From e9ce8cf4da9062d85098042044822100889bb0dd Mon Sep 17 00:00:00 2001
From: Krishna Upadhyay <24423580+kriss-u@users.noreply.github.com>
Date: Thu, 10 Jul 2025 21:39:19 -0500
Subject: [PATCH 1/2] fix: trim the direction string in flowchart

---
 .changeset/smart-humans-cover.md                  | 5 +++++
 packages/mermaid/src/diagrams/flowchart/flowDb.ts | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)
 create mode 100644 .changeset/smart-humans-cover.md

diff --git a/.changeset/smart-humans-cover.md b/.changeset/smart-humans-cover.md
new file mode 100644
index 000000000..4408e0a9c
--- /dev/null
+++ b/.changeset/smart-humans-cover.md
@@ -0,0 +1,5 @@
+---
+'mermaid': patch
+---
+
+fix: Update flowchart direction TD's behavior to be the same as TB
diff --git a/packages/mermaid/src/diagrams/flowchart/flowDb.ts b/packages/mermaid/src/diagrams/flowchart/flowDb.ts
index 65f8c4a05..303ad0e66 100644
--- a/packages/mermaid/src/diagrams/flowchart/flowDb.ts
+++ b/packages/mermaid/src/diagrams/flowchart/flowDb.ts
@@ -403,7 +403,8 @@ You have to call mermaid.initialize.`
    *
    */
   public setDirection(dir: string) {
-    this.direction = dir;
+    this.direction = dir.trim();
+
     if (/.*</.exec(this.direction)) {
       this.direction = 'RL';
     }

From 98bf9b4cb4e3f6bbda27650975891fe117489a66 Mon Sep 17 00:00:00 2001
From: Krishna Upadhyay <24423580+kriss-u@users.noreply.github.com>
Date: Thu, 10 Jul 2025 22:17:30 -0500
Subject: [PATCH 2/2] test: add tests for directions in flowchart

---
 .../src/diagrams/flowchart/flowDb.spec.ts       | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/packages/mermaid/src/diagrams/flowchart/flowDb.spec.ts b/packages/mermaid/src/diagrams/flowchart/flowDb.spec.ts
index 8d12de00b..56d3cfb57 100644
--- a/packages/mermaid/src/diagrams/flowchart/flowDb.spec.ts
+++ b/packages/mermaid/src/diagrams/flowchart/flowDb.spec.ts
@@ -126,3 +126,20 @@ describe('flow db getData', () => {
     expect(edges[0].curve).toBe('basis');
   });
 });
+
+describe('flow db direction', () => {
+  let flowDb: FlowDB;
+  beforeEach(() => {
+    flowDb = new FlowDB();
+  });
+
+  it('should set direction to TB when TD is set', () => {
+    flowDb.setDirection('TD');
+    expect(flowDb.getDirection()).toBe('TB');
+  });
+
+  it('should correctly set direction irrespective of leading spaces', () => {
+    flowDb.setDirection(' TD');
+    expect(flowDb.getDirection()).toBe('TB');
+  });
+});