fix(sessions): preserve recovered corrupt transcripts

steipete · steipete · commit 30307017a866 · 2026-06-02T11:40:04.000+01:00
diff --git a/src/agents/embedded-agent-runner/session-manager-init.test.ts b/src/agents/embedded-agent-runner/session-manager-init.test.ts
@@ -2,6 +2,7 @@ import fs from "node:fs/promises";
 import os from "node:os";
 import path from "node:path";
 import { afterEach, describe, expect, it } from "vitest";
+import { SessionManager } from "../sessions/session-manager.js";
 import { prepareSessionManagerForRun } from "./session-manager-init.js";
 
 const tempPaths: string[] = [];
@@ -205,4 +206,60 @@ describe("prepareSessionManagerForRun", () => {
     ]);
     expect(sessionManager.flushed).toBe(true);
   });
+
+  it("keeps recovered user-only transcripts through open and run preparation", async () => {
+    const sessionFile = await makeTempFile();
+    const userEntry = {
+      type: "message",
+      id: "user-1",
+      parentId: null,
+      timestamp: "2026-05-27T00:00:01.000Z",
+      message: { role: "user", content: "persisted prompt" },
+    };
+    await fs.writeFile(
+      sessionFile,
+      ['{"type":"session","id":"broken"', JSON.stringify(userEntry)].join("\n") + "\n",
+      "utf-8",
+    );
+
+    const sessionManager = SessionManager.open(sessionFile, path.dirname(sessionFile), "/old/cwd");
+
+    await prepareSessionManagerForRun({
+      sessionManager,
+      sessionFile,
+      hadSessionFile: true,
+      sessionId: "new-session",
+      cwd: "/tmp/task-repo",
+    });
+    sessionManager.appendMessage({
+      role: "assistant",
+      content: [{ type: "text", text: "response" }],
+      api: "messages",
+      provider: "anthropic",
+      model: "sonnet-4.6",
+      usage: {
+        input: 0,
+        output: 0,
+        cacheRead: 0,
+        cacheWrite: 0,
+        totalTokens: 0,
+        cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+      },
+      stopReason: "stop",
+      timestamp: Date.now(),
+    });
+
+    const entries = (await fs.readFile(sessionFile, "utf-8"))
+      .trim()
+      .split("\n")
+      .map(
+        (line) => JSON.parse(line) as { type: string; id?: string; message?: { role?: string } },
+      );
+    expect(entries.map((entry) => entry.type)).toEqual(["session", "message", "message"]);
+    expect(entries[0]).toEqual(
+      expect.objectContaining({ type: "session", id: "new-session", cwd: "/tmp/task-repo" }),
+    );
+    expect(entries[1]).toEqual(userEntry);
+    expect(entries[2]?.message?.role).toBe("assistant");
+  });
 });
diff --git a/src/agents/embedded-agent-runner/session-manager-init.ts b/src/agents/embedded-agent-runner/session-manager-init.ts
@@ -53,6 +53,7 @@ export async function prepareSessionManagerForRun(params: {
     byId?: Map<string, unknown>;
     labelsById?: Map<string, unknown>;
     leafId?: string | null;
+    wasRecoveredFromCorruptHeader?: () => boolean;
   };
 
   const header = sm.fileEntries.find((e): e is SessionHeaderEntry => e.type === "session");
@@ -69,6 +70,18 @@ export async function prepareSessionManagerForRun(params: {
   }
 
   if (params.hadSessionFile && header && !hasAssistant) {
+    if (sm.wasRecoveredFromCorruptHeader?.()) {
+      header.id = params.sessionId;
+      header.cwd = params.cwd;
+      sm.sessionId = params.sessionId;
+      sm.cwd = params.cwd;
+      await writeJsonlLines(params.sessionFile, sm.fileEntries.map(serializeJsonlLine), {
+        mode: 0o600,
+      });
+      sm.flushed = true;
+      return;
+    }
+
     // Reset file so the first assistant flush includes header+user+assistant in order.
     await assertExistingHeaderIsReadable(params.sessionFile);
     await fs.writeFile(params.sessionFile, "", "utf-8");
diff --git a/src/agents/sessions/session-manager.test.ts b/src/agents/sessions/session-manager.test.ts
@@ -78,8 +78,24 @@ describe("SessionManager.open", () => {
     await fs.writeFile(sessionFile, '{"type":"session","version":3,"id":"sess', "utf8");
 
     const sessionManager = SessionManager.open(sessionFile, dir, "/tmp/task-repo");
-    sessionManager.appendMessage({ role: "user", content: "hello" });
-    sessionManager.appendMessage({ role: "assistant", content: "hi" });
+    sessionManager.appendMessage({ role: "user", content: "hello", timestamp: Date.now() });
+    sessionManager.appendMessage({
+      role: "assistant",
+      content: [{ type: "text", text: "hi" }],
+      api: "messages",
+      provider: "anthropic",
+      model: "sonnet-4.6",
+      usage: {
+        input: 0,
+        output: 0,
+        cacheRead: 0,
+        cacheWrite: 0,
+        totalTokens: 0,
+        cost: { input: 0, output: 0, cacheRead: 0, cacheWrite: 0, total: 0 },
+      },
+      stopReason: "stop",
+      timestamp: Date.now(),
+    });
 
     const entries = (await fs.readFile(sessionFile, "utf8"))
       .trim()
diff --git a/src/agents/sessions/session-manager.ts b/src/agents/sessions/session-manager.ts
@@ -14,7 +14,6 @@ import {
 import { readdir, readFile, stat } from "node:fs/promises";
 import { join, resolve } from "node:path";
 import {
-  appendJsonlEntriesSync,
   appendJsonlEntrySync,
   writeJsonlEntriesSync,
 } from "../../config/sessions/transcript-jsonl.js";
@@ -742,6 +741,7 @@ export class SessionManager {
   private labelsById: Map<string, string> = new Map();
   private labelTimestampsById: Map<string, string> = new Map();
   private leafId: string | null = null;
+  private recoveredCorruptHeader = false;
 
   private constructor(
     cwd: string,
@@ -766,6 +766,7 @@ export class SessionManager {
   /** Switch to a different session file (used for resume and branching) */
   setSessionFile(sessionFile: string): void {
     this.sessionFile = resolve(sessionFile);
+    this.recoveredCorruptHeader = false;
     if (existsSync(this.sessionFile)) {
       this.fileEntries = loadEntriesFromFile(this.sessionFile);
 
@@ -778,15 +779,9 @@ export class SessionManager {
           const header = this.fileEntries.find((e) => e.type === "session");
           this.sessionId = header?.id ?? createSessionId();
           this.buildIndex();
-          const hasAssistant = this.fileEntries.some(
-            (e) => e.type === "message" && e.message.role === "assistant",
-          );
-          if (hasAssistant) {
-            this.rewriteFile();
-            this.flushed = true;
-          } else {
-            this.flushed = false;
-          }
+          this.rewriteFile();
+          this.recoveredCorruptHeader = true;
+          this.flushed = true;
           return;
         }
 
@@ -815,6 +810,7 @@ export class SessionManager {
   }
 
   newSession(options?: NewSessionOptions): string | undefined {
+    this.recoveredCorruptHeader = false;
     this.sessionId = options?.id ?? createSessionId();
     const timestamp = new Date().toISOString();
     const header: SessionHeader = {
@@ -884,6 +880,10 @@ export class SessionManager {
     return this.sessionId;
   }
 
+  wasRecoveredFromCorruptHeader(): boolean {
+    return this.recoveredCorruptHeader;
+  }
+
   getSessionFile(): string | undefined {
     return this.sessionFile;
   }
