diff --git a/src/hooks/todo-continuation-enforcer.test.ts b/src/hooks/todo-continuation-enforcer.test.ts
index d7c19577b..0675ca437 100644
--- a/src/hooks/todo-continuation-enforcer.test.ts
+++ b/src/hooks/todo-continuation-enforcer.test.ts
@@ -873,4 +873,193 @@ describe("todo-continuation-enforcer", () => {
     expect(promptCalls.length).toBe(1)
     expect(promptCalls[0].model).toEqual({ providerID: "openai", modelID: "gpt-5.2" })
   })
+
+  // ============================================================
+  // COMPACTION AGENT FILTERING TESTS
+  // These tests verify that compaction agent messages are filtered
+  // when resolving agent info, preventing infinite continuation loops
+  // ============================================================
+
+  test("should skip compaction agent messages when resolving agent info", async () => {
+    // #given - session where last message is from compaction agent but previous was Sisyphus
+    const sessionID = "main-compaction-filter"
+    setMainSession(sessionID)
+
+    const mockMessagesWithCompaction = [
+      { info: { id: "msg-1", role: "user", agent: "Sisyphus", model: { providerID: "anthropic", modelID: "claude-sonnet-4-5" } } },
+      { info: { id: "msg-2", role: "assistant", agent: "Sisyphus", modelID: "claude-sonnet-4-5", providerID: "anthropic" } },
+      { info: { id: "msg-3", role: "assistant", agent: "compaction", modelID: "claude-sonnet-4-5", providerID: "anthropic" } },
+    ]
+
+    const mockInput = {
+      client: {
+        session: {
+          todo: async () => ({
+            data: [{ id: "1", content: "Task 1", status: "pending", priority: "high" }],
+          }),
+          messages: async () => ({ data: mockMessagesWithCompaction }),
+          prompt: async (opts: any) => {
+            promptCalls.push({
+              sessionID: opts.path.id,
+              agent: opts.body.agent,
+              model: opts.body.model,
+              text: opts.body.parts[0].text,
+            })
+            return {}
+          },
+        },
+        tui: { showToast: async () => ({}) },
+      },
+      directory: "/tmp/test",
+    } as any
+
+    const hook = createTodoContinuationEnforcer(mockInput, {
+      backgroundManager: createMockBackgroundManager(false),
+    })
+
+    // #when - session goes idle
+    await hook.handler({ event: { type: "session.idle", properties: { sessionID } } })
+    await new Promise(r => setTimeout(r, 2500))
+
+    // #then - continuation uses Sisyphus (skipped compaction agent)
+    expect(promptCalls.length).toBe(1)
+    expect(promptCalls[0].agent).toBe("Sisyphus")
+  })
+
+  test("should skip injection when only compaction agent messages exist", async () => {
+    // #given - session with only compaction agent (post-compaction, no prior agent info)
+    const sessionID = "main-only-compaction"
+    setMainSession(sessionID)
+
+    const mockMessagesOnlyCompaction = [
+      { info: { id: "msg-1", role: "assistant", agent: "compaction" } },
+    ]
+
+    const mockInput = {
+      client: {
+        session: {
+          todo: async () => ({
+            data: [{ id: "1", content: "Task 1", status: "pending", priority: "high" }],
+          }),
+          messages: async () => ({ data: mockMessagesOnlyCompaction }),
+          prompt: async (opts: any) => {
+            promptCalls.push({
+              sessionID: opts.path.id,
+              agent: opts.body.agent,
+              model: opts.body.model,
+              text: opts.body.parts[0].text,
+            })
+            return {}
+          },
+        },
+        tui: { showToast: async () => ({}) },
+      },
+      directory: "/tmp/test",
+    } as any
+
+    const hook = createTodoContinuationEnforcer(mockInput, {})
+
+    // #when - session goes idle
+    await hook.handler({
+      event: { type: "session.idle", properties: { sessionID } },
+    })
+
+    await new Promise(r => setTimeout(r, 3000))
+
+    // #then - no continuation (compaction is in default skipAgents)
+    expect(promptCalls).toHaveLength(0)
+  })
+
+  test("should skip injection when prometheus agent is after compaction", async () => {
+    // #given - prometheus session that was compacted
+    const sessionID = "main-prometheus-compacted"
+    setMainSession(sessionID)
+
+    const mockMessagesPrometheusCompacted = [
+      { info: { id: "msg-1", role: "user", agent: "prometheus" } },
+      { info: { id: "msg-2", role: "assistant", agent: "prometheus" } },
+      { info: { id: "msg-3", role: "assistant", agent: "compaction" } },
+    ]
+
+    const mockInput = {
+      client: {
+        session: {
+          todo: async () => ({
+            data: [{ id: "1", content: "Task 1", status: "pending", priority: "high" }],
+          }),
+          messages: async () => ({ data: mockMessagesPrometheusCompacted }),
+          prompt: async (opts: any) => {
+            promptCalls.push({
+              sessionID: opts.path.id,
+              agent: opts.body.agent,
+              model: opts.body.model,
+              text: opts.body.parts[0].text,
+            })
+            return {}
+          },
+        },
+        tui: { showToast: async () => ({}) },
+      },
+      directory: "/tmp/test",
+    } as any
+
+    const hook = createTodoContinuationEnforcer(mockInput, {})
+
+    // #when - session goes idle
+    await hook.handler({
+      event: { type: "session.idle", properties: { sessionID } },
+    })
+
+    await new Promise(r => setTimeout(r, 3000))
+
+    // #then - no continuation (prometheus found after filtering compaction, prometheus is in skipAgents)
+    expect(promptCalls).toHaveLength(0)
+  })
+
+  test("should inject when agent info is undefined but skipAgents is empty", async () => {
+    // #given - session with no agent info but skipAgents is empty
+    const sessionID = "main-no-agent-no-skip"
+    setMainSession(sessionID)
+
+    const mockMessagesNoAgent = [
+      { info: { id: "msg-1", role: "user" } },
+      { info: { id: "msg-2", role: "assistant" } },
+    ]
+
+    const mockInput = {
+      client: {
+        session: {
+          todo: async () => ({
+            data: [{ id: "1", content: "Task 1", status: "pending", priority: "high" }],
+          }),
+          messages: async () => ({ data: mockMessagesNoAgent }),
+          prompt: async (opts: any) => {
+            promptCalls.push({
+              sessionID: opts.path.id,
+              agent: opts.body.agent,
+              model: opts.body.model,
+              text: opts.body.parts[0].text,
+            })
+            return {}
+          },
+        },
+        tui: { showToast: async () => ({}) },
+      },
+      directory: "/tmp/test",
+    } as any
+
+    const hook = createTodoContinuationEnforcer(mockInput, {
+      skipAgents: [],
+    })
+
+    // #when - session goes idle
+    await hook.handler({
+      event: { type: "session.idle", properties: { sessionID } },
+    })
+
+    await new Promise(r => setTimeout(r, 3000))
+
+    // #then - continuation injected (no agents to skip)
+    expect(promptCalls.length).toBe(1)
+  })
 })
diff --git a/src/hooks/todo-continuation-enforcer.ts b/src/hooks/todo-continuation-enforcer.ts
index 41e8b2c54..a4e65ea6e 100644
--- a/src/hooks/todo-continuation-enforcer.ts
+++ b/src/hooks/todo-continuation-enforcer.ts
@@ -13,7 +13,7 @@ import { createSystemDirective, SystemDirectiveTypes } from "../shared/system-di
 
 const HOOK_NAME = "todo-continuation-enforcer"
 
-const DEFAULT_SKIP_AGENTS = ["prometheus"]
+const DEFAULT_SKIP_AGENTS = ["prometheus", "compaction"]
 
 export interface TodoContinuationEnforcerOptions {
   backgroundManager?: BackgroundManager
@@ -373,6 +373,7 @@ export function createTodoContinuationEnforcer(
       }
 
       let resolvedInfo: ResolvedMessageInfo | undefined
+      let hasCompactionMessage = false
       try {
         const messagesResp = await ctx.client.session.messages({
           path: { id: sessionID },
@@ -388,6 +389,10 @@ export function createTodoContinuationEnforcer(
         }>
         for (let i = messages.length - 1; i >= 0; i--) {
           const info = messages[i].info
+          if (info?.agent === "compaction") {
+            hasCompactionMessage = true
+            continue
+          }
           if (info?.agent || info?.model || (info?.modelID && info?.providerID)) {
             resolvedInfo = {
               agent: info.agent,
@@ -401,11 +406,15 @@ export function createTodoContinuationEnforcer(
         log(`[${HOOK_NAME}] Failed to fetch messages for agent check`, { sessionID, error: String(err) })
       }
 
-      log(`[${HOOK_NAME}] Agent check`, { sessionID, agentName: resolvedInfo?.agent, skipAgents })
+      log(`[${HOOK_NAME}] Agent check`, { sessionID, agentName: resolvedInfo?.agent, skipAgents, hasCompactionMessage })
       if (resolvedInfo?.agent && skipAgents.includes(resolvedInfo.agent)) {
         log(`[${HOOK_NAME}] Skipped: agent in skipAgents list`, { sessionID, agent: resolvedInfo.agent })
         return
       }
+      if (hasCompactionMessage && !resolvedInfo?.agent) {
+        log(`[${HOOK_NAME}] Skipped: compaction occurred but no agent info resolved`, { sessionID })
+        return
+      }
 
       startCountdown(sessionID, incompleteCount, todos.length, resolvedInfo)
       return