From f04fae4c6a37aefbc205e0040e1aebb6fd53bf2f Mon Sep 17 00:00:00 2001
From: Peter Steinberger <steipete@gmail.com>
Date: Fri, 8 May 2026 13:32:17 +0100
Subject: [PATCH] refactor: stop creating jsonl compaction successors

---
 .../compaction-successor-transcript.test.ts   | 19 ++++++++++
 .../compaction-successor-transcript.ts        | 37 ++++++++-----------
 2 files changed, 35 insertions(+), 21 deletions(-)

diff --git a/src/agents/pi-embedded-runner/compaction-successor-transcript.test.ts b/src/agents/pi-embedded-runner/compaction-successor-transcript.test.ts
index 0429bac9a4c..935700bb024 100644
--- a/src/agents/pi-embedded-runner/compaction-successor-transcript.test.ts
+++ b/src/agents/pi-embedded-runner/compaction-successor-transcript.test.ts
@@ -281,6 +281,25 @@ describe("rotateTranscriptAfterCompaction", () => {
     expect(result.reason).toBe("no compaction entry");
   });
 
+  it("does not create legacy jsonl successor files for unmigrated transcripts", async () => {
+    const dir = await createTmpDir();
+    const { manager } = createCompactedSession(dir);
+
+    const result = await rotateTranscriptAfterCompaction({
+      sessionManager: manager,
+      sessionFile: path.join(dir, "legacy-session.jsonl"),
+      now: () => new Date("2026-04-27T12:15:00.000Z"),
+    });
+
+    expect(result).toMatchObject({
+      rotated: false,
+      reason: "transcript not in SQLite",
+    });
+    await expect(
+      fs.stat(path.join(dir, "2026-04-27T12-15-00-000Z_legacy-session.jsonl")),
+    ).rejects.toMatchObject({ code: "ENOENT" });
+  });
+
   it("uses a refreshed manager after manual boundary hardening", async () => {
     const dir = await createTmpDir();
     const manager = SessionManager.create(dir);
diff --git a/src/agents/pi-embedded-runner/compaction-successor-transcript.ts b/src/agents/pi-embedded-runner/compaction-successor-transcript.ts
index 93eb3c66939..326298b0624 100644
--- a/src/agents/pi-embedded-runner/compaction-successor-transcript.ts
+++ b/src/agents/pi-embedded-runner/compaction-successor-transcript.ts
@@ -1,5 +1,4 @@
 import { randomUUID } from "node:crypto";
-import path from "node:path";
 import {
   createSqliteSessionTranscriptLocator,
   isSqliteSessionTranscriptLocator,
@@ -52,6 +51,9 @@ export async function rotateTranscriptAfterCompaction(params: {
   if (!sessionFile) {
     return { rotated: false, reason: "missing session file" };
   }
+  if (!isSqliteSessionTranscriptLocator(sessionFile)) {
+    return { rotated: false, reason: "transcript not in SQLite" };
+  }
 
   const branch = params.sessionManager.getBranch();
   const latestCompactionIndex = findLatestCompactionIndex(branch);
@@ -62,10 +64,14 @@ export async function rotateTranscriptAfterCompaction(params: {
   const compaction = branch[latestCompactionIndex] as CompactionEntry;
   const timestamp = (params.now?.() ?? new Date()).toISOString();
   const sessionId = randomUUID();
+  const sourceScope = resolveSourceTranscriptScope({
+    agentId: params.agentId,
+    transcriptPath: sessionFile,
+  });
   const successorTranscriptPath = resolveSuccessorTranscriptPath({
     transcriptPath: sessionFile,
     sessionId,
-    timestamp,
+    agentId: sourceScope.agentId,
   });
   const successorEntries = buildSuccessorEntries({
     allEntries: params.sessionManager.getEntries(),
@@ -83,10 +89,6 @@ export async function rotateTranscriptAfterCompaction(params: {
     cwd: params.sessionManager.getCwd(),
     parentSession: sessionFile,
   });
-  const sourceScope = resolveSourceTranscriptScope({
-    agentId: params.agentId,
-    transcriptPath: sessionFile,
-  });
   replaceSqliteSessionTranscriptEvents({
     agentId: sourceScope.agentId,
     sessionId,
@@ -360,20 +362,13 @@ function buildSuccessorHeader(params: {
 function resolveSuccessorTranscriptPath(params: {
   transcriptPath: string;
   sessionId: string;
-  timestamp: string;
+  agentId: string;
 }): string {
-  if (isSqliteSessionTranscriptLocator(params.transcriptPath)) {
-    const existing = resolveSqliteSessionTranscriptScopeForPath({
-      transcriptPath: params.transcriptPath,
-    });
-    return createSqliteSessionTranscriptLocator({
-      agentId: existing?.agentId,
-      sessionId: params.sessionId,
-    });
-  }
-  const fileTimestamp = params.timestamp.replace(/[:.]/g, "-");
-  return path.join(
-    path.dirname(params.transcriptPath),
-    `${fileTimestamp}_${params.sessionId}.jsonl`,
-  );
+  const existing = resolveSqliteSessionTranscriptScopeForPath({
+    transcriptPath: params.transcriptPath,
+  });
+  return createSqliteSessionTranscriptLocator({
+    agentId: params.agentId || existing?.agentId || DEFAULT_AGENT_ID,
+    sessionId: params.sessionId,
+  });
 }