From 2ef0efcceb897a31535b84ded874113124508aec Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Edu=20Gonz=C3=A1lez=20de=20la=20Herr=C3=A1n?=
 <25320357+eedugon@users.noreply.github.com>
Date: Tue, 13 Jan 2026 11:32:40 +0100
Subject: [PATCH 1/3] initial attempt

---
 docs/syntax/substitutions.md                  |  3 ++
 docs/syntax/version-variables.md              |  1 +
 .../SubstitutionMutationHelper.cs             |  1 +
 .../Substitution/SubstitutionParser.cs        |  1 +
 .../Inline/SubstitutionTest.cs                | 36 ++++++++++++++++++-
 .../authoring/Inline/SubstitutionMutations.fs |  2 ++
 6 files changed, 43 insertions(+), 1 deletion(-)

diff --git a/docs/syntax/substitutions.md b/docs/syntax/substitutions.md
index 331cfd44a..43a8ea351 100644
--- a/docs/syntax/substitutions.md
+++ b/docs/syntax/substitutions.md
@@ -78,6 +78,7 @@ For variables declaring a semantic version or `Major.Minor` the following operat
 | `M.M`    | Display only the major and the minor     |
 | `M+1`    | The next major version                   |
 | `M.M+1`  | The next minor version                   |
+| `M.M-1`  | The previous minor version (returns original value if minor is 0) |
 
 ### Example
 
@@ -109,6 +110,7 @@ sub:
 * M+1: {{version.stack | M+1 }}
 * M+1 | M.M: {{version.stack | M+1 | M.M }}
 * M.M+1: {{version.stack | M.M+1 }}
+* M.M-1: {{version.stack | M.M-1 }}
 
 :::
 
@@ -130,6 +132,7 @@ sub:
 * M+1: {{version.stack | M+1 }}
 * M+1 | M.M: {{version.stack | M+1 | M.M }}
 * M.M+1: {{version.stack | M.M+1 }}
+* M.M-1: {{version.stack | M.M-1 }}
 ````
 :::
 
diff --git a/docs/syntax/version-variables.md b/docs/syntax/version-variables.md
index f841d63a6..0285f4a83 100644
--- a/docs/syntax/version-variables.md
+++ b/docs/syntax/version-variables.md
@@ -25,6 +25,7 @@ can be printed in any kind of ways.
 | `{{version.stack.base | M }}`     | {{version.stack.base | M }} |
 | `{{version.stack | M+1       | M }}` | {{version.stack | M+1 | M }} |
 | `{{version.stack.base | M.M+1 }}` | {{version.stack.base | M.M+1 }} |
+| `{{version.stack | M.M-1 }}` | {{version.stack | M.M-1 }} |
 
 ## Mutation Operators in Links and Code Blocks
 
diff --git a/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionMutationHelper.cs b/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionMutationHelper.cs
index f5e696a9c..9bb69fe97 100644
--- a/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionMutationHelper.cs
+++ b/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionMutationHelper.cs
@@ -74,6 +74,7 @@ private static string ApplySingleMutation(string value, SubstitutionMutation mut
 			SubstitutionMutation.MajorMinor => TryGetVersion(value, v => $"{v.Major}.{v.Minor}"),
 			SubstitutionMutation.IncreaseMajor => TryGetVersion(value, v => $"{v.Major + 1}.0.0"),
 			SubstitutionMutation.IncreaseMinor => TryGetVersion(value, v => $"{v.Major}.{v.Minor + 1}.0"),
+			SubstitutionMutation.DecreaseMinor => TryGetVersion(value, v => v.Minor == 0 ? value : $"{v.Major}.{v.Minor - 1}.0"),
 			SubstitutionMutation.LowerCase => (true, value.ToLowerInvariant()),
 			SubstitutionMutation.UpperCase => (true, value.ToUpperInvariant()),
 			SubstitutionMutation.Capitalize => (true, Capitalize(value)),
diff --git a/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionParser.cs b/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionParser.cs
index 78c29dc8f..4f59fe8fb 100644
--- a/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionParser.cs
+++ b/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionParser.cs
@@ -34,6 +34,7 @@ public enum SubstitutionMutation
 	[Display(Name = "M.M")] MajorMinor,
 	[Display(Name = "M+1")] IncreaseMajor,
 	[Display(Name = "M.M+1")] IncreaseMinor,
+	[Display(Name = "M.M-1")] DecreaseMinor,
 	[Display(Name = "lc")] LowerCase,
 	[Display(Name = "uc")] UpperCase,
 	[Display(Name = "tc")] TitleCase,
diff --git a/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs b/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs
index 079970d6b..d5ae1ba26 100644
--- a/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs
+++ b/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs
@@ -225,6 +225,8 @@ public class MutationOperatorTest(ITestOutputHelper output) : InlineTest(output,
 Increase major with space: {{version | M+1}}
 Increase minor: {{version|M.M+1}}
 Increase minor with space: {{version | M.M+1}}
+Decrease minor: {{version|M.M-1}}
+Decrease minor with space: {{version | M.M-1}}
 """
 )
 {
@@ -241,7 +243,39 @@ public void MutationOperatorsWorkWithAndWithoutSpaces()
 			.And.Contain("Increase major: 10.0.0")
 			.And.Contain("Increase major with space: 10.0.0")
 			.And.Contain("Increase minor: 9.1.0")
-			.And.Contain("Increase minor with space: 9.1.0");
+			.And.Contain("Increase minor with space: 9.1.0")
+			.And.Contain("Decrease minor: 9.0.4")
+			.And.Contain("Decrease minor with space: 9.0.4");
+	}
+
+	[Fact]
+	public void HasNoErrors() => Collector.Diagnostics.Should().HaveCount(0);
+}
+
+public class DecreaseMinorMutationTest(ITestOutputHelper output) : InlineTest(output,
+"""
+---
+sub:
+  version-with-minor: "9.2.3"
+  version-with-zero-minor: "9.0.4"
+---
+
+# Testing Decrease Minor Mutation
+
+Version with minor > 0: {{version-with-minor|M.M-1}}
+Version with minor > 0 and M.M: {{version-with-minor|M.M-1|M.M}}
+Version with minor = 0: {{version-with-zero-minor|M.M-1}}
+"""
+)
+{
+	[Fact]
+	public void DecreaseMinorWorksCorrectly()
+	{
+		// When minor > 0, should decrease minor
+		Html.Should().Contain("Version with minor > 0: 9.1.0")
+			.And.Contain("Version with minor > 0 and M.M: 9.1")
+			// When minor = 0, should return original value
+			.And.Contain("Version with minor = 0: 9.0.4");
 	}
 
 	[Fact]
diff --git a/tests/authoring/Inline/SubstitutionMutations.fs b/tests/authoring/Inline/SubstitutionMutations.fs
index 50600f0ee..5bbc5f263 100644
--- a/tests/authoring/Inline/SubstitutionMutations.fs
+++ b/tests/authoring/Inline/SubstitutionMutations.fs
@@ -28,6 +28,7 @@ sub:
 * M+1: {{versions.stack | M+1 }}
 * M+1 | M.M: {{versions.stack | M+1 | M.M }}
 * M.M+1: {{versions.stack | M.M+1 }}
+* M.M-1: {{versions.stack | M.M-1 }}
 """
 
     [<Fact>]
@@ -48,5 +49,6 @@ sub:
  	<li>M+1: 10.0.0</li>
  	<li>M+1 | M.M: 10.0</li>
  	<li>M.M+1: 9.2.0</li>
+ 	<li>M.M-1: 9.0.0</li>
  </ul>
         """

From 28a3a20a2cd38fe7c01426fab0ca629b63c37fe5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Edu=20Gonz=C3=A1lez=20de=20la=20Herr=C3=A1n?=
 <25320357+eedugon@users.noreply.github.com>
Date: Tue, 13 Jan 2026 11:52:49 +0100
Subject: [PATCH 2/3] unit test updated

---
 .../Inline/SubstitutionTest.cs                       | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs b/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs
index d5ae1ba26..3415c1992 100644
--- a/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs
+++ b/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs
@@ -262,9 +262,9 @@ public class DecreaseMinorMutationTest(ITestOutputHelper output) : InlineTest(ou
 
 # Testing Decrease Minor Mutation
 
-Version with minor > 0: {{version-with-minor|M.M-1}}
-Version with minor > 0 and M.M: {{version-with-minor|M.M-1|M.M}}
-Version with minor = 0: {{version-with-zero-minor|M.M-1}}
+Version with minor greater than 0: {{version-with-minor|M.M-1}}
+Version with minor greater than 0 and M.M: {{version-with-minor|M.M-1|M.M}}
+Version with minor 0: {{version-with-zero-minor|M.M-1}}
 """
 )
 {
@@ -272,10 +272,10 @@ public class DecreaseMinorMutationTest(ITestOutputHelper output) : InlineTest(ou
 	public void DecreaseMinorWorksCorrectly()
 	{
 		// When minor > 0, should decrease minor
-		Html.Should().Contain("Version with minor > 0: 9.1.0")
-			.And.Contain("Version with minor > 0 and M.M: 9.1")
+		Html.Should().Contain("Version with minor greater than 0: 9.1.0")
+			.And.Contain("Version with minor greater than 0 and M.M: 9.1")
 			// When minor = 0, should return original value
-			.And.Contain("Version with minor = 0: 9.0.4");
+			.And.Contain("Version with minor 0: 9.0.4");
 	}
 
 	[Fact]

From a1044319de2cfaffe50e8f4be19e19efbf9f74bd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Edu=20Gonz=C3=A1lez=20de=20la=20Herr=C3=A1n?=
 <25320357+eedugon@users.noreply.github.com>
Date: Wed, 14 Jan 2026 10:43:11 +0100
Subject: [PATCH 3/3] decrease major implemented

---
 docs/syntax/substitutions.md                  |  3 ++
 docs/syntax/version-variables.md              |  1 +
 .../SubstitutionMutationHelper.cs             |  1 +
 .../Substitution/SubstitutionParser.cs        |  1 +
 .../Inline/SubstitutionTest.cs                | 34 +++++++++++++++++++
 .../authoring/Inline/SubstitutionMutations.fs |  2 ++
 6 files changed, 42 insertions(+)

diff --git a/docs/syntax/substitutions.md b/docs/syntax/substitutions.md
index 43a8ea351..89200e910 100644
--- a/docs/syntax/substitutions.md
+++ b/docs/syntax/substitutions.md
@@ -77,6 +77,7 @@ For variables declaring a semantic version or `Major.Minor` the following operat
 | `M.x`    | Display major component followed by '.x' |
 | `M.M`    | Display only the major and the minor     |
 | `M+1`    | The next major version                   |
+| `M-1`    | The previous major version (returns original value if major is 0) |
 | `M.M+1`  | The next minor version                   |
 | `M.M-1`  | The previous minor version (returns original value if minor is 0) |
 
@@ -108,6 +109,7 @@ sub:
 * M.M: {{version.stack | M.M }}
 * M: {{version.stack | M }}
 * M+1: {{version.stack | M+1 }}
+* M-1: {{version.stack | M-1 }}
 * M+1 | M.M: {{version.stack | M+1 | M.M }}
 * M.M+1: {{version.stack | M.M+1 }}
 * M.M-1: {{version.stack | M.M-1 }}
@@ -130,6 +132,7 @@ sub:
 * M.M: {{version.stack | M.M }}
 * M: {{version.stack | M }}
 * M+1: {{version.stack | M+1 }}
+* M-1: {{version.stack | M-1 }}
 * M+1 | M.M: {{version.stack | M+1 | M.M }}
 * M.M+1: {{version.stack | M.M+1 }}
 * M.M-1: {{version.stack | M.M-1 }}
diff --git a/docs/syntax/version-variables.md b/docs/syntax/version-variables.md
index 0285f4a83..9365029d9 100644
--- a/docs/syntax/version-variables.md
+++ b/docs/syntax/version-variables.md
@@ -24,6 +24,7 @@ can be printed in any kind of ways.
 | `{{version.stack| M.M}}`    |  {{version.stack|M.M}} |
 | `{{version.stack.base | M }}`     | {{version.stack.base | M }} |
 | `{{version.stack | M+1       | M }}` | {{version.stack | M+1 | M }} |
+| `{{version.stack | M-1 }}` | {{version.stack | M-1 }} |
 | `{{version.stack.base | M.M+1 }}` | {{version.stack.base | M.M+1 }} |
 | `{{version.stack | M.M-1 }}` | {{version.stack | M.M-1 }} |
 
diff --git a/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionMutationHelper.cs b/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionMutationHelper.cs
index 9bb69fe97..0edc56818 100644
--- a/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionMutationHelper.cs
+++ b/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionMutationHelper.cs
@@ -73,6 +73,7 @@ private static string ApplySingleMutation(string value, SubstitutionMutation mut
 			SubstitutionMutation.MajorX => TryGetVersion(value, v => $"{v.Major}.x"),
 			SubstitutionMutation.MajorMinor => TryGetVersion(value, v => $"{v.Major}.{v.Minor}"),
 			SubstitutionMutation.IncreaseMajor => TryGetVersion(value, v => $"{v.Major + 1}.0.0"),
+			SubstitutionMutation.DecreaseMajor => TryGetVersion(value, v => v.Major == 0 ? value : $"{v.Major - 1}.0.0"),
 			SubstitutionMutation.IncreaseMinor => TryGetVersion(value, v => $"{v.Major}.{v.Minor + 1}.0"),
 			SubstitutionMutation.DecreaseMinor => TryGetVersion(value, v => v.Minor == 0 ? value : $"{v.Major}.{v.Minor - 1}.0"),
 			SubstitutionMutation.LowerCase => (true, value.ToLowerInvariant()),
diff --git a/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionParser.cs b/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionParser.cs
index 4f59fe8fb..81e9a8e1f 100644
--- a/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionParser.cs
+++ b/src/Elastic.Markdown/Myst/InlineParsers/Substitution/SubstitutionParser.cs
@@ -33,6 +33,7 @@ public enum SubstitutionMutation
 	[Display(Name = "M.x")] MajorX,
 	[Display(Name = "M.M")] MajorMinor,
 	[Display(Name = "M+1")] IncreaseMajor,
+	[Display(Name = "M-1")] DecreaseMajor,
 	[Display(Name = "M.M+1")] IncreaseMinor,
 	[Display(Name = "M.M-1")] DecreaseMinor,
 	[Display(Name = "lc")] LowerCase,
diff --git a/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs b/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs
index 3415c1992..c6b5d762a 100644
--- a/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs
+++ b/tests/Elastic.Markdown.Tests/Inline/SubstitutionTest.cs
@@ -223,6 +223,8 @@ public class MutationOperatorTest(ITestOutputHelper output) : InlineTest(output,
 Major.x with space: {{version | M.x}}
 Increase major: {{version|M+1}}
 Increase major with space: {{version | M+1}}
+Decrease major: {{version|M-1}}
+Decrease major with space: {{version | M-1}}
 Increase minor: {{version|M.M+1}}
 Increase minor with space: {{version | M.M+1}}
 Decrease minor: {{version|M.M-1}}
@@ -242,6 +244,8 @@ public void MutationOperatorsWorkWithAndWithoutSpaces()
 			.And.Contain("Major.x with space: 9.x")
 			.And.Contain("Increase major: 10.0.0")
 			.And.Contain("Increase major with space: 10.0.0")
+			.And.Contain("Decrease major: 8.0.0")
+			.And.Contain("Decrease major with space: 8.0.0")
 			.And.Contain("Increase minor: 9.1.0")
 			.And.Contain("Increase minor with space: 9.1.0")
 			.And.Contain("Decrease minor: 9.0.4")
@@ -282,6 +286,36 @@ public void DecreaseMinorWorksCorrectly()
 	public void HasNoErrors() => Collector.Diagnostics.Should().HaveCount(0);
 }
 
+public class DecreaseMajorMutationTest(ITestOutputHelper output) : InlineTest(output,
+"""
+---
+sub:
+  version-with-major: "9.2.3"
+  version-with-zero-major: "0.5.2"
+---
+
+# Testing Decrease Major Mutation
+
+Version with major greater than 0: {{version-with-major|M-1}}
+Version with major greater than 0 and M.M: {{version-with-major|M-1|M.M}}
+Version with major 0: {{version-with-zero-major|M-1}}
+"""
+)
+{
+	[Fact]
+	public void DecreaseMajorWorksCorrectly()
+	{
+		// When major > 0, should decrease major and set minor/patch to 0
+		Html.Should().Contain("Version with major greater than 0: 8.0.0")
+			.And.Contain("Version with major greater than 0 and M.M: 8.0")
+			// When major = 0, should return original value
+			.And.Contain("Version with major 0: 0.5.2");
+	}
+
+	[Fact]
+	public void HasNoErrors() => Collector.Diagnostics.Should().HaveCount(0);
+}
+
 public class MultipleMutationOperatorsTest(ITestOutputHelper output) : InlineTest(output,
 """
 ---
diff --git a/tests/authoring/Inline/SubstitutionMutations.fs b/tests/authoring/Inline/SubstitutionMutations.fs
index 5bbc5f263..067f8a005 100644
--- a/tests/authoring/Inline/SubstitutionMutations.fs
+++ b/tests/authoring/Inline/SubstitutionMutations.fs
@@ -26,6 +26,7 @@ sub:
 * M.M: {{versions.stack | M.M }}
 * M: {{versions.stack | M }}
 * M+1: {{versions.stack | M+1 }}
+* M-1: {{versions.stack | M-1 }}
 * M+1 | M.M: {{versions.stack | M+1 | M.M }}
 * M.M+1: {{versions.stack | M.M+1 }}
 * M.M-1: {{versions.stack | M.M-1 }}
@@ -47,6 +48,7 @@ sub:
  	<li>M.M: 9.1</li>
  	<li>M: 9</li>
  	<li>M+1: 10.0.0</li>
+ 	<li>M-1: 8.0.0</li>
  	<li>M+1 | M.M: 10.0</li>
  	<li>M.M+1: 9.2.0</li>
  	<li>M.M-1: 9.0.0</li>