docs: drop the upstream remote from CONTRIBUTING

profile_sync.py finds and fetches the project's main by itself. The
documented --base upstream/main failed in any clone without that remote,
where the same command without --base passes.

CONTRIBUTING.md

@@ -71,7 +71,7 @@ the checks CI runs on a pull request (Python 3.12 or newer):
 pip install pyyaml "jsonschema[format-nongpl]" markdown pyte hypothesis vermin
 python scripts/validate_pr.py --changed          # the BIOS files the branch adds
 python scripts/validate_schemas.py --source-only # profiles and platform files
-python scripts/profile_sync.py --added --base upstream/main --strict  # each profile the branch adds
+python scripts/profile_sync.py --added --strict  # each profile the branch adds
 python scripts/refresh_data_dirs.py  # data directories the pack-building tests read
 python scripts/generate_site.py       # the pages the site tests read
 npm ci --prefix website && npm run build --prefix website  # the built site, Node 24
@@ -80,10 +80,9 @@ python scripts/validate_site.py --site-dir website/dist  # links and page budget
 vermin --no-tips -t=3.8- --violations install.py         # install.py stays on Python 3.8
 ```
 
-`upstream` is this repository as a remote of your fork
-(`git remote add upstream https://github.com/Abdess/retrobios`, then
-`git fetch upstream`). A profile you only edit is not held to `--strict`: its
-older refs are reviewed by hand.
+`profile_sync.py` compares the branch with this repository's `main`, and
+fetches it in a fork's clone. A profile you only edit is not held to
+`--strict`: its older refs are reviewed by hand.
 
 The full pipeline is not needed for a contribution: it rebuilds every pack
 in `dist/`, which is why maintainers run it before a release.

scripts/generate_readme.py

@@ -981,7 +981,7 @@ the checks CI runs on a pull request (Python 3.12 or newer):
 pip install pyyaml "jsonschema[format-nongpl]" markdown pyte hypothesis vermin
 python scripts/validate_pr.py --changed          # the BIOS files the branch adds
 python scripts/validate_schemas.py --source-only # profiles and platform files
-python scripts/profile_sync.py --added --base upstream/main --strict  # each profile the branch adds
+python scripts/profile_sync.py --added --strict  # each profile the branch adds
 python scripts/refresh_data_dirs.py  # data directories the pack-building tests read
 python scripts/generate_site.py       # the pages the site tests read
 npm ci --prefix website && npm run build --prefix website  # the built site, Node 24
@@ -990,10 +990,9 @@ python scripts/validate_site.py --site-dir website/dist  # links and page budget
 vermin --no-tips -t=3.8- --violations install.py         # install.py stays on Python 3.8
 ```
 
-`upstream` is this repository as a remote of your fork
-(`git remote add upstream https://github.com/Abdess/retrobios`, then
-`git fetch upstream`). A profile you only edit is not held to `--strict`: its
-older refs are reviewed by hand.
+`profile_sync.py` compares the branch with this repository's `main`, and
+fetches it in a fork's clone. A profile you only edit is not held to
+`--strict`: its older refs are reviewed by hand.
 
 The full pipeline is not needed for a contribution: it rebuilds every pack
 in `dist/`, which is why maintainers run it before a release.

tests/test_contributing_text.py

@@ -75,7 +75,8 @@ class BeforeOpeningAPullRequest(unittest.TestCase):
         # CI holds added profiles to their upstream, not edited ones: --changed
         # failed a contributor on refs they never wrote.
         self.assertIn("profile_sync.py --added --base", workflow)
-        self.assertIn("profile_sync.py --added --base upstream/main --strict", block)
+        self.assertIn("profile_sync.py --added --strict", block)
+        self.assertNotIn("upstream/main", section)
         self.assertNotIn("--changed --strict", block)
 
     def test_it_names_the_site_build_and_the_packages_ci_runs(self):

tests/test_profile_sync.py

@@ -6017,7 +6017,11 @@ class TestBranchCheckIsWired(unittest.TestCase):
         import generate_readme  # noqa: PLC0415
 
         text = generate_readme.generate_contributing()
-        self.assertIn("profile_sync.py --added --base upstream/main --strict", text)
+        self.assertIn("profile_sync.py --added --strict", text)
+        # The default base is fetched by the tool: a documented upstream
+        # remote failed every clone that had origin alone.
+        self.assertNotIn("--base upstream/main", text)
+        self.assertNotIn("remote add upstream", text)
         self.assertNotIn("--emulator NAME --strict", text)
         workflow = (root / ".github" / "workflows" / "validate.yml").read_text()
         self.assertIn("profile_sync.py --added --base", workflow)

wiki/tools.md

@@ -475,7 +475,7 @@ python scripts/profile_sync.py --all --stale-before 2026-06-01 --limit 20 --tria
 python scripts/profile_sync.py --emulator vice --full-diff --ref vice/src/c64/c64rom.h --context 6
 python scripts/profile_sync.py --emulator vice --strict
 python scripts/profile_sync.py --changed --strict
-python scripts/profile_sync.py --added --base upstream/main --strict
+python scripts/profile_sync.py --added --strict
 ```
 
 Per part of a ref: `ANCHORED` (same content, same lines), `SHIFTED` (same