From 9fcdfd976acd3fc3babe45b98425c2af568c15ac Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 27 Nov 2025 11:48:16 +0000
Subject: [PATCH 1/8] Initial plan


From c9ac77a2b7fc4bbaa2507537fdb36dd5c08fb85f Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 27 Nov 2025 11:54:48 +0000
Subject: [PATCH 2/8] Add must-revalidate to Cache-Control header for better
 cache invalidation

Co-authored-by: DedeHai <6280424+DedeHai@users.noreply.github.com>
---
 wled00/wled_server.cpp | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/wled00/wled_server.cpp b/wled00/wled_server.cpp
index d899d3113b..35c3c1c2fa 100644
--- a/wled00/wled_server.cpp
+++ b/wled00/wled_server.cpp
@@ -78,7 +78,8 @@ static void setStaticContentCacheHeaders(AsyncWebServerResponse *response, int c
   #ifndef WLED_DEBUG
   // this header name is misleading, "no-cache" will not disable cache,
   // it just revalidates on every load using the "If-None-Match" header with the last ETag value
-  response->addHeader(FPSTR(s_cache_control), F("no-cache"));
+  // must-revalidate ensures the browser MUST check with the server before using cached content
+  response->addHeader(FPSTR(s_cache_control), F("no-cache, must-revalidate"));
   #else
   response->addHeader(FPSTR(s_cache_control), F("no-store,max-age=0"));  // prevent caching if debug build
   #endif

From 2dfe09e1b52cba678c841f88cba5f1f4b3afd792 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 27 Nov 2025 11:55:55 +0000
Subject: [PATCH 3/8] Add must-revalidate to Cache-Control header for better
 cache invalidation

Co-authored-by: DedeHai <6280424+DedeHai@users.noreply.github.com>
---
 _codeql_detected_source_root | 1 +
 1 file changed, 1 insertion(+)
 create mode 120000 _codeql_detected_source_root

diff --git a/_codeql_detected_source_root b/_codeql_detected_source_root
new file mode 120000
index 0000000000..945c9b46d6
--- /dev/null
+++ b/_codeql_detected_source_root
@@ -0,0 +1 @@
+.
\ No newline at end of file

From 441bd62ad6c6789fa9f394c8f488f079d01e7433 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 27 Nov 2025 11:56:17 +0000
Subject: [PATCH 4/8] Remove CodeQL artifact and add to gitignore

Co-authored-by: DedeHai <6280424+DedeHai@users.noreply.github.com>
---
 .gitignore                   | 1 +
 _codeql_detected_source_root | 1 -
 2 files changed, 1 insertion(+), 1 deletion(-)
 delete mode 120000 _codeql_detected_source_root

diff --git a/.gitignore b/.gitignore
index ec9d4efcc3..256d7260c8 100644
--- a/.gitignore
+++ b/.gitignore
@@ -25,3 +25,4 @@ wled-update.sh
 /wled00/Release
 /wled00/wled00.ino.cpp
 /wled00/html_*.h
+_codeql*
diff --git a/_codeql_detected_source_root b/_codeql_detected_source_root
deleted file mode 120000
index 945c9b46d6..0000000000
--- a/_codeql_detected_source_root
+++ /dev/null
@@ -1 +0,0 @@
-.
\ No newline at end of file

From 54f650a0e903688727374114c518fb1c19cd7b97 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 27 Nov 2025 13:00:02 +0000
Subject: [PATCH 5/8] Add WEB_BUILD_TIME to html_ui.h and use it for ETag
 generation

Co-authored-by: DedeHai <6280424+DedeHai@users.noreply.github.com>
---
 tools/cdata.js         | 14 ++++++++++++++
 wled00/wled_server.cpp |  2 +-
 2 files changed, 15 insertions(+), 1 deletion(-)

diff --git a/tools/cdata.js b/tools/cdata.js
index c569a6f2aa..01921dd1d8 100644
--- a/tools/cdata.js
+++ b/tools/cdata.js
@@ -38,6 +38,17 @@ const wledBanner = `
 \t\t\x1b[36m build script for web UI
 \x1b[0m`;
 
+// Generate build timestamp in format compatible with VERSION (yymmddb)
+function generateBuildTime() {
+  const now = new Date();
+  const yy = String(now.getFullYear() % 100).padStart(2, '0');
+  const mm = String(now.getMonth() + 1).padStart(2, '0');
+  const dd = String(now.getDate()).padStart(2, '0');
+  // Build number 0-5 based on 4-hour time slots (6 slots per day)
+  const b = Math.floor(now.getHours() / 4);
+  return Number(`${yy}${mm}${dd}${b}`);
+}
+
 const singleHeader = `/*
  * Binary array for the Web UI.
  * gzip is used for smaller size and improved speeds.
@@ -45,6 +56,9 @@ const singleHeader = `/*
  * Please see https://kno.wled.ge/advanced/custom-features/#changing-web-ui
  * to find out how to easily modify the web UI source!
  */
+
+// Automatically generated build time for cache busting
+#define WEB_BUILD_TIME ${generateBuildTime()}
  
 `;
 
diff --git a/wled00/wled_server.cpp b/wled00/wled_server.cpp
index 35c3c1c2fa..474a44d0a5 100644
--- a/wled00/wled_server.cpp
+++ b/wled00/wled_server.cpp
@@ -67,7 +67,7 @@ static bool inLocalSubnet(const IPAddress &client) {
  */
 
 static void generateEtag(char *etag, uint16_t eTagSuffix) {
-  sprintf_P(etag, PSTR("%7d-%02x-%04x"), VERSION, cacheInvalidate, eTagSuffix);
+  sprintf_P(etag, PSTR("%7d-%02x-%04x"), WEB_BUILD_TIME, cacheInvalidate, eTagSuffix);
 }
 
 static void setStaticContentCacheHeaders(AsyncWebServerResponse *response, int code, uint16_t eTagSuffix = 0) {

From 0adfc17617025cad69edd5ea8de22def557806dc Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 27 Nov 2025 13:13:42 +0000
Subject: [PATCH 6/8] Change WEB_BUILD_TIME format to YYMMDD_hhmmss (UTC)

Co-authored-by: Aircoookie <21045690+Aircoookie@users.noreply.github.com>
---
 tools/cdata.js         | 19 ++++++++++---------
 wled00/wled_server.cpp |  2 +-
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/tools/cdata.js b/tools/cdata.js
index 01921dd1d8..30b327fcfd 100644
--- a/tools/cdata.js
+++ b/tools/cdata.js
@@ -38,15 +38,16 @@ const wledBanner = `
 \t\t\x1b[36m build script for web UI
 \x1b[0m`;
 
-// Generate build timestamp in format compatible with VERSION (yymmddb)
+// Generate build timestamp in YYMMDD_hhmmss format (UTC)
 function generateBuildTime() {
   const now = new Date();
-  const yy = String(now.getFullYear() % 100).padStart(2, '0');
-  const mm = String(now.getMonth() + 1).padStart(2, '0');
-  const dd = String(now.getDate()).padStart(2, '0');
-  // Build number 0-5 based on 4-hour time slots (6 slots per day)
-  const b = Math.floor(now.getHours() / 4);
-  return Number(`${yy}${mm}${dd}${b}`);
+  const yy = String(now.getUTCFullYear() % 100).padStart(2, '0');
+  const mm = String(now.getUTCMonth() + 1).padStart(2, '0');
+  const dd = String(now.getUTCDate()).padStart(2, '0');
+  const hh = String(now.getUTCHours()).padStart(2, '0');
+  const min = String(now.getUTCMinutes()).padStart(2, '0');
+  const ss = String(now.getUTCSeconds()).padStart(2, '0');
+  return `${yy}${mm}${dd}_${hh}${min}${ss}`;
 }
 
 const singleHeader = `/*
@@ -57,8 +58,8 @@ const singleHeader = `/*
  * to find out how to easily modify the web UI source!
  */
 
-// Automatically generated build time for cache busting
-#define WEB_BUILD_TIME ${generateBuildTime()}
+// Automatically generated build time for cache busting (YYMMDD_hhmmss UTC)
+#define WEB_BUILD_TIME "${generateBuildTime()}"
  
 `;
 
diff --git a/wled00/wled_server.cpp b/wled00/wled_server.cpp
index 474a44d0a5..d1db7c93d1 100644
--- a/wled00/wled_server.cpp
+++ b/wled00/wled_server.cpp
@@ -67,7 +67,7 @@ static bool inLocalSubnet(const IPAddress &client) {
  */
 
 static void generateEtag(char *etag, uint16_t eTagSuffix) {
-  sprintf_P(etag, PSTR("%7d-%02x-%04x"), WEB_BUILD_TIME, cacheInvalidate, eTagSuffix);
+  sprintf_P(etag, PSTR("%s-%02x-%04x"), WEB_BUILD_TIME, cacheInvalidate, eTagSuffix);
 }
 
 static void setStaticContentCacheHeaders(AsyncWebServerResponse *response, int code, uint16_t eTagSuffix = 0) {

From 714a7f816cd3dc5239d56743fddba1d94976fac0 Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Thu, 27 Nov 2025 13:52:25 +0000
Subject: [PATCH 7/8] Change WEB_BUILD_TIME to UNIX timestamp integer for flash
 savings

Co-authored-by: DedeHai <6280424+DedeHai@users.noreply.github.com>
---
 tools/cdata.js         | 15 ++++-----------
 wled00/wled_server.cpp |  2 +-
 2 files changed, 5 insertions(+), 12 deletions(-)

diff --git a/tools/cdata.js b/tools/cdata.js
index 30b327fcfd..759d24c2da 100644
--- a/tools/cdata.js
+++ b/tools/cdata.js
@@ -38,16 +38,9 @@ const wledBanner = `
 \t\t\x1b[36m build script for web UI
 \x1b[0m`;
 
-// Generate build timestamp in YYMMDD_hhmmss format (UTC)
+// Generate build timestamp as UNIX timestamp (seconds since epoch)
 function generateBuildTime() {
-  const now = new Date();
-  const yy = String(now.getUTCFullYear() % 100).padStart(2, '0');
-  const mm = String(now.getUTCMonth() + 1).padStart(2, '0');
-  const dd = String(now.getUTCDate()).padStart(2, '0');
-  const hh = String(now.getUTCHours()).padStart(2, '0');
-  const min = String(now.getUTCMinutes()).padStart(2, '0');
-  const ss = String(now.getUTCSeconds()).padStart(2, '0');
-  return `${yy}${mm}${dd}_${hh}${min}${ss}`;
+  return Math.floor(Date.now() / 1000);
 }
 
 const singleHeader = `/*
@@ -58,8 +51,8 @@ const singleHeader = `/*
  * to find out how to easily modify the web UI source!
  */
 
-// Automatically generated build time for cache busting (YYMMDD_hhmmss UTC)
-#define WEB_BUILD_TIME "${generateBuildTime()}"
+// Automatically generated build time for cache busting (UNIX timestamp)
+#define WEB_BUILD_TIME ${generateBuildTime()}
  
 `;
 
diff --git a/wled00/wled_server.cpp b/wled00/wled_server.cpp
index d1db7c93d1..d4e266d6a2 100644
--- a/wled00/wled_server.cpp
+++ b/wled00/wled_server.cpp
@@ -67,7 +67,7 @@ static bool inLocalSubnet(const IPAddress &client) {
  */
 
 static void generateEtag(char *etag, uint16_t eTagSuffix) {
-  sprintf_P(etag, PSTR("%s-%02x-%04x"), WEB_BUILD_TIME, cacheInvalidate, eTagSuffix);
+  sprintf_P(etag, PSTR("%u-%02x-%04x"), WEB_BUILD_TIME, cacheInvalidate, eTagSuffix);
 }
 
 static void setStaticContentCacheHeaders(AsyncWebServerResponse *response, int code, uint16_t eTagSuffix = 0) {

From db71cf3289c961f694313dd8366b1fcf6961fa0c Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 28 Nov 2025 06:12:11 +0000
Subject: [PATCH 8/8] Remove unnecessary must-revalidate and _codeql gitignore
 entry

Co-authored-by: DedeHai <6280424+DedeHai@users.noreply.github.com>
---
 .gitignore             | 1 -
 wled00/wled_server.cpp | 3 +--
 2 files changed, 1 insertion(+), 3 deletions(-)

diff --git a/.gitignore b/.gitignore
index 256d7260c8..ec9d4efcc3 100644
--- a/.gitignore
+++ b/.gitignore
@@ -25,4 +25,3 @@ wled-update.sh
 /wled00/Release
 /wled00/wled00.ino.cpp
 /wled00/html_*.h
-_codeql*
diff --git a/wled00/wled_server.cpp b/wled00/wled_server.cpp
index d4e266d6a2..09aeaccff2 100644
--- a/wled00/wled_server.cpp
+++ b/wled00/wled_server.cpp
@@ -78,8 +78,7 @@ static void setStaticContentCacheHeaders(AsyncWebServerResponse *response, int c
   #ifndef WLED_DEBUG
   // this header name is misleading, "no-cache" will not disable cache,
   // it just revalidates on every load using the "If-None-Match" header with the last ETag value
-  // must-revalidate ensures the browser MUST check with the server before using cached content
-  response->addHeader(FPSTR(s_cache_control), F("no-cache, must-revalidate"));
+  response->addHeader(FPSTR(s_cache_control), F("no-cache"));
   #else
   response->addHeader(FPSTR(s_cache_control), F("no-store,max-age=0"));  // prevent caching if debug build
   #endif