Support `taplo` configuration in `pyproject.toml`

elevator pitch

Enable configuring taplo by looking for the well-known pyproject.toml file and reading [tool.taplo].

references

https://github.com/tamasfe/taplo/pull/549#issuecomment-2074841745

motivation

As a (mostly) python user, I've applied taplo (via the conda-forge redistribution of taplo-cli (disclaimer: maintainer) in a number of workflows, but have mostly relied on the CLI flags to avoid Yet Another Config File.

With the (hopefully) pending python distributions on #549, more python users will have access to an easy-to-manage version of taplo, which they could include in e.g. [project.optional-depenendencies.lint].

Many python-based tools have centralized on pyproject.toml's reserved, but unconstrained, [tool] section for their configuration. Adopting this convention would improve the overall experience for python projects that might only be using taplo for that file, making an additional top-level .taplo.toml a bit "noisier" than it needs to be.

alternatives

augment the CLI to accept a different top-level table, e.g.
```
taplo format --config pyproject.toml --config-table tool.taplo pyproject.toml
```
- this... isn't terrible, and would avoid coupling too tightly to a specific ecosystem's conventions, which can always change

design ideas

the docs might say something like
By default, every tool looks for one in the working directory or the root of the workspace by the following names (in precedence order):
- .taplo.toml
- taplo.toml
- pyproject.toml under the [tool.taplo] table

a minimal viable pyproject.toml is pretty much what one would expect:

[build-system]
build-backend = "flit_core.buildapi"
requires = ["flit_core >=3.7.1,<4"]

[project]
name = "some-neat-project"
readme = "README.md"
classifiers = ["License :: OSI Approved :: MIT License"]
requires-python = ">=3.9"
dynamic = ["version", "description"]

[project.optional-dependencies]
lint = ["taplo", "ruff"]

[tool.ruff]
# ... oh boy it's a lot

[tool.taplo]
include = ["pyproject.toml"]

[[tool.taplo.rule]]
include = ["pyproject.toml"]
keys = ["dependencies", "*-dependencies"]

[tool.taplo.rule.formatting]
reorder_keys = true

getting this into the usual suspects (e.g. schemastore.org) would make it pretty much Just Work for a lot of language server users:

"properties": {
  "tool": {
    "title": "Tool-specific configuration",
    "type": "object",
    "description": "A table for tool configurations.\n\nEvery tool that is used by the project can have its own sub-table for its configuration.\n",
    "additionalProperties": {
      "type": "object"
    },
    "x-taplo": {
      "links": {
        "key": "https://www.python.org/dev/peps/pep-0518/#id28"
      }
    },
    "properties": {
      "taplo": {
        "$ref": "https://json.schemastore.org/taplo.json"
      },

And thanks for taplo :hugs: !

tamasfe / taplo