[evoskill] Refine resolve-merge-conflicts skill: detect leftover conflict markers

.github/skills/resolve-merge-conflicts/SKILL.md

@@ -26,15 +26,41 @@ conflicts. It:
 
 1. Starts the merge with `--no-commit`, or resumes the current merge.
 2. Refuses to auto-resolve if any conflict is not a workflow `.lock.yml`.
-3. Runs `make recompile` once so generated files come from the merged Markdown.
-4. Stages the regenerated conflicting lock files.
-5. Verifies that no unresolved paths or whitespace errors remain.
+3. Scans `.github/workflows/*.md` for leftover conflict-marker lines
+   (`<<<<<<<`, `|||||||`, `=======`, `>>>>>>>`) and aborts before compiling
+   if any are found — see "Why the marker scan matters" below.
+4. Runs `make recompile` once so generated files come from the merged Markdown.
+5. Stages the regenerated conflicting lock files.
+6. Verifies that no unresolved paths or whitespace errors remain.
 
 The script does not fetch, commit, push, abort, or edit workflow Markdown.
 Refresh `origin/main` first only when credentials are available. After success,
 review the staged merge, run the repository's final validation gate, then
 commit and push.
 
+## Why the marker scan matters
+
+A source `.md` conflict resolved manually (by a human or an agent) can leave
+a stray conflict-marker line behind — most often the rarely-noticed
+`||||||| base (original)` diff3 marker — inside a workflow's YAML
+frontmatter. `git diff --check` only inspects lines touched by the current
+diff/staged hunks, so a marker already committed in otherwise-unchanged file
+content passes silently. The gh-aw compiler then parses the marker text as a
+literal YAML header option (e.g. `invalid header option: "|||||| base
+(original)"`), which fails compilation later — often in an unrelated
+scheduled recompilation run, far from the original merge, making the root
+cause hard to trace back.
+
+Run the standalone check any time you suspect a workflow `.md` file went
+through manual conflict resolution, even outside this script's merge flow:
+
+```bash
+./.github/skills/resolve-merge-conflicts/resolve.sh --verify-markers
+```
+
+It exits non-zero and lists the offending file(s)/line(s) if any marker is
+found, and does not modify the working tree.
+
 ## Safety rules
 
 - Never choose `ours` or `theirs` for compiled lock files; regenerate them.

.github/skills/resolve-merge-conflicts/resolve.sh

@@ -4,15 +4,48 @@ set -euo pipefail
 usage() {
     cat <<'EOF'
 Usage: resolve.sh [BASE_REF]
+       resolve.sh --verify-markers
 
 Merge BASE_REF (default: origin/main) without committing, then resolve
 workflow lock-file-only conflicts by running make recompile.
 
 If a merge is already in progress, BASE_REF is ignored and the current
 conflicts are processed.
+
+--verify-markers scans all .github/workflows/*.md source files (not just
+files touched by the current diff) for leftover git conflict-marker lines
+(<<<<<<<, |||||||, =======, >>>>>>>) and exits non-zero listing any hits.
+Run it after resolving mixed conflicts and before compiling, and as a
+standalone pre-flight check any time a source workflow file may have been
+merged manually — `git diff --check` only inspects changed hunks and will
+not catch markers already committed in unchanged file content.
 EOF
 }
 
+verify_markers() {
+    local repo_root
+    repo_root=$(git rev-parse --show-toplevel 2>/dev/null) ||
+        die "run this command inside a Git repository"
+    cd "$repo_root"
+
+    local pattern='^(<{7}|\|{7}|={7}|>{7})([^=<>|]|$)'
+    local hits=0
+    while IFS= read -r -d '' file; do
+        local matches
+        matches=$(grep -nE "$pattern" -- "$file" || true)
+        if [[ -n $matches ]]; then
+            hits=1
+            echo "error: leftover conflict marker(s) in $file:" >&2
+            echo "$matches" >&2
+        fi
+    done < <(find .github/workflows -maxdepth 1 -name '*.md' -print0 2>/dev/null)
+
+    if (( hits )); then
+        die "unresolved conflict markers found in workflow source; fix before compiling"
+    fi
+    echo "No conflict markers found in .github/workflows/*.md"
+}
+
 die() {
     echo "error: $*" >&2
     exit 1
@@ -22,6 +55,10 @@ if [[ ${1:-} == "--help" || ${1:-} == "-h" ]]; then
     usage
     exit 0
 fi
+if [[ ${1:-} == "--verify-markers" ]]; then
+    verify_markers
+    exit 0
+fi
 if (( $# > 1 )); then
     usage >&2
     exit 2
@@ -71,6 +108,13 @@ if (( ${#conflicts[@]} > 0 )); then
 else
     echo "No unresolved source conflicts; recompiling workflows..."
 fi
+
+# A manually resolved .md source conflict can silently leave behind a
+# conflict-marker line (e.g. "|||||| base (original)") that git diff --check
+# will not flag once staged/committed. Fail fast before compiling so the
+# error surfaces here instead of during a later scheduled recompilation.
+verify_markers
+
 make recompile
 
 if (( ${#conflicts[@]} > 0 )); then