diff --git a/API.md b/API.md
new file mode 100644
index 0000000..9fb8cc1
--- /dev/null
+++ b/API.md
@@ -0,0 +1,173 @@
+# Public API audit — pre-1.0
+
+This document is the authoritative public-API manifest for every
+crate promoted to 1.0 in this workspace. It is committed at the repo
+root (the canonical `docs/` folder is local-only per
+`.git/info/exclude`); when a crate is published to crates.io, the
+audit captured here is what its 1.0.0 promises.
+
+Generated: 2026-05-06.
+
+Closes the audit pass from #42. The companion 1.0 work lives in #43
+(MSRV policy) and #44 (coordinated release).
+
+## How to reproduce
+
+```bash
+cargo install cargo-public-api --locked
+cargo install cargo-semver-checks --locked
+
+for crate in itch-protocol itch-tcp itch-soup itch-mold; do
+    cargo public-api -p "$crate"     > "API-$crate.txt"
+    cargo semver-checks check-release -p "$crate"
+done
+```
+
+`cargo public-api` prints the full public surface for one crate;
+diff against this file across releases to catch unintended changes.
+`cargo semver-checks check-release` validates that no change since
+the last published version is breaking under SemVer.
+
+Both tools are wired into the `make pre-publish` target (see
+`Makefile`).
+
+## `#[non_exhaustive]` policy
+
+Applied to every error / event enum so future variants ship in a
+minor release without breaking downstream `match` arms.
+
+Concretely, all the following enums are `#[non_exhaustive]`:
+
+- `itch_protocol::ProtocolError`
+- `itch_protocol::primitives::TimestampError` (added 2026-05-06)
+- `itch_tcp::TransportError`
+- `itch_soup::SoupError`
+- `itch_soup::LoginRejectReason` (added 2026-05-06)
+- `itch_mold::MoldError`
+- `itch_mold::MoldEvent`
+- `itch_replay::ReplayError`
+- `itch_book::BookError`
+- `itch_source::SourceError`
+- `itch_source::impls::RingBufferSeqStoreError`
+- `itch_source_redis::RedisSeqStoreError`
+- `itch_source_postgres::PostgresSeqStoreError`
+- `itch_source_kafka::KafkaSourceError`
+
+NOT applied to closed-set ITCH 5.0 enums — exhaustive `match` is
+intentional for forward-incompatible protocol revisions:
+
+- `itch_protocol::Message` (the 20 ITCH 5.0 message kinds)
+- `itch_protocol::EventCode`
+- `itch_protocol::Side`
+- `itch_protocol::CrossType`
+- `itch_protocol::ImbalanceDirection`
+- `itch_protocol::MarketCategory`
+- `itch_protocol::FinancialStatus`
+- `itch_protocol::Authenticity`
+- `itch_protocol::YesNo`
+- `itch_protocol::LuldTier`
+- `itch_protocol::TradingState`
+- `itch_protocol::RegShoAction`
+- `itch_protocol::MarketMakerMode`
+- `itch_protocol::MarketParticipantState`
+- `itch_protocol::BreachedLevel`
+- `itch_protocol::IpoReleaseQualifier`
+- `itch_protocol::Printable`
+- `itch_protocol::PriceVariation`
+- `itch_protocol::RpiInterestFlag`
+
+A new ITCH revision lands as a new module (per ADR direction);
+`Message` itself stays exhaustive so the codec catches every
+new variant at compile time.
+
+`itch_soup::SoupPacket` is also exhaustive — it is the SoupBinTCP
+3.00 wire shape; new SoupBinTCP versions land as a separate
+module.
+
+`itch_replay::CaptureFormat` is exhaustive — application-level
+flag covering Glimpse vs RawBodies; users select one explicitly.
+
+## Per-crate public surface (summarised)
+
+The full output of `cargo public-api -p <crate>` is reproducible
+from a clean `cargo build`; this section names the headline shapes
+that downstream code is most likely to touch.
+
+### `itch-protocol`
+
+- 20 message DTOs (`SystemEvent`, `StockDirectory`, …,
+  `RetailPriceImprovement`) + `Message` enum + `Header`.
+- 18 closed-set ASCII enums in `enums` (see `#[non_exhaustive]`
+  policy above).
+- Primitive newtypes: `Stock`, `Mpid`, `Price4`, `Price8`,
+  `Timestamp`, `StockLocate`, `TrackingNumber`, `OrderReference`,
+  `MatchNumber`, `Shares`. Every newtype is
+  `#[repr(transparent)]` so future versions can rely on layout.
+- `Encode` / `Decode` traits + `Message::encode` / `decode` +
+  `ProtocolError`.
+
+### `itch-tcp`
+
+- `ItchCodec` (length-prefix Decoder / Encoder).
+- `ItchConnection` type alias.
+- `connect`, `bind`, `accept`.
+- `Server` (issue #18 onwards).
+- `TransportError` (`#[non_exhaustive]`).
+
+### `itch-soup`
+
+- `SoupConnection` + `login` / `login_with_timeout` +
+  `SoupCredentials`.
+- `ResilientSoupClient` + `ResilientSoupConfig`.
+- `SoupServer` + `Authenticator` trait + `AllowAllAuthenticator` /
+  `StaticAuthenticator`.
+- `HeartbeatConfig`, `OutboundHeartbeat`, `InboundHeartbeat`.
+- `SoupCodec` + `SoupPacket` (10 wire packet types).
+- `LoginRequest`, `LoginAccepted`, `LoginRejectReason`
+  (`#[non_exhaustive]`).
+- `SoupError` (`#[non_exhaustive]`).
+- `DEFAULT_LOGIN_TIMEOUT`, `DEFAULT_SEND_TIMEOUT`,
+  `DEFAULT_BACKOFF_MIN`, `DEFAULT_BACKOFF_MAX`,
+  `DEFAULT_RESILIENT_LOGIN_TIMEOUT`, `DEFAULT_BROADCAST_CAPACITY`,
+  `DEFAULT_SHUTDOWN_GRACE`, `DEFAULT_UNSEQUENCED_INBOX_CAPACITY`.
+
+### `itch-mold`
+
+- `MoldStream` + `MoldConfig` + `MoldEvent` (`#[non_exhaustive]`).
+- `MoldPublisher`, `MoldRequestServer`.
+- `MoldPacket` + `MoldPacketHeader` + `MessageBlock` (downstream
+  packet codec).
+- Constants: `HEADER_LEN`, `MSG_COUNT_HEARTBEAT`,
+  `MSG_COUNT_END_OF_SESSION`, `MAX_BLOCK_LEN`,
+  `DEFAULT_PACKING_MTU`, `BLOCK_LEN_PREFIX`.
+- `MoldError` (`#[non_exhaustive]`).
+- `PendingOverflowPolicy` (issue #22).
+
+## Doc coverage
+
+`cargo doc --workspace --no-deps` is required to be zero-warning
+under `RUSTDOCFLAGS=-D warnings` (CI gate). Every `pub` item
+carries a `///` doc comment; every fallible `pub fn` carries an
+`# Errors` section. The doc gate is enforced on every PR.
+
+## SemVer commitment (effective at 1.0.0)
+
+From the moment a crate ships its 1.0.0 release:
+
+- Adding a new `pub fn` / `pub const` / `pub struct` / `pub enum`
+  variant to a `#[non_exhaustive]` enum is **non-breaking**.
+- Renaming, removing, or changing the signature of any item in
+  this manifest is **breaking** (major bump).
+- Raising MSRV is **breaking-by-policy** (see `MSRV.md`) — a
+  one-minor-version deprecation window applies.
+- Changing wire format (`Message::encode` / `decode` byte shape)
+  is **breaking**.
+
+These rules are mechanically validated on every release PR by
+`cargo semver-checks check-release`.
+
+## References
+
+- ADR-0007 (independent crates).
+- `MSRV.md` (MSRV policy and current floors).
+- `CHANGELOG.md` per crate (per-release deltas).
diff --git a/Cargo.lock b/Cargo.lock
index 82818ca..55a3041 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1086,7 +1086,6 @@ dependencies = [
 name = "itch-source-kafka"
 version = "0.1.0"
 dependencies = [
- "async-trait",
  "futures",
  "itch-protocol",
  "itch-source",
diff --git a/Makefile b/Makefile
index 960fb4c..4091804 100644
--- a/Makefile
+++ b/Makefile
@@ -101,6 +101,35 @@ fuzz-list: ## List the configured fuzz targets
 
 pre-push: fix fmt lint-fix test doc ## Canonical pre-push gate
 
+# ---------- 1.0 release gates ----------
+
+# Promoted crates that ship a 1.0 release. Update this list when
+# adding or removing crates from the 1.0 promotion set (see #42).
+RELEASE_CRATES ?= itch-protocol itch-tcp itch-soup itch-mold
+
+public-api: ## Print the full public API of every promoted crate (requires `cargo install cargo-public-api`)
+	@for c in $(RELEASE_CRATES); do \
+		echo "==> $$c"; \
+		$(CARGO) public-api -p $$c || exit $$?; \
+	done
+
+semver-check: ## Validate no breaking change since the last published version of each promoted crate (requires `cargo install cargo-semver-checks`)
+	@for c in $(RELEASE_CRATES); do \
+		echo "==> $$c"; \
+		$(CARGO) semver-checks check-release -p $$c || exit $$?; \
+	done
+
+check-msrv: ## Build + test every promoted crate against the pinned MSRV (requires the MSRV toolchain installed via `rustup toolchain install`)
+	@MSRV=$$(grep -E '^rust-version' crates/itch-protocol/Cargo.toml | head -1 | sed -E 's/.*"([0-9.]+)".*/\1/'); \
+	if [ -z "$$MSRV" ]; then echo "could not detect MSRV from crates/itch-protocol/Cargo.toml"; exit 1; fi; \
+	echo "MSRV: $$MSRV"; \
+	for c in $(RELEASE_CRATES); do \
+		echo "==> $$c (build)"; $(CARGO) +$$MSRV build -p $$c || exit $$?; \
+		echo "==> $$c (test)";  $(CARGO) +$$MSRV test  -p $$c || exit $$?; \
+	done
+
+pre-publish: pre-push public-api semver-check check-msrv ## Full pre-publish gate (1.0 release-readiness)
+
 # ---------- workflow helpers ----------
 
 workflow-list: ## List GitHub Actions workflow runs
@@ -116,4 +145,5 @@ clean: ## Cargo clean
 
 .PHONY: help build release test run fmt fmt-check lint lint-fix check fix \
         doc coverage coverage-html bench bench-save bench-compare fuzz \
-        pre-push workflow-list workflow-view clean
+        pre-push public-api semver-check check-msrv pre-publish \
+        workflow-list workflow-view clean
diff --git a/crates/itch-client/src/main.rs b/crates/itch-client/src/main.rs
index 944aa80..7f95187 100644
--- a/crates/itch-client/src/main.rs
+++ b/crates/itch-client/src/main.rs
@@ -366,6 +366,10 @@ async fn run_soup(server: &str, username: &str, password: &str) -> ExitCode {
                         let detail = match reason {
                             LoginRejectReason::NotAuthorized => "not authorized",
                             LoginRejectReason::SessionUnavailable => "session unavailable",
+                            // `LoginRejectReason` is `#[non_exhaustive]` —
+                            // forward-compat arm for future SoupBinTCP
+                            // reject codes.
+                            _ => "unknown reject code",
                         };
                         error!(?reason, detail, "login rejected — terminal");
                         return ExitCode::from(6);
diff --git a/crates/itch-protocol/CHANGELOG.md b/crates/itch-protocol/CHANGELOG.md
index 9d797f8..22d35da 100644
--- a/crates/itch-protocol/CHANGELOG.md
+++ b/crates/itch-protocol/CHANGELOG.md
@@ -6,6 +6,15 @@ this project adheres to per-crate [SemVer](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
 
+### Changed
+
+- **API audit for 1.0** (#42). Added `#[non_exhaustive]` to
+  `primitives::TimestampError` so future stricter validation can
+  add reject reasons in a minor release without breaking
+  downstream `match` arms. Closed-set ITCH 5.0 enums (`Message`,
+  `EventCode`, `Side`, `CrossType`, …) deliberately stay
+  exhaustive — see the workspace `API.md` for the full policy.
+
 ### Added
 
 - **Property-based tests** (`tests/property.rs` + shared
diff --git a/crates/itch-protocol/src/primitives.rs b/crates/itch-protocol/src/primitives.rs
index 0a4618b..a43d6fa 100644
--- a/crates/itch-protocol/src/primitives.rs
+++ b/crates/itch-protocol/src/primitives.rs
@@ -146,6 +146,11 @@ impl Shares {
 pub struct Timestamp(u64);
 
 /// Reasons a `Timestamp::try_new` can reject the input.
+///
+/// `#[non_exhaustive]` is intentional: future ITCH revisions or
+/// stricter validation may add reject reasons; consumers must
+/// match with a fallback arm.
+#[non_exhaustive]
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash)]
 pub enum TimestampError {
     /// Value exceeds the u48 range `[0, 2^48 - 1]`.
diff --git a/crates/itch-soup/CHANGELOG.md b/crates/itch-soup/CHANGELOG.md
index 5f333ac..52867f9 100644
--- a/crates/itch-soup/CHANGELOG.md
+++ b/crates/itch-soup/CHANGELOG.md
@@ -6,6 +6,15 @@ this project adheres to per-crate [SemVer](https://semver.org/spec/v2.0.0.html).
 
 ## Unreleased
 
+### Changed
+
+- **API audit for 1.0** (#42). Added `#[non_exhaustive]` to
+  `LoginRejectReason` so NASDAQ's future SoupBinTCP reject codes
+  can ship in a minor release without breaking downstream `match`
+  arms. Updated `itch-client::run_soup` to add a fallback arm
+  ("unknown reject code"). See the workspace `API.md` for the
+  full enum-by-enum policy.
+
 ### Added
 
 - **Criterion bench `soup_codec`** (issue #31): per-packet
diff --git a/crates/itch-soup/src/lib.rs b/crates/itch-soup/src/lib.rs
index 5970439..fdbcadb 100644
--- a/crates/itch-soup/src/lib.rs
+++ b/crates/itch-soup/src/lib.rs
@@ -226,6 +226,11 @@ pub enum SoupError {
 }
 
 /// Codes carried by a Login Rejected (`J`) packet.
+///
+/// `#[non_exhaustive]` is intentional: NASDAQ may extend the
+/// SoupBinTCP reject codes in a future revision; consumers must
+/// match with a fallback arm to remain forward-compatible.
+#[non_exhaustive]
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub enum LoginRejectReason {
     /// `A` — Not Authorized: the username / password combination