crates/cm-api/src/quota.rs

@@ -13,6 +13,10 @@ use crate::{ApiError, AppState, Authed};
 pub struct Quota {
     pub max_agents: i64,
     pub max_live_containers: i64,
+    /// Ceiling on `queued` + `running` topology runs at once. Prevents one
+    /// workspace flooding the shared queue (a single team run also spawns a
+    /// tier-tree of children, so the practical cap grows with the topology).
+    pub max_active_runs: i64,
 }
 
 /// Per-plan limits. Unknown plans fall back to the free tier.
@@ -21,14 +25,17 @@ pub fn plan_quota(plan: &str) -> Quota {
         "team" => Quota {
             max_agents: 50,
             max_live_containers: 50,
+            max_active_runs: 100,
         },
         "pro" => Quota {
             max_agents: 20,
             max_live_containers: 20,
+            max_active_runs: 25,
         },
         _ => Quota {
             max_agents: 3,
             max_live_containers: 3,
+            max_active_runs: 5,
         },
     }
 }
@@ -61,6 +68,23 @@ pub async fn enforce_new_agent(
     Ok(())
 }
 
+/// Reject enqueueing another topology run if the workspace is at its plan cap.
+pub async fn enforce_new_run(
+    state: &AppState,
+    workspace_id: WorkspaceId,
+) -> Result<(), ApiError> {
+    let plan = plan_of(state, workspace_id).await?;
+    let quota = plan_quota(&plan);
+    let used = cm_db::repo::topology_runs::count_active(&state.pool, workspace_id).await?;
+    if used >= quota.max_active_runs {
+        return Err(ApiError::Quota(format!(
+            "active-run limit reached ({} on the {plan} plan) — wait for a run to finish or upgrade",
+            quota.max_active_runs
+        )));
+    }
+    Ok(())
+}
+
 /// Reject spinning up another container if the workspace is at its plan cap.
 pub async fn enforce_new_container(
     state: &AppState,
@@ -86,6 +110,8 @@ pub struct QuotaUsage {
     max_agents: i64,
     containers_used: i64,
     max_live_containers: i64,
+    active_runs: i64,
+    max_active_runs: i64,
 }
 
 /// `GET /api/quota` — the caller's workspace usage + limits (for the UI).
@@ -98,11 +124,15 @@ pub async fn get_quota(
     let agents_used = cm_db::repo::agents::count_active(&state.pool, user.workspace_id).await?;
     let containers_used =
         cm_db::repo::agent_containers::count_for_workspace(&state.pool, user.workspace_id).await?;
+    let active_runs =
+        cm_db::repo::topology_runs::count_active(&state.pool, user.workspace_id).await?;
     Ok(Json(QuotaUsage {
         plan,
         agents_used,
         max_agents: quota.max_agents,
         containers_used,
         max_live_containers: quota.max_live_containers,
+        active_runs,
+        max_active_runs: quota.max_active_runs,
     }))
 }

crates/cm-api/src/routes/companies.rs

@@ -266,6 +266,7 @@ pub async fn run_company(
     Json(body): Json<RunCompanyRequest>,
 ) -> Result<(StatusCode, Json<RunAccepted>), ApiError> {
     let company = cm_db::repo::companies::get(&state.pool, id, user.workspace_id).await?;
+    crate::quota::enforce_new_run(&state, user.workspace_id).await?;
     let run_id = Uuid::now_v7();
     cm_db::repo::topology_runs::enqueue_run_tier(
         &state.pool,

crates/cm-api/src/routes/orgs.rs

@@ -209,6 +209,7 @@ pub async fn run_org(
     Json(body): Json<RunOrgRequest>,
 ) -> Result<(StatusCode, Json<RunAccepted>), ApiError> {
     let org = cm_db::repo::orgs::get(&state.pool, id, user.workspace_id).await?;
+    crate::quota::enforce_new_run(&state, user.workspace_id).await?;
     let run_id = Uuid::now_v7();
     cm_db::repo::topology_runs::enqueue_run_tier(
         &state.pool,

crates/cm-api/src/routes/teams.rs

@@ -371,6 +371,7 @@ pub async fn run_team(
     Json(body): Json<RunTeamRequest>,
 ) -> Result<(StatusCode, Json<RunAccepted>), ApiError> {
     let team = cm_db::repo::teams::get_team(&state.pool, id, user.workspace_id).await?;
+    crate::quota::enforce_new_run(&state, user.workspace_id).await?;
     let run_id = Uuid::now_v7();
     cm_db::repo::topology_runs::enqueue_run(
         &state.pool,

crates/cm-api/src/routes/webhooks.rs

@@ -99,6 +99,12 @@ pub async fn trigger_hook(
         .filter(|t| !t.trim().is_empty())
         .or_else(|| (!default_task.trim().is_empty()).then_some(default_task))
         .unwrap_or_else(|| "webhook trigger".to_string());
+    // Webhooks are unauthenticated public endpoints — the enforce_new_run
+    // guard is what stops a leaked token from being weaponized into a queue
+    // flood. 429 (not 402) so external callers can back off.
+    if crate::quota::enforce_new_run(&state, ws).await.is_err() {
+        return StatusCode::TOO_MANY_REQUESTS;
+    }
     let run_id = Uuid::now_v7();
     if cm_db::repo::topology_runs::enqueue_run(&state.pool, run_id, ws, &task, &team.graph)
         .await