ba1212361f
Commit the previously-untracked standard directories and catalog them in the
root README alongside proof:
- aac/ — communication cargo class: portable boards + a ten-level
offline-first cascade (Apache-2.0 code / CC-BY-4.0 spec).
- map/ — geospatial cargo class: range-requestable signed tilesets +
an F0–F4 fidelity cascade (Apache-2.0 code / CC-BY-4.0 spec).
- sandbox/— isolated, metered, attested execution across the heterogeneous
compute fabric (Apache-2.0 code / CC-BY-4.0 spec).
- jouleclaw-otel-authz, jouleclaw-trust — new jouleclaw reference crates.
Root README now lists aac, map, sandbox, and proof in the catalog, the tree,
and the contribution guide.
Co-Authored-By: Claude Opus 4.8 <[email protected]>
1.9 KiB
Map sub-spec — The tileset container
Normative refinement of SPEC §4. Reference: map-schema::{Directory, DirEntry}.
A tileset is one addressable blob on dumb storage (object store, static host, OPFS) — the "it's just a file" deliverable. It has three parts.
1. Header
A fixed prefix carrying a magic tag, the standard version, the datum, the
AltSchedule, and the byte offset of the directory. A reader fetches the header
(a small fixed range) first.
2. Directory
An ordered table of DirEntry { key: CellKey, offset: u64, len: u64, content_id }.
- It MUST be sorted by the canonical
CellKeyorder (S2/Hilbert first), so the tiles of one viewport occupy a near-contiguous byte range. - A reader computes the cell keys a viewport needs, looks each up
(
Directory::locate, binary search), and coalesces the results into the minimal set of byte ranges (Directory::ranges_for) to fetch over HTTP range requests — no server-side logic, no per-request billing. - The Merkle leaf for each entry commits to
(key, content_id)only, not the byte offset. Re-laying-out the file (compaction, re-ordering payloads) therefore does not change the directory root the manifest signs (SPEC §5).
3. Payloads
Content-addressable, independently decodable tile bodies. A reader MUST
verify that each fetched payload hashes to the content_id the directory
claims, and MUST NOT be required to download the whole tileset to render a
viewport.
Range-request planner
Directory::ranges_for(viewport_cells) returns coalesced (start, end) spans.
Because the directory is Hilbert-sorted, a contiguous viewport collapses to one
or a few spans rather than one request per tile — the Protomaps insight,
preserved. Conformance suite C2 pins this against the sample tileset in
../conformance/v1/tileset_vectors.json.