feat(v1.1.7-email-inbound): webhook receiver + email:receive trigger

Inbound email: a provider POSTs a normalized JSON message to
POST /api/v1/email-inbound/{app_id}/{trigger_id}; the public receiver
verifies the optional HMAC signature, builds a TriggerEvent::Email, and
enqueues an outbox row the dispatcher delivers like any async trigger.
Handlers see ctx.event.email = #{from,to,cc,subject,text,html,
received_at,message_id}.

- migration 0024: widen triggers.kind + outbox.source_kind CHECKs to
  'email'; new email_trigger_details table.
- TriggerKind::Email, TriggerDetails::Email{has_inbound_secret},
  OutboxSourceKind::Email, TriggerEvent::Email; dispatcher routes the
  email row via the generic resolve_trigger path.
- Admin POST /apps/{id}/triggers/email (validate_trigger_target; module
  + cross-app rejection). inbound_secret is stored ENCRYPTED via the
  master key (deviation from the brief's plaintext default; decrypted
  per inbound request — see HANDBACK §7).
- Dashboard: email trigger form on the Triggers tab + webhook URL +
  expected-payload help.
- 8 DB-gated e2e tests (202/401/404/422/cross-app/handler-fire) +
  receiver unit tests (HMAC verify, secret round-trip, payload parse).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

crates/manager-core/src/trigger_repo.rs

@@ -57,6 +57,8 @@ pub enum TriggerKind {
     Files,
     /// v1.1.5.
     Pubsub,
+    /// v1.1.7. Inbound email via the webhook receiver.
+    Email,
 }
 
 impl TriggerKind {
@@ -69,6 +71,7 @@ impl TriggerKind {
             Self::Cron => "cron",
             Self::Files => "files",
             Self::Pubsub => "pubsub",
+            Self::Email => "email",
         }
     }
 
@@ -81,6 +84,7 @@ impl TriggerKind {
             "cron" => Some(Self::Cron),
             "files" => Some(Self::Files),
             "pubsub" => Some(Self::Pubsub),
+            "email" => Some(Self::Email),
             _ => None,
         }
     }
@@ -137,6 +141,10 @@ pub enum TriggerDetails {
     },
     /// v1.1.5. A topic pattern: exact, `<prefix>.*`, or `*`.
     Pubsub { topic_pattern: String },
+    /// v1.1.7. Inbound email. The HMAC `inbound_secret` is never
+    /// surfaced (it's encrypted at rest); we expose only whether one is
+    /// configured so the admin UI can show "signed" vs "unsigned".
+    Email { has_inbound_secret: bool },
 }
 
 /// Create payload for a KV trigger. Defaults applied at the admin
@@ -232,6 +240,33 @@ pub struct CreatePubsubTrigger {
     pub registered_by_principal: AdminUserId,
 }
 
+/// Create payload for an email trigger (v1.1.7). `inbound_secret_*` is
+/// the already-encrypted HMAC secret (sealed by the admin layer with the
+/// process master key) or `None` for an unsigned trigger.
+#[derive(Debug, Clone)]
+pub struct CreateEmailTrigger {
+    pub script_id: ScriptId,
+    pub inbound_secret_encrypted: Option<Vec<u8>>,
+    pub inbound_secret_nonce: Option<Vec<u8>>,
+    pub registered_by_principal: AdminUserId,
+}
+
+/// What the inbound-email webhook receiver needs to verify + dispatch a
+/// POST. Returned by `email_inbound_target`; `None` when the trigger
+/// doesn't exist or isn't `kind = 'email'`.
+#[derive(Debug, Clone)]
+pub struct EmailInboundTarget {
+    pub app_id: AppId,
+    pub script_id: ScriptId,
+    pub enabled: bool,
+    pub dispatch_mode: TriggerDispatchMode,
+    pub registered_by_principal: AdminUserId,
+    /// Encrypted HMAC secret + nonce; both `None` for an unsigned
+    /// trigger (accepts any POST).
+    pub inbound_secret_encrypted: Option<Vec<u8>>,
+    pub inbound_secret_nonce: Option<Vec<u8>>,
+}
+
 /// One match for the dispatcher's "which KV triggers fire on this
 /// event" lookup. Carries everything the dispatcher needs to construct
 /// the outbox row.
@@ -313,6 +348,23 @@ pub trait TriggerRepo: Send + Sync {
         req: CreatePubsubTrigger,
     ) -> Result<Trigger, TriggerRepoError>;
 
+    /// v1.1.7. Inbound email trigger. The `inbound_secret` is stored
+    /// already-encrypted (the admin layer seals it).
+    async fn create_email_trigger(
+        &self,
+        app_id: AppId,
+        req: CreateEmailTrigger,
+    ) -> Result<Trigger, TriggerRepoError>;
+
+    /// v1.1.7. The webhook receiver's hot-path lookup: resolve a
+    /// `kind = 'email'` trigger to its app, handler script, dispatch
+    /// mode, and (encrypted) HMAC secret. Returns `None` when the
+    /// trigger doesn't exist or isn't an email trigger.
+    async fn email_inbound_target(
+        &self,
+        trigger_id: TriggerId,
+    ) -> Result<Option<EmailInboundTarget>, TriggerRepoError>;
+
     async fn list_for_app(&self, app_id: AppId) -> Result<Vec<Trigger>, TriggerRepoError>;
 
     async fn get(&self, id: TriggerId) -> Result<Option<Trigger>, TriggerRepoError>;
@@ -761,6 +813,89 @@ impl TriggerRepo for PostgresTriggerRepo {
         })
     }
 
+    async fn create_email_trigger(
+        &self,
+        app_id: AppId,
+        req: CreateEmailTrigger,
+    ) -> Result<Trigger, TriggerRepoError> {
+        let has_inbound_secret = req.inbound_secret_encrypted.is_some();
+        let mut tx = self.pool.begin().await?;
+        // Inbound email is delivered async like every other fan-out
+        // event; the receiver enqueues an outbox row the dispatcher
+        // picks up. Retry settings use the standard defaults.
+        let parent: TriggerRow = sqlx::query_as(
+            "INSERT INTO triggers ( \
+                app_id, script_id, kind, enabled, dispatch_mode, \
+                retry_max_attempts, retry_backoff, retry_base_ms, \
+                registered_by_principal \
+             ) VALUES ($1, $2, 'email', TRUE, 'async', 3, 'exponential', 1000, $3) \
+             RETURNING id, app_id, script_id, kind, enabled, dispatch_mode, \
+                       retry_max_attempts, retry_backoff, retry_base_ms, \
+                       registered_by_principal, created_at, updated_at",
+        )
+        .bind(app_id.into_inner())
+        .bind(req.script_id.into_inner())
+        .bind(req.registered_by_principal.into_inner())
+        .fetch_one(&mut *tx)
+        .await?;
+
+        sqlx::query(
+            "INSERT INTO email_trigger_details \
+                (trigger_id, inbound_secret_encrypted, inbound_secret_nonce) \
+             VALUES ($1, $2, $3)",
+        )
+        .bind(parent.id)
+        .bind(req.inbound_secret_encrypted.as_deref())
+        .bind(req.inbound_secret_nonce.as_deref())
+        .execute(&mut *tx)
+        .await?;
+
+        tx.commit().await?;
+
+        Ok(Trigger {
+            id: parent.id.into(),
+            app_id: parent.app_id.into(),
+            script_id: parent.script_id.into(),
+            kind: TriggerKind::Email,
+            enabled: parent.enabled,
+            dispatch_mode: dispatch_from_str(&parent.dispatch_mode),
+            retry_max_attempts: u32::try_from(parent.retry_max_attempts).unwrap_or(3),
+            retry_backoff: BackoffShape::from_wire(&parent.retry_backoff)
+                .unwrap_or(BackoffShape::Exponential),
+            retry_base_ms: u32::try_from(parent.retry_base_ms).unwrap_or(1000),
+            registered_by_principal: parent.registered_by_principal.into(),
+            created_at: parent.created_at,
+            updated_at: parent.updated_at,
+            details: TriggerDetails::Email { has_inbound_secret },
+        })
+    }
+
+    async fn email_inbound_target(
+        &self,
+        trigger_id: TriggerId,
+    ) -> Result<Option<EmailInboundTarget>, TriggerRepoError> {
+        let row: Option<EmailInboundRow> = sqlx::query_as(
+            "SELECT t.app_id, t.script_id, t.enabled, t.dispatch_mode, \
+                    t.registered_by_principal, \
+                    d.inbound_secret_encrypted, d.inbound_secret_nonce \
+             FROM triggers t \
+             JOIN email_trigger_details d ON d.trigger_id = t.id \
+             WHERE t.id = $1 AND t.kind = 'email'",
+        )
+        .bind(trigger_id.into_inner())
+        .fetch_optional(&self.pool)
+        .await?;
+        Ok(row.map(|r| EmailInboundTarget {
+            app_id: r.app_id.into(),
+            script_id: r.script_id.into(),
+            enabled: r.enabled,
+            dispatch_mode: dispatch_from_str(&r.dispatch_mode),
+            registered_by_principal: r.registered_by_principal.into(),
+            inbound_secret_encrypted: r.inbound_secret_encrypted,
+            inbound_secret_nonce: r.inbound_secret_nonce,
+        }))
+    }
+
     async fn list_for_app(&self, app_id: AppId) -> Result<Vec<Trigger>, TriggerRepoError> {
         let parents: Vec<TriggerRow> = sqlx::query_as(
             "SELECT id, app_id, script_id, kind, enabled, dispatch_mode, \
@@ -1077,6 +1212,17 @@ async fn hydrate_one(pool: &PgPool, parent: TriggerRow) -> Result<Trigger, Trigg
                 topic_pattern: row.topic_pattern,
             }
         }
+        TriggerKind::Email => {
+            let row: EmailDetailRow = sqlx::query_as(
+                "SELECT inbound_secret_encrypted FROM email_trigger_details WHERE trigger_id = $1",
+            )
+            .bind(parent.id)
+            .fetch_one(pool)
+            .await?;
+            TriggerDetails::Email {
+                has_inbound_secret: row.inbound_secret_encrypted.is_some(),
+            }
+        }
     };
 
     Ok(Trigger {
@@ -1154,6 +1300,22 @@ struct PubsubDetailRow {
     topic_pattern: String,
 }
 
+#[derive(sqlx::FromRow)]
+struct EmailDetailRow {
+    inbound_secret_encrypted: Option<Vec<u8>>,
+}
+
+#[derive(sqlx::FromRow)]
+struct EmailInboundRow {
+    app_id: Uuid,
+    script_id: Uuid,
+    enabled: bool,
+    dispatch_mode: String,
+    registered_by_principal: Uuid,
+    inbound_secret_encrypted: Option<Vec<u8>>,
+    inbound_secret_nonce: Option<Vec<u8>>,
+}
+
 #[derive(sqlx::FromRow)]
 #[allow(clippy::struct_field_names)]
 struct DlDetailRow {