Add --prune flag to prune unrecognised files in generated dir

CHANGELOG.md

@@ -5,6 +5,17 @@
 ### Added
 
 - Expose a `slug-underscored` variable, matching `scheme-slug-underscored`
+- Add `build --prune` flag which deletes previously generated themes, or
+  unknown files in out directory, of files that aren't recognised. Renaming a
+  scheme previously left the old theme behind in every template repository
+  indefinitely. Pruning is limited to files matching a template config entry's
+  own `filename` pattern, skips scheme systems that generated nothing in the same
+  run, and only runs once every config entry has been generated successfully.
+
+### Changed
+
+- **Breaking (library):** `operation_build::build()` takes a new `prune`
+  argument before `is_quiet`.
 
 ## [0.21.0] - 2026-06-15
 

README.md

@@ -68,14 +68,15 @@ The following is a table of the available subcommands for the CLI tool (tinted-b
 | Subcommand | Description                          | Arguments            | Example Usage                              | Flags |
 |------------|--------------------------------------|----------------------|--------------------------------------------|-------|
 | `sync`  | Installs and or updates latest schemes. | - | `tinted-builder-rust sync` | `--quiet` (silence stderr and stdout) |
-| `build` | Builds the themes of a template. | `template_path`: Path to template directory. | `tinted-builder-rust build ./path/to/base16-template` | `--quiet` (silence stderr and stdout), `--sync` (equivalent of running `tinted-builder-rust sync` before `tinted-builder-rust build`) |
+| `build` | Builds the themes of a template. | `template_path`: Path to template directory. | `tinted-builder-rust build ./path/to/base16-template` | `--quiet` (silence stderr and stdout), `--sync` (equivalent of running `tinted-builder-rust sync` before `tinted-builder-rust build`), `--prune` (remove themes whose scheme no longer exists) |
 
 ## Flags
 
 | Flag/Option       | Description                             | Applicable Subcommands | Default Value | Example Usage                             |
 |-------------------|-----------------------------------------|------------------------|---------------|-------------------------------------------|
 | `--schemes-dir` `-s`   | Path to local schemes directories. Used by `build` to find schemes and by `sync` to clone/pull into those paths. | `build`, `sync` | Defaults to `<data-dir>/schemes` | `tinted-builder-rust build . -s /path/one -s /path/two` |
 | `--ignore` `-i`   | One or more glob patterns to skip when scanning schemes. Repeat this flag to add multiple ignores. | `build` | - | `tinted-builder-rust build . --ignore "**/LICENSE"` |
+| `--prune`   | Delete previously generated themes whose scheme no longer exists, such as the files left behind when a scheme is renamed. Only files matching a template config entry's own `filename` pattern are removed, and only for scheme systems that produced at least one theme in the same run. | `build` | Disabled | `tinted-builder-rust build . --prune` |
 | `--data-dir` `-d`   | Specifies a custom path for the data directory. | All | Linux: `$XDG_DATA_HOME/tinted-theming/tinted-builder-rust` or `~/.local/share`. MacOS: `~/Library/Application\ Support/tinted-theming/tinted-builder-rust` | `tinted-builder-rust sync --data-dir /path/to/custom/data-dir` |
 | `--help` `-h`     | Displays help information for the subcommand. | All | - | `tinted-builder-rust --help`, `tinted-builder-rust build --help`, etc |
 | `--version` `-V`  | Shows the version of tinted-builder-rust. | All | - | `tinted-builder-rust --version` |

tinted-builder-rust/Cargo.toml

@@ -7,10 +7,8 @@ license = "GPL-3.0-only"
 description = "Simple Base16, Base24 and Tinted8 compliant rendering of mustache templates"
 keywords = ["base16", "tinted8", "mustache", "template"]
 categories = ["template-engine"]
-homepage = "https://github.com/tinted-theming/tinted-builder-rust"
 repository = "https://github.com/tinted-theming/tinted-builder-rust"
 documentation = "https://github.com/tinted-theming/tinted-builder-rust"
-readme = "README.md"
 rust-version.workspace = true
 
 [dependencies]

tinted-builder-rust/README.md

@@ -17,6 +17,7 @@ build templates within your own Rust application.
 - [Basic usage](#basic-usage)
 - [Commands](#commands)
 - [Flags](#flags)
+- [Pruning themes](#pruning-themes)
 - [Builder specification](#builder-specification)
 - [Contributing](#contributing)
 - [License](#license)
@@ -54,18 +55,48 @@ The following is a table of the available subcommands for the CLI tool (tinted-b
 | Subcommand | Description | Arguments | Example Usage | Flags |
 |------------|-------------|-----------|---------------|-------|
 | `sync`  | Installs and or updates latest schemes. | - | `tinted-builder-rust sync` | `--quiet` (silence stderr and stdout) |
-| `build` | Builds the themes of a template. | `template_path`: Path to template directory. | `tinted-builder-rust build ./path/to/base16-template` | `--quiet` (silence stderr and stdout), `--sync` (equivalent of running `tinted-builder-rust sync` before `tinted-builder-rust build`) |
+| `build` | Builds the themes of a template. | `template_path`: Path to template directory. | `tinted-builder-rust build ./path/to/base16-template` | `--quiet` (silence stderr and stdout), `--sync` (equivalent of running `tinted-builder-rust sync` before `tinted-builder-rust build`), `--prune` (remove themes whose scheme no longer exists) |
 
 ## Flags
 
 | Flag/Option | Description | Applicable Subcommands | Default Value | Example Usage |
 |-------------|-------------|------------------------|---------------|---------------|
 | `--schemes-dir` `-s` | Path to local schemes directories.  Used by `build` to find schemes and by `sync` to clone/pull into those paths. | `build`, `sync` | Defaults to `<data-dir>/schemes` | `tinted-builder-rust build . -s /path/one -s /path/two` |
 | `--ignore` `-i`   | One or more glob patterns to skip when scanning schemes. Repeat this flag to add multiple ignores. | `build` | - | `tinted-builder-rust build . --ignore "**/LICENSE"` |
+| `--prune` | Delete previously generated themes whose scheme no longer exists, such as the files left behind when a scheme is renamed. See [Pruning themes](#pruning-themes). | `build` | Disabled | `tinted-builder-rust build . --prune` |
 | `--data-dir` `-d` | Specifies a custom path for the data directory. | All | Linux: `$XDG_DATA_HOME/tinted-theming/tinted-builder-rust`. macOS: `~/Library/Application\ Support/tinted-theming/tinted-builder-rust` | `tinted-builder-rust sync --data-dir /path/to/custom/data-dir` |
 | `--help` `-h` | Displays help information for the subcommand. | All | - | `tinted-builder-rust --help`, `tinted-builder-rust build --help`, etc |
 | `--version` `-V` | Shows the version of tinted-builder-rust. | All | - | `tinted-builder-rust --version` |
 
+## Pruning theme files
+
+A build only ever writes files, so a theme generated for a scheme that has
+since been renamed or deleted stays in the template repository forever.
+Passing `--prune` removes those leftovers once the build has finished:
+
+```sh
+tinted-builder-rust build . --prune
+```
+
+Pruning is deliberately conservative. A file is only removed when all of the
+following hold:
+
+- It sits directly in the output directory of a `templates/config.yaml` entry,
+  and its name matches that entry's `filename` pattern with the scheme slug
+  substituted. For `colors/{{ scheme-system }}-{{ scheme-slug }}.conf`, that
+  means only `colors/base16-*.conf` is ever considered.
+- It was not written by the current build.
+- Its scheme system produced at least one theme in the current build, so a
+  partially synced or heavily ignored schemes directory cannot wipe out an
+  entire system's themes.
+- It is not a dotfile and not a directory.
+
+Entries whose `filename` has no scheme slug in its last path component, such
+as `list` templates, are skipped and reported as `W002`.
+
+Note that schemes excluded with `--ignore` count as non-existent, so their
+previously generated themes are pruned too.
+
 ## List usage
 
 `tinted-builder-rust` supports an `options.list` config property which enables

tinted-builder-rust/src/cli.rs

@@ -52,6 +52,12 @@ fn build_cli() -> Command {
                         .long("sync")
                         .help("Sync with latest schemes before build")
                         .action(ArgAction::SetTrue),
+                )
+                .arg(
+                    Arg::new("prune")
+                        .long("prune")
+                        .help("Delete previously generated themes whose scheme no longer exists")
+                        .action(ArgAction::SetTrue),
                 ),
         )
         .subcommand(

tinted-builder-rust/src/main.rs

@@ -65,6 +65,9 @@ fn main() -> Result<()> {
             let is_quiet = sub_matches
                 .get_one::<bool>("quiet")
                 .is_some_and(ToOwned::to_owned);
+            let prune = sub_matches
+                .get_one::<bool>("prune")
+                .is_some_and(ToOwned::to_owned);
             let template_dir = sub_matches
                 .get_one::<String>("template-dir")
                 .cloned()
@@ -76,7 +79,7 @@ fn main() -> Result<()> {
                 operations::sync::sync(&data_schemes_path, is_quiet)?;
             }
 
-            operations::build::build(&template_path, &schemes_path, &ignores, is_quiet)?;
+            operations::build::build(&template_path, &schemes_path, &ignores, prune, is_quiet)?;
         }
         Some(("sync", sub_matches)) => {
             let is_quiet: bool = sub_matches