---
title: <GatherAndSynthesize>
description: Parallel gather from multiple sources, then synthesize into a unified result.
---

```ts
// Props
import { GatherAndSynthesize } from "smithers-orchestrator";

type SourceDef = {
  agent: AgentLike;
  prompt?: string;        // optional; defaults to a generated gather prompt
  output?: OutputTarget;
  children?: ReactNode;        // overrides prompt
};

type GatherAndSynthesizeProps = {
  id?: string;                                       // default: "gather-and-synthesize"
  sources: Record<string, SourceDef>;
  synthesizer: AgentLike;
  gatherOutput: OutputTarget;
  synthesisOutput: OutputTarget;
  gatheredResults?: Record<string, unknown> | null;  // typically from ctx.outputMaybe()
  maxConcurrency?: number;                           // default: Infinity
  synthesisPrompt?: string;
  skipIf?: boolean;
  children?: ReactNode;                              // overrides synthesisPrompt
};
```

```tsx
<Workflow name="research">
  <GatherAndSynthesize
    sources={{
      docs: { agent: docsAgent, prompt: "Search the documentation." },
      code: { agent: codeAgent, prompt: "Analyze the codebase." },
      issues: { agent: issueAgent, prompt: "Review open issues." },
    }}
    synthesizer={synthesisAgent}
    gatherOutput={outputs.gathered}
    synthesisOutput={outputs.synthesis}
    gatheredResults={gathered}
  />
</Workflow>
```

## Notes

- Synthesis task auto-receives `needs` for every source, gating it on all gathers.
- Source `children` takes priority over `prompt`.
- When `gatheredResults` is provided, it is folded into the default synthesis prompt.

{/* GENERATED:COMPONENT-SOURCE START (regenerate: pnpm docs:components) */}
## Source

The `<GatherAndSynthesize>` implementation and the files it imports, straight from the package source. This section is generated; edit the source, not this block.

<CodeGroup>
```js GatherAndSynthesize.js
// @smithers-type-exports-begin
/** @typedef {import("./GatherAndSynthesizeProps.ts").GatherAndSynthesizeProps} GatherAndSynthesizeProps */
/** @typedef {import("./SourceDef.ts").SourceDef} SourceDef */
// @smithers-type-exports-end

import React from "react";
import { Sequence } from "./Sequence.js";
import { Parallel } from "./Parallel.js";
import { Task } from "./Task.js";
/**
 * <GatherAndSynthesize> — Parallel data collection from different sources,
 * then synthesis into a unified result.
 *
 * Composes Sequence, Parallel, and Task. First a Parallel block gathers data
 * from each source agent, then a synthesis Task receives all gathered data
 * and produces a combined output.
 * @param {GatherAndSynthesizeProps} props
 */
export function GatherAndSynthesize(props) {
    if (props.skipIf)
        return null;
    const { id, sources, synthesizer, gatherOutput, synthesisOutput, gatheredResults, maxConcurrency, synthesisPrompt, children, } = props;
    const prefix = id ?? "gather-and-synthesize";
    const sourceNames = Object.keys(sources);
    // Step 1: Parallel gather from all sources
    const gatherTasks = sourceNames.map((name) => {
        const source = sources[name];
        const output = source.output ?? gatherOutput;
        const taskId = `${prefix}-gather-${name}`;
        const content = source.children ??
            source.prompt ??
            `Gather data from source "${name}".`;
        return React.createElement(Task, {
            key: taskId,
            id: taskId,
            output,
            agent: source.agent,
            label: `Gather: ${name}`,
            children: content,
        });
    });
    const gatherParallel = React.createElement(Parallel, {
        key: `${prefix}-gather`,
        id: `${prefix}-gather`,
        maxConcurrency,
    }, ...gatherTasks);
    // Step 2: Build needs + deps maps — the synthesis task depends on all gather
    // tasks (`needs` gates it until they are terminal) and resolves each gather's
    // output into its prompt (`deps`; `needs` alone is cache-context only and
    // injects nothing). `depsOptional` lets a failed gather be omitted rather
    // than deferring the synthesis forever.
    const needs = {};
    const deps = {};
    for (const name of sourceNames) {
        needs[name] = `${prefix}-gather-${name}`;
        deps[name] = sources[name].output ?? gatherOutput;
    }
    // Build synthesis prompt from gathered results
    const explicitPrompt = children ?? synthesisPrompt ??
        (gatheredResults
            ? `Synthesize the following gathered data into a unified result:\n\n${Object.entries(gatheredResults)
                .map(([name, data]) => `## ${name}\n${JSON.stringify(data, null, 2)}`)
                .join("\n\n")}`
            : undefined);
    const synthesisContent = explicitPrompt ??
        ((resolved) => {
            const gatheredText = sourceNames
                .map((name) => `## ${name}\n${name in resolved ? JSON.stringify(resolved[name]) : "(no data — this source failed)"}`)
                .join("\n\n");
            return `Synthesize the gathered data from sources: ${sourceNames.join(", ")}.\n\n${gatheredText}`;
        });
    const synthesisTask = React.createElement(Task, {
        key: `${prefix}-synthesize`,
        id: `${prefix}-synthesize`,
        output: synthesisOutput,
        agent: synthesizer,
        needs,
        deps,
        depsOptional: true,
        label: "Synthesize",
        children: synthesisContent,
    });
    return React.createElement(Sequence, null, gatherParallel, synthesisTask);
}
```

```js Sequence.js
import React from "react";
/** @typedef {import("./SequenceProps.ts").SequenceProps} SequenceProps */

/**
 * @param {SequenceProps} props
 */
export function Sequence(props) {
    if (props.skipIf)
        return null;
    // Sequence carries only a display label; pass a sanitized bag (align with
    // the sanitizing structural components) so control props don't leak through.
    // `label` names the phase group in run views (graph, the Claude /workflows
    // mirror) and is preserved in the persisted frame XML.
    const next = props.label === undefined ? {} : { label: props.label };
    return React.createElement("smithers:sequence", next, props.children);
}
```

```js Parallel.js
import React from "react";
/** @typedef {import("./ParallelProps.ts").ParallelProps} ParallelProps */

/**
 * @param {ParallelProps} props
 */
export function Parallel(props) {
    if (props.skipIf)
        return null;
    // Align prop sanitization with other structural components. `label` names
    // the phase group in run views (graph, the Claude /workflows mirror).
    const next = {
        maxConcurrency: props.maxConcurrency,
        subtreeConcurrency: props.subtreeConcurrency,
        id: props.id,
        ...(props.label === undefined ? {} : { label: props.label }),
    };
    return React.createElement("smithers:parallel", next, props.children);
}
```

```js Task.js
// @smithers-type-exports-begin
/**
 * @template D
 * @typedef {import("./InferDeps.ts").InferDeps<D>} InferDeps
 */
/** @typedef {import("./OutputTarget.ts").OutputTarget} OutputTarget */
// @smithers-type-exports-end

import React from "react";
import { renderToStaticMarkup } from "react-dom/server";
import { markdownComponents } from "../markdownComponents.js";
import { zodSchemaToJsonExample } from "../zod-to-example.js";
import { SmithersError } from "@smithers-orchestrator/errors/SmithersError";
import { SmithersContext } from "@smithers-orchestrator/react-reconciler/context";
import { AspectContext } from "../aspects/AspectContext.js";
import { AntigravityAgent } from "@smithers-orchestrator/agents/AntigravityAgent";
import { ClaudeCodeAgent } from "@smithers-orchestrator/agents/ClaudeCodeAgent";
import { GeminiAgent } from "@smithers-orchestrator/agents/GeminiAgent";
import { PiAgent } from "@smithers-orchestrator/agents/PiAgent";
/** @typedef {import("@smithers-orchestrator/agents/AgentLike").AgentLike} AgentLike */
/** @typedef {import("./DepsSpec.ts").DepsSpec} DepsSpec */
/**
 * @template Row, Output, D
 * @typedef {import("./TaskProps.ts").TaskProps<Row, Output, D>} TaskProps
 */

/**
 * Reverse the HTML-entity escaping that renderToStaticMarkup applies to text
 * (& < > " '). Without this, a prompt like `a < b && c` reaches the agent as
 * `a &lt; b &amp;&amp; c`, and injected JSON schema hints (`"key"`) arrive as
 * `&quot;key&quot;`, both of which corrupt the agent-facing text.
 * `&amp;` is decoded last so an escaped literal (`&amp;lt;`, meaning the source
 * text `&lt;`) is not double-decoded into `<`.
 * @param {string} html
 * @returns {string}
 */
function decodeHtmlEntities(html) {
    return html
        .replace(/&lt;/g, "<")
        .replace(/&gt;/g, ">")
        .replace(/&quot;/g, '"')
        .replace(/&#x27;/g, "'")
        .replace(/&#39;/g, "'")
        .replace(/&amp;/g, "&");
}
/**
 * Render a prompt React node to plain markdown text.
 *
 * If the prompt is a React element (e.g. a compiled MDX component), we inject
 * `markdownComponents` via the standard MDX `components` prop so that
 * renderToStaticMarkup outputs clean markdown instead of HTML. The static
 * render entity-escapes all text, so we decode the entities back to literal
 * characters before handing the prompt to the agent.
 * @param {unknown} prompt
 * @returns {string}
 */
export function renderPromptToText(prompt) {
    if (prompt == null)
        return "";
    if (typeof prompt === "string")
        return prompt;
    if (typeof prompt === "number")
        return String(prompt);
    try {
        let element;
        if (React.isValidElement(prompt)) {
            // Inject markdown components into the element so MDX components
            // render fragments instead of HTML tags.
            element = React.cloneElement(prompt, {
                components: markdownComponents,
            });
        }
        else {
            element = React.createElement(React.Fragment, null, prompt);
        }
        return decodeHtmlEntities(renderToStaticMarkup(element))
            .replace(/\n{3,}/g, "\n\n")
            .trim();
    }
    catch (err) {
        const result = String(prompt ?? "");
        if (result === "[object Object]") {
            throw new SmithersError("MDX_PRELOAD_INACTIVE", `MDX prompt could not be rendered — the prompt resolved to [object Object] instead of a React component.\n\n` +
                `This usually means the MDX preload is not active. Common causes:\n` +
                `  • bunfig.toml uses [run] preload instead of top-level preload (the [run] section doesn't apply to dynamic imports)\n` +
                `  • bunfig.toml is not in the current working directory\n` +
                `  • mdxPlugin() is not registered in the preload script\n` +
                `  • The MDX file is imported without a default import (use: import MyPrompt from "./prompt.mdx")\n\n` +
                `Original error: ${err instanceof Error ? err.message : String(err)}`);
        }
        return result;
    }
}
/**
 * @param {unknown} value
 * @returns {value is import("zod").ZodObject<import("zod").ZodRawShape>}
 */
function isZodObject(value) {
    return Boolean(value && typeof value === "object" && "shape" in value);
}
/**
 * @param {DepsSpec | undefined} deps
 * @param {Record<string, string> | undefined} needs
 * @returns {string[] | undefined}
 */
function deriveDepNodeIds(deps, needs) {
    if (!deps)
        return undefined;
    const ids = new Set();
    for (const key of Object.keys(deps)) {
        const nodeId = needs?.[key] ?? key;
        if (nodeId)
            ids.add(nodeId);
    }
    return ids.size > 0 ? [...ids] : undefined;
}
/**
 * @param {string[] | undefined} dependsOn
 * @param {string[] | undefined} depNodeIds
 * @returns {string[] | undefined}
 */
function mergeDependsOn(dependsOn, depNodeIds) {
    const merged = new Set();
    for (const id of dependsOn ?? [])
        merged.add(id);
    for (const id of depNodeIds ?? [])
        merged.add(id);
    return merged.size > 0 ? [...merged] : undefined;
}
/**
 * @param {any} ctx
 * @param {DepsSpec | undefined} deps
 * @param {Record<string, string> | undefined} needs
 * @param {boolean | undefined} depsOptional
 * @returns {Record<string, unknown> | null}
 */
function resolveDeps(ctx, deps, needs, depsOptional) {
    if (!deps)
        return Object.create(null);
    const keys = Object.keys(deps);
    if (keys.length === 0)
        return Object.create(null);
    const resolved = Object.create(null);
    for (const key of keys) {
        const target = deps[key];
        const nodeId = needs?.[key] ?? key;
        const value = ctx.outputMaybe(target, { nodeId });
        if (value === undefined) {
            // Optional deps mode: omit unresolved keys instead of deferring the
            // whole task. Used when the task is already gated by `needs`/`dependsOn`
            // and upstream tasks may legitimately fail (continueOnFail) without
            // producing an output row.
            if (depsOptional)
                continue;
            return null;
        }
        resolved[key] = value;
    }
    return resolved;
}
/**
 * @param {AgentLike} agent
 * @param {string[] | undefined} allowTools
 * @returns {AgentLike}
 */
function applyCliToolAllowlist(agent, allowTools) {
    if (!allowTools) {
        return agent;
    }
    if (agent instanceof ClaudeCodeAgent) {
        const opts = { ...agent.opts };
        if (allowTools.length === 0) {
            return new ClaudeCodeAgent({
                ...opts,
                allowedTools: [],
                tools: "",
            });
        }
        return new ClaudeCodeAgent({
            ...opts,
            allowedTools: [...allowTools],
        });
    }
    if (agent instanceof PiAgent) {
        const opts = { ...agent.opts };
        if (allowTools.length === 0) {
            return new PiAgent({
                ...opts,
                tools: [],
                noTools: true,
            });
        }
        return new PiAgent({
            ...opts,
            tools: [...allowTools],
            noTools: false,
        });
    }
    if (agent instanceof GeminiAgent) {
        const opts = { ...agent.opts };
        return new GeminiAgent({
            ...opts,
            allowedTools: [...allowTools],
        });
    }
    if (agent instanceof AntigravityAgent) {
        const opts = { ...agent.opts };
        return new AntigravityAgent({
            ...opts,
            allowedTools: [...allowTools],
        });
    }
    return agent;
}
/**
 * @param {unknown} ctx
 * @param {string[] | undefined} allowTools
 * @returns {string[] | undefined}
 */
function resolveCliToolAllowlist(ctx, allowTools) {
    if (allowTools !== undefined) {
        return allowTools;
    }
    const cliAgentToolsDefault = ctx && typeof ctx === "object"
        ? ctx.__smithersRuntime?.cliAgentToolsDefault
        : undefined;
    return cliAgentToolsDefault === "explicit-only" ? [] : undefined;
}
/**
 * @template Row, Output, D
 * @param {TaskProps<Row, Output, D>} props
 * @returns {React.ReactElement | null}
 */
export function Task(props) {
    const { children, agent, fallbackAgent, deps, depsOptional, ...rest } = props;
    const taskContext = props.smithersContext ?? SmithersContext;
    const ctx = React.useContext(taskContext);
    const aspectCtx = React.useContext(AspectContext);
    const depNodeIds = deriveDepNodeIds(deps, rest.needs);
    if (deps && !ctx) {
        throw new SmithersError("CONTEXT_OUTSIDE_WORKFLOW", "Task deps require a workflow context. Build the workflow with createSmithers().");
    }
    const resolvedDeps = deps ? resolveDeps(ctx, deps, rest.needs, depsOptional) : undefined;
    if (deps && resolvedDeps == null) {
        // Deps not yet available — component defers until upstream tasks complete.
        // This is normal reactive behavior; the task will re-render once deps are
        // ready. Record the deferral so the engine can distinguish a transient wait
        // from a permanent one: a deferral that survives to quiescence means a
        // dependency that can never resolve (e.g. a deps key that maps to a node id
        // no task produces), which would otherwise be a silent skip.
        ctx?.recordDeferredDep?.(props.id, depNodeIds ?? []);
        return null;
    }
    // Build aspect metadata to attach to the task element so the engine can
    // enforce budgets and track metrics at execution time.
    const aspectMeta = aspectCtx ? buildAspectMeta(aspectCtx) : undefined;
    const agentChain = Array.isArray(agent)
        ? fallbackAgent
            ? [...agent, fallbackAgent]
            : agent
        : agent && fallbackAgent
            ? [agent, fallbackAgent]
            : agent;
    const effectiveAllowTools = resolveCliToolAllowlist(ctx, rest.allowTools);
    const restrictedAgentChain = Array.isArray(agentChain)
        ? agentChain.map((entry) => applyCliToolAllowlist(entry, effectiveAllowTools))
        : agentChain
            ? applyCliToolAllowlist(agentChain, effectiveAllowTools)
            : agentChain;
    const nextDependsOn = mergeDependsOn(rest.dependsOn, depNodeIds);
    const childValue = typeof children === "function" && (agent || deps)
        ? children(resolvedDeps ?? Object.create(null))
        : children;
    if (agent) {
        // Auto-inject `schema` prop into React element children when output is a ZodObject
        let childElement = childValue;
        const schemaForInjection = props.outputSchema ??
            (isZodObject(props.output) ? props.output : undefined);
        if (React.isValidElement(childValue) && schemaForInjection) {
            childElement = React.cloneElement(childValue, {
                schema: zodSchemaToJsonExample(schemaForInjection),
            });
        }
        const prompt = renderPromptToText(childElement);
        return React.createElement("smithers:task", {
            ...rest,
            dependsOn: nextDependsOn,
            waitAsync: rest.async === true,
            agent: restrictedAgentChain,
            __smithersKind: "agent",
            ...aspectMeta,
        }, prompt);
    }
    if (typeof children === "function" && !deps) {
        const nextProps = {
            ...rest,
            dependsOn: nextDependsOn,
            waitAsync: rest.async === true,
            __smithersKind: "compute",
            __smithersComputeFn: children,
            ...aspectMeta,
        };
        return React.createElement("smithers:task", nextProps, null);
    }
    const nextProps = {
        ...rest,
        dependsOn: nextDependsOn,
        waitAsync: rest.async === true,
        __smithersKind: "static",
        __smithersPayload: childValue,
        __payload: childValue,
        ...aspectMeta,
    };
    return React.createElement("smithers:task", nextProps, null);
}
/**
 * Build the __aspects metadata object from the current AspectContext.
 * This is attached to the smithers:task element props so the engine can read
 * budgets and tracking config at execution time.
 * @param {{
 *     tokenBudget?: unknown;
 *     latencySlo?: unknown;
 *     tracking?: unknown;
 *     accumulator?: unknown;
 * }} aspectCtx
 * @returns {{ __aspects: Record<string, unknown> }}
 */
function buildAspectMeta(aspectCtx) {
    return {
        __aspects: {
            tokenBudget: aspectCtx.tokenBudget,
            latencySlo: aspectCtx.latencySlo,
            tracking: aspectCtx.tracking,
            accumulator: aspectCtx.accumulator,
        },
    };
}
```

```ts GatherAndSynthesizeProps.ts
import type React from "react";
import type { AgentLike } from "@smithers-orchestrator/agents/AgentLike";
import type { OutputTarget } from "./OutputTarget.ts";
import type { SourceDef } from "./SourceDef.ts";

export type GatherAndSynthesizeProps = {
	id?: string;
	/** Record mapping source names to source definitions. */
	sources: Record<string, SourceDef>;
	/** Agent that synthesizes gathered data. */
	synthesizer: AgentLike;
	/** Default output schema for each source gather task. */
	gatherOutput: OutputTarget;
	/** Output schema for the synthesis task. */
	synthesisOutput: OutputTarget;
	/** Gathered results keyed by source name. Typically from ctx.outputMaybe(). */
	gatheredResults?: Record<string, unknown> | null;
	/** Max parallel gatherers. */
	maxConcurrency?: number;
	/** Prompt for the synthesis task. If omitted, a default prompt is generated. */
	synthesisPrompt?: string;
	skipIf?: boolean;
	children?: React.ReactNode;
};
```

```ts SourceDef.ts
import type React from "react";
import type { AgentLike } from "@smithers-orchestrator/agents/AgentLike";
import type { OutputTarget } from "./OutputTarget.ts";

export type SourceDef = {
	agent: AgentLike;
	/** Prompt for this source. A string or ReactNode. */
	prompt?: string;
	/** Output schema for this specific source. Overrides `gatherOutput`. */
	output?: OutputTarget;
	children?: React.ReactNode;
};
```
</CodeGroup>
{/* GENERATED:COMPONENT-SOURCE END */}
