fuzz: replace : with _ for Windows

.github/workflows/test.yml

@@ -712,11 +712,6 @@ jobs:
     steps:
       - name: Checkout code
         uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-        with:
-          sparse-checkout: |
-            /*
-            !test/fuzz-libghostty/corpus/vt-parser-cmin
-            !test/fuzz-libghostty/corpus/vt-parser-min
 
       # This could be from a script if we wanted to but inlining here for now
       # in one place.

test/fuzz-libghostty/AGENTS.md

@@ -2,6 +2,9 @@
 
 - `ghostty-fuzz` is a binary built with `afl-cc`
 - Build `ghostty-fuzz` with `zig build`
+- After running `afl-cmin`/`afl-tmin`, run `corpus/sanitize-filenames.sh`
+  before committing to replace colons with underscores (colons are invalid
+  on Windows NTFS).
 
 ## Important: stdin-based input
 

test/fuzz-libghostty/README.md

@@ -118,6 +118,16 @@ This is slow (hundreds of executions per file) but produces the most
 compact corpus. It can be skipped if you only need edge-level
 deduplication from `afl-cmin`.
 
+### Windows compatibility
+
+AFL++ output filenames contain colons (e.g., `id:000024,time:0,...`), which
+are invalid on Windows (NTFS). After running `afl-cmin` or `afl-tmin`,
+rename the output files to replace colons with underscores before committing:
+
+```sh
+./corpus/sanitize-filenames.sh
+```
+
 ### Corpus directories
 
 | Directory                | Contents                                        |

test/fuzz-libghostty/corpus/sanitize-filenames.sh

@@ -0,0 +1,19 @@
+#!/bin/sh
+# Rename AFL++ output files to replace colons with underscores.
+# Colons are invalid on Windows (NTFS).
+#
+# Usage: ./sanitize-filenames.sh [directory ...]
+# Defaults to vt-parser-cmin and vt-parser-min in the same directory as this script.
+
+cd "$(dirname "$0")" || exit 1
+
+dirs="${@:-vt-parser-cmin vt-parser-min}"
+
+for dir in $dirs; do
+  [ -d "$dir" ] || continue
+  for f in "$dir"/*; do
+    [ -f "$f" ] || continue
+    newname=$(echo "$f" | tr ':' '_')
+    [ "$f" != "$newname" ] && mv "$f" "$newname"
+  done
+done