feat(trogon-source-linear): publish unroutable payloads to DLQ

Signed-off-by: Yordis Prieto <yordis.prieto@gmail.com>

Author: yordis

rsworkspace/Cargo.lock

@@ -26,6 +26,9 @@ trogon-std = { workspace = true }
 
 [dev-dependencies]
 tokio = { workspace = true, features = ["macros", "rt-multi-thread"] }
+tower = "0.5"
+tracing-subscriber = { workspace = true }
+trogon-nats = { workspace = true, features = ["test-support"] }
 trogon-std = { workspace = true, features = ["test-support"] }
 testcontainers-modules = { version = "0.8", features = ["nats"] }
 reqwest = { version = "0.12", default-features = false, features = ["json", "rustls-tls"] }

rsworkspace/crates/trogon-source-linear/Cargo.toml

@@ -9,3 +9,5 @@ pub const DEFAULT_TIMESTAMP_TOLERANCE_SECS: u64 = 60;
 /// Default JetStream ACK timeout: 10 seconds.
 pub const DEFAULT_NATS_ACK_TIMEOUT_MS: u64 = 10_000;
 pub const DEFAULT_NATS_CONNECT_TIMEOUT: Duration = Duration::from_secs(10);
+
+pub const NATS_HEADER_REJECT_REASON: &str = "X-Linear-Reject-Reason";

rsworkspace/crates/trogon-source-linear/src/constants.rs

@@ -17,6 +17,10 @@
 //! - **Headers**: `Nats-Msg-Id` (set to Linear's `webhookId` for dedup)
 //! - **Payload**: raw JSON body from Linear
 //!
+//! Payloads that pass signature verification but fail validation (invalid JSON,
+//! missing/invalid `type` or `action`, stale timestamp) are published to
+//! `{LINEAR_SUBJECT_PREFIX}.unroutable` with an `X-Linear-Reject-Reason` header.
+//!
 //! ## Configuration (env vars)
 //!
 //! | Variable | Default | Description |