komorebi/docs/dev/rule-matching.md

Window-rule matching: the three copies and the shared one

Paths (cutover stack): this document was written before the directories were renamed and keeps the paths of its time. Now: komorebi/ is komorebi-windows/, komorebi-for-kde/komorebi/ is komorebi-linux/, komorebi-for-mac/komorebi/ is komorebi-macos/, komorebi-for-kde/komorebi-hotkeys/ is komorebi-hotkeys/, komorebi-for-kde/nix/ and komorebi-for-mac/nix/ are nix/linux/ and nix/macos/, komorebi-for-kde/docs/ and komorebi-for-mac/docs/ are docs/linux/ and docs/macos/, schema*.json are in schemas/{windows,linux,macos}/, and every package is at version 0.2.0 (the 0.1.x numbers below are history).

should_act (the last rule of a list that matches a window, a composite rule needing all its conditions) and should_act_individual (one condition, by its matching strategy) existed three times: komorebi/src/window.rs (Windows), komorebi-for-kde/komorebi/src/window.rs and komorebi-for-mac/komorebi/src/window.rs. They are now komorebi_config::rules, one implementation that all three daemons call; each keeps its own function signatures as a thin wrapper so no call site changed.

Classification (diff of the three copies, before the move)

aspect	Windows	KDE	macOS
inputs	title, exe_name, class: &str, path	title, exe_name, classes: &[&str], path	same as KDE
classes	exactly one	any of the slice (for loop, true if any element satisfies the test)	same as KDE
.exe in the rule id	kept: exe_name carries .exe on Windows, ids are compared as written	identifier.id.replace(".exe", "") before anything else (every occurrence, also in a regex id and so in the regex-cache key looked up)	same as KDE
strategies (Legacy/None, Equals, DoesNotEqual, StartsWith, DoesNotStartWith, EndsWith, DoesNotEndWith, Contains, DoesNotContain, Regex)	same set, same semantics per kind	same	same
Legacy/None	title and class: starts or ends with the id; exe and path: equal	same	same
Regex	regex_identifiers.get(&id) keyed by the id, no entry means no match; applied to title, class, exe, path	same, class: any of the classes	same
case folding	none (all comparisons are case sensitive)	none	none
path handling	compared as given, no normalisation	same	same
should_act	last matching rule wins, composite = all conditions	identical to Windows except the classes type	identical to KDE
wrappers	should_act_window(_individual) pass the one class	same, pass &[class]	trait methods in workspace.rs call should_act
regex cache	REGEX_IDENTIFIERS static in komorebi/src/lib.rs, filled by static config	same name, KDE lib.rs	same name, macOS lib.rs

KDE and macOS are byte-identical in both functions. The Windows copy differs in exactly two ways, and both are preserved by a flag or a one-element slice:

1. one class instead of a list: [class] is equivalent to the single compare for every strategy (checked arm by arm: any-of over one element is the one test; the negated strategies too);
2. no .exe stripping: RuleQuirks::strip_exe_from_ids (false on Windows, true on KDE and macOS).

No other difference exists, so no per-call-site flag is needed beyond the one platform constant. The regex cache stays in each daemon (REGEX_IDENTIFIERS, lock order unchanged); the shared function receives it as &HashMap<String, Regex> exactly as the copies did.