Merge pull request #3964 from code-yeongyu/fix/electron-bun-runtime-shims

fix(electron): eliminate raw Bun.* runtime calls so plugin loads on OpenCode Desktop

.github/workflows/ci.yml

@@ -46,6 +46,9 @@ jobs:
         env:
           BUN_INSTALL_ALLOW_SCRIPTS: "@ast-grep/napi"
 
+      - name: Build plugin
+        run: bun run build
+
       - name: Run tests
         run: bun run script/run-ci-tests.ts
 

src/cli/config-manager/bun-install.ts

@@ -26,10 +26,6 @@ declare function clearTimeout(timeout: number): void
 
 type ProcessOutputStream = ReturnType<typeof spawnWithWindowsHide>["stdout"]
 
-declare const Bun: {
-  readableStreamToText(stream: NonNullable<ProcessOutputStream>): Promise<string>
-}
-
 export interface BunInstallResult {
   success: boolean
   timedOut?: boolean
@@ -50,7 +46,7 @@ function readProcessOutput(stream: ProcessOutputStream): Promise<string> {
     return Promise.resolve("")
   }
 
-  return Bun.readableStreamToText(stream)
+  return new Response(stream).text()
 }
 
 function logCapturedOutputOnFailure(outputMode: BunInstallOutputMode, output: BunInstallOutput): void {

src/features/background-agent/manager.test.ts

@@ -5023,6 +5023,54 @@ describe("BackgroundManager.handleEvent - session.error", () => {
     manager.shutdown()
   })
 
+  test("completes task when session.idle carries session id in info", async () => {
+    //#given
+    const sessionID = "ses-info-idle-completes-task"
+    const client = {
+      session: {
+        prompt: async () => ({}),
+        promptAsync: async () => ({}),
+        abort: async () => ({}),
+        messages: async () => ({
+          data: [
+            {
+              info: { role: "assistant" },
+              parts: [{ type: "text", text: "done" }],
+            },
+          ],
+        }),
+        todo: async () => ({ data: [] }),
+      },
+    }
+
+    const manager = new BackgroundManager({ pluginContext: createPluginInput(client) })
+    stubNotifyParentSession(manager)
+
+    const task = createMockTask({
+      id: "task-info-idle-completes",
+      sessionId: sessionID,
+      parentSessionId: "parent-session",
+      parentMessageId: "msg-info-idle",
+      description: "task completed by nested idle event",
+      agent: "explore",
+      status: "running",
+      startedAt: new Date(Date.now() - (MIN_IDLE_TIME_MS + 10)),
+    })
+    getTaskMap(manager).set(task.id, task)
+
+    //#when
+    manager.handleEvent({
+      type: "session.idle",
+      properties: { info: { id: sessionID } },
+    })
+    await new Promise((resolve) => setTimeout(resolve, 10))
+
+    //#then
+    expect(task.status).toBe("completed")
+
+    manager.shutdown()
+  })
+
   test("completes task on session.status idle after todo-continuation finishes", async () => {
     //#given
     const sessionID = "ses-status-idle-after-todo-continuation"
@@ -5747,6 +5795,54 @@ describe("BackgroundManager.handleEvent - non-tool event lastUpdate", () => {
     expect(task.progress!.toolCalls).toBe(2)
   })
 
+  test("should update lastUpdate when legacy message.part.updated only has part session id", () => {
+    //#given - a running task with stale lastUpdate
+    const client = {
+      session: {
+        prompt: async () => ({}),
+        promptAsync: async () => ({}),
+        abort: async () => ({}),
+      },
+    }
+    const manager = new BackgroundManager({ pluginContext: createPluginInput(client) })
+
+    const oldUpdate = new Date(Date.now() - 300_000)
+    const task: BackgroundTask = {
+      id: "task-part-only-1",
+      sessionId: "session-part-only-1",
+      parentSessionId: "parent-1",
+      parentMessageId: "msg-1",
+      description: "Legacy part-only task",
+      prompt: "Keep working",
+      agent: "oracle",
+      status: "running",
+      startedAt: new Date(Date.now() - 600_000),
+      progress: {
+        toolCalls: 0,
+        lastUpdate: oldUpdate,
+      },
+    }
+    getTaskMap(manager).set(task.id, task)
+
+    //#when - a legacy message.part.updated event arrives without top-level sessionID
+    manager.handleEvent({
+      type: "message.part.updated",
+      properties: {
+        part: {
+          id: "part-1",
+          messageID: "msg-1",
+          sessionID: "session-part-only-1",
+          type: "text",
+          text: "still working",
+        },
+      },
+    })
+
+    //#then - lastUpdate should be refreshed, toolCalls should remain 0
+    expect(task.progress!.lastUpdate.getTime()).toBeGreaterThan(oldUpdate.getTime())
+    expect(task.progress!.toolCalls).toBe(0)
+  })
+
   test("should update lastUpdate on thinking-type message.part.updated event", () => {
     //#given - a running task with stale lastUpdate
     const client = {

src/features/background-agent/manager.ts

@@ -18,6 +18,7 @@ import {
   resolveInheritedPromptTools,
   createInternalAgentTextPart,
 } from "../../shared"
+import { resolveMessageEventSessionID, resolveSessionEventID } from "../../shared/event-session-id"
 import { applySessionPromptParams } from "../../shared/session-prompt-params-helpers"
 import { setSessionTools } from "../../shared/session-tools-store"
 import { SessionCategoryRegistry } from "../../shared/session-category-registry"
@@ -118,7 +119,7 @@ interface MessagePartInfo {
 
 interface EventProperties {
   sessionID?: string
-  info?: { id?: string }
+  info?: { id?: string; sessionID?: string }
   [key: string]: unknown
 }
 
@@ -1260,8 +1261,9 @@ The fallback retry session is now created and can be inspected directly.
     this.observedIncompleteTodosBySession.delete(sessionID)
   }
 
-  private hasOutputSignalFromPart(partInfo: MessagePartInfo | undefined): boolean {
+  private hasOutputSignalFromPart(partInfo: MessagePartInfo | undefined, sessionID?: string): boolean {
-    if (!partInfo?.sessionID) return false
+    if (!partInfo) return false
+    if (!partInfo.sessionID && !sessionID) return false
     if (partInfo.tool) return true
     if (partInfo.type === "tool" || partInfo.type === "tool_result") return true
     if (partInfo.type === "text" || partInfo.type === "reasoning") return true
@@ -1279,9 +1281,9 @@ The fallback retry session is now created and can be inspected directly.
       const info = props?.info
       if (!info || typeof info !== "object") return
 
-      const sessionID = (info as Record<string, unknown>)["sessionID"]
+      const sessionID = resolveMessageEventSessionID(props)
       const role = (info as Record<string, unknown>)["role"]
-      if (typeof sessionID !== "string") return
+      if (!sessionID) return
 
       if (role === "tool") {
         this.markSessionOutputObserved(sessionID)
@@ -1312,7 +1314,7 @@ The fallback retry session is now created and can be inspected directly.
 
     if (event.type === "message.part.updated" || event.type === "message.part.delta") {
       const partInfo = resolveMessagePartInfo(props)
-      const sessionID = partInfo?.sessionID
+      const sessionID = resolveMessageEventSessionID(props)
       if (!sessionID) return
 
       const resolved = this.resolveTaskAttemptBySession(sessionID)
@@ -1320,7 +1322,7 @@ The fallback retry session is now created and can be inspected directly.
 
       const { task } = resolved
 
-      if (this.hasOutputSignalFromPart(partInfo)) {
+      if (this.hasOutputSignalFromPart(partInfo, sessionID)) {
         this.markSessionOutputObserved(sessionID)
       }
 
@@ -1404,7 +1406,7 @@ The fallback retry session is now created and can be inspected directly.
     }
 
     if (event.type === "todo.updated") {
-      const sessionID = typeof props?.sessionID === "string" ? props.sessionID : undefined
+      const sessionID = resolveSessionEventID(props)
       const todos = Array.isArray(props?.todos) ? props.todos : undefined
       if (!sessionID || !todos) return
 
@@ -1419,7 +1421,7 @@ The fallback retry session is now created and can be inspected directly.
 
     if (event.type === "session.idle") {
       if (!props || typeof props !== "object") return
-      const sessionID = typeof props.sessionID === "string" ? props.sessionID : undefined
+      const sessionID = resolveSessionEventID(props)
       if (sessionID) {
         void this.enqueueNotificationForParent(sessionID, () => this.flushPendingParentWake(sessionID)).catch((error) => {
           log("[background-agent] Failed to flush pending parent wake:", { sessionID, error })
@@ -1440,7 +1442,7 @@ The fallback retry session is now created and can be inspected directly.
     }
 
     if (event.type === "session.error") {
-      const sessionID = typeof props?.sessionID === "string" ? props.sessionID : undefined
+      const sessionID = resolveSessionEventID(props)
       if (!sessionID) return
 
       const resolved = this.resolveTaskAttemptBySession(sessionID)
@@ -1469,9 +1471,8 @@ The fallback retry session is now created and can be inspected directly.
     }
 
     if (event.type === "session.deleted") {
-      const info = props?.info
+      const sessionID = resolveSessionEventID(props)
-      if (!info || typeof info.id !== "string") return
+      if (!sessionID) return
-      const sessionID = info.id
       this.clearSessionOutputObserved(sessionID)
       this.clearSessionTodoObservation(sessionID)
 
@@ -1529,7 +1530,7 @@ The fallback retry session is now created and can be inspected directly.
     }
 
     if (event.type === "session.status") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveSessionEventID(props)
       const status = props?.status as { type?: string; message?: string } | undefined
       if (!sessionID || !status?.type) return
 

src/features/background-agent/session-idle-event-handler.ts

@@ -1,12 +1,8 @@
 import { log } from "../../shared"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { MIN_IDLE_TIME_MS } from "./constants"
 import type { BackgroundTask } from "./types"
 
-function getString(obj: Record<string, unknown>, key: string): string | undefined {
-  const value = obj[key]
-  return typeof value === "string" ? value : undefined
-}
-
 export function handleSessionIdleBackgroundEvent(args: {
   properties: Record<string, unknown>
   findBySession: (sessionID: string) => BackgroundTask | undefined
@@ -26,7 +22,7 @@ export function handleSessionIdleBackgroundEvent(args: {
     emitIdleEvent,
   } = args
 
-  const sessionID = getString(properties, "sessionID")
+  const sessionID = resolveSessionEventID(properties)
   if (!sessionID) return
 
   const task = findBySession(sessionID)

src/features/claude-code-mcp-loader/loader.ts

@@ -11,6 +11,7 @@ import type {
 import { transformMcpServer } from "./transformer"
 import { log } from "../../shared/logger"
 import { shouldLoadMcpServer } from "./scope-filter"
+import { bunFile } from "../../shared/bun-file-shim"
 
 interface McpConfigPath {
   path: string
@@ -37,7 +38,7 @@ async function loadMcpConfigFile(
   }
 
   try {
-    const content = await Bun.file(filePath).text()
+    const content = await bunFile(filePath).text()
     return JSON.parse(content) as ClaudeCodeMcpConfig
   } catch (error) {
     log(`Failed to load MCP config from ${filePath}`, error)

src/features/claude-code-plugin-loader/mcp-server-loader.ts

@@ -7,6 +7,7 @@ import type { ClaudeCodeMcpConfig } from "../claude-code-mcp-loader/types"
 import { log } from "../../shared/logger"
 import type { LoadedPlugin } from "./types"
 import { resolvePluginPaths } from "./plugin-path-resolver"
+import { bunFile } from "../../shared/bun-file-shim"
 
 export async function loadPluginMcpServers(
   plugins: LoadedPlugin[],
@@ -18,7 +19,7 @@ export async function loadPluginMcpServers(
     if (!plugin.mcpPath || !existsSync(plugin.mcpPath)) continue
 
     try {
-      const content = await Bun.file(plugin.mcpPath).text()
+      const content = await bunFile(plugin.mcpPath).text()
       let config = JSON.parse(content) as ClaudeCodeMcpConfig
 
       config = resolvePluginPaths(config, plugin.installPath)

src/features/mcp-oauth/callback-server.ts

@@ -1,3 +1,5 @@
+import { createServer, type IncomingMessage, type ServerResponse } from "node:http"
+
 import { findAvailablePort as findAvailablePortShared } from "../../shared/port-utils"
 
 const DEFAULT_PORT = 19877
@@ -51,56 +53,73 @@ export async function startCallbackServer(startPort: number = DEFAULT_PORT): Pro
 
   const timeoutId = setTimeout(() => {
     rejectCallback?.(new Error("OAuth callback timed out after 5 minutes"))
-    server.stop(true)
+    server.close()
   }, TIMEOUT_MS)
 
-  const server = Bun.serve({
+  const server = createServer((request: IncomingMessage, response: ServerResponse) => {
-    port: requestedPort,
+    const url = new URL(request.url ?? "/", "http://127.0.0.1")
-    hostname: "127.0.0.1",
-    fetch(request: Request): Response {
-      const url = new URL(request.url)
 
-      if (url.pathname !== "/oauth/callback") {
+    if (url.pathname !== "/oauth/callback") {
-        return new Response("Not Found", { status: 404 })
+      response.statusCode = 404
-      }
+      response.end("Not Found")
+      return
+    }
 
-      const oauthError = url.searchParams.get("error")
+    const oauthError = url.searchParams.get("error")
-      if (oauthError) {
+    if (oauthError) {
-        const description = url.searchParams.get("error_description") ?? oauthError
+      const description = url.searchParams.get("error_description") ?? oauthError
-        clearTimeout(timeoutId)
-        rejectCallback?.(new Error(`OAuth authorization failed: ${description}`))
-        setTimeout(() => server.stop(true), 100)
-        return new Response(`Authorization failed: ${description}`, { status: 400 })
-      }
-
-      const code = url.searchParams.get("code")
-      const state = url.searchParams.get("state")
-
-      if (!code || !state) {
-        clearTimeout(timeoutId)
-        rejectCallback?.(new Error("OAuth callback missing code or state parameter"))
-        setTimeout(() => server.stop(true), 100)
-        return new Response("Missing code or state parameter", { status: 400 })
-      }
-
-      resolveCallback?.({ code, state })
       clearTimeout(timeoutId)
+      rejectCallback?.(new Error(`OAuth authorization failed: ${description}`))
+      response.statusCode = 400
+      response.end(`Authorization failed: ${description}`)
+      setTimeout(() => server.close(), 100)
+      return
+    }
 
-      setTimeout(() => server.stop(true), 100)
+    const code = url.searchParams.get("code")
+    const state = url.searchParams.get("state")
 
-      return new Response(SUCCESS_HTML, {
+    if (!code || !state) {
-        headers: { "content-type": "text/html; charset=utf-8" },
+      clearTimeout(timeoutId)
-      })
+      rejectCallback?.(new Error("OAuth callback missing code or state parameter"))
-    },
+      response.statusCode = 400
+      response.end("Missing code or state parameter")
+      setTimeout(() => server.close(), 100)
+      return
+    }
+
+    resolveCallback?.({ code, state })
+    clearTimeout(timeoutId)
+
+    response.statusCode = 200
+    response.setHeader("content-type", "text/html; charset=utf-8")
+    response.end(SUCCESS_HTML)
+    setTimeout(() => server.close(), 100)
   })
-  const activePort = server.port ?? requestedPort
+
+  await new Promise<void>((resolve, reject) => {
+    const handleError = (error: Error): void => {
+      clearTimeout(timeoutId)
+      reject(error)
+    }
+
+    server.once("error", handleError)
+    server.once("listening", () => {
+      server.off("error", handleError)
+      resolve()
+    })
+    server.listen(requestedPort, "127.0.0.1")
+  })
+
+  const address = server.address()
+  const activePort = typeof address === "object" && address !== null ? address.port : requestedPort
 
   return {
     port: activePort,
     waitForCallback: () => callbackPromise,
     close: () => {
       clearTimeout(timeoutId)
-      server.stop(true)
+      server.close()
     },
   }
 }

src/features/team-mode/deps.ts

@@ -1,4 +1,5 @@
 import type { TeamModeConfig } from "../../config/schema/team-mode"
+import { spawn } from "../../shared/bun-spawn-shim"
 
 export interface TeamModeDependencyReport {
   tmuxAvailable: boolean
@@ -20,7 +21,7 @@ export async function checkTeamModeDependencies(
 
 async function probeBinary(cmd: string, args: string[]): Promise<boolean> {
   try {
-    const proc = Bun.spawn({ cmd: [cmd, ...args], stdout: "pipe", stderr: "pipe" })
+    const proc = spawn({ cmd: [cmd, ...args], stdout: "pipe", stderr: "pipe" })
     const code = await proc.exited
     return code === 0
   } catch {

src/features/tmux-subagent/manager.ts

@@ -2,6 +2,7 @@ import type { PluginInput } from "@opencode-ai/plugin"
 import type { TmuxConfig } from "../../config/schema"
 import type { TrackedSession, CapacityConfig, WindowState } from "./types"
 import * as sharedModule from "../../shared"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import {
   isInsideTmux as defaultIsInsideTmux,
   getCurrentPaneId as defaultGetCurrentPaneId,
@@ -1098,9 +1099,9 @@ export class TmuxSessionManager {
     if (event.type !== "session.created") return
 
     const info = event.properties?.info
-    if (!info?.id || !info?.parentID) return
+    const sessionId = resolveSessionEventID(event.properties)
+    if (!sessionId || !info?.parentID) return
 
-    const sessionId = info.id
     const title = info.title ?? "Subagent"
 
     if (!this.sourcePaneId) {

src/features/tmux-subagent/polling-manager-event-session-id.test.ts

@@ -0,0 +1,43 @@
+import { describe, expect, test } from "bun:test"
+
+import { TmuxPollingManager } from "./polling-manager"
+import type { TrackedSession } from "./types"
+
+describe("TmuxPollingManager event session ids", () => {
+  test("#given legacy message.part.updated properties #when handling activity #then part session id increments activity version", () => {
+    const sessions = new Map<string, TrackedSession>()
+    sessions.set("ses-part-only", {
+      sessionId: "ses-part-only",
+      paneId: "%1",
+      description: "test",
+      createdAt: new Date(),
+      lastSeenAt: new Date(),
+      closePending: false,
+      closeRetryCount: 0,
+      activityVersion: 0,
+    })
+
+    const client = {
+      session: {
+        status: async () => ({ data: {} }),
+        messages: async () => ({ data: [] }),
+      },
+    }
+    const manager = new TmuxPollingManager(client as never, sessions, async () => {})
+
+    manager.handleEvent({
+      type: "message.part.updated",
+      properties: {
+        part: {
+          id: "part-1",
+          messageID: "msg-1",
+          sessionID: "ses-part-only",
+          type: "text",
+          text: "working",
+        },
+      },
+    })
+
+    expect(sessions.get("ses-part-only")?.activityVersion).toBe(1)
+  })
+})

src/features/tmux-subagent/polling-manager.ts

@@ -7,6 +7,7 @@ import {
 import type { TrackedSession } from "./types"
 import { log } from "../../shared"
 import { normalizeSDKResponse } from "../../shared"
+import { resolveMessageEventSessionID } from "../../shared/event-session-id"
 
 const MIN_STABILITY_TIME_MS = 10 * 1000
 const STABLE_POLLS_REQUIRED = 3
@@ -170,10 +171,7 @@ export class TmuxPollingManager {
     if (!properties) return undefined
 
     if (event.type === "message.updated") {
-      const info = properties.info
+      return resolveMessageEventSessionID(properties)
-      if (!info || typeof info !== "object") return undefined
-      const sessionId = (info as { sessionID?: unknown }).sessionID
-      return typeof sessionId === "string" ? sessionId : undefined
     }
 
     if (
@@ -182,8 +180,7 @@ export class TmuxPollingManager {
       || event.type === "message.part.removed"
       || event.type === "message.removed"
     ) {
-      const sessionId = properties.sessionID
+      return resolveMessageEventSessionID(properties)
-      return typeof sessionId === "string" ? sessionId : undefined
     }
 
     return undefined

src/features/tmux-subagent/session-created-handler.ts

@@ -2,6 +2,7 @@ import type { PluginInput } from "@opencode-ai/plugin"
 import type { TmuxConfig } from "../../config/schema"
 import type { CapacityConfig, TrackedSession } from "./types"
 import { log } from "../../shared"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { queryWindowState } from "./pane-state-querier"
 import { decideSpawnActions, type SessionMapping } from "./decision-engine"
 import { executeActions } from "./action-executor"
@@ -44,9 +45,9 @@ export async function handleSessionCreated(
   if (event.type !== "session.created") return
 
   const info = event.properties?.info
-  if (!info?.id || !info?.parentID) return
+  const sessionId = resolveSessionEventID(event.properties)
+  if (!sessionId || !info?.parentID) return
 
-  const sessionId = info.id
   const title = info.title ?? "Subagent"
 
   if (deps.sessions.has(sessionId) || deps.pendingSessions.has(sessionId)) {

src/hooks/agent-usage-reminder/hook.ts

@@ -8,6 +8,7 @@ import { TARGET_TOOLS, AGENT_TOOLS, REMINDER_MESSAGE } from "./constants";
 import type { AgentUsageState } from "./types";
 import { getSessionAgent } from "../../features/claude-code-session-state";
 import { getAgentConfigKey } from "../../shared/agent-display-names";
+import { resolveSessionEventID } from "../../shared/event-session-id";
 
 interface ToolExecuteInput {
   tool: string;
@@ -112,15 +113,14 @@ export function createAgentUsageReminderHook(_ctx: PluginInput) {
     const props = event.properties as Record<string, unknown> | undefined;
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined;
+      const sessionID = resolveSessionEventID(props);
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        resetState(sessionInfo.id);
+        resetState(sessionID);
       }
     }
 
     if (event.type === "session.compacted") {
-      const sessionID = (props?.sessionID ??
+      const sessionID = resolveSessionEventID(props);
-        (props?.info as { id?: string } | undefined)?.id) as string | undefined;
       if (sessionID) {
         resetState(sessionID);
       }

src/hooks/anthropic-context-window-limit-recovery/recovery-hook.ts

@@ -7,6 +7,7 @@ import { executeCompact, getLastAssistant } from "./executor"
 import { attemptDeduplicationRecovery } from "./deduplication-recovery"
 import { clearSessionState } from "./state"
 import { clearAllSessionTimeouts, clearSessionTimeout } from "./session-timeout-map"
+import { resolveMessageEventSessionID, resolveSessionEventID } from "../../shared/event-session-id"
 import { log } from "../../shared/logger"
 
 export interface AnthropicContextWindowLimitRecoveryOptions {
@@ -53,17 +54,17 @@ export function createAnthropicContextWindowLimitRecoveryHook(
     const props = event.properties as Record<string, unknown> | undefined
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined
+      const sessionID = resolveSessionEventID(props)
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        clearSessionTimeout(pendingCompactionTimeoutBySession, sessionInfo.id)
+        clearSessionTimeout(pendingCompactionTimeoutBySession, sessionID)
 
-        clearSessionState(autoCompactState, sessionInfo.id)
+        clearSessionState(autoCompactState, sessionID)
       }
       return
     }
 
     if (event.type === "session.error") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveSessionEventID(props)
       dependencies.log("[auto-compact] session.error received", { sessionID, error: props?.error })
       if (!sessionID) return
 
@@ -120,7 +121,7 @@ export function createAnthropicContextWindowLimitRecoveryHook(
 
     if (event.type === "message.updated") {
       const info = props?.info as Record<string, unknown> | undefined
-      const sessionID = info?.sessionID as string | undefined
+      const sessionID = resolveMessageEventSessionID(props)
 
       if (sessionID && info?.role === "assistant" && info.error) {
         dependencies.log("[auto-compact] message.updated with error", { sessionID, error: info.error })
@@ -137,7 +138,7 @@ export function createAnthropicContextWindowLimitRecoveryHook(
     }
 
     if (event.type === "session.idle") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveSessionEventID(props)
       if (!sessionID) return
 
       if (!autoCompactState.pendingCompact.has(sessionID)) return

src/hooks/atlas/event-handler.ts

@@ -1,5 +1,6 @@
 import type { PluginInput } from "@opencode-ai/plugin"
 import { log } from "../../shared/logger"
+import { resolveMessageEventSessionID, resolveSessionEventID } from "../../shared/event-session-id"
 import { HOOK_NAME } from "./hook-name"
 import { isAbortError } from "./is-abort-error"
 import { handleAtlasSessionIdle } from "./idle-event"
@@ -17,7 +18,7 @@ export function createAtlasEventHandler(input: {
     const props = event.properties as Record<string, unknown> | undefined
 
     if (event.type === "session.error") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveSessionEventID(props)
       if (!sessionID) return
 
       const state = getState(sessionID)
@@ -39,7 +40,7 @@ export function createAtlasEventHandler(input: {
     }
 
     if (event.type === "session.idle") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveSessionEventID(props)
       if (!sessionID) return
       await handleAtlasSessionIdle({ ctx, options, getState, sessionID })
       return
@@ -47,7 +48,7 @@ export function createAtlasEventHandler(input: {
 
     if (event.type === "message.updated") {
       const info = props?.info as Record<string, unknown> | undefined
-      const sessionID = info?.sessionID as string | undefined
+      const sessionID = resolveMessageEventSessionID(props)
       const role = info?.role as string | undefined
       if (!sessionID) return
 
@@ -64,7 +65,7 @@ export function createAtlasEventHandler(input: {
 
     if (event.type === "message.part.updated") {
       const info = props?.info as Record<string, unknown> | undefined
-      const sessionID = info?.sessionID as string | undefined
+      const sessionID = resolveMessageEventSessionID(props)
       const role = info?.role as string | undefined
 
       if (sessionID && role === "assistant") {
@@ -78,7 +79,7 @@ export function createAtlasEventHandler(input: {
     }
 
     if (event.type === "tool.execute.before" || event.type === "tool.execute.after") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveMessageEventSessionID(props)
       if (sessionID) {
         const state = sessions.get(sessionID)
         if (state) {
@@ -90,20 +91,20 @@ export function createAtlasEventHandler(input: {
     }
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined
+      const sessionID = resolveSessionEventID(props)
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        const deletedState = sessions.get(sessionInfo.id)
+        const deletedState = sessions.get(sessionID)
         if (deletedState?.pendingRetryTimer) {
           clearTimeout(deletedState.pendingRetryTimer)
         }
-        sessions.delete(sessionInfo.id)
+        sessions.delete(sessionID)
-        log(`[${HOOK_NAME}] Session deleted: cleaned up`, { sessionID: sessionInfo.id })
+        log(`[${HOOK_NAME}] Session deleted: cleaned up`, { sessionID })
       }
       return
     }
 
     if (event.type === "session.compacted") {
-      const sessionID = (props?.sessionID ?? (props?.info as { id?: string } | undefined)?.id) as string | undefined
+      const sessionID = resolveSessionEventID(props)
       if (sessionID) {
         const compactedState = sessions.get(sessionID)
         if (compactedState?.pendingRetryTimer) {

src/hooks/atlas/index.test.ts

@@ -1347,6 +1347,38 @@ session_id: ses_untrusted_999
       expect(callArgs.body.parts[0].text).toContain("2 remaining")
     })
 
+    test("should inject continuation when idle event carries session id in info", async () => {
+      // given - boulder state with incomplete plan and nested session event shape
+      const planPath = join(TEST_DIR, "test-plan-info-idle.md")
+      writeFileSync(planPath, "# Plan\n- [ ] Task 1\n- [x] Task 2\n- [ ] Task 3")
+
+      const state: BoulderState = {
+        active_plan: planPath,
+        started_at: "2026-01-02T10:00:00Z",
+        session_ids: [MAIN_SESSION_ID],
+        plan_name: "test-plan-info-idle",
+      }
+      writeBoulderState(TEST_DIR, state)
+
+      const mockInput = createMockPluginInput()
+      const hook = createTestAtlasHook(mockInput)
+
+      // when
+      await hook.handler({
+        event: {
+          type: "session.idle",
+          properties: { info: { id: MAIN_SESSION_ID } },
+        },
+      })
+
+      // then - should call prompt with continuation
+      expect(mockInput._promptMock).toHaveBeenCalled()
+      const callArgs = mockInput._promptMock.mock.calls[0][0]
+      expect(callArgs.path.id).toBe(MAIN_SESSION_ID)
+      expect(callArgs.body.parts[0].text).toContain("incomplete tasks")
+      expect(callArgs.body.parts[0].text).toContain("2 remaining")
+    })
+
     test("should settle idle before injecting boulder continuation", async () => {
       // given
       const planPath = join(TEST_DIR, "test-plan.md")

src/hooks/auto-slash-command/hook.ts

@@ -5,6 +5,7 @@ import {
 } from "./detector"
 import { executeSlashCommand, type ExecutorOptions } from "./executor"
 import { log } from "../../shared"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import {
   AUTO_SLASH_COMMAND_TAG_CLOSE,
   AUTO_SLASH_COMMAND_TAG_OPEN,
@@ -25,16 +26,7 @@ function isRecord(value: unknown): value is Record<string, unknown> {
 }
 
 function getDeletedSessionID(properties: unknown): string | null {
-  if (!isRecord(properties)) {
+  return resolveSessionEventID(properties) ?? null
-    return null
-  }
-
-  const info = properties.info
-  if (!isRecord(info)) {
-    return null
-  }
-
-  return typeof info.id === "string" ? info.id : null
 }
 
 function getCommandExecutionEventID(input: CommandExecuteBeforeInput): string | null {
@@ -49,7 +41,7 @@ function getCommandExecutionEventID(input: CommandExecuteBeforeInput): string |
     "commandId",
   ]
 
-  const recordInput = input as unknown
+  const recordInput: unknown = input
   if (!isRecord(recordInput)) {
     return null
   }

src/hooks/category-skill-reminder/hook.ts

@@ -3,6 +3,7 @@ import type { AvailableSkill } from "../../agents/dynamic-agent-prompt-builder"
 import { getSessionAgent } from "../../features/claude-code-session-state"
 import { log } from "../../shared"
 import { getAgentConfigKey } from "../../shared/agent-display-names"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { buildReminderMessage } from "./formatter"
 
 /**
@@ -120,15 +121,14 @@ export function createCategorySkillReminderHook(
     const props = event.properties as Record<string, unknown> | undefined
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined
+      const sessionID = resolveSessionEventID(props)
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        sessionStates.delete(sessionInfo.id)
+        sessionStates.delete(sessionID)
       }
     }
 
     if (event.type === "session.compacted") {
-      const sessionID = (props?.sessionID ??
+      const sessionID = resolveSessionEventID(props)
-        (props?.info as { id?: string } | undefined)?.id) as string | undefined
       if (sessionID) {
         sessionStates.delete(sessionID)
       }

src/hooks/claude-code-hooks/config-loader.ts

@@ -3,6 +3,7 @@ import { join } from "path"
 import type { ClaudeHookEvent } from "./types"
 import { log } from "../../shared/logger"
 import { getOpenCodeConfigDir } from "../../shared"
+import { bunFile } from "../../shared/bun-file-shim"
 
 const CONFIG_CACHE_TTL_MS = 30_000
 
@@ -61,7 +62,7 @@ async function loadConfigFromPath(path: string): Promise<PluginExtendedConfig |
   }
 
   try {
-    const content = await Bun.file(path).text()
+    const content = await bunFile(path).text()
     return JSON.parse(content) as PluginExtendedConfig
   } catch (error) {
     log("Failed to load config", { path, error })

src/hooks/claude-code-hooks/config.ts

@@ -1,6 +1,7 @@
 import { join } from "path"
 import { existsSync } from "fs"
 import { getClaudeConfigDir } from "../../shared"
+import { bunFile } from "../../shared/bun-file-shim"
 import type { ClaudeHooksConfig, HookMatcher, HookAction } from "./types"
 
 const CONFIG_CACHE_TTL_MS = 30_000
@@ -126,7 +127,7 @@ export async function loadClaudeHooksConfig(
   for (const settingsPath of paths) {
     if (existsSync(settingsPath)) {
       try {
-        const content = await Bun.file(settingsPath).text()
+        const content = await bunFile(settingsPath).text()
         const settings = JSON.parse(content) as { hooks?: RawClaudeHooksConfig }
         if (settings.hooks) {
           const normalizedHooks = normalizeHooksConfig(settings.hooks)

src/hooks/claude-code-hooks/handlers/session-event-handler.ts

@@ -7,6 +7,7 @@ import { clearTranscriptCache } from "../transcript"
 import { clearToolInputCache, stopToolInputCacheCleanup } from "../tool-input-cache"
 import type { PluginConfig } from "../types"
 import { createInternalAgentTextPart, isHookDisabled, log } from "../../../shared"
+import { resolveSessionEventID } from "../../../shared/event-session-id"
 import {
 	clearAllSessionHookState,
 	clearSessionHookState,
@@ -26,7 +27,7 @@ export function createSessionEventHandler(
 
 		if (event.type === "session.error") {
 			const props = event.properties as Record<string, unknown> | undefined
-			const sessionID = props?.sessionID as string | undefined
+			const sessionID = resolveSessionEventID(props)
 			if (sessionID) {
 				sessionErrorState.set(sessionID, {
 					hasError: true,
@@ -38,13 +39,13 @@ export function createSessionEventHandler(
 
 		if (event.type === "session.deleted") {
 			const props = event.properties as Record<string, unknown> | undefined
-			const sessionInfo = props?.info as { id?: string } | undefined
+			const sessionID = resolveSessionEventID(props)
-			if (sessionInfo?.id) {
+			if (sessionID) {
-				parentSessionIdCache.delete(sessionInfo.id)
+				parentSessionIdCache.delete(sessionID)
-				clearTranscriptCache(sessionInfo.id)
+				clearTranscriptCache(sessionID)
-				clearToolInputCache(sessionInfo.id)
+				clearToolInputCache(sessionID)
-				contextCollector?.clear(sessionInfo.id)
+				contextCollector?.clear(sessionID)
-				clearSessionHookState(sessionInfo.id)
+				clearSessionHookState(sessionID)
 			}
 			return
 		}
@@ -54,7 +55,7 @@ export function createSessionEventHandler(
 		}
 
 		const props = event.properties as Record<string, unknown> | undefined
-		const sessionID = props?.sessionID as string | undefined
+		const sessionID = resolveSessionEventID(props)
 		if (!sessionID) return
 
 		const claudeConfig = await loadClaudeHooksConfig()

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 ??
+  return resolveSessionEventID(props)
-    (props?.info as { id?: string } | undefined)?.id) as string | undefined
 }

src/hooks/compaction-todo-preserver/hook.ts

@@ -1,4 +1,5 @@
 import type { PluginInput } from "@opencode-ai/plugin"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { log } from "../../shared/logger"
 
 interface TodoSnapshot {
@@ -97,8 +98,7 @@ async function resolveTodoWriter(): Promise<TodoWriter | null> {
 }
 
 function resolveSessionID(props?: Record<string, unknown>): string | undefined {
-  return (props?.sessionID ??
+  return resolveSessionEventID(props)
-    (props?.info as { id?: string } | undefined)?.id) as string | undefined
 }
 
 export interface CompactionTodoPreserver {

src/hooks/context-window-monitor.ts

@@ -4,6 +4,7 @@ import {
   type ContextLimitModelCacheState,
 } from "../shared/context-limit-resolver"
 import { isCompactionAgent } from "../shared/compaction-marker"
+import { resolveMessageEventSessionID, resolveSessionEventID } from "../shared/event-session-id"
 import { createSystemDirective, SystemDirectiveTypes } from "../shared/system-directive"
 
 const CONTEXT_WARNING_THRESHOLD = 0.70
@@ -86,10 +87,10 @@ export function createContextWindowMonitorHook(
     const props = event.properties as Record<string, unknown> | undefined
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined
+      const sessionID = resolveSessionEventID(props)
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        remindedSessions.delete(sessionInfo.id)
+        remindedSessions.delete(sessionID)
-        tokenCache.delete(sessionInfo.id)
+        tokenCache.delete(sessionID)
       }
     }
 
@@ -106,9 +107,10 @@ export function createContextWindowMonitorHook(
 
       if (!info || info.role !== "assistant" || !info.finish) return
       if (isCompactionAgent(info.agent)) return
-      if (!info.sessionID || !info.providerID || !info.tokens) return
+      const sessionID = resolveMessageEventSessionID(props)
+      if (!sessionID || !info.providerID || !info.tokens) return
 
-      tokenCache.set(info.sessionID, {
+      tokenCache.set(sessionID, {
         providerID: info.providerID,
         modelID: info.modelID ?? "",
         tokens: info.tokens,

src/hooks/directory-agents-injector/hook.ts

@@ -1,6 +1,7 @@
 import type { PluginInput } from "@opencode-ai/plugin";
 
 import { createDynamicTruncator } from "../../shared/dynamic-truncator";
+import { resolveSessionEventID } from "../../shared/event-session-id";
 import { processFilePathForAgentsInjection } from "./injector";
 import { clearInjectedPaths } from "./storage";
 
@@ -56,16 +57,15 @@ export function createDirectoryAgentsInjectorHook(
     const props = event.properties as Record<string, unknown> | undefined;
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined;
+      const sessionID = resolveSessionEventID(props);
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        sessionCaches.delete(sessionInfo.id);
+        sessionCaches.delete(sessionID);
-        clearInjectedPaths(sessionInfo.id);
+        clearInjectedPaths(sessionID);
       }
     }
 
     if (event.type === "session.compacted") {
-      const sessionID = (props?.sessionID ??
+      const sessionID = resolveSessionEventID(props);
-        (props?.info as { id?: string } | undefined)?.id) as string | undefined;
       if (sessionID) {
         sessionCaches.delete(sessionID);
         clearInjectedPaths(sessionID);

src/hooks/directory-readme-injector/hook.ts

@@ -1,6 +1,7 @@
 import type { PluginInput } from "@opencode-ai/plugin";
 
 import { createDynamicTruncator } from "../../shared/dynamic-truncator";
+import { resolveSessionEventID } from "../../shared/event-session-id";
 import { processFilePathForReadmeInjection } from "./injector";
 import { clearInjectedPaths } from "./storage";
 
@@ -56,16 +57,15 @@ export function createDirectoryReadmeInjectorHook(
     const props = event.properties as Record<string, unknown> | undefined;
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined;
+      const sessionID = resolveSessionEventID(props);
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        sessionCaches.delete(sessionInfo.id);
+        sessionCaches.delete(sessionID);
-        clearInjectedPaths(sessionInfo.id);
+        clearInjectedPaths(sessionID);
       }
     }
 
     if (event.type === "session.compacted") {
-      const sessionID = (props?.sessionID ??
+      const sessionID = resolveSessionEventID(props);
-        (props?.info as { id?: string } | undefined)?.id) as string | undefined;
       if (sessionID) {
         sessionCaches.delete(sessionID);
         clearInjectedPaths(sessionID);

src/hooks/hashline-edit-diff-enhancer/hook.ts

@@ -1,4 +1,5 @@
 import { log } from "../../shared"
+import { bunFile } from "../../shared/bun-file-shim"
 import { generateUnifiedDiff, countLineDiffs } from "../../tools/hashline-edit/diff-utils"
 
 interface HashlineEditDiffEnhancerConfig {
@@ -38,7 +39,7 @@ function extractFilePath(args: Record<string, unknown>): string | undefined {
 
 async function captureOldContent(filePath: string): Promise<string> {
 	try {
-		const file = Bun.file(filePath)
+		const file = bunFile(filePath)
 		if (await file.exists()) {
 			return await file.text()
 		}
@@ -79,7 +80,7 @@ export function createHashlineEditDiffEnhancerHook(config: HashlineEditDiffEnhan
 
 			let newContent: string
 			try {
-				newContent = await Bun.file(filePath).text()
+				newContent = await bunFile(filePath).text()
 			} catch {
 				log("[hashline-edit-diff-enhancer] failed to read new content", { filePath })
 				return

src/hooks/hashline-read-enhancer/hook.ts

@@ -1,4 +1,5 @@
 import type { PluginInput } from "@opencode-ai/plugin"
+import { bunFile } from "../../shared/bun-file-shim"
 import { computeLineHash } from "../../tools/hashline-edit/hash-computation"
 
 const WRITE_SUCCESS_MARKER = "File written successfully."
@@ -178,7 +179,7 @@ async function appendWriteHashlineOutput(output: { output: string; metadata: unk
     return
   }
 
-  const file = Bun.file(filePath)
+  const file = bunFile(filePath)
   if (!(await file.exists())) {
     return
   }

src/hooks/interactive-bash-session/hook.ts

@@ -5,6 +5,7 @@ import type { InteractiveBashSessionState } from "./types";
 import { tokenizeCommand, findSubcommand, extractSessionNameFromTokens } from "./parser";
 import { getOrCreateState, isOmoSession, killAllTrackedSessions } from "./state-manager";
 import { subagentSessions } from "../../features/claude-code-session-state";
+import { resolveSessionEventID } from "../../shared/event-session-id";
 
 interface ToolExecuteInput {
   tool: string;
@@ -106,8 +107,7 @@ export function createInteractiveBashSessionHook(ctx: PluginInput) {
     const props = event.properties as Record<string, unknown> | undefined;
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined;
+      const sessionID = resolveSessionEventID(props);
-      const sessionID = sessionInfo?.id;
 
       if (sessionID) {
         const state = getOrCreateStateLocal(sessionID);

src/hooks/preemptive-compaction.ts

@@ -1,5 +1,6 @@
 import type { OhMyOpenCodeConfig } from "../config"
 import { isCompactionAgent } from "../shared/compaction-marker"
+import { resolveMessageEventSessionID, resolveSessionEventID } from "../shared/event-session-id"
 import type { ContextLimitModelCacheState } from "../shared/context-limit-resolver"
 
 import { createPostCompactionDegradationMonitor } from "./preemptive-compaction-degradation-monitor"
@@ -48,7 +49,7 @@ export function createPreemptiveCompactionHook(
     const props = event.properties as Record<string, unknown> | undefined
 
     if (event.type === "session.deleted") {
-      const sessionID = (props?.info as { id?: string } | undefined)?.id
+      const sessionID = resolveSessionEventID(props)
       if (sessionID) {
         compactionInProgress.delete(sessionID)
         compactedSessions.delete(sessionID)
@@ -60,8 +61,7 @@ export function createPreemptiveCompactionHook(
     }
 
     if (event.type === "session.compacted") {
-      const sessionID = (props?.sessionID as string | undefined)
+      const sessionID = resolveSessionEventID(props)
-        ?? (props?.info as { id?: string } | undefined)?.id
       if (sessionID) {
         postCompactionMonitor.onSessionCompacted(sessionID)
       }
@@ -81,20 +81,21 @@ export function createPreemptiveCompactionHook(
         parts?: unknown
       } | undefined
 
-      if (!info || info.role !== "assistant" || !info.finish || !info.sessionID) return
+      const sessionID = resolveMessageEventSessionID(props)
+      if (!info || info.role !== "assistant" || !info.finish || !sessionID) return
       if (isCompactionAgent(info.agent)) return
 
       if (info.providerID && info.tokens) {
-        tokenCache.set(info.sessionID, {
+        tokenCache.set(sessionID, {
           providerID: info.providerID,
           modelID: info.modelID ?? "",
           tokens: info.tokens,
         })
       }
-      compactedSessions.delete(info.sessionID)
+      compactedSessions.delete(sessionID)
 
       await postCompactionMonitor.onAssistantMessageUpdated({
-        sessionID: info.sessionID,
+        sessionID,
         id: info.id,
         parts: info.parts,
       })

src/hooks/ralph-loop/index.test.ts

@@ -304,6 +304,25 @@ describe("ralph-loop", () => {
       expect(state?.iteration).toBe(2)
     })
 
+    test("should inject continuation when idle event carries session id in info", async () => {
+      // given - active loop state and nested session event shape
+      const hook = createRalphLoopHook(createMockPluginInput())
+      hook.startLoop("session-info-idle", "Build a feature", { maxIterations: 10 })
+
+      // when - session goes idle with id under info
+      await hook.event({
+        event: {
+          type: "session.idle",
+          properties: { info: { id: "session-info-idle" } },
+        },
+      })
+
+      // then - continuation should be injected for that session
+      expect(promptCalls.length).toBe(1)
+      expect(promptCalls[0].sessionID).toBe("session-info-idle")
+      expect(promptCalls[0].text).toContain("RALPH LOOP")
+    })
+
     test("should settle idle before injecting continuation", async () => {
       // given - active loop state with a configured idle settle delay
       const hook = createRalphLoopHook(createMockPluginInput(), { idleSettleMs: 25 })

src/hooks/ralph-loop/non-abort-error-continuation.test.ts

@@ -213,6 +213,77 @@ describe("ralph-loop non-abort error continuation", () => {
 		expect(hook.getState()?.iteration).toBe(3)
 	})
 
+	test("continues after retry run activity from legacy message.part.updated part session id", async () => {
+		// given - an active loop retries a recoverable runtime error
+		const hook = createRalphLoopHook({
+			directory: testDirectory,
+			project: testDirectory,
+			worktree: testDirectory,
+			serverUrl: "http://localhost:4096",
+			$: async () => ({}),
+			client: {
+				session: {
+					messages: async (options: { path: { id: string } }) => {
+						messagesCalls.push({ sessionID: options.path.id })
+						return { data: [] }
+					},
+					promptAsync: async (options: {
+						path: { id: string }
+						body: { parts: Array<{ type: string; text: string }> }
+					}) => {
+						promptCalls.push({
+							sessionID: options.path.id,
+							text: options.body.parts[0]?.text ?? "",
+						})
+						return {}
+					},
+					prompt: async () => ({}),
+				},
+				tui: {
+					showToast: async () => ({}),
+				},
+			},
+		} as never)
+
+		hook.startLoop("session-123", "Keep working", {
+			messageCountAtStart: 0,
+			maxIterations: 5,
+		})
+
+		await hook.event({
+			event: {
+				type: "session.error",
+				properties: {
+					sessionID: "session-123",
+					error: { name: "RuntimeError" },
+				},
+			},
+		})
+
+		// when - the retried run emits legacy assistant activity before any stale idle
+		await hook.event({
+			event: {
+				type: "message.part.updated",
+				properties: {
+					part: {
+						id: "part-1",
+						messageID: "msg-1",
+						sessionID: "session-123",
+						type: "text",
+						text: "working",
+					},
+				},
+			},
+		})
+		await hook.event({
+			event: { type: "session.idle", properties: { sessionID: "session-123" } },
+		})
+
+		// then - the real idle is allowed to continue the loop
+		expect(promptCalls).toHaveLength(2)
+		expect(hook.getState()?.iteration).toBe(3)
+	})
+
 	test("skips immediate runtime retry while background tasks are running", async () => {
 		// given - an active loop owns running background work
 		const hook = createRalphLoopHook({

src/hooks/ralph-loop/ralph-loop-event-handler.ts

@@ -1,5 +1,6 @@
 import type { PluginInput } from "@opencode-ai/plugin"
 import { log } from "../../shared/logger"
+import { resolveMessageEventSessionID, resolveSessionEventID } from "../../shared/event-session-id"
 import type { RalphLoopOptions, RalphLoopState } from "./types"
 import { HOOK_NAME } from "./constants"
 import { handleDetectedCompletion } from "./completion-handler"
@@ -36,12 +37,6 @@ function hasRunningBackgroundTasks(
 		: false
 }
 
-function getInfoSessionID(props: Record<string, unknown> | undefined): string | undefined {
-	const info = props?.info as Record<string, unknown> | undefined
-	const sessionID = info?.sessionID
-	return typeof sessionID === "string" ? sessionID : undefined
-}
-
 function getRuntimeRetryActivitySessionID(
 	eventType: string,
 	props: Record<string, unknown> | undefined,
@@ -49,20 +44,19 @@ function getRuntimeRetryActivitySessionID(
 	if (eventType === "message.updated") {
 		const info = props?.info as Record<string, unknown> | undefined
 		const role = info?.role
-		return role === "assistant" ? getInfoSessionID(props) : undefined
+		return role === "assistant" ? resolveMessageEventSessionID(props) : undefined
 	}
 
 	if (eventType === "message.part.updated") {
-		if (typeof props?.sessionID === "string") return props.sessionID
+		return resolveMessageEventSessionID(props)
-		return getInfoSessionID(props)
 	}
 
 	if (eventType === "message.part.delta") {
-		return typeof props?.sessionID === "string" ? props.sessionID : undefined
+		return resolveMessageEventSessionID(props)
 	}
 
 	if (eventType === "tool.execute.before" || eventType === "tool.execute.after") {
-		return typeof props?.sessionID === "string" ? props.sessionID : undefined
+		return resolveMessageEventSessionID(props)
 	}
 
 	return undefined
@@ -198,7 +192,7 @@ export function createRalphLoopEventHandler(
 		}
 
 		if (event.type === "session.idle") {
-			const sessionID = props?.sessionID as string | undefined
+			const sessionID = resolveSessionEventID(props)
 			if (!sessionID) return
 
 			if (inFlightSessions.has(sessionID)) {
@@ -389,7 +383,7 @@ export function createRalphLoopEventHandler(
 		}
 
 		if (event.type === "session.error") {
-			const sessionID = props?.sessionID as string | undefined
+			const sessionID = resolveSessionEventID(props)
 			const error = props?.error
 			if (!sessionID || isAbortError(error)) {
 				handleErroredLoopSession(props, options.loopState)

src/hooks/ralph-loop/session-event-handler.ts

@@ -1,4 +1,5 @@
 import { log } from "../../shared/logger"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { HOOK_NAME } from "./constants"
 import type { RalphLoopState } from "./types"
 
@@ -11,13 +12,13 @@ export function handleDeletedLoopSession(
 	props: Record<string, unknown> | undefined,
 	loopState: LoopStateController,
 ): boolean {
-	const sessionInfo = props?.info as { id?: string } | undefined
+	const sessionID = resolveSessionEventID(props)
-	if (!sessionInfo?.id) return false
+	if (!sessionID) return false
 
 	const state = loopState.getState()
-	if (state?.session_id === sessionInfo.id) {
+	if (state?.session_id === sessionID) {
 		loopState.clear()
-		log(`[${HOOK_NAME}] Session deleted, loop cleared`, { sessionID: sessionInfo.id })
+		log(`[${HOOK_NAME}] Session deleted, loop cleared`, { sessionID })
 	}
 	return true
 }
@@ -26,7 +27,7 @@ export function handleErroredLoopSession(
 	props: Record<string, unknown> | undefined,
 	loopState: LoopStateController,
 ): boolean {
-	const sessionID = props?.sessionID as string | undefined
+	const sessionID = resolveSessionEventID(props)
 	const error = props?.error as { name?: string } | undefined
 
 	if (error?.name === "MessageAbortedError") {

src/hooks/rules-injector/hook.ts

@@ -1,5 +1,6 @@
 import type { PluginInput } from "@opencode-ai/plugin";
 import { createDynamicTruncator } from "../../shared/dynamic-truncator";
+import { resolveSessionEventID } from "../../shared/event-session-id";
 import { getRuleInjectionFilePath } from "./output-path";
 import { createSessionCacheStore, createSessionRuleScanCacheStore } from "./cache";
 import { createRuleInjectionProcessor } from "./injector";
@@ -80,16 +81,15 @@ export function createRulesInjectorHook(
     const props = event.properties as Record<string, unknown> | undefined;
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined;
+      const sessionID = resolveSessionEventID(props);
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        clearSessionState(sessionInfo.id);
+        clearSessionState(sessionID);
       }
       clearProjectRootCache();
     }
 
     if (event.type === "session.compacted") {
-      const sessionID = (props?.sessionID ??
+      const sessionID = resolveSessionEventID(props);
-        (props?.info as { id?: string } | undefined)?.id) as string | undefined;
       if (sessionID) {
         clearSessionState(sessionID);
       }

src/hooks/runtime-fallback/event-handler.ts

@@ -10,6 +10,7 @@ import { isAbortError } from "../../shared/is-abort-error"
 import { resolveFallbackBootstrapModel } from "./fallback-bootstrap-model"
 import { dispatchFallbackRetry } from "./fallback-retry-dispatcher"
 import { createSessionStatusHandler } from "./session-status-handler"
+import { resolveMessageEventSessionID, resolveSessionEventID } from "../../shared/event-session-id"
 
 export function createEventHandler(deps: HookDeps, helpers: AutoRetryHelpers) {
   const { config, pluginConfig, sessionStates, sessionLastAccess, sessionRetryInFlight, sessionAwaitingFallbackResult, sessionFallbackTimeouts, sessionStatusRetryKeys } = deps
@@ -30,7 +31,7 @@ export function createEventHandler(deps: HookDeps, helpers: AutoRetryHelpers) {
 
   const handleSessionCreated = (props: Record<string, unknown> | undefined) => {
     const sessionInfo = props?.info as { id?: string; model?: string } | undefined
-    const sessionID = sessionInfo?.id
+    const sessionID = resolveSessionEventID(props)
     const model = sessionInfo?.model
 
     if (sessionID && model) {
@@ -41,8 +42,7 @@ export function createEventHandler(deps: HookDeps, helpers: AutoRetryHelpers) {
   }
 
   const handleSessionDeleted = (props: Record<string, unknown> | undefined) => {
-    const sessionInfo = props?.info as { id?: string } | undefined
+    const sessionID = resolveSessionEventID(props)
-    const sessionID = sessionInfo?.id
 
     if (sessionID) {
       log(`[${HOOK_NAME}] Cleaning up session state`, { sessionID })
@@ -58,7 +58,7 @@ export function createEventHandler(deps: HookDeps, helpers: AutoRetryHelpers) {
   }
 
   const handleSessionStop = async (props: Record<string, unknown> | undefined) => {
-    const sessionID = props?.sessionID as string | undefined
+    const sessionID = resolveSessionEventID(props)
     if (!sessionID) return
 
     if (sessionRetryInFlight.has(sessionID) || sessionAwaitingFallbackResult.has(sessionID)) {
@@ -73,7 +73,7 @@ export function createEventHandler(deps: HookDeps, helpers: AutoRetryHelpers) {
 
   const handleMessageUpdated = (props: Record<string, unknown> | undefined) => {
     const info = props?.info as Record<string, unknown> | undefined
-    const sessionID = info?.sessionID as string | undefined
+    const sessionID = resolveMessageEventSessionID(props)
     const role = info?.role as string | undefined
     if (!sessionID || role !== "user") return
 
@@ -81,7 +81,7 @@ export function createEventHandler(deps: HookDeps, helpers: AutoRetryHelpers) {
   }
 
   const handleSessionIdle = (props: Record<string, unknown> | undefined) => {
-    const sessionID = props?.sessionID as string | undefined
+    const sessionID = resolveSessionEventID(props)
     if (!sessionID) return
 
     if (cancelledSessions.has(sessionID)) {
@@ -111,7 +111,7 @@ export function createEventHandler(deps: HookDeps, helpers: AutoRetryHelpers) {
   }
 
   const handleSessionError = async (props: Record<string, unknown> | undefined) => {
-    const sessionID = props?.sessionID as string | undefined
+    const sessionID = resolveSessionEventID(props)
     const error = props?.error
     const agent = props?.agent as string | undefined
 

src/hooks/runtime-fallback/message-update-handler.ts

@@ -8,6 +8,7 @@ import { getFallbackModelsForSession } from "./fallback-models"
 import { resolveFallbackBootstrapModel } from "./fallback-bootstrap-model"
 import { dispatchFallbackRetry } from "./fallback-retry-dispatcher"
 import { hasVisibleAssistantResponse } from "./visible-assistant-response"
+import { resolveMessageEventSessionID } from "../../shared/event-session-id"
 
 export { hasVisibleAssistantResponse } from "./visible-assistant-response"
 
@@ -17,7 +18,7 @@ export function createMessageUpdateHandler(deps: HookDeps, helpers: AutoRetryHel
 
   return async (props: Record<string, unknown> | undefined) => {
     const info = props?.info as Record<string, unknown> | undefined
-    const sessionID = info?.sessionID as string | undefined
+    const sessionID = resolveMessageEventSessionID(props)
     const timeoutEnabled = config.timeout_seconds > 0
     const eventParts = props?.parts as Array<{ type?: string; text?: string }> | undefined
     const infoParts = info?.parts as Array<{ type?: string; text?: string }> | undefined

src/hooks/runtime-fallback/session-status-handler.ts

@@ -8,6 +8,7 @@ import { getFallbackModelsForSession } from "./fallback-models"
 import { normalizeRetryStatusMessage, extractRetryAttempt } from "../../shared/retry-status-utils"
 import { resolveFallbackBootstrapModel } from "./fallback-bootstrap-model"
 import { dispatchFallbackRetry } from "./fallback-retry-dispatcher"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 
 export function createSessionStatusHandler(
   deps: HookDeps,
@@ -22,7 +23,7 @@ export function createSessionStatusHandler(
   } = deps
 
   return async (props: Record<string, unknown> | undefined) => {
-    const sessionID = props?.sessionID as string | undefined
+    const sessionID = resolveSessionEventID(props)
     const status = props?.status as { type?: string; message?: string; attempt?: number } | undefined
     const agent = props?.agent as string | undefined
     const model = props?.model as string | undefined

src/hooks/session-notification-event-properties.ts

@@ -23,6 +23,15 @@ export function getSessionID(properties: EventProperties): string | undefined {
   const infoSessionId = info?.sessionId
   if (typeof infoSessionId === "string" && infoSessionId.length > 0) return infoSessionId
 
+  const part = properties?.part
+  if (isRecord(part)) {
+    const partSessionID = part.sessionID
+    if (typeof partSessionID === "string" && partSessionID.length > 0) return partSessionID
+
+    const partSessionId = part.sessionId
+    if (typeof partSessionId === "string" && partSessionId.length > 0) return partSessionId
+  }
+
   return undefined
 }
 

src/hooks/session-notification-utils.ts

@@ -1,14 +1,11 @@
 import { log } from "../shared/logger"
-
+import { bunWhich } from "../shared/bun-which-shim"
-declare const Bun: {
-  which(commandName: string): string | null
-}
 
 type Platform = "darwin" | "linux" | "win32" | "unsupported"
 
 async function findCommand(commandName: string): Promise<string | null> {
   try {
-    return Bun.which(commandName)
+    return bunWhich(commandName)
   } catch (error) {
     log("[session-notification] failed to resolve command path", {
       commandName,

src/hooks/session-notification.test.ts

@@ -375,6 +375,47 @@ describe("session-notification", () => {
     expect(notificationCalls).toHaveLength(0)
   })
 
+  test("should mark session activity on message.part.updated event with part session id", async () => {
+    // given - main session is set
+    const mainSessionID = "main-part-activity"
+    setMainSession(mainSessionID)
+
+    const hook = createSessionNotification(createMockPluginInput(), {
+      idleConfirmationDelay: 50,
+      skipIfIncompleteTodos: false,
+      activityGracePeriodMs: 0,
+    })
+
+    // when - session goes idle, then streamed assistant activity fires
+    await hook({
+      event: {
+        type: "session.idle",
+        properties: { sessionID: mainSessionID },
+      },
+    })
+
+    await hook({
+      event: {
+        type: "message.part.updated",
+        properties: {
+          part: {
+            id: "part-1",
+            messageID: "msg-1",
+            sessionID: mainSessionID,
+            type: "text",
+            text: "still working",
+          },
+        },
+      },
+    })
+
+    // Wait for idle delay to pass
+    await new Promise((resolve) => setTimeout(resolve, 100))
+
+    // then - notification should NOT be sent (streaming activity cancelled it)
+    expect(notificationCalls).toHaveLength(0)
+  })
+
   test("should mark session activity on tool.execute.before event", async () => {
     // given - main session is set
     const mainSessionID = "main-tool"

src/hooks/session-notification.ts

@@ -7,6 +7,7 @@ import { getEventToolName, getQuestionText, getSessionID } from "./session-notif
 import { hasIncompleteTodos } from "./session-todo-status"
 import { createIdleNotificationScheduler } from "./session-notification-scheduler"
 import { createSessionNotificationInit } from "./session-notification-init"
+import { resolveSessionEventID } from "../shared/event-session-id"
 
 interface SessionNotificationConfig {
   title?: string
@@ -98,8 +99,7 @@ export function createSessionNotification(ctx: PluginInput, config: SessionNotif
     const props = event.properties as Record<string, unknown> | undefined
 
     if (event.type === "session.created") {
-      const info = props?.info as Record<string, unknown> | undefined
+      const sessionID = resolveSessionEventID(props)
-      const sessionID = info?.id as string | undefined
       if (sessionID) scheduler.markSessionActivity(sessionID)
       return
     }
@@ -116,7 +116,11 @@ export function createSessionNotification(ctx: PluginInput, config: SessionNotif
       return
     }
 
-    if (event.type === "message.updated") {
+    if (
+      event.type === "message.updated" ||
+      event.type === "message.part.updated" ||
+      event.type === "message.part.delta"
+    ) {
       const info = props?.info as Record<string, unknown> | undefined
       const sessionID = getSessionID({ ...props, info })
       if (sessionID) scheduler.markSessionActivity(sessionID)
@@ -165,8 +169,8 @@ export function createSessionNotification(ctx: PluginInput, config: SessionNotif
     }
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined
+      const sessionID = resolveSessionEventID(props)
-      if (sessionInfo?.id) scheduler.deleteSession(sessionInfo.id)
+      if (sessionID) scheduler.deleteSession(sessionID)
     }
   }
 }

src/hooks/stop-continuation-guard/hook.ts

@@ -5,6 +5,7 @@ import {
   clearContinuationMarker,
   setContinuationMarkerSource,
 } from "../../features/run-continuation-state"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { log } from "../../shared/logger"
 
 const HOOK_NAME = "stop-continuation-guard"
@@ -86,11 +87,11 @@ export function createStopContinuationGuardHook(
     const props = event.properties as Record<string, unknown> | undefined
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined
+      const sessionID = resolveSessionEventID(props)
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        clear(sessionInfo.id)
+        clear(sessionID)
-        clearContinuationMarker(ctx.directory, sessionInfo.id)
+        clearContinuationMarker(ctx.directory, sessionID)
-        log(`[${HOOK_NAME}] Session deleted: cleaned up`, { sessionID: sessionInfo.id })
+        log(`[${HOOK_NAME}] Session deleted: cleaned up`, { sessionID })
       }
     }
   }

src/hooks/task-reminder/hook.ts

@@ -1,5 +1,7 @@
 import type { PluginInput } from "@opencode-ai/plugin"
 
+import { resolveSessionEventID } from "../../shared/event-session-id"
+
 const TASK_TOOLS = new Set([
   "task",
   "task_create",
@@ -50,8 +52,7 @@ export function createTaskReminderHook(_ctx: PluginInput) {
     "tool.execute.after": toolExecuteAfter,
     event: async ({ event }: { event: { type: string; properties?: unknown } }) => {
       if (event.type !== "session.deleted") return
-      const props = event.properties as { info?: { id?: string } } | undefined
+      const sessionId = resolveSessionEventID(event.properties)
-      const sessionId = props?.info?.id
       if (!sessionId) return
       sessionCounters.delete(sessionId)
     },

src/hooks/team-session-events/team-idle-wake-hint.ts

@@ -7,6 +7,7 @@ import {
   applyMemberSessionRouting,
   buildMemberPromptBody,
 } from "../../features/team-mode/member-session-routing"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { log } from "../../shared/logger"
 import { settleAfterSessionIdle } from "../shared/session-idle-settle"
 
@@ -35,8 +36,7 @@ export type HookImpl = (input: HookInput) => Promise<void>
 type TeamIdleWakeHintOptions = { idleSettleMs?: number }
 
 function getIdleSessionID(properties: unknown): string | undefined {
-  const record = properties as { sessionID?: string } | undefined
+  return resolveSessionEventID(properties)
-  return record?.sessionID
 }
 
 function buildWakeHint(unreadCount: number): string {

src/hooks/team-session-events/team-lead-orphan-handler.ts

@@ -3,14 +3,14 @@ import type { BackgroundManager } from "../../features/background-agent/manager"
 import { lookupTeamSession } from "../../features/team-mode/team-session-registry"
 import { loadRuntimeState, listActiveTeams, transitionRuntimeState } from "../../features/team-mode/team-state-store/store"
 import type { TmuxSessionManager } from "../../features/tmux-subagent/manager"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { log } from "../../shared/logger"
 
 type HookInput = { event: { type: string; properties?: unknown } }
 export type HookImpl = (input: HookInput) => Promise<void>
 
 function getDeletedSessionID(properties: unknown): string | undefined {
-  const record = properties as { info?: { id?: string } } | undefined
+  return resolveSessionEventID(properties)
-  return record?.info?.id
 }
 
 async function findLeadTeamRunId(

src/hooks/team-session-events/team-member-error-handler.ts

@@ -1,14 +1,14 @@
 import type { TeamModeConfig } from "../../config/schema/team-mode"
 import { findResolvedMemberSession } from "../../features/team-mode/member-session-resolution"
 import { loadRuntimeState, transitionRuntimeState } from "../../features/team-mode/team-state-store/store"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { log } from "../../shared/logger"
 
 type HookInput = { event: { type: string; properties?: unknown } }
 export type HookImpl = (input: HookInput) => Promise<void>
 
 function getErroredSessionID(properties: unknown): string | undefined {
-  const record = properties as { sessionID?: string } | undefined
+  return resolveSessionEventID(properties)
-  return record?.sessionID
 }
 
 export function createTeamMemberErrorHandler(config: TeamModeConfig): HookImpl {

src/hooks/team-session-events/team-member-status-handler.ts

@@ -2,6 +2,7 @@ import type { TeamModeConfig } from "../../config/schema/team-mode"
 import { findResolvedMemberSession } from "../../features/team-mode/member-session-resolution"
 import { loadRuntimeState, transitionRuntimeState } from "../../features/team-mode/team-state-store/store"
 import type { RuntimeStateMember } from "../../features/team-mode/types"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 import { log } from "../../shared/logger"
 
 type HookInput = { event: { type: string; properties?: unknown } }
@@ -13,13 +14,11 @@ const IDLE_TRANSITION_SOURCE_STATUSES: ReadonlySet<MemberStatus> = new Set(["run
 const COMPLETED_TRANSITION_SOURCE_STATUSES: ReadonlySet<MemberStatus> = new Set(["running", "idle", "pending"])
 
 function getSessionIDFromIdleEvent(properties: unknown): string | undefined {
-  const record = properties as { sessionID?: string } | undefined
+  return resolveSessionEventID(properties)
-  return record?.sessionID
 }
 
 function getSessionIDFromDeletedEvent(properties: unknown): string | undefined {
-  const record = properties as { info?: { id?: string } } | undefined
+  return resolveSessionEventID(properties)
-  return record?.info?.id
 }
 
 async function transitionMemberStatus(

src/hooks/think-mode/hook.ts

@@ -2,6 +2,7 @@ import { detectThinkKeyword, extractPromptText } from "./detector"
 import { isAlreadyHighVariant } from "./switcher"
 import type { ThinkModeState } from "./types"
 import { log } from "../../shared"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 
 const thinkModeState = new Map<string, ThinkModeState>()
 
@@ -66,9 +67,9 @@ export function createThinkModeHook() {
 
     event: async ({ event }: { event: { type: string; properties?: unknown } }) => {
       if (event.type === "session.deleted") {
-        const props = event.properties as { info?: { id?: string } } | undefined
+        const sessionID = resolveSessionEventID(event.properties)
-        if (props?.info?.id) {
+        if (sessionID) {
-          thinkModeState.delete(props.info.id)
+          thinkModeState.delete(sessionID)
         }
       }
     },

src/hooks/todo-continuation-enforcer/handler.ts

@@ -5,6 +5,7 @@ import {
   clearContinuationMarker,
 } from "../../features/run-continuation-state"
 import { log } from "../../shared/logger"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 
 import { DEFAULT_SKIP_AGENTS, HOOK_NAME } from "./constants"
 import { armCompactionGuard } from "./compaction-guard"
@@ -71,7 +72,7 @@ export function createTodoContinuationHandler(args: {
     const props = event.properties as Record<string, unknown> | undefined
 
     if (event.type === "session.error") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveSessionEventID(props)
       if (!sessionID) return
 
       const error = extractSessionErrorInfo(props?.error)
@@ -102,7 +103,7 @@ export function createTodoContinuationHandler(args: {
     }
 
     if (event.type === "session.idle") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveSessionEventID(props)
       if (!sessionID) return
 
       sessionStateStore.startPruneInterval()
@@ -118,7 +119,7 @@ export function createTodoContinuationHandler(args: {
     }
 
     if (event.type === "session.compacted") {
-      const sessionID = (props?.sessionID ?? (props?.info as { id?: string } | undefined)?.id) as string | undefined
+      const sessionID = resolveSessionEventID(props)
       if (sessionID) {
         const state = sessionStateStore.getState(sessionID)
         const compactionEpoch = armCompactionGuard(state, Date.now())
@@ -129,9 +130,9 @@ export function createTodoContinuationHandler(args: {
     }
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined
+      const sessionID = resolveSessionEventID(props)
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        clearContinuationMarker(ctx.directory, sessionInfo.id)
+        clearContinuationMarker(ctx.directory, sessionID)
       }
     }
 

src/hooks/todo-continuation-enforcer/non-idle-events.ts

@@ -1,4 +1,5 @@
 import { log } from "../../shared/logger"
+import { resolveMessageEventSessionID, resolveSessionEventID } from "../../shared/event-session-id"
 
 import { COUNTDOWN_GRACE_PERIOD_MS, HOOK_NAME } from "./constants"
 import type { SessionStateStore } from "./session-state"
@@ -12,7 +13,7 @@ export function handleNonIdleEvent(args: {
 
   if (eventType === "message.updated") {
     const info = properties?.info as Record<string, unknown> | undefined
-    const sessionID = info?.sessionID as string | undefined
+    const sessionID = resolveMessageEventSessionID(properties)
     const role = info?.role as string | undefined
     if (!sessionID) return
 
@@ -50,12 +51,7 @@ export function handleNonIdleEvent(args: {
   }
 
   if (eventType === "message.part.updated") {
-    const sessionID = typeof properties?.sessionID === "string"
+    const targetSessionID = resolveMessageEventSessionID(properties)
-      ? properties.sessionID
-      : undefined
-    const legacyInfo = properties?.info as Record<string, unknown> | undefined
-    const legacySessionID = legacyInfo?.sessionID as string | undefined
-    const targetSessionID = sessionID ?? legacySessionID
 
     if (targetSessionID) {
       const state = sessionStateStore.getExistingState(targetSessionID)
@@ -69,7 +65,7 @@ export function handleNonIdleEvent(args: {
   }
 
   if (eventType === "message.part.delta") {
-    const sessionID = properties?.sessionID as string | undefined
+    const sessionID = resolveMessageEventSessionID(properties)
     if (sessionID) {
       const state = sessionStateStore.getExistingState(sessionID)
       if (state) {
@@ -83,7 +79,7 @@ export function handleNonIdleEvent(args: {
   }
 
   if (eventType === "tool.execute.before" || eventType === "tool.execute.after") {
-    const sessionID = properties?.sessionID as string | undefined
+    const sessionID = resolveMessageEventSessionID(properties)
     if (sessionID) {
       const state = sessionStateStore.getExistingState(sessionID)
       if (state) {
@@ -97,10 +93,10 @@ export function handleNonIdleEvent(args: {
   }
 
   if (eventType === "session.deleted") {
-    const sessionInfo = properties?.info as { id?: string } | undefined
+    const sessionID = resolveSessionEventID(properties)
-    if (sessionInfo?.id) {
+    if (sessionID) {
-      sessionStateStore.cleanup(sessionInfo.id)
+      sessionStateStore.cleanup(sessionID)
-      log(`[${HOOK_NAME}] Session deleted: cleaned up`, { sessionID: sessionInfo.id })
+      log(`[${HOOK_NAME}] Session deleted: cleaned up`, { sessionID })
     }
     return
   }

src/hooks/todo-continuation-enforcer/todo-continuation-enforcer.test.ts

@@ -12,6 +12,7 @@ import {
 } from "./constants"
 
 type TimerCallback = (...args: any[]) => void
+type FakeTimerID = number & ReturnType<typeof setTimeout> & ReturnType<typeof setInterval>
 
 interface FakeTimers {
   advanceBy: (ms: number, advanceClock?: boolean) => Promise<void>
@@ -57,7 +58,7 @@ function createFakeTimers(): FakeTimers {
       callback,
       args,
     })
-    return id
+    return id as FakeTimerID
   }
 
   const clear = (id: number | undefined) => {
@@ -74,7 +75,7 @@ function createFakeTimers(): FakeTimers {
     if (normalized >= REAL_MAX_DELAY_MS) {
       return original.setTimeout(callback, delay, ...args)
     }
-    return schedule(callback, normalized, null, args) as unknown as ReturnType<typeof setTimeout>
+    return schedule(callback, normalized, null, args)
   }) as typeof setTimeout
 
   globalThis.setInterval = ((callback: TimerCallback, delay?: number, ...args: any[]) => {
@@ -85,7 +86,7 @@ function createFakeTimers(): FakeTimers {
     if (interval >= REAL_MAX_DELAY_MS) {
       return original.setInterval(callback, delay, ...args)
     }
-    return schedule(callback, interval, interval, args) as unknown as ReturnType<typeof setInterval>
+    return schedule(callback, interval, interval, args)
   }) as typeof setInterval
 
   globalThis.clearTimeout = ((id?: Parameters<typeof clearTimeout>[0]) => {
@@ -184,6 +185,8 @@ describe("todo-continuation-enforcer", () => {
     }
   }
 
+  type MockPluginInput = Parameters<typeof createTodoContinuationEnforcer>[0]
+
   let mockMessages: MockMessage[] = []
 
   function createMockPluginInput() {
@@ -225,7 +228,7 @@ describe("todo-continuation-enforcer", () => {
         },
       },
       directory: "/tmp/test",
-    } as any
+    } as MockPluginInput
   }
 
   function createMockBackgroundManager(runningTasks: boolean = false): BackgroundManager {
@@ -233,7 +236,7 @@ describe("todo-continuation-enforcer", () => {
       getTasksByParentSession: () => runningTasks
         ? [{ status: "running" }]
         : [],
-    } as any
+    } as BackgroundManager
   }
 
   beforeEach(() => {
@@ -302,6 +305,26 @@ describe("todo-continuation-enforcer", () => {
     expect(promptCalls[0].text).toContain("TODO CONTINUATION")
   }, { timeout: 15000 })
 
+  test("should inject continuation when idle event carries session id in info", async () => {
+    fakeTimers.restore()
+    // given - OpenCode session events can nest the session id under info
+    const sessionID = "main-info-idle"
+    setMainSession(sessionID)
+
+    const hook = createTodoContinuationEnforcer(createMockPluginInput(), {})
+
+    // when - session goes idle with the nested event shape
+    await hook.handler({
+      event: { type: "session.idle", properties: { info: { id: sessionID } } },
+    })
+
+    // then - continuation is still injected for that session
+    await wait(2500)
+    expect(promptCalls).toHaveLength(1)
+    expect(promptCalls[0].sessionID).toBe(sessionID)
+    expect(promptCalls[0].text).toContain("TODO CONTINUATION")
+  }, { timeout: 15000 })
+
   test("should not inject when all todos are complete", async () => {
     // given - session with all todos complete
     const sessionID = "main-456"
@@ -527,6 +550,42 @@ describe("todo-continuation-enforcer", () => {
     expect(promptCalls).toHaveLength(0)
   })
 
+  test("should cancel countdown on assistant activity when message.part.updated only has part session id", async () => {
+    // given - session starting countdown
+    const sessionID = "main-assistant-part-only"
+    setMainSession(sessionID)
+
+    const hook = createTodoContinuationEnforcer(createMockPluginInput(), {})
+
+    // when - session goes idle
+    await hook.handler({
+      event: { type: "session.idle", properties: { sessionID } },
+    })
+
+    // when - legacy part-only sync payload reports assistant output
+    await fakeTimers.advanceBy(500)
+    await hook.handler({
+      event: {
+        type: "message.part.updated",
+        properties: {
+          part: {
+            id: "part-1",
+            messageID: "msg-1",
+            sessionID,
+            type: "text",
+            text: "working",
+          },
+          time: Date.now(),
+        },
+      },
+    })
+
+    await fakeTimers.advanceBy(3000)
+
+    // then - no continuation injected (cancelled)
+    expect(promptCalls).toHaveLength(0)
+  })
+
   test("should cancel countdown on assistant activity with message.part.delta payload", async () => {
     // given - session starting countdown
     const sessionID = "main-assistant-delta"
@@ -1599,7 +1658,7 @@ describe("todo-continuation-enforcer", () => {
          tui: { showToast: async () => ({}) },
        },
        directory: "/tmp/test",
-     } as any
+     } as MockPluginInput
 
      const hook = createTodoContinuationEnforcer(mockInput, {
        backgroundManager: createMockBackgroundManager(false),
@@ -1660,7 +1719,7 @@ describe("todo-continuation-enforcer", () => {
          tui: { showToast: async () => ({}) },
        },
        directory: "/tmp/test",
-     } as any
+     } as MockPluginInput
 
      const hook = createTodoContinuationEnforcer(mockInput, {
        backgroundManager: createMockBackgroundManager(false),
@@ -1712,7 +1771,7 @@ describe("todo-continuation-enforcer", () => {
          tui: { showToast: async () => ({}) },
        },
        directory: "/tmp/test",
-     } as any
+     } as MockPluginInput
 
      const hook = createTodoContinuationEnforcer(mockInput, {})
 
@@ -1769,7 +1828,7 @@ describe("todo-continuation-enforcer", () => {
         tui: { showToast: async () => ({}) },
       },
       directory: "/tmp/test",
-    } as any
+    } as MockPluginInput
 
     const hook = createTodoContinuationEnforcer(mockInput, {
       backgroundManager: createMockBackgroundManager(false),
@@ -1823,7 +1882,7 @@ describe("todo-continuation-enforcer", () => {
          tui: { showToast: async () => ({}) },
        },
        directory: "/tmp/test",
-     } as any
+     } as MockPluginInput
 
      const hook = createTodoContinuationEnforcer(mockInput, {})
 
@@ -1878,7 +1937,7 @@ describe("todo-continuation-enforcer", () => {
          tui: { showToast: async () => ({}) },
        },
        directory: "/tmp/test",
-     } as any
+     } as MockPluginInput
 
      const hook = createTodoContinuationEnforcer(mockInput, {
        skipAgents: [],
@@ -2122,7 +2181,7 @@ describe("todo-continuation-enforcer", () => {
     const mockInput = createMockPluginInput()
     mockInput.client.session.promptAsync = async () => {
       const error = new Error("prompt is too long: 150000 tokens > 100000 maximum")
-      ;(error as any).name = "ContextLengthError"
+      error.name = "ContextLengthError"
       throw error
     }
 

src/hooks/unstable-agent-babysitter/unstable-agent-babysitter-hook.ts

@@ -2,6 +2,7 @@ import type { BackgroundManager } from "../../features/background-agent"
 import { getMainSessionID, getSessionAgent } from "../../features/claude-code-session-state"
 import { log } from "../../shared/logger"
 import { createInternalAgentTextPart, resolveInheritedPromptTools } from "../../shared"
+import { resolveMessageEventSessionID, resolveSessionEventID } from "../../shared/event-session-id"
 import { isAbortError } from "../../shared/is-abort-error"
 import {
   buildReminder,
@@ -128,7 +129,7 @@ export function createUnstableAgentBabysitterHook(ctx: BabysitterContext, option
     const props = event.properties as Record<string, unknown> | undefined
 
     if (event.type === "session.error") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveSessionEventID(props)
       if (!sessionID || !isAbortError(props?.error)) return
 
       cancelledSessions.add(sessionID)
@@ -138,7 +139,7 @@ export function createUnstableAgentBabysitterHook(ctx: BabysitterContext, option
     }
 
     if (event.type === "session.stop") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveSessionEventID(props)
       if (!sessionID) return
 
       cancelledSessions.add(sessionID)
@@ -149,7 +150,7 @@ export function createUnstableAgentBabysitterHook(ctx: BabysitterContext, option
 
     if (event.type === "message.updated") {
       const info = props?.info as Record<string, unknown> | undefined
-      const sessionID = info?.sessionID as string | undefined
+      const sessionID = resolveMessageEventSessionID(props)
       const role = info?.role as string | undefined
       if (!sessionID || (role !== "user" && role !== "assistant")) return
 
@@ -158,7 +159,7 @@ export function createUnstableAgentBabysitterHook(ctx: BabysitterContext, option
     }
 
     if (event.type === "tool.execute.before" || event.type === "tool.execute.after") {
-      const sessionID = props?.sessionID as string | undefined
+      const sessionID = resolveMessageEventSessionID(props)
       if (!sessionID) return
 
       cancelledSessions.delete(sessionID)
@@ -166,16 +167,16 @@ export function createUnstableAgentBabysitterHook(ctx: BabysitterContext, option
     }
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined
+      const sessionID = resolveSessionEventID(props)
-      if (!sessionInfo?.id) return
+      if (!sessionID) return
 
-      cancelledSessions.delete(sessionInfo.id)
+      cancelledSessions.delete(sessionID)
       return
     }
 
     if (event.type !== "session.idle") return
 
-    const sessionID = props?.sessionID as string | undefined
+    const sessionID = resolveSessionEventID(props)
     if (!sessionID) return
 
     const mainSessionID = getMainSessionID()

src/hooks/write-existing-file-guard/hook.ts

@@ -4,6 +4,7 @@ import { existsSync, realpathSync } from "fs"
 import { basename, dirname, isAbsolute, join, normalize, relative, resolve } from "path"
 
 import { handleWriteExistingFileGuardToolExecuteBefore } from "./tool-execute-before-handler"
+import { resolveSessionEventID } from "../../shared/event-session-id"
 
 export type GuardArgs = {
   filePath?: string
@@ -108,8 +109,7 @@ export function createWriteExistingFileGuardHook(ctx: PluginInput, options?: Wri
         return
       }
 
-      const props = event.properties as { info?: { id?: string } } | undefined
+      const sessionID = resolveSessionEventID(event.properties)
-      const sessionID = props?.info?.id
       if (!sessionID) {
         return
       }

src/plugin/event.test.ts

@@ -802,6 +802,56 @@ describe("createEventHandler - event forwarding", () => {
 		expect(forwardedEvents[0]?.event.type).toBe("message.part.delta")
 	})
 
+	it("forwards legacy message.part.updated activity with part-only session id to tmux session manager", async () => {
+		const forwardedEvents: EventInput[] = []
+		const eventHandler = createEventHandler({
+			ctx: asEventHandlerContext({}),
+			pluginConfig: asPluginConfig({
+				tmux: {
+					enabled: true,
+					layout: "main-vertical",
+					main_pane_size: 60,
+					main_pane_min_width: 120,
+					agent_pane_min_width: 40,
+					isolation: "inline",
+				},
+			}),
+			firstMessageVariantGate: {
+				markSessionCreated: () => {},
+				clear: () => {},
+			},
+			managers: createEventHandlerManagers({
+				skillMcpManager: {
+					disconnectSession: async () => {},
+				},
+				tmuxSessionManager: {
+					onEvent: (event: EventInput["event"]) => {
+						forwardedEvents.push({ event })
+					},
+					onSessionCreated: async () => {},
+					onSessionDeleted: async () => {},
+				},
+			}),
+			hooks: createEventHandlerHooks({}),
+		})
+		await eventHandler(asEventHandlerInput({
+			event: {
+				type: "message.part.updated",
+				properties: {
+					part: {
+						id: "part-1",
+						messageID: "msg-1",
+						sessionID: "ses_tmux_part_only",
+						type: "text",
+						text: "x",
+					},
+				},
+			},
+		}))
+		expect(forwardedEvents.length).toBe(1)
+		expect(forwardedEvents[0]?.event.type).toBe("message.part.updated")
+	})
+
 	it("does not forward tmux activity events when tmux integration is disabled", async () => {
 		const forwardedEvents: EventInput[] = []
 		const eventHandler = createEventHandler({

src/plugin/event.ts

@@ -47,6 +47,7 @@ import type { CreatedHooks } from "../create-hooks";
 import type { Managers } from "../create-managers";
 import { pruneRecentSyntheticIdles } from "./recent-synthetic-idles";
 import { normalizeSessionStatusToIdle } from "./session-status-normalizer";
+import { resolveMessageEventSessionID, resolveSessionEventID } from "../shared/event-session-id";
 
 type FirstMessageVariantGate = {
   markSessionCreated: (sessionInfo: { id?: string; title?: string; parentID?: string } | undefined) => void;
@@ -235,15 +236,15 @@ export function createEventHandler(args: {
 
   const getEventSessionID = (input: EventInput): string | undefined => {
     const properties = input.event.properties;
-    if (
+    if (input.event.type.startsWith("session.")) {
-      !properties ||
+      return resolveSessionEventID(properties);
-      typeof properties !== "object" ||
-      !("sessionID" in properties) ||
-      typeof properties.sessionID !== "string"
-    ) {
-      return undefined;
     }
-    return properties.sessionID;
+    if (input.event.type.startsWith("message.") || input.event.type.startsWith("tool.")) {
+      return resolveMessageEventSessionID(properties);
+    }
+    const record: Record<string, unknown> | undefined = isRecord(properties) ? properties : undefined;
+    const sessionID = record?.sessionID;
+    return typeof sessionID === "string" && sessionID.length > 0 ? sessionID : undefined;
   };
 
   const runEventHookSafely = async (
@@ -467,10 +468,11 @@ export function createEventHandler(args: {
 
     if (event.type === "session.created") {
       const sessionInfo = props?.info as { id?: string; title?: string; parentID?: string } | undefined;
-      const isSubagentSession = !!sessionInfo?.parentID || !!sessionInfo?.id && subagentSessions.has(sessionInfo.id);
+      const sessionID = resolveSessionEventID(props);
+      const isSubagentSession = !!sessionInfo?.parentID || !!sessionID && subagentSessions.has(sessionID);
 
       if (!isSubagentSession) {
-        setMainSession(sessionInfo?.id);
+        setMainSession(sessionID);
       }
 
       firstMessageVariantGate.markSessionCreated(sessionInfo);
@@ -489,62 +491,62 @@ export function createEventHandler(args: {
 
       // Skip subagent sessions — they are dispatched by specialized callbacks
       // in create-managers.ts (async) and tool-registry.ts (sync)
-      if (pluginConfig.openclaw && sessionInfo?.id && !isSubagentSession) {
+      if (pluginConfig.openclaw && sessionID && !isSubagentSession) {
         await dispatchOpenClawEvent({
           config: pluginConfig.openclaw,
           rawEvent: event.type,
           context: {
-            sessionId: sessionInfo.id,
+            sessionId: sessionID,
             projectPath: pluginContext.directory,
-            tmuxPaneId: managers.tmuxSessionManager.getTrackedPaneId?.(sessionInfo.id) ?? process.env.TMUX_PANE,
+            tmuxPaneId: managers.tmuxSessionManager.getTrackedPaneId?.(sessionID) ?? process.env.TMUX_PANE,
           },
         });
       }
     }
 
     if (event.type === "session.deleted") {
-      const sessionInfo = props?.info as { id?: string } | undefined;
+      const sessionID = resolveSessionEventID(props);
-      if (sessionInfo?.id === getMainSessionID()) {
+      if (sessionID === getMainSessionID()) {
         setMainSession(undefined);
       }
 
-      if (sessionInfo?.id) {
+      if (sessionID) {
-        const wasSyncSubagentSession = syncSubagentSessions.has(sessionInfo.id);
+        const wasSyncSubagentSession = syncSubagentSessions.has(sessionID);
-        clearSessionAgent(sessionInfo.id);
+        clearSessionAgent(sessionID);
-        lastHandledModelErrorMessageID.delete(sessionInfo.id);
+        lastHandledModelErrorMessageID.delete(sessionID);
-        lastHandledRetryStatusKey.delete(sessionInfo.id);
+        lastHandledRetryStatusKey.delete(sessionID);
-        lastKnownModelBySession.delete(sessionInfo.id);
+        lastKnownModelBySession.delete(sessionID);
         if (modelFallback) {
-          clearPendingModelFallback(modelFallback, sessionInfo.id);
+          clearPendingModelFallback(modelFallback, sessionID);
-          clearSessionFallbackChain(modelFallback, sessionInfo.id);
+          clearSessionFallbackChain(modelFallback, sessionID);
         }
-        resetMessageCursor(sessionInfo.id);
+        resetMessageCursor(sessionID);
-        clearBackgroundOutputConsumptionsForParentSession(sessionInfo.id);
+        clearBackgroundOutputConsumptionsForParentSession(sessionID);
-        clearBackgroundOutputConsumptionsForTaskSession(sessionInfo.id);
+        clearBackgroundOutputConsumptionsForTaskSession(sessionID);
-        firstMessageVariantGate.clear(sessionInfo.id);
+        firstMessageVariantGate.clear(sessionID);
-        clearSessionModel(sessionInfo.id);
+        clearSessionModel(sessionID);
-        clearSessionPromptParams(sessionInfo.id);
+        clearSessionPromptParams(sessionID);
-        syncSubagentSessions.delete(sessionInfo.id);
+        syncSubagentSessions.delete(sessionID);
         if (pluginConfig.openclaw) {
           await dispatchOpenClawEvent({
             config: pluginConfig.openclaw,
             rawEvent: event.type,
             context: {
-              sessionId: sessionInfo.id,
+              sessionId: sessionID,
               projectPath: pluginContext.directory,
-              tmuxPaneId: managers.tmuxSessionManager.getTrackedPaneId?.(sessionInfo.id) ?? process.env.TMUX_PANE,
+              tmuxPaneId: managers.tmuxSessionManager.getTrackedPaneId?.(sessionID) ?? process.env.TMUX_PANE,
             },
           });
         }
         if (wasSyncSubagentSession) {
-          subagentSessions.delete(sessionInfo.id);
+          subagentSessions.delete(sessionID);
         }
-        deleteSessionTools(sessionInfo.id);
+        deleteSessionTools(sessionID);
-        await managers.skillMcpManager.disconnectSession(sessionInfo.id);
+        await managers.skillMcpManager.disconnectSession(sessionID);
         await lspManager.cleanupTempDirectoryClients();
         if (tmuxIntegrationEnabled) {
           await managers.tmuxSessionManager.onSessionDeleted({
-            sessionID: sessionInfo.id,
+            sessionID,
           });
         }
       }
@@ -555,12 +557,12 @@ export function createEventHandler(args: {
 
     if (event.type === "message.removed") {
       const messageID = props?.messageID as string | undefined;
-      const sessionID = props?.sessionID as string | undefined;
+      const sessionID = resolveMessageEventSessionID(props);
       restoreBackgroundOutputConsumption(sessionID, messageID);
     }
 
     if (event.type === "session.idle" && pluginConfig.openclaw) {
-      const sessionID = props?.sessionID as string | undefined;
+      const sessionID = resolveSessionEventID(props);
       if (sessionID) {
         await dispatchOpenClawEvent({
           config: pluginConfig.openclaw,
@@ -582,7 +584,7 @@ export function createEventHandler(args: {
 
     if (event.type === "message.updated") {
       const info = props?.info as Record<string, unknown> | undefined;
-      const sessionID = info?.sessionID as string | undefined;
+      const sessionID = resolveMessageEventSessionID(props);
       const agent = info?.agent as string | undefined;
       const role = info?.role as string | undefined;
       if (sessionID && info?.finish === true) {
@@ -665,7 +667,7 @@ export function createEventHandler(args: {
     }
 
     if (event.type === "session.status") {
-      const sessionID = props?.sessionID as string | undefined;
+      const sessionID = resolveSessionEventID(props);
       const status = props?.status as { type?: string; attempt?: number; message?: string; next?: number } | undefined;
 
       // Retry dedupe lifecycle: set key when a retry status is handled, clear it after recovery
@@ -733,7 +735,7 @@ export function createEventHandler(args: {
 
     if (event.type === "session.error") {
       try {
-        const sessionID = props?.sessionID as string | undefined;
+        const sessionID = resolveSessionEventID(props);
         const error = props?.error;
 
         const errorName = extractErrorName(error);
@@ -818,7 +820,7 @@ export function createEventHandler(args: {
           }
         }
       } catch (err) {
-        const sessionID = props?.sessionID as string | undefined;
+        const sessionID = resolveSessionEventID(props);
         log("[event] model-fallback error in session.error:", { sessionID, error: err });
       }
 

src/plugin/session-status-normalizer.ts

@@ -1,3 +1,5 @@
+import { resolveSessionEventID } from "../shared/event-session-id"
+
 type EventInput = { event: { type: string; properties?: Record<string, unknown> } }
 type SessionStatus = { type: string }
 
@@ -10,7 +12,7 @@ export function normalizeSessionStatusToIdle(input: EventInput): EventInput | nu
 	const status = props.status as SessionStatus | undefined
 	if (!status || status.type !== "idle") return null
 
-	const sessionID = props.sessionID as string | undefined
+	const sessionID = resolveSessionEventID(props)
 	if (!sessionID) return null
 
 	return {

src/shared/binary-downloader.ts

@@ -1,6 +1,7 @@
 import { chmodSync, existsSync, mkdirSync, unlinkSync } from "node:fs";
 import * as path from "node:path";
 import { spawn } from "./bun-spawn-shim";
+import { bunWrite } from "./bun-file-shim";
 import { validateArchiveEntries, type ArchiveEntry } from "./archive-entry-validator";
 import { extractZip } from "./zip-extractor";
 
@@ -26,7 +27,7 @@ export async function downloadArchive(downloadUrl: string, archivePath: string):
   }
 
   const arrayBuffer = await response.arrayBuffer();
-  await Bun.write(archivePath, arrayBuffer);
+  await bunWrite(archivePath, arrayBuffer);
 }
 
 export async function extractTarGz(

src/shared/bun-file-shim.test.ts

@@ -0,0 +1,300 @@
+/// <reference path="../../bun-test.d.ts" />
+
+import { Buffer as NodeBuffer } from "node:buffer"
+import { readFileSync } from "node:fs"
+import { access, mkdtemp, readFile, rm, unlink, writeFile } from "node:fs/promises"
+import { tmpdir } from "node:os"
+import { dirname, join } from "node:path"
+import { fileURLToPath } from "node:url"
+import { runInNewContext } from "node:vm"
+import { afterAll, beforeAll, describe, expect, it } from "bun:test"
+
+import { bunFile, bunWrite } from "./bun-file-shim"
+
+type NodeFallbackBunFileLike = {
+  text(): Promise<string>
+  arrayBuffer(): Promise<ArrayBuffer>
+  exists(): Promise<boolean>
+  delete(): Promise<void>
+}
+
+type NodeFallbackBunFile = (path: string) => NodeFallbackBunFileLike
+type NodeFallbackBunWrite = (path: string, data: string | ArrayBuffer | Uint8Array) => Promise<number>
+
+type NodeFallbackExports = {
+  bunFile: NodeFallbackBunFile
+  bunWrite: NodeFallbackBunWrite
+}
+
+type BunFileTestRuntime = {
+  Transpiler: new (options: { loader: "ts" }) => { transformSync(source: string): string }
+}
+
+type BunFileSandbox = {
+  access: typeof access
+  Buffer: typeof NodeBuffer
+  console: Console
+  Promise: PromiseConstructor
+  readFile: typeof readFile
+  TextEncoder: typeof TextEncoder
+  Uint8Array: Uint8ArrayConstructor
+  unlink: typeof unlink
+  writeFile: typeof writeFile
+  __exports?: NodeFallbackExports
+}
+
+const runtime = globalThis as typeof globalThis & { Bun: BunFileTestRuntime }
+const NODE_FALLBACK = loadNodeFallbackBunFileShim()
+
+let temporaryDirectory = ""
+let nodeFallbackTemporaryDirectory = ""
+
+function temporaryPath(fileName: string): string {
+  return join(temporaryDirectory, fileName)
+}
+
+function nodeFallbackPath(fileName: string): string {
+  return join(nodeFallbackTemporaryDirectory, fileName)
+}
+
+function loadNodeFallbackBunFileShim(): NodeFallbackExports {
+  const sourcePath = join(dirname(fileURLToPath(import.meta.url)), "bun-file-shim.ts")
+  const source = readFileSync(sourcePath, "utf8")
+  const importStatement = 'import { access, readFile, unlink, writeFile } from "node:fs/promises"\n\n'
+  const interfaceSignature = "export interface BunFileLike {"
+  const bunFileSignature = "export function bunFile(path: string): BunFileLike {"
+  const bunWriteSignature =
+    "export async function bunWrite(path: string, data: string | ArrayBuffer | Uint8Array): Promise<number> {"
+
+  if (!source.startsWith(importStatement)) {
+    throw new Error("bun-file-shim import statement changed")
+  }
+
+  for (const signature of [interfaceSignature, bunFileSignature, bunWriteSignature]) {
+    if (!source.includes(signature)) {
+      throw new Error(`bun-file-shim signature changed: ${signature}`)
+    }
+  }
+
+  const transformedSource = source
+    .slice(importStatement.length)
+    .replace(interfaceSignature, "interface BunFileLike {")
+    .replace(bunFileSignature, "function bunFile(path: string): BunFileLike {")
+    .replace(
+      bunWriteSignature,
+      "async function bunWrite(path: string, data: string | ArrayBuffer | Uint8Array): Promise<number> {",
+    )
+  const scriptSource = `${transformedSource}\nglobalThis.__exports = { bunFile, bunWrite }\n`
+  const transpiler = new runtime.Bun.Transpiler({ loader: "ts" })
+  const script = transpiler.transformSync(scriptSource)
+  const sandbox: BunFileSandbox = {
+    access,
+    Buffer: NodeBuffer,
+    console,
+    Promise,
+    readFile,
+    TextEncoder,
+    Uint8Array,
+    unlink,
+    writeFile,
+  }
+
+  runInNewContext(script, sandbox, { filename: sourcePath })
+
+  if (!sandbox.__exports) {
+    throw new Error("Node fallback bun-file-shim loader failed")
+  }
+
+  return sandbox.__exports
+}
+
+function arrayBufferFromBytes(bytes: number[]): ArrayBuffer {
+  const arrayBuffer = new ArrayBuffer(bytes.length)
+  const view = new Uint8Array(arrayBuffer)
+
+  view.set(bytes)
+
+  return arrayBuffer
+}
+
+describe("bun-file-shim", () => {
+  beforeAll(async () => {
+    temporaryDirectory = await mkdtemp(join(tmpdir(), "bun-file-shim-"))
+  })
+
+  afterAll(async () => {
+    if (temporaryDirectory.length === 0) return
+
+    await rm(temporaryDirectory, { recursive: true, force: true })
+  })
+
+  describe("#given bunFile", () => {
+    it("#when text is called then it reads file contents", async () => {
+      const filePath = temporaryPath("text.txt")
+      const content = "hello from file"
+
+      await writeFile(filePath, content)
+
+      expect(await bunFile(filePath).text()).toBe(content)
+    })
+
+    it("#when arrayBuffer is called then it returns exact file bytes", async () => {
+      const filePath = temporaryPath("bytes.bin")
+      const bytes = new Uint8Array([0, 1, 2, 255])
+
+      await writeFile(filePath, bytes)
+
+      const arrayBuffer = await bunFile(filePath).arrayBuffer()
+
+      expect(arrayBuffer.byteLength).toBe(bytes.byteLength)
+      expect(Array.from(new Uint8Array(arrayBuffer))).toEqual(Array.from(bytes))
+    })
+
+    it("#when exists is called then it reflects file presence", async () => {
+      const existingPath = temporaryPath("existing.txt")
+      const missingPath = temporaryPath("missing.txt")
+
+      await writeFile(existingPath, "present")
+
+      expect(await bunFile(existingPath).exists()).toBe(true)
+      expect(await bunFile(missingPath).exists()).toBe(false)
+    })
+
+    it("#when delete is called then it removes the file", async () => {
+      const filePath = temporaryPath("delete-me.txt")
+
+      await writeFile(filePath, "remove")
+      await bunFile(filePath).delete()
+
+      expect(await bunFile(filePath).exists()).toBe(false)
+    })
+  })
+
+  describe("#given bunWrite", () => {
+    it("#when writing string data then it writes contents and returns byte count", async () => {
+      const filePath = temporaryPath("write-string.txt")
+      const content = "write me"
+      const bytesWritten = await bunWrite(filePath, content)
+
+      expect(bytesWritten).toBe(new TextEncoder().encode(content).byteLength)
+      expect(await readFile(filePath, "utf8")).toBe(content)
+    })
+
+    it("#when writing array buffer data then it writes exact bytes", async () => {
+      const filePath = temporaryPath("write-array-buffer.bin")
+      const arrayBuffer = arrayBufferFromBytes([65, 66, 67, 68])
+      const bytesWritten = await bunWrite(filePath, arrayBuffer)
+      const written = await readFile(filePath)
+
+      expect(bytesWritten).toBe(arrayBuffer.byteLength)
+      expect(Array.from(written)).toEqual([65, 66, 67, 68])
+    })
+
+    it("#when writing then reading text then it round trips content", async () => {
+      const filePath = temporaryPath("round-trip.txt")
+      const content = "round trip content"
+
+      await bunWrite(filePath, content)
+
+      expect(await bunFile(filePath).text()).toBe(content)
+    })
+
+    it("#when writing unicode text then it round trips content", async () => {
+      const filePath = temporaryPath("unicode-round-trip.txt")
+      const content = "Hello 世界 🌍"
+
+      await bunWrite(filePath, content)
+
+      expect(await bunFile(filePath).text()).toBe(content)
+    })
+  })
+
+  describe("#given Node fallback without Bun global", () => {
+    beforeAll(async () => {
+      nodeFallbackTemporaryDirectory = await mkdtemp(join(tmpdir(), "bun-file-shim-node-"))
+    })
+
+    afterAll(async () => {
+      if (nodeFallbackTemporaryDirectory.length === 0) return
+
+      await rm(nodeFallbackTemporaryDirectory, { recursive: true, force: true })
+    })
+
+    it("#when text is called then it reads file contents", async () => {
+      const filePath = nodeFallbackPath("text.txt")
+      const content = "hello from Node fallback"
+
+      await writeFile(filePath, content)
+
+      expect(await NODE_FALLBACK.bunFile(filePath).text()).toBe(content)
+    })
+
+    it("#when arrayBuffer is called then it returns exact file bytes", async () => {
+      const filePath = nodeFallbackPath("bytes.bin")
+      const bytes = new Uint8Array([0, 1, 2, 255, 128])
+
+      await writeFile(filePath, bytes)
+
+      const arrayBuffer = await NODE_FALLBACK.bunFile(filePath).arrayBuffer()
+
+      expect(arrayBuffer.byteLength).toBe(bytes.byteLength)
+      expect(Array.from(new Uint8Array(arrayBuffer))).toEqual(Array.from(bytes))
+    })
+
+    it("#when exists is called then it reflects file presence", async () => {
+      const existingPath = nodeFallbackPath("existing.txt")
+      const missingPath = nodeFallbackPath("missing.txt")
+
+      await writeFile(existingPath, "present")
+
+      expect(await NODE_FALLBACK.bunFile(existingPath).exists()).toBe(true)
+      expect(await NODE_FALLBACK.bunFile(missingPath).exists()).toBe(false)
+    })
+
+    it("#when delete is called then it removes the file", async () => {
+      const filePath = nodeFallbackPath("delete-me.txt")
+
+      await writeFile(filePath, "remove")
+      await NODE_FALLBACK.bunFile(filePath).delete()
+
+      expect(await NODE_FALLBACK.bunFile(filePath).exists()).toBe(false)
+    })
+
+    it("#when writing string data then it writes contents and returns byte count", async () => {
+      const filePath = nodeFallbackPath("write-string.txt")
+      const content = "write me from Node fallback"
+      const bytesWritten = await NODE_FALLBACK.bunWrite(filePath, content)
+
+      expect(bytesWritten).toBe(new TextEncoder().encode(content).byteLength)
+      expect(await readFile(filePath, "utf8")).toBe(content)
+    })
+
+    it("#when writing array buffer data then it writes exact bytes", async () => {
+      const filePath = nodeFallbackPath("write-array-buffer.bin")
+      const arrayBuffer = arrayBufferFromBytes([65, 66, 67, 68, 69])
+      const bytesWritten = await NODE_FALLBACK.bunWrite(filePath, arrayBuffer)
+      const written = await readFile(filePath)
+
+      expect(bytesWritten).toBe(arrayBuffer.byteLength)
+      expect(Array.from(written)).toEqual([65, 66, 67, 68, 69])
+    })
+
+    it("#when writing then reading text then it round trips content", async () => {
+      const filePath = nodeFallbackPath("round-trip.txt")
+      const content = "round trip through Node fallback"
+
+      await NODE_FALLBACK.bunWrite(filePath, content)
+
+      expect(await NODE_FALLBACK.bunFile(filePath).text()).toBe(content)
+    })
+
+    it("#when writing unicode text then it round trips content", async () => {
+      const filePath = nodeFallbackPath("unicode-round-trip.txt")
+      const content = "Hello 世界 🌍 from Node fallback"
+
+      await NODE_FALLBACK.bunWrite(filePath, content)
+
+      expect(await NODE_FALLBACK.bunFile(filePath).text()).toBe(content)
+    })
+  })
+})

src/shared/bun-file-shim.ts

@@ -0,0 +1,65 @@
+import { access, readFile, unlink, writeFile } from "node:fs/promises"
+
+export interface BunFileLike {
+  text(): Promise<string>
+  arrayBuffer(): Promise<ArrayBuffer>
+  exists(): Promise<boolean>
+  delete(): Promise<void>
+}
+
+type BunFileRuntime = {
+  file(path: string): BunFileLike
+  write(path: string, data: string | ArrayBuffer | Uint8Array): Promise<number>
+}
+
+const runtime = globalThis as typeof globalThis & { Bun?: BunFileRuntime }
+const IS_BUN = typeof runtime.Bun !== "undefined"
+
+function byteLength(data: string | ArrayBuffer | Uint8Array): number {
+  if (typeof data === "string") return Buffer.byteLength(data, "utf8")
+
+  return data.byteLength
+}
+
+function toWritableData(data: string | ArrayBuffer | Uint8Array): string | Uint8Array {
+  if (typeof data === "string") return data
+  if (data instanceof Uint8Array) return data
+
+  return new Uint8Array(data)
+}
+
+function createNodeFile(path: string): BunFileLike {
+  return {
+    text() {
+      return readFile(path, "utf8")
+    },
+    async arrayBuffer() {
+      const buffer = await readFile(path)
+
+      return buffer.buffer.slice(buffer.byteOffset, buffer.byteOffset + buffer.byteLength)
+    },
+    exists() {
+      return access(path).then(
+        () => true,
+        () => false,
+      )
+    },
+    delete() {
+      return unlink(path)
+    },
+  }
+}
+
+export function bunFile(path: string): BunFileLike {
+  if (IS_BUN) return runtime.Bun!.file(path)
+
+  return createNodeFile(path)
+}
+
+export async function bunWrite(path: string, data: string | ArrayBuffer | Uint8Array): Promise<number> {
+  if (IS_BUN) return runtime.Bun!.write(path, data)
+
+  await writeFile(path, toWritableData(data))
+
+  return byteLength(data)
+}

src/shared/bun-hash-shim.test.ts

@@ -0,0 +1,175 @@
+import { readFileSync } from "node:fs"
+import { dirname, join } from "node:path"
+import { fileURLToPath } from "node:url"
+import { runInNewContext } from "node:vm"
+import { describe, expect, test } from "bun:test"
+import { bunHashXxh32 as runtimeBunHashXxh32 } from "./bun-hash-shim"
+
+type HashFunction = (input: string, seed: number) => number
+type HashPair = { input: string; seed: number }
+type BunHashTestRuntime = {
+  hash: { xxHash32(data: string | Uint8Array, seed: number): number }
+  Transpiler: new (options: { loader: "ts" }) => { transformSync(source: string): string }
+}
+type HashSandbox = {
+  Math: Math
+  TextEncoder: typeof TextEncoder
+  Uint8Array: Uint8ArrayConstructor
+  __bunHashShim?: { bunHashXxh32: HashFunction }
+}
+
+const runtime = globalThis as typeof globalThis & { Bun: BunHashTestRuntime }
+const FUZZ_PAIR_COUNT = 1_200
+const FIXED_LENGTHS = [0, 1, 2, 3, 4, 15, 16, 17, 31, 32, 33, 64, 100, 255, 500]
+const FIXED_SEEDS = [0, 1, 42, 12345, 0xdeadbeef, 0xffffffff]
+const CONTENT_FRAGMENTS = ["你好世界", "\u{1f389}", "\u{1f525}", "\n", "\r\n", "\t", " "]
+const SPECIAL_INPUTS = [
+  "",
+  " ",
+  "\t\n\r\n",
+  "hello world",
+  "你好世界",
+  "\u{1f389}\u{1f525}",
+  "mixed 你好 \u{1f389} ascii",
+  "line one\nline two\r\n\tindented",
+]
+const PURE_JS_HASH = loadPureJsBunHashXxh32()
+const FUZZ_PAIRS = createFuzzPairs()
+
+function loadPureJsBunHashXxh32(): HashFunction {
+  const sourcePath = join(dirname(fileURLToPath(import.meta.url)), "bun-hash-shim.ts")
+  const source = readFileSync(sourcePath, "utf8")
+  const exportSignature = "export function bunHashXxh32(input: string, seed: number): number {"
+
+  if (!source.includes(exportSignature)) {
+    throw new Error("bunHashXxh32 export signature changed")
+  }
+
+  const scriptSource = `${source.replace(
+    exportSignature,
+    "function bunHashXxh32(input: string, seed: number): number {",
+  )}\nglobalThis.__bunHashShim = { bunHashXxh32 }\n`
+  const transpiler = new runtime.Bun.Transpiler({ loader: "ts" })
+  const script = transpiler.transformSync(scriptSource)
+  const sandbox: HashSandbox = { Math, TextEncoder, Uint8Array }
+
+  runInNewContext(script, sandbox, { filename: sourcePath })
+
+  const pureJsHash = sandbox.__bunHashShim?.bunHashXxh32
+  if (!pureJsHash) {
+    throw new Error("pure-JS bunHashXxh32 loader failed")
+  }
+
+  return pureJsHash
+}
+
+function createUint32Generator(seed: number): () => number {
+  let state = seed >>> 0
+
+  return () => {
+    state = (Math.imul(state, 1664525) + 1013904223) >>> 0
+
+    return state
+  }
+}
+
+function createSeed(pairIndex: number, nextUint32: () => number): number {
+  if (pairIndex % (FIXED_SEEDS.length + 1) === FIXED_SEEDS.length) return nextUint32()
+
+  return FIXED_SEEDS[pairIndex % FIXED_SEEDS.length] ?? 0
+}
+
+function createRandomString(length: number, nextUint32: () => number): string {
+  let value = ""
+
+  while (value.length < length) {
+    if (nextUint32() % 10 < 6) {
+      value += String.fromCharCode(32 + (nextUint32() % 95))
+      continue
+    }
+
+    const fragment = CONTENT_FRAGMENTS[nextUint32() % CONTENT_FRAGMENTS.length] ?? " "
+    if (value.length + fragment.length <= length) {
+      value += fragment
+      continue
+    }
+
+    value += String.fromCharCode(32 + (nextUint32() % 95))
+  }
+
+  return value
+}
+
+function createFuzzPairs(): HashPair[] {
+  const nextUint32 = createUint32Generator(0x5eed1234)
+  const pairs: HashPair[] = []
+
+  for (const input of SPECIAL_INPUTS) {
+    pairs.push({ input, seed: createSeed(pairs.length, nextUint32) })
+  }
+
+  for (const length of FIXED_LENGTHS) {
+    pairs.push({ input: createRandomString(length, nextUint32), seed: createSeed(pairs.length, nextUint32) })
+  }
+
+  while (pairs.length < FUZZ_PAIR_COUNT) {
+    const randomLength = nextUint32() % 501
+    const length = pairs.length % 13 === 0 ? (FIXED_LENGTHS[pairs.length % FIXED_LENGTHS.length] ?? randomLength) : randomLength
+    pairs.push({ input: createRandomString(length, nextUint32), seed: createSeed(pairs.length, nextUint32) })
+  }
+
+  return pairs
+}
+
+function nativeXxh32(input: string, seed: number): number {
+  return runtime.Bun.hash.xxHash32(input, seed)
+}
+
+function createMismatchMessage(label: string, input: string, seed: number, expected: number, actual: number): string {
+  return `${label} mismatch for input=${JSON.stringify(input)} seed=${seed} expected=${expected} actual=${actual}`
+}
+
+function expectPureJsHashToMatchBun(label: string, input: string, seed: number): void {
+  const expected = nativeXxh32(input, seed)
+  const actual = PURE_JS_HASH(input, seed)
+
+  if (actual !== expected) {
+    throw new Error(createMismatchMessage(label, input, seed, expected, actual))
+  }
+}
+
+describe("#given known XXH32 test vectors", () => {
+  test("#when pure-JS hash is called #then returns canonical values", () => {
+    expect(PURE_JS_HASH("", 0)).toBe(0x02cc5d05)
+    expect(PURE_JS_HASH("a", 0)).toBe(0x550d7456)
+    expect(PURE_JS_HASH("abc", 0)).toBe(0x32d153ff)
+  })
+
+  test("#when a non-zero seed is used #then matches Bun hash", () => {
+    expectPureJsHashToMatchBun("seeded vector", "test", 42)
+    expect(runtimeBunHashXxh32("test", 42)).toBe(nativeXxh32("test", 42))
+  })
+})
+
+describe("#given random inputs #when hashed with pure-JS and Bun.hash", () => {
+  test("#then all fuzz pairs are bit-exact", () => {
+    expect(FUZZ_PAIRS).toHaveLength(FUZZ_PAIR_COUNT)
+
+    for (const [pairIndex, pair] of FUZZ_PAIRS.entries()) {
+      expectPureJsHashToMatchBun(`fuzz pair ${pairIndex}`, pair.input, pair.seed)
+    }
+  })
+})
+
+describe("#given production-like inputs", () => {
+  test("#when hashed with line-number seeds #then pure-JS matches Bun hash", () => {
+    const inputs = ["  const x = 42;", "import { foo } from 'bar'", "// comment", ""]
+    const seeds = [0, 1, 50, 100, 999]
+
+    for (const input of inputs) {
+      for (const seed of seeds) {
+        expectPureJsHashToMatchBun("production-like input", input, seed)
+      }
+    }
+  })
+})

src/shared/bun-hash-shim.ts

@@ -0,0 +1,89 @@
+type BunHashRuntime = { hash: { xxHash32(data: string | Uint8Array, seed: number): number } }
+
+const runtime = globalThis as typeof globalThis & { Bun?: BunHashRuntime }
+const IS_BUN = typeof runtime.Bun !== "undefined"
+const encoder = new TextEncoder()
+
+const PRIME32_1 = 0x9e3779b1
+const PRIME32_2 = 0x85ebca77
+const PRIME32_3 = 0xc2b2ae3d
+const PRIME32_4 = 0x27d4eb2f
+const PRIME32_5 = 0x165667b1
+
+function rotateLeft32(value: number, bits: number): number {
+  return ((value << bits) | (value >>> (32 - bits))) >>> 0
+}
+
+function readUint32LittleEndian(input: Uint8Array, offset: number): number {
+  return (
+    ((input[offset] ?? 0) |
+      ((input[offset + 1] ?? 0) << 8) |
+      ((input[offset + 2] ?? 0) << 16) |
+      ((input[offset + 3] ?? 0) << 24)) >>>
+    0
+  )
+}
+
+function round32(accumulator: number, value: number): number {
+  const added = (accumulator + Math.imul(value, PRIME32_2)) >>> 0
+
+  return Math.imul(rotateLeft32(added, 13), PRIME32_1) >>> 0
+}
+
+function xxHash32Js(input: Uint8Array, seed: number): number {
+  let offset = 0
+  const length = input.length
+  let hash: number
+
+  if (length >= 16) {
+    const limit = length - 16
+    let value1 = (seed + PRIME32_1 + PRIME32_2) >>> 0
+    let value2 = (seed + PRIME32_2) >>> 0
+    let value3 = seed >>> 0
+    let value4 = (seed - PRIME32_1) >>> 0
+
+    while (offset <= limit) {
+      value1 = round32(value1, readUint32LittleEndian(input, offset))
+      offset += 4
+      value2 = round32(value2, readUint32LittleEndian(input, offset))
+      offset += 4
+      value3 = round32(value3, readUint32LittleEndian(input, offset))
+      offset += 4
+      value4 = round32(value4, readUint32LittleEndian(input, offset))
+      offset += 4
+    }
+
+    hash = (rotateLeft32(value1, 1) + rotateLeft32(value2, 7)) >>> 0
+    hash = (hash + rotateLeft32(value3, 12)) >>> 0
+    hash = (hash + rotateLeft32(value4, 18)) >>> 0
+  } else {
+    hash = (seed + PRIME32_5) >>> 0
+  }
+
+  hash = (hash + length) >>> 0
+
+  while (offset + 4 <= length) {
+    hash = (hash + Math.imul(readUint32LittleEndian(input, offset), PRIME32_3)) >>> 0
+    hash = Math.imul(rotateLeft32(hash, 17), PRIME32_4) >>> 0
+    offset += 4
+  }
+
+  while (offset < length) {
+    hash = (hash + Math.imul(input[offset] ?? 0, PRIME32_5)) >>> 0
+    hash = Math.imul(rotateLeft32(hash, 11), PRIME32_1) >>> 0
+    offset += 1
+  }
+
+  hash = (hash ^ (hash >>> 15)) >>> 0
+  hash = Math.imul(hash, PRIME32_2) >>> 0
+  hash = (hash ^ (hash >>> 13)) >>> 0
+  hash = Math.imul(hash, PRIME32_3) >>> 0
+
+  return (hash ^ (hash >>> 16)) >>> 0
+}
+
+export function bunHashXxh32(input: string, seed: number): number {
+  if (IS_BUN) return runtime.Bun!.hash.xxHash32(input, seed)
+
+  return xxHash32Js(encoder.encode(input), seed >>> 0)
+}

src/shared/bun-which-shim.test.ts

@@ -0,0 +1,149 @@
+import { accessSync, constants, readFileSync } from "node:fs"
+import { delimiter, dirname, join } from "node:path"
+import { fileURLToPath } from "node:url"
+import { runInNewContext } from "node:vm"
+import { describe, expect, test } from "bun:test"
+
+import { bunWhich } from "./bun-which-shim"
+
+type BunWhichFunction = (commandName: string) => string | null
+type BunWhichRuntime = {
+  Transpiler?: new (options: { loader: "ts" }) => { transformSync(source: string): string }
+  which(commandName: string): string | null
+}
+type SandboxProcess = {
+  env: { PATH?: string; Path?: string }
+  platform: typeof process.platform
+}
+type BunWhichSandbox = {
+  accessSync: typeof accessSync
+  constants: typeof constants
+  console: Console
+  delimiter: typeof delimiter
+  join: typeof join
+  process: SandboxProcess
+  __bunWhichShim?: { bunWhich: BunWhichFunction }
+}
+
+const runtime = globalThis as typeof globalThis & { Bun?: BunWhichRuntime }
+const PATH_TRAVERSAL_COMMAND_NAMES = [
+  "../etc/passwd",
+  "/etc/passwd",
+  "./tool",
+  "sub/dir/tool",
+  "C:\\Windows\\evil",
+  "C:tool",
+  ".",
+  "..",
+  "node..evil",
+]
+const NULL_BYTE_COMMAND_NAME = "node\0evil"
+const NODE_FALLBACK_BUN_WHICH = loadNodeFallbackBunWhich()
+
+function loadNodeFallbackBunWhich(): BunWhichFunction {
+  const sourcePath = join(dirname(fileURLToPath(import.meta.url)), "bun-which-shim.ts")
+  const source = readFileSync(sourcePath, "utf8")
+  const fsImport = 'import { accessSync, constants } from "node:fs"\n'
+  const pathImport = 'import { delimiter, join } from "node:path"\n'
+  const exportSignature = "export function bunWhich(commandName: string): string | null {"
+
+  if (!source.includes(fsImport) || !source.includes(pathImport) || !source.includes(exportSignature)) {
+    throw new Error("bunWhich source shape changed")
+  }
+
+  const scriptSource = `${source
+    .replace(fsImport, "")
+    .replace(pathImport, "")
+    .replace(exportSignature, "function bunWhich(commandName: string): string | null {")}\nglobalThis.__bunWhichShim = { bunWhich }\n`
+  const transpilerConstructor = runtime.Bun?.Transpiler
+  if (!transpilerConstructor) {
+    throw new Error("Bun Transpiler unavailable")
+  }
+
+  const transpiler = new transpilerConstructor({ loader: "ts" })
+  const script = transpiler.transformSync(scriptSource)
+  const sandboxProcess: SandboxProcess = {
+    env: { PATH: process.env.PATH, Path: process.env.Path },
+    platform: process.platform,
+  }
+  const sandbox: BunWhichSandbox = { accessSync, constants, console, delimiter, join, process: sandboxProcess }
+
+  runInNewContext(script, sandbox, { filename: sourcePath })
+
+  const nodeFallbackBunWhich = sandbox.__bunWhichShim?.bunWhich
+  if (!nodeFallbackBunWhich) {
+    throw new Error("Node fallback bunWhich loader failed")
+  }
+
+  return nodeFallbackBunWhich
+}
+
+describe("bunWhich", () => {
+  test("#given 'node' command #when resolved #then returns a non-null path ending in 'node'", () => {
+    const resolvedPath = bunWhich("node")
+
+    expect(resolvedPath).not.toBeNull()
+    expect(resolvedPath?.toLowerCase()).toMatch(/node(?:\.exe)?$/)
+  })
+
+  test("#given a non-existent command #when resolved #then returns null", () => {
+    const resolvedPath = bunWhich("this-command-definitely-does-not-exist-abc123xyz")
+
+    expect(resolvedPath).toBeNull()
+  })
+
+  test("#given an empty string #when resolved #then returns null", () => {
+    const resolvedPath = bunWhich("")
+
+    expect(resolvedPath).toBeNull()
+  })
+
+  test("#given the result for 'node' #when resolved #then the returned path matches Bun.which('node')", () => {
+    const nativePath = runtime.Bun?.which("node")
+    const shimPath = bunWhich("node")
+
+    expect(nativePath).not.toBeNull()
+    expect(shimPath).toBe(nativePath)
+  })
+
+  test("#given path-traversal command names #when resolved through Bun runtime #then returns null", () => {
+    for (const commandName of PATH_TRAVERSAL_COMMAND_NAMES) {
+      expect(bunWhich(commandName)).toBeNull()
+    }
+  })
+
+  test("#given a null-byte command name #when resolved through Bun runtime #then returns null", () => {
+    expect(bunWhich(NULL_BYTE_COMMAND_NAME)).toBeNull()
+  })
+})
+
+describe("#given Node fallback bunWhich loaded without Bun global", () => {
+  test("#when 'node' command is resolved #then returns a non-null path ending in 'node'", () => {
+    const resolvedPath = NODE_FALLBACK_BUN_WHICH("node")
+
+    expect(resolvedPath).not.toBeNull()
+    expect(resolvedPath?.toLowerCase()).toMatch(/node(?:\.exe)?$/)
+  })
+
+  test("#when a non-existent command is resolved #then returns null", () => {
+    const resolvedPath = NODE_FALLBACK_BUN_WHICH("this-does-not-exist-abc123xyz")
+
+    expect(resolvedPath).toBeNull()
+  })
+
+  test("#when an empty string is resolved #then returns null", () => {
+    const resolvedPath = NODE_FALLBACK_BUN_WHICH("")
+
+    expect(resolvedPath).toBeNull()
+  })
+
+  test("#when path-traversal command names are resolved #then returns null", () => {
+    for (const commandName of PATH_TRAVERSAL_COMMAND_NAMES) {
+      expect(NODE_FALLBACK_BUN_WHICH(commandName)).toBeNull()
+    }
+  })
+
+  test("#when a null-byte command name is resolved #then returns null", () => {
+    expect(NODE_FALLBACK_BUN_WHICH(NULL_BYTE_COMMAND_NAME)).toBeNull()
+  })
+})

src/shared/bun-which-shim.ts

@@ -0,0 +1,58 @@
+import { accessSync, constants } from "node:fs"
+import { delimiter, join } from "node:path"
+
+type BunWhichRuntime = { which(commandName: string): string | null }
+const runtime = globalThis as typeof globalThis & { Bun?: BunWhichRuntime }
+const IS_BUN = typeof runtime.Bun !== "undefined"
+
+function isUnsafeCommandName(commandName: string): boolean {
+  if (commandName.includes("/") || commandName.includes("\\")) return true
+  if (commandName === "." || commandName === ".." || commandName.includes("..")) return true
+  if (/^[a-zA-Z]:/.test(commandName)) return true
+  if (commandName.includes("\0")) return true
+
+  return false
+}
+
+function isExecutable(filePath: string): boolean {
+  try {
+    accessSync(filePath, constants.X_OK)
+    return true
+  } catch {
+    return false
+  }
+}
+
+function resolvePathValue(): string | undefined {
+  if (process.platform === "win32") return process.env.Path ?? process.env.PATH
+
+  return process.env.PATH
+}
+
+function getWindowsCandidates(commandName: string): string[] {
+  if (process.platform !== "win32") return [commandName]
+
+  return [commandName, `${commandName}.exe`, `${commandName}.cmd`, `${commandName}.bat`, `${commandName}.com`]
+}
+
+export function bunWhich(commandName: string): string | null {
+  if (!commandName) return null
+  if (isUnsafeCommandName(commandName)) return null
+  if (IS_BUN) return runtime.Bun?.which(commandName) ?? null
+
+  const pathValue = resolvePathValue()
+  if (!pathValue) return null
+
+  const pathEntries = pathValue.split(delimiter).filter((pathEntry) => pathEntry.length > 0)
+  if (pathEntries.length === 0) return null
+
+  const candidateNames = getWindowsCandidates(commandName)
+  for (const pathEntry of pathEntries) {
+    for (const candidateName of candidateNames) {
+      const candidatePath = join(pathEntry, candidateName)
+      if (isExecutable(candidatePath)) return candidatePath
+    }
+  }
+
+  return null
+}

src/shared/dist-bundle-bun-globals.test.ts

@@ -1,9 +1,58 @@
+/// <reference types="bun-types" />
+
 import { existsSync } from "node:fs"
 import { describe, expect, test } from "bun:test"
 
 const DIST_INDEX = "dist/index.js"
 const GLOBAL_BUN_DESTRUCTURE = /^\s*(?:var|let|const)\s*\{[^}]*\}\s*=\s*globalThis\.Bun/gm
 const TOP_LEVEL_REQUIRE_CALL = "__require("
+const RAW_BUN_API_CALL = /(?<![.$\w])Bun\.[a-zA-Z_$][a-zA-Z_$0-9]*\s*[.(]/g
+const NODE_EXPORT_SMOKE_SCRIPT = [
+  "const mod = await import('./dist/index.js');",
+  "const keys = Object.keys(mod).join(',');",
+  "console.log('SMOKE_OK:' + keys);",
+].join("\n")
+
+function hasRawBunApiCall(line: string): boolean {
+  RAW_BUN_API_CALL.lastIndex = 0
+  return RAW_BUN_API_CALL.test(line)
+}
+
+function isInsideStringLiteral(line: string, position: number): boolean {
+  let quote: "'" | '"' | "`" | null = null
+  let escaped = false
+
+  for (let index = 0; index < position; index += 1) {
+    const char = line.charAt(index)
+
+    if (escaped) {
+      escaped = false
+      continue
+    }
+
+    if (quote !== null && char === "\\") {
+      escaped = true
+      continue
+    }
+
+    if (char === "'" || char === '"' || char === "`") {
+      if (quote === char) {
+        quote = null
+      } else if (quote === null) {
+        quote = char
+      }
+    }
+  }
+
+  return quote !== null
+}
+
+function formatOffendingLine(lineNumber: number, line: string): string {
+  const content = line.trim()
+  const truncated = content.length > 120 ? `${content.slice(0, 117)}...` : content
+
+  return `${lineNumber}: ${truncated}`
+}
 
 describe("dist bundle Bun globals", () => {
   test.skipIf(!existsSync(DIST_INDEX))("#given dist bundle #when scanned #then no globalThis.Bun destructures remain", async () => {
@@ -62,4 +111,66 @@ describe("dist bundle Bun globals", () => {
       stderr: "",
     })
   })
+
+  test.skipIf(!existsSync(DIST_INDEX))("#given dist bundle #when scanned for raw Bun runtime APIs #then no unshimmed Bun API calls remain", async () => {
+    expect(hasRawBunApiCall("Bun.file('dist/index.js')")).toBe(true)
+    expect(hasRawBunApiCall("runtime.Bun.file('dist/index.js')")).toBe(false)
+    expect(hasRawBunApiCall(".Bun.file('dist/index.js')")).toBe(false)
+    expect(hasRawBunApiCall("$Bun.file('dist/index.js')")).toBe(false)
+    expect(hasRawBunApiCall("Bun.spawnSync.options")).toBe(true)
+    expect(hasRawBunApiCall("Bun.readableStreamToText(stream)")).toBe(true)
+
+    const dist = await Bun.file(DIST_INDEX).text()
+    const offending: string[] = []
+    let insideJSDoc = false
+
+    for (const [index, line] of dist.split("\n").entries()) {
+      const trimmed = line.trimStart()
+
+      if (insideJSDoc || trimmed.startsWith("/**")) {
+        insideJSDoc = !trimmed.includes("*/")
+        continue
+      }
+
+      if (line.includes("runtime.Bun") || line.includes("globalThis.Bun") || line.includes("typeof Bun")) {
+        continue
+      }
+
+      RAW_BUN_API_CALL.lastIndex = 0
+      const rawMatch = [...line.matchAll(RAW_BUN_API_CALL)].find(
+        (match) => match.index !== undefined && !isInsideStringLiteral(line, match.index),
+      )
+
+      if (rawMatch) {
+        offending.push(formatOffendingLine(index + 1, line))
+      }
+    }
+
+    expect(
+      offending,
+      `Expected zero raw Bun API calls in dist/index.js but found ${offending.length}:\n${offending.join("\n")}`,
+    ).toEqual([])
+  })
+
+  test.skipIf(!existsSync(DIST_INDEX))("#given dist bundle #when imported and inspected under node --input-type=module #then stderr has no Bun reference errors", async () => {
+    const node = Bun.which("node")
+    if (!node) return
+
+    const proc = Bun.spawn({
+      cmd: [node, "--input-type=module", "-e", NODE_EXPORT_SMOKE_SCRIPT],
+      cwd: process.cwd(),
+      stdout: "pipe",
+      stderr: "pipe",
+    })
+
+    const stdout = await new Response(proc.stdout).text()
+    const stderr = await new Response(proc.stderr).text()
+    const exitCode = await proc.exited
+    const stderrLower = stderr.toLowerCase()
+
+    expect(exitCode, stderr.trim()).toBe(0)
+    expect(stdout).toContain("SMOKE_OK:")
+    expect(stderrLower).not.toContain("referenceerror")
+    expect(stderr).not.toContain("Bun is not defined")
+  })
 })

src/shared/event-session-id.test.ts

@@ -0,0 +1,40 @@
+import { describe, expect, test } from "bun:test"
+
+import { resolveMessageEventSessionID, resolveSessionEventID } from "./event-session-id"
+
+describe("event session id resolvers", () => {
+  test("#given legacy message.part.updated properties #when resolving message session id #then part.sessionID is used", () => {
+    const sessionID = resolveMessageEventSessionID({
+      part: {
+        id: "part-1",
+        messageID: "msg-1",
+        sessionID: "ses-part-only",
+        type: "text",
+        text: "working",
+      },
+    })
+
+    expect(sessionID).toBe("ses-part-only")
+  })
+
+  test("#given message.updated info id #when resolving message session id #then message id is not mistaken for session id", () => {
+    const sessionID = resolveMessageEventSessionID({
+      info: {
+        id: "msg-not-session",
+        role: "assistant",
+      },
+    })
+
+    expect(sessionID).toBeUndefined()
+  })
+
+  test("#given legacy session lifecycle properties #when resolving session id #then info.id is used", () => {
+    const sessionID = resolveSessionEventID({
+      info: {
+        id: "ses-legacy-info-id",
+      },
+    })
+
+    expect(sessionID).toBe("ses-legacy-info-id")
+  })
+})

src/shared/event-session-id.ts

@@ -0,0 +1,23 @@
+import { isRecord } from "./record-type-guard"
+
+function getStringField(record: Record<string, unknown> | undefined, key: string): string | undefined {
+  const value = record?.[key]
+  return typeof value === "string" && value.length > 0 ? value : undefined
+}
+
+export function resolveSessionEventID(properties: unknown): string | undefined {
+  const props = isRecord(properties) ? properties : undefined
+  const info = isRecord(props?.info) ? props.info : undefined
+  return getStringField(props, "sessionID")
+    ?? getStringField(info, "sessionID")
+    ?? getStringField(info, "id")
+}
+
+export function resolveMessageEventSessionID(properties: unknown): string | undefined {
+  const props = isRecord(properties) ? properties : undefined
+  const info = isRecord(props?.info) ? props.info : undefined
+  const part = isRecord(props?.part) ? props.part : undefined
+  return getStringField(props, "sessionID")
+    ?? getStringField(info, "sessionID")
+    ?? getStringField(part, "sessionID")
+}

src/shared/index.ts

@@ -54,6 +54,7 @@ export * from "./fallback-model-availability"
 export * from "./connected-providers-cache"
 export * from "./context-limit-resolver"
 export * from "./session-utils"
+export * from "./event-session-id"
 export * from "./tmux"
 export * from "./model-suggestion-retry"
 export * from "./opencode-server-auth"

src/shared/port-utils.test.ts

@@ -1,291 +1,393 @@
-import { afterEach, beforeEach, describe, expect, it, spyOn } from "bun:test"
+import { createServer, Server } from "node:net"
-import {
+import type { AddressInfo } from "node:net"
-  isPortAvailable,
+import { networkInterfaces } from "node:os"
-  findAvailablePort,
-  getAvailableServerPort,
-  DEFAULT_SERVER_PORT,
-} from "./port-utils"
 
-const HOSTNAME = "127.0.0.1"
+import { afterAll, afterEach, beforeAll, describe, expect, test } from "bun:test"
-const REAL_PORT_SEARCH_WINDOW = 200
 
-function supportsRealSocketBinding(): boolean {
+import { DEFAULT_SERVER_PORT, findAvailablePort, getAvailableServerPort, isPortAvailable } from "./port-utils"
-  try {
+
-    const server = Bun.serve({
+const DEFAULT_HOSTNAME = "127.0.0.1"
-      port: 0,
+const MAX_PORT_ATTEMPTS = 20
-      hostname: HOSTNAME,
+const EXHAUSTED_PORT_COUNT = MAX_PORT_ATTEMPTS + 1
-      fetch: () => new Response("probe"),
+const CONTIGUOUS_SEARCH_WINDOW = 256
+const CONTIGUOUS_SEARCH_SEEDS = 8
+
+const trackedServers = new Set<Server>()
+
+type TimeoutProbeResult = {
+  closeCallCount: number
+  isAvailable: boolean
+  server: Server | undefined
+}
+
+function getRequiredPropertyDescriptor(target: object, propertyName: string): PropertyDescriptor {
+  const descriptor = Object.getOwnPropertyDescriptor(target, propertyName)
+  if (!descriptor) {
+    throw new Error(`Expected ${propertyName} property descriptor`)
+  }
+
+  return descriptor
+}
+
+function isTcpAddress(address: ReturnType<Server["address"]>): address is AddressInfo {
+  return typeof address === "object" && address !== null && "port" in address
+}
+
+function getServerPort(server: Server): number {
+  const address = server.address()
+  if (!isTcpAddress(address)) {
+    throw new Error("Expected TCP server address")
+  }
+
+  return address.port
+}
+
+function getAlternateIpv4Hostname(): string | undefined {
+  for (const addresses of Object.values(networkInterfaces())) {
+    if (!addresses) continue
+
+    for (const address of addresses) {
+      if (address.family === "IPv4" && !address.internal && address.address !== DEFAULT_HOSTNAME) {
+        return address.address
+      }
+    }
+  }
+
+  return undefined
+}
+
+function startTrackedServer(port: number, hostname: string = DEFAULT_HOSTNAME): Promise<Server> {
+  return new Promise<Server>((resolve, reject) => {
+    const server = createServer()
+
+    const removeListeners = (): void => {
+      server.removeListener("error", handleError)
+      server.removeListener("listening", handleListening)
+    }
+
+    const handleError = (error: Error): void => {
+      removeListeners()
+      trackedServers.delete(server)
+      reject(error)
+    }
+
+    const handleListening = (): void => {
+      removeListeners()
+      trackedServers.add(server)
+      resolve(server)
+    }
+
+    server.once("error", handleError)
+    server.once("listening", handleListening)
+
+    try {
+      server.listen(port, hostname)
+    } catch (error) {
+      removeListeners()
+      trackedServers.delete(server)
+      reject(error)
+    }
+  })
+}
+
+function closeTrackedServer(server: Server): Promise<void> {
+  trackedServers.delete(server)
+
+  if (!server.listening) {
+    return Promise.resolve()
+  }
+
+  return new Promise<void>((resolve, reject) => {
+    server.close((error?: Error) => {
+      if (error) {
+        reject(error)
+        return
+      }
+
+      resolve()
     })
-    server.stop(true)
+  })
+}
+
+async function closeAllTrackedServers(): Promise<void> {
+  await Promise.all(Array.from(trackedServers).map((server) => closeTrackedServer(server)))
+}
+
+async function getReleasedPort(hostname: string = DEFAULT_HOSTNAME): Promise<number> {
+  const server = await startTrackedServer(0, hostname)
+  const port = getServerPort(server)
+  await closeTrackedServer(server)
+
+  return port
+}
+
+async function canBindContiguousPorts(
+  startPort: number,
+  portCount: number,
+  hostname: string = DEFAULT_HOSTNAME
+): Promise<boolean> {
+  const servers: Server[] = []
+
+  try {
+    for (let offset = 0; offset < portCount; offset++) {
+      servers.push(await startTrackedServer(startPort + offset, hostname))
+    }
+
     return true
   } catch {
     return false
+  } finally {
+    await Promise.all(servers.map((server) => closeTrackedServer(server)))
   }
 }
 
-const canBindRealSockets = supportsRealSocketBinding()
+async function findContiguousAvailableStart(
+  portCount: number,
+  hostname: string = DEFAULT_HOSTNAME
+): Promise<number> {
+  for (let seedAttempt = 0; seedAttempt < CONTIGUOUS_SEARCH_SEEDS; seedAttempt++) {
+    const seedPort = await getReleasedPort(hostname)
+    const maxStartPort = Math.min(65_535 - portCount + 1, seedPort + CONTIGUOUS_SEARCH_WINDOW)
 
-describe("port-utils", () => {
+    for (let candidatePort = seedPort; candidatePort <= maxStartPort; candidatePort++) {
-  if (canBindRealSockets) {
+      if (await canBindContiguousPorts(candidatePort, portCount, hostname)) {
-    function startRealBlocker(port: number = 0) {
+        return candidatePort
-      return Bun.serve({
-        port,
-        hostname: HOSTNAME,
-        fetch: () => new Response("blocked"),
-      })
-    }
-
-    async function findContiguousAvailableStart(length: number): Promise<number> {
-      const probe = startRealBlocker()
-      const seedPort = probe.port
-      probe.stop(true)
-
-      for (let candidate = seedPort; candidate < seedPort + REAL_PORT_SEARCH_WINDOW; candidate++) {
-        const checks = await Promise.all(
-          Array.from({ length }, async (_, offset) => isPortAvailable(candidate + offset, HOSTNAME))
-        )
-        if (checks.every(Boolean)) {
-          return candidate
-        }
       }
-
-      throw new Error(`Could not find ${length} contiguous available ports`)
     }
-
-    describe("with real sockets", () => {
-      describe("isPortAvailable", () => {
-        it("#given unused port #when checking availability #then returns true", async () => {
-          const blocker = startRealBlocker()
-          const port = blocker.port
-          blocker.stop(true)
-
-          const result = await isPortAvailable(port)
-          expect(result).toBe(true)
-        })
-
-        it("#given port in use #when checking availability #then returns false", async () => {
-          const blocker = startRealBlocker()
-          const port = blocker.port
-
-          try {
-            const result = await isPortAvailable(port)
-            expect(result).toBe(false)
-          } finally {
-            blocker.stop(true)
-          }
-        })
-      })
-
-      describe("findAvailablePort", () => {
-        it("#given start port available #when finding port #then returns start port", async () => {
-          const startPort = await findContiguousAvailableStart(1)
-          const result = await findAvailablePort(startPort)
-          expect(result).toBe(startPort)
-        })
-
-        it("#given start port blocked #when finding port #then returns next available", async () => {
-          const startPort = await findContiguousAvailableStart(2)
-          const blocker = startRealBlocker(startPort)
-
-          try {
-            const result = await findAvailablePort(startPort)
-            expect(result).toBe(startPort + 1)
-          } finally {
-            blocker.stop(true)
-          }
-        })
-
-        it("#given multiple ports blocked #when finding port #then skips all blocked", async () => {
-          const startPort = await findContiguousAvailableStart(4)
-          const blockers = [
-            startRealBlocker(startPort),
-            startRealBlocker(startPort + 1),
-            startRealBlocker(startPort + 2),
-          ]
-
-          try {
-            const result = await findAvailablePort(startPort)
-            expect(result).toBe(startPort + 3)
-          } finally {
-            blockers.forEach((blocker) => blocker.stop(true))
-          }
-        })
-      })
-
-      describe("getAvailableServerPort", () => {
-        it("#given preferred port available #when getting port #then returns preferred with wasAutoSelected=false", async () => {
-          const preferredPort = await findContiguousAvailableStart(1)
-          const result = await getAvailableServerPort(preferredPort)
-          expect(result.port).toBe(preferredPort)
-          expect(result.wasAutoSelected).toBe(false)
-        })
-
-        it("#given preferred port blocked #when getting port #then returns alternative with wasAutoSelected=true", async () => {
-          const preferredPort = await findContiguousAvailableStart(2)
-          const blocker = startRealBlocker(preferredPort)
-
-          try {
-            const result = await getAvailableServerPort(preferredPort)
-            expect(result.port).toBe(preferredPort + 1)
-            expect(result.wasAutoSelected).toBe(true)
-          } finally {
-            blocker.stop(true)
-          }
-        })
-      })
-    })
-  } else {
-    const blockedSockets = new Set<string>()
-    let serveSpy: ReturnType<typeof spyOn>
-
-    function getSocketKey(port: number, hostname: string): string {
-      return `${hostname}:${port}`
-    }
-
-    beforeEach(() => {
-      blockedSockets.clear()
-      serveSpy = spyOn(Bun, "serve").mockImplementation(({ port, hostname }) => {
-        if (typeof port !== "number") {
-          throw new Error("Test expected numeric port")
-        }
-        const resolvedHostname = typeof hostname === "string" ? hostname : HOSTNAME
-        const socketKey = getSocketKey(port, resolvedHostname)
-
-        if (blockedSockets.has(socketKey)) {
-          const error = new Error(`Failed to start server. Is port ${port} in use?`) as Error & {
-            code?: string
-            syscall?: string
-            errno?: number
-            address?: string
-            port?: number
-          }
-          error.code = "EADDRINUSE"
-          error.syscall = "listen"
-          error.errno = 0
-          error.address = resolvedHostname
-          error.port = port
-          throw error
-        }
-
-        blockedSockets.add(socketKey)
-        return {
-          stop: (_force?: boolean) => {
-            blockedSockets.delete(socketKey)
-          },
-        } as { stop: (force?: boolean) => void }
-      })
-    })
-
-    afterEach(() => {
-      expect(blockedSockets.size).toBe(0)
-      serveSpy.mockRestore()
-      blockedSockets.clear()
-    })
-
-    describe("with mocked sockets fallback", () => {
-      describe("isPortAvailable", () => {
-        it("#given unused port #when checking availability #then returns true", async () => {
-          const port = 59999
-
-          const result = await isPortAvailable(port)
-          expect(result).toBe(true)
-          expect(blockedSockets.size).toBe(0)
-        })
-
-        it("#given port in use #when checking availability #then returns false", async () => {
-          const port = 59998
-          const blocker = Bun.serve({
-            port,
-            hostname: HOSTNAME,
-            fetch: () => new Response("blocked"),
-          })
-
-          try {
-            const result = await isPortAvailable(port)
-            expect(result).toBe(false)
-          } finally {
-            blocker.stop(true)
-          }
-        })
-
-        it("#given custom hostname #when checking availability #then passes hostname through to Bun.serve", async () => {
-          const hostname = "192.0.2.10"
-          await isPortAvailable(59995, hostname)
-
-          expect(serveSpy.mock.calls[0]?.[0]?.hostname).toBe(hostname)
-        })
-      })
-
-      describe("findAvailablePort", () => {
-        it("#given start port available #when finding port #then returns start port", async () => {
-          const startPort = 59997
-          const result = await findAvailablePort(startPort)
-          expect(result).toBe(startPort)
-        })
-
-        it("#given start port blocked #when finding port #then returns next available", async () => {
-          const startPort = 59996
-          const blocker = Bun.serve({
-            port: startPort,
-            hostname: HOSTNAME,
-            fetch: () => new Response("blocked"),
-          })
-
-          try {
-            const result = await findAvailablePort(startPort)
-            expect(result).toBe(startPort + 1)
-          } finally {
-            blocker.stop(true)
-          }
-        })
-
-        it("#given multiple ports blocked #when finding port #then skips all blocked", async () => {
-          const startPort = 59993
-          const blockers = [
-            Bun.serve({ port: startPort, hostname: HOSTNAME, fetch: () => new Response() }),
-            Bun.serve({ port: startPort + 1, hostname: HOSTNAME, fetch: () => new Response() }),
-            Bun.serve({ port: startPort + 2, hostname: HOSTNAME, fetch: () => new Response() }),
-          ]
-
-          try {
-            const result = await findAvailablePort(startPort)
-            expect(result).toBe(startPort + 3)
-          } finally {
-            blockers.forEach((blocker) => blocker.stop(true))
-          }
-        })
-      })
-
-      describe("getAvailableServerPort", () => {
-        it("#given preferred port available #when getting port #then returns preferred with wasAutoSelected=false", async () => {
-          const preferredPort = 59990
-          const result = await getAvailableServerPort(preferredPort)
-          expect(result.port).toBe(preferredPort)
-          expect(result.wasAutoSelected).toBe(false)
-        })
-
-        it("#given preferred port blocked #when getting port #then returns alternative with wasAutoSelected=true", async () => {
-          const preferredPort = 59989
-          const blocker = Bun.serve({
-            port: preferredPort,
-            hostname: HOSTNAME,
-            fetch: () => new Response("blocked"),
-          })
-
-          try {
-            const result = await getAvailableServerPort(preferredPort)
-            expect(result.port).toBe(preferredPort + 1)
-            expect(result.wasAutoSelected).toBe(true)
-          } finally {
-            blocker.stop(true)
-          }
-        })
-      })
-    })
   }
 
-  describe("DEFAULT_SERVER_PORT", () => {
+  throw new Error(`Could not find ${portCount} contiguous available ports`)
-    it("#given constant #when accessed #then returns 4096", () => {
+}
+
+async function startConsecutiveBlockers(
+  startPort: number,
+  portCount: number,
+  hostname: string = DEFAULT_HOSTNAME
+): Promise<Server[]> {
+  const servers: Server[] = []
+
+  try {
+    for (let offset = 0; offset < portCount; offset++) {
+      servers.push(await startTrackedServer(startPort + offset, hostname))
+    }
+
+    return servers
+  } catch (error) {
+    await Promise.all(servers.map((server) => closeTrackedServer(server)))
+    throw error
+  }
+}
+
+async function captureDefaultListenHostname(port: number): Promise<string | undefined> {
+  const listenDescriptor = getRequiredPropertyDescriptor(Server.prototype, "listen")
+  const closeDescriptor = getRequiredPropertyDescriptor(Server.prototype, "close")
+  let capturedHostname: string | undefined
+
+  Object.defineProperty(Server.prototype, "listen", {
+    configurable: true,
+    value: function listenAndCaptureHostname(this: Server, requestedPort: number, hostname?: string): Server {
+      if (requestedPort === port) {
+        capturedHostname = hostname
+      }
+      queueMicrotask(() => this.emit("listening"))
+      return this
+    },
+  })
+  Object.defineProperty(Server.prototype, "close", {
+    configurable: true,
+    value: function closeCapturedServer(this: Server, callback?: (error?: Error) => void): Server {
+      queueMicrotask(() => callback?.())
+      return this
+    },
+  })
+
+  try {
+    await isPortAvailable(port)
+    return capturedHostname
+  } finally {
+    Object.defineProperty(Server.prototype, "listen", listenDescriptor)
+    Object.defineProperty(Server.prototype, "close", closeDescriptor)
+  }
+}
+
+async function runTimedOutAvailabilityProbe(port: number): Promise<TimeoutProbeResult> {
+  const setTimeoutDescriptor = getRequiredPropertyDescriptor(globalThis, "setTimeout")
+  const listenDescriptor = getRequiredPropertyDescriptor(Server.prototype, "listen")
+  const closeDescriptor = getRequiredPropertyDescriptor(Server.prototype, "close")
+  const originalSetTimeout = globalThis.setTimeout
+  let timedOutServer: Server | undefined
+  let closeCallCount = 0
+
+  Object.defineProperty(globalThis, "setTimeout", {
+    configurable: true,
+    value: (callback: () => void): ReturnType<typeof setTimeout> => originalSetTimeout(callback, 0),
+  })
+  Object.defineProperty(Server.prototype, "listen", {
+    configurable: true,
+    value: function listenWithoutEmitting(this: Server): Server {
+      timedOutServer = this
+      return this
+    },
+  })
+  Object.defineProperty(Server.prototype, "close", {
+    configurable: true,
+    value: function closeTimedOutServer(this: Server, callback?: (error?: Error) => void): Server {
+      closeCallCount++
+      queueMicrotask(() => callback?.())
+      return this
+    },
+  })
+
+  try {
+    const isAvailable = await isPortAvailable(port)
+    return { closeCallCount, isAvailable, server: timedOutServer }
+  } finally {
+    Object.defineProperty(globalThis, "setTimeout", setTimeoutDescriptor)
+    Object.defineProperty(Server.prototype, "listen", listenDescriptor)
+    Object.defineProperty(Server.prototype, "close", closeDescriptor)
+  }
+}
+
+describe("port-utils", () => {
+  beforeAll(() => {
+    trackedServers.clear()
+  })
+
+  afterEach(async () => {
+    await closeAllTrackedServers()
+  })
+
+  afterAll(async () => {
+    await closeAllTrackedServers()
+  })
+
+  describe("#given isPortAvailable", () => {
+    test("#when a released port is checked #then returns true", async () => {
+      const port = await getReleasedPort()
+
+      const result = await isPortAvailable(port)
+
+      expect(result).toBe(true)
+    })
+
+    test("#when an already bound port is checked #then returns false", async () => {
+      const blocker = await startTrackedServer(0)
+      const port = getServerPort(blocker)
+
+      const result = await isPortAvailable(port)
+
+      expect(result).toBe(false)
+    })
+
+    test("#when a timed out probe is cleaned up #then no listeners or server remain active", async () => {
+      const port = await getReleasedPort()
+
+      const result = await runTimedOutAvailabilityProbe(port)
+
+      expect(result.isAvailable).toBe(false)
+      expect(result.closeCallCount).toBe(1)
+      expect(result.server).toBeDefined()
+      if (!result.server) {
+        throw new Error("Expected timed out server")
+      }
+      expect(result.server.listening).toBe(false)
+      expect(result.server.listenerCount("error")).toBe(0)
+      expect(result.server.listenerCount("listening")).toBe(0)
+    })
+
+    test("#when a successful probe finishes #then the port can be rebound immediately", async () => {
+      const port = await getReleasedPort()
+
+      const result = await isPortAvailable(port)
+      const server = await startTrackedServer(port)
+
+      expect(result).toBe(true)
+      expect(getServerPort(server)).toBe(port)
+    })
+
+    test("#when hostname is omitted #then 127.0.0.1 is the default target", async () => {
+      const blocker = await startTrackedServer(0, DEFAULT_HOSTNAME)
+      const port = getServerPort(blocker)
+
+      const result = await isPortAvailable(port)
+
+      expect(result).toBe(false)
+    })
+
+    test("#when another interface owns the port #then default probing does not bind all interfaces", async () => {
+      const alternateHostname = getAlternateIpv4Hostname()
+
+      if (!alternateHostname) {
+        const port = await getReleasedPort()
+        const capturedHostname = await captureDefaultListenHostname(port)
+        expect(capturedHostname).toBe(DEFAULT_HOSTNAME)
+        return
+      }
+
+      const blocker = await startTrackedServer(0, alternateHostname)
+      const port = getServerPort(blocker)
+
+      expect(await isPortAvailable(port)).toBe(true)
+      expect(await isPortAvailable(port, alternateHostname)).toBe(false)
+    })
+  })
+
+  describe("#given findAvailablePort", () => {
+    test("#when the start port is available #then returns the start port", async () => {
+      const startPort = await findContiguousAvailableStart(1)
+
+      const result = await findAvailablePort(startPort)
+
+      expect(result).toBe(startPort)
+    })
+
+    test("#when the first three ports are blocked #then returns the next free port", async () => {
+      const startPort = await findContiguousAvailableStart(4)
+      await startConsecutiveBlockers(startPort, 3)
+
+      const result = await findAvailablePort(startPort)
+
+      expect(result).toBe(startPort + 3)
+    })
+
+    test("#when every attempted port is blocked #then throws", async () => {
+      const startPort = await findContiguousAvailableStart(EXHAUSTED_PORT_COUNT)
+      await startConsecutiveBlockers(startPort, EXHAUSTED_PORT_COUNT)
+
+      let errorMessage: string | undefined
+      try {
+        await findAvailablePort(startPort)
+      } catch (error) {
+        if (!(error instanceof Error)) {
+          throw error
+        }
+        errorMessage = error.message
+      }
+
+      expect(errorMessage).toBe(`No available port found in range ${startPort}-${startPort + MAX_PORT_ATTEMPTS - 1}`)
+    })
+  })
+
+  describe("#given getAvailableServerPort", () => {
+    test("#when the preferred port is free #then returns the preferred port without auto-selection", async () => {
+      const preferredPort = await findContiguousAvailableStart(1)
+
+      const result = await getAvailableServerPort(preferredPort)
+
+      expect(result).toEqual({ port: preferredPort, wasAutoSelected: false })
+    })
+
+    test("#when the preferred port is blocked #then returns the next port with auto-selection", async () => {
+      const preferredPort = await findContiguousAvailableStart(2)
+      await startTrackedServer(preferredPort)
+
+      const result = await getAvailableServerPort(preferredPort)
+      expect(result).toEqual({ port: preferredPort + 1, wasAutoSelected: true })
+    })
+  })
+
+  describe("#given DEFAULT_SERVER_PORT", () => {
+    test("#when accessed #then returns 4096", () => {
       expect(DEFAULT_SERVER_PORT).toBe(4096)
     })
   })

src/shared/port-utils.ts

@@ -1,18 +1,53 @@
+import { createServer } from "node:net"
+
 const DEFAULT_SERVER_PORT = 4096
 const MAX_PORT_ATTEMPTS = 20
+const PORT_CHECK_TIMEOUT_MS = 2000
 
 export async function isPortAvailable(port: number, hostname: string = "127.0.0.1"): Promise<boolean> {
-  try {
+  return new Promise<boolean>((resolve) => {
-    const server = Bun.serve({
+    const server = createServer()
-      port,
+    let timeoutId: ReturnType<typeof setTimeout> | undefined
-      hostname,
+    let resolved = false
-      fetch: () => new Response(),
+
+    const finish = (isAvailable: boolean): void => {
+      if (resolved) {
+        return
+      }
+      resolved = true
+      if (timeoutId) {
+        clearTimeout(timeoutId)
+      }
+      server.removeAllListeners("error")
+      server.removeAllListeners("listening")
+      resolve(isAvailable)
+    }
+
+    const closeThenFinish = (isAvailable: boolean): void => {
+      try {
+        server.close(() => finish(isAvailable))
+      } catch {
+        finish(isAvailable)
+      }
+    }
+
+    timeoutId = setTimeout(() => {
+      closeThenFinish(false)
+    }, PORT_CHECK_TIMEOUT_MS)
+
+    server.once("error", () => {
+      finish(false)
     })
-    server.stop(true)
+    server.once("listening", () => {
-    return true
+      closeThenFinish(true)
-  } catch {
+    })
-    return false
+
-  }
+    try {
+      server.listen(port, hostname)
+    } catch {
+      finish(false)
+    }
+  })
 }
 
 export async function findAvailablePort(

src/tools/hashline-edit/hash-computation.ts

@@ -1,12 +1,13 @@
 import { HASHLINE_DICT } from "./constants"
 import { createHashlineChunkFormatter } from "./hashline-chunk-formatter"
+import { bunHashXxh32 } from "../../shared/bun-hash-shim"
 
 const RE_SIGNIFICANT = /[\p{L}\p{N}]/u
 
 function computeNormalizedLineHash(lineNumber: number, normalizedContent: string): string {
   const stripped = normalizedContent
   const seed = RE_SIGNIFICANT.test(stripped) ? 0 : lineNumber
-  const hash = Bun.hash.xxHash32(stripped, seed)
+  const hash = bunHashXxh32(stripped, seed)
   const index = hash % 256
   return HASHLINE_DICT[index]
 }

src/tools/hashline-edit/hashline-edit-executor.ts

@@ -1,5 +1,6 @@
 import type { ToolContext } from "@opencode-ai/plugin/tool"
 import { publishToolMetadata } from "../../features/tool-metadata-store"
+import { bunFile, bunWrite } from "../../shared/bun-file-shim"
 import { applyHashlineEditsWithReport } from "./edit-operations"
 import { countLineDiffs, generateUnifiedDiff } from "./diff-utils"
 import { canonicalizeFileText, restoreFileText } from "./file-text-canonicalization"
@@ -94,7 +95,7 @@ export async function executeHashlineEditTool(args: HashlineEditArgs, context: T
 
     const edits = deleteMode ? [] : normalizeHashlineEdits(args.edits)
 
-    const file = Bun.file(filePath)
+    const file = bunFile(filePath)
     const exists = await file.exists()
     if (!exists && !deleteMode && !canCreateFromMissingFile(edits)) {
       return `Error: File not found: ${filePath}`
@@ -102,7 +103,7 @@ export async function executeHashlineEditTool(args: HashlineEditArgs, context: T
 
     if (deleteMode) {
       if (!exists) return `Error: File not found: ${filePath}`
-      await Bun.file(filePath).delete()
+      await bunFile(filePath).delete()
       return `Successfully deleted ${filePath}`
     }
 
@@ -122,11 +123,11 @@ export async function executeHashlineEditTool(args: HashlineEditArgs, context: T
 
     const writeContent = restoreFileText(canonicalNewContent, oldEnvelope)
 
-    await Bun.write(filePath, writeContent)
+    await bunWrite(filePath, writeContent)
 
     if (pluginCtx?.client) {
       await runFormattersForFile(pluginCtx.client as FormatterClient, context.directory, filePath)
-      const formattedContent = Buffer.from(await Bun.file(filePath).arrayBuffer()).toString("utf8")
+      const formattedContent = Buffer.from(await bunFile(filePath).arrayBuffer()).toString("utf8")
       if (formattedContent !== writeContent) {
         const formattedEnvelope = canonicalizeFileText(formattedContent)
         const formattedMeta = buildSuccessMeta(
@@ -138,8 +139,8 @@ export async function executeHashlineEditTool(args: HashlineEditArgs, context: T
         )
         await publishToolMetadata(metadataContext, formattedMeta)
         if (rename && rename !== filePath) {
-          await Bun.write(rename, formattedContent)
+          await bunWrite(rename, formattedContent)
-          await Bun.file(filePath).delete()
+          await bunFile(filePath).delete()
           return `Moved ${filePath} to ${rename}`
         }
         return `Updated ${filePath}`
@@ -147,8 +148,8 @@ export async function executeHashlineEditTool(args: HashlineEditArgs, context: T
     }
 
     if (rename && rename !== filePath) {
-      await Bun.write(rename, writeContent)
+      await bunWrite(rename, writeContent)
-      await Bun.file(filePath).delete()
+      await bunFile(filePath).delete()
     }
 
     const effectivePath = rename && rename !== filePath ? rename : filePath