diff --git a/src/hooks/atlas/boulder-continuation-injector.test.ts b/src/hooks/atlas/boulder-continuation-injector.test.ts
index 5eb6e90c1..bb63d1c25 100644
--- a/src/hooks/atlas/boulder-continuation-injector.test.ts
+++ b/src/hooks/atlas/boulder-continuation-injector.test.ts
@@ -31,7 +31,7 @@ describe("injectBoulderContinuation", () => {
     } as unknown as PluginInput
 
     // when
-    await injectBoulderContinuation({
+    const result = await injectBoulderContinuation({
       ctx,
       sessionID: "ses_test_123",
       planName: "test-plan",
@@ -42,6 +42,7 @@ describe("injectBoulderContinuation", () => {
     })
 
     // then
+    expect(result).toBe("injected")
     expect(promptAsyncMock).toHaveBeenCalledTimes(1)
     expect(promptAsyncMock).toHaveBeenCalledWith(
       expect.objectContaining({
@@ -51,4 +52,73 @@ describe("injectBoulderContinuation", () => {
       }),
     )
   })
+
+  test("#given background tasks are running #when injector checks again #then it reports skipped background tasks without mutating failure count", async () => {
+    // given
+    registerAgentName("atlas")
+    const promptAsyncMock = mock(async (_request: unknown) => undefined)
+    const messagesMock = mock(async () => ({ data: [] }))
+    const sessionState = { promptFailureCount: 2, lastContinuationInjectedAt: 123 }
+
+    const ctx = {
+      directory: "/tmp",
+      client: {
+        session: {
+          messages: messagesMock,
+          promptAsync: promptAsyncMock,
+        },
+      },
+    } as unknown as PluginInput
+
+    // when
+    const result = await injectBoulderContinuation({
+      ctx,
+      sessionID: "ses_test_123",
+      planName: "test-plan",
+      remaining: 1,
+      total: 2,
+      agent: "atlas",
+      backgroundManager: {
+        getTasksByParentSession: () => [{ status: "running" }],
+      } as unknown as Parameters<typeof injectBoulderContinuation>[0]["backgroundManager"],
+      sessionState,
+    })
+
+    // then
+    expect(result).toBe("skipped_background_tasks")
+    expect(promptAsyncMock).not.toHaveBeenCalled()
+    expect(sessionState.promptFailureCount).toBe(2)
+    expect(sessionState.lastContinuationInjectedAt).toBe(123)
+  })
+
+  test("#given the continuation agent is unavailable #when injector runs #then it reports skipped agent unavailable without prompting", async () => {
+    // given
+    const promptAsyncMock = mock(async (_request: unknown) => undefined)
+    const messagesMock = mock(async () => ({ data: [] }))
+
+    const ctx = {
+      directory: "/tmp",
+      client: {
+        session: {
+          messages: messagesMock,
+          promptAsync: promptAsyncMock,
+        },
+      },
+    } as unknown as PluginInput
+
+    // when
+    const result = await injectBoulderContinuation({
+      ctx,
+      sessionID: "ses_test_123",
+      planName: "test-plan",
+      remaining: 1,
+      total: 2,
+      agent: "missing-agent",
+      sessionState: { promptFailureCount: 0 },
+    })
+
+    // then
+    expect(result).toBe("skipped_agent_unavailable")
+    expect(promptAsyncMock).not.toHaveBeenCalled()
+  })
 })
diff --git a/src/hooks/atlas/boulder-continuation-injector.ts b/src/hooks/atlas/boulder-continuation-injector.ts
index 7d64c6175..48a6f1edc 100644
--- a/src/hooks/atlas/boulder-continuation-injector.ts
+++ b/src/hooks/atlas/boulder-continuation-injector.ts
@@ -9,6 +9,8 @@ import { BOULDER_CONTINUATION_PROMPT } from "./system-reminder-templates"
 import { resolveRecentPromptContextForSession } from "./recent-model-resolver"
 import type { SessionState } from "./types"
 
+export type BoulderContinuationResult = "injected" | "skipped_background_tasks" | "skipped_agent_unavailable" | "failed"
+
 export async function injectBoulderContinuation(input: {
   ctx: PluginInput
   sessionID: string
@@ -21,7 +23,7 @@ export async function injectBoulderContinuation(input: {
   preferredTaskTitle?: string
   backgroundManager?: BackgroundManager
   sessionState: SessionState
-}): Promise<void> {
+}): Promise<BoulderContinuationResult> {
   const {
     ctx,
     sessionID,
@@ -42,7 +44,7 @@ export async function injectBoulderContinuation(input: {
 
   if (hasRunningBgTasks) {
     log(`[${HOOK_NAME}] Skipped injection: background tasks running`, { sessionID })
-    return
+    return "skipped_background_tasks"
   }
 
   const worktreeContext = worktreePath ? `\n\n[Worktree: ${worktreePath}]` : ""
@@ -61,7 +63,7 @@ export async function injectBoulderContinuation(input: {
 			sessionID,
 			agent: continuationAgent ?? agent ?? "unknown",
 		})
-		return
+		return "skipped_agent_unavailable"
 	}
 
 	try {
@@ -83,6 +85,7 @@ export async function injectBoulderContinuation(input: {
 
     sessionState.promptFailureCount = 0
     log(`[${HOOK_NAME}] Boulder continuation injected`, { sessionID })
+    return "injected"
   } catch (err) {
     sessionState.promptFailureCount += 1
     sessionState.lastFailureAt = Date.now()
@@ -91,5 +94,6 @@ export async function injectBoulderContinuation(input: {
       error: String(err),
       promptFailureCount: sessionState.promptFailureCount,
     })
+    return "failed"
   }
 }
diff --git a/src/hooks/atlas/idle-event.ts b/src/hooks/atlas/idle-event.ts
index 05734e4a3..c58ce0ff3 100644
--- a/src/hooks/atlas/idle-event.ts
+++ b/src/hooks/atlas/idle-event.ts
@@ -36,7 +36,17 @@ async function injectContinuation(input: {
   worktreePath?: string
 }): Promise<void> {
   const remaining = input.progress.total - input.progress.completed
-  input.sessionState.lastContinuationInjectedAt = Date.now()
+  if (input.sessionState.isInjectingContinuation) {
+    scheduleRetry({
+      ctx: input.ctx,
+      sessionID: input.sessionID,
+      sessionState: input.sessionState,
+      options: input.options,
+    })
+    return
+  }
+
+  input.sessionState.isInjectingContinuation = true
 
   try {
     const currentBoulder = readBoulderState(input.ctx.directory)
@@ -47,7 +57,7 @@ async function injectContinuation(input: {
       ? getTaskSessionState(input.ctx.directory, currentTask.key)
       : null
 
-    await injectBoulderContinuation({
+    const result = await injectBoulderContinuation({
       ctx: input.ctx,
       sessionID: input.sessionID,
       planName: input.planName,
@@ -60,9 +70,46 @@ async function injectContinuation(input: {
       backgroundManager: input.options?.backgroundManager,
       sessionState: input.sessionState,
     })
+
+    if (result === "injected") {
+      if (input.sessionState.pendingRetryTimer) {
+        clearTimeout(input.sessionState.pendingRetryTimer)
+        input.sessionState.pendingRetryTimer = undefined
+      }
+      input.sessionState.lastContinuationInjectedAt = Date.now()
+      return
+    }
+
+    if (result === "skipped_background_tasks") {
+      scheduleRetry({
+        ctx: input.ctx,
+        sessionID: input.sessionID,
+        sessionState: input.sessionState,
+        options: input.options,
+      })
+      return
+    }
+
+    if (result === "failed") {
+      scheduleRetry({
+        ctx: input.ctx,
+        sessionID: input.sessionID,
+        sessionState: input.sessionState,
+        options: input.options,
+      })
+    }
   } catch (error) {
     log(`[${HOOK_NAME}] Failed to inject boulder continuation`, { sessionID: input.sessionID, error })
     input.sessionState.promptFailureCount += 1
+    input.sessionState.lastFailureAt = Date.now()
+    scheduleRetry({
+      ctx: input.ctx,
+      sessionID: input.sessionID,
+      sessionState: input.sessionState,
+      options: input.options,
+    })
+  } finally {
+    input.sessionState.isInjectingContinuation = false
   }
 }
 
@@ -83,6 +130,14 @@ function scheduleRetry(input: {
     if (sessionState.promptFailureCount >= MAX_CONSECUTIVE_PROMPT_FAILURES) return
     if (sessionState.waitingForFinalWaveApproval) return
 
+    const now = Date.now()
+    if (
+      sessionState.lastContinuationInjectedAt
+      && now - sessionState.lastContinuationInjectedAt < CONTINUATION_COOLDOWN_MS
+    ) {
+      return
+    }
+
     const currentBoulder = readBoulderState(ctx.directory)
     if (!currentBoulder) return
     if (!currentBoulder.session_ids?.includes(sessionID)) return