# Contributing to fastfetch

<details>
    <summary>
    Note
    </summary>

    This document is generated by AI, and mainly for AI use. It is not a substitute for human review, and may contain errors or omissions. Please verify any information before relying on it.
</details>

Thanks for your interest in fastfetch. This document covers building, architecture, how to add a module or a logo, code style, commit conventions, and the pull request workflow.

fastfetch is a system information tool written in C23, supporting Linux, macOS, Windows, the BSDs, Solaris, Haiku and Android. The project is borderline obsessive about **startup time** and **optional dependencies** — many design decisions only make sense under that constraint, and this document keeps coming back to it.

---

## Table of contents

- [Contributor quick reference](#contributor-quick-reference)
- [Getting started](#getting-started)
- [Code map](#code-map)
- [Core architecture: modules vs. detection](#core-architecture-modules-vs-detection)
- [Module registration](#module-registration)
- [Walkthrough: adding a module](#walkthrough-adding-a-module)
- [Walkthrough: adding a logo](#walkthrough-adding-a-logo)
- [Platform conventions](#platform-conventions)
- [Code style](#code-style)
- [Commit messages](#commit-messages)
- [Changelog](#changelog)
- [Tests](#tests)
- [Pull requests](#pull-requests)
- [Gotchas](#gotchas)

---

## Contributor quick reference

| Task | Start here | Verify with |
|---|---|---|
| Build and run fastfetch | `run.sh`, `CMakeLists.txt` | `./run.sh` |
| Add a module | `src/modules/<name>/`, `src/detection/<name>/`, `src/modules/modules.c` | `cmake -B build && cmake --build build -j` |
| Add a platform implementation | `src/detection/<name>/<name>_<platform>.c` | Build on the target platform or CI |
| Add an ASCII logo | `src/logo/ascii/<letter>/<name>.txt`, matching `<letter>.inc` | `./build/fastfetch --logo <name>` |
| Change formatting or JSON output | `src/modules/<name>/<name>.c` | `./build/fastfetch -s <name> --format json` |
| Change shared formatting or containers | `src/common/format.h`, `src/common/color.h`, `src/common/FFstrbuf.h` | Build and run the matching test |
| Run the test suite | `tests/`, `build/` | `cd build && ctest --output-on-failure` |

For a normal code change, the shortest useful loop is: configure, build the `fastfetch` target, run the affected module, then run the tests. If you add a directory or a generated input, re-run `cmake -B build` so CMake refreshes its file globs.

---

## Getting started

### Building

The quickest way is `run.sh` in the repository root — it creates `build/`, configures, compiles and runs the binary:

```sh
./run.sh                 # build and run
./run.sh --format json   # arguments are forwarded to fastfetch
```

Manual build:

```sh
cmake -B build -DCMAKE_BUILD_TYPE=RelWithDebInfo
cmake --build build --target fastfetch -j$(nproc)
./build/fastfetch
```

The default build type is `RelWithDebInfo`. LTO is enabled whenever `ENABLE_LTO=ON` **and** `CMAKE_BUILD_TYPE != Debug` — so the default already has it, and only `Debug` builds lack it. This matters because LTO here is not merely an optimization: it is what strips the code of disabled modules. See [Gotchas](#gotchas).

### Common build options

| Option | Default | Notes |
|---|---|---|
| `CMAKE_BUILD_TYPE` | `RelWithDebInfo` | LTO is on for anything but `Debug` |
| `BUILD_TESTS` | `OFF` | Builds the unit tests in `tests/` |
| `BUILD_FLASHFETCH` | `ON` | Also builds the stripped-down `flashfetch` |
| `BINARY_LINK_TYPE` | `dlopen` | `dlopen` / `dynamic` / `static` |
| `ENABLE_ASAN` | `OFF` | Address Sanitizer |
| `ENABLE_LTO` | `ON` | Link-time optimization |
| `MODULE_DISABLE_<NAME>` | `OFF` | Disable a module, e.g. `MODULE_DISABLE_GPU=ON` |
| `SET_TWEAK` | `ON` | Appends a tweak to the dev version; turned off for releases |

`BINARY_LINK_TYPE=dlopen` (the default) is a deliberate design choice: optional dependencies (Vulkan, Wayland, DBus, ImageMagick, chafa, …) are loaded at runtime, so a missing library never prevents startup. When adding a third-party dependency, use the dlopen helpers in `common/library.h` — do not link it directly.

For a minimal-dependency build, see `.github/workflows/build-no-features-test.yml`:

```sh
cmake -DBUILD_TESTS=On -DENABLE_VULKAN=OFF -DENABLE_WAYLAND=OFF -DENABLE_X11=OFF \
      -DENABLE_DBUS=OFF -DENABLE_ZLIB=OFF ... .
```

### Dependencies

Required: CMake ≥ 3.21 and a C23 compiler (GCC, Clang or MSVC). Everything else is optional.

Optional dependencies are auto-detected: libpci, libdrm, vulkan, wayland, xcb, xrandr, dbus, sqlite3, rpm, imagemagick{6,7}, chafa, zlib, egl, glx, opencl, freetype, pulse, ddcutil, elf, libzfs, and more.

---

## Code map

```
src/
├── fastfetch.c          entry point: CLI parsing, module dispatch, main loop (36 KB)
├── flashfetch.c         entry point for the stripped-down build
├── options/             global (non-module) config: general / display / logo
├── modules/             module layer — module formatting and output
├── detection/           detection layer — platform-specific data retrieval
├── common/              infrastructure: FFstrbuf, FFlist, formatting, printing, networking
├── logo/                530 ASCII logos plus the image logo backends
└── 3rdparty/            yyjson, widecharwidth, display-library
```

Flow of control:

```
fastfetch.c  →  options/    (global configuration)
             →  modules/    (76 modules, formatting and output)
             →  detection/  (one platform implementation each, raw data)
             →  common/     (infrastructure)
```

The number of module directories and detection directories does not match, and that is expected. The following relationships are structural rather than a fixed inventory:

- **13 modules have no detection directory** — they are either pure layout (`break`, `separator`, `colors`, `title`, `logo`) or reuse someone else's detection result (`display`, `monitor`, `kernel`, `shell`, `terminal`, `player`, `custom`, `datetime`).
- **4 detection directories serve modules with different names** — `displayserver` (→ `display`, `monitor`), `gtk_qt` (→ `theme`, `icons`, `font`, `cursor`), `terminalshell` (→ `terminal`, `shell`) and `libc`.

So do not assume `modules/<x>/` always has a matching `detection/<x>/`.

### Layer boundaries

| Layer | Owns | Must not |
|---|---|---|
| `options/` | **Global** config (colors, logo, threading, timeouts) | hold per-module options |
| `modules/` | formatting, printing, JSON serialization | read `/proc`, call Win32 APIs, parse sysfs |
| `detection/` | cross-platform data retrieval, clean result structs | print anything, read display config |
| `common/` | general-purpose utilities, no business logic | depend on a specific module |

The test is simple: **no file under `detection/` should contain `printf` or read `instance.config`.** Symmetrically, no file under `modules/` should contain `#ifdef __linux__`.

---

## Core architecture: modules vs. detection

This is the single most important convention in the codebase. Every feature is a fixed set of files — using CPU as the example:

```
modules/cpu/option.h           module option struct
modules/cpu/cpu.c              formatting and output
detection/cpu/cpu.h            platform-independent interface
detection/cpu/cpu_linux.c     ┐
detection/cpu/cpu_apple.c     │
detection/cpu/cpu_windows.c   ├─ platform implementations, one linked per build
detection/cpu/cpu_bsd.c       │
detection/cpu/cpu_nosupport.c ┘
```

The interface is deliberately minimal — usually just two things:

```c
typedef struct FFCPUResult { ... } FFCPUResult;   // result struct
const char* ffDetectCPU(const FFCPUOptions* options, FFCPUResult* cpu);
```

The `const char*` return value is an **error string**; `nullptr` means success. This pattern is used throughout `detection/` — please keep it consistent.

Helper functions are only exposed when they are genuinely shared between platform implementations (as in `cpu.h`: `ffCPUAppleCodeToName`, `ffCPUDetectByCpuid`).

**The payoff:** adding a platform never touches `modules/`; fixing output formatting never touches `detection/`.

---

## Module registration

### The descriptor

Every module exports one `FFModuleBaseInfo` (defined in `common/option.h:46`) — essentially a hand-written vtable:

```c
typedef struct FFModuleBaseInfo {
    const char* name;                    // lookup key, e.g. "cpu"
    const char* description;             // help text
    FFModuleDisplayName displayName;     // module name in 20 languages

    void (*initOptions)(void* options);
    void (*destroyOptions)(void* options);
    void (*parseJsonObject)(void* options, struct yyjson_val* module);
    bool (*printModule)(void* options);
    bool (*generateJsonResult)(void* options, yyjson_mut_doc*, yyjson_mut_val*);
    void (*generateJsonConfig)(void* options, yyjson_mut_doc*, yyjson_mut_val*);

    FFModuleFormatArgList formatArgs;    // format placeholder table
    const uint8_t defaultOrder;          // sort weight
} FFModuleBaseInfo;
```

The source comment openly admits this is UB — `void*` is not compatible with `FF*Options*`. It is a pragmatic compromise to get polymorphism in C. Don't try to "fix" it.

### The registry: a first-letter hash bucket

`src/modules/modules.c` defines 26 `static FFModuleBaseInfo*` arrays (`A[]` through `Z[]`), each terminated by `nullptr`, collected into `ffModuleInfos[26]`:

```c
FFModuleBaseInfo** modules = ffModuleInfos[toupper(name[0]) - 'A'];  // O(1) bucket lookup
for (; *modules; ++modules) {                                        // linear scan in the bucket
    if (ffStrEqualsIgnCase(name, (*modules)->name)) { ... }
}
```

The registry is small enough that a subtraction plus a few string comparisons is preferable to a general-purpose hash table. When adding a module, place its descriptor in the bucket matching the first letter of `.name`; keep the existing `nullptr` terminator at the end.

### The calling convention: zero heap allocation

Every dispatch site (`jsonconfig.c:98`, `commandoption.c:189`) follows the same pattern:

```c
alignas(uint64_t) uint8_t optionBuf[FF_OPTION_MAX_SIZE];  // 256 bytes, on the stack
baseInfo->initOptions(optionBuf);
baseInfo->parseJsonObject(optionBuf, jsonVal);             // JSONC path only
baseInfo->printModule(optionBuf);                          // or generateJsonResult
baseInfo->destroyOptions(optionBuf);
```

`FF_OPTION_MAX_SIZE = 1 << 8` (256 bytes). Every module's `option.h` must end with:

```c
static_assert(sizeof(FFCPUOptions) <= FF_OPTION_MAX_SIZE, "FFCPUOptions size exceeds maximum allowed size");
```

**Meaning: no module option struct may exceed 256 bytes.** Hard constraint, enforced at compile time.

The three dispatch entry points:

| Entry point | Location | Used for |
|---|---|---|
| `parseModuleJsonObject` | `common/impl/jsonconfig.c:90` | the `modules[]` array in a JSONC config |
| `parseStructureCommand` | `common/impl/commandoption.c:181` | the colon-separated structure string |
| `ffParseModuleOptions` | `common/impl/commandoption.c:13` | **deprecated** — see [Gotchas](#4-cli-module-options-are-removed) |

### Build-time module discovery

`CMakeLists.txt:131` globs `src/modules/*/` and generates a `MODULE_DISABLE_<UPPER>` option per directory:

```cmake
file(GLOB FF_MODULE_DIRS RELATIVE "..." ".../src/modules/*/")
foreach(FF_MODULE_DIR ${FF_MODULE_DIRS})
    option(MODULE_DISABLE_${FF_MODULE_UPPER} "Disable module ${FF_MODULE_DIR}" OFF)
endforeach()
```

**Adding a module requires no CMake change.** The same trick generates the package manager switches (`:146` regex-scans `src/modules/packages/option.h` for `FF_PACKAGES_FLAG_*_BIT`).

---

## Walkthrough: adding a module

Adding a `Foo` module, step by step.

### 1. Define the option struct

`src/modules/foo/option.h`:

```c
#pragma once

#include "common/option.h"

typedef struct FFFooOptions {
    FFModuleArgs moduleArgs;   // must be the first field
    bool showBar;
} FFFooOptions;

static_assert(sizeof(FFFooOptions) <= FF_OPTION_MAX_SIZE, "FFFooOptions size exceeds maximum allowed size");
```

`FFModuleArgs` must come first. It provides `key`, `format`, `outputColor`, `keyColor`, `keyIcon` and `keyWidth`; because it is the first field, `ffJsonConfigParseModuleArgs()` can handle these generically and you get them **for free — no parsing code to write**.

Note these fields can only be set through the JSON config; CLI module options have been removed (see [Gotchas](#4-cli-module-options-are-removed)).

### 2. Implement detection

`src/detection/foo/foo.h`:

```c
#pragma once
#include "fastfetch.h"

typedef struct FFFooResult {
    FFstrbuf name;
    uint32_t count;
} FFFooResult;

const char* ffDetectFoo(const FFFooOptions* options, FFFooResult* result);
```

`src/detection/foo/foo_linux.c`:

```c
#include "foo.h"

const char* ffDetectFoo(const FFFooOptions* options, FFFooResult* result) {
    // read /sys, /proc, sysfs, dbus, ...
    return nullptr;  // success; return an error string on failure
}
```

**Write one file per target platform, and a `foo_nosupport.c` fallback for the rest.** There are already 45 `*_nosupport.c` files doing exactly this.

### 3. Implement the module

`src/modules/foo/foo.c` — implement the six functions, then define the descriptor:

```c
FFModuleBaseInfo ffFooModuleInfo = {
    .name = "Foo",
    .description = "Print foo information",
    .displayName = {
        .en = "Foo", .ar = "Foo", .cs = "Foo", .de = "Foo", .es = "Foo",
        .fr = "Foo", .gl = "Foo", .he = "Foo", .id = "Foo", .it = "Foo",
        .ja = "Foo", .ko = "Foo", .pl = "Foo", .pt = "Foo", .ru = "Foo",
        .tr = "Foo", .uk = "Foo", .vi = "Foo", .zh_CN = "Foo", .zh_TW = "Foo",
    },
    .initOptions = (void*) ffInitFooOptions,
    .destroyOptions = (void*) ffDestroyFooOptions,
    .parseJsonObject = (void*) ffParseFooJsonObject,
    .printModule = (void*) ffPrintFoo,
    .generateJsonResult = (void*) ffGenerateFooJsonResult,
    .generateJsonConfig = (void*) ffGenerateFooJsonConfig,
    .formatArgs = FF_FORMAT_ARG_LIST(((FFModuleFormatArg[]) {
        { "Name", "name" },
        { "Count", "count" },
    })),
    .defaultOrder = 73,
};
```

Points to note:

- **`displayName`** is a literal block of all 20 language fields — there is no shortcut macro, so copy the layout from a neighboring module: **`en`, `ar`, `cs`, `de`, `es`, `fr`, `gl`, `he`, `id`, `it`, `ja`, `ko`, `pl`, `pt`, `ru`, `tr`, `uk`, `vi`, `zh_CN`, `zh_TW`**.
  **Fill in all 20.** The struct is read by byte offset (see [Gotchas](#6-localization-uses-byte-offsets-not-enums)) and there is **no fallback** — a missing field means the key prints empty in that language.
- **`formatArgs`** must be exhaustive. It drives the placeholder list printed by `fastfetch -h foo-format`; **anything you omit is invisible and unusable to the user.**
- The `moduleFormat` section in `doc/json_schema.json` is generated by `fastfetch -h format-json`. Its metadata comes from `FFModuleBaseInfo::formatArgs`. To keep the schema and module descriptors consistent, do not edit the `moduleFormat` section in `doc/json_schema.json` by hand; update the module metadata and regenerate it instead.
- **`defaultOrder`**: use the current maximum plus 1. Search the existing descriptors for `.defaultOrder =` before choosing a value; do not copy a hard-coded value from this document. Leaving it out, or setting it to `0`, makes the module **disappear** from the interactive `--gen-config` picker. Only `logo`, `command` and `custom` do this deliberately, because they need user arguments or are invoked directly by the display layer.

### 4. Register it

- Add `#include "modules/foo/foo.h"` to `src/modules/modules.h`
- Insert into the `F[]` array in `src/modules/modules.c`:

```c
#if !FF_MODULE_DISABLE_FOO
    &ffFooModuleInfo,
#endif
```

`FF_MODULE_DISABLE_FOO` is generated by CMake — you do not define it yourself.

### 5. Modules that need warm-up

If your module needs a sampling interval (CPU usage) or a network round-trip (public IP, weather), also implement `ffPrepareFoo()` and register it in the switch inside `ffPrepareCommandOption()` in `common/impl/commandoption.c`, under the right first-letter `case`. Six modules do this today: CPUUsage, DiskIO, NetIO, PublicIP, Top and Weather.

### 6. Verify

```sh
cmake -B build && cmake --build build -j
./build/fastfetch -s foo --format json    # JSON output
./build/fastfetch -h foo-format           # list formatArgs placeholders
./build/fastfetch --gen-config            # confirm it appears in the picker
```

Note the `-format` suffix on the help flag: `fastfetch -h foo` does not work, only `fastfetch -h foo-format`.

---

## Walkthrough: adding a logo

A new logo **must** have a corresponding "Logo Request" issue, linked from the PR with `Closes #1234`. Logo PRs without a linked issue are not accepted.

### 1. Drop in the ASCII file

```
src/logo/ascii/<first-letter>/<distro>.txt
```

For example `src/logo/ascii/o/omarchy.txt`. Directories are already split by first letter (`a/` … `z/`, plus `_/`).

The file is plain ASCII art with `$1` … `$9` as color placeholders:

```
                 $3 ,-^-___
$3                /\\\///
$2refined.$1       /\\\\//
```

- `$1` … `$9` map to palette slots 1–9; at most 9 (`FASTFETCH_LOGO_MAX_COLORS = 9`)
- `$$` is a literal `$`
- Characters without a placeholder inherit the current color. Of the 530 existing logos, 239 use no placeholders at all (monochrome) and 291 do — **new logos should use placeholders**; monochrome is a legacy style
- Tabs are expanded to 4 spaces
- Colors can be overridden with `--logo-color-1` … `--logo-color-9`

### 2. Register it in the `.inc`

CMake turns each `.txt` into a `FASTFETCH_DATATEXT_LOGO_<UPPERCASE>` macro (`CMakeLists.txt:418`), but **the registry itself is maintained by hand**. Edit `src/logo/ascii/<first-letter>.inc`:

```c
#ifdef FASTFETCH_DATATEXT_LOGO_OMARCHY
// Omarchy
{
    .names = { "omarchy", "Omarchy" },
    .lines = FASTFETCH_DATATEXT_LOGO_OMARCHY,
    .colors = {
        FF_COLOR_FG_BLUE,
        FF_COLOR_FG_WHITE,
        FF_COLOR_FG_CYAN,
    },
},
#endif
```

- `names` is matched case-insensitively. Do not add names that differ only by case, because they can never be distinguished. Every name is also shown by `--list-logos`, so use user-friendly spelling such as an initial capital where appropriate.
- For a new logo, use exactly one name unless there is a specific compatibility reason to add more. That name should first be the `ID` from `/etc/os-release`. If the ID cannot distinguish this logo from another logo for the same OS, use the `NAME` value instead. `logoGetBuiltinDetected` in `src/logo/logo.c` documents the detection order: `ID`, then `NAME`, then tokens from `ID_LIKE`, then the platform name fallback. Manual `logo-source` selection uses the name directly.
- `colors` is positional — entry 0 is `$1`, entry 1 is `$2`, and so on
- `colors[0]` also becomes the title color and `colors[1]` the key color, unless the user overrides them

If the same OS has multiple logo variants, mark the variant explicitly with `.type`:

```c
.type = FF_LOGO_LINE_TYPE_SMALL_BIT,
```

Use `FF_LOGO_LINE_TYPE_ALTER_BIT` for an alternate logo, `FF_LOGO_LINE_TYPE_SMALL_BIT` for a small logo, or combine the flags when both apply. This is also a lookup optimization: a logo marked `FF_LOGO_LINE_TYPE_SMALL_BIT` is considered only for `type = small`, while a logo marked `FF_LOGO_LINE_TYPE_ALTER_BIT` is never selected by automatic detection. Alternate logos are available only when explicitly requested through `--logo <source>`.

### 3. Verify

```sh
./build/fastfetch --logo omarchy
./build/fastfetch --list-logos | grep -i omarchy
```

---

## Platform conventions

The `detection/` layer picks its implementation by **filename suffix**; the choice is made at build time from `CMAKE_SYSTEM_NAME`:

| Suffix | Platform |
|---|---|
| `_linux.c` | Linux |
| `_apple.c` / `_apple.m` | macOS / iOS (`.m` for Objective-C) |
| `_windows.c` / `_windows.cpp` | Windows (`.cpp` for WinRT / WMI) |
| `_bsd.c` | FreeBSD |
| `_nbsd.c` | NetBSD |
| `_obsd.c` | OpenBSD |
| `_sunos.c` | Solaris / illumos |
| `_haiku.c` / `.cpp` | Haiku |
| `_android.c` | Android (Termux) |
| `_gnu.c` | GNU/Hurd |
| `_nosupport.c` | Empty fallback |

Current distribution of platform files in `detection/`:

| Suffix | Files | Suffix | Files |
|---|---|---|---|
| `_linux` | 58 | `_obsd` | 16 |
| `_windows` | 47 | `_haiku` | 13 |
| `_apple` | 46 | `_android` | 12 |
| `_nosupport` | 45 | `_gnu` | 3 |
| `_bsd` | 29 | | |
| `_sunos` | 19 | | |
| `_nbsd` | 17 | | |

(These are repository inventory figures, counting `.c`, `.m`, `.cpp`, and `.h`; they may change as platforms and modules are added.)

**Don't pile `#ifdef __linux__` into one file.** When adding platform support, copy the closest existing implementation and change the suffix.

`common/` uses the same idea: `common/impl/` contains `io_unix.c` / `io_windows.c`, `netif_linux.c` / `netif_apple.c` / `netif_bsd.c` and so on, with `common/apple/`, `common/windows/` and `common/haiku/` holding platform-specific helpers.

When several platform suffixes could apply, use the most specific implementation supported by the build system (for example, `_nbsd.c` instead of the generic `_bsd.c` on NetBSD). Keep the generic file as the fallback for platforms that share its conventions.

---

## Code style

### Formatting

The project uses clang-format with `BasedOnStyle: LLVM` plus these key overrides:

```yaml
IndentWidth: 4
UseTab: Never
ColumnLimit: 0              # never wrap
InsertBraces: true          # braces even on single-statement ifs
PointerAlignment: Left      # char* p, not char *p
SortIncludes: Never         # include order is managed by hand
AlignAfterOpenBracket: DontAlign
BinPackParameters: false    # all params on one line, or one per line
```

Before committing:

```sh
clang-format -i src/modules/foo/*.c src/modules/foo/*.h
```

`src/3rdparty/**`, `build/**` and `src/logo/builtin.c` are listed in `.clang-format-ignore` — **do not reformat them.**

`.editorconfig` adds LF line endings, 4-space indent, a final newline, and trailing whitespace trimmed (except in Markdown).

### Naming

| Kind | Convention | Example |
|---|---|---|
| Functions | `ff` + PascalCase | `ffDetectCPU`, `ffPrintCPU` |
| Types | `FF` + PascalCase | `FFCPUResult`, `FFModuleBaseInfo` |
| Variables / fields | camelCase | `coresPhysical`, `keyWidth` |
| Macros | SCREAMING_SNAKE_CASE | `FF_OPTION_MAX_SIZE` |
| Module options | `FF<Name>Options` | `FFCPUOptions` |
| Detection results | `FF<Name>Result` | `FFCPUResult` |

### Spelling

CI runs codespell (`.codespellrc`). Known false positives live in `ignore-words-list` (`iterm`, `compiletime`, and various non-English distro words). Add new words there rather than changing the code.

### Compiler warnings

The build enables `-Wall -Wextra -Wconversion` plus several `-Werror`s:

```
-Werror=uninitialized -Werror=return-type -Werror=vla
-Werror=incompatible-pointer-types -Werror=implicit-function-declaration -Werror=int-conversion
```

**`-Wconversion` is strict**: every implicit narrowing conversion needs an explicit cast.

---

## Commit messages

Format:

```
<Scope>[ (Platform)]: <third-person singular verb> <object>
```

Scope is the module or subsystem name; Platform is optional. Use the third-person singular present tense, capitalize the first letter, no trailing period.

Real examples from recent history:

```
Processes (Haiku): honors `options->countKprocs`
WM (macOS): improves reliability of WM plugin detection
Memory (Windows): prefers `NQSI`
Top (Linux): improves performance of `stat` parsing
Logo (Builtin): adds omarchy
Global: introduces global macro `FF_PATH_PKG_BASE` to replace `_PATH_LOCALBASE`
LM (OpenBSD): adds support
CI: disables fail on alert
Doc: updates README
Presets: moves `top` to the bottom of running modules [ci skip]
```

Common verbs: `adds`, `removes`, `fixes`, `improves`, `updates`, `corrects`, `prefers`, `honors`, `disables`, `enables`, `introduces`, `detects`, `reports`, `skips`, `uses`.

Scopes in use: `Top`, `Processes`, `Memory`, `Logo (Builtin)`, `CI`, `Doc`, `Presets`, `Global`, plus individual module names.

Documentation-only changes get a `[ci skip]` suffix.

---

## Changelog

User-visible changes go into `CHANGELOG.md`, under the topmost version heading:

```markdown
# Unreleased

Changes:
* The DE / WM / LM modules now reports the full name ...

Features:
* Added Top module to print processes with the highest CPU, memory or disk I/O usage. (Top)
* Improved Wi-Fi module
    * Added Wifi channel width detection, exposed via `{channel-width}` in custom format.
    * Improved Wifi channel frequency accuracy on Windows, macOS.
* Added Battery detection support on SunOS. (Battery, SunOS)

Bugfixes:
* Fixed I/O rate calculation precision in DiskIO and NetIO. (DiskIO / NetIO)
```

Rules:

- Three sections: `Changes:` (behavior changes), `Features:`, `Bugfixes:`
- Past tense: `Added` / `Fixed` / `Improved`
- End each entry with its scope: `(Module, Platform)` or `(ModuleA / ModuleB)`
- Sub-bullets are indented 4 spaces

---

## Tests

Tests are standalone executables in `tests/` using a `VERIFY` macro that exits non-zero on failure:

```c
#define VERIFY(expression) \
    if (!(expression)) testFailed(&strbuf, #expression, __LINE__)
```

Current tests: `strbuf.c`, `list.c`, `format.c`, `color.c`, `duration.c`, `strutil.c`.

```sh
cmake -B build -DBUILD_TESTS=On
cmake --build build
cd build && ctest --output-on-failure
```

Coverage focuses on the core data structures and the formatting engine in `common/`. The `detection/` layer has no automated tests (it depends too heavily on a real system) and is instead covered by the CI matrix — 20 workflows under `.github/workflows/` spanning Linux (including musl, loong64, armv7l, i686), macOS, Windows, FreeBSD, NetBSD, OpenBSD, DragonFly, Solaris, OmniOS and Haiku, plus spellcheck and benchmark jobs.

**If you touch `common/FFstrbuf.h`, `common/format.h` or `common/color.h`, please extend the matching test.**

---

## Pull requests

1. **Open an issue first** (feature request / bug report / logo request) so you don't waste effort. Templates are in `.github/ISSUE_TEMPLATE/`.
2. Branch off `dev` — **`dev` is the main development branch**, not `master`.
3. Follow the [commit message convention](#commit-messages).
4. Update `CHANGELOG.md` for user-visible changes.
5. Open the PR against `dev` and fill in `.github/pull_request_template.md`:
   - Summary
   - Related issue (**required for new logos**, otherwise the PR won't be accepted)
   - Changes
   - Screenshots (required for visual changes)
   - Checklist: confirm you tested locally

### Pre-submit checklist

```sh
clang-format -i <changed files>                  # format
codespell                                        # spelling
cmake -B build -DBUILD_TESTS=On && cmake --build build -j
cd build && ctest --output-on-failure            # tests
./build/fastfetch --format json                  # verify JSON output is well-formed
./build/fastfetch -c presets/all.jsonc --stat false   # smoke-test every module
```

---

## Gotchas

Things that are easy to get wrong when reading this codebase. Most of them follow from the "obsessively fast startup" goal.

### 1. Option structs must not exceed 256 bytes

`FF_OPTION_MAX_SIZE = 1 << 8`. Exceeding it is caught at compile time by `static_assert`. Don't try to raise the value — it determines the stack cost of every module invocation.

### 2. `FF_MODULE_DISABLE_*` controls registration, not compilation

```c
// verbatim from the top of modules/modules.c:
// FF_MODULE_DISABLE_<module> only controls if the module is registered,
// the module code itself is still compiled.
// We rely `LTO` to remove the unused code (only enabled in Release mode)
```

**Disabling modules in a Debug build does not shrink the binary.** LTO is enabled whenever `CMAKE_BUILD_TYPE != Debug`, and the default `RelWithDebInfo` already satisfies that — so measure size with `RelWithDebInfo` or `Release`, never with `Debug`. (The "Release mode" wording in the comment above is imprecise.)

### 3. CMake globs don't trigger reconfiguration

Both the module directories and the logo files are discovered by glob. CMake will not notice new files on its own — you need to re-run `cmake -B build` (or delete `build/CMakeCache.txt` and start over). This is the classic CMake footgun.

### 4. CLI module options are removed

Per-module command-line flags such as `--cpu-temp` are **no longer supported**. The only job of `ffParseModuleOptions` now is to translate the flag into a JSON key, then `exit(477)` with a pointer to the config file:

```
Error: Unsupported module option: --cpu-temp
       Support of module options has been removed. Please add the flag to the JSON config instead.
       Example (demonstration only): `{ "modules": [ { "type": "cpu", "temp": true } ] }`
```

**JSONC is the first-class configuration interface; the command line is not.** When adding module options, implement `parseJsonObject` only — do not add a CLI branch.

### 5. `defaultOrder = 0` hides a module from `--gen-config`

`collectModuleInfos` (`genconfig.c:186`) skips any module whose `defaultOrder` is `0`. C zero-initializes the field, so **omitting it is the same as setting it to 0**. Only `logo`, `command` and `custom` do this on purpose.

`defaultOrder` affects only the ordering in the interactive `--gen-config` picker; it has no effect on runtime output order.

### 6. Localization uses byte offsets, not enums

`instance.config.display.keyLanguage` does not hold a language enum — it holds a **byte offset** such as `offsetof(FFModuleDisplayName, zh_CN)`. The macro `FF_MODULE_GET_DISPLAY_NAME` (`common/option.h:123`) does plain pointer arithmetic with it:

```c
#define FF_MODULE_GET_DISPLAY_NAME(moduleName) \
    (*(const char**) ((uint8_t*) &ff ## moduleName ## ModuleInfo.displayName + instance.config.display.keyLanguage))
```

Consequence: **the field order of `FFModuleDisplayName` must never change** — reordering silently scrambles every language.

### 7. The `multithreading` switch barely does anything

The global `multithreading` option currently takes effect in exactly one place: `common/impl/networking_linux.c:339`. Modules are still printed sequentially. Modules that need concurrency go through the `ffPrepare*` warm-up hooks instead, which start sampling or fire off requests before the print loop begins.

### 8. Don't print or read config inside `detection/`

The `detection/` layer must stay pure: read system state, fill a struct, return an error string. Any `printf` or any read of `instance.config` there is a design error.

### 9. `src/logo/builtin.c` and `3rdparty/` are formatting-exempt

The former is a large generated/hand-maintained data table, the latter is upstream code. Both are excluded via `.clang-format-ignore` — leave them alone.

---

## Reference

- Configuration guide: <https://github.com/fastfetch-cli/fastfetch/wiki/Configuration>
- JSON schema: `doc/json_schema.json`
- Example presets: `presets/` (`all.jsonc`, `neofetch.jsonc`, `ci.jsonc`, …)
- Man page source: `doc/fastfetch.1.in`
- Code generation scripts: `scripts/` (`gen-pciids.py`, `gen-amdgpuids.py`, `gen-man.py`)