fix: lower the pipeline floor to Python 3.9

The 3.12 guard rested on generate_readme f-strings that have since been
rewritten. Every script compiles under CPython 3.9.25, 3.10 and 3.11, and
only generate_pack's parenthesized context managers fail under 3.8. Under
3.9 the offline pipeline (--skip-packs) completed with no change to the
committed artifacts, the 15 manifests matched 3.12 byte for byte, and the
RomM pack was identical. CI now compiles every script under a real 3.9.

.github/workflows/validate.yml

@@ -165,12 +165,14 @@ jobs:
       - uses: actions/checkout@3d3c42e5aac5ba805825da76410c181273ba90b1  # v7
 
       # install.py stays on Python 3.8: the suite runs it end to end under a
-      # real 3.8 interpreter, which import-only and grammar checks miss. The
-      # last version listed is the default python.
+      # real 3.8 interpreter, which import-only and grammar checks miss. 3.9
+      # is the floor pipeline.py states for the build scripts, compiled under
+      # a real 3.9. The last version listed is the default python.
       - uses: actions/setup-python@5fda3b95a4ea91299a34e894583c3862153e4b97  # v7
         with:
           python-version: |
             3.8
+            3.9
             3.12
 
       # markdown: the site validation test renders a wiki line to prove the

README.md

@@ -131,7 +131,7 @@ python scripts/verify.py --emulator flycast
 python scripts/verify.py --platform retroarch --verbose  # emulator ground truth
 ```
 
-Requires Python 3.12 and `pyyaml`. The one-line installer alone runs on Python 3.8.
+Requires Python 3.9 or newer and `pyyaml`. The one-line installer alone runs on Python 3.8.
 
 ## Documentation site
 
@@ -180,4 +180,4 @@ The scripts and tooling are released under the [MIT License](LICENSE).
 The BIOS and firmware files are not covered by that license: they are third-party system software, preserved and provided for personal backup, archival, and interoperability with emulation software. [NOTICE](NOTICE) sets out their status and how to ask for a file to be removed.
 The reasoning, and where it is weakest, is in the [FAQ](https://abdess.github.io/retrobios/wiki/faq/#is-this-legal).
 
-*Auto-generated on 2026-10-20T20:53:07Z*
+*Auto-generated on 2026-10-21T03:32:18Z*

pyproject.toml

@@ -4,9 +4,8 @@ version = "1.0.0"
 description = "BIOS collection manager for retrogaming platforms"
 # install.py is the only entry point a user runs before cloning, and both
 # bootstraps accept 3.8, so the floor stays where the bootstraps put it. That
-# floor covers install.py alone: the build scripts under scripts/ use syntax
-# CPython 3.12 introduced, which is the version CI pins and the version a
-# contributor needs to run the pipeline or the test suite.
+# floor covers install.py alone: the build scripts under scripts/ need 3.9
+# (pipeline.py checks it), and CI runs the test suite on 3.12.
 requires-python = ">=3.8"
 dependencies = [
     "pyyaml",

scripts/generate_readme.py

@@ -582,7 +582,7 @@ def generate_readme(db: dict, platforms_dir: str) -> str:
             "python scripts/verify.py --platform retroarch --verbose  # emulator ground truth",
             "```",
             "",
-            "Requires Python 3.12 and `pyyaml`. The one-line installer alone runs on Python 3.8.",
+            "Requires Python 3.9 or newer and `pyyaml`. The one-line installer alone runs on Python 3.8.",
             "",
             "## Documentation site",
             "",

scripts/pipeline.py

@@ -51,11 +51,13 @@ import sys
 import time
 from pathlib import Path
 
-# The build scripts use syntax CPython 3.12 introduced (generate_readme's
-# f-strings, generate_pack's parenthesized context managers). On an older
-# interpreter the run got through the packs and failed hours in, at step 7.
-if sys.version_info < (3, 12):
-    sys.exit(f"pipeline.py needs Python 3.12 or newer, this is {sys.version.split()[0]}")
+# generate_pack's parenthesized context managers do not compile before
+# CPython 3.9, which builds the same database, manifests and packs as 3.12.
+# On an older interpreter the run got through the first steps and failed in
+# the packs, so it stops before step 0. A test compiles every script under
+# this floor.
+if sys.version_info < (3, 9):
+    sys.exit(f"pipeline.py needs Python 3.9 or newer, this is {sys.version.split()[0]}")
 
 sys.path.insert(0, str(Path(__file__).parent))
 from common import (

tests/test_audit_regressions.py

@@ -108,7 +108,41 @@ class ReadmeRegressions(unittest.TestCase):
             cwd=ROOT, capture_output=True, text=True, timeout=60, check=False,
         )
         self.assertEqual(proc.returncode, 1)
-        self.assertIn("needs Python 3.12", proc.stderr)
+        self.assertIn("needs Python 3.9", proc.stderr)
+
+    def test_the_floor_interpreter_compiles_every_script(self):
+        """The floor said 3.12 for a reason the code no longer carried: every
+        script compiled under 3.9, and only the guard refused it. Checked
+        with a real interpreter of the floor version, as the installer's 3.8
+        floor is."""
+        import shutil  # noqa: PLC0415
+
+        floor = re.search(
+            r"sys\.version_info < \((\d+), (\d+)\)",
+            (ROOT / "scripts" / "pipeline.py").read_text(encoding="utf-8"),
+        )
+        name = f"python{floor.group(1)}.{floor.group(2)}"
+        interpreter = shutil.which(name)
+        if interpreter is None:
+            if os.environ.get("CI"):
+                self.fail(f"CI must provide {name}")
+            self.skipTest(f"no {name} on PATH")
+        check = (
+            "import pathlib, sys\n"
+            "bad = []\n"
+            "for p in sorted(pathlib.Path('scripts').rglob('*.py')):\n"
+            "    try:\n"
+            "        compile(p.read_text(encoding='utf-8'), str(p), 'exec')\n"
+            "    except SyntaxError as e:\n"
+            "        bad.append(f'{p}:{e.lineno}')\n"
+            "print(bad)\n"
+            "sys.exit(1 if bad else 0)\n"
+        )
+        proc = subprocess.run(
+            [interpreter, "-I", "-c", check], cwd=ROOT, capture_output=True,
+            text=True, timeout=300, check=False,
+        )
+        self.assertEqual(proc.returncode, 0, proc.stdout + proc.stderr)
 
 
 class ReleaseSigningRegressions(unittest.TestCase):

wiki/installer.md

@@ -471,7 +471,7 @@ followed.
 RetroPie image, so it stays on Python 3.8 and the standard library alone.
 Tests refuse any 3.9 syntax or API, and one runs the installer end to end under
 a real 3.8 interpreter, which CI installs beside 3.12 so the check cannot skip.
-The build scripts need 3.12 and are not bound by this.
+The build scripts need 3.9 and are not bound by this.
 
 Every change to `install.py` recomputes the SHA-256 pinned in `install.sh` and
 `install.ps1` in the same commit. The tests compare the pins with the file.

wiki/testing-guide.md

@@ -24,7 +24,7 @@ python -m unittest tests.test_install tests.test_install_cores -v
 
 The table below says which module covers what.
 
-Running the build needs Python 3.12 and `pyyaml` alone, and so does most of the suite. The
+Running the build needs Python 3.9 or newer and `pyyaml` alone. CI runs the suite on 3.12. The
 schema contract tests also need `jsonschema[format-nongpl]`, and one site test
 renders a wiki line with `markdown`. The CI installs both: without them those
 tests are reported as skipped, so install them before a pull request

wiki/tools.md

@@ -1,6 +1,6 @@
 # Tools
 
-All tools are Python scripts in `scripts/`. They need Python 3.12 and `pyyaml`,
+All tools are Python scripts in `scripts/`. They need Python 3.9 or newer and `pyyaml`,
 and only `validate_schemas.py` also needs `jsonschema[format-nongpl]`. `install.py`
 alone runs on Python 3.8.