Generation, checks, review, local repair, and delivery
The policy implementation follows.
ts
export function defineAnswerFlow<Data, Value, App = undefined>(
definition: AnswerFlowDefinition<Data, Value, App>,
) {
const { maxItems, maxRepairs } = definition,
reviewPolicy = definition.reviewPolicy ?? 'optional';
if (
!Number.isSafeInteger(maxItems) ||
maxItems < 1 ||
!Number.isSafeInteger(maxRepairs) ||
maxRepairs < 0 ||
!['optional', 'required', 'off'].includes(reviewPolicy)
)
throw new TypeError('Invalid answer flow limits or policy');
for (const handler of [
definition.generate,
definition.check,
definition.fallback,
definition.canInvoke,
]) {
if (typeof handler !== 'function') throw new TypeError('Missing answer flow handler');
}
if (definition.review !== undefined && typeof definition.review !== 'function')
throw new TypeError('Invalid answer review handler');
const generateValues = definition.generate.bind(definition),
checkValue = definition.check.bind(definition),
reviewValues = definition.review?.bind(definition),
fallbackValue = definition.fallback.bind(definition),
canInvoke = definition.canInvoke.bind(definition),
observer = definition.observe?.bind(definition);
const allowed = (context: OperationContext<App>) => {
context.signal.throwIfAborted();
const value = booleanResult(
canInvoke(context),
'Answer budget checks must return boolean synchronously',
);
context.signal.throwIfAborted();
return value;
};
const issues = (cell: Cell<Data, Value>): AnswerIssue[] => {
const result = [
...cell.local.issues,
...(cell.review.status === 'failed' ? cell.review.issues : []),
];
if (!cell.hasValue || cell.local.status !== 'passed')
result.push({
code: !cell.hasValue ? 'ANSWER_MISSING' : 'ANSWER_LOCAL_CHECK',
message: 'No locally accepted value',
});
if ((reviewPolicy === 'required' || cell.knownReviewFailure) && cell.review.status !== 'passed')
result.push({ code: 'ANSWER_REVIEW_REQUIRED', message: 'Required review is unresolved' });
return result;
};
function observe(
stageId: string,
cells: Cell<Data, Value>[],
context: OperationContext<App>,
): void {
if (!observer) return;
const results = cells.map((cell) => ({
item: cell.item,
value: cell.value,
status: 'blocked' as const,
issues: issues(cell),
checks: { local: cell.local, review: cell.review },
}));
observeSafely((input) => observer(input, context), { stageId, results });
}
async function generate(
cells: Cell<Data, Value>[],
repair: boolean,
context: OperationContext<App>,
): Promise<void> {
context.signal.throwIfAborted();
if (!cells.length || !allowed(context)) return;
const previous = new Map(
cells.flatMap((cell) =>
!cell.hasValue ? [] : [[cell.item.id, cell.value as Value] as const],
),
);
const repairs = repair ? new Map(cells.map((cell) => [cell.item.id, issues(cell)])) : undefined;
for (const cell of cells) cell.generated = false;
let values: ReadonlyMap<string, Value>;
try {
values = await awaitWithSignal(
generateValues({ items: cells.map((cell) => cell.item), repairs, previous }, context),
context.signal,
);
} catch {
context.signal.throwIfAborted();
observe(repair ? 'repair-unavailable' : 'generation-unavailable', cells, context);
return;
}
context.signal.throwIfAborted();
if (
!values ||
typeof values.get !== 'function' ||
typeof values.keys !== 'function' ||
[...values.keys()].some((id) => !cells.some((cell) => cell.item.id === id))
)
throw new TypeError('Invalid generated answer ownership');
for (const cell of cells) {
cell.hasValue = values.has(cell.item.id);
cell.value = values.get(cell.item.id);
cell.generated = cell.hasValue;
cell.local = { status: 'not-run', issues: [] };
cell.review = { status: 'not-run', issues: [] };
}
}
function check(cells: Cell<Data, Value>[], context: OperationContext<App>): void {
for (const cell of cells) {
context.signal.throwIfAborted();
if (!cell.hasValue) {
cell.local = unavailable();
continue;
}
const result = snapshotAnswerCheck(
synchronous(
checkValue({ item: cell.item, value: cell.value as Value }, context),
'Answer checkers must be synchronous',
),
);
context.signal.throwIfAborted();
if (Object.hasOwn(result, 'value')) cell.value = result.value;
cell.local = result;
}
}
async function review(cells: Cell<Data, Value>[], context: OperationContext<App>): Promise<void> {
context.signal.throwIfAborted();
const selected = cells.filter((cell) => cell.local.status === 'passed' && cell.hasValue);
if (!selected.length) return;
if (reviewPolicy === 'off') {
for (const cell of selected) cell.review = { status: 'not-run', issues: [] };
return;
}
if (!reviewValues || !allowed(context)) {
for (const cell of selected) cell.review = unavailable();
return;
}
let checks: ReadonlyMap<string, AnswerCheck<Value>>;
try {
checks = await awaitWithSignal(
reviewValues(
{ items: selected.map((cell) => ({ item: cell.item, value: cell.value! })) },
context,
),
context.signal,
);
} catch {
context.signal.throwIfAborted();
for (const cell of selected) cell.review = unavailable();
return;
}
context.signal.throwIfAborted();
if (
!checks ||
typeof checks.get !== 'function' ||
typeof checks.keys !== 'function' ||
[...checks.keys()].some((id) => !selected.some((cell) => cell.item.id === id))
)
throw new TypeError('Invalid answer review ownership');
const checked = new Map([...checks].map(([id, result]) => [id, snapshotAnswerCheck(result)]));
for (const cell of selected) {
cell.review = checked.get(cell.item.id) ?? unavailable();
if (cell.review.status === 'failed') cell.knownReviewFailure = true;
if (cell.review.status === 'passed') cell.knownReviewFailure = false;
}
}
const workflow = defineWorkflow<State<Data, Value>, AnswerResult<Data, Value>[], App>({
id: 'answer-flow',
entryNodeId: 'generate',
nodes: [
{
id: 'generate',
description: 'Generate available items',
startsRound: true,
run: async (state, context) => {
await generate(
state.cells.filter((cell) => cell.item.sourceStatus === 'ready'),
false,
context,
);
},
routes: [{ id: 'to-validate', targetNodeId: 'validate' }],
},
{
id: 'validate',
description: 'Check values and retain sanitized output',
run: (state, context) => {
check(
state.cells.filter((cell) => cell.item.sourceStatus === 'ready'),
context,
);
},
routes: [{ id: 'to-review', targetNodeId: 'review' }],
},
{
id: 'review',
description: 'Review locally accepted values',
run: async (state, context) => {
await review(
state.cells.filter((cell) => cell.item.sourceStatus === 'ready'),
context,
);
observe('checked', state.cells, context);
},
routes: [{ id: 'to-select-repair', targetNodeId: 'select-repair' }],
},
{
id: 'select-repair',
description: 'Select only failed available items',
run: (state) => ({
pending: state.cells.filter(
(cell) => cell.item.sourceStatus === 'ready' && issues(cell).length > 0,
),
}),
routes: [
{
id: 'to-repair',
conditionId: '{nid}.{rid}',
when: (state, context) =>
state.pending.length > 0 && state.repairBudget.available && allowed(context),
targetNodeId: 'repair',
},
{ id: 'to-deliver', targetNodeId: 'deliver' },
],
},
{
id: 'repair',
description: 'Use one bounded repair attempt',
startsRound: true,
run: async (state, context) => {
if (!state.repairBudget.take()) throw new TypeError('Answer repair budget exhausted');
await generate(state.pending, true, context);
},
routes: [{ id: 'to-recheck', targetNodeId: 'recheck' }],
},
{
id: 'recheck',
description: 'Recheck only repaired items',
run: async (state, context) => {
const generated = state.pending.filter((cell) => cell.generated);
check(generated, context);
await review(generated, context);
observe('repaired', state.pending, context);
},
routes: [{ id: 'to-select-repair', targetNodeId: 'select-repair' }],
},
{
id: 'deliver',
description: 'Return accepted values or explicit fallback states',
run: (state, context) => ({
result: state.cells.map((cell) => {
context.signal.throwIfAborted();
const errors = issues(cell);
if (cell.item.sourceStatus === 'ready' && !errors.length && cell.hasValue)
return {
item: cell.item,
value: cell.value,
status: 'accepted' as const,
issues: errors,
checks: { local: cell.local, review: cell.review },
};
const outcome = synchronous(
fallbackValue({ item: cell.item, issues: errors }, context),
'Answer fallback must be synchronous',
);
if (
!outcome ||
typeof outcome.handled !== 'boolean' ||
(outcome.handled && !('value' in outcome))
)
throw new TypeError('Invalid answer fallback outcome');
return {
item: cell.item,
value: outcome.handled ? outcome.value : undefined,
status: outcome.handled ? ('fallback' as const) : ('blocked' as const),
issues: errors,
checks: { local: cell.local, review: cell.review },
};
}),
}),
routes: [{ id: 'complete', complete: (state) => state.result! }],
},
],
});
return Object.freeze({
/**
* Run one answer batch.
*
* @param request - Input ids the batch must cover and the items to answer; validated before
* any handler runs.
* @param context - Operation context supplying app, signal and diagnostics.
* @returns One accepted, fallback or blocked result per item, in request order.
* @throws TypeError For an invalid batch or handler output, or when the repair budget is
* exhausted without a final result.
*/
async run(
request: { inputIds: readonly string[]; items: readonly AnswerItem<Data>[] },
context: OperationContext<App>,
): Promise<AnswerResult<Data, Value>[]> {
return nativeSubFlowAsync(context, 'answer', 'answer-flow', async () => {
context.signal.throwIfAborted();
validateAnswerBatch(request.inputIds, request.items, maxItems);
const cells = request.items.map((item) => ({
item: Object.freeze({
id: item.id,
data: item.data,
sourceStatus: item.sourceStatus,
inputIds: Object.freeze([...item.inputIds]),
}),
hasValue: false,
local: { status: 'not-run' as const, issues: [] },
review: { status: 'not-run' as const, issues: [] },
knownReviewFailure: false,
}));
return new AgentCoreEngine<AnswerResult<Data, Value>[]>({
maxRounds: maxRepairs + 1,
errors: { exhausted: () => new TypeError('Answer flow exhausted') },
execution: { signal: context.signal, diagnostics: context.diagnostics },
})
.bindWorkflow(workflow, context.app as App)
.run({ cells, pending: [], repairBudget: new AttemptBudget(maxRepairs) });
});
},
});
}