fix: Persist and expose task dependencies from detail output

Detail agents define task dependencies in YAML frontmatter but they were
silently dropped — never written to the task_dependencies table. This
caused all tasks to dispatch in parallel regardless of intended ordering,
and the frontend showed no dependency information.

- Add fileIdToDbId mapping and second-pass dependency creation in
  output-handler.ts (mirrors existing phase dependency pattern)
- Add task_dependency to changeset entry entityType enum
- Add listPhaseTaskDependencies tRPC procedure for batch querying
- Wire blockedBy in PhaseDetailPanel and PhaseWithTasks from real data
- Clarify dependency semantics in detail prompt

apps/web/src/components/execution/PhaseDetailPanel.tsx

@@ -119,6 +119,23 @@ export function PhaseDetailPanel({
   const depsQuery = trpc.getPhaseDependencies.useQuery({ phaseId: phase.id });
   const dependencyIds = depsQuery.data?.dependencies ?? [];
 
+  // Task-level dependencies
+  const taskDepsQuery = trpc.listPhaseTaskDependencies.useQuery({ phaseId: phase.id });
+  const taskDepsMap = useMemo(() => {
+    const map = new Map<string, Array<{ name: string; status: string }>>();
+    const edges = taskDepsQuery.data ?? [];
+    for (const edge of edges) {
+      const blockers = edge.dependsOn
+        .map((depId) => {
+          const t = tasks.find((tk) => tk.id === depId);
+          return t ? { name: t.name, status: t.status } : null;
+        })
+        .filter(Boolean) as Array<{ name: string; status: string }>;
+      if (blockers.length > 0) map.set(edge.taskId, blockers);
+    }
+    return map;
+  }, [taskDepsQuery.data, tasks]);
+
   // Resolve dependency IDs to phase objects
   const resolvedDeps = dependencyIds
     .map((depId) => phases.find((p) => p.id === depId))
@@ -139,11 +156,11 @@ export function PhaseDetailPanel({
       task,
       phaseName: `Phase ${displayIndex}: ${phase.name}`,
       agentName: null,
-      blockedBy: [],
+      blockedBy: taskDepsMap.get(task.id) ?? [],
       dependents: [],
     }));
     handleRegisterTasks(phase.id, entries);
-  }, [tasks, phase.id, displayIndex, phase.name, handleTaskCounts, handleRegisterTasks]);
+  }, [tasks, phase.id, displayIndex, phase.name, handleTaskCounts, handleRegisterTasks, taskDepsMap]);
 
   // --- Change sets for detail agent ---
   const changeSetsQuery = trpc.listChangeSets.useQuery(
@@ -379,7 +396,7 @@ export function PhaseDetailPanel({
                 key={task.id}
                 task={task}
                 agentName={null}
-                blockedBy={[]}
+                blockedBy={taskDepsMap.get(task.id) ?? []}
                 isLast={idx === sortedTasks.length - 1}
                 onClick={() => setSelectedTaskId(task.id)}
                 onDelete={() => deleteTask.mutate({ id: task.id })}

apps/web/src/components/execution/PhaseWithTasks.tsx

@@ -1,4 +1,4 @@
-import { useEffect } from "react";
+import { useEffect, useMemo } from "react";
 import { trpc } from "@/lib/trpc";
 import { PhaseAccordion } from "@/components/PhaseAccordion";
 import type { SerializedTask } from "@/components/TaskRow";
@@ -30,6 +30,7 @@ export function PhaseWithTasks({
 }: PhaseWithTasksProps) {
   const tasksQuery = trpc.listPhaseTasks.useQuery({ phaseId: phase.id });
   const depsQuery = trpc.getPhaseDependencies.useQuery({ phaseId: phase.id });
+  const taskDepsQuery = trpc.listPhaseTaskDependencies.useQuery({ phaseId: phase.id });
 
   const tasks = tasksQuery.data ?? [];
 
@@ -39,6 +40,7 @@ export function PhaseWithTasks({
       tasks={tasks}
       tasksLoaded={tasksQuery.isSuccess}
       phaseDependencyIds={depsQuery.data?.dependencies ?? []}
+      taskDependencyEdges={taskDepsQuery.data ?? []}
       defaultExpanded={defaultExpanded}
       onTaskClick={onTaskClick}
       onTaskCounts={onTaskCounts}
@@ -52,6 +54,7 @@ interface PhaseWithTasksInnerProps {
   tasks: SerializedTask[];
   tasksLoaded: boolean;
   phaseDependencyIds: string[];
+  taskDependencyEdges: Array<{ taskId: string; dependsOn: string[] }>;
   defaultExpanded: boolean;
   onTaskClick: (taskId: string) => void;
   onTaskCounts: (phaseId: string, counts: TaskCounts) => void;
@@ -63,11 +66,27 @@ function PhaseWithTasksInner({
   tasks,
   tasksLoaded,
   phaseDependencyIds: _phaseDependencyIds,
+  taskDependencyEdges,
   defaultExpanded,
   onTaskClick,
   onTaskCounts,
   registerTasks,
 }: PhaseWithTasksInnerProps) {
+  // Build task dependency map
+  const taskDepsMap = useMemo(() => {
+    const map = new Map<string, Array<{ name: string; status: string }>>();
+    for (const edge of taskDependencyEdges) {
+      const blockers = edge.dependsOn
+        .map((depId) => {
+          const t = tasks.find((tk) => tk.id === depId);
+          return t ? { name: t.name, status: t.status } : null;
+        })
+        .filter(Boolean) as Array<{ name: string; status: string }>;
+      if (blockers.length > 0) map.set(edge.taskId, blockers);
+    }
+    return map;
+  }, [taskDependencyEdges, tasks]);
+
   // Propagate task counts and entries
   useEffect(() => {
     const complete = tasks.filter(
@@ -79,17 +98,17 @@ function PhaseWithTasksInner({
       task,
       phaseName: phase.name,
       agentName: null,
-      blockedBy: [],
+      blockedBy: taskDepsMap.get(task.id) ?? [],
       dependents: [],
     }));
     registerTasks(phase.id, entries);
-  }, [tasks, phase.id, phase.name, onTaskCounts, registerTasks]);
+  }, [tasks, phase.id, phase.name, onTaskCounts, registerTasks, taskDepsMap]);
 
   const sortedTasks = sortByPriorityAndQueueTime(tasks);
   const taskEntries = sortedTasks.map((task) => ({
     task,
     agentName: null as string | null,
-    blockedBy: [] as Array<{ name: string; status: string }>,
+    blockedBy: taskDepsMap.get(task.id) ?? [] as Array<{ name: string; status: string }>,
   }));
 
   const phaseDeps: Array<{ name: string; status: string }> = [];