feat(run): implement boulder lineage detection in continuation state

Make getContinuationState async to support client-side lineage checks.
Add hasActiveBoulderContinuation with agent eligibility verification
and subagent session tracking for proper boulder session inheritance.

🤖 Generated with assistance of OhMyOpenCode

src/cli/run/continuation-state.ts

@@ -1,10 +1,18 @@
 import { getPlanProgress, readBoulderState } from "../../features/boulder-state"
+import {
+  getSessionAgent,
+  isAgentRegistered,
+  subagentSessions,
+} from "../../features/claude-code-session-state"
 import {
   getActiveContinuationMarkerReason,
   isContinuationMarkerActive,
   readContinuationMarker,
 } from "../../features/run-continuation-state"
+import { isSessionInBoulderLineage } from "../../hooks/atlas/boulder-session-lineage"
+import { getAgentConfigKey } from "../../shared/agent-display-names"
 import { readState as readRalphLoopState } from "../../hooks/ralph-loop/storage"
+import type { RunContext } from "./types"
 
 export interface ContinuationState {
   hasActiveBoulder: boolean
@@ -15,11 +23,15 @@ export interface ContinuationState {
   activeHookMarkerReason: string | null
 }
 
-export function getContinuationState(directory: string, sessionID: string): ContinuationState {
+export async function getContinuationState(
+  directory: string,
+  sessionID: string,
+  client?: RunContext["client"],
+): Promise<ContinuationState> {
   const marker = readContinuationMarker(directory, sessionID)
 
   return {
-    hasActiveBoulder: hasActiveBoulderContinuation(directory, sessionID),
+    hasActiveBoulder: await hasActiveBoulderContinuation(directory, sessionID, client),
     hasActiveRalphLoop: hasActiveRalphLoopContinuation(directory, sessionID),
     hasHookMarker: marker !== null,
     hasTodoHookMarker: marker?.sources.todo !== undefined,
@@ -28,13 +40,41 @@ export function getContinuationState(directory: string, sessionID: string): Cont
   }
 }
 
-function hasActiveBoulderContinuation(directory: string, sessionID: string): boolean {
+async function hasActiveBoulderContinuation(
+  directory: string,
+  sessionID: string,
+  client?: RunContext["client"],
+): Promise<boolean> {
   const boulder = readBoulderState(directory)
   if (!boulder) return false
-  if (!boulder.session_ids.includes(sessionID)) return false
 
   const progress = getPlanProgress(boulder.active_plan)
-  return !progress.isComplete
+  if (progress.isComplete) return false
+  if (boulder.session_ids.includes(sessionID)) return true
+  if (!client) return false
+  if (!subagentSessions.has(sessionID)) return false
+
+  const requiredAgentName = boulder.agent ?? (isAgentRegistered("atlas") ? "atlas" : undefined)
+  if (!requiredAgentName || !isAgentRegistered(requiredAgentName)) {
+    return false
+  }
+
+  const sessionAgent = getSessionAgent(sessionID)
+  const agentKey = getAgentConfigKey(sessionAgent ?? "")
+  const requiredAgentKey = getAgentConfigKey(requiredAgentName)
+  const isEligibleSubagent =
+    agentKey === requiredAgentKey
+    || (requiredAgentKey === getAgentConfigKey("atlas") && agentKey === getAgentConfigKey("sisyphus"))
+
+  if (!isEligibleSubagent) {
+    return false
+  }
+
+  return isSessionInBoulderLineage({
+    client,
+    sessionID,
+    boulderSessionIDs: boulder.session_ids,
+  })
 }
 
 function hasActiveRalphLoopContinuation(directory: string, sessionID: string): boolean {