Text-driven indoor scene generation and editing require an intermediate representation that language models can both produce and revise. Existing LLM-based systems often rely on scene graphs or global constraint lists, which are compact but underspecify local geometry and make instruction-based edits difficult to localize. We frame the task as structured program generation and local program repair, and propose the Hierarchical Descriptive Scene Language (HDSL), an XML/CSS-style domain-specific language in which rooms, regions, objects, and support surfaces form a tree with parent-relative local coordinates. Our pipeline generates HDSL subtrees recursively with bounded verification, grounds non-virtual nodes through multimodal asset retrieval, and applies force-directed layout optimization to repair boundary and collision errors. For editing, Hierarchical Retrieval-Augmented Generation retrieves the relevant subtree, rewrites only that local context, and merges the result back through a deterministic three-way merge. In our reproduced benchmark, HDSL improves average object coverage, text-scene alignment, and generation time over full text-to-scene baselines while remaining competitive with layout-only reproductions on geometry metrics. On thirty paired editing instructions, HRAG reduces token use by 67.6% and runtime by 68.1%, and cuts non-target removals by 87.5% over full-scene rewriting; attribute ablations confirm that local coordinates and virtual/leaf flags are necessary for valid, locality-preserving edits.