diff --git a/.claude/CLAUDE.md b/.claude/CLAUDE.md
index 99a5100..4cc05bf 100644
--- a/.claude/CLAUDE.md
+++ b/.claude/CLAUDE.md
@@ -60,6 +60,13 @@ keep the citation accurate.
 * don't use abbreviations, except very common ones ("s" for seconds, "min", "max", etc.)
 * if a variable holds a value that has a unit or if a function returns a value that has a unit, append that unit to the name (e.g. "m_shipVelocity_mps", "getAcceleration_mpss()")
 * always enclose scopes in braces
+* keep source files ASCII-only. A non-ASCII character needed at runtime (a glyph in a
+  UI string, a symbol drawn on a widget) is written as its code point with a comment
+  naming it (`const QChar shiftGlyph(0x21E7);  // U+21E7 UPWARDS WHITE ARROW`), never
+  as a literal character: MSVC 2017 does not read the sources as UTF-8 by default and
+  silently mangles them. Never round-trip a source file through
+  `Get-Content`/`Set-Content` either: Windows PowerShell reads it as ANSI and writes
+  it back double-encoded with a BOM. Use the Edit/Write tools.
 
 ## Build
 
@@ -96,6 +103,15 @@ output directories and copies the Qt DLLs.
 Run the app: `build/DotaFactory/Debug/app/DotaFactory.exe`, optionally
 `--replay <file>` for view-only playback of a recorded run.
 
+**Visual verification is the user's job.** Screen-capturing the app window does not
+work here: `CopyFromScreen` and `PrintWindow` both return a blank white client area
+even while the app is running and rendering normally, because the capture cannot read
+the composited surface of the `QOpenGLWidget`-backed window. A blank capture therefore
+says nothing about whether the UI works, so do not read one as a regression and do not
+try to work around it. To check a UI change: build, run the tests, launch the app, and
+ask the user to look at it. Redirecting the process's stdout/stderr to a file does
+work and is worth checking for Qt warnings.
+
 ## Tests
 
 Catch2, single executable, links `lib` only — no QApplication, no display.