JSC), and Deno (
 - **Put generic utilities under [src/utils/](src/utils/), never in domain files.** If a function does not depend on the scope it was written in, it does not belong there. Categorize by nature (`strings.ts`, `paths.ts`), never by consumer, never a `misc.ts`.
 - **Vendored code carries an attribution header.** Deliberate cuts from upstream are documented at the top of the vendored file, not here.
 - **Extract duplicated logic between sibling modules to a shared module in the same layer.** If N files in the same folder share the same skeleton with small parameterizable differences, extract the skeleton. The `shared/` pattern applies equally to `src/` and to test helpers.
-  - [src/runtimes/lifecycle.ts](src/runtimes/lifecycle.ts) for runtime setup and teardown.
+  - `src/runtimes/lifecycle/` for runtime setup and teardown.
   - `shared/` subfolders under [src/reporters/](src/reporters/), [src/converters/](src/converters/), and [test/**utils**/readers/](test/__utils__/readers/) for cross-consumer helpers.
   - AST primitives live in [src/converters/shared/](src/converters/shared/).
 - **Promote on second consumer. Never duplicate. Never import from a sibling.** The moment a helper in `reporters/text/` is needed by `reporters/html/`, it moves to `reporters/shared/` in the same commit. A sibling reporter (or converter) reaching into another's internals is a bug to fix, not a shortcut to use.
 - **Single file vs. directory with `index.ts` barrel.** When a file accumulates distinct responsibilities (discovery, parsing, serialization, orchestration), promote it to a directory. `index.ts` is strictly the orchestrator and public entry. Each responsibility goes into its own file. Established patterns: [src/reporters/text/](src/reporters/text/), [src/converters/v8-to-istanbul/](src/converters/v8-to-istanbul/), [src/converters/v8-nodefy/](src/converters/v8-nodefy/), [src/reporters/shared/lcov/](src/reporters/shared/lcov/), [src/configs/](src/configs/).
 - **Runtime envelope handling stays at the entry boundary.** [src/converters/v8-nodefy/](src/converters/v8-nodefy/) is the only site where Node-vs-Deno V8 envelopes are inspected. Everything downstream operates on the uniform `V8NodefiedDocument`.
 - **Bun's preload script lives at [src/runtimes/bun/preload.ts](src/runtimes/bun/preload.ts) and builds separately in `lib/preload-bun.js`.**
-- **`index.ts` is never a type aggregator.** Types still come from `@types/`.
+- **[src/core.ts](src/core.ts) is the boundary: [src/bin/](src/bin/) and [src/integrations/](src/integrations/) only import from it.**
+- **[src/integrations/](src/integrations/)\<runner\>.ts adapts the core to the shape an external test runner expects (e.g., `poku`, `vitest`, etc.).**
 
 ### Exports
 
diff --git a/src/@types/cli.ts b/src/@types/cli.ts
index 0b9d87b..ec0d329 100644
--- a/src/@types/cli.ts
+++ b/src/@types/cli.ts
@@ -1,4 +1,4 @@
-import type { PokuPlugin } from 'poku/plugins';
+import type { CoverageOptions, CoverageState } from './coverage.js';
 import type { Runtime } from './reporters.js';
 
 export type SpawnExitOutcome = {
@@ -9,10 +9,7 @@ export type SpawnExitOutcome = {
 export type SpawnRuntimeInputs = {
   runtime: Runtime;
   command: readonly string[];
-  plugin: PokuPlugin;
-};
-
-export type PluginContextMockInputs = {
-  runtime: Runtime;
   cwd: string;
+  options: CoverageOptions;
+  state: CoverageState;
 };
diff --git a/src/@types/coverage.ts b/src/@types/coverage.ts
index be65bf9..f13f063 100644
--- a/src/@types/coverage.ts
+++ b/src/@types/coverage.ts
@@ -1,9 +1,14 @@
 import type { CoverageThresholds } from './check-coverage.js';
-import type { Reporter } from './reporters.js';
+import type { Reporter, Runtime } from './reporters.js';
 import type { IDE } from './terminal.js';
 import type { TypesOptions } from './type-coverage.js';
 import type { Watermarks } from './watermarks.js';
 
+export type CoverageContext = {
+  cwd: string;
+  runtime: Runtime;
+};
+
 export type CoverageState = {
   enabled: boolean;
   tempDir: string;
diff --git a/src/bin/cli.ts b/src/bin/cli.ts
index 4671a50..70bec9d 100644
--- a/src/bin/cli.ts
+++ b/src/bin/cli.ts
@@ -1,9 +1,10 @@
 import type { SpawnExitOutcome } from '../@types/cli.js';
 import process from 'node:process';
-import { coverage } from '../index.js';
-import { pluginContextMock } from './plugin-context-mock.js';
+import { bun, config, deno, node, state } from '../core.js';
 import { runtime } from './runtime.js';
 
+const runtimes = { node, deno, bun } as const;
+
 const run = async (command: readonly string[]): Promise<void> => {
   if (command.length === 0) {
     process.stderr.write('coverage: missing command.\n');
@@ -11,29 +12,35 @@ const run = async (command: readonly string[]): Promise<void> => {
     return;
   }
 
-  let exitOutcome: SpawnExitOutcome = {
-    code: 0,
-    signal: null,
-  };
-
   const cwd = process.cwd();
   const detectedRuntime = runtime.get(command);
-  const plugin = coverage();
-  const context = pluginContextMock.create({
-    runtime: detectedRuntime,
-    cwd,
-  });
 
-  await plugin.setup?.(context);
+  const cliConfig = process.argv
+    .find((argument) => argument.startsWith('--coverageConfig'))
+    ?.split('=')[1];
+  const options = config.load(cwd, cliConfig);
+
+  const coverageState = state.create();
+  coverageState.cwd = cwd;
+
+  runtimes[detectedRuntime].setup(options, coverageState);
+
+  let exitOutcome: SpawnExitOutcome = { code: 0, signal: null };
 
   try {
     exitOutcome = await runtime.run({
       runtime: detectedRuntime,
       command,
-      plugin,
+      cwd,
+      options,
+      state: coverageState,
     });
   } finally {
-    await plugin.teardown?.(context);
+    runtimes[detectedRuntime].teardown(
+      { cwd, runtime: detectedRuntime },
+      options,
+      coverageState
+    );
   }
 
   if (exitOutcome.signal) {
diff --git a/src/bin/plugin-context-mock.ts b/src/bin/plugin-context-mock.ts
deleted file mode 100644
index 0113382..0000000
--- a/src/bin/plugin-context-mock.ts
+++ /dev/null
@@ -1,19 +0,0 @@
-import type { PluginContext, ReporterPlugin } from 'poku/plugins';
-import type { PluginContextMockInputs } from '../@types/cli.js';
-
-const create = ({ runtime, cwd }: PluginContextMockInputs): PluginContext => {
-  const now = new Date();
-
-  return {
-    configs: Object.create(null),
-    runtime,
-    cwd,
-    configFile: undefined,
-    runAsOnly: false,
-    results: { passed: 0, failed: 0, skipped: 0, todo: 0 },
-    timespan: { started: now, finished: now, duration: 0 },
-    reporter: Object.create(null) as ReturnType<ReporterPlugin>,
-  };
-};
-
-export const pluginContextMock = { create } as const;
diff --git a/src/bin/runtime.ts b/src/bin/runtime.ts
index 5a99bd3..43e1399 100644
--- a/src/bin/runtime.ts
+++ b/src/bin/runtime.ts
@@ -2,9 +2,12 @@ import type { SpawnExitOutcome, SpawnRuntimeInputs } from '../@types/cli.js';
 import type { Runtime } from '../@types/reporters.js';
 import { spawn } from 'node:child_process';
 import process from 'node:process';
+import { bun, deno, node } from '../core.js';
 
 const FORWARDED_SIGNALS: NodeJS.Signals[] = ['SIGINT', 'SIGTERM', 'SIGHUP'];
 
+const runtimes = { node, deno, bun } as const;
+
 const get = (command: readonly string[]): Runtime => {
   const firstToken = command[0] ?? '';
   const baseName =
@@ -22,9 +25,8 @@ const get = (command: readonly string[]): Runtime => {
 const run = (inputs: SpawnRuntimeInputs): Promise<SpawnExitOutcome> =>
   new Promise((resolveOutcome) => {
     const userCommand = inputs.command.slice();
-    const finalCommand = inputs.plugin.runner
-      ? inputs.plugin.runner(userCommand, '')
-      : userCommand;
+    const runtimeAdapter = runtimes[inputs.runtime];
+    const finalCommand = runtimeAdapter.runner(userCommand, '', inputs.state);
 
     if (finalCommand.length === 0) {
       process.stderr.write(
@@ -35,7 +37,7 @@ const run = (inputs: SpawnRuntimeInputs): Promise<SpawnExitOutcome> =>
     }
 
     const [binary, ...args] = finalCommand;
-    const needsPipedStderr = inputs.plugin.onTestProcess !== undefined;
+    const needsPipedStderr = runtimeAdapter.onTestProcess !== undefined;
     const child = spawn(binary, args, {
       stdio: needsPipedStderr ? ['inherit', 'inherit', 'pipe'] : 'inherit',
       shell: false,
@@ -45,7 +47,7 @@ const run = (inputs: SpawnRuntimeInputs): Promise<SpawnExitOutcome> =>
       child.stderr.pipe(process.stderr);
     }
 
-    inputs.plugin.onTestProcess?.(child, '');
+    runtimeAdapter.onTestProcess?.(child, '', inputs.state);
 
     const forwardSignal = (signal: NodeJS.Signals): void => {
       if (!child.killed) child.kill(signal);
diff --git a/src/converters/jsc-to-aggregation/index.ts b/src/converters/jsc-to-aggregation/index.ts
index 5c9233b..74c57b7 100644
--- a/src/converters/jsc-to-aggregation/index.ts
+++ b/src/converters/jsc-to-aggregation/index.ts
@@ -7,7 +7,7 @@ import type {
 import type { SourceMapDocument } from '../../@types/source-map.js';
 import type { FileAggregation } from '../../@types/v8.js';
 import { fileURLToPath, pathToFileURL } from 'node:url';
-import { fileFilter } from '../../file-filter.js';
+import { fileFilter } from '../../utils/file-filter.js';
 import { offsets } from '../../utils/offsets.js';
 import { paths } from '../../utils/paths.js';
 import { sourceLines } from '../../utils/source-lines.js';
diff --git a/src/converters/shared/pre-remap-filter.ts b/src/converters/shared/pre-remap-filter.ts
index f3af0f5..216b90f 100644
--- a/src/converters/shared/pre-remap-filter.ts
+++ b/src/converters/shared/pre-remap-filter.ts
@@ -3,7 +3,7 @@ import type {
   ResolvedScriptSource,
   V8ScriptCoverage,
 } from '../../@types/v8.js';
-import { fileFilter } from '../../file-filter.js';
+import { fileFilter } from '../../utils/file-filter.js';
 import { v8Discovery } from './v8-discovery.js';
 
 const passes = (
diff --git a/src/core.ts b/src/core.ts
new file mode 100644
index 0000000..03c6882
--- /dev/null
+++ b/src/core.ts
@@ -0,0 +1,5 @@
+export { config } from './configs/index.js';
+export { bun } from './runtimes/bun.js';
+export { deno } from './runtimes/deno.js';
+export { node } from './runtimes/node.js';
+export { state } from './runtimes/lifecycle/state.js';
diff --git a/src/index.ts b/src/index.ts
index 0c4f8ed..bb935a7 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -1,69 +1,2 @@
-import type { PokuPlugin } from 'poku/plugins';
-import type { CoverageOptions } from './@types/coverage.js';
-import type { Runtime } from './@types/reporters.js';
-import { isAbsolute, resolve } from 'node:path';
-import process from 'node:process';
-import { config } from './configs/index.js';
-import { bun } from './runtimes/bun.js';
-import { deno } from './runtimes/deno.js';
-import { node } from './runtimes/node.js';
-import { state } from './state.js';
-
 export type { CoverageOptions } from './@types/coverage.js';
-
-const runtimes = { node, deno, bun } as const;
-
-export const coverage = (
-  options: CoverageOptions = Object.create(null)
-): PokuPlugin => {
-  const coverageState = state.create();
-  let runtime: Runtime | undefined;
-  let resolvedOptions: CoverageOptions = options;
-
-  return {
-    name: '@pokujs/coverage',
-
-    setup(context) {
-      if (options.requireFlag && !process.argv.includes('--coverage')) return;
-
-      runtime = context.runtime;
-      coverageState.cwd = context.cwd;
-
-      const cliConfig = process.argv
-        .find((arg) => arg.startsWith('--coverageConfig'))
-        ?.split('=')[1];
-
-      const fileConfig = config.load(context.cwd, cliConfig ?? options.config);
-
-      resolvedOptions = { ...fileConfig, ...options };
-
-      runtimes[context.runtime].setup(context, resolvedOptions, coverageState);
-    },
-
-    runner(command, file) {
-      if (!runtime) return command;
-
-      const absoluteTestFile = isAbsolute(file)
-        ? file
-        : resolve(coverageState.cwd, file);
-
-      coverageState.testFiles.add(absoluteTestFile);
-
-      return runtimes[runtime].runner(command, file, coverageState);
-    },
-
-    onTestProcess(child, file) {
-      if (!runtime) return;
-
-      runtimes[runtime].onTestProcess?.(child, file, coverageState);
-    },
-
-    teardown(context) {
-      runtimes[context.runtime].teardown(
-        context,
-        resolvedOptions,
-        coverageState
-      );
-    },
-  };
-};
+export { coverage } from './integrations/poku.js';
diff --git a/src/integrations/poku.ts b/src/integrations/poku.ts
new file mode 100644
index 0000000..b511072
--- /dev/null
+++ b/src/integrations/poku.ts
@@ -0,0 +1,63 @@
+import type { PokuPlugin } from 'poku/plugins';
+import type { CoverageOptions } from '../@types/coverage.js';
+import type { Runtime } from '../@types/reporters.js';
+import { isAbsolute, resolve } from 'node:path';
+import process from 'node:process';
+import { bun, config, deno, node, state } from '../core.js';
+
+const runtimes = { node, deno, bun } as const;
+
+export const coverage = (
+  options: CoverageOptions = Object.create(null)
+): PokuPlugin => {
+  const coverageState = state.create();
+  let runtime: Runtime | undefined;
+  let resolvedOptions: CoverageOptions = options;
+
+  return {
+    name: '@pokujs/coverage',
+
+    setup(context) {
+      if (options.requireFlag && !process.argv.includes('--coverage')) return;
+
+      runtime = context.runtime;
+      coverageState.cwd = context.cwd;
+
+      const cliConfig = process.argv
+        .find((arg) => arg.startsWith('--coverageConfig'))
+        ?.split('=')[1];
+
+      const fileConfig = config.load(context.cwd, cliConfig ?? options.config);
+
+      resolvedOptions = { ...fileConfig, ...options };
+
+      runtimes[context.runtime].setup(resolvedOptions, coverageState);
+    },
+
+    runner(command, file) {
+      if (!runtime) return command;
+
+      const absoluteTestFile = isAbsolute(file)
+        ? file
+        : resolve(coverageState.cwd, file);
+
+      coverageState.testFiles.add(absoluteTestFile);
+
+      return runtimes[runtime].runner(command, file, coverageState);
+    },
+
+    onTestProcess(child, file) {
+      if (!runtime) return;
+
+      runtimes[runtime].onTestProcess?.(child, file, coverageState);
+    },
+
+    teardown(context) {
+      runtimes[context.runtime].teardown(
+        context,
+        resolvedOptions,
+        coverageState
+      );
+    },
+  };
+};
diff --git a/src/reporters/html-spa/build-data.ts b/src/reporters/html-spa/build-data.ts
index 669198b..3e943a2 100644
--- a/src/reporters/html-spa/build-data.ts
+++ b/src/reporters/html-spa/build-data.ts
@@ -10,13 +10,13 @@ import type {
   WatermarkMetric,
   Watermarks,
 } from '../../@types/watermarks.js';
-import { watermarks } from '../../watermarks.js';
 import {
   metricsForFile,
   metricsForSubtree,
 } from '../shared/html/row-metrics.js';
 import { metrics } from '../shared/metrics.js';
 import { skip } from '../shared/skip.js';
+import { watermarks } from '../shared/watermarks.js';
 
 const round2 = (value: number): number => Math.round(value * 100) / 100;
 
diff --git a/src/all-files.ts b/src/reporters/shared/all-files.ts
similarity index 93%
rename from src/all-files.ts
rename to src/reporters/shared/all-files.ts
index ef9115e..3e2bd4a 100644
--- a/src/all-files.ts
+++ b/src/reporters/shared/all-files.ts
@@ -1,12 +1,12 @@
-import type { CoverageMap, FileCoverage } from './@types/istanbul.js';
-import type { ReporterContext, Runtime } from './@types/reporters.js';
-import type { SourceContents } from './@types/source-discovery.js';
+import type { CoverageMap, FileCoverage } from '../../@types/istanbul.js';
+import type { ReporterContext, Runtime } from '../../@types/reporters.js';
+import type { SourceContents } from '../../@types/source-discovery.js';
 import { readdirSync, readFileSync } from 'node:fs';
 import { isAbsolute, join, resolve } from 'node:path';
-import { nonExecutableLines } from './converters/shared/non-executable-lines.js';
-import { fileFilter } from './file-filter.js';
-import { paths } from './utils/paths.js';
-import { sourceLines as sourceLinesUtil } from './utils/source-lines.js';
+import { nonExecutableLines } from '../../converters/shared/non-executable-lines.js';
+import { fileFilter } from '../../utils/file-filter.js';
+import { paths } from '../../utils/paths.js';
+import { sourceLines as sourceLinesUtil } from '../../utils/source-lines.js';
 
 const DEFAULT_SOURCE_EXTENSIONS: readonly string[] = [
   '.js',
diff --git a/src/reporters/shared/file-coverage.ts b/src/reporters/shared/file-coverage.ts
index 05f8129..bda2891 100644
--- a/src/reporters/shared/file-coverage.ts
+++ b/src/reporters/shared/file-coverage.ts
@@ -5,9 +5,9 @@ import type { ReporterContext } from '../../@types/reporters.js';
 import type { Metric } from '../../@types/text.js';
 import type { CoverageModel } from '../../@types/tree.js';
 import { readFileSync } from 'node:fs';
-import { allFiles } from '../../all-files.js';
 import { ignoreDirectives } from '../../converters/shared/ignore-directives.js';
-import { fileFilter } from '../../file-filter.js';
+import { fileFilter } from '../../utils/file-filter.js';
+import { allFiles } from './all-files.js';
 
 const filterCoverageMap = (
   coverageMap: CoverageMap,
diff --git a/src/reporters/shared/html/templates.ts b/src/reporters/shared/html/templates.ts
index 6080945..dc98b9e 100644
--- a/src/reporters/shared/html/templates.ts
+++ b/src/reporters/shared/html/templates.ts
@@ -10,8 +10,8 @@ import type {
   Watermarks,
 } from '../../../@types/watermarks.js';
 import { html } from '../../../utils/html.js';
-import { watermarks } from '../../../watermarks.js';
 import { metrics } from '../metrics.js';
+import { watermarks } from '../watermarks.js';
 import { relativeHref } from './link-mapper.js';
 
 export const metricReportClass = (
diff --git a/src/reporters/shared/lcov/filter.ts b/src/reporters/shared/lcov/filter.ts
index 8e41242..aeae10b 100644
--- a/src/reporters/shared/lcov/filter.ts
+++ b/src/reporters/shared/lcov/filter.ts
@@ -1,6 +1,6 @@
 import type { ResolvedFileFilter } from '../../../@types/file-filter.js';
 import { isAbsolute, resolve } from 'node:path';
-import { fileFilter } from '../../../file-filter.js';
+import { fileFilter } from '../../../utils/file-filter.js';
 import { paths } from '../../../utils/paths.js';
 
 export const filter = (
diff --git a/src/reporters/shared/lcov/runtimes/bun.ts b/src/reporters/shared/lcov/runtimes/bun.ts
index 14ebc71..7febf23 100644
--- a/src/reporters/shared/lcov/runtimes/bun.ts
+++ b/src/reporters/shared/lcov/runtimes/bun.ts
@@ -1,6 +1,6 @@
 import type { ReporterContext } from '../../../../@types/reporters.js';
-import { allFiles } from '../../../../all-files.js';
 import { lcovSerialize } from '../../../../converters/shared/lcov-serialize.js';
+import { allFiles } from '../../all-files.js';
 import { filter } from '../filter.js';
 
 const produce = (context: ReporterContext): string => {
diff --git a/src/reporters/shared/lcov/runtimes/v8-converter.ts b/src/reporters/shared/lcov/runtimes/v8-converter.ts
index 3fb3fbf..014b1ab 100644
--- a/src/reporters/shared/lcov/runtimes/v8-converter.ts
+++ b/src/reporters/shared/lcov/runtimes/v8-converter.ts
@@ -1,6 +1,6 @@
 import type { ReporterContext } from '../../../../@types/reporters.js';
-import { allFiles } from '../../../../all-files.js';
 import { lcovSerialize } from '../../../../converters/shared/lcov-serialize.js';
+import { allFiles } from '../../all-files.js';
 import { filter } from '../filter.js';
 
 const produce = (context: ReporterContext): string => {
diff --git a/src/watermarks.ts b/src/reporters/shared/watermarks.ts
similarity index 95%
rename from src/watermarks.ts
rename to src/reporters/shared/watermarks.ts
index 38733f2..8a43df0 100644
--- a/src/watermarks.ts
+++ b/src/reporters/shared/watermarks.ts
@@ -1,9 +1,9 @@
-import type { ColorName } from './@types/terminal.js';
+import type { ColorName } from '../../@types/terminal.js';
 import type {
   WatermarkLevel,
   WatermarkMetric,
   Watermarks,
-} from './@types/watermarks.js';
+} from '../../@types/watermarks.js';
 
 const DEFAULT_WATERMARKS: Watermarks = {
   statements: [50, 80],
diff --git a/src/reporters/text-summary/index.ts b/src/reporters/text-summary/index.ts
index 7922cf5..c3e5417 100644
--- a/src/reporters/text-summary/index.ts
+++ b/src/reporters/text-summary/index.ts
@@ -7,10 +7,10 @@ import type { Report, Runtime } from '../../@types/reporters.js';
 import type { Metric } from '../../@types/text.js';
 import type { WatermarkMetric } from '../../@types/watermarks.js';
 import { terminal } from '../../utils/terminal.js';
-import { watermarks } from '../../watermarks.js';
 import { fileCoverage } from '../shared/file-coverage.js';
 import { lcov } from '../shared/lcov/index.js';
 import { metrics } from '../shared/metrics.js';
+import { watermarks } from '../shared/watermarks.js';
 
 const KEY_WIDTH = 12;
 const HEADER =
diff --git a/src/reporters/text/table.ts b/src/reporters/text/table.ts
index b7040a6..7e8ff84 100644
--- a/src/reporters/text/table.ts
+++ b/src/reporters/text/table.ts
@@ -10,12 +10,12 @@ import type {
 import type { CoverageModel } from '../../@types/tree.js';
 import type { Watermarks } from '../../@types/watermarks.js';
 import { terminal } from '../../utils/terminal.js';
-import { watermarks } from '../../watermarks.js';
 import { metrics } from '../shared/metrics.js';
 import { nameCell } from '../shared/name-cell.js';
 import { ranges } from '../shared/ranges.js';
 import { skip } from '../shared/skip.js';
 import { tableRenderer } from '../shared/table.js';
+import { watermarks } from '../shared/watermarks.js';
 import { buildTree, walkTree } from './tree.js';
 
 const formatPercentageValue = (value: number | null): string =>
diff --git a/src/reporters/types/index.ts b/src/reporters/types/index.ts
index 5dc8453..fc210f0 100644
--- a/src/reporters/types/index.ts
+++ b/src/reporters/types/index.ts
@@ -1,6 +1,6 @@
 import type { Report } from '../../@types/reporters.js';
-import { allFiles } from '../../all-files.js';
 import { ide } from '../../utils/ide.js';
+import { allFiles } from '../shared/all-files.js';
 import { analyses } from './analyses.js';
 import { typesCoverage } from './coverage.js';
 import { typesDiscovery } from './discovery.js';
diff --git a/src/reporters/types/table.ts b/src/reporters/types/table.ts
index ba0b34a..8f1b871 100644
--- a/src/reporters/types/table.ts
+++ b/src/reporters/types/table.ts
@@ -7,11 +7,11 @@ import type {
 } from '../../@types/type-coverage.js';
 import type { Watermarks } from '../../@types/watermarks.js';
 import { terminal } from '../../utils/terminal.js';
-import { watermarks } from '../../watermarks.js';
 import { nameCell } from '../shared/name-cell.js';
 import { pathTree } from '../shared/path-tree.js';
 import { ranges } from '../shared/ranges.js';
 import { tableRenderer } from '../shared/table.js';
+import { watermarks } from '../shared/watermarks.js';
 
 const COLUMNS: readonly Column[] = [
   { header: 'Type Files', align: 'left' },
diff --git a/src/runtimes/bun.ts b/src/runtimes/bun.ts
index 4a0131f..83eceb1 100644
--- a/src/runtimes/bun.ts
+++ b/src/runtimes/bun.ts
@@ -1,6 +1,9 @@
 import type { ChildProcess } from 'node:child_process';
-import type { PluginContext } from 'poku/plugins';
-import type { CoverageOptions, CoverageState } from '../@types/coverage.js';
+import type {
+  CoverageContext,
+  CoverageOptions,
+  CoverageState,
+} from '../@types/coverage.js';
 import type { JscInspectorHandle } from '../@types/jsc.js';
 import type { DataListener } from '../@types/runtimes.js';
 import { join } from 'node:path';
@@ -8,7 +11,7 @@ import { moduleDir } from '../utils/module-dir.js';
 import { strings } from '../utils/strings.js';
 import { jscInspector } from './bun/inspector.js';
 import { FLUSH_MARKER } from './bun/marker.js';
-import { lifecycle } from './lifecycle.js';
+import { lifecycle } from './lifecycle/index.js';
 
 const INSPECTOR_URL_PATTERN =
   /ws:\/\/(?:\d{1,3}(?:\.\d{1,3}){3}|\[[0-9a-fA-F:]+\]|[A-Za-z0-9.-]+):\d{1,5}\/[A-Za-z0-9._-]+/;
@@ -138,17 +141,13 @@ const runner = (
 };
 
 export const bun = {
-  setup: (
-    _context: PluginContext,
-    options: CoverageOptions,
-    state: CoverageState
-  ): void => {
+  setup: (options: CoverageOptions, state: CoverageState): void => {
     lifecycle.setup(options, state, 'bun');
   },
   runner,
   onTestProcess,
   teardown: (
-    context: PluginContext,
+    context: CoverageContext,
     options: CoverageOptions,
     state: CoverageState
   ): void => lifecycle.teardown(context, options, state, 'bun'),
diff --git a/src/runtimes/deno.ts b/src/runtimes/deno.ts
index 1b7a2ef..a52628e 100644
--- a/src/runtimes/deno.ts
+++ b/src/runtimes/deno.ts
@@ -1,19 +1,19 @@
-import type { PluginContext } from 'poku/plugins';
-import type { CoverageOptions, CoverageState } from '../@types/coverage.js';
-import { lifecycle } from './lifecycle.js';
+import type {
+  CoverageContext,
+  CoverageOptions,
+  CoverageState,
+} from '../@types/coverage.js';
+import { lifecycle } from './lifecycle/index.js';
 
 const ENV_VAR = 'DENO_COVERAGE_DIR';
 
 export const deno = {
-  setup: (
-    _context: PluginContext,
-    options: CoverageOptions,
-    state: CoverageState
-  ): void => lifecycle.setup(options, state, 'deno', ENV_VAR),
+  setup: (options: CoverageOptions, state: CoverageState): void =>
+    lifecycle.setup(options, state, 'deno', ENV_VAR),
   runner: (command: string[]): string[] => command,
   onTestProcess: undefined,
   teardown: (
-    context: PluginContext,
+    context: CoverageContext,
     options: CoverageOptions,
     state: CoverageState
   ): void => lifecycle.teardown(context, options, state, 'deno', ENV_VAR),
diff --git a/src/check-coverage.ts b/src/runtimes/lifecycle/check-coverage.ts
similarity index 91%
rename from src/check-coverage.ts
rename to src/runtimes/lifecycle/check-coverage.ts
index 25e67ff..bc1a3a6 100644
--- a/src/check-coverage.ts
+++ b/src/runtimes/lifecycle/check-coverage.ts
@@ -2,22 +2,22 @@ import type {
   CoverageFailure,
   CoverageMetric,
   CoverageThresholds,
-} from './@types/check-coverage.js';
-import type { ReporterContext } from './@types/reporters.js';
-import type { Metric } from './@types/text.js';
-import type { CoverageModel } from './@types/tree.js';
+} from '../../@types/check-coverage.js';
+import type { ReporterContext } from '../../@types/reporters.js';
+import type { Metric } from '../../@types/text.js';
+import type { CoverageModel } from '../../@types/tree.js';
 import type {
   FileTypeCoverage,
   TypeCoverageReport,
-} from './@types/type-coverage.js';
-import type { WatermarkMetric } from './@types/watermarks.js';
+} from '../../@types/type-coverage.js';
+import type { WatermarkMetric } from '../../@types/watermarks.js';
 import { relative } from 'node:path';
 import process from 'node:process';
-import { fileCoverage } from './reporters/shared/file-coverage.js';
-import { lcov } from './reporters/shared/lcov/index.js';
-import { metrics } from './reporters/shared/metrics.js';
-import { terminal } from './utils/terminal.js';
-import { watermarks } from './watermarks.js';
+import { fileCoverage } from '../../reporters/shared/file-coverage.js';
+import { lcov } from '../../reporters/shared/lcov/index.js';
+import { metrics } from '../../reporters/shared/metrics.js';
+import { watermarks } from '../../reporters/shared/watermarks.js';
+import { terminal } from '../../utils/terminal.js';
 
 const METRIC_ORDER: readonly CoverageMetric[] = [
   'statements',
diff --git a/src/runtimes/lifecycle.ts b/src/runtimes/lifecycle/index.ts
similarity index 81%
rename from src/runtimes/lifecycle.ts
rename to src/runtimes/lifecycle/index.ts
index 003567f..26f4072 100644
--- a/src/runtimes/lifecycle.ts
+++ b/src/runtimes/lifecycle/index.ts
@@ -1,20 +1,23 @@
-import type { PluginContext } from 'poku/plugins';
-import type { DiscoveredBranch } from '../@types/branch-discovery.js';
-import type { CoverageOptions, CoverageState } from '../@types/coverage.js';
-import type { CoverageMap } from '../@types/istanbul.js';
-import type { ReporterContext, Runtime } from '../@types/reporters.js';
+import type { DiscoveredBranch } from '../../@types/branch-discovery.js';
+import type {
+  CoverageContext,
+  CoverageOptions,
+  CoverageState,
+} from '../../@types/coverage.js';
+import type { CoverageMap } from '../../@types/istanbul.js';
+import type { ReporterContext, Runtime } from '../../@types/reporters.js';
 import { mkdirSync, mkdtempSync, rmSync } from 'node:fs';
 import { tmpdir } from 'node:os';
 import { join, resolve } from 'node:path';
 import process from 'node:process';
-import { checkCoverage } from '../check-coverage.js';
-import { converters } from '../converters/index.js';
-import { discoveryMerge } from '../converters/shared/discovery-merge.js';
-import { fileFilter } from '../file-filter.js';
-import { reporters } from '../reporters/index.js';
-import { fileCoverage } from '../reporters/shared/file-coverage.js';
-import { watermarks } from '../watermarks.js';
-import { sourceMaps } from './source-maps.js';
+import { converters } from '../../converters/index.js';
+import { discoveryMerge } from '../../converters/shared/discovery-merge.js';
+import { reporters } from '../../reporters/index.js';
+import { fileCoverage } from '../../reporters/shared/file-coverage.js';
+import { watermarks } from '../../reporters/shared/watermarks.js';
+import { fileFilter } from '../../utils/file-filter.js';
+import { sourceMaps } from '../source-maps.js';
+import { checkCoverage } from './check-coverage.js';
 
 const setup = (
   options: CoverageOptions,
@@ -44,7 +47,7 @@ const setup = (
 };
 
 const teardown = (
-  context: PluginContext,
+  context: CoverageContext,
   options: CoverageOptions,
   state: CoverageState,
   runtime: Runtime,
diff --git a/src/state.ts b/src/runtimes/lifecycle/state.ts
similarity index 81%
rename from src/state.ts
rename to src/runtimes/lifecycle/state.ts
index 404af25..47de4b2 100644
--- a/src/state.ts
+++ b/src/runtimes/lifecycle/state.ts
@@ -1,4 +1,4 @@
-import type { CoverageState } from './@types/coverage.js';
+import type { CoverageState } from '../../@types/coverage.js';
 
 const create = (): CoverageState => ({
   enabled: false,
diff --git a/src/runtimes/node.ts b/src/runtimes/node.ts
index a454cbe..ccddb46 100644
--- a/src/runtimes/node.ts
+++ b/src/runtimes/node.ts
@@ -1,19 +1,19 @@
-import type { PluginContext } from 'poku/plugins';
-import type { CoverageOptions, CoverageState } from '../@types/coverage.js';
-import { lifecycle } from './lifecycle.js';
+import type {
+  CoverageContext,
+  CoverageOptions,
+  CoverageState,
+} from '../@types/coverage.js';
+import { lifecycle } from './lifecycle/index.js';
 
 const ENV_VAR = 'NODE_V8_COVERAGE';
 
 export const node = {
-  setup: (
-    _context: PluginContext,
-    options: CoverageOptions,
-    state: CoverageState
-  ): void => lifecycle.setup(options, state, 'node', ENV_VAR),
+  setup: (options: CoverageOptions, state: CoverageState): void =>
+    lifecycle.setup(options, state, 'node', ENV_VAR),
   runner: (command: string[]): string[] => command,
   onTestProcess: undefined,
   teardown: (
-    context: PluginContext,
+    context: CoverageContext,
     options: CoverageOptions,
     state: CoverageState
   ): void => lifecycle.teardown(context, options, state, 'node', ENV_VAR),
diff --git a/src/file-filter.ts b/src/utils/file-filter.ts
similarity index 94%
rename from src/file-filter.ts
rename to src/utils/file-filter.ts
index a9cfab3..fd9caa6 100644
--- a/src/file-filter.ts
+++ b/src/utils/file-filter.ts
@@ -1,9 +1,9 @@
 import type {
   FileFilterOptions,
   ResolvedFileFilter,
-} from './@types/file-filter.js';
-import { globs } from './utils/globs.js';
-import { paths } from './utils/paths.js';
+} from '../@types/file-filter.js';
+import { globs } from './globs.js';
+import { paths } from './paths.js';
 
 /*
  * Extends exclude list adapted from @istanbuljs/schema.
diff --git a/tools/build.mts b/tools/build.mts
index 67509e3..fafe514 100644
--- a/tools/build.mts
+++ b/tools/build.mts
@@ -1,15 +1,27 @@
-import type { BuildOptions } from 'esbuild';
+import type { BuildOptions, Plugin } from 'esbuild';
 import { chmod, mkdir, rm, writeFile } from 'node:fs/promises';
 import { generateDtsBundle } from 'dts-bundle-generator';
 import { build } from 'esbuild';
 
+const externalizeCore = (targetSpecifier: string): Plugin => ({
+  name: 'externalize-core',
+  setup(buildInstance) {
+    buildInstance.onResolve({ filter: /(^|\/)core\.js$/ }, () => ({
+      path: targetSpecifier,
+      external: true,
+    }));
+  },
+});
+
+const esmToCjs: Pick<BuildOptions, 'banner' | 'define'> = {
+  banner: {
+    js: "const __importMetaUrl = require('node:url').pathToFileURL(__filename).href;",
+  },
+  define: { 'import.meta.url': '__importMetaUrl' },
+};
+
 const [dtsBundle] = generateDtsBundle(
-  [
-    {
-      filePath: 'src/index.ts',
-      output: { noBanner: true },
-    },
-  ],
+  [{ filePath: 'src/index.ts', output: { noBanner: true } }],
   { preferredConfigPath: 'tsconfig.json' }
 );
 
@@ -33,22 +45,39 @@ const buildOptions: BuildOptions = {
 await rm('lib', { recursive: true, force: true });
 await mkdir('lib', { recursive: true });
 await Promise.all([
+  // Index
   build({
     ...buildOptions,
     format: 'esm',
     entryPoints: ['src/index.ts'],
     outfile: 'lib/index.js',
+    plugins: [externalizeCore('./core.js')],
   }),
   build({
     ...buildOptions,
+    ...esmToCjs,
     format: 'cjs',
     entryPoints: ['src/index.ts'],
     outfile: 'lib/index.cjs',
-    banner: {
-      js: "const __importMetaUrl = require('node:url').pathToFileURL(__filename).href;",
-    },
-    define: { 'import.meta.url': '__importMetaUrl' },
+    plugins: [externalizeCore('./core.cjs')],
+  }),
+
+  // Core
+  build({
+    ...buildOptions,
+    format: 'esm',
+    entryPoints: ['src/core.ts'],
+    outfile: 'lib/core.js',
+  }),
+  build({
+    ...buildOptions,
+    ...esmToCjs,
+    format: 'cjs',
+    entryPoints: ['src/core.ts'],
+    outfile: 'lib/core.cjs',
   }),
+
+  // Preload
   build({
     ...buildOptions,
     format: 'esm',
@@ -56,14 +85,18 @@ await Promise.all([
     outfile: 'lib/preload-bun.js',
     minify: true,
   }),
+
+  // CLI
   build({
     ...buildOptions,
     format: 'esm',
     entryPoints: ['src/bin/cli.ts'],
     outfile: 'lib/bin/cli.js',
     banner: { js: '#!/usr/bin/env node' },
-    external: ['../index.js'],
+    external: ['../core.js'],
   }),
+
+  // Declarations
   writeFile('lib/index.d.ts', dtsBundle, 'utf-8'),
 ]);