add mermaid lineage chart for wants

databuild/http_server.rs

@@ -1,6 +1,7 @@
 use crate::build_event_log::BELStorage;
 use crate::build_state::BuildState;
 use crate::commands::Command;
+use crate::lineage::build_lineage_graph;
 use crate::web::templates::{
     BaseContext, DerivativeWantView, HomePage, JobRunDetailPage, JobRunDetailView, JobRunsListPage,
     PartitionDetailPage, PartitionDetailView, PartitionsListPage, WantCreatePage, WantDetailPage,
@@ -268,9 +269,12 @@ async fn want_detail_page(
                 .map(|w| DerivativeWantView::from(&w))
                 .collect();
 
+            // Build lineage graph (up to 3 generations)
+            let lineage_mermaid = build_lineage_graph(&build_state, &want.want_id, 3).to_mermaid();
+
             let template = WantDetailPage {
                 base: BaseContext::default(),
-                want: WantDetailView::new(&want, derivative_wants),
+                want: WantDetailView::new(&want, derivative_wants, lineage_mermaid),
             };
             match template.render() {
                 Ok(html) => Html(html).into_response(),

databuild/lib.rs

@@ -9,6 +9,7 @@ pub mod http_server;
 mod job;
 mod job_run;
 mod job_run_state;
+pub mod lineage;
 mod mock_job_run;
 pub mod orchestrator;
 mod partition_state;

databuild/lineage.rs

@@ -0,0 +1,381 @@
+//! Lineage graph generation for visualizing want → partition → job run dependencies.
+//!
+//! This module provides functionality for building Mermaid flowcharts that show
+//! the dependency relationships between wants, partitions, and job runs.
+
+use crate::build_state::BuildState;
+use std::collections::HashSet;
+
+// =============================================================================
+// Lineage Graph Data Structures
+// =============================================================================
+
+/// Node types in the lineage graph
+#[derive(Debug, Clone, PartialEq, Eq)]
+pub enum LineageNodeType {
+    Want,
+    Partition,
+    JobRun,
+}
+
+/// A node in the lineage graph
+#[derive(Debug, Clone)]
+pub struct LineageNode {
+    pub id: String,
+    pub label: String,
+    pub node_type: LineageNodeType,
+    pub status_color: String,
+    pub url: String,
+}
+
+/// An edge in the lineage graph
+#[derive(Debug, Clone)]
+pub struct LineageEdge {
+    pub from: String,
+    pub to: String,
+    pub dashed: bool,
+}
+
+/// A directed graph representing want/partition/job run lineage
+#[derive(Debug, Clone, Default)]
+pub struct LineageGraph {
+    pub nodes: Vec<LineageNode>,
+    pub edges: Vec<LineageEdge>,
+}
+
+impl LineageGraph {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn add_node(&mut self, node: LineageNode) {
+        // Only add if not already present
+        if !self.nodes.iter().any(|n| n.id == node.id) {
+            self.nodes.push(node);
+        }
+    }
+
+    pub fn add_edge(&mut self, from: String, to: String, dashed: bool) {
+        let edge = LineageEdge { from, to, dashed };
+        // Only add if not already present
+        if !self
+            .edges
+            .iter()
+            .any(|e| e.from == edge.from && e.to == edge.to)
+        {
+            self.edges.push(edge);
+        }
+    }
+
+    /// Generate Mermaid flowchart syntax
+    pub fn to_mermaid(&self) -> String {
+        let mut lines = vec!["flowchart TD".to_string()];
+
+        // Add nodes with labels and shapes
+        for node in &self.nodes {
+            let shape = match node.node_type {
+                LineageNodeType::Want => format!("{}[\"🎯 {}\"]", node.id, node.label),
+                LineageNodeType::Partition => format!("{}[/\"📦 {}\"/]", node.id, node.label),
+                LineageNodeType::JobRun => format!("{}([\"⚙️ {}\"])", node.id, node.label),
+            };
+            lines.push(format!("    {}", shape));
+        }
+
+        lines.push(String::new());
+
+        // Add edges
+        for edge in &self.edges {
+            let arrow = if edge.dashed { "-.->" } else { "-->" };
+            lines.push(format!("    {} {} {}", edge.from, arrow, edge.to));
+        }
+
+        lines.push(String::new());
+
+        // Add styles for status colors
+        for node in &self.nodes {
+            if !node.status_color.is_empty() {
+                lines.push(format!("    style {} fill:{}", node.id, node.status_color));
+            }
+        }
+
+        lines.push(String::new());
+
+        // Add click handlers for navigation
+        for node in &self.nodes {
+            if !node.url.is_empty() {
+                lines.push(format!("    click {} \"{}\"", node.id, node.url));
+            }
+        }
+
+        lines.join("\n")
+    }
+}
+
+// =============================================================================
+// Status Color Mapping
+// =============================================================================
+
+/// Map status names to colors for the lineage graph.
+/// Status names are matched case-insensitively against proto-generated enum names.
+pub fn status_to_color(status_name: &str) -> &'static str {
+    match status_name.to_lowercase().as_str() {
+        "wantsuccessful" | "partitionlive" | "jobrunsucceeded" => "#dcfce7", // green
+        "wantbuilding" | "partitionbuilding" | "jobrunrunning" => "#ede9fe", // blue
+        "wantidle" | "jobrunqueued" => "#9ca3af",                            // gray
+        "wantfailed" | "partitionfailed" | "jobrunfailed" => "#fee2e2;",     // red
+        "wantdepmiss" | "jobrundepmiss" => "#fef3e2",                        // orange
+        "wantupstreamfailed" | "partitionupstreamfailed" => "#fee2e2",       // red
+        "wantupstreambuilding" | "partitionupstreambuilding" => "#a855f7",   // purple
+        "wantcanceled" | "jobruncanceled" => "#6b7280",                      // dark gray
+        _ => "#e5e7eb",                                                      // light gray default
+    }
+}
+
+// =============================================================================
+// Graph Builder
+// =============================================================================
+
+/// Build a lineage graph starting from a want, traversing up to `max_depth` generations.
+/// The graph shows: Want -> Partitions -> JobRuns -> DerivativeWants -> ...
+pub fn build_lineage_graph(
+    build_state: &BuildState,
+    want_id: &str,
+    max_depth: usize,
+) -> LineageGraph {
+    let mut graph = LineageGraph::new();
+    let mut visited_wants: HashSet<String> = HashSet::new();
+
+    fn add_want_to_graph(
+        build_state: &BuildState,
+        graph: &mut LineageGraph,
+        visited_wants: &mut HashSet<String>,
+        want_id: &str,
+        depth: usize,
+        max_depth: usize,
+    ) {
+        if depth > max_depth || visited_wants.contains(want_id) {
+            return;
+        }
+        visited_wants.insert(want_id.to_string());
+
+        let Some(want) = build_state.get_want(want_id) else {
+            return;
+        };
+
+        // Create node ID (sanitize for mermaid)
+        let want_node_id = format!("W{}", sanitize_node_id(want_id));
+        let status_name = want.status.as_ref().map(|s| s.name.as_str()).unwrap_or("");
+
+        // Add want node
+        graph.add_node(LineageNode {
+            id: want_node_id.clone(),
+            label: truncate_label(want_id, 30),
+            node_type: LineageNodeType::Want,
+            status_color: status_to_color(status_name).to_string(),
+            url: format!("/wants/{}", want_id),
+        });
+
+        // Add partition nodes and edges from want to partitions
+        for partition in &want.partitions {
+            let partition_ref = &partition.r#ref;
+            let partition_node_id = format!("P{}", sanitize_node_id(partition_ref));
+
+            // Get partition status if available
+            let partition_status = build_state
+                .get_partition(partition_ref)
+                .and_then(|p| p.status)
+                .map(|s| s.name)
+                .unwrap_or_default();
+
+            graph.add_node(LineageNode {
+                id: partition_node_id.clone(),
+                label: truncate_label(partition_ref, 25),
+                node_type: LineageNodeType::Partition,
+                status_color: status_to_color(&partition_status).to_string(),
+                url: format!("/partitions/{}", urlencoding::encode(partition_ref)),
+            });
+
+            // Want -> Partition edge
+            graph.add_edge(want_node_id.clone(), partition_node_id.clone(), false);
+        }
+
+        // Add job run nodes and edges from partitions to job runs
+        for job_run in &want.job_runs {
+            let job_run_node_id = format!("JR{}", sanitize_node_id(&job_run.id));
+            let job_status_name = job_run
+                .status
+                .as_ref()
+                .map(|s| s.name.as_str())
+                .unwrap_or("");
+
+            // Use job_label if available, otherwise job_run_id
+            let job_label = if job_run.job_label.is_empty() {
+                &job_run.id
+            } else {
+                &job_run.job_label
+            };
+
+            graph.add_node(LineageNode {
+                id: job_run_node_id.clone(),
+                label: truncate_label(job_label, 25),
+                node_type: LineageNodeType::JobRun,
+                status_color: status_to_color(job_status_name).to_string(),
+                url: format!("/job_runs/{}", job_run.id),
+            });
+
+            // Connect partitions being built to this job run (dashed = building relationship)
+            for partition in &job_run.building_partitions {
+                let partition_node_id = format!("P{}", sanitize_node_id(&partition.r#ref));
+                graph.add_edge(partition_node_id, job_run_node_id.clone(), true);
+            }
+
+            // Recurse into derivative wants
+            for derivative_want_id in &job_run.derivative_want_ids {
+                add_want_to_graph(
+                    build_state,
+                    graph,
+                    visited_wants,
+                    derivative_want_id,
+                    depth + 1,
+                    max_depth,
+                );
+
+                // Add edge from job run to derivative want
+                let derivative_want_node_id = format!("W{}", sanitize_node_id(derivative_want_id));
+                graph.add_edge(job_run_node_id.clone(), derivative_want_node_id, false);
+            }
+        }
+    }
+
+    add_want_to_graph(
+        build_state,
+        &mut graph,
+        &mut visited_wants,
+        want_id,
+        0,
+        max_depth,
+    );
+
+    graph
+}
+
+/// Sanitize a string to be a valid mermaid node ID (alphanumeric + underscore only)
+pub fn sanitize_node_id(s: &str) -> String {
+    s.chars()
+        .map(|c| if c.is_alphanumeric() { c } else { '_' })
+        .collect()
+}
+
+/// Truncate a label to fit in the graph, adding ellipsis if needed
+pub fn truncate_label(s: &str, max_len: usize) -> String {
+    if s.len() <= max_len {
+        s.to_string()
+    } else {
+        format!("{}...", &s[..max_len - 3])
+    }
+}
+
+// =============================================================================
+// Tests
+// =============================================================================
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::build_state::BuildState;
+    use crate::util::test_scenarios::multihop_scenario;
+
+    /// Helper to replay events into a fresh BuildState
+    fn build_state_from_events(events: &[crate::data_build_event::Event]) -> BuildState {
+        let mut state = BuildState::default();
+        for event in events {
+            state.handle_event(event);
+        }
+        state
+    }
+
+    #[test]
+    fn test_lineage_graph_mermaid_generation() {
+        let mut graph = LineageGraph::new();
+
+        graph.add_node(LineageNode {
+            id: "W_beta_want".to_string(),
+            label: "beta-want".to_string(),
+            node_type: LineageNodeType::Want,
+            status_color: "#22c55e".to_string(),
+            url: "/wants/beta-want".to_string(),
+        });
+
+        graph.add_node(LineageNode {
+            id: "P_data_beta".to_string(),
+            label: "data/beta".to_string(),
+            node_type: LineageNodeType::Partition,
+            status_color: "#22c55e".to_string(),
+            url: "/partitions/data%2Fbeta".to_string(),
+        });
+
+        graph.add_node(LineageNode {
+            id: "JR_beta_job".to_string(),
+            label: "//job_beta".to_string(),
+            node_type: LineageNodeType::JobRun,
+            status_color: "#f97316".to_string(),
+            url: "/job_runs/beta-job".to_string(),
+        });
+
+        graph.add_edge("W_beta_want".to_string(), "P_data_beta".to_string(), false);
+        graph.add_edge("P_data_beta".to_string(), "JR_beta_job".to_string(), true);
+
+        let mermaid = graph.to_mermaid();
+
+        assert!(
+            mermaid.contains("flowchart TD"),
+            "Should have flowchart header"
+        );
+        assert!(mermaid.contains("W_beta_want"), "Should have want node");
+        assert!(
+            mermaid.contains("P_data_beta"),
+            "Should have partition node"
+        );
+        assert!(mermaid.contains("JR_beta_job"), "Should have job run node");
+        assert!(mermaid.contains("-->"), "Should have solid edge");
+        assert!(mermaid.contains("-.->"), "Should have dashed edge");
+        assert!(
+            mermaid.contains("style W_beta_want fill:#22c55e"),
+            "Should have status color"
+        );
+        assert!(
+            mermaid.contains("click W_beta_want"),
+            "Should have click handler"
+        );
+    }
+
+    #[test]
+    fn test_sanitize_node_id() {
+        assert_eq!(sanitize_node_id("data/beta"), "data_beta");
+        assert_eq!(sanitize_node_id("job-run-123"), "job_run_123");
+        assert_eq!(sanitize_node_id("simple"), "simple");
+    }
+
+    #[test]
+    fn test_truncate_label() {
+        assert_eq!(truncate_label("short", 10), "short");
+        assert_eq!(truncate_label("this is very long", 10), "this is...");
+    }
+
+    #[test]
+    fn test_build_lineage_graph_from_multihop_scenario() {
+        let (events, ids) = multihop_scenario();
+        let state = build_state_from_events(&events);
+
+        let graph = build_lineage_graph(&state, &ids.beta_want_id, 3);
+
+        // Should have nodes for beta want, alpha want, partitions, and job runs
+        assert!(!graph.nodes.is_empty(), "Graph should have nodes");
+        assert!(!graph.edges.is_empty(), "Graph should have edges");
+
+        // Check that the mermaid output is valid
+        let mermaid = graph.to_mermaid();
+        assert!(mermaid.contains("flowchart TD"));
+        assert!(mermaid.contains("beta_want") || mermaid.contains("beta"));
+    }
+}

databuild/web/templates.rs

@@ -126,12 +126,18 @@ pub struct WantDetailView {
     pub derivative_want_ids: Vec<String>,
     pub job_runs: Vec<JobRunDetailView>,
     pub derivative_wants: Vec<DerivativeWantView>,
+    /// Mermaid flowchart showing want -> partition -> job run -> derivative want lineage
+    pub lineage_mermaid: String,
 }
 
 impl WantDetailView {
-    /// Create a WantDetailView with derivative wants populated.
-    /// Use this for the detail page where derivative wants need to be shown.
-    pub fn new(w: &WantDetail, derivative_wants: Vec<DerivativeWantView>) -> Self {
+    /// Create a WantDetailView with derivative wants and lineage graph populated.
+    /// Use this for the detail page where full lineage information is shown.
+    pub fn new(
+        w: &WantDetail,
+        derivative_wants: Vec<DerivativeWantView>,
+        lineage_mermaid: String,
+    ) -> Self {
         use crate::want_detail::Lifetime;
 
         let (lifetime, data_timestamp, ttl_seconds, sla_seconds, is_ephemeral, source_job_run_id) =
@@ -179,14 +185,15 @@ impl WantDetailView {
             derivative_want_ids: w.derivative_want_ids.clone(),
             job_runs: w.job_runs.iter().map(JobRunDetailView::from).collect(),
             derivative_wants,
+            lineage_mermaid,
         }
     }
 }
 
-/// For list pages where derivative wants aren't needed
+/// For list pages where derivative wants and lineage aren't needed
 impl From<WantDetail> for WantDetailView {
     fn from(w: WantDetail) -> Self {
-        Self::new(&w, vec![])
+        Self::new(&w, vec![], String::new())
     }
 }
 
@@ -590,7 +597,7 @@ mod tests {
 
             let template = WantDetailPage {
                 base: BaseContext::default(),
-                want: WantDetailView::new(&want_detail, derivative_wants),
+                want: WantDetailView::new(&want_detail, derivative_wants, String::new()),
             };
             let html = template.render().expect("template should render");
 
@@ -601,5 +608,52 @@ mod tests {
                 html
             );
         }
+
+        /// Given: A want detail view with lineage mermaid content
+        /// When: We render the template
+        /// Then: The HTML should contain the mermaid diagram
+        #[test]
+        fn test_want_detail_page_shows_lineage_mermaid() {
+            let (events, ids) = multihop_scenario();
+            let state = build_state_from_events(&events);
+
+            let want_detail = state
+                .get_want(&ids.beta_want_id)
+                .expect("beta want should exist");
+
+            let derivative_wants: Vec<_> = want_detail
+                .derivative_want_ids
+                .iter()
+                .filter_map(|id| state.get_want(id))
+                .map(|w| DerivativeWantView::from(&w))
+                .collect();
+
+            // Create a simple lineage mermaid string
+            let lineage_mermaid = "flowchart TD\n    W[Want]\n    P[Partition]".to_string();
+
+            let template = WantDetailPage {
+                base: BaseContext::default(),
+                want: WantDetailView::new(&want_detail, derivative_wants, lineage_mermaid),
+            };
+            let html = template.render().expect("template should render");
+
+            // Verify lineage graph section is present
+            assert!(
+                html.contains("Lineage Graph"),
+                "Should have Lineage Graph section header"
+            );
+            assert!(
+                html.contains("class=\"mermaid\""),
+                "Should have mermaid pre element"
+            );
+            assert!(
+                html.contains("flowchart TD"),
+                "Should contain the mermaid content"
+            );
+            assert!(
+                html.contains("mermaid.esm.min.mjs"),
+                "Should include mermaid script"
+            );
+        }
     }
 }

databuild/web/templates/wants/detail.html

@@ -54,6 +54,17 @@
     </ul>
 </div>
 
+{% if !want.lineage_mermaid.is_empty() %}
+<div class="detail-section">
+    <h2>Lineage Graph</h2>
+    <div class="mermaid-container" style="background: var(--color-bg-secondary); border-radius: 8px; padding: 16px; overflow-x: auto; display: flex; justify-content: center;">
+        <pre class="mermaid" style="margin: 0;">
+{{ want.lineage_mermaid }}
+        </pre>
+    </div>
+</div>
+{% endif %}
+
 {% if !want.upstreams.is_empty() %}
 <div class="detail-section">
     <h2>Upstream Dependencies ({{ want.upstreams.len() }})</h2>
@@ -117,4 +128,20 @@
 </div>
 {% endif %}
 
+{% if !want.lineage_mermaid.is_empty() %}
+<script type="module">
+    import mermaid from 'https://cdn.jsdelivr.net/npm/mermaid@11/dist/mermaid.esm.min.mjs';
+    mermaid.initialize({
+        startOnLoad: true,
+        theme: 'neutral',
+        flowchart: {
+            useMaxWidth: true,
+            htmlLabels: true,
+            curve: 'basis'
+        },
+        securityLevel: 'loose'
+    });
+</script>
+{% endif %}
+
 {% call base::footer() %}