feat(policy): support native PolicyPlugin exports from module files

[yxbh]

Summary

• What changed
• Why it changed

What changed

Add support for loading native PolicyPlugin exports directly from .js/.mjs module files. The plugin loader (loadPluginChain) now detects modules that export a PolicyPlugin object (identified by a meta property) and adds them directly to the plugin chain with trusted-code trust, instead of requiring compilation through PolicyConfig.

Files changed:

File	Change
packages/core/.../policy/types.ts	Add isNativePlugin() type guard and validateNativePlugin()
packages/core/.../policy/index.ts	Export new functions
packages/core/.../policy.ts	Update loadPolicy() return type to PolicyConfig | PolicyPlugin, detect native exports, fix Windows import() with pathToFileURL
packages/core/.../policy/loader.ts	Handle native plugins in loadPluginChain() — add directly to chain
packages/core/.../readiness/index.ts	Guard legacy resolveChain path against native plugin exports
src/.../__tests__/policy-engine-types.test.ts	14 tests for isNativePlugin and validateNativePlugin
src/.../__tests__/policy-loader.test.ts	6 tests for native plugin loading and engine execution
src/.../__tests__/policy.test.ts	Fix type narrowing for loadPolicy() union return type

Why it changed

The plugin engine already supports a rich 5-stage pipeline (detect → afterDetect → beforeRecommend → recommend → afterRecommend) with immutable patch types (SignalPatch, RecommendationPatch). However, loadPluginChain() only accepted PolicyConfig objects and compiled them — module authors could not export a raw PolicyPlugin to use the full hook API.

This limited what policy modules can do:

• No signal mutation — can't modify signals from other detectors (e.g., change status, add metadata)
• No cross-signal recommendations — can't compose recommendations based on signals from multiple detectors
• No recommendation patching — can't modify or remove recommendations from other plugins

Corporate/enterprise policies (e.g., tool governance, MCP server allow/deny lists) need these capabilities.

Example usage

// Before: PolicyConfig (criteria DSL) — limited to add/disable/override
export default {
  name: 'my-policy',
  criteria: { add: [...], disable: [...] }
};

// After: Native PolicyPlugin — full lifecycle hooks
export default {
  meta: { name: 'my-policy', sourceType: 'module', trust: 'trusted-code' },
  afterDetect: async (signals, ctx) => ({
    modify: signals
      .filter(s => s.metadata?.type === 'cursorrules')
      .map(s => ({ id: s.id, changes: { status: 'error', metadata: { blocked: true } } }))
  }),
  afterRecommend: async (recs, signals, ctx) => ({
    add: [{
      id: 'custom-rec', signalId: '...', impact: 'critical',
      message: '...', origin: { addedBy: 'my-policy' }
    }]
  })
};

Checklist

• Tests added or updated (20 new tests, 657 total passing)
• Lint/typecheck pass
• Docs updated if needed (no user-facing docs changes needed — this extends an internal API)

[Copilot]

Pull request overview

Adds first-class support for module-exported “native” PolicyPlugin objects (with lifecycle hooks) alongside existing PolicyConfig-based policies, so policy authors can use the full plugin engine pipeline.

Changes:

• Introduces isNativePlugin() and validateNativePlugin() to detect/validate native plugin exports.
• Updates loadPolicy() and loadPluginChain() to load native PolicyPlugin exports and force sourceType: "module" + trust: "trusted-code".
• Adds tests covering type guards/validation, loading native plugins, and engine execution behavior.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/services/tests/policy-loader.test.ts	Adds end-to-end tests for loading/executing native plugin modules in a plugin chain.
src/services/tests/policy-engine-types.test.ts	Adds unit tests for isNativePlugin() and validateNativePlugin().
packages/core/src/services/readiness/index.ts	Guards the legacy resolveChain path against native plugin exports.
packages/core/src/services/policy/types.ts	Adds the native plugin type guard + validator helpers.
packages/core/src/services/policy/loader.ts	Accepts native plugin exports directly into the engine chain with trusted-code trust.
packages/core/src/services/policy/index.ts	Re-exports the new helper APIs from the policy service entrypoint.
packages/core/src/services/policy.ts	Expands loadPolicy() to return `PolicyConfig

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 9 out of 9 changed files in this pull request and generated 4 comments.

[Copilot]

Pull request overview

Copilot reviewed 8 out of 8 changed files in this pull request and generated 3 comments.

[yxbh]

Closing to open a clean PR with squashed history.