Add rules.toml: declarative event->action automation without Lua

Adds a bread.rules built-in module plus a breadd/src/core/rules.rs
parser/validator so the common "when event X happens, do Y" case
(dock connect script, AC-disconnect notification, keyboard rate on
connect) no longer requires hand-written init.lua.

- rules.toml is optional, XDG_CONFIG_HOME-aware (mirrors breadd.toml's
  config_path() resolution), and purely additive alongside init.lua.
- Each [[rule]] needs `on` (event suffix, "bread." implied, wildcards
  supported) and exactly one of run/exec/notify. `run` names a single
  script (tilde-expanded + shell-quoted so spaces in the path can't be
  word-split); `exec` is a raw shell command line passed through as-is;
  `notify` shows a desktop notification.
- Rule data is threaded into the bread.rules Lua module via globals
  set just before it loads (same technique load_profiles() already
  uses for __profiles_path), avoiding any need to hand-escape values
  into generated Lua source text.
- Parse/validation failures surface through the existing module
  load-error path (Lua error() -> run_on_load -> set_module_status),
  so a bad rules.toml shows up via `bread doctor` exactly like a
  broken hand-written module would, without blocking other valid
  rules in the same file.
- Documentation.md gets a new Getting-started fast path plus a
  Dictionary entry; README's Configuration section gets a short
  pointer. Since: v1.5.
This commit is contained in:
Breadway 2026-08-04 22:05:26 +08:00
parent 96639516b1
commit 45b5aee117
7 changed files with 904 additions and 6 deletions

View file

@ -256,6 +256,19 @@ fn config_path() -> PathBuf {
expand_home("~/.config/bread/breadd.toml")
}
/// Location of the optional `rules.toml` — declarative automation rules
/// (see `crate::core::rules`). Resolved with the exact same
/// `XDG_CONFIG_HOME`-vs-`HOME` precedence as `config_path()` above; see the
/// `expand_home` doc comment for why every config-adjacent path the daemon
/// resolves has to agree on that precedence.
pub fn rules_path() -> PathBuf {
if let Ok(xdg) = env::var("XDG_CONFIG_HOME") {
return Path::new(&xdg).join("bread").join("rules.toml");
}
expand_home("~/.config/bread/rules.toml")
}
/// Expands a leading `~/`. `~/.config/...` paths specifically prefer
/// `$XDG_CONFIG_HOME` when it's set, consistent with `config_path()`'s own
/// resolution of `breadd.toml` itself — otherwise the default `lua.entry_point`
@ -264,7 +277,7 @@ fn config_path() -> PathBuf {
/// though the config file that sets them was found via that same variable,
/// which is exactly the kind of inconsistency that made init.lua/module
/// loading silently no-op for a XDG_CONFIG_HOME-only test setup.
fn expand_home(input: &str) -> PathBuf {
pub(crate) fn expand_home(input: &str) -> PathBuf {
if let Some(stripped) = input.strip_prefix("~/.config/") {
if let Ok(xdg_config) = env::var("XDG_CONFIG_HOME") {
return Path::new(&xdg_config).join(stripped);
@ -586,4 +599,25 @@ log_level = "trace"
PathBuf::from("/synthetic/home/.config/bread/breadd.toml")
);
}
#[test]
fn rules_path_respects_xdg_config_home() {
let _g = EnvGuard::new(&["XDG_CONFIG_HOME", "HOME"]);
std::env::set_var("XDG_CONFIG_HOME", "/synthetic/xdg-config");
assert_eq!(
rules_path(),
PathBuf::from("/synthetic/xdg-config/bread/rules.toml")
);
}
#[test]
fn rules_path_falls_back_to_home_when_no_xdg() {
let _g = EnvGuard::new(&["XDG_CONFIG_HOME", "HOME"]);
std::env::remove_var("XDG_CONFIG_HOME");
std::env::set_var("HOME", "/synthetic/home");
assert_eq!(
rules_path(),
PathBuf::from("/synthetic/home/.config/bread/rules.toml")
);
}
}

View file

@ -1,5 +1,6 @@
pub mod config;
pub mod normalizer;
pub mod rules;
pub mod state_engine;
pub mod subscriptions;
pub mod supervisor;

410
breadd/src/core/rules.rs Normal file
View file

@ -0,0 +1,410 @@
//! `rules.toml` — a declarative shortcut for the common "when event X
//! happens, do Y" case that otherwise requires hand-written Lua
//! (`bread.on(...)`, `bread.exec(...)`, etc).
//!
//! This module owns TOML parsing and validation only; it has no `mlua`
//! dependency so it can be unit-tested in isolation. The `bread.rules`
//! built-in Lua module (`breadd/src/lua/mod.rs`, `BUILTIN_RULES`) is the
//! other half — it takes the [`ParsedRule`]s this module produces and turns
//! each one into a real `bread.on()` subscription.
//!
//! Schema:
//!
//! ```toml
//! [[rule]]
//! on = "device.dock.connected" # matched against "bread." .. on, wildcards allowed
//! run = "~/.config/bread/scripts/dock-connected.sh"
//!
//! [[rule]]
//! on = "power.ac.disconnected"
//! notify = "Unplugged"
//!
//! [[rule]]
//! on = "device.keyboard.connected"
//! exec = "xset r rate 200 40"
//! ```
//!
//! Exactly one of `run` / `notify` / `exec` must be set per rule. `run` and
//! `exec` both ultimately shell out via `bread.exec()`, but with distinct
//! semantics documented on [`RuleAction`].
use std::path::Path;
use serde::Deserialize;
#[derive(Debug, Default, Deserialize)]
struct RulesFile {
#[serde(default, rename = "rule")]
rule: Vec<RawRule>,
}
#[derive(Debug, Default, Deserialize)]
struct RawRule {
on: Option<String>,
run: Option<String>,
notify: Option<String>,
exec: Option<String>,
}
/// The action a validated rule fires when its event matches.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum RuleAction {
/// Path to a single script/executable. Treated as exactly one program —
/// tilde-expanded and shell-quoted as a whole before being handed to
/// `bread.exec()`, so a path containing spaces still runs as one file
/// rather than being word-split into a command plus arguments.
Run(String),
/// A raw shell command line, passed to `bread.exec()` verbatim (same as
/// calling `bread.exec()` from hand-written Lua) — you're responsible
/// for quoting/escaping exactly as if you'd typed it in a shell.
Exec(String),
/// A desktop notification message, passed to `bread.notify()`.
Notify(String),
}
/// A `[[rule]]` entry that passed validation.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ParsedRule {
/// Event-name suffix, e.g. `"device.dock.connected"`. The real
/// subscription is `"bread." .. on` — wildcards (`*`, `**`, `?`) are
/// whatever `bread.on()` itself supports, since this is handed straight
/// through.
pub on: String,
pub action: RuleAction,
}
/// A `[[rule]]` entry that failed validation — reported, not silently
/// dropped, so it shows up via `bread doctor` the same way a broken Lua
/// module would.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct RuleIssue {
/// Zero-based position of the `[[rule]]` table in the file.
pub index: usize,
/// The rule's `on` value, if it had one (helps identify *which* rule in
/// a large file when `on` itself isn't the problem).
pub on: Option<String>,
pub message: String,
}
impl std::fmt::Display for RuleIssue {
fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
match &self.on {
Some(on) => write!(f, "rule #{} (on = \"{}\"): {}", self.index, on, self.message),
None => write!(f, "rule #{}: {}", self.index, self.message),
}
}
}
/// Result of attempting to load `rules.toml`.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum RulesLoadOutcome {
/// The file doesn't exist. Not an error — `rules.toml` is entirely
/// optional and purely additive alongside `init.lua`.
Absent,
/// The file exists but couldn't be read, or doesn't parse as TOML at
/// all — no rules could be recovered from it.
Fatal(String),
/// The file parsed as TOML. `rules` are the entries that passed
/// validation (register these); `issues` describes any `[[rule]]`
/// entries that didn't (report these, but they don't block the rest of
/// the file from working).
Loaded {
rules: Vec<ParsedRule>,
issues: Vec<RuleIssue>,
},
}
/// Location of `rules.toml` — re-exported from `core::config` (single
/// source of truth, colocated with `config_path()`'s identical
/// `XDG_CONFIG_HOME`-vs-`HOME` resolution for `breadd.toml`) so callers that
/// only care about rules loading can reach it as `rules::rules_path()`.
pub use crate::core::config::rules_path;
/// Reads and validates `rules.toml` at `path`. Never panics — every failure
/// mode (missing file, unreadable file, invalid TOML, invalid individual
/// rules) is represented in the returned [`RulesLoadOutcome`].
pub fn load_rules(path: &Path) -> RulesLoadOutcome {
if !path.exists() {
return RulesLoadOutcome::Absent;
}
let raw = match std::fs::read_to_string(path) {
Ok(s) => s,
Err(e) => return RulesLoadOutcome::Fatal(format!("failed to read rules.toml: {e}")),
};
let parsed: RulesFile = match toml::from_str(&raw) {
Ok(v) => v,
Err(e) => return RulesLoadOutcome::Fatal(format!("failed to parse rules.toml: {e}")),
};
let mut rules = Vec::new();
let mut issues = Vec::new();
for (index, raw_rule) in parsed.rule.into_iter().enumerate() {
match validate_rule(index, raw_rule) {
Ok(rule) => rules.push(rule),
Err(issue) => issues.push(issue),
}
}
RulesLoadOutcome::Loaded { rules, issues }
}
fn validate_rule(index: usize, raw: RawRule) -> Result<ParsedRule, RuleIssue> {
let on = raw.on.filter(|s| !s.trim().is_empty());
let mut present = Vec::new();
if raw.run.is_some() {
present.push("run");
}
if raw.notify.is_some() {
present.push("notify");
}
if raw.exec.is_some() {
present.push("exec");
}
let Some(on) = on else {
return Err(RuleIssue {
index,
on: None,
message: "missing or empty `on`".to_string(),
});
};
if present.is_empty() {
return Err(RuleIssue {
index,
on: Some(on),
message: "must set exactly one of `run`, `notify`, `exec` (none set)".to_string(),
});
}
if present.len() > 1 {
return Err(RuleIssue {
index,
on: Some(on),
message: format!(
"must set exactly one of `run`, `notify`, `exec` (found: {})",
present.join(", ")
),
});
}
let action = if let Some(v) = raw.run {
RuleAction::Run(v)
} else if let Some(v) = raw.notify {
RuleAction::Notify(v)
} else {
RuleAction::Exec(raw.exec.expect("exactly one action present"))
};
Ok(ParsedRule { on, action })
}
#[cfg(test)]
mod tests {
use super::*;
use std::io::Write;
use std::path::PathBuf;
fn write_temp(contents: &str) -> (tempfile::TempDir, PathBuf) {
let dir = tempfile::tempdir().expect("tempdir");
let path = dir.path().join("rules.toml");
let mut f = std::fs::File::create(&path).expect("create rules.toml");
f.write_all(contents.as_bytes()).expect("write rules.toml");
(dir, path)
}
#[test]
fn absent_file_is_not_an_error() {
let dir = tempfile::tempdir().expect("tempdir");
let path = dir.path().join("does-not-exist.toml");
assert_eq!(load_rules(&path), RulesLoadOutcome::Absent);
}
#[test]
fn invalid_toml_is_fatal() {
let (_dir, path) = write_temp("[[rule\nbroken");
match load_rules(&path) {
RulesLoadOutcome::Fatal(msg) => assert!(msg.contains("failed to parse")),
other => panic!("expected Fatal, got {other:?}"),
}
}
#[test]
fn empty_file_loads_with_no_rules() {
let (_dir, path) = write_temp("");
assert_eq!(
load_rules(&path),
RulesLoadOutcome::Loaded {
rules: vec![],
issues: vec![],
}
);
}
#[test]
fn well_formed_rules_all_three_action_kinds_parse() {
let (_dir, path) = write_temp(
r#"
[[rule]]
on = "device.dock.connected"
run = "~/.config/bread/scripts/dock-connected.sh"
[[rule]]
on = "power.ac.disconnected"
notify = "Unplugged"
[[rule]]
on = "device.keyboard.connected"
exec = "xset r rate 200 40"
"#,
);
let RulesLoadOutcome::Loaded { rules, issues } = load_rules(&path) else {
panic!("expected Loaded");
};
assert!(issues.is_empty());
assert_eq!(
rules,
vec![
ParsedRule {
on: "device.dock.connected".to_string(),
action: RuleAction::Run(
"~/.config/bread/scripts/dock-connected.sh".to_string()
),
},
ParsedRule {
on: "power.ac.disconnected".to_string(),
action: RuleAction::Notify("Unplugged".to_string()),
},
ParsedRule {
on: "device.keyboard.connected".to_string(),
action: RuleAction::Exec("xset r rate 200 40".to_string()),
},
]
);
}
#[test]
fn wildcard_on_is_passed_through_unvalidated() {
let (_dir, path) = write_temp(
r#"
[[rule]]
on = "device.*.connected"
exec = "true"
"#,
);
let RulesLoadOutcome::Loaded { rules, issues } = load_rules(&path) else {
panic!("expected Loaded");
};
assert!(issues.is_empty());
assert_eq!(rules[0].on, "device.*.connected");
}
#[test]
fn missing_on_is_reported_with_index_and_no_on() {
let (_dir, path) = write_temp(
r#"
[[rule]]
exec = "true"
"#,
);
let RulesLoadOutcome::Loaded { rules, issues } = load_rules(&path) else {
panic!("expected Loaded");
};
assert!(rules.is_empty());
assert_eq!(issues.len(), 1);
assert_eq!(issues[0].index, 0);
assert_eq!(issues[0].on, None);
assert!(issues[0].message.contains("missing or empty"));
}
#[test]
fn empty_on_is_treated_as_missing() {
let (_dir, path) = write_temp(
r#"
[[rule]]
on = " "
exec = "true"
"#,
);
let RulesLoadOutcome::Loaded { issues, .. } = load_rules(&path) else {
panic!("expected Loaded");
};
assert_eq!(issues.len(), 1);
assert!(issues[0].message.contains("missing or empty"));
}
#[test]
fn zero_action_keys_is_reported() {
let (_dir, path) = write_temp(
r#"
[[rule]]
on = "power.ac.disconnected"
"#,
);
let RulesLoadOutcome::Loaded { rules, issues } = load_rules(&path) else {
panic!("expected Loaded");
};
assert!(rules.is_empty());
assert_eq!(issues.len(), 1);
assert_eq!(issues[0].on.as_deref(), Some("power.ac.disconnected"));
assert!(issues[0].message.contains("none set"));
}
#[test]
fn multiple_action_keys_is_reported() {
let (_dir, path) = write_temp(
r#"
[[rule]]
on = "power.ac.disconnected"
notify = "Unplugged"
exec = "true"
"#,
);
let RulesLoadOutcome::Loaded { rules, issues } = load_rules(&path) else {
panic!("expected Loaded");
};
assert!(rules.is_empty());
assert_eq!(issues.len(), 1);
assert!(issues[0].message.contains("notify"));
assert!(issues[0].message.contains("exec"));
}
#[test]
fn one_bad_rule_does_not_block_other_valid_rules() {
let (_dir, path) = write_temp(
r#"
[[rule]]
on = "device.dock.connected"
exec = "true"
[[rule]]
notify = "no on here"
[[rule]]
on = "power.ac.disconnected"
notify = "Unplugged"
"#,
);
let RulesLoadOutcome::Loaded { rules, issues } = load_rules(&path) else {
panic!("expected Loaded");
};
assert_eq!(rules.len(), 2);
assert_eq!(issues.len(), 1);
assert_eq!(issues[0].index, 1);
}
#[test]
fn rule_issue_display_includes_index_and_on() {
let issue = RuleIssue {
index: 2,
on: Some("power.ac.disconnected".to_string()),
message: "must set exactly one of `run`, `notify`, `exec` (none set)".to_string(),
};
assert_eq!(
issue.to_string(),
"rule #2 (on = \"power.ac.disconnected\"): must set exactly one of `run`, `notify`, `exec` (none set)"
);
}
}