diff --git a/.pre-commit-hooks.yaml b/.pre-commit-hooks.yaml
index 91ff7b4..cb9d274 100644
--- a/.pre-commit-hooks.yaml
+++ b/.pre-commit-hooks.yaml
@@ -144,3 +144,5 @@
   description: Run ansible-lint with Polymath settings
   entry: polymath_code_standard ansible
   types: [file]
+  # Each process installs ansible/requirements.yml into the same cache, so all files go to one process.
+  require_serial: true
diff --git a/CHANGELOG.md b/CHANGELOG.md
index fb27f03..b99bcf9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,16 @@
 All notable changes to this project are documented in this file.
 Releases follow semantic versioning as described in [DEVELOPING.md](./DEVELOPING.md).
 
+## 2.7.1
+
+### Fixed
+
+- `polymath-ansible` resolves collections that the repo develops under `ansible/collections/`.
+  Since 2.3.0 only the `.polymath-ansible/` cache was on the collections path.
+  Syntax-check reported the repo's own roles and playbooks as not found, unless the playbook sat beside a `collections/` directory.
+- `polymath-ansible` runs as a single process.
+  Under `--all-files`, parallel runs installed `ansible/requirements.yml` into the same cache at once and failed with "Directory not empty".
+
 ## 2.7.0
 
 Minor bump: a new check in `polymath-general`.
diff --git a/README.md b/README.md
index 01a5afd..c184ed1 100644
--- a/README.md
+++ b/README.md
@@ -36,7 +36,7 @@ Use only the hooks that apply to your project.
 ---
 repos:
   - repo: https://github.com/polymathrobotics/polymath_code_standard
-    rev: v2.7.0
+    rev: v2.7.1
     hooks:
       # File hygiene for all staged files
       - id: polymath-general
@@ -330,6 +330,7 @@ No arguments.
 
 Installs Ansible collections and roles from `ansible/requirements.yml` and runs `ansible-lint` with Polymath's configuration.
 Dependencies are cached in `.polymath-ansible/` (automatically gitignored) and only reinstalled when `requirements.yml` changes.
+Collections the repo develops itself under `ansible/collections/` resolve from the working tree.
 
 No arguments.
 
diff --git a/polymath_code_standard/checkers/ansible/__init__.py b/polymath_code_standard/checkers/ansible/__init__.py
index 2900ffb..ad05e45 100644
--- a/polymath_code_standard/checkers/ansible/__init__.py
+++ b/polymath_code_standard/checkers/ansible/__init__.py
@@ -4,6 +4,7 @@
 import hashlib
 import importlib.resources
 import json
+import os
 from pathlib import Path
 
 import yaml
@@ -13,6 +14,9 @@
 # Config files bundled alongside this checker
 CONFIG_DIR = importlib.resources.files(__package__)
 
+# Where a repo keeps the collections it develops itself, so its playbooks resolve them from the working tree.
+REPO_COLLECTIONS_DIR = Path('ansible/collections')
+
 # Where a repo declares the collections and roles its playbooks import.
 REQUIREMENTS = Path('ansible/requirements.yml')
 
@@ -67,7 +71,7 @@ def run(self, args: argparse.Namespace) -> list[Result]:
                 args.files,
                 name='ansible-lint',
                 env={
-                    'ANSIBLE_COLLECTIONS_PATH': str(COLLECTIONS_DIR),
+                    'ANSIBLE_COLLECTIONS_PATH': os.pathsep.join([str(REPO_COLLECTIONS_DIR), str(COLLECTIONS_DIR)]),
                     'ANSIBLE_ROLES_PATH': str(ROLES_DIR),
                 },
             )
diff --git a/pyproject.toml b/pyproject.toml
index 9e175ea..0a925c7 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "polymath-code-standard"
-version = "2.7.0"
+version = "2.7.1"
 description = "Polymath Code Standard pre-commit hooks"
 requires-python = ">=3.10"
 dependencies = [
diff --git a/tests/test_ansible.py b/tests/test_ansible.py
index 20fd0e7..413e6f2 100644
--- a/tests/test_ansible.py
+++ b/tests/test_ansible.py
@@ -58,6 +58,22 @@ def test_ansible_installs_requirements(tmp_path, monkeypatch):
     assert ansible_checker.AnsibleGroup._install_requirements() == []
 
 
+def test_ansible_resolves_repo_collection(tmp_path, monkeypatch):
+    """A playbook resolves a collection the repo develops under ansible/collections."""
+    role = tmp_path / 'ansible' / 'collections' / 'ansible_collections' / 'acme' / 'local' / 'roles' / 'greet'
+    (role / 'tasks').mkdir(parents=True)
+    (role / 'tasks' / 'main.yml').write_text('---\n- name: Greet\n  ansible.builtin.debug:\n    msg: hello\n')
+    # Ansible finds a collections/ directory beside the playbook by itself, so nest the playbook away from it.
+    scenario = tmp_path / 'ansible' / 'scenarios' / 'greet'
+    scenario.mkdir(parents=True)
+    (scenario / 'converge.yml').write_text(
+        '---\n- name: Greet some computer\n  hosts: all\n  roles:\n    - role: acme.local.greet\n'
+    )
+    monkeypatch.chdir(tmp_path)
+
+    assert runner.main(['ansible', 'ansible/scenarios/greet/converge.yml']) == 0
+
+
 def test_ansible_stamp_tracks_requirements(tmp_path, monkeypatch):
     monkeypatch.chdir(tmp_path)
     (tmp_path / 'ansible').mkdir()
diff --git a/uv.lock b/uv.lock
index d6244ed..7e3bcd0 100644
--- a/uv.lock
+++ b/uv.lock
@@ -829,7 +829,7 @@ wheels = [
 
 [[package]]
 name = "polymath-code-standard"
-version = "2.7.0"
+version = "2.7.1"
 source = { editable = "." }
 dependencies = [
     { name = "ansible-lint" },