diff --git a/.build-wt-028a5dca b/.build-wt-028a5dca
deleted file mode 160000
index 028a5dca..00000000
--- a/.build-wt-028a5dca
+++ /dev/null
@@ -1 +0,0 @@
-Subproject commit 028a5dcaddd69b4be80cc595d33d450be1c46e8b
diff --git a/.github/workflows/build-observer-firmwares.yml b/.github/workflows/build-observer-firmwares.yml
index 35514591..804139b7 100644
--- a/.github/workflows/build-observer-firmwares.yml
+++ b/.github/workflows/build-observer-firmwares.yml
@@ -25,6 +25,9 @@ on:
       - 'LICENSE'
       - '.vscode/**'
       - '.claude/**'
+      # Throwaway build worktrees never affect the binaries.
+      - '.build-wt-*'
+      - '.build-wt-*/**'
 
 # Own group: serialize builds against each other only. Do NOT share this group
 # with sync-flasher-content.yml — a mixed code+docs commit triggers both, and a
diff --git a/.gitignore b/.gitignore
index bee82048..6e7f5748 100644
--- a/.gitignore
+++ b/.gitignore
@@ -24,3 +24,6 @@ platformio.local.ini
 .claude/*
 .cursorrules
 src/helpers/esp32/WebConfigHtml.h
+# Throwaway build worktrees; committing one adds a stray gitlink that makes every
+# CI checkout warn "No url found for submodule path ... in .gitmodules".
+.build-wt-*/