Improve lockfile documentation structure (#874)

Author: tobiasraabe

CHANGELOG.md

@@ -7,6 +7,9 @@ releases are available on [PyPI](https://pypi.org/project/pytask) and
 
 ## Unreleased
 
+- [#874](https://github.com/pytask-dev/pytask/pull/874) improves the lockfile
+  documentation by restructuring related guides around user workflows and introducing
+  `pytask.lock` in the tutorials.
 - [#868](https://github.com/pytask-dev/pytask/pull/868) resets the global marker
   configuration during unconfigure so `--strict-markers` no longer leaks into later
   marker access in the same process.

docs/AGENTS.md

@@ -2,6 +2,11 @@
 
 ## General
 
+- The structure of the documentation follows https://diataxis.fr/. When writing or
+    editing an article, read the relevant guidance from the Diataxis Framework before:
+    https://diataxis.fr/tutorials, https://diataxis.fr/how-to-guides/,
+    https://diataxis.fr/explanation/, https://diataxis.fr/reference/.
+    https://diataxis.fr/compass/ tells you where belongs what and how do they relate.
 - Document only public APIs and user-facing behavior - exclude internals, framework
     abstractions, and implementation plumbing - Users need actionable documentation on
     what they can use, not confusing details about internal mechanics they can't control

docs/CLAUDE.md

@@ -9,8 +9,8 @@ specific tasks with pytask.
 
 - [Migrating From Scripts To Pytask](migrating_from_scripts_to_pytask.md)
 - [Interfaces For Dependencies Products](interfaces_for_dependencies_products.md)
-- [Portability](portability.md)
-- [Update the Lockfile to Match Project State](reconciling_lockfile_state.md)
+- [Move a Project to Another Machine](move_project_to_another_machine.md)
+- [Update the Lockfile to Match Project State](update_the_lockfile_to_match_project_state.md)
 - [Remote Files](remote_files.md)
 - [Functional Interface](functional_interface.md)
 - [Capture Warnings](capture_warnings.md)

docs/source/how_to_guides/index.md

@@ -0,0 +1,77 @@
+# Move a Project to Another Machine
+
+This guide teaches you how to move a pytask project to another machine or environment
+and reuse existing outputs where possible.
+
+## Update the lockfile on the source machine
+
+Run a normal build with [`pytask build`](../reference_guides/commands.md#pytask-build)
+before moving the project with its `pytask.lock` and files and outputs are up-to-date:
+
+```console
+$ pytask build
+```
+
+## Move the project files and reusable outputs
+
+If you have not done it yet, commit `pytask.lock` to your repository and move it with
+the project. In practice, move:
+
+- the project files tracked in version control, including source files, configuration,
+    data inputs, and `pytask.lock`
+- the build artifacts you want to reuse, often in `bld/` if you follow the tutorial
+    layout
+- the `.pytask` folder if you use the data catalog and it manages some of your files
+
+## Keep external files in the same relative layout
+
+If tasks use files outside the project root, keep the same relative layout on the target
+machine. The project root is the folder with the `pyproject.toml` file.
+
+For example, if a task reads `../shared/input.csv` from the source machine, the moved
+project also needs a readable `../shared/input.csv` next to the project root on the
+target machine.
+
+## Run pytask on the target machine
+
+After you moved the project to the target machine, run pytask to build the project:
+
+```console
+$ pytask build
+```
+
+Assuming that the project was fully built before the move, pytask will not rebuild the
+project and skip all tasks.
+
+## Clean stale lockfile entries
+
+If you removed, renamed, or moved tasks before transferring the project, clean up stale
+lockfile entries on the source machine before you move the project:
+
+```console
+$ pytask build --clean-lockfile
+```
+
+This rewrites the lockfile after a successful build with only the currently collected
+tasks and their current state values.
+
+## If your project uses custom nodes
+
+Make sure custom node IDs and state values stay stable across machines:
+
+- Use project-relative IDs instead of absolute paths.
+- Prefer file content hashes over timestamps.
+- Avoid machine-specific paths or timestamps in custom
+    [`state()`](../api/nodes_and_tasks.md#pytask.PNode.state) implementations.
+- Provide a custom hash function for
+    [`PythonNode`](../api/nodes_and_tasks.md#pytask.PythonNode) values that are not
+    natively stable.
+
+Most projects that only use built-in nodes do not need extra work here.
+
+!!! seealso
+
+    The lockfile format and behavior are documented in the
+    [reference guide](../reference_guides/lockfile.md). For custom nodes, see
+    [Writing custom nodes](writing_custom_nodes.md). For hashing guidance, see
+    [Hashing inputs of tasks](hashing_inputs_of_tasks.md).

docs/source/how_to_guides/move_project_to_another_machine.md

@@ -36,6 +36,8 @@ my_project
 │       ├────task_data_preparation.py
 │       └────task_plot_data.py
 │
+├───pytask.lock
+│
 └───pyproject.toml
 ```
 
@@ -107,6 +109,10 @@ Now, let us execute the two paths.
 
 --8<-- "docs/source/_static/md/defining-dependencies-products.md"
 
+The build updates `pytask.lock` with the state of both tasks. When you run the same
+tasks again without changing their dependencies, products, or source files, pytask uses
+the lockfile to skip them.
+
 ## Relative paths
 
 Dependencies and products do not have to be absolute paths. If paths are relative, they

docs/source/how_to_guides/portability.md

@@ -19,7 +19,7 @@ The following directory tree gives an overview of the project's different parts.
 ```text
 my_project
 │
-├───.pytask
+├───.pytask  # Generated by pytask.
 │
 ├───bld
 │   └────...
@@ -30,13 +30,16 @@ my_project
 │       ├────config.py
 │       └────...
 │
+├───pytask.lock  # Generated by pytask.
+│
 └───pyproject.toml
 ```
 
-Replicate this directory structure for your project or start from pytask's
+Create the project files and folders for your project or start from pytask's
 [cookiecutter-pytask-project](https://github.com/pytask-dev/cookiecutter-pytask-project)
 template or any other
 [linked template or example project](../how_to_guides/bp_templates_and_projects.md).
+pytask creates the `.pytask` folder and `pytask.lock` file later when you run tasks.
 
 ## The `src` directory
 
@@ -129,10 +132,24 @@ The `[tool.pytask.ini_options]` section tells pytask to look for tasks in
 `src/my_project`. You will learn more about configuration in the
 [configuration tutorial](configuration.md).
 
+## The `pytask.lock` file
+
+The `pytask.lock` file records which tasks and products are up to date. pytask updates
+it during builds so later runs can skip unchanged tasks. This file should be kept in
+version control.
+
+!!! seealso
+
+    You will later learn how to sync the state of the lockfile with the project state with
+    the [`pytask lock`](../reference_guides/commands.md#pytask-lock) command or how the
+    lockfile enables you to
+    [move a project to another machine](../how_to_guides/move_project_to_another_machine.md),
+    but don't worry about it for now.
+
 ## The `.pytask` directory
 
-The `.pytask` directory is where pytask stores its information. You do not need to
-interact with it.
+The `.pytask` directory is where pytask stores some of its ephemeral information. You do
+not need to interact with it, nor do you need to keep it in version control.
 
 ## Installation
 

…_to_guides/reconciling_lockfile_state.md …e_the_lockfile_to_match_project_state.mddocs/source/how_to_guides/reconciling_lockfile_state.md renamed to docs/source/how_to_guides/update_the_lockfile_to_match_project_state.md docs/source/how_to_guides/reconciling_lockfile_state.md renamed to docs/source/how_to_guides/update_the_lockfile_to_match_project_state.md

@@ -36,6 +36,8 @@ my_project
 │       ├────task_data_preparation.py
 │       └────task_plot_data.py
 │
+├───pytask.lock
+│
 └───pyproject.toml
 ```
 
@@ -148,6 +150,8 @@ my_project
 │
 ├───pyproject.toml
 │
+├───pytask.lock
+│
 ├───src
 │   └───my_project
 │       ├────config.py