diff --git a/AGENTS.md b/AGENTS.md
index 496242a9..e6b9f51d 100644
--- a/AGENTS.md
+++ b/AGENTS.md
@@ -138,6 +138,9 @@ Swarm-level:
   with **no identity** and a TLS failure that names no cause.
 - **`swarm-queue-client/`** — the one authenticated connect to the swarm
   NATS queue.
+- **`swarm-wire/`** — serde-only request and reply contracts services
+  exchange over the queue (builder, claude login), so naming one links
+  neither the queue client nor the store client.
 - **`swarm-nats-auth/`** — NATS auth-callout responder; without it the
   queue is fail-closed and admits nobody.
 - **`swarm-agent-verify/`** — checks a `swarm-agent.<agent>.<secret>`
diff --git a/Cargo.lock b/Cargo.lock
index 8ecce245..b6674478 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4811,6 +4811,7 @@ dependencies = [
  "serde_json",
  "swarm-queue-client",
  "swarm-secret-client",
+ "swarm-wire",
  "tokio",
  "tracing",
 ]
@@ -4846,6 +4847,7 @@ dependencies = [
  "serde_json",
  "swarm-queue-client",
  "swarm-secret-client",
+ "swarm-wire",
  "tokio",
  "tracing",
 ]
@@ -4889,6 +4891,7 @@ dependencies = [
  "swarm-matrix-client",
  "swarm-queue-client",
  "swarm-secret-client",
+ "swarm-wire",
  "tempfile",
  "tokio",
  "tower",
@@ -5010,6 +5013,7 @@ dependencies = [
  "swarm-agent-verify",
  "swarm-queue-client",
  "swarm-secret-client",
+ "swarm-wire",
  "tokio",
  "tracing",
  "tracing-subscriber",
@@ -5076,6 +5080,14 @@ dependencies = [
  "vaultrs",
 ]
 
+[[package]]
+name = "swarm-wire"
+version = "0.1.0"
+dependencies = [
+ "serde",
+ "serde_json",
+]
+
 [[package]]
 name = "swarmctl"
 version = "0.1.0"
diff --git a/Cargo.toml b/Cargo.toml
index ed69dd19..a1f718b8 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -43,6 +43,7 @@ members = [
   "swarm-logs-auth",
   "swarm-metrics-auth",
   "swarm-secret-client",
+  "swarm-wire",
   "swarmctl",
 ]
 
@@ -118,6 +119,7 @@ swarm-controller-api = { path = "swarm-controller-api" }
 swarm-matrix-client = { path = "swarm-matrix-client" }
 swarm-queue-client = { path = "swarm-queue-client" }
 swarm-secret-client = { path = "swarm-secret-client" }
+swarm-wire = { path = "swarm-wire" }
 thiserror = "2"
 vaultrs = "0.8"
 # vaultrs's transport crates. Direct dependencies because one endpoint is
diff --git a/swarm-builder/Cargo.toml b/swarm-builder/Cargo.toml
index 4275fee9..bbb5d424 100644
--- a/swarm-builder/Cargo.toml
+++ b/swarm-builder/Cargo.toml
@@ -15,10 +15,11 @@ async-nats.workspace = true
 futures-util.workspace = true
 hive-log.workspace = true
 serde_json.workspace = true
-# The build subject and the shapes the controller sends and reads back.
 swarm-queue-client.workspace = true
 # The forge token and queue client secret paths, and the store login.
 swarm-secret-client.workspace = true
+# The build subject and the shapes the controller sends and reads back.
+swarm-wire.workspace = true
 tokio.workspace = true
 tracing.workspace = true
 
diff --git a/swarm-builder/src/archetypes.rs b/swarm-builder/src/archetypes.rs
index 76222ade..cf35081f 100644
--- a/swarm-builder/src/archetypes.rs
+++ b/swarm-builder/src/archetypes.rs
@@ -9,7 +9,7 @@ use std::path::PathBuf;
 use std::process::Stdio;
 use std::time::Duration;
 
-use swarm_queue_client::builder::ArchetypesReply;
+use swarm_wire::builder::ArchetypesReply;
 
 /// What every evaluation is run with, fixed at start.
 pub struct Evaluator {
@@ -105,7 +105,7 @@ mod tests {
             nix: PathBuf::from("nix"),
             hyperhive: "/nix/store/h-source".to_owned(),
             nixpkgs: "/nix/store/n-source".to_owned(),
-            deadline: swarm_queue_client::builder::ARCHETYPES_DEADLINE,
+            deadline: swarm_wire::builder::ARCHETYPES_DEADLINE,
         }
     }
 
diff --git a/swarm-builder/src/main.rs b/swarm-builder/src/main.rs
index bf0cfe2b..5c835f37 100644
--- a/swarm-builder/src/main.rs
+++ b/swarm-builder/src/main.rs
@@ -1,11 +1,11 @@
 //! The swarm builder's build service.
 //!
 //! Connects to the swarm queue as its own OIDC client, takes build requests
-//! from swarm-controller on [`swarm_queue_client::builder::SUBJECT`], builds
+//! from swarm-controller on [`swarm_wire::builder::SUBJECT`], builds
 //! each agent config at its commit, answers on the request's reply subject,
 //! and logs one line per build. It writes nothing to the forge: the
 //! controller turns the reply into a commit status. It also answers
-//! [`swarm_queue_client::builder::ARCHETYPES_SUBJECT`] with the agent
+//! [`swarm_wire::builder::ARCHETYPES_SUBJECT`] with the agent
 //! archetypes its hyperhive source declares, which the controller stores.
 //!
 //! The store identity comes from the `BAO_*` environment. The queue client
@@ -19,13 +19,13 @@ use std::time::Duration;
 
 use anyhow::{Context, Result, anyhow, bail};
 use futures_util::StreamExt as _;
-use swarm_queue_client::builder::{
-    ARCHETYPES_DEADLINE, ARCHETYPES_SUBJECT, BUILD_DEADLINE, BuildAgent, QUEUE_GROUP,
-    REPLY_DEADLINE, Reply, SUBJECT,
-};
 use swarm_queue_client::{ClientSecret, QueueConfig};
 use swarm_secret_client::forge::Credential;
 use swarm_secret_client::stored_secret::StoredSecret;
+use swarm_wire::builder::{
+    ARCHETYPES_DEADLINE, ARCHETYPES_SUBJECT, BUILD_DEADLINE, BuildAgent, QUEUE_GROUP,
+    REPLY_DEADLINE, Reply, SUBJECT,
+};
 
 mod archetypes;
 mod nix_build;
@@ -168,10 +168,10 @@ async fn answer_evaluations(
         };
         let reply = evaluator.eval().await;
         match &reply {
-            swarm_queue_client::builder::ArchetypesReply::Evaluated { archetypes, .. } => {
+            swarm_wire::builder::ArchetypesReply::Evaluated { archetypes, .. } => {
                 tracing::info!(count = archetypes.len(), "archetypes evaluated");
             }
-            swarm_queue_client::builder::ArchetypesReply::Failed { error_tail } => {
+            swarm_wire::builder::ArchetypesReply::Failed { error_tail } => {
                 tracing::warn!(%error_tail, "archetype evaluation failed");
             }
         }
diff --git a/swarm-builder/src/nix_build.rs b/swarm-builder/src/nix_build.rs
index 099a28de..b6937378 100644
--- a/swarm-builder/src/nix_build.rs
+++ b/swarm-builder/src/nix_build.rs
@@ -16,7 +16,7 @@ use std::path::PathBuf;
 use std::process::Stdio;
 use std::time::Duration;
 
-use swarm_queue_client::builder::{BuildAgent, Reply};
+use swarm_wire::builder::{BuildAgent, Reply};
 use tokio::io::AsyncReadExt as _;
 
 /// The most of `nix`'s stderr a failed build's reply carries, from its end.
@@ -293,7 +293,7 @@ pub(crate) fn tail(stderr: &str, status: std::process::ExitStatus) -> String {
 #[cfg(test)]
 mod tests {
     use super::*;
-    use swarm_queue_client::builder::BUILD_DEADLINE;
+    use swarm_wire::builder::BUILD_DEADLINE;
 
     fn job() -> BuildAgent {
         BuildAgent {
diff --git a/swarm-claude-login/Cargo.toml b/swarm-claude-login/Cargo.toml
index 68238712..b1af0ca1 100644
--- a/swarm-claude-login/Cargo.toml
+++ b/swarm-claude-login/Cargo.toml
@@ -21,6 +21,8 @@ hive-types.workspace = true
 swarm-queue-client.workspace = true
 # The credentials and queue client secret paths, and the store login.
 swarm-secret-client.workspace = true
+# The login subject and the requests and replies it carries.
+swarm-wire.workspace = true
 tokio.workspace = true
 tracing.workspace = true
 
diff --git a/swarm-claude-login/src/login.rs b/swarm-claude-login/src/login.rs
index 17246354..1b504623 100644
--- a/swarm-claude-login/src/login.rs
+++ b/swarm-claude-login/src/login.rs
@@ -14,8 +14,8 @@ use std::process::Stdio;
 use std::sync::Arc;
 use std::time::Duration;
 
-use swarm_queue_client::claude_login::Reply;
 use swarm_secret_client::claude_login::Credentials;
+use swarm_wire::claude_login::Reply;
 use tokio::io::{AsyncBufReadExt as _, AsyncRead, AsyncWriteExt as _, BufReader};
 use tokio::process::{Child, ChildStdin, Command};
 use tokio::sync::{Mutex, watch};
diff --git a/swarm-claude-login/src/main.rs b/swarm-claude-login/src/main.rs
index 36bcdf3f..1efcf0b0 100644
--- a/swarm-claude-login/src/main.rs
+++ b/swarm-claude-login/src/main.rs
@@ -2,7 +2,7 @@
 //!
 //! Connects to the swarm queue as its own OIDC client, takes an operator's
 //! login steps from swarm-controller on
-//! [`swarm_queue_client::claude_login::SUBJECT`], runs `claude auth login`
+//! [`swarm_wire::claude_login::SUBJECT`], runs `claude auth login`
 //! for the agent named ([`login`]), and writes the credentials it produces to
 //! that agent's store leaf, a new version over any stored before. The agent's
 //! harness takes a version newer than the one it last installed.
@@ -16,10 +16,10 @@ use std::sync::Arc;
 
 use anyhow::{Context, Result, bail};
 use futures_util::StreamExt as _;
-use swarm_queue_client::claude_login::{Reply, Request, SESSION_DEADLINE, STEP_DEADLINE, SUBJECT};
 use swarm_queue_client::{ClientSecret, QueueConfig};
 use swarm_secret_client::claude_login::{Credentials, client_secret_path, credentials_path};
 use swarm_secret_client::stored_secret::StoredSecret;
+use swarm_wire::claude_login::{Reply, Request, SESSION_DEADLINE, STEP_DEADLINE, SUBJECT};
 
 mod login;
 
@@ -190,7 +190,7 @@ mod tests {
     use std::sync::Arc;
     use std::time::Duration;
 
-    use swarm_queue_client::claude_login::{Reply, Request};
+    use swarm_wire::claude_login::{Reply, Request};
 
     use super::{handle, login};
 
diff --git a/swarm-controller/Cargo.toml b/swarm-controller/Cargo.toml
index f1e40ade..14204773 100644
--- a/swarm-controller/Cargo.toml
+++ b/swarm-controller/Cargo.toml
@@ -118,6 +118,8 @@ swarm-queue-client = { workspace = true, features = [
 # name and the object's shape are agreements between the two ends, and a
 # second spelling here would be a store this hive could not read.
 swarm-secret-client.workspace = true
+# The builder and claude login subjects, requests and replies it sends.
+swarm-wire.workspace = true
 # The appservice calls `matrix_account::agent_token` mints agents' accounts
 # with — shared with `swarm-matrix-ctl`, which pins the same device id.
 swarm-matrix-client.workspace = true
diff --git a/swarm-controller/src/archetypes.rs b/swarm-controller/src/archetypes.rs
index 1507e57e..6c755a9f 100644
--- a/swarm-controller/src/archetypes.rs
+++ b/swarm-controller/src/archetypes.rs
@@ -16,7 +16,7 @@ use hive_sh4re::permissions::Permission;
 use problem_details::ProblemDetails;
 use serde::{Deserialize, Serialize};
 use swarm_queue_client::archetypes::{ArchetypeMeta, BUILTIN_SOURCE, SourceRecord};
-use swarm_queue_client::builder::{
+use swarm_wire::builder::{
     ARCHETYPES_DEADLINE, ARCHETYPES_SUBJECT, ArchetypesReply, EvalArchetypes,
 };
 use utoipa::ToSchema;
@@ -361,7 +361,7 @@ mod tests {
         let mut requests = builder
             .queue_subscribe(
                 ARCHETYPES_SUBJECT,
-                swarm_queue_client::builder::QUEUE_GROUP.to_owned(),
+                swarm_wire::builder::QUEUE_GROUP.to_owned(),
             )
             .await
             .expect("subscribe");
diff --git a/swarm-controller/src/builder.rs b/swarm-controller/src/builder.rs
index cef00653..88323bca 100644
--- a/swarm-controller/src/builder.rs
+++ b/swarm-controller/src/builder.rs
@@ -16,7 +16,7 @@ use std::future::Future;
 
 use forgejo_api::structs::CommitStatusState;
 use hive_jobq::scheduler::Outcome;
-use swarm_queue_client::builder::{BuildAgent, REPLY_DEADLINE, Reply, SUBJECT};
+use swarm_wire::builder::{BuildAgent, REPLY_DEADLINE, Reply, SUBJECT};
 
 use crate::agent_renewal::unix_now;
 use crate::forge::{self, CONFIG_ORG};
@@ -534,7 +534,7 @@ mod tests {
 
         let builder = nats.client().await;
         let mut requests = builder
-            .queue_subscribe(SUBJECT, swarm_queue_client::builder::QUEUE_GROUP.to_owned())
+            .queue_subscribe(SUBJECT, swarm_wire::builder::QUEUE_GROUP.to_owned())
             .await
             .expect("subscribe");
         // A message the builder sends itself and receives back proves the
diff --git a/swarm-controller/src/claude_login.rs b/swarm-controller/src/claude_login.rs
index 10425785..857a9c58 100644
--- a/swarm-controller/src/claude_login.rs
+++ b/swarm-controller/src/claude_login.rs
@@ -21,7 +21,7 @@ use axum::extract::{Path, State};
 use axum::http::{HeaderMap, StatusCode};
 use problem_details::ProblemDetails;
 use serde::{Deserialize, Serialize};
-use swarm_queue_client::claude_login::{REPLY_DEADLINE, Reply, Request, SUBJECT};
+use swarm_wire::claude_login::{REPLY_DEADLINE, Reply, Request, SUBJECT};
 use utoipa::ToSchema;
 
 use crate::{AppState, error_problem};
@@ -243,7 +243,7 @@ mod tests {
     use std::sync::Mutex;
 
     use axum::http::StatusCode;
-    use swarm_queue_client::claude_login::{Reply, Request};
+    use swarm_wire::claude_login::{Reply, Request};
 
     use super::{LoginSink, relay};
 
diff --git a/swarm-controller/src/main.rs b/swarm-controller/src/main.rs
index ce88efd3..ed5499a3 100644
--- a/swarm-controller/src/main.rs
+++ b/swarm-controller/src/main.rs
@@ -601,7 +601,7 @@ async fn build_agent(
     rev: String,
     pr: u64,
 ) -> hive_jobq::scheduler::Outcome {
-    let job = swarm_queue_client::builder::BuildAgent { agent, rev, pr };
+    let job = swarm_wire::builder::BuildAgent { agent, rev, pr };
     let builds = builder::runs::Builds::Live(deps.queue.clone());
     let link_base = std::env::var(PUBLIC_URL_ENV).ok();
     builder::run(
diff --git a/swarm-nats-auth/Cargo.toml b/swarm-nats-auth/Cargo.toml
index 7ba2da59..0bf8e78b 100644
--- a/swarm-nats-auth/Cargo.toml
+++ b/swarm-nats-auth/Cargo.toml
@@ -33,6 +33,8 @@ swarm-queue-client = { workspace = true, features = ["notices"] }
 # credentials `swarm-agent-verify` checks a presented token against.
 swarm-secret-client.workspace = true
 swarm-agent-verify.workspace = true
+# The builder and login subjects it grants.
+swarm-wire.workspace = true
 tokio.workspace = true
 tracing.workspace = true
 tracing-subscriber.workspace = true
diff --git a/swarm-nats-auth/src/policy.rs b/swarm-nats-auth/src/policy.rs
index c18b1153..088be44b 100644
--- a/swarm-nats-auth/src/policy.rs
+++ b/swarm-nats-auth/src/policy.rs
@@ -281,11 +281,11 @@ impl Policy {
         Permissions {
             publish: vec![Self::inbox(client_id)],
             subscribe: Some(vec![
-                swarm_queue_client::builder::SUBJECT.to_owned(),
-                swarm_queue_client::builder::ARCHETYPES_SUBJECT.to_owned(),
+                swarm_wire::builder::SUBJECT.to_owned(),
+                swarm_wire::builder::ARCHETYPES_SUBJECT.to_owned(),
                 Self::inbox(client_id),
             ]),
-            responses: Some(swarm_queue_client::builder::REPLY_DEADLINE),
+            responses: Some(swarm_wire::builder::REPLY_DEADLINE),
         }
     }
 
@@ -296,10 +296,10 @@ impl Policy {
         Permissions {
             publish: vec![Self::inbox(client_id)],
             subscribe: Some(vec![
-                swarm_queue_client::claude_login::SUBJECT.to_owned(),
+                swarm_wire::claude_login::SUBJECT.to_owned(),
                 Self::inbox(client_id),
             ]),
-            responses: Some(swarm_queue_client::claude_login::REPLY_DEADLINE),
+            responses: Some(swarm_wire::claude_login::REPLY_DEADLINE),
         }
     }
 
@@ -661,11 +661,11 @@ impl Policy {
             // back on this client's inbox, which it already subscribes to.
             swarm_queue_client::review_classifier::SUBJECT.to_owned(),
             // A build of an agent config, sent as a request the same way.
-            swarm_queue_client::builder::SUBJECT.to_owned(),
+            swarm_wire::builder::SUBJECT.to_owned(),
             // An archetype evaluation, sent as a request the same way.
-            swarm_queue_client::builder::ARCHETYPES_SUBJECT.to_owned(),
+            swarm_wire::builder::ARCHETYPES_SUBJECT.to_owned(),
             // An operator's claude login step, sent as a request the same way.
-            swarm_queue_client::claude_login::SUBJECT.to_owned(),
+            swarm_wire::claude_login::SUBJECT.to_owned(),
             // The wanted-state buckets — one per hive, all created and written
             // by this single client.
             //
@@ -1532,8 +1532,8 @@ mod tests {
 
     #[test]
     fn the_builder_hears_its_subject_and_inbox_only_and_answers_by_reply() {
-        use swarm_queue_client::builder::{ARCHETYPES_SUBJECT, REPLY_DEADLINE, SUBJECT};
         use swarm_queue_client::client_inbox_prefix;
+        use swarm_wire::builder::{ARCHETYPES_SUBJECT, REPLY_DEADLINE, SUBJECT};
 
         let p = policy()
             .with_builders(vec![BUILDER.to_owned()])
@@ -1562,7 +1562,7 @@ mod tests {
 
     #[test]
     fn only_the_reader_may_send_a_build() {
-        use swarm_queue_client::builder::{ARCHETYPES_SUBJECT, SUBJECT};
+        use swarm_wire::builder::{ARCHETYPES_SUBJECT, SUBJECT};
 
         let p = with_classifier().with_builders(vec![BUILDER.to_owned()]);
         let reader = p.permissions("swarm-controller").expect("the reader");
@@ -1589,8 +1589,8 @@ mod tests {
 
     #[test]
     fn the_claude_login_minter_hears_its_subject_and_inbox_only_and_answers_by_reply() {
-        use swarm_queue_client::claude_login::{REPLY_DEADLINE, SUBJECT};
         use swarm_queue_client::client_inbox_prefix;
+        use swarm_wire::claude_login::{REPLY_DEADLINE, SUBJECT};
 
         let p = policy()
             .with_claude_logins(vec![CLAUDE_LOGIN.to_owned()])
@@ -1602,7 +1602,7 @@ mod tests {
         for refused in [
             ">".to_owned(),
             "$SWARM.>".to_owned(),
-            swarm_queue_client::builder::SUBJECT.to_owned(),
+            swarm_wire::builder::SUBJECT.to_owned(),
             reply(&client_inbox_prefix("swarm-controller")),
         ] {
             assert!(
@@ -1618,7 +1618,7 @@ mod tests {
 
     #[test]
     fn only_the_reader_may_send_a_login_step() {
-        use swarm_queue_client::claude_login::SUBJECT;
+        use swarm_wire::claude_login::SUBJECT;
 
         let p = with_classifier()
             .with_builders(vec![BUILDER.to_owned()])
diff --git a/swarm-queue-client/src/archetypes.rs b/swarm-queue-client/src/archetypes.rs
index 519a9a4e..e99984a5 100644
--- a/swarm-queue-client/src/archetypes.rs
+++ b/swarm-queue-client/src/archetypes.rs
@@ -4,7 +4,7 @@
 //!
 //! **swarm-controller is the only writer and the only reader.** The swarm
 //! builder evaluates the source and answers on
-//! [`crate::builder::ARCHETYPES_SUBJECT`]; the controller checks each
+//! `swarm_wire::builder::ARCHETYPES_SUBJECT`; the controller checks each
 //! archetype's settings the way `POST /api/agents` checks them and writes the
 //! result here, so the create screen lists archetypes from a value that a
 //! create would accept.
diff --git a/swarm-queue-client/src/lib.rs b/swarm-queue-client/src/lib.rs
index ee0ef4ea..534e933e 100644
--- a/swarm-queue-client/src/lib.rs
+++ b/swarm-queue-client/src/lib.rs
@@ -494,13 +494,6 @@ pub mod review_classifier;
 mod startup_read;
 pub use startup_read::read_with_startup_retry;
 
-/// The builder's build subject and the request and reply it carries.
-pub mod builder;
-
-/// The claude login minter's subject and the requests and replies it
-/// carries.
-pub mod claude_login;
-
 /// Only the fields this needs; authelia returns several.
 #[derive(serde::Deserialize)]
 struct TokenResponse {
diff --git a/swarm-wire/Cargo.toml b/swarm-wire/Cargo.toml
new file mode 100644
index 00000000..ee968020
--- /dev/null
+++ b/swarm-wire/Cargo.toml
@@ -0,0 +1,11 @@
+[package]
+name = "swarm-wire"
+version.workspace = true
+edition.workspace = true
+
+[dependencies]
+serde.workspace = true
+serde_json.workspace = true
+
+[lints]
+workspace = true
diff --git a/swarm-queue-client/src/builder.rs b/swarm-wire/src/builder.rs
similarity index 56%
rename from swarm-queue-client/src/builder.rs
rename to swarm-wire/src/builder.rs
index 9ba1e6bd..aeb66f54 100644
--- a/swarm-queue-client/src/builder.rs
+++ b/swarm-wire/src/builder.rs
@@ -82,40 +82,97 @@ pub enum ArchetypesReply {
 
 #[cfg(test)]
 mod tests {
+    use serde_json::json;
+
     use super::*;
 
     #[test]
-    fn the_wire_tags_the_reply_by_state() {
-        let json = serde_json::to_value(Reply::Built {
-            out_path: "/nix/store/x".to_owned(),
-        })
-        .expect("encodes");
-        assert_eq!(json["state"], "built");
-        assert_eq!(json["out_path"], "/nix/store/x");
-        let json = serde_json::to_value(Reply::Failed {
-            error_tail: "e".to_owned(),
-        })
-        .expect("encodes");
-        assert_eq!(json["state"], "failed");
+    fn the_build_request_serializes_as_pinned() {
+        let req = BuildAgent {
+            agent: "atlas".to_owned(),
+            rev: "abc".to_owned(),
+            pr: 7,
+        };
+        let value = serde_json::to_value(&req).expect("encodes");
+        assert_eq!(value, json!({"agent": "atlas", "rev": "abc", "pr": 7}));
+        assert_eq!(
+            serde_json::from_value::<BuildAgent>(value).expect("decodes"),
+            req
+        );
+    }
+
+    #[test]
+    fn the_reply_serializes_as_pinned() {
+        for (reply, wire) in [
+            (
+                Reply::Built {
+                    out_path: "/nix/store/x".to_owned(),
+                },
+                json!({"state": "built", "out_path": "/nix/store/x"}),
+            ),
+            (
+                Reply::Failed {
+                    error_tail: "e".to_owned(),
+                },
+                json!({"state": "failed", "error_tail": "e"}),
+            ),
+        ] {
+            assert_eq!(serde_json::to_value(&reply).expect("encodes"), wire);
+            assert_eq!(
+                serde_json::from_value::<Reply>(wire).expect("decodes"),
+                reply
+            );
+        }
+    }
+
+    #[test]
+    fn the_archetypes_request_and_reply_serialize_as_pinned() {
+        let req = EvalArchetypes::default();
+        let value = serde_json::to_value(&req).expect("encodes");
+        assert_eq!(value, json!({}));
+        assert_eq!(
+            serde_json::from_value::<EvalArchetypes>(value).expect("decodes"),
+            req
+        );
+
+        let mut archetypes = serde_json::Map::new();
+        archetypes.insert("coder".to_owned(), json!({"description": "d"}));
+        for (reply, wire) in [
+            (
+                ArchetypesReply::Evaluated {
+                    source: "/nix/store/h".to_owned(),
+                    archetypes,
+                },
+                json!({
+                    "state": "evaluated",
+                    "source": "/nix/store/h",
+                    "archetypes": {"coder": {"description": "d"}},
+                }),
+            ),
+            (
+                ArchetypesReply::Failed {
+                    error_tail: "e".to_owned(),
+                },
+                json!({"state": "failed", "error_tail": "e"}),
+            ),
+        ] {
+            assert_eq!(serde_json::to_value(&reply).expect("encodes"), wire);
+            assert_eq!(
+                serde_json::from_value::<ArchetypesReply>(wire).expect("decodes"),
+                reply
+            );
+        }
+    }
+
+    #[test]
+    fn the_subjects_are_pinned() {
+        assert_eq!(SUBJECT, "$SWARM.builder.build");
+        assert_eq!(ARCHETYPES_SUBJECT, "$SWARM.builder.archetypes");
+        assert_eq!(QUEUE_GROUP, "builder");
     }
 
     #[test]
     fn the_reply_deadline_outlasts_the_build() {
         assert!(REPLY_DEADLINE > BUILD_DEADLINE);
     }
-
-    #[test]
-    fn the_archetypes_reply_is_tagged_by_state() {
-        let json = serde_json::to_value(ArchetypesReply::Evaluated {
-            source: "/nix/store/h".to_owned(),
-            archetypes: serde_json::Map::new(),
-        })
-        .expect("encodes");
-        assert_eq!(json["state"], "evaluated");
-        let json = serde_json::to_value(ArchetypesReply::Failed {
-            error_tail: "e".to_owned(),
-        })
-        .expect("encodes");
-        assert_eq!(json["state"], "failed");
-    }
 }
diff --git a/swarm-queue-client/src/claude_login.rs b/swarm-wire/src/claude_login.rs
similarity index 61%
rename from swarm-queue-client/src/claude_login.rs
rename to swarm-wire/src/claude_login.rs
index d1242cec..d541bea2 100644
--- a/swarm-queue-client/src/claude_login.rs
+++ b/swarm-wire/src/claude_login.rs
@@ -71,19 +71,68 @@ pub enum Reply {
 
 #[cfg(test)]
 mod tests {
+    use serde_json::json;
+
     use super::*;
 
     #[test]
-    fn the_wire_tags_the_request_by_step_and_the_reply_by_state() {
-        let json = serde_json::to_value(Request::Code {
-            agent: "atlas".to_owned(),
-            code: "c".to_owned(),
-        })
-        .expect("encodes");
-        assert_eq!(json["step"], "code");
-        assert_eq!(json["agent"], "atlas");
-        let json = serde_json::to_value(Reply::Stored).expect("encodes");
-        assert_eq!(json["state"], "stored");
+    fn the_request_serializes_as_pinned() {
+        for (req, wire) in [
+            (
+                Request::Start {
+                    agent: "atlas".to_owned(),
+                    operator: "mara".to_owned(),
+                },
+                json!({"step": "start", "agent": "atlas", "operator": "mara"}),
+            ),
+            (
+                Request::Code {
+                    agent: "atlas".to_owned(),
+                    code: "c".to_owned(),
+                },
+                json!({"step": "code", "agent": "atlas", "code": "c"}),
+            ),
+            (
+                Request::Cancel {
+                    agent: "atlas".to_owned(),
+                },
+                json!({"step": "cancel", "agent": "atlas"}),
+            ),
+        ] {
+            assert_eq!(serde_json::to_value(&req).expect("encodes"), wire);
+            assert!(serde_json::from_value::<Request>(wire).expect("decodes") == req);
+        }
+    }
+
+    #[test]
+    fn the_reply_serializes_as_pinned() {
+        for (reply, wire) in [
+            (
+                Reply::Started {
+                    url: "https://u".to_owned(),
+                },
+                json!({"state": "started", "url": "https://u"}),
+            ),
+            (Reply::Stored, json!({"state": "stored"})),
+            (Reply::Cancelled, json!({"state": "cancelled"})),
+            (
+                Reply::Failed {
+                    error: "e".to_owned(),
+                },
+                json!({"state": "failed", "error": "e"}),
+            ),
+        ] {
+            assert_eq!(serde_json::to_value(&reply).expect("encodes"), wire);
+            assert_eq!(
+                serde_json::from_value::<Reply>(wire).expect("decodes"),
+                reply
+            );
+        }
+    }
+
+    #[test]
+    fn the_subject_is_pinned() {
+        assert_eq!(SUBJECT, "$SWARM.claude-login.request");
     }
 
     #[test]
diff --git a/swarm-wire/src/lib.rs b/swarm-wire/src/lib.rs
new file mode 100644
index 00000000..10c4c562
--- /dev/null
+++ b/swarm-wire/src/lib.rs
@@ -0,0 +1,9 @@
+//! The request and reply shapes swarm services exchange over the queue: the
+//! subjects, their deadlines and the serde types that travel each way.
+//!
+//! Serde only, with no queue client and no secret-store client. A crate that
+//! names a contract (the sender, the answerer, the auth-callout responder that
+//! grants the subject) depends on this one without linking either.
+
+pub mod builder;
+pub mod claude_login;