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/server/agent/output-handler.ts

@@ -498,6 +498,7 @@ export class OutputHandler {
           const phaseInput = readFrontmatterFile(join(agentWorkdir, '.cw', 'input', 'phase.md'));
           const phaseId = (phaseInput?.data?.id as string) ?? null;
           const entries: CreateChangeSetEntryData[] = [];
+          const fileIdToDbId = new Map<string, string>();
 
           // Load existing tasks for dedup — prevents duplicates when multiple agents finish concurrently
           const existingTasks = phaseId ? await this.taskRepository.findByPhaseId(phaseId) : [];
@@ -506,6 +507,9 @@ export class OutputHandler {
           for (const [i, t] of tasks.entries()) {
             if (existingNames.has(t.title)) {
               log.info({ agentId, task: t.title, phaseId }, 'skipped duplicate task');
+              // Map deduped file ID to existing DB ID for dependency resolution
+              const existing = existingTasks.find(et => et.name === t.title);
+              if (existing) fileIdToDbId.set(t.id, existing.id);
               continue;
             }
             try {
@@ -518,6 +522,7 @@ export class OutputHandler {
                 category: (t.category as any) ?? 'execute',
                 type: (t.type as any) ?? 'auto',
               });
+              fileIdToDbId.set(t.id, created.id);
               existingNames.add(t.title); // prevent dupes within same agent output
               entries.push({
                 entityType: 'task',
@@ -536,6 +541,29 @@ export class OutputHandler {
             }
           }
 
+          // Second pass: create task dependencies
+          let depSortOrder = entries.length;
+          for (const t of tasks) {
+            const taskDbId = fileIdToDbId.get(t.id);
+            if (!taskDbId || t.dependencies.length === 0) continue;
+            for (const depFileId of t.dependencies) {
+              const depDbId = fileIdToDbId.get(depFileId);
+              if (!depDbId) continue;
+              try {
+                await this.taskRepository.createDependency(taskDbId, depDbId);
+                entries.push({
+                  entityType: 'task_dependency',
+                  entityId: `${taskDbId}:${depDbId}`,
+                  action: 'create',
+                  newState: JSON.stringify({ taskId: taskDbId, dependsOnTaskId: depDbId }),
+                  sortOrder: depSortOrder++,
+                });
+              } catch (err) {
+                log.warn({ agentId, taskDbId, depFileId, err: err instanceof Error ? err.message : String(err) }, 'failed to create task dependency');
+              }
+            }
+          }
+
           if (entries.length > 0) {
             try {
               const cs = await this.changeSetRepository!.createWithEntries({

apps/server/agent/prompts/detail.ts

@@ -13,7 +13,7 @@ ${CODEBASE_EXPLORATION}
 
 <output_format>
 Write one file per task to \`.cw/output/tasks/{id}.md\`:
-- Frontmatter: \`title\`, \`category\` (execute|research|discuss|plan|detail|refine|verify|merge|review), \`type\` (auto|checkpoint:human-verify|checkpoint:decision|checkpoint:human-action), \`dependencies\` (list of task IDs)
+- Frontmatter: \`title\`, \`category\` (execute|research|discuss|plan|detail|refine|verify|merge|review), \`type\` (auto|checkpoint:human-verify|checkpoint:decision|checkpoint:human-action), \`dependencies\` (list of task IDs that must complete before this task can start)
 - Body: Detailed task description
 </output_format>
 
@@ -59,6 +59,7 @@ Parallel tasks must not modify the same files. Include a file list per task:
 Files: src/db/schema/users.ts (create), src/db/migrations/001_users.sql (create)
 \`\`\`
 If two tasks touch the same file or one needs the other's output, add a dependency.
+Tasks with no dependencies run in parallel. Add a dependency when one task needs another's output or modifies the same files.
 </file_ownership>
 
 <task_sizing>

apps/server/db/repositories/change-set-repository.ts

@@ -16,7 +16,7 @@ export type CreateChangeSetData = {
 };
 
 export type CreateChangeSetEntryData = {
-  entityType: 'page' | 'phase' | 'task' | 'phase_dependency';
+  entityType: 'page' | 'phase' | 'task' | 'phase_dependency' | 'task_dependency';
   entityId: string;
   action: 'create' | 'update' | 'delete';
   previousState?: string | null;

apps/server/db/schema.ts

@@ -339,7 +339,7 @@ export const changeSetEntries = sqliteTable('change_set_entries', {
   changeSetId: text('change_set_id')
     .notNull()
     .references(() => changeSets.id, { onDelete: 'cascade' }),
-  entityType: text('entity_type', { enum: ['page', 'phase', 'task', 'phase_dependency'] }).notNull(),
+  entityType: text('entity_type', { enum: ['page', 'phase', 'task', 'phase_dependency', 'task_dependency'] }).notNull(),
   entityId: text('entity_id').notNull(),
   action: text('action', { enum: ['create', 'update', 'delete'] }).notNull(),
   previousState: text('previous_state'), // JSON snapshot, null for creates

apps/server/trpc/routers/task.ts

@@ -151,6 +151,19 @@ export function taskProcedures(publicProcedure: ProcedureBuilder) {
         return { success: true };
       }),
 
+    listPhaseTaskDependencies: publicProcedure
+      .input(z.object({ phaseId: z.string().min(1) }))
+      .query(async ({ ctx, input }) => {
+        const taskRepo = requireTaskRepository(ctx);
+        const tasks = await taskRepo.findByPhaseId(input.phaseId);
+        const edges: Array<{ taskId: string; dependsOn: string[] }> = [];
+        for (const t of tasks) {
+          const deps = await taskRepo.getDependencies(t.id);
+          if (deps.length > 0) edges.push({ taskId: t.id, dependsOn: deps });
+        }
+        return edges;
+      }),
+
     approveTask: publicProcedure
       .input(z.object({ taskId: z.string().min(1) }))
       .mutation(async ({ ctx, input }) => {

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 }> = [];

docs/agent.md

@@ -9,7 +9,7 @@
 | `types.ts` | Core types: `AgentInfo`, `AgentManager` interface, `SpawnOptions`, `StreamEvent` |
 | `manager.ts` | `MultiProviderAgentManager` — main orchestrator class |
 | `process-manager.ts` | `AgentProcessManager` — worktree creation, command building, detached spawn |
-| `output-handler.ts` | `OutputHandler` — JSONL stream parsing, completion detection, proposal creation, task dedup |
+| `output-handler.ts` | `OutputHandler` — JSONL stream parsing, completion detection, proposal creation, task dedup, task dependency persistence |
 | `file-tailer.ts` | `FileTailer` — watches output files, fires parser + raw content callbacks |
 | `file-io.ts` | Input/output file I/O: frontmatter writing, signal.json reading, tiptap conversion |
 | `markdown-to-tiptap.ts` | Markdown to Tiptap JSON conversion using MarkdownManager |

docs/server-api.md

@@ -79,6 +79,7 @@ Each procedure uses `require*Repository(ctx)` helpers that throw `TRPCError(INTE
 | listPhaseTasks | query | All tasks for phase |
 | listPendingApprovals | query | Tasks with status=pending_approval |
 | deleteTask | mutation | Delete a task by ID |
+| listPhaseTaskDependencies | query | All task dependency edges for tasks in a phase |
 | approveTask | mutation | Approve and complete task |
 
 ### Initiatives