big bump

impl test_job_fail_want_mapping
impl test_schedulable_want_no_matching_job
2025-11-16 22:21:56 -08:00 · 2025-10-20 09:04:22 -07:00 · 2025-10-20 08:06:06 -07:00 · 2025-10-20 07:51:50 -07:00 · 2025-10-16 22:28:42 -07:00 · 2025-10-16 20:30:11 -07:00
20 changed files with 2351 additions and 515 deletions
--- a/MODULE.bazel
+++ b/MODULE.bazel
@ -3,15 +3,21 @@ module(
    version = "0.1",
 )

-bazel_dep(name = "bazel_skylib", version = "1.8.1")
-bazel_dep(name = "platforms", version = "0.0.11")
-bazel_dep(name = "rules_shell", version = "0.4.0")
+bazel_dep(name = "bazel_skylib", version = "1.8.2")
+bazel_dep(name = "platforms", version = "1.0.0")
+bazel_dep(name = "rules_shell", version = "0.6.1")
 bazel_dep(name = "rules_oci", version = "2.2.6")
 bazel_dep(name = "aspect_bazel_lib", version = "2.14.0")
-bazel_dep(name = "rules_rust", version = "0.61.0")
+bazel_dep(name = "rules_rust", version = "0.67.0")
 bazel_dep(name = "rules_proto", version = "7.0.2")
 bazel_dep(name = "protobuf", version = "29.0", repo_name = "com_google_protobuf")

+#rust = use_extension("@rules_rust//rust:extensions.bzl", "rust")
+#rust.toolchain(
+#    edition = "2024",
+#    versions = ["1.91.1"],
+#)
+
 crate = use_extension("@rules_rust//crate_universe:extensions.bzl", "crate")
 crate.spec(
    features = ["derive"],
--- a/MODULE.bazel.lock
+++ b/MODULE.bazel.lock
--- a/databuild/BUILD.bazel
+++ b/databuild/BUILD.bazel
@ -39,6 +39,8 @@ rust_library(
 rust_test(
    name = "databuild_test",
    crate = ":databuild",
+    data = ["//databuild/test:test_job_helper"],
+    env = {"RUST_BACKTRACE": "1"},
 )

 # Legacy filegroup for backwards compatibility
--- a/databuild/build_event_log.rs
+++ b/databuild/build_event_log.rs
@ -6,18 +6,18 @@ use std::error::Error;
 use std::fmt::Debug;
 use std::time::{SystemTime, UNIX_EPOCH};
 use crate::build_state::BuildState;
-use crate::util::current_timestamp;
+use crate::util::{current_timestamp, DatabuildError};

 pub trait BELStorage {
-    fn append_event(&mut self, event: &Event) -> Result<u64, Box<dyn Error>>;
+    fn append_event(&mut self, event: &Event) -> Result<u64, DatabuildError>;
    fn list_events(
        &self,
        since_idx: u64,
        limit: u64,
-    ) -> Result<Vec<DataBuildEvent>, Box<dyn Error>>;
+    ) -> Result<Vec<DataBuildEvent>, DatabuildError>;
 }

-#[derive(Debug)]
+#[derive(Debug, Clone)]
 pub struct MemoryBELStorage {
    pub events: Vec<DataBuildEvent>,
 }
@ -35,7 +35,7 @@ impl MemoryBELStorage {
 }

 impl BELStorage for MemoryBELStorage {
-    fn append_event(&mut self, event: &Event) -> Result<u64, Box<dyn Error>> {
+    fn append_event(&mut self, event: &Event) -> Result<u64, DatabuildError> {
        let timestamp = current_timestamp();
        let dbe = DataBuildEvent {
            timestamp,
@ -50,7 +50,7 @@ impl BELStorage for MemoryBELStorage {
        &self,
        since_idx: u64,
        limit: u64,
-    ) -> Result<Vec<DataBuildEvent>, Box<dyn Error>> {
+    ) -> Result<Vec<DataBuildEvent>, DatabuildError> {
        Ok(self
            .events
            .iter()
@ -67,7 +67,7 @@ struct SqliteBELStorage {
 }

 impl SqliteBELStorage {
-    fn create(database_url: &str) -> Result<SqliteBELStorage, Box<dyn Error>> {
+    fn create(database_url: &str) -> Result<SqliteBELStorage, DatabuildError> {
        let connection = Connection::open(database_url)?;

        // Create the events table
@ -85,7 +85,7 @@ impl SqliteBELStorage {
 }

 impl BELStorage for SqliteBELStorage {
-    fn append_event(&mut self, event: &Event) -> Result<u64, Box<dyn Error>> {
+    fn append_event(&mut self, event: &Event) -> Result<u64, DatabuildError> {
        let now = SystemTime::now();
        let duration_since_epoch = now.duration_since(UNIX_EPOCH).expect("Time went backwards");
        let timestamp = duration_since_epoch.as_nanos() as u64;
@ -113,7 +113,7 @@ impl BELStorage for SqliteBELStorage {
        &self,
        since_idx: u64,
        limit: u64,
-    ) -> Result<Vec<DataBuildEvent>, Box<dyn Error>> {
+    ) -> Result<Vec<DataBuildEvent>, DatabuildError> {
        let mut stmt = self.connection.prepare(
            "SELECT event_id, timestamp, event_data FROM events
             WHERE timestamp > ?1
@ -153,7 +153,7 @@ impl BELStorage for SqliteBELStorage {
    }
 }

-#[derive(Debug)]
+#[derive(Debug, Default)]
 pub struct BuildEventLog<S: BELStorage + Debug> {
    pub storage: S,
    pub state: BuildState,
@ -164,106 +164,108 @@ impl<S: BELStorage + Debug> BuildEventLog<S> {
        BuildEventLog { storage, state }
    }

-    pub fn append_event(&mut self, event: &Event) -> Result<u64, Box<dyn Error>> {
-        self.state.handle_event(&event);
+    pub fn append_event(&mut self, event: &Event) -> Result<u64, DatabuildError> {
+        self.state.handle_event(&event)?;
        let idx = self.storage.append_event(event)?;
        Ok(idx)
    }
+}

-    pub fn schedulable_wants(&self) -> Vec<WantDetail> {
-        todo!()
+impl Clone for BuildEventLog<MemoryBELStorage> {
+    fn clone(&self) -> Self {
+        Self {
+            storage: self.storage.clone(),
+            state: self.state.clone(),
+        }
    }
 }

 mod tests {
-    use uuid::Uuid;
-    use crate::build_event_log::{BELStorage, BuildEventLog, SqliteBELStorage};
-    use crate::data_build_event::Event;
-    use crate::{PartitionRef, WantCreateEventV1};
-    use crate::build_state::BuildState;
+    mod sqlite_bel_storage {
+        use uuid::Uuid;
+        use crate::build_event_log::{BELStorage, BuildEventLog, SqliteBELStorage};
+        use crate::data_build_event::Event;
+        use crate::{PartitionRef, WantCreateEventV1};
+        use crate::build_state::BuildState;

-    #[test]
-    fn test_hello() {
-        assert_eq!(2 + 3, 5);
-    }
+        #[test]
+        fn test_sqlite_append_event() {
+            let storage =
+                SqliteBELStorage::create(":memory:").expect("Failed to create SQLite storage");
+            let state = BuildState::default();
+            let mut log = BuildEventLog { storage, state };

-    #[test]
-    fn test_sqlite_append_event() {
-        let storage =
-            SqliteBELStorage::create(":memory:").expect("Failed to create SQLite storage");
-        let state = BuildState::default();
-        let mut log = BuildEventLog { storage, state };
+            let want_id = "sqlite_test_1234".to_string();

-        let want_id = "sqlite_test_1234".to_string();
+            // Initial state - verify storage is empty
+            let events = log
+                .storage
+                .list_events(0, 100)
+                .expect("Failed to list events");
+            assert_eq!(events.len(), 0);

-        // Initial state - verify storage is empty
-        let events = log
-            .storage
-            .list_events(0, 100)
-            .expect("Failed to list events");
-        assert_eq!(events.len(), 0);
+            // Verify want doesn't exist in state
+            assert!(log.state.get_want(&want_id).is_none());

-        // Verify want doesn't exist in state
-        assert!(log.state.get_want(&want_id).is_none());
+            // Append an event
+            let mut e = WantCreateEventV1::default();
+            e.want_id = want_id.clone();
+            e.partitions = vec!(PartitionRef { r#ref: "sqlite_partition_1234".to_string() });
+            let event_id = log
+                .append_event(&Event::WantCreateV1(e))
+                .expect("append_event failed");

-        // Append an event
-        let mut e = WantCreateEventV1::default();
-        e.want_id = want_id.clone();
-        e.partitions = vec!(PartitionRef { r#ref: "sqlite_partition_1234".to_string() });
-        let event_id = log
-            .append_event(&Event::WantCreateV1(e))
-            .expect("append_event failed");
+            // Verify event was stored
+            assert!(event_id > 0);

-        // Verify event was stored
-        assert!(event_id > 0);
+            // Verify event can be retrieved
+            let events = log
+                .storage
+                .list_events(0, 100)
+                .expect("Failed to list events");
+            assert_eq!(events.len(), 1);

-        // Verify event can be retrieved
-        let events = log
-            .storage
-            .list_events(0, 100)
-            .expect("Failed to list events");
-        assert_eq!(events.len(), 1);
+            let stored_event = &events[0];
+            assert_eq!(stored_event.event_id, event_id);
+            assert!(stored_event.timestamp > 0);

-        let stored_event = &events[0];
-        assert_eq!(stored_event.event_id, event_id);
-        assert!(stored_event.timestamp > 0);
+            // Verify the event content
+            if let Some(Event::WantCreateV1(want_event)) = &stored_event.event {
+                assert_eq!(want_event.want_id, want_id);
+                assert_eq!(want_event.partitions.len(), 1);
+                assert_eq!(want_event.partitions[0].r#ref, "sqlite_partition_1234");
+            } else {
+                panic!("Expected WantCreateV1 event, got {:?}", stored_event.event);
+            }

-        // Verify the event content
-        if let Some(Event::WantCreateV1(want_event)) = &stored_event.event {
-            assert_eq!(want_event.want_id, want_id);
-            assert_eq!(want_event.partitions.len(), 1);
-            assert_eq!(want_event.partitions[0].r#ref, "sqlite_partition_1234");
-        } else {
-            panic!("Expected WantCreateV1 event, got {:?}", stored_event.event);
+            // Verify state was updated
+            assert!(
+                log.state.get_want(&want_id).is_some(),
+                "want_id not found in state"
+            );
+            assert_eq!(
+                log.state.get_want(&want_id)
+                    .map(|want| want.want_id.clone())
+                    .expect("state.wants want_id not found"),
+                want_id,
+                "want_id not equal in state",
+            );
+
+            let mut e2 = WantCreateEventV1::default();
+            e2.want_id = Uuid::new_v4().into();
+            log.append_event(&Event::WantCreateV1(e2)).expect("append_event failed");
+            let mut e3 = WantCreateEventV1::default();
+            e3.want_id = Uuid::new_v4().into();
+            log.append_event(&Event::WantCreateV1(e3)).expect("append_event failed");
+            let mut e4 = WantCreateEventV1::default();
+            e4.want_id = Uuid::new_v4().into();
+            log.append_event(&Event::WantCreateV1(e4)).expect("append_event failed");
+
+            let events = log
+                .storage
+                .list_events(0, 100)
+                .expect("Failed to list events");
+            assert_eq!(events.len(), 4);
        }
-
-        // Verify state was updated
-        assert!(
-            log.state.get_want(&want_id).is_some(),
-            "want_id not found in state"
-        );
-        assert_eq!(
-            log.state.get_want(&want_id)
-                .map(|want| want.want_id.clone())
-                .expect("state.wants want_id not found"),
-            want_id,
-            "want_id not equal in state",
-        );
-
-        let mut e2 = WantCreateEventV1::default();
-        e2.want_id = Uuid::new_v4().into();
-        log.append_event(&Event::WantCreateV1(e2)).expect("append_event failed");
-        let mut e3 = WantCreateEventV1::default();
-        e3.want_id = Uuid::new_v4().into();
-        log.append_event(&Event::WantCreateV1(e3)).expect("append_event failed");
-        let mut e4 = WantCreateEventV1::default();
-        e4.want_id = Uuid::new_v4().into();
-        log.append_event(&Event::WantCreateV1(e4)).expect("append_event failed");
-
-        let events = log
-            .storage
-            .list_events(0, 100)
-            .expect("Failed to list events");
-        assert_eq!(events.len(), 4);
    }
 }
--- a/databuild/build_state.rs
+++ b/databuild/build_state.rs
@ -1,13 +1,44 @@
 use crate::data_build_event::Event;
-use crate::util::current_timestamp;
-use crate::{JobRunDetail, ListJobRunsRequest, ListJobRunsResponse, ListPartitionsRequest, ListPartitionsResponse, ListTaintsRequest, ListTaintsResponse, ListWantsRequest, ListWantsResponse, PartitionDetail, TaintDetail, WantCancelEventV1, WantCreateEventV1, WantDetail, WantStatusCode};
-use rusqlite::types::{FromSql, FromSqlResult, ToSqlOutput, ValueRef};
-use rusqlite::{Connection, ToSql};
+use crate::data_deps::{missing_deps_to_want_events, WantTimestamps};
+use crate::job_run::{DepMissJobRun, SubProcessBackend};
+use crate::util::{current_timestamp, DatabuildError};
+use crate::{
+    JobRunBufferEventV1, JobRunCancelEventV1, JobRunDetail, JobRunFailureEventV1,
+    JobRunHeartbeatEventV1, JobRunMissingDepsEventV1,
+    JobRunStatusCode, JobRunSuccessEventV1, ListJobRunsRequest, ListJobRunsResponse,
+    ListPartitionsRequest, ListPartitionsResponse, ListTaintsRequest, ListTaintsResponse,
+    ListWantsRequest, ListWantsResponse, PartitionDetail, PartitionRef, PartitionStatusCode,
+    TaintCreateEventV1, TaintDeleteEventV1, TaintDetail, WantCancelEventV1, WantCreateEventV1,
+    WantDetail, WantStatusCode,
+};
+use rusqlite::types::FromSql;
+use rusqlite::ToSql;
 use serde::{Deserialize, Serialize};
 use std::collections::BTreeMap;
 use std::error::Error;

-#[derive(Debug)]
+/**
+Design Notes
+
+The build state struct is the heart of the service and orchestrator, adapting build events to
+higher level questions about build state. One temptation is to implement the build state as a set
+of hierarchically defined reducers, to achieve information hiding and factor system capabilities and
+state tracking simply. Unfortunately, to update state based on an event, you need a mutable borrow
+of some part of the build state (that the reducer controls, for instance), and an immutable borrow
+of the whole state for read/query purposes. The whole state needs to be available to handle state
+updates like "this is the list of currently active job runs" in response to a job run event. Put
+simply, this isn't possible without introducing some locking of the whole state and mutable state
+subset, since they would conflict (the mutable subset would have already been borrowed, so can't
+be borrowed immutably as part of the whole state borrow). You might also define a "query" phase
+in which reducers query the state based on the received event, but that just increases complexity.
+
+Instead, databuild opts for an entity-component system (ECS) that just provides the whole build
+state mutably to all state update functionality, trusting that we know how to use it responsibly.
+This means no boxing or "query phase", and means we can have all state updates happen as map lookups
+and updates, which is exceptionally fast.
+*/
+
+#[derive(Debug, Clone)]
 pub struct BuildState {
    wants: BTreeMap<String, WantDetail>,
    taints: BTreeMap<String, TaintDetail>,
@ -27,22 +58,210 @@ impl Default for BuildState {
 }

 impl BuildState {
+    pub fn count_job_runs(&self) -> usize {
+        self.job_runs.len()
+    }

-    pub fn handle_event(&mut self, event: &Event) -> () {
+    /// Handles reacting to events, updating state, and erroring if its an invalid state transition
+    pub fn handle_event(&mut self, event: &Event) -> Result<(), DatabuildError> {
        match event {
-            Event::WantCreateV1(e) => {
-                self.wants.insert(e.want_id.clone(), e.clone().into());
-            }
-            Event::WantCancelV1(e) => {
-                if let Some(want) = self.wants.get_mut(&e.want_id) {
-                    want.status = Some(WantStatusCode::WantCanceled.into());
-                    want.last_updated_timestamp = current_timestamp();
+            // JobRun events
+            Event::JobRunBufferV1(e) => self.handle_job_run_buffer(e),
+            Event::JobRunHeartbeatV1(e) => self.handle_job_run_heartbeat(e),
+            Event::JobRunFailureV1(e) => self.handle_job_run_failure(e),
+            Event::JobRunCancelV1(e) => self.handle_job_run_cancel(e),
+            Event::JobRunSuccessV1(e) => self.handle_job_run_success(e),
+            Event::JobRunMissingDepsV1(e) => self.handle_job_run_dep_miss(e),
+            // Want events
+            Event::WantCreateV1(e) => self.handle_want_create(e),
+            Event::WantCancelV1(e) => self.handle_want_cancel(e),
+            // Taint events
+            Event::TaintCreateV1(e) => self.handle_taint_create(e),
+            Event::TaintDeleteV1(e) => self.handle_taint_delete(e),
+            // Ruh roh!
+            _ => panic!("Unhandled event type! {:?}", event),
+        }
+    }
+
+    fn handle_want_create(&mut self, event: &WantCreateEventV1) -> Result<(), DatabuildError> {
+        self.wants
+            .insert(event.want_id.clone(), event.clone().into());
+        Ok(())
+    }
+
+    fn handle_want_cancel(&mut self, event: &WantCancelEventV1) -> Result<(), DatabuildError> {
+        if let Some(want) = self.wants.get_mut(&event.want_id) {
+            want.status = Some(WantStatusCode::WantCanceled.into());
+            want.last_updated_timestamp = current_timestamp();
+        }
+        Ok(())
+    }
+
+    fn handle_job_run_buffer(&mut self, event: &JobRunBufferEventV1) -> Result<(), DatabuildError> {
+        // No job run should exist
+        if self.job_runs.get(&event.job_run_id).is_some() {
+            Err(format!("Job run ID collision on job run ID {}", event.job_run_id).into())
+        } else {
+            // Create job run to be inserted
+            let job_run: JobRunDetail = event.clone().into();
+
+            for pref in job_run.building_partitions.iter() {
+                // Update all wants that point to this partition ref to `Building`
+                // Query notes: "update all wants that point to this partition to building"
+                if let Some(want) = self.wants.get_mut(&pref.r#ref) {
+                    want.status = Some(WantStatusCode::WantBuilding.into());
                }
            }
-            _ => (),
+
+            self.job_runs.insert(event.job_run_id.clone(), job_run.clone());
+            println!("Inserted job run: {:?}", job_run);
+            Ok(())
        }
    }

+    fn update_job_run_status(
+        &mut self,
+        job_run_id: &str,
+        status: JobRunStatusCode,
+    ) -> Result<(), DatabuildError> {
+        if let Some(job_run) = self.job_runs.get_mut(job_run_id) {
+            job_run.last_heartbeat_at = Some(current_timestamp());
+            job_run.status = Some(status.into());
+            Ok(())
+        } else {
+            Err(format!("Job run ID {} not found", job_run_id).into())
+        }
+    }
+
+    fn update_partition_status(
+        &mut self,
+        pref: &PartitionRef,
+        status: PartitionStatusCode,
+        job_run_id: Option<&str>,
+    ) -> Result<(), DatabuildError> {
+        if let Some(partition) = self.partitions.get_mut(&pref.r#ref) {
+            partition.status = Some(status.clone().into());
+            partition.last_updated_timestamp = Some(current_timestamp());
+            if let Some(job_run_id) = job_run_id.map(str::to_string) {
+                if !partition.job_run_ids.contains(&job_run_id) {
+                    partition.job_run_ids.push(job_run_id);
+                }
+            }
+        } else {
+            // Partition doesn't exist yet, needs to be inserted
+            let want_ids = if let Some(jrid) = job_run_id {
+                let job_run = self.get_job_run(jrid).expect("Job run must exist for partition");
+                job_run.servicing_wants.iter().map(|wap| wap.want_id.clone()).collect()
+            } else {
+                vec![]
+            };
+
+            let partition = PartitionDetail {
+                r#ref: Some(pref.clone()),
+                status: Some(status.into()),
+                last_updated_timestamp: Some(current_timestamp()),
+                job_run_ids: job_run_id.map(|jrid| vec![jrid.to_string()]).unwrap_or(vec![]),
+                want_ids,
+                ..PartitionDetail::default()
+            };
+            self.partitions.insert(pref.r#ref.clone(), partition);
+        };
+
+        self.update_wants_for_partition(&pref)
+    }
+
+    /// Walks the state from this want ID to update its status.
+    fn update_want_status(&mut self, want_id: &str) -> Result<(), DatabuildError> {
+        if let Some(want) = self.wants.get(want_id) {
+            let details: Vec<Option<PartitionDetail>> = want
+                .upstreams
+                .iter()
+                .map(|pref| self.get_partition(&pref.r#ref))
+                .collect();
+            let status: WantStatusCode = details.into();
+            if let Some(mut_want) = self.wants.get_mut(want_id) {
+                mut_want.status = Some(status.into());
+                mut_want.last_updated_timestamp = current_timestamp();
+            }
+            Ok(())
+        } else {
+            Err(format!("Want id {} not found", want_id).into())
+        }
+    }
+
+    fn handle_job_run_heartbeat(
+        &mut self,
+        event: &JobRunHeartbeatEventV1,
+    ) -> Result<(), DatabuildError> {
+        self.update_job_run_status(&event.job_run_id, JobRunStatusCode::JobRunRunning)
+    }
+
+    fn handle_job_run_success(
+        &mut self,
+        event: &JobRunSuccessEventV1,
+    ) -> Result<(), DatabuildError> {
+        println!("Job run success event: {:?}", event);
+        self.update_job_run_status(&event.job_run_id, JobRunStatusCode::JobRunSucceeded)?;
+        let job_run = self.get_job_run(&event.job_run_id).unwrap();
+        // Update partitions being build by this job
+        for pref in job_run.building_partitions {
+            self.update_partition_status(&pref, PartitionStatusCode::PartitionLive, Some(&event.job_run_id))?;
+        }
+        Ok(())
+    }
+
+    fn update_wants_for_partition(&mut self, pref: &PartitionRef) -> Result<(), DatabuildError> {
+        // todo!("Go to every want that references this partition and update its status")
+        let want_ids = self
+            .partitions
+            .get(&pref.r#ref)
+            .map(|p| p.want_ids.clone())
+            .ok_or(format!("Partition for ref {} not found", pref.r#ref))?;
+        for want_id in want_ids.iter() {
+            self.update_want_status(want_id)?;
+        }
+        Ok(())
+    }
+
+    fn handle_job_run_failure(
+        &mut self,
+        event: &JobRunFailureEventV1,
+    ) -> Result<(), DatabuildError> {
+        self.update_job_run_status(&event.job_run_id, JobRunStatusCode::JobRunFailed)?;
+        let job_run = self.get_job_run(&event.job_run_id).unwrap();
+        for pref in job_run.building_partitions {
+            self.update_partition_status(&pref, PartitionStatusCode::PartitionFailed, Some(&event.job_run_id))?;
+        }
+        Ok(())
+    }
+
+    fn handle_job_run_cancel(&mut self, event: &JobRunCancelEventV1) -> Result<(), DatabuildError> {
+        todo!("should update already inserted job run, partition status, want status")
+    }
+
+    fn handle_job_run_dep_miss(
+        &mut self,
+        event: &JobRunMissingDepsEventV1,
+    ) -> Result<(), DatabuildError> {
+        todo!("should update already inserted job run, schedule wants...?")
+    }
+
+    fn handle_taint_create(&mut self, event: &TaintCreateEventV1) -> Result<(), DatabuildError> {
+        todo!("...?")
+    }
+
+    fn handle_taint_delete(&mut self, event: &TaintDeleteEventV1) -> Result<(), DatabuildError> {
+        todo!("...?")
+    }
+
+    fn with_wants(self, wants: BTreeMap<String, WantDetail>) -> Self {
+        Self { wants, ..self }
+    }
+
+    fn with_partitions(self, partitions: BTreeMap<String, PartitionDetail>) -> Self {
+        Self { partitions, ..self }
+    }
+
    pub fn get_want(&self, want_id: &str) -> Option<WantDetail> {
        self.wants.get(want_id).cloned()
    }
@ -99,13 +318,133 @@ impl BuildState {
            page_size,
        }
    }
+
+    /**
+    Wants are schedulable when their partition is live and not tainted
+    */
+    pub fn want_schedulability(&self, want: &WantDetail) -> WantSchedulability {
+        let live_details: Vec<&PartitionDetail> = want
+            .upstreams
+            .iter()
+            .map(|pref| self.partitions.get(&pref.r#ref))
+            .flatten()
+            .collect();
+        let live: Vec<PartitionRef> = live_details
+            .iter()
+            .map(|pd| pd.r#ref.clone().expect("pref must have ref"))
+            .collect();
+        let missing: Vec<PartitionRef> = want
+            .upstreams
+            .iter()
+            .filter(|pref| self.partitions.get(&pref.r#ref).is_none())
+            .cloned()
+            .collect();
+        let tainted: Vec<PartitionRef> = live_details
+            .iter()
+            .filter(|p| p.status == Some(PartitionStatusCode::PartitionTainted.into()))
+            .map(|pref| pref.r#ref.clone().unwrap())
+            .collect();
+        WantSchedulability {
+            want: want.clone(),
+            status: WantUpstreamStatus {
+                live,
+                tainted,
+                missing,
+            },
+        }
+    }
+
+    pub fn schedulable_wants(&self) -> WantsSchedulability {
+        WantsSchedulability(
+            self.wants
+                .values()
+                // Do not consider fulfilled or currently building wants in schedulability query
+                .filter(|w| {
+                    w.status.clone().expect("want must have status").code
+                        != WantStatusCode::WantSuccessful as i32
+                })
+                .filter(|w| {
+                    w.status.clone().expect("want must have status").code
+                        != WantStatusCode::WantBuilding as i32
+                })
+                .cloned()
+                .map(|w| self.want_schedulability(&w))
+                .collect(),
+        )
+    }
+
+    /// Maps a dep miss into the BEL events it implies, so that the job can be run successfully later
+    pub fn dep_miss_to_events(
+        &self,
+        dep_miss: &DepMissJobRun<SubProcessBackend>,
+    ) -> Result<Vec<Event>, DatabuildError> {
+        let mut events = vec![];
+        // Append literal job run dep miss
+        events.push(dep_miss.state.to_event(&dep_miss.id()));
+        // Append wants from dep miss
+        let job_run_detail = self
+            .get_job_run(&dep_miss.job_run_id.to_string())
+            .ok_or(format!(
+                "Unable to find job run with id `{}`",
+                dep_miss.job_run_id
+            ))?;
+        // Infer data/SLA timestamps from upstream want
+        let want_timestamps: WantTimestamps = job_run_detail
+            .servicing_wants
+            .iter()
+            .flat_map(|wap| self.get_want(&wap.want_id).map(|w| w.into()))
+            .reduce(|a: WantTimestamps, b: WantTimestamps| a.merge(b))
+            .ok_or(format!("No servicing wants found"))?;
+        // Create wants from dep misses
+        let want_events = missing_deps_to_want_events(
+            dep_miss.state.missing_deps.clone(),
+            &dep_miss.job_run_id,
+            want_timestamps,
+        );
+        events.extend(want_events);
+
+        Ok(events)
+    }
+}
+
+/// The status of partitions required by a want to build (sensed from dep miss job run)
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct WantUpstreamStatus {
+    pub live: Vec<PartitionRef>,
+    pub tainted: Vec<PartitionRef>,
+    pub missing: Vec<PartitionRef>,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct WantSchedulability {
+    pub want: WantDetail,
+    pub status: WantUpstreamStatus,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize, Default)]
+pub struct WantsSchedulability(pub Vec<WantSchedulability>);
+
+impl Into<bool> for WantsSchedulability {
+    fn into(self) -> bool {
+        self.0.iter().all(|w| w.is_schedulable())
+    }
+}
+
+impl WantSchedulability {
+    pub fn is_schedulable(&self) -> bool {
+        self.status.missing.is_empty() && self.status.tainted.is_empty()
+    }
 }

 fn list_state_items<T: Clone>(map: &BTreeMap<String, T>, page: u64, page_size: u64) -> Vec<T> {
    // TODO when we add filtering, can we add it generically via some trait or filter object that can be provided?
    let start = page * page_size;
    let end = start + page_size;
-    map.values().skip(start as usize).take(end as usize).cloned().collect()
+    map.values()
+        .skip(start as usize)
+        .take(end as usize)
+        .cloned()
+        .collect()
 }

 mod consts {
@ -114,6 +453,106 @@ mod consts {

 #[cfg(test)]
 mod tests {
+    mod schedulable_wants {
+        use crate::build_state::BuildState;
+        use crate::{
+            PartitionDetail, PartitionRef, PartitionStatus, PartitionStatusCode, WantDetail,
+            WantStatus, WantStatusCode,
+        };
+        use std::collections::BTreeMap;
+
+        impl WantDetail {
+            fn with_partitions(self, partitions: Vec<PartitionRef>) -> Self {
+                Self { partitions, ..self }
+            }
+            fn with_upstreams(self, upstreams: Vec<PartitionRef>) -> Self {
+                Self { upstreams, ..self }
+            }
+            fn with_status(self, status: Option<WantStatus>) -> Self {
+                Self { status, ..self }
+            }
+        }
+
+        impl PartitionDetail {
+            fn with_status(self, status: Option<PartitionStatus>) -> Self {
+                Self { status, ..self }
+            }
+            fn with_ref(self, r#ref: Option<PartitionRef>) -> Self {
+                Self { r#ref, ..self }
+            }
+        }
+
+        #[test]
+        fn test_empty_wants_noop() {
+            assert_eq!(BuildState::default().schedulable_wants().0.len(), 0);
+        }
+
+        // A want with satisfied upstreams (incl "none") should be schedulable
+        #[test]
+        fn test_simple_want_with_live_upstream_is_schedulable() {
+            // Given...
+            let test_partition = "test_partition";
+            let state = BuildState::default()
+                .with_wants(BTreeMap::from([(
+                    "foo".to_string(),
+                    WantDetail::default()
+                        .with_partitions(vec![test_partition.into()])
+                        .with_status(Some(WantStatusCode::WantIdle.into())),
+                )]))
+                .with_partitions(BTreeMap::from([(
+                    test_partition.to_string(),
+                    PartitionDetail::default().with_ref(Some(test_partition.into())),
+                )]));
+
+            // Should...
+            let schedulability = state.schedulable_wants();
+            let ws = schedulability.0.first().unwrap();
+            assert!(ws.is_schedulable());
+        }
+
+        #[test]
+        fn test_simple_want_without_live_upstream_is_not_schedulable() {
+            // Given...
+            let test_partition = "test_partition";
+            let state = BuildState::default().with_wants(BTreeMap::from([(
+                test_partition.to_string(),
+                WantDetail::default()
+                    .with_upstreams(vec![test_partition.into()])
+                    .with_status(Some(WantStatusCode::WantIdle.into())),
+            )]));
+
+            // Should...
+            let schedulability = state.schedulable_wants();
+            let ws = schedulability.0.first().unwrap();
+            assert!(!ws.is_schedulable());
+        }
+
+        #[test]
+        #[ignore]
+        fn test_simple_want_with_tainted_upstream_is_not_schedulable() {
+            // Given...
+            let test_partition = "test_partition";
+            let state = BuildState::default()
+                .with_wants(BTreeMap::from([(
+                    "foo".to_string(),
+                    WantDetail::default()
+                        .with_partitions(vec![test_partition.into()])
+                        .with_status(Some(WantStatusCode::WantIdle.into())),
+                )]))
+                .with_partitions(BTreeMap::from([(
+                    test_partition.to_string(),
+                    PartitionDetail::default()
+                        .with_ref(Some(test_partition.into()))
+                        .with_status(Some(PartitionStatusCode::PartitionTainted.into())),
+                )]));
+
+            // Should...
+            let schedulability = state.schedulable_wants();
+            let ws = schedulability.0.first().unwrap();
+            assert!(ws.is_schedulable());
+        }
+    }
+
    mod sqlite_build_state {
        mod want {
            use crate::build_state::BuildState;
--- a/databuild/data_deps.rs
+++ b/databuild/data_deps.rs
@ -0,0 +1,243 @@
+use crate::data_build_event::Event;
+use crate::{
+    JobRunMissingDeps, JobRunReadDeps, JobTriggeredEvent, MissingDeps, ReadDeps, WantCreateEventV1,
+    WantDetail,
+};
+use uuid::Uuid;
+
+// TODO - how do we version this?
+pub const DATABUILD_MISSING_DEPS_JSON: &str = "DATABUILD_MISSING_DEPS_JSON:";
+pub const DATABUILD_DEP_READ_JSON: &str = "DATABUILD_DEP_READ_JSON:";
+
+pub enum DataDepLogLine {
+    DepMiss(JobRunMissingDeps),
+    DepRead(JobRunReadDeps),
+}
+
+impl From<DataDepLogLine> for String {
+    fn from(value: DataDepLogLine) -> Self {
+        match value {
+            DataDepLogLine::DepMiss(dm) => {
+                format!(
+                    "{}{}",
+                    DATABUILD_MISSING_DEPS_JSON,
+                    serde_json::to_string(&dm).expect("json serialize")
+                )
+            }
+            DataDepLogLine::DepRead(dr) => {
+                format!(
+                    "{}{}",
+                    DATABUILD_DEP_READ_JSON,
+                    serde_json::to_string(&dr).expect("json serialize")
+                )
+            }
+        }
+    }
+}
+
+#[derive(Default, Debug)]
+pub struct JobRunDataDepResults {
+    pub reads: Vec<ReadDeps>,
+    pub misses: Vec<MissingDeps>,
+}
+
+impl JobRunDataDepResults {
+    pub fn with(mut self, dep_log_line: DataDepLogLine) -> Self {
+        match dep_log_line {
+            DataDepLogLine::DepMiss(dm) => self.misses.extend(dm.missing_deps),
+            DataDepLogLine::DepRead(rd) => self.reads.extend(rd.read_deps),
+        }
+        self
+    }
+
+    pub fn with_lines(mut self, lines: Vec<String>) -> Self {
+        lines
+            .iter()
+            .flat_map(|line| parse_log_line(line))
+            .fold(self, |agg, it| agg.with(it))
+    }
+}
+
+impl Into<JobRunDataDepResults> for Vec<String> {
+    fn into(self) -> JobRunDataDepResults {
+        JobRunDataDepResults::default().with_lines(self)
+    }
+}
+
+pub fn parse_log_line(line: &str) -> Option<DataDepLogLine> {
+    if let Some(message) = line_matches(line, DATABUILD_MISSING_DEPS_JSON) {
+        serde_json::from_str(message)
+            .ok()
+            .map(|dm| DataDepLogLine::DepMiss(dm))
+    } else if let Some(message) = line_matches(line, DATABUILD_DEP_READ_JSON) {
+        serde_json::from_str(message)
+            .ok()
+            .map(|dm| DataDepLogLine::DepRead(dm))
+    } else {
+        None
+    }
+}
+
+fn line_matches<'a>(line: &'a str, prefix: &'a str) -> Option<&'a str> {
+    line.trim().strip_prefix(prefix)
+}
+
+pub struct WantTimestamps {
+    data_timestamp: u64,
+    ttl_seconds: u64,
+    sla_seconds: u64,
+}
+
+impl From<WantDetail> for WantTimestamps {
+    fn from(want_detail: WantDetail) -> Self {
+        WantTimestamps {
+            data_timestamp: want_detail.data_timestamp,
+            ttl_seconds: want_detail.ttl_seconds,
+            sla_seconds: want_detail.sla_seconds,
+        }
+    }
+}
+
+impl WantTimestamps {
+    pub fn merge(self, other: WantTimestamps) -> WantTimestamps {
+        // TODO does this make sense?
+        WantTimestamps {
+            data_timestamp: self.data_timestamp.min(other.data_timestamp),
+            ttl_seconds: self.ttl_seconds.max(other.ttl_seconds),
+            sla_seconds: self.sla_seconds.max(other.sla_seconds),
+        }
+    }
+}
+
+pub fn missing_deps_to_want_events(
+    missing_deps: Vec<MissingDeps>,
+    job_run_id: &Uuid,
+    want_timestamps: WantTimestamps,
+) -> Vec<Event> {
+    missing_deps
+        .iter()
+        .map(|md| {
+            Event::WantCreateV1(WantCreateEventV1 {
+                want_id: Uuid::new_v4().into(),
+                partitions: md.missing.clone(),
+                data_timestamp: want_timestamps.data_timestamp,
+                ttl_seconds: want_timestamps.ttl_seconds,
+                sla_seconds: want_timestamps.sla_seconds,
+                source: Some(
+                    JobTriggeredEvent {
+                        job_run_id: job_run_id.to_string(),
+                    }
+                    .into(),
+                ),
+                comment: Some("Missing data".to_string()),
+            })
+        })
+        .collect()
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_missing_deps_with_1_to_1_and_1_to_n() {
+        let log_line = r#"DATABUILD_MISSING_DEPS_JSON:{"version":"1","missing_deps":[{"impacted":[{"ref":"output/p1"}],"missing":[{"ref":"input/p1"}]},{"impacted":[{"ref":"output/p2"},{"ref":"output/p3"}],"missing":[{"ref":"input/p2"}]}]}"#.to_string();
+
+        let result = parse_log_line(&log_line);
+        assert!(result.is_some());
+
+        let missing_deps = match result.unwrap() {
+            DataDepLogLine::DepMiss(md) => md,
+            _ => panic!("expected dep miss log line"),
+        };
+        assert_eq!(missing_deps.missing_deps.len(), 2);
+
+        // First entry: 1:1 (one missing input -> one impacted output)
+        assert_eq!(missing_deps.missing_deps[0].impacted.len(), 1);
+        assert_eq!(missing_deps.missing_deps[0].impacted[0].r#ref, "output/p1");
+        assert_eq!(missing_deps.missing_deps[0].missing.len(), 1);
+        assert_eq!(missing_deps.missing_deps[0].missing[0].r#ref, "input/p1");
+
+        // Second entry: 1:N (one missing input -> multiple impacted outputs)
+        assert_eq!(missing_deps.missing_deps[1].impacted.len(), 2);
+        assert_eq!(missing_deps.missing_deps[1].impacted[0].r#ref, "output/p2");
+        assert_eq!(missing_deps.missing_deps[1].impacted[1].r#ref, "output/p3");
+        assert_eq!(missing_deps.missing_deps[1].missing.len(), 1);
+        assert_eq!(missing_deps.missing_deps[1].missing[0].r#ref, "input/p2");
+    }
+
+    /// We can accumulate dep miss and read events
+    #[test]
+    fn test_accumulate_dep_parse_and_miss() {
+        // Given
+        let r = JobRunDataDepResults::default();
+        assert_eq!(r.misses.len(), 0);
+        assert_eq!(r.reads.len(), 0);
+
+        // When
+        let r = r
+            .with(DataDepLogLine::DepRead(JobRunReadDeps {
+                version: "1".into(),
+                read_deps: vec![ReadDeps {
+                    impacted: vec!["output/p1".into()],
+                    read: vec!["input/p1".into()],
+                }],
+            }))
+            .with(DataDepLogLine::DepRead(JobRunReadDeps {
+                version: "1".into(),
+                read_deps: vec![ReadDeps {
+                    impacted: vec!["output/p2".into()],
+                    read: vec!["input/p2".into(), "input/p2".into()],
+                }],
+            }))
+            .with(DataDepLogLine::DepMiss(JobRunMissingDeps {
+                version: "1".into(),
+                missing_deps: vec![MissingDeps {
+                    impacted: vec!["output/p3".into()],
+                    missing: vec!["input/p3".into()],
+                }],
+            }));
+    }
+
+    /// It's acceptable to print separately for each missing dep
+    #[test]
+    fn test_parse_multiple_missing_deps() {
+        // Given
+        let r = JobRunDataDepResults::default();
+        let stdout_lines: Vec<String> = vec![
+            "something".into(),
+            DataDepLogLine::DepRead(JobRunReadDeps {
+                version: "1".into(),
+                read_deps: vec![ReadDeps {
+                    impacted: vec!["output/p1".into()],
+                    read: vec!["input/p1".into()],
+                }],
+            })
+            .into(),
+            DataDepLogLine::DepRead(JobRunReadDeps {
+                version: "1".into(),
+                read_deps: vec![ReadDeps {
+                    impacted: vec!["output/p2".into()],
+                    read: vec!["input/p2".into()],
+                }],
+            })
+            .into(),
+            "something else".into(),
+            DataDepLogLine::DepMiss(JobRunMissingDeps {
+                version: "1".into(),
+                missing_deps: vec![MissingDeps {
+                    impacted: vec!["output/p3".into()],
+                    missing: vec!["input/p3".into()],
+                }],
+            })
+            .into(),
+        ];
+
+        // When
+        let results = r.with_lines(stdout_lines);
+
+        // Should
+        assert_eq!(results.misses.len(), 1);
+        assert_eq!(results.reads.len(), 2);
+    }
+}
--- a/databuild/databuild.proto
+++ b/databuild/databuild.proto
@ -53,7 +53,8 @@ message WantAttributedPartitions {
 message JobRunBufferEventV1 {
  string job_run_id = 1;
  string job_label = 2;
-  repeated WantAttributedPartitions want_attributed_partitions = 3;
+  repeated PartitionRef building_partitions = 3;
+  repeated WantAttributedPartitions want_attributed_partitions = 4;
  // TODO how do we handle buffer definition? Start simple, noop until we want something here?
 }
 // Just indicates that job has entered queue
@ -73,6 +74,7 @@ message JobRunSuccessEventV1 {
 // Simply indicates that the job has failed. Depending on retry logic defined in job, it may retry.
 message JobRunFailureEventV1 {
  string job_run_id = 1;
+  string reason = 2;
 }
 // Job was explicitly canceled.
 message JobRunCancelEventV1 {
@ -84,12 +86,30 @@ message JobRunCancelEventV1 {
 message JobRunMissingDepsEventV1 {
  string job_run_id = 1;
  repeated MissingDeps missing_deps = 2;
+  repeated ReadDeps read_deps = 3;
+}
+message JobRunReadDepsEventV1 {
+  string job_run_id = 1;
+  repeated ReadDeps read_deps = 2;
+}
+message JobRunMissingDeps {
+  string version = 1;
+  repeated MissingDeps missing_deps = 2;
 }
 message MissingDeps {
  // The list of partition refs that are prevented from building by these missing deps (can be just 1)
  repeated PartitionRef impacted = 1;
  repeated PartitionRef missing = 2;
 }
+message JobRunReadDeps {
+  string version = 1;
+  repeated ReadDeps read_deps = 2;
+}
+message ReadDeps {
+  // The list of partition refs that are built using the read deps (can be just 1)
+  repeated PartitionRef impacted = 1;
+  repeated PartitionRef read = 2;
+}


 message WantCreateEventV1 {
@ -147,14 +167,17 @@ enum WantStatusCode {

 message WantDetail {
  string want_id = 1;
+  // The partitions directly wanted by this want
  repeated PartitionRef partitions = 2;
-  uint64 data_timestamp = 3;
-  uint64 ttl_seconds = 4;
-  uint64 sla_seconds = 5;
-  EventSource source = 6;
-  optional string comment = 7;
-  WantStatus status = 8;
-  uint64 last_updated_timestamp = 9;
+  // The upstream partitions, detected from a dep miss job run failure
+  repeated PartitionRef upstreams = 3;
+  uint64 data_timestamp = 4;
+  uint64 ttl_seconds = 5;
+  uint64 sla_seconds = 6;
+  EventSource source = 7;
+  optional string comment = 8;
+  WantStatus status = 9;
+  uint64 last_updated_timestamp = 10;
  // TODO
 }

@ -167,6 +190,7 @@ message PartitionDetail {
  optional uint64 last_updated_timestamp = 3;
  // IDs that associate the partition with other objects
  repeated string job_run_ids = 4;
+  // Wants that reference this partition
  repeated string want_ids = 5;
  repeated string taint_ids = 6;
 }
@ -188,9 +212,25 @@ message TaintDetail {
  // TODO
 }

-message JobRunDetail {
-  // TODO
+message JobRunStatus {
+  JobRunStatusCode code = 1;
+  string name = 2;
 }
+enum JobRunStatusCode {
+  JobRunQueued = 0;
+  JobRunRunning = 1;
+  JobRunFailed = 2;
+  JobRunCanceled = 3;
+  JobRunSucceeded = 4;
+}
+message JobRunDetail {
+  string id = 1;
+  JobRunStatus status = 2;
+  optional uint64 last_heartbeat_at = 3;
+  repeated PartitionRef building_partitions = 4;
+  repeated WantAttributedPartitions servicing_wants = 5;
+}
+


 message EventFilter {
--- a/databuild/event_transforms.rs
+++ b/databuild/event_transforms.rs
@ -1,6 +1,7 @@
-use crate::util::current_timestamp;
-use crate::{PartitionRef, WantCancelEventV1, WantCreateEventV1, WantDetail, WantStatus, WantStatusCode};
 use crate::data_build_event::Event;
+use crate::util::current_timestamp;
+use crate::{event_source, EventSource, JobRunBufferEventV1, JobRunDetail, JobRunStatus, JobRunStatusCode, JobTriggeredEvent, ManuallyTriggeredEvent, PartitionDetail, PartitionRef, PartitionStatus, PartitionStatusCode, WantAttributedPartitions, WantCancelEventV1, WantCreateEventV1, WantDetail, WantStatus, WantStatusCode};
+use crate::PartitionStatusCode::{PartitionFailed, PartitionLive};

 impl From<&WantCreateEventV1> for WantDetail {
    fn from(e: &WantCreateEventV1) -> Self {
@ -12,12 +13,13 @@ impl From<WantCreateEventV1> for WantDetail {
        WantDetail {
            want_id: e.want_id,
            partitions: e.partitions,
+            upstreams: vec![],
            data_timestamp: e.data_timestamp,
            ttl_seconds: e.ttl_seconds,
            sla_seconds: e.sla_seconds,
            source: e.source,
            comment: e.comment,
-            status: Default::default(),
+            status: Some(Default::default()),
            last_updated_timestamp: current_timestamp(),
        }
    }
@ -33,6 +35,14 @@ impl From<WantCancelEventV1> for Event {
    }
 }

+impl From<WantCreateEventV1> for WantAttributedPartitions {
+    fn from(value: WantCreateEventV1) -> Self {
+        Self {
+            want_id: value.want_id,
+            partitions: value.partitions,
+        }
+    }
+}

 impl From<WantStatusCode> for WantStatus {
    fn from(code: WantStatusCode) -> Self {
@ -43,6 +53,50 @@ impl From<WantStatusCode> for WantStatus {
    }
 }

+impl From<JobRunBufferEventV1> for JobRunDetail {
+    fn from(value: JobRunBufferEventV1) -> Self {
+        Self {
+            id: value.job_run_id,
+            status: Some(JobRunStatusCode::JobRunQueued.into()),
+            last_heartbeat_at: None,
+            building_partitions: value.building_partitions,
+            servicing_wants: value.want_attributed_partitions,
+        }
+    }
+}
+
+
+pub fn want_status_matches_any(pds: &Vec<Option<PartitionDetail>>, status: PartitionStatusCode) -> bool {
+    pds.iter()
+        .any(|pd| pd.clone()
+            .map(|pd| pd.status == Some(status.into()))
+        .unwrap_or(false))
+}
+
+pub fn want_status_matches_all(pds: &Vec<Option<PartitionDetail>>, status: PartitionStatusCode) -> bool {
+    pds.iter()
+        .all(|pd| pd.clone()
+            .map(|pd| pd.status == Some(status.into()))
+        .unwrap_or(false))
+}
+
+/// Merges a list of partition details into a single status code.
+/// Takes the lowest state as the want status.
+impl Into<WantStatusCode> for Vec<Option<PartitionDetail>> {
+
+    fn into(self) -> WantStatusCode {
+        if want_status_matches_any(&self, PartitionFailed) {
+            WantStatusCode::WantFailed
+        } else if want_status_matches_all(&self, PartitionLive) {
+            WantStatusCode::WantSuccessful
+        } else if self.iter().any(|pd| pd.is_none()) {
+            WantStatusCode::WantBuilding
+        } else {
+            WantStatusCode::WantIdle
+        }
+    }
+}
+
 impl From<&str> for PartitionRef {
    fn from(value: &str) -> Self {
        Self {
@ -50,3 +104,46 @@ impl From<&str> for PartitionRef {
        }
    }
 }
+
+impl From<PartitionStatusCode> for PartitionStatus {
+    fn from(code: PartitionStatusCode) -> Self {
+        PartitionStatus {
+            code: code.into(),
+            name: code.as_str_name().to_string(),
+        }
+    }
+}
+
+impl From<JobRunStatusCode> for JobRunStatus {
+    fn from(code: JobRunStatusCode) -> Self {
+        JobRunStatus {
+            code: code.into(),
+            name: code.as_str_name().to_string(),
+        }
+    }
+}
+
+impl From<ManuallyTriggeredEvent> for EventSource {
+    fn from(value: ManuallyTriggeredEvent) -> Self {
+        Self {
+            source: Some(event_source::Source::ManuallyTriggered(value)),
+        }
+    }
+}
+
+impl From<JobTriggeredEvent> for EventSource {
+    fn from(value: JobTriggeredEvent) -> Self {
+        Self {
+            source: Some(event_source::Source::JobTriggered(value)),
+        }
+    }
+}
+
+impl From<&WantDetail> for WantAttributedPartitions {
+    fn from(value: &WantDetail) -> Self {
+        Self {
+            want_id: value.want_id.clone(),
+            partitions: value.partitions.clone(),
+        }
+    }
+}
--- a/databuild/job.rs
+++ b/databuild/job.rs
@ -1,22 +1,21 @@
-use crate::job_run::JobRun;
+use crate::job_run::{NotStartedJobRun, SubProcessBackend};
 use crate::{PartitionRef, WantDetail};
 use regex::Regex;
-use std::error::Error;

 #[derive(Debug, Clone)]
 pub struct JobConfiguration {
    pub label: String,
    pub pattern: String,
-    pub entrypoint: String,
+    pub entry_point: String,
 }

 impl JobConfiguration {
    /** Launch job to build the partitions specified by the provided wants. */
-    pub fn spawn(&self, wants: Vec<WantDetail>) -> Result<JobRun, Box<dyn Error>> {
+    pub fn spawn(&self, wants: Vec<WantDetail>) -> Result<NotStartedJobRun<SubProcessBackend>, std::io::Error> {
        let wanted_refs: Vec<PartitionRef> =
            wants.iter().flat_map(|want| want.partitions.clone()).collect();
        let args: Vec<String> = wanted_refs.iter().map(|pref| pref.r#ref.clone()).collect();
-        JobRun::spawn(self.entrypoint.clone(), args)
+        Ok(NotStartedJobRun::spawn(self.entry_point.clone(), args))
    }

    pub fn matches(&self, refs: &PartitionRef) -> bool {
--- a/databuild/job_run.rs
+++ b/databuild/job_run.rs
@ -1,164 +1,542 @@
-use crate::build_event_log::{BELStorage, MemoryBELStorage};
 use crate::data_build_event::Event;
-use crate::data_build_event::Event::{JobRunFailureV1, JobRunSuccessV1};
-use crate::{DataBuildEvent, JobRunFailureEventV1, JobRunHeartbeatEventV1, JobRunSuccessEventV1};
+use crate::data_deps::JobRunDataDepResults;
+use crate::{
+    EventSource, JobRunCancelEventV1, JobRunFailureEventV1, JobRunMissingDepsEventV1, JobRunStatus,
+    JobRunSuccessEventV1, MissingDeps, ReadDeps,
+};
+use crate::util::DatabuildError;
+use std::collections::HashMap;
 use std::error::Error;
 use std::io::{BufRead, BufReader};
-use std::process::{Child, Command, ExitStatus, Stdio};
+use std::marker::PhantomData;
+use std::process::{Child, Command, Stdio};
 use uuid::Uuid;
+// TODO log to /var/log/databuild/jobruns/$JOB_RUN_ID/, and rotate over max size (e.g. only ever use 1GB for logs)
+// Leave door open to background log processor that tails job logs, but don't include in jobrun concept

-/** Wrapper type that can be mocked */
-trait JobRunChild {
-    fn exit_status(&mut self) -> Option<ExitStatus>;
-    fn stdout_lines(&mut self) -> Vec<String>;
-}
+/// Backend trait that defines the state types and transition logic for different job run implementations
+pub trait JobRunBackend: Sized {
+    type NotStartedState;
+    type RunningState;
+    type CompletedState;
+    type FailedState;
+    type CanceledState;
+    type DepMissState;

-#[derive(Debug)]
-struct WrappedProcessChild(Child);
+    /// Create a new not-started job run
+    fn create(entry_point: String, args: Vec<String>) -> Self::NotStartedState;

-impl JobRunChild for WrappedProcessChild {
-    fn exit_status(&mut self) -> Option<ExitStatus> {
-        self.0.try_wait().expect("coudn't wait")
+    /// Convenience method to spawn a new job run (calls create and wraps in JobRun)
+    fn spawn(entry_point: String, args: Vec<String>) -> NotStartedJobRun<Self> {
+        NotStartedJobRun::spawn(entry_point, args)
    }

-    fn stdout_lines(&mut self) -> Vec<String> {
-        let mut stdout_lines = Vec::new();
-        let stdout = self.0.stdout.take().expect("stdout not piped");
-        let reader = BufReader::new(stdout);
-        for line in reader.lines() {
-            stdout_lines.push(line.expect("stdout not piped"));
+    /// Transition from NotStarted to Running
+    fn start(
+        not_started: Self::NotStartedState,
+        env: Option<HashMap<String, String>>,
+    ) -> Result<Self::RunningState, DatabuildError>;
+
+    /// Poll a running job for state changes
+    fn poll(
+        running: &mut Self::RunningState,
+    ) -> Result<
+        PollResult<Self::CompletedState, Self::FailedState, Self::DepMissState>,
+        DatabuildError,
+    >;
+
+    /// Cancel a running job
+    fn cancel_job(
+        running: Self::RunningState,
+        source: EventSource,
+    ) -> Result<Self::CanceledState, DatabuildError>;
+}
+
+/// Result of polling a running job
+pub enum PollResult<C, F, D> {
+    StillRunning,
+    Completed(C),
+    Failed(F),
+    DepMiss(D),
+}
+
+/// Generic JobRun that works with any backend, parameterized by state
+pub struct JobRun<B: JobRunBackend, S> {
+    pub job_run_id: Uuid,
+    pub state: S,
+    pub _backend: PhantomData<B>,
+}
+
+/// Type aliases for specific states
+pub type NotStartedJobRun<B> = JobRun<B, <B as JobRunBackend>::NotStartedState>;
+pub type RunningJobRun<B> = JobRun<B, <B as JobRunBackend>::RunningState>;
+pub type CompletedJobRun<B> = JobRun<B, <B as JobRunBackend>::CompletedState>;
+pub type FailedJobRun<B> = JobRun<B, <B as JobRunBackend>::FailedState>;
+pub type CanceledJobRun<B> = JobRun<B, <B as JobRunBackend>::CanceledState>;
+pub type DepMissJobRun<B> = JobRun<B, <B as JobRunBackend>::DepMissState>;
+
+// Methods available on all JobRun states
+impl<B: JobRunBackend, S> JobRun<B, S> {
+    pub fn id(&self) -> Uuid {
+        self.job_run_id
+    }
+}
+
+// Methods available only on NotStarted state
+impl<B: JobRunBackend> NotStartedJobRun<B> {
+    pub fn spawn(entry_point: String, args: Vec<String>) -> Self {
+        JobRun {
+            job_run_id: Uuid::new_v4(),
+            state: B::create(entry_point, args),
+            _backend: PhantomData,
        }
-        stdout_lines
    }
-}

-impl From<Child> for WrappedProcessChild {
-    fn from(child: Child) -> Self {
-        Self { 0: child }
+    pub fn run(self) -> Result<RunningJobRun<B>, DatabuildError> {
+        self.run_with_env(None)
    }
-}

-pub struct JobRun {
-    job_run_id: Uuid,
-    events: MemoryBELStorage,
-    child: Box<dyn JobRunChild>,
-    unhandled_lines: Vec<String>,
-}
-
-const EVENT_SIZE_LIMIT: u64 = 1000000;
-
-impl JobRun {
-    pub fn spawn(command: String, args: Vec<String>) -> Result<JobRun, Box<dyn Error>> {
+    pub fn run_with_env(
+        self,
+        env: Option<HashMap<String, String>>,
+    ) -> Result<RunningJobRun<B>, DatabuildError> {
+        let running_state = B::start(self.state, env)?;
        Ok(JobRun {
-            job_run_id: Default::default(),
-            events: Default::default(),
-            child: Box::new(WrappedProcessChild::from(
-                Command::new(command)
-                    .args(args)
-                    .stdout(Stdio::piped())
-                    .spawn()?,
-            )),
-            unhandled_lines: Default::default(),
+            job_run_id: self.job_run_id,
+            state: running_state,
+            _backend: PhantomData,
+        })
+    }
+}
+
+// Methods available only on Running state
+impl<B: JobRunBackend> RunningJobRun<B> {
+    pub fn visit(&mut self) -> Result<JobRunVisitResult<B>, DatabuildError> {
+        match B::poll(&mut self.state)? {
+            PollResult::StillRunning => Ok(JobRunVisitResult::StillRunning),
+            PollResult::Completed(completed_state) => {
+                let job_run_id = self.job_run_id;
+                Ok(JobRunVisitResult::Completed(JobRun {
+                    job_run_id,
+                    state: completed_state,
+                    _backend: PhantomData,
+                }))
+            }
+            PollResult::Failed(failed_state) => {
+                let job_run_id = self.job_run_id;
+                Ok(JobRunVisitResult::Failed(JobRun {
+                    job_run_id,
+                    state: failed_state,
+                    _backend: PhantomData,
+                }))
+            }
+            PollResult::DepMiss(state) => {
+                let job_run_id = self.job_run_id;
+                Ok(JobRunVisitResult::DepMiss(JobRun {
+                    job_run_id,
+                    state,
+                    _backend: PhantomData,
+                }))
+            }
+        }
+    }
+
+    pub fn cancel(self, source: EventSource) -> Result<CanceledJobRun<B>, DatabuildError> {
+        let canceled_state = B::cancel_job(self.state, source)?;
+        Ok(JobRun {
+            job_run_id: self.job_run_id,
+            state: canceled_state,
+            _backend: PhantomData,
+        })
+    }
+}
+
+/// Result of visiting a running job
+pub enum JobRunVisitResult<B: JobRunBackend> {
+    StillRunning,
+    Completed(CompletedJobRun<B>),
+    Failed(FailedJobRun<B>),
+    DepMiss(DepMissJobRun<B>),
+}
+
+pub enum JobRunConfig {
+    SubProcess {
+        entry_point: String,
+        args: Vec<String>,
+    },
+}
+
+// ===== SubProcess Backend Implementation =====
+
+/// SubProcess backend for running jobs as local subprocesses
+pub struct SubProcessBackend;
+
+/// NotStarted state for SubProcess backend
+pub struct SubProcessNotStarted {
+    pub entry_point: String,
+    pub args: Vec<String>,
+}
+
+/// Running state for SubProcess backend
+pub struct SubProcessRunning {
+    pub process: Child,
+    pub stdout_buffer: Vec<String>,
+}
+
+/// Completed state for SubProcess backend
+pub struct SubProcessCompleted {
+    pub exit_code: i32,
+    pub stdout_buffer: Vec<String>,
+    pub read_deps: Vec<ReadDeps>,
+}
+
+/// Failed state for SubProcess backend
+pub struct SubProcessFailed {
+    pub exit_code: i32,
+    pub reason: String,
+    pub stdout_buffer: Vec<String>,
+}
+
+/// Canceled state for SubProcess backend
+pub struct SubProcessCanceled {
+    pub source: EventSource,
+    pub stdout_buffer: Vec<String>,
+}
+
+pub struct SubProcessDepMiss {
+    pub stdout_buffer: Vec<String>,
+    pub missing_deps: Vec<MissingDeps>,
+    pub read_deps: Vec<ReadDeps>,
+}
+
+impl JobRunBackend for SubProcessBackend {
+    type NotStartedState = SubProcessNotStarted;
+    type RunningState = SubProcessRunning;
+    type CompletedState = SubProcessCompleted;
+    type FailedState = SubProcessFailed;
+    type CanceledState = SubProcessCanceled;
+    type DepMissState = SubProcessDepMiss;
+
+    fn create(entry_point: String, args: Vec<String>) -> Self::NotStartedState {
+        SubProcessNotStarted { entry_point, args }
+    }
+
+    fn start(
+        not_started: Self::NotStartedState,
+        env: Option<HashMap<String, String>>,
+    ) -> Result<Self::RunningState, DatabuildError> {
+        let process = Command::new(not_started.entry_point)
+            .args(not_started.args)
+            .stdout(Stdio::piped())
+            .stderr(Stdio::piped())
+            .envs(env.unwrap_or_default())
+            .spawn()?;
+
+        Ok(SubProcessRunning {
+            process,
+            stdout_buffer: Vec::new(),
        })
    }

-    pub fn visit(&mut self, since_idx: u64) -> Result<Vec<DataBuildEvent>, Box<dyn Error>> {
-        // Collect new lines from child process
-
-        // Parse BEL events from child process
-        let new_events = Self::process_lines(self.job_run_id, &self.unhandled_lines);
-        for event in new_events {
-            self.events.append_event(&event)?;
-        }
-        self.unhandled_lines.drain(..);
-
-        // Potentially react to job completion
-        match self.exit_status() {
-            None => {} // No exit -> no harm
-            Some(status) => {
-                if status.success() {
-                    self.events
-                        .append_event(&JobRunSuccessV1(JobRunSuccessEventV1 {
-                            job_run_id: self.job_run_id.into(),
-                        }))?;
-                } else {
-                    self.events
-                        .append_event(&JobRunFailureV1(JobRunFailureEventV1 {
-                            job_run_id: self.job_run_id.into(),
-                        }))?;
+    fn poll(
+        running: &mut Self::RunningState,
+    ) -> Result<
+        PollResult<Self::CompletedState, Self::FailedState, Self::DepMissState>,
+        DatabuildError,
+    > {
+        // Non-blocking check for exit status
+        if let Some(exit_status) = running.process.try_wait()? {
+            // Job has exited
+            // Read any remaining stdout
+            if let Some(stdout) = running.process.stdout.take() {
+                let reader = BufReader::new(stdout);
+                for line in reader.lines() {
+                    // TODO we should write lines to the job's file logs
+                    if let Ok(line) = line {
+                        running.stdout_buffer.push(line);
+                    }
                }
            }
-        }

-        // Return BEL events since provided idx
-        self.events
-            .list_events(since_idx, EVENT_SIZE_LIMIT)
-            .and_then(|events| {
-                if events.len() as u64 == EVENT_SIZE_LIMIT {
-                    Err(format!(
-                        "Returned {} events - that's way too many.",
-                        EVENT_SIZE_LIMIT
-                    )
-                    .into())
-                } else {
-                    Ok(events)
+            // Take ownership of stdout_buffer, parse dep events
+            let stdout_buffer = std::mem::take(&mut running.stdout_buffer);
+            let deps: JobRunDataDepResults = stdout_buffer.clone().into();
+
+            // Check exit status and return appropriate result
+            match exit_status.code() {
+                Some(0) => {
+                    // Success case
+                    Ok(PollResult::Completed(SubProcessCompleted {
+                        exit_code: 0,
+                        stdout_buffer,
+                        read_deps: deps.reads,
+                    }))
                }
-            })
-    }
-
-    pub fn cancel(&mut self) {
-        todo!()
-    }
-
-    pub fn event_for_line(line: String) -> Option<Event> {
-        // TODO parse missing data dep event
-        // TODO parse job state
-        None
-    }
-
-    pub fn process_lines(job_run_id: Uuid, lines: &Vec<String>) -> Vec<Event> {
-        let mut events: Vec<Event> = Default::default();
-
-        if lines.len() > 0 {
-            // If any lines were written to stdout, we should heartbeat
-            events.push(Event::JobRunHeartbeatV1(JobRunHeartbeatEventV1 {
-                job_run_id: job_run_id.clone().into(),
-            }));
+                Some(code) => {
+                    // Failed with exit code
+                    match deps.misses {
+                        vec if vec.is_empty() => {
+                            // No missing deps, job failed
+                            let reason = format!("Job failed with exit code {}", code);
+                            Ok(PollResult::Failed(SubProcessFailed {
+                                exit_code: code,
+                                reason,
+                                stdout_buffer,
+                            }))
+                        }
+                        misses => Ok(PollResult::DepMiss(SubProcessDepMiss {
+                            stdout_buffer,
+                            missing_deps: misses,
+                            read_deps: deps.reads,
+                        })),
+                    }
+                }
+                None => {
+                    // Terminated by signal (Unix) - treat as failure
+                    let reason = format!("Job terminated by signal: {}", exit_status);
+                    Ok(PollResult::Failed(SubProcessFailed {
+                        exit_code: -1,
+                        reason,
+                        stdout_buffer,
+                    }))
+                }
+            }
+        } else {
+            // Still running
+            Ok(PollResult::StillRunning)
        }
+    }

-        for event in lines
-            .iter()
-            .flat_map(|line| Self::event_for_line(line.clone()))
-        {
-            events.push(event);
+    fn cancel_job(
+        mut running: Self::RunningState,
+        source: EventSource,
+    ) -> Result<Self::CanceledState, DatabuildError> {
+        // Kill the process
+        running.process.kill()?;
+
+        // Wait for it to actually terminate
+        running.process.wait()?;
+
+        // Return canceled state
+        Ok(SubProcessCanceled {
+            source,
+            stdout_buffer: running.stdout_buffer,
+        })
+    }
+}
+
+// Helper functions to convert between states and events
+impl SubProcessCompleted {
+    pub fn to_event(&self, job_run_id: &Uuid) -> Event {
+        Event::JobRunSuccessV1(JobRunSuccessEventV1 {
+            job_run_id: job_run_id.to_string(),
+        })
+    }
+}
+
+impl SubProcessFailed {
+    pub fn to_event(&self, job_run_id: &Uuid) -> Event {
+        Event::JobRunFailureV1(JobRunFailureEventV1 {
+            job_run_id: job_run_id.to_string(),
+            reason: self.reason.clone(),
+        })
+    }
+}
+
+impl SubProcessCanceled {
+    pub fn to_event(&self, job_run_id: &Uuid) -> JobRunCancelEventV1 {
+        JobRunCancelEventV1 {
+            job_run_id: job_run_id.to_string(),
+            source: Some(self.source.clone()),
+            comment: Some("Job was canceled".to_string()),
        }
-
-        events
    }
+}

-    pub fn exit_status(&mut self) -> Option<ExitStatus> {
-        self.child.exit_status()
+impl SubProcessDepMiss {
+    pub fn to_event(&self, job_run_id: &Uuid) -> Event {
+        Event::JobRunMissingDepsV1(JobRunMissingDepsEventV1 {
+            job_run_id: job_run_id.to_string(),
+            missing_deps: self.missing_deps.clone(),
+            read_deps: self.read_deps.clone(),
+        })
    }
 }

+// Old JobRunPollResult structure - kept for compatibility during migration
+pub struct JobRunPollResult {
+    pub new_events: Vec<Event>,
+    pub status: JobRunStatus,
+}
+
 mod tests {
-    use crate::job_run::JobRun;
+    use crate::data_build_event::Event;
+    use crate::data_deps::DATABUILD_MISSING_DEPS_JSON;
+    use crate::job_run::{JobRunBackend, JobRunVisitResult, SubProcessBackend};
+    use crate::mock_job_run::MockJobRun;
+    use crate::{JobRunMissingDeps, ManuallyTriggeredEvent, MissingDeps};

+    /// Happy path - run that succeeds should emit a JobRunSuccessEventV1
    #[test]
-    fn test_process_lines_empty() {
-        let lines = Vec::<String>::new();
-        let events = JobRun::process_lines(Default::default(), &lines);
-        assert_eq!(events.len(), 0);
+    fn test_job_run_success_returns_job_run_success_event() {
+        // Spawn a job run that will succeed (exit code 0)
+        let job_run = SubProcessBackend::spawn(MockJobRun::bin_path(), vec![]);
+
+        // Start the job - this consumes the NotStarted and returns Running
+        let mut running_job = job_run.run().unwrap();
+
+        // Poll until we get completion
+        loop {
+            match running_job.visit().unwrap() {
+                JobRunVisitResult::Completed(completed) => {
+                    // Generate the event from the completed state
+                    let event = completed.state.to_event(&completed.id());
+                    assert!(matches!(event, Event::JobRunSuccessV1(_)));
+                    break;
+                }
+                JobRunVisitResult::Failed(failed) => {
+                    panic!("Job failed unexpectedly: {}", failed.state.reason);
+                }
+                JobRunVisitResult::StillRunning => {
+                    // Sleep briefly and poll again
+                    std::thread::sleep(std::time::Duration::from_millis(10));
+                    continue;
+                }
+                JobRunVisitResult::DepMiss(dep_miss) => {
+                    panic!("Job dep miss unexpectedly");
+                }
+            }
+        }
    }

+    /// Job run that fails should emit a JobRunFailureEventV1
    #[test]
-    fn test_process_lines_heartbeat() {
-        let lines_1 = vec!["Hello, salem".to_string()];
-        let events_1 = JobRun::process_lines(Default::default(), &lines_1);
-        assert_eq!(events_1.len(), 1);
+    fn test_job_run_failure_returns_job_run_failure_event() {
+        // Spawn a job run
+        let job_run = SubProcessBackend::spawn(MockJobRun::bin_path(), vec![]);

-        let lines_2 = vec!["Hello, salem".to_string(), "Hello, pippin".to_string()];
-        let events_2 = JobRun::process_lines(Default::default(), &lines_2);
-        assert_eq!(events_2.len(), 1);
+        // Start the job with an exit code that indicates failure (non-zero)
+        let env = MockJobRun::new().exit_code(1).to_env();
+        let mut running_job = job_run.run_with_env(Some(env)).unwrap();
+
+        // Poll until we get completion
+        loop {
+            match running_job.visit().unwrap() {
+                JobRunVisitResult::Completed(_) => {
+                    panic!("Job succeeded unexpectedly");
+                }
+                JobRunVisitResult::Failed(failed) => {
+                    // Generate the event from the failed state
+                    let event = failed.state.to_event(&failed.id());
+                    assert!(matches!(event, Event::JobRunFailureV1(_)));
+                    break;
+                }
+                JobRunVisitResult::StillRunning => {
+                    // Sleep briefly and poll again
+                    std::thread::sleep(std::time::Duration::from_millis(10));
+                    continue;
+                }
+                JobRunVisitResult::DepMiss(dep_miss) => {
+                    panic!("Job dep miss unexpectedly");
+                }
+            }
+        }
+    }
+
+    /// Canceling an event before it completes should result in it:
+    /// - Stop the actual subprocess (e.g. no output file should be written)
+    /// - Emitting a JobRunCancelEventV1 event
+    #[test]
+    fn test_job_run_cancel_returns_job_run_cancel_event() {
+        use crate::ManuallyTriggeredEvent;
+        use std::fs;
+        use uuid::Uuid;
+
+        // Create a temp file path for the test
+        let temp_file = format!("/tmp/databuild_test_cancel_{}", Uuid::new_v4());
+
+        // Spawn a job run that will sleep for 1 second and write a file
+        let job_run = SubProcessBackend::spawn(MockJobRun::bin_path(), vec![]);
+
+        let env = MockJobRun::new()
+            .sleep_ms(1000)
+            .output_file(&temp_file, &"completed".to_string())
+            .exit_code(0)
+            .to_env();
+        let running_job = job_run.run_with_env(Some(env)).unwrap();
+
+        // Give it a tiny bit of time to start
+        std::thread::sleep(std::time::Duration::from_millis(10));
+
+        // Cancel the job before it can complete - this consumes the running job and returns canceled
+        let canceled_job = running_job
+            .cancel(
+                ManuallyTriggeredEvent {
+                    user: "test_user".into(),
+                }
+                .into(),
+            )
+            .unwrap();
+
+        // Generate the cancel event from the canceled state
+        let cancel_event = canceled_job.state.to_event(&canceled_job.id());
+
+        // Verify we got the cancel event
+        assert_eq!(cancel_event.job_run_id, canceled_job.id().to_string());
+        assert!(cancel_event.source.is_some());
+        assert_eq!(cancel_event.comment, Some("Job was canceled".to_string()));
+
+        // Verify the output file was NOT written (process was killed before it could complete)
+        assert!(
+            !std::path::Path::new(&temp_file).exists(),
+            "Output file should not exist - process should have been killed"
+        );
+
+        // Cleanup just in case
+        let _ = fs::remove_file(&temp_file);
+    }
+
+    /// Job run that fails and emits a recognized "dep miss" statement should emit a JobRunMissingDepsEventV1
+    #[test]
+    fn test_job_run_fail_on_missing_deps_should_emit_missing_deps_event() {
+        // Spawn a job run that will sleep for 1 second and write a file
+        let job_run = SubProcessBackend::spawn(MockJobRun::bin_path(), vec![]);
+
+        let expected_dep_miss = JobRunMissingDeps {
+            version: "1".into(),
+            missing_deps: vec![MissingDeps {
+                impacted: vec!["my_fav_output".into()],
+                missing: vec!["cool_input_1".into(), "cool_input_2".into()],
+            }],
+        };
+        let dep_miss_json =
+            serde_json::to_string(&expected_dep_miss).expect("Failed to serialize dep miss");
+        let dep_miss_line = format!("{}{}", DATABUILD_MISSING_DEPS_JSON, dep_miss_json);
+        let env = MockJobRun::new()
+            .stdout_msg(&dep_miss_line)
+            .exit_code(1)
+            .to_env();
+        let mut running_job = job_run.run_with_env(Some(env)).unwrap();
+
+        // Poll until we get completion
+        loop {
+            match running_job.visit().unwrap() {
+                JobRunVisitResult::Completed(_) => {
+                    panic!("Job succeeded unexpectedly");
+                }
+                JobRunVisitResult::Failed(failed) => {
+                    panic!("Job failed unexpectedly");
+                }
+                JobRunVisitResult::StillRunning => {
+                    // Sleep briefly and poll again
+                    std::thread::sleep(std::time::Duration::from_millis(10));
+                    continue;
+                }
+                JobRunVisitResult::DepMiss(backend) => {
+                    assert_eq!(backend.state.missing_deps, expected_dep_miss.missing_deps);
+                    break;
+                }
+            }
+        }
    }
 }
--- a/databuild/lib.rs
+++ b/databuild/lib.rs
@ -6,6 +6,8 @@ mod util;
 mod build_state;
 mod event_transforms;
 mod event_defaults;
+mod data_deps;
+mod mock_job_run;

 // Include generated protobuf code
 include!("databuild.rs");
--- a/databuild/mock_job_run.rs
+++ b/databuild/mock_job_run.rs
@ -0,0 +1,83 @@
+use std::collections::HashMap;
+
+pub struct MockJobRun {
+    sleep_ms: u64,
+    stdout_msg: String,
+    output_file: Option<OutputFile>,
+    exit_code: u8,
+}
+
+pub struct OutputFile {
+    path: String,
+    contents: String,
+}
+
+impl Default for MockJobRun {
+    fn default() -> Self {
+        Self {
+            sleep_ms: 0,
+            stdout_msg: "test executed".to_string(),
+            output_file: None,
+            exit_code: 0,
+        }
+    }
+}
+
+impl MockJobRun {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn sleep_ms(mut self, val: u64) -> Self {
+        self.sleep_ms = val;
+        self
+    }
+
+    pub fn stdout_msg(mut self, val: &String) -> Self {
+        self.stdout_msg = val.into();
+        self
+    }
+
+    pub fn output_file(mut self, path: &String, contents: &String) -> Self {
+        self.output_file = Some(OutputFile {
+            path: path.to_string(),
+            contents: contents.to_string(),
+        });
+        self
+    }
+
+    pub fn exit_code(mut self, val: u8) -> Self {
+        self.exit_code = val;
+        self
+    }
+
+    pub fn to_env(&self) -> HashMap<String, String> {
+        let mut env = HashMap::new();
+        env.insert(
+            "DATABUILD_TEST_SLEEP_MS".to_string(),
+            self.sleep_ms.to_string(),
+        );
+        env.insert(
+            "DATABUILD_TEST_EXIT_CODE".to_string(),
+            self.exit_code.to_string(),
+        );
+        env.insert("DATABUILD_TEST_STDOUT".to_string(), self.stdout_msg.clone());
+        if let Some(output_file) = &self.output_file {
+            env.insert(
+                "DATABUILD_TEST_OUTPUT_FILE".to_string(),
+                output_file.path.clone(),
+            );
+            env.insert(
+                "DATABUILD_TEST_OUTPUT_CONTENTS".to_string(),
+                output_file.contents.clone(),
+            );
+        }
+        env
+    }
+
+    pub fn bin_path() -> String {
+        std::env::var("TEST_SRCDIR")
+            .map(|srcdir| format!("{}/_main/databuild/test/test_job_helper", srcdir))
+            .unwrap_or_else(|_| "bazel-bin/databuild/test/test_job_helper".to_string())
+    }
+}
--- a/databuild/orchestrator.rs
+++ b/databuild/orchestrator.rs
@ -1,41 +1,95 @@
-use crate::build_event_log::{BELStorage, BuildEventLog};
+use crate::build_event_log::{BELStorage, BuildEventLog, MemoryBELStorage};
+use crate::build_state::BuildState;
+use crate::data_build_event::Event;
 use crate::job::JobConfiguration;
-use crate::job_run::JobRun;
-use crate::{PartitionRef, WantDetail};
+use crate::job_run::{
+    CompletedJobRun, DepMissJobRun, FailedJobRun, NotStartedJobRun, RunningJobRun,
+    SubProcessBackend,
+};
+use crate::{JobRunBufferEventV1, PartitionRef, WantDetail};
 use std::collections::HashMap;
 use std::error::Error;
 use std::fmt::Debug;
+use crate::util::DatabuildError;

 /**
 Orchestrator turns wants, config, and BEL state into scheduled jobs. It uses lightweight threads +
-the visitor pattern to monitor job exec progress and liveness, and adds
+the visitor pattern to monitor job exec progress and liveness.
+
+JTBDs:
+- Orchestrator turns job run dep miss failures into derivative wants for the missed partitions
+- Orchestrator turns schedulable wants into job runs to build the requested partitions
+- Orchestrator polls queued and active job runs, keeping track of their state, and scheduling queued
+  jobs when possible
 */
-
 struct Orchestrator<S: BELStorage + Debug> {
-    bel: BuildEventLog<S>,
-    job_runs: Vec<JobRunHandle>,
-    config: OrchestratorConfig,
+    pub bel: BuildEventLog<S>,
+    pub not_started_jobs: Vec<NotStartedJobRun<SubProcessBackend>>,
+    pub running_jobs: Vec<RunningJobRun<SubProcessBackend>>,
+    pub completed_jobs: Vec<CompletedJobRun<SubProcessBackend>>,
+    pub failed_jobs: Vec<FailedJobRun<SubProcessBackend>>,
+    pub dep_miss_jobs: Vec<DepMissJobRun<SubProcessBackend>>,
+    pub config: OrchestratorConfig,
 }

-struct JobRunHandle {
-    job_run: JobRun,
-    bel_idx: u64,
-}
-
-impl From<JobRun> for JobRunHandle {
-    fn from(job_run: JobRun) -> Self {
+impl Default for Orchestrator<MemoryBELStorage> {
+    fn default() -> Self {
        Self {
-            job_run,
-            bel_idx: 0,
+            bel: Default::default(),
+            not_started_jobs: Default::default(),
+            running_jobs: Default::default(),
+            completed_jobs: Default::default(),
+            failed_jobs: Default::default(),
+            dep_miss_jobs: Default::default(),
+            config: Default::default(),
        }
    }
 }

+impl Orchestrator<MemoryBELStorage> {
+    fn copy(&self) -> Self {
+        Self {
+            bel: self.bel.clone(),
+            not_started_jobs: Default::default(),
+            running_jobs: Default::default(),
+            completed_jobs: Default::default(),
+            failed_jobs: Default::default(),
+            dep_miss_jobs: Default::default(),
+            config: self.config.clone(),
+        }
+    }
+}
+
+impl<S: BELStorage + Debug> Orchestrator<S> {
+    fn with_config(self, config: OrchestratorConfig) -> Self {
+        Self { config, ..self }
+    }
+
+    fn with_jobs(self, jobs: Vec<JobConfiguration>) -> Self {
+        Self {
+            config: self.config.with_jobs(jobs),
+            ..self
+        }
+    }
+
+    fn with_bel(self, bel: BuildEventLog<S>) -> Self {
+        Self { bel, ..self }
+    }
+}
+
 #[derive(Debug, Clone)]
 struct OrchestratorConfig {
    jobs: Vec<JobConfiguration>,
 }

+impl Default for OrchestratorConfig {
+    fn default() -> Self {
+        Self {
+            jobs: Vec::default(),
+        }
+    }
+}
+
 impl OrchestratorConfig {
    fn job_configuration_for_label(&self, label: &str) -> Option<JobConfiguration> {
        self.jobs.iter().find(|job| job.label == label).cloned()
@ -44,6 +98,14 @@ impl OrchestratorConfig {
    fn match_job_partition(&self, pref: &PartitionRef) -> Option<JobConfiguration> {
        self.jobs.iter().find(|job| job.matches(pref)).cloned()
    }
+
+    fn with_jobs(self, jobs: Vec<JobConfiguration>) -> Self {
+        Self { jobs }
+    }
+
+    fn with_job(self, job: JobConfiguration) -> Self {
+        Self { jobs: vec![job] }
+    }
 }

 #[derive(Debug, Clone)]
@ -52,6 +114,12 @@ struct WantGroup {
    wants: Vec<WantDetail>,
 }

+impl WantGroup {
+    pub fn spawn(&self) -> Result<NotStartedJobRun<SubProcessBackend>, std::io::Error> {
+        self.job.spawn(self.wants.clone())
+    }
+}
+
 #[derive(Debug, Clone)]
 struct GroupedWants {
    want_groups: Vec<WantGroup>,
@ -62,54 +130,123 @@ impl<S: BELStorage + Debug> Orchestrator<S> {
    fn new(storage: S, config: OrchestratorConfig) -> Self {
        Self {
            bel: BuildEventLog::new(storage, Default::default()),
-            job_runs: Vec::new(),
+            not_started_jobs: Vec::new(),
+            running_jobs: Vec::new(),
+            completed_jobs: Vec::new(),
+            failed_jobs: Vec::new(),
+            dep_miss_jobs: Vec::new(),
            config,
        }
    }

-    /** Continuously invoked function to watch job run status */
-    fn poll_job_runs(&mut self) -> Result<(), Box<dyn Error>> {
-        // Visit existing jobs, remove completed
-        self.job_runs.retain_mut(|jr| {
-            // Append emitted events
-            let events = jr
-                .job_run
-                .visit(jr.bel_idx.clone())
-                .expect("Job visit failed");
-            events
-                .iter()
-                .filter_map(|event| event.event.clone())
-                .for_each(|event| {
-                    self.bel
-                        .append_event(&event)
-                        .expect("Failed to append event");
-                });
+    fn job_runs_count(&self) -> usize {
+        self.not_started_jobs.len()
+            + self.running_jobs.len()
+            + self.completed_jobs.len()
+            + self.failed_jobs.len()
+            + self.dep_miss_jobs.len()
+    }

-            // Retain job run if it doesn't yet have an exit code (still running)
-            jr.job_run.exit_status().is_none()
-        });
+    /// Visits individual job runs, appending resulting events, and moving runs between run status
+    /// containers.
+    fn poll_job_runs(&mut self) -> Result<(), DatabuildError> {
+        use crate::job_run::JobRunVisitResult;
+
+        // Coherence check setup
+        let total_runs_count = self.job_runs_count();
+
+        // First, start any not-started jobs
+        while let Some(job) = self.not_started_jobs.pop() {
+            let running = job.run()?;
+            self.running_jobs.push(running);
+        }
+
+        // Visit running jobs and transition them to terminal states
+        let mut still_running = Vec::new();
+        // TODO make sure that failure in the middle can't mess up build state - likely need to
+        //  refactor here (e.g. turn state changes into data, commit them after all have been
+        //  calculated and validated)
+        for mut job in self.running_jobs.drain(..) {
+            match job.visit()? {
+                JobRunVisitResult::StillRunning => {
+                    println!("Still running job: {:?}", job.id());
+                    still_running.push(job);
+                }
+                JobRunVisitResult::Completed(completed) => {
+                    // Emit success event
+                    println!("Completed job: {:?}", completed.id());
+                    let result = run_complete_to_events(&self.bel.state, &completed)?;
+                    for event in result.events {
+                        self.bel.append_event(&event)?;
+                    }
+                    // Move job to completed
+                    self.completed_jobs.push(completed);
+                }
+                JobRunVisitResult::Failed(failed) => {
+                    // Emit failure event
+                    println!("Failed job: {:?}", failed.id());
+                    let event: Event = failed.state.to_event(&failed.id());
+                    self.bel.append_event(&event)?;
+                    self.failed_jobs.push(failed);
+                }
+                JobRunVisitResult::DepMiss(dep_miss) => {
+                    println!("Dep miss job: {:?}", dep_miss.job_run_id);
+                    for event in self.bel.state.dep_miss_to_events(&dep_miss)? {
+                        self.bel.append_event(&event)?;
+                    }
+                    // Record missing upstream status in want details
+                    self.dep_miss_jobs.push(dep_miss);
+                }
+            }
+        }
+        self.running_jobs = still_running;
+
+        // Panic because this should never happen
+        assert_eq!(
+            self.job_runs_count(),
+            total_runs_count,
+            "Detected job run count change during job run visit (should never happen)"
+        );

        Ok(())
    }

    /** Continuously invoked function to watch wants and schedule new jobs */
-    fn poll_wants(&mut self) -> Result<(), Box<dyn Error>> {
+    fn poll_wants(&mut self) -> Result<(), DatabuildError> {
        // Collect unhandled wants, group by job that handles each partition,
-        let grouped_wants =
-            Orchestrator::<S>::group_wants(&self.config, &self.bel.schedulable_wants());
+        let schedulability = self.bel.state.schedulable_wants();
+        println!("schedulability: {:?}", schedulability);
+        let schedulable_wants = schedulability
+            .0
+            .iter()
+            .filter_map(|ws| match ws.is_schedulable() {
+                false => None,
+                true => Some(ws.want.clone()),
+            })
+            .collect();
+        let grouped_wants = Orchestrator::<S>::group_wants(&self.config, &schedulable_wants);
+        println!("grouped wants: {:?}", grouped_wants);

-        if !grouped_wants.want_groups.is_empty() {
+        if !grouped_wants.unhandled_wants.is_empty() {
            // All wants must be mapped to jobs that can be handled
            // TODO we probably want to handle this gracefully in the near future
            Err(format!(
                "Unable to map following wants: {:?}",
-                &grouped_wants.want_groups
+                &grouped_wants.unhandled_wants
            )
            .into())
        } else {
+            // Spawn jobs and add events
            for wg in grouped_wants.want_groups {
-                let job_run = wg.job.spawn(wg.wants)?;
-                self.job_runs.push(JobRunHandle::from(job_run));
+                let job_run = wg.spawn()?;
+                let job_buffer_event = Event::JobRunBufferV1(JobRunBufferEventV1 {
+                    job_run_id: job_run.job_run_id.into(),
+                    job_label: wg.job.label,
+                    building_partitions: wg.wants.iter().map(|w| w.partitions.clone()).flatten().collect(),
+                    want_attributed_partitions: wg.wants.iter().map(|w| w.into()).collect(),
+                });
+                self.bel.append_event(&job_buffer_event)?;
+                self.not_started_jobs.push(job_run);
            }

            Ok(())
@ -142,17 +279,103 @@ impl<S: BELStorage + Debug> Orchestrator<S> {
        }
    }

+    fn step(&mut self) -> Result<(), DatabuildError> {
+        self.poll_job_runs()?;
+        self.poll_wants()?;
+        Ok(())
+    }
+
    /** Entrypoint for running jobs */
-    pub fn join(mut self) -> Result<(), Box<dyn Error>> {
+    pub fn join(&mut self) -> Result<(), DatabuildError> {
        loop {
-            self.poll_job_runs()?;
-            self.poll_wants()?;
+            self.step()?
        }
    }
 }

+#[derive(Default, Clone, Debug)]
+pub struct JobRunCompleteResult {
+    /// Events to append to the BEL from this job completing
+    pub events: Vec<Event>,
+}
+
+/// Handle successful run completion:
+/// - Adding run success event
+/// - Updating status for partitions actually built by the job
+fn run_complete_to_events(
+    bel_state: &BuildState,
+    completed: &CompletedJobRun<SubProcessBackend>,
+) -> Result<JobRunCompleteResult, DatabuildError> {
+    let mut events = vec![
+        // Event marking completion of job
+        completed.state.to_event(&completed.id()),
+    ];
+    // let job_detail = bel_state
+    //     .get_job_run(&completed.job_run_id.to_string())
+    //     .ok_or(format!(
+    //         "No job run found for id `{}`",
+    //         completed.job_run_id
+    //     ))?;
+
+    Ok(JobRunCompleteResult {
+        // built_partitions: job_detail.building_partitions,
+        events,
+    })
+}
+
 #[cfg(test)]
 mod tests {
+    use crate::build_event_log::MemoryBELStorage;
+    use crate::job::JobConfiguration;
+    use crate::mock_job_run::MockJobRun;
+    use crate::orchestrator::{Orchestrator, OrchestratorConfig};
+    use crate::util::current_timestamp;
+    use crate::WantCreateEventV1;
+    use uuid::Uuid;
+
+    fn build_orchestrator() -> Orchestrator<MemoryBELStorage> {
+        Orchestrator::default()
+    }
+
+    impl WantCreateEventV1 {
+        /// A naive random want for testing purposes
+        pub fn sample() -> Self {
+            Self {
+                want_id: Uuid::new_v4().to_string(),
+                partitions: vec![],
+                data_timestamp: current_timestamp(),
+                ttl_seconds: 1000,
+                sla_seconds: 1000,
+                source: None,
+                comment: Some("test want".to_string()),
+            }
+        }
+    }
+
+    /// Scenario 1
+    /// A test scenario that simulates a databuild application with 2 jobs, alpha and beta, with
+    /// alpha depending on a single output from beta, and beta with no deps.
+    fn setup_scenario_a_to_b(
+        mut orchestrator: Orchestrator<MemoryBELStorage>,
+    ) -> Orchestrator<MemoryBELStorage> {
+        // Define test jobs
+        orchestrator.config = OrchestratorConfig {
+            jobs: vec![
+                JobConfiguration {
+                    label: "alpha".to_string(),
+                    pattern: "data/alpha".to_string(),
+                    entry_point: MockJobRun::bin_path(),
+                },
+                JobConfiguration {
+                    label: "beta".to_string(),
+                    pattern: "data/beta".to_string(),
+                    entry_point: MockJobRun::bin_path(),
+                },
+            ],
+        };
+        orchestrator
+    }
+
    // The orchestrator needs to be able to actually execute job runs
    mod run_jobs {
        // Use case: the orchestrator should be able to execute a spawned-process job
@ -189,48 +412,243 @@ mod tests {
    // The orchestrator polls wants so that it can react to new wants created by users, or to wants
    // created by itself (for dep miss job run failures)
    mod poll_wants {
+        use crate::data_build_event::Event;
+        use crate::orchestrator::tests::{build_orchestrator, setup_scenario_a_to_b};
+        use crate::WantCreateEventV1;
+
        // Use case: Empty schedulable wants is a valid case, and should create no new jobs.
        #[test]
-        #[ignore]
        fn test_empty_wants_noop() {
-            todo!()
+            let mut orchestrator = build_orchestrator();
+            // Should init with no work to do
+            assert!(orchestrator.not_started_jobs.is_empty());
+            assert!(orchestrator.running_jobs.is_empty());
+            orchestrator
+                .poll_wants()
+                .expect("shouldn't fail to poll empty wants");
+            // Should still be empty since no work to do
+            assert!(orchestrator.not_started_jobs.is_empty());
+            assert!(orchestrator.running_jobs.is_empty());
        }

        // Use case: Some schedulable wants with jobs that can be matched should launch those jobs
        //  (but in this case using a noop/mock child process)
        #[test]
-        #[ignore]
        fn test_schedulable_wants_should_schedule() {
-            todo!()
+            // Given
+            let mut orchestrator = setup_scenario_a_to_b(build_orchestrator());
+            let events = vec![Event::WantCreateV1(WantCreateEventV1 {
+                partitions: vec!["data/alpha".into()],
+                ..WantCreateEventV1::sample()
+            })];
+            assert_eq!(orchestrator.bel.state.schedulable_wants().0.len(), 0);
+            for e in events {
+                orchestrator.bel.append_event(&e).expect("append");
+            }
+            assert_eq!(orchestrator.not_started_jobs.len(), 0);
+            assert_eq!(orchestrator.bel.state.count_job_runs(), 0);
+
+            // When
+            assert_eq!(orchestrator.bel.state.schedulable_wants().0.len(), 1);
+            orchestrator
+                .poll_wants()
+                .expect("shouldn't fail to poll wants");
+
+            // Should schedule alpha job
+            assert_eq!(orchestrator.not_started_jobs.len(), 1);
+            assert_eq!(
+                orchestrator
+                    .not_started_jobs
+                    .iter()
+                    .take(1)
+                    .last()
+                    .unwrap()
+                    .state
+                    .args,
+                vec!["data/alpha"],
+                "should have scheduled alpha job"
+            );
+            assert_eq!(orchestrator.bel.state.count_job_runs(), 1);
        }

        // Use case: A schedulable want that can't be matched to a job should return an error
        #[test]
-        #[ignore]
        fn test_schedulable_want_no_matching_job() {
-            todo!()
+            // Given
+            let mut orchestrator = build_orchestrator();
+            let events = vec![Event::WantCreateV1(WantCreateEventV1 {
+                partitions: vec!["data/alpha".into()],
+                ..WantCreateEventV1::sample()
+            })];
+
+            // When
+            orchestrator
+                .poll_wants()
+                .expect("shouldn't fail to poll wants");
+
+            // Should not have scheduled any jobs
+            assert_eq!(orchestrator.not_started_jobs.len(), 0);
        }
    }

-    // Orchestrator want creation is the means of data dependency propagation, allowing the
-    // orchestrator to create partitions needed by jobs that produce the existing wanted partitions.
+    /// Orchestrator want creation is the means of data dependency propagation, allowing the
+    /// orchestrator to create partitions needed by jobs that produce the existing wanted partitions.
    mod want_create {
-        // Use case: The orchestrator should map a failed job into a set of wants
+        use crate::data_build_event::Event;
+        use crate::job_run::{DepMissJobRun, SubProcessDepMiss};
+        use crate::orchestrator::tests::{build_orchestrator, setup_scenario_a_to_b};
+        use crate::{
+            JobRunBufferEventV1, MissingDeps, WantAttributedPartitions, WantCreateEventV1,
+        };
+        use std::marker::PhantomData;
+        use uuid::Uuid;
+
+        /// Use case: The orchestrator should map a failed job into a set of wants
        #[test]
-        #[ignore]
        fn test_job_fail_want_mapping() {
-            todo!()
+            // Given a
+            let mut orchestrator = setup_scenario_a_to_b(build_orchestrator());
+            // Add event for originating want
+            let want_create = WantCreateEventV1::sample();
+            let building_partitions = vec!["data/beta".into()];
+            orchestrator
+                .bel
+                .append_event(&Event::WantCreateV1(WantCreateEventV1 {
+                    partitions: building_partitions.clone(),
+                    ..want_create.clone()
+                }))
+                .expect("event append");
+            // Create failed job run detail
+            let want_attributed_partitions: Vec<WantAttributedPartitions> =
+                vec![want_create.clone().into()];
+            let job_run_id = Uuid::new_v4();
+            let job_run = JobRunBufferEventV1 {
+                job_run_id: job_run_id.into(),
+                building_partitions: building_partitions.clone(),
+                want_attributed_partitions: want_attributed_partitions.clone(),
+                ..JobRunBufferEventV1::default()
+            };
+            orchestrator
+                .bel
+                .append_event(&Event::JobRunBufferV1(job_run))
+                .expect("event append");
+
+            // Job runs should not be empty
+            orchestrator
+                .bel
+                .state
+                .get_job_run(&job_run_id.to_string())
+                .expect("job run should exist");
+
+            // Add event for job failure
+            let dep_miss_job_run = DepMissJobRun {
+                job_run_id,
+                state: SubProcessDepMiss {
+                    stdout_buffer: vec![],
+                    missing_deps: vec![MissingDeps {
+                        impacted: vec!["data/beta".into()],
+                        missing: vec!["data/alpha".into()],
+                    }],
+                    read_deps: vec![],
+                },
+                _backend: PhantomData,
+            };
+
+            // When calculating events from dep miss
+            // TODO this needs to be migrated - orchestrator shouldn't contain mapping logic
+            let events = orchestrator
+                .bel
+                .state
+                .dep_miss_to_events(&dep_miss_job_run)
+                .unwrap();
+
+            // Should have scheduled a job for alpha
+            assert_eq!(
+                events
+                    .iter()
+                    .filter(|e| match e {
+                        Event::WantCreateV1(e) => e.partitions.contains(&"data/alpha".into()),
+                        _ => false,
+                    })
+                    .count(),
+                1
+            );
+            assert!(
+                orchestrator.not_started_jobs.is_empty(),
+                "shouldn't have scheduled yet"
+            );
+
+            // Should schedule job after we poll wants
+            orchestrator.poll_wants().expect("poll wants");
+            assert_eq!(
+                orchestrator.not_started_jobs.len(),
+                1,
+                "should have scheduled job"
+            );
        }
    }

-    // Orchestrator needs to be able to achieve high level orchestration use cases.
+    /// Orchestrator needs to be able to achieve high level orchestration use cases.
    mod orchestration {
-        // Use case: should run a job to produce a partition in reaction to a want, then have the
-        // want fulfilled.
+        use crate::data_build_event::Event;
+        use crate::orchestrator::tests::{build_orchestrator, setup_scenario_a_to_b};
+        use crate::{PartitionStatusCode, WantCreateEventV1};
+        use std::thread;
+        use std::time::Duration;
+
+        /// Use case: should run a job to produce a partition in reaction to a want, then have the
+        /// want fulfilled.
        #[test]
-        #[ignore]
        fn test_want_builds_partition() {
-            todo!()
+            // Given
+            let mut orchestrator = setup_scenario_a_to_b(build_orchestrator());
+            // Add event for originating want
+            let partition = "data/alpha";
+            orchestrator
+                .bel
+                .append_event(&Event::WantCreateV1(WantCreateEventV1 {
+                    partitions: vec![partition.into()],
+                    ..WantCreateEventV1::sample()
+                }))
+                .expect("event append");
+
+            // When
+            // Poll wants then schedule pending jobs
+            orchestrator.poll_wants().expect("stage unscheduled jobs based on wants failed");
+            assert_eq!(orchestrator.not_started_jobs.len(), 1);
+            // poll job runs should start job run
+            orchestrator.poll_job_runs().expect("should start run");
+            assert_eq!(orchestrator.running_jobs.len(), 1);
+            assert_eq!(orchestrator.bel.state.count_job_runs(), 1);
+            thread::sleep(Duration::from_millis(1));
+            // Should still be running after 1ms
+            orchestrator.poll_job_runs().expect("should still be running");
+            assert_eq!(orchestrator.running_jobs.len(), 1);
+            assert_eq!(orchestrator.bel.state.count_job_runs(), 1);
+            println!("STATE: {:?}", orchestrator.bel.state);
+
+            // Wait for it to complete
+            thread::sleep(Duration::from_millis(10));
+            orchestrator.poll_job_runs().expect("should be able to poll existing job run");
+
+            // Job run should have succeeded
+            assert!(orchestrator.not_started_jobs.is_empty());
+            assert!(orchestrator.failed_jobs.is_empty());
+            assert!(orchestrator.dep_miss_jobs.is_empty());
+            assert!(orchestrator.running_jobs.is_empty());
+            assert_eq!(orchestrator.completed_jobs.len(), 1);
+
+            // Build state should show partition as live
+            assert_eq!(
+                orchestrator
+                    .bel
+                    .state
+                    .get_partition(partition)
+                    .unwrap()
+                    .status,
+                Some(PartitionStatusCode::PartitionLive.into()),
+                "partition should be live after job run completion"
+            );
        }

        // Use case: a graph with multi-hop deps should achieve the multi-hop build
@ -258,7 +676,7 @@ mod tests {
            JobConfiguration {
                label: label.to_string(),
                pattern: pattern.to_string(),
-                entrypoint: "test_entrypoint".to_string(),
+                entry_point: "test_entrypoint".to_string(),
            }
        }

@ -271,6 +689,7 @@ mod tests {
                        r#ref: r.to_string(),
                    })
                    .collect(),
+                upstreams: vec![],
                data_timestamp: 0,
                ttl_seconds: 0,
                sla_seconds: 0,
--- a/databuild/test/BUILD.bazel
+++ b/databuild/test/BUILD.bazel
@ -0,0 +1,14 @@
+load("@rules_rust//rust:defs.bzl", "rust_binary")
+
+rust_binary(
+    name = "test_job_helper",
+    srcs = ["test_job_helper.rs"],
+    visibility = ["//visibility:public"],
+)
+
+sh_test(
+    name = "test_job_helper_test",
+    srcs = ["test_job_helper_test.sh"],
+    args = ["$(location :test_job_helper)"],
+    data = [":test_job_helper"],
+)
--- a/databuild/test/test_job_helper.rs
+++ b/databuild/test/test_job_helper.rs
@ -0,0 +1,40 @@
+// Simple test helper binary for testing DataBuild job runs
+// Configurable via environment variables:
+// - DATABUILD_TEST_OUTPUT_FILE: Path to write a marker file
+// - DATABUILD_TEST_EXIT_CODE: Exit code to return (default: 0)
+// - DATABUILD_TEST_STDOUT: Message to write to stdout (default: "test executed")
+// - DATABUILD_TEST_SLEEP_MS: Milliseconds to sleep before exiting (default: 0)
+
+use std::env;
+use std::fs;
+use std::thread;
+use std::time::Duration;
+
+fn main() {
+    // Optional: sleep for testing long-running jobs
+    if let Ok(sleep_ms) = env::var("DATABUILD_TEST_SLEEP_MS") {
+        if let Ok(ms) = sleep_ms.parse::<u64>() {
+            thread::sleep(Duration::from_millis(ms));
+        }
+    }
+
+    // Write to stdout (for capturing output)
+    let stdout_msg = env::var("DATABUILD_TEST_STDOUT")
+        .unwrap_or_else(|_| "test executed".to_string());
+    println!("{}", stdout_msg);
+
+    // Optionally write to a file (for verifying execution)
+    if let Ok(output_file) = env::var("DATABUILD_TEST_OUTPUT_FILE") {
+        let content = env::var("DATABUILD_TEST_FILE_CONTENT")
+            .unwrap_or_else(|_| "test executed".to_string());
+        fs::write(output_file, content).expect("Failed to write output file");
+    }
+
+    // Exit with configured exit code
+    let exit_code = env::var("DATABUILD_TEST_EXIT_CODE")
+        .ok()
+        .and_then(|s| s.parse().ok())
+        .unwrap_or(0);
+
+    std::process::exit(exit_code);
+}
--- a/databuild/test/test_job_helper_test.sh
+++ b/databuild/test/test_job_helper_test.sh
@ -0,0 +1,46 @@
+#!/bin/bash
+set -e
+
+HELPER="$1"
+
+# Test 1: Default behavior - exit code 0, default stdout
+OUTPUT=$("$HELPER")
+if [ "$OUTPUT" != "test executed" ]; then
+    echo "Test 1 failed: Expected 'test executed', got '$OUTPUT'"
+    exit 1
+fi
+echo "Test 1 passed: Default stdout"
+
+# Test 2: Custom exit code
+DATABUILD_TEST_EXIT_CODE=42 "$HELPER" || EXIT_CODE=$?
+if [ "$EXIT_CODE" != "42" ]; then
+    echo "Test 2 failed: Expected exit code 42, got $EXIT_CODE"
+    exit 1
+fi
+echo "Test 2 passed: Custom exit code"
+
+# Test 3: Custom stdout message
+OUTPUT=$(DATABUILD_TEST_STDOUT="custom message" "$HELPER")
+if [ "$OUTPUT" != "custom message" ]; then
+    echo "Test 3 failed: Expected 'custom message', got '$OUTPUT'"
+    exit 1
+fi
+echo "Test 3 passed: Custom stdout"
+
+# Test 4: Write to file
+TEMP_FILE=$(mktemp)
+DATABUILD_TEST_OUTPUT_FILE="$TEMP_FILE" DATABUILD_TEST_FILE_CONTENT="hello world" "$HELPER" > /dev/null
+if [ ! -f "$TEMP_FILE" ]; then
+    echo "Test 4 failed: Output file not created"
+    exit 1
+fi
+CONTENT=$(cat "$TEMP_FILE")
+if [ "$CONTENT" != "hello world" ]; then
+    echo "Test 4 failed: Expected 'hello world' in file, got '$CONTENT'"
+    rm "$TEMP_FILE"
+    exit 1
+fi
+rm "$TEMP_FILE"
+echo "Test 4 passed: Write to file"
+
+echo "All tests passed!"
--- a/databuild/util.rs
+++ b/databuild/util.rs
@ -1,7 +1,75 @@
 use std::time::{SystemTime, UNIX_EPOCH};
+use std::backtrace::Backtrace;

 pub fn current_timestamp() -> u64 {
    let now = SystemTime::now();
    let duration_since_epoch = now.duration_since(UNIX_EPOCH).expect("Time went backwards");
    duration_since_epoch.as_nanos() as u64
 }
+
+fn maybe_backtrace() -> Backtrace {
+    if std::env::var("RUST_BACKTRACE").is_ok() {
+        Backtrace::force_capture()
+    } else {
+        Backtrace::disabled()
+    }
+}
+
+#[derive(Debug)]
+pub struct DatabuildError {
+    msg: String,
+    source: Option<Box<dyn std::error::Error + Send + Sync>>,
+    backtrace: Backtrace,
+}
+
+impl DatabuildError {
+    fn new(msg: impl Into<String>) -> Self {
+        Self {
+            msg: msg.into(),
+            source: None,
+            backtrace: maybe_backtrace()
+        }
+    }
+}
+
+impl From<std::io::Error> for DatabuildError {
+    fn from(err: std::io::Error) -> Self {
+        Self {
+            msg: err.to_string(),
+            source: Some(Box::new(err)),
+            backtrace: maybe_backtrace()
+        }
+    }
+}
+
+impl From<rusqlite::Error> for DatabuildError {
+    fn from(err: rusqlite::Error) -> Self {
+        Self {
+            msg: err.to_string(),
+            source: Some(Box::new(err)),
+            backtrace: maybe_backtrace()
+        }
+    }
+}
+
+impl From<prost::EncodeError> for DatabuildError {
+    fn from(err: prost::EncodeError) -> Self {
+        Self {
+            msg: err.to_string(),
+            source: Some(Box::new(err)),
+            backtrace: maybe_backtrace()
+        }
+    }
+}
+
+impl From<String> for DatabuildError {
+    fn from(value: String) -> Self {
+        Self::new(value)
+    }
+}
+
+impl std::fmt::Display for DatabuildError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "{}", self.msg)
+    }
+}
--- a/docs/ideas/metadata.md
+++ b/docs/ideas/metadata.md
@ -0,0 +1,2 @@
+
+It would be cool to have user-defined partition/want/job-run metadata, and allow querying of this metadata. Basic example: adding a `run_url` to a job or `adls_location` to a partition. More advanced: adding a `dbx_cores` field to job runs, and using querying over job runs downstream from a want to control parallelism down to the number-of-cores-used level.
--- a/docs/ideas/querying.md
+++ b/docs/ideas/querying.md
@ -0,0 +1,16 @@
+
+Querying seems to be a fundamental factor of the problem. For instance:
+
+- Upon canceling a want, canceling all wants it spawned, and the jobs attached to them.
+- Answering the question, "what in-progress job runs were spawned by this want?"
+- Answering, "why was this partition built?"
+- Answering, "what partitions needed to be built and jobs run to fulfill this want?"
+- Answering, "what jobs produce the partitions missed by this job run?"
+
+Let's start prefixing functions that should probably be mostly queries with `query_`.
+
+
+Notes on JTBDs and queries:
+
+- When a want is schedulable (query), map the requested partitions to the job runs that create them (query), and start them
+- 
--- a/scripts/generate_cargo_toml.py
+++ b/scripts/generate_cargo_toml.py
@ -129,40 +129,6 @@ def parse_crate_specs(module_content):
            crates[package] = crate_info

    return crates
-    """Extract crate specifications from MODULE.bazel content."""
-    crates = {}
-
-    # Find all crate.spec() calls
-    spec_pattern = r'crate\.spec\(\s*(.*?)\s*\)'
-    specs = re.findall(spec_pattern, module_content, re.DOTALL)
-
-    for spec in specs:
-        # Parse the spec parameters
-        package_match = re.search(r'package\s*=\s*"([^"]+)"', spec)
-        version_match = re.search(r'version\s*=\s*"([^"]+)"', spec)
-        features_match = re.search(r'features\s*=\s*\[(.*?)\]', spec, re.DOTALL)
-        default_features_match = re.search(r'default_features\s*=\s*False', spec)
-
-        if package_match and version_match:
-            package = package_match.group(1)
-            version = version_match.group(1)
-
-            crate_info = {"version": version}
-
-            # Handle features
-            if features_match:
-                features_str = features_match.group(1)
-                features = [f.strip().strip('"') for f in features_str.split(',') if f.strip()]
-                if features:
-                    crate_info["features"] = features
-
-            # Handle default-features = false
-            if default_features_match:
-                crate_info["default-features"] = False
-
-            crates[package] = crate_info
-
-    return crates

 def generate_cargo_toml(crates, structure, project_name="databuild"):
    """Generate Cargo.toml content from parsed crates and project structure."""
@ -170,7 +136,7 @@ def generate_cargo_toml(crates, structure, project_name="databuild"):
        f'[package]',
        f'name = "{project_name}"',
        f'version = "0.1.0"',
-        f'edition = "2021"',
+        f'edition = "2024"',
        f'',
        f'# Generated from MODULE.bazel for IDE support only',
        f'# Actual dependencies are managed by Bazel',
Author	SHA1	Message	Date
Stuart Axelbrooke	2cf778a07b	big bump Some checks failed / setup (push) Has been cancelled Details	2025-11-16 22:21:56 -08:00
Stuart Axelbrooke	5361e295e0	impl test_job_fail_want_mapping	2025-10-20 09:04:22 -07:00
Stuart Axelbrooke	75ef722a2c	impl test_schedulable_want_no_matching_job	2025-10-20 08:06:06 -07:00
Stuart Axelbrooke	bbeceaa015	add tests for want propagation, update dep read/miss reporting	2025-10-20 07:51:50 -07:00
Stuart Axelbrooke	1bca863be1	impl want propagation in orchestrator	2025-10-16 22:28:42 -07:00
Stuart Axelbrooke	3f223829bb	impl dep miss in job run	2025-10-16 20:30:11 -07:00
Stuart Axelbrooke	aa2106ad8c	impl dep miss state in job runs	2025-10-16 19:55:50 -07:00
Stuart Axelbrooke	2cd2ce7f7d	impl log line parsing	2025-10-16 19:36:04 -07:00
Stuart Axelbrooke	9559a410d3	impl log line parsing	2025-10-16 19:33:18 -07:00
Stuart Axelbrooke	cb580f83eb	lay groundwork for log line parsing	2025-10-16 19:27:42 -07:00
Stuart Axelbrooke	1f4138ecc0	little tweak to job run constructor	2025-10-16 18:53:51 -07:00
Stuart Axelbrooke	eeb90d0386	refactor top level job run interface to represent job states as states	2025-10-16 18:47:23 -07:00
Stuart Axelbrooke	6572d4e3bd	refactor job run state to separate state types	2025-10-16 18:19:24 -07:00
Stuart Axelbrooke	cfcb201285	implement job canceling	2025-10-16 17:54:30 -07:00
Stuart Axelbrooke	7debea96a2	implement simple job succeeds and job fails tests for job run	2025-10-14 20:37:03 -07:00
Stuart Axelbrooke	fa5a5fa200	integrate test bin and get failing first job run test	2025-10-14 20:08:35 -07:00
Stuart Axelbrooke	d7fb2323d8	add more job run details	2025-10-14 19:54:03 -07:00
Stuart Axelbrooke	ea85af4d2b	add test binary tests	2025-10-14 19:32:15 -07:00
Stuart Axelbrooke	bea9616227	add test binary	2025-10-13 19:49:48 -07:00
Stuart Axelbrooke	873f766aa0	add job run basics	2025-10-13 19:38:12 -07:00
Stuart Axelbrooke	bc61d8f530	partition schedulability	2025-10-13 13:29:04 -07:00
Stuart Axelbrooke	ac567240ea	Add design notes for build state	2025-10-12 13:44:25 -07:00
				`@ -0,0 +1,2 @@`

				It would be cool to have user-defined partition/want/job-run metadata, and allow querying of this metadata. Basic example: adding a `run_url` to a job or `adls_location` to a partition. More advanced: adding a `dbx_cores` field to job runs, and using querying over job runs downstream from a want to control parallelism down to the number-of-cores-used level.