fix(session): preserve plugin turn invariants

packages/hooks/hook-protocol/src/invariant.ts

@@ -17,6 +17,11 @@ interface HookTransition {
   delta: 1 | -1
 }
 
+interface HookTrace {
+  openTurn: number | null
+  pending: Map<string, number>
+}
+
 /** Correlation key shared by an invoked/result pair. */
 function hookKey(data: { turn: number; point: string; handlerId: string }): string {
   return `${data.turn}\0${data.point}\0${data.handlerId}`
@@ -24,10 +29,15 @@ function hookKey(data: { turn: number; point: string; handlerId: string }): stri
 
 /** Validate one hook event against committed pending invocations. */
 function validateHookEvent(
-  pending: ReadonlyMap<string, number>,
+  trace: HookTrace,
   event: SessionEvent,
   fail: InvariantFailure,
 ): HookTransition | undefined {
+  if (event.type !== 'hook/invoked' && event.type !== 'hook/result') return undefined
+  if (trace.openTurn === null) fail(`${event.type} appended outside any open turn`)
+  if (event.data.turn !== trace.openTurn) {
+    fail(`${event.type} names turn ${event.data.turn} but open turn is ${trace.openTurn}`)
+  }
   if (event.type === 'hook/invoked') {
     if (event.data.point.length === 0 || event.data.handlerId.length === 0) {
       fail('hook/invoked point and handlerId must be non-empty')
@@ -38,9 +48,8 @@ function validateHookEvent(
     }
     return { key: hookKey(event.data), delta: 1 }
   }
-  if (event.type !== 'hook/result') return undefined
   const key = hookKey(event.data)
-  if ((pending.get(key) ?? 0) === 0) {
+  if ((trace.pending.get(key) ?? 0) === 0) {
     fail(`hook/result has no matching hook/invoked for ${JSON.stringify(event.data.handlerId)}`)
   }
   if (!Number.isFinite(event.data.durationMs) || event.data.durationMs < 0) {
@@ -60,28 +69,39 @@ function applyHookTransition(pending: Map<string, number>, transition: HookTrans
 // Event owners keep precommit staging local so their vocabularies never move into a central helper.
 /* jscpd:ignore-start */
 const install: InvariantInstaller = Object.assign((ctx: Context, fail: InvariantFailure) => {
-  const traces = new WeakMap<Session, Map<string, number>>()
+  const traces = new WeakMap<Session, HookTrace>()
   const staged = new WeakMap<SessionEvent, { session: Session; transition: HookTransition }>()
-  const seed = (session: Session): Map<string, number> => {
-    const pending = new Map<string, number>()
-    traces.set(session, pending)
+  const seed = (session: Session): HookTrace => {
+    const trace: HookTrace = { openTurn: null, pending: new Map() }
+    traces.set(session, trace)
     for (const event of session.events) {
-      const transition = validateHookEvent(pending, event, fail)
-      if (transition !== undefined) applyHookTransition(pending, transition)
+      if (event.type === 'turn/start') trace.openTurn = event.data.turn
+      else if (event.type === 'turn/end') trace.openTurn = null
+      const transition = validateHookEvent(trace, event, fail)
+      if (transition !== undefined) applyHookTransition(trace.pending, transition)
     }
-    return pending
+    return trace
   }
-  const traceFor = (session: Session): Map<string, number> => traces.get(session) ?? seed(session)
+  const traceFor = (session: Session): HookTrace => traces.get(session) ?? seed(session)
 
   for (const session of ctx.sessions.list()) seed(session)
   ctx.on('session/created', (session) => { seed(session) }, { global: true })
   ctx.on('session/event', (session, event) => {
+    const trace = traceFor(session)
+    if (event.type === 'turn/start') {
+      trace.openTurn = event.data.turn
+      return
+    }
+    if (event.type === 'turn/end') {
+      trace.openTurn = null
+      return
+    }
     if (event.type !== 'hook/invoked' && event.type !== 'hook/result') return
     const candidate = staged.get(event)
     /* v8 ignore next -- internal/dispatch stages every hook provenance event */
     if (candidate === undefined || candidate.session !== session) return fail('hook event published without pre-commit validation')
     staged.delete(event)
-    applyHookTransition(traceFor(session), candidate.transition)
+    applyHookTransition(trace.pending, candidate.transition)
   }, { global: true })
   ctx.on('internal/dispatch', (_mode, eventName, args) => {
     if (eventName !== 'session/event') return

packages/hooks/hook-protocol/tests/invariant.spec.ts

@@ -29,12 +29,18 @@ const result = (overrides: Record<string, unknown> = {}) => ({
   ...overrides,
 })
 
+function startTurn(session: Session, turn = 1): void {
+  session.append('turn/start', { turn, trigger: { kind: 'message', source: { kind: 'user' } } })
+}
+
 describe('hook-protocol invariants', () => {
   it('pairs serial and repeated handler invocations', async () => {
     const ctx = await setup()
     const session = ctx.sessions.create()
+    startTurn(session)
     session.append('hook/invoked', invoked())
     session.append('hook/invoked', invoked())
+    session.append('step/start', { turn: 1, step: 1 })
     session.append('hook/result', result())
     session.append('hook/result', result())
   })
@@ -56,26 +62,52 @@ describe('hook-protocol invariants', () => {
     const session = new Session(SessionId('bare-hook-session'))
     expect(() => {
       ctx.emit('session/event', session, {
-        type: 'hook/invoked', seq: 0, time: 0, data: invoked(),
+        type: 'turn/start', seq: 0, time: 0,
+        data: { turn: 1, trigger: { kind: 'message', source: { kind: 'user' } } },
       })
       ctx.emit('session/event', session, {
-        type: 'hook/result', seq: 1, time: 1, data: result(),
+        type: 'hook/invoked', seq: 1, time: 1, data: invoked(),
+      })
+      ctx.emit('session/event', session, {
+        type: 'hook/result', seq: 2, time: 2, data: result(),
       })
     }).not.toThrow()
   })
 
+  it('rejects hook events outside or for a different open turn', async () => {
+    const ctx = await setup()
+    const session = ctx.sessions.create()
+    expect(() => session.append('hook/invoked', invoked())).toThrow(/outside any open turn/)
+    startTurn(session)
+    expect(() => session.append('hook/invoked', invoked({ turn: 2 }))).toThrow(/but open turn is 1/)
+  })
+
+  it('rejects an unenclosed hook event when replaying an existing session', async () => {
+    const ctx = new Context()
+    await ctx.plugin(SessionStore)
+    const session = ctx.sessions.create()
+    startTurn(session)
+    session.append('turn/end', { turn: 1, reason: { kind: 'completed' } })
+    session.append('hook/invoked', invoked())
+    await ctx.plugin(InvariantService)
+    await expect(ctx.plugin(HookInvariant).then(() => undefined)).rejects.toThrow(/outside any open turn/)
+  })
+
   it.each([
     [invoked({ point: '' }), /point and handlerId must be non-empty/],
     [invoked({ handlerId: '' }), /point and handlerId must be non-empty/],
     [invoked({ dialect: 'other' }), /unknown dialect/],
   ])('rejects malformed hook invocation %#', async (data, message) => {
     const ctx = await setup()
-    expect(() => ctx.sessions.create().append('hook/invoked', data as never)).toThrow(message)
+    const session = ctx.sessions.create()
+    startTurn(session)
+    expect(() => session.append('hook/invoked', data as never)).toThrow(message)
   })
 
   it('rejects unmatched and malformed results', async () => {
     const ctx = await setup()
     const session = ctx.sessions.create()
+    startTurn(session)
     expect(() => session.append('hook/result', result())).toThrow(/no matching hook\/invoked/)
     session.append('hook/invoked', invoked())
     expect(() => session.append('hook/result', result({ durationMs: -1 })))