What's New in v0.2

Sayiir v0.2 is backward-compatible. Existing v0.1 workflows continue to work without changes. New features are additive — adopt them incrementally.

New features

Loops with exit conditions

Iterative workflows are now a first-class primitive. A loop body runs repeatedly until it returns LoopResult.done(), with a configurable max-iterations safety net.

Flow.loop() (Python) / flow.loop() (Node.js) — add a loop step to the workflow
LoopResult.again(value) — continue iterating with value as the next input
LoopResult.done(value) — exit the loop, passing value to the next step
max_iterations (default: 10) — safety limit to prevent runaway loops
on_max policy — "fail" (default) raises an error, "exit_with_last" exits gracefully with the last value
Each iteration is durably checkpointed

See the Loops & Iteration guide for details.

Conditional branching

Route workflow execution based on data. A router task returns a string key, and the matching branch executes.

Flow.route() — add a routing step with declared keys
.branch(key, task) — define what runs for each key
.default_branch() / .defaultBranch() — optional fallback for unmatched keys
Keys are validated at build time for exhaustiveness
Branch output is wrapped in a BranchEnvelope containing the matched key and value

See the Durable Workflows guide for branching examples.

Workflow composition

Build modular pipelines by inlining child workflows as sub-steps.

Flow.then_flow(child) (Python) / flow.thenFlow(child) (Node.js) — inline a child workflow’s task graph
Task registries from parent and child merge automatically
The child’s input type must match the previous step’s output type

See the Composing Workflows guide for details.

Task execution context

Tasks can access read-only metadata about the current execution at runtime.

get_task_context() (Python) / getTaskContext() (Node.js) — returns context or None/undefined outside a running task
Available properties: workflow_id, instance_id, task_id, metadata, workflow_metadata
Context is read-only

New exports

Python — new imports from sayiir: LoopResult, OnMax, get_task_context, TaskExecutionContext

Node.js — new exports from "sayiir": LoopResult, getTaskContext, and types LoopOptions, BranchEnvelope, TaskExecutionContext

API changes

Rust: `workflow!` macro improvements

The workflow! macro now supports loops, child workflows, and the infallible builder pattern:

loop task_name N — loop a task up to N iterations (fails on max by default)
loop task_name N exit_with_last — loop with graceful exit on max iterations
flow expr — inline a child workflow, merging its task registry automatically

Rust: infallible builder methods

In v0.1, most builder methods (then_registered, branch_registered, join_registered, route_registered) returned Result<..., BuildError>, requiring ? or .unwrap() at every step.

In v0.2, all builder methods are infallible. Errors are accumulated internally and reported together when .build() is called. This means:

Chaining builder calls no longer requires ? after each step
.build() returns Result<Workflow, BuildErrors> — a single point where all validation errors surface
BuildErrors (plural) replaces BuildError, collecting every issue found during construction

Rust crate versions

Update your Cargo.toml dependencies from 0.1 to 0.2:

Crate	Version
`sayiir-runtime`	`0.2`
`sayiir-persistence`	`0.2`
`sayiir-postgres`	`0.2`

Breaking changes

Rust only: Builder methods no longer return Result. If your code used ? on intermediate builder calls, remove them — errors now surface at .build(). The error type changed from BuildError to BuildErrors.
Python / Node.js: No breaking changes. All v0.1 APIs work unchanged.