From c693db2b9fa3539bab7ec2f84e7269ba98b0802e Mon Sep 17 00:00:00 2001
From: alosslessdev <alosslessdev@users.noreply.github.com>
Date: Fri, 23 Oct 2026 01:09:08 -0500
Subject: [PATCH 01/10] Conditional formatting: colour-scale editor and New
 Rule list (part of #1165)

New Formatting Rule offers Excel's six rule types. The colour-scale branch
edits per-stop type, value and colour, and Manage Rules edits a rule in place.

Formula rules refuse an empty or unparseable formula: the dialog keeps OK
disabled until a formula is typed, and the command rejects both an empty rule
and a formula that does not parse (#1999), so neither a rule that never applies
nor a workbook Excel cannot open is written.

Percent and percentile stops are clamped to 0-100, and an edit past the last
rule names home.manageRules and leaves no undo step.
---
 ROADMAP.md                               |   1 +
 crates/engine/src/cmd/insert.rs          | 421 ++++++++++++++++++-----
 crates/ui-egui/src/dialogs.rs            | 319 ++++++++++++++++-
 crates/ui-egui/src/i18n/cs.rs            |  25 ++
 crates/ui-egui/src/i18n/de.rs            |  24 ++
 crates/ui-egui/src/i18n/es.rs            |  24 ++
 crates/ui-egui/src/i18n/fr.rs            |  24 ++
 crates/ui-egui/src/i18n/ja.rs            |  21 ++
 crates/ui-egui/src/i18n/ko.rs            |  24 ++
 crates/ui-egui/src/i18n/pt.rs            |  22 ++
 crates/ui-egui/src/i18n/ru.rs            |  24 ++
 crates/ui-egui/src/i18n/sr.rs            |  24 ++
 crates/ui-egui/src/i18n/zh.rs            |  24 ++
 crates/ui-egui/src/ribbon.rs             |  34 +-
 crates/ui-egui/tests/color_scale_rule.rs | 249 ++++++++++++++
 docs/gaps.md                             |   1 +
 docs/target-app-parity.md                |   3 +-
 docs/ui-parity.md                        |   2 +
 18 files changed, 1178 insertions(+), 88 deletions(-)
 create mode 100644 crates/ui-egui/tests/color_scale_rule.rs

diff --git a/ROADMAP.md b/ROADMAP.md
index 48b3cf9bc7..8f7cf001b0 100644
--- a/ROADMAP.md
+++ b/ROADMAP.md
@@ -245,6 +245,7 @@ Ranked; estimates in Opus 5.5 agent-hours. Detail and the full beta-gate list in
 | 2026-10-20 | minor | Dutch (nl) listed under other shipped languages; progress log row |
 | 2026-10-19 | minor | Progress log: long flat operator chains (#916) |
 | 2026-10-19 | trivial | Progress log: desktop theme portal read timeout |
+| 2026-10-17 | minor | Conditional formatting: 2-/3-colour scale editor with per-stop type/value/colour, and in-place rule editing (part of #1165) |
 | 2026-10-16 | minor | Progress log: undo steps share picture and macro bytes |
 | 2026-10-16 | minor | Progress log: floating pictures' textures bounded and kept per workbook |
 | 2026-10-16 | trivial | Progress log: web preferences kept between visits (#1562) |
diff --git a/crates/engine/src/cmd/insert.rs b/crates/engine/src/cmd/insert.rs
index 9719bf451b..1634cf32b0 100644
--- a/crates/engine/src/cmd/insert.rs
+++ b/crates/engine/src/cmd/insert.rs
@@ -190,7 +190,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Conditional Formatting",
             ["Home", "Styles"],
             None,
-            "{range?, rule: {type: cellIs|expression|containsText|beginsWith|endsWith|blanks|noBlanks|errors|noErrors|duplicate|unique|top10|aboveAverage|timePeriod|colorScale|dataBar|iconSet, operator?, value?, value2?, formula?, text?, rank?, bottom?, percent?, below?, period?, colors?: [..], color?, set?, style?: {font?: {bold?, italic?, color?}, fill?: \"#FFC7CE\" | {pattern?, fg?, bg?}, borders?, num_fmt?} (colours \"#RRGGBB\") | preset?: lightRedFill|redText|yellowFill|greenFill|redBorder|lightRedFillDarkRedText…}; a text `value` is matched as text, or kept when already a quoted literal}",
+            "{range?, rule: {type: cellIs|expression|containsText|beginsWith|endsWith|blanks|noBlanks|errors|noErrors|duplicate|unique|top10|aboveAverage|timePeriod|colorScale|dataBar|iconSet, operator?, value?, value2?, formula?, text?, rank?, bottom?, percent?, below?, period?, colors?: [..], stops?: [{type: min|max|num|percent|percentile|formula, value?, color}], color?, set?, style?: {font?: {bold?, italic?, color?}, fill?: \"#FFC7CE\" | {pattern?, fg?, bg?}, borders?, num_fmt?} (colours \"#RRGGBB\") | preset?: lightRedFill|redText|yellowFill|greenFill|redBorder|lightRedFillDarkRedText…}; a text `value` is matched as text, or kept when already a quoted literal}",
             has_doc,
             add_cf
         ),
@@ -200,7 +200,7 @@ pub fn specs() -> Vec<CommandSpec> {
             "Manage Rules…",
             ["Home", "Styles", "Conditional Formatting"],
             None,
-            "{delete?: index, moveUp?: index, moveDown?: index}",
+            "{delete?: index, moveUp?: index, moveDown?: index, edit?: index, rule?: {...} (with edit)}",
             has_doc,
             manage_cf
         ),
@@ -1493,36 +1493,40 @@ fn cf_style_json(st: &Json) -> Result<Json> {
 fn check_cf_formula(cmd: &str, what: &str, formula: &str) -> Result<()> {
     // Strip exactly one leading '=', the way the XLSX writer does: a value like '===A1'
     // only parses after several strips and would still be saved unparseable. (#1999 review)
-    if gridcraft_formula::parse(formula.strip_prefix('=').unwrap_or(formula)).is_err() {
+    let parsed = formula.strip_prefix('=').unwrap_or(formula);
+    // A rule with no formula never applies; the dialog also keeps OK disabled for it.
+    if parsed.trim().is_empty() {
+        return Err(bad(cmd, format!("the {what} formula is empty")));
+    }
+    if gridcraft_formula::parse(parsed).is_err() {
         return Err(bad(cmd, format!("invalid {what} formula `{formula}` — it does not parse; Excel would reject the saved file")));
     }
     Ok(())
 }
 
-fn check_cf_value(what: &str, v: &gridcraft_model::features::CfValueKind) -> Result<()> {
+fn check_cf_value(cmd: &str, what: &str, v: &gridcraft_model::features::CfValueKind) -> Result<()> {
     if let gridcraft_model::features::CfValueKind::Formula(f) = v {
-        check_cf_formula("home.conditionalFormat", what, f)?;
+        check_cf_formula(cmd, what, f)?;
     }
     Ok(())
 }
 
-fn check_cf_rule(rule: &CfRule) -> Result<()> {
-    const CMD: &str = "home.conditionalFormat";
+fn check_cf_rule(cmd: &str, rule: &CfRule) -> Result<()> {
     match rule {
         CfRule::CellIs { a, b, .. } => {
-            check_cf_formula(CMD, "comparison value", a)?;
+            check_cf_formula(cmd, "comparison value", a)?;
             if let Some(b) = b {
-                check_cf_formula(CMD, "second comparison value", b)?;
+                check_cf_formula(cmd, "second comparison value", b)?;
             }
         }
-        CfRule::Expression { formula, .. } => check_cf_formula(CMD, "rule", formula)?,
+        CfRule::Expression { formula, .. } => check_cf_formula(cmd, "rule", formula)?,
         CfRule::DataBar { min, max, .. } => {
-            check_cf_value("data bar minimum", min)?;
-            check_cf_value("data bar maximum", max)?;
+            check_cf_value(cmd, "data bar minimum", min)?;
+            check_cf_value(cmd, "data bar maximum", max)?;
         }
         CfRule::ColorScale { stops } => {
             for (kind, _) in stops {
-                check_cf_value("color scale threshold", kind)?;
+                check_cf_value(cmd, "color scale threshold", kind)?;
             }
         }
         _ => {}
@@ -1530,41 +1534,50 @@ fn check_cf_rule(rule: &CfRule) -> Result<()> {
     Ok(())
 }
 
-fn add_cf(s: &mut Session, p: &Json) -> Result<Json> {
-    let ranges = target_ranges(s, p)?;
-    let sheet = target_sheet(s, p)?;
-    let Some(rule) = p.get("rule") else {
-        s.ui_requests.push(crate::UiRequest::Dialog("newFormattingRule".into(), json!({})));
-        return ok();
-    };
+fn cf_style(rule: &Json, cmd: &str) -> Result<Style> {
     let g = |k: &str| rule.get(k).and_then(Json::as_str).map(str::to_string);
-    let style = Box::new(match rule.get("style") {
+    match rule.get("style") {
         Some(st) if !st.is_null() => {
             let st = cf_style_json(st)?;
             let base = serde_json::to_value(Style::default()).map_err(|e| EngineError::Other(e.to_string()))?;
-            serde_json::from_value(super::format::merge_json(base, &st)).map_err(|e| bad("home.conditionalFormat", e.to_string()))?
+            Ok(serde_json::from_value(super::format::merge_json(base, &st)).map_err(|e| bad(cmd, e.to_string()))?)
         }
-        _ => preset_style(g("preset").as_deref().unwrap_or("lightRedFillDarkRedText")),
-    });
-    let kind = g("type").unwrap_or_else(|| "cellIs".into());
-    let value_kind = |v: Option<&Json>, default: CfValueKind| -> CfValueKind {
-        match v {
-            Some(Json::Object(o)) => {
-                let t = o.get("type").and_then(Json::as_str).unwrap_or("num");
-                let val = o.get("value").and_then(Json::as_f64).unwrap_or(0.0);
-                match t {
-                    "min" => CfValueKind::Min,
-                    "max" => CfValueKind::Max,
-                    "percent" => CfValueKind::Percent(val),
-                    "percentile" => CfValueKind::Percentile(val),
-                    "formula" => CfValueKind::Formula(o.get("value").and_then(Json::as_str).unwrap_or("").into()),
-                    _ => CfValueKind::Number(val),
+        _ => Ok(preset_style(g("preset").as_deref().unwrap_or("lightRedFillDarkRedText"))),
+    }
+}
+
+fn cf_value_kind(v: Option<&Json>, default: CfValueKind, cmd: &str) -> Result<CfValueKind> {
+    match v {
+        Some(Json::Object(o)) => {
+            let t = o.get("type").and_then(Json::as_str).unwrap_or("num");
+            let val = o.get("value").and_then(Json::as_f64).unwrap_or(0.0);
+            Ok(match t {
+                "min" => CfValueKind::Min,
+                "max" => CfValueKind::Max,
+                // The dialog clamps these to 0-100; engine callers get the same range.
+                "percent" => CfValueKind::Percent(val.clamp(0.0, 100.0)),
+                "percentile" => CfValueKind::Percentile(val.clamp(0.0, 100.0)),
+                "formula" => {
+                    let f = o.get("value").and_then(Json::as_str).unwrap_or("");
+                    if f.trim().is_empty() {
+                        return Err(bad(cmd, "a formula stop needs a formula"));
+                    }
+                    // Stored exactly: the evaluator takes the formula as written.
+                    CfValueKind::Formula(f.into())
                 }
-            }
-            _ => default,
+                "num" => CfValueKind::Number(val),
+                other => return Err(bad(cmd, format!("unknown stop type `{other}`"))),
+            })
         }
-    };
-    let rule = match kind.as_str() {
+        _ => Ok(default),
+    }
+}
+
+fn cf_rule(rule: &Json, cmd: &str) -> Result<CfRule> {
+    let g = |k: &str| rule.get(k).and_then(Json::as_str).map(str::to_string);
+    let style = Box::new(cf_style(rule, cmd)?);
+    let kind = g("type").unwrap_or_else(|| "cellIs".into());
+    match kind.as_str() {
         "cellIs" => {
             // Excel's file and VBA names (`lessThan`, …) are accepted too.
             let op = match g("operator").as_deref().unwrap_or("greater") {
@@ -1576,7 +1589,7 @@ fn add_cf(s: &mut Session, p: &Json) -> Result<Json> {
                 "greaterOrEqual" | "greaterThanOrEqual" => CfOperator::GreaterOrEqual,
                 "lessOrEqual" | "lessThanOrEqual" => CfOperator::LessOrEqual,
                 "greater" | "greaterThan" => CfOperator::Greater,
-                other => return Err(bad("home.conditionalFormat", format!("unknown operator `{other}`"))),
+                other => return Err(bad(cmd, format!("unknown operator `{other}`"))),
             };
             let a = rule.get("value").map(super::edit::json_to_input).unwrap_or_default();
             let b = rule.get("value2").map(super::edit::json_to_input);
@@ -1591,59 +1604,83 @@ fn add_cf(s: &mut Session, p: &Json) -> Result<Json> {
                     format!("\"{}\"", v.replace('"', "\"\""))
                 }
             };
-            CfRule::CellIs { op, a: quote(a), b: b.map(quote), style }
-        }
-        "expression" => CfRule::Expression { formula: g("formula").unwrap_or_default().trim_start_matches('=').to_string(), style },
-        "containsText" => CfRule::ContainsText { text: g("text").unwrap_or_default(), style },
-        "notContainsText" => CfRule::NotContainsText { text: g("text").unwrap_or_default(), style },
-        "beginsWith" => CfRule::BeginsWith { text: g("text").unwrap_or_default(), style },
-        "endsWith" => CfRule::EndsWith { text: g("text").unwrap_or_default(), style },
-        "blanks" => CfRule::Blanks { style },
-        "noBlanks" => CfRule::NoBlanks { style },
-        "errors" => CfRule::Errors { style },
-        "noErrors" => CfRule::NoErrors { style },
-        "duplicate" => CfRule::Duplicate { style },
-        "unique" => CfRule::Unique { style },
-        "top10" => CfRule::Top10 {
+            Ok(CfRule::CellIs { op, a: quote(a), b: b.map(quote), style })
+        }
+        "expression" => Ok(CfRule::Expression { formula: g("formula").unwrap_or_default().trim_start_matches('=').to_string(), style }),
+        "containsText" => Ok(CfRule::ContainsText { text: g("text").unwrap_or_default(), style }),
+        "notContainsText" => Ok(CfRule::NotContainsText { text: g("text").unwrap_or_default(), style }),
+        "beginsWith" => Ok(CfRule::BeginsWith { text: g("text").unwrap_or_default(), style }),
+        "endsWith" => Ok(CfRule::EndsWith { text: g("text").unwrap_or_default(), style }),
+        "blanks" => Ok(CfRule::Blanks { style }),
+        "noBlanks" => Ok(CfRule::NoBlanks { style }),
+        "errors" => Ok(CfRule::Errors { style }),
+        "noErrors" => Ok(CfRule::NoErrors { style }),
+        "duplicate" => Ok(CfRule::Duplicate { style }),
+        "unique" => Ok(CfRule::Unique { style }),
+        "top10" => Ok(CfRule::Top10 {
             bottom: rule.get("bottom").and_then(Json::as_bool).unwrap_or(false),
             percent: rule.get("percent").and_then(Json::as_bool).unwrap_or(false),
             rank: rule.get("rank").and_then(Json::as_u64).unwrap_or(10) as u32,
             style,
-        },
-        "aboveAverage" => CfRule::AboveAverage { below: rule.get("below").and_then(Json::as_bool).unwrap_or(false), equal: false, std_dev: 0, style },
-        "timePeriod" => CfRule::TimePeriod { period: g("period").unwrap_or_else(|| "today".into()), style },
+        }),
+        "aboveAverage" => {
+            Ok(CfRule::AboveAverage { below: rule.get("below").and_then(Json::as_bool).unwrap_or(false), equal: false, std_dev: 0, style })
+        }
+        "timePeriod" => Ok(CfRule::TimePeriod { period: g("period").unwrap_or_else(|| "today".into()), style }),
         "colorScale" => {
-            let cols: Vec<Color> = rule
-                .get("colors")
-                .and_then(Json::as_array)
-                .map(|a| a.iter().filter_map(|c| super::format::color_param(Some(c))).collect())
-                .unwrap_or_else(|| vec![Color::rgb(0xF8, 0x69, 0x6B), Color::rgb(0xFF, 0xEB, 0x84), Color::rgb(0x63, 0xBE, 0x7B)]);
-            let stops = match cols.len() {
-                2 => vec![(CfValueKind::Min, cols[0]), (CfValueKind::Max, cols[1])],
-                _ => vec![
-                    (CfValueKind::Min, cols.first().copied().unwrap_or_default()),
-                    (CfValueKind::Percentile(50.0), cols.get(1).copied().unwrap_or_default()),
-                    (CfValueKind::Max, cols.get(2).copied().unwrap_or_default()),
-                ],
+            let stops = if let Some(list) = rule.get("stops").and_then(Json::as_array) {
+                let mut out = Vec::with_capacity(list.len().min(3));
+                for stop in list {
+                    let color = super::format::color_param(stop.get("color")).ok_or_else(|| bad(cmd, "a colour-scale stop needs a colour"))?;
+                    out.push((cf_value_kind(Some(stop), CfValueKind::Min, cmd)?, color));
+                }
+                if !(2..=3).contains(&out.len()) {
+                    return Err(bad(cmd, "a colour scale needs two or three stops"));
+                }
+                out
+            } else {
+                let cols: Vec<Color> = rule
+                    .get("colors")
+                    .and_then(Json::as_array)
+                    .map(|a| a.iter().filter_map(|c| super::format::color_param(Some(c))).collect())
+                    .unwrap_or_else(|| vec![Color::rgb(0xF8, 0x69, 0x6B), Color::rgb(0xFF, 0xEB, 0x84), Color::rgb(0x63, 0xBE, 0x7B)]);
+                match cols.len() {
+                    2 => vec![(CfValueKind::Min, cols[0]), (CfValueKind::Max, cols[1])],
+                    _ => vec![
+                        (CfValueKind::Min, cols.first().copied().unwrap_or_default()),
+                        (CfValueKind::Percentile(50.0), cols.get(1).copied().unwrap_or_default()),
+                        (CfValueKind::Max, cols.get(2).copied().unwrap_or_default()),
+                    ],
+                }
             };
-            CfRule::ColorScale { stops }
+            Ok(CfRule::ColorScale { stops })
         }
-        "dataBar" => CfRule::DataBar {
-            min: value_kind(rule.get("min"), CfValueKind::Min),
-            max: value_kind(rule.get("max"), CfValueKind::Max),
+        "dataBar" => Ok(CfRule::DataBar {
+            min: cf_value_kind(rule.get("min"), CfValueKind::Min, cmd)?,
+            max: cf_value_kind(rule.get("max"), CfValueKind::Max, cmd)?,
             color: super::format::color_param(rule.get("color")).unwrap_or(Color::rgb(0x63, 0x8E, 0xC6)),
             gradient: rule.get("gradient").and_then(Json::as_bool).unwrap_or(true),
             show_value: true,
-        },
-        "iconSet" => CfRule::IconSet {
+        }),
+        "iconSet" => Ok(CfRule::IconSet {
             set: g("set").unwrap_or_else(|| "3TrafficLights1".into()),
             thresholds: vec![],
             reverse: rule.get("reverse").and_then(Json::as_bool).unwrap_or(false),
             show_value: true,
-        },
-        other => return Err(bad("home.conditionalFormat", format!("unknown rule type `{other}`"))),
+        }),
+        other => Err(bad(cmd, format!("unknown rule type `{other}`"))),
+    }
+}
+
+fn add_cf(s: &mut Session, p: &Json) -> Result<Json> {
+    let ranges = target_ranges(s, p)?;
+    let sheet = target_sheet(s, p)?;
+    let Some(rule) = p.get("rule") else {
+        s.ui_requests.push(crate::UiRequest::Dialog("newFormattingRule".into(), json!({})));
+        return ok();
     };
-    check_cf_rule(&rule)?;
+    let rule = cf_rule(rule, "home.conditionalFormat")?;
+    check_cf_rule("home.conditionalFormat", &rule)?;
     edit(s, |cx| {
         let sh = cx.sheet_mut(sheet)?;
         let priority = sh.cond_formats.iter().map(|c| c.priority).max().unwrap_or(0) + 1;
@@ -1677,17 +1714,30 @@ fn clear_cf(s: &mut Session, p: &Json) -> Result<Json> {
 
 fn manage_cf(s: &mut Session, p: &Json) -> Result<Json> {
     let sheet = target_sheet(s, p)?;
-    if p.get("delete").is_none() && p.get("moveUp").is_none() && p.get("moveDown").is_none() {
+    if p.get("delete").is_none() && p.get("moveUp").is_none() && p.get("moveDown").is_none() && p.get("edit").is_none() {
         let list: Vec<Json> = s
             .doc()?
             .wb
             .sheet(sheet)
             .map(|sh| {
-                sh.cond_formats.iter().map(|c| json!({"ranges": c.ranges.iter().map(|r| r.a1()).collect::<Vec<_>>(), "rule": c.rule})).collect()
+                sh.cond_formats
+                    .iter()
+                    .map(|c| json!({"ranges": c.ranges.iter().map(|r| r.a1()).collect::<Vec<_>>(), "rule": c.rule, "priority": c.priority}))
+                    .collect()
             })
             .unwrap_or_default();
         return Ok(json!({"rules": list}));
     }
+    let edited = match (p.get("edit"), p.get("rule")) {
+        (None, _) => None,
+        (Some(_), None) => return Err(bad("home.manageRules", "missing `rule` for an edit")),
+        (Some(e), Some(rule)) => {
+            let i = e.as_u64().ok_or_else(|| bad("home.manageRules", "`edit` must be a rule index"))?;
+            let rule = cf_rule(rule, "home.manageRules")?;
+            check_cf_rule("home.manageRules", &rule)?;
+            Some((i as usize, rule))
+        }
+    };
     edit(s, |cx| {
         let sh = cx.sheet_mut(sheet)?;
         // The count is taken again after each step: a delete shortens the list.
@@ -1696,6 +1746,10 @@ fn manage_cf(s: &mut Session, p: &Json) -> Result<Json> {
         {
             sh.cond_formats.remove(i);
         }
+        if let Some((i, rule)) = edited {
+            let cf = sh.cond_formats.get_mut(i).ok_or_else(|| bad("home.manageRules", format!("no conditional format at index {i}")))?;
+            cf.rule = rule;
+        }
         if let Some(i) = u32_param(p, "moveUp").map(|v| v as usize)
             && i > 0
             && i < sh.cond_formats.len()
@@ -1801,4 +1855,207 @@ mod tests {
         s.execute("table.rename", json!({"table": "Table1", "name": "Table1"})).unwrap();
         s.execute("table.rename", json!({"table": "Table1", "name": "Rates"})).unwrap();
     }
+
+    #[test]
+    fn colour_scale_thresholds_are_clamped_to_the_percent_range() {
+        let mut s = Session::new();
+        s.new_workbook();
+        s.execute(
+            "home.conditionalFormat",
+            json!({"range": "A1:A3", "rule": {"type": "colorScale", "stops": [
+                {"type": "percent", "value": -5, "color": "#112233"},
+                {"type": "percentile", "value": 150, "color": "#445566"},
+                {"type": "max", "color": "#778899"},
+            ]}}),
+        )
+        .unwrap();
+        let list = s.execute("home.manageRules", json!({})).unwrap();
+        let rule: CfRule = serde_json::from_value(list["rules"][0]["rule"].clone()).unwrap();
+        let CfRule::ColorScale { stops } = rule else { panic!("expected a colour scale") };
+        assert_eq!(
+            stops,
+            vec![
+                (CfValueKind::Percent(0.0), Color::Rgb(0x112233)),
+                (CfValueKind::Percentile(100.0), Color::Rgb(0x445566)),
+                (CfValueKind::Max, Color::Rgb(0x778899)),
+            ]
+        );
+    }
+
+    #[test]
+    fn colour_scale_stops_reject_empty_formulas_and_unknown_types() {
+        let mut s = Session::new();
+        s.new_workbook();
+        let with_stops = |stops: Json| json!({"range": "A1:A3", "rule": {"type": "colorScale", "stops": stops}});
+        let err = s
+            .execute(
+                "home.conditionalFormat",
+                with_stops(json!([
+                    {"type": "min", "color": "#112233"},
+                    {"type": "formula", "value": "  ", "color": "#445566"},
+                    {"type": "max", "color": "#778899"},
+                ])),
+            )
+            .unwrap_err()
+            .to_string();
+        assert!(err.contains("home.conditionalFormat"), "{err}");
+        assert!(err.contains("formula"), "{err}");
+
+        let err = s
+            .execute(
+                "home.conditionalFormat",
+                with_stops(json!([
+                    {"type": "min", "color": "#112233"},
+                    {"type": "median", "value": 50, "color": "#445566"},
+                    {"type": "max", "color": "#778899"},
+                ])),
+            )
+            .unwrap_err()
+            .to_string();
+        assert!(err.contains("unknown stop type `median`"), "{err}");
+        let rules = s.execute("home.manageRules", json!({})).unwrap();
+        assert_eq!(rules["rules"].as_array().map(Vec::len), Some(0));
+    }
+
+    #[test]
+    fn colour_scale_formulas_are_stored_verbatim() {
+        let mut s = Session::new();
+        s.new_workbook();
+        s.execute(
+            "home.conditionalFormat",
+            json!({"range": "A1:A3", "rule": {"type": "colorScale", "stops": [
+                {"type": "min", "color": "#112233"},
+                {"type": "formula", "value": "=$Z$1", "color": "#445566"},
+                {"type": "max", "color": "#778899"},
+            ]}}),
+        )
+        .unwrap();
+        let list = s.execute("home.manageRules", json!({})).unwrap();
+        let rule: CfRule = serde_json::from_value(list["rules"][0]["rule"].clone()).unwrap();
+        let CfRule::ColorScale { stops } = rule else { panic!("expected a colour scale") };
+        assert_eq!(stops[1].0, CfValueKind::Formula("=$Z$1".into()));
+    }
+
+    #[test]
+    fn manage_rules_rejects_a_non_index_edit() {
+        let mut s = Session::new();
+        s.new_workbook();
+        s.execute("home.conditionalFormat", json!({"range": "A1:A3", "rule": {"type": "colorScale", "colors": ["#112233", "#778899"]}})).unwrap();
+        for bad in [json!("0"), json!(1.5), json!(-1), json!(true)] {
+            let err = s
+                .execute("home.manageRules", json!({"edit": bad, "rule": {"type": "colorScale", "colors": ["#112233", "#778899"]}}))
+                .unwrap_err()
+                .to_string();
+            assert!(err.contains("`edit` must be a rule index"), "{err}");
+        }
+        let rules = s.execute("home.manageRules", json!({})).unwrap();
+        assert_eq!(rules["rules"].as_array().map(Vec::len), Some(1));
+    }
+
+    #[test]
+    fn manage_rules_rejects_an_edit_past_the_last_rule() {
+        let mut s = Session::new();
+        s.new_workbook();
+        s.execute("home.conditionalFormat", json!({"range": "A1:A3", "rule": {"type": "colorScale", "colors": ["#112233", "#778899"]}})).unwrap();
+        let err = s
+            .execute("home.manageRules", json!({"edit": 1, "rule": {"type": "colorScale", "colors": ["#112233", "#778899"]}}))
+            .unwrap_err()
+            .to_string();
+        assert!(err.contains("home.manageRules"), "{err}");
+        assert!(err.contains("index 1"), "{err}");
+        let rules = s.execute("home.manageRules", json!({})).unwrap();
+        assert_eq!(rules["rules"].as_array().map(Vec::len), Some(1), "the failed edit leaves the rule alone");
+    }
+
+    #[test]
+    fn manage_rules_names_itself_in_a_stop_count_error() {
+        let mut s = Session::new();
+        s.new_workbook();
+        let err = s
+            .execute(
+                "home.manageRules",
+                json!({"edit": 0, "rule": {"type": "colorScale", "stops": [
+                    {"type": "min", "color": "#112233"},
+                ]}}),
+            )
+            .unwrap_err()
+            .to_string();
+        assert!(err.contains("home.manageRules"), "{err}");
+    }
+
+    #[test]
+    fn a_formula_rule_needs_a_formula_that_parses() {
+        let mut s = Session::new();
+        s.new_workbook();
+        // An empty box used to create a rule that never applies.
+        let err =
+            s.execute("home.conditionalFormat", json!({"range": "A1:A3", "rule": {"type": "expression", "formula": ""}})).unwrap_err().to_string();
+        assert!(err.contains("formula is empty"), "{err}");
+        // `=C1>` used to be written as `<formula>C1&gt;</formula>`, which Excel refuses to open.
+        let err = s
+            .execute("home.conditionalFormat", json!({"range": "A1:A3", "rule": {"type": "expression", "formula": "=C1>"}}))
+            .unwrap_err()
+            .to_string();
+        assert!(err.contains("invalid"), "{err}");
+        assert!(err.contains("does not parse"), "{err}");
+        let rules = s.execute("home.manageRules", json!({})).unwrap();
+        assert_eq!(rules["rules"].as_array().map(Vec::len), Some(0), "a refused rule is not stored");
+    }
+
+    #[test]
+    fn an_invalid_formula_on_edit_leaves_the_rule_alone() {
+        let mut s = Session::new();
+        s.new_workbook();
+        s.execute("home.conditionalFormat", json!({"range": "A1:A3", "rule": {"type": "expression", "formula": "A1>2"}})).unwrap();
+        let err = s.execute("home.manageRules", json!({"edit": 0, "rule": {"type": "expression", "formula": "=C1>"}})).unwrap_err().to_string();
+        assert!(err.contains("home.manageRules"), "{err}");
+        let rule: CfRule = serde_json::from_value(s.execute("home.manageRules", json!({})).unwrap()["rules"][0]["rule"].clone()).unwrap();
+        let CfRule::Expression { formula, .. } = rule else { panic!("expected a formula rule, got {rule:?}") };
+        assert_eq!(formula, "A1>2");
+    }
+
+    #[test]
+    fn colour_scale_stops_keep_their_thresholds_and_can_be_edited() {
+        let mut s = Session::new();
+        s.new_workbook();
+        s.execute(
+            "home.conditionalFormat",
+            json!({"range": "A1:A3", "rule": {"type": "colorScale", "stops": [
+                {"type": "min", "color": "#112233"},
+                {"type": "num", "value": 5, "color": "#445566"},
+                {"type": "percentile", "value": 90, "color": "#778899"},
+            ]}}),
+        )
+        .unwrap();
+        let list = s.execute("home.manageRules", json!({})).unwrap();
+        let rule: CfRule = serde_json::from_value(list["rules"][0]["rule"].clone()).unwrap();
+        let stops = match rule {
+            CfRule::ColorScale { stops } => stops,
+            _ => Vec::new(),
+        };
+        assert_eq!(
+            stops,
+            vec![
+                (CfValueKind::Min, Color::Rgb(0x112233)),
+                (CfValueKind::Number(5.0), Color::Rgb(0x445566)),
+                (CfValueKind::Percentile(90.0), Color::Rgb(0x778899)),
+            ]
+        );
+
+        s.execute(
+            "home.manageRules",
+            json!({"edit": 0, "rule": {"type": "colorScale", "stops": [
+                {"type": "formula", "value": "$B$1", "color": "#ABCABC"},
+                {"type": "max", "color": "#DEFDEF"},
+            ]}}),
+        )
+        .unwrap();
+        let list = s.execute("home.manageRules", json!({})).unwrap();
+        let rule: CfRule = serde_json::from_value(list["rules"][0]["rule"].clone()).unwrap();
+        let stops = match rule {
+            CfRule::ColorScale { stops } => stops,
+            _ => Vec::new(),
+        };
+        assert_eq!(stops, vec![(CfValueKind::Formula("$B$1".into()), Color::Rgb(0xABCABC)), (CfValueKind::Max, Color::Rgb(0xDEFDEF))]);
+    }
 }
diff --git a/crates/ui-egui/src/dialogs.rs b/crates/ui-egui/src/dialogs.rs
index 46b9b0b2e1..5798c56caf 100644
--- a/crates/ui-egui/src/dialogs.rs
+++ b/crates/ui-egui/src/dialogs.rs
@@ -5,6 +5,7 @@
 //! `ui.dialog.set {field, value}` edits a field and `ui.dialog.confirm` presses OK.
 
 use egui::{Color32, Key, Sense, Stroke, StrokeKind, vec2};
+use gridcraft_engine::model::{CfRule, CfValueKind, Color as CellColor};
 
 use crate::icons::{self, Icon};
 use gridcraft_engine::core::{CellRef, RangeRef};
@@ -786,6 +787,12 @@ impl Dialog {
                 d.values.insert("operator".into(), p("operator"));
                 d
             }
+            "newFormattingRule" => {
+                let theme = app.session.active().map(|d| d.wb.theme.clone()).unwrap_or_default();
+                let mut d = Dialog::custom("newFormattingRule", "New Formatting Rule", new_rule_defaults(&params, &theme));
+                d.command = Some(if params.get("edit").is_some() { "home.manageRules" } else { "home.conditionalFormat" });
+                d
+            }
             "formatCells" => {
                 let mut d = Dialog::custom("formatCells", "Format Cells", json!({}));
                 d.tab = p("tab").as_str().unwrap_or("Number").to_string();
@@ -1230,6 +1237,24 @@ pub(crate) fn build_params(d: &Dialog) -> Json {
                 v["range"] = json!(pick.applies_to);
             }
         }
+        "newFormattingRule" => {
+            let mut out = match d.values.get("ruleType").and_then(Json::as_str).unwrap_or("allCells") {
+                "formula" => {
+                    let formula = d.values.get("formula").and_then(Json::as_str).unwrap_or("").to_string();
+                    let preset = d.values.get("preset").and_then(Json::as_str).unwrap_or("lightRedFillDarkRedText");
+                    json!({"rule": {"type": "expression", "formula": formula, "preset": preset}})
+                }
+                _ => {
+                    let stops: Vec<Json> =
+                        d.values.get("stops").and_then(Json::as_array).map(|a| a.iter().map(cf_stop_params).collect()).unwrap_or_default();
+                    json!({"rule": {"type": "colorScale", "stops": stops}})
+                }
+            };
+            if let Some(edit) = d.values.get("edit").and_then(Json::as_u64) {
+                out["edit"] = json!(edit);
+            }
+            v = out;
+        }
         "series" => {
             if let Some(s) = d.values.get("stop").and_then(Json::as_str).and_then(|s| s.parse::<f64>().ok()) {
                 v["stop"] = json!(s);
@@ -1263,7 +1288,7 @@ pub fn show(app: &mut SheetApp, ctx: &egui::Context) {
     let width = match d.name.as_str() {
         "formatCells" => 560.0,
         "about" => 660.0,
-        "insertFunction" | "commandSearch" | "nameManager" | "manageRules" | "journal" | "agents" | "macros" => 520.0,
+        "insertFunction" | "commandSearch" | "nameManager" | "manageRules" | "newFormattingRule" | "journal" | "agents" | "macros" => 520.0,
         "recommendedCharts" => 600.0,
         "analysisToolPak" => 420.0,
         "solver" => 460.0,
@@ -1299,6 +1324,7 @@ pub fn show(app: &mut SheetApp, ctx: &egui::Context) {
                 "nameManager" => name_manager(app, ui, &mut d, &mut open),
                 "pasteName" => paste_name(app, ui, &mut d, &mut confirm, &mut open),
                 "manageRules" => manage_rules(app, ui),
+                "newFormattingRule" => new_formatting_rule(ui, &mut d, &mut confirm, &mut open),
                 "recommendedCharts" => recommended_charts(app, ui, &mut d, &mut confirm, &mut open),
                 "selectData" => select_data(app, ui, &mut d, &mut confirm, &mut open),
                 "commandSearch" => command_search(app, ui, &mut d, &mut confirm),
@@ -1703,6 +1729,11 @@ fn paste_special_shortcuts(d: &mut Dialog, ctx: &egui::Context) {
 }
 
 fn ok_cancel(ui: &mut egui::Ui, confirm: &mut bool, open: &mut bool) {
+    ok_cancel_enabled(ui, confirm, open, true);
+}
+
+/// Like [`ok_cancel`], but OK (and Enter) do nothing while `enabled` is false.
+fn ok_cancel_enabled(ui: &mut egui::Ui, confirm: &mut bool, open: &mut bool, enabled: bool) {
     ui.add_space(8.0);
     // A row as tall as the buttons: a right-to-left layout straight in the window takes all the
     // height it is offered, which stretched every form dialog to the screen's height.
@@ -1710,14 +1741,17 @@ fn ok_cancel(ui: &mut egui::Ui, confirm: &mut bool, open: &mut bool) {
         ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
             let lang = crate::i18n::current(ui.ctx());
             let t = crate::theme::Tokens::get(ui.ctx());
-            let ok = ui.add(egui::Button::new(egui::RichText::new(format!("   {}   ", lang.tr("OK"))).color(t.on_accent)).fill(t.accent));
-            if ok.clicked() || ui.input(|i| i.key_pressed(Key::Enter)) {
+            let ok = ui.add_enabled(
+                enabled,
+                egui::Button::new(egui::RichText::new(format!("   {}   ", lang.tr("OK"))).color(t.on_accent)).fill(t.accent),
+            );
+            if enabled && (ok.clicked() || ui.input(|i| i.key_pressed(Key::Enter))) {
                 *confirm = true;
             }
             if ui.button(format!(" {} ", lang.tr("Cancel"))).clicked() {
                 *open = false;
             }
-        })
+        });
     });
 }
 
@@ -1931,6 +1965,280 @@ fn macros(app: &mut SheetApp, ui: &mut egui::Ui, d: &mut Dialog) {
     });
 }
 
+fn cf_stop_json(kind: CfValueKind, color: &CellColor, theme: &gridcraft_engine::model::Theme) -> Json {
+    let (ty, value) = match kind {
+        CfValueKind::Min => ("min", Json::Null),
+        CfValueKind::Max => ("max", Json::Null),
+        CfValueKind::Number(n) => ("num", json!(n)),
+        CfValueKind::Percent(n) => ("percent", json!(n)),
+        CfValueKind::Percentile(n) => ("percentile", json!(n)),
+        CfValueKind::Formula(f) => ("formula", json!(f)),
+    };
+    let hex = color.hex(theme).unwrap_or_else(|| "#000000".into());
+    // `source` keeps a theme colour by reference: OK without touching the picker sends it back
+    // unchanged, instead of freezing the theme's current RGB into the rule.
+    json!({"type": ty, "value": value, "color": hex.clone(), "source": color, "sourceHex": hex})
+}
+
+/// The stop as the engine takes it, dropping the dialog's bookkeeping. A colour the user did not
+/// change keeps its original theme reference; a changed one is sent as the picked RGB.
+fn cf_stop_params(stop: &Json) -> Json {
+    let mut obj = stop.as_object().cloned().unwrap_or_default();
+    let source = obj.remove("source").and_then(|v| serde_json::from_value::<CellColor>(v).ok());
+    let source_hex = obj.remove("sourceHex").and_then(|v| v.as_str().map(str::to_string));
+    if let (Some(source), Some(source_hex)) = (source, source_hex)
+        && obj.get("color").and_then(Json::as_str).is_some_and(|c| c.eq_ignore_ascii_case(&source_hex))
+    {
+        obj.insert(
+            "color".into(),
+            match source {
+                CellColor::Auto => json!("auto"),
+                CellColor::Rgb(v) => json!(format!("#{v:06X}")),
+                CellColor::Theme(i, tint) => json!({"theme": i, "tint": tint as f64 / 1000.0}),
+            },
+        );
+    }
+    Json::Object(obj)
+}
+
+fn default_scale_stops(style: &str) -> Vec<Json> {
+    if style == "2color" {
+        vec![json!({"type": "min", "value": null, "color": "#F8696B"}), json!({"type": "max", "value": null, "color": "#63BE7B"})]
+    } else {
+        vec![
+            json!({"type": "min", "value": null, "color": "#F8696B"}),
+            json!({"type": "percentile", "value": 50, "color": "#FFEB84"}),
+            json!({"type": "max", "value": null, "color": "#63BE7B"}),
+        ]
+    }
+}
+
+fn new_rule_defaults(params: &Json, theme: &gridcraft_engine::model::Theme) -> Json {
+    // Excel's New Formatting Rule opens on the first type. Manage Rules edits a colour scale,
+    // so an edit always stays on that branch.
+    let mut rule_type = params.get("ruleType").and_then(Json::as_str).unwrap_or("allCells").to_string();
+    if params.get("edit").is_some() || !matches!(rule_type.as_str(), "allCells" | "formula") {
+        rule_type = "allCells".into();
+    }
+    let mut style = params.get("style").and_then(Json::as_str).unwrap_or("3color").to_string();
+    if !matches!(style.as_str(), "2color" | "3color") {
+        style = "3color".into();
+    }
+    let existing = params.get("rule").and_then(|rule| serde_json::from_value::<CfRule>(rule.clone()).ok()).and_then(|rule| match rule {
+        CfRule::ColorScale { stops } if (2..=3).contains(&stops.len()) => {
+            Some(stops.into_iter().map(|(kind, color)| cf_stop_json(kind, &color, theme)).collect::<Vec<_>>())
+        }
+        _ => None,
+    });
+    let stops = match existing {
+        Some(stops) => {
+            style = if stops.len() == 2 { "2color".into() } else { "3color".into() };
+            stops
+        }
+        None => default_scale_stops(&style),
+    };
+    json!({
+        "ruleType": rule_type,
+        "style": style,
+        "stops": stops,
+        "formula": "",
+        "preset": "lightRedFillDarkRedText",
+        "edit": params.get("edit").cloned(),
+    })
+}
+
+fn parse_hex_color(s: &str) -> Color32 {
+    let h = s.trim_start_matches('#');
+    u32::from_str_radix(h.get(..6).unwrap_or("000000"), 16)
+        .map(|v| Color32::from_rgb((v >> 16) as u8, (v >> 8) as u8, v as u8))
+        .unwrap_or(Color32::WHITE)
+}
+
+fn hex_color(c: Color32) -> String {
+    format!("#{:02X}{:02X}{:02X}", c.r(), c.g(), c.b())
+}
+
+fn scale_preview(ui: &mut egui::Ui, stops: &[Json]) {
+    let (rect, _) = ui.allocate_exact_size(vec2(280.0, 26.0), Sense::hover());
+    let colors: Vec<Color32> = stops.iter().map(|s| parse_hex_color(s.get("color").and_then(Json::as_str).unwrap_or("#FFFFFF"))).collect();
+    if colors.is_empty() {
+        return;
+    }
+    let n = 64;
+    for i in 0..n {
+        let t = i as f32 / (n - 1) as f32;
+        let pos = t * (colors.len() - 1) as f32;
+        let lo = pos.floor() as usize;
+        let hi = (lo + 1).min(colors.len() - 1);
+        let f = pos - lo as f32;
+        let a = colors[lo];
+        let b = colors[hi];
+        let c = Color32::from_rgb(
+            (a.r() as f32 + (b.r() as f32 - a.r() as f32) * f) as u8,
+            (a.g() as f32 + (b.g() as f32 - a.g() as f32) * f) as u8,
+            (a.b() as f32 + (b.b() as f32 - a.b() as f32) * f) as u8,
+        );
+        let x = rect.left() + rect.width() * i as f32 / n as f32;
+        ui.painter().rect_filled(egui::Rect::from_min_size(egui::pos2(x, rect.top()), vec2(rect.width() / n as f32 + 0.5, rect.height())), 0.0, c);
+    }
+    ui.painter().rect_stroke(rect, 0.0, Stroke::new(1.0, Color32::from_gray(190)), StrokeKind::Inside);
+}
+
+fn stop_combo(ui: &mut egui::Ui, id: (&'static str, usize), current: &mut String, options: &[(&str, &str)], lang: crate::i18n::Language) {
+    let shown = options.iter().find(|(v, _)| *v == current).map(|(_, l)| lang.tr(l)).unwrap_or(current.as_str());
+    egui::ComboBox::from_id_salt(id).selected_text(shown).width(120.0).show_ui(ui, |ui| {
+        for (v, l) in options {
+            if ui.selectable_label(current == v, lang.tr(l)).clicked() {
+                *current = (*v).to_string();
+            }
+        }
+    });
+}
+
+fn colour_scale_editor(ui: &mut egui::Ui, d: &mut Dialog, lang: crate::i18n::Language) {
+    ui.label(lang.tr("Format all cells based on their values"));
+    ui.horizontal(|ui| {
+        ui.label(lang.tr("Format Style:"));
+        let mut style = d.values.get("style").and_then(Json::as_str).unwrap_or("3color").to_string();
+        egui::ComboBox::from_id_salt("newFormattingRule.style")
+            .selected_text(lang.tr(if style == "2color" { "2-Color Scale" } else { "3-Color Scale" }))
+            .width(150.0)
+            .show_ui(ui, |ui| {
+                for (v, l) in [("2color", "2-Color Scale"), ("3color", "3-Color Scale")] {
+                    if ui.selectable_label(style == v, lang.tr(l)).clicked() {
+                        style = v.to_string();
+                    }
+                }
+            });
+        d.values.insert("style".into(), json!(style));
+        let mut stops = d.values.get("stops").and_then(Json::as_array).cloned().unwrap_or_default();
+        if style == "2color" && stops.len() == 3 {
+            stops.remove(1);
+        } else if style == "3color" && stops.len() == 2 {
+            stops.insert(1, json!({"type": "percentile", "value": 50, "color": "#FFEB84"}));
+        }
+        d.values.insert("stops".into(), Json::Array(stops));
+    });
+    let mut stops = d.values.get("stops").and_then(Json::as_array).cloned().unwrap_or_default();
+    let count = stops.len();
+    for i in 0..count {
+        let mut obj = stops.get(i).and_then(Json::as_object).cloned().unwrap_or_default();
+        let mut ty = obj.get("type").and_then(Json::as_str).unwrap_or("num").to_string();
+        let options: &[(&str, &str)] = if i == 0 {
+            &[("min", "Lowest value"), ("num", "Number"), ("percent", "Percent"), ("percentile", "Percentile"), ("formula", "Formula")]
+        } else if i + 1 == count {
+            &[("max", "Highest value"), ("num", "Number"), ("percent", "Percent"), ("percentile", "Percentile"), ("formula", "Formula")]
+        } else {
+            &[("num", "Number"), ("percent", "Percent"), ("percentile", "Percentile"), ("formula", "Formula")]
+        };
+        ui.horizontal(|ui| {
+            ui.label(lang.tr(if i == 0 {
+                "Minimum"
+            } else if i + 1 == count {
+                "Maximum"
+            } else {
+                "Midpoint"
+            }));
+            stop_combo(ui, ("newFormattingRule.stopType", i), &mut ty, options, lang);
+            match ty.as_str() {
+                "min" | "max" => {
+                    ui.label(lang.tr(if ty == "min" { "Lowest value" } else { "Highest value" }));
+                }
+                "formula" => {
+                    let mut f = obj.get("value").and_then(Json::as_str).unwrap_or("").to_string();
+                    if ui.add(egui::TextEdit::singleline(&mut f).desired_width(120.0).hint_text(lang.tr("Formula"))).changed() {
+                        obj.insert("value".into(), json!(f));
+                    }
+                }
+                _ => {
+                    let mut n = obj.get("value").and_then(Json::as_f64).unwrap_or(0.0);
+                    let speed = if ty == "num" { 1.0 } else { 0.1 };
+                    if ui.add(egui::DragValue::new(&mut n).speed(speed).range(if ty == "num" { f64::MIN..=f64::MAX } else { 0.0..=100.0 })).changed()
+                    {
+                        obj.insert("value".into(), json!(n));
+                    }
+                }
+            }
+            let c = parse_hex_color(obj.get("color").and_then(Json::as_str).unwrap_or("#FFFFFF"));
+            let mut rgb = [c.r(), c.g(), c.b()];
+            if ui.color_edit_button_srgb(&mut rgb).changed() {
+                obj.insert("color".into(), json!(hex_color(Color32::from_rgb(rgb[0], rgb[1], rgb[2]))));
+            }
+        });
+        obj.insert("type".into(), json!(ty));
+        stops[i] = Json::Object(obj);
+    }
+    d.values.insert("stops".into(), Json::Array(stops.clone()));
+    scale_preview(ui, &stops);
+}
+
+fn preset_combo(ui: &mut egui::Ui, d: &mut Dialog, lang: crate::i18n::Language) {
+    const PRESETS: &[(&str, &str)] = &[
+        ("lightRedFillDarkRedText", "Light Red Fill with Dark Red Text"),
+        ("yellowFillDarkYellowText", "Yellow Fill with Dark Yellow Text"),
+        ("greenFillDarkGreenText", "Green Fill with Dark Green Text"),
+        ("lightRedFill", "Light Red Fill"),
+        ("redText", "Red Text"),
+        ("redBorder", "Red Border"),
+    ];
+    let mut preset = d.values.get("preset").and_then(Json::as_str).unwrap_or("lightRedFillDarkRedText").to_string();
+    let shown = PRESETS.iter().find(|(v, _)| *v == preset).map(|(_, l)| lang.tr(l)).unwrap_or(preset.as_str());
+    egui::ComboBox::from_id_salt("newFormattingRule.preset").selected_text(shown).width(260.0).show_ui(ui, |ui| {
+        for (v, l) in PRESETS {
+            if ui.selectable_label(preset == *v, lang.tr(l)).clicked() {
+                preset = (*v).to_string();
+            }
+        }
+    });
+    d.values.insert("preset".into(), json!(preset));
+}
+
+/// Excel's six rule types, in its order.
+const RULE_TYPES: &[(&str, &str)] = &[
+    ("allCells", "Format all cells based on their values"),
+    ("cellsThatContain", "Format only cells that contain"),
+    ("topBottom", "Format only top or bottom ranked values"),
+    ("aboveBelow", "Format only values that are above or below average"),
+    ("uniqueDuplicate", "Format only unique or duplicate values"),
+    ("formula", "Use a formula to determine which cells to format"),
+];
+
+fn new_formatting_rule(ui: &mut egui::Ui, d: &mut Dialog, confirm: &mut bool, open: &mut bool) {
+    let lang = crate::i18n::current(ui.ctx());
+    ui.label(lang.tr("Select a Rule Type"));
+    let mut rule_type = d.values.get("ruleType").and_then(Json::as_str).unwrap_or("allCells").to_string();
+    for (v, label) in RULE_TYPES {
+        ui.selectable_value(&mut rule_type, (*v).to_string(), lang.tr(label));
+    }
+    d.values.insert("ruleType".into(), json!(rule_type));
+    ui.separator();
+    ui.label(lang.tr("Edit the Rule Description"));
+    let supported = match rule_type.as_str() {
+        "allCells" => {
+            colour_scale_editor(ui, d, lang);
+            true
+        }
+        "formula" => {
+            ui.label(lang.tr("Format values where this formula is true:"));
+            let mut formula = d.values.get("formula").and_then(Json::as_str).unwrap_or("").to_string();
+            if ui.add(egui::TextEdit::singleline(&mut formula).desired_width(360.0)).changed() {
+                d.values.insert("formula".into(), json!(formula.clone()));
+            }
+            ui.horizontal(|ui| {
+                ui.label(lang.tr("with"));
+                preset_combo(ui, d, lang);
+            });
+            // A formula rule with no formula never applies; OK waits for one.
+            !formula.trim().is_empty()
+        }
+        _ => {
+            ui.label(lang.tr("This rule type isn't available yet."));
+            false
+        }
+    };
+    ok_cancel_enabled(ui, confirm, open, supported);
+}
+
 /// Draws the six-tab Format Cells editor (number, alignment, font, border, fill, protection); the Number tab shows a sample preview, and the style draft updates.
 fn format_cells(app: &mut SheetApp, ui: &mut egui::Ui, d: &mut Dialog, confirm: &mut bool) {
     // `d.tab` stays the English name (it is what `open_dialog` and tests pass); only the drawn
@@ -2844,6 +3152,9 @@ fn manage_rules(app: &mut SheetApp, ui: &mut egui::Ui) {
                 i + 1,
                 r["ranges"].as_array().map(|a| a.iter().filter_map(|x| x.as_str()).collect::<Vec<_>>().join(",")).unwrap_or_default()
             ));
+            if kind.contains("ColorScale") && ui.small_button("Edit").clicked() {
+                app.open_dialog("newFormattingRule", json!({"edit": i, "rule": r["rule"].clone()}));
+            }
             if ui.small_button("▲").clicked() {
                 app.run_or_alert("home.manageRules", json!({"moveUp": i}));
             }
diff --git a/crates/ui-egui/src/i18n/cs.rs b/crates/ui-egui/src/i18n/cs.rs
index e24dad5e1a..2813c6414d 100644
--- a/crates/ui-egui/src/i18n/cs.rs
+++ b/crates/ui-egui/src/i18n/cs.rs
@@ -545,6 +545,31 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Previous sheet" => "Předchozí list",
         "Zoom In" => "Přiblížit",
         "Zoom Out" => "Oddálit",
+        // Conditional formatting: colour scales.
+        "New Formatting Rule" => "Nové pravidlo formátování",
+        "Format all cells based on their values" => "Formátovat všechny buňky podle jejich hodnot",
+        "Format Style:" => "Styl formátu:",
+        "2-Color Scale" => "Dvoubarevná škála",
+        "3-Color Scale" => "Tříbarevná škála",
+        "Lowest value" => "Nejnižší hodnota",
+        "Highest value" => "Nejvyšší hodnota",
+        "Percent" => "Procento",
+        "Percentile" => "Percentil",
+        "Formula" => "Vzorec",
+        "Minimum" => "Minimum",
+        "Maximum" => "Maximum",
+        "Midpoint" => "Střední bod",
+        "More Rules…" => "Další pravidla…",
+        "Select a Rule Type" => "Vybrat typ pravidla",
+        "Edit the Rule Description" => "Upravit popis pravidla",
+        "Format only cells that contain" => "Formátovat pouze buňky, které obsahují",
+        "Format only top or bottom ranked values" => "Formátovat pouze hodnoty s nejvyšším nebo nejnižším pořadím",
+        "Format only values that are above or below average" => "Formátovat pouze hodnoty nad nebo pod průměrem",
+        "Format only unique or duplicate values" => "Formátovat pouze jedinečné nebo duplicitní hodnoty",
+        "Use a formula to determine which cells to format" => "Pomocí vzorce určit, které buňky se mají formátovat",
+        "Format values where this formula is true:" => "Formátovat hodnoty, pro které platí tento vzorec:",
+        "with" => "s",
+        "This rule type isn't available yet." => "Tento typ pravidla zatím není dostupný.",
         // widgets.rs (alphabetical keys).
         "Dismiss" => "Zavřít",
         "Rename" => "Přejmenovat",
diff --git a/crates/ui-egui/src/i18n/de.rs b/crates/ui-egui/src/i18n/de.rs
index 218eceb437..b62eba24dd 100644
--- a/crates/ui-egui/src/i18n/de.rs
+++ b/crates/ui-egui/src/i18n/de.rs
@@ -462,6 +462,30 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "All sheets" => "Alle Blätter",
         "New sheet (⇧F11)" => "Neues Blatt (⇧F11)",
         "Text Box" => "Textfeld",
+        "New Formatting Rule" => "Neue Formatierungsregel",
+        "Format all cells based on their values" => "Alle Zellen basierend auf ihren Werten formatieren",
+        "Format Style:" => "Formatvorlage:",
+        "2-Color Scale" => "2-Farben-Skala",
+        "3-Color Scale" => "3-Farben-Skala",
+        "Lowest value" => "Niedrigster Wert",
+        "Highest value" => "Höchster Wert",
+        "Percent" => "Prozent",
+        "Percentile" => "Perzentil",
+        "Formula" => "Formel",
+        "Minimum" => "Minimum",
+        "Maximum" => "Maximum",
+        "Midpoint" => "Mittelpunkt",
+        "More Rules…" => "Weitere Regeln…",
+        "Select a Rule Type" => "Regeltyp auswählen",
+        "Edit the Rule Description" => "Regelbeschreibung bearbeiten",
+        "Format only cells that contain" => "Nur Zellen formatieren, die enthalten",
+        "Format only top or bottom ranked values" => "Nur Werte formatieren, die oben oder unten eingestuft sind",
+        "Format only values that are above or below average" => "Nur Werte formatieren, die über oder unter dem Durchschnitt liegen",
+        "Format only unique or duplicate values" => "Nur eindeutige oder doppelte Werte formatieren",
+        "Use a formula to determine which cells to format" => "Formel zur Ermittlung der zu formatierenden Zellen verwenden",
+        "Format values where this formula is true:" => "Werte formatieren, für die diese Formel wahr ist:",
+        "with" => "mit",
+        "This rule type isn't available yet." => "Dieser Regeltyp ist noch nicht verfügbar.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/es.rs b/crates/ui-egui/src/i18n/es.rs
index ab1fa1276a..106b2a1b75 100644
--- a/crates/ui-egui/src/i18n/es.rs
+++ b/crates/ui-egui/src/i18n/es.rs
@@ -478,6 +478,30 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "All sheets" => "Todas las hojas",
         "New sheet (⇧F11)" => "Nueva hoja (⇧F11)",
         "Text Box" => "Cuadro de texto",
+        "New Formatting Rule" => "Nueva regla de formato",
+        "Format all cells based on their values" => "Dar formato a todas las celdas según sus valores",
+        "Format Style:" => "Estilo de formato:",
+        "2-Color Scale" => "Escala de 2 colores",
+        "3-Color Scale" => "Escala de 3 colores",
+        "Lowest value" => "Valor mínimo",
+        "Highest value" => "Valor máximo",
+        "Percent" => "Porcentaje",
+        "Percentile" => "Percentil",
+        "Formula" => "Fórmula",
+        "Minimum" => "Mínimo",
+        "Maximum" => "Máximo",
+        "Midpoint" => "Punto medio",
+        "More Rules…" => "Más reglas…",
+        "Select a Rule Type" => "Seleccionar un tipo de regla",
+        "Edit the Rule Description" => "Editar la descripción de la regla",
+        "Format only cells that contain" => "Dar formato solo a las celdas que contengan",
+        "Format only top or bottom ranked values" => "Dar formato solo a los valores con clasificación superior o inferior",
+        "Format only values that are above or below average" => "Dar formato solo a los valores que estén por encima o por debajo del promedio",
+        "Format only unique or duplicate values" => "Dar formato solo a los valores únicos o duplicados",
+        "Use a formula to determine which cells to format" => "Usar una fórmula para determinar qué celdas se van a aplicar formato",
+        "Format values where this formula is true:" => "Dar formato a los valores donde esta fórmula sea verdadera:",
+        "with" => "con",
+        "This rule type isn't available yet." => "Este tipo de regla aún no está disponible.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/fr.rs b/crates/ui-egui/src/i18n/fr.rs
index 34511876a9..9285a2917f 100644
--- a/crates/ui-egui/src/i18n/fr.rs
+++ b/crates/ui-egui/src/i18n/fr.rs
@@ -450,6 +450,30 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "All sheets" => "Toutes les feuilles",
         "New sheet (⇧F11)" => "Nouvelle feuille (⇧F11)",
         "Text Box" => "Zone de texte",
+        "New Formatting Rule" => "Nouvelle règle de mise en forme",
+        "Format all cells based on their values" => "Mettre en forme toutes les cellules en fonction de leurs valeurs",
+        "Format Style:" => "Style de mise en forme :",
+        "2-Color Scale" => "Échelle à 2 couleurs",
+        "3-Color Scale" => "Échelle à 3 couleurs",
+        "Lowest value" => "Valeur la plus basse",
+        "Highest value" => "Valeur la plus haute",
+        "Percent" => "Pourcentage",
+        "Percentile" => "Centile",
+        "Formula" => "Formule",
+        "Minimum" => "Minimum",
+        "Maximum" => "Maximum",
+        "Midpoint" => "Point milieu",
+        "More Rules…" => "Autres règles…",
+        "Select a Rule Type" => "Sélectionner un type de règle",
+        "Edit the Rule Description" => "Modifier la description de la règle",
+        "Format only cells that contain" => "Mettre en forme uniquement les cellules qui contiennent",
+        "Format only top or bottom ranked values" => "Mettre en forme uniquement les valeurs classées en haut ou en bas",
+        "Format only values that are above or below average" => "Mettre en forme uniquement les valeurs supérieures ou inférieures à la moyenne",
+        "Format only unique or duplicate values" => "Mettre en forme uniquement les valeurs uniques ou en double",
+        "Use a formula to determine which cells to format" => "Utiliser une formule pour déterminer pour quelles cellules le format sera appliqué",
+        "Format values where this formula is true:" => "Mettre en forme les valeurs pour lesquelles cette formule est vraie :",
+        "with" => "avec",
+        "This rule type isn't available yet." => "Ce type de règle n'est pas encore disponible.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/ja.rs b/crates/ui-egui/src/i18n/ja.rs
index ea48f80744..da54c59cd6 100644
--- a/crates/ui-egui/src/i18n/ja.rs
+++ b/crates/ui-egui/src/i18n/ja.rs
@@ -990,6 +990,27 @@ pub(super) const DIALOGS: &[(&str, &str)] = &[
     ("Tab Color", "シートの見出しの色"),
     ("Unhide…", "再表示…"),
     ("Unprotect Sheet…", "シート保護の解除…"),
+    ("New Formatting Rule", "新しい書式ルール"),
+    ("Format all cells based on their values", "値に基づいてすべてのセルを書式設定"),
+    ("Format Style:", "書式スタイル:"),
+    ("2-Color Scale", "2 色スケール"),
+    ("3-Color Scale", "3 色スケール"),
+    ("Lowest value", "最小値"),
+    ("Highest value", "最大値"),
+    ("Percentile", "パーセンタイル"),
+    ("Formula", "数式"),
+    ("Minimum", "最小"),
+    ("Maximum", "最大"),
+    ("Midpoint", "中間"),
+    ("More Rules…", "その他のルール…"),
+    ("Select a Rule Type", "ルールの種類を選択"),
+    ("Edit the Rule Description", "ルールの説明を編集"),
+    ("Format only cells that contain", "含むセルのみを書式設定"),
+    ("Format only top or bottom ranked values", "上位または下位に入る値のみを書式設定"),
+    ("Format only values that are above or below average", "平均より上または下の値のみを書式設定"),
+    ("Format only unique or duplicate values", "重複する値または一意の値のみを書式設定"),
+    ("Use a formula to determine which cells to format", "数式を使用して、書式設定するセルを決定"),
+    ("This rule type isn't available yet.", "このルールの種類はまだ使用できません。"),
 ];
 
 /// Labels of the ribbon menus, pop-ups and palettes that the reference catalog does not cover (the
diff --git a/crates/ui-egui/src/i18n/ko.rs b/crates/ui-egui/src/i18n/ko.rs
index 936e7417c0..2c3fb7de5e 100644
--- a/crates/ui-egui/src/i18n/ko.rs
+++ b/crates/ui-egui/src/i18n/ko.rs
@@ -446,6 +446,30 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "All sheets" => "모든 시트",
         "New sheet (⇧F11)" => "새 시트 (⇧F11)",
         "Text Box" => "텍스트 상자",
+        "New Formatting Rule" => "새 서식 규칙",
+        "Format all cells based on their values" => "해당 값에 따라 모든 셀의 서식 지정",
+        "Format Style:" => "서식 스타일:",
+        "2-Color Scale" => "2색조 눈금",
+        "3-Color Scale" => "3색조 눈금",
+        "Lowest value" => "최저값",
+        "Highest value" => "최고값",
+        "Percent" => "백분율",
+        "Percentile" => "백분위수",
+        "Formula" => "수식",
+        "Minimum" => "최소",
+        "Maximum" => "최대",
+        "Midpoint" => "중간점",
+        "More Rules…" => "기타 규칙…",
+        "Select a Rule Type" => "규칙 유형 선택",
+        "Edit the Rule Description" => "규칙 설명 편집",
+        "Format only cells that contain" => "다음을 포함하는 셀만 서식 지정",
+        "Format only top or bottom ranked values" => "순위가 위 또는 아래인 값만 서식 지정",
+        "Format only values that are above or below average" => "평균보다 높거나 낮은 값만 서식 지정",
+        "Format only unique or duplicate values" => "고유하거나 중복되는 값만 서식 지정",
+        "Use a formula to determine which cells to format" => "수식을 사용하여 서식을 지정할 셀 결정",
+        "Format values where this formula is true:" => "다음 수식을 만족하는 값에 서식 지정:",
+        "with" => "서식:",
+        "This rule type isn't available yet." => "이 규칙 유형은 아직 사용할 수 없습니다.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/pt.rs b/crates/ui-egui/src/i18n/pt.rs
index d72ee2460a..1b9bef4148 100644
--- a/crates/ui-egui/src/i18n/pt.rs
+++ b/crates/ui-egui/src/i18n/pt.rs
@@ -982,6 +982,28 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
             "Salvamento automático: salvar após cada alteração (pastas de trabalho salvas em um arquivo)"
         }
         "All sheets" => "Todas as planilhas",
+        "New Formatting Rule" => "Nova Regra de Formatação",
+        "Format all cells based on their values" => "Formatar todas as células com base em seus valores",
+        "Format Style:" => "Estilo de Formatação:",
+        "2-Color Scale" => "Escala de 2 Cores",
+        "3-Color Scale" => "Escala de 3 Cores",
+        "Lowest value" => "Valor mais baixo",
+        "Highest value" => "Valor mais alto",
+        "Percent" => "Porcentagem",
+        "Percentile" => "Percentil",
+        "Formula" => "Fórmula",
+        "Minimum" => "Mínimo",
+        "Maximum" => "Máximo",
+        "Midpoint" => "Ponto Médio",
+        "More Rules…" => "Mais Regras…",
+        "Select a Rule Type" => "Selecionar um Tipo de Regra",
+        "Edit the Rule Description" => "Editar a Descrição da Regra",
+        "Format only cells that contain" => "Formatar apenas células que contenham",
+        "Format only top or bottom ranked values" => "Formatar apenas valores classificados acima ou abaixo",
+        "Format only values that are above or below average" => "Formatar apenas valores acima ou abaixo da média",
+        "Format only unique or duplicate values" => "Formatar apenas valores exclusivos ou duplicados",
+        "Use a formula to determine which cells to format" => "Usar uma fórmula para determinar quais células devem ser formatadas",
+        "This rule type isn't available yet." => "Este tipo de regra ainda não está disponível.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/ru.rs b/crates/ui-egui/src/i18n/ru.rs
index e3ae28581d..153b928555 100644
--- a/crates/ui-egui/src/i18n/ru.rs
+++ b/crates/ui-egui/src/i18n/ru.rs
@@ -448,6 +448,30 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "All sheets" => "Все листы",
         "New sheet (⇧F11)" => "Новый лист (⇧F11)",
         "Text Box" => "Надпись",
+        "New Formatting Rule" => "Новое правило форматирования",
+        "Format all cells based on their values" => "Форматировать все ячейки на основе их значений",
+        "Format Style:" => "Стиль формата:",
+        "2-Color Scale" => "Двухцветная шкала",
+        "3-Color Scale" => "Трехцветная шкала",
+        "Lowest value" => "Наименьшее значение",
+        "Highest value" => "Наибольшее значение",
+        "Percent" => "Процент",
+        "Percentile" => "Процентиль",
+        "Formula" => "Формула",
+        "Minimum" => "Минимум",
+        "Maximum" => "Максимум",
+        "Midpoint" => "Средняя точка",
+        "More Rules…" => "Другие правила…",
+        "Select a Rule Type" => "Выбор типа правила",
+        "Edit the Rule Description" => "Изменение описания правила",
+        "Format only cells that contain" => "Форматировать только ячейки, которые содержат",
+        "Format only top or bottom ranked values" => "Форматировать только значения, имеющие верхний или нижний рейтинг",
+        "Format only values that are above or below average" => "Форматировать только значения выше или ниже среднего",
+        "Format only unique or duplicate values" => "Форматировать только уникальные или повторяющиеся значения",
+        "Use a formula to determine which cells to format" => "Использовать формулу для определения форматируемых ячеек",
+        "Format values where this formula is true:" => "Форматировать значения, для которых следующая формула является истинной:",
+        "with" => "с форматом",
+        "This rule type isn't available yet." => "Этот тип правила пока недоступен.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/sr.rs b/crates/ui-egui/src/i18n/sr.rs
index db75b63c25..6cc66b5099 100644
--- a/crates/ui-egui/src/i18n/sr.rs
+++ b/crates/ui-egui/src/i18n/sr.rs
@@ -446,6 +446,30 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "All sheets" => "Сви листови",
         "New sheet (⇧F11)" => "Нови лист (⇧F11)",
         "Text Box" => "Текстуално поље",
+        "New Formatting Rule" => "Novo pravilo oblikovanja",
+        "Format all cells based on their values" => "Oblikuj sve ćelije na osnovu njihovih vrednosti",
+        "Format Style:" => "Stil oblikovanja:",
+        "2-Color Scale" => "Dvobojna skala",
+        "3-Color Scale" => "Trobojna skala",
+        "Lowest value" => "Najniža vrednost",
+        "Highest value" => "Najviša vrednost",
+        "Percent" => "Procenat",
+        "Percentile" => "Percentil",
+        "Formula" => "Formula",
+        "Minimum" => "Minimum",
+        "Maximum" => "Maksimum",
+        "Midpoint" => "Srednja tačka",
+        "More Rules…" => "Druga pravila…",
+        "Select a Rule Type" => "Izaberi tip pravila",
+        "Edit the Rule Description" => "Uredi opis pravila",
+        "Format only cells that contain" => "Oblikuj samo ćelije koje sadrže",
+        "Format only top or bottom ranked values" => "Oblikuj samo vrednosti rangirane na vrhu ili dnu",
+        "Format only values that are above or below average" => "Oblikuj samo vrednosti iznad ili ispod proseka",
+        "Format only unique or duplicate values" => "Oblikuj samo jedinstvene ili duplikatne vrednosti",
+        "Use a formula to determine which cells to format" => "Koristi formulu za određivanje ćelija koje se oblikuju",
+        "Format values where this formula is true:" => "Oblikuj vrednosti za koje je ova formula tačna:",
+        "with" => "sa",
+        "This rule type isn't available yet." => "Ovaj tip pravila još nije dostupan.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/zh.rs b/crates/ui-egui/src/i18n/zh.rs
index 9ce01e39d8..eb72544016 100644
--- a/crates/ui-egui/src/i18n/zh.rs
+++ b/crates/ui-egui/src/i18n/zh.rs
@@ -438,6 +438,30 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "All sheets" => "所有工作表",
         "New sheet (⇧F11)" => "新建工作表 (⇧F11)",
         "Text Box" => "文本框",
+        "New Formatting Rule" => "新建格式规则",
+        "Format all cells based on their values" => "基于各自值设置所有单元格的格式",
+        "Format Style:" => "格式样式:",
+        "2-Color Scale" => "双色刻度",
+        "3-Color Scale" => "三色刻度",
+        "Lowest value" => "最小值",
+        "Highest value" => "最大值",
+        "Percent" => "百分比",
+        "Percentile" => "百分位",
+        "Formula" => "公式",
+        "Minimum" => "最小",
+        "Maximum" => "最大",
+        "Midpoint" => "中点",
+        "More Rules…" => "其他规则…",
+        "Select a Rule Type" => "选择规则类型",
+        "Edit the Rule Description" => "编辑规则说明",
+        "Format only cells that contain" => "仅对包含以下内容的单元格设置格式",
+        "Format only top or bottom ranked values" => "仅对排名靠前或靠后的数值设置格式",
+        "Format only values that are above or below average" => "仅对高于或低于平均值的数值设置格式",
+        "Format only unique or duplicate values" => "仅对唯一值或重复值设置格式",
+        "Use a formula to determine which cells to format" => "使用公式确定要设置格式的单元格",
+        "Format values where this formula is true:" => "为符合此公式的值设置格式:",
+        "with" => "格式:",
+        "This rule type isn't available yet." => "此规则类型尚不可用。",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/ribbon.rs b/crates/ui-egui/src/ribbon.rs
index 8ac5ae778a..302949cf6e 100644
--- a/crates/ui-egui/src/ribbon.rs
+++ b/crates/ui-egui/src/ribbon.rs
@@ -1469,6 +1469,10 @@ fn cf_menu(app: &mut SheetApp, ui: &mut Ui) {
                 act(app, "home.conditionalFormat", json!({"rule": {"type": "colorScale", "colors": cols}}));
             }
         }
+        ui.separator();
+        if ui.button("More Rules…").clicked() {
+            app.open_dialog("newFormattingRule", json!({"style": "3color"}));
+        }
     });
     ui.menu_button("Icon Sets", |ui| {
         for (label, set) in [
@@ -1486,7 +1490,7 @@ fn cf_menu(app: &mut SheetApp, ui: &mut Ui) {
     });
     ui.separator();
     if ui.button("New Rule…").clicked() {
-        app.open_dialog("cfQuick", json!({"type": "expression", "title": "New Formatting Rule"}));
+        app.open_dialog("newFormattingRule", json!({}));
     }
     ui.menu_button("Clear Rules", |ui| {
         menu_items(
@@ -2959,6 +2963,34 @@ mod title_bar_tests {
     }
 }
 
+#[cfg(test)]
+mod ribbon_tests {
+    use super::*;
+    use egui_kittest::kittest::Queryable;
+
+    #[test]
+    fn new_rule_opens_the_rule_type_list_with_the_formula_entry() {
+        let mut session = gridcraft_engine::Session::new();
+        session.new_workbook();
+        let app = SheetApp::new(session, Default::default());
+        let mut h = egui_kittest::Harness::builder().with_size(vec2(900.0, 800.0)).build_ui_state(
+            |ui, app: &mut SheetApp| {
+                cf_menu(app, ui);
+                crate::dialogs::show(app, ui.ctx());
+            },
+            app,
+        );
+        h.run_steps(2);
+        h.get_by_label("New Rule…").click();
+        h.run_steps(2);
+        let d = h.state().dialog.as_ref().expect("New Rule… opens a dialog");
+        assert_eq!(d.name(), "newFormattingRule");
+        assert_eq!(d.values.get("ruleType").and_then(serde_json::Value::as_str), Some("allCells"));
+        // Formula rules stay reachable: New Rule… shows Excel's rule-type list, formula entry included.
+        h.get_by_label("Use a formula to determine which cells to format");
+    }
+}
+
 #[cfg(test)]
 mod checkbox_on_tests {
     use super::*;
diff --git a/crates/ui-egui/tests/color_scale_rule.rs b/crates/ui-egui/tests/color_scale_rule.rs
new file mode 100644
index 0000000000..95afc236f4
--- /dev/null
+++ b/crates/ui-egui/tests/color_scale_rule.rs
@@ -0,0 +1,249 @@
+//! New Formatting Rule: the 2-/3-colour scale branch and in-place editing.
+
+use egui::vec2;
+use egui_kittest::kittest::Queryable;
+use gridcraft_engine::Session;
+use gridcraft_engine::model::{CfRule, CfValueKind, Color};
+use gridcraft_ui_egui::SheetApp;
+use serde_json::json;
+
+fn harness() -> egui_kittest::Harness<'static, SheetApp> {
+    let mut session = Session::new();
+    session.new_workbook();
+    session.run("range.setValues", json!({"range": "A1:A3", "values": [[1], [2], [3]]})).unwrap();
+    session.run("selection.set", json!({"range": "A1:A3"})).unwrap();
+    let mut h = egui_kittest::Harness::builder().with_size(vec2(1200.0, 800.0)).build_ui_state(
+        |ui, app: &mut SheetApp| {
+            app.logic(&ui.ctx().clone());
+            app.ui(ui);
+        },
+        SheetApp::new(session, Default::default()),
+    );
+    h.run_steps(6);
+    h
+}
+
+fn stops(h: &egui_kittest::Harness<'static, SheetApp>) -> Vec<(CfValueKind, Color)> {
+    let doc = h.state().session.active().unwrap();
+    let rule = &doc.wb.active().unwrap().cond_formats[0].rule;
+    match rule {
+        CfRule::ColorScale { stops } => stops.clone(),
+        _ => Vec::new(),
+    }
+}
+
+#[test]
+fn creates_a_three_colour_scale_with_per_stop_thresholds() {
+    let mut h = harness();
+    h.state_mut().run("home.conditionalFormat", json!({})).unwrap();
+    h.run_steps(6);
+    assert_eq!(h.state().dialog.as_ref().map(|d| d.name.as_str()), Some("newFormattingRule"));
+
+    h.state_mut().dialog.as_mut().unwrap().values.insert(
+        "stops".into(),
+        json!([
+            {"type": "min", "color": "#112233"},
+            {"type": "percentile", "value": 90, "color": "#445566"},
+            {"type": "max", "color": "#778899"},
+        ]),
+    );
+    h.run_steps(2);
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert!(h.state().dialog.is_none());
+    assert_eq!(
+        stops(&h),
+        vec![
+            (CfValueKind::Min, Color::Rgb(0x112233)),
+            (CfValueKind::Percentile(90.0), Color::Rgb(0x445566)),
+            (CfValueKind::Max, Color::Rgb(0x778899)),
+        ]
+    );
+}
+
+#[test]
+fn edits_an_existing_scale_in_place() {
+    let mut h = harness();
+    h.state_mut()
+        .run(
+            "home.conditionalFormat",
+            json!({"rule": {"type": "colorScale", "stops": [
+                {"type": "min", "color": "#112233"},
+                {"type": "percentile", "value": 50, "color": "#445566"},
+                {"type": "max", "color": "#778899"},
+            ]}}),
+        )
+        .unwrap();
+    let rule = serde_json::to_value(&h.state().session.active().unwrap().wb.active().unwrap().cond_formats[0].rule).unwrap();
+    h.state_mut().open_dialog("newFormattingRule", json!({"edit": 0, "rule": rule}));
+    h.run_steps(6);
+    h.state_mut().dialog.as_mut().unwrap().values.insert("style".into(), json!("2color"));
+    h.state_mut().dialog.as_mut().unwrap().values.insert(
+        "stops".into(),
+        json!([
+            {"type": "formula", "value": "$B$1", "color": "#ABCABC"},
+            {"type": "max", "color": "#DEFDEF"},
+        ]),
+    );
+    h.run_steps(2);
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert!(h.state().dialog.is_none());
+    assert_eq!(stops(&h), vec![(CfValueKind::Formula("$B$1".into()), Color::Rgb(0xABCABC)), (CfValueKind::Max, Color::Rgb(0xDEFDEF))]);
+}
+
+#[test]
+fn new_rule_still_creates_a_formula_rule() {
+    let mut h = harness();
+    h.state_mut().open_dialog("newFormattingRule", json!({}));
+    h.run_steps(6);
+    assert_eq!(h.state().dialog.as_ref().unwrap().values["ruleType"], json!("allCells"));
+
+    h.get_by_label("Use a formula to determine which cells to format").click();
+    h.run_steps(4);
+    assert_eq!(h.state().dialog.as_ref().unwrap().values["ruleType"], json!("formula"));
+    h.state_mut().dialog.as_mut().unwrap().values.insert("formula".into(), json!("=A1>2"));
+    h.run_steps(2);
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert!(h.state().dialog.is_none());
+    let rule = &h.state().session.active().unwrap().wb.active().unwrap().cond_formats[0].rule;
+    let CfRule::Expression { formula, .. } = rule else { panic!("expected a formula rule, got {rule:?}") };
+    assert_eq!(formula, "A1>2");
+}
+
+#[test]
+fn the_editor_widgets_drive_the_scale() {
+    let mut h = harness();
+    h.state_mut().open_dialog("newFormattingRule", json!({}));
+    h.run_steps(6);
+
+    // Format Style: 3 -> 2 -> 3 through the combo itself.
+    h.get_all_by_role(egui::accesskit::Role::ComboBox).next().expect("format style").click();
+    h.run_steps(2);
+    h.get_by_label("2-Color Scale").click();
+    h.run_steps(2);
+    assert_eq!(h.state().dialog.as_ref().unwrap().values["stops"].as_array().unwrap().len(), 2);
+    h.get_all_by_role(egui::accesskit::Role::ComboBox).next().expect("format style").click();
+    h.run_steps(2);
+    h.get_by_label("3-Color Scale").click();
+    h.run_steps(2);
+
+    // Midpoint: Percentile -> Number, then type a new threshold.
+    h.get_all_by_role(egui::accesskit::Role::ComboBox).nth(2).expect("midpoint type").click();
+    h.run_steps(2);
+    h.get_by_label("Number").click();
+    h.run_steps(2);
+    h.get_all_by_role(egui::accesskit::Role::SpinButton).next().expect("midpoint threshold").click();
+    h.run_steps(1);
+    h.key_press_modifiers(egui::Modifiers::COMMAND, egui::Key::A);
+    h.key_press(egui::Key::Backspace);
+    h.get_all_by_role(egui::accesskit::Role::SpinButton).next().expect("midpoint threshold").type_text("75");
+    h.key_press(egui::Key::Tab);
+    h.run_steps(2);
+    assert_eq!(h.state().dialog.as_ref().unwrap().values["stops"][1]["value"], json!(75.0));
+
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert_eq!(
+        stops(&h),
+        vec![(CfValueKind::Min, Color::Rgb(0xF8696B)), (CfValueKind::Number(75.0), Color::Rgb(0xFFEB84)), (CfValueKind::Max, Color::Rgb(0x63BE7B)),]
+    );
+}
+
+#[test]
+fn switching_three_to_two_to_three_uses_the_default_midpoint() {
+    let mut h = harness();
+    h.state_mut()
+        .run(
+            "home.conditionalFormat",
+            json!({"rule": {"type": "colorScale", "stops": [
+                {"type": "min", "color": "#112233"},
+                {"type": "percentile", "value": 50, "color": "#445566"},
+                {"type": "max", "color": "#778899"},
+            ]}}),
+        )
+        .unwrap();
+    let rule = serde_json::to_value(&h.state().session.active().unwrap().wb.active().unwrap().cond_formats[0].rule).unwrap();
+    h.state_mut().open_dialog("newFormattingRule", json!({"edit": 0, "rule": rule}));
+    h.run_steps(6);
+
+    // The style combo drives these transitions in `new_formatting_rule`.
+    h.state_mut().dialog.as_mut().unwrap().values.insert("style".into(), json!("2color"));
+    h.run_steps(2);
+    let two = h.state().dialog.as_ref().unwrap().values["stops"].as_array().unwrap().clone();
+    assert_eq!(two.len(), 2);
+    assert_eq!(two[0]["color"], json!("#112233"), "dropping the midpoint keeps the minimum's colour");
+    assert_eq!(two[1]["color"], json!("#778899"), "dropping the midpoint keeps the maximum's colour");
+
+    h.state_mut().dialog.as_mut().unwrap().values.insert("style".into(), json!("3color"));
+    h.run_steps(2);
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert!(h.state().dialog.is_none());
+    assert_eq!(
+        stops(&h),
+        vec![
+            (CfValueKind::Min, Color::Rgb(0x112233)),
+            (CfValueKind::Percentile(50.0), Color::Rgb(0xFFEB84)),
+            (CfValueKind::Max, Color::Rgb(0x778899)),
+        ]
+    );
+}
+
+#[test]
+fn edit_keeps_an_unchanged_theme_colour() {
+    let mut h = harness();
+    h.state_mut()
+        .run(
+            "home.conditionalFormat",
+            json!({"rule": {"type": "colorScale", "stops": [
+                {"type": "min", "color": {"theme": 4, "tint": 0}},
+                {"type": "percentile", "value": 50, "color": {"theme": 2, "tint": 0}},
+                {"type": "max", "color": {"theme": 6, "tint": 0}},
+            ]}}),
+        )
+        .unwrap();
+    let rule = serde_json::to_value(&h.state().session.active().unwrap().wb.active().unwrap().cond_formats[0].rule).unwrap();
+    h.state_mut().open_dialog("newFormattingRule", json!({"edit": 0, "rule": rule}));
+    h.run_steps(6);
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert!(h.state().dialog.is_none());
+    assert_eq!(
+        stops(&h),
+        vec![(CfValueKind::Min, Color::Theme(4, 0)), (CfValueKind::Percentile(50.0), Color::Theme(2, 0)), (CfValueKind::Max, Color::Theme(6, 0)),]
+    );
+}
+
+#[test]
+fn an_empty_formula_keeps_ok_disabled() {
+    let mut h = harness();
+    h.state_mut().open_dialog("newFormattingRule", json!({}));
+    h.run_steps(6);
+    h.get_by_label("Use a formula to determine which cells to format").click();
+    h.run_steps(4);
+    assert_eq!(h.state().dialog.as_ref().unwrap().values["ruleType"], json!("formula"));
+    // No formula typed: OK (and Enter) must do nothing, or the rule never applies.
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert!(h.state().dialog.is_some(), "the dialog stays open for a formula");
+    assert!(h.state().session.active().unwrap().wb.active().unwrap().cond_formats.is_empty());
+}
+
+#[test]
+fn an_unparseable_formula_is_refused_with_a_message() {
+    let mut h = harness();
+    h.state_mut().open_dialog("newFormattingRule", json!({}));
+    h.run_steps(6);
+    h.get_by_label("Use a formula to determine which cells to format").click();
+    h.run_steps(4);
+    h.state_mut().dialog.as_mut().unwrap().values.insert("formula".into(), json!("=C1>"));
+    h.run_steps(2);
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert!(h.state().dialog.is_some(), "an invalid formula keeps the dialog open");
+    let message = h.state().message.as_ref().map(|(_, m)| m.clone()).unwrap_or_default();
+    assert!(message.contains("invalid") && message.contains("does not parse"), "{message}");
+    assert!(h.state().session.active().unwrap().wb.active().unwrap().cond_formats.is_empty(), "no unopenable rule is stored");
+}
diff --git a/docs/gaps.md b/docs/gaps.md
index 77a4bde8cc..7e26d098cd 100644
--- a/docs/gaps.md
+++ b/docs/gaps.md
@@ -185,6 +185,7 @@ No alpha blockers: every core workflow passes the [alpha gate](roadmap.md#alpha-
 | 2026-10-23 | minor | §8: PivotTable Show Details: double-clicking a value cell lists its source records on a new sheet (#2364) |
 | 2026-10-20 | minor | §11: the Japanese catalog covers the dialogs, messages and menus — 943 keys (~43%), matching the pt-BR coverage; a test keeps the two catalogs in step |
 | 2026-10-17 | minor | §6: the five reports it tracked are closed and their PRs merged (#57, #133, #139, #140, #134; PRs #148, #155, #156, #157); the entry stays open for §15's oracle suite |
+| 2026-10-17 | minor | Conditional formatting: the 2-/3-colour scale branch of the New Formatting Rule dialog edits per-stop type/value/colour and updates rules in place (part of #1165) |
 | 2026-10-15 | minor | §6: Maximum Iterations and Maximum Change in File › Options › Formulas; dropped the stale "no Options dialog yet" |
 | 2026-10-15 | minor | §13: Solver prepares reports before committing the solution, model and report sheets together; report refusal preserves the workbook and Undo/Redo (#1050) |
 | 2026-10-13 | trivial | §4: multi-level category axes landed |
diff --git a/docs/target-app-parity.md b/docs/target-app-parity.md
index 99a1e0717a..b4e7a398d2 100644
--- a/docs/target-app-parity.md
+++ b/docs/target-app-parity.md
@@ -296,7 +296,8 @@ The inventory carried over from the 2026-10-07 ROADMAP.md, updated for what land
   the fill handle explains how to fill versus select cells.
 - Formatting: fonts, fills, all border styles, alignment (wrap, indent, rotation, merge), number
   formats, 47 cell styles, 60 table styles, conditional formatting (cell rules, text, dates,
-  duplicates, top/bottom, averages, data bars, colour scales, icon sets, formulas), automatic
+  duplicates, top/bottom, averages, data bars, colour scales with per-stop type/value/colour
+  editors, icon sets, formulas), automatic
   row heights, autofit, hide/unhide, freeze panes.
   Border presets include visual diagrams; Format Cells previews draft borders before applying.
 - Data: sort (multi-level, by colour, custom lists), AutoFilter (values, custom, top 10,
diff --git a/docs/ui-parity.md b/docs/ui-parity.md
index ed875cc8ef..bf5251901b 100644
--- a/docs/ui-parity.md
+++ b/docs/ui-parity.md
@@ -209,6 +209,7 @@ scrollbar bugs 2–4 · pixel/feel pass against observed Excel 7–12.
 | 2026-10-19 | trivial | While a mouse button is held (a click or a drag selecting cells) the selection outline is drawn on its cells at once instead of gliding after the pointer, which read as lag; keyboard moves still glide |
 | 2026-10-18 | minor | Keytip letters typed with left Alt held continue the sequence (Alt+H, O, A / Alt+H, O, I ran nothing before: Alt+letter cancelled keytips); other Alt combinations, AltGr and macOS Option are unchanged (#1846) |
 | 2026-10-17 | minor | A Ctrl+Alt+letter key that types a character (a user-defined Windows hotkey such as Ctrl+Alt+A for `ä`) types it instead of running the Ctrl+letter shortcut, e.g. Select All (#1530) |
+| 2026-10-17 | minor | Conditional formatting: 2-/3-colour scale editor with per-stop type/value/colour, reached from New Rule… → Format all cells based on their values and Color Scales › More Rules…; Manage Rules edits a scale in place (part of #1165) |
 | 2026-10-16 | minor | Right-drag on the fill handle opens the fill menu on release: Copy Cells, Fill Series, Fill Formatting Only, Fill Without Formatting, Series…; Esc cancels the drag or closes the menu without filling |
 | 2026-10-16 | minor | With the active cell in a Table whose header row is scrolled out of view, the column headings show the header names and their filter buttons in place of the letters (#1423) |
 | 2026-10-16 | minor | Ctrl+6 hides every object (charts, pictures, shapes, slicers) and shows them again; hidden objects are not drawn, take no clicks and drop their selection, and the setting is saved with the workbook (`workbookPr showObjects`) |
@@ -228,6 +229,7 @@ scrollbar bugs 2–4 · pixel/feel pass against observed Excel 7–12.
 | 2026-10-13 | minor | Grid drags keep their own cursor over selection borders, fill handles and outside the grid; hover resumes on release (#936) |
 | 2026-10-13 | minor | AutoFill month patterns retain the workbook's date system, preventing shifted dates in 1904 workbooks when filling forward or backward |
 | 2026-10-13 | minor | Sheet tab bar: the tab strip shrinks to its tabs, up to 60% of the bar, so New sheet (+) sits right after the last tab and the horizontal scrollbar takes the rest (part of #943) |
+| 2026-10-12 | minor | The File view's recent list tells when each workbook was last changed, read off the UI thread |
 | 2026-10-13 | minor | Horizontal scrollbar in the sheet tab bar: drag, track click pages, frozen columns excluded from the page (#840) |
 | 2026-10-13 | minor | Formula-entry Command/Ctrl-click adds arguments and Shift-click extends references; ordinary replacement and dragging retain their behavior. Readiness estimates unchanged. |
 | 2026-10-12 | minor | Next/previous sheet navigation no longer activates hidden worksheets at either workbook boundary; command tests cover Hidden, VeryHidden and selection retention |

From fded60a3259d0f7913dddaf5df1011f2e9aed834 Mon Sep 17 00:00:00 2001
From: alosslessdev <alosslessdev@users.noreply.github.com>
Date: Fri, 23 Oct 2026 05:01:20 -0500
Subject: [PATCH 02/10] Conditional formatting: refuse non-numeric colour-scale
 stop values (#1822)

---
 crates/engine/src/cmd/insert.rs | 98 +++++++++++++++++++++++++--------
 crates/ui-egui/src/dialogs.rs   |  5 ++
 2 files changed, 80 insertions(+), 23 deletions(-)

diff --git a/crates/engine/src/cmd/insert.rs b/crates/engine/src/cmd/insert.rs
index 1634cf32b0..45840d7738 100644
--- a/crates/engine/src/cmd/insert.rs
+++ b/crates/engine/src/cmd/insert.rs
@@ -1547,30 +1547,33 @@ fn cf_style(rule: &Json, cmd: &str) -> Result<Style> {
 }
 
 fn cf_value_kind(v: Option<&Json>, default: CfValueKind, cmd: &str) -> Result<CfValueKind> {
-    match v {
-        Some(Json::Object(o)) => {
-            let t = o.get("type").and_then(Json::as_str).unwrap_or("num");
-            let val = o.get("value").and_then(Json::as_f64).unwrap_or(0.0);
-            Ok(match t {
-                "min" => CfValueKind::Min,
-                "max" => CfValueKind::Max,
-                // The dialog clamps these to 0-100; engine callers get the same range.
-                "percent" => CfValueKind::Percent(val.clamp(0.0, 100.0)),
-                "percentile" => CfValueKind::Percentile(val.clamp(0.0, 100.0)),
-                "formula" => {
-                    let f = o.get("value").and_then(Json::as_str).unwrap_or("");
-                    if f.trim().is_empty() {
-                        return Err(bad(cmd, "a formula stop needs a formula"));
-                    }
-                    // Stored exactly: the evaluator takes the formula as written.
-                    CfValueKind::Formula(f.into())
-                }
-                "num" => CfValueKind::Number(val),
-                other => return Err(bad(cmd, format!("unknown stop type `{other}`"))),
-            })
+    let Some(Json::Object(o)) = v else { return Ok(default) };
+    let t = o.get("type").and_then(Json::as_str).unwrap_or("num");
+    // A value that is given must be a number: a string used to be read as 0 without a word.
+    // Only an omitted `value` defaults to zero.
+    let number = || -> Result<f64> {
+        match o.get("value") {
+            None => Ok(0.0),
+            Some(v) => v.as_f64().ok_or_else(|| bad(cmd, format!("the `{t}` stop's `value` must be a number, not {v}"))),
         }
-        _ => Ok(default),
-    }
+    };
+    Ok(match t {
+        "min" => CfValueKind::Min,
+        "max" => CfValueKind::Max,
+        // The dialog clamps these to 0-100; engine callers get the same range.
+        "percent" => CfValueKind::Percent(number()?.clamp(0.0, 100.0)),
+        "percentile" => CfValueKind::Percentile(number()?.clamp(0.0, 100.0)),
+        "formula" => {
+            let f = o.get("value").and_then(Json::as_str).unwrap_or("");
+            if f.trim().is_empty() {
+                return Err(bad(cmd, "a formula stop needs a formula"));
+            }
+            // Stored exactly: the evaluator takes the formula as written.
+            CfValueKind::Formula(f.into())
+        }
+        "num" => CfValueKind::Number(number()?),
+        other => return Err(bad(cmd, format!("unknown stop type `{other}`"))),
+    })
 }
 
 fn cf_rule(rule: &Json, cmd: &str) -> Result<CfRule> {
@@ -2014,6 +2017,55 @@ mod tests {
         assert_eq!(formula, "A1>2");
     }
 
+    #[test]
+    fn a_given_stop_value_must_be_a_number() {
+        let mut s = Session::new();
+        s.new_workbook();
+        for ty in ["num", "percent", "percentile"] {
+            let err = s
+                .execute(
+                    "home.conditionalFormat",
+                    json!({"range": "A1:A3", "rule": {"type": "colorScale", "stops": [
+                        {"type": ty, "value": "5", "color": "#112233"},
+                        {"type": "max", "color": "#778899"},
+                    ]}}),
+                )
+                .unwrap_err()
+                .to_string();
+            assert!(err.contains("home.conditionalFormat"), "{ty}: {err}");
+            assert!(err.contains(&format!("`{ty}` stop's `value` must be a number")), "{ty}: {err}");
+        }
+        // A refused scale stores nothing.
+        let rules = s.execute("home.manageRules", json!({})).unwrap();
+        assert_eq!(rules["rules"].as_array().map(Vec::len), Some(0));
+    }
+
+    #[test]
+    fn an_omitted_stop_value_is_zero() {
+        let mut s = Session::new();
+        s.new_workbook();
+        s.execute(
+            "home.conditionalFormat",
+            json!({"range": "A1:A3", "rule": {"type": "colorScale", "stops": [
+                {"type": "num", "color": "#112233"},
+                {"type": "percent", "color": "#445566"},
+                {"type": "percentile", "color": "#778899"},
+            ]}}),
+        )
+        .unwrap();
+        let list = s.execute("home.manageRules", json!({})).unwrap();
+        let rule: CfRule = serde_json::from_value(list["rules"][0]["rule"].clone()).unwrap();
+        let CfRule::ColorScale { stops } = rule else { panic!("expected a colour scale") };
+        assert_eq!(
+            stops,
+            vec![
+                (CfValueKind::Number(0.0), Color::Rgb(0x112233)),
+                (CfValueKind::Percent(0.0), Color::Rgb(0x445566)),
+                (CfValueKind::Percentile(0.0), Color::Rgb(0x778899)),
+            ]
+        );
+    }
+
     #[test]
     fn colour_scale_stops_keep_their_thresholds_and_can_be_edited() {
         let mut s = Session::new();
diff --git a/crates/ui-egui/src/dialogs.rs b/crates/ui-egui/src/dialogs.rs
index 5798c56caf..7b5a1fb009 100644
--- a/crates/ui-egui/src/dialogs.rs
+++ b/crates/ui-egui/src/dialogs.rs
@@ -2157,6 +2157,11 @@ fn colour_scale_editor(ui: &mut egui::Ui, d: &mut Dialog, lang: crate::i18n::Lan
                     {
                         obj.insert("value".into(), json!(n));
                     }
+                    // A numeric stop must carry a number: a stop switched from Lowest or
+                    // Highest value still holds `null`, which the engine refuses.
+                    if obj.get("value").and_then(Json::as_f64).is_none() {
+                        obj.insert("value".into(), json!(n));
+                    }
                 }
             }
             let c = parse_hex_color(obj.get("color").and_then(Json::as_str).unwrap_or("#FFFFFF"));

From 516b19c15183accac2033b301f7d1300c7bc10b9 Mon Sep 17 00:00:00 2001
From: alosslessdev <alosslessdev@users.noreply.github.com>
Date: Fri, 23 Oct 2026 05:34:22 -0500
Subject: [PATCH 03/10] Conditional formatting: require a formula for formula
 scale stops (#1822)

---
 crates/ui-egui/src/dialogs.rs            | 16 +++++--
 crates/ui-egui/tests/color_scale_rule.rs | 53 ++++++++++++++++++++++++
 2 files changed, 65 insertions(+), 4 deletions(-)

diff --git a/crates/ui-egui/src/dialogs.rs b/crates/ui-egui/src/dialogs.rs
index 7b5a1fb009..19cc8c97da 100644
--- a/crates/ui-egui/src/dialogs.rs
+++ b/crates/ui-egui/src/dialogs.rs
@@ -2146,9 +2146,10 @@ fn colour_scale_editor(ui: &mut egui::Ui, d: &mut Dialog, lang: crate::i18n::Lan
                 }
                 "formula" => {
                     let mut f = obj.get("value").and_then(Json::as_str).unwrap_or("").to_string();
-                    if ui.add(egui::TextEdit::singleline(&mut f).desired_width(120.0).hint_text(lang.tr("Formula"))).changed() {
-                        obj.insert("value".into(), json!(f));
-                    }
+                    ui.add(egui::TextEdit::singleline(&mut f).desired_width(120.0).hint_text(lang.tr("Formula")));
+                    // Store what the field shows as a string even when it was not edited: a
+                    // stop switched from Number still holds that number, which is no formula.
+                    obj.insert("value".into(), json!(f));
                 }
                 _ => {
                     let mut n = obj.get("value").and_then(Json::as_f64).unwrap_or(0.0);
@@ -2221,7 +2222,14 @@ fn new_formatting_rule(ui: &mut egui::Ui, d: &mut Dialog, confirm: &mut bool, op
     let supported = match rule_type.as_str() {
         "allCells" => {
             colour_scale_editor(ui, d, lang);
-            true
+            // A formula stop needs a formula: one whose value is missing, not a string, or
+            // blank would create a rule that never applies. Other stops confirm as they are.
+            d.values.get("stops").and_then(Json::as_array).is_none_or(|stops| {
+                stops.iter().all(|s| {
+                    s.get("type").and_then(Json::as_str) != Some("formula")
+                        || s.get("value").and_then(Json::as_str).is_some_and(|f| !f.trim().is_empty())
+                })
+            })
         }
         "formula" => {
             ui.label(lang.tr("Format values where this formula is true:"));
diff --git a/crates/ui-egui/tests/color_scale_rule.rs b/crates/ui-egui/tests/color_scale_rule.rs
index 95afc236f4..03fe078b7b 100644
--- a/crates/ui-egui/tests/color_scale_rule.rs
+++ b/crates/ui-egui/tests/color_scale_rule.rs
@@ -247,3 +247,56 @@ fn an_unparseable_formula_is_refused_with_a_message() {
     assert!(message.contains("invalid") && message.contains("does not parse"), "{message}");
     assert!(h.state().session.active().unwrap().wb.active().unwrap().cond_formats.is_empty(), "no unopenable rule is stored");
 }
+
+#[test]
+fn switching_a_numeric_stop_to_formula_needs_a_formula() {
+    let mut h = harness();
+    h.state_mut().open_dialog("newFormattingRule", json!({}));
+    h.run_steps(6);
+
+    // Switching a Number stop to Formula without touching the field: the editor must store the
+    // field as a string rather than leave the old number in place, and OK must wait for one.
+    h.state_mut().dialog.as_mut().unwrap().values.insert(
+        "stops".into(),
+        json!([
+            {"type": "formula", "value": 7, "color": "#112233"},
+            {"type": "max", "color": "#778899"},
+        ]),
+    );
+    h.run_steps(2);
+    let stops_json = h.state().dialog.as_ref().unwrap().values["stops"].as_array().unwrap().clone();
+    assert_eq!(stops_json[0]["value"], json!(""), "a numeric value is not a formula");
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert!(h.state().dialog.is_some(), "a formula stop with no formula does not confirm");
+    assert!(h.state().session.active().unwrap().wb.active().unwrap().cond_formats.is_empty());
+
+    // A blank formula is refused the same way.
+    h.state_mut().dialog.as_mut().unwrap().values.insert(
+        "stops".into(),
+        json!([
+            {"type": "formula", "value": "   ", "color": "#112233"},
+            {"type": "max", "color": "#778899"},
+        ]),
+    );
+    h.run_steps(2);
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert!(h.state().dialog.is_some(), "a blank formula does not confirm");
+    assert!(h.state().session.active().unwrap().wb.active().unwrap().cond_formats.is_empty());
+
+    // A real formula confirms.
+    h.state_mut().dialog.as_mut().unwrap().values.insert("style".into(), json!("2color"));
+    h.state_mut().dialog.as_mut().unwrap().values.insert(
+        "stops".into(),
+        json!([
+            {"type": "formula", "value": "$Z$1", "color": "#112233"},
+            {"type": "max", "color": "#778899"},
+        ]),
+    );
+    h.run_steps(2);
+    h.get_by_label("   OK   ").click();
+    h.run_steps(6);
+    assert!(h.state().dialog.is_none());
+    assert_eq!(stops(&h), vec![(CfValueKind::Formula("$Z$1".into()), Color::Rgb(0x112233)), (CfValueKind::Max, Color::Rgb(0x778899))]);
+}

From a327501fb1354c0c4952fa5b80e40f193dd57383 Mon Sep 17 00:00:00 2001
From: alosslessdev <alosslessdev@users.noreply.github.com>
Date: Sun, 25 Oct 2026 03:08:34 -0500
Subject: [PATCH 04/10] Conditional formatting: cover the new rule labels in
 the remaining catalogs (#1822)

---
 crates/ui-egui/src/i18n/el.rs | 29 +++++++++++++++++++++++++++
 crates/ui-egui/src/i18n/it.rs | 29 +++++++++++++++++++++++++++
 crates/ui-egui/src/i18n/nl.rs | 33 +++++++++++++++++++++++++++++++
 crates/ui-egui/src/i18n/pl.rs | 29 +++++++++++++++++++++++++++
 crates/ui-egui/src/i18n/ro.rs | 29 +++++++++++++++++++++++++++
 crates/ui-egui/src/i18n/tr.rs | 35 +++++++++++++++++++++++++++++++++
 crates/ui-egui/src/i18n/uk.rs | 37 +++++++++++++++++++++++++++++++++--
 crates/ui-egui/src/i18n/vi.rs | 35 +++++++++++++++++++++++++++++++++
 docs/ui-parity.md             |  1 -
 9 files changed, 254 insertions(+), 3 deletions(-)

diff --git a/crates/ui-egui/src/i18n/el.rs b/crates/ui-egui/src/i18n/el.rs
index d826b1eb85..965969f69e 100644
--- a/crates/ui-egui/src/i18n/el.rs
+++ b/crates/ui-egui/src/i18n/el.rs
@@ -983,6 +983,35 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "A CSV file, web page or PDF is a copy: the workbook keeps its own file." => {
             "Ένα αρχείο CSV, μια ιστοσελίδα ή ένα PDF είναι αντίγραφο: το βιβλίο εργασίας διατηρεί το δικό του αρχείο."
         }
+        // Conditional formatting: colour scales.
+        "New Formatting Rule" => "Νέος κανόνας μορφοποίησης",
+        "Format all cells based on their values" => "Μορφοποίηση όλων των κελιών με βάση τις τιμές τους",
+        "Format Style:" => "Στυλ μορφής:",
+        "2-Color Scale" => "Κλίμακα 2 χρωμάτων",
+        "3-Color Scale" => "Κλίμακα 3 χρωμάτων",
+        "Lowest value" => "Χαμηλότερη τιμή",
+        "Highest value" => "Υψηλότερη τιμή",
+        "Percent" => "Ποσοστό",
+        "Percentile" => "Εκατοστημόριο",
+        "Formula" => "Τύπος",
+        "Minimum" => "Ελάχιστο",
+        "Maximum" => "Μέγιστο",
+        "Midpoint" => "Μέσο σημείο",
+        "More Rules…" => "Περισσότεροι κανόνες…",
+        "Select a Rule Type" => "Επιλογή τύπου κανόνα",
+        "Edit the Rule Description" => "Επεξεργασία περιγραφής κανόνα",
+        "Format only cells that contain" => "Μορφοποίηση μόνο κελιών που περιέχουν",
+        "Format only top or bottom ranked values" => {
+            "Μορφοποίηση μόνο τιμών με την υψηλότερη ή χαμηλότερη κατάταξη"
+        }
+        "Format only values that are above or below average" => {
+            "Μορφοποίηση μόνο τιμών πάνω ή κάτω από τον μέσο όρο"
+        }
+        "Format only unique or duplicate values" => "Μορφοποίηση μόνο μοναδικών ή διπλότυπων τιμών",
+        "Use a formula to determine which cells to format" => {
+            "Χρήση τύπου για τον καθορισμό των κελιών που θα μορφοποιηθούν"
+        }
+        "This rule type isn't available yet." => "Αυτός ο τύπος κανόνα δεν είναι ακόμη διαθέσιμος.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/it.rs b/crates/ui-egui/src/i18n/it.rs
index 7f79b40762..f7becbffbf 100644
--- a/crates/ui-egui/src/i18n/it.rs
+++ b/crates/ui-egui/src/i18n/it.rs
@@ -986,6 +986,35 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Report Layout" => "Layout rapporto",
         "Compact" => "Compatto",
         "Tabular" => "Tabulare",
+        // Conditional formatting: colour scales.
+        "New Formatting Rule" => "Nuova regola di formattazione",
+        "Format all cells based on their values" => "Formatta tutte le celle in base ai loro valori",
+        "Format Style:" => "Stile formato:",
+        "2-Color Scale" => "Scala a 2 colori",
+        "3-Color Scale" => "Scala a 3 colori",
+        "Lowest value" => "Valore minimo",
+        "Highest value" => "Valore massimo",
+        "Percent" => "Percentuale",
+        "Percentile" => "Percentile",
+        "Formula" => "Formula",
+        "Minimum" => "Minimo",
+        "Maximum" => "Massimo",
+        "Midpoint" => "Punto medio",
+        "More Rules…" => "Altre regole…",
+        "Select a Rule Type" => "Seleziona un tipo di regola",
+        "Edit the Rule Description" => "Modifica la descrizione della regola",
+        "Format only cells that contain" => "Formatta solo le celle che contengono",
+        "Format only top or bottom ranked values" => {
+            "Formatta solo i valori con classificazione superiore o inferiore"
+        }
+        "Format only values that are above or below average" => {
+            "Formatta solo i valori superiori o inferiori alla media"
+        }
+        "Format only unique or duplicate values" => "Formatta solo valori univoci o duplicati",
+        "Use a formula to determine which cells to format" => {
+            "Usa una formula per determinare quali celle formattare"
+        }
+        "This rule type isn't available yet." => "Questo tipo di regola non è ancora disponibile.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/nl.rs b/crates/ui-egui/src/i18n/nl.rs
index 9cedcce74c..74693c23d2 100644
--- a/crates/ui-egui/src/i18n/nl.rs
+++ b/crates/ui-egui/src/i18n/nl.rs
@@ -527,6 +527,39 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Zoom In" => "Inzoomen",
         "Zoom Out" => "Uitzoomen",
         "Dismiss" => "Negeren",
+        // Conditional formatting: colour scales.
+        "New Formatting Rule" => "Nieuwe opmaakregel",
+        "Format all cells based on their values" => "Alle cellen opmaken op basis van hun waarden",
+        "Format Style:" => "Opmaakstijl:",
+        "2-Color Scale" => "Schaal met 2 kleuren",
+        "3-Color Scale" => "Schaal met 3 kleuren",
+        "Lowest value" => "Laagste waarde",
+        "Highest value" => "Hoogste waarde",
+        "Percent" => "Percentage",
+        "Percentile" => "Percentiel",
+        "Formula" => "Formule",
+        "Minimum" => "Minimum",
+        "Maximum" => "Maximum",
+        "Midpoint" => "Middelpunt",
+        "More Rules…" => "Meer regels…",
+        "Select a Rule Type" => "Een regeltype selecteren",
+        "Edit the Rule Description" => "De beschrijving van de regel bewerken",
+        "Format only cells that contain" => "Alleen cellen opmaken die bevatten",
+        "Format only top or bottom ranked values" => {
+            "Alleen waarden met een hoge of lage rangorde opmaken"
+        }
+        "Format only values that are above or below average" => {
+            "Alleen waarden boven of onder het gemiddelde opmaken"
+        }
+        "Format only unique or duplicate values" => "Alleen unieke of dubbele waarden opmaken",
+        "Use a formula to determine which cells to format" => {
+            "Een formule gebruiken om te bepalen welke cellen worden opgemaakt"
+        }
+        "Format values where this formula is true:" => {
+            "Waarden opmaken waarop deze formule waar is:"
+        }
+        "with" => "met",
+        "This rule type isn't available yet." => "Dit regeltype is nog niet beschikbaar.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/pl.rs b/crates/ui-egui/src/i18n/pl.rs
index 1a229f90df..8f93e98709 100644
--- a/crates/ui-egui/src/i18n/pl.rs
+++ b/crates/ui-egui/src/i18n/pl.rs
@@ -977,6 +977,35 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Report Layout" => "Układ raportu",
         "Compact" => "Kompaktowy",
         "Tabular" => "Tabelaryczny",
+        // Conditional formatting: colour scales.
+        "New Formatting Rule" => "Nowa reguła formatowania",
+        "Format all cells based on their values" => "Formatuj wszystkie komórki na podstawie ich wartości",
+        "Format Style:" => "Styl formatu:",
+        "2-Color Scale" => "Skala dwukolorowa",
+        "3-Color Scale" => "Skala trójkolorowa",
+        "Lowest value" => "Najniższa wartość",
+        "Highest value" => "Najwyższa wartość",
+        "Percent" => "Procent",
+        "Percentile" => "Percentyl",
+        "Formula" => "Formuła",
+        "Minimum" => "Minimum",
+        "Maximum" => "Maksimum",
+        "Midpoint" => "Punkt środkowy",
+        "More Rules…" => "Więcej reguł…",
+        "Select a Rule Type" => "Wybierz typ reguły",
+        "Edit the Rule Description" => "Edytuj opis reguły",
+        "Format only cells that contain" => "Formatuj tylko komórki zawierające",
+        "Format only top or bottom ranked values" => {
+            "Formatuj tylko wartości o najwyższej lub najniższej pozycji"
+        }
+        "Format only values that are above or below average" => {
+            "Formatuj tylko wartości powyżej lub poniżej średniej"
+        }
+        "Format only unique or duplicate values" => "Formatuj tylko wartości unikatowe lub zduplikowane",
+        "Use a formula to determine which cells to format" => {
+            "Użyj formuły do określenia, które komórki mają być formatowane"
+        }
+        "This rule type isn't available yet." => "Ten typ reguły nie jest jeszcze dostępny.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/ro.rs b/crates/ui-egui/src/i18n/ro.rs
index e715768484..759d94962b 100644
--- a/crates/ui-egui/src/i18n/ro.rs
+++ b/crates/ui-egui/src/i18n/ro.rs
@@ -1039,6 +1039,35 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Format Chart Area…" => "Formatare zonă diagramă…",
         "Error checking options" => "Opțiuni de verificare a erorilor",
         "Paste formulas that refer to the copied cells" => "Lipire formule care fac referire la celulele copiate",
+        // Conditional formatting: colour scales.
+        "New Formatting Rule" => "Regulă de formatare nouă",
+        "Format all cells based on their values" => "Formatați toate celulele în funcție de valorile lor",
+        "Format Style:" => "Stil de formatare:",
+        "2-Color Scale" => "Scară cu 2 culori",
+        "3-Color Scale" => "Scară cu 3 culori",
+        "Lowest value" => "Valoarea cea mai mică",
+        "Highest value" => "Valoarea cea mai mare",
+        "Percent" => "Procent",
+        "Percentile" => "Percentilă",
+        "Formula" => "Formulă",
+        "Minimum" => "Minim",
+        "Maximum" => "Maxim",
+        "Midpoint" => "Punct de mijloc",
+        "More Rules…" => "Mai multe reguli…",
+        "Select a Rule Type" => "Selectați un tip de regulă",
+        "Edit the Rule Description" => "Editați descrierea regulii",
+        "Format only cells that contain" => "Formatați numai celulele care conțin",
+        "Format only top or bottom ranked values" => {
+            "Formatați numai valorile clasate primele sau ultimele"
+        }
+        "Format only values that are above or below average" => {
+            "Formatați numai valorile peste sau sub medie"
+        }
+        "Format only unique or duplicate values" => "Formatați numai valorile unice sau duplicate",
+        "Use a formula to determine which cells to format" => {
+            "Utilizați o formulă pentru a stabili ce celule să fie formatate"
+        }
+        "This rule type isn't available yet." => "Acest tip de regulă nu este încă disponibil.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/tr.rs b/crates/ui-egui/src/i18n/tr.rs
index ea1a16380e..54eee9cc32 100644
--- a/crates/ui-egui/src/i18n/tr.rs
+++ b/crates/ui-egui/src/i18n/tr.rs
@@ -416,6 +416,41 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Print" => "Yazdır",
         "Print What" => "Yazdırılacaklar",
         "Text Box" => "Metin Kutusu",
+        // Conditional formatting: colour scales.
+        "New Formatting Rule" => "Yeni Biçimlendirme Kuralı",
+        "Format all cells based on their values" => "Tüm hücreleri değerlerine göre biçimlendir",
+        "Format Style:" => "Biçim Stili:",
+        "2-Color Scale" => "2 Renkli Ölçek",
+        "3-Color Scale" => "3 Renkli Ölçek",
+        "Lowest value" => "En düşük değer",
+        "Highest value" => "En yüksek değer",
+        "Percent" => "Yüzde",
+        "Percentile" => "Yüzdebirlik",
+        "Formula" => "Formül",
+        "Minimum" => "Minimum",
+        "Maximum" => "Maksimum",
+        "Midpoint" => "Orta nokta",
+        "More Rules…" => "Diğer Kurallar…",
+        "Select a Rule Type" => "Kural Türü Seçin",
+        "Edit the Rule Description" => "Kural Açıklamasını Düzenle",
+        "Format only cells that contain" => "Yalnızca şunu içeren hücreleri biçimlendir",
+        "Format only top or bottom ranked values" => {
+            "Yalnızca en yüksek veya en düşük sıralamadaki değerleri biçimlendir"
+        }
+        "Format only values that are above or below average" => {
+            "Yalnızca ortalamanın üstündeki veya altındaki değerleri biçimlendir"
+        }
+        "Format only unique or duplicate values" => {
+            "Yalnızca benzersiz veya yinelenen değerleri biçimlendir"
+        }
+        "Use a formula to determine which cells to format" => {
+            "Hangi hücrelerin biçimlendirileceğini belirlemek için formül kullan"
+        }
+        "Format values where this formula is true:" => {
+            "Bu formülün doğru olduğu değerleri biçimlendir:"
+        }
+        "with" => "ile",
+        "This rule type isn't available yet." => "Bu kural türü henüz kullanılamıyor.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/uk.rs b/crates/ui-egui/src/i18n/uk.rs
index 8055f77fc5..cecbde945a 100644
--- a/crates/ui-egui/src/i18n/uk.rs
+++ b/crates/ui-egui/src/i18n/uk.rs
@@ -633,8 +633,6 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Last month" => "Last month",
         "This month" => "This month",
         "Next month" => "Next month",
-        "Format values where this formula is true:" => "Format values where this formula is true:",
-        "with" => "with",
         "Light Red Fill with Dark Red Text" => "Light Red Fill with Dark Red Text",
         "Yellow Fill with Dark Yellow Text" => "Yellow Fill with Dark Yellow Text",
         "Green Fill with Dark Green Text" => "Green Fill with Dark Green Text",
@@ -981,6 +979,41 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Report Layout" => "Report Layout",
         "Compact" => "Compact",
         "Tabular" => "Tabular",
+        // Conditional formatting: colour scales.
+        "New Formatting Rule" => "Нове правило форматування",
+        "Format all cells based on their values" => "Форматувати всі клітинки за їхніми значеннями",
+        "Format Style:" => "Стиль формату:",
+        "2-Color Scale" => "Двоколірна шкала",
+        "3-Color Scale" => "Триколірна шкала",
+        "Lowest value" => "Найнижче значення",
+        "Highest value" => "Найвище значення",
+        "Percent" => "Відсоток",
+        "Percentile" => "Перцентиль",
+        "Formula" => "Формула",
+        "Minimum" => "Мінімум",
+        "Maximum" => "Максимум",
+        "Midpoint" => "Середина",
+        "More Rules…" => "Більше правил…",
+        "Select a Rule Type" => "Виберіть тип правила",
+        "Edit the Rule Description" => "Редагувати опис правила",
+        "Format only cells that contain" => "Форматувати лише клітинки, що містять",
+        "Format only top or bottom ranked values" => {
+            "Форматувати лише значення з найвищим або найнижчим рейтингом"
+        }
+        "Format only values that are above or below average" => {
+            "Форматувати лише значення вище або нижче середнього"
+        }
+        "Format only unique or duplicate values" => {
+            "Форматувати лише унікальні або повторювані значення"
+        }
+        "Use a formula to determine which cells to format" => {
+            "Використати формулу, щоб визначити, які клітинки форматувати"
+        }
+        "Format values where this formula is true:" => {
+            "Форматувати значення, для яких ця формула істинна:"
+        }
+        "with" => "з",
+        "This rule type isn't available yet." => "Цей тип правила ще недоступний.",
         _ => return None,
     })
 }
diff --git a/crates/ui-egui/src/i18n/vi.rs b/crates/ui-egui/src/i18n/vi.rs
index 874c7caff6..b33a8c5145 100644
--- a/crates/ui-egui/src/i18n/vi.rs
+++ b/crates/ui-egui/src/i18n/vi.rs
@@ -418,6 +418,41 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Enable iterative calculation" => "Bật tính toán lặp",
         "Calculation settings are saved with the workbook." => "Thiết lập tính toán được lưu cùng sổ làm việc.",
         "Text Box" => "Hộp văn bản",
+        // Conditional formatting: colour scales.
+        "New Formatting Rule" => "Quy tắc định dạng mới",
+        "Format all cells based on their values" => "Định dạng tất cả ô dựa trên giá trị của chúng",
+        "Format Style:" => "Kiểu định dạng:",
+        "2-Color Scale" => "Thang 2 màu",
+        "3-Color Scale" => "Thang 3 màu",
+        "Lowest value" => "Giá trị thấp nhất",
+        "Highest value" => "Giá trị cao nhất",
+        "Percent" => "Phần trăm",
+        "Percentile" => "Bách phân vị",
+        "Formula" => "Công thức",
+        "Minimum" => "Tối thiểu",
+        "Maximum" => "Tối đa",
+        "Midpoint" => "Điểm giữa",
+        "More Rules…" => "Thêm quy tắc…",
+        "Select a Rule Type" => "Chọn loại quy tắc",
+        "Edit the Rule Description" => "Sửa mô tả quy tắc",
+        "Format only cells that contain" => "Chỉ định dạng các ô chứa",
+        "Format only top or bottom ranked values" => {
+            "Chỉ định dạng các giá trị có thứ hạng cao nhất hoặc thấp nhất"
+        }
+        "Format only values that are above or below average" => {
+            "Chỉ định dạng các giá trị trên hoặc dưới mức trung bình"
+        }
+        "Format only unique or duplicate values" => {
+            "Chỉ định dạng các giá trị duy nhất hoặc trùng lặp"
+        }
+        "Use a formula to determine which cells to format" => {
+            "Dùng công thức để xác định ô nào cần định dạng"
+        }
+        "Format values where this formula is true:" => {
+            "Định dạng các giá trị mà công thức này đúng:"
+        }
+        "with" => "với",
+        "This rule type isn't available yet." => "Loại quy tắc này chưa khả dụng.",
         _ => return None,
     })
 }
diff --git a/docs/ui-parity.md b/docs/ui-parity.md
index bf5251901b..2245ed13f6 100644
--- a/docs/ui-parity.md
+++ b/docs/ui-parity.md
@@ -229,7 +229,6 @@ scrollbar bugs 2–4 · pixel/feel pass against observed Excel 7–12.
 | 2026-10-13 | minor | Grid drags keep their own cursor over selection borders, fill handles and outside the grid; hover resumes on release (#936) |
 | 2026-10-13 | minor | AutoFill month patterns retain the workbook's date system, preventing shifted dates in 1904 workbooks when filling forward or backward |
 | 2026-10-13 | minor | Sheet tab bar: the tab strip shrinks to its tabs, up to 60% of the bar, so New sheet (+) sits right after the last tab and the horizontal scrollbar takes the rest (part of #943) |
-| 2026-10-12 | minor | The File view's recent list tells when each workbook was last changed, read off the UI thread |
 | 2026-10-13 | minor | Horizontal scrollbar in the sheet tab bar: drag, track click pages, frozen columns excluded from the page (#840) |
 | 2026-10-13 | minor | Formula-entry Command/Ctrl-click adds arguments and Shift-click extends references; ordinary replacement and dragging retain their behavior. Readiness estimates unchanged. |
 | 2026-10-12 | minor | Next/previous sheet navigation no longer activates hidden worksheets at either workbook boundary; command tests cover Hidden, VeryHidden and selection retention |

From 6cfd7d83aa217ee8873f84ff32fd084d4aea476e Mon Sep 17 00:00:00 2001
From: alosslessdev <alosslessdev@users.noreply.github.com>
Date: Sun, 25 Oct 2026 03:08:48 -0500
Subject: [PATCH 05/10] Contributors: add alosslessdev (#1822)

---
 contributors/people.toml | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/contributors/people.toml b/contributors/people.toml
index 5ce80fe59e..32e5b90cba 100644
--- a/contributors/people.toml
+++ b/contributors/people.toml
@@ -103,3 +103,6 @@ real_name = "Helen Kwok"
 [people.dotCooCoo]
 real_name = "Robert Lee"
 sync_github_name = true
+
+[people.alosslessdev]
+real_name = "Francisco Herrera"

From 8b17f1e779f8d36fac7349381ae5b0289b9d6d3c Mon Sep 17 00:00:00 2001
From: alosslessdev <alosslessdev@users.noreply.github.com>
Date: Sun, 25 Oct 2026 03:14:34 -0500
Subject: [PATCH 06/10] Conditional formatting: rustfmt after the rebase
 (#1822)

---
 crates/ui-egui/src/dialogs.rs |  6 ++----
 crates/ui-egui/src/i18n/el.rs | 12 +++---------
 crates/ui-egui/src/i18n/it.rs | 12 +++---------
 crates/ui-egui/src/i18n/nl.rs | 16 ++++------------
 crates/ui-egui/src/i18n/pl.rs | 12 +++---------
 crates/ui-egui/src/i18n/ro.rs | 12 +++---------
 crates/ui-egui/src/i18n/tr.rs | 20 +++++---------------
 crates/ui-egui/src/i18n/uk.rs | 20 +++++---------------
 crates/ui-egui/src/i18n/vi.rs | 20 +++++---------------
 9 files changed, 33 insertions(+), 97 deletions(-)

diff --git a/crates/ui-egui/src/dialogs.rs b/crates/ui-egui/src/dialogs.rs
index 19cc8c97da..ff655960d3 100644
--- a/crates/ui-egui/src/dialogs.rs
+++ b/crates/ui-egui/src/dialogs.rs
@@ -1741,10 +1741,8 @@ fn ok_cancel_enabled(ui: &mut egui::Ui, confirm: &mut bool, open: &mut bool, ena
         ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
             let lang = crate::i18n::current(ui.ctx());
             let t = crate::theme::Tokens::get(ui.ctx());
-            let ok = ui.add_enabled(
-                enabled,
-                egui::Button::new(egui::RichText::new(format!("   {}   ", lang.tr("OK"))).color(t.on_accent)).fill(t.accent),
-            );
+            let ok =
+                ui.add_enabled(enabled, egui::Button::new(egui::RichText::new(format!("   {}   ", lang.tr("OK"))).color(t.on_accent)).fill(t.accent));
             if enabled && (ok.clicked() || ui.input(|i| i.key_pressed(Key::Enter))) {
                 *confirm = true;
             }
diff --git a/crates/ui-egui/src/i18n/el.rs b/crates/ui-egui/src/i18n/el.rs
index 965969f69e..07b80c21fe 100644
--- a/crates/ui-egui/src/i18n/el.rs
+++ b/crates/ui-egui/src/i18n/el.rs
@@ -1001,16 +1001,10 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Select a Rule Type" => "Επιλογή τύπου κανόνα",
         "Edit the Rule Description" => "Επεξεργασία περιγραφής κανόνα",
         "Format only cells that contain" => "Μορφοποίηση μόνο κελιών που περιέχουν",
-        "Format only top or bottom ranked values" => {
-            "Μορφοποίηση μόνο τιμών με την υψηλότερη ή χαμηλότερη κατάταξη"
-        }
-        "Format only values that are above or below average" => {
-            "Μορφοποίηση μόνο τιμών πάνω ή κάτω από τον μέσο όρο"
-        }
+        "Format only top or bottom ranked values" => "Μορφοποίηση μόνο τιμών με την υψηλότερη ή χαμηλότερη κατάταξη",
+        "Format only values that are above or below average" => "Μορφοποίηση μόνο τιμών πάνω ή κάτω από τον μέσο όρο",
         "Format only unique or duplicate values" => "Μορφοποίηση μόνο μοναδικών ή διπλότυπων τιμών",
-        "Use a formula to determine which cells to format" => {
-            "Χρήση τύπου για τον καθορισμό των κελιών που θα μορφοποιηθούν"
-        }
+        "Use a formula to determine which cells to format" => "Χρήση τύπου για τον καθορισμό των κελιών που θα μορφοποιηθούν",
         "This rule type isn't available yet." => "Αυτός ο τύπος κανόνα δεν είναι ακόμη διαθέσιμος.",
         _ => return None,
     })
diff --git a/crates/ui-egui/src/i18n/it.rs b/crates/ui-egui/src/i18n/it.rs
index f7becbffbf..076eed42d2 100644
--- a/crates/ui-egui/src/i18n/it.rs
+++ b/crates/ui-egui/src/i18n/it.rs
@@ -1004,16 +1004,10 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Select a Rule Type" => "Seleziona un tipo di regola",
         "Edit the Rule Description" => "Modifica la descrizione della regola",
         "Format only cells that contain" => "Formatta solo le celle che contengono",
-        "Format only top or bottom ranked values" => {
-            "Formatta solo i valori con classificazione superiore o inferiore"
-        }
-        "Format only values that are above or below average" => {
-            "Formatta solo i valori superiori o inferiori alla media"
-        }
+        "Format only top or bottom ranked values" => "Formatta solo i valori con classificazione superiore o inferiore",
+        "Format only values that are above or below average" => "Formatta solo i valori superiori o inferiori alla media",
         "Format only unique or duplicate values" => "Formatta solo valori univoci o duplicati",
-        "Use a formula to determine which cells to format" => {
-            "Usa una formula per determinare quali celle formattare"
-        }
+        "Use a formula to determine which cells to format" => "Usa una formula per determinare quali celle formattare",
         "This rule type isn't available yet." => "Questo tipo di regola non è ancora disponibile.",
         _ => return None,
     })
diff --git a/crates/ui-egui/src/i18n/nl.rs b/crates/ui-egui/src/i18n/nl.rs
index 74693c23d2..cb8160669d 100644
--- a/crates/ui-egui/src/i18n/nl.rs
+++ b/crates/ui-egui/src/i18n/nl.rs
@@ -545,19 +545,11 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Select a Rule Type" => "Een regeltype selecteren",
         "Edit the Rule Description" => "De beschrijving van de regel bewerken",
         "Format only cells that contain" => "Alleen cellen opmaken die bevatten",
-        "Format only top or bottom ranked values" => {
-            "Alleen waarden met een hoge of lage rangorde opmaken"
-        }
-        "Format only values that are above or below average" => {
-            "Alleen waarden boven of onder het gemiddelde opmaken"
-        }
+        "Format only top or bottom ranked values" => "Alleen waarden met een hoge of lage rangorde opmaken",
+        "Format only values that are above or below average" => "Alleen waarden boven of onder het gemiddelde opmaken",
         "Format only unique or duplicate values" => "Alleen unieke of dubbele waarden opmaken",
-        "Use a formula to determine which cells to format" => {
-            "Een formule gebruiken om te bepalen welke cellen worden opgemaakt"
-        }
-        "Format values where this formula is true:" => {
-            "Waarden opmaken waarop deze formule waar is:"
-        }
+        "Use a formula to determine which cells to format" => "Een formule gebruiken om te bepalen welke cellen worden opgemaakt",
+        "Format values where this formula is true:" => "Waarden opmaken waarop deze formule waar is:",
         "with" => "met",
         "This rule type isn't available yet." => "Dit regeltype is nog niet beschikbaar.",
         _ => return None,
diff --git a/crates/ui-egui/src/i18n/pl.rs b/crates/ui-egui/src/i18n/pl.rs
index 8f93e98709..d1fccc0d7f 100644
--- a/crates/ui-egui/src/i18n/pl.rs
+++ b/crates/ui-egui/src/i18n/pl.rs
@@ -995,16 +995,10 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Select a Rule Type" => "Wybierz typ reguły",
         "Edit the Rule Description" => "Edytuj opis reguły",
         "Format only cells that contain" => "Formatuj tylko komórki zawierające",
-        "Format only top or bottom ranked values" => {
-            "Formatuj tylko wartości o najwyższej lub najniższej pozycji"
-        }
-        "Format only values that are above or below average" => {
-            "Formatuj tylko wartości powyżej lub poniżej średniej"
-        }
+        "Format only top or bottom ranked values" => "Formatuj tylko wartości o najwyższej lub najniższej pozycji",
+        "Format only values that are above or below average" => "Formatuj tylko wartości powyżej lub poniżej średniej",
         "Format only unique or duplicate values" => "Formatuj tylko wartości unikatowe lub zduplikowane",
-        "Use a formula to determine which cells to format" => {
-            "Użyj formuły do określenia, które komórki mają być formatowane"
-        }
+        "Use a formula to determine which cells to format" => "Użyj formuły do określenia, które komórki mają być formatowane",
         "This rule type isn't available yet." => "Ten typ reguły nie jest jeszcze dostępny.",
         _ => return None,
     })
diff --git a/crates/ui-egui/src/i18n/ro.rs b/crates/ui-egui/src/i18n/ro.rs
index 759d94962b..f2f1305120 100644
--- a/crates/ui-egui/src/i18n/ro.rs
+++ b/crates/ui-egui/src/i18n/ro.rs
@@ -1057,16 +1057,10 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Select a Rule Type" => "Selectați un tip de regulă",
         "Edit the Rule Description" => "Editați descrierea regulii",
         "Format only cells that contain" => "Formatați numai celulele care conțin",
-        "Format only top or bottom ranked values" => {
-            "Formatați numai valorile clasate primele sau ultimele"
-        }
-        "Format only values that are above or below average" => {
-            "Formatați numai valorile peste sau sub medie"
-        }
+        "Format only top or bottom ranked values" => "Formatați numai valorile clasate primele sau ultimele",
+        "Format only values that are above or below average" => "Formatați numai valorile peste sau sub medie",
         "Format only unique or duplicate values" => "Formatați numai valorile unice sau duplicate",
-        "Use a formula to determine which cells to format" => {
-            "Utilizați o formulă pentru a stabili ce celule să fie formatate"
-        }
+        "Use a formula to determine which cells to format" => "Utilizați o formulă pentru a stabili ce celule să fie formatate",
         "This rule type isn't available yet." => "Acest tip de regulă nu este încă disponibil.",
         _ => return None,
     })
diff --git a/crates/ui-egui/src/i18n/tr.rs b/crates/ui-egui/src/i18n/tr.rs
index 54eee9cc32..8bb90341d9 100644
--- a/crates/ui-egui/src/i18n/tr.rs
+++ b/crates/ui-egui/src/i18n/tr.rs
@@ -434,21 +434,11 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Select a Rule Type" => "Kural Türü Seçin",
         "Edit the Rule Description" => "Kural Açıklamasını Düzenle",
         "Format only cells that contain" => "Yalnızca şunu içeren hücreleri biçimlendir",
-        "Format only top or bottom ranked values" => {
-            "Yalnızca en yüksek veya en düşük sıralamadaki değerleri biçimlendir"
-        }
-        "Format only values that are above or below average" => {
-            "Yalnızca ortalamanın üstündeki veya altındaki değerleri biçimlendir"
-        }
-        "Format only unique or duplicate values" => {
-            "Yalnızca benzersiz veya yinelenen değerleri biçimlendir"
-        }
-        "Use a formula to determine which cells to format" => {
-            "Hangi hücrelerin biçimlendirileceğini belirlemek için formül kullan"
-        }
-        "Format values where this formula is true:" => {
-            "Bu formülün doğru olduğu değerleri biçimlendir:"
-        }
+        "Format only top or bottom ranked values" => "Yalnızca en yüksek veya en düşük sıralamadaki değerleri biçimlendir",
+        "Format only values that are above or below average" => "Yalnızca ortalamanın üstündeki veya altındaki değerleri biçimlendir",
+        "Format only unique or duplicate values" => "Yalnızca benzersiz veya yinelenen değerleri biçimlendir",
+        "Use a formula to determine which cells to format" => "Hangi hücrelerin biçimlendirileceğini belirlemek için formül kullan",
+        "Format values where this formula is true:" => "Bu formülün doğru olduğu değerleri biçimlendir:",
         "with" => "ile",
         "This rule type isn't available yet." => "Bu kural türü henüz kullanılamıyor.",
         _ => return None,
diff --git a/crates/ui-egui/src/i18n/uk.rs b/crates/ui-egui/src/i18n/uk.rs
index cecbde945a..760bae32f2 100644
--- a/crates/ui-egui/src/i18n/uk.rs
+++ b/crates/ui-egui/src/i18n/uk.rs
@@ -997,21 +997,11 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Select a Rule Type" => "Виберіть тип правила",
         "Edit the Rule Description" => "Редагувати опис правила",
         "Format only cells that contain" => "Форматувати лише клітинки, що містять",
-        "Format only top or bottom ranked values" => {
-            "Форматувати лише значення з найвищим або найнижчим рейтингом"
-        }
-        "Format only values that are above or below average" => {
-            "Форматувати лише значення вище або нижче середнього"
-        }
-        "Format only unique or duplicate values" => {
-            "Форматувати лише унікальні або повторювані значення"
-        }
-        "Use a formula to determine which cells to format" => {
-            "Використати формулу, щоб визначити, які клітинки форматувати"
-        }
-        "Format values where this formula is true:" => {
-            "Форматувати значення, для яких ця формула істинна:"
-        }
+        "Format only top or bottom ranked values" => "Форматувати лише значення з найвищим або найнижчим рейтингом",
+        "Format only values that are above or below average" => "Форматувати лише значення вище або нижче середнього",
+        "Format only unique or duplicate values" => "Форматувати лише унікальні або повторювані значення",
+        "Use a formula to determine which cells to format" => "Використати формулу, щоб визначити, які клітинки форматувати",
+        "Format values where this formula is true:" => "Форматувати значення, для яких ця формула істинна:",
         "with" => "з",
         "This rule type isn't available yet." => "Цей тип правила ще недоступний.",
         _ => return None,
diff --git a/crates/ui-egui/src/i18n/vi.rs b/crates/ui-egui/src/i18n/vi.rs
index b33a8c5145..29f488efbb 100644
--- a/crates/ui-egui/src/i18n/vi.rs
+++ b/crates/ui-egui/src/i18n/vi.rs
@@ -436,21 +436,11 @@ pub(super) fn translate(text: &str) -> Option<&'static str> {
         "Select a Rule Type" => "Chọn loại quy tắc",
         "Edit the Rule Description" => "Sửa mô tả quy tắc",
         "Format only cells that contain" => "Chỉ định dạng các ô chứa",
-        "Format only top or bottom ranked values" => {
-            "Chỉ định dạng các giá trị có thứ hạng cao nhất hoặc thấp nhất"
-        }
-        "Format only values that are above or below average" => {
-            "Chỉ định dạng các giá trị trên hoặc dưới mức trung bình"
-        }
-        "Format only unique or duplicate values" => {
-            "Chỉ định dạng các giá trị duy nhất hoặc trùng lặp"
-        }
-        "Use a formula to determine which cells to format" => {
-            "Dùng công thức để xác định ô nào cần định dạng"
-        }
-        "Format values where this formula is true:" => {
-            "Định dạng các giá trị mà công thức này đúng:"
-        }
+        "Format only top or bottom ranked values" => "Chỉ định dạng các giá trị có thứ hạng cao nhất hoặc thấp nhất",
+        "Format only values that are above or below average" => "Chỉ định dạng các giá trị trên hoặc dưới mức trung bình",
+        "Format only unique or duplicate values" => "Chỉ định dạng các giá trị duy nhất hoặc trùng lặp",
+        "Use a formula to determine which cells to format" => "Dùng công thức để xác định ô nào cần định dạng",
+        "Format values where this formula is true:" => "Định dạng các giá trị mà công thức này đúng:",
         "with" => "với",
         "This rule type isn't available yet." => "Loại quy tắc này chưa khả dụng.",
         _ => return None,

From 81a8abc12b7ee087ded7fb2966f559630958dedb Mon Sep 17 00:00:00 2001
From: alosslessdev <alosslessdev@users.noreply.github.com>
Date: Sun, 25 Oct 2026 12:20:17 -0500
Subject: [PATCH 07/10] New Formatting Rule: pick grid references for formula
 rules and keep the opening range (#1822)

---
 crates/ui-egui/src/dialogs.rs | 100 ++++++++++++++++++++++++++++++++--
 1 file changed, 94 insertions(+), 6 deletions(-)

diff --git a/crates/ui-egui/src/dialogs.rs b/crates/ui-egui/src/dialogs.rs
index ff655960d3..d2897dac8a 100644
--- a/crates/ui-egui/src/dialogs.rs
+++ b/crates/ui-egui/src/dialogs.rs
@@ -791,6 +791,21 @@ impl Dialog {
                 let theme = app.session.active().map(|d| d.wb.theme.clone()).unwrap_or_default();
                 let mut d = Dialog::custom("newFormattingRule", "New Formatting Rule", new_rule_defaults(&params, &theme));
                 d.command = Some(if params.get("edit").is_some() { "home.manageRules" } else { "home.conditionalFormat" });
+                // The sheet and selection the rule was opened on: Excel's "Applies to" stays put
+                // even if the selection moves or another sheet is shown before OK.
+                let (sheet, applies_to) = app
+                    .session
+                    .active()
+                    .map(|doc| {
+                        (
+                            doc.wb.active().map(|sh| sh.name.clone()).unwrap_or_default(),
+                            doc.selection.ranges.iter().map(RangeRef::a1).collect::<Vec<_>>().join(","),
+                        )
+                    })
+                    .unwrap_or_default();
+                d.values.insert("sheet".into(), json!(sheet));
+                d.values.insert("applies_to".into(), json!(applies_to));
+                sync_rule_pick(&mut d);
                 d
             }
             "formatCells" => {
@@ -1242,7 +1257,14 @@ pub(crate) fn build_params(d: &Dialog) -> Json {
                 "formula" => {
                     let formula = d.values.get("formula").and_then(Json::as_str).unwrap_or("").to_string();
                     let preset = d.values.get("preset").and_then(Json::as_str).unwrap_or("lightRedFillDarkRedText");
-                    json!({"rule": {"type": "expression", "formula": formula, "preset": preset}})
+                    let mut out = json!({"rule": {"type": "expression", "formula": formula, "preset": preset}});
+                    // The rule covers the range and sheet the dialog opened on, not whatever the
+                    // selection shows now.
+                    if let Some(pick) = d.pick.as_ref().filter(|pick| !pick.applies_to.is_empty() && !pick.sheet.is_empty()) {
+                        out["sheet"] = json!(pick.sheet.as_str());
+                        out["range"] = json!(pick.applies_to);
+                    }
+                    out
                 }
                 _ => {
                     let stops: Vec<Json> =
@@ -2207,6 +2229,21 @@ const RULE_TYPES: &[(&str, &str)] = &[
     ("formula", "Use a formula to determine which cells to format"),
 ];
 
+/// Gives a formula rule's box point mode, on the sheet and selection the dialog opened on;
+/// other rule types take clicks on the grid as selection.
+fn sync_rule_pick(d: &mut Dialog) {
+    if d.values.get("ruleType").and_then(Json::as_str) != Some("formula") {
+        d.pick = None;
+        return;
+    }
+    if d.pick.is_some() {
+        return;
+    }
+    let sheet = d.values.get("sheet").and_then(Json::as_str).unwrap_or_default().to_string();
+    let applies_to = d.values.get("applies_to").and_then(Json::as_str).unwrap_or_default().to_string();
+    d.pick = Some(RefPick { key: "formula", sheet, caret: 0, point: None, anchor: CellRef::new(0, 0), refocus: false, applies_to });
+}
+
 fn new_formatting_rule(ui: &mut egui::Ui, d: &mut Dialog, confirm: &mut bool, open: &mut bool) {
     let lang = crate::i18n::current(ui.ctx());
     ui.label(lang.tr("Select a Rule Type"));
@@ -2215,6 +2252,9 @@ fn new_formatting_rule(ui: &mut egui::Ui, d: &mut Dialog, confirm: &mut bool, op
         ui.selectable_value(&mut rule_type, (*v).to_string(), lang.tr(label));
     }
     d.values.insert("ruleType".into(), json!(rule_type));
+    // Only a formula rule's box takes grid references, and it keeps the sheet and "Applies to"
+    // range the dialog opened on.
+    sync_rule_pick(d);
     ui.separator();
     ui.label(lang.tr("Edit the Rule Description"));
     let supported = match rule_type.as_str() {
@@ -2232,9 +2272,13 @@ fn new_formatting_rule(ui: &mut egui::Ui, d: &mut Dialog, confirm: &mut bool, op
         "formula" => {
             ui.label(lang.tr("Format values where this formula is true:"));
             let mut formula = d.values.get("formula").and_then(Json::as_str).unwrap_or("").to_string();
-            if ui.add(egui::TextEdit::singleline(&mut formula).desired_width(360.0)).changed() {
+            let r = ui.add(egui::TextEdit::singleline(&mut formula).desired_width(360.0));
+            if r.changed() {
                 d.values.insert("formula".into(), json!(formula.clone()));
             }
+            if let Some(pick) = d.pick.as_mut().filter(|pick| pick.key == "formula") {
+                track_pick(pick, &r, r.changed());
+            }
             ui.horizontal(|ui| {
                 ui.label(lang.tr("with"));
                 preset_combo(ui, d, lang);
@@ -3754,12 +3798,56 @@ mod tests {
     }
 
     #[test]
-    fn data_validation_without_a_rule_opens_on_a_blank_list() {
+    fn formula_rule_picks_references_and_keeps_the_opening_range() {
         let mut session = gridcraft_engine::Session::default();
         session.new_workbook();
+        session.execute("selection.set", json!({"range": "B2:C5"})).unwrap();
         let mut app = SheetApp::new(session, Default::default());
-        let d = Dialog::open(&mut app, "dataValidation", json!({})).unwrap();
-        assert_eq!(d.values["type"], "list");
-        assert!(d.values.get("formula1").is_none());
+        let sheet = app.session.active().unwrap().wb.active().unwrap().name.clone();
+        let mut d = Dialog::open(&mut app, "newFormattingRule", json!({"ruleType": "formula"})).unwrap();
+        assert!(d.picks_references());
+        assert_eq!(d.pick.as_ref().unwrap().sheet, sheet);
+
+        // A grid click writes the reference into the formula box.
+        d.pick_reference(CellRef::new(0, 0), &sheet, false);
+        assert_eq!(d.values["formula"], "=$A$1");
+
+        // Moving the selection before OK must not move the rule.
+        app.session.execute("selection.set", json!({"range": "D2:E6"})).unwrap();
+        let params = build_params(&d);
+        assert_eq!(params["sheet"], sheet.as_str());
+        assert_eq!(params["range"], "B2:C5");
+    }
+
+    #[test]
+    fn a_rule_switched_to_formula_picks_on_the_opening_scope() {
+        let mut session = gridcraft_engine::Session::default();
+        session.new_workbook();
+        session.execute("selection.set", json!({"range": "B2:C5"})).unwrap();
+        let mut app = SheetApp::new(session, Default::default());
+        let sheet = app.session.active().unwrap().wb.active().unwrap().name.clone();
+        // The dialog opens on the default (colour scale) type; choosing the formula type later
+        // turns point mode on, still on the sheet and range it opened with.
+        let mut d = Dialog::open(&mut app, "newFormattingRule", json!({})).unwrap();
+        assert!(!d.picks_references());
+        d.values.insert("ruleType".into(), json!("formula"));
+        sync_rule_pick(&mut d);
+        assert!(d.picks_references());
+
+        app.session.execute("selection.set", json!({"range": "D2:E6"})).unwrap();
+        let params = build_params(&d);
+        assert_eq!(params["sheet"], sheet.as_str());
+        assert_eq!(params["range"], "B2:C5");
+    }
+
+    #[test]
+    fn colour_scale_rule_does_not_take_grid_references() {
+        let mut session = gridcraft_engine::Session::default();
+        session.new_workbook();
+        session.execute("selection.set", json!({"range": "B2:C5"})).unwrap();
+        let mut app = SheetApp::new(session, Default::default());
+        let d = Dialog::open(&mut app, "newFormattingRule", json!({})).unwrap();
+        assert!(!d.picks_references());
+        assert!(build_params(&d).get("range").is_none());
     }
 }

From 5a035ac5c60f122773c9c223f2f407a9588721eb Mon Sep 17 00:00:00 2001
From: alosslessdev <alosslessdev@users.noreply.github.com>
Date: Sun, 25 Oct 2026 13:04:20 -0500
Subject: [PATCH 08/10] Conditional formatting: keep the opening scope for
 colour scales and reject bad rule params (#1822)

---
 crates/engine/src/cmd/insert.rs          | 41 ++++++++++++++++++++++--
 crates/ui-egui/src/dialogs.rs            | 26 +++++++++------
 crates/ui-egui/tests/color_scale_rule.rs |  9 ++++++
 3 files changed, 64 insertions(+), 12 deletions(-)

diff --git a/crates/engine/src/cmd/insert.rs b/crates/engine/src/cmd/insert.rs
index 45840d7738..b6e7797689 100644
--- a/crates/engine/src/cmd/insert.rs
+++ b/crates/engine/src/cmd/insert.rs
@@ -1631,7 +1631,9 @@ fn cf_rule(rule: &Json, cmd: &str) -> Result<CfRule> {
         }
         "timePeriod" => Ok(CfRule::TimePeriod { period: g("period").unwrap_or_else(|| "today".into()), style }),
         "colorScale" => {
-            let stops = if let Some(list) = rule.get("stops").and_then(Json::as_array) {
+            let stops = if let Some(stops) = rule.get("stops") {
+                // A present but misshapen `stops` is a mistake, not a request for `colors`.
+                let list = stops.as_array().ok_or_else(|| bad(cmd, "`stops` must be an array"))?;
                 let mut out = Vec::with_capacity(list.len().min(3));
                 for stop in list {
                     let color = super::format::color_param(stop.get("color")).ok_or_else(|| bad(cmd, "a colour-scale stop needs a colour"))?;
@@ -1736,9 +1738,12 @@ fn manage_cf(s: &mut Session, p: &Json) -> Result<Json> {
         (Some(_), None) => return Err(bad("home.manageRules", "missing `rule` for an edit")),
         (Some(e), Some(rule)) => {
             let i = e.as_u64().ok_or_else(|| bad("home.manageRules", "`edit` must be a rule index"))?;
+            // A number too large for `usize` on this target names no rule: casting it would
+            // wrap to a real index and replace that rule instead of reporting out of range.
+            let i = usize::try_from(i).map_err(|_| bad("home.manageRules", format!("no conditional format at index {i}")))?;
             let rule = cf_rule(rule, "home.manageRules")?;
             check_cf_rule("home.manageRules", &rule)?;
-            Some((i as usize, rule))
+            Some((i, rule))
         }
     };
     edit(s, |cx| {
@@ -1920,6 +1925,23 @@ mod tests {
         assert_eq!(rules["rules"].as_array().map(Vec::len), Some(0));
     }
 
+    #[test]
+    fn colour_scale_rejects_a_stops_value_that_is_not_an_array() {
+        let mut s = Session::new();
+        s.new_workbook();
+        // `stops` present but misshapen used to fall back to the default scale instead of erroring.
+        for stops in [json!({}), json!(null), json!("min")] {
+            let err = s
+                .execute("home.conditionalFormat", json!({"range": "A1:A3", "rule": {"type": "colorScale", "stops": stops}}))
+                .unwrap_err()
+                .to_string();
+            assert!(err.contains("home.conditionalFormat"), "{err}");
+            assert!(err.contains("`stops` must be an array"), "{err}");
+        }
+        let rules = s.execute("home.manageRules", json!({})).unwrap();
+        assert_eq!(rules["rules"].as_array().map(Vec::len), Some(0), "an invalid `stops` creates no rule");
+    }
+
     #[test]
     fn colour_scale_formulas_are_stored_verbatim() {
         let mut s = Session::new();
@@ -1970,6 +1992,21 @@ mod tests {
         assert_eq!(rules["rules"].as_array().map(Vec::len), Some(1), "the failed edit leaves the rule alone");
     }
 
+    #[test]
+    fn manage_rules_rejects_an_edit_index_that_does_not_fit_a_usize() {
+        let mut s = Session::new();
+        s.new_workbook();
+        s.execute("home.conditionalFormat", json!({"range": "A1:A3", "rule": {"type": "expression", "formula": "A1>2"}})).unwrap();
+        // On a 32-bit target this used to cast to zero and replace the rule at index 0.
+        let err =
+            s.execute("home.manageRules", json!({"edit": 4294967296u64, "rule": {"type": "expression", "formula": "A1>3"}})).unwrap_err().to_string();
+        assert!(err.contains("home.manageRules"), "{err}");
+        assert!(err.contains("index 4294967296"), "{err}");
+        let rule: CfRule = serde_json::from_value(s.execute("home.manageRules", json!({})).unwrap()["rules"][0]["rule"].clone()).unwrap();
+        let CfRule::Expression { formula, .. } = rule else { panic!("expected a formula rule, got {rule:?}") };
+        assert_eq!(formula, "A1>2", "the failed edit leaves the rule alone");
+    }
+
     #[test]
     fn manage_rules_names_itself_in_a_stop_count_error() {
         let mut s = Session::new();
diff --git a/crates/ui-egui/src/dialogs.rs b/crates/ui-egui/src/dialogs.rs
index d2897dac8a..0a126ed09a 100644
--- a/crates/ui-egui/src/dialogs.rs
+++ b/crates/ui-egui/src/dialogs.rs
@@ -1257,14 +1257,7 @@ pub(crate) fn build_params(d: &Dialog) -> Json {
                 "formula" => {
                     let formula = d.values.get("formula").and_then(Json::as_str).unwrap_or("").to_string();
                     let preset = d.values.get("preset").and_then(Json::as_str).unwrap_or("lightRedFillDarkRedText");
-                    let mut out = json!({"rule": {"type": "expression", "formula": formula, "preset": preset}});
-                    // The rule covers the range and sheet the dialog opened on, not whatever the
-                    // selection shows now.
-                    if let Some(pick) = d.pick.as_ref().filter(|pick| !pick.applies_to.is_empty() && !pick.sheet.is_empty()) {
-                        out["sheet"] = json!(pick.sheet.as_str());
-                        out["range"] = json!(pick.applies_to);
-                    }
-                    out
+                    json!({"rule": {"type": "expression", "formula": formula, "preset": preset}})
                 }
                 _ => {
                     let stops: Vec<Json> =
@@ -1272,6 +1265,15 @@ pub(crate) fn build_params(d: &Dialog) -> Json {
                     json!({"rule": {"type": "colorScale", "stops": stops}})
                 }
             };
+            // The rule covers the sheet and range the dialog opened on, not whatever the
+            // selection shows now: a formula rule's pick box holds the same opening scope, and
+            // colour scales have no pick box but need it just as much to edit in place.
+            let sheet = d.values.get("sheet").and_then(Json::as_str).unwrap_or_default();
+            let applies_to = d.values.get("applies_to").and_then(Json::as_str).unwrap_or_default();
+            if !sheet.is_empty() && !applies_to.is_empty() {
+                out["sheet"] = json!(sheet);
+                out["range"] = json!(applies_to);
+            }
             if let Some(edit) = d.values.get("edit").and_then(Json::as_u64) {
                 out["edit"] = json!(edit);
             }
@@ -3841,13 +3843,17 @@ mod tests {
     }
 
     #[test]
-    fn colour_scale_rule_does_not_take_grid_references() {
+    fn colour_scale_rule_keeps_the_opening_range_without_grid_references() {
         let mut session = gridcraft_engine::Session::default();
         session.new_workbook();
         session.execute("selection.set", json!({"range": "B2:C5"})).unwrap();
         let mut app = SheetApp::new(session, Default::default());
+        let sheet = app.session.active().unwrap().wb.active().unwrap().name.clone();
         let d = Dialog::open(&mut app, "newFormattingRule", json!({})).unwrap();
         assert!(!d.picks_references());
-        assert!(build_params(&d).get("range").is_none());
+        // No pick box, but the rule still covers the range and sheet the dialog opened on.
+        let params = build_params(&d);
+        assert_eq!(params["sheet"], sheet.as_str());
+        assert_eq!(params["range"], "B2:C5");
     }
 }
diff --git a/crates/ui-egui/tests/color_scale_rule.rs b/crates/ui-egui/tests/color_scale_rule.rs
index 03fe078b7b..dc36de5d75 100644
--- a/crates/ui-egui/tests/color_scale_rule.rs
+++ b/crates/ui-egui/tests/color_scale_rule.rs
@@ -48,9 +48,18 @@ fn creates_a_three_colour_scale_with_per_stop_thresholds() {
         ]),
     );
     h.run_steps(2);
+    // The rule covers the sheet and range the dialog opened on, not the one shown at OK.
+    h.state_mut().run("home.insertSheet", json!({"name": "Two"})).unwrap();
+    h.state_mut().run("selection.set", json!({"range": "B1:B2"})).unwrap();
+    h.run_steps(2);
     h.get_by_label("   OK   ").click();
     h.run_steps(6);
     assert!(h.state().dialog.is_none());
+    let two = h.state_mut().run("home.manageRules", json!({"sheet": "Two"})).unwrap();
+    assert_eq!(two["rules"].as_array().map(Vec::len), Some(0), "the rule does not land on the sheet shown at OK");
+    let list = h.state_mut().run("home.manageRules", json!({"sheet": "Sheet1"})).unwrap();
+    assert_eq!(list["rules"][0]["ranges"], json!(["A1:A3"]));
+    h.state_mut().run("sheet.activate", json!({"sheet": "Sheet1"})).unwrap();
     assert_eq!(
         stops(&h),
         vec![

From a5b1415c9e8944a8c7aa4e341c7b60627226b88f Mon Sep 17 00:00:00 2001
From: alosslessdev <alosslessdev@users.noreply.github.com>
Date: Sun, 25 Oct 2026 16:10:03 -0500
Subject: [PATCH 09/10] Conditional formatting: translate the rule editor's
 Edit and More Rules labels (#1822)

---
 crates/ui-egui/src/dialogs.rs            |  3 ++-
 crates/ui-egui/src/ribbon.rs             | 18 +++++++++++++++++-
 crates/ui-egui/tests/color_scale_rule.rs | 21 +++++++++++++++++++++
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/crates/ui-egui/src/dialogs.rs b/crates/ui-egui/src/dialogs.rs
index 0a126ed09a..3aa441a8ed 100644
--- a/crates/ui-egui/src/dialogs.rs
+++ b/crates/ui-egui/src/dialogs.rs
@@ -3196,6 +3196,7 @@ fn select_data(app: &mut SheetApp, ui: &mut egui::Ui, d: &mut Dialog, confirm: &
 }
 
 fn manage_rules(app: &mut SheetApp, ui: &mut egui::Ui) {
+    let lang = app.ui.language;
     let list = app.session.run("home.manageRules", json!({})).unwrap_or(Json::Null);
     let rules = list["rules"].as_array().cloned().unwrap_or_default();
     if rules.is_empty() {
@@ -3209,7 +3210,7 @@ fn manage_rules(app: &mut SheetApp, ui: &mut egui::Ui) {
                 i + 1,
                 r["ranges"].as_array().map(|a| a.iter().filter_map(|x| x.as_str()).collect::<Vec<_>>().join(",")).unwrap_or_default()
             ));
-            if kind.contains("ColorScale") && ui.small_button("Edit").clicked() {
+            if kind.contains("ColorScale") && ui.small_button(lang.tr("Edit")).clicked() {
                 app.open_dialog("newFormattingRule", json!({"edit": i, "rule": r["rule"].clone()}));
             }
             if ui.small_button("▲").clicked() {
diff --git a/crates/ui-egui/src/ribbon.rs b/crates/ui-egui/src/ribbon.rs
index 302949cf6e..20f756e895 100644
--- a/crates/ui-egui/src/ribbon.rs
+++ b/crates/ui-egui/src/ribbon.rs
@@ -1417,6 +1417,7 @@ fn number_combo(app: &mut SheetApp, ui: &mut Ui, st: &Style) {
 }
 
 fn cf_menu(app: &mut SheetApp, ui: &mut Ui) {
+    let lang = app.ui.language;
     ui.menu_button("Highlight Cells Rules", |ui| {
         for (label, op) in [("Greater Than…", "greater"), ("Less Than…", "less"), ("Between…", "between"), ("Equal To…", "equal")] {
             if ui.button(label).clicked() {
@@ -1470,7 +1471,7 @@ fn cf_menu(app: &mut SheetApp, ui: &mut Ui) {
             }
         }
         ui.separator();
-        if ui.button("More Rules…").clicked() {
+        if ui.button(lang.tr("More Rules…")).clicked() {
             app.open_dialog("newFormattingRule", json!({"style": "3color"}));
         }
     });
@@ -2989,6 +2990,21 @@ mod ribbon_tests {
         // Formula rules stay reachable: New Rule… shows Excel's rule-type list, formula entry included.
         h.get_by_label("Use a formula to determine which cells to format");
     }
+
+    #[test]
+    fn more_rules_follows_the_interface_language() {
+        let mut session = gridcraft_engine::Session::new();
+        session.new_workbook();
+        let mut app = SheetApp::new(session, Default::default());
+        app.run("app.language.set", serde_json::json!({"language": "es"})).unwrap();
+        let mut h = egui_kittest::Harness::builder().with_size(vec2(900.0, 800.0)).build_ui_state(|ui, app: &mut SheetApp| cf_menu(app, ui), app);
+        h.run_steps(2);
+        h.get_by_label("Color Scales").click();
+        h.run_steps(2);
+        let more = crate::i18n::Language::Es.tr("More Rules…");
+        assert_ne!(more, "More Rules…");
+        assert!(h.query_all_by_label(more).next().is_some(), "More Rules… stays English");
+    }
 }
 
 #[cfg(test)]
diff --git a/crates/ui-egui/tests/color_scale_rule.rs b/crates/ui-egui/tests/color_scale_rule.rs
index dc36de5d75..f7da751ac7 100644
--- a/crates/ui-egui/tests/color_scale_rule.rs
+++ b/crates/ui-egui/tests/color_scale_rule.rs
@@ -5,6 +5,7 @@ use egui_kittest::kittest::Queryable;
 use gridcraft_engine::Session;
 use gridcraft_engine::model::{CfRule, CfValueKind, Color};
 use gridcraft_ui_egui::SheetApp;
+use gridcraft_ui_egui::i18n::Language;
 use serde_json::json;
 
 fn harness() -> egui_kittest::Harness<'static, SheetApp> {
@@ -309,3 +310,23 @@ fn switching_a_numeric_stop_to_formula_needs_a_formula() {
     assert!(h.state().dialog.is_none());
     assert_eq!(stops(&h), vec![(CfValueKind::Formula("$Z$1".into()), Color::Rgb(0x112233)), (CfValueKind::Max, Color::Rgb(0x778899))]);
 }
+
+#[test]
+fn the_rule_list_translates_its_edit_button() {
+    let mut h = harness();
+    h.state_mut()
+        .run(
+            "home.conditionalFormat",
+            json!({"rule": {"type": "colorScale", "stops": [
+                {"type": "min", "color": "#112233"},
+                {"type": "max", "color": "#778899"},
+            ]}}),
+        )
+        .unwrap();
+    h.state_mut().run("app.language.set", json!({"language": Language::Es.code()})).unwrap();
+    h.state_mut().open_dialog("manageRules", json!({}));
+    h.run_steps(6);
+    let edit = Language::Es.tr("Edit");
+    assert_ne!(edit, "Edit");
+    assert!(h.query_all_by_label(edit).next().is_some(), "Edit stays English");
+}

From 18f11876e31bc4b91e73c3368b6819aae8be5f94 Mon Sep 17 00:00:00 2001
From: alosslessdev <alosslessdev@users.noreply.github.com>
Date: Sun, 25 Oct 2026 17:45:30 -0500
Subject: [PATCH 10/10] Tests: restore the data validation dialog test the
 rebase dropped (#1822)

---
 crates/ui-egui/src/dialogs.rs | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/crates/ui-egui/src/dialogs.rs b/crates/ui-egui/src/dialogs.rs
index 3aa441a8ed..a86640be19 100644
--- a/crates/ui-egui/src/dialogs.rs
+++ b/crates/ui-egui/src/dialogs.rs
@@ -3800,6 +3800,16 @@ mod tests {
         assert!(gridcraft_engine::cmd::data::check_validation(&doc.wb, 0, at, "4").is_some());
     }
 
+    #[test]
+    fn data_validation_without_a_rule_opens_on_a_blank_list() {
+        let mut session = gridcraft_engine::Session::default();
+        session.new_workbook();
+        let mut app = SheetApp::new(session, Default::default());
+        let d = Dialog::open(&mut app, "dataValidation", json!({})).unwrap();
+        assert_eq!(d.values["type"], "list");
+        assert!(d.values.get("formula1").is_none());
+    }
+
     #[test]
     fn formula_rule_picks_references_and_keeps_the_opening_range() {
         let mut session = gridcraft_engine::Session::default();