fix(hooks): pass user-configured policyParams to custom policies (#585)

[AVPthegreat]

Summary

Fixes #585 by passing user-configured policyParams to custom policies and policies without a pre-defined schema in policy-evaluator.ts.

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❌ Root Cause Analysis

In src/hooks/policy-evaluator.ts (lines 94-106):

const schema = POLICY_PARAMS_MAP.get(policy.name);
let ctx: PolicyContext;
if (schema) {
  const userParams = getConfigParamsFor(config, policy.name) ?? {};
  // ...
  ctx = { ...baseCtx, params: resolvedParams };
} else {
  // Custom hooks and policies without schema get empty params
  ctx = { ...baseCtx, params: {} }; // <--- BUG!
}

Why it failed:

1. POLICY_PARAMS_MAP only contains schemas for built-in policies. For custom policies (e.g. custom/my-policy), schema is undefined.
2. When schema was undefined, the else branch unconditionally set params: {}.
3. It never called getConfigParamsFor(config, policy.name), meaning any policyParams: { "custom/my-policy": { maxCount: 10 } } configured in policies-config.json was completely ignored for custom policies.

---

✅ Fix Details

Updated the else branch in src/hooks/policy-evaluator.ts to query getConfigParamsFor(config, policy.name) when schema is undefined:

} else {
  // Custom hooks and policies without schema get user-configured params if present
  const userParams = getConfigParamsFor(config, policy.name) ?? {};
  ctx = { ...baseCtx, params: userParams };
}

---

🧪 Unit Tests & Verification

Added unit test in __tests__/hooks/policy-evaluator.test.ts:

it("passes user-configured policyParams to custom policies without schema", async () => {
  let capturedParams: unknown = null;
  registerPolicy("custom/my-policy", "desc", (ctx) => {
    capturedParams = ctx.params;
    return { decision: "allow" };
  }, { events: ["PreToolUse"] });

  const config = {
    enabledPolicies: ["custom/my-policy"],
    policyParams: {
      "custom/my-policy": { maxCount: 10, threshold: 5 },
    },
  };

  await evaluatePolicies("PreToolUse", { tool_name: "Bash" }, undefined, config);
  expect(capturedParams).toEqual({ maxCount: 10, threshold: 5 });
});

Test Results:

• Ran vitest run __tests__/hooks/policy-evaluator.test.ts
• Result: ✓ 70 passed (70)

Summary by CodeRabbit

• Bug Fixes

  • Custom policies without a defined parameter schema now receive their configured policy parameters during evaluation.
  • Policies continue to receive an empty parameter set when no configuration is provided.

• Tests

  • Added coverage verifying that custom policies receive configured parameters unchanged.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: e3f9ffb9-101e-4a8e-8f98-e4e145932ace

📥 Commits

Reviewing files that changed from the base of the PR and between af74838 and 0d7c9df.

📒 Files selected for processing (2)

• __tests__/hooks/policy-evaluator.test.ts
• src/hooks/policy-evaluator.ts

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📝 Walkthrough

Walkthrough

evaluatePolicies now forwards configured policyParams to custom policies without parameter schemas, while retaining an empty-object fallback. A Vitest test verifies that the configured values arrive unchanged in ctx.params.

Changes

Custom policy parameter forwarding

Layer / File(s)	Summary
Forward configured parameters and verify evaluation src/hooks/policy-evaluator.ts, __tests__/hooks/policy-evaluator.test.ts	Schema-less policies receive configured parameters through ctx.params, and a test confirms exact forwarding of { maxCount, threshold }.

Estimated code review effort: 2 (Simple) | ~10 minutes

Suggested reviewers: copilot

Poem

A bunny found params tucked out of sight,
And passed them along with a hop of delight.
Custom hooks now see
Their config decree—
No more empty baskets tonight!

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly summarizes the main fix: forwarding user-configured policyParams to custom policies.
Description check	✅ Passed	It explains the bug, fix, and test evidence, but it does not follow the template's Type of Change or Checklist sections.
Linked Issues check	✅ Passed	The code and test directly address #585 by passing configured policyParams to custom policies without schemas.
Out of Scope Changes check	✅ Passed	The changes stay focused on policy parameter forwarding and the corresponding unit test, with no unrelated edits.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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[hermes-exosphere]

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[Copilot]

Pull request overview

This PR fixes an evaluation gap in the hook policy system by ensuring custom policies (and any policies without a built-in params schema) receive user-configured policyParams via ctx.params, aligning behavior with user expectations and the existing config surface.

Changes:

• Updated evaluatePolicies() to pass getConfigParamsFor(config, policy.name) through when a policy has no schema (instead of always {}).
• Added a unit test verifying that a custom policy without schema receives configured params.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
src/hooks/policy-evaluator.ts	Passes user-configured params to schema-less/custom policies during evaluation.
tests/hooks/policy-evaluator.test.ts	Adds coverage to ensure custom policies without schema receive configured policyParams.

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