refactor: Rename Leaf to DeltaSpace for semantic clarity

- Renamed Leaf class to DeltaSpace throughout the codebase
- Updated all imports, method signatures, and variable names
- Updated documentation and comments to reflect the new naming
- DeltaSpace better represents a container for delta-compressed files

The term "DeltaSpace" is more semantically accurate than "Leaf" as it
represents a space/container for managing related files with delta
compression, not a terminal node in a tree structure.

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

docs/deltaglider_architecture_guidelines.txt

@@ -42,21 +42,21 @@ interface DiffPort {
 interface HashPort { sha256(pathOrStream) -> Sha256 }
 
 interface CachePort {
-  refPath(bucket, leaf) -> Path
-  hasRef(bucket, leaf, sha) -> Bool
-  writeRef(bucket, leaf, src) -> Path
-  evict(bucket, leaf)
+  refPath(bucket, prefix) -> Path
+  hasRef(bucket, prefix, sha) -> Bool
+  writeRef(bucket, prefix, src) -> Path
+  evict(bucket, prefix)
 }
 
 interface DeltaService {
-  put(localFile, leaf, maxRatio) -> PutSummary
+  put(localFile, deltaSpace, maxRatio) -> PutSummary
   get(deltaKey, out) -> void
   verify(deltaKey) -> VerifyResult
 }
 
 4. Domain Use-Cases
 -------------------
-put(localFile, leaf):
+put(localFile, deltaSpace):
 - If no reference.bin: upload as reference, cache, create zero-diff delta.
 - Else: ensure cached reference valid, generate delta, upload with metadata.
 
@@ -69,7 +69,7 @@ verify(deltaKey):
 
 5. Object Model
 ---------------
-- Leaf { bucket, prefix }
+- DeltaSpace { bucket, prefix }
 - ObjectKey { bucket, key }
 - Sha256 { hex }
 - DeltaMeta { tool, original_name, file_sha256, file_size, created_at, ref_key, ref_sha256, delta_size, note? }

docs/deltaglider_metadata_schema.txt

@@ -12,7 +12,7 @@ General Rules
 
 Reference Object (`reference.bin`)
 ---------------------------------
-Stored once per leaf prefix.
+Stored once per DeltaSpace prefix.
 
 Required keys:
 - tool: deltaglider/0.1.0
@@ -31,7 +31,7 @@ Required keys:
 - file_sha256: SHA256 of hydrated file
 - file_size: size in bytes of hydrated file
 - created_at: ISO8601 UTC timestamp
-- ref_key: key of reference file (e.g. path/to/leaf/reference.bin)
+- ref_key: key of reference file (e.g. path/to/delta_space/reference.bin)
 - ref_sha256: SHA256 of reference file
 - delta_size: size in bytes of delta file
 - delta_cmd: "xdelta3 -e -9 -s reference.bin <file> <file>.delta"

docs/deltaglider_specs.txt

@@ -12,14 +12,14 @@ The cost of storing large binary artifacts (e.g., ZIP plugins, deliverables) on
 by only a few kilobytes. Current practice redundantly uploads full versions, wasting space and increasing transfer times.
 
 deltaglider is a CLI tool that transparently reduces storage overhead by representing a directory of similar large files as:
-- A single reference file (reference.bin) in each leaf S3 prefix.
+- A single reference file (reference.bin) in each DeltaSpace S3 prefix.
 - A set of delta files (<original>.delta) encoding differences against the reference.
 
 This approach compresses storage usage to near-optimal while retaining simple semantics.
 
 Goals
 -----
-1. Save S3 space by storing only one full copy of similar files per leaf and small binary deltas for subsequent versions.
+1. Save S3 space by storing only one full copy of similar files per DeltaSpace and small binary deltas for subsequent versions.
 2. Transparent developer workflow – deltaglider put/get mirrors aws s3 cp.
 3. Minimal state management – no manifests, no external databases.
 4. Integrity assurance – strong hashing (SHA256) stored in metadata, verified on upload/restore.
@@ -28,19 +28,19 @@ Goals
 Non-Goals
 ---------
 - Deduplication across multiple directories/prefixes.
-- Streaming delta generation across multiple references (always one reference per leaf).
+- Streaming delta generation across multiple references (always one reference per DeltaSpace).
 - Automatic background compaction or garbage collection.
 
 Terminology
 -----------
-- Leaf prefix: An S3 "directory" containing only files, no further sub-prefixes.
-- Reference file: The first uploaded file in a leaf, stored as reference.bin.
+- DeltaSpace: An S3 prefix containing related files for delta compression.
+- Reference file: The first uploaded file in a DeltaSpace, stored as reference.bin.
 - Delta file: Result of running xdelta3 against the reference, named <original>.delta.
 
 Architecture
 ------------
 Reference Selection
-- First uploaded file in a leaf becomes the reference.
+- First uploaded file in a DeltaSpace becomes the reference.
 - Stored as reference.bin.
 - Original filename preserved in metadata of both reference.bin and zero-diff delta.
 
@@ -68,7 +68,7 @@ Local Cache
 
 CLI Specification
 -----------------
-deltaglider put <file> <s3://bucket/path/to/leaf/>
+deltaglider put <file> <s3://bucket/path/to/delta_space/>
 - If no reference.bin: upload <file> as reference.bin, upload zero-diff <file>.delta.
 - If reference.bin exists: create delta, upload <file>.delta with metadata.
 - Output JSON summary.