feat(FN-4080): complete Step 2 — route thinking persistence by agent kind

Fusion-Task-Id: FN-4080
Fusion-Task-Lineage: 086863ba-7100-41ab-9cfc-197301fbcab0

packages/engine/src/__tests__/persist-thinking-routing.test.ts

@@ -0,0 +1,57 @@
+import { describe, expect, it, vi, beforeEach } from "vitest";
+import { isEphemeralAgent, resolvePersistAgentThinkingLog, type GlobalSettings } from "@fusion/core";
+import { AgentLogger } from "../agent-logger.js";
+
+vi.mock("../agent-logger.js", () => ({
+  AgentLogger: vi.fn(),
+}));
+
+function createLoggerForAgent(agent: { metadata?: Record<string, unknown> }, settings: Partial<GlobalSettings>) {
+  const ephemeral = isEphemeralAgent(agent);
+  return new AgentLogger({
+    persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral }),
+  });
+}
+
+describe("thinking persistence routing", () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+  });
+
+  const permanentAgent = { metadata: { type: "permanent" } };
+  const ephemeralAgent = { metadata: { agentKind: "task-worker" } };
+
+  it.each([
+    {
+      name: "both off",
+      settings: { persistAgentThinkingLogPermanent: false, persistAgentThinkingLogEphemeral: false },
+      expectedPermanent: false,
+      expectedEphemeral: false,
+    },
+    {
+      name: "permanent only",
+      settings: { persistAgentThinkingLogPermanent: true, persistAgentThinkingLogEphemeral: false },
+      expectedPermanent: true,
+      expectedEphemeral: false,
+    },
+    {
+      name: "ephemeral only",
+      settings: { persistAgentThinkingLogPermanent: false, persistAgentThinkingLogEphemeral: true },
+      expectedPermanent: false,
+      expectedEphemeral: true,
+    },
+    {
+      name: "legacy fallback",
+      settings: { persistAgentThinkingLog: true },
+      expectedPermanent: true,
+      expectedEphemeral: true,
+    },
+  ])("routes %s", ({ settings, expectedPermanent, expectedEphemeral }) => {
+    createLoggerForAgent(permanentAgent, settings);
+    createLoggerForAgent(ephemeralAgent, settings);
+
+    const calls = vi.mocked(AgentLogger).mock.calls;
+    expect(calls[0]?.[0]).toMatchObject({ persistAgentThinkingLog: expectedPermanent });
+    expect(calls[1]?.[0]).toMatchObject({ persistAgentThinkingLog: expectedEphemeral });
+  });
+});

packages/engine/src/agent-heartbeat.ts

@@ -18,7 +18,7 @@
  */
 
 import type { AgentStore, AgentHeartbeatRun, HeartbeatInvocationSource, AgentHeartbeatConfig, AgentBudgetStatus, Message, MessageStore, TaskStore, TaskDetail, AgentRole, Agent, InboxTask, RunMutationContext, Settings, AgentConfigRevision, ReflectionStore, ChatStore, ChatRoom, ChatRoomMessage } from "@fusion/core";
-import { ApprovalRequestStore, buildExecutionMemoryInstructions, isEphemeralAgent, hasAgentIdentity, resolveEffectiveAgentPermissionPolicy, canAgentTakeImplementationTask, canAgentTakeImplementationTaskForExplicitRouting } from "@fusion/core";
+import { ApprovalRequestStore, buildExecutionMemoryInstructions, isEphemeralAgent, hasAgentIdentity, resolveEffectiveAgentPermissionPolicy, canAgentTakeImplementationTask, canAgentTakeImplementationTaskForExplicitRouting, resolvePersistAgentThinkingLog } from "@fusion/core";
 import type { ToolDefinition } from "@mariozechner/pi-coding-agent";
 import { Type, type Static } from "@mariozechner/pi-ai";
 import { createHash } from "node:crypto";
@@ -2029,7 +2029,7 @@ export class HeartbeatMonitor {
             appendLog: (entry) => this.store.appendRunLog(agentId, run.id, entry),
             agent: agent.role as AgentRole,
             persistAgentToolOutput: memorySettings?.persistAgentToolOutput,
-            persistAgentThinkingLog: memorySettings?.persistAgentThinkingLog,
+            persistAgentThinkingLog: resolvePersistAgentThinkingLog(memorySettings, { ephemeral: isAgentEphemeral }),
           });
         } else if (taskId) {
           agentLogger = new AgentLogger({
@@ -2038,7 +2038,7 @@ export class HeartbeatMonitor {
             agent: agent.role as AgentRole,
             appendLog: (entry) => this.store.appendRunLog(agentId, run.id, entry),
             persistAgentToolOutput: memorySettings?.persistAgentToolOutput,
-            persistAgentThinkingLog: memorySettings?.persistAgentThinkingLog,
+            persistAgentThinkingLog: resolvePersistAgentThinkingLog(memorySettings, { ephemeral: isAgentEphemeral }),
           });
         }
 

packages/engine/src/executor.ts

@@ -12,6 +12,7 @@ import {
   getTaskMergeBlocker,
   isEphemeralAgent,
   resolveAgentPrompt,
+  resolvePersistAgentThinkingLog,
   resolveEffectiveAgentPermissionPolicy,
   resolveProjectDefaultModel,
   type RunCommandResult,
@@ -3160,7 +3161,8 @@ export class TaskExecutor {
         taskId: task.id,
         agent: "executor",
         persistAgentToolOutput: settings.persistAgentToolOutput,
-        persistAgentThinkingLog: settings.persistAgentThinkingLog,
+        // Executor sessions are task-scoped ephemeral workers.
+        persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
         onAgentText: (taskId, delta) => {
           lastAssistantText += delta;
           stuckDetector?.recordActivity(taskId);
@@ -5290,7 +5292,8 @@ ${feedback}
         taskId: task.id,
         agent: "executor",
         persistAgentToolOutput: settings.persistAgentToolOutput,
-        persistAgentThinkingLog: settings.persistAgentThinkingLog,
+        // Executor sessions are task-scoped ephemeral workers.
+        persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
         onAgentText: this.options.onAgentText,
         onAgentTool: this.options.onAgentTool,
       });
@@ -6100,7 +6103,8 @@ and show an appropriate message to the user.\`
       taskId: task.id,
       agent: "reviewer",
       persistAgentToolOutput: settings.persistAgentToolOutput,
-      persistAgentThinkingLog: settings.persistAgentThinkingLog,
+      // Review-in-executor sessions are task-scoped ephemeral workers.
+      persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
       onAgentText: (taskId, delta) => {
         this.options.onAgentText?.(taskId, delta);
       },

packages/engine/src/merger.ts

@@ -39,6 +39,7 @@ import {
   resolveTaskMergeTarget,
   resolveTitleSummarizerSettingsModel,
   resolveAgentPrompt,
+  resolvePersistAgentThinkingLog,
   summarizeCommitBody,
   summarizeCommitSubject,
   summarizeMergeCommit,
@@ -1006,7 +1007,8 @@ async function attemptInMergeVerificationFix(
       taskId,
       agent: "merger",
       persistAgentToolOutput: settings.persistAgentToolOutput,
-      persistAgentThinkingLog: settings.persistAgentThinkingLog,
+      // Merger agents are task-scoped ephemeral workers.
+    persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
       onAgentText: options.onAgentText,
       onAgentTool: options.onAgentTool,
     });
@@ -2116,7 +2118,8 @@ async function runAiAgentForAutostashConflict(params: {
     taskId,
     agent: "merger",
     persistAgentToolOutput: settings.persistAgentToolOutput,
-    persistAgentThinkingLog: settings.persistAgentThinkingLog,
+    // Merger agents are task-scoped ephemeral workers.
+    persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
     onAgentText: options.onAgentText
       ? (_id: string, delta: string) => options.onAgentText!(delta)
       : undefined,
@@ -2486,7 +2489,8 @@ async function runAiAgentForAutostashHardFail(params: {
     taskId,
     agent: "merger",
     persistAgentToolOutput: settings.persistAgentToolOutput,
-    persistAgentThinkingLog: settings.persistAgentThinkingLog,
+    // Merger agents are task-scoped ephemeral workers.
+    persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
     onAgentText: options.onAgentText
       ? (_id: string, delta: string) => options.onAgentText!(delta)
       : undefined,
@@ -4931,7 +4935,8 @@ You are assisting with a paused \`git pull --rebase\`.
     taskId,
     agent: "merger",
     persistAgentToolOutput: settings.persistAgentToolOutput,
-    persistAgentThinkingLog: settings.persistAgentThinkingLog,
+    // Merger agents are task-scoped ephemeral workers.
+    persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
     onAgentText: options?.onAgentText
       ? (_id, delta) => options.onAgentText?.(delta)
       : undefined,
@@ -7878,7 +7883,8 @@ async function runAiAgentForCommit(params: AiAgentParams): Promise<{ success: bo
     taskId,
     agent: "merger",
     persistAgentToolOutput: settings.persistAgentToolOutput,
-    persistAgentThinkingLog: settings.persistAgentThinkingLog,
+    // Merger agents are task-scoped ephemeral workers.
+    persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
     onAgentText: options.onAgentText
       ? (_id, delta) => options.onAgentText!(delta)
       : undefined,
@@ -8492,7 +8498,8 @@ If issues are found that need attention, describe them clearly and include concr
     taskId,
     agent: "merger",
     persistAgentToolOutput: settings.persistAgentToolOutput,
-    persistAgentThinkingLog: settings.persistAgentThinkingLog,
+    // Merger agents are task-scoped ephemeral workers.
+    persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
   });
 
   try {

packages/engine/src/reviewer.ts

@@ -9,7 +9,7 @@
  */
 
 import type { TaskStore, TaskComment, AgentPromptsConfig, Settings } from "@fusion/core";
-import { buildReviewerMemoryInstructions, resolveAgentPrompt } from "@fusion/core";
+import { buildReviewerMemoryInstructions, resolveAgentPrompt, resolvePersistAgentThinkingLog } from "@fusion/core";
 import { describeModel, promptWithFallback } from "./pi.js";
 import { isContextLimitError } from "./context-limit-detector.js";
 import { createResolvedAgentSession, extractRuntimeHint } from "./agent-session-helpers.js";
@@ -350,7 +350,8 @@ export async function reviewStep(
           ? (_id, delta) => options.onText!(delta)
           : undefined,
         persistAgentToolOutput: liveSettings?.persistAgentToolOutput,
-        persistAgentThinkingLog: liveSettings?.persistAgentThinkingLog,
+        // Reviewer sessions are task-scoped ephemeral workers.
+        persistAgentThinkingLog: resolvePersistAgentThinkingLog(liveSettings, { ephemeral: true }),
       })
     : null;
 

packages/engine/src/step-session-executor.ts

@@ -18,6 +18,7 @@ import { existsSync } from "node:fs";
 import { join } from "node:path";
 import type { AgentSession } from "@mariozechner/pi-coding-agent";
 import type { AgentStore, MessageStore, PermanentAgentGatingContext, TaskDetail, Settings, TaskStore } from "@fusion/core";
+import { resolvePersistAgentThinkingLog } from "@fusion/core";
 
 import {
   createResolvedAgentSession,
@@ -890,7 +891,8 @@ export class StepSessionExecutor {
           taskId: taskDetail.id,
           agent: "executor",
           persistAgentToolOutput: settings.persistAgentToolOutput,
-          persistAgentThinkingLog: settings.persistAgentThinkingLog,
+          // Step-session workers are task-scoped ephemeral agents.
+          persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
         });
         let session: AgentSession | null = null;
 

packages/engine/src/triage.ts

@@ -9,6 +9,7 @@ import type {
 import {
   buildTriageMemoryInstructions,
   resolveAgentPrompt,
+  resolvePersistAgentThinkingLog,
   sortTasksByPriorityThenAgeAndId,
 } from "@fusion/core";
 import type { ImageContent } from "@mariozechner/pi-ai";
@@ -928,7 +929,8 @@ export class TriageProcessor {
           taskId: task.id,
           agent: "triage",
           persistAgentToolOutput: settings.persistAgentToolOutput,
-          persistAgentThinkingLog: settings.persistAgentThinkingLog,
+          // Triage runs in a task-scoped ephemeral worker session.
+          persistAgentThinkingLog: resolvePersistAgentThinkingLog(settings, { ephemeral: true }),
           onAgentText: (id, delta) => {
             stuckDetector?.recordActivity(task.id);
             this.options.onAgentText?.(id, delta);