fix(mode): guard suspended retry flush disposal

packages/mode/mode/src/index.ts

@@ -234,6 +234,7 @@ export class ModesService extends Service {
   constructor(ctx: Context, config: ModeConfig = { modes: {} }) {
     super(ctx, 'modes')
     this.resolved = resolveConfig(config)
+    let disposed = false
 
     // Boundary flushes ride the loop's interception seams, NOT the
     // `session/event` feed: post-commit session observers are observe-only
@@ -273,7 +274,10 @@ export class ModesService extends Service {
       next,
     ) => {
       const decision = await next()
-      if (decision.action !== 'retry') return decision
+      // A waterfall can capture this wrapper before Cordis unregisters it.
+      // Do not let that stale continuation mutate the session after its
+      // owning plugin fiber has been disposed.
+      if (disposed || decision.action !== 'retry') return decision
       try {
         this.onBoundary(agent.session, false)
       } catch (error) {
@@ -281,6 +285,7 @@ export class ModesService extends Service {
       }
       return decision
     }, { prepend: true })
+    ctx.effect(() => () => { disposed = true }, 'dsh-mode: close boundary lifetime')
 
     ctx.on('agent/created', (agent) => {
       const seed = agent.options.mode

packages/mode/mode/tests/mode.spec.ts

@@ -874,6 +874,30 @@ describe('exit_plan_mode', () => {
 })
 
 describe('HMR disposal', () => {
+  it('does not flush a retry boundary that resumes after plugin disposal', async () => {
+    const ctx = new Context()
+    await ctx.plugin(SystemPrompt)
+    await ctx.plugin(ToolRegistry)
+    const fiber = await ctx.plugin(ModesService, PLAN_CONFIG)
+    const agent = agentWithSession('disposed-in-flight-recovery')
+    const recoveryEntered = Promise.withResolvers<true>()
+    const releaseRecovery = Promise.withResolvers<true>()
+    ctx.on('agent/request-error', async (_agent, _turn, _step, _error, _failure, _history, _signal, _next) => {
+      recoveryEntered.resolve(true)
+      await releaseRecovery.promise
+      return { action: 'retry' }
+    })
+    ctx.modes.set(agent, PLAN_MODE)
+
+    const recovery = recoveryBoundary(ctx, agent, { action: 'fail' })
+    await recoveryEntered.promise
+    await fiber.dispose()
+    releaseRecovery.resolve(true)
+
+    expect(await recovery).toEqual({ action: 'retry' })
+    expect(agent.session.events.some(event => event.type === 'mode/set')).toBe(false)
+  })
+
   it('unregisters the service, listeners, prompt section, and stable exit tool with the plugin fiber', async () => {
     const ctx = new Context()
     await ctx.plugin(SystemPrompt)