From 4c22d6de769a810e5ac6b25c10b207cba4b37fce Mon Sep 17 00:00:00 2001
From: justsisyphus <sisyphus-dev-ai@users.noreply.github.com>
Date: Thu, 15 Jan 2026 14:30:48 +0900
Subject: [PATCH] fix(todo-continuation): preserve model when injecting
 continuation prompt

---
 src/hooks/todo-continuation-enforcer.test.ts | 22 ++++++++++++++++++++
 src/hooks/todo-continuation-enforcer.ts      | 10 ++++++---
 2 files changed, 29 insertions(+), 3 deletions(-)

diff --git a/src/hooks/todo-continuation-enforcer.test.ts b/src/hooks/todo-continuation-enforcer.test.ts
index e680cfd6..2f693b8c 100644
--- a/src/hooks/todo-continuation-enforcer.test.ts
+++ b/src/hooks/todo-continuation-enforcer.test.ts
@@ -807,4 +807,26 @@ describe("todo-continuation-enforcer", () => {
     // #then - no continuation (API fallback detected the abort)
     expect(promptCalls).toHaveLength(0)
   })
+
+  test("should pass model property in prompt call (undefined when no message context)", async () => {
+    // #given - session with incomplete todos, no prior message context available
+    const sessionID = "main-model-preserve"
+    setMainSession(sessionID)
+
+    const hook = createTodoContinuationEnforcer(createMockPluginInput(), {
+      backgroundManager: createMockBackgroundManager(false),
+    })
+
+    // #when - session goes idle and continuation is injected
+    await hook.handler({
+      event: { type: "session.idle", properties: { sessionID } },
+    })
+
+    await new Promise(r => setTimeout(r, 2500))
+
+    // #then - prompt call made, model is undefined when no context (expected behavior)
+    expect(promptCalls.length).toBe(1)
+    expect(promptCalls[0].text).toContain("TODO CONTINUATION")
+    expect("model" in promptCalls[0]).toBe(true)
+  })
 })
diff --git a/src/hooks/todo-continuation-enforcer.ts b/src/hooks/todo-continuation-enforcer.ts
index b551a7ca..0c4966ea 100644
--- a/src/hooks/todo-continuation-enforcer.ts
+++ b/src/hooks/todo-continuation-enforcer.ts
@@ -206,14 +206,18 @@ export function createTodoContinuationEnforcer(
 
     const prompt = `${CONTINUATION_PROMPT}\n\n[Status: ${todos.length - freshIncompleteCount}/${todos.length} completed, ${freshIncompleteCount} remaining]`
 
-    try {
-      log(`[${HOOK_NAME}] Injecting continuation`, { sessionID, agent: prevMessage?.agent, incompleteCount: freshIncompleteCount })
+    const model = prevMessage?.model?.providerID && prevMessage?.model?.modelID
+      ? { providerID: prevMessage.model.providerID, modelID: prevMessage.model.modelID }
+      : undefined
+
+    try {
+      log(`[${HOOK_NAME}] Injecting continuation`, { sessionID, agent: prevMessage?.agent, model, incompleteCount: freshIncompleteCount })
 
-      // Don't pass model - let OpenCode use session's existing lastModel
       await ctx.client.session.prompt({
         path: { id: sessionID },
         body: {
           agent: prevMessage?.agent,
+          ...(model !== undefined ? { model } : {}),
           parts: [{ type: "text", text: prompt }],
         },
         query: { directory: ctx.directory },