Add the transport skeleton composer, rules registry and local build driver (NZ graph G6)

changelog.d/transport-compose-cli.added.md

@@ -0,0 +1,21 @@
+Add the transport skeleton composer, its local-only build driver and
+`tools/build_transport.py`. A country's `transport_graph.json` spec resource
+declares the skeleton graph; each node binds only the spec resources it
+selects, every rules node runs through the one `simulate.rules_by_ref@1`
+router, and later packages append branches through a typed extension point
+that cannot re-key the skeleton. The driver runs ancestor-closed checkpoints
+on `<out>/.graph-store` and writes every output under `--out`; it refuses an
+existing store tree that contains a link, which could redirect store writes.
+Activation checks every selected resource and reference set and every null
+scenario knob before donor preparation. Calibration ancestry refuses hold-out
+selections and sources, benefit-unit engine references, and graph digests.
+Selected resource lists remain literal data. The driver writes deterministic
+HDF5 container bytes while readback continues to hash the complete file.
+CREATE inventories are cached by implementation, parameters and source bytes;
+a cold build runs CREATE twice, and a warm inventory does not run the probe.
+Cold `--resume require` builds refuse before preparation. Local spec directories
+are protected from output overlap, node ids must be safe filenames, and
+extensions receive independent spec copies.
+Extensions can declare new sources and pre-export checkpoints, and use
+`transport_rules_node` to obtain a binding's engine reference and period.
+The locality property is parametrized over every selected resource.

changelog.d/transport-rules-registry.added.md

@@ -0,0 +1,9 @@
+Add explicit transport registry preparation with pinned Axiom bindings, one
+multi-engine rules kernel, shared calibration and terminal kernels, and the
+transport gate bindings. Engines use the persons-households-benefit-units
+schema and nesting that the benefit-unit rule declares (the schema CREATE
+builds). Engine-free adapters can exercise registry dispatch without
+installing a country engine. Module hashes and tree digests bind the actual
+RuleSpec bytes. Engine commit and wheel SHA-256 pins, and the RuleSpec commit
+for exported trees, are format-checked caller declarations; installed engine
+provenance is not checked.

docs/agent-guide.md

@@ -339,6 +339,35 @@ Update this guide in the same PR whenever the workspace layout, test
 commands, or release flow change. If you find it contradicting the repo,
 trust the repo and fix this file.
 
+The transport build driver (`tools/build_transport.py`, a shim over
+`microcosm.build.transport.cli`) composes a country's graph from its
+`transport_graph.json` spec resource and runs it locally: every file it
+writes, including its `.graph-store`, lies under `--out`, and it has no
+upload or staging path. Before it opens the store it refuses any link in an
+existing store tree (the root, `objects`, `tmp` or a shard), because the
+store creates those directories by following links; it does not guard
+against links planted while a build is running. It refuses before reading any graph source while the
+country spec still has unresolved evidence: every selected resource/reference
+set and every null scenario knob is checked before donor preparation.
+Tests for it run on the engine-free toy package in
+`test_support/microcosm_build/transport_composed.py`. The rules registry checks
+module hashes and binds the RuleSpec tree digest. Engine commit and wheel
+SHA-256 pins, and the RuleSpec commit for exported trees, are format-checked
+caller declarations; installed engine provenance is not checked.
+Fresh driver runs write identical HDF5 bytes with object timestamps disabled;
+readback keys continue to include the complete container bytes. CREATE's column
+inventory is cached by implementation, parameters and source bytes. A cold
+build runs CREATE twice (inventory probe and graph execution); warm inventory
+lookups hash the inputs without running the probe. Cold `--resume require`
+refuses before preparation. Output directories must also be disjoint from a
+local `--spec-dir`.
+G7 extensions can wrap a factory in `TransportExtension` to declare additional
+sources and ordered checkpoints. Source names must be new; skeleton predecessor
+sets must stay identical. Checkpoints run after calibration and before export,
+and must not depend on the exported dataset. `transport_rules_node` supplies
+the prepared engine reference and period from the binding, so extensions do
+not repeat period values.
+
 UK size experiments use `microcosm-build-uk --release-role dense --dataset-households`
 (`tools/build_uk_full.py`; `tools/build_uk_rowwise_candidate.py` is a stub over it)
 with the same pool inputs as the dense candidate. The flag changes exported