move agent_token from swarm-queue-client to swarm-agent-verify

per #5471, verifiers stop depending on the queue client. the module is
store-free and needs only thiserror, so swarm-agent-verify gains one
dependency and loses its swarm-queue-client edge. consumers import it
from swarm_agent_verify; swarm-logs and swarm-metrics, whose only use of
swarm-queue-client was this module, drop that dependency, as does
swarm-logs-auth.

Cargo.lock

@@ -1689,6 +1689,7 @@ dependencies = [
  "serde",
  "serde_json",
  "sha1",
+ "swarm-agent-verify",
  "swarm-queue-client",
  "swarm-secret-client",
  "tempfile",
@@ -2056,6 +2057,7 @@ dependencies = [
  "schemars",
  "serde",
  "serde_json",
+ "swarm-agent-verify",
  "swarm-queue-client",
  "swarm-secret-client",
  "tokio",
@@ -4769,8 +4771,8 @@ version = "0.1.0"
 dependencies = [
  "anyhow",
  "subtle",
- "swarm-queue-client",
  "swarm-secret-client",
+ "thiserror 2.0.18",
  "tokio",
  "tracing",
 ]
@@ -4923,7 +4925,7 @@ dependencies = [
  "clap-markdown",
  "reqwest",
  "serde_json",
- "swarm-queue-client",
+ "swarm-agent-verify",
  "swarm-secret-client",
  "tokio",
 ]
@@ -4937,7 +4939,6 @@ dependencies = [
  "clap",
  "sha2 0.11.0",
  "swarm-agent-verify",
- "swarm-queue-client",
  "swarm-secret-client",
  "tokio",
  "tracing",
@@ -4976,7 +4977,7 @@ dependencies = [
  "clap",
  "clap-markdown",
  "reqwest",
- "swarm-queue-client",
+ "swarm-agent-verify",
  "swarm-secret-client",
  "tokio",
 ]

hive-agent/Cargo.toml

@@ -52,6 +52,8 @@ swarm-queue-client = { workspace = true, features = [
   "agents-md-initial",
   "operator-profiles",
 ] }
+# The spelling of the token the queue connection presents.
+swarm-agent-verify.workspace = true
 # This agent's own queue secret, read from the store under its own certificate.
 swarm-secret-client.workspace = true
 # The directory an AGENTS.md edit is applied in, and the file it is written

hive-agent/src/swarm_queue.rs

@@ -386,7 +386,7 @@ async fn connect_as_agent<S: SecretSource>(
         // `Sync` as async-nats's auth callback requires; the store read is not.
         let attempt = tokio::spawn(async move {
             let value = secret.for_attempt().await.map_err(|e| format!("{e:#}"))?;
-            swarm_queue_client::agent_token::format_agent_token(&name, &value)
+            swarm_agent_verify::agent_token::format_agent_token(&name, &value)
                 .map_err(|e| e.to_string())
         });
         async move { attempt.await.map_err(|e| e.to_string())? }

hive-subagent-mcp/Cargo.toml

@@ -34,6 +34,8 @@ swarm-queue-client = { workspace = true, features = [
   "agent-inference",
   "agent-permissions",
 ] }
+# The spelling of the token the queue connection presents.
+swarm-agent-verify.workspace = true
 # The agent's own queue credential, read under its store identity.
 swarm-secret-client.workspace = true
 tokio.workspace = true

hive-subagent-mcp/src/swarm_term.rs

@@ -237,7 +237,7 @@ pub(crate) async fn connect(target: &Arc<Target>) -> anyhow::Result<async_nats::
         // `Sync` as async-nats's auth callback requires; the store read is not.
         let attempt = tokio::spawn(async move {
             let value = target.store.read().await.map_err(|e| format!("{e:#}"))?;
-            swarm_queue_client::agent_token::format_agent_token(&target.agent, &value)
+            swarm_agent_verify::agent_token::format_agent_token(&target.agent, &value)
                 .map_err(|e| e.to_string())
         });
         async move { attempt.await.map_err(|e| e.to_string())? }

swarm-agent-verify/Cargo.toml

@@ -7,10 +7,9 @@ edition.workspace = true
 anyhow.workspace = true
 # Comparing an agent's presented secret with the stored one.
 subtle.workspace = true
-# The agent-token spelling the agent also uses.
-swarm-queue-client.workspace = true
 # The read of the stored credential the token is checked against.
 swarm-secret-client.workspace = true
+thiserror.workspace = true
 tokio.workspace = true
 tracing.workspace = true
 

swarm-agent-verify/src/agent_token.rs

@@ -0,0 +1,153 @@
+//! The one spelling of the token an agent presents its own queue secret in,
+//! shared by the agent that formats it and the verifiers that parse it back:
+//! [`AGENT_TOKEN_PREFIX`], the agent's name, `.`, the secret.
+//!
+//! The secret itself lives at `swarm/agents/<agent>/queue` in the swarm's
+//! secret store (`swarm_secret_client::queue`). This module knows nothing of
+//! the store.
+
+/// Marks an `auth_token` as an agent's own credential.
+///
+/// An OIDC access token may itself contain `.`, so the `<agent>.<secret>`
+/// shape alone does not tell the two apart. Authelia's access tokens start
+/// `authelia_at_`.
+pub const AGENT_TOKEN_PREFIX: &str = "swarm-agent.";
+
+/// An agent's own credential as presented at the queue.
+///
+/// No `Debug`: `secret` is the credential itself.
+pub struct AgentToken<'a> {
+    /// The agent the presenter claims to be. Unproven until `secret` is
+    /// checked against that agent's stored credential.
+    pub agent: &'a str,
+    /// The presented secret.
+    pub secret: &'a str,
+}
+
+/// A token that is not `<agent>.<secret>` after its prefix, or parts that
+/// would not make one. Carries the reason only: a token holds a secret.
+#[derive(Debug, thiserror::Error)]
+#[error("malformed agent token: {0}")]
+pub struct Malformed(pub &'static str);
+
+/// Spell `agent`'s credential as the token it presents at the queue.
+///
+/// # Errors
+/// [`Malformed`] when `agent` or `secret` is empty or holds anything outside
+/// `[A-Za-z0-9_-]`. Either would make [`parse_agent_token`] split the token
+/// differently than it was joined.
+pub fn format_agent_token(agent: &str, secret: &str) -> Result<String, Malformed> {
+    check_agent(agent)?;
+    check_secret(secret)?;
+    Ok(format!("{AGENT_TOKEN_PREFIX}{agent}.{secret}"))
+}
+
+/// Read a presented token back into an [`AgentToken`].
+///
+/// `None` when `token` does not start with [`AGENT_TOKEN_PREFIX`]: it is some
+/// other kind of token, not a malformed one of these. `Some(Err(_))` when it
+/// does and is not exactly `<agent>.<secret>` after it.
+#[must_use]
+pub fn parse_agent_token(token: &str) -> Option<Result<AgentToken<'_>, Malformed>> {
+    let rest = token.strip_prefix(AGENT_TOKEN_PREFIX)?;
+    Some(
+        rest.split_once('.')
+            .ok_or(Malformed("no `.` between the agent and the secret"))
+            .and_then(|(agent, secret)| {
+                check_agent(agent)?;
+                check_secret(secret)?;
+                Ok(AgentToken { agent, secret })
+            }),
+    )
+}
+
+fn is_segment(s: &str) -> bool {
+    !s.is_empty()
+        && s.bytes()
+            .all(|b| b.is_ascii_alphanumeric() || b == b'-' || b == b'_')
+}
+
+/// The alphabet a store path segment allows, so the name cannot widen a
+/// subject with `.`, `*` or `>`, or address another agent's path.
+fn check_agent(agent: &str) -> Result<(), Malformed> {
+    if is_segment(agent) {
+        Ok(())
+    } else {
+        Err(Malformed("the agent is not a single [A-Za-z0-9_-] segment"))
+    }
+}
+
+/// The alphabet the controller mints secrets in, base64url without padding.
+/// The error never carries the value.
+fn check_secret(secret: &str) -> Result<(), Malformed> {
+    if is_segment(secret) {
+        Ok(())
+    } else {
+        Err(Malformed(
+            "the secret is empty or holds a byte outside [A-Za-z0-9_-]",
+        ))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn an_agent_token_round_trips() {
+        let token = format_agent_token("atlas", "Ab9_-z").expect("legal");
+        assert_eq!(token, "swarm-agent.atlas.Ab9_-z");
+        let parsed = parse_agent_token(&token)
+            .expect("carries the prefix")
+            .expect("well-formed");
+        assert_eq!(parsed.agent, "atlas");
+        assert_eq!(parsed.secret, "Ab9_-z");
+    }
+
+    /// Anything without the prefix belongs to the OIDC path, including a
+    /// token that happens to look like `<agent>.<secret>`.
+    #[test]
+    fn a_token_without_the_prefix_is_not_an_agent_token() {
+        for token in ["authelia_at_abc.def", "atlas.s3cr3t", "", "swarm-agent"] {
+            assert!(parse_agent_token(token).is_none(), "{token:?}");
+        }
+    }
+
+    #[test]
+    fn a_malformed_agent_token_is_refused() {
+        for token in [
+            "swarm-agent.",
+            "swarm-agent.atlas",
+            "swarm-agent.atlas.",
+            "swarm-agent..s3cr3t",
+            "swarm-agent.atlas.s3.cr3t",
+            "swarm-agent.at*las.s3cr3t",
+            "swarm-agent.at>las.s3cr3t",
+            "swarm-agent.at/las.s3cr3t",
+            "swarm-agent.atlas.s3cr3t=",
+            "swarm-agent.atlas.s3 cr3t",
+        ] {
+            assert!(
+                matches!(parse_agent_token(token), Some(Err(_))),
+                "{token:?} must be refused"
+            );
+        }
+    }
+
+    /// What formats always parses back into the same two parts.
+    #[test]
+    fn formatting_refuses_what_parsing_would_split_differently() {
+        assert!(format_agent_token("at.las", "s3cr3t").is_err());
+        assert!(format_agent_token("atlas", "s3.cr3t").is_err());
+        assert!(format_agent_token("atlas", "").is_err());
+        assert!(format_agent_token("", "s3cr3t").is_err());
+    }
+
+    #[test]
+    fn a_malformed_secret_is_not_echoed_in_the_error() {
+        let Some(Err(e)) = parse_agent_token("swarm-agent.atlas.hunter2!") else {
+            panic!("must be refused");
+        };
+        assert!(!e.to_string().contains("hunter2"), "{e}");
+    }
+}

swarm-agent-verify/src/lib.rs

@@ -1,22 +1,27 @@
 //! Checking an agent's own credential against the swarm secret store.
 //!
-//! The token is `swarm_queue_client::agent_token`'s spelling: a prefix, the
+//! The token is [`agent_token`]'s spelling: a prefix, the
 //! agent's name, and its secret. The name is only a claim. It becomes an
 //! identity when the secret equals the one stored at
 //! `swarm/agents/<agent>/queue`, and [`verify`] grants nothing on the name
 //! alone: every path that does not reach that comparison, and every lookup
 //! that fails, is a denial.
 //!
+//! [`agent_token`] also holds the spelling the agents, `swarm-logs` and
+//! `swarm-metrics` format their token in.
+//!
 //! Two verifiers use this: the queue's auth callout (`swarm-nats-auth`) and
 //! the log store's `auth_request` responder (`swarm-logs-auth`). Each reads
 //! the store under its own certificate.
 
+pub mod agent_token;
+
 use std::future::Future;
 use std::time::Duration;
 
+use crate::agent_token::AgentToken;
 use anyhow::Context;
 use subtle::ConstantTimeEq;
-use swarm_queue_client::agent_token::AgentToken;
 use swarm_secret_client::client::{DEFAULT_CERT_MOUNT, Settings};
 use swarm_secret_client::queue::{self, AgentCredential};
 
@@ -118,7 +123,7 @@ pub async fn verify(
 #[cfg(test)]
 mod tests {
     use super::*;
-    use swarm_queue_client::agent_token::parse_agent_token;
+    use crate::agent_token::parse_agent_token;
 
     /// A store holding at most one credential, or failing outright.
     enum Fake {

swarm-logs-auth/Cargo.toml

@@ -14,8 +14,6 @@ clap.workspace = true
 # The verdict cache's key: a digest of the bearer, never the bearer.
 sha2.workspace = true
 swarm-agent-verify.workspace = true
-# The agent-token spelling.
-swarm-queue-client.workspace = true
 swarm-secret-client.workspace = true
 tokio.workspace = true
 tracing.workspace = true

swarm-logs-auth/src/main.rs

@@ -28,7 +28,7 @@ use axum::extract::State;
 use axum::http::{HeaderMap, StatusCode, header};
 use clap::Parser;
 use swarm_agent_verify::CredentialSource;
-use swarm_queue_client::agent_token::parse_agent_token;
+use swarm_agent_verify::agent_token::parse_agent_token;
 use verdicts::Verdicts;
 
 /// How long one store lookup may take before the request is denied. Well

swarm-logs/Cargo.toml

@@ -13,7 +13,7 @@ anyhow.workspace = true
 clap.workspace = true
 clap-markdown = "0.1"
 # The agent-token spelling the gateway's responder parses.
-swarm-queue-client.workspace = true
+swarm-agent-verify.workspace = true
 # The read of this agent's own queue secret.
 swarm-secret-client.workspace = true
 # Only to drive that one async read; the query itself is blocking.

swarm-logs/README.md

@@ -25,7 +25,7 @@ As the agent itself. On each query it reads the agent's own queue secret,
 store certificate (`nix/agent-modules/bao.nix`), the same read `hive-agent`
 makes for its queue connection. It sends the secret as
 `Authorization: Bearer swarm-agent.<agent>.<secret>`, spelled by
-`swarm_queue_client::agent_token`.
+`swarm_agent_verify::agent_token`.
 
 At the gateway, nginx hands a bearer of that shape to `swarm-logs-auth`, which
 compares it with the stored secret (`swarm-agent-verify`, the check the queue's

swarm-logs/src/auth.rs

@@ -5,7 +5,7 @@
 //! The read is `hive-agent`'s `swarm_queue` one: the same variables, the same
 //! path (`swarm/agents/<agent>/queue`) and the same cert-auth role. The secret
 //! goes out as `Bearer swarm-agent.<agent>.<secret>`, spelled by
-//! `swarm_queue_client::agent_token`; the gateway's `swarm-logs-auth`
+//! `swarm_agent_verify::agent_token`; the gateway's `swarm-logs-auth`
 //! responder checks it against the store.
 //!
 //! 🩸 The secret is never logged and never rendered into an error.
@@ -87,7 +87,7 @@ impl Config {
                 .with_context(|| format!("reading {}", self.path))
         })?;
         let stored = stored.with_context(|| format!("nothing is stored at {}", self.path))?;
-        swarm_queue_client::agent_token::format_agent_token(&self.agent, &stored.value)
+        swarm_agent_verify::agent_token::format_agent_token(&self.agent, &stored.value)
             .with_context(|| format!("spelling the credential stored at {}", self.path))
     }
 }

swarm-metrics/Cargo.toml

@@ -13,7 +13,7 @@ anyhow.workspace = true
 clap.workspace = true
 clap-markdown = "0.1"
 # The agent-token spelling the gateway's responder parses.
-swarm-queue-client.workspace = true
+swarm-agent-verify.workspace = true
 # The read of this agent's own queue secret.
 swarm-secret-client.workspace = true
 # Only to drive that one async read; the query itself is blocking.

swarm-metrics/src/auth.rs

@@ -5,7 +5,7 @@
 //! The same read and the same bearer as `swarm-logs`' `auth` module: path
 //! `swarm/agents/<agent>/queue`, the agent's cert-auth role, and
 //! `Bearer swarm-agent.<agent>.<secret>` spelled by
-//! `swarm_queue_client::agent_token`. On the metrics store's host a
+//! `swarm_agent_verify::agent_token`. On the metrics store's host a
 //! `swarm-logs-auth` instance checks it against the store.
 //!
 //! 🩸 The secret is never logged and never rendered into an error.
@@ -86,7 +86,7 @@ impl Config {
                 .with_context(|| format!("reading {}", self.path))
         })?;
         let stored = stored.with_context(|| format!("nothing is stored at {}", self.path))?;
-        swarm_queue_client::agent_token::format_agent_token(&self.agent, &stored.value)
+        swarm_agent_verify::agent_token::format_agent_token(&self.agent, &stored.value)
             .with_context(|| format!("spelling the credential stored at {}", self.path))
     }
 }

swarm-nats-auth/src/agent_token.rs

@@ -1,6 +1,6 @@
 //! Classifying a presented `auth_token`, and the grant for an agent's own.
 //!
-//! The spelling is `swarm_queue_client::agent_token`'s, shared with the agent
+//! The spelling is `swarm_agent_verify::agent_token`'s, shared with the agent
 //! that presents it. Whether its secret is the stored one is
 //! [`swarm_agent_verify::verify`]'s answer; nothing here grants on the name
 //! alone.
@@ -9,7 +9,7 @@
 //! unchanged.
 
 use swarm_agent_verify::CredentialSource;
-use swarm_queue_client::agent_token::{AgentToken, Malformed, parse_agent_token};
+use swarm_agent_verify::agent_token::{AgentToken, Malformed, parse_agent_token};
 
 use crate::policy::{Permissions, Policy};
 

swarm-queue-client/src/lib.rs

@@ -200,10 +200,6 @@ pub mod wanted;
 /// inside it. See the module doc for why the two must not merge.
 pub mod agent_status;
 
-/// The token an agent presents its own queue secret in. Store-free, so an agent
-/// formats it without linking the secret-store client.
-pub mod agent_token;
-
 /// The bucket agent icons are published into — one key per agent, with no
 /// hive in it, unlike [`agent_status`]. See the module doc for why the
 /// placement stays out of the key, and for who may write it.

swarm-secret-client/src/queue.rs

@@ -24,7 +24,7 @@
 //! renewing the other.
 //!
 //! The token an agent presents that secret in at the queue is spelled by
-//! `swarm_queue_client::agent_token`, which needs no store client.
+//! `swarm_agent_verify::agent_token`.
 
 use serde::{Deserialize, Serialize};