diff --git a/bounty-notes/issue-42-webhooks-test.md b/bounty-notes/issue-42-webhooks-test.md
new file mode 100644
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+++ b/bounty-notes/issue-42-webhooks-test.md
@@ -0,0 +1,34 @@
+# CodeBounty webhook verification for issue #42
+
+Fixes #42.
+
+This adds a deterministic webhook payload validation fixture for the CodeBounty webhook test issue. The fixture and validator let maintainers confirm that a bounty webhook event carries the fields required to route a bounty notification back to the correct GitHub issue and visible reward.
+
+## Added artifacts
+
+- `test-fixtures/codebounty-webhook-issue-42.json` — sample `bounty.available` payload for `CodeBountyOrg/BountyTestRepository#42` with the $150 visible bounty amount.
+- `scripts/validate-codebounty-webhook.mjs` — dependency-free Node.js validator that parses a webhook JSON file/stdin and checks:
+  - event name
+  - repository full name
+  - issue number
+  - positive bounty amount
+  - bounty status
+
+## Validation commands
+
+```bash
+node --check scripts/validate-codebounty-webhook.mjs
+node scripts/validate-codebounty-webhook.mjs test-fixtures/codebounty-webhook-issue-42.json
+```
+
+Expected normalized output:
+
+```json
+{
+  "event": "bounty.available",
+  "repository": "CodeBountyOrg/BountyTestRepository",
+  "issue": "#42",
+  "bounty": "$150",
+  "status": "available"
+}
+```
diff --git a/scripts/validate-codebounty-webhook.mjs b/scripts/validate-codebounty-webhook.mjs
new file mode 100644
index 0000000..a6a2152
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+++ b/scripts/validate-codebounty-webhook.mjs
@@ -0,0 +1,59 @@
+#!/usr/bin/env node
+import { readFileSync } from 'node:fs';
+
+const requiredString = (payload, path) => {
+  const value = path.split('.').reduce((current, key) => current?.[key], payload);
+  if (typeof value !== 'string' || value.trim() === '') {
+    throw new Error(`Missing required string: ${path}`);
+  }
+  return value.trim();
+};
+
+const requiredNumber = (payload, path) => {
+  const value = path.split('.').reduce((current, key) => current?.[key], payload);
+  if (typeof value !== 'number' || Number.isNaN(value)) {
+    throw new Error(`Missing required number: ${path}`);
+  }
+  return value;
+};
+
+const readPayload = () => {
+  const inputPath = process.argv[2];
+  const raw = inputPath ? readFileSync(inputPath, 'utf8') : readFileSync(0, 'utf8');
+  try {
+    return JSON.parse(raw);
+  } catch (error) {
+    throw new Error(`Webhook payload is not valid JSON: ${error.message}`);
+  }
+};
+
+const normalizeWebhookPayload = (payload) => {
+  const event = requiredString(payload, 'event');
+  const repository = requiredString(payload, 'repository.full_name');
+  const issueNumber = requiredNumber(payload, 'issue.number');
+  const bountyAmount = requiredNumber(payload, 'bounty.amount_usd');
+  const bountyStatus = requiredString(payload, 'bounty.status');
+
+  if (issueNumber <= 0) {
+    throw new Error('issue.number must be positive');
+  }
+
+  if (bountyAmount <= 0) {
+    throw new Error('bounty.amount_usd must be positive');
+  }
+
+  return {
+    event,
+    repository,
+    issue: `#${issueNumber}`,
+    bounty: `$${bountyAmount}`,
+    status: bountyStatus,
+  };
+};
+
+const main = () => {
+  const normalized = normalizeWebhookPayload(readPayload());
+  console.log(JSON.stringify(normalized, null, 2));
+};
+
+main();
diff --git a/test-fixtures/codebounty-webhook-issue-42.json b/test-fixtures/codebounty-webhook-issue-42.json
new file mode 100644
index 0000000..478507d
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+++ b/test-fixtures/codebounty-webhook-issue-42.json
@@ -0,0 +1,15 @@
+{
+  "event": "bounty.available",
+  "repository": {
+    "full_name": "CodeBountyOrg/BountyTestRepository"
+  },
+  "issue": {
+    "number": 42,
+    "title": "webhooks test"
+  },
+  "bounty": {
+    "amount_usd": 150,
+    "status": "available",
+    "provider": "CodeBounty"
+  }
+}