diff --git a/scripts/pipeline.py b/scripts/pipeline.py
index f4a75922..e813e9bc 100644
--- a/scripts/pipeline.py
+++ b/scripts/pipeline.py
@@ -2,6 +2,7 @@
 """Run the full retrobios pipeline.
 
 Steps, numbered as the run prints them:
+  0    validate_schemas.py          profiles and platform YAMLs, as PR CI checks them
   1    generate_db.py --force       rebuild database.json from bios/
   1b   provenance_report.py         dump-catalog coverage, derivable.json
   1c   romset_recipes.py            archive identification, reconstruction targets
@@ -39,6 +40,7 @@ from __future__ import annotations
 
 import argparse
 import contextlib
+import importlib.util
 import os
 import re
 import subprocess
@@ -469,6 +471,20 @@ def main() -> None:
     total_start = time.monotonic()
     results = StepResults(total_start)
 
+    # Step 0: the schema check PR validation runs. Without it a profile with
+    # `cores: [81]` unquoted passed the whole pipeline and failed CI on push.
+    # jsonschema is tooling only, so its absence skips the step.
+    if importlib.util.find_spec("jsonschema") is None:
+        print("\n--- 0/8 validate schemas: SKIPPED (jsonschema not installed) ---")
+        results["validate_schemas"] = SKIPPED
+    else:
+        ok, _ = run(
+            [sys.executable, "scripts/validate_schemas.py", "--source-only"],
+            "0/8 validate schemas",
+        )
+        results["validate_schemas"] = ok
+        all_ok = all_ok and ok
+
     # Step 1: Generate database
     ok, out = run(
         [
diff --git a/tests/test_audit_regressions.py b/tests/test_audit_regressions.py
index a6394a7b..a0a19423 100644
--- a/tests/test_audit_regressions.py
+++ b/tests/test_audit_regressions.py
@@ -5572,5 +5572,20 @@ class AHashConflictIsReportedOnce(unittest.TestCase):
         self.assertEqual(err.getvalue().count("WARNING"), 1)
 
 
+class ThePipelineRunsTheSchemaCheckCIRuns(unittest.TestCase):
+    """The pipeline the repository asks for after every change never ran
+    validate_schemas.py, which PR validation does: a profile with an
+    unquoted numeric core name passed it and failed CI on push."""
+
+    def test_the_ci_command_is_a_pipeline_step(self):
+        workflow = (ROOT / ".github" / "workflows" / "validate.yml").read_text(encoding="utf-8")
+        command = re.search(r"python (scripts/validate_schemas\.py[^\n]*)", workflow).group(1)
+        script, *flags = command.split()
+        source = (ROOT / "scripts" / "pipeline.py").read_text(encoding="utf-8")
+        self.assertIn(f'"{script}"', source)
+        for flag in flags:
+            self.assertIn(f'"{flag}"', source)
+
+
 if __name__ == "__main__":
     unittest.main()
diff --git a/wiki/adding-a-platform.md b/wiki/adding-a-platform.md
index 301bf639..269ac7dc 100644
--- a/wiki/adding-a-platform.md
+++ b/wiki/adding-a-platform.md
@@ -365,6 +365,7 @@ python scripts/pipeline.py --offline
 
 This executes in sequence:
 
+0. `validate_schemas.py --source-only` - the schema check PR validation runs
 1. `generate_db.py` - rebuild `database.json` from `bios/`
 1b. `provenance_report.py` - dump-catalog coverage from `provenance/`
 2. `refresh_data_dirs.py` - update data directories (skipped with `--offline`)
diff --git a/wiki/tools.md b/wiki/tools.md
index 6adb1ffd..c3ca6b28 100644
--- a/wiki/tools.md
+++ b/wiki/tools.md
@@ -23,6 +23,7 @@ Pipeline steps:
 
 | Step | Description | Skipped by |
 |------|-------------|------------|
+| 0/8 | Validate profiles and platform YAMLs against the schemas | - (no `jsonschema` installed) |
 | 1/8 | Generate database | - |
 | 1b | Dump-catalog coverage report | - (offline, reads `provenance/`) |
 | 1c | Romset recipes: identify archives, list rebuild targets | - (offline, reads `recipes/`) |