diff --git a/.cspell/code-terms.txt b/.cspell/code-terms.txt
index 5f72ea22130..8b44cbb9c68 100644
--- a/.cspell/code-terms.txt
+++ b/.cspell/code-terms.txt
@@ -89,6 +89,7 @@ MULT
NODIR
NSTR
outdir
+parsererror
Qcontrolx
QSTR
reinit
diff --git a/.gitignore b/.gitignore
index 7eb55d5cbab..7931d1ed618 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,7 @@ coverage/
dist
v8-compile-cache-0
+node-compile-cache/
yarn-error.log
.npmrc
diff --git a/demos/sandboxBaseUrl-test.html b/demos/sandboxBaseUrl-test.html
new file mode 100644
index 00000000000..3bec452da2b
--- /dev/null
+++ b/demos/sandboxBaseUrl-test.html
@@ -0,0 +1,294 @@
+
+
+
+
+
+ sandboxBaseUrl Feature Test
+
+
+
+ 🧪 sandboxBaseUrl Feature Test
+
+
+ What this tests: The sandboxBaseUrl config option enables
+ relative URLs in diagram links to work correctly when using
+ securityLevel: 'sandbox'.
+
+
+
+
Before testing: You need to build mermaid first. Run from the repo root:
+
pnpm install && pnpm build
+
+
Test 1: With sandboxBaseUrl (should work)
+
+ Expected: Clicking "Details Page" should navigate to the resolved URL
+ (shown in browser console). Clicking "GitHub" should open GitHub.
+
+
+
+flowchart TD
+ A[Home Page] --> B[Details Page]
+ A --> C[GitHub]
+
+ click A "./" "Go to current directory"
+ click B "./details.html" "View details page"
+ click C "https://github.com/mermaid-js/mermaid" "View GitHub"
+
+
+
+
Test 2: Without sandboxBaseUrl (relative links won't work)
+
+ Expected: Clicking "Details Page" will fail (navigate to
+ about:blank#blocked). Clicking "GitHub" should still work (absolute URL).
+
+
+
+flowchart TD
+ A[Home Page] --> B[Details Page]
+ A --> C[GitHub]
+
+ click A "./" "Go to current directory"
+ click B "./details.html" "View details page"
+ click C "https://github.com/mermaid-js/mermaid" "View GitHub"
+
+
+
+
Test 3: Various URL Types with sandboxBaseUrl
+
+ Tests different URL patterns: relative (./, ../), absolute (/), hash (#), and external
+ (https://)
+
+
+
+flowchart LR
+ A[Relative ./] --> B[Parent ../]
+ B --> C[Absolute /]
+ C --> D[Hash #section]
+ D --> E[External URL]
+
+ click A "./page.html" "Relative path"
+ click B "../parent.html" "Parent directory"
+ click C "/root.html" "Absolute path"
+ click D "#test-section" "Hash link"
+ click E "https://mermaid.js.org" "External site"
+
+
+
+
Test 4: Strict Mode (non-sandbox) - Links Disabled
+
+ In strict mode, click functionality is disabled entirely (this is expected
+ behavior).
+
+
+
+flowchart TD
+ A[Click me] --> B[Won't work]
+ click A "https://github.com" "This link is disabled in strict mode"
+
+
+
+
Console Output
+
+ Check the browser console (F12) for resolved URLs and any errors.
+
+
+ Waiting for mermaid to load...
+
+