From f745a722f1f8587184ebc24e04fa70627ca25be4 Mon Sep 17 00:00:00 2001
From: "William J. Bowman" <wjb@williamjbowman.com>
Date: Thu, 9 Jul 2026 22:21:31 +0000
Subject: [PATCH] Fix hyperref label mismatch for tech/def cross-references in
 LaTeX

When rendering `@tech` links with `#:tag-prefixes`, the resolved destination
tag (e.g. `(tech "chp1:" "book:" "widget")`) differs from the raw
link-element tag (e.g. `(tech ("book:" "chp1:" "widget"))`), causing
`\hyperref` to reference a label that does not exist.

The section/part rendering path appears to handle this by using
`(vector-ref dest 1)` from the resolved destination rather than
`(link-element-tag e)`. Adapt the same pattern for tech/def refs.
---
 scribble-lib/scribble/latex-render.rkt        |  4 +-
 .../tests/scribble/latex-tech-hyperref.rkt    | 54 +++++++++++++++++++
 2 files changed, 56 insertions(+), 2 deletions(-)
 create mode 100644 scribble-test/tests/scribble/latex-tech-hyperref.rkt

diff --git a/scribble-lib/scribble/latex-render.rkt b/scribble-lib/scribble/latex-render.rkt
index 61435ddcce..a3392b35a9 100644
--- a/scribble-lib/scribble/latex-render.rkt
+++ b/scribble-lib/scribble/latex-render.rkt
@@ -402,7 +402,7 @@
                                  (link-element? e)
                                  (not (disable-hyperref))
                                  (let-values ([(dest ext?) (resolve-get/ext? part ri (link-element-tag e))])
-                                   (and dest (not ext?))))]
+                                   (and (not ext?) dest)))]
                  [check-render
                   (lambda ()
                     (when (render-element? e)
@@ -544,7 +544,7 @@
                 (core-render e tt?)]))
             (when hyperref?
               (printf "\\hyperref[t:~a]{"
-                      (t-encode (link-element-tag e))))
+                      (t-encode (vector-ref hyperref? 1))))
             (let loop ([l (if style (style-properties style) null)] [tt? #f])
               (if (null? l)
                   (if hyperref?
diff --git a/scribble-test/tests/scribble/latex-tech-hyperref.rkt b/scribble-test/tests/scribble/latex-tech-hyperref.rkt
new file mode 100644
index 0000000000..b514cf6ff2
--- /dev/null
+++ b/scribble-test/tests/scribble/latex-tech-hyperref.rkt
@@ -0,0 +1,54 @@
+#lang racket/base
+
+(require racket/file
+         rackunit
+         scribble/core
+         scribble/latex-render
+         scribble/manual
+         scribble/render)
+
+(define (latex-render-string doc)
+  (dynamic-wind
+   (λ() (render (list doc)
+                (list "example-for-latex-tech-hyperref-test")
+                #:render-mixin render-mixin))
+   (λ() (file->string "example-for-latex-tech-hyperref-test.tex"))
+   (λ() (delete-file "example-for-latex-tech-hyperref-test.tex"))))
+
+; Regression test: when @tech is used with #:tag-prefixes, the resolved
+; destination tag must be used for \hyperref rather than the raw link-element
+; tag, so that \hyperref and \label refer to the same anchor.
+(test-case "tech hyperref tag matches deftech label tag when using tag-prefixes"
+  (define str
+    (latex-render-string
+     (part "book:"
+           '((part "top"))
+           '("Doc")
+           (style #f null)
+           null
+           null
+           (list
+            (part "chp1:"
+                  '((part "chp1"))
+                  '("Chapter One")
+                  (style #f null)
+                  null
+                  (list (paragraph (style #f null) (list (deftech "widget"))))
+                  null)
+            (part #f
+                  '((part "sec2"))
+                  '("Section Two")
+                  (style #f null)
+                  null
+                  (list (paragraph (style #f null)
+                                   (list (tech #:tag-prefixes '("book:" "chp1:") "widget"))))
+                  null)))))
+
+  (define label-m
+    (regexp-match #rx"\\\\label\\{(t:[a-z0-9:_]+)\\}\\\\textit\\{widget\\}" str))
+  (define href-m
+    (regexp-match #rx"\\\\hyperref\\[(t:[a-z0-9:_]+)\\]" str))
+
+  (check-not-false (and label-m href-m) "both \\label and \\hyperref for tech term must appear")
+  (check-equal? (cadr label-m) (cadr href-m)
+                "\\hyperref tag must match \\label tag for tech term"))