fix(plugin): normalize event session ids

Handle OpenCode session events that carry the session ID under properties.info.id or properties.info.sessionID so background tasks and continuation hooks do not miss idle/error/delete events.

Add regression coverage for nested session.idle events completing background tasks and waking continuation hooks.

src/hooks/compaction-context-injector/hook.ts

@@ -3,6 +3,7 @@ import {
   clearCompactionAgentConfigCheckpoint,
   setCompactionAgentConfigCheckpoint,
 } from "../../shared/compaction-agent-config-checkpoint"
+import { resolveMessageEventSessionID } from "../../shared/event-session-id"
 import { log } from "../../shared/logger"
 import { COMPACTION_CONTEXT_PROMPT } from "./compaction-context-prompt"
 import { resolveSessionPromptConfig } from "./session-prompt-config-resolver"
@@ -121,14 +122,15 @@ export function createCompactionContextInjector(options?: {
         sessionID?: string
       } | undefined
 
-      if (!info?.sessionID || info.role !== "assistant" || !info.id) {
+      const sessionID = resolveMessageEventSessionID(props)
+      if (!sessionID || info?.role !== "assistant" || !info.id) {
         return
       }
 
-      const tailState = getTailState(info.sessionID)
+      const tailState = getTailState(sessionID)
       if (tailState.currentMessageID && tailState.currentMessageID !== info.id) {
         finalizeTrackedAssistantMessage(tailState)
-        await maybeWarnAboutNoTextTail(info.sessionID)
+        await maybeWarnAboutNoTextTail(sessionID)
       }
 
       if (tailState.currentMessageID !== info.id) {
@@ -139,7 +141,7 @@ export function createCompactionContextInjector(options?: {
     }
 
     if (event.type === "message.part.delta") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveMessageEventSessionID(props)
       const messageID = props?.messageID as string | undefined
       const field = props?.field as string | undefined
       const delta = props?.delta as string | undefined

src/hooks/compaction-context-injector/session-id.ts

@@ -1,8 +1,9 @@
+import { resolveSessionEventID } from "../../shared/event-session-id"
+
 export function isCompactionAgent(agent: string | undefined): boolean {
   return agent?.trim().toLowerCase() === "compaction"
 }
 
 export function resolveSessionID(props?: Record<string, unknown>): string | undefined {
-  return (props?.sessionID ??
-    (props?.info as { id?: string } | undefined)?.id) as string | undefined
+  return resolveSessionEventID(props)
 }