Mechanical move-only extraction for backlog#1840 PR1+PR4: the site-replication state (load/parse/persist/RMW transaction), repair state machine, peer transport (client cache, DNS resolver, send_peer_* family), retry queue, and the four storage-side hooks move from rustfs/src/admin/handlers/site_replication.rs into the new infra-layer module rustfs/src/site_replication/ ({mod,state,state_lock,identity,transport,retry,repair,hooks}.rs). The admin handler file keeps route registration, all Operation impls, request/response glue, and the in-file test module, and re-exports the moved items so existing paths keep resolving. admin/site_replication_identity.rs and admin/site_replication_state.rs relocate wholesale as identity.rs/state_lock.rs.
Storage access from the moved code goes through a new site_replication consumer module in the root facade (rustfs/src/storage_api.rs), including an s3 shim so the module stays off the direct s3s surface (file count stays at the 215 baseline). The three admin runtime-source wrappers the moved code needs (outbound TLS generation incl. the test atomic, outbound TLS state, runtime port) are reproduced locally; the TLS-generation trio moves out of admin/runtime_sources.rs since site replication was its only consumer. The one non-verbatim rewrite: site_replication_peer_payload inlines encrypt_stream_io in its encrypted branch, which is provably the branch encode_compatible_admin_payload always took for the /minio/admin peer-join wire path.
app/bucket_usecase.rs now imports the three bucket hooks from crate::site_replication, deleting the three app->interface entries from the layer baseline (shrink-only). The peer-client cache test moves with the owner-local SITE_REPLICATION_PEER_CLIENT static into transport.rs (228+1 = 229 tests conserved). New module files are added to the logging-guardrail checked list; the s3_error! line baseline tightens 1620 -> 1619; global-state/config-consumer inventories and ARCHITECTURE.md pointers updated.
Verified: cargo check -p rustfs --all-targets clean; cargo clippy --workspace --all-targets clean; cargo nextest run -p rustfs --lib 3852/3852 passed; make pre-commit green; scripts/check_layer_dependencies.sh green with baseline-only deletions; line-multiset conservation audit over the moved code accounts for every non-verbatim line (visibility bumps, import rewrites, fmt reflow).
Refs rustfs/backlog#1840
backlog#1834 PR5. Whether the scanner, heal, audit and notify modules are on gets read from infra (storage helpers, node-service RPC) and from interface (admin handlers), but the switches lived in startup_background (composition) and server (interface). Every one of those reads was an upward edge carried in the layer-dependency baseline.
The env-derived scanner/heal predicates and the audit/notify state cells now live in rustfs/src/module_switches.rs, at the bottom of the layer order, so the same reads are ordinary downward edges. startup_background and server import from there; server keeps re-exporting the getters for its own consumers.
The issue's plan was to move is/refresh_audit/notify_module_enabled as a group. Moving refresh_* wholesale would have dragged resolve_audit_module_state and resolve_notify_module_state — server-side configuration logic — down into infra, which breaks more layering than it fixes. State and resolution are split instead: module_switches owns the atomics plus is_*/set_* accessors, and server's refresh_* keeps the configuration logic and publishes through the setter.
That leaves storage/helper.rs's test module importing refresh_* from server, so two infra->interface edges stay. Those tests assert that a configuration change takes effect through refresh, which a plain setter would no longer exercise; the edges are worth more than the two baseline lines.
Baseline drops 44 -> 36 lines, deletions only:
- 4 interface/infra -> composition edges for ENV_SCANNER_ENABLED, scanner_enabled_from_env and heal_enabled_from_env
- 2 infra -> interface edges for is_audit_module_enabled and is_notify_module_enabled
- cycle|composition<->infra and cycle|composition<->interface
The two cycles were not expected to go until whole subsystems moved out; clearing composition's inbound upward edges dissolved both, leaving three of the original five.
Verification: scripts/check_layer_dependencies.sh passes, cargo check -p rustfs warning-free, make pre-commit exit 0.
RemoteAddr, the DependencyReadiness family (DependencyReadiness, ReadinessDegradedReason, DependencyReadinessReport), and convert_ecstore_object_info (with its offset_date_time_to_timestamp helper) are consumed across app, infra, and interface layers but lived under server, so every lower-layer import was an upward app->interface or infra->interface edge the layer guard had to baseline.
They now live in a new layer-neutral rustfs/src/shared_types.rs (classified infra by the guard, making all consumer imports downward or lateral). server::readiness and server::event re-export for their own internals; the eight consumer sites (admin_usecase, bucket_usecase, object_usecase, cluster_snapshot, storage/access, storage/helper, plus the admin handler tests) import from the new home. Pure move: no type, impl, or behavior change.
The regenerated layer-dependency baseline shrinks by exactly eight lines with zero additions — the ratchet's intended direction. The two remaining readiness entries (collect/snapshot fn imports) need the collection machinery itself extracted from server and are left for the issue's PR5 scope.
Ref rustfs/backlog#1834 (PR4).
Zhengchao An