fix(ci): block agent PR title prefixes

.github/workflows/pr-title-check.yml

@@ -0,0 +1,21 @@
+name: PR Title Check
+
+on:
+  pull_request:
+    types: [opened, edited, synchronize, reopened]
+    branches: [main]
+
+permissions:
+  contents: read
+
+jobs:
+  pr-title:
+    name: Check PR title
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@34e114876b0b11c390a56381ad16ebd13914f8d5 # v4
+
+      - name: Check for agent/tool PR title prefix
+        env:
+          PR_TITLE: ${{ github.event.pull_request.title }}
+        run: node scripts/check-pr-title.cjs "$PR_TITLE"

AGENTS.md

@@ -4,6 +4,10 @@
 
 adcp-go is the Go SDK and reference implementation for the Ad Context Protocol (AdCP) Trusted Match Protocol (TMP). It provides a router, targeting engine, and reference agents for real-time ad package activation with structural privacy guarantees.
 
+## PR title hygiene
+
+Use concrete PR titles that describe the change. Do not prefix titles with the tool or model that authored the PR, such as `[codex]`, `[claude]`, `[cursor]`, or similar ownership tags. Put authoring-tool context in the PR body or labels when it matters, not in the review-facing title.
+
 ## Production hardening is a first-class priority
 
 This project is designed to run in trusted execution environments (TEEs) and be embedded into existing ad tech infrastructure (e.g., Prebid Server). Every change should consider:

scripts/check-pr-title.cjs

@@ -0,0 +1,18 @@
+#!/usr/bin/env node
+
+const title = (process.argv.slice(2).join(' ') || process.env.PR_TITLE || '').trim();
+
+if (!title) {
+  console.error('PR title is empty.');
+  process.exit(1);
+}
+
+const disallowedAgentPrefix =
+  /^\[(codex|claude|claude-code|openai|chatgpt|copilot|cursor|aider|devin|agent|ai)\](?:\s|:|-|$)/i;
+
+if (disallowedAgentPrefix.test(title)) {
+  console.error(`Invalid PR title: ${title}`);
+  console.error('Remove the leading agent/tool prefix. Use a concrete PR title instead, for example:');
+  console.error('  fix(ci): block agent PR title prefixes');
+  process.exit(1);
+}