fix(parity): init delete_suppressed; gate deleted-path retention

- Initialize PipelineContextSender.delete_suppressed=false: an uninitialized
  true silently skipped the --delete keep-set manifest under -m/--threads,
  so destination extras were never removed.
- Allocate/install the receiver deleted-path observer only when
  report_deletes is set (--info=del / -i / --out-format under --delete), cap
  the retained list at MAX_MANIFEST_ENTRIES, and free already-created lists
  on the receiver-pipeline create failure path.
- Validate report_deletes/report_stats/report_dest_info on receive.
- Correct stale comments (config.h report_deletes, delete_plan.h deleted
  count, multiprocessing.h stats locking, utils.h observer placement).
- Tests: sender delete_suppressed init, report_deletes gating (unit), and
  -m/--delete default delete-after keep-set removal (integration).

src/server/receiver.c

@@ -104,6 +104,11 @@ void receiver_record_deleted_path(void* context, const char* rel_path) {
   ArrayList* paths = context;
   if (!paths || !rel_path)
     return;
+  /* Bound the retained list like the keep-set manifest: only MAX_MANIFEST_ENTRIES
+     paths are ever transmitted in the terminal STATUS_STATS frame, so recording
+     more only grows memory.  A hostile/huge deletion set is therefore capped. */
+  if ((size_t)paths->size >= (size_t)MAX_MANIFEST_ENTRIES)
+    return;
   char* copy = str_dup(rel_path);
   if (copy && !array_list_add(paths, copy))
     free(copy);
@@ -417,7 +422,8 @@ int receiver_process_pending(Config* config, int file_descriptor, const Receiver
            --max-delete-capped commit still succeeds and the transfer proceeds;
            the terminal success frame reports the cap. */
         size_t deleted = 0;
-        DeletePathObserver observer = sink->deleted_paths ? receiver_record_deleted_path : NULL;
+        DeletePathObserver observer =
+            (config->report_deletes && sink->deleted_paths) ? receiver_record_deleted_path : NULL;
         DeleteCommitResult deletion =
             (config->use_delete || config->delete_missing_args)
                 ? manifest_delete_all_observed(config, manifest, &deleted, observer,
@@ -459,7 +465,7 @@ int receiver_process_pending(Config* config, int file_descriptor, const Receiver
       }
       if (!plan_session) {
         plan_session = delete_plan_session_create(config);
-        if (plan_session && sink->deleted_paths)
+        if (plan_session && config->report_deletes && sink->deleted_paths)
           delete_plan_session_set_delete_observer(plan_session, receiver_record_deleted_path,
                                                   (void*)sink->deleted_paths);
       }
@@ -505,7 +511,8 @@ int receiver_process_pending(Config* config, int file_descriptor, const Receiver
       deferred_manifest = NULL;
     } else {
       size_t deleted = 0;
-      DeletePathObserver observer = sink->deleted_paths ? receiver_record_deleted_path : NULL;
+      DeletePathObserver observer =
+          (config->report_deletes && sink->deleted_paths) ? receiver_record_deleted_path : NULL;
       DeleteCommitResult deletion = manifest_delete_all_observed(
           config, deferred_manifest, &deleted, observer, (void*)sink->deleted_paths);
       receiver_tally_deleted(sink, deleted);
@@ -525,7 +532,7 @@ int receiver_process_pending(Config* config, int file_descriptor, const Receiver
      hands the session to its caller instead, which commits after the disk
      writer drained. */
   if (plan_session) {
-    if (sink->deleted_paths)
+    if (config->report_deletes && sink->deleted_paths)
       delete_plan_session_set_delete_observer(plan_session, receiver_record_deleted_path,
                                               (void*)sink->deleted_paths);
     if (pending_plans) {
@@ -684,8 +691,11 @@ int receiver_receive_files(Config* config, int file_descriptor) {
   ReceiverSaveContext context = {.config = config, .outcomes = {0}};
   dir_time_list_init(&context.dir_times);
   context.would_delete = array_list_create(free);
-  context.deleted_paths = array_list_create(free);
-  if (!context.would_delete || !context.deleted_paths) {
+  /* report_deletes (--info=del / -i / --out-format under --delete) is the only
+     reason to retain the actually-removed paths; a plain --delete must not
+     str_dup every removal.  NULL is handled by every consumer. */
+  context.deleted_paths = config->report_deletes ? array_list_create(free) : NULL;
+  if (!context.would_delete || (config->report_deletes && !context.deleted_paths)) {
     array_list_delete(context.would_delete);
     array_list_delete(context.deleted_paths);
     return -1;

src/server/receiver_pipeline.c

@@ -47,9 +47,15 @@ PipelineContextReceiver* pipeline_context_receiver_create(Config* config, Queue*
   context->would_delete = array_list_create(free);
   if (!context->would_delete)
     goto fail;
-  context->deleted_paths = array_list_create(free);
-  if (!context->deleted_paths)
-    goto fail;
+  /* The actually-removed path list is only needed to render rsync's
+     `deleting PATH` lines, which the client requests via report_deletes
+     (--info=del / -i / --out-format under --delete).  A plain --delete run must
+     not allocate it or observe every removal. */
+  if (config->report_deletes) {
+    context->deleted_paths = array_list_create(free);
+    if (!context->deleted_paths)
+      goto fail;
+  }
   return context;
 
 fail:
@@ -60,6 +66,12 @@ fail:
     cnd_destroy(&context->condition_not_full);
   if (init >= 1)
     mtx_destroy(&context->mutex);
+  /* Free every list that was already created before the failing allocation:
+     `context` itself is freed below, so they would otherwise leak. */
+  if (context->would_delete)
+    array_list_delete(context->would_delete);
+  if (context->deleted_paths)
+    array_list_delete(context->deleted_paths);
   free(context);
   return NULL;
 }

src/shared/config.c

@@ -206,7 +206,8 @@ static bool validate_received_config(const Config* config) {
          valid_wire_bool(config->preserve_perms) && valid_wire_bool(config->preserve_times) &&
          valid_wire_bool(config->preserve_owner) && valid_wire_bool(config->preserve_group) &&
          valid_wire_bool(config->munge_links) && valid_wire_bool(config->keep_dirlinks) &&
-         valid_wire_bool(config->fake_super) &&
+         valid_wire_bool(config->fake_super) && valid_wire_bool(config->report_dest_info) &&
+         valid_wire_bool(config->report_stats) && valid_wire_bool(config->report_deletes) &&
          (!config->copy_as_set || (config->copy_as_uid >= 0 && config->copy_as_gid >= 0)) &&
          (!config->use_compression ||
           (config->compression_level >= 1 && config->compression_level <= 22)) &&

src/shared/config.h

@@ -265,8 +265,9 @@ typedef enum SuperMode { SUPER_MODE_AUTO = 0, SUPER_MODE_ON = 1, SUPER_MODE_OFF
  * the destination-relative paths it ACTUALLY removed in its terminal
  * STATUS_STATS record (the same path-list field the dry-run would-delete report
  * uses), so the sender can print rsync's `deleting PATH`/`*deleting` lines for a
- * real (non-dry-run) deletion.  It is set only when --info=del is requested with
- * --delete; the transfer decision itself is unchanged. */
+ * real (non-dry-run) deletion.  It is set when --delete is active and any of
+ * --info=del, -i/--itemize-changes or --out-format requests per-file change
+ * output; the transfer decision itself is unchanged. */
 #define CONFIG_WIRE_OUTPUT_FIELDS(X)                                                               \
   X(report_dest_info, bool, false, BOOL)                                                           \
   X(report_stats, bool, false, BOOL) X(report_deletes, bool, false, BOOL)

src/shared/delete_plan.h

@@ -77,8 +77,10 @@ int delete_plan_session_receive(DeletePlanSession* session, const Config* config
 DeleteCommitResult delete_plan_session_commit(DeletePlanSession* session, const Config* config);
 /* True once the shared --max-delete budget stopped part of a deletion. */
 bool delete_plan_session_limit_reached(const DeletePlanSession* session);
-/* Number of destination entries the session's plans removed (or, for
-   --delete-delay, snapshotted for removal), for the end-of-transfer stats. */
+/* Number of destination entries the session's plans ACTUALLY removed, for the
+   end-of-transfer stats.  A --delete-delay entry only snapshotted for removal
+   that survives the commit (e.g. a directory refilled before it is removed, so
+   unlink/rmdir fails with ENOTEMPTY) is not counted. */
 size_t delete_plan_session_deleted(const DeletePlanSession* session);
 /* Install an observer invoked for every destination-relative path the session
    truly removes (including the deferred --delete-delay commit), so the receiver

src/shared/multiprocessing.c

@@ -38,6 +38,7 @@ PipelineContextSender* pipeline_context_sender_create(Config* config, Queue* que
   context->remove_source_files = NULL;
   context->early_delete = false;
   context->delete_plans = NULL;
+  context->delete_suppressed = false;
   context->scan_stopped_early = false;
   context->total_files = 0;
   context->progress_bytes = 0;

src/shared/multiprocessing.h

@@ -93,7 +93,11 @@ typedef struct {
   unsigned long long progress_bytes;
   unsigned long long total_bytes;
   /* Per-type flist / transferred accounting for the rsync --stats breakdown and
-     the progress `to-chk` denominator.  Guarded by mutex_progress. */
+     the progress `to-chk` denominator.  Owned by the sender thread: it is the
+     only writer (the entry/transfer notes in send_chunks_multithreaded) and it
+     reads the totals in its completion tail, so no lock is needed.  This is NOT
+     guarded by mutex_progress (which covers total_files/progress_bytes/
+     total_bytes/sender_done). */
   TransferStats stats;
   bool sender_done;
   atomic_bool cancelled;

src/shared/utils.h

@@ -134,6 +134,11 @@ bool path_under_skip_prefix(const char* child_rel, bool at_root, const DeleteSki
    cap and returns DELETE_WALK_LIMIT_REACHED when more extras remained.
    `deleted_out`/`skipped_out` optionally receive the number of entries removed
    and the number skipped because of the cap. */
+DeleteWalkResult delete_extras_limited(const char* dest_root, const ArrayList* manifest,
+                                       const ArrayList* synced_dirs, size_t max_delete,
+                                       const DeleteSkipEntry* skips, int skip_count,
+                                       size_t* deleted_out, size_t* skipped_out);
+
 /* Optional per-deletion observer: called for each destination-relative path
    actually removed (a file, symlink, or directory), in removal order, so the
    receiver can stream rsync's `--info=del`/`--info=remove` lines. */
@@ -147,11 +152,6 @@ DeleteWalkResult delete_extras_limited_observed(const char* dest_root, const Arr
                                                 size_t* deleted_out, size_t* skipped_out,
                                                 DeletePathObserver observer,
                                                 void* observer_context);
-
-DeleteWalkResult delete_extras_limited(const char* dest_root, const ArrayList* manifest,
-                                       const ArrayList* synced_dirs, size_t max_delete,
-                                       const DeleteSkipEntry* skips, int skip_count,
-                                       size_t* deleted_out, size_t* skipped_out);
 /* Read-only companion to delete_extras_limited: walk the destination exactly as
    the delete pass would and APPEND (strdup'd) destination-relative paths that
    WOULD be removed, without touching disk.  Used for -n/--dry-run --delete

tests/integration/test_delete_timing_parity.py

@@ -441,3 +441,24 @@ class TestDeleteDelayVsAfterSnapshot:
                     f"{timing} (mt={mt}): new_extra present="
                     f"{os.path.exists(new_extra)}, expected survives={new_survives}"
                 )
+
+
+class TestDeleteAfterThreadsKeepSet:
+    """Regression: -m/--threads with the default delete-after timing (plain
+    --delete) must still transmit the keep-set manifest and remove destination
+    extras.  PipelineContextSender.delete_suppressed was left uninitialized, so a
+    garbage true silently skipped the manifest under --threads."""
+
+    @pytest.mark.parametrize("delete_flag", ["--delete", "--delete-after"])
+    def test_threads_delete_after_sends_keep_set(self, delete_flag):
+        source, dest, received = _seed_pair("mtkeep")
+        extra = os.path.join(received, "d", "old_extra")
+        assert os.path.exists(extra)
+        with ServerManager() as server:
+            server.start(extra_args=["--allow-delete"])
+            result, _ = run_client(source, dest, flags=["--threads", delete_flag],
+                                   port=server.port)
+        assert result.returncode == 0, (result.stderr or result.stdout)[:300]
+        assert not os.path.exists(extra), (
+            f"{delete_flag} --threads did not remove an extra: keep-set manifest was suppressed"
+        )

tests/test_multiprocessing.c

@@ -103,6 +103,62 @@ static void test_sender_zero_capacity() {
   config_delete(cfg);
 }
 
+/* Regression (blocker): PipelineContextSender.delete_suppressed must be
+   initialized false.  A garbage true silently suppresses the --delete keep-set
+   manifest under -m/--threads, so destination extras would never be removed. */
+static void test_sender_delete_suppressed_initialized() {
+  Config* cfg = config_create();
+  EXPECT_NOT_NULL(cfg);
+  free(cfg->version);
+  cfg->version = str_dup(PROTOCOL_VERSION);
+  cfg->send_directory = str_dup("/src");
+  cfg->receive_root_directory = str_dup("/dst");
+
+  Queue* q1 = queue_create(5, NULL);
+  Queue* q2 = queue_create(5, NULL);
+  EXPECT_NOT_NULL(q1);
+  EXPECT_NOT_NULL(q2);
+  PipelineContextSender* ctx = pipeline_context_sender_create(cfg, q1, q2);
+  EXPECT_NOT_NULL(ctx);
+  EXPECT_FALSE(ctx->delete_suppressed);
+  pipeline_context_sender_destroy(ctx);
+  config_delete(cfg);
+}
+
+/* --info=del (report_deletes) is the only reason the receiver retains the
+   actually-removed paths: a plain --delete receiver must not allocate the list,
+   and with report_deletes armed the observer records into it. */
+static void test_receiver_deleted_paths_gated_by_report_deletes() {
+  Config* plain = config_create();
+  EXPECT_NOT_NULL(plain);
+  free(plain->version);
+  plain->version = str_dup(PROTOCOL_VERSION);
+  plain->receive_root_directory = str_dup("/dst");
+  plain->report_deletes = false;
+  Queue* q_plain = queue_create(5, file_destroy);
+  EXPECT_NOT_NULL(q_plain);
+  PipelineContextReceiver* ctx_plain = pipeline_context_receiver_create(plain, q_plain, -1, NULL);
+  EXPECT_NOT_NULL(ctx_plain);
+  EXPECT_NULL(ctx_plain->deleted_paths);
+  pipeline_context_receiver_destroy(ctx_plain);
+
+  Config* info = config_create();
+  EXPECT_NOT_NULL(info);
+  free(info->version);
+  info->version = str_dup(PROTOCOL_VERSION);
+  info->receive_root_directory = str_dup("/dst");
+  info->report_deletes = true;
+  Queue* q_info = queue_create(5, file_destroy);
+  EXPECT_NOT_NULL(q_info);
+  PipelineContextReceiver* ctx_info = pipeline_context_receiver_create(info, q_info, -1, NULL);
+  EXPECT_NOT_NULL(ctx_info);
+  EXPECT_NOT_NULL(ctx_info->deleted_paths);
+  receiver_record_deleted_path(ctx_info->deleted_paths, "d/old_extra");
+  EXPECT_EQ_INT(ctx_info->deleted_paths->size, 1);
+  EXPECT_EQ_STR((const char*)ctx_info->deleted_paths->items[0], "d/old_extra");
+  pipeline_context_receiver_destroy(ctx_info);
+}
+
 /* Test receiver with zero file_descriptor */
 static void test_receiver_fd_zero() {
   Config* cfg = config_create();
@@ -462,6 +518,8 @@ void test_multiprocessing() {
   test_receiver_create_destroy();
   test_sender_queue_capacities();
   test_sender_zero_capacity();
+  test_sender_delete_suppressed_initialized();
+  test_receiver_deleted_paths_gated_by_report_deletes();
   test_receiver_fd_zero();
   if (!is_running_under_valgrind()) {
     test_receive_thread_finished();