tasks/docs/red-review-zap-sdk.md

Red Review — ZAP SDK (pkg/sdk) on feat/zap-internal

Reviewer: Red (adversarial) Branch state at review: a9a061e06 feat(sdk/worker): native poll/dispatch runtime, zero upstream deps HEAD: a9a061e06. All five Blue commits landed:

• 7174e9d81 feat(sdk/temporal) — Blue#1
• 86961b48b feat(sdk/activity) — Blue#3
• f928a20fc feat(sdk/workflow) — Blue#4
• a3c9d818d feat(sdk/client) — Blue#2
• a9a061e06 feat(sdk/worker) — Blue#5 (landed during review)

Build + race-test pass against the delivered tree:

ok  github.com/hanzoai/tasks/pkg/sdk/activity
ok  github.com/hanzoai/tasks/pkg/sdk/client
ok  github.com/hanzoai/tasks/pkg/sdk/temporal
ok  github.com/hanzoai/tasks/pkg/sdk/worker
ok  github.com/hanzoai/tasks/pkg/sdk/workflow

That is the thinnest possible definition of "green." The findings below are everything the green bar does not catch.

---

1. Import purity

Scope: pkg/sdk/**.

$ rg 'go\.temporal\.io' pkg/sdk     # all hits are comments only
$ rg 'google\.golang\.org/grpc' pkg/sdk   # all hits are comments only

Result: clean. No go.temporal.io/* imports, no google.golang.org/grpc imports anywhere under pkg/sdk/. References are all in package-doc comments and migration notes. The policy stated in pkg/sdk/doc.go is honoured.

Severity: n/a (pass).

Caveat — this only covers pkg/sdk/. Outside the SDK, go.temporal.io/sdk and go.temporal.io/api are still pervasive in tests/, service/worker/workerdeployment/, and temporaltest/. Flagging because the task spec says "zero go.temporal.io imports anywhere in the binary", and the binary still links those. Example hits:

service/worker/workerdeployment/workflow.go
service/worker/workerdeployment/version_workflow.go
service/worker/workerdeployment/client.go
service/worker/workerdeployment/util.go
tests/xdc/...
tests/testcore/functional_test_base.go
temporaltest/embedded/server.go
temporaltest/internal/lite_server.go

CI cannot enforce go.temporal.io/sdk = 0 hits binary-wide until these are migrated or vendored behind the new surface.

---

2. Interface coverage — gap matrix

Caller repos surveyed:

• ~/work/hanzo/base/plugins/tasks/ — workflows.go, activities.go, worker.go, durable.go.
• ~/work/hanzo/commerce/billing/workflows/ — dunning.go, register.go, subscription.go.
• ~/work/hanzo/commerce/infra/tasks.go.
• ~/work/hanzo/ta — does not exist on this machine. Review was performed against base + commerce only.

Caller symbol universe (extracted via grep):

activity.GetLogger
activity.RecordHeartbeat
client.Client, client.Close, client.Dial, client.Options
client.ExecuteWorkflow, client.SignalWorkflow, client.CancelWorkflow,
client.TerminateWorkflow, client.SignalWithStartWorkflow,
client.GetWorkflow, client.QueryWorkflow, client.CheckHealth
client.StartWorkflowOptions, client.WorkflowRun, client.WorkflowRunGetOptions
temporal.RetryPolicy
worker.InterruptCh, worker.New, worker.Options, worker.Worker (w.Run / w.Start / w.Stop)
workflow.ActivityOptions, workflow.Context, workflow.Future, workflow.ReceiveChannel
workflow.ExecuteActivity, workflow.ExecuteChildWorkflow, workflow.LocalActivityOptions
workflow.GetLogger, workflow.GetSignalChannel, workflow.NewSelector, workflow.NewTimer
workflow.Now, workflow.WithActivityOptions, workflow.WithCancel

Type constructors via external packages (must be satisfied or factored):
go.temporal.io/api/workflowservice/v1.ListWorkflowExecutionsRequest
client.DescribeWorkflowExecution → *workflowservice.DescribeWorkflowExecutionResponse
response.WorkflowExecutionInfo.GetStatus().String()
run.Get(ctx, result) and run.GetWithOptions(ctx, result, opts)

Gap table — SDK symbol callers need but no Blue agent shipped:

Needed by caller	Status	Severity	Note
workflow.ExecuteChildWorkflow	missing	HIGH	commerce/billing/workflows/subscription.go L157 calls workflow.ExecuteChildWorkflow(ctx, DunningWorkflow, ...). Absent.
workflow.LocalActivityOptions (type + WithLocalActivityOptions)	missing	HIGH	commerce/infra/tasks.go L346-355. Absent.
client.QueryWorkflow	missing	HIGH	commerce/infra/tasks.go L189-202. Absent from client.Client.
client.SignalWithStartWorkflow	missing	HIGH	commerce/infra/tasks.go L146-169. Absent.
client.GetWorkflow(ctx, id, runID) WorkflowRun	missing	HIGH	commerce/infra/tasks.go L127-134. Absent.
client.CheckHealth(ctx, req) (*resp, error)	shape mismatch	HIGH	commerce/infra/tasks.go L255. SDK has Health(ctx)(string,string,error); commerce expects the upstream shape.
client.WorkflowRun.GetWithOptions(ctx, valuePtr, opts)	missing	MEDIUM	commerce/infra/tasks.go L317-319. Absent from client.WorkflowRun.
client.WorkflowRunGetOptions	missing	MEDIUM	commerce/infra/tasks.go L317. Absent.
worker.InterruptCh() <-chan interface{} (package-level)	missing	HIGH	commerce/infra/tasks.go L236, L243. The package-level constructor is absent; Worker.Run(interruptCh <-chan any) exists but the idiom w.Run(worker.InterruptCh()) won't compile.
worker.Options.MaxConcurrentWorkflowTaskExecutionSize	missing	MEDIUM	commerce/infra/tasks.go L214. Only MaxConcurrentWorkflowTaskPollers is exposed; commerce expects the execution-size knob.
worker.Options.MaxConcurrentLocalActivityExecutionSize	missing	MEDIUM	commerce/infra/tasks.go L215. Absent.
worker.Options.WorkerActivitiesPerSecond	missing	MEDIUM	commerce/infra/tasks.go L216. Absent.
worker.Options.WorkerLocalActivitiesPerSecond	missing	MEDIUM	commerce/infra/tasks.go L217. Absent.
worker.Options.TaskQueueActivitiesPerSecond	missing	MEDIUM	commerce/infra/tasks.go L218. Absent.
worker.Options.EnableSessionWorker	missing	MEDIUM	commerce/infra/tasks.go L219. Absent.
client.ListWorkflow(ctx, *workflowservice.ListWorkflowExecutionsRequest) (*Resp, error)	shape mismatch	HIGH	base/plugins/tasks/durable.go L314, L373. base imports the upstream workflowservice package and passes a protobuf request. SDK ships ListWorkflows(ctx, query, pageSize, token) with a totally different signature + zero workflowservice types. base will not compile post-migration without a rewrite.
client.DescribeWorkflowExecution(ctx, id, runID)	shape mismatch	HIGH	base/plugins/tasks/durable.go L256-275. base calls desc.WorkflowExecutionInfo.GetStatus().String() — protobuf-generated accessor chain. SDK returns a flat *WorkflowExecutionInfo with Status WorkflowStatus (int8). base needs a full conversion layer.
workflow.GetLogger	present	—	OK.
workflow.GetSignalChannel	present	—	OK.
workflow.NewSelector.AddFuture/AddReceive/AddDefault/Select	present	—	OK.
workflow.NewTimer / WithCancel / WithActivityOptions / ExecuteActivity	present	—	OK.
workflow.Now	present	—	OK.
workflow.ReceiveChannel.Receive(ctx, valPtr) → signature mismatch	bug	HIGH	See Finding #6.2 below. SDK's ReceiveChannel.Receive returns (ok bool); base/plugins/tasks/workflows.go calls it for its side effect only (ch.Receive(ctx, &data) ignoring return) which is source-compatible, but Temporal's upstream returns void — a two-valued returns force unused-returns linters to complain and any Go code that used ch.Receive(ctx, &v) as an expression fragment breaks. Low-blast but must be documented.
temporal.RetryPolicy	present	—	OK. Shape matches.
activity.GetLogger, activity.RecordHeartbeat, activity.GetInfo	present	—	OK.

Before base or commerce can flip their imports, every HIGH row above is a compile-time blocker. That is the feature matrix CI needs to gate on before enforcing the go.temporal.io/sdk = 0 hits rule.

---

3. Wire-contract adherence (schema/tasks.zap vs. implementation)

3.1 Opcode-to-RPC mapping — pass

All 20 RPCs declared in schema/tasks.zap are backed by an opcode in the client or worker_transport. No RPC in the schema is orphaned; no opcode in the implementation is orphaned. Allocation:

0x0050-0x005F  legacy pkg/tasks one-shot (reserved; unchanged)
0x0060-0x0065  startWorkflow, signal, cancel, terminate, describe, listWorkflows
0x0070-0x0073  createSchedule, listSchedules, deleteSchedule, pauseSchedule
0x0080-0x0082  registerNamespace, describeNamespace, listNamespaces
0x0090         health
0x00A0-0x00A5  pollWorkflowTask, pollActivityTask, respond* (workflow/activity), heartbeat

Note on stability: transport.go historically declared worker opcodes at 0x0070-0x007F (first landing of Blue#2 stored them there), which collided with client schedule opcodes. Blue#2's second revision moved them to 0x00A0-0x00A5. If any pre-GA server build is already deployed that used the 0x0070-0x007F layout, it will silently route worker polls to createSchedule/listSchedules/... and produce decode errors that look transient. The append-only contract in schema/tasks.zap must be respected — document the relocation in the schema file so no server build references the old numbers.

3.2 Request/response struct layout — mismatches

The schema is the authoritative wire contract. Implementations deviate:

3.2.1 Payloads wrapping lost — MEDIUM, cross-service compat issue

Schema:

struct RespondActivityTaskCompletedRequest
  taskToken Bytes
  result Payloads                 # = struct { items List(Payload) }

struct RecordActivityTaskHeartbeatRequest
  taskToken Bytes
  details Payloads

struct ActivityTask
  ...
  input Payloads

struct WorkflowTask
  ...
  workflowType WorkflowType       # struct { name Text }
  workflowExecution WorkflowExecution   # struct { workflowId, runId }

Implementation (pkg/sdk/client/transport.go + worker_transport.go):

RespondActivityTaskCompletedRequest.Result []byte          # raw bytes, not Payloads
RecordActivityTaskHeartbeatRequest.Details []byte          # raw bytes, not Payloads
ActivityTask.Input []byte                                  # raw bytes, not Payloads
WorkflowTask.WorkflowTypeName string                       # flat, not WorkflowType
WorkflowTask.WorkflowID / RunID string                     # flat, not WorkflowExecution
PollWorkflowTaskRequest.TaskQueueName / TaskQueueKind     # flat, not TaskQueue

Every Payloads → Bytes collapse is a schema mismatch that will produce frames no schema-conformant server (or alternate worker implementation) can decode. In particular:

• A MIME-type roundtrip (metadata Bytes inside Payload) is lost — the worker has no way to honour non-JSON payloads coming off the wire.
• A server that emits the canonical schema's nested object will produce zap frames with fields at offsets the client does not read; client will see empty strings/bytes for WorkflowTypeName, WorkflowID, etc. The workflow type lookup will then fall through to the "no workflow registered" path (dispatch.go L51-66) and the server will see every workflow silently "complete with empty commands."

3.2.2 High-level RPC bodies are JSON-blob-in-ZAP-envelope, not schema-native

Schema:

startWorkflow (req StartWorkflowRequest) -> (resp StartWorkflowResponse)

StartWorkflowRequest is a typed ZAP struct with 8 fields; StartWorkflowResponse is { runId Text }.

Implementation (pkg/sdk/client/client.go L235-254):

// envelope:
//   field 0  Bytes  = JSON body
//   field 8  Uint32 = status
//   field 12 Bytes  = error detail

Every high-level RPC (startWorkflow, signal, cancel, terminate, describe, list, schedule/, namespace/, health) is sent as a single Bytes field holding JSON. The schema structs are not populated at all — their field offsets never appear in the wire. A server that parses StartWorkflowRequest per the schema sees an unknown-field frame. A ZAP peer that validates schema will reject these frames outright.

The workaround is documented ("v1 wire note: single Bytes field") but the schema file (schema/tasks.zap) does not say that — the schema currently lies about what's on the wire.

3.2.3 Health RPC response shape — MEDIUM

Schema: health () -> (service Text, status Text) — two typed fields on the response object.

Client (pkg/sdk/client/schedule.go L212-222): sends {} as a JSON body and unmarshals a JSON {"service":"…","status":"…"} out of the body field. Schema-conformant server emitting (service Text, status Text) at field offsets N, M will not populate the JSON body. The client will then decode "" for service/status.

3.2.4 Response envelope status at Uint32 field 8 — MINOR schema drift

The wire envelope declares status at field offset 8 and error at field offset 12. The schema has no "envelope" concept; each RPC's response is whatever its schema struct declares. The current envelope forces every response to carry 24 bytes of object header + status + error slots that the schema does not declare, and steals field offset 0 for the JSON body. If a future schema RPC declares a struct with a Bytes field at offset 0, the wire will be ambiguous.

Action for Blue (wire contract): Either (a) rewrite the schema to declare this JSON-envelope explicitly as the v1 contract and state that every high-level RPC embeds its real body in field 0, or (b) land native ZAP serde for each RPC that matches the declared struct. Until one of the two is done, schema/tasks.zap is a lie. Pick one and make it true.

---

4. Determinism — where replay will diverge

4.1 Phase-1 "replay" is a stub, by declaration

pkg/sdk/worker/dispatch.go L71:

env := workflow.NewStubEnv()
ctx2 := workflow.NewContextFromEnv(env)

Every time a WorkflowTask is dispatched the worker constructs a fresh workflow.StubEnv and runs the user's workflow function from scratch against it. There is no event log, no replay, no history scheduler. This is acknowledged in pkg/sdk/workflow/env.go L24-32 as Phase 1. Accepting that, here are the concrete traps user code will hit today:

4.2 Activities never touch the wire in Phase 1 — CRITICAL behavioural surprise

dispatch.go line 71 uses workflow.NewStubEnv() — the same StubEnv used by tests, with no activity registrations populated at runtime. stub.go L245-275 resolves ExecuteActivity by looking up e.activities[name] and returns the pre-registered response; if none exists it settles the Future with (nil, nil) — success, empty payload. That means in production today:

• A workflow that calls workflow.ExecuteActivity(ctx, "ExecuteTask", task) gets a Future that settles immediately with nil, nil.
• f.Get(ctx, &result) decodes nil into result — no-op, no error.
• task.State stays whatever default it was initialised to.
• Server receives an empty commands response (dispatch.go L101 hard-codes Commands: nil).

Base's AgentTaskWorkflow (base/plugins/tasks/workflows.go L65) would enter this path with actFuture settling to nil immediately, then Selector would fire the future case and set task.State = TaskCompleted with task.Output = nil — silent task "success" with no activity ever running. A production user hitting this path would see workflows flip to completed instantly, with no side effects, no audit trail, and no way to distinguish a successful activity from a stubbed one.

This is the biggest blast radius of the delivery. It's not a bug by intent — it's the declared Phase-1 shape — but a service that imports this SDK and doesn't realise the StubEnv is the runtime will ship broken workflows to production.

Fix priority: the worker must either (a) dispatch activities over the wire via its own CoroutineEnv, or (b) refuse to start when the registered workflow calls ExecuteActivity and the dispatch env is StubEnv. Either way, the current behaviour (silent no-op) is unacceptable.

4.3 StubEnv.Select busy-spins — HIGH, production DoS

stub.go L292-312:

for {
    if idx := readyIndex(cases); idx >= 0 {
        return idx
    }
    select {
    case <-sc.done: return -1
    case <-time.After(time.Millisecond): // re-check
    }
}

Every 1 ms the selector re-scans its cases. time.After(time.Millisecond) allocates a new timer each iteration — no caching. With N workers running N workflows each with M selector loops:

• CPU: N·M·1000 Hz of re-scan work + timer allocation.
• Memory: one *time.Timer leak per iteration until GC'd.

Under moderate load (100 concurrent workflows × 3 selectors each) this burns a core just to spin. On a Kubernetes pod with a CPU limit this will throttle the real workflow path.

Fix priority: replace the spin with a condvar or a signal channel fan-in that parks until one of the cases can emit. See the standard Temporal dispatcher idiom — one goroutine per workflow driven by a runChan that the settlement/signal paths write to.

4.4 StubEnv.NewTimer fires instantly + advances clock — determinism violation

stub.go L235-243:

func (e *StubEnv) NewTimer(d time.Duration) Future {
    f := NewFuture()
    e.AdvanceClock(d)
    f.Settle(nil, nil)
    return f
}

In a real workflow, a timer fires at the right workflow time and the selector unblocks. In Phase-1 the timer is already settled when NewTimer returns. That means:

• Base's AgentTaskWorkflow builds workflow.NewTimer(timerCtx, 24h) and tops the selector with it. In production, the selector sees the timer as ready immediately; timerFuture.Get returns nil; the callback runs the timeout path; workflow status becomes "timeout" on first poll. The real 24-hour wait collapses to a few microseconds.
• Commerce's DunningWorkflow schedules workflow.NewTimer(timerCtx, delay) between dunning attempts. Today the delay is zero; dunning fires every retry back-to-back as fast as the worker can poll. The retry schedule (24h / 72h / 168h) is ignored. A payment processor that dunning-spams is an automatic customer incident.
• Commerce's SubscriptionLifecycleWorkflow.Phase2 is a forever-loop with NewTimer(PeriodEnd.Sub(Now)). With instant timers, workflow.Now(ctx) returns a stub clock that jumps on each call. sleepDuration = params.PeriodEnd.Sub(now) evaluates once with the stub clock; the timer fires immediately; the next iteration sees the clock already past PeriodEnd. The workflow immediately invokes RenewSubscriptionActivity. In production this bills every subscriber on their first workflow task rather than at period end.

Fix priority: Phase-1 is not safe for billing workflows. Block shipping commerce/billing on this SDK until the worker owns a real event-time scheduler.

4.5 workflow.Now(ctx) vs time.Now() — no enforcement

The doc (workflow/env.go L36-38) forbids calling time.Now, rand.Read, spawning goroutines inside workflow functions. There is no linter or runtime check. Existing caller code already drifts:

• base/plugins/tasks/workflows.go L109-110, L120-121: now := time.Now().UTC(); task.CompletedAt = &now inside the workflow function. Today this calls wall-clock time even though the workflow is supposedly deterministic. The symptom: on replay (Phase 2) different runs stamp different completion times.
• commerce/billing/workflows/dunning.go — no wall clock, but the workflow builds dunningSchedule = []time.Duration{...} as a package var which is compiled in; if the binary restarts with a different value (e.g. A/B test config flag), replays would use a different schedule.

Fix priority: ship the tasks-vet linter mentioned in the env.go doc before Phase 2, and fail base compilation. CI can grep for time.Now() inside functions whose first parameter is workflow.Context.

4.6 Workflow arg decode path conflates history with input — HIGH

dispatch.go L77-78:

args, decodeErr := decodeWorkflowArgs(fn, ctx2, task.History)

Schema declares WorkflowTask.history Bytes as "encoded WorkflowHistory frame" — the entire event log. The client decodes it as a JSON array of workflow arguments. Every WorkflowTask's history field becomes the input JSON. So:

• On any non-first workflow task (after a signal), the server must package the start-input into history again or the worker will re-decode yesterday's history bytes as this morning's args.
• Server implementations of pollWorkflowTask that emit a real event log would produce history bytes the client cannot decode as []json.RawMessage — appendDecodedArgs falls back to "treat the whole input as one arg" (L412-416), which silently binds the history bytes to arg[0]. The user's activity then receives garbage.

Fix priority: separate the input and the history in the schema (WorkflowTask.input Payloads + history Bytes) and in the transport, and have dispatch read input for arg decoding. The current shape is not even self-consistent for Phase 1.

4.7 invokeFunc swallows the workflow's return error — HIGH

dispatch.go L94:

// Invoke synchronously. Errors from the workflow itself are captured
// by the engine — the worker's job is to ship commands; errors
// manifest as commands in Phase 2.
_ = invokeFunc(fn, args)

The workflow returns (T, error); the worker discards err. A workflow that returns fmt.Errorf("boom") today will respond to the server with "success, empty commands." The server will mark the workflow completed rather than failed. There is zero feedback loop for a workflow-level error path.

Commerce's DunningWorkflow returns nil on its happy paths but returns a real error when the dunning workflow itself crashes (return err inside Phase 2 of subscription.go L147). That error is silently dropped.

Fix priority: encode workflow errors into a FailureCommand today — a one-commit Phase-1 fix, not a Phase-2 deferral.

---

5. Ranked attack surface

5.1 [CRITICAL] Workflow activities are no-ops in production dispatch

Description: pkg/sdk/worker/dispatch.go L71 uses workflow.NewStubEnv() as the workflow runtime, which means every workflow.ExecuteActivity settles to (nil,nil) without ever contacting the matching service. Workflows appear to succeed; no activity runs. Location: pkg/sdk/worker/dispatch.go:71, pkg/sdk/workflow/stub.go:245-275 Attack Complexity: None — default behaviour. Exploitability: Any service that imports this SDK and calls ExecuteActivity. Impact: Silent data corruption — billing/dunning/task workflows appear complete while doing nothing. Tasks marked Completed without the executor running. Payment processor emits invoices that never post. Detectability: No. Telemetry will show workflow completions + zero activity invocations, a pattern nobody is looking for. Fix Hint: The worker must dispatch activities over the wire (pollActivityTask / respondActivityTaskCompleted) or must refuse to Start when a registered workflow calls ExecuteActivity against a StubEnv runtime.

5.2 [CRITICAL] Billing timers collapse to zero duration

Description: StubEnv.NewTimer settles the Future immediately and advances the stub clock by the requested duration. Any workflow using workflow.NewTimer executes its "after timer fires" path on the first poll. Commerce subscription/dunning schedules collapse. Location: pkg/sdk/workflow/stub.go:235-243; consumed at pkg/sdk/worker/dispatch.go:71 Attack Complexity: None — default behaviour. Exploitability: First commerce deploy. Impact: Dunning fires back-to-back without the 24h/72h/168h gaps; subscription renewal happens at workflow start rather than period end; customer billed early; dunning emails spammed. Detectability: Visible if monitoring tracks dunning interval histograms. Otherwise not. Fix Hint: Do not ship commerce/billing on Phase 1. Worker must own an event-time scheduler that parks timers until the clock advances.

5.3 [HIGH] Missing SDK symbols block base and commerce migration

Description: client.SignalWithStartWorkflow, client.GetWorkflow, client.QueryWorkflow, client.CheckHealth, workflow.ExecuteChildWorkflow, workflow.LocalActivityOptions, worker.InterruptCh, and multiple worker.Options fields are absent. See §2 for the full table. Location: pkg/sdk/{client,workflow,worker}/ Attack Complexity: n/a — this is a compile-time gap. Exploitability: n/a. Impact: go build of hanzoai/base and hanzoai/commerce fails after import swap. CI cannot enforce go.temporal.io/sdk = 0 hits until every row is closed. Fix Hint: Prioritise this list over Phase-2 replay. Without it the migration cannot begin.

5.4 [HIGH] Schema lies: StartWorkflowRequest fields never touch the wire

Description: Every high-level RPC is sent as a JSON body inside a generic {body, status, error} envelope (client.go L235-254). The startWorkflowRequest struct declared in schema/tasks.zap — with its Payloads, Timeouts, RetryPolicy sub-structs — is not emitted on the wire. A schema-conformant server will reject these frames as malformed. A schema-driven client in another language will not interoperate. Location: schema/tasks.zap:77-95; pkg/sdk/client/client.go:235-254 Attack Complexity: High (cross-implementation interop only). Exploitability: Any non-Go ZAP peer. Impact: The canonical wire contract is unenforced. Wire-format drift is invisible. Fix Hint: Document the JSON envelope in the schema OR ship native ZAP serde for every RPC. Pick one.

5.5 [HIGH] Worker encodes input Payloads as raw Bytes

Description: Schema declares ActivityTask.input Payloads (a list of {metadata Bytes, data Bytes}); transport.go collapses it to Input []byte. MIME types and multi-argument encoding (two Payload entries = two args) are lost. Workers in other languages that produce schema-conformant Payloads will see empty inputs. Location: pkg/sdk/client/transport.go:145-155; pkg/sdk/client/worker_transport.go:194-211 Attack Complexity: n/a. Exploitability: Interop. Impact: Multi-language worker interop broken. Activity args that are not flat JSON are unrepresentable. Fix Hint: Honour the schema; encode Payloads as a nested list of {metadata, data}.

5.6 [HIGH] WorkflowTask.WorkflowType is flattened, losing schema layering

Description: Schema: WorkflowTask.workflowType: WorkflowType where WorkflowType = struct { name Text }. Implementation: flat WorkflowTypeName string. A server emitting the nested struct will produce a frame where WorkflowTypeName at the client's field 24 offset is empty — the worker will look up an empty-string name in its registry and fall through to "no workflow registered" (dispatch.go L51-66), silently responding with empty commands. Location: pkg/sdk/client/transport.go:133-140; pkg/sdk/client/worker_transport.go:177-191 Attack Complexity: n/a. Exploitability: Any real server that emits the schema-conformant WorkflowTask. Impact: Every workflow silently becomes a no-op on the worker. Same symptom as §5.1 via a different path. Fix Hint: Encode/decode nested WorkflowExecution + WorkflowType per schema.

5.7 [HIGH] Workflow errors silently swallowed in dispatch

Description: _ = invokeFunc(fn, args) in dispatch.go L94 discards the workflow's return error. Workflows that explicitly return err are reported as completed. Location: pkg/sdk/worker/dispatch.go:94 Attack Complexity: None. Exploitability: Any workflow that returns an error. Impact: Failure states invisible to the engine. Retry policies never trigger. Audit logs show success. Fix Hint: Emit a FailureCommand on non-nil error. Trivial fix, do not defer to Phase 2.

5.8 [HIGH] PollWorkflowTaskRequest.taskQueue flattened — schema mismatch

Description: Schema: taskQueue: TaskQueue (name Text, kind Int8). Implementation: flat TaskQueueName string + TaskQueueKind int8 encoded as separate top-level fields. A server reading a schema-conformant nested TaskQueue struct sees an empty task-queue name on every worker poll. Location: pkg/sdk/client/transport.go:116-130; pkg/sdk/client/worker_transport.go:112-134 Impact: No workers receive tasks. Poll returns unrouted. Fix Hint: Encode as nested TaskQueue per schema.

5.9 [MEDIUM] StubEnv.Select busy-spin + timer-allocation storm

Description: 1 ms spin + time.After allocation per cycle per workflow. Scales as N·M·1000 per-second where N = live workflows, M = selectors per workflow. On a typical 100-workflow service this is ~300k allocations/second in GC, plus 1 CPU burned. Location: pkg/sdk/workflow/stub.go:292-312 Attack Complexity: None. Exploitability: Any high-throughput workload. Impact: CPU throttling, GC pressure, elevated p99 on every unrelated operation in the process. Fix Hint: Replace with a condvar + per-env "readable" channel that the settlers write to.

5.10 [MEDIUM] Heartbeat sink captures closure with live context — leak-prone

Description: dispatch.go L191-201 closes over ctx, task, w.transport inside scope.HeartbeatSink. After the activity returns, if user code spawned a goroutine that still holds the scope and calls activity.RecordHeartbeat, the sink fires on a stale task token with a stale ctx. If the worker has recycled the task slot the heartbeat hits the wrong task (best case: stale-token rejection; worst case: server lookup accepts it and updates the wrong activity's heartbeat time). Location: pkg/sdk/worker/dispatch.go:189-201 Attack Complexity: Medium — requires user code to leak a goroutine. Exploitability: Low in practice, but reproducible. Impact: Stale-token writes on the wire; cross-task state confusion under goroutine-leak conditions. Fix Hint: Nil out scope.HeartbeatSink after dispatch returns, or gate it on an atomic stopped flag.

5.11 [MEDIUM] json.Marshal failures silently dropped in heartbeat sink

Description: payload, _ := json.Marshal(details) (dispatch.go L192). If marshal fails (channel, func, cyclic reference in user details) the heartbeat ships an empty payload. User's liveness-with-details becomes liveness-without-details; detail-dependent server logic sees empty. Location: pkg/sdk/worker/dispatch.go:192 Fix Hint: Wrap the error path — log at warn, use an empty-but-valid heartbeat or fall back to temporal.Encode shape.

5.12 [MEDIUM] Client.DescribeWorkflow shape incompatible with base caller

Description: base/plugins/tasks/durable.go L256-275 calls desc.WorkflowExecutionInfo.GetStatus().String() (upstream protobuf accessors). SDK returns *client.WorkflowExecutionInfo with Status client.WorkflowStatus (int8). Every base call site breaks post-migration. Location: pkg/sdk/client/workflow.go:25-49 Impact: base is not migrable with the current client surface. Fix Hint: Provide a conversion helper or change the ListWorkflow/DescribeWorkflow return shape to be a superset of what base needs.

5.13 [MEDIUM] Opcode allocation history includes a reuse

Description: Blue#2's first revision of transport.go declared worker poll opcodes at 0x0070-0x0075, which already belong to schedule ops. Second revision moved worker to 0x00A0-0x00A5. If any server build shipped against the first revision, it will route worker polls to createSchedule/listSchedules/... — silent miswiring that returns decode errors. Location: pkg/sdk/client/transport.go:21-32 (current state) Fix Hint: Pin an explicit "opcode history" block in schema/tasks.zap stating what each opcode was used for and when. Opcodes are append-only; document the false-start.

5.14 [MEDIUM] Info TaskToken is copied on return but raw-referenced in-worker

Description: activity.GetInfo deep-copies TaskToken to the caller (good). Inside the worker, scope.Info.TaskToken = copyBytes(task.TaskToken) is a fresh copy — but the HeartbeatSink closure (dispatch.go L195) captures task.TaskToken directly, not via scope. An adversarial activity that tampers with scope.Info.TaskToken via reflection cannot affect the sink, but if future refactors point the sink at scope.Info.TaskToken, the raw-vs-copy distinction becomes load-bearing for isolation. Location: pkg/sdk/worker/dispatch.go:175-201 Fix Hint: Route all sink writes through a single tokenForTask(task) accessor.

5.15 [MEDIUM] workflow.NewFuture is exported but documented as internal

Description: future.go L60 exports NewFuture() Settleable for "worker / StubEnv" use; user workflow code is not expected to call it. It is reachable from any import of github.com/hanzoai/tasks/pkg/sdk/workflow. A user who calls workflow.NewFuture() and Settles it from a goroutine will bypass the entire scheduler, break replay determinism, and see no warning. Location: pkg/sdk/workflow/future.go:60 Fix Hint: Move NewFuture into an internal/ subpackage or a separate workflow/test package that user code does not pull in by default.

5.16 [LOW] Workflow+activity input decoder silently binds garbage to arg[0]

Description: appendDecodedArgs (dispatch.go L404-430) tolerates malformed JSON by treating the whole input as arg[0] when the function signature takes exactly one non-context argument. If the server starts sending a real history log that happens to not parse as a JSON array, the workflow runs with garbage bound to its first argument. Location: pkg/sdk/worker/dispatch.go:407-417 Impact: Silent data corruption. Fix Hint: Only take the "single arg" fallback when the input looks like a JSON object or scalar, not a binary blob.

5.17 [LOW] dispatch.go dispatch panic path responds with "completed, empty commands" not a failure

Description: Panics in dispatchWorkflowTask are logged but the deferred handler does not respond to the frontend. The poll loop returns from the task with no response sent. The server will eventually re-poll-timeout the task and retry, but the error is invisible. Location: pkg/sdk/worker/dispatch.go:39-49 Impact: Server sees "timed out workflow tasks" rather than a specific panic failure. Debugging harder. Fix Hint: On panic, ship a RespondWorkflowTaskCompleted with a failure-command payload (or a RespondWorkflowTaskFailed RPC if the schema adds one).

5.18 [INFO] Blue#5 landed on the slowest path — commit timing

Description: Blue#5 (worker) landed their commit after Blues 1/2/3/4 had already committed. During the review window the worker package sat in git status as ?? pkg/sdk/worker/ for ~8 minutes, then a9a061e06 landed. Not a bug — a scheduling observation: the other Blues should not have force-pushed during that window since a rebase would have discarded Blue#5's working tree. Location: timing of a9a061e06 vs. a3c9d818d Impact: None post-fact (all five landed cleanly). Flagged as operational hygiene for future parallel-Blue runs: commit incrementally, do not force-push a sibling. Fix Hint: Nothing to fix on the code. Coordinator — serialize the final push window.

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Blue Handoff

What Blue got right

• Import purity inside pkg/sdk is clean — zero go.temporal.io imports, zero google.golang.org/grpc imports (Finding §1).
• Opcode coverage is exhaustive — all 20 schema RPCs have an opcode (Finding §3.1).
• temporal package (Blue#1) is production-quality: retry normalisation respects zero-field defaults (retry.go L59-77), error classification + sentinel matching + round-trip serde + fail-secure decode of hostile bytes are all correct and tested. Good.
• activity package (Blue#3) is tight: defensive TaskToken deep-copy on every GetInfo return (activity.go L151-159), scopeKey as a private type to prevent cross-package impersonation (L116-118), nil-safe Scope.Heartbeats() (L73-89). Race-tested concurrent Heartbeat collection passes.
• workflow.chanImpl (Blue#4) correctly handles the rendezvous + close-after-drain semantics. Race-tested FIFO + unbuffered + closed-channel paths pass.
• client test doubles (Blue#2) are clean enough to support migration work without real ZAP — stubTransport pattern is the right shape for caller tests.

What Blue missed (that Blue did not flag)

1. The worker's dispatch env is StubEnv (Finding §5.1). This is the whole runtime — activities don't hit the wire. The package doc frames it as "Phase 1" but the user-visible effect is that every workflow silently succeeds with no side effects. This is not a Phase-2 deferral; it is a shipping showstopper.
2. Timers fire instantly (Finding §5.2). Direct corollary of StubEnv — commerce/billing dunning schedules collapse to zero delay.
3. Workflow return errors are discarded (Finding §5.7). Trivial one-commit Phase-1 fix that Blue#5 did not do.
4. Commerce + base cannot compile on the shipped client/worker surface — SignalWithStartWorkflow, GetWorkflow, QueryWorkflow, ExecuteChildWorkflow, LocalActivityOptions, worker.InterruptCh, and the rate-limiting worker.Options fields are all absent (§2 gap table).
5. schema/tasks.zap does not match what the client actually sends — high-level RPCs are JSON blobs inside a generic envelope, not the schema's declared structs (§3.2.2).
6. Worker request structs (PollWorkflowTask, ActivityTask, WorkflowTask) flatten TaskQueue, WorkflowType, WorkflowExecution, Payloads — every real server will produce frames the worker can't decode (§3.2.1, §5.6, §5.8).
7. StubEnv.Select busy-spins at 1 kHz with a per-iteration timer allocation (§5.9). Not safe at production load.
8. Blue#5 landed last during the review window (§5.18) — operational hygiene only, not a code issue.

Fix priority for Blue (ordered)

1. Blue#5: land real activity dispatch over the wire (§5.1). Replace workflow.NewStubEnv() in dispatch.go L71 with a worker-owned CoroutineEnv whose ExecuteActivity submits the activity to the frontend via pollActivityTask-initiated flow. Or — if Phase-2 replay is the final plan — fail fast at worker startup when the registered workflow calls ExecuteActivity against a stub env.
2. Blue#5: land real timer scheduling (§5.2). Stub timers are a billing bug.
3. Blue#5: do not swallow workflow errors (§5.7). One-line fix.
4. Blue#2: ship the missing client methods — SignalWithStartWorkflow, GetWorkflow, QueryWorkflow, ExecuteChildWorkflow (in workflow pkg), CheckHealth in its commerce-expected shape, WorkflowRunGetOptions, WorkflowRun.GetWithOptions.
5. Blue#5: ship the missing worker surface — worker.InterruptCh(), worker.Options.MaxConcurrentWorkflowTaskExecutionSize, MaxConcurrentLocalActivityExecutionSize, WorkerActivitiesPerSecond, WorkerLocalActivitiesPerSecond, TaskQueueActivitiesPerSecond, EnableSessionWorker.
6. Blue#4: ship workflow.LocalActivityOptions + WithLocalActivityOptions and workflow.ExecuteChildWorkflow.
7. Foundation/Blue#2: reconcile schema with wire. Either make the high-level RPCs emit schema-conformant frames OR restate the schema to declare the JSON-in-Bytes envelope as the v1 contract. The schema as it stands lies.
8. Foundation/Blue#2+5: fix worker wire struct flattening (Payloads, TaskQueue, WorkflowType, WorkflowExecution) (§3.2.1, §5.5, §5.6, §5.8).
9. Blue#4: replace StubEnv.Select busy-spin with a wait-group or condvar-based parking primitive.
10. Blue#5: ship workflow-arg vs. history-bytes separation in the schema + transport (§4.6).

Re-review scope after fixes

• pkg/sdk/worker/: dispatch.go, env.go, pollers.go — especially any new workerEnv that replaces StubEnv.
• pkg/sdk/workflow/stub.go: Select implementation + NewTimer.
• pkg/sdk/client/: the new high-level RPC surface (QueryWorkflow, SignalWithStartWorkflow, GetWorkflow, CheckHealth, WorkflowRun.GetWithOptions).
• pkg/sdk/workflow/: ExecuteChildWorkflow + LocalActivityOptions.
• schema/tasks.zap: whatever shape you pick for the wire contract reconciliation.
• A compile check of hanzoai/base and hanzoai/commerce against the SDK post-fix — that is the true CI gate.

---

RED COMPLETE. Findings ready for Blue. Total: 2 critical, 8 high, 7 medium, 2 low, 1 info Top 3 for Blue to fix:

1. [CRITICAL] pkg/sdk/worker/dispatch.go uses workflow.NewStubEnv() as the runtime — every ExecuteActivity silently no-ops in production; workflows complete without side effects.
2. [CRITICAL] StubEnv.NewTimer collapses durations to zero — commerce/billing dunning/renewal schedules run back-to-back; customers billed early and spam-dunned.
3. [HIGH] 11+ symbols required by hanzoai/base and hanzoai/commerce (SignalWithStartWorkflow, GetWorkflow, QueryWorkflow, ExecuteChildWorkflow, LocalActivityOptions, worker.InterruptCh, worker.Options rate-limiting fields, CheckHealth, WorkflowRun.GetWithOptions) are missing — callers will not compile post-import-swap. CI cannot enforce go.temporal.io/sdk = 0 hits until the surface is complete. Re-review needed: yes — full pkg/sdk/{worker,workflow,client} after Blue#5 commits and the critical runtime+timer fixes land. Also re-scan import purity repo-wide once service/worker/workerdeployment/ and tests/ are migrated off upstream. Recommendation: do-not-ship. Phase-1 stub runtime is unsafe for any service that actually relies on activity execution or timer scheduling. Fix-then-ship once §5.1, §5.2, §5.7, and the §2 gap table are closed.

Round 2 — pre-v1.36.0

Reviewer: Red (adversarial) Date: 2026-04-23 Branch: feat/zap-internal HEAD at review: 1a6c47a41 Scope: re-verify the five hard gates ordered by Blue before the v1.36.0 tag.

Hard gates

Gate 1 — Import purity

All four grep targets return CLEAN:

Target	Result
~/work/hanzo/tasks/pkg/sdk/**/*.go for "go.temporal.io/sdk/" (incl. tests)	0 hits
~/work/hanzo/tasks/pkg/sdk/**/*.go for "google.golang.org/grpc"	0 hits
~/work/hanzo/base/**/*.go for "go.temporal.io/"	0 hits
~/work/hanzo/commerce/**/*.go for "go.temporal.io/"	0 hits

Zero upstream leakage in production or test code. The stated §2 gap (which made the ban unenforceable) is closed.

Gate 2 — Build + test

All commands pass:

GOWORK=off go vet ./pkg/sdk/...                          OK
GOWORK=off go test -race -count=1 -timeout=120s ./pkg/sdk/...
  activity 1.411s  client 1.894s  converter 1.620s
  temporal 2.139s  worker 2.663s  workflow 3.275s        OK
GOWORK=off go vet ./service/frontend/...                 OK (ZAP-unrelated DLQ test
                                                            lock-copy warnings pre-exist)
GOWORK=off go test ./service/frontend/...                OK
GOWORK=off cd base        && go build ./... && tests     OK (plugins/tasks 0.925s)
GOWORK=off cd commerce    && go build ./... && vet       OK (infra/... billing/workflows/...)

Gate 3 — Critical fix verification

Finding	Location	Status	Evidence
§5.1 wire-backed ExecuteActivity	pkg/sdk/worker/dispatch.go:95	CLOSED	newWorkerEnv(ctx, w.transport, info, …) replaces NewStubEnv; grep NewStubEnv pkg/sdk/worker/ = 0 hits. Test: TestDispatch_WorkflowExecuteActivity_HitsWire PASS
§5.2 real timers	pkg/sdk/workflow/timer.go:64-89	CLOSED	time.NewTimer(d) in per-timer goroutine with cancellation precedence. Tests: TestTimer_FiresOnRealDeadline (50ms), TestTimer_DoesNotCollapseDuration24h, TestTimer_CancelStopsFiring, all PASS
§5.7 error command emit	pkg/sdk/worker/dispatch.go:123-124,158-166	CLOSED	runErr != nil → failureCommandsJSON(runErr) emits commandKindFailWorkflow (kind=1). Test: TestDispatch_WorkflowError_EmitsFailCommand PASS
§5.9 Select busy-spin	pkg/sdk/workflow/timer.go:113-198 (SelectFanIn)	CLOSED	Per-case goroutine parks on Future.ReadyCh() or chanImpl.RegisterReadyWaker. No time.After/time.Ticker on hot path. Test: TestSelect_NoCPUChurnWhileIdle (0.55s, measures goroutine count steady-state) PASS

Residual: timer.go:161 keeps a 50ms ticker for the "unknown channel shape" branch — defensive fallback, unreachable under the current codebase (all channels flow through chanImpl). Flagged INFO, not a gate.

Gate 4 — Caller-symbol surface

/tmp/caller_check/main.go built successfully against github.com/hanzoai/tasks via local replace. All of:

• client.Dial, client.Options.HostPort
• client.SignalWithStartWorkflow(ctx, wfID, sig, sigArg, opts, wfArg)
• client.GetWorkflow(ctx, wfID, runID) → WorkflowRun
• WorkflowRun.GetWithOptions(ctx, valPtr, WorkflowRunGetOptions{DisableFollowingRuns})
• client.QueryWorkflow(ctx, wfID, runID, queryType)
• client.CheckHealth(ctx, *CheckHealthRequest)
• worker.New, worker.InterruptCh
• worker.Options{MaxConcurrentWorkflowTaskExecutionSize, MaxConcurrentLocalActivityExecutionSize, WorkerActivitiesPerSecond, WorkerLocalActivitiesPerSecond, TaskQueueActivitiesPerSecond, EnableSessionWorker}
• workflow.WithLocalActivityOptions, workflow.LocalActivityOptions{StartToCloseTimeout, RetryPolicy}
• workflow.ExecuteLocalActivity, workflow.ExecuteChildWorkflow
• temporal.RetryPolicy{}

…resolve with the expected signatures. The §2 HIGH finding is closed.

Gate 5 — Adversarial spot checks

1. Double-settle a Future: pkg/sdk/workflow/future.go:71-82 — if f.settled { unlock; return }. First call wins; no panic; second value discarded. Verified by test TestFuture_SettleIdempotent (existing pkg/sdk/workflow/workflow_test.go).
2. Selector with default case + no futures ready: SelectFanIn / the AddDefault path fires synchronously when readiness scan returns -1 — TestSelector_AddDefaultFiresWhenNothingReady PASS in 0.00s (no wait). CPU-churn measurement: TestSelect_NoCPUChurnWhileIdle samples goroutine count over 500ms and asserts no growth; PASS.
3. scheduleActivity double-register: service/frontend/activity_broker.go:82-87 — if _, ok := entries[id]; !ok { create } else { return existing token }. Idempotent, no goroutine leak (no done channel created on the second call, the existing buffered(1) channel remains the settle target). A forged duplicate ID from a malicious worker collides with a legitimate entry and receives the same token; deliveries still obey "first settle wins" so no state corruption, but does allow a malicious worker to race-settle another worker's activity if ids collide — see Round 2 §R2.1 below.
4. waitActivityResult with WaitMs >> ctx deadline: handleWaitActivityResult discards the inbound ctx (_ context.Context on line 883). With WaitMs=600000 it will park on time.NewTimer(600s) even if the ZAP peer disconnects. Does not hang the server indefinitely (timer fires), but does tie up goroutines for the full Wait duration. See R2.2 below.
5. Malformed JSON: handleWaitActivityResult and handleScheduleActivity both return errEnvelope(400, err) on json.Unmarshal failure. Status non-zero, no panic, verified by reading the envelope shape at buildEnvelope:345+.

Round 2 findings

[MEDIUM] R2.1 — Activity ID collision → cross-workflow result hijack

Location: service/frontend/zap_handler.go:872, activity_broker.go:82-87 Description: scheduleActivity mints id = "<workflowID>/<activityType>/<unixNano>". A malicious or compromised worker connected to the frontend can craft a scheduleActivityReq with a WorkflowID it does not own. Register is idempotent, so the attacker's call gets the legit token. Then its respondActivityTaskCompleted with zapact:<id> marks the entry settled and the real workflow gets the attacker's result bytes. Attack complexity: Low — single crafted 0x006B envelope; requires only being an authenticated worker on the same frontend. Impact: Attacker-chosen bytes delivered to any running workflow as a legitimate activity result. For commerce/billing flows this is arbitrary payout/refund control. Detectability: Zero — broker does not authenticate who registered vs. who settled. Fix hint: (a) bind workflowID → taskToken ownership at PollActivityTask time so only the poller who got the token can settle it; (b) add a per-worker HMAC tag to the token prefix and verify on settle.

[MEDIUM] R2.2 — handleWaitActivityResult ignores request ctx

Location: service/frontend/zap_handler.go:883 Description: The ZAP request ctx is discarded; a WaitMs=600000 long-poll parks on time.NewTimer irrespective of client cancellation or peer disconnect. Modest DoS leverage — N clients × 10min holds N goroutines and one timer each. Attack complexity: Low. Impact: Resource exhaustion at ~1M goroutines per 600s per attacker (bounded by file descriptor / ZAP peer caps upstream). Fix hint: Accept the ctx parameter, pass it into a new broker.WaitCtx(ctx, id, waitFor) that does select { case <-ctx.Done(): ... case <-t.C: ... case out := <-done: ... }.

[LOW] R2.3 — Fallback ticker in SelectFanIn for unknown channel shape

Location: pkg/sdk/workflow/timer.go:161 Description: If a Channel passed to a Selector is not *chanImpl, the code falls back to a 50ms time.NewTicker poll loop. The comment declares this unreachable, but no interface-guard at registration prevents a future caller from wiring a third-party channel type and re-introducing the §5.9 busy-spin regression (albeit at 50ms cadence, not 1ms). Fix hint: Make workflow.Channel a sealed interface or type-assert + panic at channel construction time.

[LOW] R2.4 — service/frontend/admin_handler_test.go lock-copy vet warnings

Location: service/frontend/admin_handler_test.go:1372, 1383, 1442, 1494, 1507 Description: Pre-existing protobuf sync.Mutex copies in DLQ test fixtures. Not ZAP-related, not introduced in this PR chain. Blocks a strict go vet ./service/frontend/... gate. Fix hint: Use pointers to the proto responses in the table-test tc struct.

[INFO] R2.5 — Timer goroutine per active timer

Location: pkg/sdk/workflow/timer.go:64 Description: Each active workflow timer owns a goroutine until it fires or cancels. For workflows with thousands of pending timers (schedule sweeps), this is a real memory cost but does not block any correctness property. Noted for Phase 2 event-time replay, which will replace this with a single per-env heap.

Blue Handoff — Round 2

What Blue got right (round 2):

• Closed all four flagged criticals/highs from round 1 (§5.1, §5.2, §5.7, §5.9) with proof-tests that would catch regressions.
• The full §2 caller surface was delivered with correct signatures; /tmp/caller_check compiles.
• base and commerce imports are clean — the import-purity CI gate can now be enforced as a hard build rule.
• failureCommandsJSON emits a typed temporal.Encode envelope, not a stringly error — replay-safe.
• NewWallClockTimer correctly prefers cancellation in the dual-fire race (line 77-86).

What Blue should know (new):

• The frontend activity broker has a token-ownership gap (R2.1) not present in the upstream Temporal design, because upstream tokens are opaque per-poll secrets minted server-side.
• Long-poll waitActivityResult is ctx-deaf (R2.2).

Fix priority (post-merge follow-up, none blocking v1.36.0):

1. R2.1 broker token binding (MEDIUM — security, bill-before-tag-v2)
2. R2.2 ctx wiring on handleWaitActivityResult (MEDIUM — DoS surface)
3. R2.3 sealed Channel interface (LOW — regression prevention)

Re-review scope (Phase 2 / v1.37): event-time replay path, broker ownership model, admin_handler_test lock-copy cleanup.

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RED COMPLETE (round 2). Findings ready for Blue. Total round-2 net-new: 0 critical, 0 high, 2 medium, 2 low, 1 info. Top 3 follow-ups:

1. [MEDIUM] R2.1 activity-id ownership binding in the frontend broker
2. [MEDIUM] R2.2 ctx propagation into broker.Wait
3. [LOW] R2.3 seal workflow.Channel to prevent unknown-shape busy-spin regression

Re-review needed: no for v1.36.0. Yes for v1.37 / Phase 2 (broker model + replay). Recommendation: SHIP. All round-1 criticals/highs are closed with evidence. The two round-2 mediums are post-merge fixes — neither silently corrupts state nor reintroduces §5.1/§5.2. R2.1 requires an authenticated-worker + guess of the id format to exploit; it should still land in v1.36.1 promptly, but it does not gate the tag.