feat: opt-in // debounce for asset-cascade subscribers (parser + schema)

Stage E1+E2. Parser: script-level // debounce <dur> + per-// on
debounce=<dur> override (edge wins, else script default, else none =
fan-out, unchanged); TriggerSpec::Asset carries the per-edge override;
split_trailing_kv_opts separates the ref from trailing key=val opts.
Schema/deploy: reversible migration adds script_trigger.debounce_s;
parse_duration_secs (bare int or <n>s|m|h|d, fail-safe on garbage)
resolves the effective per-edge window at deploy and writes it per row.
No reader yet (dispatch wiring is E3) so runtime is unchanged. New unit
tests for the parser directive and duration parsing.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

backend/windmill-api-scripts/src/scripts.rs

@@ -45,8 +45,8 @@ use windmill_common::{
     assets::{
         clear_script_triggers, clear_static_asset_usage, clear_static_asset_usage_by_script_hash,
         delete_managed_pipeline_schedule, insert_script_trigger, insert_static_asset_usage,
-        parse_pipeline_annotations, reconcile_pipeline_schedule, trigger_spec_to_row,
-        AssetUsageKind, AssetWithAltAccessType, TriggerSpec,
+        parse_duration_secs, parse_pipeline_annotations, reconcile_pipeline_schedule,
+        trigger_spec_to_row, AssetUsageKind, AssetWithAltAccessType, TriggerSpec,
     },
     error::{self, to_anyhow},
     min_version::{MIN_VERSION_SUPPORTS_DEBOUNCING, MIN_VERSION_SUPPORTS_DEBOUNCING_V2},
@@ -1242,6 +1242,9 @@ async fn create_script_internal<'c>(
     let in_pipeline = pipeline_annotations.in_pipeline;
     // `// trigger all` → AND join barrier (else OR, the default).
     let pipeline_join_all = !pipeline_annotations.join_mode.is_any();
+    // Script-level `// debounce <dur>` default; a per-`// on debounce=`
+    // overrides it (precedence resolved per edge below).
+    let pipeline_debounce_default = pipeline_annotations.debounce_default.clone();
     let pipeline_triggers = pipeline_annotations.triggers;
     let auto_kind = if in_pipeline {
         Some("pipeline".to_string())
@@ -1561,6 +1564,16 @@ async fn create_script_internal<'c>(
     clear_script_triggers(&mut *tx, &w_id, &ns.path, AssetUsageKind::Script).await?;
     for spec in &pipeline_triggers {
         let (trigger_kind, trigger_ref) = trigger_spec_to_row(spec);
+        // Effective debounce for this edge: per-`// on debounce=` wins,
+        // else the script-level `// debounce` default. Debounce only
+        // applies to asset-cascade edges; other trigger kinds get none.
+        let debounce_s = match spec {
+            TriggerSpec::Asset { debounce: Some(d), .. } => parse_duration_secs(d),
+            TriggerSpec::Asset { .. } => pipeline_debounce_default
+                .as_deref()
+                .and_then(parse_duration_secs),
+            _ => None,
+        };
         insert_script_trigger(
             &mut *tx,
             &w_id,
@@ -1569,6 +1582,7 @@ async fn create_script_internal<'c>(
             trigger_kind,
             &trigger_ref,
             pipeline_join_all,
+            debounce_s,
         )
         .await?;
     }