feat(wm): add global layout_defaults for per-layout default options

Adds a top-level layout_defaults setting that defines default
layout_options and layout_options_rules per layout. Workspaces without
their own layout_options or layout_options_rules automatically inherit
the global defaults. If a workspace defines either setting, all global
defaults for that layout are fully replaced.

docs/common-workflows/layout-ratios.md

@@ -237,6 +237,78 @@ not specified in the matching rule default to their standard defaults (not the b
 
 This increases the visible scrolling columns as more windows are added.
 
+## Layout Defaults
+
+You can define global per-layout default `layout_options` and `layout_options_rules` using
+the top-level `layout_defaults` setting. This avoids repeating the same configuration across
+every workspace that uses the same layout.
+
+### Configuration
+
+```json
+{
+  "layout_defaults": {
+    "VerticalStack": {
+      "layout_options": { "column_ratios": [0.7] },
+      "layout_options_rules": {
+        "2": { "column_ratios": [0.7] },
+        "3": { "column_ratios": [0.55] },
+        "5": { "column_ratios": [0.4] }
+      }
+    },
+    "Columns": {
+      "layout_options": { "column_ratios": [0.3, 0.4] },
+      "layout_options_rules": {
+        "4": { "column_ratios": [0.2, 0.3, 0.3] }
+      }
+    },
+    "HorizontalStack": {
+      "layout_options": { "row_ratios": [0.6] }
+    }
+  },
+  "monitors": [
+    {
+      "workspaces": [
+        {
+          "name": "main",
+          "layout": "VerticalStack"
+        }
+      ]
+    }
+  ]
+}
+```
+
+In this example, every workspace using `VerticalStack`, `Columns`, or `HorizontalStack`
+automatically gets the global `layout_options` and `layout_options_rules` without needing
+to specify them per-workspace. Note that `VerticalStack` only has 2 columns (main + stack),
+so only a single `column_ratios` value is meaningful, while `Columns` distributes windows
+across multiple columns where additional ratios control each column's width.
+
+### Resolution Cascade
+
+Global defaults act as a fallback. If a workspace defines **either** `layout_options` or
+`layout_options_rules`, it **completely replaces** all global `layout_defaults` for that
+layout. Global defaults are only used when the workspace has **neither** setting.
+
+Within the effective source (workspace or global):
+1. Try threshold match from the rules (highest matching threshold wins)
+2. If a rule matches → use it (full replacement of base options)
+3. Otherwise → use the base `layout_options`
+
+### Override Examples
+
+| Workspace Config | Global Config | Effective Behavior |
+|------------------|---------------|--------------------|
+| No `layout_options`, no rules | `layout_defaults` has both | Uses global base + global rules |
+| Has `layout_options` only | `layout_defaults` has both | Workspace base only (all globals ignored) |
+| Has `layout_options_rules` only | `layout_defaults` has both | Workspace rules only (all globals ignored) |
+| Has both | `layout_defaults` has both | All workspace (all globals ignored) |
+
+This "complete replacement" semantic means you never get a mix of workspace and global
+settings for the same layout. If you override anything at the workspace level, you take
+full control of that layout's options for that workspace.
+
 ## Progressive Ratio Behavior
 
 Ratios are applied progressively as windows are added. For example, with `row_ratios: [0.3, 0.5]` in a VerticalStack:

komorebi-layouts/src/default_layout.rs

@@ -1,3 +1,5 @@
+use std::collections::HashMap;
+
 use clap::ValueEnum;
 use serde::Deserialize;
 use serde::Serialize;
@@ -54,7 +56,7 @@ pub fn validate_ratios(ratios: &[f32]) -> [Option<f32>; MAX_RATIOS] {
 }
 
 #[derive(
-    Clone, Copy, Debug, Serialize, Deserialize, Eq, PartialEq, Display, EnumString, ValueEnum,
+    Clone, Copy, Debug, Serialize, Deserialize, Eq, PartialEq, Hash, Display, EnumString, ValueEnum,
 )]
 #[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
 /// A predefined komorebi layout
@@ -250,6 +252,21 @@ pub struct GridLayoutOptions {
     pub rows: usize,
 }
 
+#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
+#[cfg_attr(feature = "schemars", derive(schemars::JsonSchema))]
+/// Per-layout default options entry for the `layout_defaults` global setting.
+/// Contains both base layout options and threshold-based layout options rules.
+pub struct LayoutDefaultEntry {
+    /// Default layout options for this layout
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub layout_options: Option<LayoutOptions>,
+    /// Threshold-based layout options rules in the format of threshold => options.
+    /// When container count >= threshold, the highest matching threshold's options
+    /// fully replace the base `layout_options`.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub layout_options_rules: Option<HashMap<usize, LayoutOptions>>,
+}
+
 impl DefaultLayout {
     pub fn leftmost_index(&self, len: usize) -> usize {
         match self {

komorebi-layouts/src/default_layout_tests.rs

@@ -433,3 +433,522 @@ mod layout_options_rules_tests {
         assert!(opts.grid.is_none());
     }
 }
+
+mod layout_default_entry_tests {
+    use super::*;
+    use std::collections::HashMap;
+
+    #[test]
+    fn test_default_layout_as_hashmap_key() {
+        let mut map: HashMap<DefaultLayout, &str> = HashMap::new();
+        map.insert(DefaultLayout::BSP, "bsp");
+        map.insert(DefaultLayout::VerticalStack, "vstack");
+        map.insert(DefaultLayout::Columns, "cols");
+
+        assert_eq!(map.len(), 3);
+        assert_eq!(map[&DefaultLayout::BSP], "bsp");
+        assert_eq!(map[&DefaultLayout::VerticalStack], "vstack");
+        assert_eq!(map[&DefaultLayout::Columns], "cols");
+    }
+
+    #[test]
+    fn test_default_layout_hash_consistency() {
+        // Same variant inserted twice should overwrite
+        let mut map: HashMap<DefaultLayout, i32> = HashMap::new();
+        map.insert(DefaultLayout::Grid, 1);
+        map.insert(DefaultLayout::Grid, 2);
+        assert_eq!(map.len(), 1);
+        assert_eq!(map[&DefaultLayout::Grid], 2);
+    }
+
+    #[test]
+    fn test_layout_default_entry_deserialize_full() {
+        let json = r#"{
+            "layout_options": {"column_ratios": [0.7]},
+            "layout_options_rules": {
+                "2": {"column_ratios": [0.7]},
+                "3": {"column_ratios": [0.55]},
+                "5": {"column_ratios": [0.3, 0.3, 0.3]}
+            }
+        }"#;
+        let entry: LayoutDefaultEntry = serde_json::from_str(json).unwrap();
+
+        let base = entry.layout_options.unwrap();
+        assert_eq!(base.column_ratios.unwrap()[0], Some(0.7));
+
+        let rules = entry.layout_options_rules.unwrap();
+        assert_eq!(rules.len(), 3);
+        assert_eq!(rules[&2].column_ratios.unwrap()[0], Some(0.7));
+        assert_eq!(rules[&3].column_ratios.unwrap()[0], Some(0.55));
+        let r5 = rules[&5].column_ratios.unwrap();
+        assert_eq!(r5[0], Some(0.3));
+        assert_eq!(r5[1], Some(0.3));
+        assert_eq!(r5[2], Some(0.3));
+    }
+
+    #[test]
+    fn test_layout_default_entry_deserialize_only_base() {
+        let json = r#"{
+            "layout_options": {"column_ratios": [0.6]}
+        }"#;
+        let entry: LayoutDefaultEntry = serde_json::from_str(json).unwrap();
+
+        assert!(entry.layout_options.is_some());
+        assert_eq!(
+            entry.layout_options.unwrap().column_ratios.unwrap()[0],
+            Some(0.6)
+        );
+        assert!(entry.layout_options_rules.is_none());
+    }
+
+    #[test]
+    fn test_layout_default_entry_deserialize_only_rules() {
+        let json = r#"{
+            "layout_options_rules": {
+                "3": {"column_ratios": [0.4]}
+            }
+        }"#;
+        let entry: LayoutDefaultEntry = serde_json::from_str(json).unwrap();
+
+        assert!(entry.layout_options.is_none());
+        let rules = entry.layout_options_rules.unwrap();
+        assert_eq!(rules.len(), 1);
+        assert_eq!(rules[&3].column_ratios.unwrap()[0], Some(0.4));
+    }
+
+    #[test]
+    fn test_layout_default_entry_deserialize_empty() {
+        let json = r#"{}"#;
+        let entry: LayoutDefaultEntry = serde_json::from_str(json).unwrap();
+        assert!(entry.layout_options.is_none());
+        assert!(entry.layout_options_rules.is_none());
+    }
+
+    #[test]
+    fn test_layout_default_entry_roundtrip() {
+        let json = r#"{
+            "layout_options": {"column_ratios": [0.7]},
+            "layout_options_rules": {
+                "2": {"column_ratios": [0.6]},
+                "5": {"column_ratios": [0.3, 0.3, 0.3]}
+            }
+        }"#;
+        let original: LayoutDefaultEntry = serde_json::from_str(json).unwrap();
+        let serialized = serde_json::to_string(&original).unwrap();
+        let deserialized: LayoutDefaultEntry = serde_json::from_str(&serialized).unwrap();
+
+        assert_eq!(
+            original.layout_options.unwrap().column_ratios,
+            deserialized.layout_options.unwrap().column_ratios
+        );
+        let orig_rules = original.layout_options_rules.unwrap();
+        let deser_rules = deserialized.layout_options_rules.unwrap();
+        assert_eq!(orig_rules.len(), deser_rules.len());
+        for (key, orig_opts) in &orig_rules {
+            let deser_opts = &deser_rules[key];
+            assert_eq!(orig_opts.column_ratios, deser_opts.column_ratios);
+        }
+    }
+
+    #[test]
+    fn test_layout_defaults_full_config_deserialize() {
+        // Simulate the top-level layout_defaults field
+        let json = r#"{
+            "VerticalStack": {
+                "layout_options": {"column_ratios": [0.7]},
+                "layout_options_rules": {
+                    "2": {"column_ratios": [0.7]},
+                    "3": {"column_ratios": [0.55]}
+                }
+            },
+            "HorizontalStack": {
+                "layout_options": {"column_ratios": [0.6]}
+            },
+            "Columns": {
+                "layout_options_rules": {
+                    "4": {"column_ratios": [0.3, 0.3, 0.3]}
+                }
+            }
+        }"#;
+        let defaults: HashMap<DefaultLayout, LayoutDefaultEntry> =
+            serde_json::from_str(json).unwrap();
+
+        assert_eq!(defaults.len(), 3);
+
+        // VerticalStack: has both base and rules
+        let vs = &defaults[&DefaultLayout::VerticalStack];
+        assert!(vs.layout_options.is_some());
+        assert_eq!(vs.layout_options_rules.as_ref().unwrap().len(), 2);
+
+        // HorizontalStack: has only base
+        let hs = &defaults[&DefaultLayout::HorizontalStack];
+        assert!(hs.layout_options.is_some());
+        assert!(hs.layout_options_rules.is_none());
+
+        // Columns: has only rules
+        let cols = &defaults[&DefaultLayout::Columns];
+        assert!(cols.layout_options.is_none());
+        assert_eq!(cols.layout_options_rules.as_ref().unwrap().len(), 1);
+    }
+
+    #[test]
+    fn test_layout_default_entry_with_scrolling_and_grid() {
+        let json = r#"{
+            "layout_options": {
+                "column_ratios": [0.5],
+                "scrolling": {"columns": 3},
+                "grid": {"rows": 2}
+            },
+            "layout_options_rules": {
+                "4": {
+                    "scrolling": {"columns": 5, "center_focused_column": true}
+                }
+            }
+        }"#;
+        let entry: LayoutDefaultEntry = serde_json::from_str(json).unwrap();
+
+        let base = entry.layout_options.unwrap();
+        assert_eq!(base.scrolling.unwrap().columns, 3);
+        assert_eq!(base.grid.unwrap().rows, 2);
+
+        let rules = entry.layout_options_rules.unwrap();
+        let r4 = &rules[&4];
+        assert_eq!(r4.scrolling.unwrap().columns, 5);
+        assert_eq!(r4.scrolling.unwrap().center_focused_column, Some(true));
+        // Rule doesn't inherit base fields - full replacement
+        assert!(r4.column_ratios.is_none());
+        assert!(r4.grid.is_none());
+    }
+
+    #[test]
+    fn test_layout_default_entry_skip_serializing_none() {
+        // When both fields are None, they should not appear in output
+        let entry = LayoutDefaultEntry {
+            layout_options: None,
+            layout_options_rules: None,
+        };
+        let json = serde_json::to_string(&entry).unwrap();
+        assert!(!json.contains("layout_options"));
+        assert!(!json.contains("layout_options_rules"));
+        assert_eq!(json, "{}");
+    }
+}
+
+/// Tests for the complete-replacement cascade logic.
+///
+/// This mirrors the resolution algorithm in workspace.rs::update():
+///   - If the workspace defines EITHER layout_options OR layout_options_rules,
+///     it completely replaces the global layout_defaults for this layout.
+///   - Global defaults are only used when the workspace has NEITHER setting.
+///   - Within the effective source (workspace or global):
+///     1. Try threshold match from rules (highest matching threshold wins)
+///     2. If a rule matches -> use it (full replacement of base)
+///     3. Else -> use the base layout_options
+///
+/// Since the actual cascade is in workspace.rs (which has heavy WM dependencies),
+/// we test the pure algorithm here using the same data structures.
+mod cascade_resolution_tests {
+    use super::*;
+
+    /// Simulates the cascade resolution logic from workspace.rs::update().
+    /// This is a pure function equivalent of the inline code in update().
+    fn resolve_effective_options(
+        container_count: usize,
+        workspace_base: Option<LayoutOptions>,
+        workspace_rules: &[(usize, LayoutOptions)], // sorted by threshold ascending
+        global_base: Option<LayoutOptions>,
+        global_rules: &[(usize, LayoutOptions)], // sorted by threshold ascending
+    ) -> Option<LayoutOptions> {
+        let has_workspace_overrides = workspace_base.is_some() || !workspace_rules.is_empty();
+
+        let (effective_base, effective_rules): (Option<LayoutOptions>, &[(usize, LayoutOptions)]) =
+            if has_workspace_overrides {
+                (workspace_base, workspace_rules)
+            } else {
+                (global_base, global_rules)
+            };
+
+        // Try threshold match from effective rules
+        let mut matched = None;
+        for (threshold, opts) in effective_rules {
+            if container_count >= *threshold {
+                matched = Some(*opts);
+            }
+        }
+
+        // If a rule matched, use it (full replacement); otherwise use effective base
+        if matched.is_some() {
+            matched
+        } else {
+            effective_base
+        }
+    }
+
+    fn opts_with_ratio(ratio: f32) -> LayoutOptions {
+        layout_options_with_column_ratios(&[ratio])
+    }
+
+    // --- No overrides ---
+
+    #[test]
+    fn test_no_workspace_no_global_returns_none() {
+        let result = resolve_effective_options(3, None, &[], None, &[]);
+        assert!(result.is_none());
+    }
+
+    // --- Base-only scenarios ---
+
+    #[test]
+    fn test_workspace_base_only() {
+        let ws_base = opts_with_ratio(0.7);
+        let result = resolve_effective_options(3, Some(ws_base), &[], None, &[]);
+        assert_eq!(result.unwrap().column_ratios, ws_base.column_ratios);
+    }
+
+    #[test]
+    fn test_global_base_only() {
+        let global_base = opts_with_ratio(0.6);
+        let result = resolve_effective_options(3, None, &[], Some(global_base), &[]);
+        assert_eq!(result.unwrap().column_ratios, global_base.column_ratios);
+    }
+
+    #[test]
+    fn test_workspace_base_overrides_all_globals() {
+        // Workspace has base → globals (both base and rules) are ignored entirely
+        let ws_base = opts_with_ratio(0.7);
+        let global_base = opts_with_ratio(0.6);
+        let global_rules = vec![(2, opts_with_ratio(0.5))];
+        let result =
+            resolve_effective_options(3, Some(ws_base), &[], Some(global_base), &global_rules);
+        // Workspace base wins; global rules are NOT used even though they would match
+        assert_eq!(result.unwrap().column_ratios, ws_base.column_ratios);
+    }
+
+    // --- Rules-only scenarios ---
+
+    #[test]
+    fn test_global_rules_match() {
+        let global_rules = vec![(2, opts_with_ratio(0.6)), (4, opts_with_ratio(0.5))];
+        // 3 containers: matches threshold 2, not 4
+        let result = resolve_effective_options(3, None, &[], None, &global_rules);
+        assert_eq!(result.unwrap().column_ratios.unwrap()[0], Some(0.6));
+    }
+
+    #[test]
+    fn test_global_rules_highest_matching_threshold_wins() {
+        let global_rules = vec![(2, opts_with_ratio(0.6)), (4, opts_with_ratio(0.5))];
+        // 5 containers: matches both thresholds 2 and 4; highest (4) wins
+        let result = resolve_effective_options(5, None, &[], None, &global_rules);
+        assert_eq!(result.unwrap().column_ratios.unwrap()[0], Some(0.5));
+    }
+
+    #[test]
+    fn test_global_rules_no_match_falls_through_to_none() {
+        let global_rules = vec![(5, opts_with_ratio(0.5))];
+        // 3 containers: doesn't match threshold 5
+        let result = resolve_effective_options(3, None, &[], None, &global_rules);
+        assert!(result.is_none());
+    }
+
+    #[test]
+    fn test_global_rules_no_match_falls_through_to_global_base() {
+        let global_base = opts_with_ratio(0.6);
+        let global_rules = vec![(5, opts_with_ratio(0.5))];
+        // 3 containers: doesn't match threshold 5, falls back to global base
+        let result = resolve_effective_options(3, None, &[], Some(global_base), &global_rules);
+        assert_eq!(result.unwrap().column_ratios, global_base.column_ratios);
+    }
+
+    #[test]
+    fn test_workspace_rules_override_global_rules() {
+        let ws_rules = vec![(2, opts_with_ratio(0.8))];
+        let global_rules = vec![(2, opts_with_ratio(0.6))];
+        // Workspace has rules → global rules are ignored entirely
+        let result = resolve_effective_options(3, None, &ws_rules, None, &global_rules);
+        assert_eq!(result.unwrap().column_ratios.unwrap()[0], Some(0.8));
+    }
+
+    // --- Complete replacement: workspace having EITHER setting disables ALL globals ---
+
+    #[test]
+    fn test_workspace_rules_disable_global_base() {
+        // Workspace has rules but no base. Global has base.
+        // Since workspace has a setting, globals are completely replaced.
+        let ws_rules = vec![(2, opts_with_ratio(0.8))];
+        let global_base = opts_with_ratio(0.6);
+        // Rule matches → use it. Global base is NOT available as fallback.
+        let result = resolve_effective_options(3, None, &ws_rules, Some(global_base), &[]);
+        assert_eq!(result.unwrap().column_ratios.unwrap()[0], Some(0.8));
+    }
+
+    #[test]
+    fn test_workspace_rules_no_match_does_not_fall_to_global_base() {
+        // Workspace has rules (but they don't match). Global has base.
+        // Since workspace has a setting, globals are completely replaced → returns None.
+        let ws_rules = vec![(5, opts_with_ratio(0.8))];
+        let global_base = opts_with_ratio(0.6);
+        let result = resolve_effective_options(3, None, &ws_rules, Some(global_base), &[]);
+        // No workspace base, no rule match, globals ignored → None
+        assert!(result.is_none());
+    }
+
+    #[test]
+    fn test_workspace_base_disables_global_rules() {
+        // Workspace has base but no rules. Global has rules.
+        // Since workspace has a setting, globals are completely replaced.
+        let ws_base = opts_with_ratio(0.7);
+        let global_rules = vec![(2, opts_with_ratio(0.5))];
+        // No workspace rules → no rule match → use workspace base. Global rules ignored.
+        let result = resolve_effective_options(3, Some(ws_base), &[], None, &global_rules);
+        assert_eq!(result.unwrap().column_ratios, ws_base.column_ratios);
+    }
+
+    #[test]
+    fn test_workspace_base_disables_global_rules_and_base() {
+        // Workspace has base. Global has both rules and base.
+        // Since workspace has a setting, all globals are completely replaced.
+        let ws_base = opts_with_ratio(0.7);
+        let global_base = opts_with_ratio(0.6);
+        let global_rules = vec![(2, opts_with_ratio(0.5))];
+        let result =
+            resolve_effective_options(3, Some(ws_base), &[], Some(global_base), &global_rules);
+        // Only workspace base is used; global rules and base are both ignored
+        assert_eq!(result.unwrap().column_ratios, ws_base.column_ratios);
+    }
+
+    #[test]
+    fn test_workspace_rules_disable_global_rules_and_base() {
+        // Workspace has rules. Global has both rules and base.
+        // Since workspace has a setting, all globals are completely replaced.
+        let ws_rules = vec![(2, opts_with_ratio(0.8))];
+        let global_base = opts_with_ratio(0.6);
+        let global_rules = vec![(2, opts_with_ratio(0.5))];
+        let result =
+            resolve_effective_options(3, None, &ws_rules, Some(global_base), &global_rules);
+        // Workspace rule matches → 0.8. Global base and rules both ignored.
+        assert_eq!(result.unwrap().column_ratios.unwrap()[0], Some(0.8));
+    }
+
+    // --- Full replacement semantics (rule match replaces base) ---
+
+    #[test]
+    fn test_rule_match_is_full_replacement_not_merge() {
+        // When a rule matches, its options FULLY REPLACE the base.
+        // Fields not specified in the rule default to their standard defaults.
+        let ws_base = layout_options_with_ratios(&[0.7], &[0.4]);
+        let rule_opts = layout_options_with_column_ratios(&[0.5]);
+        // rule_opts has column_ratios but no row_ratios
+        let ws_rules = vec![(2, rule_opts)];
+        let result = resolve_effective_options(3, Some(ws_base), &ws_rules, None, &[]);
+        let effective = result.unwrap();
+        // Column ratios come from the rule
+        assert_eq!(effective.column_ratios.unwrap()[0], Some(0.5));
+        // Row ratios are NOT inherited from ws_base - they're None (full replacement)
+        assert!(effective.row_ratios.is_none());
+    }
+
+    // --- Edge cases ---
+
+    #[test]
+    fn test_exact_threshold_match() {
+        let rules = vec![(3, opts_with_ratio(0.6))];
+        let result = resolve_effective_options(3, None, &rules, None, &[]);
+        assert_eq!(result.unwrap().column_ratios.unwrap()[0], Some(0.6));
+    }
+
+    #[test]
+    fn test_container_count_one_below_threshold() {
+        let rules = vec![(3, opts_with_ratio(0.6))];
+        let result = resolve_effective_options(2, None, &rules, None, &[]);
+        assert!(result.is_none());
+    }
+
+    #[test]
+    fn test_zero_containers() {
+        let ws_base = opts_with_ratio(0.7);
+        let rules = vec![(1, opts_with_ratio(0.5))];
+        let result = resolve_effective_options(0, Some(ws_base), &rules, None, &[]);
+        // 0 containers doesn't match threshold 1 → falls back to workspace base
+        assert_eq!(result.unwrap().column_ratios, ws_base.column_ratios);
+    }
+
+    #[test]
+    fn test_many_thresholds_correct_match() {
+        let rules = vec![
+            (1, opts_with_ratio(0.8)),
+            (3, opts_with_ratio(0.6)),
+            (5, opts_with_ratio(0.4)),
+            (8, opts_with_ratio(0.3)),
+        ];
+        // 6 containers: matches 1, 3, 5 but not 8. Highest match is 5.
+        let result = resolve_effective_options(6, None, &rules, None, &[]);
+        assert_eq!(result.unwrap().column_ratios.unwrap()[0], Some(0.4));
+    }
+
+    #[test]
+    fn test_workspace_rules_disable_global_rules_even_if_ws_rules_dont_match() {
+        // Key behavior: if workspace has ANY setting, globals are entirely ignored.
+        // Even if workspace rules don't match, we don't fall back to global rules.
+        let ws_rules = vec![(10, opts_with_ratio(0.8))]; // threshold too high
+        let global_rules = vec![(2, opts_with_ratio(0.5))]; // would match
+        let result = resolve_effective_options(3, None, &ws_rules, None, &global_rules);
+        // Workspace has rules → all globals ignored. WS rules don't match → None.
+        assert!(result.is_none());
+    }
+
+    #[test]
+    fn test_all_four_sources_present_rules_match() {
+        // All four sources present: workspace base, workspace rules, global base, global rules
+        let ws_base = opts_with_ratio(0.7);
+        let ws_rules = vec![(2, opts_with_ratio(0.8))];
+        let global_base = opts_with_ratio(0.6);
+        let global_rules = vec![(2, opts_with_ratio(0.5))];
+        let result = resolve_effective_options(
+            3,
+            Some(ws_base),
+            &ws_rules,
+            Some(global_base),
+            &global_rules,
+        );
+        // Workspace has settings → uses workspace only. Rule matches → 0.8
+        assert_eq!(result.unwrap().column_ratios.unwrap()[0], Some(0.8));
+    }
+
+    #[test]
+    fn test_all_four_sources_present_rules_no_match() {
+        // All four sources present, but workspace rules don't match
+        let ws_base = opts_with_ratio(0.7);
+        let ws_rules = vec![(10, opts_with_ratio(0.8))]; // threshold too high
+        let global_base = opts_with_ratio(0.6);
+        let global_rules = vec![(10, opts_with_ratio(0.5))]; // also too high
+        let result = resolve_effective_options(
+            3,
+            Some(ws_base),
+            &ws_rules,
+            Some(global_base),
+            &global_rules,
+        );
+        // Workspace has settings → uses workspace only. No rule match → workspace base 0.7
+        assert_eq!(result.unwrap().column_ratios, ws_base.column_ratios);
+    }
+
+    // --- Workspace with both base and rules ---
+
+    #[test]
+    fn test_workspace_both_rule_matches() {
+        let ws_base = opts_with_ratio(0.7);
+        let ws_rules = vec![(2, opts_with_ratio(0.5))];
+        let result = resolve_effective_options(3, Some(ws_base), &ws_rules, None, &[]);
+        // Rule matches → use rule (full replacement), not ws_base
+        assert_eq!(result.unwrap().column_ratios.unwrap()[0], Some(0.5));
+    }
+
+    #[test]
+    fn test_workspace_both_rule_no_match() {
+        let ws_base = opts_with_ratio(0.7);
+        let ws_rules = vec![(10, opts_with_ratio(0.5))];
+        let result = resolve_effective_options(3, Some(ws_base), &ws_rules, None, &[]);
+        // Rule doesn't match → fall back to ws_base
+        assert_eq!(result.unwrap().column_ratios, ws_base.column_ratios);
+    }
+}

komorebi/src/core/mod.rs

@@ -32,6 +32,7 @@ pub use komorebi_layouts::DefaultLayout;
 pub use komorebi_layouts::Direction;
 pub use komorebi_layouts::GridLayoutOptions;
 pub use komorebi_layouts::Layout;
+pub use komorebi_layouts::LayoutDefaultEntry;
 pub use komorebi_layouts::LayoutOptions;
 pub use komorebi_layouts::MAX_RATIO;
 pub use komorebi_layouts::MAX_RATIOS;

komorebi/src/lib.rs

@@ -238,6 +238,9 @@ lazy_static! {
     static ref FLOATING_WINDOW_TOGGLE_ASPECT_RATIO: Arc<Mutex<AspectRatio>> = Arc::new(Mutex::new(AspectRatio::Predefined(PredefinedAspectRatio::Widescreen)));
 
     static ref CURRENT_VIRTUAL_DESKTOP: Arc<Mutex<Option<Vec<u8>>>> = Arc::new(Mutex::new(None));
+
+    pub static ref LAYOUT_DEFAULTS: Arc<Mutex<HashMap<DefaultLayout, LayoutDefaultEntry>>> =
+        Arc::new(Mutex::new(HashMap::new()));
 }
 
 pub static DEFAULT_WORKSPACE_PADDING: AtomicI32 = AtomicI32::new(10);

komorebi/src/state.rs

@@ -254,6 +254,7 @@ impl From<&WindowManager> for State {
                             layout_options: workspace.layout_options,
                             layout_rules: workspace.layout_rules.clone(),
                             layout_options_rules: workspace.layout_options_rules.clone(),
+                            layout_defaults_cache: workspace.layout_defaults_cache.clone(),
                             work_area_offset_rules: workspace.work_area_offset_rules.clone(),
                             layout_flip: workspace.layout_flip,
                             workspace_padding: workspace.workspace_padding,

komorebi/src/static_config.rs

@@ -13,6 +13,7 @@ use crate::FloatingLayerBehaviour;
 use crate::HIDING_BEHAVIOUR;
 use crate::IGNORE_IDENTIFIERS;
 use crate::LAYERED_WHITELIST;
+use crate::LAYOUT_DEFAULTS;
 use crate::MANAGE_IDENTIFIERS;
 use crate::MONITOR_INDEX_PREFERENCES;
 use crate::NO_TITLEBAR;
@@ -53,6 +54,7 @@ use crate::core::DefaultLayout;
 use crate::core::FocusFollowsMouseImplementation;
 use crate::core::HidingBehaviour;
 use crate::core::Layout;
+use crate::core::LayoutDefaultEntry;
 use crate::core::LayoutOptions;
 use crate::core::MoveBehaviour;
 use crate::core::OperationBehaviour;
@@ -593,6 +595,11 @@ pub struct StaticConfig {
     #[serde(skip_serializing_if = "Option::is_none")]
     #[cfg_attr(feature = "schemars", schemars(extend("default" = DEFAULT_CONTAINER_PADDING)))]
     pub default_container_padding: Option<i32>,
+    /// Per-layout default options and rules, keyed by layout name.
+    /// Applied as fallback when a workspace does not define its own layout_options or layout_options_rules.
+    /// If a workspace defines either setting, all global defaults for that layout are completely replaced.
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub layout_defaults: Option<HashMap<DefaultLayout, LayoutDefaultEntry>>,
     /// Monitor and workspace configurations
     #[serde(skip_serializing_if = "Option::is_none")]
     pub monitors: Option<Vec<MonitorConfig>>,
@@ -902,6 +909,14 @@ impl From<&WindowManager> for StaticConfig {
             default_container_padding: Option::from(
                 DEFAULT_CONTAINER_PADDING.load(Ordering::SeqCst),
             ),
+            layout_defaults: {
+                let guard = LAYOUT_DEFAULTS.lock();
+                if guard.is_empty() {
+                    None
+                } else {
+                    Some(guard.clone())
+                }
+            },
             monitors: Option::from(monitors),
             window_hiding_behaviour: Option::from(*HIDING_BEHAVIOUR.lock()),
             global_work_area_offset: value.work_area_offset,
@@ -1017,6 +1032,12 @@ impl StaticConfig {
             DEFAULT_WORKSPACE_PADDING.store(workspace, Ordering::SeqCst);
         }
 
+        if let Some(defaults) = &self.layout_defaults {
+            *LAYOUT_DEFAULTS.lock() = defaults.clone();
+        } else {
+            LAYOUT_DEFAULTS.lock().clear();
+        }
+
         if let Some(border_width) = self.border_width {
             border_manager::BORDER_WIDTH.store(border_width, Ordering::SeqCst);
         }
@@ -1425,7 +1446,7 @@ impl StaticConfig {
                             workspace_config.layout = Some(DefaultLayout::Columns);
                         }
 
-                        ws.load_static_config(workspace_config)?;
+                        ws.load_static_config(workspace_config, value.layout_defaults.as_ref())?;
                     }
                 }
 
@@ -1508,7 +1529,10 @@ impl StaticConfig {
 
                     for (j, ws) in m.workspaces_mut().iter_mut().enumerate() {
                         if let Some(workspace_config) = monitor_config.workspaces.get(j) {
-                            ws.load_static_config(workspace_config)?;
+                            ws.load_static_config(
+                                workspace_config,
+                                value.layout_defaults.as_ref(),
+                            )?;
                         }
                     }
 
@@ -1590,7 +1614,7 @@ impl StaticConfig {
 
                 for (j, ws) in monitor.workspaces_mut().iter_mut().enumerate() {
                     if let Some(workspace_config) = monitor_config.workspaces.get(j) {
-                        ws.load_static_config(workspace_config)?;
+                        ws.load_static_config(workspace_config, value.layout_defaults.as_ref())?;
                     }
                 }
 
@@ -1673,7 +1697,10 @@ impl StaticConfig {
 
                     for (j, ws) in m.workspaces_mut().iter_mut().enumerate() {
                         if let Some(workspace_config) = monitor_config.workspaces.get(j) {
-                            ws.load_static_config(workspace_config)?;
+                            ws.load_static_config(
+                                workspace_config,
+                                value.layout_defaults.as_ref(),
+                            )?;
                         }
                     }
 

komorebi/src/workspace.rs

@@ -1,3 +1,4 @@
+use std::collections::HashMap;
 use std::collections::VecDeque;
 use std::ffi::OsStr;
 use std::fmt::Display;
@@ -25,6 +26,7 @@ use crate::core::CustomLayout;
 use crate::core::CycleDirection;
 use crate::core::DefaultLayout;
 use crate::core::Layout;
+use crate::core::LayoutDefaultEntry;
 use crate::core::LayoutOptions;
 use crate::core::OperationDirection;
 use crate::core::Rect;
@@ -65,6 +67,10 @@ pub struct Workspace {
     /// Sorted by threshold ascending at load time.
     #[serde(default)]
     pub layout_options_rules: Vec<(usize, LayoutOptions)>,
+    /// Cached per-layout defaults from the global `layout_defaults` config setting.
+    /// Pre-sorted at config load time; used as fallback when workspace has no overrides.
+    #[serde(skip)]
+    pub(crate) layout_defaults_cache: HashMap<DefaultLayout, CachedLayoutDefault>,
     pub work_area_offset_rules: Vec<(usize, Rect)>,
     pub layout_flip: Option<Axis>,
     pub workspace_padding: Option<i32>,
@@ -124,6 +130,7 @@ impl Default for Workspace {
             layout_options: None,
             layout_rules: vec![],
             layout_options_rules: vec![],
+            layout_defaults_cache: HashMap::new(),
             work_area_offset_rules: vec![],
             layout_flip: None,
             workspace_padding: Option::from(DEFAULT_WORKSPACE_PADDING.load(Ordering::SeqCst)),
@@ -170,8 +177,49 @@ pub struct WorkspaceGlobals {
     pub floating_layer_behaviour: Option<FloatingLayerBehaviour>,
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
+/// Cached per-layout default options (pre-sorted rules) derived from the global `layout_defaults`.
+pub(crate) struct CachedLayoutDefault {
+    pub layout_options: Option<LayoutOptions>,
+    /// Threshold-based rules, sorted by threshold ascending at load time
+    pub layout_options_rules: Vec<(usize, LayoutOptions)>,
+}
+
+/// Convert an optional HashMap of threshold-based layout options rules into a Vec sorted by
+/// threshold ascending.
+fn sorted_layout_options_rules(
+    rules: Option<&HashMap<usize, LayoutOptions>>,
+) -> Vec<(usize, LayoutOptions)> {
+    match rules {
+        Some(rules) => {
+            let mut sorted: Vec<(usize, LayoutOptions)> =
+                rules.iter().map(|(t, o)| (*t, *o)).collect();
+            sorted.sort_by_key(|(t, _)| *t);
+            sorted
+        }
+        None => vec![],
+    }
+}
+
+/// Find the highest matching threshold rule for the given container count.
+/// Rules must be sorted by threshold ascending.
+fn resolve_threshold_match(
+    rules: &[(usize, LayoutOptions)],
+    container_count: usize,
+) -> Option<LayoutOptions> {
+    rules
+        .iter()
+        .rev()
+        .find(|(threshold, _)| container_count >= *threshold)
+        .map(|(_, opts)| *opts)
+}
+
 impl Workspace {
-    pub fn load_static_config(&mut self, config: &WorkspaceConfig) -> eyre::Result<()> {
+    pub fn load_static_config(
+        &mut self,
+        config: &WorkspaceConfig,
+        layout_defaults: Option<&HashMap<DefaultLayout, LayoutDefaultEntry>>,
+    ) -> eyre::Result<()> {
         self.name = Option::from(config.name.clone());
 
         self.container_padding = config.container_padding;
@@ -261,14 +309,8 @@ impl Workspace {
         self.layout_options = config.layout_options;
 
         // Load threshold-based layout options rules, sorted by threshold ascending
-        self.layout_options_rules = if let Some(rules) = &config.layout_options_rules {
-            let mut sorted_rules: Vec<(usize, LayoutOptions)> =
-                rules.iter().map(|(t, o)| (*t, *o)).collect();
-            sorted_rules.sort_by_key(|(t, _)| *t);
-            sorted_rules
-        } else {
-            vec![]
-        };
+        self.layout_options_rules =
+            sorted_layout_options_rules(config.layout_options_rules.as_ref());
 
         tracing::debug!(
             "Workspace '{}' loaded layout_options: {:?}, layout_options_rules: {} entries",
@@ -277,11 +319,63 @@ impl Workspace {
             self.layout_options_rules.len(),
         );
 
+        // Cache per-layout defaults from global layout_defaults, pre-sorting rules
+        self.layout_defaults_cache = if let Some(defaults) = layout_defaults {
+            defaults
+                .iter()
+                .map(|(layout, entry)| {
+                    (
+                        *layout,
+                        CachedLayoutDefault {
+                            layout_options: entry.layout_options,
+                            layout_options_rules: sorted_layout_options_rules(
+                                entry.layout_options_rules.as_ref(),
+                            ),
+                        },
+                    )
+                })
+                .collect()
+        } else {
+            HashMap::new()
+        };
+
         self.workspace_config = Some(config.clone());
 
         Ok(())
     }
 
+    /// Compute effective layout options using the complete-replacement cascade:
+    ///
+    /// If the workspace defines EITHER `layout_options` OR `layout_options_rules`,
+    /// it completely replaces the global `layout_defaults` for this layout.
+    /// Global defaults are only used when the workspace has NEITHER setting.
+    ///
+    /// Within the effective source (workspace or global):
+    ///   1. Try threshold match from rules (highest matching threshold wins)
+    ///   2. If a rule matches -> use it (full replacement of base)
+    ///   3. Else -> use the base `layout_options`
+    fn effective_layout_options(&self) -> Option<LayoutOptions> {
+        let container_count = self.containers().len();
+
+        let has_workspace_overrides =
+            self.layout_options.is_some() || !self.layout_options_rules.is_empty();
+
+        let (effective_base, effective_rules): (Option<LayoutOptions>, &[(usize, LayoutOptions)]) =
+            if has_workspace_overrides {
+                (self.layout_options, &self.layout_options_rules)
+            } else {
+                match &self.layout {
+                    Layout::Default(dl) => match self.layout_defaults_cache.get(dl) {
+                        Some(entry) => (entry.layout_options, &entry.layout_options_rules),
+                        None => (None, &[]),
+                    },
+                    Layout::Custom(_) => (None, &[]),
+                }
+            };
+
+        resolve_threshold_match(effective_rules, container_count).or(effective_base)
+    }
+
     pub fn hide(&mut self, omit: Option<isize>) {
         for window in self.floating_windows_mut().iter_mut().rev() {
             let mut should_hide = omit.is_none();
@@ -602,27 +696,7 @@ impl Workspace {
             } else if let Some(window) = &mut self.maximized_window {
                 window.maximize();
             } else if !self.containers().is_empty() {
-                // Compute effective layout options:
-                //   1. If layout_options_rules has a matching threshold (container_count >= threshold),
-                //      use the highest matching threshold's options (full replacement)
-                //   2. Otherwise, use the workspace base layout_options
-                let effective_layout_options = if !self.layout_options_rules.is_empty() {
-                    let container_count = self.containers().len();
-                    let mut matched = None;
-                    for (threshold, opts) in &self.layout_options_rules {
-                        if container_count >= *threshold {
-                            matched = Some(*opts);
-                        }
-                    }
-                    // If a rule matched, use it entirely (replaces base layout_options)
-                    if matched.is_some() {
-                        matched
-                    } else {
-                        self.layout_options
-                    }
-                } else {
-                    self.layout_options
-                };
+                let effective_layout_options = self.effective_layout_options();
 
                 tracing::debug!(
                     "Workspace '{}' update() - effective_layout_options: {:?} (base: {:?}, rules: {})",

schema.json

@@ -304,6 +304,16 @@
         "$ref": "#/$defs/MatchingRule"
       }
     },
+    "layout_defaults": {
+      "description": "Per-layout default options and rules, keyed by layout name.\nApplied as fallback when a workspace does not define its own layout_options or layout_options_rules.\nIf a workspace defines either setting, all global defaults for that layout are completely replaced.",
+      "type": [
+        "object",
+        "null"
+      ],
+      "additionalProperties": {
+        "$ref": "#/$defs/LayoutDefaultEntry"
+      }
+    },
     "manage_rules": {
       "description": "Individual window force-manage rules",
       "type": [
@@ -3290,6 +3300,36 @@
         "colours"
       ]
     },
+    "LayoutDefaultEntry": {
+      "description": "Per-layout default options entry for the `layout_defaults` global setting.\nContains both base layout options and threshold-based layout options rules.",
+      "type": "object",
+      "properties": {
+        "layout_options": {
+          "description": "Default layout options for this layout",
+          "anyOf": [
+            {
+              "$ref": "#/$defs/LayoutOptions"
+            },
+            {
+              "type": "null"
+            }
+          ]
+        },
+        "layout_options_rules": {
+          "description": "Threshold-based layout options rules in the format of threshold => options.\nWhen container count >= threshold, the highest matching threshold's options\nfully replace the base `layout_options`.",
+          "type": [
+            "object",
+            "null"
+          ],
+          "additionalProperties": false,
+          "patternProperties": {
+            "^\\d+$": {
+              "$ref": "#/$defs/LayoutOptions"
+            }
+          }
+        }
+      }
+    },
     "LayoutOptions": {
       "description": "Options for specific layouts",
       "type": "object",