diff --git a/scripts/check-agent-docs-drift.sh b/scripts/check-agent-docs-drift.sh
index ff46c8f8..41047663 100755
--- a/scripts/check-agent-docs-drift.sh
+++ b/scripts/check-agent-docs-drift.sh
@@ -11,11 +11,17 @@
 # What is checked per repo:
 #   1. Legacy files MUST NOT exist (they used to duplicate AGENTS.md):
 #        .cursorrules, .windsurfrules, .clinerules, CLAUDE.md
-#   2. AGENTS.md MUST contain the canonical-behavior-pointer marker.
-#   3. .github/copilot-instructions.md MUST contain the AUTO-GENERATED marker
+#   2. Per-tool subdirectory AGENTS.md duplicates MUST NOT exist (an earlier
+#      "centralize agent docs" refactor introduced redirect pointers in
+#      .claude/, .cline/, .cursor/, .devin/ that duplicate the canonical
+#      repo-root AGENTS.md). Listed files:
+#        .claude/AGENTS.md, .cline/AGENTS.md, .cursor/AGENTS.md,
+#        .devin/AGENTS.md, .devin/CONTEXT.md
+#   3. AGENTS.md MUST contain the canonical-behavior-pointer marker.
+#   4. .github/copilot-instructions.md MUST contain the AUTO-GENERATED marker
 #      AND a reference to the canonical guidelines file.
-#   4. .aider.conf.yml MUST exist and reference AGENTS.md.
-#   5. .editorconfig MUST exist with the canonical first line "root = true".
+#   5. .aider.conf.yml MUST exist and reference AGENTS.md.
+#   6. .editorconfig MUST exist with the canonical first line "root = true".
 #
 # Repair: bash scripts/update-agent-docs.sh
 
@@ -33,6 +39,15 @@ if [[ ! -f "$REPOS_TXT" ]]; then
 fi
 
 LEGACY_FILES=(.cursorrules .windsurfrules .clinerules CLAUDE.md)
+# Per-tool subdirectory duplicates (introduced by an earlier "centralize
+# agent docs" refactor and superseded by single-source-of-truth).
+LEGACY_SUBDIR_FILES=(
+  .claude/AGENTS.md
+  .cline/AGENTS.md
+  .cursor/AGENTS.md
+  .devin/AGENTS.md
+  .devin/CONTEXT.md
+)
 AGENTS_POINTER_MARKER="<!-- BEGIN: canonical-behavior-pointer (auto-managed) -->"
 COPILOT_GENERATED_MARKER="<!-- AUTO-GENERATED by learning_ai_common_plat/scripts/update-agent-docs.sh -->"
 COPILOT_CANONICAL_REF="agent-behavior-guidelines.md"
@@ -62,19 +77,26 @@ for repo in "${REPOS[@]}"; do
 
   issues=()
 
-  # 1 — Legacy files must be gone.
+  # 1 — Legacy root files must be gone.
   for f in "${LEGACY_FILES[@]}"; do
     if [[ -e "${repo_dir}/${f}" ]]; then
       issues+=("legacy file still present: $f")
     fi
   done
 
-  # 2 — AGENTS.md must have the canonical pointer block.
+  # 2 — Legacy per-tool subdirectory duplicates must be gone.
+  for f in "${LEGACY_SUBDIR_FILES[@]}"; do
+    if [[ -e "${repo_dir}/${f}" ]]; then
+      issues+=("legacy per-tool duplicate still present: $f")
+    fi
+  done
+
+  # 3 — AGENTS.md must have the canonical pointer block.
   if ! grep -qF "$AGENTS_POINTER_MARKER" "${repo_dir}/AGENTS.md"; then
     issues+=("AGENTS.md missing canonical-behavior-pointer block")
   fi
 
-  # 3 — Copilot file: must exist, must be AUTO-GENERATED, must reference canonical.
+  # 4 — Copilot file: must exist, must be AUTO-GENERATED, must reference canonical.
   copilot="${repo_dir}/.github/copilot-instructions.md"
   if [[ ! -f "$copilot" ]]; then
     issues+=(".github/copilot-instructions.md missing")
@@ -87,7 +109,7 @@ for repo in "${REPOS[@]}"; do
     fi
   fi
 
-  # 4 — Aider config: must exist and reference AGENTS.md.
+  # 5 — Aider config: must exist and reference AGENTS.md.
   aider="${repo_dir}/.aider.conf.yml"
   if [[ ! -f "$aider" ]]; then
     issues+=(".aider.conf.yml missing")
@@ -95,7 +117,7 @@ for repo in "${REPOS[@]}"; do
     issues+=(".aider.conf.yml does not reference AGENTS.md")
   fi
 
-  # 5 — Editorconfig: must exist with canonical first line.
+  # 6 — Editorconfig: must exist with canonical first line.
   editorconfig="${repo_dir}/.editorconfig"
   if [[ ! -f "$editorconfig" ]]; then
     issues+=(".editorconfig missing")