feat: expose fail_fast() on SubmitBuilder and DomainSubmitBuilder

docs/glossary.md

@@ -30,7 +30,7 @@ Quick reference for terms used throughout the taskmill documentation.
 | **Recurring task** | A task that automatically re-submits itself after each completion according to a `RecurringSchedule`. Recurring schedules survive restarts and support pause, resume, and cancel operations. See [Quick Start](quick-start.md#recurring-tasks). |
 | **Typed task** | A struct that implements the `TypedTask` trait, giving you compile-time type safety for task payloads and configuration. Declares `type Domain: DomainKey` for compile-time domain identity and `fn config() -> TaskTypeConfig` for static defaults (priority, IO budget, TTL, retry policy, etc.). Register with `Domain::task::<T>(executor)` and submit with `handle.submit(task)`. See [Quick Start](quick-start.md#typed-tasks). |
 | **TaskTypeConfig** | A struct returned by `TypedTask::config()` that holds static per-task-type defaults — priority, IO budget, group key, TTL, retry policy, duplicate strategy, etc. All fields are `Option`; `None` means "use the next layer's default" (domain default, then scheduler global, then built-in). |
-| **DomainSubmitBuilder** | The fluent builder returned by `DomainHandle::submit_with(task)`. Implements `IntoFuture` so bare `.await` applies all defaults; chain override methods (`.priority()`, `.run_after()`, `.parent()`, etc.) before `.await` to override individual fields for that call only. |
+| **DomainSubmitBuilder** | The fluent builder returned by `DomainHandle::submit_with(task)`. Implements `IntoFuture` so bare `.await` applies all defaults; chain override methods (`.priority()`, `.run_after()`, `.parent()`, `.fail_fast()`, etc.) before `.await` to override individual fields for that call only. |
 | **Domain-scoped state** | Application state registered on a `Domain` via `.state(value)`, visible only to executors within that domain. `TaskContext::state::<T>()` checks domain state first and falls back to global state registered on `SchedulerBuilder`. See [Configuration](configuration.md#application-state). |
 | **TypedEventStream** | A per-task-type event subscription (`TypedEventStream<T>`) created via `handle.task_events::<T>()`. Filters the global scheduler event broadcast to only events matching `T::TASK_TYPE` within the domain. Terminal events include the `TaskHistoryRecord`. |
 | **Qualified task type** | The full database-stored task type including the domain prefix, e.g. `"media::thumbnail"`. Required when using store-level query APIs (`history_stats`, `task_lookup`, `avg_throughput`). `DomainHandle` methods apply the prefix automatically, so you typically only need the short form when submitting tasks. |

docs/quick-start.md

@@ -294,7 +294,20 @@ ctx.domain::<Storage>()
     .await?;
 ```
 
-By default, if any child fails, its siblings are cancelled and the parent fails immediately (fail-fast). Disable this per-submission with `.fail_fast(false)`.
+By default, if any child fails, its siblings are cancelled and the parent fails immediately (fail-fast). Disable this per-submission with `.fail_fast(false)`:
+
+```rust
+// Typed builder
+media.submit_with(ScanTask { .. })
+    .fail_fast(false)
+    .await?;
+
+// Untyped
+scheduler.submit(
+    TaskSubmission::new("scan")
+        .fail_fast(false)
+).await?;
+```
 
 ## Sharing the scheduler
 

src/domain.rs

@@ -861,6 +861,15 @@ impl<D: DomainKey> DomainSubmitBuilder<D> {
         self
     }
 
+    /// Control whether a child failure immediately fails the parent.
+    ///
+    /// Defaults to `true`. Set to `false` to let the parent's `finalize()`
+    /// run even when some children fail.
+    pub fn fail_fast(mut self, fail_fast: bool) -> Self {
+        self.inner = self.inner.fail_fast(fail_fast);
+        self
+    }
+
     /// Set the parent task ID.
     pub fn parent(mut self, id: i64) -> Self {
         self.inner = self.inner.parent(id);

src/lib.rs

@@ -127,7 +127,9 @@
 //! [`TypedExecutor::finalize`] method is called — useful for assembly work
 //! like `CompleteMultipartUpload`. If any child fails and
 //! [`fail_fast`](TaskSubmission::fail_fast) is `true` (the default), siblings
-//! are cancelled and the parent fails immediately.
+//! are cancelled and the parent fails immediately. Disable this with
+//! [`DomainSubmitBuilder::fail_fast(false)`](DomainSubmitBuilder::fail_fast)
+//! (or [`TaskSubmission::fail_fast`] for untyped submissions).
 //!
 //! ## Task TTL & automatic expiry
 //!

src/task/submit_builder.rs

@@ -112,6 +112,7 @@ pub struct SubmitBuilder {
     override_on_dependency_failure: Option<DependencyFailurePolicy>,
     override_tags: HashMap<String, String>,
     override_parent_id: Option<i64>,
+    override_fail_fast: Option<bool>,
 }
 
 impl SubmitBuilder {
@@ -140,6 +141,7 @@ impl SubmitBuilder {
             override_on_dependency_failure: None,
             override_tags: HashMap::new(),
             override_parent_id: None,
+            override_fail_fast: None,
         }
     }
 
@@ -212,6 +214,15 @@ impl SubmitBuilder {
         self
     }
 
+    /// Control whether a child failure immediately fails the parent.
+    ///
+    /// Defaults to `true`. Set to `false` to let the parent's `finalize()`
+    /// run even when some children fail.
+    pub fn fail_fast(mut self, fail_fast: bool) -> Self {
+        self.override_fail_fast = Some(fail_fast);
+        self
+    }
+
     /// Set the parent task ID for hierarchical tasks (parent-child
     /// relationship). This does **not** establish a dependency — use
     /// [`depends_on`](Self::depends_on) for that.
@@ -349,6 +360,9 @@ impl SubmitBuilder {
         if let Some(pid) = self.override_parent_id.take() {
             self.submission.parent_id = Some(pid);
         }
+        if let Some(ff) = self.override_fail_fast.take() {
+            self.submission.fail_fast = ff;
+        }
     }
 
     /// Submit the task, returning the outcome.