fix(memory): point the drift remediation and missing-args error at operations[]

Review finding (stale wording): the drift remediation and the missing-parameter error
still steered the model to the unadvertised top-level memory(action=...) shape. Both now
name operations[] (a single change is a one-item list); the legacy shape still executes.
The [BLOCKED: ...] load-time placeholder keeps its memory(action=remove, ...) hint: two
origin/main tests pin that exact text, and that call still works.

tools/memory_tool.py

@@ -268,14 +268,14 @@ def _memory_tool(action, target, content, old_text, new_text, operations, store)
         if gate_result is not None:
             return "rejected", gate_result
         return _applied(store.apply_batch(target, operations))
-    # Reject calls that provide neither action (single-op) nor operations
-    # (batch).  Without this guard the dispatch falls through to the generic
+    # Reject calls with neither operations[] nor the legacy top-level action.
+    # Without this guard the dispatch falls through to the generic
     # "Unknown action 'None'" error, which gives the model no signal about
     # *why* the call was malformed and can trigger repeated retries. (#64291)
     if not action and not operations:
         return _invalid(
-            "Missing required parameter: provide 'action' (add/patch/remove) "
-            "or 'operations' (batch list). Got neither."
+            "Missing required parameter: 'operations', a list of {action: add/patch/remove, "
+            "content?, old_text?} changes; a single change is a one-item list."
         )
     if action == "replace":
         return _invalid(_REPLACE_REMOVED)

tools/memory_tool_store.py

@@ -55,9 +55,9 @@ def _drift_error(path: Path, bak_path: str) -> dict[str, Any]:
         f"either rewrite the file as a clean §-delimited list of entries, or move the extra "
         f"content out — then retry. This guard exists to prevent silent data loss (issue #26045)."
     ), "drift", drift_backup=bak_path, remediation=(
-        "Open the .bak file, integrate the missing entries into the memory tool one at a time via "
-        f"memory(action=add, target='{_store_target(path.name)}', content=...), then remove or rewrite the "
-        "original file to a clean state."))
+        "Open the .bak file, integrate the missing entries into the memory tool with one add op per entry via "
+        f"memory(target='{_store_target(path.name)}', operations=[{{action: 'add', content: ...}}]), then remove or "
+        "rewrite the original file to a clean state."))
 
 
 def _read_failed_error(path: Path) -> dict[str, Any]: