Merge branch 'ds/path-walk-filters'

The "git pack-objects --path-walk" traversal has been integrated
with several object filters, including blobless and sparse filters.

* ds/path-walk-filters:
  path-walk: support `combine` filter
  path-walk: support `object:type` filter
  path-walk: support `tree:0` filter
  t6601: tag otherwise-unreachable trees
  pack-objects: support sparse:oid filter with path-walk
  path-walk: add pl_sparse_trees to control tree pruning
  path-walk: support blob size limit filter
  backfill: die on incompatible filter options
  path-walk: support blobless filter
  path-walk: always emit directly-requested objects
  t/perf: add pack-objects filter and path-walk benchmark
  pack-objects: pass --objects with --path-walk
  t5620: make test work with path-walk var

12 files changed, 1124 insertions, 78 deletions

diff --git a/Documentation/git-backfill.adoc b/Documentation/git-backfill.adoc
index c0a3b80615..82d6a1969d 100644
--- a/Documentation/git-backfill.adoc
+++ b/Documentation/git-backfill.adoc
@@ -80,6 +80,10 @@ OPTIONS
 +
 You may also use commit-limiting options understood by
 linkgit:git-rev-list[1] such as `--first-parent`, `--since`, or pathspecs.
++
+Most `--filter=<spec>` options don't work with the purpose of
+`git backfill`, but the `sparse:<oid>` filter is integrated to provide a
+focused set of paths to download, distinct from the `--sparse` option.
 
 SEE ALSO
 --------
diff --git a/Documentation/git-pack-objects.adoc b/Documentation/git-pack-objects.adoc
index b78175fbe1..8a27aa19fd 100644
--- a/Documentation/git-pack-objects.adoc
+++ b/Documentation/git-pack-objects.adoc
@@ -402,9 +402,11 @@ will be automatically changed to version `1`.
 	of filenames that cause collisions in Git's default name-hash
 	algorithm.
 +
-Incompatible with `--delta-islands`, `--shallow`, or `--filter`. The
-`--use-bitmap-index` option will be ignored in the presence of
-`--path-walk.`
+Incompatible with `--delta-islands`. The `--use-bitmap-index` option is
+ignored in the presence of `--path-walk`. The `--path-walk` option
+supports the `--filter=<spec>` forms `blob:none`, `blob:limit=<n>`,
+`tree:0`, `object:type=<type>`, and `sparse:<oid>`. These supported filter
+types can be combined with the `combine:<spec>+<spec>` form.
 
 
 DELTA ISLANDS
diff --git a/Documentation/technical/api-path-walk.adoc b/Documentation/technical/api-path-walk.adoc
index a67de1b143..6e17b13d61 100644
--- a/Documentation/technical/api-path-walk.adoc
+++ b/Documentation/technical/api-path-walk.adoc
@@ -48,6 +48,13 @@ commits.
 	applications could disable some options to make it simpler to walk
 	the objects or to have fewer calls to `path_fn`.
 +
+Note that objects directly requested as pending objects (such as targets
+of lightweight tags or other ref tips) are always emitted to `path_fn`,
+even when the corresponding type flag is disabled. Only objects
+discovered during the tree walk are subject to these type filters. This
+ensures that objects specifically requested through the revision input
+are never silently dropped.
++
 While it is possible to walk only commits in this way, consumers would be
 better off using the revision walk API instead.
 
diff --git a/builtin/backfill.c b/builtin/backfill.c
index 7ffab2ea74..e71e0f4742 100644
--- a/builtin/backfill.c
+++ b/builtin/backfill.c
@@ -96,9 +96,10 @@ static void reject_unsupported_rev_list_options(struct rev_info *revs)
 	if (revs->explicit_diff_merges)
 		die(_("'%s' cannot be used with 'git backfill'"),
 		    "--diff-merges");
-	if (revs->filter.choice)
-		die(_("'%s' cannot be used with 'git backfill'"),
-		    "--filter");
+	if (!path_walk_filter_compatible(&revs->filter))
+		die(_("cannot backfill with these filter options"));
+	if (revs->filter.blob_limit_value)
+		die(_("cannot backfill with blob size limits"));
 }
 
 static int do_backfill(struct backfill_context *ctx)
@@ -108,6 +109,7 @@ static int do_backfill(struct backfill_context *ctx)
 
 	if (ctx->sparse) {
 		CALLOC_ARRAY(info.pl, 1);
+		info.pl_sparse_trees = 1;
 		if (get_sparse_checkout_patterns(info.pl)) {
 			path_walk_info_clear(&info);
 			return error(_("problem loading sparse-checkout"));
diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index 480cc0bd8c..fe9fbecb30 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -4764,7 +4764,7 @@ static int add_objects_by_path(const char *path,
 	return 0;
 }
 
-static void get_object_list_path_walk(struct rev_info *revs)
+static int get_object_list_path_walk(struct rev_info *revs)
 {
 	struct path_walk_info info = PATH_WALK_INFO_INIT;
 	unsigned int processed = 0;
@@ -4787,8 +4787,9 @@ static void get_object_list_path_walk(struct rev_info *revs)
 	result = walk_objects_by_path(&info);
 	trace2_region_leave("pack-objects", "path-walk", revs->repo);
 
-	if (result)
-		die(_("failed to pack objects via path-walk"));
+	path_walk_info_clear(&info);
+
+	return result;
 }
 
 static void get_object_list(struct rev_info *revs, struct strvec *argv)
@@ -4851,8 +4852,13 @@ static void get_object_list(struct rev_info *revs, struct strvec *argv)
 		fn_show_object = show_object;
 
 	if (path_walk) {
-		get_object_list_path_walk(revs);
-	} else {
+		if (get_object_list_path_walk(revs)) {
+			warning(_("failed to pack objects via path-walk"));
+			path_walk = 0;
+		}
+	}
+
+	if (!path_walk) {
 		if (prepare_revision_walk(revs))
 			die(_("revision walk setup failed"));
 		mark_edges_uninteresting(revs, show_edge, sparse);
@@ -5187,7 +5193,7 @@ int cmd_pack_objects(int argc,
 
 	if (path_walk) {
 		const char *option = NULL;
-		if (filter_options.choice)
+		if (!path_walk_filter_compatible(&filter_options))
 			option = "--filter";
 		else if (use_delta_islands)
 			option = "--delta-islands";
@@ -5200,10 +5206,7 @@ int cmd_pack_objects(int argc,
 	}
 	if (path_walk) {
 		strvec_push(&rp, "--boundary");
-		 /*
-		  * We must disable the bitmaps because we are removing
-		  * the --objects / --objects-edge[-aggressive] options.
-		  */
+		strvec_push(&rp, "--objects");
 		use_bitmap_index = 0;
 	} else if (thin) {
 		use_internal_rev_list = 1;
diff --git a/path-walk.c b/path-walk.c
index 6e426af433..94ff90bd15 100644
--- a/path-walk.c
+++ b/path-walk.c
@@ -9,6 +9,9 @@
 #include "hashmap.h"
 #include "hex.h"
 #include "list-objects.h"
+#include "list-objects-filter-options.h"
+#include "object-name.h"
+#include "odb.h"
 #include "object.h"
 #include "oid-array.h"
 #include "path.h"
@@ -178,11 +181,6 @@ static int add_tree_entries(struct path_walk_context *ctx,
 			return -1;
 		}
 
-		/* Skip this object if already seen. */
-		if (o->flags & SEEN)
-			continue;
-		o->flags |= SEEN;
-
 		strbuf_setlen(&path, base_len);
 		strbuf_add(&path, entry.path, entry.pathlen);
 
@@ -193,6 +191,40 @@ static int add_tree_entries(struct path_walk_context *ctx,
 		if (type == OBJ_TREE)
 			strbuf_addch(&path, '/');
 
+		if (o->flags & SEEN) {
+			/*
+			 * A tree with a shared OID may appear at multiple
+			 * paths. Even though we already added this tree to
+			 * the output at some other path, we still need to
+			 * walk into it at this in-cone path to discover
+			 * blobs that were not found at the earlier
+			 * out-of-cone path.
+			 *
+			 * Only do this for paths not yet in our map, to
+			 * avoid duplicate entries when the same tree OID
+			 * appears at the same path across multiple commits.
+			 */
+			if (type == OBJ_TREE && ctx->info->pl &&
+			    ctx->info->pl->use_cone_patterns &&
+			    !ctx->info->pl_sparse_trees &&
+			    !strmap_contains(&ctx->paths_to_lists, path.buf)) {
+				int dtype;
+				enum pattern_match_result m;
+				m = path_matches_pattern_list(path.buf, path.len,
+							      path.buf + base_len,
+							      &dtype,
+							      ctx->info->pl,
+							      ctx->repo->index);
+				if (m != NOT_MATCHED) {
+					add_path_to_list(ctx, path.buf, type,
+							 &entry.oid,
+							 !(o->flags & UNINTERESTING));
+					push_to_stack(ctx, path.buf);
+				}
+			}
+			continue;
+		}
+
 		if (ctx->info->pl) {
 			int dtype;
 			enum pattern_match_result match;
@@ -202,7 +234,8 @@ static int add_tree_entries(struct path_walk_context *ctx,
 							  ctx->repo->index);
 
 			if (ctx->info->pl->use_cone_patterns &&
-			    match == NOT_MATCHED)
+			    match == NOT_MATCHED &&
+			    (type == OBJ_BLOB || ctx->info->pl_sparse_trees))
 				continue;
 			else if (!ctx->info->pl->use_cone_patterns &&
 				 type == OBJ_BLOB &&
@@ -237,6 +270,7 @@ static int add_tree_entries(struct path_walk_context *ctx,
 				continue;
 		}
 
+		o->flags |= SEEN;
 		add_path_to_list(ctx, path.buf, type, &entry.oid,
 				 !(o->flags & UNINTERESTING));
 
@@ -249,6 +283,17 @@ static int add_tree_entries(struct path_walk_context *ctx,
 }
 
 /*
+ * Paths starting with '/' (e.g., "/tags", "/tagged-blobs") hold objects that
+ * were directly requested by 'pending' objects rather than discovered during
+ * tree traversal.
+ */
+static int path_is_for_direct_objects(const char *path)
+{
+	ASSERT(path);
+	return path[0] == '/';
+}
+
+/*
  * For each path in paths_to_explore, walk the trees another level
  * and add any found blobs to the batch (but only if they exist and
  * haven't been added yet).
@@ -306,23 +351,57 @@ static int walk_path(struct path_walk_context *ctx,
 
 	if (list->type == OBJ_BLOB &&
 	    ctx->revs->prune_data.nr &&
+	    !path_is_for_direct_objects(path) &&
 	    !match_pathspec(ctx->repo->index, &ctx->revs->prune_data,
 			   path, strlen(path), 0,
 			   NULL, 0))
 		return 0;
 
-	/* Evaluate function pointer on this data, if requested. */
-	if ((list->type == OBJ_TREE && ctx->info->trees) ||
-	    (list->type == OBJ_BLOB && ctx->info->blobs) ||
-	    (list->type == OBJ_TAG && ctx->info->tags))
+	/*
+	 * Evaluate function pointer on this data, if requested.
+	 * Ignore object type filters for tagged objects (path starts
+	 * with `/`), first for blobs and then other types.
+	 */
+	if (list->type == OBJ_BLOB &&
+	    ctx->info->blob_limit &&
+	    !path_is_for_direct_objects(path)) {
+		struct oid_array filtered = OID_ARRAY_INIT;
+
+		for (size_t i = 0; i < list->oids.nr; i++) {
+			unsigned long size;
+
+			if (odb_read_object_info(ctx->repo->objects,
+						 &list->oids.oid[i],
+						 &size) != OBJ_BLOB ||
+				size < ctx->info->blob_limit)
+				oid_array_append(&filtered,
+						 &list->oids.oid[i]);
+		}
+
+		if (filtered.nr)
+			ret = ctx->info->path_fn(path, &filtered, list->type,
+						 ctx->info->path_fn_data);
+		oid_array_clear(&filtered);
+	} else if ((!ctx->info->strict_types && path_is_for_direct_objects(path)) ||
+		   (list->type == OBJ_TREE && ctx->info->trees) ||
+		   (list->type == OBJ_BLOB && ctx->info->blobs) ||
+		   (list->type == OBJ_TAG && ctx->info->tags)) {
 		ret = ctx->info->path_fn(path, &list->oids, list->type,
 					ctx->info->path_fn_data);
+	}
 
-	/* Expand data for children. */
-	if (list->type == OBJ_TREE) {
+	/*
+	 * Expand tree children, except when the set is directly requested
+	 * _and_ we are otherwise filtering out trees.
+	 */
+	if (list->type == OBJ_TREE &&
+	    (!path_is_for_direct_objects(path) || ctx->info->trees)) {
+		/* Use root path if expanding from tagged/direct trees. */
+		const char *expand_path = !strcmp(path, "/tagged-trees")
+					  ? root_path : path;
 		for (size_t i = 0; i < list->oids.nr; i++) {
 			ret |= add_tree_entries(ctx,
-					    path,
+					    expand_path,
 					    &list->oids.oid[i]);
 		}
 	}
@@ -370,14 +449,12 @@ static int setup_pending_objects(struct path_walk_info *info,
 {
 	struct type_and_oid_list *tags = NULL;
 	struct type_and_oid_list *tagged_blobs = NULL;
-	struct type_and_oid_list *root_tree_list = NULL;
+	struct type_and_oid_list *tagged_trees = NULL;
 
 	if (info->tags)
 		CALLOC_ARRAY(tags, 1);
-	if (info->blobs)
-		CALLOC_ARRAY(tagged_blobs, 1);
-	if (info->trees)
-		root_tree_list = strmap_get(&ctx->paths_to_lists, root_path);
+	CALLOC_ARRAY(tagged_blobs, 1);
+	CALLOC_ARRAY(tagged_trees, 1);
 
 	/*
 	 * Pending objects include:
@@ -421,22 +498,19 @@ static int setup_pending_objects(struct path_walk_info *info,
 
 		switch (obj->type) {
 		case OBJ_TREE:
-			if (!info->trees)
-				continue;
-			if (pending->path) {
-				char *path = *pending->path ? xstrfmt("%s/", pending->path)
-							    : xstrdup("");
+			if (pending->path && *pending->path) {
+				char *path = xstrfmt("%s/", pending->path);
 				add_path_to_list(ctx, path, OBJ_TREE, &obj->oid, 1);
 				free(path);
+			} else if (!pending->path || !info->trees) {
+				oid_array_append(&tagged_trees->oids, &obj->oid);
 			} else {
-				/* assume a root tree, such as a lightweight tag. */
-				oid_array_append(&root_tree_list->oids, &obj->oid);
+				add_path_to_list(ctx, root_path, OBJ_TREE,
+						 &obj->oid, 1);
 			}
 			break;
 
 		case OBJ_BLOB:
-			if (!info->blobs)
-				continue;
 			if (pending->path)
 				add_path_to_list(ctx, pending->path, OBJ_BLOB, &obj->oid, 1);
 			else
@@ -469,6 +543,18 @@ static int setup_pending_objects(struct path_walk_info *info,
 			free(tagged_blobs);
 		}
 	}
+	if (tagged_trees) {
+		if (tagged_trees->oids.nr) {
+			const char *tagged_tree_path = "/tagged-trees";
+			tagged_trees->type = OBJ_TREE;
+			tagged_trees->maybe_interesting = 1;
+			strmap_put(&ctx->paths_to_lists, tagged_tree_path, tagged_trees);
+			push_to_stack(ctx, tagged_tree_path);
+		} else {
+			oid_array_clear(&tagged_trees->oids);
+			free(tagged_trees);
+		}
+	}
 	if (tags) {
 		if (tags->oids.nr) {
 			const char *tag_path = "/tags";
@@ -485,6 +571,123 @@ static int setup_pending_objects(struct path_walk_info *info,
 	return 0;
 }
 
+static int prepare_filters_one(struct path_walk_info *info,
+			       struct list_objects_filter_options *options)
+{
+	switch (options->choice) {
+	case LOFC_DISABLED:
+		return 1;
+
+	case LOFC_BLOB_NONE:
+		if (info) {
+			info->blobs = 0;
+			list_objects_filter_release(options);
+		}
+		return 1;
+
+	case LOFC_BLOB_LIMIT:
+		if (info) {
+			if (!options->blob_limit_value)
+				info->blobs = 0;
+			else if (!info->blob_limit ||
+				 info->blob_limit > options->blob_limit_value)
+				info->blob_limit = options->blob_limit_value;
+			list_objects_filter_release(options);
+		}
+		return 1;
+
+	case LOFC_TREE_DEPTH:
+		if (options->tree_exclude_depth) {
+			error(_("tree:%lu filter not supported by the path-walk API"),
+			      options->tree_exclude_depth);
+			return 0;
+		}
+		if (info) {
+			info->trees = 0;
+			info->blobs = 0;
+		}
+		return 1;
+
+	case LOFC_OBJECT_TYPE:
+		if (info) {
+			info->commits &= options->object_type == OBJ_COMMIT;
+			info->tags &= options->object_type == OBJ_TAG;
+			info->trees &= options->object_type == OBJ_TREE;
+			info->blobs &= options->object_type == OBJ_BLOB;
+			info->strict_types = 1;
+			list_objects_filter_release(options);
+		}
+		return 1;
+
+	case LOFC_SPARSE_OID:
+		if (info) {
+			struct object_id sparse_oid;
+			struct repository *repo = info->revs->repo;
+
+			if (info->pl) {
+				warning(_("sparse filter cannot be combined with existing sparse patterns"));
+				return 0;
+			}
+
+			if (repo_get_oid_with_flags(repo,
+						    options->sparse_oid_name,
+						    &sparse_oid,
+						    GET_OID_BLOB)) {
+				error(_("unable to access sparse blob in '%s'"),
+				      options->sparse_oid_name);
+				return 0;
+			}
+
+			CALLOC_ARRAY(info->pl, 1);
+			info->pl->use_cone_patterns = 1;
+
+			if (add_patterns_from_blob_to_list(&sparse_oid, "", 0,
+							   info->pl) < 0) {
+				clear_pattern_list(info->pl);
+				FREE_AND_NULL(info->pl);
+				error(_("unable to parse sparse filter data in '%s'"),
+				      oid_to_hex(&sparse_oid));
+				return 0;
+			}
+
+			if (!info->pl->use_cone_patterns) {
+				clear_pattern_list(info->pl);
+				FREE_AND_NULL(info->pl);
+				warning(_("sparse filter is not cone-mode compatible"));
+				return 0;
+			}
+		}
+		return 1;
+
+	case LOFC_COMBINE:
+		for (size_t i = 0; i < options->sub_nr; i++) {
+			if (!prepare_filters_one(info, &options->sub[i]))
+				return 0;
+		}
+		return 1;
+
+	default:
+		error(_("object filter '%s' not supported by the path-walk API"),
+		      list_objects_filter_spec(options));
+		return 0;
+	}
+}
+
+static int prepare_filters(struct path_walk_info *info,
+			   struct list_objects_filter_options *options)
+{
+	if (!prepare_filters_one(info, options))
+		return 0;
+	if (info)
+		list_objects_filter_release(options);
+	return 1;
+}
+
+int path_walk_filter_compatible(struct list_objects_filter_options *options)
+{
+	return prepare_filters(NULL, options);
+}
+
 /**
  * Given the configuration of 'info', walk the commits based on 'info->revs' and
  * call 'info->path_fn' on each discovered path.
@@ -512,6 +715,9 @@ int walk_objects_by_path(struct path_walk_info *info)
 
 	trace2_region_enter("path-walk", "commit-walk", info->revs->repo);
 
+	if (!prepare_filters(info, &info->revs->filter))
+		return -1;
+
 	CALLOC_ARRAY(commit_list, 1);
 	commit_list->type = OBJ_COMMIT;
 
@@ -532,15 +738,17 @@ int walk_objects_by_path(struct path_walk_info *info)
 	push_to_stack(&ctx, root_path);
 
 	/*
-	 * Set these values before preparing the walk to catch
-	 * lightweight tags pointing to non-commits and indexed objects.
+	 * Ensure that prepare_revision_walk() keeps all pending objects
+	 * even through an object type filter.
 	 */
-	info->revs->blob_objects = info->blobs;
-	info->revs->tree_objects = info->trees;
+	info->revs->blob_objects = info->revs->tree_objects = 1;
 
 	if (prepare_revision_walk(info->revs))
 		die(_("failed to setup revision walk"));
 
+	info->revs->blob_objects = info->blobs;
+	info->revs->tree_objects = info->trees;
+
 	/*
 	 * Walk trees to mark them as UNINTERESTING.
 	 * This is particularly important when 'edge_aggressive' is set.
diff --git a/path-walk.h b/path-walk.h
index 5ef5a8440e..a2652b2d46 100644
--- a/path-walk.h
+++ b/path-walk.h
@@ -36,6 +36,11 @@ struct path_walk_info {
 	/**
 	 * Initialize which object types the path_fn should be called on. This
 	 * could also limit the walk to skip blobs if not set.
+	 *
+	 * Note: even when 'blobs' or 'trees' is disabled, objects that are
+	 * directly requested as pending objects will still be emitted to
+	 * path_fn. Only objects discovered during the tree walk are filtered by
+	 * these flags.
 	 */
 	int commits;
 	int trees;
@@ -43,6 +48,19 @@ struct path_walk_info {
 	int tags;
 
 	/**
+	 * If 'strict_types' is 0, then direct object requests will no longer
+	 * override the object type restrictions.
+	 */
+	int strict_types;
+
+	/**
+	 * If non-zero, specifies a maximum blob size. Blobs with a
+	 * size equal to or greater than this limit will not be
+	 * emitted unless included in 'pending'.
+	 */
+	unsigned long blob_limit;
+
+	/**
 	 * When 'prune_all_uninteresting' is set and a path has all objects
 	 * marked as UNINTERESTING, then the path-walk will not visit those
 	 * objects. It will not call path_fn on those objects and will not
@@ -64,8 +82,14 @@ struct path_walk_info {
 	 * of the cone. If not in cone mode, then all tree paths will be
 	 * explored but the path_fn will only be called when the path matches
 	 * the sparse-checkout patterns.
+	 *
+	 * When 'pl_sparse_trees' is zero, the sparse patterns only restrict
+	 * blobs and all trees are included in the walk output. This matches
+	 * the behavior of the sparse:oid object filter. When nonzero, trees
+	 * are also pruned by the sparse patterns (as used by backfill).
 	 */
 	struct pattern_list *pl;
+	int pl_sparse_trees;
 };
 
 #define PATH_WALK_INFO_INIT {   \
@@ -85,3 +109,10 @@ void path_walk_info_clear(struct path_walk_info *info);
  * Returns nonzero on an error.
  */
 int walk_objects_by_path(struct path_walk_info *info);
+
+struct list_objects_filter_options;
+/**
+ * Given a set of options for filtering objects, return 1 if the options
+ * are compatible with the path-walk API and 0 otherwise.
+ */
+int path_walk_filter_compatible(struct list_objects_filter_options *options);
diff --git a/t/helper/test-path-walk.c b/t/helper/test-path-walk.c
index 69676b15a5..4233badb58 100644
--- a/t/helper/test-path-walk.c
+++ b/t/helper/test-path-walk.c
@@ -4,6 +4,7 @@
 #include "dir.h"
 #include "environment.h"
 #include "hex.h"
+#include "list-objects-filter-options.h"
 #include "object-name.h"
 #include "object.h"
 #include "pretty.h"
@@ -67,10 +68,12 @@ static int emit_block(const char *path, struct oid_array *oids,
 
 int cmd__path_walk(int argc, const char **argv)
 {
-	int res, stdin_pl = 0;
+	int res, stdin_pl = 0, pl_sparse_trees = -1;
 	struct rev_info revs = REV_INFO_INIT;
 	struct path_walk_info info = PATH_WALK_INFO_INIT;
 	struct path_walk_test_data data = { 0 };
+	struct list_objects_filter_options filter_options =
+		LIST_OBJECTS_FILTER_INIT;
 	struct option options[] = {
 		OPT_BOOL(0, "blobs", &info.blobs,
 			 N_("toggle inclusion of blob objects")),
@@ -86,11 +89,14 @@ int cmd__path_walk(int argc, const char **argv)
 			 N_("toggle aggressive edge walk")),
 		OPT_BOOL(0, "stdin-pl", &stdin_pl,
 			 N_("read a pattern list over stdin")),
+		OPT_BOOL(0, "pl-sparse-trees", &pl_sparse_trees,
+			 N_("toggle pruning of trees by sparse patterns")),
+		OPT_PARSE_LIST_OBJECTS_FILTER(&filter_options),
 		OPT_END(),
 	};
 
 	setup_git_directory(the_repository);
-	revs.repo = the_repository;
+	repo_init_revisions(the_repository, &revs, NULL);
 
 	argc = parse_options(argc, argv, NULL,
 			     options, path_walk_usage,
@@ -101,6 +107,10 @@ int cmd__path_walk(int argc, const char **argv)
 	else
 		usage(path_walk_usage[0]);
 
+	/* Apply the filter after setup_revisions to avoid the --objects check. */
+	if (filter_options.choice)
+		list_objects_filter_copy(&revs.filter, &filter_options);
+
 	info.revs = &revs;
 	info.path_fn = emit_block;
 	info.path_fn_data = &data;
@@ -108,6 +118,8 @@ int cmd__path_walk(int argc, const char **argv)
 	if (stdin_pl) {
 		struct strbuf in = STRBUF_INIT;
 		CALLOC_ARRAY(info.pl, 1);
+		info.pl_sparse_trees = (pl_sparse_trees >= 0) ?
+			pl_sparse_trees : 1;
 
 		info.pl->use_cone_patterns = 1;
 
@@ -129,6 +141,7 @@ int cmd__path_walk(int argc, const char **argv)
 		free(info.pl);
 	}
 
+	list_objects_filter_release(&filter_options);
 	release_revisions(&revs);
 	return res;
 }
diff --git a/t/perf/p5315-pack-objects-filter.sh b/t/perf/p5315-pack-objects-filter.sh
new file mode 100755
index 0000000000..445ff25be2
--- /dev/null
+++ b/t/perf/p5315-pack-objects-filter.sh
@@ -0,0 +1,129 @@
+#!/bin/sh
+
+test_description='Tests pack-objects performance with filters and --path-walk'
+. ./perf-lib.sh
+
+test_perf_large_repo
+
+test_expect_success 'setup filter inputs' '
+	# Sample a few depth-2 directories from the test repo to build
+	# a cone-mode sparse-checkout definition.  The sampling picks
+	# directories at evenly-spaced positions so the choice is stable
+	# and scales to repos of any shape.
+
+	git ls-tree -d HEAD >top-entries &&
+	grep "^040000" top-entries |
+		awk "{print \$4;}" >top-dirs &&
+	top_nr=$(wc -l <top-dirs) &&
+
+	while read tdir
+	do
+		git ls-tree -d --format="$tdir/%(path)" "HEAD:$tdir" || return 1
+	done <top-dirs >depth2-dirs &&
+
+	d2_nr=$(wc -l <depth2-dirs) &&
+
+	if test "$d2_nr" -ge 2
+	then
+		# Pick two directories from evenly-spaced positions.
+		first=$(sed -n "1p" depth2-dirs) &&
+		mid=$(sed -n "$((d2_nr / 2 + 1))p" depth2-dirs) &&
+
+		p1=$(dirname "$first") &&
+		p2=$(dirname "$mid") &&
+
+		# Build cone-mode sparse-checkout patterns.
+		{
+			echo "/*" &&
+			echo "!/*/" &&
+			echo "/$p1/" &&
+			echo "!/$p1/*/" &&
+			if test "$p1" != "$p2"
+			then
+				echo "/$p2/" &&
+				echo "!/$p2/*/"
+			fi &&
+			echo "/$first/" &&
+			if test "$first" != "$mid"
+			then
+				echo "/$mid/"
+			fi
+		} >sparse-patterns &&
+
+		git hash-object -w sparse-patterns >sparse-oid &&
+		echo "Sparse cone: $first $mid" &&
+		cat sparse-patterns &&
+		test_set_prereq SPARSE_OID
+	elif test "$top_nr" -ge 1
+	then
+		# Fallback: use a single top-level directory.
+		first=$(sed -n "1p" top-dirs) &&
+		{
+			echo "/*" &&
+			echo "!/*/" &&
+			echo "/$first/"
+		} >sparse-patterns &&
+
+		git hash-object -w sparse-patterns >sparse-oid &&
+		echo "Sparse cone: $first" &&
+		cat sparse-patterns &&
+		test_set_prereq SPARSE_OID
+	fi
+'
+
+test_perf 'repack (no filter)' '
+	git pack-objects --stdout --no-reuse-delta --revs --all </dev/null >pk
+'
+
+test_size 'repack size (no filter)' '
+	test_file_size pk
+'
+
+test_perf 'repack (no filter, --path-walk)' '
+	git pack-objects --stdout --no-reuse-delta --revs --all --path-walk </dev/null >pk
+'
+
+test_size 'repack size (no filter, --path-walk)' '
+	test_file_size pk
+'
+
+test_perf 'repack (blob:none)' '
+	git pack-objects --stdout --no-reuse-delta --revs --all --filter=blob:none </dev/null >pk
+'
+
+test_size 'repack size (blob:none)' '
+	test_file_size pk
+'
+
+test_perf 'repack (blob:none, --path-walk)' '
+	git pack-objects --stdout --no-reuse-delta --revs --all --path-walk \
+		--filter=blob:none </dev/null >pk
+'
+
+test_size 'repack size (blob:none, --path-walk)' '
+	test_file_size pk
+'
+
+test_perf 'repack (sparse:oid)' \
+	--prereq SPARSE_OID '
+	git pack-objects --stdout --no-reuse-delta --revs --all \
+		--filter=sparse:oid=$(cat sparse-oid) </dev/null >pk
+'
+
+test_size 'repack size (sparse:oid)' \
+	--prereq SPARSE_OID '
+	test_file_size pk
+'
+
+test_perf 'repack (sparse:oid, --path-walk)' \
+	--prereq SPARSE_OID '
+	git pack-objects --stdout --no-reuse-delta --revs --all --path-walk \
+		--filter=sparse:oid=$(cat sparse-oid) </dev/null >pk
+'
+
+test_size 'repack size (sparse:oid, --path-walk)' \
+	--prereq SPARSE_OID '
+	test_file_size pk
+'
+
+test_done
diff --git a/t/t5317-pack-objects-filter-objects.sh b/t/t5317-pack-objects-filter-objects.sh
index 501d715b9a..dddb79ba62 100755
--- a/t/t5317-pack-objects-filter-objects.sh
+++ b/t/t5317-pack-objects-filter-objects.sh
@@ -478,4 +478,129 @@ test_expect_success 'verify pack-objects w/ --missing=allow-any' '
 	EOF
 '
 
+# Test that --path-walk produces the same object set as standard traversal
+# when using sparse:oid filters with cone-mode patterns.
+#
+# The sparse:oid filter restricts only blobs, not trees. Both standard
+# and path-walk should produce identical sets of blobs, commits, and trees.
+
+test_expect_success 'setup pw_sparse for path-walk comparison' '
+	git init pw_sparse &&
+	mkdir -p pw_sparse/inc/sub pw_sparse/exc/sub &&
+
+	for n in 1 2
+	do
+		echo "inc $n" >pw_sparse/inc/file$n &&
+		echo "inc sub $n" >pw_sparse/inc/sub/file$n &&
+		echo "exc $n" >pw_sparse/exc/file$n &&
+		echo "exc sub $n" >pw_sparse/exc/sub/file$n &&
+		echo "root $n" >pw_sparse/root$n || return 1
+	done &&
+
+	git -C pw_sparse add . &&
+	git -C pw_sparse commit -m "first" &&
+
+	echo "inc 1 modified" >pw_sparse/inc/file1 &&
+	echo "exc 1 modified" >pw_sparse/exc/file1 &&
+	echo "root 1 modified" >pw_sparse/root1 &&
+	git -C pw_sparse add . &&
+	git -C pw_sparse commit -m "second" &&
+
+	# Cone-mode sparse pattern: include root + inc/
+	printf "/*\n!/*/\n/inc/\n" |
+	git -C pw_sparse hash-object -w --stdin >sparse_oid
+'
+
+test_expect_success 'sparse:oid with --path-walk produces same blobs' '
+	oid=$(cat sparse_oid) &&
+
+	git -C pw_sparse pack-objects --revs --stdout \
+		--filter=sparse:oid=$oid >standard.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C pw_sparse index-pack ../standard.pack &&
+	git -C pw_sparse verify-pack -v ../standard.pack >standard_verify &&
+
+	git -C pw_sparse pack-objects --revs --stdout \
+		--path-walk --filter=sparse:oid=$oid >pathwalk.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C pw_sparse index-pack ../pathwalk.pack &&
+	git -C pw_sparse verify-pack -v ../pathwalk.pack >pathwalk_verify &&
+
+	# Blobs must match exactly
+	grep -E "^[0-9a-f]{40} blob" standard_verify |
+	awk "{print \$1}" | sort >standard_blobs &&
+	grep -E "^[0-9a-f]{40} blob" pathwalk_verify |
+	awk "{print \$1}" | sort >pathwalk_blobs &&
+	test_cmp standard_blobs pathwalk_blobs &&
+
+	# Commits must match exactly
+	grep -E "^[0-9a-f]{40} commit" standard_verify |
+	awk "{print \$1}" | sort >standard_commits &&
+	grep -E "^[0-9a-f]{40} commit" pathwalk_verify |
+	awk "{print \$1}" | sort >pathwalk_commits &&
+	test_cmp standard_commits pathwalk_commits
+'
+
+test_expect_success 'sparse:oid with --path-walk includes all trees' '
+	# The sparse:oid filter restricts only blobs, not trees.
+	# Both standard and path-walk should include the same trees.
+	grep -E "^[0-9a-f]{40} tree" standard_verify |
+	awk "{print \$1}" | sort >standard_trees &&
+	grep -E "^[0-9a-f]{40} tree" pathwalk_verify |
+	awk "{print \$1}" | sort >pathwalk_trees &&
+
+	test_cmp standard_trees pathwalk_trees
+'
+
+# Test the edge case where the same tree/blob OID appears at both an
+# in-cone and out-of-cone path. When sibling directories have identical
+# contents, they share a tree OID. The path-walk defers marking objects
+# SEEN until after checking sparse patterns, so an object at an out-of-cone
+# path can still be discovered at an in-cone path.
+
+test_expect_success 'setup pw_shared for shared OID across cone boundary' '
+	git init pw_shared &&
+	mkdir pw_shared/aaa pw_shared/zzz &&
+	echo "shared content" >pw_shared/aaa/file &&
+	echo "shared content" >pw_shared/zzz/file &&
+	echo "root file" >pw_shared/rootfile &&
+	git -C pw_shared add . &&
+	git -C pw_shared commit -m "aaa and zzz share tree OID" &&
+
+	# Verify they share a tree OID
+	aaa_tree=$(git -C pw_shared rev-parse HEAD:aaa) &&
+	zzz_tree=$(git -C pw_shared rev-parse HEAD:zzz) &&
+	test "$aaa_tree" = "$zzz_tree" &&
+
+	# Cone pattern: include root + zzz/ (not aaa/)
+	printf "/*\n!/*/\n/zzz/\n" |
+	git -C pw_shared hash-object -w --stdin >shared_sparse_oid
+'
+
+test_expect_success 'shared tree OID: --path-walk blobs match standard' '
+	oid=$(cat shared_sparse_oid) &&
+
+	git -C pw_shared pack-objects --revs --stdout \
+		--filter=sparse:oid=$oid >shared_std.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C pw_shared index-pack ../shared_std.pack &&
+	git -C pw_shared verify-pack -v ../shared_std.pack >shared_std_verify &&
+
+	git -C pw_shared pack-objects --revs --stdout \
+		--path-walk --filter=sparse:oid=$oid >shared_pw.pack <<-EOF &&
+	HEAD
+	EOF
+	git -C pw_shared index-pack ../shared_pw.pack &&
+	git -C pw_shared verify-pack -v ../shared_pw.pack >shared_pw_verify &&
+
+	grep -E "^[0-9a-f]{40} blob" shared_std_verify |
+	awk "{print \$1}" | sort >shared_std_blobs &&
+	grep -E "^[0-9a-f]{40} blob" shared_pw_verify |
+	awk "{print \$1}" | sort >shared_pw_blobs &&
+	test_cmp shared_std_blobs shared_pw_blobs
+'
+
 test_done
diff --git a/t/t5620-backfill.sh b/t/t5620-backfill.sh
index 94f35ce190..d2ea68e065 100755
--- a/t/t5620-backfill.sh
+++ b/t/t5620-backfill.sh
@@ -15,6 +15,14 @@ test_expect_success 'backfill rejects unexpected arguments' '
 	test_grep "unrecognized argument: --unexpected-arg" err
 '
 
+test_expect_success 'backfill rejects incompatible filter options' '
+	test_must_fail git backfill --objects --filter=tree:1 2>err &&
+	test_grep "cannot backfill with these filter options" err &&
+
+	test_must_fail git backfill --objects --filter=blob:limit=10m 2>err &&
+	test_grep "cannot backfill with blob size limits" err
+'
+
 # We create objects in the 'src' repo.
 test_expect_success 'setup repo for object creation' '
 	echo "{print \$1}" >print_1.awk &&
diff --git a/t/t6601-path-walk.sh b/t/t6601-path-walk.sh
index 56bd1e3c5b..e9fcd85e75 100755
--- a/t/t6601-path-walk.sh
+++ b/t/t6601-path-walk.sh
@@ -7,17 +7,15 @@ test_description='direct path-walk API tests'
 test_expect_success 'setup test repository' '
 	git checkout -b base &&
 
-	# Make some objects that will only be reachable
-	# via non-commit tags.
-	mkdir child &&
-	echo file >child/file &&
-	git add child &&
-	git commit -m "will abandon" &&
-	git tag -a -m "tree" tree-tag HEAD^{tree} &&
-	echo file2 >file2 &&
-	git add file2 &&
-	git commit --amend -m "will abandon" &&
-	git tag tree-tag2 HEAD^{tree} &&
+	# Create tree objects that are only reachable via tags,
+	# not from any commit in the history.
+	child_blob_oid=$(echo "child blob content" | git hash-object -t blob -w --stdin) &&
+	child_tree_oid=$(printf "100644 blob %s\tfile\n" "$child_blob_oid" | git mktree) &&
+	tree_tag_oid=$(printf "040000 tree %s\tchild\n" "$child_tree_oid" | git mktree) &&
+	git tag -a -m "tree" tree-tag "$tree_tag_oid" &&
+	file2_blob_oid=$(echo "tagged tree file2" | git hash-object -t blob -w --stdin) &&
+	tree_tag2_oid=$(printf "040000 tree %s\tchild\n100644 blob %s\tfile2\n" "$child_tree_oid" "$file2_blob_oid" | git mktree) &&
+	git tag tree-tag2 "$tree_tag2_oid" &&
 
 	echo blob >file &&
 	blob_oid=$(git hash-object -t blob -w --stdin <file) &&
@@ -26,7 +24,7 @@ test_expect_success 'setup test repository' '
 	blob2_oid=$(git hash-object -t blob -w --stdin <file2) &&
 	git tag blob-tag2 "$blob2_oid" &&
 
-	rm -fr child file file2 &&
+	rm -fr file file2 &&
 
 	mkdir left &&
 	mkdir right &&
@@ -34,7 +32,7 @@ test_expect_success 'setup test repository' '
 	echo b >left/b &&
 	echo c >right/c &&
 	git add . &&
-	git commit --amend -m "first" &&
+	git commit -m "first" &&
 	git tag -m "first" first HEAD &&
 
 	echo d >right/d &&
@@ -79,23 +77,23 @@ test_expect_success 'all' '
 	3:tree::$(git rev-parse base^{tree})
 	3:tree::$(git rev-parse base~1^{tree})
 	3:tree::$(git rev-parse base~2^{tree})
-	3:tree::$(git rev-parse refs/tags/tree-tag^{})
-	3:tree::$(git rev-parse refs/tags/tree-tag2^{})
 	4:blob:a:$(git rev-parse base~2:a)
-	5:blob:file2:$(git rev-parse refs/tags/tree-tag2^{}:file2)
-	6:tree:a/:$(git rev-parse base:a)
-	7:tree:child/:$(git rev-parse refs/tags/tree-tag:child)
-	8:blob:child/file:$(git rev-parse refs/tags/tree-tag:child/file)
-	9:tree:left/:$(git rev-parse base:left)
-	9:tree:left/:$(git rev-parse base~2:left)
-	10:blob:left/b:$(git rev-parse base~2:left/b)
-	10:blob:left/b:$(git rev-parse base:left/b)
-	11:tree:right/:$(git rev-parse topic:right)
-	11:tree:right/:$(git rev-parse base~1:right)
-	11:tree:right/:$(git rev-parse base~2:right)
-	12:blob:right/c:$(git rev-parse base~2:right/c)
-	12:blob:right/c:$(git rev-parse topic:right/c)
-	13:blob:right/d:$(git rev-parse base~1:right/d)
+	5:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag^{})
+	5:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag2^{})
+	6:blob:file2:$(git rev-parse refs/tags/tree-tag2^{}:file2)
+	7:tree:a/:$(git rev-parse base:a)
+	8:tree:child/:$(git rev-parse refs/tags/tree-tag:child)
+	9:blob:child/file:$(git rev-parse refs/tags/tree-tag:child/file)
+	10:tree:left/:$(git rev-parse base:left)
+	10:tree:left/:$(git rev-parse base~2:left)
+	11:blob:left/b:$(git rev-parse base~2:left/b)
+	11:blob:left/b:$(git rev-parse base:left/b)
+	12:tree:right/:$(git rev-parse topic:right)
+	12:tree:right/:$(git rev-parse base~1:right)
+	12:tree:right/:$(git rev-parse base~2:right)
+	13:blob:right/c:$(git rev-parse base~2:right/c)
+	13:blob:right/c:$(git rev-parse topic:right/c)
+	14:blob:right/d:$(git rev-parse base~1:right/d)
 	blobs:10
 	commits:4
 	tags:7
@@ -206,6 +204,43 @@ test_expect_success 'base & topic, sparse' '
 	test_cmp_sorted expect out
 '
 
+test_expect_success 'base & topic, sparse, no tree pruning' '
+	cat >patterns <<-EOF &&
+	/*
+	!/*/
+	/left/
+	EOF
+
+	test-tool path-walk --stdin-pl --no-pl-sparse-trees \
+		-- base topic <patterns >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	1:tree::$(git rev-parse topic^{tree})
+	1:tree::$(git rev-parse base^{tree})
+	1:tree::$(git rev-parse base~1^{tree})
+	1:tree::$(git rev-parse base~2^{tree})
+	2:blob:a:$(git rev-parse base~2:a)
+	3:tree:a/:$(git rev-parse base:a)
+	4:tree:left/:$(git rev-parse base:left)
+	4:tree:left/:$(git rev-parse base~2:left)
+	5:blob:left/b:$(git rev-parse base~2:left/b)
+	5:blob:left/b:$(git rev-parse base:left/b)
+	6:tree:right/:$(git rev-parse topic:right)
+	6:tree:right/:$(git rev-parse base~1:right)
+	6:tree:right/:$(git rev-parse base~2:right)
+	blobs:3
+	commits:4
+	tags:0
+	trees:10
+	EOF
+
+	test_cmp_sorted expect out
+'
+
 test_expect_success 'topic only' '
 	test-tool path-walk -- topic >out &&
 
@@ -415,4 +450,483 @@ test_expect_success 'trees are reported exactly once' '
 	test_line_count = 1 out-filtered
 '
 
+test_expect_success 'all, blob:none filter' '
+	test-tool path-walk --filter=blob:none -- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	1:tag:/tags:$(git rev-parse refs/tags/first)
+	1:tag:/tags:$(git rev-parse refs/tags/second.1)
+	1:tag:/tags:$(git rev-parse refs/tags/second.2)
+	1:tag:/tags:$(git rev-parse refs/tags/third)
+	1:tag:/tags:$(git rev-parse refs/tags/fourth)
+	1:tag:/tags:$(git rev-parse refs/tags/tree-tag)
+	1:tag:/tags:$(git rev-parse refs/tags/blob-tag)
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag^{})
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag2^{})
+	3:tree::$(git rev-parse topic^{tree})
+	3:tree::$(git rev-parse base^{tree})
+	3:tree::$(git rev-parse base~1^{tree})
+	3:tree::$(git rev-parse base~2^{tree})
+	4:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag^{})
+	4:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag2^{})
+	5:tree:a/:$(git rev-parse base:a)
+	6:tree:child/:$(git rev-parse refs/tags/tree-tag:child)
+	7:tree:left/:$(git rev-parse base:left)
+	7:tree:left/:$(git rev-parse base~2:left)
+	8:tree:right/:$(git rev-parse topic:right)
+	8:tree:right/:$(git rev-parse base~1:right)
+	8:tree:right/:$(git rev-parse base~2:right)
+	blobs:2
+	commits:4
+	tags:7
+	trees:13
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'topic only, blob:none filter' '
+	test-tool path-walk --filter=blob:none -- topic >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	1:tree::$(git rev-parse topic^{tree})
+	1:tree::$(git rev-parse base~1^{tree})
+	1:tree::$(git rev-parse base~2^{tree})
+	2:tree:left/:$(git rev-parse base~2:left)
+	3:tree:right/:$(git rev-parse topic:right)
+	3:tree:right/:$(git rev-parse base~1:right)
+	3:tree:right/:$(git rev-parse base~2:right)
+	blobs:0
+	commits:3
+	tags:0
+	trees:7
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'all, blob:limit=0 filter' '
+	test-tool path-walk --filter=blob:limit=0 -- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	1:tag:/tags:$(git rev-parse refs/tags/first)
+	1:tag:/tags:$(git rev-parse refs/tags/second.1)
+	1:tag:/tags:$(git rev-parse refs/tags/second.2)
+	1:tag:/tags:$(git rev-parse refs/tags/third)
+	1:tag:/tags:$(git rev-parse refs/tags/fourth)
+	1:tag:/tags:$(git rev-parse refs/tags/tree-tag)
+	1:tag:/tags:$(git rev-parse refs/tags/blob-tag)
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag^{})
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag2^{})
+	3:tree::$(git rev-parse topic^{tree})
+	3:tree::$(git rev-parse base^{tree})
+	3:tree::$(git rev-parse base~1^{tree})
+	3:tree::$(git rev-parse base~2^{tree})
+	4:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag^{})
+	4:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag2^{})
+	5:tree:a/:$(git rev-parse base:a)
+	6:tree:child/:$(git rev-parse refs/tags/tree-tag:child)
+	7:tree:left/:$(git rev-parse base:left)
+	7:tree:left/:$(git rev-parse base~2:left)
+	8:tree:right/:$(git rev-parse topic:right)
+	8:tree:right/:$(git rev-parse base~1:right)
+	8:tree:right/:$(git rev-parse base~2:right)
+	blobs:2
+	commits:4
+	tags:7
+	trees:13
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'all, blob:limit=3 filter' '
+	test-tool path-walk --filter=blob:limit=3 -- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	1:tag:/tags:$(git rev-parse refs/tags/first)
+	1:tag:/tags:$(git rev-parse refs/tags/second.1)
+	1:tag:/tags:$(git rev-parse refs/tags/second.2)
+	1:tag:/tags:$(git rev-parse refs/tags/third)
+	1:tag:/tags:$(git rev-parse refs/tags/fourth)
+	1:tag:/tags:$(git rev-parse refs/tags/tree-tag)
+	1:tag:/tags:$(git rev-parse refs/tags/blob-tag)
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag^{})
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag2^{})
+	3:tree::$(git rev-parse topic^{tree})
+	3:tree::$(git rev-parse base^{tree})
+	3:tree::$(git rev-parse base~1^{tree})
+	3:tree::$(git rev-parse base~2^{tree})
+	4:blob:a:$(git rev-parse base~2:a)
+	5:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag^{})
+	5:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag2^{})
+	6:tree:a/:$(git rev-parse base:a)
+	7:tree:child/:$(git rev-parse refs/tags/tree-tag:child)
+	8:tree:left/:$(git rev-parse base:left)
+	8:tree:left/:$(git rev-parse base~2:left)
+	9:blob:left/b:$(git rev-parse base~2:left/b)
+	10:tree:right/:$(git rev-parse topic:right)
+	10:tree:right/:$(git rev-parse base~1:right)
+	10:tree:right/:$(git rev-parse base~2:right)
+	11:blob:right/c:$(git rev-parse base~2:right/c)
+	12:blob:right/d:$(git rev-parse base~1:right/d)
+	blobs:6
+	commits:4
+	tags:7
+	trees:13
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'all, tree:0 filter' '
+	test-tool path-walk --filter=tree:0 -- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	1:tag:/tags:$(git rev-parse refs/tags/first)
+	1:tag:/tags:$(git rev-parse refs/tags/second.1)
+	1:tag:/tags:$(git rev-parse refs/tags/second.2)
+	1:tag:/tags:$(git rev-parse refs/tags/third)
+	1:tag:/tags:$(git rev-parse refs/tags/fourth)
+	1:tag:/tags:$(git rev-parse refs/tags/tree-tag)
+	1:tag:/tags:$(git rev-parse refs/tags/blob-tag)
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag^{})
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag2^{})
+	3:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag^{tree})
+	3:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag2)
+	blobs:2
+	commits:4
+	tags:7
+	trees:2
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'topic only, tree:0 filter' '
+	test-tool path-walk --filter=tree:0 -- topic >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	blobs:0
+	commits:3
+	tags:0
+	trees:0
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'tree:1 filter is rejected' '
+	test_must_fail test-tool path-walk --filter=tree:1 -- --all 2>err &&
+	test_grep "tree:1 filter not supported by the path-walk API" err
+'
+
+test_expect_success 'all, object:type=commit filter' '
+	test-tool path-walk --filter=object:type=commit -- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	blobs:0
+	commits:4
+	tags:0
+	trees:0
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'all, object:type=tag filter' '
+	test-tool path-walk --filter=object:type=tag -- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:tag:/tags:$(git rev-parse refs/tags/first)
+	0:tag:/tags:$(git rev-parse refs/tags/second.1)
+	0:tag:/tags:$(git rev-parse refs/tags/second.2)
+	0:tag:/tags:$(git rev-parse refs/tags/third)
+	0:tag:/tags:$(git rev-parse refs/tags/fourth)
+	0:tag:/tags:$(git rev-parse refs/tags/tree-tag)
+	0:tag:/tags:$(git rev-parse refs/tags/blob-tag)
+	blobs:0
+	commits:0
+	tags:7
+	trees:0
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'all, object:type=tree filter' '
+	test-tool path-walk --filter=object:type=tree -- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:tree::$(git rev-parse topic^{tree})
+	0:tree::$(git rev-parse base^{tree})
+	0:tree::$(git rev-parse base~1^{tree})
+	0:tree::$(git rev-parse base~2^{tree})
+	1:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag^{})
+	1:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag2^{})
+	2:tree:a/:$(git rev-parse base:a)
+	3:tree:child/:$(git rev-parse refs/tags/tree-tag:child)
+	4:tree:left/:$(git rev-parse base:left)
+	4:tree:left/:$(git rev-parse base~2:left)
+	5:tree:right/:$(git rev-parse topic:right)
+	5:tree:right/:$(git rev-parse base~1:right)
+	5:tree:right/:$(git rev-parse base~2:right)
+	blobs:0
+	commits:0
+	tags:0
+	trees:13
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'all, object:type=blob filter' '
+	test-tool path-walk --filter=object:type=blob -- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag^{})
+	0:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag2^{})
+	1:blob:a:$(git rev-parse base~2:a)
+	2:blob:left/b:$(git rev-parse base:left/b)
+	2:blob:left/b:$(git rev-parse base~2:left/b)
+	3:blob:right/c:$(git rev-parse base~2:right/c)
+	3:blob:right/c:$(git rev-parse topic:right/c)
+	4:blob:right/d:$(git rev-parse base~1:right/d)
+	blobs:8
+	commits:0
+	tags:0
+	trees:0
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'all, combine:blob:none+tree:0 filter' '
+	test-tool path-walk \
+		--filter=combine:blob:none+tree:0 -- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	1:tag:/tags:$(git rev-parse refs/tags/first)
+	1:tag:/tags:$(git rev-parse refs/tags/second.1)
+	1:tag:/tags:$(git rev-parse refs/tags/second.2)
+	1:tag:/tags:$(git rev-parse refs/tags/third)
+	1:tag:/tags:$(git rev-parse refs/tags/fourth)
+	1:tag:/tags:$(git rev-parse refs/tags/tree-tag)
+	1:tag:/tags:$(git rev-parse refs/tags/blob-tag)
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag^{})
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag2^{})
+	3:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag^{tree})
+	3:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag2)
+	blobs:2
+	commits:4
+	tags:7
+	trees:2
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'all, combine:object:type=blob+blob:limit=3 filter' '
+	test-tool path-walk \
+		--filter=combine:object:type=blob+blob:limit=3 \
+		-- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag^{})
+	0:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag2^{})
+	1:blob:a:$(git rev-parse base~2:a)
+	2:blob:left/b:$(git rev-parse base~2:left/b)
+	3:blob:right/c:$(git rev-parse base~2:right/c)
+	4:blob:right/d:$(git rev-parse base~1:right/d)
+	blobs:6
+	commits:0
+	tags:0
+	trees:0
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'all, combine of disjoint object:types is empty' '
+	test-tool path-walk \
+		--filter=combine:object:type=blob+object:type=tree \
+		-- --all >out &&
+
+	cat >expect <<-EOF &&
+	blobs:0
+	commits:0
+	tags:0
+	trees:0
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'combine: rejects unsupported subfilters' '
+	test_must_fail test-tool path-walk \
+		--filter=combine:tree:1+blob:none -- --all 2>err &&
+	test_grep "tree:1 filter not supported by the path-walk API" err
+'
+
+test_expect_success 'setup sparse filter blob' '
+	# Cone-mode patterns: include root, exclude all dirs, include left/
+	cat >patterns <<-\EOF &&
+	/*
+	!/*/
+	/left/
+	EOF
+	sparse_oid=$(git hash-object -w -t blob patterns)
+'
+
+test_expect_success 'all, sparse:oid filter' '
+	test-tool path-walk --filter=sparse:oid=$sparse_oid -- --all >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	1:tag:/tags:$(git rev-parse refs/tags/first)
+	1:tag:/tags:$(git rev-parse refs/tags/second.1)
+	1:tag:/tags:$(git rev-parse refs/tags/second.2)
+	1:tag:/tags:$(git rev-parse refs/tags/third)
+	1:tag:/tags:$(git rev-parse refs/tags/fourth)
+	1:tag:/tags:$(git rev-parse refs/tags/tree-tag)
+	1:tag:/tags:$(git rev-parse refs/tags/blob-tag)
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag^{})
+	2:blob:/tagged-blobs:$(git rev-parse refs/tags/blob-tag2^{})
+	3:tree::$(git rev-parse topic^{tree})
+	3:tree::$(git rev-parse base^{tree})
+	3:tree::$(git rev-parse base~1^{tree})
+	3:tree::$(git rev-parse base~2^{tree})
+	4:blob:a:$(git rev-parse base~2:a)
+	5:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag^{})
+	5:tree:/tagged-trees:$(git rev-parse refs/tags/tree-tag2^{})
+	6:blob:file2:$(git rev-parse refs/tags/tree-tag2^{}:file2)
+	7:tree:a/:$(git rev-parse base:a)
+	8:tree:child/:$(git rev-parse refs/tags/tree-tag:child)
+	9:tree:left/:$(git rev-parse base:left)
+	9:tree:left/:$(git rev-parse base~2:left)
+	10:blob:left/b:$(git rev-parse base~2:left/b)
+	10:blob:left/b:$(git rev-parse base:left/b)
+	11:tree:right/:$(git rev-parse topic:right)
+	11:tree:right/:$(git rev-parse base~1:right)
+	11:tree:right/:$(git rev-parse base~2:right)
+	blobs:6
+	commits:4
+	tags:7
+	trees:13
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+test_expect_success 'topic only, sparse:oid filter' '
+	test-tool path-walk --filter=sparse:oid=$sparse_oid -- topic >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse topic)
+	0:commit::$(git rev-parse base~1)
+	0:commit::$(git rev-parse base~2)
+	1:tree::$(git rev-parse topic^{tree})
+	1:tree::$(git rev-parse base~1^{tree})
+	1:tree::$(git rev-parse base~2^{tree})
+	2:blob:a:$(git rev-parse base~2:a)
+	3:tree:left/:$(git rev-parse base~2:left)
+	4:blob:left/b:$(git rev-parse base~2:left/b)
+	5:tree:right/:$(git rev-parse topic:right)
+	5:tree:right/:$(git rev-parse base~1:right)
+	5:tree:right/:$(git rev-parse base~2:right)
+	blobs:2
+	commits:3
+	tags:0
+	trees:7
+	EOF
+
+	test_cmp_sorted expect out
+'
+
+# Demonstrate the SEEN flag ordering issue: when the same tree/blob OID
+# appears at two sibling paths where one is in-cone and the other is
+# out-of-cone, the path-walk must still discover blobs at the in-cone
+# path even when the shared tree OID was first encountered out-of-cone.
+# Since sparse:oid includes all trees, the out-of-cone tree (aaa/) is
+# walked first, and its blob is skipped. The path-walk then re-walks
+# the same tree OID at the in-cone path (zzz/) to find the blob there.
+
+test_expect_success 'setup shared tree OID across cone boundary' '
+	git checkout --orphan shared-tree &&
+	git rm -rf . &&
+	mkdir aaa zzz &&
+	echo "shared content" >aaa/file &&
+	echo "shared content" >zzz/file &&
+	echo "root file" >rootfile &&
+	git add aaa zzz rootfile &&
+	git commit -m "aaa and zzz have same tree OID" &&
+
+	# Verify they really share a tree OID
+	aaa_tree=$(git rev-parse HEAD:aaa) &&
+	zzz_tree=$(git rev-parse HEAD:zzz) &&
+	test "$aaa_tree" = "$zzz_tree" &&
+
+	# Cone pattern: include root + zzz/ (not aaa/)
+	cat >shared-patterns <<-\EOF &&
+	/*
+	!/*/
+	/zzz/
+	EOF
+	shared_sparse_oid=$(git hash-object -w -t blob shared-patterns)
+'
+
+test_expect_success 'sparse:oid with shared tree OID across cone boundary' '
+	test-tool path-walk \
+		--filter=sparse:oid=$shared_sparse_oid \
+		-- shared-tree >out &&
+
+	cat >expect <<-EOF &&
+	0:commit::$(git rev-parse shared-tree)
+	1:tree::$(git rev-parse shared-tree^{tree})
+	2:blob:rootfile:$(git rev-parse shared-tree:rootfile)
+	3:tree:aaa/:$(git rev-parse shared-tree:aaa)
+	4:tree:zzz/:$(git rev-parse shared-tree:zzz)
+	5:blob:zzz/file:$(git rev-parse shared-tree:zzz/file)
+	blobs:2
+	commits:1
+	tags:0
+	trees:3
+	EOF
+
+	test_cmp_sorted expect out
+'
+
 test_done