replayer: add bounded Rust dry-run foundation

.github/workflows/rust.yml

@@ -32,6 +32,7 @@ on:
       - "scripts/generate-control-proto.sh"
       - "tests/controlplane/**"
       - "tests/dataplane/capture-format/**"
+      - "tests/replayer/**"
   push:
     branches:
       - main
@@ -56,6 +57,7 @@ on:
       - "scripts/generate-control-proto.sh"
       - "tests/controlplane/**"
       - "tests/dataplane/capture-format/**"
+      - "tests/replayer/**"
   # The control-plane evidence jobs below do not run on pull requests. They
   # re-prove live etcd / Go-oracle behaviour that a pull request rarely
   # changes, and re-running them on every push to a branch was the bulk of
@@ -131,6 +133,8 @@ jobs:
         run: make rust-lint
       - name: Run unit tests
         run: make rust-test
+      - name: Compare Go and Rust replay decoders and kill a mutation
+        run: make replayer-differential-evidence
       - name: Run doc tests
         run: make rust-doc-test
       - name: Reject a stale lockfile

AGENTS.md

@@ -78,6 +78,7 @@ When adding or modifying features, prefer extending existing packages before cre
 - `pkg/util/` - Utilities, including buffered IO, etcd wrapper, HTTP wrapper, simple MySQL lexer, and others.
 - `rust/crates/mysql-wire/` - MySQL wire-format types and codec boundaries; it does not own sockets or routing decisions.
 - `rust/crates/proxy-io/` - Client/backend transport ownership, including future TLS, compression, and PROXY protocol support.
+- `rust/crates/replayer-core/` - Bounded offline traffic replay primitives: input storage, native/audit decoding, deterministic ordering, filtering, and local checkpoints; it has no control-plane or SQL-serving dependency.
 - `rust/crates/session-core/` - Protocol-independent session lifecycle and migration state.
 - `rust/crates/control-router/` - Staged namespace-scoped routing selection, exact config/topology/health capture, and reservation accounting. Production dataplane/binary wiring remains prohibited until full routing parity is complete.
 - `rust/crates/control-routing/` - Protocol-independent route values, pure group matching/port-conflict primitives, and Go-compatible time arithmetic; it owns no reservation or production selector yet and carries no wire payloads.
@@ -94,6 +95,7 @@ When adding or modifying features, prefer extending existing packages before cre
 - `rust/crates/dataplane/` - Rust dataplane orchestration across wire, transport, session, and control components.
 - `rust/crates/differential-runner/` - Payload-free Rust consumer for the immutable Go protocol corpus; it drives merged wire/session parsers and emits sharded semantic observations.
 - `rust/crates/tiproxy-rs/` - Rust dataplane executable and build/version metadata.
+- `rust/crates/tiproxy-replayer/` - Standalone Rust offline traffic replayer composition root; replay payloads never enter the SQL-serving process or control bridge.
 - `tests/compatibility/` - Versioned client-driver and MySQL capability contract shared by the Go/Rust dataplane integration tests.
 - `tests/controlplane/cproute/api-differential/` - One test-only external router API input/output runner and its frozen acceptance/retirement inventories; synthetic adapter smoke does not qualify recorded-trace acceptance. Its `metrics/` package shares value-only query packets and decoding between recording and API replay; it owns no factor state. Its `clock/` package supplies the shared public event clock to test-build overlays only.
 - `tests/controlplane/` - Versioned Go control-plane contract and fault catalogs plus the payload-free observation comparator used by every Rust control-plane migration slice.

Makefile

@@ -43,7 +43,7 @@ CARGO_DENY_VERSION := 0.20.2
 RUST_TOOL_ROOT ?= $(GOBIN)/rust-tools
 RUST_TOOL_BIN := $(RUST_TOOL_ROOT)/bin
 
-.PHONY: cmd_% test lint parity-drift parity-drift-weekly docker docker-release golangci-lint gocovmerge clean rust-build rust-test rust-doc-test rust-lint rust-release rust-install-tools rust-supply-chain rust-negative-tests control-proto-generate control-proto-generate-check controlplane-contracts controlplane-differential controlplane-differential-self-test controlplane-cp001-evidence controlplane-cplog-evidence controlplane-cpadmin-evidence controlplane-cpdiag-evidence controlplane-cpctl-evidence controlplane-cpmeter-evidence controlplane-cp002-evidence controlplane-cp003-evidence controlplane-cp003-authority-evidence controlplane-cp004-evidence controlplane-cproute-evidence controlplane-cpmetrics-evidence controlplane-cpmetrics-applied-evidence controlplane-cpmetrics-collector-evidence controlplane-cpmetrics-factor-evidence controlplane-cproute-resource-evidence controlplane-cproute-migration-evidence controlplane-cproute-balance-evidence controlplane-cproute-worker-evidence controlplane-cproute-shadow-evidence controlplane-cproute-recorder-evidence controlplane-cproute-read-foundation-evidence controlplane-cproute-time-evidence controlplane-cproute-native-evidence controlplane-cptopo-evidence dataplane-differential dataplane-differential-coverage dataplane-differential-mutation dataplane-integration dataplane-t2-integration dataplane-t3-integration dataplane-t4-integration dataplane-t4-qualification dataplane-integration-go dataplane-integration-self-test
+.PHONY: cmd_% test lint parity-drift parity-drift-weekly docker docker-release golangci-lint gocovmerge clean rust-build rust-test rust-doc-test rust-lint rust-release rust-install-tools rust-supply-chain rust-negative-tests control-proto-generate control-proto-generate-check controlplane-contracts controlplane-differential controlplane-differential-self-test controlplane-cp001-evidence controlplane-cplog-evidence controlplane-cpadmin-evidence controlplane-cpdiag-evidence controlplane-cpctl-evidence controlplane-cpmeter-evidence controlplane-cp002-evidence controlplane-cp003-evidence controlplane-cp003-authority-evidence controlplane-cp004-evidence controlplane-cproute-evidence controlplane-cpmetrics-evidence controlplane-cpmetrics-applied-evidence controlplane-cpmetrics-collector-evidence controlplane-cpmetrics-factor-evidence controlplane-cproute-resource-evidence controlplane-cproute-migration-evidence controlplane-cproute-balance-evidence controlplane-cproute-worker-evidence controlplane-cproute-shadow-evidence controlplane-cproute-recorder-evidence controlplane-cproute-read-foundation-evidence controlplane-cproute-time-evidence controlplane-cproute-native-evidence controlplane-cptopo-evidence replayer-differential-evidence dataplane-differential dataplane-differential-coverage dataplane-differential-mutation dataplane-integration dataplane-t2-integration dataplane-t3-integration dataplane-t4-integration dataplane-t4-qualification dataplane-integration-go dataplane-integration-self-test
 
 default: cmd
 
@@ -209,6 +209,9 @@ controlplane-cproute-migration-evidence:
 controlplane-cptopo-evidence:
 	$(RUST_BUILD_ENV) tests/controlplane/cptopo/run.sh
 
+replayer-differential-evidence:
+	$(RUST_BUILD_ENV) tests/replayer/differential/run.sh
+
 DIFFERENTIAL_SHARD_INDEX ?= 0
 DIFFERENTIAL_SHARD_COUNT ?= 4