[PHP] Add exact local cleanup to file sync patches

[adamziel]

File sync cleanup can now remove selected indexed paths without removing skipped or excluded children.

FileSyncPatchProcessor::start_from_fresh_local_tree() plans exact deletions. The push direction keeps collapsing deleted subtrees to one root.

FileSyncCleanupProcessor removes one exact file, link, or empty directory per step. It uses unlink() and rmdir() and never walks a directory recursively. If a cache, storage, excluded, or newly created child remains, its parent remains too. After the exact removals, cleanup prunes one unchanged empty parent per step.

The cursor stores a pending removal and the local type, size, and ctime seen by the fresh scan. Cleanup checks those fields before removing the path. If they changed, it returns restart and leaves the new path alone.

$cleanup = FileSyncCleanupProcessor::start(
    $work_directory,
    $filesystem_root,
    $patch_result_index,
    $storage_path,
    ["wp-content"],
    ["wp-content/uploads/keep"]
);

do {
    $has_next_step = $cleanup->next_step();
    $cleanup->flush_pending_output();
    save_cursor($cleanup->get_cursor());
} while ($has_next_step);

$status = $cleanup->get_status();
$cleanup->close();

if ($status === "restart") {
    restart_file_sync();
}

[github-actions]

Pull pipeline performance — large-directory

Site: large-directory · 2,000+ plus targeted file-transfer scenarios files · 10,000 posts · 25,000 postmeta · PHP 8.5.9

Stage	PR	trunk	Δ	Status	Details
playground-sqlite-db-pull	10.27 s	9.59 s	⚪ +678 ms (+7.1%)	✓	condition=db-pull in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=lexer native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=selected trunk: condition=db-pull in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=lexer native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=selected
playground-sqlite-db-apply	3.75 s	3.74 s	⚪ +17 ms (+0.5%)	✓	condition=db-apply to SQLite in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=parser native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=verified native_ast=WP_MySQL_Native_Parser_Node sqlite_driver_parser=verified trunk: condition=db-apply to SQLite in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=parser native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=verified native_ast=WP_MySQL_Native_Parser_Node sqlite_driver_parser=verified
Total	14.02 s	13.33 s	⚪ +695 ms (+5.2%)

_{Numbers carry runner noise; treat single-run deltas as directional, not authoritative.}

_{📈 Trunk performance history — commit-by-commit timeline.}