The page cache is one directory per document; the shipped suites measure under a UTF-8 locale (from dev 3321e7c9e36e)

sks/document/document_class.cpp

@@ -1,4 +1,6 @@
 #include "util.h"
+#include <functional>
+#include <sstream>
 #include "machine.h"
 #include "error.h"
 #include "kutil.h"
@@ -133,6 +135,30 @@ Document_class::Document_class(Machine& machine) : Klammer_base(machine)
 }
 
 
+// The cache directory of ONE document: the target's cache directory
+// (_latex_files, _html_pages) with a subdirectory per document, named by
+// the document's stem and a hash of its absolute path.  The cache used to
+// be one directory per target with an entry per chapter BASENAME, shared by
+// every document on the machine, and freshness is only "the source is
+// older than the entry": document A's kt/alpha.kt was served document B's
+// cached alpha whenever B had rendered later -- silently when the chapter
+// assembled, with B's error message when it did not (TODO 79, 2026-10-19).
+// The hash, not the path itself: a path can be long and hold any
+// character; the stem is for the eye.  A document given as a string
+// (ktext -s) has no file and is keyed by the working directory, where its
+// _text.kt is rewritten on every run.
+std::string Document_class::document_cache_directory(const std::string& target_cache) const
+{
+    const fs::path document = m_kt_root_filename.empty()
+        ? fs::current_path() / "_string_input"
+        : fs::absolute(fs::path(m_kt_root_filename)).lexically_normal();
+    std::ostringstream key;
+    key << document.stem().string() << "-" << std::hex
+        << std::hash<std::string>{}(document.generic_string());
+    return cache_directory(target_cache + "/" + key.str());
+}
+
+
 void Document_class::save_string_input_as_file()
 {
     if (!m_text.empty()) {