Documented unquoted template syntax causes YAML parsing error

[paduszyk]

Description

Using a template at the beginning of an unquoted run value causes Lefthook to fail while parsing the configuration:

Error: yaml: line 8: did not find expected key

The current templates documentation recommends this syntax:

- run: {wrapper} yarn format

However, { begins a flow mapping in YAML. It therefore cannot begin an unquoted plain scalar. Lefthook fails during YAML parsing before template substitution occurs.

Quoting the value or using a block scalar resolves the error:

- run: "{wrapper} yarn format"

- run: |
    {wrapper} yarn format

lefthook.yml

templates:
  wrapper: npm exec --no --

pre-commit:
  jobs:
    - name: Prettier
      run: {wrapper} prettier --check .

Commands to reproduce

export LEFTHOOK_VERBOSE=true
npx lefthook validate

Alternatively:

export LEFTHOOK_VERBOSE=true
npx lefthook run pre-commit --all-files

Observed result:

Error: yaml: line 6: did not find expected key

Expected result: the configuration is parsed and {wrapper} is replaced with its configured value, as shown in the documentation.

Lefthook version

2.1.10 8d9cfec5f52367af6374a5430b4e9568844856e5

Possible solution

Update the documentation examples to quote run values that begin with a template:

- run: "{wrapper} yarn format"
- run: "{wrapper} yarn lint"
- run: "{wrapper} yarn test"

The earlier {dip} example on the same page should be quoted as well:

- run: "{dip} bundle exec rubocop -- {staged_files}"

Alternatively, Lefthook could preprocess leading template placeholders before YAML parsing, though documenting YAML-valid quoted values is likely simpler and less surprising.