Durability & Scheduling Runtime Audit (2026)

Durability & Scheduling Runtime Audit (2026)

Conducted: 2026-05-01
Scope: @scheduled, @durable, DurabilityKind, actor/workflow/activity keywords, vox-orchestrator

Verdict Summary

Feature	Status	Risk
@scheduled("1h")	Parses only	High — users may expect a cron loop
@durable decorator	Parses only	High — durability semantics not implemented
DurabilityKind::Workflow	Parses only	High — no journal, saga log, or replay
DurabilityKind::Activity	Parses only	High — no retry/checkpoint wrapper
DurabilityKind::Actor	Partially wired	Medium — handler splitting works; mailbox dispatch doesn’t connect to generated code
actor/workflow/activity keywords	Syntax unified	Medium — compile identically to fn
vox-orchestrator	Active, orthogonal	Low — operates at agent-session level, not function durability

No passing integration tests exist for any scheduler invocation, journal replay, or actor mailbox integration.

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Detailed Findings

@scheduled("1h") — Parses Only

• AST: ScheduledDecl { interval: String } in crates/vox-compiler/src/ast/decl/fundecl.rs:176-182.
• HIR lowering: hir/lower/mod.rs:322-326 sets HirFn { schedule_interval: Some(interval) }. The string is preserved.
• Codegen: No reference to schedule_interval anywhere in crates/vox-compiler/src/codegen_rust/. Emits a plain async fn.
• Runtime: No scheduler loop, no tokio::time::interval, no cron wiring anywhere in crates/vox-actor-runtime/.
• Golden: examples/golden/scheduled_tick.vox compiles and lowers (counted in golden_vox_examples_test.rs:97), but no invocation test exists.

Conclusion: The interval metadata travels from parse to HIR and stops. It is dead code beyond the HIR.

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@durable / DurabilityKind — Parses, Lowers, No Engine

• Variants (crates/vox-compiler/src/hir/nodes/durability.rs:13-23):
  • Workflow — “survives crashes; calls to activity functions replayed via journal”
  • Activity — “retried on failure, never replayed mid-execution”
  • Actor — “stateful entity with message handlers — isolated memory, serialised handler dispatch”
• HIR attachment: HirFn { durability: Option<DurabilityKind> } set at hir/lower/mod.rs:297, 302, 307.
• Codegen: The durability field is never read in codegen_rust/. All three variants emit identical plain async fn Rust code.
• Runtime projection: RuntimeProjectionModule in runtime_projection.rs:31-45 captures DB planning but ignores durability metadata entirely.

Conclusion: The HIR accurately describes what these features should do. Nothing downstream implements those semantics.

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actor / workflow / activity Keywords — Phase 2 Syntax Unification

Per AGENTS.md §Grammar Unification: “They lower to HirFn { durability: Some(DurabilityKind::_) } — no separate HIR node types.”

• Actor: Handler splitting into per-handler HirFn entries works at HIR level (hir/lower/mod.rs:305-314). vox-actor-runtime/src/scheduler.rs has actor mailbox/spawn/dispatch logic, but the generated Rust functions do not connect to it — the wiring is manual.
• Workflow / Activity: Parsed, lowered with correct DurabilityKind. Generated Rust is a plain async fn. examples/golden/checkout_workflow.vox does not use the workflow/activity keywords — it uses plain fn.
• No integration tests for any of the three execution models.

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vox-orchestrator — Active but Orthogonal

The crate (~200 .rs files) handles model selection, context injection, A2A message bus, remote dispatch, and agent session management. It is the canonical replacement for the retired vox-dei crate.

It has zero references to DurabilityKind, schedule_interval, or workflow journals. It operates at the AI agent session level, not at the function-durability level. It is unrelated to the scheduling and durability gaps above.

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Consequences for Phase 4

The interop plan’s Phase 4 requires an honest resolution of these stubs before documenting or shipping them. The options, per the plan:

1. Fix the wiring — implement the scheduler loop for @scheduled, a retry wrapper for @durable Activity, and a journal engine for @durable Workflow. This is substantial work; each is roughly a separate sub-project.
2. Remove the decorators from the grammar (with a deprecation cycle) until each can be re-introduced with a real implementation.

Recommended path: Remove @scheduled and @durable from the public grammar in the next release, retaining them as internal/reserved identifiers. Re-introduce each when its runtime is ready. The actor keyword can stay since the handler-splitting HIR work is real; document the current limitation (no auto-mailbox integration) explicitly.

The HIR DurabilityKind variants and schedule_interval field are worth keeping as internal compiler metadata — they will be needed when the runtime implementations land.

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Files Referenced

File	Relevance
crates/vox-compiler/src/ast/decl/fundecl.rs:176-182	ScheduledDecl AST node
crates/vox-compiler/src/hir/nodes/durability.rs:13-23	DurabilityKind variants
crates/vox-compiler/src/hir/lower/mod.rs:297-326	Lowering for all three kinds
crates/vox-compiler/src/codegen_rust/	Absent: no durability codegen
crates/vox-actor-runtime/src/scheduler.rs	Actor mailbox (partial); no cron loop
examples/golden/scheduled_tick.vox	Parses/lowers; no runtime test
examples/golden/counter_actor.vox	Notes: “persistent state inside actor blocks not parsed yet”