From 75969ed5c499a1a45d9cfcbaaf999567fc4d9c2e Mon Sep 17 00:00:00 2001
From: Marc Gratch <me@marcgratch.com>
Date: Mon, 23 Feb 2026 11:43:52 -0600
Subject: [PATCH] fix(plugins): pass session context to before_compaction hook
 in subscribe handler

The handleAutoCompactionStart handler was calling runBeforeCompaction with
only messageCount and an empty hook context. Plugins receiving this hook
could not identify the session or snapshot the transcript during
auto-compaction.

The other call site in compact.ts already passes the full payload
(messages, sessionFile, sessionKey). This aligns the subscribe handler
to do the same using ctx.params.session and ctx.params.sessionKey.

(cherry picked from commit 318a19d1a1a428ff1be2e03f51777c3829c6e322)
---
 .../pi-embedded-subscribe.handlers.compaction.ts |  6 +++++-
 src/plugins/wired-hooks-compaction.test.ts       | 16 +++++++++++++---
 2 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/src/agents/pi-embedded-subscribe.handlers.compaction.ts b/src/agents/pi-embedded-subscribe.handlers.compaction.ts
index a9dda4110e0..a8072bf2e1a 100644
--- a/src/agents/pi-embedded-subscribe.handlers.compaction.ts
+++ b/src/agents/pi-embedded-subscribe.handlers.compaction.ts
@@ -24,8 +24,12 @@ export function handleAutoCompactionStart(ctx: EmbeddedPiSubscribeContext) {
       .runBeforeCompaction(
         {
           messageCount: ctx.params.session.messages?.length ?? 0,
+          messages: ctx.params.session.messages,
+          sessionFile: ctx.params.session.sessionFile,
+        },
+        {
+          sessionKey: ctx.params.sessionKey,
         },
-        {},
       )
       .catch((err) => {
         ctx.log.warn(`before_compaction hook failed: ${String(err)}`);
diff --git a/src/plugins/wired-hooks-compaction.test.ts b/src/plugins/wired-hooks-compaction.test.ts
index 2292d95b760..05e63a2b2f9 100644
--- a/src/plugins/wired-hooks-compaction.test.ts
+++ b/src/plugins/wired-hooks-compaction.test.ts
@@ -41,7 +41,11 @@ describe("compaction hook wiring", () => {
     hookMocks.runner.hasHooks.mockReturnValue(true);
 
     const ctx = {
-      params: { runId: "r1", session: { messages: [1, 2, 3] } },
+      params: {
+        runId: "r1",
+        sessionKey: "agent:main:web-abc123",
+        session: { messages: [1, 2, 3], sessionFile: "/tmp/test.jsonl" },
+      },
       state: { compactionInFlight: false },
       log: { debug: vi.fn(), warn: vi.fn() },
       incrementCompactionCount: vi.fn(),
@@ -53,10 +57,16 @@ describe("compaction hook wiring", () => {
     expect(hookMocks.runner.runBeforeCompaction).toHaveBeenCalledTimes(1);
 
     const beforeCalls = hookMocks.runner.runBeforeCompaction.mock.calls as unknown as Array<
-      [unknown]
+      [unknown, unknown]
     >;
-    const event = beforeCalls[0]?.[0] as { messageCount?: number } | undefined;
+    const event = beforeCalls[0]?.[0] as
+      | { messageCount?: number; messages?: unknown[]; sessionFile?: string }
+      | undefined;
     expect(event?.messageCount).toBe(3);
+    expect(event?.messages).toEqual([1, 2, 3]);
+    expect(event?.sessionFile).toBe("/tmp/test.jsonl");
+    const hookCtx = beforeCalls[0]?.[1] as { sessionKey?: string } | undefined;
+    expect(hookCtx?.sessionKey).toBe("agent:main:web-abc123");
   });
 
   it("calls runAfterCompaction when willRetry is false", () => {