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feat: declared workflow inputs #27

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Merged
senamakel merged 5 commits into from
Jul 31, 2026
Merged

feat: declared workflow inputs #27

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7e28bdd
feat(model): declare typed workflow inputs
senamakel Jul 31, 2026
d26e4c8
feat(engine): resolve declared inputs and expose them to expressions
senamakel Jul 31, 2026
f6e2f34
feat(authoring): expose declared inputs to graph ops, catalog and docs
senamakel Jul 31, 2026
df9b936
docs(expr): warn that a jq program must write .inputs.<name>
senamakel Jul 31, 2026
548dbe3
feat(sub_workflow): forward declared inputs per item as well
senamakel Jul 31, 2026
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20 changes: 19 additions & 1 deletion src/catalog.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -206,6 +206,12 @@ pub fn contract_for(kind: &str) -> Option<NodeKindContract> {
notes: vec![
"Exactly ONE trigger node per graph — zero or multiple is a hard reject."
.to_string(),
"A workflow's typed PARAMETERS are NOT declared here. They live in the graph's \
top-level `inputs` array (name/type/required/default/description), are validated \
before the run starts, and are read from any node as \"=inputs.<name>\". The \
trigger payload — free-form, whatever fired the run — stays at \
\"=run.trigger.<path>\"."
.to_string(),
],
},
"agent" => NodeKindContract {
Expand Down Expand Up @@ -458,15 +464,27 @@ pub fn contract_for(kind: &str) -> Option<NodeKindContract> {
"string",
"The id of a saved workflow to run as the child. Provide this OR workflow.",
),
ConfigField::optional(
"inputs",
"object",
"Values for the child's declared workflow inputs, by name. Each value is \
resolved against THIS node's scope, so a parent can forward its own inputs \
(\"=inputs.repo\") or an upstream node's output. Under \
execution=\"per_item\" the scope is the current element, so each child in a \
fan-out gets values from its own item (\"=item.name\").",
),
],
ports: PortSpec::linear(),
example: json!({
"id": "sub", "kind": "sub_workflow", "name": "Enrich",
"config": { "workflow_id": "flow-123" }
"config": { "workflow_id": "flow-123", "inputs": { "repo": "=inputs.repo" } }
}),
notes: vec![
"Exactly one of workflow / workflow_id — having both or neither is a hard reject."
.to_string(),
"The child validates config.inputs against its OWN declarations, so omitting a \
required child input fails before the child executes anything."
.to_string(),
],
},
"memory" => NodeKindContract {
Expand Down
177 changes: 125 additions & 52 deletions src/engine.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -4,8 +4,11 @@
//! [`WorkflowGraph`](crate::model::WorkflowGraph) — capturing the run's host
//! [`Capabilities`] in each node handler — then drives it and returns the final
//! run state. State is a [`serde_json::Value`] laid out as
//! `{ "run": { "trigger": … }, "nodes": { "<id>": { "items": [ … ] } } }`;
//! a merge reducer folds each node's item output into that map.
//! `{ "run": { "trigger": …, "inputs": { … } }, "nodes": { "<id>": { "items": [ … ] } } }`;
//! a merge reducer folds each node's item output into that map. `run.trigger` is
//! the free-form payload that fired the run; `run.inputs` is the workflow's
//! resolved declared inputs (see [`RunInput`]), which node config addresses as
//! `=inputs.<name>`.
//!
//! Lowering covers the **linear** path (one successor per node), **conditional
//! branching** (successors on distinct ports), **parallel fan-out** (several
Expand Down Expand Up @@ -98,6 +101,67 @@ impl CancellationToken {
}
}

/// What a caller hands a run: the trigger payload plus values for the
/// workflow's declared inputs.
///
/// The two are deliberately separate channels. The **trigger payload** is
/// whatever fired the run — a webhook body, a chat message, an empty object for
/// a manual start — and is free-form by nature. **Inputs** are the workflow's
/// declared, typed parameters (see [`crate::model::WorkflowInput`]); they are
/// validated against the graph's declarations before anything executes.
///
/// Every entry point takes `impl Into<RunInput>`, and [`Value`] converts, so a
/// caller with no declared inputs passes a bare payload exactly as before:
///
/// ```
/// use tinyflows::engine::RunInput;
/// use serde_json::json;
///
/// // Trigger payload only — the historical form.
/// let plain: RunInput = json!({"from": "webhook"}).into();
/// assert!(plain.inputs.is_empty());
///
/// // With declared input values.
/// let mut values = serde_json::Map::new();
/// values.insert("repo".into(), json!("acme/api"));
/// let parameterized = RunInput::new(json!({})).with_inputs(values);
/// assert_eq!(parameterized.inputs["repo"], json!("acme/api"));
/// ```
#[derive(Debug, Clone, Default)]
pub struct RunInput {
/// The trigger payload, seeded as the trigger node's item and `run.trigger`.
pub trigger: Value,
/// Caller-supplied values for the workflow's declared inputs, by name.
/// Validated by [`crate::model::resolve_inputs`] before the run starts.
pub inputs: Map<String, Value>,
}

impl RunInput {
/// A run carrying only a trigger payload and no declared-input values.
#[must_use]
pub fn new(trigger: Value) -> Self {
Self {
trigger,
inputs: Map::new(),
}
}

/// Attaches values for the workflow's declared inputs.
#[must_use]
pub fn with_inputs(mut self, inputs: Map<String, Value>) -> Self {
self.inputs = inputs;
self
}
}

impl From<Value> for RunInput {
/// Treats a bare JSON value as a trigger payload with no declared inputs —
/// what every caller meant before inputs existed.
fn from(trigger: Value) -> Self {
Self::new(trigger)
}
}

/// The result of a completed workflow run.
#[derive(Debug, Clone)]
pub struct RunOutcome {
Expand Down Expand Up @@ -447,7 +511,7 @@ fn error_item(node_id: &str, e: &EngineError) -> Item {
/// not yet implemented surfaces its `Unimplemented` error here.
pub async fn run(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
capabilities: &Capabilities,
) -> Result<RunOutcome> {
run_with_observer(
Expand All @@ -470,7 +534,7 @@ pub async fn run(
/// Same as [`run`].
pub async fn run_with_observer(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
capabilities: &Capabilities,
observer: &Arc<dyn RunObserver>,
) -> Result<RunOutcome> {
Expand Down Expand Up @@ -509,7 +573,7 @@ pub async fn run_with_observer(
/// Same as [`run`].
pub async fn run_cancellable(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
capabilities: &Capabilities,
token: CancellationToken,
) -> Result<RunOutcome> {
Expand All @@ -524,7 +588,7 @@ pub async fn run_cancellable(
/// Same as [`run_cancellable`].
pub async fn run_cancellable_with_observer(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
capabilities: &Capabilities,
token: CancellationToken,
observer: &Arc<dyn RunObserver>,
Expand Down Expand Up @@ -570,7 +634,7 @@ pub const MAX_SUB_WORKFLOW_DEPTH: u64 = 8;
/// Same as [`run`].
pub(crate) async fn run_sub_workflow(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
capabilities: &Capabilities,
depth: u64,
) -> Result<RunOutcome> {
Expand Down Expand Up @@ -1316,7 +1380,7 @@ fn default_thread_id(workflow: &CompiledWorkflow) -> Result<String> {
#[allow(clippy::too_many_arguments)]
async fn build_and_run(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
capabilities: &Capabilities,
observer: &Arc<dyn RunObserver>,
checkpointer: Arc<dyn Checkpointer<Value>>,
Expand All @@ -1325,6 +1389,14 @@ async fn build_and_run(
run_meta_overlay: Option<Value>,
token: CancellationToken,
) -> Result<(CompiledGraph<Value, Value>, String, RunOutcome, GraphRunIds)> {
// Declared inputs are resolved FIRST — before the run id is minted, before
// the observer is told a run started, and before any graph is built. A
// caller that gets an `Input` error can therefore be certain nothing ran and
// nothing was observed, which is what lets a host reject a bad call without
// recording a phantom run.
let RunInput { trigger, inputs } = input.into();
let resolved_inputs = crate::model::resolve_inputs(&workflow.graph.inputs, &inputs)?;

// Process-local, monotonic run id — no time/random source.
let run_id = format!("run-{}", NEXT_RUN_ID.fetch_add(1, Ordering::Relaxed));
observer.on_run_start(&run_id);
Expand All @@ -1347,9 +1419,13 @@ async fn build_and_run(
token.clone(),
)?;

let seed_items = items_update(&trigger_id, &[Item::new(input.clone())], None)
let seed_items = items_update(&trigger_id, &[Item::new(trigger.clone())], None)
.map_err(|e| EngineError::Capability(e.to_string()))?;
let mut initial = json!({ "run": { "trigger": input } });
// `run.inputs` holds the resolved declared inputs — one entry per
// declaration, defaults already applied. `expr_scope_for` lifts it to the
// top-level `inputs` scope key, so node config addresses it as
// `=inputs.<name>` (and jq programs walking `run` still see it too).
let mut initial = json!({ "run": { "trigger": trigger, "inputs": resolved_inputs } });
merge(&mut initial, seed_items);
// Optional run-level metadata overlaid onto `run` before the run starts —
// e.g. the `sub_workflow_depth` counter a nested `sub_workflow` run threads
Expand Down Expand Up @@ -1441,15 +1517,33 @@ async fn build_and_run(
/// execution of the resumed run fails.
pub async fn resume(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
newly_approved: Vec<String>,
capabilities: &Capabilities,
) -> Result<RunOutcome> {
// Union `newly_approved` into `input["approvals"]`: start from any existing
// approvals array (ignoring non-string entries), then append each newly
// approved id that is not already present. Reading defensively — a missing or
// non-array `approvals` simply yields an empty starting set, never a panic.
let mut approvals: Vec<String> = input
run(
workflow,
merge_approvals(input, newly_approved),
capabilities,
)
.await
}

/// Unions `newly_approved` into the run input's `trigger["approvals"]`, leaving
/// the declared-input values untouched.
///
/// Reads defensively: a missing or non-array `approvals` yields an empty
/// starting set, and a non-object trigger (which carries no fields to preserve)
/// is replaced by a fresh object holding just the merged approvals. Declared
/// inputs ride along unchanged — a resume re-runs the *same* parameterized
/// workflow, so dropping them would silently change what it does.
fn merge_approvals(input: impl Into<RunInput>, newly_approved: Vec<String>) -> RunInput {
let RunInput {
mut trigger,
inputs,
} = input.into();

let mut approvals: Vec<String> = trigger
.get("approvals")
.and_then(Value::as_array)
.map(|existing| {
Expand All @@ -1466,16 +1560,13 @@ pub async fn resume(
}
}

let mut merged_input = input;
if let Value::Object(map) = &mut merged_input {
if let Value::Object(map) = &mut trigger {
map.insert("approvals".to_string(), json!(approvals));
} else {
// A non-object input carries no fields to preserve, so replace it with a
// fresh object holding just the merged approvals.
merged_input = json!({ "approvals": approvals });
trigger = json!({ "approvals": approvals });
}

run(workflow, merged_input, capabilities).await
RunInput { trigger, inputs }
}

/// Like [`resume`], but observes `token`: cancelling it winds the resumed run
Expand All @@ -1487,36 +1578,18 @@ pub async fn resume(
/// Same as [`resume`].
pub async fn resume_cancellable(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
newly_approved: Vec<String>,
capabilities: &Capabilities,
token: CancellationToken,
) -> Result<RunOutcome> {
let mut approvals: Vec<String> = input
.get("approvals")
.and_then(Value::as_array)
.map(|existing| {
existing
.iter()
.filter_map(Value::as_str)
.map(str::to_string)
.collect()
})
.unwrap_or_default();
for id in newly_approved {
if !approvals.contains(&id) {
approvals.push(id);
}
}

let mut merged_input = input;
if let Value::Object(map) = &mut merged_input {
map.insert("approvals".to_string(), json!(approvals));
} else {
merged_input = json!({ "approvals": approvals });
}

run_cancellable(workflow, merged_input, capabilities, token).await
run_cancellable(
workflow,
merge_approvals(input, newly_approved),
capabilities,
token,
)
.await
}

/// A live, resumable workflow run.
Expand Down Expand Up @@ -1601,7 +1674,7 @@ impl ResumableRun {
/// Same as [`run`].
pub async fn run_resumable(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
capabilities: &Capabilities,
) -> Result<ResumableRun> {
let observer = Arc::new(crate::observability::NoopObserver) as Arc<dyn RunObserver>;
Expand Down Expand Up @@ -1654,7 +1727,7 @@ pub async fn run_resumable(
/// execution (including any node executor error) fails.
pub async fn run_with_checkpointer(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
capabilities: &Capabilities,
checkpointer: Arc<dyn Checkpointer<Value>>,
thread_id: &str,
Expand Down Expand Up @@ -1740,7 +1813,7 @@ pub async fn resume_with_checkpointer(
/// Same as [`run_with_checkpointer`].
pub async fn run_with_checkpointer_journaled(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
capabilities: &Capabilities,
checkpointer: Arc<dyn Checkpointer<Value>>,
thread_id: &str,
Expand Down Expand Up @@ -1775,7 +1848,7 @@ pub async fn run_with_checkpointer_journaled(
/// Same as [`run_with_checkpointer_journaled`].
pub async fn run_with_checkpointer_journaled_observed(
workflow: &CompiledWorkflow,
input: Value,
input: impl Into<RunInput>,
capabilities: &Capabilities,
checkpointer: Arc<dyn Checkpointer<Value>>,
thread_id: &str,
Expand Down
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