fix: Discord Ed25519 signature verification and capabilities header alias (#148) (#372)

* test: add failing tests for Discord signature validation and capabilities alias (Red phase)

TDD Red phase for #148. Adds 19 tests across 4 categories:
- Category 1: CredentialLocationSchema header_name alias (2 failing)
- Category 2: Ed25519 signature verification (3 failing)
- Category 3: Router signature key management (2 failing)
- Category 5: Discord capabilities public_key setup (1 failing)

All 8 failures are expected — stubs return false/None by design.
Implementation will follow in Green phase.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: add Discord Ed25519 signature verification and capabilities alias (#148)

Implement the Green phase for Discord channel security fixes:

- Add real Ed25519 signature verification in signature.rs using ed25519-dalek
- Add #[serde(alias = "header_name")] to CredentialLocationSchema::Header
  for backward compatibility with external JSON files
- Add signature_keys storage to WasmChannelRouter (register/get/unregister)
- Add discord_public_key to discord.capabilities.json setup.required_secrets
- Add nested capabilities resolution to CapabilitiesFile for channel-level
  JSON compatibility

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* style: address PR #372 review comments

- Fix invalid hex character in test fake_pub_key (router.rs)
- Simplify signature parsing with from_slice/try_from (signature.rs)
- Use idiomatic Option::or for nested capability merging (capabilities_schema.rs)

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: enforce signature verification, staleness check, key validation, recursive resolve

Address PR #372 review feedback:

- Wire verify_discord_signature() into webhook_handler with Ed25519
  signature + timestamp staleness check (5s window via now_secs param)
- Validate Ed25519 keys in register_signature_key() (hex decode +
  VerifyingKey::try_from) before storing, return Result<(), String>
- Recursively resolve nested capabilities in resolve_nested()
- Add 25 new tests: 8 staleness, 6 key validation, 7 webhook
  integration (tower::oneshot), 4 resolve_nested edge cases
- Fix pre-existing clippy warning in signal.rs

Co-Authored-By: Claude Opus 4.6 <[email protected]>

* fix: wire register_signature_key() into all channel loading paths

The Ed25519 signature key registration was implemented and tested but
never called from production code. All three channel loading paths
(setup_wasm_channels, activate_wasm_channel, refresh_active_channel)
now read the public key from the secrets store and register it with
the webhook router, enabling Discord signature verification.

Adds `signature_key_secret_name` field to WebhookSchema so channels
can declare which secret contains their Ed25519 public key.

Co-Authored-By: Claude Opus 4.6 <[email protected]>

---------

Co-authored-by: Claude Opus 4.6 <[email protected]>

Cargo.lock

@@ -492,6 +492,12 @@ version = "0.22.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "72b3254f16251a8381aa12e40e3c4d2f0199f8c6508fbecb9d91f575e0fbb8c6"
 
+[[package]]
+name = "base64ct"
+version = "1.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2af50177e190e07a26ab74f8b1efbfe2ef87da2116221318cb1c2e82baf7de06"
+
 [[package]]
 name = "bincode"
 version = "1.3.3"
@@ -949,6 +955,12 @@ dependencies = [
  "crossbeam-utils",
 ]
 
+[[package]]
+name = "const-oid"
+version = "0.9.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c2459377285ad874054d797f3ccebf984978aa39129f6eafde5cdc8315b612f8"
+
 [[package]]
 name = "const-random"
 version = "0.1.18"
@@ -1353,6 +1365,33 @@ dependencies = [
  "cipher",
 ]
 
+[[package]]
+name = "curve25519-dalek"
+version = "4.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "97fb8b7c4503de7d6ae7b42ab72a5a59857b4c937ec27a3d4539dba95b5ab2be"
+dependencies = [
+ "cfg-if",
+ "cpufeatures",
+ "curve25519-dalek-derive",
+ "digest",
+ "fiat-crypto",
+ "rustc_version",
+ "subtle",
+ "zeroize",
+]
+
+[[package]]
+name = "curve25519-dalek-derive"
+version = "0.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f46882e17999c6cc590af592290432be3bce0428cb0d5f8b6715e4dc7b383eb3"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.116",
+]
+
 [[package]]
 name = "darling"
 version = "0.21.3"
@@ -1438,6 +1477,16 @@ dependencies = [
  "uuid",
 ]
 
+[[package]]
+name = "der"
+version = "0.7.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e7c1832837b905bbfb5101e07cc24c8deddf52f93225eee6ead5f4d63d53ddcb"
+dependencies = [
+ "const-oid",
+ "zeroize",
+]
+
 [[package]]
 name = "deranged"
 version = "0.5.6"
@@ -1607,6 +1656,30 @@ version = "1.0.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d0881ea181b1df73ff77ffaaf9c7544ecc11e82fba9b5f27b262a3c73a332555"
 
+[[package]]
+name = "ed25519"
+version = "2.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "115531babc129696a58c64a4fef0a8bf9e9698629fb97e9e40767d235cfbcd53"
+dependencies = [
+ "pkcs8",
+ "signature",
+]
+
+[[package]]
+name = "ed25519-dalek"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "70e796c081cee67dc755e1a36a0a172b897fab85fc3f6bc48307991f64e4eca9"
+dependencies = [
+ "curve25519-dalek",
+ "ed25519",
+ "serde",
+ "sha2",
+ "subtle",
+ "zeroize",
+]
+
 [[package]]
 name = "ego-tree"
 version = "0.10.0"
@@ -1773,6 +1846,12 @@ dependencies = [
  "windows-sys 0.59.0",
 ]
 
+[[package]]
+name = "fiat-crypto"
+version = "0.2.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "28dea519a9695b9977216879a3ebfddf92f1c08c05d984f8996aecd6ecdc811d"
+
 [[package]]
 name = "filetime"
 version = "0.2.27"
@@ -2719,9 +2798,11 @@ dependencies = [
  "deadpool-postgres",
  "dirs 6.0.0",
  "dotenvy",
+ "ed25519-dalek",
  "flate2",
  "fs4",
  "futures",
+ "hex",
  "hkdf",
  "html-to-markdown-rs",
  "http-body-util",
@@ -3814,6 +3895,16 @@ dependencies = [
  "futures-io",
 ]
 
+[[package]]
+name = "pkcs8"
+version = "0.10.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f950b2377845cebe5cf8b5165cb3cc1a5e0fa5cfa3e1f7f55707d8fd82e0a7b7"
+dependencies = [
+ "der",
+ "spki",
+]
+
 [[package]]
 name = "pkg-config"
 version = "0.3.32"
@@ -5104,6 +5195,15 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "signature"
+version = "2.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "77549399552de45a898a580c1b41d445bf730df867cc44e6c0233bbc4b8329de"
+dependencies = [
+ "rand_core 0.6.4",
+]
+
 [[package]]
 name = "simd-adler32"
 version = "0.3.8"
@@ -5157,6 +5257,16 @@ dependencies = [
  "windows-sys 0.60.2",
 ]
 
+[[package]]
+name = "spki"
+version = "0.7.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d91ed6c858b01f942cd56b37a94b3e0a1798290327d1236e4d9cf4eaca44d29d"
+dependencies = [
+ "base64ct",
+ "der",
+]
+
 [[package]]
 name = "sptr"
 version = "0.3.2"

Cargo.toml

@@ -154,6 +154,8 @@ lru = "0.16.3"
 # HTML to Markdown conversion (feature gated)
 html-to-markdown-rs = { version = "2.3", optional = true }
 readabilityrs = { version = "0.1.2", optional = true }
+ed25519-dalek = { version = "2.2.0", features = ["std"] }
+hex = "0.4.3"
 
 # macOS keychain
 [target.'cfg(target_os = "macos")'.dependencies]

channels-src/discord/discord.capabilities.json

@@ -8,6 +8,11 @@
         "name": "discord_bot_token",
         "prompt": "Enter your Discord Bot Token (from Developer Portal)",
         "optional": false
+      },
+      {
+        "name": "discord_public_key",
+        "prompt": "Enter your Discord Application Public Key (from Developer Portal > General Information)",
+        "optional": false
       }
     ]
   },
@@ -39,6 +44,9 @@
       "emit_rate_limit": {
         "messages_per_minute": 100,
         "messages_per_hour": 5000
+      },
+      "webhook": {
+        "signature_key_secret_name": "discord_public_key"
       }
     }
   },

src/channels/wasm/loader.rs

@@ -248,6 +248,13 @@ impl LoadedChannel {
             .and_then(|f| f.webhook_secret_header())
     }
 
+    /// Get the signature verification key secret name from capabilities.
+    pub fn signature_key_secret_name(&self) -> Option<String> {
+        self.capabilities_file
+            .as_ref()
+            .and_then(|f| f.signature_key_secret_name().map(|s| s.to_string()))
+    }
+
     /// Get the webhook secret name from capabilities.
     pub fn webhook_secret_name(&self) -> String {
         self.capabilities_file
@@ -416,6 +423,18 @@ mod tests {
         assert!(channels.contains_key("channel"));
     }
 
+    #[test]
+    fn test_loaded_channel_signature_key_none_without_caps() {
+        // We can't easily construct a WasmChannel without a runtime, so test
+        // the delegation logic directly: when capabilities_file is None, the
+        // chain returns None (same logic as LoadedChannel::signature_key_secret_name).
+        let cap_file: Option<crate::channels::wasm::schema::ChannelCapabilitiesFile> = None;
+        let result = cap_file
+            .as_ref()
+            .and_then(|f| f.signature_key_secret_name().map(|s| s.to_string()));
+        assert_eq!(result, None);
+    }
+
     #[tokio::test]
     async fn test_loader_invalid_name() {
         let config = WasmChannelRuntimeConfig::for_testing();

src/channels/wasm/mod.rs

@@ -86,6 +86,7 @@ mod loader;
 mod router;
 mod runtime;
 mod schema;
+pub(crate) mod signature;
 mod wrapper;
 
 // Core types

src/channels/wasm/router.rs

@@ -42,6 +42,8 @@ pub struct WasmChannelRouter {
     secrets: RwLock<HashMap<String, String>>,
     /// Webhook secret header names by channel name (e.g., "X-Telegram-Bot-Api-Secret-Token").
     secret_headers: RwLock<HashMap<String, String>>,
+    /// Ed25519 public keys for signature verification by channel name (hex-encoded).
+    signature_keys: RwLock<HashMap<String, String>>,
 }
 
 impl WasmChannelRouter {
@@ -52,6 +54,7 @@ impl WasmChannelRouter {
             path_to_channel: RwLock::new(HashMap::new()),
             secrets: RwLock::new(HashMap::new()),
             secret_headers: RwLock::new(HashMap::new()),
+            signature_keys: RwLock::new(HashMap::new()),
         }
     }
 
@@ -130,6 +133,7 @@ impl WasmChannelRouter {
         self.channels.write().await.remove(channel_name);
         self.secrets.write().await.remove(channel_name);
         self.secret_headers.write().await.remove(channel_name);
+        self.signature_keys.write().await.remove(channel_name);
 
         // Remove all paths for this channel
         self.path_to_channel
@@ -174,6 +178,36 @@ impl WasmChannelRouter {
     pub async fn list_paths(&self) -> Vec<String> {
         self.path_to_channel.read().await.keys().cloned().collect()
     }
+
+    /// Register an Ed25519 public key for signature verification.
+    ///
+    /// Validates that the key is valid hex encoding of a 32-byte Ed25519 public key.
+    /// Channels with a registered key will have Discord-style Ed25519
+    /// signature validation performed before forwarding to WASM.
+    pub async fn register_signature_key(
+        &self,
+        channel_name: &str,
+        public_key_hex: &str,
+    ) -> Result<(), String> {
+        use ed25519_dalek::VerifyingKey;
+
+        let key_bytes = hex::decode(public_key_hex).map_err(|e| format!("invalid hex: {e}"))?;
+        VerifyingKey::try_from(key_bytes.as_slice())
+            .map_err(|e| format!("invalid Ed25519 public key: {e}"))?;
+
+        self.signature_keys
+            .write()
+            .await
+            .insert(channel_name.to_string(), public_key_hex.to_string());
+        Ok(())
+    }
+
+    /// Get the signature verification key for a channel.
+    ///
+    /// Returns `None` if no key is registered (no signature check needed).
+    pub async fn get_signature_key(&self, channel_name: &str) -> Option<String> {
+        self.signature_keys.read().await.get(channel_name).cloned()
+    }
 }
 
 impl Default for WasmChannelRouter {
@@ -342,6 +376,57 @@ async fn webhook_handler(
         }
     }
 
+    // Ed25519 signature verification (Discord-style)
+    if let Some(pub_key_hex) = state.router.get_signature_key(channel_name).await {
+        let sig_hex = headers
+            .get("x-signature-ed25519")
+            .and_then(|v| v.to_str().ok());
+        let timestamp = headers
+            .get("x-signature-timestamp")
+            .and_then(|v| v.to_str().ok());
+
+        match (sig_hex, timestamp) {
+            (Some(sig), Some(ts)) => {
+                let now_secs = std::time::SystemTime::now()
+                    .duration_since(std::time::UNIX_EPOCH)
+                    .unwrap_or_default()
+                    .as_secs() as i64;
+
+                if !crate::channels::wasm::signature::verify_discord_signature(
+                    &pub_key_hex,
+                    sig,
+                    ts,
+                    &body,
+                    now_secs,
+                ) {
+                    tracing::warn!(
+                        channel = %channel_name,
+                        "Ed25519 signature verification failed"
+                    );
+                    return (
+                        StatusCode::UNAUTHORIZED,
+                        Json(serde_json::json!({
+                            "error": "Invalid signature"
+                        })),
+                    );
+                }
+                tracing::debug!(channel = %channel_name, "Ed25519 signature verified");
+            }
+            _ => {
+                tracing::warn!(
+                    channel = %channel_name,
+                    "Signature headers missing but key is registered"
+                );
+                return (
+                    StatusCode::UNAUTHORIZED,
+                    Json(serde_json::json!({
+                        "error": "Missing signature headers"
+                    })),
+                );
+            }
+        }
+    }
+
     // Convert headers to HashMap
     let headers_map: HashMap<String, String> = headers
         .iter()
@@ -644,4 +729,437 @@ mod tests {
             .await;
         assert_eq!(router.get_secret_header("slack").await, "X-Webhook-Secret");
     }
+
+    // ── Category 3: Router Signature Key Management ─────────────────────
+
+    #[tokio::test]
+    async fn test_register_and_get_signature_key() {
+        let router = WasmChannelRouter::new();
+        let channel = create_test_channel("discord");
+
+        router.register(channel, vec![], None, None).await;
+
+        let fake_pub_key = "a1b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a1b2";
+        router
+            .register_signature_key("discord", fake_pub_key)
+            .await
+            .unwrap();
+
+        let key = router.get_signature_key("discord").await;
+        assert_eq!(key, Some(fake_pub_key.to_string()));
+    }
+
+    #[tokio::test]
+    async fn test_no_signature_key_returns_none() {
+        let router = WasmChannelRouter::new();
+        let channel = create_test_channel("slack");
+        router.register(channel, vec![], None, None).await;
+
+        // Slack has no signature key registered
+        let key = router.get_signature_key("slack").await;
+        assert!(key.is_none());
+    }
+
+    #[tokio::test]
+    async fn test_unregister_removes_signature_key() {
+        let router = WasmChannelRouter::new();
+        let channel = create_test_channel("discord");
+
+        let endpoints = vec![RegisteredEndpoint {
+            channel_name: "discord".to_string(),
+            path: "/webhook/discord".to_string(),
+            methods: vec!["POST".to_string()],
+            require_secret: false,
+        }];
+
+        router.register(channel, endpoints, None, None).await;
+        // Use a valid 32-byte Ed25519 key for this test
+        let valid_key = "d75a980182b10ab7d54bfed3c964073a0ee172f3daa3f4a18446b7e8c7ac6602";
+        router
+            .register_signature_key("discord", valid_key)
+            .await
+            .unwrap();
+
+        // Key should exist
+        assert!(router.get_signature_key("discord").await.is_some());
+
+        // Unregister
+        router.unregister("discord").await;
+
+        // Key should be gone
+        assert!(router.get_signature_key("discord").await.is_none());
+    }
+
+    // ── Key Validation Tests ──────────────────────────────────────────
+
+    #[tokio::test]
+    async fn test_register_valid_signature_key_succeeds() {
+        let router = WasmChannelRouter::new();
+        let channel = create_test_channel("discord");
+        router.register(channel, vec![], None, None).await;
+
+        // Valid 32-byte Ed25519 public key (from test keypair)
+        let valid_key = "d75a980182b10ab7d54bfed3c964073a0ee172f3daa3f4a18446b7e8c7ac6602";
+        let result = router.register_signature_key("discord", valid_key).await;
+        assert!(result.is_ok(), "Valid Ed25519 key should be accepted");
+    }
+
+    #[tokio::test]
+    async fn test_register_invalid_hex_key_fails() {
+        let router = WasmChannelRouter::new();
+        let channel = create_test_channel("discord");
+        router.register(channel, vec![], None, None).await;
+
+        let result = router
+            .register_signature_key("discord", "not-valid-hex-zzz")
+            .await;
+        assert!(result.is_err(), "Invalid hex should be rejected");
+    }
+
+    #[tokio::test]
+    async fn test_register_wrong_length_key_fails() {
+        let router = WasmChannelRouter::new();
+        let channel = create_test_channel("discord");
+        router.register(channel, vec![], None, None).await;
+
+        // 16 bytes instead of 32
+        let short_key = hex::encode([0u8; 16]);
+        let result = router.register_signature_key("discord", &short_key).await;
+        assert!(result.is_err(), "Wrong-length key should be rejected");
+    }
+
+    #[tokio::test]
+    async fn test_register_empty_key_fails() {
+        let router = WasmChannelRouter::new();
+        let channel = create_test_channel("discord");
+        router.register(channel, vec![], None, None).await;
+
+        let result = router.register_signature_key("discord", "").await;
+        assert!(result.is_err(), "Empty key should be rejected");
+    }
+
+    #[tokio::test]
+    async fn test_valid_key_is_retrievable() {
+        let router = WasmChannelRouter::new();
+        let channel = create_test_channel("discord");
+        router.register(channel, vec![], None, None).await;
+
+        let valid_key = "d75a980182b10ab7d54bfed3c964073a0ee172f3daa3f4a18446b7e8c7ac6602";
+        router
+            .register_signature_key("discord", valid_key)
+            .await
+            .unwrap();
+
+        let stored = router.get_signature_key("discord").await;
+        assert_eq!(stored, Some(valid_key.to_string()));
+    }
+
+    #[tokio::test]
+    async fn test_invalid_key_does_not_store() {
+        let router = WasmChannelRouter::new();
+        let channel = create_test_channel("discord");
+        router.register(channel, vec![], None, None).await;
+
+        // Attempt to register invalid key
+        let _ = router
+            .register_signature_key("discord", "not-valid-hex")
+            .await;
+
+        // Should not have stored anything
+        let stored = router.get_signature_key("discord").await;
+        assert!(stored.is_none(), "Invalid key should not be stored");
+    }
+
+    // ── Webhook Handler Integration Tests ─────────────────────────────
+
+    use axum::Router as AxumRouter;
+    use axum::body::Body;
+    use axum::http::{Request, StatusCode};
+    use tower::ServiceExt;
+
+    use crate::channels::wasm::router::create_wasm_channel_router;
+    use ed25519_dalek::{Signer, SigningKey};
+
+    /// Helper to create a router with a registered channel at /webhook/discord.
+    async fn setup_discord_router() -> (Arc<WasmChannelRouter>, AxumRouter) {
+        let wasm_router = Arc::new(WasmChannelRouter::new());
+        let channel = create_test_channel("discord");
+
+        let endpoints = vec![RegisteredEndpoint {
+            channel_name: "discord".to_string(),
+            path: "/webhook/discord".to_string(),
+            methods: vec!["POST".to_string()],
+            require_secret: false,
+        }];
+
+        wasm_router.register(channel, endpoints, None, None).await;
+
+        let app = create_wasm_channel_router(wasm_router.clone(), None);
+        (wasm_router, app)
+    }
+
+    /// Helper: generate a test keypair.
+    fn test_signing_key() -> SigningKey {
+        SigningKey::from_bytes(&[
+            0x9d, 0x61, 0xb1, 0x9d, 0xef, 0xfd, 0x5a, 0x60, 0xba, 0x84, 0x4a, 0xf4, 0x92, 0xec,
+            0x2c, 0xc4, 0x44, 0x49, 0xc5, 0x69, 0x7b, 0x32, 0x69, 0x19, 0x70, 0x3b, 0xac, 0x03,
+            0x1c, 0xae, 0x7f, 0x60,
+        ])
+    }
+
+    #[tokio::test]
+    async fn test_webhook_rejects_missing_sig_headers() {
+        let (wasm_router, app) = setup_discord_router().await;
+
+        // Register a signature key
+        let signing_key = test_signing_key();
+        let pub_key_hex = hex::encode(signing_key.verifying_key().to_bytes());
+        wasm_router
+            .register_signature_key("discord", &pub_key_hex)
+            .await
+            .unwrap();
+
+        // Send request without signature headers
+        let req = Request::builder()
+            .method("POST")
+            .uri("/webhook/discord")
+            .header("content-type", "application/json")
+            .body(Body::from(r#"{"type":1}"#))
+            .unwrap();
+
+        let resp = app.oneshot(req).await.unwrap();
+        assert_eq!(
+            resp.status(),
+            StatusCode::UNAUTHORIZED,
+            "Missing signature headers should return 401"
+        );
+    }
+
+    #[tokio::test]
+    async fn test_webhook_rejects_invalid_signature() {
+        let (wasm_router, app) = setup_discord_router().await;
+
+        let signing_key = test_signing_key();
+        let pub_key_hex = hex::encode(signing_key.verifying_key().to_bytes());
+        wasm_router
+            .register_signature_key("discord", &pub_key_hex)
+            .await
+            .unwrap();
+
+        let req = Request::builder()
+            .method("POST")
+            .uri("/webhook/discord")
+            .header("content-type", "application/json")
+            .header("x-signature-ed25519", "deadbeefdeadbeef")
+            .header("x-signature-timestamp", "1234567890")
+            .body(Body::from(r#"{"type":1}"#))
+            .unwrap();
+
+        let resp = app.oneshot(req).await.unwrap();
+        assert_eq!(
+            resp.status(),
+            StatusCode::UNAUTHORIZED,
+            "Invalid signature should return 401"
+        );
+    }
+
+    #[tokio::test]
+    async fn test_webhook_accepts_valid_signature() {
+        let (wasm_router, app) = setup_discord_router().await;
+
+        let signing_key = test_signing_key();
+        let pub_key_hex = hex::encode(signing_key.verifying_key().to_bytes());
+        wasm_router
+            .register_signature_key("discord", &pub_key_hex)
+            .await
+            .unwrap();
+
+        // Use current timestamp so staleness check passes
+        let now_secs = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_secs();
+        let timestamp = now_secs.to_string();
+        let body_bytes = br#"{"type":1}"#;
+
+        let mut message = Vec::new();
+        message.extend_from_slice(timestamp.as_bytes());
+        message.extend_from_slice(body_bytes);
+        let signature = signing_key.sign(&message);
+        let sig_hex = hex::encode(signature.to_bytes());
+
+        let req = Request::builder()
+            .method("POST")
+            .uri("/webhook/discord")
+            .header("content-type", "application/json")
+            .header("x-signature-ed25519", &sig_hex)
+            .header("x-signature-timestamp", &timestamp)
+            .body(Body::from(&body_bytes[..]))
+            .unwrap();
+
+        let resp = app.oneshot(req).await.unwrap();
+        // Should NOT be 401 — signature is valid (may be 500 since no WASM module)
+        assert_ne!(
+            resp.status(),
+            StatusCode::UNAUTHORIZED,
+            "Valid signature should not return 401"
+        );
+    }
+
+    #[tokio::test]
+    async fn test_webhook_skips_sig_for_no_key() {
+        let (_wasm_router, app) = setup_discord_router().await;
+
+        // No signature key registered — should not require signature
+        let req = Request::builder()
+            .method("POST")
+            .uri("/webhook/discord")
+            .header("content-type", "application/json")
+            .body(Body::from(r#"{"type":1}"#))
+            .unwrap();
+
+        let resp = app.oneshot(req).await.unwrap();
+        // Should NOT be 401 (may be 500 since no WASM module, but not auth failure)
+        assert_ne!(
+            resp.status(),
+            StatusCode::UNAUTHORIZED,
+            "No signature key registered — should skip sig check"
+        );
+    }
+
+    #[tokio::test]
+    async fn test_webhook_sig_check_uses_body() {
+        let (wasm_router, app) = setup_discord_router().await;
+
+        let signing_key = test_signing_key();
+        let pub_key_hex = hex::encode(signing_key.verifying_key().to_bytes());
+        wasm_router
+            .register_signature_key("discord", &pub_key_hex)
+            .await
+            .unwrap();
+
+        let timestamp = "1234567890";
+        // Sign body A
+        let body_a = br#"{"type":1}"#;
+        let mut message = Vec::new();
+        message.extend_from_slice(timestamp.as_bytes());
+        message.extend_from_slice(body_a);
+        let signature = signing_key.sign(&message);
+        let sig_hex = hex::encode(signature.to_bytes());
+
+        // But send body B
+        let body_b = br#"{"type":2}"#;
+        let req = Request::builder()
+            .method("POST")
+            .uri("/webhook/discord")
+            .header("content-type", "application/json")
+            .header("x-signature-ed25519", &sig_hex)
+            .header("x-signature-timestamp", timestamp)
+            .body(Body::from(&body_b[..]))
+            .unwrap();
+
+        let resp = app.oneshot(req).await.unwrap();
+        assert_eq!(
+            resp.status(),
+            StatusCode::UNAUTHORIZED,
+            "Signature for different body should return 401"
+        );
+    }
+
+    #[tokio::test]
+    async fn test_webhook_sig_check_uses_timestamp() {
+        let (wasm_router, app) = setup_discord_router().await;
+
+        let signing_key = test_signing_key();
+        let pub_key_hex = hex::encode(signing_key.verifying_key().to_bytes());
+        wasm_router
+            .register_signature_key("discord", &pub_key_hex)
+            .await
+            .unwrap();
+
+        // Sign with timestamp A
+        let timestamp_a = "1234567890";
+        let body = br#"{"type":1}"#;
+        let mut message = Vec::new();
+        message.extend_from_slice(timestamp_a.as_bytes());
+        message.extend_from_slice(body);
+        let signature = signing_key.sign(&message);
+        let sig_hex = hex::encode(signature.to_bytes());
+
+        // But send timestamp B in the header
+        let timestamp_b = "9999999999";
+        let req = Request::builder()
+            .method("POST")
+            .uri("/webhook/discord")
+            .header("content-type", "application/json")
+            .header("x-signature-ed25519", &sig_hex)
+            .header("x-signature-timestamp", timestamp_b)
+            .body(Body::from(&body[..]))
+            .unwrap();
+
+        let resp = app.oneshot(req).await.unwrap();
+        assert_eq!(
+            resp.status(),
+            StatusCode::UNAUTHORIZED,
+            "Signature with mismatched timestamp should return 401"
+        );
+    }
+
+    #[tokio::test]
+    async fn test_webhook_sig_plus_secret() {
+        let wasm_router = Arc::new(WasmChannelRouter::new());
+        let channel = create_test_channel("discord");
+
+        let endpoints = vec![RegisteredEndpoint {
+            channel_name: "discord".to_string(),
+            path: "/webhook/discord".to_string(),
+            methods: vec!["POST".to_string()],
+            require_secret: true,
+        }];
+
+        // Register with BOTH secret and signature key
+        wasm_router
+            .register(channel, endpoints, Some("my-secret".to_string()), None)
+            .await;
+
+        let signing_key = test_signing_key();
+        let pub_key_hex = hex::encode(signing_key.verifying_key().to_bytes());
+        wasm_router
+            .register_signature_key("discord", &pub_key_hex)
+            .await
+            .unwrap();
+
+        let app = create_wasm_channel_router(wasm_router.clone(), None);
+
+        // Use current timestamp so staleness check passes
+        let now_secs = std::time::SystemTime::now()
+            .duration_since(std::time::UNIX_EPOCH)
+            .unwrap()
+            .as_secs();
+        let timestamp = now_secs.to_string();
+        let body = br#"{"type":1}"#;
+        let mut message = Vec::new();
+        message.extend_from_slice(timestamp.as_bytes());
+        message.extend_from_slice(body);
+        let signature = signing_key.sign(&message);
+        let sig_hex = hex::encode(signature.to_bytes());
+
+        // Provide valid signature AND valid secret
+        let req = Request::builder()
+            .method("POST")
+            .uri("/webhook/discord?secret=my-secret")
+            .header("content-type", "application/json")
+            .header("x-signature-ed25519", &sig_hex)
+            .header("x-signature-timestamp", &timestamp)
+            .body(Body::from(&body[..]))
+            .unwrap();
+
+        let resp = app.oneshot(req).await.unwrap();
+        // Should pass both checks (may be 500 due to no WASM module, but not 401)
+        assert_ne!(
+            resp.status(),
+            StatusCode::UNAUTHORIZED,
+            "Valid secret + valid signature should not return 401"
+        );
+    }
 }

src/channels/wasm/schema.rs

@@ -111,6 +111,18 @@ impl ChannelCapabilitiesFile {
             .and_then(|w| w.secret_header.as_deref())
     }
 
+    /// Get the signature verification key secret name for this channel.
+    ///
+    /// Returns the secret name declared in `webhook.signature_key_secret_name`,
+    /// used to look up the Ed25519 public key in the secrets store.
+    pub fn signature_key_secret_name(&self) -> Option<&str> {
+        self.capabilities
+            .channel
+            .as_ref()
+            .and_then(|c| c.webhook.as_ref())
+            .and_then(|w| w.signature_key_secret_name.as_deref())
+    }
+
     /// Get the webhook secret name for this channel.
     ///
     /// Returns the configured secret name or defaults to "{channel_name}_webhook_secret".
@@ -230,6 +242,11 @@ pub struct WebhookSchema {
     /// Default: "{channel_name}_webhook_secret"
     #[serde(default)]
     pub secret_name: Option<String>,
+
+    /// Secret name in secrets store containing the Ed25519 public key
+    /// for signature verification (e.g., Discord interaction verification).
+    #[serde(default)]
+    pub signature_key_secret_name: Option<String>,
 }
 
 /// Setup configuration schema.
@@ -585,4 +602,90 @@ mod tests {
             64
         );
     }
+
+    // ── Category 5: Discord Capabilities Setup & Configuration ──────────
+
+    #[test]
+    fn test_discord_capabilities_has_public_key_secret() {
+        let json = include_str!("../../../channels-src/discord/discord.capabilities.json");
+        let file = ChannelCapabilitiesFile::from_json(json).unwrap();
+
+        let secret_names: Vec<&str> = file
+            .setup
+            .required_secrets
+            .iter()
+            .map(|s| s.name.as_str())
+            .collect();
+
+        assert!(
+            secret_names.contains(&"discord_public_key"),
+            "discord.capabilities.json must include discord_public_key in setup.required_secrets, \
+             found: {:?}",
+            secret_names
+        );
+    }
+
+    #[test]
+    fn test_webhook_schema_signature_key_secret_name() {
+        let json = r#"{
+            "name": "discord",
+            "capabilities": {
+                "channel": {
+                    "allowed_paths": ["/webhook/discord"],
+                    "webhook": {
+                        "signature_key_secret_name": "discord_public_key"
+                    }
+                }
+            }
+        }"#;
+
+        let file = ChannelCapabilitiesFile::from_json(json).unwrap();
+        assert_eq!(file.signature_key_secret_name(), Some("discord_public_key"));
+    }
+
+    #[test]
+    fn test_signature_key_secret_name_none_when_missing() {
+        let json = r#"{
+            "name": "telegram",
+            "capabilities": {
+                "channel": {
+                    "allowed_paths": ["/webhook/telegram"],
+                    "webhook": {
+                        "secret_header": "X-Telegram-Bot-Api-Secret-Token"
+                    }
+                }
+            }
+        }"#;
+
+        let file = ChannelCapabilitiesFile::from_json(json).unwrap();
+        assert_eq!(file.signature_key_secret_name(), None);
+    }
+
+    #[test]
+    fn test_discord_capabilities_signature_key() {
+        let json = include_str!("../../../channels-src/discord/discord.capabilities.json");
+        let file = ChannelCapabilitiesFile::from_json(json).unwrap();
+        assert_eq!(
+            file.signature_key_secret_name(),
+            Some("discord_public_key"),
+            "discord.capabilities.json must declare signature_key_secret_name"
+        );
+    }
+
+    #[test]
+    fn test_discord_capabilities_secrets_allowlist() {
+        let json = include_str!("../../../channels-src/discord/discord.capabilities.json");
+        let file = ChannelCapabilitiesFile::from_json(json).unwrap();
+
+        let caps = file.to_capabilities();
+        let secrets_caps = caps
+            .tool_capabilities
+            .secrets
+            .expect("Discord should have secrets capability");
+
+        assert!(
+            secrets_caps.is_allowed("discord_public_key"),
+            "discord_public_key must be in the secrets allowlist"
+        );
+    }
 }

src/channels/wasm/signature.rs

@@ -0,0 +1,341 @@
+//! Discord Ed25519 signature verification.
+//!
+//! Validates `X-Signature-Ed25519` and `X-Signature-Timestamp` headers
+//! on incoming Discord interaction webhooks, per Discord's security requirements.
+//!
+//! See: <https://discord.com/developers/docs/interactions/overview#validating-security-request-headers>
+
+/// Verify a Discord interaction signature.
+///
+/// Discord signs each interaction with Ed25519 using:
+/// - message = `timestamp` (UTF-8 bytes) ++ `body` (raw bytes)
+/// - signature = Ed25519 detached signature (hex-encoded in header)
+/// - public_key = Application public key from Developer Portal (hex-encoded)
+///
+/// Returns `true` if the signature is valid, `false` on any error
+/// (bad hex, wrong length, invalid signature, etc.).
+pub fn verify_discord_signature(
+    public_key_hex: &str,
+    signature_hex: &str,
+    timestamp: &str,
+    body: &[u8],
+    now_secs: i64,
+) -> bool {
+    // Staleness check: reject non-numeric or stale/future timestamps
+    let ts: i64 = match timestamp.parse() {
+        Ok(v) => v,
+        Err(_) => return false,
+    };
+    if (now_secs - ts).abs() > 5 {
+        return false;
+    }
+    use ed25519_dalek::{Signature, VerifyingKey};
+
+    let Ok(sig_bytes) = hex::decode(signature_hex) else {
+        return false;
+    };
+    let Ok(key_bytes) = hex::decode(public_key_hex) else {
+        return false;
+    };
+    let Ok(signature) = Signature::from_slice(&sig_bytes) else {
+        return false;
+    };
+    let Ok(verifying_key) = VerifyingKey::try_from(key_bytes.as_slice()) else {
+        return false;
+    };
+
+    let mut message = Vec::with_capacity(timestamp.len() + body.len());
+    message.extend_from_slice(timestamp.as_bytes());
+    message.extend_from_slice(body);
+    verifying_key.verify_strict(&message, &signature).is_ok()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ed25519_dalek::{Signer, SigningKey};
+
+    /// Helper: generate a test keypair and produce a valid signature for the given timestamp+body.
+    fn sign_test_message(timestamp: &str, body: &[u8]) -> (String, String, String) {
+        let signing_key = SigningKey::from_bytes(&[
+            0x9d, 0x61, 0xb1, 0x9d, 0xef, 0xfd, 0x5a, 0x60, 0xba, 0x84, 0x4a, 0xf4, 0x92, 0xec,
+            0x2c, 0xc4, 0x44, 0x49, 0xc5, 0x69, 0x7b, 0x32, 0x69, 0x19, 0x70, 0x3b, 0xac, 0x03,
+            0x1c, 0xae, 0x7f, 0x60,
+        ]);
+        let verifying_key = signing_key.verifying_key();
+
+        let mut message = Vec::new();
+        message.extend_from_slice(timestamp.as_bytes());
+        message.extend_from_slice(body);
+
+        let signature = signing_key.sign(&message);
+
+        let public_key_hex = hex::encode(verifying_key.to_bytes());
+        let signature_hex = hex::encode(signature.to_bytes());
+
+        (public_key_hex, signature_hex, timestamp.to_string())
+    }
+
+    // ── Category 2: Ed25519 Signature Verification ──────────────────────
+
+    /// Existing tests pass `now_secs` matching their hardcoded timestamp
+    /// so they continue testing crypto-only behavior.
+    const TEST_TS: i64 = 1234567890;
+
+    #[test]
+    fn test_valid_signature_succeeds() {
+        let timestamp = "1234567890";
+        let body = b"test body content";
+        let (pub_key, sig, ts) = sign_test_message(timestamp, body);
+
+        assert!(
+            verify_discord_signature(&pub_key, &sig, &ts, body, TEST_TS),
+            "Valid signature should verify successfully"
+        );
+    }
+
+    #[test]
+    fn test_invalid_signature_fails() {
+        let timestamp = "1234567890";
+        let body = b"test body content";
+        let (pub_key, mut sig, ts) = sign_test_message(timestamp, body);
+
+        // Tamper one byte of the signature
+        let mut sig_bytes = hex::decode(&sig).unwrap();
+        sig_bytes[0] ^= 0xff;
+        sig = hex::encode(&sig_bytes);
+
+        assert!(
+            !verify_discord_signature(&pub_key, &sig, &ts, body, TEST_TS),
+            "Tampered signature should fail verification"
+        );
+    }
+
+    #[test]
+    fn test_tampered_body_fails() {
+        let timestamp = "1234567890";
+        let body = b"original body";
+        let (pub_key, sig, ts) = sign_test_message(timestamp, body);
+
+        let tampered_body = b"tampered body";
+        assert!(
+            !verify_discord_signature(&pub_key, &sig, &ts, tampered_body, TEST_TS),
+            "Signature for different body should fail"
+        );
+    }
+
+    #[test]
+    fn test_tampered_timestamp_fails() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, sig, _ts) = sign_test_message(timestamp, body);
+
+        assert!(
+            !verify_discord_signature(&pub_key, &sig, "9999999999", body, TEST_TS),
+            "Signature with wrong timestamp should fail"
+        );
+    }
+
+    #[test]
+    fn test_invalid_hex_signature_fails() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, _sig, ts) = sign_test_message(timestamp, body);
+
+        assert!(
+            !verify_discord_signature(&pub_key, "not-valid-hex-zzz", &ts, body, TEST_TS),
+            "Non-hex signature should fail gracefully"
+        );
+    }
+
+    #[test]
+    fn test_invalid_hex_public_key_fails() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (_pub_key, sig, ts) = sign_test_message(timestamp, body);
+
+        assert!(
+            !verify_discord_signature("not-valid-hex-zzz", &sig, &ts, body, TEST_TS),
+            "Non-hex public key should fail gracefully"
+        );
+    }
+
+    #[test]
+    fn test_wrong_length_signature_fails() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, _sig, ts) = sign_test_message(timestamp, body);
+
+        // Too short (only 32 bytes instead of 64)
+        let short_sig = hex::encode([0u8; 32]);
+        assert!(
+            !verify_discord_signature(&pub_key, &short_sig, &ts, body, TEST_TS),
+            "Short signature should fail"
+        );
+    }
+
+    #[test]
+    fn test_wrong_length_public_key_fails() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (_pub_key, sig, ts) = sign_test_message(timestamp, body);
+
+        // Too short (only 16 bytes instead of 32)
+        let short_key = hex::encode([0u8; 16]);
+        assert!(
+            !verify_discord_signature(&short_key, &sig, &ts, body, TEST_TS),
+            "Short public key should fail"
+        );
+    }
+
+    #[test]
+    fn test_empty_body_valid_signature() {
+        let timestamp = "1234567890";
+        let body = b"";
+        let (pub_key, sig, ts) = sign_test_message(timestamp, body);
+
+        assert!(
+            verify_discord_signature(&pub_key, &sig, &ts, body, TEST_TS),
+            "Empty body with valid signature should succeed"
+        );
+    }
+
+    #[test]
+    fn test_discord_reference_vector() {
+        // Hardcoded test vector using the RFC 8032 test key
+        // This ensures the implementation matches the standard Ed25519 algorithm
+        let signing_key = SigningKey::from_bytes(&[
+            0xc5, 0xaa, 0x8d, 0xf4, 0x3f, 0x9f, 0x83, 0x7b, 0xed, 0xb7, 0x44, 0x2f, 0x31, 0xdc,
+            0xb7, 0xb1, 0x66, 0xd3, 0x85, 0x35, 0x07, 0x6f, 0x09, 0x4b, 0x85, 0xce, 0x3a, 0x2e,
+            0x0b, 0x44, 0x58, 0xf7,
+        ]);
+        let verifying_key = signing_key.verifying_key();
+        let public_key_hex = hex::encode(verifying_key.to_bytes());
+
+        let timestamp = "1609459200";
+        let now_secs: i64 = 1609459200;
+        let body = br#"{"type":1}"#; // Discord PING
+
+        let mut message = Vec::new();
+        message.extend_from_slice(timestamp.as_bytes());
+        message.extend_from_slice(body);
+
+        let signature = signing_key.sign(&message);
+        let signature_hex = hex::encode(signature.to_bytes());
+
+        assert!(
+            verify_discord_signature(&public_key_hex, &signature_hex, timestamp, body, now_secs),
+            "Reference vector should verify"
+        );
+
+        // Same key, but tampered body should fail
+        assert!(
+            !verify_discord_signature(
+                &public_key_hex,
+                &signature_hex,
+                timestamp,
+                br#"{"type":2}"#,
+                now_secs
+            ),
+            "Reference vector with tampered body should fail"
+        );
+    }
+
+    // ── Category: Timestamp Staleness ─────────────────────────────────
+
+    #[test]
+    fn test_stale_timestamp_rejected() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, sig, ts) = sign_test_message(timestamp, body);
+        // now_secs is 100 seconds after the timestamp — too stale
+        assert!(
+            !verify_discord_signature(&pub_key, &sig, &ts, body, TEST_TS + 100),
+            "Stale timestamp (100s old) should be rejected"
+        );
+    }
+
+    #[test]
+    fn test_future_timestamp_rejected() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, sig, ts) = sign_test_message(timestamp, body);
+        // now_secs is 100 seconds before the timestamp — future
+        assert!(
+            !verify_discord_signature(&pub_key, &sig, &ts, body, TEST_TS - 100),
+            "Future timestamp (100s ahead) should be rejected"
+        );
+    }
+
+    #[test]
+    fn test_fresh_timestamp_accepted() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, sig, ts) = sign_test_message(timestamp, body);
+        // now_secs matches exactly — fresh
+        assert!(
+            verify_discord_signature(&pub_key, &sig, &ts, body, TEST_TS),
+            "Fresh timestamp (0s difference) should be accepted"
+        );
+    }
+
+    #[test]
+    fn test_non_numeric_timestamp_rejected() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, sig, _ts) = sign_test_message(timestamp, body);
+        // Pass a non-numeric timestamp string
+        assert!(
+            !verify_discord_signature(&pub_key, &sig, "not-a-number", body, 0),
+            "Non-numeric timestamp should be rejected"
+        );
+    }
+
+    #[test]
+    fn test_empty_timestamp_rejected() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, sig, _ts) = sign_test_message(timestamp, body);
+        // Pass an empty timestamp string
+        assert!(
+            !verify_discord_signature(&pub_key, &sig, "", body, 0),
+            "Empty timestamp should be rejected"
+        );
+    }
+
+    #[test]
+    fn test_boundary_5s_accepted() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, sig, ts) = sign_test_message(timestamp, body);
+        // Exactly 5 seconds difference — should be accepted (> 5, not >= 5)
+        assert!(
+            verify_discord_signature(&pub_key, &sig, &ts, body, TEST_TS + 5),
+            "Timestamp exactly 5s old should be accepted"
+        );
+    }
+
+    #[test]
+    fn test_boundary_6s_rejected() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, sig, ts) = sign_test_message(timestamp, body);
+        // 6 seconds difference — should be rejected
+        assert!(
+            !verify_discord_signature(&pub_key, &sig, &ts, body, TEST_TS + 6),
+            "Timestamp 6s old should be rejected"
+        );
+    }
+
+    #[test]
+    fn test_negative_timestamp_rejected() {
+        let timestamp = "1234567890";
+        let body = b"test body";
+        let (pub_key, sig, _ts) = sign_test_message(timestamp, body);
+        // Pass a negative timestamp string
+        assert!(
+            !verify_discord_signature(&pub_key, &sig, "-1", body, TEST_TS),
+            "Negative timestamp should be rejected"
+        );
+    }
+}

src/extensions/manager.rs

@@ -1796,6 +1796,7 @@ impl ExtensionManager {
         let channel_name = loaded.name().to_string();
         let webhook_secret_name = loaded.webhook_secret_name();
         let secret_header = loaded.webhook_secret_header().map(|s| s.to_string());
+        let sig_key_secret_name = loaded.signature_key_secret_name();
 
         // Get webhook secret from secrets store
         let webhook_secret = self
@@ -1861,6 +1862,26 @@ impl ExtensionManager {
                 )
                 .await;
             tracing::info!(channel = %channel_name, "Registered hot-activated channel with webhook router");
+
+            // Register Ed25519 signature key if declared in capabilities
+            if let Some(ref sig_key_name) = sig_key_secret_name
+                && let Ok(key_secret) = self
+                    .secrets
+                    .get_decrypted(&self.user_id, sig_key_name)
+                    .await
+            {
+                match wasm_channel_router
+                    .register_signature_key(&channel_name, key_secret.expose())
+                    .await
+                {
+                    Ok(()) => {
+                        tracing::info!(channel = %channel_name, "Registered signature key for hot-activated channel")
+                    }
+                    Err(e) => {
+                        tracing::error!(channel = %channel_name, error = %e, "Failed to register signature key")
+                    }
+                }
+            }
         }
 
         // Inject credentials
@@ -1996,6 +2017,37 @@ impl ExtensionManager {
             existing_channel.update_config(config_updates).await;
         }
 
+        // Also refresh signature key in the router
+        let sig_key_secret_name = {
+            let cap_path = self
+                .wasm_channels_dir
+                .join(format!("{}.capabilities.json", name));
+            match tokio::fs::read(&cap_path).await {
+                Ok(bytes) => crate::channels::wasm::ChannelCapabilitiesFile::from_bytes(&bytes)
+                    .ok()
+                    .and_then(|f| f.signature_key_secret_name().map(|s| s.to_string())),
+                Err(_) => None,
+            }
+        };
+        if let Some(ref sig_key_name) = sig_key_secret_name
+            && let Ok(key_secret) = self
+                .secrets
+                .get_decrypted(&self.user_id, sig_key_name)
+                .await
+        {
+            match router
+                .register_signature_key(name, key_secret.expose())
+                .await
+            {
+                Ok(()) => {
+                    tracing::info!(channel = %name, "Refreshed signature verification key")
+                }
+                Err(e) => {
+                    tracing::error!(channel = %name, error = %e, "Failed to refresh signature key")
+                }
+            }
+        }
+
         // Refresh tunnel_url in case it wasn't set at startup
         if let Some(ref tunnel_url) = self.tunnel_url {
             let mut config_updates = std::collections::HashMap::new();

src/main.rs

@@ -896,6 +896,7 @@ async fn setup_wasm_channels(
         tracing::info!("Loaded WASM channel: {}", channel_name);
 
         let secret_name = loaded.webhook_secret_name();
+        let sig_key_secret_name = loaded.signature_key_secret_name();
 
         let webhook_secret = if let Some(secrets) = secrets_store {
             secrets
@@ -969,6 +970,25 @@ async fn setup_wasm_channels(
                 secret_header,
             )
             .await;
+
+        // Register Ed25519 signature key if declared in capabilities
+        if let Some(ref sig_key_name) = sig_key_secret_name
+            && let Some(secrets) = secrets_store
+            && let Ok(key_secret) = secrets.get_decrypted("default", sig_key_name).await
+        {
+            match wasm_router
+                .register_signature_key(&channel_name, key_secret.expose())
+                .await
+            {
+                Ok(()) => {
+                    tracing::info!(channel = %channel_name, "Registered Ed25519 signature key")
+                }
+                Err(e) => {
+                    tracing::error!(channel = %channel_name, error = %e, "Invalid signature key in secrets store")
+                }
+            }
+        }
+
         if let Some(secrets) = secrets_store {
             match inject_channel_credentials(&channel_arc, secrets.as_ref(), &channel_name).await {
                 Ok(count) => {

src/tools/wasm/capabilities_schema.rs

@@ -61,17 +61,42 @@ pub struct CapabilitiesFile {
     /// Used by `ironclaw config` to guide users through auth setup.
     #[serde(default)]
     pub auth: Option<AuthCapabilitySchema>,
+
+    /// Nested capabilities wrapper for channel-level JSON compatibility.
+    ///
+    /// Channel capabilities files nest tool capabilities under a `"capabilities"` key.
+    /// This allows `from_json()`/`from_bytes()` to also parse channel-level JSON;
+    /// inner fields are promoted into top-level fields by `resolve_nested()`.
+    /// Always `None` after construction via the public parse methods.
+    #[serde(default, skip_serializing)]
+    pub capabilities: Option<Box<CapabilitiesFile>>,
 }
 
 impl CapabilitiesFile {
     /// Parse from JSON string.
     pub fn from_json(json: &str) -> Result<Self, serde_json::Error> {
-        serde_json::from_str(json)
+        serde_json::from_str::<Self>(json).map(Self::resolve_nested)
     }
 
     /// Parse from JSON bytes.
     pub fn from_bytes(bytes: &[u8]) -> Result<Self, serde_json::Error> {
-        serde_json::from_slice(bytes)
+        serde_json::from_slice::<Self>(bytes).map(Self::resolve_nested)
+    }
+
+    /// Merge nested `capabilities` wrapper into top-level fields.
+    ///
+    /// Channel-level JSON nests tool capabilities under `"capabilities"`.
+    /// This promotes the inner fields so callers can access them uniformly.
+    fn resolve_nested(mut self) -> Self {
+        if let Some(inner) = self.capabilities.take() {
+            let inner = inner.resolve_nested();
+            self.http = self.http.or(inner.http);
+            self.secrets = self.secrets.or(inner.secrets);
+            self.tool_invoke = self.tool_invoke.or(inner.tool_invoke);
+            self.workspace = self.workspace.or(inner.workspace);
+            self.auth = self.auth.or(inner.auth);
+        }
+        self
     }
 
     /// Convert to runtime Capabilities.
@@ -234,6 +259,7 @@ pub enum CredentialLocationSchema {
 
     /// Custom header.
     Header {
+        #[serde(alias = "header_name")]
         name: String,
         #[serde(default)]
         prefix: Option<String>,
@@ -754,4 +780,217 @@ mod tests {
         assert!(auth.display_name.is_none());
         assert!(auth.setup_url.is_none());
     }
+
+    // ── Category 1: Header field name alias ─────────────────────────────
+
+    #[test]
+    fn test_header_location_with_name_field() {
+        let json = r#"{
+            "http": {
+                "allowlist": [{ "host": "discord.com" }],
+                "credentials": {
+                    "bot_token": {
+                        "secret_name": "discord_bot_token",
+                        "location": { "type": "header", "name": "Authorization", "prefix": "Bot " },
+                        "host_patterns": ["discord.com"]
+                    }
+                }
+            }
+        }"#;
+
+        let caps = CapabilitiesFile::from_json(json).unwrap();
+        let http = caps.http.unwrap();
+        let cred = http.credentials.get("bot_token").unwrap();
+        match &cred.location {
+            CredentialLocationSchema::Header { name, prefix } => {
+                assert_eq!(name, "Authorization");
+                assert_eq!(prefix, &Some("Bot ".to_string()));
+            }
+            _ => panic!("Expected Header location"),
+        }
+    }
+
+    #[test]
+    fn test_header_location_with_header_name_alias() {
+        // Uses "header_name" instead of "name" — should parse via serde alias
+        let json = r#"{
+            "http": {
+                "allowlist": [{ "host": "discord.com" }],
+                "credentials": {
+                    "bot_token": {
+                        "secret_name": "discord_bot_token",
+                        "location": { "type": "header", "header_name": "Authorization", "prefix": "Bot " },
+                        "host_patterns": ["discord.com"]
+                    }
+                }
+            }
+        }"#;
+
+        let caps = CapabilitiesFile::from_json(json).unwrap();
+        let http = caps.http.unwrap();
+        let cred = http.credentials.get("bot_token").unwrap();
+        match &cred.location {
+            CredentialLocationSchema::Header { name, prefix } => {
+                assert_eq!(name, "Authorization");
+                assert_eq!(prefix, &Some("Bot ".to_string()));
+            }
+            _ => panic!("Expected Header location"),
+        }
+    }
+
+    #[test]
+    fn test_discord_capabilities_file_parses() {
+        // Full Discord capabilities JSON — tests end-to-end parsing
+        let json = r#"{
+            "type": "channel",
+            "name": "discord",
+            "description": "Discord channel",
+            "setup": {
+                "required_secrets": [
+                    {
+                        "name": "discord_bot_token",
+                        "prompt": "Enter your Discord Bot Token",
+                        "optional": false
+                    },
+                    {
+                        "name": "discord_public_key",
+                        "prompt": "Enter your Discord Public Key",
+                        "optional": false
+                    }
+                ]
+            },
+            "capabilities": {
+                "http": {
+                    "allowlist": [{ "host": "discord.com", "path_prefix": "/api/v10" }],
+                    "credentials": {
+                        "discord_bot_token": {
+                            "secret_name": "discord_bot_token",
+                            "location": { "type": "header", "name": "Authorization", "prefix": "Bot " },
+                            "host_patterns": ["discord.com"]
+                        }
+                    }
+                }
+            },
+            "config": {
+                "require_signature_verification": true
+            }
+        }"#;
+
+        // This must not panic — parsing should succeed
+        let caps = CapabilitiesFile::from_json(json).unwrap();
+        let http = caps.http.unwrap();
+        assert!(http.credentials.contains_key("discord_bot_token"));
+    }
+
+    #[test]
+    fn test_header_location_missing_name_fails() {
+        // Neither "name" nor "header_name" provided — should fail
+        let json = r#"{
+            "http": {
+                "allowlist": [{ "host": "example.com" }],
+                "credentials": {
+                    "api_key": {
+                        "secret_name": "my_key",
+                        "location": { "type": "header", "prefix": "Key " },
+                        "host_patterns": ["example.com"]
+                    }
+                }
+            }
+        }"#;
+
+        assert!(
+            CapabilitiesFile::from_json(json).is_err(),
+            "Header without name or header_name should fail deserialization"
+        );
+    }
+
+    // ── resolve_nested tests ──────────────────────────────────────────
+
+    #[test]
+    fn test_resolve_nested_outer_takes_precedence() {
+        // Outer http should win over inner http
+        let json = r#"{
+            "http": {
+                "allowlist": [{ "host": "outer.example.com" }]
+            },
+            "capabilities": {
+                "http": {
+                    "allowlist": [{ "host": "inner.example.com" }]
+                }
+            }
+        }"#;
+
+        let caps = CapabilitiesFile::from_json(json).unwrap();
+        let http = caps.http.unwrap();
+        assert_eq!(
+            http.allowlist[0].host, "outer.example.com",
+            "Outer http should take precedence over inner"
+        );
+    }
+
+    #[test]
+    fn test_resolve_nested_doubly_nested() {
+        // capabilities.capabilities.http should resolve to top-level
+        let json = r#"{
+            "capabilities": {
+                "capabilities": {
+                    "http": {
+                        "allowlist": [{ "host": "deep.example.com" }]
+                    }
+                }
+            }
+        }"#;
+
+        let caps = CapabilitiesFile::from_json(json).unwrap();
+        let http = caps.http.unwrap();
+        assert_eq!(
+            http.allowlist[0].host, "deep.example.com",
+            "Doubly-nested capabilities should be resolved"
+        );
+    }
+
+    #[test]
+    fn test_resolve_nested_all_fields_promoted() {
+        // Inner has secrets, workspace, and auth — all should be promoted
+        let json = r#"{
+            "capabilities": {
+                "secrets": {
+                    "allowed_names": ["my_secret"]
+                },
+                "workspace": {
+                    "allowed_prefixes": ["data/"]
+                },
+                "auth": {
+                    "secret_name": "my_auth_token"
+                }
+            }
+        }"#;
+
+        let caps = CapabilitiesFile::from_json(json).unwrap();
+        assert!(caps.secrets.is_some(), "secrets should be promoted");
+        assert!(caps.workspace.is_some(), "workspace should be promoted");
+        assert!(caps.auth.is_some(), "auth should be promoted");
+
+        assert_eq!(caps.secrets.unwrap().allowed_names, vec!["my_secret"]);
+        assert_eq!(caps.workspace.unwrap().allowed_prefixes, vec!["data/"]);
+        assert_eq!(caps.auth.unwrap().secret_name, "my_auth_token");
+    }
+
+    #[test]
+    fn test_resolve_nested_empty_capabilities_noop() {
+        // Empty inner capabilities should not clobber outer http
+        let json = r#"{
+            "http": {
+                "allowlist": [{ "host": "preserved.example.com" }]
+            },
+            "capabilities": {}
+        }"#;
+
+        let caps = CapabilitiesFile::from_json(json).unwrap();
+        let http = caps.http.unwrap();
+        assert_eq!(
+            http.allowlist[0].host, "preserved.example.com",
+            "Empty inner capabilities should not clobber outer http"
+        );
+    }
 }